Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/31/13
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
326 PM MDT THU AUG 29 2013
.SHORT TERM...(TONIGHT THROUGH FRIDAY NIGHT)
ISSUED AT 242 PM MDT THU AUG 29 2013
SHOWERS AND STORMS DEVELOPED AS EXPECTED AROUND 18Z OVER THE FAVORED
HIGHER TERRAIN AREAS PARTICULARLY THE ABAJOS...SAN JUANS...AND
FLATTOPS. THE 12Z GJT SOUNDING SHOWED PW VALUES OF 0.95 INCHES
WHICH IS MATCHING UP QUITE WELL WITH THE RAP AND THE NAM MODELS.
THE GFS PWATS WERE MUCH LOWER SO THINKING THE GFS IS UNDERPLAYING
THE AMT OF MOISTURE. WITH HIGH PRESSURE OVERHEAD...LIGHT STEERING
FLOW WILL LEAD TO STORMS STAYING RELATIVELY ANCHORED TO THE
TERRAIN WITH LITTLE MOVEMENT. SIMILAR PATTERN TO YESTERDAY...SO
EXPECT MUCH OF THE SAME WITH CONVECTION ENDING SHORTLY AFTER
SUNSET AND SOME STORMS LINGERING TILL MIDNIGHT. BIGGEST CONCERN
FOR THE REST OF THIS AFTERNOON INTO THE EVENING IS ANY STORMS THAT
FORM OVER ALREADY SATURATED AREAS...ESPECIALLY THE SAN JUANS WHERE
FLOODING OCCURRED YESTERDAY IN OURAY AND OVER RED MOUNTAIN PASS.
THE 12Z NAM SEEMS TO BE HANDLING THE MOISTURE BETTER THAN THE GFS SO
LEANING TOWARDS IT FOR FRIDAY. PW VALUES STAY RELATIVELY THE SAME
AT 0.9 INCHES ACROSS MUCH OF WESTERN COLORADO. HOWEVER PWATS
INCREASE SOME OVER SE UTAH...WITH SOME OF THE DEEPER MOISTURE
ASSOCIATED WITH THE INVERTED TROUGH OVER AZ AND SOCAL CREEPING INTO
SE UTAH WHERE PWATS INCREASE TO A LITTLE OVER AN INCH. AN ACTIVE
NORTHERN STREAM CAUSES THE RIDGE TO FLATTEN A LITTLE WHICH LAYS A
55KT JET MAX OVER THE CO-WY BORDER. IN ADDITION TO THIS...850-700MB
STREAMLINES SHOW A LOW LEVEL CONVERGENCE SIGNATURE THAT MOVES
THROUGH SE UTAH AND SW COLORADO FRIDAY AFTERNOON...WITH UPPER LEVEL
DIVERGENCE AS INDICATED IN DIVQ FIELDS. THINKING THAT FRIDAY MAY BE
A LITTLE MORE ACTIVE AND WIDESPREAD IN TERMS OF CONVECTION AS THERE
IS SOME LOW LEVEL AND UPPER LEVEL SUPPORT AND SEVERAL STRONG VORT
MAXES THAT MOVE THROUGH THE FLOW THAT CAN ACT AS A TRIGGER ON THE
MOISTURE. THINK THERE WILL BE ENOUGH SFC HEATING TO GET THINGS
GOING AGAIN AS SKIES BEGIN RELATIVELY CLEAR FRIDAY MORNING.
CONVECTION WILL BEGIN FRIDAY AFTERNOON OVER THE HIGHER TERRAIN WITH
SOME STORMS FORMING OVER THE VALLEYS LATER IN THE DAY AS
DISTURBANCES AND BOUNDARIES INTERACT GIVEN THE ADDITIONAL FORCING.
THINGS SHOULD WIND DOWN AFTER SUNSET AGAIN WITH SOME STORMS
LINGERING UNTIL MIDNIGHT.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 242 PM MDT THU AUG 29 2013
THE UPPER RIDGE STAYS CENTERED OVER THE FOUR CORNERS ON SATURDAY FOR
ANOTHER DAY OF MAINLY AFTERNOON THUNDERSTORMS OVER ELEVATED
LOCATIONS AS SUFFICIENT 0.60 TO 1.00 PWATS REMAIN TRAPPED UNDER
THE RIDGE...WITH THE DRIEST IN NORTHERN AREAS. THINKING THAT THE
NORTHERN UT/CO BORDER WILL SEE SOME BETTER ORGANIZED/LONGER LIVING
STORMS DESPITE THE LOWER BUT STILL GOOD ENOUGH AVAILABLE MOISTURE
SATURDAY AS THE MODELS INDICATE A MODERATE 40-50 KT SPEED MAX AT
250 MB. SE UTAH AND THE SAN JUANS OF COLORADO WILL REMAIN THE MOST
LIKELY LOCATION FOR STORM DEVELOPMENT WITH HEAVY RAIN AS THE
BIGGEST THREAT. IN SOUTHERN AREAS WITH LOW SHEER...CELLS WILL LIKELY BE
SHORT-LIVED BUT COULD CAUSE INTENSE HEAVY RAINFALL IN LOCALIZED
AREAS WITHIN A SHORT PERIOD OF TIME. A FEW OF THESE STORMS MAY
SURVIVE PAST SUNSET BUT OTHERWISE ARE EXPECTED TO DIMINISH AFTER
DARK. A VORT MAX AXIS WILL LIE NW TO SE ACROSS OUR AREA AND HELP
WITH STORM DEVELOPMENT AS WELL.
DISCREPANCY OVER THE WEEKEND ON THE AMOUNT OF MOISTURE WHICH WILL
REMAIN AVAILABLE BUT OVERALL TRENDS ARE SHOWING A SIMILAR
PATTERN.
SUNDAY IS EXPECTED TO BE SLIGHTLY DRIER UP ALONG THE WYOMING
BORDER WITH OUR CWA DUE TO DRY AIR ADVECTION KICKING INTO THE
REGION FROM THE NORTHWEST AND MINIMAL FORCING ALOFT...THEREFORE POPS
ARE AMPLIFIED TO THE SOUTHERN HALF OF OUR AREA. THIS IS NOT
EXPECTED TO LAST LONG AND WILL LIKELY KEEP A SECTION OF THE
NORTHERN REGION RAIN-FREE ON SUNDAY. ELSEWHERE...ESPECIALLY DOWN
IN THE SAN JUANS...ABAJOS...AND LA SALS...THE ATMOSPHERE WILL
REMAIN JUICY AND ALLOW FOR STRONG DIURNAL TSTORMS IN THE AFTERNOON.
MONDAY THROUGH WEDNESDAY...UPPER LEVEL HIGH PRESSURE STAYS POSITIONED
OVER COLORADO THROUGHOUT THE PERIOD. MONSOONAL MOISTURE CONTINUES
TO STREAM AROUND THE WRN PERIPHERY OF THE HIGH ALLOWING FOR DAILY
STORM INITIATION. SHORTWAVE ON TUESDAY SLICING THROUGH THE CENTER
OF THE HIGH PRESSURE WILL ALLOW FOR ENHANCED ACTIVITY ASSUMING
SKIES REMAIN FAIRLY CLEAR DURING THE FIRST HALF OF THE DAY.
THURSDAY COULD GET INTERESTING...BUT THIS FAR OUT THERE IS VERY
LOW CONFIDENCE IN THE LONG TERM MODELS...ESPECIALLY WITH TWO VERY
DIFFERENT SOLUTIONS. THE GFS IS PROGGING A STRONG PACIFIC LOW TO
DROP DOWN INTO THE INTERMOUNTAIN WEST THURSDAY SWIPING WITHIN NEAR
REACH OF THE REGION...FILTERING UNSEASONALLY COOL AIR INTO NORTHERN
BREACHES OF THE CWA. THE EURO KEEPS THIS FEATURE ALONG THE
NORTHERN ROCKIES WITHOUT MUCH INTERACTION WITH COLORADO AND UTAH.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 242 PM MDT THU AUG 29 2013
EXPECT THUNDERSTORMS IN VICINITY OF MOUNTAIN AIRPORTS WITH SOME
LOCALIZED AREAS OF HEAVY RAIN REDUCING VISIBILITY AND CEILINGS TO
IFR/MVFR AT TIMES. GUSTY ERRATIC WINDS CAN BE EXPECTED IN VICINITY
OF ANY STORMS. ACTIVITY IS EXPECTED TO WIND DOWN BY SUNSET OR
SHORTLY THEREAFTER WITH CLEARING SKIES OVERNIGHT. STORMS WILL
DEVELOP OVER THE HIGHER TERRAIN BY 18Z FRIDAY WITH SOME INCREASE
IN COVERAGE AS COMPARED TO TODAY. SOME STORMS MAY IMPACT VALLEY
AIRPORTS FRIDAY AFTERNOON INTO THE EVENING AS STORMS DRIFT OFF
HIGHER TERRAIN. VFR CONDITIONS WILL BE SEEN AT MOST TAF SITES
EXCEPT ASE...MTJ...EGE...AND ANY MOUNTAIN SITES THAT MAY SEE BRIEF
IFR/MVFR IN LOCALLY HEAVY RAIN.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...MDA
LONG TERM...JAM
AVIATION...MDA
AREA FORECAST DISCUSSION
NWS ALBANY NY
745 PM EDT FRI AUG 30 2013
.SYNOPSIS...
A SOUTHWEST FLOW OF WARM AND HUMID AIR...WILL COMBINE WITH A WEAK
LOW PRESSURE SYSTEM SLOWLY TRACKING EASTWARD THROUGH THE SAINT
LAWRENCE VALLEY TO PRODUCE ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS TONIGHT THROUGH SUNDAY. A MUCH STRONGER SYSTEM WILL
BRING A THREAT FOR MORE NUMEROUS SHOWERS AND THUNDERSTORMS ON LABOR
DAY.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 730 PM EDT...A FEW LIGHT SHOWERS WERE WORKING ACROSS OUR
NORTHERN ZONES. OTHERWISE QUIET WITH PLENTY OF HIGH CLOUDS AND
SOMEWHAT MUGGY CONDITIONS WITH DEWPOINTS WELL IN THE 60S.
LOW PRESSURE AND ITS ASSOCIATED FRONTAL BOUNDARY WAS WORKING INTO
THE GREAT LAKES...WITH A LINE OF SHOWERS AND STORMS AHEAD OF IT.
THIS LINE OF STORMS WORKING ACROSS THE GREAT LAKES...ABOUT TO ENTER
INTO LAKE ONTARIO. THERE WAS A SEVERE THUNDERSTORM WATCH ASSOCIATED
WITH THIS LINE BUT AS OF NOW...NO OFFICIAL NWS SEVERE THUNDERSTORM
WARNINGS.
THE HIGH RESOLUTION MODELS HAVE HONED IN ON THESE...AND TEND TO
BRING THEM ACROSS OUR REGION LATE THIS EVENING THROUGH EARLY
MORNING...OVERALL WEAKENING. A THETA E RIDGE LOOKS TO SLIDE SOUTH
BUT WEAKEN. FOR NOW...JUST HAVE CHANCES OF CONVECTION OVERNIGHT WITH
NO SPECIFIC TIMING AS WE WAIT AND SEE WHAT THE COMPLEX WILL
ULTIMATELY DO. SURFACE INSTABILITY WAS CURRENTLY PRESENT TO SUPPORT
CONVECTION FROM THE SURFACE. WHILE THIS INSTABILITY WILL WEAKEN
AFTER SUNSET...THE LATEST RUC13 DOES INDICATE DECREASE SHOWALTER
INDICES (INSTABILITY FROM THE H850 LEVEL) WHICH IMPLIES INCREASING
INSTABILITY ALOFT.
BOTTOM LINE...WE WILL CONTINUE TO MONITOR THIS COMPLEX BUT FOR NOW
CONFIDENCE IS NOT HIGH IT WILL COMPLETELY SURVIVE INTO OUR
REGION.
FOR THE EVENING HOURS...MOST AREAS WILL REMAIN PRECIPITATION FREE.
IT WILL BE MUGGY WITH TEMPERATURES SLOWLY FALLING THROUGH THE 70S
AND A LIGHT TO SOUTH WIND UNDER 10 MPH OR LESS.
OVERNIGHT LOWS WILL BE IN THE 60S. IF THE CLOUDS HOLD...WE MIGHT
HAVE TO RAISE THE OVERNIGHT LOWS A LITTLE ON THE NEXT UPDATE.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
FOR SATURDAY...WEAK LOW PRESSURE AT THE SURFACE AND
ALOFT WILL REMAIN OVER AND NORTH OF THE AREA. WITH WARM AND HUMID
AIRMASS IN PLACE...ONLY A WEAK TRIGGER NEEDED TO START SHOWERS AND
STORMS. MODELS DON`T INDICATE ANY PARTICULAR FORCING FOR THE
SHOWERS/STORMS SO PARTLY SUNNY CONDITIONS WITH A CHANCE OF
AFTERNOON SHOWERS AND THUNDERSTORMS LOOKS GOOD. FOR
SUNDAY...STRONG IMPULSE HAS REACHED THE WESTERN GREAT LAKES. THIS
WORKS TO INDUCE WEAK RIDGING ACROSS THE ALBANY FORECAST AREA.
THIS WEAK RIDGING/HIGH PRESSURE SHOULD KEEP GENERALLY FAIR WEATHER
OVER THE AREA WITH AGAIN A CHANCE FOR SHOWERS AND THUNDERSTORMS...
MAINLY SUNDAY AFTERNOON. BY LATE SUNDAY NIGHT...AN UPPER LEVEL
TROUGH...ASSOCIATED WITH DEEP GREAT LAKES LOW MAY BRING AN
INCREASED THREAT OF SHOWERS AND STORMS.
MAX/MIN TEMPERATURES GENERALLY A MOS BLEND. AREAS OF FOG EXPECTED
EACH MORNING WITH STEAMY AIRMASS IN PLACE.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
THE LONG TERM PERIOD WILL COINCIDE WITH THE BEGINNING OF
METEOROLOGICAL FALL (WHICH STARTS RIGHT ON LABOR DAY). THIS
YEAR...ALMOST ON QUE...OUR WEATHER WILL BECOME MUCH MORE AUTUMNAL
FEELING. HAVE LEANED HEAVILY WITH THE 12Z EUROPEAN MODEL...WHICH IS
FAIRLY CLOSE TO THE HPC GUIDANCE.
ON LABOR DAY ITSELF...WE WILL REMAIN IN A FAIRLY HUMID AND WARM AIR
MASS. A PRE-FRONTAL TROUGH LOOKS TO BE THE INITIAL TRIGGER EARLY ON
LABOR DAY. THE ACTUAL COLD FRONT...A FAIRLY STRONG ONE AT
THAT...WILL MOVE THROUGH OUR REGION LATE IN THE DAY OR MONDAY NIGHT
WITH THE POSSIBILITY OF ADDITIONAL SHOWERS OR THUNDERSTORMS. AT THIS
POINT IT IS VERY HARD TO NAIL DOWN THE EXACT TIMING OF THE
SYSTEMS...OR WHICH ONE WOULD BRING THE BULK OF CONVECTIVE ACTIVITY.
BY TUESDAY...THE 12Z EUROPEAN HAS THE COLD FRONT TO OUR EAST. THERE
IS STILL THE UPPER AIR TROUGH THAT NEEDS TO COME THROUGH TO OUR
NORTH...BUT THERE WILL BE LOT LESS AVAILABLE MOISTURE. THEREFORE WE
DROP POPS TO SLIGHT CHANCES (24 PERCENT BY TUESDAY).
MEANWHILE...H850 TEMPERATURES ARE FORECAST TO COOL FROM ABOUT +16C
TO +17C ON MONDAY...DOWN TO AROUND +9C BY LATE TUESDAY VIA A GUSTY
NORTHWEST BREEZE.
HIGH PRESSURE BUILDS INTO THE REGION BY WEDNESDAY. HOWEVER...IT WILL
BE DISPLACED TO THE SOUTH AND EAST AS YET ANOTHER COOLER COLD FRONT
MOVES THROUGH ON THURSDAY. THIS ONE SHOULD HAVE VERY LITTLE MOISTURE
TO WORK WITH AND SO WE ONLY ASSIGNED SLIGHT POPS FOR THURSDAY.
BEHIND THE SECOND COLD FRONT COMES THE COOLEST AIRMASS SINCE LAST
MAY! EVEN THOUGH FORECAST H850 TEMPS WERE NOT AS COOL ON THIS RUN
COMPARED TO PREVIOUS ONES...TE EUROPEAN MODEL STILL INDICATED THEY
WOULD BE COOLING DOWN TO A RANGE BETWEEN +2C IN OUR NORTHERN
ZONES...TO ABOUT +5C IN OUR SOUTHERN ZONES BY FRIDAY.
TEMPERATURES ON LABOR DAY LOOK TO MAX OUT BETWEEN THE UPPER 70S
ACROSS THE MOUNTAINS...TO 80-85 ACROSS THE MAJORITY OF OUR COUNTY
WARNING AREA. THIS ASSUMES PLENTY OF CLOUD COVER. IF WE WERE TO
RECEIVE MORE BREAKS OF SUNSHINE IT COULD BE A LITTLE WARMER THAN
WHAT WE ARE FORECASTING ALONG WITH AN INCREASED RISK OF STRONGER
THUNDERSTORMS. EITHER WAY...IT WILL BE HUMID.
LOWS MONDAY NIGHT WILL RANGE BETWEEN THE UPPER 50S TO MID 60S.
TUESDAY WILL SEE HIGHS NEAR 80 AROUND POUGHKEEPSIE...MAINLY IN THE
70S ELSEWHERE...EXCEPT UPPER 60S OVER THE HIGHEST MOUNTAIN AREAS. A
BREEZE ON TUESDAY NIGHT MIGHT KEEP TEMPERATURES FROM FALLING MORE
THAN THEY WOULD HAVE OTHERWISE. A LITTLE COOLER TUESDAY NIGHT WITH
LOWS RANGING FROM THE MID 40S TO MID 50S.
WEDNESDAY MIGHT BE THE PICK OF THE WEAK...WITH LOW HUMIDITY...LOTS
OF SUNSHINE AND TEMPERATURES IN THE 70S. WEDNESDAY NIGHT LOWS WILL
BE SIMILAR TO TUESDAY...45 TO 55.
THURSDAY...AS THE H850 TEMPERATURES DIP INTO THE SINGLE
NUMBERS...THERE COULD BE A LOT OF CLOUD COVER AROUND AND THOSE
ISOLATED SHOWERS. HIGH TEMPERATURES THAT DAY MIGHT NOT GET OUT OF
THE 60S FROM ALBANY NORTHWARD...EVEN UPPER 50S ACROSS MUCH OF THE
ADIRONDACK PARK. EVEN FURTHER SOUTH...ONLY LOWER 70S FOR A HIGH
ACROSS THE MID HUDSON VALLEY AND LOWER LITCHFIELD COUNTY.
ENOUGH COLD AIR ADVECTION CLOUDS AND A GRADIENT WOULD BE ONLY THING
PREVENTING TEMPERATURES FROM REACHING FROSTY LEVELS IN OUR
ADIRONDACKS BY THURSDAY NIGHT. WE EXPECT BOTH THE CLOUDS AND A BIT
BREEZE TO HOLD TEMPERATURES UP A LITTLE...AS THEY WILL RANGE FROM
THE LOWER 40S NORTHWEST TO THE LOWER 50S NORTHWEST BY FRIDAY
MORNING.
TEMPERATURES ONCE AGAIN LOOK TO BE HELD MAINLY TO THE 60S ON FRIDAY
DESPITE A GOOD DEAL OF SUNSHINE.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
A LOT OF DEBRIS HIGH AND MID LEVEL CLOUDS SHOULD PREVENT THE
FORMATION OF IFR FOG TONIGHT. HOWEVER...SHOWERS AND EVEN
THUNDERSTORMS MIGHT IMPACT THE TAFS LATER OVERNIGHT.
WE ARE FOLLOWING A LINE OF SHOWERS AND THUNDERSTORMS WELL TO THE
WEST OF THE TERMINALS AS OF 745 PM EDT. WE EXPECT NO PROBLEMS
THROUGH THE EVENING HOURS AND ALL OF OUR SITES LOOK TO REMAIN VFR.
BY 06Z-09Z WE DID INCLUDE VCSH IN ALL THE TAFS ASSUMING SOME SHOWER
ACTIVITY WILL BE AROUND OR NEAR THE SITES. CONFIDENCE WAS TOO LOW TO
INCLUDE THUNDER (EVEN AS A TEMPO) AS THE PROBABILITY OF THESE
DIRECTLY IMPACTING A TAF SITE WAS 25 PERCENT. WE WILL MONITOR INTO
THE EVENING HOURS...AND IF CONFIDENCE INCREASES WE WILL UPDATE THE
TAFS.
ASSUMING NOT A WHOLE LOT OF RAIN AND THE CLOUD COVER...SOME KGFL AND
KPSF MIGHT GO MVFR WITH SOME HAZE AND MVFR CIGS. HOWEVER...FOR
NOW...WE KEPT KALB AND KPOU VFR THROUGHOUT THE NIGHT (ADDING A
LITTLE HAZE BUT ONLY LOWERING VSBY TO 6SM).
LATER ON SATURDAY...THE CONVECTION THREAT LOOKS TO INCREASE AS A
SYSTEM OUT IN THE GREAT LAKES HEADS OUR WAY INCREASING INSTABILITY.
WE DECIDED TO INCLUDE A PROB30 GROUP FOR THUNDER AND MVFR MAINLY
DURING SATURDAY AFTERNOON AS THE THREAT OF A THUNDERSTORM IMPACTING
ANY TAF SITE IS ABOUT 30-49 PERCENT...UP TO HALF OF THE TIME.
THE SURFACE WIND WILL BE LIGHT OR SOUTH UNDER 10KTS
TONIGHT...INCREASING TO NEAR 10KTS LATER ON SATURDAY.
OUTLOOK...
SATURDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
SUNDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
LABOR DAY: HIGH OPERATIONAL IMPACT. LIKELY SHRA...TSRA.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
TUESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
TUESDAY NIGHT AND WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.FIRE WEATHER...
NO FIRE WEATHER ISSUES ARE EXPECTED AT THIS TIME.
A WARM HUMID SOUTHWEST FLOW OF AIR WILL REMAIN IN PLACE THROUGH
MONDAY. THE BEST CHANCE FOR SHOWERS AND THUNDERSTORMS TONIGHT INTO
SATURDAY WITH A WEAK LOW PRESSURE SYSTEM...AND AGAIN ON LABOR DAY AS
STRONGER COLD FRONT PUSHES INTO THE REGION.
MAXIMUM RELATIVE HUMIDITY VALUES RISE TO AROUND 80 TO 100 PERCENT
TONIGHT. RH VALUES WILL ONLY DROP TO BETWEEN 50 AND 70 PERCENT ON
SATURDAY. WINDS TONIGHT WILL BE SOUTHWEST AROUND 5 MPH...BECOMING
LIGHT AND VARIABLE LATER TONIGHT. WINDS ON SATURDAY WILL BECOME
SOUTHERLY AND INCREASE TO AROUND 10 MPH. LIGHT AND VARIABLE WINDS
EXPECTED AGAIN ON SATURDAY NIGHT.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS.
THE NEXT SEVERAL DAYS THROUGH THE LABOR DAY WEEKEND WILL
FEATURE PERIODS OF ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS.
THE BEST CHANCE WILL BE LATE TONIGHT THROUGH SATURDAY AND AGAIN ON
LABOR DAY.
HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE
EXPECTED WITH THUNDERSTORMS. ISOLATED URBAN...SMALL STREAM AND POOR
DRAINAGE FLOODING WILL BE POSSIBLE DURING THE HOLIDAY WEEKEND. SOME
WITHIN BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE SHOWERS
AND STORMS OCCUR.
RAINFALL AMOUNTS WILL BE QUITE VARIABLE DUE TO THE SHOWERY NATURE
OF THE RAIN...WITH SOME LOCATIONS RECEIVING OVER AN INCH OF RAIN
WHILE OTHERS REMAIN DRY.
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...SND/HWJIV
NEAR TERM...SND/HWJIV
SHORT TERM...SND
LONG TERM...HWJIV
AVIATION...HWJIV
FIRE WEATHER...SND
HYDROLOGY...SND/JPV
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
355 AM EDT THU AUG 29 2013
.SYNOPSIS...
LOW PRESSURE JUST OFF THE VIRGINIA COAST WILL MOVE FURTHER OUT TO SEA
TODAY AND TONIGHT. HIGH PRESSURE FROM THE GREAT LAKES REGION WILL
THEN BUILD TOWARD THE AREA AND MOVE OFF THE COAST LATE FRIDAY. A
COLD FRONT IS EXPECTED FROM THE WEST LATE MONDAY BEFORE SLOWLY
MOVING OFF THE COAST LATE TUESDAY NIGHT. HIGH PRESSURE WILL THEN
BUILD INTO THE AREA PROVIDING SEASONABLY COOLER AND LESS HUMID
WEATHER BEGINNING THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLY THIS MORNING...ESTF UPDATE AT 1230 AM CONTINUED WITH THE 1115
PM TUESDAY UPDATE WITH A LITTLE FOG INTO NNJ WITH LESS
SKYCOVER...LIGHT WIND RADIATION COOLING CONDITION IN NJ.
ISOLATED SHOWERS NOW DEVELOPING AND ENTERING BERKS COUNTY TO THE NW
OF KRDG AT 305 AM.
TODAY...LOOKING LIKE A HEAVY RAIN EVENT FOR PTNS SE PA THRU THE
DELMARVA OR SNJ VCNTY KRDG-KPHL-KACY SWWD WITH 21Z/27 SREF PROBS FOR
1 INCH OF RAIN...PWAT BUILDING TO 2.1 INCHES OVER DELMARVA...SLOW -
10 KT - NW-W STEERING CURRENTS AND A SHORT WAVE LIFTING MOISTURE
OVER A SHALLOW CONVERGENCE ZONE NEAR SFC LOW PRES SOMEWHERE OVER E
MD DE. WHILE SVR TSTMS ARE UNLIKELY DUE TO WEAK SHEAR AND TT UNDER
48C...GULLY WASHERS ARE LIKELY WITH KI IN THE MID 30S THIS AFTN
THERE...SWI NEAR -2 AND A NEAR 90F AIRMASS IN THE WARM SECTOR. ML
CAPE WILL BE NEAR 1400J WHERE AND WHEN ITS NOT INITIALLY NOT RAINING
DURING MIDDAY. LIGHT WIND.
THE 00Z/28 RGEM/GGEM LOOK TOO FAR NORTH WITH THEIR FCST QPF
BULLSEYES.
THIS FCST IS A 50 50 BLEND OF THE GFS/NAM ELEMENTS WITH SOME RGEM IN
THE SKYCOVER PTN OF THE FCST. NO SREF INPUT INTO THE POP BUT THE
NEAR TERM PTN OF THIS FCST HAS A RELIANCE ON THE RAP MODEL GUIDANCE
AS SEEN IN THE CONSTANTLY MODEL UPDATED COSPA PRODUCT.
HPCQPF 06Z GRIDS WERE USED...WHICH FORCED THE BOX WX TOOL WORDING OF
HEAVY RAIN POSSIBLE FROM JUST SW OF KPHL S AND WEST TODAY.
FOR THUNDER...USED THE KI 36 (BLENDED 00Z/28 NAM/GFS KI) FOR
THUNDER. THAT KEEPS THUNDER LIMITED INLAND.
WE DID REVIEW THE 00Z/28 SPCWRF FOR TIMING CONVECTION AND ALSO THE
NSSL WRF QPF FCST (TTN-CMAY AXIS WHICH LOOKS TOO FAR NE BUT ISOLATED
3 INCH AMTS).
NO FLASH FLOOD WATCH. HOURLY FFG OVER 2.5 INCHES AND 6 HRLY IS
GENERALLY OVER 4.5 INCHES. MY CONCERN WITH RESPECT TO FFG...CHESTER
COUNTY PA AND NEW CASTLE DE. HOWEVER THAT DOESNT RULE OUT OTHER
COUNTIES. ITS WHERE ANY TSTMS REPEAT OR ARE QSTNRY THIS AFTN.
CONFIDENCE: AVERAGE
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
LEFTOVER CONVECTION DURING THE EVENING...MAINLY TO THE S OF KPHL.
THEN FOG AND STRATUS OVERNIGHT WITH POTENTIAL FOR 1/4MI DENSE FOG IN
PLACES WITH LIGHT WIND AND CLEARING ALOFT LEAVING THE MOIST BL
EXPOSED TO SATURATION. USED THE UPS CROSSOVER TOOL FOR FOG AFTER
06Z.
CONFIDENCE: ABOVE AVERAGE.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
THE H5 RIDGE IS FORECAST TO REMAIN CENTERED NEAR THE FOUR CORNERS
REGION THROUGH MOST OF THE EXTENDED PERIOD AS IT AMPLIFIES BY THE
MIDDLE OF NEXT WEEK. AT THE SAME TIME, THE H5 TROUGH DIGS FURTHER
SOUTH INTO THE EASTERN U.S., THUS PREVENTING ANY PROLONGED PERIOD OF
ABOVE NORMAL TEMPERATURES FOR THE CWA.
AT THE SURFACE, HIGH PRESSURE OVER THE APPALACHIANS EARLY FRIDAY
WILL SLIP OFF THE COAST BY FRIDAY NIGHT, ESTABLISHING A SOUTHERLY
FLOW OVER THE REGION INTO THE EARLY PART OF NEXT WEEK. WARMER THAN
NORMAL TEMPERATURES WILL RESULT FOR SATURDAY THROUGH MONDAY. IN
TERMS OF PRECIPITATION...A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS ON SATURDAY WILL GRADUALLY BECOME MORE LIKELY UNTIL
MONDAY EVENING. THEN A COLD FRONT IS EXPECTED TO SLOWLY MOVE THROUGH
THE REGION MONDAY NIGHT INTO TUESDAY NIGHT, USHERING IN SEASONABLY COOLER
TEMPERATURES FOR THE MID-WEEK PERIOD. RIGHT NOW THE TIMING OF THIS
FRONT, AND THE TIME OF YEAR, WOULD SUGGEST A LOW CHANCE OF SEVERE
WEATHER WITH THIS FRONTAL PASSAGE, BUT THE SITUATION WILL CONTINUE
TO BE MONITORED.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
EARLY THIS MORNING PRIOR TO 12Z...VFR WITH SCT-BKN CLOUDS AOA 5000
FT DEVELOPING. PATCHY MVFR OR IFR FOG POSSIBLE NEW JERSEY WHERE BEST
RADIATIONAL COOLING. SHOWERS DEVELOPING VCNTY KRDG AROUND 0715Z.
LIGHT WIND. CONFIDENCE: AVERAGE
TODAY AFTER 12Z...VFR CIGS OVERSPREADING THE AREA. ANY MORNING
FOG WILL BURN OFF BY 14Z. LIGHT WIND. SHOWERS AND SCT TSTMS
EXPECTED MOST TAF SITES FOR 1-4 HOURS. MOST LIKELY AREA FOR TSTMS
IS VCNTY KRDG-KPHL-KILG-KMIV. THE 06Z TAFS HAVE 3SM MDT SHOWERS
WHERE MY CONFIDENCE IS GREATEST FOR CONVECTION BUT NO MENTION OF
TSTM ATTM DESPITE MY EXPECTATION THAT KRDG/KPHL/KILG WILL RECORD A
TSTM TODAY. CONFIDENCE ON DETAILS: AVERAGE.
TONIGHT...VFR CIGS OR MVFR CONDS IN FOG/SCT SHOWERS AND ISO TSTMS
DIMINISHING EARLY WITH IFR CONDS IN ST/FOG APPEARING LIKELY LATE
FOR MOST TAF SITES. 21Z/27 SREF PROBS FOR THIS IFR OCCURRENCE ARE
ABOUT 40-50 PCT FOCUSED ON KMIV-KPHL AXIS. CONFIDENCE ON CIGS/VSBY
EARLY IS BELOW AVG. CONFIDENCE ON SOME SORT OF IFR IN FOG/STRATUS
LATE .. AFTER 06Z...IS ABOVE AVERAGE.
OUTLOOK...
THURSDAY...MAINLY VFR. THERE IS A CHANCE OF SHOWERS AND THUNDERSTORMS
ON THURSDAY AFTERNOON AROUND KABE AND KRDG.
THURSDAY NIGHT THROUGH FRIDAY NIGHT...MAINLY VFR WITH LATE NIGHT
AND EARLY MORNING VISIBILITY RESTRICTIONS POSSIBLE.
SATURDAY THROUGH SUNDAY...MAINLY VFR WITH LATE NIGHT AND EARLY
MORNING VISIBILITY RESTRICTIONS POSSIBLE. THERE IS A CHANCE OF
MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS.
&&
.MARINE...
NO HEADLINES THROUGH TONIGHT.
ATLC SEAS WILL CONTINUE TO RUN AROUND 2-3 FEET.
LIGHT AND VARIABLE WINDS TREND SOUTHERLY OR SOUTHEASTERLY DURING
THE DAY THEN EVENTUALLY NE TONIGHT.
NE GUSTS 15-20 KT POSSIBLE S NJ AND DE COASTS NEAR DAYBREAK
THURSDAY.
OUTLOOK...
WEAK LOW PRESSURE IS FORECAST TO PASS OFF THE VIRGINIA COAST ON
WEDNESDAY NIGHT. HIGH PRESSURE SHOULD FOLLOW FOR THURSDAY THROUGH
SATURDAY. A WARM FRONT MAY APPROACH FROM THE SOUTHWEST ON SUNDAY.
WIND SPEEDS AND WAVE HEIGHTS ARE EXPECTED TO REMAIN BELOW THE
SMALL CRAFT ADVISORY CRITERIA THROUGH THE PERIOD.
&&
.RIP CURRENTS...
TODAY...CURRENTLY IS OUTLOOKED LOW RISK BUT IF NE WINDS AVG 20 KT
ALONG THE DE COAST...THIS COULD RESULT IN A MDT RISK THERE WITH A
HIGHER THAN MODELED SWELL. SO THERE IS RISK UNCERTAINTY FOR
THURSDAY.
FRIDAY THROUGH MONDAY OUTLOOK AS LOW RISK DAYS.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 11 PM EDT THIS EVENING
FOR ANZ454-455.
&&
$$
SYNOPSIS...MIKETTA
NEAR TERM...DRAG
SHORT TERM...DRAG
LONG TERM...MIKETTA
AVIATION...DRAG/MIKETTA
MARINE...DRAG/MIKETTA
RIP CURRENTS...DRAG
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
343 AM EDT THU AUG 29 2013
.SYNOPSIS...
LOW PRESSURE JUST OFF THE VIRGINIA COAST WILL MOVE FURTHER OUT TO SEA
TODAY AND TONIGHT. HIGH PRESSURE FROM THE GREAT LAKES REGION WILL
THEN BUILD TOWARD THE AREA AND MOVE OFF THE COAST LATE FRIDAY. A
COLD FRONT IS EXPECTED FROM THE WEST LATE MONDAY BEFORE SLOWLY
MOVING OFF THE COAST LATE TUESDAY NIGHT. HIGH PRESSURE WILL THEN
BUILD INTO THE AREA PROVIDING SEASONABLY COOLER AND LESS HUMID
WEATHER BEGINNING THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLY THIS MORNING...ESTF UPDATE AT 1230 AM CONTINUED WITH THE 1115
PM TUESDAY UPDATE WITH A LITTLE FOG INTO NNJ WITH LESS
SKYCOVER...LIGHT WIND RADIATION COOLING CONDITION IN NJ.
ISOLATED SHOWERS NOW DEVELOPING AND ENTERING BERKS COUNTY TO THE NW
OF KRDG AT 305 AM.
TODAY...LOOKING LIKE A HEAVY RAIN EVENT FOR PTNS SE PA THRU THE
DELMARVA OR SNJ VCNTY KRDG-KPHL-KACY SWWD WITH 21Z/27 SREF PROBS FOR
1 INCH OF RAIN...PWAT BUILDING TO 2.1 INCHES OVER DELMARVA...SLOW -
10 KT - NW-W STEERING CURRENTS AND A SHORT WAVE LIFTING MOISTURE
OVER A SHALLOW CONVERGENCE ZONE NEAR SFC LOW PRES SOMEWHERE OVER E
MD DE. WHILE SVR TSTMS ARE UNLIKELY DUE TO WEAK SHEAR AND TT UNDER
48C...GULLY WASHERS ARE LIKELY WITH KI IN THE MID 30S THIS AFTN
THERE...SWI NEAR -2 AND A NEAR 90F AIRMASS IN THE WARM SECTOR. ML
CAPE WILL BE NEAR 1400J WHERE AND WHEN ITS NOT INITIALLY NOT RAINING
DURING MIDDAY. LIGHT WIND.
THE 00Z/28 RGEM/GGEM LOOK TOO FAR NORTH WITH THEIR FCST QPF
BULLSEYES.
THIS FCST IS A 50 50 BLEND OF THE GFS/NAM ELEMENTS WITH SOME RGEM IN
THE SKYCOVER PTN OF THE FCST. NO SREF INPUT INTO THE POP BUT THE
NEAR TERM PTN OF THIS FCST HAS A RELIANCE ON THE RAP MODEL GUIDANCE
AS SEEN IN THE CONSTANTLY MODEL UPDATED COSPA PRODUCT.
HPCQPF 06Z GRIDS WERE USED...WHICH FORCED THE BOX WX TOOL WORDING OF
HEAVY RAIN POSSIBLE FROM JUST SW OF KPHL S AND WEST TODAY.
FOR THUNDER...USED THE KI 36 (BLENDED 00Z/28 NAM/GFS KI) FOR
THUNDER. THAT KEEPS THUNDER LIMITED INLAND.
WE DID REVIEW THE 00Z/28 SPCWRF FOR TIMING CONVECTION AND ALSO THE
NSSL WRF QPF FCST (TTN-CMAY AXIS WHICH LOOKS TOO FAR NE BUT ISOLATED
3 INCH AMTS).
NO FLASH FLOOD WATCH. HOURLY FFG OVER 2.5 INCHES AND 6 HRLY IS
GENERALLY OVER 4.5 INCHES. MY CONCERN WITH RESPECT TO FFG...CHESTER
COUNTY PA AND NEW CASTLE DE. HOWEVER THAT DOESNT RULE OUT OTHER
COUNTIES. ITS WHERE ANY TSTMS REPEAT OR ARE QSTNRY THIS AFTN.
CONFIDENCE: AVERAGE
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
LEFTOVER CONVECTION DURING THE EVENING...MAINLY TO THE S OF KPHL.
THEN FOG AND STRATUS OVERNIGHT WITH POTENTIAL FOR 1/4MI DENSE FOG IN
PLACES WITH LIGHT WIND AND CLEARING ALOFT LEAVING THE MOIST BL
EXPOSED TO SATURATION. USED THE UPS CROSSOVER TOOL FOR FOG AFTER
06Z.
CONFIDENCE: ABOVE AVERAGE.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
THE H5 RIDGE IS FORECAST TO REMAIN CENTERED NEAR THE FOUR CORNERS
REGION THROUGH MOST OF THE EXTENDED PERIOD AS IT AMPLIFIES BY THE
MIDDLE OF NEXT WEEK. AT THE SAME TIME, THE H5 TROUGH DIGS FURTHER
SOUTH INTO THE EASTERN U.S., THUS PREVENTING ANY PROLONGED PERIOD OF
ABOVE NORMAL TEMPERATURES FOR THE CWA.
AT THE SURFACE, HIGH PRESSURE OVER THE APPALACHIANS EARLY FRIDAY
WILL SLIP OFF THE COAST BY FRIDAY NIGHT, ESTABLISHING A SOUTHERLY
FLOW OVER THE REGION INTO THE EARLY PART OF NEXT WEEK. WARMER THAN
NORMAL TEMPERATURES WILL RESULT FOR SATURDAY THROUGH MONDAY. IN
TERMS OF PRECIPITATION...A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS ON SATURDAY WILL GRADUALLY BECOME MORE LIKELY UNTIL
MONDAY EVENING. THEN A COLD FRONT IS EXPECTED TO SLOWLY MOVE THROUGH
THE REGION MONDAY NIGHT INTO TUESDAY NIGHT, USHERING IN SEASONABLY COOLER
TEMPERATURES FOR THE MID-WEEK PERIOD. RIGHT NOW THE TIMING OF THIS
FRONT, AND THE TIME OF YEAR, WOULD SUGGEST A LOW CHANCE OF SEVERE
WEATHER WITH THIS FRONTAL PASSAGE, BUT THE SITUATION WILL CONTINUE
TO BE MONITORED.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
EARLY THIS MORNING PRIOR TO 12Z...VFR WITH SCT-BKN CLOUDS AOA 5000
FT DEVELOPING. PATCHY MVFR OR IFR FOG POSSIBLE NEW JERSEY WHERE BEST
RADIATIONAL COOLING. SHOWERS DEVELOPING VCNTY KRDG AROUND 0715Z.
LIGHT WIND. CONFIDENCE: AVERAGE
TODAY AFTER 12Z...VFR CIGS OVERSPREADING THE AREA. ANY MORNING
FOG WILL BURN OFF BY 14Z. LIGHT WIND. SHOWERS AND SCT TSTMS
EXPECTED MOST TAF SITES FOR 1-4 HOURS. MOST LIKELY AREA FOR TSTMS
IS VCNTY KRDG-KPHL-KILG-KMIV. THE 06Z TAFS HAVE 3SM MDT SHOWERS
WHERE MY CONFIDENCE IS GREATEST FOR CONVECTION BUT NO MENTION OF
TSTM ATTM DESPITE MY EXPECTATION THAT KRDG/KPHL/KILG WILL RECORD A
TSTM TODAY. CONFIDENCE ON DETAILS: AVERAGE.
TONIGHT...VFR CIGS OR MVFR CONDS IN FOG/SCT SHOWERS AND ISO TSTMS
DIMINISHING EARLY WITH IFR CONDS IN ST/FOG APPEARING LIKELY LATE
FOR MOST TAF SITES. 21Z/27 SREF PROBS FOR THIS IFR OCCURRENCE ARE
ABOUT 40-50 PCT FOCUSED ON KMIV-KPHL AXIS. CONFIDENCE ON CIGS/VSBY
EARLY IS BELOW AVG. CONFIDENCE ON SOME SORT OF IFR IN FOG/STRATUS
LATE .. AFTER 06Z...IS ABOVE AVERAGE.
OUTLOOK...
THURSDAY...MAINLY VFR. THERE IS A CHANCE OF SHOWERS AND THUNDERSTORMS
ON THURSDAY AFTERNOON AROUND KABE AND KRDG.
THURSDAY NIGHT THROUGH FRIDAY NIGHT...MAINLY VFR WITH LATE NIGHT
AND EARLY MORNING VISIBILITY RESTRICTIONS POSSIBLE.
SATURDAY THROUGH SUNDAY...MAINLY VFR WITH LATE NIGHT AND EARLY
MORNING VISIBILITY RESTRICTIONS POSSIBLE. THERE IS A CHANCE OF
MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS.
&&
.MARINE...
NO HEADLINES THROUGH TONIGHT.
ATLC SEAS WILL CONTINUE TO RUN AROUND 2-3 FEET.
LIGHT AND VARIABLE WINDS TREND SOUTHERLY OR SOUTHEASTERLY DURING
THE DAY THEN EVENTUALLY NE TONIGHT.
NE GUSTS 15-20 KT POSSIBLE S NJ AND DE COASTS NEAR DAYBREAK
THURSDAY.
OUTLOOK...
WEAK LOW PRESSURE IS FORECAST TO PASS OFF THE VIRGINIA COAST ON
WEDNESDAY NIGHT. HIGH PRESSURE SHOULD FOLLOW FOR THURSDAY THROUGH
SATURDAY. A WARM FRONT MAY APPROACH FROM THE SOUTHWEST ON SUNDAY.
WIND SPEEDS AND WAVE HEIGHTS ARE EXPECTED TO REMAIN BELOW THE
SMALL CRAFT ADVISORY CRITERIA THROUGH THE PERIOD.
&&
.RIP CURRENTS...
TODAY...LOW RISK DOES NOT MEAN NO RISK BUT ITS BEEN A LOW RISK
SUMMER IN OUR FCST AREA SINCE THE ATLANTIC TROPICAL BASIN HAS BEEN
NOTABLY QUIET...DESPITE A FEW NAMED STORMS THAT JUST HAVENT SENT
MUCH SWELL UP OUR WAY.
THURSDAY...CURRENTLY IS OUTLOOKED LOW RISK BUT IF NE WINDS AVG 20
KT ALONG THE DE COAST...THIS COULD RESULT IN A MDT RISK THERE WITH
A HIGHER THAN MODELED SWELL. SO THERE IS RISK UNCERTAINTY FOR THURSDAY.
FRIDAY THROUGH MONDAY OUTLOOK AS LOW RISK DAYS.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 11 PM EDT THIS EVENING
FOR ANZ454-455.
&&
$$
SYNOPSIS...MIKETTA
NEAR TERM...DRAG
SHORT TERM...DRAG
LONG TERM...MIKETTA
AVIATION...DRAG
MARINE...DRAG
RIP CURRENTS...DRAG
AREA FORECAST DISCUSSION
NWS MIAMI FL
308 PM EDT THU AUG 29 2013
.SYNOPSIS...
A WEAK SURFACE HIGH PRESSURE SYSTEM ACROSS THE AREA WILL PERSIST
THROUGH THE WEEKEND AS A LOW PRESSURE TROUGH NORTH OF THE AREA
WEAKENS THROUGH THE PERIOD.
&&
.SHORT TERM...TRHOUGH SATURDAY NIGHT.
UPPER LEVEL LOW ACROSS THE AREA HAS WEAKENED SINCE YESTERDAY
SQUEEZED BETWEEN A STRONG UPPER LEVEL RIDGE ACROSS THE MIDDLE PART
OF THE COUNTRY AND ANOTHER ONE JUST EAST OF THE BAHAMAS. THE LOW
ITSELF IS AT THE TAIL END OF AN UPPER LEVEL TROUGH OFF THE EAST
COAST OF THE US. SHORT RANGE MODEL CONSENSUS INDICATE THIS
FEATURE, AS WEAK AS IT IS, WILL DRIFT SOUTHWEST OVER THE NEXT DAY
OR SO AND THEM MOVE NORTH OF THE AREA BY LATE IN THE WEEKEND. THE
COMBINATION OF DRIER AIR WRAPPED AROUND THIS LOW ALONG WITH UPR
LEVEL CONVERGENCE AND FAIRLY UNIMPRESSIVE THERMODYNAMIC PROFILES
HAVE RESULTED IN SUPPRESSED CONVECTIVE ACTIVITY WITH THIS FEATURE.
NORMALLY IN THE SUMMER TIME THE INTRUSION OF THIS KIND OF FEATURE
WITH COOLER MID LEVEL TEMPS RESULTS IN FAIRLY ACTIVE CONVECTION.
FOR THE REST OF TODAY WE ARE STILL FORECASTING A CHANCE OF
SHOWERS AND STORMS BUT SOMEWHAT LIMITED IN COVERAGE. THERE IS
STILL AN OFF CHANCE OF A STRONG STORM WITH MAIN CONCERN BEING
GUSTY WINDS AND LIGHTNING. THIS IS CONSISTENT WITH BOTH HRRR AND
LOCAL HIGH RES MODELS.
FOR THE REMAINDER OF THE PERIOD THERE IS FAIRLY GOOD CONSENSUS
WITH UPR LEVEL RIDGE ACROSS THE MIDDLE SECTIONS OF THE COUNTRY
RETROGRADING AS AFOREMENTIONED UPPER LEVEL LOW MOVES WEST
SOUTHWEST. ALONG WITH THAT GLOBAL AND HIGH RES MODELS KEEP PWAT
LEVELS AROUND OR BELOW NORMAL. WITH FAIRLY UNIMPRESSIVE
THERMODYNAMIC PROFILES THIS CALLS FOR PERSISTENCE FOR NEXT COUPLE
DAYS WITH ROUTINE DIURNAL CONVECTION IN THE FORM OF SCATTERED
SHOWERS AND STORMS. GIVEN FAIRLY WEAK STORM MOTION VECTORS THERE
ARE ABOUT EQUAL CHANCES OF RAIN ON BOTH SOUTHWEST AND SOUTHEAST
FLORIDA WITH EMPHASIS ACROSS INTERIOR AS SEA AND LAKE BREEZES
REMAIN DOMINANT.
.LONG TERM...SUNDAY THROUGH NEXT THURSDAY
WITH UPPER LEVEL LOW OUT OF THE AREA AND LARGE SCALE PATTERN WITH
RIDGING ON THE WEST, TROUGH ON THE EAST, AND RIDGE OF HIGH PRESSURE
AT LOW LEVELS PERSISTING ACROSS THE AREA A PERSISTENT PATTERN OF
DIURNAL SHOWERS AND THUNDERSTORMS IS FORECAST FOR THE ENTIRE
PERIOD WITH NO HIGHLIGHTS AT THIS TIME. TEMPS WILL REMAIN AROUND
NORMAL EXCEPT OVERNIGHT LOWS SLIGHTLY ABOVE NORMAL.
&&
.AVIATION...
THE EAST COAST SEA BREEZE HAS ALREADY PENETRATED WELL INLAND OF THE
EAST COAST TAF SITES THIS AFTERNOON...WHICH HAS PROVIDED MOSTLY
SUNNY CONDITIONS WITH LIGHT ONSHORE FLOW. THE COMBINATION OF THE
UPPER LOW CENTERED OVERHEAD AND LOW-LEVEL CONVERGENCE SETTING UP
INLAND HAS ALREADY BEGUN TO INITIATE A FEW SHOWERS AND
STORMS...MAINLY OVER THE LAKE AND GLADES COUNTY AREAS. THE LATEST
HRRR RUN CONTINUES TO INDICATE MOSTLY ISOLATED ACTIVITY ACROSS THE
INTERIOR THROUGH THE REMAINDER OF THE AFTERNOON/EVENING PERIODS.
HOWEVER...THE WRF SOLUTIONS STILL HINT AS SOME EAST COAST ACTIVITY
SETTING UP TOWARD PBI THROUGH THE EARLY EVENING PERIOD. DUE TO THIS
UNCERTAINTY...WILL INCLUDE VCTS IN THE PBI TAF THROUGH THE LATE
AFTERNOON/EARLY EVENING PERIODS AND UPDATE AS CONDITIONS EVOLVE.
OTHERWISE...VFR CONDITIONS ARE TO PREVAIL THROUGH THE REMAINDER OF
THE PERIOD. WINDS OVERNIGHT ARE FORECAST TO BECOME CALM OR LIGHT
OFFSHORE ASSOCIATED WITH A LAND BREEZE...THEN ONSHORE THROUGH THE
LATE MORNING/EARLY AFTERNOON HOURS FRIDAY. SLIGHT CHANCE FOR A FEW
MORNING SHOWERS SPREADING ASHORE ALONG THE EAST COAST
...HOWEVER...CONFIDENCE REMAINS TOO LOW TO INSERT IN THIS PACKAGE.
&&
.MARINE...
WITH RIDGE OF HIGH PRESSURE AT THE SURFACE IN CONTROL ACROSS THE
AREA THROUGH THE NEXT 5 DAYS OR SO WINDS ARE FORECAST TO REMAIN
BELOW 10 TO 15 KNOTS RANGE THROUGH THE PERIOD. SEAS ARE NOT
FORECAST TO EXCEED 1-3 FEET ACROSS THE ATLANTIC WATERS AND
GENERALLY LESS THAN 2 FEET ACROSS THE GULF WATERS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 76 90 75 90 / 20 30 20 30
FORT LAUDERDALE 78 91 78 90 / 20 30 20 30
MIAMI 78 92 77 90 / 20 30 20 30
NAPLES 75 91 74 90 / 20 30 20 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...52/PS
AVIATION/RADAR...85/AG
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
1016 AM EDT Thu Aug 29 2013
.NEAR TERM [Through Tonight]...
Looking at our sounding from Tallahassee this morning, there is a
strong capping inversion just above 750mb. Even if the cap can be
broken, there is still a bit of CIN present above the inversion.
Our morning sounding indicates quite a bit of dry air with below
normal PWATs for this time of year, and it appears the dry air
will continue to be advected into our CWA for at least the next
day. Therefore I think we are going to be hard pressed to get any
showers or thunderstorms today. If they are going to occur, the
best chance is along a weak surface trough extending through
central Georgia. Hi-Res model guidance such as the HRRR and WRF
are indicating some shower and thunderstorm activity late this
afternoon around the surface trough. Therefore bumped up PoPs just
a bit for our far eastern and northern GA counties.
This afternoon expect mostly clear skies with high temperatures
reaching the middle 90s with heat indices near 100.
&&
.SHORT TERM [Friday Through Wednesday]...
With the ridge off to the west expected to weaken further and a
weak surface trough moving into the region by Friday, a return to
more wet conditions can be expected by the weekend. Model guidance
continues to be in good agreement about increasing rain chances,
especially across the eastern third of the forecast area by Friday
afternoon. While a washout isn`t expected, rain chances will be
higher than recent days with pops nearing 50 percent along I-75 in
Southern Georgia.
By Saturday, rain chances become more uniform as our region is
located in between the ridge to the west and an upper trough to
the east of the Florida Peninsula. Expect an earlier start to
convection on Saturday morning and lasting into the evening hours
with rain chances around 50 percent, though these could increase
in future forecasts.
Afternoon temperatures will trend lower through the period due to
increased afternoon cloud cover and convective activity.
&&
.LONG TERM [Wednesday Night through Wednesday]...
At the start of the extended period, the forecast area will be
situated in a weakness between a strong upper ridge over the
western states and a weaker ridge over the Bahamas. A weakening
upper low is forecast to be in place across northern Florida. This
pattern should keep PoPs relatively high into early next week with
temperatures near seasonal norms. By late Tuesday into Wednesday,
a deep trough is forecast to develop over the eastern CONUS,
pushing a cold front into the southeastern states. The GFS is
faster and stronger with the front, pushing it off the panhandle
coast by Tuesday afternoon and bringing much drier air into the
region. The ECMWF is slower and weaker with the front, stalling it
across south Georgia or north Florida on Wednesday. The GFS is
often overzealous with fronts this time of year, so prefer the
Euro timing and strength. With this in mind, will keep some PoPs
in for the entire extended.
&&
.AVIATION [Beginning 14Z Thursday]...
[Through 12Z Friday] VFR conditions will continue throughout the
entire period. There is a small chance of thunderstorms for eastern
most terminals this aftn but PoPs remain low enough that this was
left out of the TAF package. After 07z, expect MVFR VSBYS to develop
all sites and MVFR CIGS likely especially at VLD.
&&
.MARINE...
Winds across the marine area are expected to increase to around 15
knots late this evening and continue into Friday in response to an
approaching surface trough. This trough will dissipate on Saturday
leaving our region in light to occasionally moderate southwesterly
flow into next week. No headlines are anticipated.
&&
.FIRE WEATHER...
High pressure and a dry airmass will dominate local weather one
more day but relative humidities will remain above critical levels.
With an approaching cold front, the airmass will begin to moisten up
on Friday with unsettled weather through the weekend. Hazardous fire
weather conditions are not anticipated in the foreseeable future.
&&
.HYDROLOGY...
Flows remain in recession across all basins with the exception of
the Suwannee. Modest rises will continue through this week across
the Middle and Lower Suwannee as routed flows from the
Withlacoochee and Alapaha Rivers progress downstream. From Branford
on through Fowler`s Bluff, the Suwannee will continue moving
toward action stage through the weekend and could near minor flood
stage at Wilcox (US-19) by the middle of next week. For more
information, check out the rivers and lakes tab on our homepage.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 95 73 93 73 92 / 10 10 40 30 50
Panama City 92 76 92 77 89 / 0 10 30 20 40
Dothan 94 73 94 73 92 / 10 10 30 20 50
Albany 95 75 93 73 91 / 20 20 40 30 50
Valdosta 95 72 93 71 90 / 20 20 50 30 50
Cross City 93 72 92 71 89 / 10 10 50 30 50
Apalachicola 90 76 90 77 87 / 0 10 30 20 40
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...Navarro/Harrigan
SHORT TERM...Godsey
LONG TERM...Camp
AVIATION...Block
MARINE...Godsey/Navarro
FIRE WEATHER...Block
HYDROLOGY...Godsey
AREA FORECAST DISCUSSION
NWS MIAMI FL
918 AM EDT THU AUG 29 2013
.UPDATE...
UPPER LEVEL LOW ACROSS THE AREA HAS WEAKENED SINCE YESTERDAY
SQUEEZED BETWEEN A STRONG UPPER LEVEL RIDGE ACROSS THE MIDDLE PART
OF THE COUNTRY AND ANOTHER ONE JUST EAST OF THE BAHAMAS. THE LOW
ITSELF IS AT THE TAIL END OF AN UPPER LEVEL TROUGH OFF THE EAST
COAST OF THE US. ASSOCIATED WITH THE UPPER LEVEL LOW MID LEVEL
TEMPS ACROSS THE AREA ARE COOL (AROUND -8C). WHILE H6-H5 LAPSE
RATES ARE DECENT THAT IS NOT THE CASE ABOVE H5 AND BETWEEN H9 AND
H7. PWAT VALUES ARE RUNNING AROUND 10-20% BELOW NORMAL AS DRIER
AIR MASS HAS WORKED ITS WAY INTO THE REGION ASSOCIATED WITH
AFOREMENTIONED UPPER LEVEL RIDGE TO THE NORTH WHICH IS AN
IMPRESSIVE 597 DM HIGH. EVEN SOME SAHARAN DUST HAS WORKED ITS WAY INTO
THE REGION. ALL OF THIS EXPELS A LESS ACTIVE DIURNAL CONVECTIVE
CYCLE IN TERMS OF COVERAGE BUT STILL A POTENTIAL FOR ISOLATED STRONG
STORMS AS DRY LAYER AT LOW LEVELS COULD INDUCE STRONGER DOWNDRAFTS.
SO MAIN CONCERNS FOR TODAY ARE GUSTY WINDS AND LIGHTNING WITH A
FEW OF THE STORMS. THIS IS CONSISTENT WITH HRRR AND LOCAL HIGH RES
ENS MODELS. SHORT TERM GRIDS HAVE BEEN UPDATED ACCORDINGLY.
&&
.PREV DISCUSSION... /ISSUED 710 AM EDT THU AUG 29 2013/
AVIATION...
THE WINDS WILL REMAIN LIGHT AND VARIABLE THROUGH THE EARLY MORNING
HOURS THEN BECOMING EASTERLY AT 5 TO 10 MPH FOR LATE MORNING AND
AFTERNOON HOURS. THE ONLY EXCEPTION TO THIS IS KAPF TAF SITE WILL
SWING TO A WESTERLY DIRECTION AND INCREASE UP TO 5 TO 10 MPH AFTER
14Z. THE WINDS WILL THEN DECREASE TO LIGHT AND VARIABLE AFTER 23Z
TONIGHT.
THERE COULD BE SOME SHOWERS AROUND THE TAF SITES FROM 14Z UNTIL 23Z
TODAY WITH ANY A FEW THUNDERSTORMS. HOWEVER...THE BEST COVERAGE
SHOULD BE OVER THE INTERIOR AREAS. SO HAVE KEPT THE VCSH IN THE
FORECAST FOR ALL OF THE TAF SITES ACROSS SOUTH FLORIDA. THE CEILING
AND VIS WILL ALSO REMAIN IN THE VFR CONDITIONS...DUE TO THE UNKNOWN
TIMING OF THE SHOWERS AND THUNDERSTORMS.
PREV DISCUSSION... /ISSUED 445 AM EDT THU AUG 29 2013/
DISCUSSION...
A PESKY UPPER LEVEL LOW CONTINUES TO MEANDER OVER SOUTH FLORIDA
TODAY. LOOKING AT WATER VAPOR, THERE IS ONLY MODERATE MOISTURE IN
THE MID AND UPPER LEVELS. PWATS WILL STILL APPROACH 2 INCHES
HOWEVER. LOOKING AT VARIOUS CONVECTIVE PARAMETERS, THERE IS STILL
NOT MUCH TO MENTION. 700MB VORTICITY ADVECTION IS BEST OVER PALM
BEACH COUNTY THIS AFTERNOON, ALTHOUGH, THERE IS ENOUGH TO POSSIBLY
GENERATE SHOWERS ACROSS MUCH OF SOUTH FLORIDA, ESPECIALLY NORTH OF
I75. LAPSE RATES ARE STILL VERY QUESTIONABLE ACROSS THE ENTIRE
AREA, WITH GENERALLY LESS THAN 6.8 FROM 1000MB TO 700MB. MODELS
SOUNDING ARE SHOWING A LITTLE MORE CAPE, BUT ONLY BETWEEN 1300 AND
1600 JOULES. STORM MOTION WILL BE AROUND 15KTS. SO NOT THINKING
ANY HEAVY RAINS FOR A PROLONGED PERIOD TODAY, ALTHOUGH STILL CAN
NOT RULE OUT LOCALIZED URBAN FLOODING WHERE THUNDERSTORMS ARE ABLE
TO FORM, GENERALLY IN THE LAKE REGION. ALSO, LOOKS AS THOUGH THERE
WILL BE CONVERGENCE ALOFT OVER THE MAINLAND, WITH DIVERGENCE
STAYING OVER THE ATLANTIC WATERS OFF SHORE FROM JUPITER. OVERALL,
NOT IMPRESSED WITH CONVECTIVE PARAMETERS TODAY. THINK MAYBE EVEN LESS
THEN YESTERDAY FOR THE SOUTHERN AREAS AND PERHAPS ABOUT THE SAME
FOR THE LAKE REGION.
AS THE LOW DRIFTS TO THE NORTH, CONDITIONS ARE PROGGED TO IMPROVE
THROUGH THE WEEKEND. MODELS ARE INDICATING THE LOW MAY FALL APART
BY THE WEEKEND AND HIGH PRESSURE TRYING TO BUILD IN. PWATS WILL
BEGIN TO DROP, BEING LESS THAN 1.5 INCHES AT TIMES. FOR THE
WEEKEND, THERE IS ALMOST NO 500MB VORT ADVECTION, AND ONLY WEAK
700MB ADVECTION. SO ONLY A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS FOR THE HOLIDAY WEEKEND ALONG THE COAST, AND LOW
CHANCE FOR THE INTERIOR LOCATIONS.
FOR THE BEGINNING OF NEXT WEEK, MODELS ARE DIFFERING ON AN UPPER
LEVEL TROUGH MOVING INTO THE EASTERN UNITED STATES. THE GFS DIGS
THE TROUGH FURTHER SOUTH, AFFECTING THE SOUTH FLORIDA WEATHER. THE
ECMWF IS A LITTLE LESS AGGRESSIVE, KEEPING THE TROUGH WELL NORTH OF
FLORIDA. BUT, GIVEN A LIKELY RETURN TO A MORE NORMAL DIURNAL
PATTERN, HAVE GONE WITH CHANCE POPS FOR MONDAY ACROSS THE ENTIRE
CWA EACH AFTERNOON THROUGH THE END OF THE FORECAST PERIOD.
AVIATION...
THE WEATHER SHOULD REMAIN DRY THROUGH THE MORNING HOURS OVER THE
TAF SITES ALONG WITH LIGHT AND VARIABLE WINDS. THE WINDS WILL THEN
BECOME EASTERLY AT 5 TO 10 KNOTS THIS AFTERNOON ALONG THE EAST
COAST TAF SITES...AND WESTERLY AT KAPF TAF SITE AFTER 14Z
TODAY. SCATTERED SHOWERS SHOULD ALSO DEVELOP AROUND THE TAF SITES
LATE THURSDAY MORNING INTO THIS AFTERNOON. SO HAVE PUT IN VCSH FOR
ALL OF THE TAF SITES FOR THIS AFTERNOON. THERE COULD ALSO BE A FEW
STORMS AROUND THURSDAY AFTERNOON...BUT THE COVERAGE WILL BE FEW
AND FAR. SO WILL KEEP THE THUNDER OUT OF THE TAF SITES AT THIS
TIME.
THE CEILING AND VIS WILL ALSO REMAIN IN THE VFR CONDITIONS OVER
ALL OF THE TAF SITES OF SOUTH FLORIDA...DUE TO THE UNKNOWN TIMING
OF THE SHOWERS AND THUNDERSTORMS FOR LATER TODAY.
MARINE...
AN UPPER LEVEL LOW WILL KEEP A CHANCE OF SHOWERS AND THUNDERSTORMS
IN THE FORECAST TODAY, ESPECIALLY IN THE WATERS OFF PALM BEACH
COUNTY. CONDITIONS WILL IMPROVE THROUGH THE WEEKEND AS THE LOW
WEAKENS. GIVEN THAT WINDS ARE FORECAST TO REMAIN LESS THAN 10 KTS
AND NOT REMAIN IN ANY GIVEN DIRECTION FOR ANY SIGNIFICANT LENGTH
OF TIME, WAVE HEIGHTS WILL ONLY BE 1 TO 2 FEET FOR THE ATLANTIC
WATERS AND CALM TO 1 FOOT FOR THE GULF THROUGH THE WEEKEND.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 89 75 90 77 / 30 30 20 10
FORT LAUDERDALE 88 79 90 79 / 20 20 20 10
MIAMI 90 77 91 78 / 20 20 20 10
NAPLES 88 74 89 75 / 30 20 20 10
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...52/PS
AVIATION/RADAR...85/AG
AREA FORECAST DISCUSSION...UPDATED
NWS MIAMI FL
133 AM EDT THU AUG 29 2013
.AVIATION...
THE WEATHER SHOULD REMAIN DRY THROUGH THE MORNING HOURS OVER THE
TAF SITES ALONG WITH LIGHT AND VARIABLE WINDS. THE WINDS WILL THEN
BECOME EASTERLY AT 5 TO 10 KNOTS THIS AFTERNOON ALONG THE EAST
COAST TAF SITES...AND WESTERLY AT KAPF TAF SITE AFTER 14Z
TODAY. SCATTERED SHOWERS SHOULD ALSO DEVELOP AROUND THE TAF SITES
LATE THURSDAY MORNING INTO THIS AFTERNOON. SO HAVE PUT IN VCSH FOR
ALL OF THE TAF SITES FOR THIS AFTERNOON. THERE COULD ALSO BE A FEW
STORMS AROUND THURSDAY AFTERNOON...BUT THE COVERAGE WILL BE FEW
AND FAR. SO WILL KEEP THE THUNDER OUT OF THE TAF SITES AT THIS
TIME.
THE CEILING AND VIS WILL ALSO REMAIN IN THE VFR CONDITIONS OVER
ALL OF THE TAF SITES OF SOUTH FLORIDA...DUE TO THE UNKNOWN TIMING
OF THE SHOWERS AND THUNDERSTORMS FOR LATER TODAY.
&&
.AVIATION...54/BNB
.PREV DISCUSSION... /ISSUED 847 PM EDT WED AUG 28 2013/
UPDATE...
ONLY CHANGES TO PREVIOUS FORECAST WERE DONE IN THE SHORT TERM...TO
ACCOUNT FOR THE PERSISTENT ACTIVITY ACROSS THE LAKE OKEECHOBEE
AREA AND SURROUNDING COMMUNITIES. LATEST HRRR RUN KEEPS THIS AREA WET
OVERNIGHT...WITH A DECREASE IN COVERAGE AFTER MIDNIGHT. 00Z
SOUNDING SHOWING A SLIGHTLY DRIER AIRMASS AT MID-LEVELS COMPARED
TO YESTERDAYS AND THIS MORNINGS OBSERVATIONS. THIS IS DUE TO THE COMBINATION
OF THE LOW PRESSURE WEAKENING WHILE MOVING NORTHEAST...ALLOWING
FOR A SOUTHWEST FLOW AT MID LEVELS TO BRING DRIER AIR TO THE AREA.
THIS IS CONSISTENT WITH CURRENT MODEL GUIDANCE AND FORECAST TREND.
&&
PREV DISCUSSION... /ISSUED 804 PM EDT WED AUG 28 2013/
AVIATION...
COVERAGE OF SHRAS/TSRAS ASSOCIATED WITH A PERSISTENT H5 LOW HAS
SLOWLY DIMINISHED ACROSS THE AREA EARLY THIS EVENING AND IS NOW
RELEGATED TO THE INTERIOR AND LAKE OKEECHOBEE AREAS. ACTIVITY
SHOULD CONTINUE TO DECREASE IN COVERAGE THROUGH THE EVENING AND
IS NOT EXPECTED TO AFFECT THE TAF SITES. WINDS SHOULD BECOME LIGHT
AND VARIABLE OVERNIGHT BEFORE LIGHT EASTERLY FLOW RETURNS TOMORROW
FOR THE EAST COAST SITES. KAPF SHOULD SEE A GULF BREEZE DEVELOP
DURING THE EARLY AFTERNOON HOURS TOMORROW AND PENETRATE INLAND DUE
TO THE WEAKER EASTERLY FLOW.
&&
PREV DISCUSSION... /ISSUED 224 PM EDT WED AUG 28 2013/
SHORT TERM (TONIGHT-FRIDAY NIGHT)...
THE LATEST MODEL GUIDANCE REMAINS IN DECENT AGREEMENT THROUGH THE
SHORT-TERM PERIOD AND INDICATES THE MID/UPPER LOW CURRENTLY OVERHEAD
THAT HAS LED TO THE ADDITIONAL CLOUD/RAINFALL COVERAGE WILL CONTINUE
TO INFLUENCE THE LOCAL WEATHER THROUGH THE BULK OF THE PERIOD AS IT
GRADUALLY LIFTS NNE OVER THE STATE WITHIN THE WEAKNESS IN THE RIDGE.
MODEL SOUNDINGS ACROSS THE LOCAL AREA SHOW THE DEEP LAYER FLOW
GRADUALLY SHIFTING TOWARD THE WEST TONIGHT THROUGH FRIDAY WITH THE
PRECIPITABLE WATER REMAINING AROUND AND JUST UNDER THE 2" MARK.
DECENT MID-LEVEL LAPSE RATES ACROSS THE AREA THURSDAY COULD RESULT
IN A FEW STRONG STORMS DEVELOPING PROVIDED ANY BREAKS IN THE CLOUD
COVERAGE ALLOWING FOR DESTABILIZATION. THIS COMBINED WITH THE DEEP
LAYER FLOW SHIFTING TO THE SW SHOULD FAVOR MUCH OF THE
AFTERNOON/EVENING DEVELOPMENT OVER THE EASTERN HALF OF THE PENINSULA
AND TOWARD THE EAST COAST EACH DAY. THE MAIN IMPACTS OR CONCERNS
WOULD BE MINOR FLOODING AND GUSTY WINDS IF THIS VERIFIES.
HOWEVER...UNCERTAINTY REMAINS HIGH AS THE LATEST HI-RES MODEL
REFLECTIVITIES FROM THE WRF SHOW MAINLY ISOLATED COVERAGE THROUGH
THIS TIME.
LONG TERM (SATURDAY-WEDNESDAY)...
CONDITIONS ARE EXPECTED TO TREND BACK TOWARD NORMAL THROUGH THE
WEEKEND AS UPPER HEIGHTS BEGIN TO RISE AND THE AFOREMENTIONED
MID/UPPER LOW LIFTS NORTH OF OUR LOCAL AREA. ANOTHER WEAK FRONTAL
BOUNDARY ASSOCIATED WITH AN UPPER TROUGH DEEPENING OVER THE EAST
COAST EARLY NEXT WEEK IS PROGGED TO ENTER THE STATE FROM THE NORTH
TUESDAY THROUGH THE MID-WEEK PERIOD. THESE FEATURES MAY BEGIN TO
SUPPORT ADDITIONAL RAIN CHANCES ACROSS THE STATE BY THE END OF THE
PERIOD IF THE EXTENDED GUIDANCE REMAINS PERSISTENT WITH THIS
SOLUTION.
MARINE...
SCATTERED SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE THROUGH
THURSDAY AS AN UPPER LOW CONTINUES TO INFLUENCE THE LOCAL WEATHER.
MARINERS CAN EXPECT PERIODS WITH REDUCED VISIBILITIES...GUSTY
WINDS AND LOCALLY CHOPPIER CONDITIONS IN AND AROUND THIS ACTIVITY.
HIGH PRESSURE WILL BUILD BACK OVERHEAD THROUGH THE WEEKEND WITH
LIGHT WINDS CONTINUING.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 76 90 77 91 / 40 20 20 20
FORT LAUDERDALE 79 91 79 90 / 30 20 30 20
MIAMI 78 91 78 93 / 30 20 30 20
NAPLES 75 90 75 91 / 20 20 20 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...84/AK
AVIATION/RADAR...59/RM
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
530 PM CDT THU AUG 29 2013
.DISCUSSION...
309 PM CDT
THE MAIN FORECAST CONCERNS WILL BE THE CHANCES AND TIMING OF
THUNDERSTORM ACTIVITY LATE FRIDAY AND FRIDAY NIGHT. TEMPERATURES ARE
ALSO A SIGNIFICANT FOCUS AS IT APPEARS WE WILL BE ON A SEE SAW OVER
THE NEXT SEVERAL DAYS AS SEVERAL COLD FRONTS TAKE AIM ON THE AREA.
THE LAST BIT OF LOW CLOUDS FROM THIS MORNING ARE FINALLY
DISSIPATING JUST WEST OF KPNT EARLY THIS AFTERNOON...SETTING UP
MOSTLY SUNNY SKIES ACROSS THE REGION. HOWEVER...LOW CLOUDS AND FOG
CONTINUE TO FESTER ACROSS THE SOUTHEASTERN TIP OF LAKE
MICHIGAN...JUST OFF THE COOK COUNTY ILLINOIS AND LAKE AND PORTER
COUNTY INDIANA SHORES. ALTHOUGH THIS ACTIVITY HAS REMAINED MAINLY
OVER THE WATERS OF LAKE MICHIGAN THROUGH THE DAY...IT IS POSSIBLY
THAT SOME OF THIS FOG COULD ROLL IN ACROSS THE SHORES EARLY THIS
EVENING. THEREFORE...I ADDED THE MENTION OF AREAS OF FOG FOR THE
IMMEDIATE SHORE LINE. IF THIS FOG DOES MOVE ONSHORE...IT WILL LIKELY
BE DENSE...SO CONDITIONS WILL NEED TO BE MONITORED THIS EVENING. THE
GOOD NEWS IS THAT THE WINDS SHOULD SWITCH OUT OF THE SOUTH OVERNIGHT
TONIGHT...WHICH SHOULD ALLOW ANY FOG TO MOVE BACK OUT OVER THE LAKE
LATER TONIGHT.
THE MAIN WEATHER DISTURBANCE OF INTEREST LATER FRIDAY/FRIDAY
NIGHT...IS CURRENTLY NOTED IN THE WATER VAPOR IMAGERY MOVING ACROSS
NORTH DAKOTA...ALONG THE NORTHERN PERIPHERY OF THE UPPER RIDGE
ENCOMPASSING THE PLAINS. THIS FEATURE IS EXPECTED TO PRODUCE
CONVECTION WELL NORTH OF THE AREA TONIGHT. HOWEVER...A SURFACE COLD
FRONT IS FORECAST TO DROP SOUTHWARD ACROSS WISCONSIN THROUGH THE DAY
ON FRIDAY. TO THE SOUTH OF THIS FRONT...A THERMAL RIDGE WILL SHIFT
EASTWARD ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA....SETTING UP ANOTHER DAY OF HOT AND HUMID CONDITIONS. THIS
SHOULD ALLOW TEMPERATURES TO AGAIN TOP OUT IN THE LOWER TO MIDDLE
90S ACROSS THE AREA ON FRIDAY...WITH HEAT INDICES NEAR 100 DEGREES.
DURING THE LATE AFTERNOON AND EVENING HOURS...THIS COLD FRONT WILL
BEGIN TO MOVE OVER NORTHERN ILLINOIS. IT APPEARS THAT SCATTERED
CONVECTIVE INITIATION WILL OCCUR ACROSS SOUTHERN WISCONSIN BY MID
AFTERNOON...THEN PROGRESS SOUTHEASTWARD ACROSS NORTHERN ILLINOIS
LATER IN THE AFTERNOON AND INTO THE EVENING. IT APPEARS THERE WILL
BE A THREAT FOR SOME STRONG TO SEVERE STORMS WITH THIS ACTIVITY.
HOWEVER...DEEP LAYER SHEAR LOOKS TO REMAIN RATHER MARGINAL (20 TO 30
KT) FOR ORGANIZED CONVECTION. IN SPITE OF THIS...MODEL SOUNDINGS
INDICATE STEEP MID LEVEL LAPS RATES AND PROFILES SUPPORTIVE OF SOME
STRONG WIND GUSTS/MICRO-BURST...SO THE THREAT OF SEVERE STORMS IS NOT
ZERO. IN ADDITION...THE HIGH THETA-E AIR MASS AHEAD OF THE
APPROACHING FRONT...WITH PWATS EXPECTED TO BE AROUND 1.9
INCHES...COULD SUPPORT SOME TORRENTIAL DOWNPOURS IN THE STRONGEST
STORMS. THESE STORMS SHOULD DROP SOUTH AND EASTWARD ACROSS THE AREA
THROUGH THE EVENING. SOME THIS ACTIVITY COULD LINGER OVERNIGHT INTO
EARLY SATURDAY ACROSS MY FAR SOUTHERN COUNTIES.
SOME COOLER AIR ARRIVES ACROSS THE AREA FOR SATURDAY IN THE WAKE OF
THIS FRONTAL ZONE. THIS SHOULD DROP TEMPERATURES BACK INTO THE MID
TO UPPER 80S FOR SATURDAY.
A SECOND SYSTEM LOOKS TO TOP THE RIDGE AXIS ACROSS THE PLAINS...AND
THEN DIG SOUTHEASTWARD OVER THE GREAT LAKES LATE SUNDAY AND INTO
MONDAY. THIS SYSTEM LOOKS TO DRIVE ANOTHER...STRONGER COLD FRONT
ACROSS THE AREA DURING THE DAY ON SUNDAY. THIS APPEARS TO BE ANOTHER
DECENT SHOT FOR SOME SHOWERS AND THUNDERSTORMS INTO SUNDAY EVENING.
ONCE THIS FRONT PASSES BY...MUCH COOLER AND DRIER AIR WILL MOVE
ACROSS THE AREA FOR MONDAY AS A SURFACE HIGH BUILDS EASTWARD ACROSS
THE MID MISSISSIPPI RIVER VALLEY. THIS SHOULD RESULT IN HIGHS BACK
INTO THE 70S FOR MONDAY AND TUESDAY.
TEMPERATURES LOOK TO MODERATE BACK INTO THE 80S BY WEDNESDAY AS THE
THERMAL RIDGE SHIFTS EASTWARD ALONG THE BACK SIDE OF THE SURFACE
HIGH. HOWEVER...THE OVERALL PATTERN LOOKS TO REMAIN DRY ACROSS THE
REGION THROUGH THE MIDDLE OF NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* HIGHER END MVFR VSBY POSSIBLE LATER EVENING AND OVERNIGHT INTO
EARLY FRI MORNING.
* CHANCE OF SHRA/TSRA LATER FRI AFTERNOON INTO EARLY EVENING.
* COLD FRONT DROPPING SE TO ACROSS N CENTRAL AND FAR NE IL BY
31.00Z.
TRS
//DISCUSSION...UPDATED 18Z...
THE LAKE BREEZE BOUNDARY HAS PUSHED THROUGH MDW AND ORD SO
EASTERLY WINDS ARE IN STORE THROUGH EARLY EVENING THERE. BASED ON
NEAR LAKE OBSERVATIONS...SPEEDS SHOULD REMAIN PRIMARILY BELOW
10KT. THERE ARE THEN A FEW FORECAST UNCERTAINTIES THIS EVENING
THROUGH THE OVERNIGHT. FIRST IS THE PERSISTENT AREA OF FOG OVER
THE SOUTHERN TIP OF LAKE MICHIGAN. THE HRRR MODEL WHICH HAS A
DECENT HANDLE ON THE CURRENT POSITION OF THE FOG BANK TRIES TO
OOZE IT A BIT INLAND EARLY THIS EVENING BEFORE WINDS TURN LIGHT
SOUTHERLY AND MOVE IT BACK OVER THE LAKE. IF THE FOG WERE TO MAKE
A BETTER PUSH INLAND THAN EXPECTED...MDW WOULD BE AT RISK BUT GYY
IS MOST LIKELY TO GET CLIPPED SO HAVE INTRODUCED LOW MVFR VSBY AT
GYY EARLY THIS EVENING. IF THE FOG OVERSPREADS GYY...IFR VSBY AND
CIGS ARE CERTAINLY POSSIBLE. SECOND...A MOIST AIR MASS REMAINS IN
PLACE OVER THE AREA AND WITH LIGHT WINDS TONIGHT...MVFR OR LOWER
BR IS POSSIBLE...AND MORE LIKELY TO BE OBSERVED AT RFD/DPA/GYY
THAN ORD AND MDW. GIVEN THE UNCERTAINTY THE LIGHT SOUTH WINDS WILL
HAVE ON HOW LOW VSBY GETS TONIGHT INTO EARLY FRIDAY...KEPT
RFD/DPA/GYY AT MVFR FOR NOW.
WINDS WILL THEN SHIFT SOUTH-SOUTHWEST (200-230 DEGREES) MID-
LATE FRIDAY MORNING AHEAD OF A COLD FRONT AND BECOME GUSTY.
FORECAST SOUNDINGS SUGGEST THE POTENTIAL FOR GUSTS TO AROUND 20 KT
AND SPORADICALLY HIGHER. SCATTERED THUNDERSTORMS ARE POSSIBLE AS
THE FRONT APPROACHES EARLY FRIDAY EVENING. OPTED TO KEEP THE ORD
TAF DRY AS THE BEST CHANCE FOR SHRA/TSRA CURRENTLY APPEARS TO BE
AT OR A BIT AFTER 00Z TOMORROW EVENING.
RC
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* HIGH CONFIDENCE IN ALL OPERATIONALLY SIGNIFICANT ELEMENTS
THROUGH THE NIGHT AND INTO FRI AFTERNOON.
* MEDIUM CONFIDENCE IN SCT TSRA MOVING INTO CHI AREA LATER
AFTERNOON AND EARLY EVENING.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT...CHC SHRA/TSRA. MVFR CIGS PSBL.
SATURDAY...MVFR CIGS PSBL.
SUNDAY...CHC SHRA/TSRA.
MONDAY THROUGH WEDNESDAY...VFR.
JEE
&&
.MARINE...
303 PM CDT
HIGH PRESSURE OVER MICHIGAN WILL CONTINUE TO MOVE SOUTHEASTWARD
TONIGHT WHILE LOW PRESSURE MOVES FROM MINNESOTA TO LAKE SUPERIOR.
THE PRESSURE GRADIENT WILL BUILD ACROSS NORTHERN SECTIONS OF THE
LAKE OVERNIGHT AND SPREAD DOWN THE LAKE FRIDAY MORNING. THIS WILL
SUPPORT AND INCREASE IN SOUTHWESTERLY WINDS ACROSS THE LAKE THROUGH
FRIDAY MORNING. ANOTHER CONCERN LINGERING FOG OF SOUTHERN LAKE
MICHIGAN THIS AFTERNOON. HAVE ISSUED A DENSE FOG ADVISORY FOR MOST
OF THE IL/IN NEARSHORE WATERS AND THE FAR SOUTHWEST CORNER OF THE
OPEN WATERS. WITH WINDS REMAINING LIGHT ACROSS THE FAR SOUTH INTO
TONIGHT SO THIS FOG MAY CONTINUE THOUGH IT MAY LIFT TO LOW STRATUS
AROUND THE EDGES INTO EARLY EVENING. LOW CONFIDENCE IN HOW IT
EVOLVES BUT THE PRESSURE GRADIENT ORGANIZES SOMEWHAT THIS EVENING
SO A STEADIER...BUT STILL LIGHT...SOUTH WIND SHOULD RESULT AND MAY
HELP ANY REMAINING VSBY REDUCTIONS TO IMPROVE. A COLD FRONT WILL
DROP SOUTHWARD DOWN THE LAKE FRIDAY AND FRIDAY EVENING TURNING
WINDS NORTHERLY. WEAK HIGH PRESSURE WILL THEN BUILD IN SATURDAY
BRINGING WEAKENING WINDS INTO SATURDAY EVENING. STRONG LOW
PRESSURE WILL THEN MOVE FROM NORTHERN MINNESOTA/WESTERN ONTARIO
ACROSS LAKE SUPERIOR SUNDAY SENDING A COLD FRONT EASTWARD ACROSS
THE LAKE SUNDAY AFTERNOON OR EVENING. STRONG HIGH PRESSURE WILL
MOVE EAST ACROSS THE PLAINS AND MID AND UPPER MISSISSIPPI RIVER
VALLEY MONDAY. THERE WILL BE A STRONG PRESSURE GRADIENT BETWEEN
THE TWO SYSTEMS WITH A PUSH OF COOLER AIR SPREADING IN BEHIND THE
FRONT SO WINDS WILL BE INCREASING AS THEY TURN NORTHWEST THEN MORE
NORTHERLY. THE HIGH WILL THEN MOVE ACROSS THE LAKE
TUESDAY/WEDNESDAY BRINGING LIGHT AND VARIABLE WINDS.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...DENSE FOG ADVISORY...LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ779
UNTIL 10 PM THURSDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
310 PM CDT THU AUG 29 2013
.DISCUSSION...
309 PM CDT
THE MAIN FORECAST CONCERNS WILL BE THE CHANCES AND TIMING OF
THUNDERSTORM ACTIVITY LATE FRIDAY AND FRIDAY NIGHT. TEMPERATURES ARE
ALSO A SIGNIFICANT FOCUS AS IT APPEARS WE WILL BE ON A SEE SAW OVER
THE NEXT SEVERAL DAYS AS SEVERAL COLD FRONTS TAKE AIM ON THE AREA.
THE LAST BIT OF LOW CLOUDS FROM THIS MORNING ARE FINALLY
DISSIPATING JUST WEST OF KPNT EARLY THIS AFTERNOON...SETTING UP
MOSTLY SUNNY SKIES ACROSS THE REGION. HOWEVER...LOW CLOUDS AND FOG
CONTINUE TO FESTER ACROSS THE SOUTHEASTERN TIP OF LAKE
MICHIGAN...JUST OFF THE COOK COUNTY ILLINOIS AND LAKE AND PORTER
COUNTY INDIANA SHORES. ALTHOUGH THIS ACTIVITY HAS REMAINED MAINLY
OVER THE WATERS OF LAKE MICHIGAN THROUGH THE DAY...IT IS POSSIBLY
THAT SOME OF THIS FOG COULD ROLL IN ACROSS THE SHORES EARLY THIS
EVENING. THEREFORE...I ADDED THE MENTION OF AREAS OF FOG FOR THE
IMMEDIATE SHORE LINE. IF THIS FOG DOES MOVE ONSHORE...IT WILL LIKELY
BE DENSE...SO CONDITIONS WILL NEED TO BE MONITORED THIS EVENING. THE
GOOD NEWS IS THAT THE WINDS SHOULD SWITCH OUT OF THE SOUTH OVERNIGHT
TONIGHT...WHICH SHOULD ALLOW ANY FOG TO MOVE BACK OUT OVER THE LAKE
LATER TONIGHT.
THE MAIN WEATHER DISTURBANCE OF INTEREST LATER FRIDAY/FRIDAY
NIGHT...IS CURRENTLY NOTED IN THE WATER VAPOR IMAGERY MOVING ACROSS
NORTH DAKOTA...ALONG THE NORTHERN PERIPHERY OF THE UPPER RIDGE
ENCOMPASSING THE PLAINS. THIS FEATURE IS EXPECTED TO PRODUCE
CONVECTION WELL NORTH OF THE AREA TONIGHT. HOWEVER...A SURFACE COLD
FRONT IS FORECAST TO DROP SOUTHWARD ACROSS WISCONSIN THROUGH THE DAY
ON FRIDAY. TO THE SOUTH OF THIS FRONT...A THERMAL RIDGE WILL SHIFT
EASTWARD ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA....SETTING UP ANOTHER DAY OF HOT AND HUMID CONDITIONS. THIS
SHOULD ALLOW TEMPERATURES TO AGAIN TOP OUT IN THE LOWER TO MIDDLE
90S ACROSS THE AREA ON FRIDAY...WITH HEAT INDICIES NEAR 100 DEGREES.
DURING THE LATE AFTERNOON AND EVENING HOURS...THIS COLD FRONT WILL
BEGIN TO MOVE OVER NORTHERN ILLINOIS. IT APPEARS THAT SCATTERED
CONVECTIVE INITIATION WILL OCCUR ACROSS SOUTHERN WISCONSIN BY MID
AFTERNOON...THEN PROGRESS SOUTHEASTWARD ACROSS NORTHERN ILLINOIS
LATER IN THE AFTERNOON AND INTO THE EVENING. IT APPEARS THERE WILL
BE A THREAT FOR SOME STRONG TO SEVERE STORMS WITH THIS ACTIVITY.
HOWEVER...DEEP LAYER SHEAR LOOKS TO REMAIN RATHER MARGINAL (20 TO 30
KT) FOR ORGANIZED CONVECTION. IN SPITE OF THIS...MODEL SOUNDINGS
INDICATE STEEP MID LEVEL LAPS RATES AND PROFILES SUPPORTIVE OF SOME
STRONG WIND GUSTS/MICROBURST...SO THE THREAT OF SEVERE STORMS IS NOT
ZERO. IN ADDITION...THE HIGH THETA-E AIRMASS AHEAD OF THE
APPROACHING FRONT...WITH PWATS EXPECTED TO BE AROUND 1.9
INCHES...COULD SUPPORT SOME TORRENTIAL DOWNPOURS IN THE STRONGEST
STORMS. THESE STORMS SHOULD DROP SOUTH AND EASTWARD ACROSS THE AREA
THROUGH THE EVENING. SOME THIS ACTIVITY COULD LINGER OVERNIGHT INTO
EARLY SATURDAY ACROSS MY FAR SOUTHERN COUNTIES.
SOME COOLER AIR ARRIVES ACROSS THE AREA FOR SATURDAY IN THE WAKE OF
THIS FRONTAL ZONE. THIS SHOULD DROP TEMPERATURES BACK INTO THE MID
TO UPPER 80S FOR SATURDAY.
A SECOND SYSTEM LOOKS TO TOP THE RIDGE AXIS ACROSS THE PLAINS...AND
THEN DIG SOUTHEASTWARD OVER THE GREAT LAKES LATE SUNDAY AND INTO
MONDAY. THIS SYSTEM LOOKS TO DRIVE ANOTHER...STRONGER COLD FRONT
ACROSS THE AREA DURING THE DAY ON SUNDAY. THIS APPEARS TO BE ANOTHER
DECENT SHOT FOR SOME SHOWERS AND THUNDERSTORMS INTO SUNDAY EVENING.
ONCE THIS FRONT PASSES BY...MUCH COOLER AND DRIER AIR WILL MOVE
ACROSS THE AREA FOR MONDAY AS A SURFACE HIGH BUILDS EASTWARD ACROSS
THE MID MISSISSIPPI RIVER VALLEY. THIS SHOULD RESULT IN HIGHS BACK
INTO THE 70S FOR MONDAY AND TUESDAY.
TEMPERATURES LOOK TO MODERATE BACK INTO THE 80S BY WEDNESDAY AS THE
THERMAL RIDGE SHIFTS EASTWARD ALONG THE BACK SIDE OF THE SURFACE
HIGH. HOWEVER...THE OVERALL PATTERN LOOKS TO REMAIN DRY ACROSS THE
REGION THROUGH THE MIDDLE OF NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* EAST WINDS JUST UNDER 10 KT THROUGH EARLY EVENING.
* MVFR VSBY POSSIBLE TONIGHT INTO EARLY FRIDAY.
* SOUTH-SOUTHWEST WINDS OF 200-230 DEG DEVELOP MID-LATE FRIDAY
MORNING WITH GUSTS TO AROUND 20 KT POSSIBLE.
* SHRA/TSRA POSSIBLE LATE AFTERNOON THROUGH EARLY EVE FRIDAY.
RC
//DISCUSSION...UPDATED 18Z...
THE LAKE BREEZE BOUNDARY HAS PUSHED THROUGH MDW AND ORD SO
EASTERLY WINDS ARE IN STORE THROUGH EARLY EVENING THERE. BASED ON
NEAR LAKE OBSERVATIONS...SPEEDS SHOULD REMAIN PRIMARILY BELOW
10KT. THERE ARE THEN A FEW FORECAST UNCERTAINTIES THIS EVENING
THROUGH THE OVERNIGHT. FIRST IS THE PERSISTENT AREA OF FOG OVER
THE SOUTHERN TIP OF LAKE MICHIGAN. THE HRRR MODEL WHICH HAS A
DECENT HANDLE ON THE CURRENT POSITION OF THE FOG BANK TRIES TO
OOZE IT A BIT INLAND EARLY THIS EVENING BEFORE WINDS TURN LIGHT
SOUTHERLY AND MOVE IT BACK OVER THE LAKE. IF THE FOG WERE TO MAKE
A BETTER PUSH INLAND THAN EXPECTED...MDW WOULD BE AT RISK BUT GYY
IS MOST LIKELY TO GET CLIPPED SO HAVE INTRODUCED LOW MVFR VSBY AT
GYY EARLY THIS EVENING. IF THE FOG OVERSPREADS GYY...IFR VSBY AND
CIGS ARE CERTAINLY POSSIBLE. SECOND...A MOIST AIR MASS REMAINS IN
PLACE OVER THE AREA AND WITH LIGHT WINDS TONIGHT...MVFR OR LOWER
BR IS POSSIBLE...AND MORE LIKELY TO BE OBSERVED AT RFD/DPA/GYY
THAN ORD AND MDW. GIVEN THE UNCERTAINTY THE LIGHT SOUTH WINDS WILL
HAVE ON HOW LOW VSBY GETS TONIGHT INTO EARLY FRIDAY...KEPT
RFD/DPA/GYY AT MVFR FOR NOW.
WINDS WILL THEN SHIFT SOUTH-SOUTHWEST (200-230 DEGREES) MID-
LATE FRIDAY MORNING AHEAD OF A COLD FRONT AND BECOME GUSTY.
FORECAST SOUNDINGS SUGGEST THE POTENTIAL FOR GUSTS TO AROUND 20 KT
AND SPORADICALLY HIGHER. SCATTERED THUNDERSTORMS ARE POSSIBLE AS
THE FRONT APPROACHES EARLY FRIDAY EVENING. OPTED TO KEEP THE ORD
TAF DRY AS THE BEST CHANCE FOR SHRA/TSRA CURRENTLY APPEARS TO BE
AT OR A BIT AFTER 00Z TOMORROW EVENING.
RC
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN EAST WINDS REMAINING PRIMARILY BELOW 10 KT
THROUGH EARLY THIS EVENING.
* MEDIUM CONFIDENCE THAT VSBY WILL REMAIN VFR OVERNIGHT THROUGH
EARLY FRIDAY.
* MEDIUM-HIGH CONFIDENCE IN WIND SPEED AND DIRECTION MID-LATE
FRIDAY MORNING THROUGH FRIDAY AFTERNOON.
* MEDIUM CONFIDENCE THAT BEST POTENTIAL FOR SHRA/TSRA IS AT OR A
BIT AFTER 00Z FRIDAY EVENING.
RC
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT...CHC SHRA/TSRA. MVFR CIGS PSBL.
SATURDAY...MVFR CIGS PSBL.
SUNDAY...CHC SHRA/TSRA.
MONDAY THROUGH WEDNESDAY...VFR.
JEE
&&
.MARINE...
303 PM CDT
HIGH PRESSURE OVER MICHIGAN WILL CONTINUE TO MOVE SOUTHEASTWARD
TONIGHT WHILE LOW PRESSURE MOVES FROM MINNESOTA TO LAKE SUPERIOR.
THE PRESSURE GRADIENT WILL BUILD ACROSS NORTHERN SECTIONS OF THE
LAKE OVERNIGHT AND SPREAD DOWN THE LAKE FRIDAY MORNING. THIS WILL
SUPPORT AND INCREASE IN SOUTHWESTERLY WINDS ACROSS THE LAKE THROUGH
FRIDAY MORNING. ANOTHER CONCERN LINGERING FOG OF SOUTHERN LAKE
MICHIGAN THIS AFTERNOON. HAVE ISSUED A DENSE FOG ADVISORY FOR MOST
OF THE IL/IN NEARSHORE WATERS AND THE FAR SOUTHWEST CORNER OF THE
OPEN WATERS. WITH WINDS REMAINING LIGHT ACROSS THE FAR SOUTH INTO
TONIGHT SO THIS FOG MAY CONTINUE THOUGH IT MAY LIFT TO LOW STRATUS
AROUND THE EDGES INTO EARLY EVENING. LOW CONFIDENCE IN HOW IT
EVOLVES BUT THE PRESSURE GRADIENT ORGANIZES SOMEWHAT THIS EVENING
SO A STEADIER...BUT STILL LIGHT...SOUTH WIND SHOULD RESULT AND MAY
HELP ANY REMAINING VSBY REDUCTIONS TO IMPROVE. A COLD FRONT WILL
DROP SOUTHWARD DOWN THE LAKE FRIDAY AND FRIDAY EVENING TURNING
WINDS NORTHERLY. WEAK HIGH PRESSURE WILL THEN BUILD IN SATURDAY
BRINGING WEAKENING WINDS INTO SATURDAY EVENING. STRONG LOW
PRESSURE WILL THEN MOVE FROM NORTHERN MINNESOTA/WESTERN ONTARIO
ACROSS LAKE SUPERIOR SUNDAY SENDING A COLD FRONT EASTWARD ACROSS
THE LAKE SUNDAY AFTERNOON OR EVENING. STRONG HIGH PRESSURE WILL
MOVE EAST ACROSS THE PLAINS AND MID AND UPPER MISSISSIPPI RIVER
VALLEY MONDAY. THERE WILL BE A STRONG PRESSURE GRADIENT BETWEEN
THE TWO SYSTEMS WITH A PUSH OF COOLER AIR SPREADING IN BEHIND THE
FRONT SO WINDS WILL BE INCREASING AS THEY TURN NORTHWEST THEN MORE
NORTHERLY. THE HIGH WILL THEN MOVE ACROSS THE LAKE
TUESDAY/WEDNESDAY BRINGING LIGHT AND VARIABLE WINDS.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...DENSE FOG ADVISORY...LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ779
UNTIL 10 PM THURSDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
306 PM CDT THU AUG 29 2013
.DISCUSSION...
324 AM CDT
THE FORECAST CHALLENGES INCLUDE FOG IN THE NEAR TERM...THEN
INCREASING TEMPS AND THUNDERSTORM CHANCES FRIDAY...FOLLOWED BY A
COOL DOWN AND RETURN TO MORE SEASONABLE CONDITIONS TOWARD END OF THE
HOLIDAY WEEKEND.
GOES IMAGERY THIS MORNING SHOWS EXPANDING AREA OF STRATUS ACROSS
MUCH OF THE FORECAST AREA WITH SURFACE OBS AND WEBCAMS SHOWING A
SMATTERING OF DENSE FOG HERE AND THERE. ALL INDICATIONS ARE THAT THE
STRATUS IS THIN AND SHOULD BURN OFF QUICKLY THIS MORNING EXPECT NEAR
THE LAKE FRONT WHERE MARINE STRATUS AND POSSIBLY EVEN SOME FOG COULD
HOLD ON INTO THE AFTERNOON. ANOTHER COMPARATIVELY COOL DAY NEAR THE
LAKE WITH 70S RANGING QUICKLY UPWARD TO 80S INLAND JUST A FEW MILES
WITH UPPER 80S TO NEAR 90 EXPECTED SOUTHERN AND WESTERN PORTIONS OF
THE CWA.
SURFACE BOUNDARY STALLED OUT FROM SOUTHERN MINNESOTA TO CENTRAL
ILLINOIS WILL DISSIPATE THIS AFTERNOON INTO TONIGHT AS BROAD
SOUTHERLY FLOW DEVELOPS WITH SFC LOW TRACKING EAST INTO THE UPPER
GREAT LAKES FRIDAY MORNING. TRAILING COLD FRONT ALONG WITH GLANCING
BLOW FROM THE ASSOCIATED SHORTWAVE PASSING TO OUR NORTHEAST COULD
RESULT IN CONVECTION DEVELOPING FRIDAY AFTERNOON OVER SOUTHERN WI OR
POSSIBLY FAR NORTHERN ILLINOIS. HOT AND HUMID CONDITIONS WILL RESULT
IN MODERATE TO STRONG INSTABILITY ACROSS THE AREA THOUGH CONFIDENCE
IS LOW IN THE MAGNITUDE OF THE DEEP LAYER SHEAR. DEPENDING ON THE
TIMING AND TRACK OF THE VORT AND ASSOCIATED STRONGER MID LEVEL FLOW
SHEAR COULD BE WEAK TO POSSIBLY ON THE HIGHER END OF MODERATE. GIVEN
THE UNCERTAINTIES ABOUT POSSIBLE CONVECTIVE INITIATION AND MAGNITUDE
OF SHEAR IF STORMS DO FORM...CONFIDENCE IN SEVERE THREAT ISN`T HIGH
BUT WORTH KEEPING AN EYE ON SINCE NORTHWEST FLOWS CAN BE FULL OF
SURPRISES. MODELS ALL AGREE IN A RESURGENCE OF THE MORE INTENSE HEAT
AND HUMIDITY WITH HIGHS IN THE LOW TO MID 90S AND HEAT INDICES
POTENTIALLY GETTING UP CLOSE TO OR PERHAPS A BIT OVER 100 FRIDAY
AFTERNOON.
WEAK COLD FRONT LOOKS TO PASS THROUGH THE AREA FRIDAY NIGHT
RESULTING IN A WIND SHIFT TO THE NORTH AND SLIGHTLY COOLER AIR
ARRIVING SATURDAY...EXCEPT NEAR THE LAKE WHERE THE COOL DOWN WILL BE
MORE PRONOUNCED WITH THE FLOW OFF THE LAKE.
MUCH STRONGER SHORTWAVE WILL CREST THE TOP OF THE SLOWLY
RETROGRADING CENTRAL CONUS RIDGE SATURDAY BEFORE DIGGING SOUTHEAST
INTO THE GREAT LAKES REGION SUNDAY. STRONGER COLD FRONT WITH A MORE
ROBUST PUSH OF COOLER AND LESS HUMID AIR WILL MOVE THROUGH LATER
SUNDAY. ITS QUESTIONABLE HOW MUCH MOISTURE/INSTABILITY WILL BE
AROUND FOR CONVECTION WITH THIS SECOND FRONT IN THE WAKE OF THE
FIRST FROPA. HAVE MAINTAINED JUST CHANCE POPS FOR NOW WITH SOME
GUIDANCE STILL SUGGESTING A DRY SECONDARY FROPA AND GIVEN THE TRENDS
THIS SUMMER...DRIER IS USUALLY THE WAY TO GO.
DRY NORTHWEST FLOW THEN FORECAST TO SET UP OVER THE AREA THROUGH
MUCH OF NEXT WEEK. INITIAL PUSH OF COOLER AIR MONDAY INTO TUESDAY
WILL BE REPLACED WITH QUICK WARM UP MIDWEEK FOLLOWED BY ANOTHER
NORTHWEST FLOW COLD FRONT AND PUSH OF COOLER AIR. ALL IN ALL LOOKS
LIKE PRETTY TYPICAL EARLY METEOROLOGICAL FALL TYPE WEATHER.
IZZI
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* EAST WINDS JUST UNDER 10 KT THROUGH EARLY EVENING.
* MVFR VSBY POSSIBLE TONIGHT INTO EARLY FRIDAY.
* SOUTH-SOUTHWEST WINDS OF 200-230 DEG DEVELOP MID-LATE FRIDAY
MORNING WITH GUSTS TO AROUND 20 KT POSSIBLE.
* SHRA/TSRA POSSIBLE LATE AFTERNOON THROUGH EARLY EVE FRIDAY.
RC
//DISCUSSION...UPDATED 18Z...
THE LAKE BREEZE BOUNDARY HAS PUSHED THROUGH MDW AND ORD SO
EASTERLY WINDS ARE IN STORE THROUGH EARLY EVENING THERE. BASED ON
NEAR LAKE OBSERVATIONS...SPEEDS SHOULD REMAIN PRIMARILY BELOW
10KT. THERE ARE THEN A FEW FORECAST UNCERTAINTIES THIS EVENING
THROUGH THE OVERNIGHT. FIRST IS THE PERSISTENT AREA OF FOG OVER
THE SOUTHERN TIP OF LAKE MICHIGAN. THE HRRR MODEL WHICH HAS A
DECENT HANDLE ON THE CURRENT POSITION OF THE FOG BANK TRIES TO
OOZE IT A BIT INLAND EARLY THIS EVENING BEFORE WINDS TURN LIGHT
SOUTHERLY AND MOVE IT BACK OVER THE LAKE. IF THE FOG WERE TO MAKE
A BETTER PUSH INLAND THAN EXPECTED...MDW WOULD BE AT RISK BUT GYY
IS MOST LIKELY TO GET CLIPPED SO HAVE INTRODUCED LOW MVFR VSBY AT
GYY EARLY THIS EVENING. IF THE FOG OVERSPREADS GYY...IFR VSBY AND
CIGS ARE CERTAINLY POSSIBLE. SECOND...A MOIST AIR MASS REMAINS IN
PLACE OVER THE AREA AND WITH LIGHT WINDS TONIGHT...MVFR OR LOWER
BR IS POSSIBLE...AND MORE LIKELY TO BE OBSERVED AT RFD/DPA/GYY
THAN ORD AND MDW. GIVEN THE UNCERTAINTY THE LIGHT SOUTH WINDS WILL
HAVE ON HOW LOW VSBY GETS TONIGHT INTO EARLY FRIDAY...KEPT
RFD/DPA/GYY AT MVFR FOR NOW.
WINDS WILL THEN SHIFT SOUTH-SOUTHWEST (200-230 DEGREES) MID-
LATE FRIDAY MORNING AHEAD OF A COLD FRONT AND BECOME GUSTY.
FORECAST SOUNDINGS SUGGEST THE POTENTIAL FOR GUSTS TO AROUND 20 KT
AND SPORADICALLY HIGHER. SCATTERED THUNDERSTORMS ARE POSSIBLE AS
THE FRONT APPROACHES EARLY FRIDAY EVENING. OPTED TO KEEP THE ORD
TAF DRY AS THE BEST CHANCE FOR SHRA/TSRA CURRENTLY APPEARS TO BE
AT OR A BIT AFTER 00Z TOMORROW EVENING.
RC
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN EAST WINDS REMAINING PRIMARILY BELOW 10 KT
THROUGH EARLY THIS EVENING.
* MEDIUM CONFIDENCE THAT VSBY WILL REMAIN VFR OVERNIGHT THROUGH
EARLY FRIDAY.
* MEDIUM-HIGH CONFIDENCE IN WIND SPEED AND DIRECTION MID-LATE
FRIDAY MORNING THROUGH FRIDAY AFTERNOON.
* MEDIUM CONFIDENCE THAT BEST POTENTIAL FOR SHRA/TSRA IS AT OR A
BIT AFTER 00Z FRIDAY EVENING.
RC
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT...CHC SHRA/TSRA. MVFR CIGS PSBL.
SATURDAY...MVFR CIGS PSBL.
SUNDAY...CHC SHRA/TSRA.
MONDAY THROUGH WEDNESDAY...VFR.
JEE
&&
.MARINE...
303 PM CDT
HIGH PRESSURE OVER MICHIGAN WILL CONTINUE TO MOVE SOUTHEASTWARD
TONIGHT WHILE LOW PRESSURE MOVES FROM MINNESOTA TO LAKE SUPERIOR.
THE PRESSURE GRADIENT WILL BUILD ACROSS NORTHERN SECTIONS OF THE
LAKE OVERNIGHT AND SPREAD DOWN THE LAKE FRIDAY MORNING. THIS WILL
SUPPORT AND INCREASE IN SOUTHWESTERLY WINDS ACROSS THE LAKE THROUGH
FRIDAY MORNING. ANOTHER CONCERN LINGERING FOG OF SOUTHERN LAKE
MICHIGAN THIS AFTERNOON. HAVE ISSUED A DENSE FOG ADVISORY FOR MOST
OF THE IL/IN NEARSHORE WATERS AND THE FAR SOUTHWEST CORNER OF THE
OPEN WATERS. WITH WINDS REMAINING LIGHT ACROSS THE FAR SOUTH INTO
TONIGHT SO THIS FOG MAY CONTINUE THOUGH IT MAY LIFT TO LOW STRATUS
AROUND THE EDGES INTO EARLY EVENING. LOW CONFIDENCE IN HOW IT
EVOLVES BUT THE PRESSURE GRADIENT ORGANIZES SOMEWHAT THIS EVENING
SO A STEADIER...BUT STILL LIGHT...SOUTH WIND SHOULD RESULT AND MAY
HELP ANY REMAINING VSBY REDUCTIONS TO IMPROVE. A COLD FRONT WILL
DROP SOUTHWARD DOWN THE LAKE FRIDAY AND FRIDAY EVENING TURNING
WINDS NORTHERLY. WEAK HIGH PRESSURE WILL THEN BUILD IN SATURDAY
BRINGING WEAKENING WINDS INTO SATURDAY EVENING. STRONG LOW
PRESSURE WILL THEN MOVE FROM NORTHERN MINNESOTA/WESTERN ONTARIO
ACROSS LAKE SUPERIOR SUNDAY SENDING A COLD FRONT EASTWARD ACROSS
THE LAKE SUNDAY AFTERNOON OR EVENING. STRONG HIGH PRESSURE WILL
MOVE EAST ACROSS THE PLAINS AND MID AND UPPER MISSISSIPPI RIVER
VALLEY MONDAY. THERE WILL BE A STRONG PRESSURE GRADIENT BETWEEN
THE TWO SYSTEMS WITH A PUSH OF COOLER AIR SPREADING IN BEHIND THE
FRONT SO WINDS WILL BE INCREASING AS THEY TURN NORTHWEST THEN MORE
NORTHERLY. THE HIGH WILL THEN MOVE ACROSS THE LAKE
TUESDAY/WEDNESDAY BRINGING LIGHT AND VARIABLE WINDS.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...DENSE FOG ADVISORY...LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ779
UNTIL 10 PM THURSDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
107 PM CDT THU AUG 29 2013
.DISCUSSION...
324 AM CDT
THE FORECAST CHALLENGES INCLUDE FOG IN THE NEAR TERM...THEN
INCREASING TEMPS AND THUNDERSTORM CHANCES FRIDAY...FOLLOWED BY A
COOL DOWN AND RETURN TO MORE SEASONABLE CONDITIONS TOWARD END OF THE
HOLIDAY WEEKEND.
GOES IMAGERY THIS MORNING SHOWS EXPANDING AREA OF STRATUS ACROSS
MUCH OF THE FORECAST AREA WITH SURFACE OBS AND WEBCAMS SHOWING A
SMATTERING OF DENSE FOG HERE AND THERE. ALL INDICATIONS ARE THAT THE
STRATUS IS THIN AND SHOULD BURN OFF QUICKLY THIS MORNING EXPECT NEAR
THE LAKE FRONT WHERE MARINE STRATUS AND POSSIBLY EVEN SOME FOG COULD
HOLD ON INTO THE AFTERNOON. ANOTHER COMPARATIVELY COOL DAY NEAR THE
LAKE WITH 70S RANGING QUICKLY UPWARD TO 80S INLAND JUST A FEW MILES
WITH UPPER 80S TO NEAR 90 EXPECTED SOUTHERN AND WESTERN PORTIONS OF
THE CWA.
SURFACE BOUNDARY STALLED OUT FROM SOUTHERN MINNESOTA TO CENTRAL
ILLINOIS WILL DISSIPATE THIS AFTERNOON INTO TONIGHT AS BROAD
SOUTHERLY FLOW DEVELOPS WITH SFC LOW TRACKING EAST INTO THE UPPER
GREAT LAKES FRIDAY MORNING. TRAILING COLD FRONT ALONG WITH GLANCING
BLOW FROM THE ASSOCIATED SHORTWAVE PASSING TO OUR NORTHEAST COULD
RESULT IN CONVECTION DEVELOPING FRIDAY AFTERNOON OVER SOUTHERN WI OR
POSSIBLY FAR NORTHERN ILLINOIS. HOT AND HUMID CONDITIONS WILL RESULT
IN MODERATE TO STRONG INSTABILITY ACROSS THE AREA THOUGH CONFIDENCE
IS LOW IN THE MAGNITUDE OF THE DEEP LAYER SHEAR. DEPENDING ON THE
TIMING AND TRACK OF THE VORT AND ASSOCIATED STRONGER MID LEVEL FLOW
SHEAR COULD BE WEAK TO POSSIBLY ON THE HIGHER END OF MODERATE. GIVEN
THE UNCERTAINTIES ABOUT POSSIBLE CONVECTIVE INITIATION AND MAGNITUDE
OF SHEAR IF STORMS DO FORM...CONFIDENCE IN SEVERE THREAT ISN`T HIGH
BUT WORTH KEEPING AN EYE ON SINCE NORTHWEST FLOWS CAN BE FULL OF
SURPRISES. MODELS ALL AGREE IN A RESURGENCE OF THE MORE INTENSE HEAT
AND HUMIDITY WITH HIGHS IN THE LOW TO MID 90S AND HEAT INDICES
POTENTIALLY GETTING UP CLOSE TO OR PERHAPS A BIT OVER 100 FRIDAY
AFTERNOON.
WEAK COLD FRONT LOOKS TO PASS THROUGH THE AREA FRIDAY NIGHT
RESULTING IN A WIND SHIFT TO THE NORTH AND SLIGHTLY COOLER AIR
ARRIVING SATURDAY...EXCEPT NEAR THE LAKE WHERE THE COOL DOWN WILL BE
MORE PRONOUNCED WITH THE FLOW OFF THE LAKE.
MUCH STRONGER SHORTWAVE WILL CREST THE TOP OF THE SLOWLY
RETROGRADING CENTRAL CONUS RIDGE SATURDAY BEFORE DIGGING SOUTHEAST
INTO THE GREAT LAKES REGION SUNDAY. STRONGER COLD FRONT WITH A MORE
ROBUST PUSH OF COOLER AND LESS HUMID AIR WILL MOVE THROUGH LATER
SUNDAY. ITS QUESTIONABLE HOW MUCH MOISTURE/INSTABILITY WILL BE
AROUND FOR CONVECTION WITH THIS SECOND FRONT IN THE WAKE OF THE
FIRST FROPA. HAVE MAINTAINED JUST CHANCE POPS FOR NOW WITH SOME
GUIDANCE STILL SUGGESTING A DRY SECONDARY FROPA AND GIVEN THE TRENDS
THIS SUMMER...DRIER IS USUALLY THE WAY TO GO.
DRY NORTHWEST FLOW THEN FORECAST TO SET UP OVER THE AREA THROUGH
MUCH OF NEXT WEEK. INITIAL PUSH OF COOLER AIR MONDAY INTO TUESDAY
WILL BE REPLACED WITH QUICK WARM UP MIDWEEK FOLLOWED BY ANOTHER
NORTHWEST FLOW COLD FRONT AND PUSH OF COOLER AIR. ALL IN ALL LOOKS
LIKE PRETTY TYPICAL EARLY METEOROLOGICAL FALL TYPE WEATHER.
IZZI
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* EAST WINDS JUST UNDER 10 KT THROUGH EARLY EVENING.
* MVFR VSBY POSSIBLE TONIGHT INTO EARLY FRIDAY.
* SOUTH-SOUTHWEST WINDS OF 200-230 DEG DEVELOP MID-LATE FRIDAY
MORNING WITH GUSTS TO AROUND 20 KT POSSIBLE.
* SHRA/TSRA POSSIBLE LATE AFTERNOON THROUGH EARLY EVE FRIDAY.
RC
//DISCUSSION...UPDATED 18Z...
THE LAKE BREEZE BOUNDARY HAS PUSHED THROUGH MDW AND ORD SO
EASTERLY WINDS ARE IN STORE THROUGH EARLY EVENING THERE. BASED ON
NEAR LAKE OBSERVATIONS...SPEEDS SHOULD REMAIN PRIMARILY BELOW
10KT. THERE ARE THEN A FEW FORECAST UNCERTAINTIES THIS EVENING
THROUGH THE OVERNIGHT. FIRST IS THE PERSISTENT AREA OF FOG OVER
THE SOUTHERN TIP OF LAKE MICHIGAN. THE HRRR MODEL WHICH HAS A
DECENT HANDLE ON THE CURRENT POSITION OF THE FOG BANK TRIES TO
OOZE IT A BIT INLAND EARLY THIS EVENING BEFORE WINDS TURN LIGHT
SOUTHERLY AND MOVE IT BACK OVER THE LAKE. IF THE FOG WERE TO MAKE
A BETTER PUSH INLAND THAN EXPECTED...MDW WOULD BE AT RISK BUT GYY
IS MOST LIKELY TO GET CLIPPED SO HAVE INTRODUCED LOW MVFR VSBY AT
GYY EARLY THIS EVENING. IF THE FOG OVERSPREADS GYY...IFR VSBY AND
CIGS ARE CERTAINLY POSSIBLE. SECOND...A MOIST AIR MASS REMAINS IN
PLACE OVER THE AREA AND WITH LIGHT WINDS TONIGHT...MVFR OR LOWER
BR IS POSSIBLE...AND MORE LIKELY TO BE OBSERVED AT RFD/DPA/GYY
THAN ORD AND MDW. GIVEN THE UNCERTAINTY THE LIGHT SOUTH WINDS WILL
HAVE ON HOW LOW VSBY GETS TONIGHT INTO EARLY FRIDAY...KEPT
RFD/DPA/GYY AT MVFR FOR NOW.
WINDS WILL THEN SHIFT SOUTH-SOUTHWEST (200-230 DEGREES) MID-
LATE FRIDAY MORNING AHEAD OF A COLD FRONT AND BECOME GUSTY.
FORECAST SOUNDINGS SUGGEST THE POTENTIAL FOR GUSTS TO AROUND 20 KT
AND SPORADICALLY HIGHER. SCATTERED THUNDERSTORMS ARE POSSIBLE AS
THE FRONT APPROACHES EARLY FRIDAY EVENING. OPTED TO KEEP THE ORD
TAF DRY AS THE BEST CHANCE FOR SHRA/TSRA CURRENTLY APPEARS TO BE
AT OR A BIT AFTER 00Z TOMORROW EVENING.
RC
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE IN EAST WINDS REMAINING PRIMARILY BELOW 10 KT
THROUGH EARLY THIS EVENING.
* MEDIUM CONFIDENCE THAT VSBY WILL REMAIN VFR OVERNIGHT THROUGH
EARLY FRIDAY.
* MEDIUM-HIGH CONFIDENCE IN WIND SPEED AND DIRECTION MID-LATE
FRIDAY MORNING THROUGH FRIDAY AFTERNOON.
* MEDIUM CONFIDENCE THAT BEST POTENTIAL FOR SHRA/TSRA IS AT OR A
BIT AFTER 00Z FRIDAY EVENING.
RC
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT...CHC SHRA/TSRA. MVFR CIGS PSBL.
SATURDAY...MVFR CIGS PSBL.
SUNDAY...CHC SHRA/TSRA.
MONDAY THROUGH WEDNESDAY...VFR.
JEE
&&
.MARINE...
310 AM CDT
HIGH PRESSURE IS OVER THE GREAT LAKES WITH LIGHT WINDS EXPECTED
TODAY. OVER THE SOUTHERN HALF OF THE LAKE WINDS WILL TURN ONSHORE
RESULTING IN VARIABLE WINDS. LOW PRESSURE CURRENTLY OVER THE
DAKOTAS SHIFTS EAST AND WINDS BECOME SOUTH AHEAD OF IT TONIGHT. THE
LOW PASSES OVER THE LAKE FRIDAY WITH NORTH WINDS EXPECTED BEHIND THE
LOW FRIDAY NIGHT. A BRIEF RIDGE OF HIGH PRESSURE MOVES OVER THE
LAKE SATURDAY BEFORE A MUCH MORE SUBSTANTIAL LOW PASSES NORTH OF THE
LAKE SUNDAY. GUIDANCE STILL DIFFERS ON THE TRACK OF THE LOW BUT
WENT WITH THE MORE CONSISTENT ECMWF MODEL THAT CONTINUES TO INDICATE
THE LOW WILL PASS NORTH OF THE LAKE. WINDS TURN NORTH BEHIND THE
LOWS COLD FRONT SUNDAY NIGHT WITH WINDS AT LEAST 15 TO 25 KT
EXPECTED SUNDAY NIGHT AND MONDAY. WILL MONITOR WINDS AND WAVES OVER
INDIANA NEXT MONDAY BECAUSE A SMALL CRAFT ADVISORY AND RIP CURRENT
STATEMENT MAY BOTH BE NEEDED FOR THE INDIANA NEARSHORE WATERS
MONDAY AND MONDAY NIGHT. HIGH PRESSURE MOVES IN MONDAY NIGHT
ALLOWING WINDS TO DIMINISH IN SPEED.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
406 AM CDT THU AUG 29 2013
.DISCUSSION...
324 AM CDT
THE FORECAST CHALLENGES INCLUDE FOG IN THE NEAR TERM...THEN
INCREASING TEMPS AND THUNDERSTORM CHANCES FRIDAY...FOLLOWED BY A
COOL DOWN AND RETURN TO MORE SEASONABLE CONDITIONS TOWARD END OF THE
HOLIDAY WEEKEND.
GOES IMAGERY THIS MORNING SHOWS EXPANDING AREA OF STRATUS ACROSS
MUCH OF THE FORECAST AREA WITH SURFACE OBS AND WEBCAMS SHOWING A
SMATTERING OF DENSE FOG HERE AND THERE. ALL INDICATIONS ARE THAT THE
STRATUS IS THIN AND SHOULD BURN OFF QUICKLY THIS MORNING EXPECT NEAR
THE LAKE FRONT WHERE MARINE STRATUS AND POSSIBLY EVEN SOME FOG COULD
HOLD ON INTO THE AFTERNOON. ANOTHER COMPARATIVELY COOL DAY NEAR THE
LAKE WITH 70S RANGING QUICKLY UPWARD TO 80S INLAND JUST A FEW MILES
WITH UPPER 80S TO NEAR 90 EXPECTED SOUTHERN AND WESTERN PORTIONS OF
THE CWA.
SURFACE BOUNDARY STALLED OUT FROM SOUTHERN MINNESOTA TO CENTRAL
ILLINOIS WILL DISSIPATE THIS AFTERNOON INTO TONIGHT AS BROAD
SOUTHERLY FLOW DEVELOPS WITH SFC LOW TRACKING EAST INTO THE UPPER
GREAT LAKES FRIDAY MORNING. TRAILING COLD FRONT ALONG WITH GLANCING
BLOW FROM THE ASSOCIATED SHORTWAVE PASSING TO OUR NORTHEAST COULD
RESULT IN CONVECTION DEVELOPING FRIDAY AFTERNOON OVER SOUTHERN WI OR
POSSIBLY FAR NORTHERN ILLINOIS. HOT AND HUMID CONDITIONS WILL RESULT
IN MODERATE TO STRONG INSTABILITY ACROSS THE AREA THOUGH CONFIDENCE
IS LOW IN THE MAGNITUDE OF THE DEEP LAYER SHEAR. DEPENDING ON THE
TIMING AND TRACK OF THE VORT AND ASSOCIATED STRONGER MID LEVEL FLOW
SHEAR COULD BE WEAK TO POSSIBLY ON THE HIGHER END OF MODERATE. GIVEN
THE UNCERTAINTIES ABOUT POSSIBLE CONVECTIVE INITIATION AND MAGNITUDE
OF SHEAR IF STORMS DO FORM...CONFIDENCE IN SEVERE THREAT ISN`T HIGH
BUT WORTH KEEPING AN EYE ON SINCE NORTHWEST FLOWS CAN BE FULL OF
SURPRISES. MODELS ALL AGREE IN A RESURGENCE OF THE MORE INTENSE HEAT
AND HUMIDITY WITH HIGHS IN THE LOW TO MID 90S AND HEAT INDICES
POTENTIALLY GETTING UP CLOSE TO OR PERHAPS A BIT OVER 100 FRIDAY
AFTERNOON.
WEAK COLD FRONT LOOKS TO PASS THROUGH THE AREA FRIDAY NIGHT
RESULTING IN A WIND SHIFT TO THE NORTH AND SLIGHTLY COOLER AIR
ARRIVING SATURDAY...EXCEPT NEAR THE LAKE WHERE THE COOL DOWN WILL BE
MORE PRONOUNCED WITH THE FLOW OFF THE LAKE.
MUCH STRONGER SHORTWAVE WILL CREST THE TOP OF THE SLOWLY
RETROGRADING CENTRAL CONUS RIDGE SATURDAY BEFORE DIGGING SOUTHEAST
INTO THE GREAT LAKES REGION SUNDAY. STRONGER COLD FRONT WITH A MORE
ROBUST PUSH OF COOLER AND LESS HUMID AIR WILL MOVE THROUGH LATER
SUNDAY. ITS QUESTIONABLE HOW MUCH MOISTURE/INSTABILITY WILL BE
AROUND FOR CONVECTION WITH THIS SECOND FRONT IN THE WAKE OF THE
FIRST FROPA. HAVE MAINTAINED JUST CHANCE POPS FOR NOW WITH SOME
GUIDANCE STILL SUGGESTING A DRY SECONDARY FROPA AND GIVEN THE TRENDS
THIS SUMMER...DRIER IS USUALLY THE WAY TO GO.
DRY NORTHWEST FLOW THEN FORECAST TO SET UP OVER THE AREA THROUGH
MUCH OF NEXT WEEK. INITIAL PUSH OF COOLER AIR MONDAY INTO TUESDAY
WILL BE REPLACED WITH QUICK WARM UP MIDWEEK FOLLOWED BY ANOTHER
NORTHWEST FLOW COLD FRONT AND PUSH OF COOLER AIR. ALL IN ALL LOOKS
LIKE PRETTY TYPICAL EARLY METEOROLOGICAL FALL TYPE WEATHER.
IZZI
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* CHANCE THAT IFR CIGS COULD MOVE BACK IN EARLY THIS
MORNING...ESPECIALLY AT MDW.
* EAST WINDS ARND 10 KT BCMG SE THIS EVENING ARND 05 KT.
JEE
//DISCUSSION...UPDATED 06Z...
HIGH PRESSURE IS SETTLING OVER THE REGION RESULTING IN LIGHT TO
CALM WINDS. AN AREA OF LIFR TO IFR CIGS IS STILL PUSHING WEST OFF
OF THE LAKE AND EXPECTING IT TO REACH RFD BY 07Z. CIGS UNDER THE
STRATUS WILL RANGE FROM 002 TO 006 FT BASED ON CURRENT OBS WITH
VSBY BEING EVEN MORE VARIABLE. GUIDANCE INDICATES VSBY WILL DROP
AT ALL OF THE TERMINALS ARND 8Z AND TOOK THE MORE FOG PRONE AREAS
SUCH AS GYY...DPA...AND RFD DOWN TO 1 TO 1 1/2 SM. WITH FLOW OFF
THE LAKE AND BEING A BIT WARMER...KEPT MDW AND ORD AT 2SM.
ONCE MIXING GETS GOING THIS MORNING...ARND 14Z...THINKING THE FOG
AND STRATUS WILL QUICKLY ERODE LEADING TO A VFR DAY. WINDS WILL
BE EAST ARND 10 KT AND SLOWLY VEER TO SE ARND 5KT IN THE EVENING.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* MEDIUM CONFIDENCE IN IFR CIGS STAYING OUT OF ORD AND MDW THIS
MORNING.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
JEE
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...VFR. CHANCE TS AFTERNOON AND NIGHT...LOCAL IFR POSSIBLE
WITH TSRA.
SATURDAY AND SUNDAY...VFR. CHANCE TS DAYTIME...SLIGHT CHANCE
NIGHTTIME...LOCAL IFR POSSIBLE WITH TSRA.
MONDAY AND TUESDAY...VFR. WX NIL.
TRS
&&
.MARINE...
310 AM CDT
HIGH PRESSURE IS OVER THE GREAT LAKES WITH LIGHT WINDS EXPECTED
TODAY. OVER THE SOUTHERN HALF OF THE LAKE WINDS WILL TURN ONSHORE
RESULTING IN VARIABLE WINDS. LOW PRESSURE CURRENTLY OVER THE
DAKOTAS SHIFTS EAST AND WINDS BECOME SOUTH AHEAD OF IT TONIGHT. THE
LOW PASSES OVER THE LAKE FRIDAY WITH NORTH WINDS EXPECTED BEHIND THE
LOW FRIDAY NIGHT. A BRIEF RIDGE OF HIGH PRESSURE MOVES OVER THE
LAKE SATURDAY BEFORE A MUCH MORE SUBSTANTIAL LOW PASSES NORTH OF THE
LAKE SUNDAY. GUIDANCE STILL DIFFERS ON THE TRACK OF THE LOW BUT
WENT WITH THE MORE CONSISTENT ECMWF MODEL THAT CONTINUES TO INDICATE
THE LOW WILL PASS NORTH OF THE LAKE. WINDS TURN NORTH BEHIND THE
LOWS COLD FRONT SUNDAY NIGHT WITH WINDS AT LEAST 15 TO 25 KT
EXPECTED SUNDAY NIGHT AND MONDAY. WILL MONITOR WINDS AND WAVES OVER
INDIANA NEXT MONDAY BECAUSE A SMALL CRAFT ADVISORY AND RIP CURRENT
STATEMENT MAY BOTH BE NEEDED FOR THE INDIANA NEARSHORE WATERS
MONDAY AND MONDAY NIGHT. HIGH PRESSURE MOVES IN MONDAY NIGHT
ALLOWING WINDS TO DIMINISH IN SPEED.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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Area Forecast Discussion
National Weather Service Lincoln IL
353 AM CDT Thu Aug 29 2013
.DISCUSSION...
ISSUED 317 AM CDT Thu Aug 29 2013
Weak cold front dropping through the CWA this morning breaking up
the persistence of the sfc ridge for the Midwest. Upper level
ridge remains firmly in place though it is weakening somewhat with
a series of short waves rotating over the ridge and dampening the
more amplified flow until the end of the weekend...when the
northwesterly flow is restored. Series of waves essentially bring
pops through the holiday weekend until Monday. In the short term,
some fog this morning in the vicinity of the front as it moves
into Central Illinois. Models in fair agreement about the
continuing heat...until the cooler air moves in for Monday
afternoon.
SHORT TERM...Today and tomorrow...
Heat continues. With only small differences in some of the
temperatures...and a slightly lower dewpoint on the back side of
the frontal boundary...todays heat indices will still climb into
the 90s. Tomorrow will climb again into the low 100s as a wave
passes to the north across the Great Lakes. For this forecast
run...keeping the pops to Friday night instead of the earlier QPF
in both the NAM and GFS that moves in Friday afternoon. Concern
for the trend requiring moving the precip up into the afternoon
tomorrow... particularly with watching the cold front actually
spawn activity after quite a cap was in place yesterday afternoon.
LONG TERM...Saturday through Wednesday...
Heat continues through the weekend...with low pops for sct precip
likely making the heat maxes patchy with respect to timing...and
clearing behind convection. Potential for high heat index values
continues...but will be tempered in some locations by rainfall.
Sunday night showers should move through with a cold front that
brings significantly cooler air in and highs on Monday will only
reach into the lower 80s. Even cooler on Tuesday into the upper
70s. Behind the front for Sun night/Mon morning...the forecast
dries out again. ECMWF was a bit slower with the passage of the
boundary...but the 00z has come around to a solution more in line
with the GFS. Anticipate that even the slight chance pops in the
extended will fall out of the AllBlend should the trend continue.
HJS
&&
.AVIATION...
ISSUED 1155 PM CDT Wed Aug 28 2013
A STRATUS DECK OF CLOUDS BELOW 1K FT ALONG WITH SOME FOG WITH IFR
TO MVFR VSBYS OFF LAKE MI HAS BEEN DRIFTING STEADILY SSW TOWARD
RANTOUL AND DANVILLE. HRRR MODEL SEEMS TO BE HANDLING THIS STRATUS
CLOUD DECK THE BEST AND USED THIS MODEL FOR THE AVIATION FORECAST
OVERNIGHT INTO THU MORNING. HAVE IFR TO MVFR CONDITIONS MOVING
INTO CMI BETWEEN 06Z-07Z...BMI FROM 07Z-08Z AND PIA AND DEC 10Z-12Z.
CONFIDENCE OF THESE LOW CLOUDS OF 500-1K FT AND VSBYS AS LOW AS
1-3 MILES LOWERS AS YOU GO FURTHER SW ACROSS CENTRAL IL. HRRR
KEEPS LOW CLOUDS NE OF SPI THOUGH FOG COULD DEVELOP THERE TOO WITH
VSBYS 2-4 MILES DEVELOPING OVERNIGHT. FOG AND LOW CLOUDS TO
DISSIPATE/SCATTER OUT BETWEEN 14Z-15Z THU WITH VFR CONDITIONS
EXPECTED BY THU AFTERNOON. ENE WINDS STAY FAIRLY LIGHTER UNDER 10
KTS NEXT 24 HOURS AS FRONTAL BOUNDARY NEAR SPI PUSHES SLOWLY SW
AND WEAKENS DURING OVERNIGHT INTO THU.
07
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1247 AM CDT THU AUG 29 2013
.DISCUSSION...
955 PM CDT
A CHALLENGING OVERNIGHT INTO EARLY MORNING FORECAST WEIGHING HOW
WIDESPREAD AND THICK FOG WILL BE. OVERALL HAVE NOT MADE TOO MANY
CHANGES TO GOING FORECAST...WITH AREAS OF FOG SOME LOCALLY DENSE
BEING THE PRIMARY WORDING USED.
THE COOL FRONT CONTINUES TO SLOWLY MOVE SOUTHWARD AND IS LOCATED
JUST SOUTH OF THE CWA THIS EVE. LINGERING DEW POINTS IN THE UPPER
60S TO LOW 70S REMAIN TO THE NORTH...ALONG WITH JUST A FAIRLY MOIST
COLUMN WITH THE 00Z DVN RAOB RECORDING A PWAT OF SLIGHTLY OVER TWO
INCHES. OCCASIONAL SCATTERED 2000-5000 FT CLOUDS HAVE BEEN SEEN
IN THIS MOIST POST FRONTAL AIR MASS. OF GREATER CONCERN IS AN AREA
OF STRATUS THAT IS THE REMNANTS OF A MUCH LARGER AREA OVER LAKE
MI TODAY. THIS AREA NOW ENCOMPASSES DOWNTOWN CHICAGO AND INTO
NORTHWEST INDIANA. PER WEB CAMS OF DOWNTOWN CHICAGO AND
OBSERVATIONS THIS HAS LOWERED TO 400-800 FT. COULD FORESEE THIS
SLOW SETTLING TREND TO CONTINUE WITH ONLY SUBTLE DRY AIR ADVECTION
IN THE LOW-LEVELS. AM MOST CONCERNED NEAR THE PERIPHERY OF THE
CURRENT STRATUS WHERE SATURATION IS LIKELY TO OCCUR EVEN LOWER IN
THE VERTICAL. WITH AREA OF STRATUS STILL ADVECTING...AND
SCATTERED OTHER CLOUDS...INCLUDING EVEN HIGH CLOUDS FROM SHORT
WAVE IN WESTERN WI...JUST DID NOT FEEL CONFIDENT ENOUGH TO ISSUE
AN ADVISORY. DO BELIEVE THERE WILL BE SOME DENSE FOG IN PLACES IN
THE MORNING...MAYBE EVEN WIDESPREAD IN A FEW COUNTIES. JUST COULD
NOT DEFINE AN AREA AT THIS TIME. ALSO CURRENT OBSERVATIONS FROM
LAW ENFORCEMENT IN A FEW COUNTIES AND FROM THE SHORE OF LAKE
MICHIGAN INDICATE THAT VISIBILITY IS MAINLY PRETTY GOOD WITH ONLY
SOME LIGHT HAZE/FOG.
HAVE ADJUSTED HOURLY FORECAST TEMPERATURES/DEW POINTS TO MATCH
GOING TRENDS. CLOUDS WILL DICTATE A GREAT DEAL ON HOW LOW OR NOT
SO LOW MINS WILL FALL OUT. AREAS THAT REMAIN UNDER STRATUS FOR
MUCH OF THE NIGHT...LIKE ALONG THE IL/IN STATE LINE...SHOULD FALL
OUT WARMER THAN INITIALLY THOUGHT. HAVE BUMPED UP MINS SOME THERE
TOWARD BIAS-CORRECTED MOS. OTHERWISE DID NOT HAVE CONFIDENCE
ENOUGH TO ADJUST ANY OTHER LOCATIONS.
MTF
//PREV DISCUSSION...
306 PM CDT
FORECAST CONCERNS INCLUDE FOG POTENTIAL TONIGHT...TEMPERATURES AND
SHOWER/T-STORM CHANCES LATE IN THE WEEK INTO THE WEEKEND.
SHORT TERM...TONIGHT THROUGH SATURDAY...
TONIGHT...THE WEAK FRONT DROPPING SOUTH THROUGH THE AREA TODAY WILL
STALL JUST OUTSIDE THE CWA TONIGHT INTO THURSDAY AND A WEAK SURFACE
RIDGE WILL SPREAD SOUTHEAST OVER THE WESTERN LAKES REGION. FORECAST
SOUNDINGS SHOW A MOIST LOW LEVEL AIR MASS BUT PLENTY OF DRY AIR
ALOFT...WHICH IS A GOOD SET-UP FOR FOG VERSUS STRATUS. WILL NEED TO
WATCH FOR REEMERGENCE OF LAKE FOG BUT IT APPEARS TONIGHT WILL BE
MORE OF A RADIATIONAL FOG SET-UP WHERE RURAL AND SUBURBAN AREAS SEE
THE GREATER IMPACTS...ESPECIALLY NORTH OF INTERSTATE 80. RAW MODEL
OUTPUT AND MOS GUIDANCE SUGGESTS DENSE FOG IS POSSIBLE...BUT WILL
HOLD OFF ON AN ADVISORY AND ALLOW THE EVENING SHIFT TO ASSESS.
TEMPERATURES WILL LIKELY FOLLOW DEW POINTS DOWN TO THE MID-UPPER 60S
FOR MOST OF THE AREA OUTSIDE CHICAGO...WITH A FEW LOW 60S POSSIBLE
WEST OF THE FOX VALLEY.
CONFIDENCE IN AT LEAST PATCHY FOG...MEDIUM-HIGH.
CONFIDENCE IN DENSE FOG...MEDIUM.
THURSDAY THROUGH SATURDAY...THURSDAY WILL BE ANOTHER VERY WARM AND
HUMID DAY AWAY FROM THE LAKEFRONT WITH H85 TEMPS AROUND +20 TO +21
AND H9 TEMPS IN THE LOW-MID +20S. A SHORTWAVE OVER THE NORTHERN
ROCKIES THIS AFTERNOON WILL ROUND THE LARGE CENTRAL RIDGE TO THE
NORTHERN PLAINS AND UPPER MIDWEST BY THE EVENING. THE NORTHERN TRACK
OF THIS WAVE SHOULD KEEP THE FORCING FOR SHRA/TSRA NORTHWEST OF US
DURING THE DAY THURSDAY AND PRIMARILY TO THE NORTH THURSDAY NIGHT.
LIMITED SLIGHT POPS TO ONLY THE WISCONSIN BORDER.
UNCERTAINTY INCREASES GREATLY ON FRIDAY INTO SATURDAY AS SOLUTIONS
BEGIN TO DIVERGE AMONGST THE MODEL GUIDANCE IN THEIR HANDLING OF THE
STRENGTH OF THE LEAD WAVE. THE 12Z NAM AND CANADIAN ARE MUCH
STRONGER...DEVELOP AND TRACKING A CONSOLIDATED FAIRLY VIGOROUS
SURFACE LOW ACROSS LAKE MICHIGAN...WITH THE TRAILING COLD FRONT
SWEEPING ACROSS THE AREA LATE FRIDAY AND BRINGING A DRY AND COOLER
DAY ON SATURDAY.
FOR NOW WILL SIDE CONSERVATIVELY WITH THE GFS AND ECMWF
ROUTE...WHICH DO HAVE A COLD FRONT APPROACHING...BUT ALSO KEEP A
WEAK SURFACE LOW JUST TO OUR WEST INTO SATURDAY THAT THEN LARGELY
WASHES OUT ALONG WITH THE FRONT. WILL KEEP LOW CHANCE POPS MAINLY
FRIDAY AFTERNOON NORTH OF I-80 THEN NOT MAKE MAJOR CHANGES WITH
CHANCE POPS INTO SATURDAY DUE TO THE UNCERTAINTY. AS ALLUDED TO
EARLIER...TEMPERATURES HAVE BUST POTENTIAL ON FRIDAY...BUT IT
APPEARS THAT GUIDANCE IS ALLOWING FOR A WINDOW WHERE THE VERY WARM
THERMAL PROFILES/850 MB 20-22C 925 MB MID-UPPER 20S C WILL BE
TAPPED INTO. THUS WILL CONTINUE WITH PREVIOUS FORECAST IDEA OF LOW
90S AND A FEW MID 90S IN THE FAR WEST AND SOUTHWEST CWA. ITS
POSSIBLE THAT WINDS COULD TURN SOUTHEAST FRIDAY
AFTERNOON...RESULTING IN MINOR COOLING ALONG THE IL LAKEFRONT.
MAXIMUM HEAT INDEX VALUES ARE EXPECTED TO APPROACH 100 DEGREES AND
A FEW LOCATIONS COULD TOP 100 DEGREES...BUT AM NOT ANTICIPATING
NEEDING ANY HEADLINES. WITH THIS FORECAST SIDING MORE TOWARD THE
GFS/ECMWF SOLUTION THROUGH SATURDAY...SATURDAY WILL BE ANOTHER HOT
DAY IN THE LOW TO PERHAPS MID 90S FOR MOST OF THE AREA. WEAK FLOW
ALOFT WILL ENABLE A LAKE BREEZE TO WORK INLAND AND COOL OFF
LAKESHORE AREAS.
CONFIDENCE IN SHOWER/T-STORM TRENDS...LOW.
CONFIDENCE IN TEMPERATURES...MEDIUM.
LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...
THE UPPER LEVEL PATTERN WILL REALIGN IN THIS PERIOD...WITH A SHARP
AMPLIFICATION OF THE EASTERN NOAM TROUGH AND BETTER AGREEMENT AMONGST
THE GUIDANCE IN A STRONG SURFACE LOW TRACKING NORTH OF THE GREAT
LAKES AND INTO QUEBEC MONDAY. TRAILING FROM THIS LOW WILL BE A
STRONG COLD FRONT THAT WILL SWEEP ACROSS THE AREA ON
SUNDAY...BRINGING AT LEAST A CHANCE FOR SCATTERED STORMS. IT WILL BE
ANOTHER WARM TO HOT DAY AHEAD OF THE FRONT...WITH HIGHS DICTATED BY
FRONTAL TIMING. LOW 90S FOR PARTS OF THE AREA SEEM REASONABLE
AGAIN...ESPECIALLY SOUTH OF I-80. ON LABOR DAY...THE GFS AND ECMWF
HAVE COME INTO LINE WITH SUB 10C AIR AT 850...WHICH WILL RESULT IN
MOST AREAS IN THE MID 70S NORTH OF I-80 AND UPPER 70S SOUTH OF I-80.
THE LAKEFRONT WILL BE EVEN COOLER AND STRONG NORTH WINDS WILL LIKELY
RESULT IN DANGEROUS SWIMMING CONDITIONS DUE TO LARGE WAVES AND
STRONG CURRENTS. AFTER A COOL START TO TUESDAY...THE EASTERN TROUGH
WILL DEPART AND WARMING THERMAL PROFILES WILL SUPPORT SIMILAR IF NOT
SLIGHTLY WARMER AFTERNOON TEMPERATURES. WEDNESDAY WILL RETURN TO
SEASONABLE TEMPERATURES BUT THEN A PEEK BEYOND THE EXTENDED SHOWS
THE POSSIBILITY OF ANOTHER COOL DOWN...POSSIBLY SHARPER THAN EARLIER
IN THE WEEK.
CONFIDENCE IN SHOWERS/T-STORMS SUNDAY...MEDIUM.
CONFIDENCE IN TEMPERATURES...MEDIUM.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* LIFR/IFR CIGS AND IFR VSBY THIS MORNING.
* EAST WINDS ARND 10KT BECOMING SE ARND 5KT IN THE EVENING.
JEE
//DISCUSSION...UPDATED 06Z...
HIGH PRESSURE IS SETTLING OVER THE REGION RESULTING IN LIGHT TO
CALM WINDS. AN AREA OF LIFR TO IFR CIGS IS STILL PUSHING WEST OFF
OF THE LAKE AND EXPECTING IT TO REACH RFD BY 07Z. CIGS UNDER THE
STRATUS WILL RANGE FROM 002 TO 006 FT BASED ON CURRENT OBS WITH
VSBY BEING EVEN MORE VARIABLE. GUIDANCE INDICATES VSBY WILL DROP
AT ALL OF THE TERMINALS ARND 8Z AND TOOK THE MORE FOG PRONE AREAS
SUCH AS GYY...DPA...AND RFD DOWN TO 1 TO 1 1/2 SM. WITH FLOW OFF
THE LAKE AND BEING A BIT WARMER...KEPT MDW AND ORD AT 2SM.
ONCE MIXING GETS GOING THIS MORNING...ARND 14Z...THINKING THE FOG
AND STRATUS WILL QUICKLY ERODE LEADING TO A VFR DAY. WINDS WILL
BE EAST ARND 10 KT AND SLOWLY VEER TO SE ARND 5KT IN THE EVENING.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN CIG TRENDS...MEDIUM CONFIDENCE ON TIMING OF
IMPROVEMENT.
* HIGH CONFIDENCE IN VSBY TRENDS...MEDIUM-LOW CONFIDENCE ON HOW
LOW VSBY WILL GO AND MEDIUM-HIGH CONFIDENCE IN TIMING OF
IMPROVEMENT TO VFR.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
JEE
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...VFR. CHANCE TS AFTERNOON AND NIGHT...LOCAL IFR POSSIBLE
WITH TSRA.
SATURDAY AND SUNDAY...VFR. CHANCE TS DAYTIME...SLIGHT CHANCE
NIGHTTIME...LOCAL IFR POSSIBLE WITH TSRA.
MONDAY AND TUESDAY...VFR. WX NIL.
TRS
&&
.MARINE...
156 PM CDT
MAIN MARINE FORECAST CONCERNS INCLUDE THE POTENTIAL FOR PERSISTENCE
OR REDEVELOPMENT OF PATCHY/LOCALLY DENSE FOG TONIGHT...A BRIEF
PERIOD OF MODEST SOUTH WINDS FRIDAY AND TIMING THE PASSAGE OF
ANOTHER WEAK COLD FRONT LATE FRIDAY/FRIDAY NIGHT. A STRONGER COLD
FRONT SHOULD PUSH ACROSS THE LAKE LATE IN THE WEEKEND...WITH A
PERIOD OF RELATIVELY STRONG NORTH WINDS LATE SUNDAY NIGHT INTO
MONDAY.
EARLY AFTERNOON SURFACE ANALYSIS DEPICTS LOW PRESSURE CENTERED OVER
WESTERN PENNSYLVANIA...TRAILING A COLD FRONT ACROSS IN/IL WHICH
CONTINUED TO SINK VERY SLOWLY TO THE SOUTH. A WEAK AREA OF HIGH
PRESSURE WAS OVER THE UPPER MISSISSIPPI VALLEY AND NORTHERN LAKES.
THIS HIGH WILL CONTINUE TO DRIFT TO THE SOUTHEAST ACROSS LAKE
MICHIGAN TONIGHT...DRIFTING ACROSS THE CENTRAL LAKES THURSDAY AND
THURSDAY NIGHT. THE COMBINATION OF COOLER BUT STILL MOIST AIR OVER
THE LAKE HAS LED TO AREAS OF FOG/LOW STRATUS CLOUDS WHICH MAY TEND
TO REDEVELOP TONIGHT. HOWEVER...MODEL FORECAST SOUNDINGS SUGGEST
THAT THE MOIST LAYER OVER THE OPEN WATERS MAY BE SIGNIFICANTLY
SHALLOWER TONIGHT THAN IT WAS THIS MORNING WHICH LEADS TO SOMEWHAT
LOW CONFIDENCE IN HOW EXTENSIVE FOG MAY BE ACROSS THE LAKE TONIGHT.
THE COLD FRONT STRETCHED ACROSS THE MIDWEST WILL BEGIN TO LIFT BACK
NORTH AS A WARM FRONT ACROSS THE UPPER MIDWEST LATER THURSDAY AND
THURSDAY NIGHT...WITH LIGHT SOUTHEAST FLOW DEVELOPING ACROSS THE
LAKE AS THE SURFACE RIDGE CONTINUES TO DRIFT OFF TO THE EAST. THE
FIRST OF TWO UPPER DISTURBANCES WILL TRAVERSE ONTARIO AND THE
NORTHERN LAKES FRIDAY/FRIDAY NIGHT...WHICH WILL TRAIL A WEAK COLD
FRONT ACROSS THE LAKE ONCE AGAIN. MODELS ARE NOT IN GREAT AGREEMENT
IN HANDLING OF THE SURFACE PRESSURE FIELD LATE FRIDAY SATURDAY WITH
RESPECT TO THE SURFACE TROUGH WITH THIS FRONT...THOUGH THE OVERALL
TREND SEEMS TO BE TOWARD WEAK GRADIENT/WIND FIELD. A STRONGER UPPER
DISTURBANCE AND ASSOCIATED LOW PRESSURE CENTER WILL TRACK ACROSS
ONTARIO SATURDAY NIGHT INTO SUNDAY...WHICH WILL DRAG A STRONGER
FRONT SOUTH ACROSS THE LAKE SUNDAY. NORTH WINDS SHOULD STRENGTHEN
BEHIND THIS FRONT SUNDAY NIGHT...AS THE LOW DEEPENS OVER EASTERN
ONTARIO AND QUEBEC...AND HIGH PRESSURE BUILDS SOUTHEAST INTO THE
UPPER MIDWEST. NORTH WINDS 20-25 KT APPEAR LIKELY LATE SUNDAY NIGHT
INTO MONDAY BEFORE THE GRADIENT EVENTUALLY WEAKENS AS THE RIDGE AXIS
APPROACHES MONDAY NIGHT.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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Area Forecast Discussion
National Weather Service Lincoln IL
1200 AM CDT Thu Aug 29 2013
.DISCUSSION...
ISSUED 855 PM CDT Wed Aug 28 2013
Will be updating the forecast around 9 pm to remove the mention of
isolated showers and thunderstorms over the ne CWA this evening. A
few showers and thunderstorms occurred along a frontal boundary near
I-74 since 22Z/5 pm and just two remain at 845 pm near the Knox, Fulton
and Peoria county border and near Heyworth near the McLean and DeWitt
county border. Isolated convection has been weakening past hour
and should be gone during next half hour.
Frontal boundary just sw of I-74 will continue pushing slowly sw
through rest of central IL rest of tonight and have wsw winds turn
ne behind the front and generally less than 10 mph. Patchy fog to
develop during overnight after 1 am in moist airmass across ne
half where temps cools quicker toward dewpoints. Muggy dewpoints
have pooled from 73-78F over central and ne areas near the frontal
boundary. Lows in the upper 60s and lower 70s look on track with
coolest readings over ne areas where front has already passed by
and a bit stronger ne winds to advect in cooler air more.
07
&&
.AVIATION...
ISSUED 1155 PM CDT Wed Aug 28 2013
A STRATUS DECK OF CLOUDS BELOW 1K FT ALONG WITH SOME FOG WITH IFR
TO MVFR VSBYS OFF LAKE MI HAS BEEN DRIFTING STEADILY SSW TOWARD
RANTOUL AND DANVILLE. HRRR MODEL SEEMS TO BE HANDLING THIS STRATUS
CLOUD DECK THE BEST AND USED THIS MODEL FOR THE AVIATION FORECAST
OVERNIGHT INTO THU MORNING. HAVE IFR TO MVFR CONDITIONS MOVING
INTO CMI BETWEEN 06Z-07Z...BMI FROM 07Z-08Z AND PIA AND DEC 10Z-12Z.
CONFIDENCE OF THESE LOW CLOUDS OF 500-1K FT AND VSBYS AS LOW AS
1-3 MILES LOWERS AS YOU GO FURTHER SW ACROSS CENTRAL IL. HRRR
KEEPS LOW CLOUDS NE OF SPI THOUGH FOG COULD DEVELOP THERE TOO WITH
VSBYS 2-4 MILES DEVELOPING OVERNIGHT. FOG AND LOW CLOUDS TO
DISSIPATE/SCATTER OUT BETWEEN 14Z-15Z THU WITH VFR CONDITIONS
EXPECTED BY THU AFTERNOON. ENE WINDS STAY FAIRLY LIGHTER UNDER 10
KTS NEXT 24 HOURS AS FRONTAL BOUNDARY NEAR SPI PUSHES SLOWLY SW
AND WEAKENS DURING OVERNIGHT INTO THU.
07
&&
.PREV DISCUSSION...
ISSUED 215 PM CDT Wed Aug 28 2013
Upper level ridge continues to hold firmly over the central U.S.
early this afternoon. Several impulses were noted on the water
vapor loop rotating around the northwest periphery of the heat
dome with one such feature seen over the Dakotas, responsible for
a complex of storms over central and eastern South Dakota. An
upper level wave was depicted over parts of western KS rotating
north-northeast.
The lastest surface map indicates a weak cold front located just
north of Moline ese towards Pontiac. Temperatures to the south of
the front were into the upper 80s to middle 90s, while to the
north of the front, early afternoon readings were in the middle
80s.
SHORT TERM...Tonight through Saturday
The main challenge this period will be convection chances along
the front this evening...and then rain chances late Friday into
Saturday as a weak upper level disturbance tracks southeast into
the region. Mixed layer capes in the 2500-3000 J/KG range right
along the boundary with some weak convergence noted over the
past hour across north central IL. However, current 700 mb temps
were +12 to +13C with forecast soundings continuing to indicate
a rather deep warm layer extending from 950-700 mb which would
tend to suppress any organized updrafts later this afternoon.
Short term models indicate a rather narrow window of opportunity
late this afternoon into early this evening where the cap weakens
slightly with a bit better low level moisture convergence along
the front. Will keep an eye on satellite and radar trends this
afternoon and make a last minute decision whether to include some
isolated convection along the front.
The frontal boundary will slip to the south and west of the area
for Thursday but as far as any important changes in temperature
or dew points, not seeing it in model data. A light easterly wind
may be able to keep temperatures down a few degrees, however, dew
points are still expected to be at least in the upper 60s. The
weak surface high across the Great Lakes will begin to edge off to
our east late tomorrow with return flow setting up to our west.
Models indicate another shortwave pushing across the Dakotas into
Minnesota late Thursday night will kick off some scattered storms
to our north, but based on the orientation of the 850 thermal axis
and low level jet, most if not all the activity will remain out to
our northwest. The better low level warm advection and moisture
transport will begin to shift further east and south on Friday with
convection occurring over the northern Great Lakes shifting sse into
the better instability axis Friday afternoon, and especially Friday
night. However, with the better forcing remaining to our north, POPs
will remain in the slight chance category Friday night with
mentionable POPs continuing on Saturday, especially over the east.
Temperatures will inch back into the mid 90s over the far west on
Friday as our flow becomes more southerly, and depending on the
amount of cloud cover and any precip on Saturday, we should see
similar afternoon highs, especially across the west.
LONG TERM...Sunday through Wednesday
The pattern is then forecast to amplify across the Great Lakes
region early next week as the heat dome shifts west into the
Rockies while a trof deepens in over the upper lakes. This should
allow much cooler and less humid air into the midwest starting
on Labor Day and continuing into most of next week. It looks as
if a secondary upper wave will dig southeast into the Great Lakes
region by Wednesday helping to carve out a rather deep trof over
the eastern U.S. by the end of the week. So even though we may
temporarily cool off early next week, it looks as it there will
be one more surge of heat ahead of the second shortwave on Wed
with 850 temps around +22C by Wednesday afternoon, with a
significant cool down seen on the latest ECMWF on Thu and beyond
with forecast 850 mb temps of +6 to +8. Will play it a bit more
conservative with the temperatures that far out as the ECMWF was
quite a bit more aggressive/cooler with the initial trof digging into
the Lakes for early next week than what we are seeing now. Right now
we are looking at afternoon highs warming at least into the middle
80s by Wednesday afternoon.
With the initial trof digging southeast into the northern Great Lakes
early next week, combined with a very warm and moist atmosphere ahead
of the approaching cold front late Sunday, you would think it would
be an ideal setup for rainfall across the area. But that hasn`t
been the case for most of our area this Summer. Despite the more
favorable dynamics approaching late Sunday, we are still seeing
some rather warm temperatures in the 850-700 mb layer for Sunday
before the combination of 500 mb height falls and cooling break
down the warm layer by Sunday evening. Will carry mentionable POPs
ahead of the front west of the IL river during the day Sunday,
and over most of the area Sunday night, before the cold front and
precip chances shift off to our east and south by Monday.
Smith
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1250 PM CDT THU AUG 29 2013
.UPDATE...
ISSUED AT 628 AM CDT THU AUG 29 2013
SURFACE OBSERVATIONS INDICATED LOCALLY DENSE FOG HAS FORMED JUST
ALONG THE BOUNDARY IN SE IA. FOG AND LOW STRATUS IS ALSO SHOWING UP
ALONG WHAT NOW LOOKS TO BE A REINFORCING BACKDOOR COOL FRONT THAT
CONTINUES TO ADVANCE WESTWARD ACROSS IL...REACHING FROM ABOUT
STOCKTON TO KEWANEE. HAVE UPDATED THE FORECAST TO HIT FOG WORDING
A LITTLE HEAVIER AND FOR MORE CLOUD COVER EARLY THIS MORNING. MOST
RECENT RAP MODEL 925 MB RH FIELDS INDICATE THE ADVANCING STRATUS
AND SEPARATE AREA OF STRATUS DEVELOPING OVER EAST CENTRAL IA MAY
MERGE INTO A DECK IN THE LOW LEVEL CONVERGENCE AXIS THAT COULD
HOLD FOR MUCH OF THE MORNING. WILL CONTINUE TO WATCH THESE TRENDS
CLOSELY AS ANY DELAYED CLEARING COULD IMPACT TEMPERATURES.
&&
.SYNOPSIS...
ISSUED AT 343 AM CDT THU AUG 29 2013
AT 07Z THE SURFACE BOUNDARY WAS NEARLY STATIONARY FROM N CENTRAL
IA...SOUTHEAST TO SOUTH CENTRAL IL...JUST SOUTH OF A LINE FROM OTM
TO SOUTHEAST IA TO MQB IN W CENTRAL IL. LIGHT EASTERLY WINDS AND
LOW LEVEL MOISTURE POOLING NORTHEAST OF THIS BOUNDARY WAS KEEPING
BOTH TEMPERATURES AND DEWPOINTS IN THE 70S OVER ALL BUT THE FAR
SOUTHWEST AND NORTHEASTERN PORTIONS OF THE FORECAST AREA. THIS
MOISTURE CONVERGENCE WAS RESULTING IN AREAS OF DEVELOPING LOW
CLOUDS AND FOG. SO FAR THIS HAS BEEN CONFINED TO CLOSEST TO THE
BOUNDARY IN SE IA AND W CENTRAL IL. SATELLITE FOG CHANNEL IMAGERY
SHOWED AN AREA OF LOW CLOUDS EXPANDING EAST OUT OF NE IL...IN THE
LIGHT EASTERLY FLOW AROUND HIGH PRESSURE OVER WI AND LOWER MI. 00Z
UPPER AIR ANALYSIS SHOWED THE UPPER RIDGE HOLDING STRONG FROM AR
AND MO N-NE INTO THE NORTHERN PLAINS. THE HEAT DOME REMAINED IN
PLACE OVER THE PLAINS AND ROCKIES WITH A THERMAL RIDGE OF 850 MB
TEMPERATURES IN THE LOWER 20S REACHING FROM NEB AND SD E-SE ACROSS
IA INTO THE OHIO VALLEY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 343 AM CDT THU AUG 29 2013
CHALLENGES INCLUDE FOG TRENDS EARLY THIS MORNING...THEN THE
MAGNITUDE OF HEAT AND HUMIDITY TODAY AND TONIGHT AS THE ON-GOING
LATE AUGUST HEAT WAVE CONTINUES.
EARLY THIS MORNING...STRATUS DECK OVER NE IL WILL LIKELY CONTINUE
WESTWARD...BUT AT THE CURRENT RATE...DO NOT EXPECT IT TO REACH THE
MS RIVER UNTIL AFTER SUNRISE...AND CONFIDENCE NOT HIGH THAT IT WILL
HOLD TOGETHER OR CONTINUE AT THE SAME PACE. HAVE ALREADY UPDATED TO
ADD AREAS OF EARLY MORNING FOG FOR MUCH OF THE FORECAST AREA. BASED
ON TRENDS THE PAST FEW DAYS WITH THIS BOUNDARY...WILL EXPECT ANY FOG
TO BURN OFF BY MID MORNING.
THE STATIONARY FRONT IS STILL PROGGED TO SLOWLY DISSIPATE AS HIGH
PRESSURE BUILDS SOUTHEAST INTO THE GREAT LAKES AND WINDS BECOME
LIGHT SE TO SOUTH. SOUTHWEST OF THIS CONVERGENCE ZONE...IT WILL BE
ANOTHER DAY OF DEEP MIXING AND NEAR RECORD HEAT WITH THE AIRMASS
SUPPORTING HIGHS WELL INTO THE MID AND POSSIBLY UPPER 90S AND HEAT
INDEX READINGS BACK ABOVE 100. ALONG AND JUST NORTHEAST OF THE
BOUNDARY...DEWPOINTS LINGERING IN THE 70S WILL RESULT IN HEAT
INDEX READINGS ABOVE 100 AS WELL...DESPITE SLIGHTLY COOLER HIGHS
AROUND 90 TO THE LOWER 90S. FAR EAST CENTRAL IA AND NW IL...IN THE
MODIFIED DRIER GREAT LAKES AIRMASS AND LIGHT EASTERLY WINDS...
HIGHS SHOULD BE LIMITED TO THE MID TO UPPER 80S WITH HEAT INDEX
VALUES FROM THE UPPER 80S TO LOWER 90S. THIS SUPPORTS THE CURRENT
HEAT ADVISORY AREA AND WILL BE KEEPING IT INTACT TODAY AND HAVE
EXPANDED INTO FRIDAY. CANNOT RULE OUT AN ISOLATED BRIEF SHOWER TO
BREAK THROUGH THE CAP ALONG THE BOUNDARY AS OCCURRED LATE
YESTERDAY...BUT DOES NOT LOOK WORTHY OF MENTION BEYOND A 10
PERCENT POP.
TONIGHT...DEWPOINTS WILL RECOVER BACK INTO THE UPPER 60S TO LOWER
70S OVER MOST OF THE AREA...SUPPORTING LOWS IN A RANGE FROM THE
UPPER 60S NORTHEAST TO MID 70S IN THE FAR SOUTH. ANY NOCTURNAL
CONVECTION IN THE NORTHERN PLAINS OR UPPER MS VALLEY SHOULD REMAIN
NORTH OF THE AREA AND HAVE A DRY FORECAST.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 343 AM CDT THU AUG 29 2013
FORECAST FOCUS ON A SCORCHER ON FRIDAY THEN STRONG COLD FRONT
ARRIVES ON SUNDAY ENDING THE HEAT WAVE.
FRIDAY THROUGH SATURDAY...COMPRESSIONAL HEATING AHEAD OF A WEAK COLD
FRONT WILL PUSH TEMPERATURES TO NEAR RECORD LEVELS AT SOME LOCATIONS
ON FRIDAY. 850 MB TEMPERATURES ARE PROGGED TO +22 TO 24C AND WITH A
CAPPED ATMOSPHERE SURFACE TEMPERATURES SHOULD SOAR INTO THE MID TO
UPPER 90S AT MANY LOCATIONS. COMBINED WITH DEWPOINTS AT LEAST IN THE
LOWER 70S THIS WILL CREATE HEAT INDEX VALUES OF 100 TO 107. THIS IS
THE REASON FOR EXTENDING THE HEAT ADVISORY TO 7 PM ON FRIDAY. HAVE
LEFT OUT OUR NORTHEAST COUNTIES FOR NOW AS SOME DEBATE ON THE
POTENTIAL FOR DEBRIS CLOUDS FROM A POSSIBLE MCS PUSHING ACROSS THE
GREAT LAKES. IF A FULLY SUNNY DAY IS EVIDENT THEN THE ADVISORY WILL
NEED TO BE ISSUED FOR OUR NORTHEAST CWA.
A SIGNIFICANT SHORT WAVE WILL BE MOVING ACROSS THE MIDWEST WHICH
WILL SEND A WEAK COLD FRONT INTO THE DVN CWA BY FRIDAY EVENING. THE
CAP SHOULD WEAKEN AS CONVECTIVE TEMPERATURES ARE REACHED BUT MODELS
DIFFER ON COVERAGE OF ANY CONVECTION. THE GFS IS MUCH MORE
AGGRESSIVE WITH INDICATING WIDESPREAD THUNDERSTORMS FRIDAY NIGHT BUT
THE ECMWF HINTS AT ONLY ISOLATED OR WIDELY SCATTERED COVERAGE. ANY
STORMS THAT DO FORM IN THE VERY UNSTABLE ATMOSPHERE MAY BE CAPABLE
OF ISOLATED DAMAGING WIND. FOR NOW WILL GO WITH A 30 PERCENT POP.
SPC HAS THE ENTIRE CWA IN A SEE TEXT WITH A 5% PROBABILITY OF SEVERE.
THE FRONT WILL STALL IN THE AREA ON SATURDAY KEEPING TEMPERATURES A
BIT LOWER WITH HIGHS RANGING FROM THE UPPER 80S NORTH TO MID 90S
SOUTH. THE HEAT ADVISORY MAY NEED TO BE EXTENDED IN OUR SOUTH ON
SATURDAY.
SUNDAY THROUGH NEXT WEEK...A STRONG COLD FRONT WILL SWEEP ACROSS THE
CWA ON SUNDAY BRINGING WITH IT A 30-40% CHANCE FOR THUNDERSTORMS.
THIS OCCURRING AS A DEEPENING TROUGH DIGS SOUTHEAST INTO THE MIDWEST
AND GREAT LAKES. THE TIMING WILL BE CRUCIAL TO COVERAGE AND
INTENSITY OF THE STORMS. IF THE FRONT CAN ARRIVE DURING THE
AFTERNOON THEN THE SEVERE WEATHER POTENTIAL WILL INCREASE. WITH THE
PASSAGE OF THE FRONT MUCH COOLER AND LESS HUMID AIR WILL MAKE FOR A
VERY PLEASANT LABOR DAY AND ALSO ON TUESDAY. HIGHS WILL BE IN THE
70S TO LOWER 80S AND LOWS IN THE 50S EARLY IN THE WEEK.
TEMPERATURES SHOULD WARM BACK INTO THE 80S NEXT WEDNESDAY AHEAD OF
ANOTHER STRONG COLD FRONT WHICH WILL THEN USHER ANOTHER FALL-LIKE
AIRMASS INTO THE MIDWEST FOR LATE IN THE WEEK. HOWEVER...MUCH OF NEXT
WEEK LOOKS DRY.
HAASE
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1243 PM CDT THU AUG 29 2013
ASIDE FROM THE LAST OF A LINGERING STRATUS DECK AT 2400 FT AT/NEAR MLI
AND DBQ FOR THE FIRST HOUR/TWO OF PERIOD...VFR CONDITIONS WILL
PREVAIL THROUGH THE REMAINDER OF THE AFTERNOON AND EVENING. AFTER
MIDNIGHT...EXPECT SOME MVFR VISIBILITIES /4-5SM/ IN FOG TO DEVELOP
AND LAST THROUGH 14Z. LIGHT SOUTH SOUTHWEST WINDS WILL BE COMMON
THROUGH THE PERIOD WITH SPEEDS UNDER 10 KTS.
&&
.CLIMATE...
ISSUED AT 343 AM CDT THU AUG 29 2013
RECORD HIGHS FOR AUGUST 29...
MOLINE.........97 IN 1984
CEDAR RAPIDS...97 IN 1925
DUBUQUE........99 IN 1984
BURLINGTON.....96 IN 1953
RECORD HIGHS FOR AUGUST 30...
MOLINE.........98 IN 1953 AND PREVIOUS YEARS
CEDAR RAPIDS...100 IN 1953
DUBUQUE........94 IN 1941 AND PREVIOUS YEARS
BURLINGTON.....102 IN 1947
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...HEAT ADVISORY UNTIL 7 PM CDT FRIDAY FOR BENTON-BUCHANAN-CEDAR-
DES MOINES-HENRY IA-IOWA-JEFFERSON-JOHNSON-JONES-KEOKUK-LEE-
LINN-LOUISA-MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.
IL...HEAT ADVISORY UNTIL 7 PM CDT FRIDAY FOR HANCOCK-HENDERSON-HENRY
IL-MCDONOUGH-MERCER-ROCK ISLAND-WARREN.
MO...HEAT ADVISORY UNTIL 7 PM CDT FRIDAY FOR CLARK-SCOTLAND.
&&
$$
UPDATE...SHEETS
SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...HAASE
AVIATION...14
CLIMATE...SHEETS
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
638 AM CDT THU AUG 29 2013
.UPDATE...
ISSUED AT 628 AM CDT THU AUG 29 2013
SURFACE OBSERVATIONS INDICATED LOCALLY DENSE FOG HAS FORMED JUST
ALONG THE BOUNDARY IN SE IA. FOG AND LOW STRATUS IS ALSO SHOWING UP
ALONG WHAT NOW LOOKS TO BE A REINFORCING BACKDOOR COOL FRONT THAT
CONTINUES TO ADVANCE WESTWARD ACROSS IL...REACHING FROM ABOUT
STOCKTON TO KEWANEE. HAVE UPDATED THE FORECAST TO HIT FOG WORDING
A LITTLE HEAVIER AND FOR MORE CLOUD COVER EARLY THIS MORNING. MOST
RECENT RAP MODEL 925 MB RH FIELDS INDICATE THE ADVANCING STRATUS
AND SEPARATE AREA OF STRATUS DEVELOPING OVER EAST CENTRAL IA MAY
MERGE INTO A DECK IN THE LOW LEVEL CONVERGENCE AXIS THAT COULD
HOLD FOR MUCH OF THE MORNING. WILL CONTINUE TO WATCH THESE TRENDS
CLOSELY AS ANY DELAYED CLEARING COULD IMPACT TEMPERATURES.
&&
.SYNOPSIS...
ISSUED AT 343 AM CDT THU AUG 29 2013
AT 07Z THE SURFACE BOUNDARY WAS NEARLY STATIONARY FROM N CENTRAL
IA...SOUTHEAST TO SOUTH CENTRAL IL...JUST SOUTH OF A LINE FROM OTM
TO SOUTHEAST IA TO MQB IN W CENTRAL IL. LIGHT EASTERLY WINDS AND
LOW LEVEL MOISTURE POOLING NORTHEAST OF THIS BOUNDARY WAS KEEPING
BOTH TEMPERATURES AND DEWPOINTS IN THE 70S OVER ALL BUT THE FAR
SOUTHWEST AND NORTHEASTERN PORTIONS OF THE FORECAST AREA. THIS
MOISTURE CONVERGENCE WAS RESULTING IN AREAS OF DEVELOPING LOW
CLOUDS AND FOG. SO FAR THIS HAS BEEN CONFINED TO CLOSEST TO THE
BOUNDARY IN SE IA AND W CENTRAL IL. SATELLITE FOG CHANNEL IMAGERY
SHOWED AN AREA OF LOW CLOUDS EXPANDING EAST OUT OF NE IL...IN THE
LIGHT EASTERLY FLOW AROUND HIGH PRESSURE OVER WI AND LOWER MI. 00Z
UPPER AIR ANALYSIS SHOWED THE UPPER RIDGE HOLDING STRONG FROM AR
AND MO N-NE INTO THE NORTHERN PLAINS. THE HEAT DOME REMAINED IN
PLACE OVER THE PLAINS AND ROCKIES WITH A THERMAL RIDGE OF 850 MB
TEMPERATURES IN THE LOWER 20S REACHING FROM NEB AND SD E-SE ACROSS
IA INTO THE OHIO VALLEY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 343 AM CDT THU AUG 29 2013
CHALLENGES INCLUDE FOG TRENDS EARLY THIS MORNING...THEN THE
MAGNITUDE OF HEAT AND HUMIDITY TODAY AND TONIGHT AS THE ON-GOING
LATE AUGUST HEAT WAVE CONTINUES.
EARLY THIS MORNING...STRATUS DECK OVER NE IL WILL LIKELY CONTINUE
WESTWARD...BUT AT THE CURRENT RATE...DO NOT EXPECT IT TO REACH THE
MS RIVER UNTIL AFTER SUNRISE...AND CONFIDENCE NOT HIGH THAT IT WILL
HOLD TOGETHER OR CONTINUE AT THE SAME PACE. HAVE ALREADY UPDATED TO
ADD AREAS OF EARLY MORNING FOG FOR MUCH OF THE FORECAST AREA. BASED
ON TRENDS THE PAST FEW DAYS WITH THIS BOUNDARY...WILL EXPECT ANY FOG
TO BURN OFF BY MID MORNING.
THE STATIONARY FRONT IS STILL PROGGED TO SLOWLY DISSIPATE AS HIGH
PRESSURE BUILDS SOUTHEAST INTO THE GREAT LAKES AND WINDS BECOME
LIGHT SE TO SOUTH. SOUTHWEST OF THIS CONVERGENCE ZONE...IT WILL BE
ANOTHER DAY OF DEEP MIXING AND NEAR RECORD HEAT WITH THE AIRMASS
SUPPORTING HIGHS WELL INTO THE MID AND POSSIBLY UPPER 90S AND HEAT
INDEX READINGS BACK ABOVE 100. ALONG AND JUST NORTHEAST OF THE
BOUNDARY...DEWPOINTS LINGERING IN THE 70S WILL RESULT IN HEAT
INDEX READINGS ABOVE 100 AS WELL...DESPITE SLIGHTLY COOLER HIGHS
AROUND 90 TO THE LOWER 90S. FAR EAST CENTRAL IA AND NW IL...IN THE
MODIFIED DRIER GREAT LAKES AIRMASS AND LIGHT EASTERLY WINDS...
HIGHS SHOULD BE LIMITED TO THE MID TO UPPER 80S WITH HEAT INDEX
VALUES FROM THE UPPER 80S TO LOWER 90S. THIS SUPPORTS THE CURRENT
HEAT ADVISORY AREA AND WILL BE KEEPING IT INTACT TODAY AND HAVE
EXPANDED INTO FRIDAY. CANNOT RULE OUT AN ISOLATED BRIEF SHOWER TO
BREAK THROUGH THE CAP ALONG THE BOUNDARY AS OCCURRED LATE
YESTERDAY...BUT DOES NOT LOOK WORTHY OF MENTION BEYOND A 10
PERCENT POP.
TONIGHT...DEWPOINTS WILL RECOVER BACK INTO THE UPPER 60S TO LOWER
70S OVER MOST OF THE AREA...SUPPORTING LOWS IN A RANGE FROM THE
UPPER 60S NORTHEAST TO MID 70S IN THE FAR SOUTH. ANY NOCTURNAL
CONVECTION IN THE NORTHERN PLAINS OR UPPER MS VALLEY SHOULD REMAIN
NORTH OF THE AREA AND HAVE A DRY FORECAST.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 343 AM CDT THU AUG 29 2013
FORECAST FOCUS ON A SCORCHER ON FRIDAY THEN STRONG COLD FRONT
ARRIVES ON SUNDAY ENDING THE HEAT WAVE.
FRIDAY THROUGH SATURDAY...COMPRESSIONAL HEATING AHEAD OF A WEAK COLD
FRONT WILL PUSH TEMPERATURES TO NEAR RECORD LEVELS AT SOME LOCATIONS
ON FRIDAY. 850 MB TEMPERATURES ARE PROGGED TO +22 TO 24C AND WITH A
CAPPED ATMOSPHERE SURFACE TEMPERATURES SHOULD SOAR INTO THE MID TO
UPPER 90S AT MANY LOCATIONS. COMBINED WITH DEWPOINTS AT LEAST IN THE
LOWER 70S THIS WILL CREATE HEAT INDEX VALUES OF 100 TO 107. THIS IS
THE REASON FOR EXTENDING THE HEAT ADVISORY TO 7 PM ON FRIDAY. HAVE
LEFT OUT OUR NORTHEAST COUNTIES FOR NOW AS SOME DEBATE ON THE
POTENTIAL FOR DEBRIS CLOUDS FROM A POSSIBLE MCS PUSHING ACROSS THE
GREAT LAKES. IF A FULLY SUNNY DAY IS EVIDENT THEN THE ADVISORY WILL
NEED TO BE ISSUED FOR OUR NORTHEAST CWA.
A SIGNIFICANT SHORT WAVE WILL BE MOVING ACROSS THE MIDWEST WHICH
WILL SEND A WEAK COLD FRONT INTO THE DVN CWA BY FRIDAY EVENING. THE
CAP SHOULD WEAKEN AS CONVECTIVE TEMPERATURES ARE REACHED BUT MODELS
DIFFER ON COVERAGE OF ANY CONVECTION. THE GFS IS MUCH MORE
AGGRESSIVE WITH INDICATING WIDESPREAD THUNDERSTORMS FRIDAY NIGHT BUT
THE ECMWF HINTS AT ONLY ISOLATED OR WIDELY SCATTERED COVERAGE. ANY
STORMS THAT DO FORM IN THE VERY UNSTABLE ATMOSPHERE MAY BE CAPABLE
OF ISOLATED DAMAGING WIND. FOR NOW WILL GO WITH A 30 PERCENT POP.
SPC HAS THE ENTIRE CWA IN A SEE TEXT WITH A 5% PROBABILITY OF SEVERE.
THE FRONT WILL STALL IN THE AREA ON SATURDAY KEEPING TEMPERATURES A
BIT LOWER WITH HIGHS RANGING FROM THE UPPER 80S NORTH TO MID 90S
SOUTH. THE HEAT ADVISORY MAY NEED TO BE EXTENDED IN OUR SOUTH ON
SATURDAY.
SUNDAY THROUGH NEXT WEEK...A STRONG COLD FRONT WILL SWEEP ACROSS THE
CWA ON SUNDAY BRINGING WITH IT A 30-40% CHANCE FOR THUNDERSTORMS.
THIS OCCURRING AS A DEEPENING TROUGH DIGS SOUTHEAST INTO THE MIDWEST
AND GREAT LAKES. THE TIMING WILL BE CRUCIAL TO COVERAGE AND
INTENSITY OF THE STORMS. IF THE FRONT CAN ARRIVE DURING THE
AFTERNOON THEN THE SEVERE WEATHER POTENTIAL WILL INCREASE. WITH THE
PASSAGE OF THE FRONT MUCH COOLER AND LESS HUMID AIR WILL MAKE FOR A
VERY PLEASANT LABOR DAY AND ALSO ON TUESDAY. HIGHS WILL BE IN THE
70S TO LOWER 80S AND LOWS IN THE 50S EARLY IN THE WEEK.
TEMPERATURES SHOULD WARM BACK INTO THE 80S NEXT WEDNESDAY AHEAD OF
ANOTHER STRONG COLD FRONT WHICH WILL THEN USHER ANOTHER FALL-LIKE
AIRMASS INTO THE MIDWEST FOR LATE IN THE WEEK. HOWEVER...MUCH OF NEXT
WEEK LOOKS DRY.
HAASE
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 621 AM CDT THU AUG 29 2013
MOISTURE ASSOCIATED WITH A SURFACE BOUNDARY STALLED FROM NW TO SE
ACROSS IA AND IL WAS PRODUCING AREAS OF FOG AND STRATUS THIS
MORNING. THE NEW FORECASTS HAVE IFR CONDITIONS POSSIBLE AT ALL
SITES UNTIL ABOUT 15Z...THEN RETURNING TO VFR . THERE IS A LOW
POTENTIAL THAT LOW CLOUDS AND AT LIGHT FOG COULD HANG ON
LONGER...RESULTING IN MVFR AND POSSIBLE IFR CONDITIONS THROUGH
LATE MORNING. HOWEVER...BY AFTERNOON...CONFIDENCE IS HIGH THAT
CONDITIONS WILL BE VFR AT ALL SITES WITH LIGHT SOUTHEAST TO SOUTH
SURFACE WINDS. MVFR FOG WILL LIKELY REDEVELOP AFTER SUNSET.
&&
.CLIMATE...
ISSUED AT 343 AM CDT THU AUG 29 2013
RECORD HIGHS FOR AUGUST 29...
MOLINE.........97 IN 1984
CEDAR RAPIDS...97 IN 1925
DUBUQUE........99 IN 1984
BURLINGTON.....96 IN 1953
RECORD HIGHS FOR AUGUST 30...
MOLINE.........98 IN 1953 AND PREVIOUS YEARS
CEDAR RAPIDS...100 IN 1953
DUBUQUE........94 IN 1941 AND PREVIOUS YEARS
BURLINGTON.....102 IN 1947
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...HEAT ADVISORY UNTIL 7 PM CDT FRIDAY FOR BENTON-BUCHANAN-CEDAR-
DES MOINES-HENRY IA-IOWA-JEFFERSON-JOHNSON-JONES-KEOKUK-LEE-
LINN-LOUISA-MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.
IL...HEAT ADVISORY UNTIL 7 PM CDT FRIDAY FOR HANCOCK-HENDERSON-HENRY
IL-MCDONOUGH-MERCER-ROCK ISLAND-WARREN.
MO...HEAT ADVISORY UNTIL 7 PM CDT FRIDAY FOR CLARK-SCOTLAND.
&&
$$
UPDATE...SHEETS
SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...HAASE
AVIATION...SHEETS
CLIMATE...SHEETS
AREA FORECAST DISCUSSION
NWS GRAY ME
1020 PM EDT FRI AUG 30 2013
.SYNOPSIS...
A COLD FRONT OVER EASTERN CANADA WILL DROP SOUTHWARD TOWARDS THE
INTERNATIONAL BORDER TONIGHT AND SATURDAY. LOW PRESSURE IS
FORECAST TO TRACK EASTWARD ALONG THIS FRONTAL BOUNDARY LATE
SATURDAY AND SATURDAY NIGHT. THE BOUNDARY WILL REMAIN STALLED
THROUGH SUNDAY. A WARM FRONT LIFTS THROUGH THE REGION ON MONDAY
WITH A COLD FRONT MOVING EAST TUESDAY NIGHT INTO WEDNESDAY
MORNING. A SECONDARY COLD FRONT SWEEPS THROUGH ON THURSDAY. HIGH
PRESSURE BUILDS IN FRIDAY AND SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
10 PM UPDATE...CONTINUED TO RAISE POPS AND QPF ACROSS THE MOUNTAINS
FOR THE NEXT 4-6 HOURS OR SO AS OCCASIONAL CLUSTERS/LINES OF SHOWERS
AND STORMS CONTINUE TO STREAM EASTWARD JUST SOUTH OF THE CANADIAN
BORDER FROM ME TO NY. SOME LOCATIONS MAY SEE OVER 1 INCH OF RAIN IN
THE NEXT FEW HOURS. OTHERWISE...THERE ARE SHOWERS AND STORMS NEAR
UTICA NY THAT THE HRRR HAS A PRETTY GOOD HANDLE ON. THIS ACTIVITY
MAY MOVE ACROSS THE REST OF NH AND INTO SOUTHERN ME AFTER 06Z SO
BOOSTED POPS ACROSS THE BOARD TO ACCOUNT FOR THIS POSSIBILITY.
OTHERWISE...NO SIGNIFICANT CHANGES.
7 PM UPDATE...UPDATED POPS AND SKY A BIT FOR THIS EVENING. RADAR
SHOWS A CLUSTER OF SHOWERS AND THUNDERSTORMS BETWEEN BURLINGTON VT
AND MONTREAL. THESE ARE MOVING IN A GENERAL EASTWARD DIRECTION AND
SHOULD AFFECT NORTHERN COOS COUNTY NORTHEASTWARD INTO THE WESTERN
MAINE MOUNTAINS BETWEEN 8 PM AND 11 PM. SOME GUSTY WINDS...HEAVY
RAIN...AND FREQUENT LIGHTNING POSSIBLE WITH THESE OF THEY DON/T
WEAKEN BEFOREHAND. OTHERWISE...A FAIR EVENING FOR THE REST OF THE
AREA OUTSIDE OF A SPOTTY SHOWER OR TWO.
PREVIOUS DISCUSSION...
CLOUDS GRADUALLY INCREASE ACROSS THE AREA TONIGHT IN ADVANCE OF
SHORTWAVE PRESENTLY OVER THE GREAT LAKES ON GOES IMAGERY. A
FRONTAL BOUNDARY EXTENDED FROM THE GREAT LAKES INTO EASTERN QUEBEC
WILL DROP SLOWLY SOUTHWARD INTO THE SAINT LAWRENCE VALLEY OVERNIGHT.
WIDELY SCATTERED SHOWERS AND ISOLATED THUNDER ARE POSSIBLE ACROSS
NORTHERN AND WESTERN SECTIONS OF THE FORECAST AREA THROUGH TONIGHT
AHEAD OF THIS BOUNDARY AND THE APPROACHING SHORTWAVE. OTHERWISE...A
PARTLY CLOUDY NIGHT WITH PATCHY FOG DEVELOPING.
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
THE FRONT SHOULD BE NEAR OR SLIGHTLY NORTH OF OUR INTERNATIONAL
BORDER ON SATURDAY WITH SURFACE WAVE TO RIDE EASTWARD ALONG IT.
THE LOW, ASSOCIATED SHORTWAVE, AND DAYTIME HEATING WILL BRING
INCREASING POPS ACROSS THE AREA DURING THE DAY. HIGHS SHOULD BE
NEAR 80F WITH DEW POINTS IN THE 60S YIELDING A HUMID SUMMER DAY.
GIVEN THE AIRMASS IN PLACE...EXPECT THE POTENTIAL FOR LOCALLY
HEAVY RAINFALL. CONVECTION WILL WIND DOWN SATURDAY NIGHT AS THE
LOW AND UPPER SUPPORT RACE OFFSHORE.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
SEVERAL DAYS OF RAIN SHOWERS ARE EXPECTED THROUGH MIDWEEK AS A
COUPLE OF SEPARATE UPPER LEVEL SHORT WAVES AFFECT THE AREA. ON
SUNDAY A BOUNDARY WILL STALL OVER THE MOUNTAINS AND FOOTHILLS. THIS
FRONT WILL HELP FOCUS SHOWERS AND ISOLATED THUNDERSTORMS...WITH THE
BEST CHANCES ACROSS THE NORTH. AMPLE SB CAPE IS AVAILABLE FOR A FEW
STRONG STORMS WITH AMPLE INSTABILITY AND BULK SHEAR POOLING AROUND
THE STATIONARY BOUNDARY.
A WARM FRONT LIFTS NORTH INTO THE AREA ON MONDAY AS A CUTOFF LOW
OVER CANADA DIGS INTO THE NORTHEAST. MONDAY NIGHT INTO TUESDAY
MORNING WILL BE RAINY AND FOGGY WITH THE AXIS OF HEAVIEST RAIN
SHIFTING NORTH WITH THE WARM FRONT. MODELS DISAGREE ON THE LOCATION
OF THE HIGHEST QPF...BUT WIDESPREAD TOTALS OF 1 INCH WITH ISOLATED
SPOTS UP TO 2 INCHES ARE EXPECTED.
THE HEAVIER RAIN WILL SHIFT INTO EASTERN MAINE DURING THE DAY
TUESDAY AS THE MAIN TROUGH AXIS MOVES OVERHEAD. RAIN SHOULD END
SOMETIME TUESDAY NIGHT WITH THE PASSAGE OF THE 700 MB TROUGH. A FEW
UPSLOPE SHOWERS MAY LINGER OVER NORTHERN NH AND WESTERN MAINE. AFTER
A BRIEF RESPITE A COLD FRONT WILL PUSH THROUGH QUICKLY ON THURSDAY
WITH ANOTHER CHANCE FOR RAIN. HIGH PRESSURE FINALLY BUILDS IN FOR
THE FRIDAY AND SATURDAY TIME FRAME.
DESPITE THE RAIN AND CLOUD COVER HIGH TEMPERATURES SHOULD BE ABOVE
NORMAL THANKS TO PERIODS OF WARM AIR ADVECTION AND WESTERLY WINDS.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
SHORT TERM /THROUGH SATURDAY NIGHT/...SCT MVFR TONIGHT IN SHOWERS
AND FOG. AREAS OF MVFR SAT IN SHOWERS AND THUNDERSTORMS.
WIDESPREAD MVFR SAT NIGHT IN CIGS WITH LCL IFR IN FOG.
LONG TERM...PERIODS OF MVFR/IFR ARE EXPECTED SATURDAY THROUGH
TUESDAY IN THUNDERSTORMS...SHOWERS...AND FOG. TIMING OF INDIVIDUAL
DROPS IN CEILING/VISIBILITY WILL BE HARD TO PIN DOWN BUT WITH
AMPLE MOISTURE...LATE EVENING INTO THE EARLY MORNING HOURS EACH
DAY WILL SEE RESTRICTIONS.
&&
.MARINE...
SHORT TERM /THROUGH SATURDAY NIGHT/...WINDS AND SEAS MAY APPROACH
SCA THRESHOLDS SAT NIGHT.
LONG TERM...SEAS WILL BE AROUND 5-6 FT SUNDAY INTO MONDAY MORNING
WITH A STALLED BOUNDARY JUST NORTH OF THE WATERS.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
ES/HANES
NEAR TERM UPDATE...MLE
AREA FORECAST DISCUSSION
NWS CARIBOU ME
635 AM EDT THU AUG 29 2013
.SYNOPSIS...
HIGH PRESSURE NORTH OF THE STATE WILL WILL KEEP IT DRY TODAY
ACROSS FAR NORTHERN MAINE. SHOWERS ACROSS CENTRAL AND INTERIOR
DOWNEAST MAINE WILL DIMINISH LATER TODAY. A FRONTAL BOUNDARY WILL
ADVANCE TOWARDS THE REGION FROM THE WEST LATE FRIDAY INTO THE
WEEKEND WITH MORE SHOWERS.
&&
.NEAR TERM /THROUGH TONIGHT/...
CHALLENGING FCST THROUGH TODAY AT LEAST W/RAINFALL PLACEMENT.
630 AM UPDATE...
ADJUSTED THE PRECIP CHANCES BASED ON THE LATEST RADAR AND RUC
PLACEMENT OF THE RAINFALL. AREA OF RAIN HAS SHIFTED MORE ON A LINE
FROM NORTHERN SOMERSET COUNTY SE TOWARD LINCOLN AND DOVER-FOXCROFT
INTO THE BANGOR REGION. INCREASE PERCENTAGES TO 90% IN THESE AREAS
AND CARRIED THE MENTION OF PERIODS OF HEAVY RAINFALL ESPECIALLY
ACROSS LINCOLN AND DOVER-FOXCROFT. FURTHER NORTH ACROSS AROOSTOOK
COUNTY, IT IS PRETTY MUCH RAIN-FREE AS DRIER CONTINUES TO WORKS
ITS WAY S.
PREVIOUS DISCUSSION...
LATEST RADAR IMAGERY SHOWED A SWATH OF RAIN OCCURRING ACROSS THE
CENTRAL HIGHLANDS(MT. KATAHDIN AND MILLINOCKET) SE INTO WASHINGTON
COUNTY. LATEST MESO ANALYSIS SHOWED THIS RAINFALL LINING UP WELL A
STRONG THETA E GRADIENT IN THE LLVLS COUPLED TO LLVL CONVERGENCE.
1000-700 LAYER SHOWED SOME DEFORMATION BANDING TO ADD TO THIS PER
THE LATEST RUC W/UPPER LOW MOVING ACROSS THE CWA. RAIN SHIELD HAS
BEEN EXPANDING SOME INTO NORTHERN PISCATAQUIS AND SE AROOSTOOK
COUNTY. THE 12/00Z RUNS OF THE ECMWF DEPICTED THIS QUITE WELL AND
DECIDED TO BLEND THE ECMWF AND RUC FOR THE POPS AND PLACEMENT OF
RAIN THIS MORNING SHOWING 70-90% PRECIP CHANCES FOR THE
AFOREMENTIONED AREAS. ADDITIONAL RAINFALL OF UP TO .75 INCHES IS
POSSIBLE W/SOME LOCATIONS RECEIVING CLOSE TO AN INCH. A FLOOD
ADVISORY WAS ISSUED FOR THE MILLINOCKET AND BAXTER STATE PARK
REGION TO COVER THIS POTENTIAL. THE MILLINOCKET REGION HAS ALREADY
RECEIVED UP TO 1.5 INCHES OF RAIN SINCE WEDNESDAY AFTERNOON.
FURTHER NORTH, DRIER AIR WAS WEDGING DOWN FROM SE CANADA W/HIGH
PRES NOSING IN. THEREFORE, THERE WILL BE SHARP CUTOFF OF PRECIP
BOTH NORTH AND WELL TOWARD THE BANGOR AND BAR HARBOR REGIONS.
TEMPERATURES WILL BE A TOUGH CALL TODAY DEPENDING ON WHERE THE SUN
WILL BREAK OUT AND THIS LOOKS TO MOST LIKELY ACROSS THE DOWNEAST
AND SWRN AREAS. OTHERWISE, NE FLOW WILL KEEP CLOUDS AROUND MUCH OF
THE DAY LIMITING HEATING AS SEEN FROM THE LATEST IR SATL SHOWING
CLOUDS FILLING BACK IN EVEN ACROSS THE CROWN OF MAINE. THEREFORE,
AFTERNOON MAXES WILL STRUGGLE TO GET THROUGH THE UPPER 60S TODAY
ACROSS MUCH OF THE REGION W/THE EXCEPTION OF THE INTERIOR
DOWNEAST(BANGOR AREA) AS TEMPERATURES ARE EXPECTED TO CLIMB INTO
THE LOWER 70S. STILL BELOW NORMAL FOR LATE AUGUST.
THINGS ARE EXPECTED TO DRY OUT AS LOW PRES PULLS AWAY AND HIGH
PRES RIDGES IN FROM THE WEST. DECIDED TO STAY CLOSE TO THE
DAYCREW`S OVERNIGHT LOWS W/READINGS DROPPING INTO THE UPPER 40S
NORTH AND LOW TO MID 50S CENTRAL AND DOWNEAST AREAS. ADDED PATCHY
FOG FOR LATE TONIGHT W/THE CLEARING AND WET GROUND FROM THE
RAINFALL. CENTRAL AND INTERIOR DOWNEAST WILL BE MOST PRONE TO THE
FOG DEVELOPMENT.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
LOW PRESSURE ACROSS THE GREAT LAKES FRIDAY WILL BE MOVING SLOWLY
EAST AND A WEAK FRONTAL BOUNDARY WILL ALSO BE MOVING EAST. CLOUDS
WILL ONCE AGAIN BE ON THE INCREASE WITH THE CHANCE OF AN ISOLATED
SHOWER ACROSS WESTERN AND NORTHERN AREAS. THE FRONTAL BOUNDARY IS
THEN EXPECTED TO SET UP SOMEWHERE ACROSS CENTRAL OR NORTHERN MAINE
FRI NIGHT INTO SAT INCREASING THE CHANCE OF SHOWERS...ESPECIALLY
DURING THE AFTERNOON SATURDAY. OTHERWISE...IT IS EXPECTED TO MUGGY
WITH PATCHY FOG FRI NIGHT.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
THE WEATHER PATTERN CAN BE SUMMED UP AS HIGHLY UNSETTLED. AN UPPER
TROUGH NEAR LAKE WINNEPEG SATURDAY EVENING IS EXPECTED TO AMPLIFY AS
IT MOVES EAST AND RE-ESTABLISH AN EAST COAST TROUGH...A PATTERN SEEN
OFTEN THIS SUMMER. THIS PATTERN WILL PRODUCE A MOIST SOUTHWEST FLOW
ALOFT AHEAD OF THE UPPER TROUGH WITH A SERIES OF SHORTWAVES TO
TRAVERSE THE AREA SUN THROUGH TUE. MUCH OF THE TIME IS LIKELY TO BE
CLOUDY AND MUGGY WITH OCCASIONAL BOUTS OF SHOWERS. IT IS IMPOSSIBLE
AT THIS TIME FRAME TO TIME OUT INDIVIDUAL SHORTWAVES SO WILL HAVE TO
HAVE A BROAD BRUSH OF HIGH CHANCE POPS THOUGH MUCH OF THE PERIOD
WITH THE UNDERSTANDING THAT LIKELY OR EVEN CATEGORICAL POPS WILL
BE NEEDED FOR SOME FORECAST PERIODS DOWN THE ROAD. THE AIR MASS
WILL FEATURE DAYTIME HIGHS WILL BE CLOSE TO NORMAL WITH LOWS WELL
ABOVE NORMAL IN THE MUGGY AIR MASS. IT MAY NOT BE UNTIL SOMETIME
LATE NEXT WEEK THAT THE TROUGH AXIS IS ABLE TO FINALLY PUSH EAST
OF THE AREA WITH SOME DRIER AIR.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
NEAR TERM: IFR/MVFR THIS MORNING ACROSS ALL TERMINALS IMPROVING TO
VFR LATER TODAY INTO THE EVENING. THERE IS POTENTIAL FOR MVFR
CONDITIONS DUE TO SOME FOG DEVELOPMENT LATER TONIGHT.
SHORT TERM: MAINLY VFR FRI OUTSIDE OF ANY PATCHY EARLY MORNING FOG.
CONDITIONS ARE EXPECTED TO LOWER FRI NIGHT TO IFR/MVFR IN STRATUS
AND PATCHY FOG...WITH MVFR MUCH OF THE TIME SAT THROUGH MON WITH
OCCASIONAL IFR.
&&
.MARINE...
NEAR TERM: NO HEADLINES ATTM. SOME CONCERN ABOUT WINDS THIS
MORNING AS THE GRADIENT HAS TIGHTENED A BIT MORE THAN WHAT THE
PREVIOUS GUIDANCE WAS SHOWING. 44027 WAS SUSTAINED AT 20 KTS
W/GUSTS TO 25 KT. CLOSER INTO THE INTRA-COASTAL ZONE, WINDS AROUND
15KT. USING A BLEND OF THE NAM12 AND GFS40 WINDS, DECIDED TO ADD
GUSTS TO 25 KT FOR THE OUTER ZONES TO ACCOUNT FOR THE STRONGER
PRES GRADIENT THIS MORNING AS LOW PRES PULLS NNE ACROSS THE NW
ALTC. THIS WILL NEED TO BE MONITORED FOR A POSSIBLE SCA IF WINDS
STAY UP LONGER. SEAS ARE HOLDING AT 2-4 FT AND KEPT SEAS IN THIS
RANGE THROUGH TONIGHT.
SHORT TERM: THE WIND AND SEAS ARE EXPECTED TO REMAIN BELOW SCA LEVELS
THROUGH THE WEEKEND. A LONGER SLY FETCH IS EXPECTED TO DEVELOP
EARLY NEXT WEEK AS AN AREA OF LOW PRESSURE TO THE WEST OF THE WATERS
MOVES NORTH OF THE REGION TUESDAY. THERE IS THE POTENTIAL THAT SEAS
MAY APPROACH SCA LEVELS MON-TUE.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...HEWITT
SHORT TERM...CB
LONG TERM...CB
AVIATION...HEWITT/CB
MARINE...HEWITT/CB
AREA FORECAST DISCUSSION
NWS CARIBOU ME
356 AM EDT THU AUG 29 2013
.SYNOPSIS...
HIGH PRESSURE NORTH OF THE STATE WILL WILL KEEP IT DRY TODAY
ACROSS FAR NORTHERN MAINE. SHOWERS ACROSS CENTRAL AND INTERIOR
DOWNEAST MAINE WILL DIMINISH LATER TODAY. A FRONTAL BOUNDARY WILL
ADVANCE TOWARDS THE REGION FROM THE WEST LATE FRIDAY INTO THE
WEEKEND WITH MORE SHOWERS.
&&
.NEAR TERM /THROUGH TONIGHT/...
CHALLENGING FCST THROUGH TODAY AT LEAST W/RAINFALL PLACEMENT.
LATEST RADAR IMAGERY SHOWED A SWATH OF RAIN OCCURRING ACROSS THE
CENTRAL HIGHLANDS(MT. KATAHDIN AND MILLINOCKET) SE INTO
WASHINGTON COUNTY. LATEST MESO ANALYSIS SHOWED THIS RAINFALL
LINING UP WELL A STRONG THETA E GRADIENT IN THE LLVLS COUPLED TO
LLVL CONVERGENCE. 1000-700 LAYER SHOWED SOME DEFORMATION BANDING
TO ADD TO THIS PER THE LATEST RUC W/UPPER LOW MOVING ACROSS THE
CWA. RAIN SHIELD HAS BEEN EXPANDING SOME INTO NORTHERN PISCATAQUIS
AND SE AROOSTOOK COUNTY. THE 12/00Z RUNS OF THE ECMWF DEPICTED
THIS QUITE WELL AND DECIDED TO BLEND THE ECMWF AND RUC FOR THE
POPS AND PLACEMENT OF RAIN THIS MORNING SHOWING 70-90% PRECIP
CHANCES FOR THE AFOREMENTIONED AREAS. ADDITIONAL RAINFALL OF UP TO
.75 INCHES IS POSSIBLE W/SOME LOCATIONS RECEIVING CLOSE TO AN
INCH. A FLOOD ADVISORY WAS ISSUED FOR THE MILLINOCKET AND BAXTER
STATE PARK REGION TO COVER THIS POTENTIAL. THE MILLINOCKET REGION
HAS ALREADY RECEIVED UP TO 1.5 INCHES OF RAIN SINCE WEDNESDAY
AFTERNOON. FURTHER NORTH, DRIER AIR WAS WEDGING DOWN FROM SE
CANADA W/HIGH PRES NOSING IN. THEREFORE, THERE WILL BE SHARP
CUTOFF OF PRECIP BOTH NORTH AND WELL TOWARD THE BANGOR AND BAR HARBOR
REGIONS. TEMPERATURES WILL BE A TOUGH CALL TODAY DEPENDING ON
WHERE THE SUN WILL BREAK OUT AND THIS LOOKS TO MOST LIKELY ACROSS
THE DOWNEAST AND SWRN AREAS. OTHERWISE, NE FLOW WILL KEEP CLOUDS
AROUND MUCH OF THE DAY LIMITING HEATING AS SEEN FROM THE LATEST IR
SATL SHOWING CLOUDS FILLING BACK IN EVEN ACROSS THE CROWN OF MAINE.
THEREFORE, AFTERNOON MAXES WILL STRUGGLE TO GET THROUGH THE UPPER
60S TODAY ACROSS MUCH OF THE REGION W/THE EXCEPTION OF THE
INTERIOR DOWNEAST(BANGOR AREA) AS TEMPERATURES ARE EXPECTED TO
CLIMB INTO THE LOWER 70S. STILL BELOW NORMAL FOR LATE AUGUST.
THINGS ARE EXPECTED TO DRY OUT AS LOW PRES PULLS AWAY AND HIGH
PRES RIDGES IN FROM THE WEST. DECIDED TO STAY CLOSE TO THE
DAYCREW`S OVERNIGHT LOWS W/READINGS DROPPING INTO THE UPPER 40S
NORTH AND LOW TO MID 50S CENTRAL AND DOWNEAST AREAS. ADDED PATCHY
FOG FOR LATE TONIGHT W/THE CLEARING AND WET GROUND FROM THE
RAINFALL. CENTRAL AND INTERIOR DOWNEAST WILL BE MOST PRONE TO THE
FOG DEVELOPMENT.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
LOW PRESSURE ACROSS THE GREAT LAKES FRIDAY WILL BE MOVING SLOWLY
EAST AND A WEAK FRONTAL BOUNDARY WILL ALSO BE MOVING EAST. CLOUDS
WILL ONCE AGAIN BE ON THE INCREASE WITH THE CHANCE OF AN ISOLATED
SHOWER ACROSS WESTERN AND NORTHERN AREAS. THE FRONTAL BOUNDARY IS
THEN EXPECTED TO SET UP SOMEWHERE ACROSS CENTRAL OR NORTHERN MAINE
FRI NIGHT INTO SAT INCREASING THE CHANCE OF SHOWERS...ESPECIALLY
DURING THE AFTERNOON SATURDAY. OTHERWISE...IT IS EXPECTED TO MUGGY
WITH PATCHY FOG FRI NIGHT.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
THE WEATHER PATTERN CAN BE SUMMED UP AS HIGHLY UNSETTLED. AN UPPER
TROUGH NEAR LAKE WINNEPEG SATURDAY EVENING IS EXPECTED TO AMPLIFY AS
IT MOVES EAST AND RE-ESTABLISH AN EAST COAST TROUGH...A PATTERN SEEN
OFTEN THIS SUMMER. THIS PATTERN WILL PRODUCE A MOIST SOUTHWEST FLOW
ALOFT AHEAD OF THE UPPER TROUGH WITH A SERIES OF SHORTWAVES TO
TRAVERSE THE AREA SUN THROUGH TUE. MUCH OF THE TIME IS LIKELY TO BE
CLOUDY AND MUGGY WITH OCCASIONAL BOUTS OF SHOWERS. IT IS IMPOSSIBLE
AT THIS TIME FRAME TO TIME OUT INDIVIDUAL SHORTWAVES SO WILL HAVE TO
HAVE A BROAD BRUSH OF HIGH CHANCE POPS THOUGH MUCH OF THE PERIOD
WITH THE UNDERSTANDING THAT LIKELY OR EVEN CATEGORICAL POPS WILL
BE NEEDED FOR SOME FORECAST PERIODS DOWN THE ROAD. THE AIR MASS
WILL FEATURE DAYTIME HIGHS WILL BE CLOSE TO NORMAL WITH LOWS WELL
ABOVE NORMAL IN THE MUGGY AIR MASS. IT MAY NOT BE UNTIL SOMETIME
LATE NEXT WEEK THAT THE TROUGH AXIS IS ABLE TO FINALLY PUSH EAST
OF THE AREA WITH SOME DRIER AIR.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
NEAR TERM: IFR/MVFR THIS MORNING ACROSS ALL TERMINALS IMPROVING TO
VFR LATER TODAY INTO THE EVENING. THERE IS POTENTIAL FOR MVFR
CONDITIONS DUE TO SOME FOG DEVELOPMENT LATER TONIGHT.
SHORT TERM: MAINLY VFR FRI OUTSIDE OF ANY PATCHY EARLY MORNING FOG.
CONDITIONS ARE EXPECTED TO LOWER FRI NIGHT TO IFR/MVFR IN STRATUS
AND PATCHY FOG...WITH MVFR MUCH OF THE TIME SAT THROUGH MON WITH
OCCASIONAL IFR.
&&
.MARINE...
NEAR TERM: NO HEADLINES ATTM. SOME CONCERN ABOUT WINDS THIS
MORNING AS THE GRADIENT HAS TIGHTENED A BIT MORE THAN WHAT THE
PREVIOUS GUIDANCE WAS SHOWING. 44027 WAS SUSTAINED AT 20 KTS
W/GUSTS TO 25 KT. CLOSER INTO THE INTRA-COASTAL ZONE, WINDS AROUND
15KT. USING A BLEND OF THE NAM12 AND GFS40 WINDS, DECIDED TO ADD
GUSTS TO 25 KT FOR THE OUTER ZONES TO ACCOUNT FOR THE STRONGER
PRES GRADIENT THIS MORNING AS LOW PRES PULLS NNE ACROSS THE NW
ALTC. THIS WILL NEED TO BE MONITORED FOR A POSSIBLE SCA IF WINDS
STAY UP LONGER. SEAS ARE HOLDING AT 2-4 FT AND KEPT SEAS IN THIS
RANGE THROUGH TONIGHT.
SHORT TERM: THE WIND AND SEAS ARE EXPECTED TO REMAIN BELOW SCA LEVELS
THROUGH THE WEEKEND. A LONGER SLY FETCH IS EXPECTED TO DEVELOP
EARLY NEXT WEEK AS AN AREA OF LOW PRESSURE TO THE WEST OF THE WATERS
MOVES NORTH OF THE REGION TUESDAY. THERE IS THE POTENTIAL THAT SEAS
MAY APPROACH SCA LEVELS MON-TUE.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...HEWITT
SHORT TERM...CB
LONG TERM...CB
AVIATION...HEWITT/CB
MARINE...HEWITT/CB
AREA FORECAST DISCUSSION
NWS CARIBOU ME
102 AM EDT THU AUG 29 2013
.SYNOPSIS...
A COLD FRONT WILL PRESS SOUTH OF THE AREA THIS EVENING. HIGH
PRESSURE WILL BUILD DOWN FROM THE NORTH LATE TONIGHT INTO
THURSDAY. ANOTHER FRONT WILL APPROACH ON FRIDAY.&&
.NEAR TERM /THROUGH THURSDAY/...
100 AM UPDATE...
LATEST RADAR IMAGERY SHOWING A BAND OF SHOWERS MOVING WSW ACROSS
THE CENTRAL HIGHLANDS AND PORTIONS OF INTERIOR DOWNEAST. THE
LATEST RUC HAD A GOOD HANDLE ON THE PLACEMENT OF THE SHOWERS AND
EXPANDED THE 60-70% POPS FURTHER WSW ACROSS THE CENTRAL HIGHLANDS
INTO SWRN PISCATAQUIS AND PENOBSCOT COUNTIES. ENHANCED THE
WORDING FOR HEAVY RAINFALL IN THIS BAND AS RADAR ESTIMATES WERE
SHOWING UP TO .50-.75 INCHES PER HOUR. THE LATEST GEM HANDLED THE
SKY FCST WELL PER THE LATEST IR SATL WHICH SHOWED SOME CLEARING
ACROSS NORTHERN MAINE. THIS IN TURN HAS ALLOWED TEMPERATURES TO
DROP OFF INTO THE UPPER 50S. TWEAKED THE OVERNIGHT LOWS TO ACCOUNT
FOR THIS AS WELL.
PREVIOUS DISCUSSION...
FOR SOME SUNSHINE FOR NRN PTNS OF THE FA BY MIDDAY THU AND THE
REST OF THE FA BY MID AFTN AS INTRUSION OF SOMEWHAT DRIER AIR
MOVES INTO THE REGION.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
HIGH PRESSURE RIDGING DOWN FROM THE NORTHEAST WILL BRING A CLEAR
TO PARTLY CLOUDY NIGHT WITH LIGHT WINDS THURSDAY NIGHT. SOME
PATCHY FOG IS LIKELY IN THE RIVER VALLEYS AND ALONG THE COAST. A
WEAK SHORTWAVE OF LOW PRESSURE SLIDING EAST SOUTHEASTWARD BENEATH
A TROUGH IN EASTERN CANADA WILL APPROACH ON FRIDAY. CLOUDS WILL
INCREASE AHEAD OF THIS SHORTWAVE AND SOME ISOLATED SHOWERS ARE
POSSIBLE IN CENTRAL OR WESTERN AREAS LATE IN THE DAY. A STATIONARY
FRONT FORMING ACROSS NORTHERN AREAS FRIDAY NIGHT MAY PROVIDE THE
FOCUS FOR SOME SHOWERS LATE FRIDAY NIGHT INTO SATURDAY. OTHERWISE
SATURDAY WILL TURN OUT MOSTLY CLOUDY WITH A SOUTHERLY BREEZE
BRINGING INCREASING HUMIDITY AND A CHANCE FOR SHOWERS OVER CENTRAL
AND NORTHERN AREAS ESPECIALLY DURING THE AFTERNOON.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
FRONTAL BOUNDARY IS FORECAST TO BEGIN MOVING NORTH SATURDAY NIGHT
WITH FAIRLY GOOD GUIDANCE AGREEMENT. ALSO THERE WILL BE A UPPER
LEVEL SHORTWAVE MOVING EAST. THESE FACTORS WILL INCREASE CHANCES
OF SHOWERS FOR SUNDAY ACROSS THE REGION. THIS BOUNDARY WILL MOVE
NORTH IN ADVANCE OF A SURFACE LOW/COLD FRONT AND UPPER LEVEL
TROUGH MOVING EAST OUT OF ONTARIO. THERE ARE SOME MODEL
DISAGREEMENTS IN TERMS OF INTENSITY AND LOCATION OF SURFACE LOW.
EITHER SOLUTION WILL BRING A UNSETTLED PATTERN FOR MONDAY AND
TUESDAY. SOME WRAP AROUND SHOWERS WILL BE POSSIBLE ON WEDNESDAY AS
LOW CONTINUES TO TRACK NORTH AND EAST OF THE REGION. HIGHS AND
LOWS WILL GENERALLY BE NEAR TO SLIGHTLY ABOVE NORMAL THROUGH THE
PERIOD.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
NEAR TERM: CURRENT VFR CONDITIONS ARE XPCTD TO LOWER TO MVFR AND
IFR BEGINNING LATE THIS AFTN WITH THE ARRIVAL OF STEADIER SHWRS
AND CONTG INTO THIS EVE...WITH CONDITIONS SLOWLY IMPROVING FROM
THE FAR N LATE TNGT TO DOWNEAST THU MORN...RESULTING IN VFR
CONDITIONS MSLY ALL TAF SITES THU AFTN.
SHORT TERM: NEAR TERM: VFR CONDITIONS THURSDAY NIGHT MAY LOWER TO IFR IN
VALLEY FOG AT SOME SITES LATE. VFR CONDITIONS ARE EXPECTED FRIDAY.
CONDITIONS MAY LOWER TO MVFR FRIDAY NIGHT AND REMAIN MVFR WITH
LOCAL IFR CONDITIONS IN LOW CLOUDS ON SATURDAY. MVFR/IFR WILL BE
POSSIBLE IN HEAVIER SHOWERS SUNDAY AND MONDAY.
&&
.MARINE...
NEAR TERM: NO HDLNS XPCTD THRU THU. PATCHY FOG IS XPCTD OVR THE
WATERS OVRNGT...BUT WITH WINDS BECOMING SLIGHTLY OFFSHORE BY THU
MORN...ANY FOG SHOULD LIFT AT OR SHORTLY AFT SUNRISE THU. KEPT
CLOSE TO WW3 WV HTS...LOWERED TO 1 TO 2 FT ALG THE IMMEDIATE
COASTLINE.
SHORT TERM: WINDS AND SEAS ARE EXPECTED TO BE BELOW SCA THURSDAY
NIGHT THROUGH SATURDAY.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...HEWITT
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
125 AM EDT THU AUG 29 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 412 PM EDT WED AUG 28 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE OVER
THE CNTRL CONUS RESULTING IN ACYC FLOW FROM THE NRN PLAINS THROUGH
THE UPPER MS VALLEY AND GREAT LAKES. A WEAK SHORTWAVE TROUGH FROM
NEAR CYPL-CYHD INTO NW MN SUPPORTED SOME SCT SHRA/TSRA. A MORE
SIGNIFICANT UPSTREAM SHRTWV WAS MOVING FROM IDAHO INTO WRN MONTANA.
MID CLOUDS OVER MN INTO NW WI LEFTOVER FROM EARLIER CONVECTION AND A
WAA PATTERN UPSTREAM...WERE SPREADING INTO WRN UPPER MI. AT THE
SFC...A WEAK RIDGE FROM NRN ONTARIO INTO UPPER MI HAS BROUGHT MOSTLY
CLEAR SKIES AND LIGHT WINDS ACROSS UPPER MI AND PROMINENT LAKE
BREEZES. INLAND...MIXING IN THE SLIGHTLY DRIER AIRMASS PWAT AROUND
1.0 INCH (NEAR NORMAL) HAS DROPPED DEWPOINTS TO AROUND 60F.
WITH MAINLY CLEAR SKIES AND LIGHT WINDS...SOME FOG WILL DEVELOP
OVERNIGHT. HOWEVER...THERE HAS BEEN ENOUGH LOW LEVEL DRYING SO THAT
THE FOG IS NOT EXPECTED TO BECOME AS DENSE OR WIDESPREAD AS LAST
NIGHT. IN ADDITION...SOME MID CLOUDS MOVING INTO THE WEST MAY ALSO
LIMIT THE RADIATIONAL COOLING. OTHERWISE...MIN TEMPS SHOULD AGAIN
DROP TO AROUND 60 INLAND WITH LOWER TO MID 60S ALONG THE GREAT
LAKES.
AS THE NRN ROCKIES SHORTWAVE MOVES THROUGH SRN SASK AND MANITOBA TO
NRN MN WAA AHEAD OF THE SYSTEM WILL BRING INCREASING CLOUDS ACROSS
THE CWA. SOME SHRA/TSRA SUPPORTED BY 310K-315K ISENTROPIC ASCENT
NORTH OF A WARM FRONT INTO SRN MN MAY BRING SOME SHRA/TSRA FROM WRN
LAKE SUPERIOR AND NW WI INTO THE FAR WEST LATE. HOWEVER...ONLY LOW
END POPS WERE INCLUDED AS THE BULK OF ANY PCPN IS EXPECTED TO HOLD
OFF UNTIL AFT 00Z.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 431 PM EDT WED AUG 28 2013
ONE OF THE CONCERNS INHIBITING WIDESPREAD CONVECTION THURSDAY NIGHT
WILL BE THE FACT THAT THE SFC LOW/MAIN TROUGH WILL REMAIN TO OUR S.
SO WHILE THE SHORTWAVE CROSSES UPPER MI...STORMS MAY BE A BIT MORE
ELEVATED. THE LATEST NON-EURO RUNS DO INDICATE THE POTENTIAL FOR
MODERATE TO HEAVY RAIN...PRIMARILY ACROSS LAKE SUPERIOR...WITH 2-3IN
FALLING SOMEWHERE ACROSS THE CWA. EXACT TIMING AND PLACEMENT OF THE
HEAVIER RAIN WILL NEED TO BE PINNED DOWN A BIT LATER. THERE WAS
ENOUGH CERTAINTY TO KEEP LIKELY POPS GOING OVER THE FAR W LATE
THURSDAY EVENING...AND ACROSS MUCH OF THE W HALF OVERNIGHT...BEFORE
CONTINUING THE TRACK AROUND THE 500MB RIDGE AND SHIFTING TO OUR SE
FRIDAY MORNING. THE MOST UNSTABLE AIR WILL LIKELY BE ACROSS THE
INTERIOR W AND TO OUR SW...CLOSER TO THE SFC LOW.
A TEMPORARY RIDGE WILL EXPAND ACROSS THE UPPER GREAT LAKES FRIDAY
EVENING AS THE SFC LOW STRETCHING FROM N LAKE MI TO E IA EXITS
ACROSS LOWER MI. DIMINISHED THE CHANCE OF SHOWERS/TS FOR FRIDAY
NIGHT AND SATURDAY...AHEAD OF THE DEEPENING CANADIAN LOW. THE SFC
LOW IS STILL FIGURED TO BE OVER LAKE WINNIPEG AROUND 12Z
SATURDAY...AND SHIFT ACROSS S ONTARIO/LAKE SUPERIOR SUNDAY
MORNING-AFTERNOON. THE ECMWF IS REMAINS THE DEEPEST AT THE SFC AND
ALOFT WITH THIS FEATURE...BUT THE 12Z GFS IS CATCHING UP. WILL
CONTINUE TO LEAN THE FCST A BIT CLOSER TO THE ECMWF SOLUTION FOR
MUCH OF THIS PERIOD. QUICKER THAN ITS RUN FROM YESTERDAY...THE 12Z
ECMWF DEVELOPS THE 500MB LOW OVER ONTARIO SUNDAY MORNING /ABOUT
18HRS FASTER THAN THE GFS/. THIS WILL BE THE START OF OUR NEAR TO
BELOW NORMAL TEMPERATURES...AS ANOTHER LOW DIVES INTO EASTERN CANADA
ON WEDNESDAY. THE RESULT WILL BE A SIGNIFICANT TROUGH SUPPRESSING
THE STRONG HIGH TO OUR SW...AND 60S AND LOW 70S RETURNING TO THE
FCST FOR MONDAY...BEFORE MODERATING BACK TO NORMAL /70S/ BY
WEDNESDAY. STRONGER NW WINDS OF 10-20KTS ACROSS LAKE SUPERIOR AND
850MB TEMPS OF 4-6C SHOULD KEEP TEMPS IN THE 60S MONDAY...ALONG WITH
THE POTENTIAL FOR SHOWERS/DRIZZLE NEAR LAKE SUPERIOR. WAY OUT IN THE
FUTURE...THE ECMWF DOES HAVE 0 TO -2C TEMPS ACROSS LAKE SUPERIOR ON
THURSDAY. WILL WILL NEED TO WAIT AND SEE ON THAT ONE. EITHER
WAY...THE WARM AIR LOOKS TO BE DONE FOR A WHILE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 124 AM EDT THU AUG 29 2013
SOME MID AND HIGH CLOUDINESS STREAMING ACROSS UPPER MI HAS MADE FOG
FCST OVERNIGHT MORE CHALLENGING. INITIALLY...CLOUDS WILL WORK TO
DELAY FOG DEVELOPMENT...BUT IT STILL LOOKS LIKE CLOUDS SHOULD THIN
OUT SUFFICIENTLY FOR SOME RADIATIONAL FOG TO DEVELOP. WHILE KCMX
SHOULD ONLY FALL TO MVFR...IT MAY NOT TAKE LONG FOR IFR CONDITIONS
TO SET IN AT KIWD/KSAW ONCE CLOUDS THIN OUT. MAY SEE SOME BRIEF
PERIODS WITH VIS DOWN TO LIFR/VLIFR. IF ENOUGH CLOUDINESS HAPPENS TO
LINGER THRU THE NIGHT...FOG WILL NOT DEVELOP. FOG WILL BURN OFF A
COUPLE OF HRS AFTER SUNRISE WITH VFR CONDITIONS TO FOLLOW. THERE
MIGHT BE ISOLD/SCT SHRA/TSRA LATE THIS AFTN...BUT CONFIDENCE IN
DEVELOPMENT IS VERY LOW...SO NO MENTION WAS INCLUDED IN FCST. BETTER
POTENTIAL FOR SHRA/TSRA WILL DEVELOP TONIGHT...ESPECIALLY JUST
BEYOND THIS FCST PERIOD...AS A RATHER STRONG DISTURBANCE APPROACHES
THE UPPER LAKES.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 412 PM EDT WED AUG 28 2013
PATCHY FOG WILL PERSIST THROUGH THROUGH THURSDAY AS RELATIVELY HIGH
DEWPOINTS REMAIN THROUGH THE WEEK. DRIER AIR BEGINS MOVING IN FOR
THE WEEKEND... LIMITING FOG POTENTIAL FOR THE WEEKEND. LIGHT WINDS
WILL PREVAIL THROUGH MUCH OF THE FORECAST PERIOD AS THE PRESSURE
GRADIENT REMAINS LIGHT UNDER THE INFLUENCE OF RIDGING ALOFT. THE
PRESSURE GRADIENT WILL TIGHTEN SUNDAY WITH THE PASSAGE OF A LOW
PRESSURE SYSTEM TO THE NORTH OF LAKE SUPERIOR. BEHIND THE COLD
FRONT...NORTHWEST WINDS ARE EXPECTED TO INCREASE INTO THE 15 TO 25
KNOT RANGE. WAVES WILL MAY ALSO BUILD INTO THE 3 TO 7 FOOT RANGE
WITH COLDER AIR MOVING IN.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...ROLFSON
MARINE...JLB
AREA FORECAST DISCUSSION
NWS DULUTH MN
350 PM CDT THU AUG 29 2013
.SHORT TERM...THE MAIN FOCUS FOR TONIGHT IS THUNDERSTORMS.
AT 330 PM...THUNDERSTORMS WERE GENERALLY ON THE DECREASE ACROSS
THE CWA. THE STRONGEST STORM WAS LOCATED OVER IRON COUNTY. THIS
WAS PART OF THE LARGE LINE OF STORMS THAT MOVED FROM THE DAKOTAS
LAST NIGHT...THROUGH NORTHERN MINNESOTA AND NORTHERN WISCONSIN.
TEMPERATURES RANGED FROM THE 60S NEAR LAKE SUPERIOR TO NEAR 90 IN
OUR FAR SOUTHERN COUNTIES. DEWPOINTS WERE LARGELY IN THE 60S NORTH
TO THE 70S SOUTH.
THE MAIN FOCUS FOR TONIGHT WILL DEFINITELY BE THUNDERSTORMS. THE
ATMOSPHERE HAS BEEN WORKED OVER PRETTY WELL FROM THE MCS THAT
MOVED ACROSS MUCH OF THE CWA DURING THE DAY. IT MAY STILL TAKE
SOME TIME BEFORE THINGS DESTABILIZE FURTHER FOR MORE DEVELOPMENT
LATER THIS AFTERNOON AND INTO THE EVENING. THE NMM WRF/NSSL WRF/
HRRR AND RAP NOT DOING THE BEST AS OF 330 PM. THE 4 KM NMM WRF
SEEMS TO HAVE THE BEST HANDLE ON THE CURRENT SCENARIO. THIS MODEL
INDICATES THAT STORMS WILL FIRE UP AGAIN ACROSS NW MN AND SWEEP
FROM NW TO SE ACROSS ESPECIALLY THE SW 1/3 OF THE CWA. THIS WOULD
MAKE THE MOST SENSE AS THIS SHOULD BE THE AREA MOST APT TO
DESTABILIZE AND WITH THE BEST SURFACE CONVERGENCE. MANY OF THE
MODELS ARE ACTUALLY INDICATING THE MOST WIDESPREAD PRECIPITATION
ACROSS NORTHERN PORTIONS OF THE AREA...WHICH WOULD BE WHERE IT HAS
LARGELY STABILIZED THOUGH.
FRIDAY SHOULD BE MUCH MORE QUIET...AS A COLD FRONT BRINGS A BIT
COOLER AND DRIER AIR TO THE REGION. HIGH TEMPERATURES SHOULD STILL
BE IN THE 80S FOR THE MOST PART.
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
DRY CONDITIONS ARE EXPECTED FRI NIGHT AND EARLY SAT ACROSS MUCH OF
THE UPPER MIDWEST AS A WEAK RIDGE OF HIGH PRESSURE ALOFT AND A SFC
HIGH DOMINATE THE REGION. THE NEXT SYSTEM WILL DEVELOP OVER THE NRN
PLAINS AND CANADIAN FRONT RANGE FRI NIGHT AND MOVE EWD THROUGH NRN
MN AND INTO WRN ONTARIO DURING THE DAY SAT AND SAT NIGHT. THE MODELS
ARE IN VERY GOOD AGREEMENT BRINGING THE SFC LOW EWD JUST NORTH OF
THE INTERNATIONAL BORDER INTO WRN ONTARIO BY SUNDAY MORNING...WITH A
SFC TROUGH/COLD FRONT EXTENDING SWD THROUGH MN. SHOWERS AND STORMS
ARE EXPECTED TO SPREAD ACROSS THE REGION ALONG AND AHEAD OF THIS
FRONT...WITH A CHANCE OF A FEW STRONG OR SEVERE STORMS. AS THE SFC
LOW TRACKS TO THE EAST INTO CENTRAL ONTARIO AND THE FRONT SLIDES
INTO WI/MICH U.P. A TIGHT PRES GRADIENT WILL SET UP ON THE BACK SIDE
OF THE LOW IN NE MN AND ALLOW GUSTY N WINDS TO DEVELOP WITH A FEW
SUNDAY MORNING AND AFTERNOON CAA RAIN SHOWERS. HIGH PRESSURE WILL
MOVE IN AND DOMINATE THE AREA BY MONDAY AND CONTINUE TO BRING DRY
CONDITIONS TO THE NORTHLAND THROUGH TUE AND INTO EARLY WED. A WEAK
FRONT WILL DROP SWD INTO THE REGION LATE WED AND BRING WITH IT
ADDITIONAL CHANCES FOR SHOWERS.
TEMPERATURES SATURDAY WILL CONTINUE TO BE WARM WITH HIGHS IN THE
UPPER 70S AND LOWER TO MID 80S...ALONG WITH HUMID CONDITIONS.
HOWEVER...THE COLD FRONT ON SATURDAY NIGHT WILL USHER IN A MUCH
DRIER AND COOLER AIR MASS WITH HIGHS ON SUN AND MON IN THE 60S AND
70S...AND NOTICEABLY LOWER HUMIDITIES. TEMPS WARM BA
&&
.AVIATION...18Z TAF ISSUANCE...
LINE OF THUNDERSTORMS CURRENTLY MOVING TO THE EAST JUST NORTH OF
DLH WITH GUSTY WINDS...HEAVY LINE AND FREQUENT LIGHTNING. A BRIEF
BREAK IN THE CONVECTION IS EXPECTED EARLY THIS AFTERNOON BEFORE
ANOTHER ROUND DEVELOPS IN THE LATE AFTERNOON ACROSS N-CENTRAL MN
AND MOVES ACROSS THE NORTHLAND EARLY THIS EVENING. SOME OF THE
STORMS COULD BECOME STRONG TO SEVERE WITH VERY GUSTY WINDS AND
HAIL. A FEW OF THE STORMS COULD LINGER AROUND HYR UNTIL
06-08Z...OTHERWISE CONDITIONS CLEAR OUT FROM WEST TO EAST INTO
EARLY FRIDAY MORNING. WINDS WILL INCREASE FROM THE NNW DURING THE
MORNING FRIDAY...WITH MVFR CIGS.
&&
.POINT TEMPS/POPS...
DLH 64 80 58 79 / 80 30 0 20
INL 61 84 62 82 / 80 10 20 50
BRD 68 86 62 86 / 50 10 0 40
HYR 71 83 58 84 / 70 30 0 10
ASX 68 78 59 78 / 80 30 0 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...DAP
LONG TERM....TENTINGER
AVIATION...TENTINGER
AREA FORECAST DISCUSSION
NWS GLASGOW MT
742 PM MDT FRI AUG 30 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY...
UPDATE...SLIGHT CHANGES MADE TO CURRENT CONDITIONS. OTHERWISE A
QUIET NIGHT LOOKS TO OCCUR BEFORE THE COOLER AND BREEZY CONDITIONS
PREVAIL FOR TOMORROW. PROTON
NOT AS WARM THIS WEEKEND WITH WIND SATURDAY.
LOW PRESSURE OVER SASK THIS AFTERNOON WILL BEGIN TO SEND A COLD
FRONT OUR WAY TONIGHT WHEN AN UPPER LEVEL SYSTEM TO IT/S WEST
CATCHES UP. THIS FRONT IS EXPECTED TO PUSH SOUTHEAST THROUGH NE MT
SATURDAY MORNING. 850 MB TEMPS FALL A FEW DEGREES SATURDAY AND
ATMOSPHERE MIXES TO ABOUT 750 MB. WINDS AT THAT LEVEL LOOK TO BE
ABOUT 25-30 KTS SO 20 TO 30 MPH SURFACE WINDS CAN BE EXPECTED.
THESE WINDS ARE LOOKING TO OCCUR FROM ABOUT NOON TO 8 PM OVER FORT
PECK LAKE...SO WILL GO AHEAD AND ISSUE A LAKE WIND ADVISORY FOR
THIS PERIOD.
OTHERWISE...SOME MID-LEVEL INSTABILITY MAY BUBBLE UP A SHOWER/STORM
LATE THIS AFTERNOON. THE HRRR AS USUAL IS EXCITED ABOUT IT WHILE THE
OTHER MODELS (INCLUDING THE RUC) ARE MUCH DRIER. THE NAM IS SHOWING
THIS TO OCCUR LATER TONIGHT IN THE SOUTHERN ZONES...FINALLY EXITING
INTO THE DAKOTAS SATURDAY AFTERNOON.
SURFACE HIGH PRESSURE THEN BUILDS INTO THE AREA SATURDAY NIGHT
PROVIDING LIGHT WINDS...NEAR NORMAL TEMPS AND CLEAR SKIES THROUGH
SUNDAY. ENJOY! TFJ
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
THE LONG TERM FORECAST PERIOD IS CHARACTERIZED BY A SIGNIFICANT
AND AMPLIFIED WEATHER PATTERN...BASICALLY SPLIT BETWEEN TWO
DIFFERENT WEATHER REGIMES.
SUNDAY NIGHT THROUGH WEDNESDAY AFTERNOON...THE CENTRAL CONUS RIDGE
AND THE PACIFIC NORTHWEST LOW BUTT UP AGAINST EACH OTHER IN A
STRUGGLE FOR DOMINANCE THAT DOES NOT COME TO A RESOLUTION UNTIL
LATE WEDNESDAY NIGHT.
IT SHOULD BE NOTED THAT THE LARGE SCALE MODELS HINT AT A SHORT
WAVE DISTURBANCE RIDING UP AND AROUND THE RIDGE OF HIGH PRESSURE
MAKING ITS WAY THROUGH EASTERN MONTANA TUESDAY MORNING THROUGH
TUESDAY AFTERNOON...LIKELY BRINGING ONLY ISOLATED PRECIPITATION TO
THE AREA.
THE BIGGER STORY BEGINS OVERNIGHT WEDNESDAY NIGHT AS THE LARGE
UPPER LEVEL LOW PRESSURE SYSTEM FINALLY MOVES INLAND OVER THE
PACIFIC NORTHWEST...TURNING OUR FLOW ALOFT FROM THE SOUTHWEST AND
SOUTH. THIS WILL LIKELY PUMP SIGNIFICANT AMOUNTS OF PACIFIC
MOISTURE OVER THE NORTHERN ROCKIES AND NORTHERN HIGH PLAINS. WITH
EACH MODEL RUN...THE CONSENSUS IMPROVES REGARDING THE TIMING AND
PLACEMENT OF THIS UPPER LOW INTO THE INTER-MOUNTAIN NORTHWEST.
AT THIS TIME...SIGNIFICANT DIFFERENCES WITH THIS WEATHER REGIME
CHANGE BEGIN TO EMERGE EARLY THURSDAY MORNING AS THE AGGRESSIVE GEM
PUSHES FASTER AHEAD...FOLLOWED BY THE SLOWER GFS AND THEN THE
SLOWEST EC. FOR NOW...CAN ONLY BROAD-BRUSH THE END OF THE EXTENDED
FORECAST PERIOD WITH A WETTER WEATHER PATTERN. WOULD EXPECT THINGS
TO COME MORE INTO FOCUS OVER THE NEXT FEW DAYS. BMICKELSON
PREVIOUS LONG TERM DISCUSSION...UPPER RIDGE WILL BE OVER THE AREA MOST OF THE
WEEK WITH WARM AND MAINLY DRY WEATHER. THERE WILL BE SUMMER LIKE
TEMPERATURES NEAR 90 MONDAY AND TUESDAY.
ECMWF STILL WANTS TO BRING A BACK DOOR COLD FRONT THROUGH THE AREA
TUESDAY NIGHT WHILE THE GFS KEEP THE FRONT TO THE EAST. THIS HAS
THE ECMWF FORECASTING COOLER TEMPERATURES ON WEDNESDAY. WILL GO
SOMEWHAT COOLER ON WEDNESDAY FOR NOW.
MODELS EVENTUALLY WANT TO BRING AN UPPER LOW/TROUGH INLAND TOWARDS
THE END OF NEXT WEEK. THE FLOW ALOFT IS EXPECTED TO TURN TO THE
SOUTHWEST AROUND THURSDAY ALLOWING FOR SOME INCREASE IN MOISTURE.
WILL MENTION A SLIGHT CHANCE OF THUNDERSTORMS STARTING THURSDAY
AFTERNOON IN THE WEST AND SPREADING TO THE ENTIRE AREA BY FRIDAY.
FORRESTER
&&
.AVIATION...
VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD. WEST TO
NORTHWEST WINDS AROUND 5 TO 10 KTS ARE ANTICIPATED TONIGHT AT THE
TERMINALS. WINDS WILL INCREASE TO 15 TO 25 KTS BY TOMORROW
AFTERNOON WITH GUSTS TO 35 KTS POSSIBLE. MALIAWCO
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM NOON TO 8 PM MDT SATURDAY FOR FORT PECK
LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN
VALLEY...GARFIELD...MCCONE...PETROLEUM.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION...UPDATED
NWS ALBUQUERQUE NM
947 PM MDT FRI AUG 30 2013
.UPDATE...
WILL ADJUST POPS DOWN CONSIDERABLY FOR THE REMAINDER OF THE NIGHT
BASED ON RADAR TRENDS AND HRRR MODEL. ZONES OUT SHORTLY. CHJ
&&
.PREV DISCUSSION...523 PM MDT FRI AUG 30 2013...
.AVIATION...
00Z TAF CYCLE
SCT SHRA/TSRA WILL CONTINUE TO ROLL SLOWLY W OR NW OFF THE
NORTHERN AND WESTERN HIGH TERRAIN...WITH ISOLD ACTIVITY ACROSS THE
CENTRAL HIGHLANDS AND SC MTS. LOCALLY HEAVY RAIN AND LOW VSBYS
WILL BE THE MAIN THREATS WITH THESE CELLS. KSAF/KGUP/KFMN WILL
HAVE THE GREATEST POTENTIAL TO BE IMPACTED THIS EVENING. MUCH OF
THE ACTIVITY WILL DIMINISH BETWEEN 04-06Z. ANOTHER ROUND OF IFR
CIGS APPEARS POSSIBLE AT KGUP TONIGHT AND HAVE INSERTED THIS INTO
THE TAF. SHRA/TSRA WILL REDEVELOP SAT AFTN OVER THE HIGH TERRAIN.
THE NRN MTS WILL BE FAVORED...THOUGH SOME OF THIS ACTIVITY MAY
ROLL OFF INTO THE NE PLAINS.
34
.PREV DISCUSSION...334 PM MDT FRI AUG 30 2013...
LATEST BLENDED TOTAL PRECIPITABLE WATER SATELLITE IMAGERY
INDICATING A ROUGHLY THREE TENTHS OF AN INCH DROP IN SAME OVER
PAST ROUGHLY 18 HOURS ACROSS NE NM. THUS SOME OF THE SIGNIFICANTLY
DRIER AIR IN E CO EARLIER IS EASING SOUTHWARD INTO THE STATE.
THE RATON DEWPOINT HAS DROPPED TO 29 DEGREES AS OF MID AFTN AND
THIS DRIER AIR EXPECTED TO CONTINUE HEADING TO S AND TO SOME
DEGREE SW OVER NEXT 24 TO 36 HOURS.
CENTER OF THE UPPER HIGH NOW OVER FAR NE NM TODAY WILL SAG A BIT
FARTHER TO SW INTO OR VERY NEAR CENTRAL NM BY SAT AFTN. A SLIGHT
MOISTURE UPTICK MAY STILL OCCUR IN THE NW CORNER OF NM SAT...BUT
ELSEWHERE THE AIRMASS WILL SHOW LITTLE PWAT CHANGE AND IN MANY
CASES SOME DECREASE. LOWERED POPS A BIT MORE ACROSS MAINLY CENTRAL
AND NE NM FOR SAT GIVEN PWAT TREND OF TODAY SO FAR. EXPECT ANOTHER
VERY WARM TO HOT DAY IN EAST NM AGAIN SAT WITH UPPER 90S AND A FEW
TRIPLE DIGIT READINGS AGAIN. DECIDED TO GO AHEAD AT INCLUDE NEAR
RECORD TEMP HIGHLIGHTS IN HAZARD GRID FOR MUCH OF E CENTRAL AND NE
NM SAT.
HIGH PRESSURE WILL STAY OVER CENTRAL NM ON SUN...BUT HAVING LOST A
BIT OF STRENGTH. BACK DOOR COLD FRONT...FIRST IN QUITE SOME TIME...
TO DROP INTO NORTHEASTERN NM SUN MORN...SO SAY MAJORITY OF FCST
MODELS. IN ITS WAKE WILL COME HIGHER SFC DEWPOINTS AND SOME
UPSLOPE FORCING FOR A HEALTHY INCREASE IN SHOWER AND STORM ACTION
ALONG THE EAST SLOPES OF THE SANGRE DE CRISTOS AND INTO THE
NORTHEASTERN PLAINS. HAVE KEPT THE LIKELY POPS CATEGORY IN MUCH OF
THIS REGION...BUT TRIMMED ITS SOUTHERNMOST EXTENT JUST A HAIR.
WEAK STEERING FLOW WILL KEEP OVERALL MOVEMENT OF CELLS VERY SLOW...
BUT THAT MAY CAUSE ACTUAL OVERALL MOVEMENT TO BE MORE DRIVEN BY
FRONTAL MOVEMENT AND BOUNDARY INTERACTIONS.
THE FRONT WILL SURGE FARTHER SOUTH AND WEST SUN LATE AFTN AND
NIGHT...MOST LIKELY MAKING IT TO OR PERHAPS EVEN WEST OF THE
CONTINENTAL DIVIDE BY EARLY MON. SOME LEFTOVER UPSLOPE FLOW MAY
KEEP THINGS GOING ALONG THE CENTRAL MOUNTAIN CHAIN MONDAY...BUT
THE FOCUS MAY SHIFT TOWARD THE DIVIDE AND HIGH TERRAIN WEST OF THE
RIO GRANDE. SOME MODELS ARE LESSENING THEIR EARLIER FAVORING
THEIR MORE WESTWARD BIAS OF THE MON PCPN.
THERE IS STILL NO SIGNS OF THE UPPER HIGH BREAKING DOWN
SIGNIFICANTLY IN MID TO LATER PERIODS...THOUGH THE CENTER MAY EASE
A LITTLE WAYS OUT OF NM. GFS FAVORS AN EVEN STRONGER BACK DOOR
FRONT COMING INTO NM THE WEEKEND OF SEP 7TH...WHILE THE EUROPEAN
IS MUCH SLOWER AND WEAKER WITH IT...SHOWING IT STAYING NE OF THE
STATE THROUGH SUN NIGHT. 43
.FIRE WEATHER...
A DRIER AND MORE STABLE AIRMASS ALOFT HAS PUSHED OVER MORE OF THE
FORECAST AREA TODAY. SHOWERS AND THUNDERSTORMS ARE MUCH MORE MUTED
AS A RESULT. THE MAIN WETTING RAIN CHANCE WILL BE FOUND ALONG
AND WEST OF THE CONTINENTAL DIVIDE. TEMPERATURES ARE QUITE WARM
ACROSS THE EAST WITH NEAR RECORD LEVELS. HUMIDITY VALUES AS A RESULT
HAVE FALLEN INTO THE LOW/MID TEENS ACROSS THE NORTHEAST.
MODELS REMAIN CONSISTENT WITH THE DRIER AND MORE STABLE AIRMASS TO
REMAIN OVER MOST OF THE FORECAST AREA ON SATURDAY AS THE UPPER HIGH
CENTERS ITSELF OVER SOUTHERN NM. THE BEST WETTING RAIN POTENTIAL
WILL BE FOUND ACROSS THE NORTHWEST THIRD OR SO. THE MAIN MONSOONAL
PLUME WILL REMAIN OVER ARIZONA. NEAR RECORD HIGH TEMPERATURES ONCE
AGAIN POSSIBLE ACROSS THE NORTHEAST WITH ABOVE NORMAL TEMPERATURES
AREAWIDE DURING THE AFTERNOON. EXPECTING SOME TEEN HUMIDITY VALUES
ONCE AGAIN ACROSS THE NORTHEAST AND EAST CENTRAL AREAS. THIS WILL
ADD TO THE CURING GRASS PROCESS ACROSS THE EAST. A FEW SOUTHERLY
BREEZES...SIMILAR TO TODAY WILL BE FOUND ACROSS THE EAST.
THE UPPER HIGH IS EXPECTED TO WEAKEN SLIGHTLY AND MOVE NORTHWARD
SUNDAY INTO MONDAY. MODELS CONTINUE TO SHOW A MODERATELY STRONG BACK
DOOR COLD FRONT UNDERCUTTING THIS HIGH FROM THE EAST AND PUSHING
HIGHER SURFACE MOISTURE WESTWARD. WETTING RAINFALL COVERAGE SHOULD
INCREASE ACCORDINGLY...STARTING ACROSS THE NORTHEAST HALF ON SUNDAY
AND SPREADING INTO CENTRAL AND EVEN SOME WESTERN AREAS ON MONDAY.
MODELS STILL DIFFER A BIT ON THE RAINFALL COVERAGE ACROSS THE
EASTERN PLAINS ON MONDAY. SUSPECT IT WILL BE TOO STABLE THERE FOR
SIGNIFICANT ACTION BUT REALLY DEPENDENT ON THE STRENGTH OF THE BACK
DOOR COLD FRONT. IF IT COMES IN WEAKER THEN ALL BETS ARE OFF. EITHER
WAY...THE EASTERN PLAINS HAVE SOME POTENTIAL FOR WETTING RAIN AND
WOULD HELP EASE THE DRYING CONDITIONS THERE. GAP WINDS SHOULD
ENERGIZE ALONG THE CENTRAL MOUNTAINS SUNDAY NIGHT. HUMIDITY VALUES
WILL GO UP AREAWIDE WITH AN ACCOMPANYING COOLING EFFECT.
BASED ON THE LONGER RANGE MODELS...THE AREA SHOULD EXPERIENCE SOME
SORT OF RECYCLING MODE TUESDAY THROUGH THE END OF THE WEEK. DURING
THIS PERIOD...THE UPPER HIGH WOULD STRENGTHEN SLIGHTLY AND SLIDE A
LITTLE FURTHER TO THE NORTH. DRIER AND MORE STABLE AIR WOULD SLIDE
UNDERNEATH IT AND LOWER WETTING RAIN CHANCES. WILL CONTINUE TO
MONITOR MODEL TRENDS ON THIS BUT STARTING TO SEE RUN TO RUN
CONSISTENCY FOR THE DRIER SCENARIO AFTER MONDAY. TEMPERATURES WOULD WARM
AND HUMIDITY VALUES WOULD LOWER SOME AS A RESULT. VENTILATION RATES
WOULD VARY ACROSS THE AREA. READINGS APPEAR IN THE GRIDS AS BEING
THE LOWEST ON TUESDAY AND WEDNESDAY BUT SOME IMPROVEMENT EXPECTED AS
THE UPPER HIGH MIGRATES NORTHWARD DURING THE LATTER HALF OF THE
WEEK. 50
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
40
AREA FORECAST DISCUSSION...UPDATED
NWS ALBUQUERQUE NM
1131 PM MDT WED AUG 28 2013
.AVIATION...
06Z TAF CYCLE
LIGHT SHRA CONTINUES ACROSS THE SW MTNS AND LOWER RIO GRANDE
VALLEY. DOES NOT LOOK PROMISING FOR SHRA TO MAKE IT TO KABQ SO
HAVE REMOVED VCSH FOR NOW. OTHERWISE...LIGHT SHRA WILL CONTINUE
OVERNIGHT WITH MT TOPS OCCASIONALLY OBSCURED ACROSS THE SW MTNS.
PRECIP LOOKS TO FAVOR SIMILAR AREAS ON THURS. ISO-SCT -TSRA IS
EXPECTED ACROSS THE NRN MTS WHILE TS POTENTIAL WILL REMAIN
UNCERTAIN FOR AREAS SW OF A LINE FROM KGUP TO KSRR DUE TO REMNANT
CLOUD COVER AND INSTABILITY CONCERNS. IF TS CAN DEVELOP...MAIN
THREATS WILL BE HVY RAIN/LOW VSBY AS PRECIPITABLE WATER VALUES
REMAIN WELL ABOVE NORMAL FOR THE AREA.
34
&&
.PREV DISCUSSION...805 PM MDT WED AUG 28 2013...
WILL CANCEL FLASH FLOOD WATCH EARLY BASED ON LATEST RADAR RETURNS.
ADJUSTED POPS DOWN SOME OVER W AND CNTRL AREAS ACCORDINGLY. FFA
AND ZFP OUT SHORTLY. CHJ
.PREV DISCUSSION...255 PM MDT WED AUG 28 2013...
A DEEP SUBTROPICAL MOISTURE SURGE HAS ARRIVED OVER SOUTHERN NM AS A
WELL DEFINED INVERTED TROUGH SHIFTS SLOWLY NORTHWEST OF THE AREA.
CIRA BLENDED TOTAL PWAT VALUES ARE 150-175PCT OF NORMAL OVER THE
EL PASO AREA...AND THIS MOISTURE WILL ADVECT NORTH THRU TONIGHT ON
INCREASING 700-500MB SSE FLOW. ABUNDANT CLOUD COVER HAS LIMITED
CONVECTION ACROSS MUCH OF THE SOUTH THUS FAR HOWEVER A SLUG OF
NMRS SHRA/TSRA DEVELOPING AROUND I-10 AND IS SLIDING NORTH. LATEST
RUC AND HRRR SHOW THIS MASS OF PRECIP MOVING NORTH UP THE RGV AND
SOUTHERN HIGH TERRAIN INTO THIS EVENING BEFORE TAPERING OFF AFTER
MIDNIGHT. HAVE TIGHTENED UP POPS FURTHER WITH FOCUS OVER CATRON...
SOCORRO...AND LINCOLN COUNTIES.
CLOUD COVER ASSCD WITH THIS AREA OF PRECIP WILL LINGER INTO EARLY
THURSDAY AND LIKELY LIMIT CONVECTION AGAIN UNTIL LATE DAY WITHIN
ITS PERIPHERY. MODELS DO SHOW A SIMILAR FEATURE TMRW BUT FARTHER
NORTH WITH A MASS OF SHRA/TSRA SLIDING ACROSS THE SW HIGH TERRAIN
AND SOUTHERN PORTIONS OF THE NM CONT DVD THRU MID DAY. CONVECTION
SHOULD BE MORE WIDESPREAD FOR THE REMAINDER OF THE HIGH TERRAIN
AFT 3 OR 4 PM AS THETA-E RIDGE VALUES ARE HIGHER AND LIFTED INDICES
MORE UNSTABLE.
THE REAL JUICE AND FORCING MOVES INTO THE REGION FRIDAY THRU MONDAY
WITH PWAT VALUES AVERAGING AROUND 1.2 INCHES. FOCUS FOR CONVECTION
WILL BE OVER NORTHERN AND WESTERN NM FRIDAY...THEN OVER CENTRAL
AND NORTHERN NM FOR SATURDAY THROUGH MONDAY AS A BACK DOOR FRONTAL
BNDRY MOVES SW OVER THE AREA. LCL HEAVY RAIN THREAT WILL INCREASE
AND FLASH FLOOD WATCHES ARE POSSIBLE FOR AT LEAST BURN SCAR AREAS
THRU THE LABOR DAY HOLIDAY. FOLKS PLANNING OUTDOOR ACTIVITIES OVER
THE HOLIDAY WEEKEND SHOULD PREPARE FOR WET WEATHER. TEMPS IN THIS
PATTERN WILL BE CLOSER TO SEASONAL NORMALS. GUYER
.FIRE WEATHER...
BASED ON SATELLITE IMAGERY...ABUNDANT MOISTURE IS TRYING TO FLOW UP
FROM MEXICO. SOUTHERN PORTIONS OF THE AREA...ESPECIALLY SOCORRO
COUNTY WESTWARD WILL EXPERIENCE WETTING RAIN TODAY AND TONIGHT.
ISOLATED WETTING RAIN WILL BE FOUND FURTHER NORTH OVER THE NORTHWEST
AND NORTH CENTRAL MOUNTAINS. THE MID LEVEL DRY INTRUSION WHICH WAS
SQUARELY OVER THE FORECAST AREA YESTERDAY HAS SHIFTED
NORTH/NORTHEAST...THUS THE LOWEST HUMIDITY VALUES ARE FOUND THERE.
OVERALL...HUMIDITY VALUES HAVE TRENDED UP TODAY.
MOISTURE WILL CONTINUE TO MOVE NORTH AND WESTWARD ON THURSDAY. THIS
WILL SET THE STAGE FOR INCREASE WETTING RAIN COVERAGE CENTRAL
MOUNTAINS WESTWARD DURING THE AFTERNOON AND EVENING. A PRETTY DECENT
WETTING RAIN SIGNAL SHOWS UP ACROSS THE NORTHWEST AND WEST CENTRAL
HIGHLANDS. DRIER AND MORE STABLE AIR WILL BE FOUND OVER THE EASTERN
PLAINS. HUMIDITY VALUES FOR THE MOST PART WILL TREND UP EVEN MORE
ALTHOUGH LOWER SLIGHTLY ACROSS THE FAR EAST. HIGH TEMPERATURES WILL
BE ABOVE NORMAL NORTH AND EAST AS THE HIGH CENTER SHIFTS MORE OVER
PORTIONS OF THE SOUTHERN ROCKIES AND PLAINS INCLUDING OVER PARTS OF
NEW MEXICO. DUE TO THE PROXIMITY OF THE HIGH PRESSURE
ALOFT...VENTILATION RATES WILL LOWER ACROSS MOST OF THE AREA.
THE WEATHER MODELS DEPICT A BROAD HIGH PRESSURE AREA OVER THE DESERT
SOUTHWEST AND SOUTHERN ROCKIES FRIDAY INTO SATURDAY. SMALLER
ATMOSPHERIC WAVES WILL ROTATE AROUND THIS HIGH PRESSURE AREA AND
KICK OFF SCATTERED TO NUMEROUS WETTING THUNDERSTORMS. WESTERN AND
NORTHERN PORTIONS OF NM WILL MOST LIKELY EXPERIENCE THESE WAVES.
DRIER AND MORE STABLE AIR ALOFT WILL REMAINED CENTERED OVER EASTERN
NM. THE FLOW ALOFT WILL BE RATHER WEAK DURING THIS PERIOD SO SOME
POOR VENTILATION RATES SHOW UP IN AREAS. HIGH TEMPERATURES WILL
GENERALLY BE NEAR NORMAL WEST AND SEVERAL DEGREES ABOVE NORMAL EAST.
MINIMUM HUMIDITY VALUES WILL ALSO BE IN THE 20S EAST AND CANT RULE
OUT SOME UPPER TEENS. THUS CURING OF THE FINE OR GRASS FUELS WOULD MOST
LIKELY CONTINUE THERE.
BOTH THE GFS AND ECMWF MODELS SHOW AN UPTICK IN WETTING
THUNDERSTORMS OVER THE ENTIRE FORECAST AREA SUNDAY INTO EARLY NEXT
WEEK. THE UPPER HIGH WEAKENS SOME AND ALLOWS THE ATMOSPHERE TO
BECOME MORE UNSTABLE. ABUNDANT LOW LEVEL MOISTURE WOULD ALSO BEGIN
TO FILL IN ACROSS THE FORECAST AREA AND ALLOW FOR SCATTERED TO
NUMEROUS WETTING STORMS. THIS PERIOD COULD BECOME SOME SORT OF PSEUDO
MONSOON BURST EVENT. WILL CONTINUE TO MONITOR THE MODELS AND GET A
BETTER GAUGE FOR CONFIDENCE AS TIME GOES ON. CONDITIONS WOULD THEN
GRADUALLY IMPROVE SOME ACROSS THE EASTERN PLAINS. 50
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
751 PM EDT FRI AUG 30 2013
.SYNOPSIS...
THE LABOR DAY HOLIDAY WEEKEND WILL FEATURE WARM, HUMID AND
UNSETTLED WEATHER. SHOWERS AND THUNDERSTORMS ARE EXPECTED, BEING
MOST NUMEROUS SATURDAY AFTERNOON AND MONDAY. SOME OF THE
THUNDERSTORMS WILL BRING LOCALLY HEAVY DOWNPOURS. DRIER AND COOLER
WEATHER WILL RETURN FOR THE LATER HALF OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 750 PM EDT FRIDAY...COMPOSITE RADAR LOOP SHOWING MOST OF
THE RAIN SHOWERS AND SOME EMBEDDED THUNDERSTORMS MAINLY NORTH OF
THE BORDER IN CANADA AT THIS TIME. THESE ARE MOVING EAST...WITH
JUST A FEW SHOWERS ACROSS FAR NORTHERN VERMONT ALONG THE
INTERNATIONAL BORDER AT THIS TIME. OTHERWISE...MAINLY MID LEVEL
CLOUD COVER ACROSS THE REGION AT THIS TIME. SEEING MORE SHOWER AND
THUNDERSTORM ACTIVITY FURTHER UPSTREAM ACROSS SOUTHEAST ONTARIO
THAT IS WEST OF THE SAINT LAWRENCE VALLEY IN NORTHERN NEW YORK AT
THIS TIME. WILL LEAVE IN CHANCE POPS OVERNIGHT FOR RAIN SHOWERS OR
AN ISOLATED THUNDERSTORM. HAVE UPDATED THE GRIDS WITH THE LATEST
SURFACE DATA.
PREVIOUS DISCUSSION FROM 330 PM EDT FRIDAY...STILL MONITORING THE APPROACH
OF THE CONVECTIVE CLUSTER MOVING ACROSS EASTERN ONTARIO AND THE
GREAT LAKES. RADAR SHOWING A FEW SMALL T-STORMS DEVELOPING BETWEEN
MASSENA AND OTTAWA, WHICH IS ALSO AN AREA THAT LOCAL ANALYSIS
INDICATES IS MOST UNSTABLE (CAPE APPROACHING 2000 J/KG AND LIFTED
INDEX VALUES LESS THAN -4). ELSEWHERE ACROSS THE REGION, CAPE
VALUES ARE A LITTLE LOWER (1000-1500 J/KG) ALONG WITH SUB-ZERO
LIFTED INDEX VALUES. HOWEVER, HAVEN`T YET SEEN SHOWER DEVELOPMENT.
LIKELY DUE TO MID-LEVEL DRY AIR. HOWEVER WATER VAPOR SHOWS
INCREASING MOISTURE MOVING IN, SO WOULD THINK WE SHOULD BE ABLE TO
POP A FEW INSTABILITY SHOWERS YET THIS AFTERNOON. HAVE KEPT IN
SOME SMALL POPS FOR THE EARLY EVENING FOR THE HIGHER TERRAIN.
OTHERWISE, THE FORECAST REALLY HINGES ON HOW THE CONVECTIVE
CLUSTER WILL EVOLVE TONIGHT AS IT MOVES INTO OUR AREA. MODELS
CONTINUE TO STRUGGLE WITH ALL THE DETAILS, AND THIS LEADS TO LOW
CONFIDENCE IN OVERALL FORECAST DETAILS. DO THINK THE 15Z HRRR HAD
A DECENT HANDLE ON THINGS AND SO HAVE TRIED TO PAINT ITS SCENARIO
IN. BASICALLY ITS FOR CONVECTION TO REACH THE ST LAWRENCE VALLEY
ABOUT 5PM AND WORK ITS WAY EASTWARD DURING THE MID EVENING.
HOWEVER SHORTWAVE SUPPORT APPEARS TO BE WEAKENING AND WITH LOSS OF
SUN, CONVECTION SHOULD DIMINISH AFTER SUNSET AS IT GETS TOWARD
VERMONT. BY MIDNIGHT EXPECT A BROKEN BAND OF SHOWERS -- PERHAPS AN
ISOLATED THUNDERSHOWER -- TO BE DISSIPATING ACROSS THE REGION.
NOT LOOKING FOR ANYTHING STRONG OR SEVERE OR MUCH IN THE WAY OF
HEAVY RAIN (OUTSIDE LOCALIZED DOWNPOUR). SEMI-BROADBRUSHED THE
GRIDDED FORECAST AS SPECIFIC LOCATION AND TIMING IS STILL TOO FUZZY.
SKIES OVERNIGHT WILL TREND MOSTLY CLOUDY. THE DEBRIS CLOUDS WILL
KEEP TEMPERATURES IN THE 60S FOR PRETTY MUCH EVERYONE. ADD ON
DEWPOINTS IN THE 60S, IT WILL BE RATHER MUGGY. THE CLOUDS SHOULD
PRECLUDE MUCH IN THE WAY OF ANY DENSE FOG FROM FORMING.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
AS OF 330 PM EDT FRIDAY...SATURDAY THE REGION WILL BE SMACK DAB
IN THE CONTINUE WARM AIRMASS THAT WILL ALSO HAVE BECOME JUICED
FROM INCREASED MOISTURE. PRECIPITABLE WATER VALUES SHOULD BE UP
AROUND 1.75". A WEAK SURFACE BOUNDARY WILL BE STRUNG OUT JUST TO
OUR NORTH AND ADD IN OTHER WEAK BOUNDARIES FROM THE LEFTOVER
CONVECTIVE COMPLEX, WE WILL CERTAINLY HAVE PLENTY OF FOCUS
MECHANISMS FOR CONVECTIVE DEVELOPMENT. SHOULD BE ABLE TO SQUEAK
OUT A BIT OF SUNSHINE DURING THE MORNING, SO TEMPERATURES SHOULD
CLIMB QUICKLY THROUGH THE 70S AND PERHAPS INTO THE LOW 80S IN A
FEW SPOTS. THIS WILL PRODUCE ABUNDANT SURFACE BASED INSTABILITY
WITH CAPE VALUES OVER 1500 J/KG AND NEGATIVE LIFTED INDEX VALUES.
TOSS IN A LITTLE UPPER LEVEL ENERGY ZIPPING BY DURING MID- DAY,
AND ALL THE INGREDIENTS ARE IN PLACE FOR DEVELOPMENT OF WIDESPREAD
THUNDERSTORMS. WIND FIELDS ARE NOT ALL THAT STRONG, NOR IS THERE
MUCH SHEAR, SO THE STORMS WILL BE MORE DISORGANIZED BUT CAPABLE OF
PRODUCING SOME LOCALLY HEAVY DOWNPOURS. THIS COULD CAUSE A LITTLE
BIT OF MINOR FLOODING PROBLEMS.
SATURDAY NIGHT - STORMS SHOULD WIND DOWN IN THE EVENING, BUT LOTS
OF CLOUDS WILL REMAIN. ANOTHER WARM/MUGGY NIGHT WITH TEMPERATURES
IN THE MID-UPPER 60S FOR MOST OF US.
SUNDAY - LOOKS LIKE THE QUIETEST WEATHER FOR THE WEEKEND. THAT
SURFACE BOUNDARY SLIDES TO A POINT JUST SOUTH OF HERE, SO EVER SO
SLIGHTLY MORE STABLE CONDITIONS. NO IDENTIFIABLE TRIGGER ALOFT EITHER.
SO THAT SAID, SURFACE DEWPOINTS WILL STILL BE WELL INTO THE 60S,
SO ITS CONTINUED HUMID. SUNSHINE WILL AGAIN RESULT IN CONVECTION
STARTING TO BUBBLE UP BY MID-DAY. HAVE PAINTED INTO THE GRIDS
SCATTERED AFTERNOON SHOWERS/THUNDERSTORMS. COVERAGE WONT BE AS
STUPENDOUS AS ON SATURDAY AND MOST OF US MAY MANAGE TO STAY DRY.
SUNDAYS TEMPERATURES SHOULD RISE INTO THE LOWER TO PERHAPS 80S AS
SUNSHINE OFFSETS A SLIGHTLY COOLER AIRMASS (925MB TEMPERATURES
SHOULD BE 17-19C VS 20-22C THAT WERE OVERHEAD ON SATURDAY)
SUNDAY NIGHT - FAIRLY SIGNIFICANT UPPER TROUGH BEGINS TO DEVELOP
SOMEWHERE TO OUR WEST. SO ALTHOUGH ANY DAYTIME HEATING CONVECTION
SHOULD WIND DOWN IN THE EVENING, BY LATE NIGHT WE MAY SEE
SHOWERS/ISOLATED THUNDERSTORM RETURN TO THE AREA ALL THANKS TO
SOUTHERLY FLOW BECOMING DEEPER AND MORE ESTABLISHED. STILL A
SWEATY/WARM/MUGGY NIGHT WITH ALL THE CLOUDS AND HIGH DEWPOINTS.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 330 PM EDT FRIDAY...CHANGEABLE WEATHER EXPECTED THROUGH THE
EXTENDED FCST PERIOD AS THE PATTERN TRANSITIONS FROM A WARM AND
HUMID AIR MASS WITH WIDESPREAD SHOWERS AND TSTMS ON MONDAY TO
QUIET...DRY CONDITIONS AND BELOW AVERAGE TEMPERATURES BY THE END
OF THE WORK WEEK. IN FACT...CURRENT INDICATIONS ARE THAT THE FIRST
FROST OF THE SEASON IS POSSIBLE THURSDAY NIGHT OR FRIDAY NIGHT
ACROSS THE NRN ADIRONDACKS AND ESSEX COUNTY VT.
THE 12Z GFS REMAINS CONSISTENT WITH PREVIOUS RUNS SHOWING POTENTIAL
FOR WIDESPREAD SHOWERS AND THUNDERSTORMS MONDAY AFTN INTO MONDAY
EVENING. UPSTREAM 700-500MB SHORTWAVE TROUGH IS PROGGED TO AMPLIFY
ACROSS THE ERN GREAT LAKES REGION WITH INCREASING SWLY DEEP-LAYER
SHEAR TO 30-35 KTS ACROSS THE NORTH COUNTRY. PRE-EXISTING AIR MASS
SHOULD REMAIN MODERATELY HUMID WITH BOUNDARY LAYER DEWPOINTS IN THE
MID-UPR 60S AND HIGH TEMPS IN THE LOWER 80S IN VALLEY LOCATIONS.
THIS WILL CONTRIBUTE TO MODERATE SURFACE-BASED INSTABILITY WITH CAPE
VALUES 1000-2000 J/KG. MID-LEVEL LAPSE RATES AND LOW-LEVEL SHEAR NOT
GREAT...BUT OVERALL CONDITIONS FAVOR A FEW SVR STORMS MONDAY
AFTN/EARLY EVE WITH LOCALLY DAMAGING WINDS AND MARGINALLY SVR HAIL.
PW VALUES PEAK AROUND 1.70 INCHES 00Z TUESDAY AND SUPPORT LOCALLY
HEAVY DOWNPOURS WITH THE CONVECTIVE STORMS.
SURFACE TROUGH TRANSLATES EWD ACROSS THE AREA DURING MONDAY NIGHT
AND AS INSTABILITY DIMINISHING SHOULD SEE CONTINUED CHANCES FOR
SHOWER ACTIVITY...GRADUALLY LESSENING FROM WEST TO EAST OVERNIGHT.
NOT A FRONT...SO WITH LITTLE LOW-LEVEL CAA AND CONTINUED CLOUDS
SHOULD SEE LOWS MAINLY IN THE LOW-MID 60S.
LINGERING UPPER TROUGH ON TUESDAY...MAY GENERATE ISOLD/SCT SHOWERS
DURING THE AFTN HOURS. STILL WARM WITH HIGHS IN THE MID 70S TO NEAR
80...WITH SLIGHTLY LESS HUMIDITY. ONCE THE UPR TROUGH CLEARS THE
AREA LATE TUESDAY/TUESDAY NIGHT...SHOULD TRANSITION TO MOSTLY CLEAR
CONDITIONS. PROSPECTS GOOD FOR VALLEY FOG ON TUESDAY NIGHT/WED
MORNING AS A RESULT WITH LOWS IN THE 50S TO AROUND 60.
WED-FRI: WEDNESDAY...LOOKS DRY AND MOSTLY SUNNY WITH SW-NE ORIENTED
LOW-LEVEL RIDGE AXIS IN PLACE. SHOULD SEE NEAR SEASONABLE HIGHS IN
THE MID 70S. A COLD FRONT SLIDES SEWD ACROSS THE REGION ON
THURSDAY...AND SHOULD BE ASSOCIATED WITH A NARROW BAND OF SHOWERS
THURSDAY AFTN. SHOWING 30 POPS WITH THIS FEATURE FOR THURSDAY AFTN.
IN THE WAKE OF THE COLD FRONT...STRONGER CAA AND SHOULD SEE LOWS
DOWN INTO THE 40S THURSDAY NIGHT WITH HIGHS 62-68F ON FRIDAY. LARGER
SFC ANTICYCLONE BUILDS IN THU NIGHT THRU FRIDAY...AND OVERALL
PATTERN MAY ALLOW A FROST TO OCCUR THU NIGHT OR FRIDAY NIGHT IN THE
COLDER SPOTS WITHIN THE NRN ADIRONDACKS AND IN THE SHELTERED VALLEYS
OF THE NORTHEAST KINGDOM...ESPECIALLY IN ESSEX COUNTY VT. GOOD
POTENTIAL AGAIN FOR RIVER VALLEY FOG THURSDAY NIGHT AND FRIDAY
NIGHT BASED ON SYNOPTIC PATTERN AND ASSOCIATED CLIMATOLOGY.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
THROUGH 00Z SUNDAY...PRIMARILY VFR/MVFR EXPECTED THROUGH THE
PERIOD. VFR CONDITIONS SHOULD PREVAIL AT MOST TAF SITES THIS
EVENING AND OVERNIGHT. SOME SCATTERED RAIN SHOWERS AND PERHAPS AN
ISOLATED THUNDERSTORM MAY BRIEFLY REDUCE VISIBILITIES TO
MVFR...ESPECIALLY MSS THIS EVENING. COVERAGE OF RAIN SHOWERS WILL
LESSEN AFTER 06Z...ALTHOUGH THE CHANCE EXISTS THROUGH THE NIGHT.
SOME FOG/BR MAY ALSO DEVELOP...BUT WILL BE PATCHY AND SHORT-LIVED
WITH GENERALLY UNFAVORABLE FOG ENVIRONMENT. ADDITIONAL
SHOWERS/THUNDERSTORMS DEVELOP ON SATURDAY (ESPECIALLY 15Z ONWARD)...WITH
BRIEF PERIODS OF MVFR/IFR LIKELY...HOWEVER GIVEN EXPECTED
SCATTERED NATURE...WILL ONLY PUT VCSH IN TAFS FOR NOW. CEILINGS
WILL LOWER ON SATURDAY...WITH MVFR CEILINGS EXPECTED AT
SLK/MSS...ESPECIALLY IN THE AFTERNOON. GENERALLY LIGHT AND
VARIABLE WINDS TONIGHT TURN SOUTH/SOUTHWEST AT BTV/RUT/MPV/SLK
5-10 KNOTS WITH GUSTS UP TO 15 KNOTS ON SATURDAY. PBG WILL LIKELY
SEE A SOUTHEAST LAKE BREEZE DEVELOP...WITH A CHANNELED NORTHEAST
FLOW DEVELOPING AT MSS.
00Z SUNDAY THROUGH WEDNESDAY...SEVERAL ROUNDS OF SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE THRU THE AVIATION OUTLOOK PERIOD.
FIRST SFC/UPR TROUGH BRINGS WIDESPREAD SHOWERS AND T-STORMS INTO
SATURDAY EVENING. SHOULD SEE BRIEF INTERVALS OF MVFR AND POSSIBLE BRIEF
IFR AT ALL TAF LOCATIONS ASSOCIATED WITH THE CONVECTIVE ACTIVITY.
ANY PRECIPITATION SHOULD BE ISOLD SUNDAY...WITH MAINLY VFR
CONDITIONS DURING THE DAYLIGHT HRS. ANOTHER STRONG UPR TROUGH
APPROACHES THE REGION FROM THE WEST DURING MONDAY/MONDAY
NIGHT...LIKELY RESULTING IN NUMEROUS ADDITIONAL SHOWERS AND
TSTMS...ESPECIALLY MONDAY AFTN/EVE. DURING THESE HIGHER THREAT
PERIODS A FEW OF THE STORMS COULD TREND STRONG WITH GUSTY
WINDS/TURBULENCE/FRQ LIGHTNING. SCATTERED SHOWERS POSSIBLE TUESDAY
AND TRENDING DRIER FOR WEDNESDAY. PATCHY BR/FG AND ASSOC MVFR/IFR
CONDS ALSO POSSIBLE FROM 06-12Z EACH MORNING...WITH HIGHEST
CONFIDENCE AT MPV AND SLK.
&&
.EQUIPMENT...
AS OF 342 AM EDT FRIDAY...NOAA WEATHER RADIO STATION WXM 44...
BROADCASTING FROM THE TOP OF MOUNT ASCUTNEY VERMONT...REMAINS OFF
THE AIR UNTIL FURTHER NOTICE DUE TO A DAMAGED ANTENNA. REPLACEMENT
PARTS HAVE BEEN ORDERED...THOUGH IT STILL MAY BE UNTIL SEVERAL
WEEKS MORE BEFORE SERVICE IS RESTORED. WE APOLOGIZE FOR THE
INCONVENIENCE.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...NASH
NEAR TERM...WGH/NASH
SHORT TERM...NASH
LONG TERM...BANACOS
AVIATION...BANACOS/MUCCILLI
EQUIPMENT...WFO BTV
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
539 PM EDT THU AUG 29 2013
.SYNOPSIS...
A COLD FRONT WILL CONTINUE TO SLOWLY MOVE SOUTH THROUGH THE AREA
TONIGHT. HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTH
FRIDAY AND SATURDAY. THE HIGH WILL GRADUALLY SHIFT OFFSHORE WITH
ANOTHER COLD FRONT APPROACHING TUESDAY BEFORE MOVING OFFSHORE ON
WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 535 PM THURSDAY...THE FRONT ON SATELLITE AND RADAR IMAGERY
IS MOVING SOUTHWEST ACROSS EASTERN NC EARLY THIS EVENING AND @ 530
PM WAS LOCATED ROUGHLY ALONG A GREENVILLE TO TO NEWPORT LINE.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WERE OCCURRING ALONG AND
IN VICINITY OF THE BOUNDARY. THE HRRR MODEL WAS IN SYNC WITH
CURRENT RADAR TRENDS AND INDICATES THAT SHOWER THREAT WILL ENDING
SHORTLY AFTER 00Z AIDED BY LOSS OF SURFACE HEATING AND THE FRONT
MOVING OUT OF THE AREA. MODERATE NORTHEAST SURGE FOLLOWS THE FRONT
BUT IS FORECAST TO SUBSIDE AFTER MIDNIGHT WITH THE POTENTIAL FOR
PATCHY FOG IN AREAS THAT DECOUPLE. A MORE LIKELY SCENARIO IS THE
DEVELOPMENT OF WIDESPREAD LOW STRATUS CLOUDS AFTER 06Z AS THE
BOUNDARY LAYER FLOW REMAINS WELL MIXED ABOVE A SHALLOW
NOCTURNAL/FRONTAL INVERSION. FORECAST LOW TEMPERATURES WILL RANGE
FROM THE MIDDLE 60S INLAND TO THE LOWER 70S BEACHES.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
AS OF 245 PM THURSDAY...FRIDAY WILL BE CHARACTERIZED BY A SLIGHTLY
DRIER AIRMASS WITH WARM TEMPERATURES IN THE MIDDLE TO UPPER 80S
AWAY FROM THE IMMEDIATE COAST. DEWPOINTS WILL DROP INTO THE UPPER
60S WITH A LIGHT NORTHEAST WIND AS HIGH PRESSURE BUILDS SOUTH
ACROSS THE MID-ATLANTIC. MAY START THE DAY WITH SOME LOW STRATUS
BUT IT SHOULD DISSIPATE AS THE DRIER AIR STARTS TO MIX TO THE
SURFACE BY MID MORNING.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
AS OF 230 PM THU...HIGH PRESSURE WILL BE THE DOMINANT FEATURE
ACROSS THE AREA THIS WEEKEND INTO EARLY NEXT WEEK. HIGH PRESSURE
WILL TRANSITION OFF THE COAST SAT WHILE A BOUNDARY PUSHES BACK
NORTH OVER THE REGION BY LATE AFTERNOON AS A WEAK WARM FRONT.
LITTLE IF ANY PRECIP IS EXPECTED TO OCCUR AS BOUNDARY LAYER WILL
REMAIN DRY...THOUGH AN ISO SHOWER/STORM POSSIBLE INLAND WITH SEA
BREEZE PROPAGATION AND WILL MAINTAIN ISOLATED POPS SAT
AFTERNOON...WITH BEST CHANCES ACROSS SOUTHERN CWA. SW RETURN FLOW
INCREASES SUN BRINGING WARM/MOIST CONDITIONS BACK TO THE AREA WITH
FORECAST SOUNDINGS INDICATING PWATS NEAR 2 INCHES. WILL CONTINUE
LOW END CHANCE POPS INLAND AND SLIGHT E OF HWY 17.
BY MON AN UPPER LEVEL TROUGH OVER SOUTH CENTRAL CANADA WILL DIG
SOUTH AND EAST INTO THE GREAT LAKES REGION. SHORT WAVE ENERGY IN
BROAD SW FLOW WILL MOVE ACROSS THE REGION BRINGING A BETTER CHANCE
FOR ORGANIZED CONVECTION IN TANDEM WITH PIEDMONT TROUGH AND SEA
BREEZE...AND HAVE MAINTAINED CHANCE POPS ACROSS THE REGION. FOR
TUES...THE UPPER TROUGH WILL MOVE EAST FROM THE GREAT LAKES INTO
THE NORTHEASTERN STATES...DRAGGING A COLD FRONT THROUGH EASTERN NC
LATE TUE INTO TUE NIGHT. WILL CONTINUE GOOD CHANCE POPS TUE
TAPERING OFF BEHIND THE FRONT TUE NIGHT INTO WED. TEMPS THROUGH
THE PERIOD WILL BE NEAR CLIMO...WITH HIGHS GENERALLY IN THE MID
80S TO AROUND 90 DEGREES. THE WARMEST DAYS OF THE PERIOD LOOK LIKE
SUN AND MON. SLIGHTLY COOLER AND DRIER AIRMASS EXPECTED BEHIND THE
FRONT FOR WED/THU...THOUGH NO SIG TEMP SWINGS EXPECTED.
&&
.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
SHORT TERM /TONIGHT AND FRIDAY/...
AS OF 535 PM THURSDAY...SHOWER THREAT WILL ENDING AT THE TAF SITES
AROUND 00Z. MAIN CONCERN TONIGHT IS THE POTENTIAL FOR WIDESPREAD
IFR CONDITIONS. A MODERATE NORTHEAST SURGE IS OCCURRING BEHIND A
SOUTHWEST MOVING COLD FRONTAL BOUNDARY WHICH IS MOVING THROUGH THE
TAF SITES EARLY THIS EVENING. THIS SURGE IS EXPECTED TO SUBSIDE
AFTER 06Z AND ALONG WITH CLEARING BEHIND THE FRONT COULD LEAD TO
PATCHY FOG ESPECIALLY IN AREAS THAT RECEIVED RAINFALL AND WHERE
WINDS DECOUPLE. WHAT IS MORE LIKELY TO OCCUR IS THAT WIDESPREAD
STRATUS WILL DEVELOP AS THE BOUNDARY LAYER ABOVE THE SURFACE
REMAINS WELL MIXED OVERNIGHT. ALL OF THE AVIATION GUIDANCE FROM
BUFKIT TO THE UPS FOG TOOL TO THE MOS IS INDICATING IFR CEILINGS
AND/OR VISIBILITIES AFTER 06Z SO WILL CONTINUE TREND ESTABLISHED
IN PREVIOUS TAFS AND FORECAST IFR AROUND 08Z THROUGH 14Z FRIDAY.
VFR CONDITIONS THEN A FORECAST TO PREVAIL AFTER THE FOG/STRATUS
DISSIPATE AS HIGH PRESSURE AND DRIER AIR BUILD OVER THE REGION.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 230 PM THU...PRED VFR CONDITIONS EXPECTED THROUGH THE
PERIOD. A COLD FRONT WILL APPROACH FROM THE WEST MONDAY
NIGHT...MOVING THROUGH EASTERN NC LATE TUE AND TUE NIGHT. SCT
MAINLY DIURNAL SHOWERS/TSTMS POSSIBLE SUN THROUGH TUE WITH PERIODS
OF SUB-VFR POSSIBLE. WITH CALM TO LIGHT WINDS OVERNIGHT AND MOIST
BL...COULD SEE PATCHY FOG/STRATUS EACH NIGHT AND EARLY MORNING.
&&
.MARINE...
SHORT TERM /TONIGHT AND FRIDAY/...
AS OF 535 PM THURSDAY...COLD FRONT CONTINUES TO MOVE SOUTHWEST
THROUGH THE WATERS FOLLOWED BY A MODERATE NORTHEAST SURGE WITH
SUSTAINED WINDS TO 20 KT AND A FEW GUSTS TO 25 KT. THESE WINDS
WILL CONTINUE THROUGH THE EVENING THEN BEGIN TO SUBSIDE AFTER 06Z
AS THE GRADIENT RELAXES LATE. ON FRIDAY NORTHEAST WINDS AROUND 15
KT IN THE MORNING WILL SUBSIDE TO 10 KT LATE IN THE AFTERNOON. SEAS
WILL RANGE FROM 3 TO 5 FEET NORTH TO 2 TO 4 FEET SOUTH.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 230 PM THU...HIGH PRESSURE WILL BE THE DOMINANT FEATURE OVER
THE WATERS THIS WEEKEND INTO EARLY NEXT WEEK. OVERALL EXPECT
PLEASANT BOATING CONDITIONS THIS WEEKEND WITH VEERING WINDS 5-15KT
AND SEAS 2-4FT. A COLD FRONT WILL APPROACH THE WATERS FROM THE
WEST MON NIGHT INTO TUE...MOVING THROUGH TUE NIGHT INTO EARLY WED
MORNING. A BRIEF PERIOD OF SCA CONDITIONS WILL BE POSSIBLE MONDAY
EVENING...MAINLY FOR THE CENTRAL WATERS...AS GRADIENT TIGHTENS
AHEAD OF APPROACHING FRONT. SWLY WINDS EXPECTED TO INCREASE TO
15-20KT WITH SEAS BUILDING TO 6FT ACROSS THE OUTER CENTRAL WATERS.
SW FLOW 10-20KT WILL CONTINUE INTO TUE WITH SEAS 5FT OR LESS.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...CTC/JME
NEAR TERM...CTC/JME
SHORT TERM...CTC
LONG TERM...CQD
AVIATION...JME/CQD/LEP
MARINE...CTC/JME/CQD
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
330 PM EDT THU AUG 29 2013
.SYNOPSIS...
A COLD FRONT WILL MOVE THROUGH THE EASTERN CAROLINAS THIS EVENING
AS HIGH PRESSURE OVER THE MID-ATLANTIC STATES BUILDS IN. THE HIGH
WILL MOVE OFFSHORE SATURDAY ALLOWING A WARM FRONT TO RETURN
NORTHWARD SATURDAY AFTERNOON. HOT AND HUMID CONDITIONS ARE
EXPECTED NEXT WEEK...UNTIL A STRONGER COLD FRONT ARRIVES FROM THE
NORTH TUESDAY NIGHT OR WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 2 PM THURSDAY...COLD FRONT CONTINUES TO MAKE PROGRESS
SOUTHWARD AS IT EXTENDS WESTWARD FROM LOW PRESSURE CENTER
NORTHEAST OF CAPE HATTERAS. THE BEST CONVECTION AND LIGHTNING WITH
THIS SYSTEM REMAINS OUT OVER THE COASTAL WATERS EAST OF HATTERAS
CLOSE TO THE LOW AND WHERE BEST UPPER LEVEL SUPPORT EXISTS. AS
BOUNDARY SINKS SOUTH REACHING JUST NORTH OF LOCAL CWA...THE WINDS
WERE SHIFTING TO THE NORTH BEHIND IT AND A FEW SHOWERS WERE
STARTING TO POP UP JUST NORTH OF CWA AND STREAMING SOUTH. ALTHOUGH
THE WINDS WERE SHIFTING TO THE NORTH...THE DEWPOINT TEMPS WERE NOT
SHOWING MUCH OF A DROP WITH PLENTY OF MOISTURE AND CLOUDS WRAPPING
AROUND THE LOW WELL UP INTO THE MID ATLANTIC STATES THIS
AFTERNOON. EXPECT CLOUDS TO SPREAD SOUTH WITH INCREASING SHOWER
ACTIVITY AS FRONT DROPS THROUGH AREA THIS AFTERNOON INTO EARLY
THIS EVENING.
TEMPS IN THE MID TO UPPER 80S MOST PLACES BUT TAPERING OFF AS
CLOUDS SPREAD SOUTH. AREAS OF GREATER HEATING WILL AID IN
DESTABILIZING THE ATMOSPHERE MORE. LOOKING AT SOUNDING DATA AND
CONVECTIVE PARAMETERS...THE ML CAPE DOES INCREASE CLOSE TO 2000
J/KG WHILE DCAPES UP TO 1600 J/KG THIS AFTERNOON. THE OVERALL
PROFILE SHOWS FAIRLY DECENT DRY LAYER FROM THE SURFACE UP CLOSE TO
10 K FT. PCP WATER VALUES ACTUALLY DECREASE THROUGH THIS AFTERNOON
AS LAYER OF MOIST AIR BETWEEN 10 AND 20K FT GETS ERODED SOMEWHAT.
MID TO UPPER LEVELS REMAIN WARM WITH -5C TEMPS THIS AFTERNOON WITH
THE MID LEVEL LAPSE RATES REMAINING UNIMPRESSIVE AND MOISTURE
THROUGH THE COLUMN ACTUALLY DIMINISHES THROUGH THIS AFTERNOON.
ANOTHER FACTOR WILL BE THE ACTUAL FORCING MECHANISM TO INITIATE
ANY CONVECTION AS THE BEST MID TO UPPER LEVEL SUPPORT REMAINS
EAST OF MID TO UPPER TROUGH OVER THE ATLANTIC. A FEW MINOR
PERTURBATIONS IN THE MID TO UPPER LEVEL FLOW MAY ACT TO ENHANCE
SOME CONVECTIVE DEVELOPMENT...BUT OVERALL EXPECT BEST FORCING TO
COME FROM FRONT MOVING SOUTH AIDED BY CONVERGENCE ALONG SEA
BREEZE. THE SEA BREEZE SHOULD REMAINED PINNED CLOSER TO THE COAST
WITH A STRONGER W-SW FLOW. THE WESTERLY DOWNSLOPE COMPONENT TO THE
FLOW AHEAD OF THE FRONT WILL ALSO WORK AGAINST CONVECTIVE
DEVELOPMENT...BUT EXPECT MORE ISOLATED SHOWERS INLAND WITH BETTER
CONVECTIVE DEVELOPMENT AS FRONT INTERACTS WITH SEA BREEZE CLOSER
TO THE COAST...ESPECIALLY FROM CAPE FEAR SOUTH INTO NORTHEAST
SOUTH CAROLINA. MAIN ACTIVITY STILL FORECAST TO OCCUR AS FRONT
DROPS SOUTH AND INTERACTS WITH SEA BREEZE BETWEEN 2 PM TO 5 PM
OVER CAPE FEAR AND CONTINUING SOUTH MOVING OVER SOUTH CAROLINA
THROUGH THE LATE AFTERNOON INTO EARLY THIS EVENING. ALTHOUGH NOT
EXPECTING VERY WIDESPREAD OR DEEP CONVECTION...A FEW STORMS COULD
POTENTIALLY PRODUCE SOME VERY GUSTY WINDS INDICATIVE OF INVERTED-V
SOUNDING PROFILE AND DCAPES OF 1600 J/KG.
AS THE FRONT MOVES TO THE SOUTH OF THE SOUTH SANTEE RIVER DURING
THE LATE EVENING HOURS AND WINDS SHIFT AROUND TO THE NORTH TO
NORTHEAST...MORE STABLE AIR WILL ARRIVE FROM THE NORTH. THE RELATIVELY
COOLER AIR MAKING ITS WAY IN BEHIND THE FRONT COMBINING WITH
LINGERING MOISTURE AND EASTERLY COMPONENT TO THE FLOW COULD
PRODUCE SOME STRATUS AND FOG OVERNIGHT. LOWS TONIGHT WILL BE A
LITTLE TRICKY AS DEWPOINT TEMPS DROP TO THE MID 60S BUT CLOUDS AND
MOISTURE MAY LINGER IN LOW LEVELS. WILL HOLD MOST LOW TEMPS CLOSER
TO 70 WITH SOME 60S OVER NORTHERN TIER COUNTIES AS COOLER AND
DRIER AIR ADVECTS IN FROM THE NORTH.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 PM THURSDAY...THE UPPER RIDGE ACROSS THE PLAINS STATES
WILL WEAKEN AND RETROGRADE INTO THE DESERT SOUTHWEST LATE THIS
WEEK AS A SERIES OF SHORTWAVE TROUGHS ERODE HEIGHTS ACROSS THE
NORTHERN PLAINS...GREAT LAKES AND NORTHEASTERN STATES. AT THE
SURFACE THE COLD FRONT SHOULD MAKE IT DOWN TO ALMOST THE FLORIDA-
GEORGIA STATE LINE FRIDAY AFTERNOON. SURFACE HIGH PRESSURE OFF
THE MD/DE COAST WILL MAINTAIN A NE LOW-LEVEL FLOW ACROSS THE
EASTERN CAROLINAS. ALTHOUGH THIS IS NOT A COOL DRY AIRMASS...
THETA-E VALUES SHOULD FALL JUST ENOUGH TO MAKE DAYTIME CONVECTION
ONLY ISOLATED AT BEST ACROSS EASTERN SOUTH CAROLINA FRIDAY.
AS THE HIGH MOVES FARTHER OFF THE MID-ATLANTIC COAST SATURDAY THE
FRONT WILL BE DRAWN NORTHWARD...LIKELY MOVING BACK ACROSS THE AREA
SATURDAY AFTERNOON. ISOLATED SHOWERS ARE AGAIN POSSIBLE BUT
COVERAGE SHOULD BE LIMITED BY VERY DRY AIR ALOFT WITH MID-LEVEL
RIDGING PERSISTING. THE APPROACH OF THE TAIL END OF AN UPPER
DISTURBANCE SATURDAY NIGHT COULD LEAD TO AN INCREASE IN SHOWER
CHANCES...ESPECIALLY OFFSHORE AND PERHAPS NEAR THE COAST.
GFS AND NAM MOS ARE IN GOOD AGREEMENT WITH HIGH AND LOW
TEMPERATURES THROUGH THE NEXT SEVERAL PERIODS...AND BOTH AGREE
WITH FORECAST SOUNDING-DERIVED TECHNIQUES. UNLIKE YESTERDAY EVEN
THE EXPERIMENTAL ECMWF MOS IS IN THE BALLPARK FRIDAY THROUGH
SATURDAY NIGHT.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 3 PM THURSDAY...WITH AN EASTWARD PROPAGATING UPPER LEVEL
TROUGH APPROACHING THE AREA JUST AHEAD OF THE UPCOMING COLD FRONTAL
PASSAGE...PRECIPITABLE WATER VALUES WILL STEADILY INCREASE TO UP
NEAR 2 INCHES BEGINNING SUNDAY AFTERNOON/EVENING AS SOUTHWEST FLOW
CONTINUES. THIS WILL ALLOW FOR MOIST AND WARM CONDITIONS FROM THE
GULF OF MEXICO TO INFILTRATE INTO THE AREA...AND AS A RESULT...WILL
INCREASE SHOWER AND THUNDERSTORM CHANCES SUNDAY THROUGH TUESDAY.
LATEST GUIDANCES HAS THE COLD FRONT PUSHING THROUGH THE FORECAST
AREA TUESDAY AFTERNOON AND INTO THE EVENING HOURS WITH SFC HIGH
PRESSURE QUICKLY BUILDING IN BEHIND. WITH DRIER AIR SUBSTANTIALLY
DECREASING PRECIPITABLE WATER VALUES...HAVE KEPT WITH THE DRYING
TREND AND THUS HAVE MUCH LOWER POPS WEDNESDAY AND THURSDAY.
AS FOR TEMPERATURES...UPPER 80S TO LOWER 90S ARE EXPECTED SUNDAY
THROUGH TUESDAY...KEEPING THE VALUES JUST ABOVE CLIMATOLOGY. WITH
THE PASSAGE OF THE FRONT...THEY WILL DROP TO NEAR-CLIMATOLOGY...WITH
MAINLY MID TO UPPER 80S ACROSS THE BOARD. OVERNIGHT LOWS WILL REMAIN
IN THE LOWER 70S...DROPPING UPPER 60S/NEAR 70 BEHIND THE
FRONT...JUST ON THE CUSP OF CLIMATOLOGY.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 18Z...A COLD FRONT DROPPING SOUTHWARD ALONG WITH SEA BREEZE
INTERACTIONS WILL PROVIDE THE FOCUS FOR ISO/SCT CONVECTION ALONG
THE COAST THIS AFTN. HAVE INCLUDED PREVAILING VCTS FOR KILM...KCRE
AND KMYR WITH TEMPO TSRA BASED ON THE LATEST HRRR TRENDS. BRIEF
PERIODS OF MVFR/IFR VSBYS AND GUSTY WINDS ARE POSSIBLE WITH
SHOWERS/T-STORMS THAT MOVE DIRECTLY OVER A TAF SITE. DRIER MID-
LEVEL AIR INLAND SHOULD LIMIT THE THREAT OF DEEP CONVECTION FOR
KLBT/KFLO...SO HAVE CHOSEN NOT TO MENTION PCPN ATTM. WEST WINDS
AROUND 10 KTS WILL VEER TO THE NORTHWEST LATER TODAY AND THEN THE
NORTHEAST FOLLOWING FROPA. THE FRONT SHOULD CLEAR OUR SOUTHERN
TERMS AROUND OR JUST AFTER 00Z. GFS FCST SOUNDINGS DEPICT POST-
FRONTAL MVFR/IFR CIGS DEVELOPING EARLY FRIDAY...SO HAVE INCLUDED
PREVAILING MVFR CIGS BEFORE 12Z. BEST CHANCES FOR IFR WOULD BE AT
KLBT/KILM...BUT CONFIDENCE IS LOW ATTM. VFR SHOULD PREVAIL DURING
THE DAY ON FRIDAY WITH E-NE WINDS AROUND 10 KTS.
EXTENDED OUTLOOK...EARLY MORNING IFR/MVFR CIGS/VSBYS POSSIBLE ON
SATURDAY...ESPECIALLY INLAND AT KLBT/KFLO. SCATTERED SHRA/TSRA
POSSIBLE MONDAY AND TUESDAY. OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 2 PM THURSDAY...AN EAST-WEST ORIENTED FRONT WILL SINK SOUTH
THROUGH THE WATERS THIS AFTERNOON INTO THIS EVENING. SOUTHWEST
WINDS WILL REMAIN IN PLACE AHEAD OF THE FRONT BUT WILL DECREASE
THROUGH THIS AFTERNOON AS THEY VEER AROUND TO MORE WESTERLY JUST AHEAD
OF THE COLD FRONT. OVERALL EXPECT SW TO W WINDS 10 TO 15 KTS WITH
HIGHER GUSTS AHEAD OF FRONT MAKING A SHARP TRANSITION TO THE NORTH
BEHIND THE FRONT.
THE COLD FRONT WILL REACH THE NORTHERN WATERS BY MID AND LATE
AFTERNOON AND SHOULD DROP SOUTH OF SOUTHERNMOST WATERS BY LATE
THIS EVE. WINDS WILL SHIFT TO THE N AND THEN NE LATER TONIGHT AS A
NE SURGE MOVES DOWN THE COAST AND ACROSS THE WATERS. SUSTAINED
WINDS WILL INCREASE TO AROUND 15 KT WITH HIGHER GUSTS OVERNIGHT
AND THIS WILL ALLOW SEAS TO BUILD. AT THIS TIME...WILL CAP SEAS AT
4 FT...BUT SOME 5 FOOTERS MAY DEVELOP BY FRI MORNING ACROSS
PORTIONS OF THE OUTERMOST WATERS.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 PM THURSDAY...ALL MODELS SHOW THE SURFACE COLD FRONT
SHOULD BE SOUTH OF GEORGETOWN SC BY FRIDAY MORNING...WITH
NORTHEAST WINDS BEING PRODUCED BY HIGH PRESSURE ACROSS THE MID-
ATLANTIC WATERS. THESE WINDS SHOULD REACH A SOLID 15 KNOTS DURING
THE DAY FRIDAY...VEERING MORE EASTERLY AND DIMINISHING TO AROUND
10 KNOTS FRIDAY NIGHT. UNFORTUNATELY A SHORT-PERIOD CHOP AS HIGH
AS 3-4 FEET SHOULD ACCOMPANY THE WINDS FRIDAY...DIMINISHING DOWN
TOWARD 2 FEET SATURDAY. THE FRONT WILL BEGIN TO RETURN NORTH
SATURDAY WITH LIGHT WINDS TURNING SOUTHERLY BY SATURDAY NIGHT AS
THE FRONT MOVES THROUGH.
LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 3 PM THURSDAY...SOUTHWEST FLOW WILL CONTINUE ACROSS THE
WATERS INTO EARLY TUESDAY AHEAD OF AN APPROACHING COLD FRONT...WITH
SUSTAINED WINDS AROUND 10 TO 15 KTS...INCREASING UP TO 20 KTS INTO
MONDAY AND TUESDAY. OVERALL SEAS WILL RANGE FROM 2 TO 4 FEET SUNDAY
AND MONDAY...THOUGH LATEST MODELS ILLUSTRATE 5 FT SEAS POSSIBLE JUST
ON THE CUSP OF THE FORECAST AREA OUT 20 NM. AS THE FRONT PUSHES
CLOSER...CONDITIONS COULD WARRANT A SCEC...BUT HAVE NOT INTRODUCED
ONE ATTM.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TRA
NEAR TERM...RGZ
SHORT TERM...TRA
LONG TERM...SGL
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
254 PM EDT THU AUG 29 2013
.SYNOPSIS...
A COLD FRONT WILL CONTINUE TO SLOWLY MOVE SOUTH TONIGHT. HIGH PRESSURE
WILL BUILD INTO THE REGION FROM THE NORTH FRIDAY AND SATURDAY. THE
HIGH WILL GRADUALLY SHIFT OFFSHORE WITH ANOTHER COLD FRONT APPROACHING
TUESDAY BEFORE MOVING OFFSHORE ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 245 PM THURSDAY...AS ADVERTISED BY THE 3KM HRRR MODEL AND
OTHER HIGH RESOLUTION MODELS...PATCHY SHOWERS HAVE DEVELOPED NEAR
THE ALBEMARLE SOUND REGION AND ARE MOVING/SPREADING SOUTH AND
SOUTHWEST. WHILE THERE IS SOME MODERATE INSTABILITY...NO THUNDER
HAS BEEN OBSERVED AS MORNING CLOUD COVER LIKELY CUT DOWN ON ANY
WIDESPREAD CONVECTIVE POTENTIAL THIS EVENING. WITH PRECIPITABLE
WATER VALUES STILL AROUND 2 INCHES...THERE WILL BE SOME BRIEF
DOWNPOURS WITH THESE SHOWERS. GOOD AGREEMENT AMONGST THE VARIOUS
SHORT TERM MODELS THAT PRECIPITATION WILL WANE QUICKLY BEFORE
MIDNIGHT. WITH A LOW-LEVEL NORTHEAST FLOW...EXPECT STRATUS TO
BE LIKELY OVERNIGHT. LOW TEMPERATURES WILL GENERALLY BY IN THE 68
TO 72 DEGREE RANGE.
&&
.SHORT TERM /FRIDAY/...
AS OF 245 PM THURSDAY...FRIDAY WILL BE CHARACTERIZED BY A SLIGHTLY
DRIER AIRMASS WITH WARM TEMPERATURES IN THE MIDDLE TO UPPER 80S
AWAY FROM THE IMMEDIATE COAST. DEWPOINTS WILL DROP INTO THE UPPER
60S WITH A LIGHT NORTHEAST WIND AS HIGH PRESSURE BUILDS SOUTH
ACROSS THE MID-ATLANTIC. MAY START THE DAY WITH SOME LOW STRATUS
BUT IT SHOULD DISSIPATE AS THE DRIER AIR STARTS TO MIX TO THE
SURFACE BY MID MORNING.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
AS OF 230 PM THU...HIGH PRESSURE WILL BE THE DOMINANT FEATURE
ACROSS THE AREA THIS WEEKEND INTO EARLY NEXT WEEK. HIGH PRESSURE
WILL TRANSITION OFF THE COAST SAT WHILE A BOUNDARY PUSHES BACK
NORTH OVER THE REGION BY LATE AFTERNOON AS A WEAK WARM FRONT.
LITTLE IF ANY PRECIP IS EXPECTED TO OCCUR AS BOUNDARY LAYER WILL
REMAIN DRY...THOUGH AN ISO SHOWER/STORM POSSIBLE INLAND WITH SEA
BREEZE PROPAGATION AND WILL MAINTAIN ISOLATED POPS SAT
AFTERNOON...WITH BEST CHANCES ACROSS SOUTHERN CWA. SW RETURN FLOW
INCREASES SUN BRINGING WARM/MOIST CONDITIONS BACK TO THE AREA WITH
FORECAST SOUNDINGS INDICATING PWATS NEAR 2 INCHES. WILL CONTINUE
LOW END CHANCE POPS INLAND AND SLIGHT E OF HWY 17.
BY MON AN UPPER LEVEL TROUGH OVER SOUTH CENTRAL CANADA WILL DIG
SOUTH AND EAST INTO THE GREAT LAKES REGION. SHORT WAVE ENERGY IN
BROAD SW FLOW WILL MOVE ACROSS THE REGION BRINGING A BETTER CHANCE
FOR ORGANIZED CONVECTION IN TANDEM WITH PIEDMONT TROUGH AND SEA
BREEZE...AND HAVE MAINTAINED CHANCE POPS ACROSS THE REGION. FOR
TUES...THE UPPER TROUGH WILL MOVE EAST FROM THE GREAT LAKES INTO
THE NORTHEASTERN STATES...DRAGGING A COLD FRONT THROUGH EASTERN NC
LATE TUE INTO TUE NIGHT. WILL CONTINUE GOOD CHANCE POPS TUE
TAPERING OFF BEHIND THE FRONT TUE NIGHT INTO WED. TEMPS THROUGH
THE PERIOD WILL BE NEAR CLIMO...WITH HIGHS GENERALLY IN THE MID
80S TO AROUND 90 DEGREES. THE WARMEST DAYS OF THE PERIOD LOOK LIKE
SUN AND MON. SLIGHTLY COOLER AND DRIER AIRMASS EXPECTED BEHIND THE
FRONT FOR WED/THU...THOUGH NO SIG TEMP SWINGS EXPECTED.
&&
.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
SHORT TERM /TONIGHT AND FRIDAY/...
VFR/MVFR CONDITIONS ARE EXPECTED THROUGH THE REMAINDER OF
THE AFTERNOON AS A WEAK COLD FRONT SINKS FURTHER SOUTH.
SUFFICIENT LOW/MID LEVEL MOISTURE IS STILL IN PLACE WITH BKN
CEILINGS ACROSS MUCH OF THE AREA. LIGHT NORTHERLY FLOW WILL DIMINISH
OVERNIGHT WITH ATMOSPHERIC DRYING TAKING SHAPE. HOWEVER...GIVEN
CALM CONDITIONS AT THE SFC AND TEMPERATURES DROPPING A FEW DEGREES
BELOW THE CROSS OVER TEMP...FEEL FOG AND ESPECIALLY STRATUS WILL BE
AN ISSUE OVERNIGHT. ANTICIPATE MOST LOCATIONS TO DROP TO IFR
CIGS/MVFR CIGS...WITH THE POSSIBILITY OF DROPPING TO LIFR IN SOME
LOCATIONS...LIKELY BETWEEN 9-12Z. GIVEN SLOW MIXING IN THE
MORNING...MIGHT TAKE SOME TIME TO SCATTER OUT ANY LOW LEVEL MOISTURE
ACROSS THE REGION. VFR CONDITIONS ARE EXPECTED THROUGH TOMORROW
WITH DIURNAL CU FORMATION UNDER NELY FLOW.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 230 PM THU...PRED VFR CONDITIONS EXPECTED THROUGH THE
PERIOD. A COLD FRONT WILL APPROACH FROM THE WEST MONDAY
NIGHT...MOVING THROUGH EASTERN NC LATE TUE AND TUE NIGHT. SCT
MAINLY DIURNAL SHOWERS/TSTMS POSSIBLE SUN THROUGH TUE WITH PERIODS
OF SUB-VFR POSSIBLE. WITH CALM TO LIGHT WINDS OVERNIGHT AND MOIST
BL...COULD SEE PATCHY FOG/STRATUS EACH NIGHT AND EARLY MORNING.
&&
.MARINE...
SHORT TERM /TONIGHT AND FRIDAY/...
AS OF 255 PM THURSDAY...AS COLD FRONT SINKS SOUTH OF THE REGION
OVER THE NEXT FEW HOURS...AM SEEING A BIT OF A CAA SURGE. NE WINDS
AROUND GUSTING TO AROUND 20 KNOTS OVER THE SOUNDS AND NORTHERN
WATERS. THIS SURGE WILL MOVE SOUTH OVER THE NEXT FEW HOURS BEFORE
SUBSIDING LATE TONIGHT. LATEST LOCAL NWPS MODEL KEEPS SEAS AT 5
FEET OR BELOW. WINDS SHOULD GENERALLY BE NE AT 10 TO 15 KNOTS
AREA-WIDE ON FRIDAY...SEAS WILL RANGE FROM 3 TO 5 FEET NORTH TO 2
TO 4 FEET SOUTH.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 230 PM THU...HIGH PRESSURE WILL BE THE DOMINANT FEATURE OVER
THE WATERS THIS WEEKEND INTO EARLY NEXT WEEK. OVERALL EXPECT
PLEASANT BOATING CONDITIONS THIS WEEKEND WITH VEERING WINDS 5-15KT
AND SEAS 2-4FT. A COLD FRONT WILL APPROACH THE WATERS FROM THE
WEST MON NIGHT INTO TUE...MOVING THROUGH TUE NIGHT INTO EARLY WED
MORNING. A BRIEF PERIOD OF SCA CONDITIONS WILL BE POSSIBLE MONDAY
EVENING...MAINLY FOR THE CENTRAL WATERS...AS GRADIENT TIGHTENS
AHEAD OF APPROACHING FRONT. SWLY WINDS EXPECTED TO INCREASE TO
15-20KT WITH SEAS BUILDING TO 6FT ACROSS THE OUTER CENTRAL WATERS.
SW FLOW 10-20KT WILL CONTINUE INTO TUE WITH SEAS 5FT OR LESS.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...CTC
NEAR TERM...CTC
SHORT TERM...CTC
LONG TERM...CQD
AVIATION...CQD/LEP
MARINE...CTC/CQD
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
213 PM EDT THU AUG 29 2013
.SYNOPSIS...
A COLD FRONT WILL MOVE ACROSS THE AREA...FROM NORTH TO
SOUTH...THROUGH THIS EVENING. HIGH PRESSURE WILL BUILD IN BEHIND
THE FRONT FOR THE WEEKEND. THE FRONT WILL RETURN NORTH DURING THE
WEEKEND WITH HOT AND HUMID CONDITIONS DEVELOPING EARLY NEXT WEEK.
A STRONGER COLD FRONT WILL ARRIVE FROM THE NORTH TUESDAY OR
WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 2 PM THURSDAY...COLD FRONT CONTINUES TO MAKE PROGRESS
SOUTHWARD AS IT EXTENDS WESTWARD FROM LOW PRESSURE CENTER
NORTHEAST OF CAPE HATTERAS. THE BEST CONVECTION AND LIGHTNING WITH
THIS SYSTEM REMAINS OUT OVER THE COASTAL WATERS EAST OF HATTERAS
CLOSE TO THE LOW AND WHERE BEST UPPER LEVEL SUPPORT EXISTS. AS
BOUNDARY SINKS SOUTH REACHING JUST NORTH OF LOCAL CWA...THE WINDS
WERE SHIFTING TO THE NORTH BEHIND IT AND A FEW SHOWERS WERE
STARTING TO POP UP JUST NORTH OF CWA AND STREAMING SOUTH. ALTHOUGH
THE WINDS WERE SHIFTING TO THE NORTH...THE DEWPOINT TEMPS WERE NOT
SHOWING MUCH OF A DROP WITH PLENTY OF MOISTURE AND CLOUDS WRAPPING
AROUND THE LOW WELL UP INTO THE MID ATLANTIC STATES THIS
AFTERNOON. EXPECT CLOUDS TO SPREAD SOUTH WITH INCREASING SHOWER
ACTIVITY AS FRONT DROPS THROUGH AREA THIS AFTERNOON INTO EARLY
THIS EVENING.
TEMPS IN THE MID TO UPPER 80S MOST PLACES BUT TAPERING OFF AS
CLOUDS SPREAD SOUTH. AREAS OF GREATER HEATING WILL AID IN
DESTABILIZING THE ATMOSPHERE MORE. LOOKING AT SOUNDING DATA AND
CONVECTIVE PARAMETERS...THE ML CAPE DOES INCREASE CLOSE TO 2000
J/KG WHILE DCAPES UP TO 1600 J/KG THIS AFTERNOON. THE OVERALL
PROFILE SHOWS FAIRLY DECENT DRY LAYER FROM THE SURFACE UP CLOSE TO
10 K FT. PCP WATER VALUES ACTUALLY DECREASE THROUGH THIS AFTERNOON
AS LAYER OF MOIST AIR BETWEEN 10 AND 20K FT GETS ERODED SOMEWHAT.
MID TO UPPER LEVELS REMAIN WARM WITH -5C TEMPS THIS AFTERNOON WITH
THE MID LEVEL LAPSE RATES REMAINING UNIMPRESSIVE AND MOISTURE
THROUGH THE COLUMN ACTUALLY DIMINISHES THROUGH THIS AFTERNOON.
ANOTHER FACTOR WILL BE THE ACTUAL FORCING MECHANISM TO INITIATE
ANY CONVECTION AS THE BEST MID TO UPPER LEVEL SUPPORT REMAINS
EAST OF MID TO UPPER TROUGH OVER THE ATLANTIC. A FEW MINOR
PERTURBATIONS IN THE MID TO UPPER LEVEL FLOW MAY ACT TO ENHANCE
SOME CONVECTIVE DEVELOPMENT...BUT OVERALL EXPECT BEST FORCING TO
COME FROM FRONT MOVING SOUTH AIDED BY CONVERGENCE ALONG SEA
BREEZE. THE SEA BREEZE SHOULD REMAINED PINNED CLOSER TO THE COAST
WITH A STRONGER W-SW FLOW. THE WESTERLY DOWNSLOPE COMPONENT TO THE
FLOW AHEAD OF THE FRONT WILL ALSO WORK AGAINST CONVECTIVE
DEVELOPMENT....BUT EXPECT MORE ISOLATED SHOWERS INLAND WITH BETTER
CONVECTIVE DEVELOPMENT AS FRONT INTERACTS WITH SEA BREEZE CLOSER
TO THE COAST....ESPECIALLY FROM CAPE FEAR SOUTH INTO NORTHEAST
SOUTH CAROLINA. MAIN ACTIVITY STILL FORECAST TO OCCUR AS FRONT
DROPS SOUTH AND INTERACTS WITH SEA BREEZE BETWEEN 2 PM TO 5 PM
OVER CAPE FEAR AND CONTINUING SOUTH MOVING OVER SOUTH CAROLINA
THROUGH THE LATE AFTERNOON INTO EARLY THIS EVENING. ALTHOUGH NOT
EXPECTING VERY WIDESPREAD OR DEEP CONVECTION...A FEW STORMS COULD
POTENTIALLY PRODUCE SOME VERY GUSTY WINDS INDICATIVE OF INVERTED-V
SOUNDING PROFILE AND DCAPES OF 1600 J/KG.
AS THE FRONT MOVES TO THE SOUTH OF THE SOUTH SANTEE RIVER DURING
THE LATE EVENING HOURS AND WINDS SHIFT AROUND TO THE NORTH TO
NORTHEAST...MORE STABLE AIR WILL ARRIVE FROM THE NORTH. THE RELATIVELY
COOLER AIR MAKING ITS WAY IN BEHIND THE FRONT COMBINING WITH
LINGERING MOISTURE AND EASTERLY COMPONENT TO THE FLOW COULD
PRODUCE SOME STRATUS AND FOG OVERNIGHT. LOWS TONIGHT WILL BE A
LITTLE TRICKY AS DEWPOINT TEMPS DROP TO THE MID 60S BUT CLOUDS AND
MOISTURE MAY LINGER IN LOW LEVELS. WILL HOLD MOST LOW TEMPS CLOSER
TO 70 WITH SOME 60S OVER NORTHERN TIER COUNTIES AS COOLER AND
DRIER AIR ADVECTS IN FROM THE NORTH.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...DISSIPATING FRONT WILL REMAIN STALLED SOUTH OF
THE AREA FRI AS DRIER HIGH PRESSURE TO THE NORTH WEAKLY BUILDS
SOUTH. LARGE AREA OF DEEP DRY AIR...PWATS UNDER 1.5 INCH...AND WEAK
MID LEVEL CAP WILL KEEP MOST OF THE AREA DRY. THE EXCEPTION ON FRI
COULD BE SOUTHERN SC COUNTIES. THE FRONT WILL BE IN CLOSE PROXIMITY
TO DEEPER MOISTURE AND COULD HELP GENERATE SOME ISOLATED AFTERNOON
CONVECTION.
WHAT IS LEFT OF THE STALLED FRONT SAT MORNING WILL LIFT NORTH AS
BERMUDA HIGH BUILDS BACK IN FROM THE EAST. THE RESULTING SOUTHERLY
FLOW WILL HELP WARM/MOISTEN THE LOW LEVELS BUT DRY AIR AND
WEST-NORTHWEST FLOW ALOFT WILL AGAIN CONTRIBUTE TO LIMITED COVERAGE
OF AFTERNOON CONVECTION. ILL DEFINED MID LEVEL PATTERN AND LACK OF
SIGNIFICANT FORCING WILL ALSO PLAY A ROLE IN LIMITING PRECIP
COVERAGE. DEEPEST MOISTURE REMAINS OVER SC COUNTIES SO WILL CONTINUE
WITH HIGHEST POP TO THE SOUTH.
HIGH TEMPERATURES NEAR CLIMO FRI WILL WARM SLIGHTLY ON SAT AS RETURN
FLOW STARTS TO DEVELOP. LOWS WILL BE NEAR TO SLIGHTLY ABOVE CLIMO
EACH NIGHT.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 3 AM THURSDAY...SUMMER PATTERN IN PLACE AT THE START OF THE
WEEK WITH BERMUDA HIGH AND PIEDMONT TROUGH UNDER WEAKLY ZONAL FLOW
ALOFT. DEEP TROPICAL MOISTURE SPREADING NORTH FROM FL/GOMEX
ASSOCIATED WITH A WEAK TROPICAL WAVE WILL INCREASE SHOWER AND
THUNDERSTORM POTENTIAL SUN. STRENGTHENING MID LEVEL TROUGH MON
AHEAD OF COLD FRONT AND SHORTWAVE TROUGH MOVING INTO THE SOUTHEAST
LATER MON INTO TUE WILL FURTHER INCREASE SHOWER AND THUNDERSTORM
CHANCES. HIGHEST POP WILL BE ON MON...HIGH CHC...BUT ACTIVITY WILL
SPILL OVER INTO TUE AS FRONT IS NOT EXPECTED TO PUSH OFF THE COAST
UNTIL SOMETIME TUE AFTERNOON. WILL MAINTAIN INHERITED LOW CHC POP
FOR TUE THEN DRY THINGS OUT TUE NIGHT AND BEYOND AS HIGH PRESSURE
AND MUCH DRIER AIR BUILDS IN FROM THE NORTHWEST. PRECIPITABLE WATER
VALUES ARE BASICALLY CUT IN HALF...DROPPING FROM OVER 2 INCHES
SUN/MON TO UNDER AN INCH BY THE END OF THE PERIOD.
TEMPERATURES START OUT ABOVE CLIMO...BOTH LOWS AND HIGHS THROUGH MON
NIGHT BEFORE COLD FRONT PASSAGE ON TUE BRINGS A COOLER AND DRIER AIR
MASS FOR THE END OF THE PERIOD. HIGHS WILL BE SOLIDLY IN THE 90S SUN
AND MON...POTENTIALLY TUE IF FRONT IS SLOWER...THEN DROP BACK CLOSER
TO CLIMO...MID TO UPPER 80S WED. LOWS WELL ABOVE CLIMO FOR MUCH
OF THE PERIOD DROP A LITTLE BY MID WEEK...THOUGH STILL SEVERAL
DEGREES ABOVE CLIMO.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 18Z...A COLD FRONT DROPPING SOUTHWARD ALONG WITH SEA BREEZE
INTERACTIONS WILL PROVIDE THE FOCUS FOR ISO/SCT CONVECTION ALONG
THE COAST THIS AFTN. HAVE INCLUDED PREVAILING VCTS FOR KILM...KCRE
AND KMYR WITH TEMPO TSRA BASED ON THE LATEST HRRR TRENDS. BRIEF
PERIODS OF MVFR/IFR VSBYS AND GUSTY WINDS ARE POSSIBLE WITH
SHOWERS/T-STORMS THAT MOVE DIRECTLY OVER A TAF SITE. DRIER MID-
LEVEL AIR INLAND SHOULD LIMIT THE THREAT OF DEEP CONVECTION FOR
KLBT/KFLO...SO HAVE CHOSEN NOT TO MENTION PCPN ATTM. WEST WINDS
AROUND 10 KTS WILL VEER TO THE NORTHWEST LATER TODAY AND THEN THE
NORTHEAST FOLLOWING FROPA. THE FRONT SHOULD CLEAR OUR SOUTHERN
TERMS AROUND OR JUST AFTER 00Z. GFS FCST SOUNDINGS DEPICT POST-
FRONTAL MVFR/IFR CIGS DEVELOPING EARLY FRIDAY...SO HAVE INCLUDED
PREVAILING MVFR CIGS BEFORE 12Z. BEST CHANCES FOR IFR WOULD BE AT
KLBT/KILM...BUT CONFIDENCE IS LOW ATTM. VFR SHOULD PREVAIL DURING
THE DAY ON FRIDAY WITH E-NE WINDS AROUND 10 KTS.
EXTENDED OUTLOOK...EARLY MORNING IFR/MVFR CIGS/VSBYS POSSIBLE ON
SATURDAY...ESPECIALLY INLAND AT KLBT/KFLO. SCATTERED SHRA/TSRA
POSSIBLE MONDAY AND TUESDAY. OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 2 PM THURSDAY...AN EAST-WEST ORIENTED FRONT WILL SINK SOUTH
THROUGH THE WATERS THIS AFTERNOON INTO THIS EVENING. SOUTHWEST
WINDS WILL REMAIN IN PLACE AHEAD OF THE FRONT BUT WILL DECREASE
THROUGH THIS AFTERNOON AS THEY VEER AROUND TO MORE WESTERLY JUST AHEAD
OF THE COLD FRONT. OVERALL EXPECT SW TO W WINDS 10 TO 15 KTS WITH
HIGHER GUSTS AHEAD OF FRONT MAKING A SHARP TRANSITION TO THE NORTH
BEHIND THE FRONT.
THE COLD FRONT WILL REACH THE NORTHERN WATERS BY MID AND LATE
AFTERNOON AND SHOULD DROP SOUTH OF SOUTHERNMOST WATERS BY LATE
THIS EVE. WINDS WILL SHIFT TO THE N AND THEN NE LATER TONIGHT AS A
NE SURGE MOVES DOWN THE COAST AND ACROSS THE WATERS. SUSTAINED
WINDS WILL INCREASE TO AROUND 15 KT WITH HIGHER GUSTS OVERNIGHT
AND THIS WILL ALLOW SEAS TO BUILD. AT THIS TIME...WILL CAP SEAS AT
4 FT...BUT SOME 5 FOOTERS MAY DEVELOP BY FRI MORNING ACROSS
PORTIONS OF THE OUTERMOST WATERS.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...NORTHEAST FLOW OF 10 TO 15 KT AT THE START OF
THE PERIOD WILL WEAKEN AS GRADIENT RELAXES FRI INTO FRI NIGHT. WINDS
WILL BECOME SOUTHERLY SAT AS RETURN FLOW AROUND BERMUDA HIGH
DEVELOPS. GRADIENT SAT AND SAT NIGHT REMAINS WEAK WITH SPEEDS 10
KT OR LESS FOR THE SECOND HALF OF THE PERIOD. SEAS 2 TO 4 FT AT
THE START OF THE PERIOD WILL SUBSIDE TO 2 TO 3 FT FRI NIGHT AND 2
FT SAT/SAT NIGHT.
LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM THURSDAY...SOUTH TO SOUTHWEST FLOW WILL CONTINUE WITH
WATERS BETWEEN BERMUDA HIGH AND PIEDMONT TROUGH. COLD FRONT WELL
NORTHWEST OF THE AREA WILL SLOWLY APPROACH THE WATERS. AS THE
FRONT MOVES CLOSER THE GRADIENT WILL SLOWLY TIGHTEN...PUSHING
SPEEDS TO 10 TO 15 KT SUN AND 15 TO 20 KT FOR MON. LATEST
FORECASTS KEEP SEAS UNDER 6 FT THROUGH THE END OF THE PERIOD BUT
SOME 5 FT DO GET INTO PORTIONS OF THE WATERS NEAR 20 NM. COULD SEE
HEADLINES BEING REQUIRED LATE MON AND MON NIGHT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...RGZ
SHORT TERM...III
LONG TERM...III
AVIATION...MRR
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1122 PM CDT WED AUG 28 2013
.UPDATE...
ISSUED AT 1120 PM CDT WED AUG 28 2013
NO MAJOR CHANGES PLANNED TO THIS UPDATE. A BAND OF CONVECTION
WILL MOVE INTO WESTERN/CENTRAL ND OVERNIGHT AHEAD OF A STRONGER
SHORTWAVE. ADDITIONAL SHOWERS/STORMS MAY DEVELOP OVER EASTERN ND
LATER TONIGHT WITH INCREASING MID LEVEL WAA AND INSTABILITY. THIS
IS ALL HANDLED WELL IN THE CURRENT GRIDS. THERE COULD BE SOME VERY
PATCHY FOG BEFORE CLOUDS INCREASE...BUT WITH NO EVIDENCE OF FOG
YET AND THE HRRR NOT INDICATING ANY...FOR NOW WILL LEAVE OUT...BUT
SOMETHING TO MONITOR. THERE COULD BE SEVERE STORMS LATER TONIGHT
AND A BETTER CHANCE ON THU...WITH AMPLE INSTABILITY/SHEAR. PWATS
ALSO RISE OVER 2 INCHES IN SOME AREAS...SO LOCALLY HEAVY RAIN WILL
ALSO BE A THREAT.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 323 PM CDT WED AUG 28 2013
WEAK SURFACE BOUNDARY HAS DROPPED OUT OF MANITOBA AND EXTENDS FROM
FLAG ISLAND TO JUST SOUTH OF ROSEAU TO ST THOMAS TO CANDO. THIS
BOUNDARY IS PROGGED TO DROP JUST A BIT SOUTH AND WITH DEW PTS NR
70 ALONG BOUNDARY AND HEATING OF TEMPS INTO THE LOWER 90S ALONG
BOUNDARY ALL CAUSING A FEW STORMS TO FIRE. WILL NEED TO INCLUDE
ISOLD POP FOR THIS THRU SUNSET.
OTHERWISE MAIN ACTION LATE TONIGHT. WATER VAPOR SHOWS NEXT SHORT
WAVE MOVING INTO SOUTHWEST MONTANA AT 19Z. THIS SHORT WAVE WILL
MOVE EAST ON TOP OF THE 500 MB RIDGE AND INTO ERN ND TOWARD 12Z
AND THEN INTO MINNESOTA THURSDAY THROUGH 18Z. ALL MODELS INDICATE
A 30-35 KT LOW LEVEL JET ALONG 850 MB BOUNDARY WHICH WILL LIE IN
THE CENTRAL PART OF THE STATE LIKELY JUST NORTH OF I-94.
SOUTHEASTERLY UPSLOPE FLOW INTO EASTERN MONTANA AIDING IN STORM
DEVELOPMENT THERE AND EXPECT AS SHORT WAVE MOVES INTO CNTRL
MONTANA STORM TO GROW IN COVERAGE AND SEEMS AS IF AN MCS IS LIKELY
TO FORM AND MOVE EAST INTO WRN ND LATER THIS EVE AND THEN CNTRL ND
OVERNIGHT REACHING THE RED RIVER VALLEY LIKELY AFTER 08Z. TRIED TO
TIME POPS A BIT MORE TOWARD THAT IDEA...WITH LIKELY POPS 09Z-12Z
IN MUCH OF ERN ND. SEVERE WX BY THEN QUESTIONABLE....BUT WITH
PWATS OF 2.10 INCHES ALONG 850 MB BOUNDARY HEAVY RAIN SEEMS
REASONABLE. COULD BE LOCALIZED FLASH FLOODING ISSUES BUT WHERE AND
WHEN CANNOT SAY AND CONDITIONS PRIOR TO RAIN HAVE BEEN VERY VERY
DRY.
SYSTEM WILL MOVE EAST WITH PRECIP ENDING IN THE MORNING IN ERN ND
AND IN THE AFTN IN NW MN.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 323 PM CDT WED AUG 28 2013
DRY THURSDAY NIGHT AND FRIDAY WITH HIGH PRESSURE MOVING. A TAD
COOLER BUT NOT MUCH.
FOR SATURDAY THROUGH WEDNESDAY...LONG WAVE PATTERN IS ZONAL AND
SPLIT ACROSS NORTH AMERICA AT THE BEGINNING OF THE PERIOD AND
AMPLIFIES BY THE END OF THE PERIOD. LONG WAVE UPPER RIDGE REMAINS
FROM THE DESERT SOUTHWEST INTO MT. THE ECMWF AND GFS WERE IN
AGREEMENT AT 84 HOURS. THE ECMWF IS A FASTER SOLUTION THAN THE GFS
BY THE END OF THE PERIOD. BOTH GFS AND ECMWF HAVE SHIFTED WEST IN
THE LAST MODEL RUN. WILL BLEND THE ECMWF AND GFS.
WILL KEEP YESTERDAYS PRECIP FOR SAT NIGHT. BUMPED UP POPS FOR SUN.
TOOK OUT PRECIP FOR TUE.
TEMPERATURES WERE LOWERED A DEGREE OR TWO FOR SUN AND MON AND RAISED
ONE OR TWO DEGREES FOR TUE AND WED COMPARED TO YESTERDAYS RUN.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1120 PM CDT WED AUG 28 2013
THE CHANCE FOR SHOWERS AND STORMS WILL INCREASE FROM WEST TO EAST
BY LATE TONIGHT INTO THU. EXPECT MAINLY VFR CONDITIONS...ALTHOUGH
MVFR AND EVEN IFR CONDITIONS ARE POSSIBLE NEAR STRONGER STORMS
CONTAINING VERY HEAVY RAIN AND STRONGER WINDS. THE BEST CHANCE FOR
PROLONGED RAIN TOMORROW SHOULD OCCUR ACROSS THE NORTH.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...DK
SHORT TERM...RIDDLE
LONG TERM...HOPPES/RIDDLE
AVIATION...DK
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
958 PM EDT FRI AUG 30 2013
.SYNOPSIS...
LOW PRESSURE MOVING ACROSS THE CENTRAL GREAT LAKES WILL DRAG A
COLD FRONT ACROSS THE AREA LATE TONIGHT AND SATURDAY. THE FRONT
WILL STALL ACROSS CENTRAL OHIO SATURDAY NIGHT. A STRONGER COLD
FRONT WILL FOLLOW ON MONDAY USHERING COOLER AIR FOR MID WEEK.
&&
.NEAR TERM /UNTIL 7 AM SATURDAY MORNING/...
THE UPPER LEVEL TROUGH CONTINUES TO MOVE TOWARD NORTHERN OHIO AND
NW PA. THIS UPPER LEVEL SUPPORT COMBINED WITH THE WEAK COLD FRONT
AND OUTFLOW BOUNDARIES HAS BEEN ENOUGH TO KEEP THE THUNDERSTORMS
GOING ACROSS SOUTHERN ONTARIO INTO MICHIGAN. THE CURRENT INCREASE
IN THE COVERAGE IS LIKELY CAUSED BY THE WARM ADVECTION AT 850 MB.
SO WE MAY SEE AN INCREASE OVER THE NEXT COUPLE HOURS ACROSS
SOUTHERN MICHIGAN INTO NW OHIO. STILL DONT BELIEVE IT WILL BE MORE
THAN SCATTERED COVERAGE AT THIS POINT.
PREVIOUS DISCUSSION...
FOR THE EARLY EVENING WILL HAVE SLIGHT CHANCE POPS NWRN PA. RADAR
HAS CONTINUED TO SHOW SMALL RAIN SHOWERS IMPACTING ERIE COUNTY FAR
NORTHEAST AND THIS COULD CONTINUE INTO THE EVENING. MOST AREAS
WILL REMAIN DRY HOWEVER. ELSEWHERE EXPECT PARTLY CLOUDY SKIES
THROUGH THE EVENING. OVERNIGHT A COLD FRONT TO OUR NORTH WILL
CONTINUE DROPPING SOUTH TOWARD THE AREA. CONVECTION IS OCCURRING
ON THE LINE WITH ONE DEVELOPING CLUSTER IN SERN WI WITH A BROKEN
LINE ACROSS NORTHERN LOWER MI. HRRR BRINGS THE WI CLUSTER INTO NRN
INDIANA BY 03Z WHILE THE ACTIVITY ACROSS NRN LOWER MI WEAKENS AND
BECOMES INCREASINGLY ISOLATED IN SERN LOWER MI AND ONTARIO JUST
NORTH OF THE LAKE. WILL BRING CHANCE POPS TO NWRN OHIO AND THE
LAKE MAINLY AFTER MIDNIGHT WITH POPS INCREASING TO CHANCE ACROSS
THE REMAINDER OF THE AREA TIER BETWEEN 06Z AND 12Z. FOLLOWED SREF
TIMING BUT GUIDANCE POPS WERE MUCH HIGHER THAN THE GFS MOS SO DID
SCALE BACK TOWARD THE GFS MOS CHANCE POPS. TEMPS AGAIN MILD WITH
LOWS IN THE UPPER 60S.
&&
.SHORT TERM /7 AM SATURDAY MORNING THROUGH MONDAY NIGHT/...
WILL CONTINUE WITH CHANCE POPS THROUGH THE DAY AS THE WEAK COLD
FRONT SLOWLY SAGS SOUTH THROUGH THE AREA. BEST CHANCE LIKELY
SOUTHEAST COUNTIES GIVEN THAT THE FRONT WILL BE MOVING INTO THAT
AREA DURING THE AFTERNOON HOURS. SATURDAY NIGHT THE FRONT WILL
LIKELY STALL JUST TO OUR SOUTH AS LOW PRESSURE MOVES ALONG IT WEST
OF THE AREA. BOTH THE NAM AND GFS INDICATE MOISTURE INCREASES
AGAIN FROM THE SOUTHWEST AS THE FRONT WAFFLES BACK TOWARD OR INTO
THE AREA. BROUGHT CHANCE POPS BACK AFTER MIDNIGHT WEST AFTER
HAVING DRIED IT OUT FOR THE EVENING. SUNDAY THROUGH MONDAY MODELS
CONTINUE TO INCREASE MOISTURE ACROSS THE AREA AHEAD OF ANOTHER
APPROACHING COLD FRONT. THE FRONT WILL MOVE THROUGH THE AREA
MONDAY AND WITH FORECAST CAPES FROM 2-3000J/KG FOR THE AFTERNOON
TSTMS COULD GET STRONG. WILL CONTINUE TO WATCH SEVERE POTENTIAL
BUT FOR NOW WILL HAVE HIGH CHANCE TO LIKELY POPS THROUGH THE DAY.
TUESDAY NIGHT WILL ALLOW WESTERN COUNTIES TO DRY OUT AS HIGH
PRESSURE AND DRIER AIR MOVE IN. WILL KEEP CHANCE POPS FOR SHOWERS
IN THE EAST GIVEN THE MOISTURE AND THE FACT THAT COOLER AIR WILL
BE MOVING ACROSS THE LAKE. HIGHS ABOVE NORMAL MUCH OF THE PERIOD.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
HIGH PRESSURE WILL BUILD OVER THE AREA ON TUESDAY AS THE UPPER LEVEL
TROUGH AXIS SHIFTS EAST OF THE GREAT LAKES. THE AIRMASS WILL FEEL
NOTICEABLY DIFFERENT WITH DECREASING HUMIDITY AND TEMPERATURES
DROPPING BACK TO BELOW NORMAL VALUES. EXPECTING SCT-BKN CLOUDS WITH
THE GREATEST COVERAGE IN NE OH/NW PA. HIGHS WILL TOP OUT IN THE LOW
70S IN OHIO...STRUGGLING TO GET OUT OF THE 60S IN NW PA.
HIGH PRESSURE WILL BUILD SOUTHEAST ACROSS THE REGION ON
WEDNESDAY...SHIFTING TO THE OHIO VALLEY ON THURSDAY. TEMPERATURES
WILL REBOUND SEVERAL DEGREES WITH MOSTLY SUNNY SKIES AND GOOD
INSOLATION ON WEDNESDAY.
12Z MODEL SUITE HAS COME INTO BETTER AGREEMENT WITH THE HANDLING OF
THE NEXT FRONT ON THURSDAY. THE 00Z ECMWF WHICH WAS FASTER AND
STRONGER WITH THE NEXT COLD FRONT HAS SLOWED DOWN WITH THE 12Z RUN
AND TRENDED TOWARDS A WEAKER FRONT. THIS IS CLOSER TO THE SOLUTION
OFFERED BY THE GFS SO WILL LEAN THE FORECAST TOWARDS JUST ANOTHER
MODEST DROP IN TEMPERATURES TOWARDS THE END OF THE WEEK INSTEAD OF
THE COLDER SOLUTION.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
FORECAST STILL ON TRACK AND LITTLE IN THE WAY OF CHANGES WERE
MADE. VFR CONDITIONS WILL CONTINUE THROUGH ABOUT 04Z WHEN HZ/BR
WILL START TO DEVELOP WITH HIGH BOUNDARY LAYER MOISTURE IN PLACE.
LOW PRESSURE WILL MOVE FROM THE UPPER GREAT LAKES TO NEAR LAKE
ONTARIO OVERNIGHT. SHOWERS AND A FEW THUNDERSTORMS WILL OCCUR
AHEAD OF THE ASSOCIATED FRONT THAT WILL PUSH SOUTH OVER THE AREA
LATE TONIGHT INTO SATURDAY MORNING. HAVE CONTINUED THE VCSH
MENTION FOR ALL THE TAF SITES...BUT INCLUDED VCTS AT TOL AND ERI.
AS FAR AS WE CAN SEE NOW...THEY HAVE THE BEST TS CHANCES. COVERAGE
OF SHOWERS STILL IN QUESTION WITH THIS FRONT THAT WILL BE
WEAKENING AND SLOWING AS IT APPROACHES. A SCT- BKN MVFR CLOUD DECK
WILL LIKELY DEVELOP BEHIND THE FRONT ON SATURDAY MORNING WITH SOME
POTENTIAL FOR IFR CLOUDS/VISIBILITY. FRONT EXPECTED TO BE SOUTH OF
LAKE ERIE IN THE MORNING AND HENCE A WIND SHIFT TO THE NORTH.
FRONT MAY LINGER CLOSE ENOUGH TO SOUTHERN TIER INTO THE AFTERNOON
SO HAVE INCLUDED A VCTS AT YNG AND CAK FOR THE AFTERNOON. NOT OUT
OF THE QUESTION FOR MFD OR MAYBE FDY TO HAVE TS SATURDAY TOO...BUT
CHANCES LOW. BY 00Z SUN ALL WINDS WILL HAVE SHIFTED TO THE NORTH.
OUTLOOK...NON VFR LIKELY INLAND LOCATIONS EACH MORNING IN PATCHY
FOG. NON VFR IN SCATTERED SHOWERS/THUNDERSTORMS SATURDAY THROUGH
MONDAY.
&&
.MARINE...
A LIGHT SOUTHWESTERLY FLOW WITH SOME DEGREE OF A LAKE BREEZE ON THE
EASTERN HALF OF THE LAKE IS IN PLACE TODAY. WINDS WILL INCREASE TO
10 TO 15 KNOTS AHEAD OF A COLD FRONT THAT WILL PUSH SOUTH ACROSS THE
LAKE LATE TONIGHT INTO SATURDAY MORNING. SCATTERED SHOWERS AND
THUNDERSTORMS ARE ALSO EXPECTED AHEAD OF THE FRONT. WINDS WILL SHIFT
TO THE NORTHWEST BEHIND THE FRONT ON SATURDAY BUT ARE NOT EXPECTED
TO BE MORE THAN 5 TO 15 KNOTS AS THE FRONT STALLS OVER CENTRAL
OHIO.
WIND WILL SHIFT AROUND TO THE SOUTH ON SUNDAY AS A WARM FRONT PUSHES
BACK NORTH OVER THE LAKE. THERE WILL BE A CHANCE OF THUNDERSTORMS
SUNDAY...INCREASING SUNDAY NIGHT INTO MONDAY AS LOW PRESSURE
APPROACHES THE GREAT LAKES FROM THE WEST. THIS SYSTEM WILL PULL A
STRONGER COLD FRONT ACROSS THE LAKE ON MONDAY WITH NORTHWESTERLY
WINDS INCREASING TO 10 TO 20 KNOTS DURING THE AFTERNOON. THE
NORTHWESTERLY FLOW WILL LEAD TO WAVES BUILDING TO 2 TO 4 FEET ON
MONDAY NIGHT AND TUESDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TK
NEAR TERM...TK/MULLEN
SHORT TERM...TK
LONG TERM...KEC
AVIATION...OUDEMAN
MARINE...KEC
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
655 PM EDT FRI AUG 30 2013
.SYNOPSIS...
LOW PRESSURE MOVING ACROSS THE CENTRAL GREAT LAKES WILL DRAG A
COLD FRONT ACROSS THE AREA LATE TONIGHT AND SATURDAY. THE FRONT
WILL STALL ACROSS CENTRAL OHIO SATURDAY NIGHT. A STRONGER COLD
FRONT WILL FOLLOW ON MONDAY USHERING COOLER AIR FOR MID WEEK.
&&
.NEAR TERM /UNTIL 7 AM SATURDAY MORNING/...
ONLY MADE SOME MINOR TWEAKS TO THE FORECAST AT THIS TIME...MAINLY
TO HOURLY CLOUD COVER AND TEMPERATURES.
WE CONTINUE TO WATCH A 5H TROUGH AXIS MOVING ACROSS SOUTHERN
ONTARIO WITH THE MAIN JET ENERGY JUST NORTH OF LAKE ERIE. BEST
CHANCE OF SEEING THUNDERSTORMS WILL BE OVER SOUTHERN ONTARIO
THROUGH THE EVENING. AN IMPROVING SHEAR PROFILE AND ADEQUATE LOW
LEVEL MOISTURE POINT TO THE DEVELOPMENT OF A FEW SHOWERS OR
THUNDERSTORMS LATE IN THE EVENING ACROSS NW PA AND MAYBE EXTREME
NE OHIO. LOW LEVEL CONVERGENCE IS MINIMAL SO IT MAY BE DIFFICULT
FOR THESE TO DEVELOP. OTHERWISE WE WILL CONTINUE TO WATCH THE
MOVEMENT OF THE WEAK COLD FRONT ACROSS MICHIGAN AND THE OUTFLOW
BOUNDARIES FROM THE CURRENT THUNDER. THESE MAY BRING SOME THUNDER
NEAR THE TOLEDO AREA LATE.
PREVIOUS DISCUSSION...
FOR THE EARLY EVENING WILL HAVE SLIGHT CHANCE POPS NWRN PA. RADAR
HAS CONTINUED TO SHOW SMALL RAIN SHOWERS IMPACTING ERIE COUNTY FAR
NORTHEAST AND THIS COULD CONTINUE INTO THE EVENING. MOST AREAS
WILL REMAIN DRY HOWEVER. ELSEWHERE EXPECT PARTLY CLOUDY SKIES
THROUGH THE EVENING. OVERNIGHT A COLD FRONT TO OUR NORTH WILL
CONTINUE DROPPING SOUTH TOWARD THE AREA. CONVECTION IS OCCURRING
ON THE LINE WITH ONE DEVELOPING CLUSTER IN SERN WI WITH A BROKEN
LINE ACROSS NORTHERN LOWER MI. HRRR BRINGS THE WI CLUSTER INTO NRN
INDIANA BY 03Z WHILE THE ACTIVITY ACROSS NRN LOWER MI WEAKENS AND
BECOMES INCREASINGLY ISOLATED IN SERN LOWER MI AND ONTARIO JUST
NORTH OF THE LAKE. WILL BRING CHANCE POPS TO NWRN OHIO AND THE
LAKE MAINLY AFTER MIDNIGHT WITH POPS INCREASING TO CHANCE ACROSS
THE REMAINDER OF THE AREA TIER BETWEEN 06Z AND 12Z. FOLLOWED SREF
TIMING BUT GUIDANCE POPS WERE MUCH HIGHER THAN THE GFS MOS SO DID
SCALE BACK TOWARD THE GFS MOS CHANCE POPS. TEMPS AGAIN MILD WITH
LOWS IN THE UPPER 60S.
&&
.SHORT TERM /7 AM SATURDAY MORNING THROUGH MONDAY NIGHT/...
WILL CONTINUE WITH CHANCE POPS THROUGH THE DAY AS THE WEAK COLD
FRONT SLOWLY SAGS SOUTH THROUGH THE AREA. BEST CHANCE LIKELY
SOUTHEAST COUNTIES GIVEN THAT THE FRONT WILL BE MOVING INTO THAT
AREA DURING THE AFTERNOON HOURS. SATURDAY NIGHT THE FRONT WILL
LIKELY STALL JUST TO OUR SOUTH AS LOW PRESSURE MOVES ALONG IT WEST
OF THE AREA. BOTH THE NAM AND GFS INDICATE MOISTURE INCREASES
AGAIN FROM THE SOUTHWEST AS THE FRONT WAFFLES BACK TOWARD OR INTO
THE AREA. BROUGHT CHANCE POPS BACK AFTER MIDNIGHT WEST AFTER
HAVING DRIED IT OUT FOR THE EVENING. SUNDAY THROUGH MONDAY MODELS
CONTINUE TO INCREASE MOISTURE ACROSS THE AREA AHEAD OF ANOTHER
APPROACHING COLD FRONT. THE FRONT WILL MOVE THROUGH THE AREA
MONDAY AND WITH FORECAST CAPES FROM 2-3000J/KG FOR THE AFTERNOON
TSTMS COULD GET STRONG. WILL CONTINUE TO WATCH SEVERE POTENTIAL
BUT FOR NOW WILL HAVE HIGH CHANCE TO LIKELY POPS THROUGH THE DAY.
TUESDAY NIGHT WILL ALLOW WESTERN COUNTIES TO DRY OUT AS HIGH
PRESSURE AND DRIER AIR MOVE IN. WILL KEEP CHANCE POPS FOR SHOWERS
IN THE EAST GIVEN THE MOISTURE AND THE FACT THAT COOLER AIR WILL
BE MOVING ACROSS THE LAKE. HIGHS ABOVE NORMAL MUCH OF THE PERIOD.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
HIGH PRESSURE WILL BUILD OVER THE AREA ON TUESDAY AS THE UPPER LEVEL
TROUGH AXIS SHIFTS EAST OF THE GREAT LAKES. THE AIRMASS WILL FEEL
NOTICEABLY DIFFERENT WITH DECREASING HUMIDITY AND TEMPERATURES
DROPPING BACK TO BELOW NORMAL VALUES. EXPECTING SCT-BKN CLOUDS WITH
THE GREATEST COVERAGE IN NE OH/NW PA. HIGHS WILL TOP OUT IN THE LOW
70S IN OHIO...STRUGGLING TO GET OUT OF THE 60S IN NW PA.
HIGH PRESSURE WILL BUILD SOUTHEAST ACROSS THE REGION ON
WEDNESDAY...SHIFTING TO THE OHIO VALLEY ON THURSDAY. TEMPERATURES
WILL REBOUND SEVERAL DEGREES WITH MOSTLY SUNNY SKIES AND GOOD
INSOLATION ON WEDNESDAY.
12Z MODEL SUITE HAS COME INTO BETTER AGREEMENT WITH THE HANDLING OF
THE NEXT FRONT ON THURSDAY. THE 00Z ECMWF WHICH WAS FASTER AND
STRONGER WITH THE NEXT COLD FRONT HAS SLOWED DOWN WITH THE 12Z RUN
AND TRENDED TOWARDS A WEAKER FRONT. THIS IS CLOSER TO THE SOLUTION
OFFERED BY THE GFS SO WILL LEAN THE FORECAST TOWARDS JUST ANOTHER
MODEST DROP IN TEMPERATURES TOWARDS THE END OF THE WEEK INSTEAD OF
THE COLDER SOLUTION.
&&
.AVIATION /18Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL CONTINUE THROUGH ABOUT 04Z WHEN HZ/BR WILL
START TO DEVELOP WITH HIGH BOUNDARY LAYER MOISTURE IN PLACE. LOW
PRESSURE WILL MOVE FROM THE UPPER GREAT LAKES TO NEAR LAKE ONTARIO
OVERNIGHT. SHOWERS AND A FEW THUNDERSTORMS WILL OCCUR AHEAD OF THE
ASSOCIATED FRONT THAT WILL PUSH SOUTH OVER THE AREA LATE TONIGHT
INTO SATURDAY MORNING. FOR NOW HAVE PUT VCSH INTO ALL SITES BUT
HAVE NOT INCLUDED THUNDERSTORMS GIVEN THE UNCERTAINTY IN COVERAGE.
A SCT- BKN MVFR CLOUD DECK WILL LIKELY DEVELOP BEHIND THE FRONT ON
SATURDAY MORNING WITH SOME POTENTIAL FOR IFR CLOUDS/VISIBILITY.
OUTLOOK...NON VFR LIKELY INLAND LOCATIONS EACH MORNING IN PATCHY
FOG. NON VFR IN SCATTERED SHOWERS/THUNDERSTORMS SATURDAY THROUGH
MONDAY.
&&
.MARINE...
A LIGHT SOUTHWESTERLY FLOW WITH SOME DEGREE OF A LAKE BREEZE ON THE
EASTERN HALF OF THE LAKE IS IN PLACE TODAY. WINDS WILL INCREASE TO
10 TO 15 KNOTS AHEAD OF A COLD FRONT THAT WILL PUSH SOUTH ACROSS THE
LAKE LATE TONIGHT INTO SATURDAY MORNING. SCATTERED SHOWERS AND
THUNDERSTORMS ARE ALSO EXPECTED AHEAD OF THE FRONT. WINDS WILL SHIFT
TO THE NORTHWEST BEHIND THE FRONT ON SATURDAY BUT ARE NOT EXPECTED
TO BE MORE THAN 5 TO 15 KNOTS AS THE FRONT STALLS OVER CENTRAL
OHIO.
WIND WILL SHIFT AROUND TO THE SOUTH ON SUNDAY AS A WARM FRONT PUSHES
BACK NORTH OVER THE LAKE. THERE WILL BE A CHANCE OF THUNDERSTORMS
SUNDAY...INCREASING SUNDAY NIGHT INTO MONDAY AS LOW PRESSURE
APPROACHES THE GREAT LAKES FROM THE WEST. THIS SYSTEM WILL PULL A
STRONGER COLD FRONT ACROSS THE LAKE ON MONDAY WITH NORTHWESTERLY
WINDS INCREASING TO 10 TO 20 KNOTS DURING THE AFTERNOON. THE
NORTHWESTERLY FLOW WILL LEAD TO WAVES BUILDING TO 2 TO 4 FEET ON
MONDAY NIGHT AND TUESDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TK
NEAR TERM...TK/MULLEN
SHORT TERM...TK
LONG TERM...KEC
AVIATION...KEC
MARINE...KEC
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
937 PM CDT FRI AUG 30 2013
.UPDATE...
NO MAJOR UPDATES THIS EVENING. THUNDERSTORMS ARE BEGINNING TO WANE
AS DIABATIC HEATING CEASES. AS A WAVE MOVES ACROSS SOUTHERN CANADA
AND THE FAR NORTHERN PLAINS TNT...A STORM OR TWO MAY STILL SINK SOUTH
INTO THE NORTHERN CWA OVERNIGHT SO WILL KEEP POPS IN PLACE.
HOWEVER LLJ (WAA) NOT PARTICULARLY IMPRESSIVE SO SLIGHT CHC POPS
LOOK APPROPRIATE. UPDATES WILL BE ISSUED WHEN SVR WATCH EXPIRES.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT
DESTABILIZATION OCCURRING THIS AFTERNOON ACROSS THE WESTERN
DAKOTAS WITH MESO-ANALYSIS INDICATING AROUND 2000 J/KG MLCAPE.
SHEAR VALUES RANGE FROM AROUND 35 TO 40 KNOTS OVER WESTERN SD. A
SEVERE STORM IS AFFECTING THE BLACK HILLS AT THIS TIME...WITH VIS
SATELLITE IMAGERY SHOWING THE BEGINNINGS OF A CU FIELD EXTENDING
NORTHWARD INTO DICKINSON ND. HI RES MODELS DO SHOW ISOLD/WDLY SCT
CONVECTION OCCURRING OVER THE NEXT FEW HOURS AND LASTING INTO THE
EVENING HOURS...SOME OF WHICH MAY AFFECT THE FAR WESTERN CWA.
LATEST HRRR RUN HAS THE CONVECTION OVER THE BLACK HILLS NAILED
RIGHT NOW AND SHOWS SMALL BUT POTENT CELLS DEVELOPING ALONG THE
CURRENT CU FIELD OVER THE NEXT COUPLE HOURS...THEN PUSHES THINGS
INTO CORSON/DEWEY COUNTIES. NOT SURE AREAL COVERAGE WILL BE AS
GREAT AS THE HRRR...BUT IN SOME FORM OR ANOTHER...DO EXPECT ISOLD
TO WDLY SCT STORMS OVER THE NEXT FEW HOURS. SVR WATCH 505 WAS
RECENTLY ISSUED TO COVER THIS THREAT. WITH THE LACK OF ANY
APPRECIABLE LOW LEVEL JET OVERNIGHT...DO NOT EXPECT THIS ACTIVITY
TO SURVIVE MUCH PAST THE MISSOURI RIVER AND SHOULD WANE WITH THE
LOSS OF DAYTIME HEATING.
FOCUS WILL THEN TURN TO THE ADVANCING COLD FRONT ON SATURDAY.
FRONT WILL SET UP ACROSS THE EASTERN CWA BY PEAK HEATING...WITH
MODERATE INSTABILITY AND SHEAR DEVELOPING. ALTHOUGH BEST UPPER
LEVEL SUPPORT IS NORTH OF THE REGION...CONVERGENCE ALONG THE SHARP
FRONTAL BOUNDARY ALONG WITH SUFFICIENT LOW LEVEL MOISTURE AND
STEEP LAPSE RATES IS EXPECTED TO LEAD TO MID/LATE AFTERNOON
THUNDERSTORM DEVELOPMENT ALONG THE FRONT. SPEED OF THE FRONT WILL
BE KEY IN DETERMINING BEST CHANCE FOR STORMS. GIVEN PLACEMENT OF
THE FRONT BY AFTERNOON...CONVECTIVE INITIATION COULD OCCUR BETWEEN
THE JAMES VALLEY AND I-29...WITH MORE CONSOLIDATION/BETTER STORM
CHANCES CLOSER TO I-29 AND POINTS EAST BY LATE AFTERNOON AND INTO
THE EVENING. DAY TWO SLIGHT RISK IS NOW INCLUDING EASTERN PORTIONS
OF THE FORECAST AREA.
BEHIND THIS FRONT WILL BE MUCH COOLER AIR...WITH HIGHS ON SUNDAY
EXPECTED TO DROP BACK INTO THE 70S FOR MOST AREAS. SFC HIGH WILL
BUILD SOUTH INTO THE AREA SUNDAY NIGHT...AND WITH THE COOLER AND
DRIER AIR MASS IN PLACE...LOWS BY MONDAY MORNING COULD ACTUALLY
DIP INTO THE UPPER 40S.
.LONG TERM...MONDAY THROUGH FRIDAY
THE LONG TERM LOOKS TO REMAIN ON THE DRY SIDE WITH UPPER LEVEL
RIDGING AND SUBSIDENT FLOW DOMINATING THE WEATHER. THE MODELS SHOW
THE UPPER LEVEL RIDGE AXIS OUT WEST TO BEGIN THE LONG TERM PUSHING
EAST THROUGH FRIDAY OVER OUR REGION. ANY SHORT WAVES MOVING OVER
THE RIDGE SHOULD BE MOISTURE STARVED WITH ONLY SOME CLOUDS MOVING
IN. AFTER A COOLER DAY ON MONDAY...WARMER AIR WILL RETURN FOR
TUESDAY AND REMAIN THROUGH FRIDAY. SHOULD HAVE MID 70S EAST ON
MONDAY WARMING TO THE 80S TO THE LOWER 90S ACROSS ALL OF THE CWA
THROUGH THE REST OF THE WEEK.
&&
.AVIATION...
00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
VFR CONDITIONS ARE EXPECTED AT ALL TERMINALS THROUGH TNT. HOWEVER
WILL HAVE TO MONITOR FOR ANY CHC OF THUNDERSTORMS AT KMBG/KPIR AND
THEN KABR LATE. RIGHT EXPECT MOST OF THE ACTIVITY OVER THE WESTERN
DAKOTAS TO DISSIPATE WITH THE SETTING SUN LATER THIS EVENING.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...TDK
SHORT TERM...TMT
LONG TERM...MOHR
AVIATION...TDK
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
134 PM EDT THU AUG 29 2013
.SYNOPSIS...
A FRONTAL BOUNDARY SHIFTS SOUTH INTO NORTH CAROLINA THIS AFTERNOON.
WEAK HIGH PRESSURE SHOULD BUILD INTO THE AREA BEHIND IT FOR
THIS AFTERNOON INTO FRIDAY BEFORE SLIDING OFFSHORE BY SATURDAY.
THIS WILL BRING A RETURN FLOW OF MOISTURE ALONG WITH AN ASSOCIATED
WARM FRONT LATER IN THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 125 PM EDT THURSDAY...
MADE SOME MINOR ADJUSTMENTS IN POPS AND TEMPERATURES FOR THIS
AFTERNOON INTO THIS EVENING.
AS OF 940 AM EDT THURSDAY...
THIS MORNING 8AM/12Z RNK SOUNDING SHOWED PLENTY OF MOISTURE
UP TO 640 MB WITH A NORTHERLY FLOW. KFCX 88D INDICATED WIDELY
SCATTERED SHOWERS TRAVELING SOUTH THIS MORNING. COLD FRONT ACROSS
SOUTHERN PORTIONS OF CWA THIS MORNING WILL SLOWLY DRIFT SOUTH
TODAY. MADE SOME ADJUSTMENTS IN THE POPS TO SHAPE TOWARDS RADAR
TRENDS AND HRRR FOR NEXT COUPLE OF HOURS...THEN KEPT THE SCATTERED
STORMS IN FOR THE AFTERNOON INTO TONIGHT. THE BEST CHANCE REMAIN
ALONG THE SOUTHERN BLUE RIDGE THIS AFTERNOON WITH MOISTURE
CONVERGENCE. HIGH PRESSURE BUILDS SOUTH ACROSS THE REGION
TONIGHT. HIGH TEMPERATURES THIS AFTERNOON WILL RANGE FROM THE
UPPER 70S IN THE MOUNTAINS TO THE MID 80S IN THE PIEDMONT.
AS OF 315 AM EDT THURSDAY...
SOUPY AIRMASS IN PLACE THIS MORNING WITH TEMPS STILL RUNNING IN THE
70S OVER MUCH OF THE AREA. FRONTAL BOUNDARY SITUATED FROM LOW
PRESSURE OVER VA TIDEWATER NORTHWEST INTO NRN WV THEN INTO SRN
OHIO. HIGHER THETA-E ACROSS ERN KY/SRN WV SHIFTING SE INTO THE NC
MTNS WILL KEEP SHOWERS AROUND THRU AT LEAST MID MORNING...BUT
MAINLY ISOLATED.
AT THE MOMENT SKIES HAVE CLEARED OVER THE FOOTHILLS AND PIEDMONT
THANKS TO A CONSISTENT NNW FLOW DOWNSLOPING WIND. THIS WILL CHANGE
THRU DAYBREAK AS THE FLOW COMES AROUND TO THE NORTH THEN NORTHEAST.
STILL HINGING ON CLOUDS INCREASING ALONG THE BLUE RIDGE AND POINTS
EAST BUT THEN SLOWLY MIXING OUT TOWARD MIDDAY. THE 00Z CMC HAS A
PRETTY GOOD HANDLE EARLY...BUT DOES NOT REALLY ENHANCE LOW CLOUDS
DEVELOPING OVER THE BLUE RIDGE LIKE THE NAM DOES...SO LEANED TOWARD
A BLEND OF THE TWO.
THROUGH THE DAY...WILL BE DEALING WITH SOME DRYING ALOFT...BUT
KEEPING THE LOW LVLS MOIST...AS NOT MUCH CHANGE IN AIRMASS EXPECTED.
THERE WILL BE ENOUGH LOW LEVEL CONVERGENCE AROUND NEAR THE FRONT
THAT AT LEAST ISOLATED SHOWERS OR STORMS OCCUR THIS AFTERNOON. STILL
LOOKS LIKE THE SRN BLUE RIDGE HAS THE BEST CHANCE OF SEEING
SCATTERED COVERAGE GIVEN THE FORECAST CONVERGENCE PATTERN IN THE
WINDS.
GIVEN A LACK OF UPSTREAM CONVECTION AND CLOUDS...THINK THE SUN WILL
BREAK THROUGH TOWARD EARLY AFTERNOON IN THE NORTH...THEN MID
AFTERNOON ELSEWHERE. THESE LOWER CLOUDS MAY BE HARD TO MIX OUT UNTIL
LATE MORNING. FOR THE AFTERNOON ENOUGH SUN WILL AVAILABLE TO REALIZE
WARMER HIGHS...BUT SOUPY AIRMASS WILL STILL CUT INTO REALLY WARM
TEMPS...SO WENT CLOSE TO OR JUST BELOW MAV MOS WITH UPPER 70S/LOWER
80S WEST TO MID TO UPPER 80S ACROSS THE SOUTHERN SHENANDOAH
SOUTHEAST INTO SOUTHSIDE VA AND THE NC PIEDMONT/FOOTHILLS.
LOW LVLS WINDS CONTINUE TO SHIFT TOWARD THE EAST THEN SOUTHEAST LATE
TONIGHT AS HIGH PRESSURE NOSES SOUTH OVER THE ALLEGHANY HIGHLANDS.
STILL ENOUGH CONVERGENCE AND LOW LVL MOISTURE TO HANG ONTO POPS OF
THE 20/30 VARIETY OVER THE SOUTHERN BLUE RIDGE AND ADJACENT AREAS
THIS EVENING...GRADUALLY SHRINKING TO SLIGHT CHANCE OVER THE NC MTNS
AFTER MIDNIGHT. ENOUGH DRY AIR MAY ALLOW TEMPS TO FALL IN THE NRN
CWA TO THE LOWER 60S TONIGHT...WITH MID TO UPPER 60S PREVALENT
ELSEWHERE.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
AS OF 400 AM EDT THURSDAY...
THE STRONG UPPER HIGH OVER THE MIDWEST WILL WEAKEN AS IT MOVES TO
THE FOUR CORNERS REGION LATE THIS WEEKEND. AS HEIGHTS LOWER OVER THE
SOUTHEASTERN/GULF COAST STATES...AND AN UPPER TROUGH STRENGTHENS
OVER THE GREAT LAKES...SOUPY HIGH PWAT AIR WILL BE FORCED NORTH FROM
THE GULF OF MEXICO AS WINDS BECOME S AND SW EVENTUALLY. BEFORE
THIS...JUST GARDEN VARIETY STORMS ACROSS EXTREME SW VA AND NW NC FOR
FRIDAY. GOOD UPSLOPE COMPONENT MOST OF THE DAY MAY KEEP SPOTS ALONG
THE SOUTHERN HALF OF THE BLUE RIDGE BELOW 80F. ALTHOUGH BOTH
SATURDAY AND SUNDAY HAVE THE POTENTIAL FOR SLOW MOVING STORMS AND
WATER PROBLEMS...ESPECIALLY ACROSS NW NC...AN UPPER WAVE WILL BE
INVOLVED SUNDAY WHICH SHOULD INCREASE COVERAGE. DESPITE A LOT OF
CLOUDS AND STORMS AROUND...H85 TEMPS IN THE UPPER TEENS WILL STILL
GET SOME SPOTS INTO THE MID 80S. STORMS WILL PROBABLY MORE SCATTERED
ACROSS THE SOUTHSIDE AND NC PIEDMONT THIS WEEKEND...SUCH THAT UPPER
80S MAY BE POSSIBLE THERE. ELSEWHERE...GUIDANCE TEMPS WILL PROBABLY
CONTINUE THEIR CURRENT WARM BIAS SO WENT A FEW DEGREES BELOW ON MAX
T EVERYWHERE ELSE.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 245 PM EDT WEDNESDAY
THE GFS/ECMWF/CANADIAN/GFS ENSEMBLES ARE ALL IN GOOD AGREEMENT THAT
THE UPPER TROF...WHICH HAS BEEN PERSISTENT ACROSS THE EASTERN U.S.
FOR MOST OF THE SUMMER...AMPLIFIES BY EARLY NEXT WEEK.
THERE ARE SOME MINOR DIFFERENCE WITH REGARD TO AMPLIFICATION WITH
THE ECMWF FORECASTING A SLIGHTLY DEEPER/SLOWER EASTERN U.S. TROF
COMPARED TO THE GFS AND CANADIAN MODELS. WITH THE BLOCKY
PATTERN...LEANED TOWARD THE STRONGER ECWMF SOLUTION.
AS THE UPPER TROF DEEPENS...A STRONG COLD FRONT WILL PUSH THROUGH
MONDAY NIGHT/EARLY TUESDAY BRINGING COOLER TEMPS...DRIER
WEATHER...AND LOWER DEW POINTS FOR TUESDAY AND WEDNESDAY.
BEFORE THE FRONTAL PASSAGE...DIURNALLY DRIVEN SHOWERS AND STORMS
WILL BE FOUND SUNDAY AND MONDAY. LOCALLY HEAVY RAIN WILL BE POSSIBLE
AS PWATS WILL BE 1-2 STANDARD DEVIATIONS ABOVE NORMAL PER THE GEFS.
FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT WENT BELOW GFS MOS
GUIDANCE FOR TEMPS WITH THE GEFS SHOWING 850MB TEMPS 1-2 STANDARD
DEVIATIONS BELOW NORMAL.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 130 PM EDT THURSDAY...
WEAK COLD FRONT WILL CONTINUE TO SINK SOUTH INTO THE
CAROLINAS...AS HIGH PRESSURE BUILD INTO OUR REGION FROM THE NORTH.
SCT TO BKN MVFR CLOUDS EXPECTED THIS AFTERNOON INTO TONIGHT.
MOST OF THE SHOWER/STORMS THIS AFTERNOON INTO TONIGHT WILL BE
CONFINED TO THE SOUTHERN BLUE RIDGE SOUTH OF ROA/BCB AND SOUTH OF
BLF. THEREFORE LEAVING ANY MENTION OUT OF THE TAFS GIVEN THREAT IS
20 PERCENT OR LESS.
THIS EVENING INTO TONIGHT...THE HIGH PRESSURE BEHIND THE FRONT
MOVES IN AND SKIES SHOULD CLEAR ENOUGH FOR FOG TO FORM AT MOST
STATIONS. DENSE FOG WILL OCCUR AT LWB/BCB WITH IFR VSBYS AT LYH.
MAYBE SOME LOWER CLOUDS MVFR AT ROA/DAN AND IFR AT BLF.
FOG/LOW CLOUDS ERODE FRIDAY MORNING...WITH A RETURN TO OVERALL
VFR CONDITIONS UNDER HIGH PRESSURE...WITH ONLY ISOLATED SHOWERS
AT BEST FRIDAY AFTERNOON AND SATURDAY. DEEPER MOISTURE WILL MAKE A
RETURN LATER IN THE WEEKEND WITH MORE IN THE WAY OF CONVECTIVE
DRIVEN SUB-VFR CONDITIONS POSSIBLE WITH A PASSING WARM FRONT
SUNDAY...AND ANOTHER COLD FRONT LATER MONDAY. OTHERWISE SOME
PATCHY FOG LIKELY DURING THE OVERNIGHTS INTO SATURDAY...WITH LATE
NIGHT/EARLY MORNING MVFR/IFR CONDITIONS POSSIBLE ESPECIALLY AT THE
VALLEY LOCATIONS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...WP/KK
NEAR TERM...KK/WP
SHORT TERM...KM
LONG TERM...PH
AVIATION...KK/WP
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
943 AM EDT THU AUG 29 2013
.SYNOPSIS...
A FRONTAL BOUNDARY SHIFTS SOUTH INTO NORTH CAROLINA BY LATE THIS
MORNING. WEAK HIGH PRESSURE SHOULD BUILD INTO THE AREA BEHIND IT
FOR THURSDAY AFTERNOON INTO FRIDAY BEFORE SLIDING OFFSHORE BY SATURDAY.
THIS WILL BRING A RETURN FLOW OF MOISTURE ALONG WITH AN ASSOCIATED
WARM FRONT LATER IN THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 940 AM EDT THURSDAY...
THIS MORNING 8AM/12Z RNK SOUNDING SHOWED PLENTY OF MOISTURE
UP TO 640 MB WITH A NORTHERLY FLOW. KFCX 88D INDICATED WIDELY
SCATTERED SHOWERS TRAVELING SOUTH THIS MORNING. COLD FRONT ACROSS
SOUTHERN PORTIONS OF CWA THIS MORNING WILL SLOWLY DRIFT SOUTH
TODAY. MADE SOME ADJUSTMENTS IN THE POPS TO SHAPE TOWARDS RADAR
TRENDS AND HRRR FOR NEXT COUPLE OF HOURS...THEN KEPT THE SCATTERED
STORMS IN FOR THE AFTERNOON INTO TONIGHT. THE BEST CHANCE REMAIN
ALONG THE SOUTHERN BLUE RIDGE THIS AFTERNOON WITH MOISTURE
CONVERGENCE. HIGH PRESSURE BUILDS SOUTH ACROSS THE REGION
TONIGHT. HIGH TEMPERATURES THIS AFTERNOON WILL RANGE FROM THE
UPPER 70S IN THE MOUNTAINS TO THE MID 80S IN THE PIEDMONT.
AS OF 315 AM EDT THURSDAY...
SOUPY AIRMASS IN PLACE THIS MORNING WITH TEMPS STILL RUNNING IN THE
70S OVER MUCH OF THE AREA. FRONTAL BOUNDARY SITUATED FROM LOW
PRESSURE OVER VA TIDEWATER NORTHWEST INTO NRN WV THEN INTO SRN
OHIO. HIGHER THETA-E ACROSS ERN KY/SRN WV SHIFTING SE INTO THE NC
MTNS WILL KEEP SHOWERS AROUND THRU AT LEAST MID MORNING...BUT
MAINLY ISOLATED.
AT THE MOMENT SKIES HAVE CLEARED OVER THE FOOTHILLS AND PIEDMONT
THANKS TO A CONSISTENT NNW FLOW DOWNSLOPING WIND. THIS WILL CHANGE
THRU DAYBREAK AS THE FLOW COMES AROUND TO THE NORTH THEN NORTHEAST.
STILL HINGING ON CLOUDS INCREASING ALONG THE BLUE RIDGE AND POINTS
EAST BUT THEN SLOWLY MIXING OUT TOWARD MIDDAY. THE 00Z CMC HAS A
PRETTY GOOD HANDLE EARLY...BUT DOES NOT REALLY ENHANCE LOW CLOUDS
DEVELOPING OVER THE BLUE RIDGE LIKE THE NAM DOES...SO LEANED TOWARD
A BLEND OF THE TWO.
THROUGH THE DAY...WILL BE DEALING WITH SOME DRYING ALOFT...BUT
KEEPING THE LOW LVLS MOIST...AS NOT MUCH CHANGE IN AIRMASS EXPECTED.
THERE WILL BE ENOUGH LOW LEVEL CONVERGENCE AROUND NEAR THE FRONT
THAT AT LEAST ISOLATED SHOWERS OR STORMS OCCUR THIS AFTERNOON. STILL
LOOKS LIKE THE SRN BLUE RIDGE HAS THE BEST CHANCE OF SEEING
SCATTERED COVERAGE GIVEN THE FORECAST CONVERGENCE PATTERN IN THE
WINDS.
GIVEN A LACK OF UPSTREAM CONVECTION AND CLOUDS...THINK THE SUN WILL
BREAK THROUGH TOWARD EARLY AFTERNOON IN THE NORTH...THEN MID
AFTERNOON ELSEWHERE. THESE LOWER CLOUDS MAY BE HARD TO MIX OUT UNTIL
LATE MORNING. FOR THE AFTERNOON ENOUGH SUN WILL AVAILABLE TO REALIZE
WARMER HIGHS...BUT SOUPY AIRMASS WILL STILL CUT INTO REALLY WARM
TEMPS...SO WENT CLOSE TO OR JUST BELOW MAV MOS WITH UPPER 70S/LOWER
80S WEST TO MID TO UPPER 80S ACROSS THE SOUTHERN SHENANDOAH
SOUTHEAST INTO SOUTHSIDE VA AND THE NC PIEDMONT/FOOTHILLS.
LOW LVLS WINDS CONTINUE TO SHIFT TOWARD THE EAST THEN SOUTHEAST LATE
TONIGHT AS HIGH PRESSURE NOSES SOUTH OVER THE ALLEGHANY HIGHLANDS.
STILL ENOUGH CONVERGENCE AND LOW LVL MOISTURE TO HANG ONTO POPS OF
THE 20/30 VARIETY OVER THE SOUTHERN BLUE RIDGE AND ADJACENT AREAS
THIS EVENING...GRADUALLY SHRINKING TO SLIGHT CHANCE OVER THE NC MTNS
AFTER MIDNIGHT. ENOUGH DRY AIR MAY ALLOW TEMPS TO FALL IN THE NRN
CWA TO THE LOWER 60S TONIGHT...WITH MID TO UPPER 60S PREVALENT
ELSEWHERE.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
AS OF 400 AM EDT THURSDAY...
THE STRONG UPPER HIGH OVER THE MIDWEST WILL WEAKEN AS IT MOVES TO
THE FOUR CORNERS REGION LATE THIS WEEKEND. AS HEIGHTS LOWER OVER THE
SOUTHEASTERN/GULF COAST STATES...AND AN UPPER TROUGH STRENGTHENS
OVER THE GREAT LAKES...SOUPY HIGH PWAT AIR WILL BE FORCED NORTH FROM
THE GULF OF MEXICO AS WINDS BECOME S AND SW EVENTUALLY. BEFORE
THIS...JUST GARDEN VARIETY STORMS ACROSS EXTREME SW VA AND NW NC FOR
FRIDAY. GOOD UPSLOPE COMPONENT MOST OF THE DAY MAY KEEP SPOTS ALONG
THE SOUTHERN HALF OF THE BLUE RIDGE BELOW 80F. ALTHOUGH BOTH
SATURDAY AND SUNDAY HAVE THE POTENTIAL FOR SLOW MOVING STORMS AND
WATER PROBLEMS...ESPECIALLY ACROSS NW NC...AN UPPER WAVE WILL BE
INVOLVED SUNDAY WHICH SHOULD INCREASE COVERAGE. DESPITE A LOT OF
CLOUDS AND STORMS AROUND...H85 TEMPS IN THE UPPER TEENS WILL STILL
GET SOME SPOTS INTO THE MID 80S. STORMS WILL PROBABLY MORE SCATTERED
ACROSS THE SOUTHSIDE AND NC PIEDMONT THIS WEEKEND...SUCH THAT UPPER
80S MAY BE POSSIBLE THERE. ELSEWHERE...GUIDANCE TEMPS WILL PROBABLY
CONTINUE THEIR CURRENT WARM BIAS SO WENT A FEW DEGREES BELOW ON MAX
T EVERYWHERE ELSE.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 245 PM EDT WEDNESDAY
THE GFS/ECMWF/CANADIAN/GFS ENSEMBLES ARE ALL IN GOOD AGREEMENT THAT
THE UPPER TROF...WHICH HAS BEEN PERSISTENT ACROSS THE EASTERN U.S.
FOR MOST OF THE SUMMER...AMPLIFIES BY EARLY NEXT WEEK.
THERE ARE SOME MINOR DIFFERENCE WITH REGARD TO AMPLIFICATION WITH
THE ECMWF FORECASTING A SLIGHTLY DEEPER/SLOWER EASTERN U.S. TROF
COMPARED TO THE GFS AND CANADIAN MODELS. WITH THE BLOCKY
PATTERN...LEANED TOWARD THE STRONGER ECWMF SOLUTION.
AS THE UPPER TROF DEEPENS...A STRONG COLD FRONT WILL PUSH THROUGH
MONDAY NIGHT/EARLY TUESDAY BRINGING COOLER TEMPS...DRIER
WEATHER...AND LOWER DEW POINTS FOR TUESDAY AND WEDNESDAY.
BEFORE THE FRONTAL PASSAGE...DIURNALLY DRIVEN SHOWERS AND STORMS
WILL BE FOUND SUNDAY AND MONDAY. LOCALLY HEAVY RAIN WILL BE POSSIBLE
AS PWATS WILL BE 1-2 STANDARD DEVIATIONS ABOVE NORMAL PER THE GEFS.
FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT WENT BELOW GFS MOS
GUIDANCE FOR TEMPS WITH THE GEFS SHOWING 850MB TEMPS 1-2 STANDARD
DEVIATIONS BELOW NORMAL.
&&
.AVIATION /13Z THURSDAY THROUGH MONDAY/...
AS OF 730 AM EDT THURSDAY...
IFR/MVFR CIGS/VSBYS WILL BE SLOW TO ERODE THIS MORNING AS THE FLOW
TURNS SLOWLY NORTH THEN NORTHEAST. A FEW SHOWERS FROM LYH TO NORTH
OF ROA SO KEEPING SOME VCSH IN AT THESE SITES AS WELL AS DAN BUT
NOT EXPECTING ANYTHING TOO HEAVY.
NOT MUCH CHANGE FROM PREVIOUS FORECAST AS EXPECT GRADUAL TREND TO
VFR BY EARLY AFTERNOON BUT SKIES STAYING BKN V SCT.
MOST OF THE SHOWER/STORMS THIS AFTERNOON WILL BE CONFINED TO THE
SOUTHERN BLUE RIDGE SOUTH OF ROA/BCB AND SOUTH OF BLF. THEREFORE
LEAVING ANY MENTION OUT OF THE TAFS GIVEN THREAT IS 20 PERCENT OR
LESS.
THIS EVENING...THE HIGH PRESSURE BEHIND THE FRONT MOVES IN AND
SKIES SHOULD CLEAR ENOUGH FOR FOG TO FORM AT MOST STATIONS. DENSE
FOG WILL OCCUR AT LWB/BCB WITH IFR VSBYS AT LYH. MAYBE SOME LOWER
CLOUDS MVFR AT ROA/DAN AND IFR AT BLF.
FOG/LOW CLOUDS ERODE FRIDAY MORNING...WITH A RETURN TO OVERALL
VFR CONDITIONS UNDER HIGH PRESSURE...WITH ONLY ISOLATED SHOWERS
AT BEST FRIDAY AFTERNOON AND SATURDAY. DEEPER MOISTURE WILL MAKE A
RETURN LATER IN THE WEEKEND WITH MORE IN THE WAY OF CONVECTIVE
DRIVEN SUB-VFR CONDITIONS POSSIBLE WITH A PASSING WARM FRONT
SUNDAY...AND ANOTHER COLD FRONT LATER MONDAY. OTHERWISE SOME
PATCHY FOG LIKELY DURING THE OVERNIGHTS INTO SATURDAY...WITH LATE
NIGHT/EARLY MORNING MVFR/IFR CONDITIONS POSSIBLE ESPECIALLY AT THE
VALLEY LOCATIONS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...WP
NEAR TERM...KK/WP
SHORT TERM...KM
LONG TERM...PH
AVIATION...JH/KK/WP
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
709 PM CDT FRI AUG 30 2013
.UPDATE...MAIN COLD FRONT IS MOVING SWWD AROUND 19KT THROUGH ERN
WI AT THIS TIME. AN OUTFLOW BOUNDARY THAT EXTENDS FROM N-S ACROSS
DANE AND GREEN COUNTIES IS STILL INITIATING ISOLD SHOWERS AND
TSTORMS OVER GREEN COUNTY AND MAY INITIATE MORE FOR THE NEXT HOUR OR
SO. OTHERWISE COLD ADVECTION TO TAKE HOLD BUT WEAKEN DURING THE
OVERNIGHT WITH SOME STRATUS AND LIGHT FOG EXPECTED. THE FOG AND
STRATUS WILL BURN OFF SAT AM WITH TEMPS REBOUNDING INTO THE MID TO
UPPER 70S LAKESIDE TO LOWER TO MID 80S WELL INLAND.
&&
.PREV DISCUSSION... /ISSUED 354 PM CDT FRI AUG 30 2013/
VERY SHORT TERM...TONIGHT AND SATURDAY.
TONIGHT - CONFIDENCE...MEDIUM
PLENTY OF CAPE POOLING AHEAD OF SOUTHWARD MOVING FRONTAL BOUNDARY.
STORMS ARE ORGAN ZING AS BEST AS THEY CAN GIVEN THE LACK OF DECENT
0-6KM SHEAR AND SUSPECT MID LEVEL LAPSE RATES. HOWEVER PLENTY OF
CAPE IN THE LOW LEVELS WITH GOOD LOW LEVEL LAPSE RATES WITH
SURFACE/925 CONVERGENCE ALLOWING FOR SOME STRONGER WINDS AND HAIL.
WATER VAPOR/RUC COMBO DOES SHOW A WEAK UPSTREAM WAVE RIDING IN
FROM SRN MN AND NRN IA. HRRR SHOWING STORMS CLEARING THE FAR SOUTH
AROUND 00Z OR SO. HOWEVER 4KM WRF-SPC AND 12Z ECMWF LINGER PRECIP
ACROSS PORTIONS OF SC WI DEEPER INTO THE EVENING. BASED ON FRONTAL
PROGRESSION WILL BANK ON A QUICKER EXIT OF PRECIP BASED ON OTHER
MODELS. SO FRONTAL BOUNDARY EXITS TO THE SOUTH THIS EVENING TAKING
ANY LINGERING STORMS WITH IT. WILL RETAIN HEAT ADVISORY FOR SOUTHERN
TIER ONLY AS I-94 CORRIDOR AFFECTED BY OUTFLOW AND STORMS.
SURFACE/925 COOL AIR ADVECTION THEN TAKES HOLD. NOT SO MUCH UP TO
850 MILLIBARS...BUT FROM 925 AND ON DOWN PRETTY STRONG SIGNAL AND
THIS IS PLAUSIBLE GIVEN CONDITIONS UPSTREAM IN NORTHERN WISCONSIN.
EXPECTING COOLER AND DRIER DEW POINTS TO ADVECT INTO THE AREA WITH
THE EVOLVING POST-FRONTAL NORTH WINDS. LOW LEVEL WIND FLOW/DEGREE OF
MIXING SUGGESTS THE EVOLUTION OF DENSE FOG NOT LIKELY. LOOKS MORE
LIKE STRATUS POTENTIAL.
SATURDAY - CONFIDENCE...MEDIUM HIGH PRESSURE SETTLES IN. MORNING
FOG/LOW STRATUS POTENTIAL WILL GRADUALLY BURN OFF. NOT A BIG
DROP OFF IN 850 TEMPS. NEVERTHELESS CU RULE SUPPORTIVE OF SCT
COVERAGE AFTER MORNING STRATUS. 925 TEMPS PROGGD TO 20-23C.
COMFORTABLY COOLER AND LESS HUMID. SO LOW TO MID 80S WITH
MID/UPPER 70S IN THE FAR EAST WITH THE SUSTAINED ONSHORE FLOW.
SHORT TERM...SATURDAY NIGHT THROUGH MONDAY.
SATURDAY NIGHT AND SUNDAY...FORECAST CONFIDENCE MEDIUM TO HIGH.
NEXT BEST CHANCE OF PRECIPITATION COMES WITH SHORT WAVE TROUGH AND
COLD FRONT. STILL SOME DIFFERENCES IN CONFIGURATION OF SHORT WAVE
THAT IMPACTS TIMING OF SURFACE TROUGH/COLD FRONT THROUGH REGION.
WILL GO WITH BLENDED SOLUTION THAT BRINGS A CHANCE TO THE NW CWA
BETWEEN 06Z AND 12Z SUNDAY...THEN HIGH CHANCE POPS ACROSS THE
ENTIRE FORECAST AREA DURING THE DAY SUNDAY. SHOULD SEE LOW TO MID
80S HIGHS PRIOR TO ONSET OF PCPN.
SUNDAY NIGHT AND MONDAY...FORECAST CONFIDENCE HIGH.
PRECIPITATION CHANCES LINGER INTO SUNDAY EVENING IN THE EAST WITH
HIGH PRESSURE BUILDING IN BEHIND. LABOR DAY MORE FALL-LIKE WITH
LOW TO MID 70 HIGHS.
LONG TERM...MONDAY NIGHT THROUGH FRIDAY...FORECAST CONFIDENCE
MEDIUM TO HIGH.
DRY WEATHER AS HIGH PRESSURE DOMINATES THE WESTERN GREAT LAKES REGION
UNDER NORTHWEST FLOW REGIME. MODELS TRY TO BRUSH SW/SOUTHERN CWA
WITH LIGHT QPF WITH A WEAK WAVE/WARM AIR ADVECTION BUT FOR NOW
WILL LEAVE DRY. BELOW NORMAL TEMPERATURES WILL WARM BACK TOWARD
NORMAL LEVELS...OR SLIGHTLY ABOVE...WEDNESDAY THROUGH THE REST OF
THE EXTENDED.
AVIATION/00Z TAFS/...
THUNDERSTORM POTENTIAL THROUGH 00Z WITH FRONTAL BOUNDARY DROPPING
IN FROM THE NORTH. WINDS WILL SHIFT TO THE NORTH IN THE WAKE OF
THE FRONT WITH THE EVENING FROPA. WILL MONITOR STRATUS TRENDS IN
THE COOL ADVECTION REGIME. EXPECT MVFR CEILINGS AND POTENTIAL FOR
IFR LATER TONIGHT INTO EARLY SATURDAY. THINKING ENOUGH MIXING WILL
INHIBIT DENSE FOG FORMATION.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...GEHRING
TONIGHT/SATURDAY AND AVIATION/MARINE...COLLAR
SATURDAY NIGHT THROUGH FRIDAY...REM
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1215 PM CDT THU AUG 29 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 300 AM CDT THU AUG 29 2013
..CURRENTLY AS OF 08Z..
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED A POTENT UPPER
TROUGH JUST OFF THE PACIFIC NORTHWEST COAST...STRONG SUBTROPICAL
RIDGING OVER THE CENTRAL PLAINS AND TROUGHING ALONG THE EAST COAST
OF THE U.S.. ROUNDING THE SUBTROPICAL RIDGE WAS A CLUSTER OF
SHORTWAVES OVER SOUTHERN SASKATCHEWAN AND NORTHERN NORTH DAKOTA.
SHOWERS AND THUNDERSTORMS HAVE BEEN ACCOMPANYING THESE SHORTWAVES...
WHICH ALSO ARE BEING AIDED BY MOISTURE TRANSPORT FROM SOUTHERLY
20-30 KT 850MB WINDS PER RADAR VWP DATA ACROSS THE WESTERN DAKOTAS.
EASTERN EXTENT OF THIS MOISTURE TRANSPORT HAS PRODUCED SOME STORMS
NEAR FARGO. FARTHER EAST OVER THE FORECAST AREA...CONDITIONS HAVE
REMAINED DRY THUS FAR DUE TO LITTLE IF ANY FORCING AS WELL AS STILL
SOME DRY AIR ABOVE THE SURFACE LINGERING AROUND AS SEEN IN THE 00Z
MPX SOUNDING. SURFACE MOISTURE REMAINS HIGH...ESPECIALLY OVER
NORTHERN IOWA AND SOUTHERN MN WHERE DEWPOINTS ARE IN THE LOW 70S.
THIS HIGHER MOISTURE IS POOLED ALONG A WARM FRONTAL BOUNDARY
BISECTING IOWA NORTHWEST TO SOUTHEAST. AIRMASS REMAINS WARM ACROSS
THE UPPER MIDWEST...WITH 925MB TEMPS AT 00Z RANGING FROM 22C AT
GRB...TO 25C AT MPX AND DVN...AND 27-29C AT ABR...BIS AND OAX.
..HAZARDS..
1. HEAT. HEAT INDICES ARE AGAIN EXPECTED TO CLIMB INTO THE 90 TO 100
RANGE...HIGHEST IN NORTHEAST IOWA...BUT STILL NOT HIGH ENOUGH TO
WARRANT A HEAT ADVISORY MENTION.
2. STORMS. BULK OF THE STORM ACTION IS EXPECTED NORTH OF THE
FORECAST AREA THROUGH TONIGHT. HOWEVER...THERE IS A SMALL CHANCE
SOME OF THE STORMS COULD ROLL THROUGH LOCATIONS NORTHEAST OF I-94
TONIGHT AND PRODUCE LARGE HAIL AND DAMAGING WINDS.
..SYNOPTIC OVERVIEW..
29.00Z MODEL GUIDANCE IS IN GOOD AGREEMENT SHOWING A RETROGRESSION
WESTWARD OF THE SUBTROPICAL RIDGE INTO COLORADO BY 12Z FRIDAY.
MEANWHILE...THE CLUSTER OF SHORTWAVES PRESENTLY TOPPING THE GENERAL
RIDGING ARE PROGGED TO CONTINUE MARCHING EAST...REACHING LAKE
SUPERIOR AND UPPER MICHIGAN BY 12Z FRIDAY. AS THESE SHORTWAVES PRESS
EAST...THE WARM FRONTAL BOUNDARY IN IOWA GETS LIFTED NORTHEAST...
PERHAPS ALL THE WAY INTO UPPER MI BY 12Z FRIDAY. ADDITIONALLY...ALL
INDICATIONS ARE THAT A LOW PRESSURE AREA WILL ACCOMPANY THE
SHORTWAVES...WHICH IS ALREADY EVIDENT OVER FAR SOUTHWEST NORTH
DAKOTA.
..DETAILS..
29.00Z MODEL GUIDANCE HAS DEFINITELY TRENDED DRIER FOR THE FORECAST
AREA FOR BOTH TODAY AND TONIGHT...A TREND THAT STARTED WITH THE
28.12Z MODEL GUIDANCE AND PREVIOUS FORECAST. IN FACT...THE 29.00Z
REGIONAL CANADIAN IS COMPLETELY DRY. CERTAINLY GIVEN THE TRACK OF
THE SHORTWAVES AND SURFACE LOW...CONFIDENCE IS VERY HIGH THAT
LOCATIONS NORTH OF HERE FROM NORTHERN MN THROUGH NORTHWEST WI AND
UPPER MI WILL SEE SHOWERS AND STORMS. THE ONLY QUESTION MARK IS IF
THE WARM FRONT LIFTING THROUGH THE AREA CAN SPARK ANY CONVECTION...
EITHER DRIVEN BY 310-315K ISENTROPIC LIFT / 850MB MOISTURE
TRANSPORT...OR THROUGH SURFACE BASED CONVECTION. THERE IS A THIRD
SCENARIO PRESENTED BY THE 29.00Z NAM...WHERE SOME OF THE CONVECTION
COMING OUT OF NORTH DAKOTA THIS MORNING ROLLS DOWN ALONG THE
FRONT...IMPACTING LOCATIONS ALONG/WEST OF THE MS RIVER. HOWEVER...
HRRR TRENDS SUGGEST THIS WILL NOT HAPPEN...WHICH MAKES SENSE TOO AS
THE STRONGEST LOW LEVEL MOISTURE TRANSPORT REMAINS AIMED NORTHWEST
AND NORTH OF THE AREA. CHECKING OUT SURFACE BASED CONVECTION
POTENTIAL...MODIFYING A VARIETY OF SOUNDINGS FROM THE RAP AS WELL AS
THE 29.00Z GFS ALL SHOW A CAP HOLDING IN PLACE...LOCATED AROUND
775MB. THIS CAP ORIGINATES FROM WARM AIR BEING ADVECTED IN SOUTH OF
THE SHORTWAVE TRACK. IMPRESSIVE TO SEE THAT ALL OF TODAY THE 29.00Z
GFS DOES NOT PRODUCE ANY PRECIPITATION...WHICH THAT SIGNAL ALONE
LENDS MORE CONFIDENCE TO A DRY FORECAST. TO HELP BLEND WITH
NEIGHBORING OFFICES TO THE NORTH...HAVE MAINTAINED 20 PERCENT
CHANCES ACROSS FAR NORTHERN PORTIONS OF THE FORECAST AREA.
AS WE HEAD INTO TONIGHT...THE 29.00Z GFS/NAM/ECMWF INDICATE
POTENTIAL FOR SOME CONVECTION NORTHEAST OF I-94 AS THE LOW LEVEL JET
STRENGTHENS. FEEL IT IS PRUDENT TO HAVE A 20-40 PERCENT CHANCE IN THIS
AREA. OTHERWISE CAPPING AND DRY CONDITIONS SHOULD DOMINATE THE REST
OF THE FORECAST AREA.
MUCH OF THE WARM ADVECTION TODAY OCCURRING SOUTH OF THE TRACK OF THE
SHORTWAVES IS PROGGED TO OCCUR UP IN THAT 700-800MB LAYER. 925MB
TEMPERATURES REALLY DO NOT RESPOND IN OUR FORECAST AREA UNTIL AFTER
00Z. 925MB READINGS ARE PROGGED VERY SIMILAR TO YESTERDAY...
THEREFORE...ANTICIPATING SIMILAR HIGHS. WITH DEWPOINTS RUNNING IN
THE UPPER 60S TO MID 70S...WE SHOULD SEE YET AGAIN ANOTHER DAY OF
HEAT INDICES IN THE 90-100 RANGE...HIGHEST OVER NORTHEAST IA WHERE
HIGHEST TEMPERATURES AND DEWPOINTS ARE EXPECTED. ANOTHER WARM NIGHT
ON TAP TONIGHT AS WARMER 925MB SURGES IN AND DEWPOINTS REMAIN UP.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 300 AM CDT THU AUG 29 2013
..HAZARDS..
1. HEAT. HEAT INDICES HAVE COME DOWN SLIGHTLY ACROSS NORTHEAST IOWA
FOR FRIDAY...NOW IN THE 95-100 RANGE. SATURDAY HAS ALSO COME
DOWN...NOW MOSTLY AT OR BELOW 90. SO IT IS POSSIBLE NOW THAT WE CAN
GET THROUGH LABOR DAY WEEKEND WITHOUT ANY HEAT ADVISORIES...A BIG
CHANGE FROM WHAT THINGS LOOKED LIKE 4-7 DAYS AGO.
..SYNOPTIC OVERVIEW..
FOCUS FOR MUCH OF THE LONG TERM PERIOD IS THE IMPACT THE TROUGH
CURRENTLY JUST OFF THE PACIFIC NORTHWEST WILL HAVE ON THE FORECAST
AREA. THIS TROUGH IS PROGGED TO BEGIN EJECTING OUT ON FRIDAY...
CAUSING RIDGING TO BUILD OVER THE NORTHERN PLAINS...AND IN RESPONSE
TURNING THE UPPER FLOW MORE NORTHWESTERLY OVER THE FORECAST AREA.
THIS NORTHWEST FLOW WILL HELP DRIVE A COLD FRONT THROUGH THE AREA ON
FRIDAY. HEADING INTO THE WEEKEND...THE TROUGH IS EXPECTED TO MARCH
ACROSS SOUTHERN CANADA...WITH GOOD MODEL AGREEMENT FOR IT TO DIG
INTO THE WESTERN GREAT LAKES REGION ON SUNDAY. A WARM FRONTAL
PASSAGE IS LIKELY AHEAD OF THE TROUGH LATE SATURDAY...FOLLOWED BY A
FAIRLY STRONG COLD FRONTAL PASSAGE SUNDAY MORNING. ALL INDICATIONS
ARE THAT THIS TROUGH WILL EVENTUALLY ENCOMPASS MUCH OF THE EASTERN
THIRD OF THE U.S. BY TUESDAY...ALLOWING HIGH PRESSURE TO COME INTO
THE FORECAST AREA AT THE SURFACE. THE FORECAST BEYOND TUESDAY IS
MORE UNCERTAIN...PARTICULARLY DRIVEN BY THE ECMWF WHICH SHOWS A VERY
POTENT NORTHERN STREAM SHORTWAVE TROUGH DROPPING DOWN INTO THE
WESTERN GREAT LAKES REGION ON WEDNESDAY. THE 29.00Z GFS/CANADIAN
SHOW THIS SAME FEATURE TOO...BUT KEEP IT MORE PROGRESSIVE AND
IMPACTING SOUTHEAST CANADA INSTEAD. THE TWO SCENARIOS ARE
DRAMATICALLY DIFFERENT WHEN IT COMES TO BOTH PRECIPITATION AND
TEMPERATURE FORECASTS.
..DETAILS..
WITH A COLD FRONT COMING THROUGH ON FRIDAY...THERE ARE QUESTIONS ON
CAN IT PRODUCE ANY PRECIPITATION...AS WELL AS ITS TIMING FOR IMPACT
ON TEMPERATURES. MODELS HAVE DEFINITELY SPED UP ON THE COLD FRONTAL
TIMING...ESPECIALLY THE 29.00Z ECMWF/CANADIAN...HAVING IT NOW REACH
DVN BY 00Z SATURDAY. IF THIS TREND CONTINUES...WE MAY NOT HAVE ANY
CONVECTION ON FRIDAY. HOWEVER...THE 29.00Z GFS/REGIONAL CANADIAN/NAM
DEPICT A SLOWER TIMING...SO HAVE KEPT SOME 20-30 PERCENT CHANCES
GOING FOR NOW. THE SPEEDING UP OF THE FRONT ALSO HELPS TO PUSH THE
SURGE OF WARM AIR COMING IN HERE TONIGHT SOUTHEAST QUICKER. AS A
RESULT...HIGHS HAVE BEEN LOWERED SLIGHTLY...WHICH ALSO LOWERS HEAT
INDICES.
MAINLY DRY CONDITIONS LOOK TO PREVAIL FRIDAY NIGHT THROUGH SATURDAY
AS HIGH PRESSURE BECOMES FIRMLY IN CONTROL. LOWERED TEMPERATURES A
BIT DURING THIS PERIOD AS THE AIR COMING IN IS A LITTLE COOLER THAN
PREVIOUSLY FORECAST.
THE WARM AIR SURGE AS WELL AS MOISTURE TRANSPORT AHEAD OF THE POTENT
SHORTWAVE CROSSING SOUTHERN CANADA COMES ACROSS THE AREA SATURDAY
NIGHT. 29.00Z GFS/ECMWF/NAM/CANADIAN ARE ALL IN GOOD AGREEMENT
SHOWING SOME SHOWERS AND THUNDERSTORMS IN THIS WARM ADVECTION SURGE
COMING INTO THE FORECAST AREA...ESPECIALLY AFTER MIDNIGHT. RAISED
CHANCES TO 40-50...HIGHEST OVER WESTERN PORTIONS OF THE FORECAST
AREA. SOME OF THESE CHANCES PERSIST INTO SUNDAY WITH THE COLD FRONT
COMING THROUGH. AS IT STANDS RIGHT NOW...THE BULK OF THE COLD
ADVECTION BEHIND THE FRONT APPEARS TO WAIT UNTIL AFTER SUNSET SUNDAY.
BEYOND SUNDAY...HIGH PRESSURE DOMINATES FOR THE MOST PART EXCEPT FOR
POSSIBLY A COLD FRONTAL PASSAGE ON WEDNESDAY PER 28.12Z/29.00Z
ECMWF. BOTH ECMWF MODELS SUGGEST THE FRONT WILL HAVE LITTLE MOISTURE
TO WORK WITH SO IT COMES THROUGH DRY. THEREFORE...DRY CONDITIONS ARE
FORECAST BEYOND SUNDAY. THE BIGGER THING WILL BE TEMPERATURES. 925MB
TEMPS PLUMMET FROM 22-25C ON SATURDAY...TO 18-22C ON SUNDAY...AND
14-17C ON MONDAY. GRADUAL WARMING IS EXPECTED FOR TUESDAY AND
POSSIBLY WEDNESDAY AS WELL...DEPENDING ON IF THAT COLD FRONT COMES
THROUGH OR NOT. LAST NOTE WOULD BE POTENTIAL FOR VALLEY FOG TUESDAY
MORNING...BUT TOO EARLY TO PUT THAT IN THE FORECAST AT THIS TIME
GIVEN HOW SENSITIVE VALLEY FOG CAN BE TO OTHER VARIABLES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1215 PM CDT THU AUG 29 2013
VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD. A WEAK
FRONTAL BOUNDARY WILL APPROACH THE TAF SITES FROM WESTERN
MINNESOTA TONIGHT BRINGING AN INCREASE IN MID LEVEL CLOUDS.
ALSO...A WEAK LOW LEVEL JET DEVELOPS TONIGHT WITH WINDS
INCREASING TO AROUND 30 KTS AT 1200FT. WILL HAVE TO KEEP A VERY
CLOSE EYE ON THE POTENTIAL FOR LOW LEVEL WIND SHEAR LATE TONIGHT
INTO EARLY FRIDAY MORNING. OTHERWISE...THE FRONT WILL MAKE ITS WAY
ACROSS THE TAF SITES LATE TONIGHT INTO EARLY MONDAY MORNING WITH
WINDS SWITCHING TO THE NORTH AT 9 TO 12 KTS IN ITS WAKE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
643 AM CDT THU AUG 29 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 300 AM CDT THU AUG 29 2013
..CURRENTLY AS OF 08Z..
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED A POTENT UPPER
TROUGH JUST OFF THE PACIFIC NORTHWEST COAST...STRONG SUBTROPICAL
RIDGING OVER THE CENTRAL PLAINS AND TROUGHING ALONG THE EAST COAST
OF THE U.S.. ROUNDING THE SUBTROPICAL RIDGE WAS A CLUSTER OF
SHORTWAVES OVER SOUTHERN SASKATCHEWAN AND NORTHERN NORTH DAKOTA.
SHOWERS AND THUNDERSTORMS HAVE BEEN ACCOMPANYING THESE SHORTWAVES...
WHICH ALSO ARE BEING AIDED BY MOISTURE TRANSPORT FROM SOUTHERLY
20-30 KT 850MB WINDS PER RADAR VWP DATA ACROSS THE WESTERN DAKOTAS.
EASTERN EXTENT OF THIS MOISTURE TRANSPORT HAS PRODUCED SOME STORMS
NEAR FARGO. FARTHER EAST OVER THE FORECAST AREA...CONDITIONS HAVE
REMAINED DRY THUS FAR DUE TO LITTLE IF ANY FORCING AS WELL AS STILL
SOME DRY AIR ABOVE THE SURFACE LINGERING AROUND AS SEEN IN THE 00Z
MPX SOUNDING. SURFACE MOISTURE REMAINS HIGH...ESPECIALLY OVER
NORTHERN IOWA AND SOUTHERN MN WHERE DEWPOINTS ARE IN THE LOW 70S.
THIS HIGHER MOISTURE IS POOLED ALONG A WARM FRONTAL BOUNDARY
BISECTING IOWA NORTHWEST TO SOUTHEAST. AIRMASS REMAINS WARM ACROSS
THE UPPER MIDWEST...WITH 925MB TEMPS AT 00Z RANGING FROM 22C AT
GRB...TO 25C AT MPX AND DVN...AND 27-29C AT ABR...BIS AND OAX.
..HAZARDS..
1. HEAT. HEAT INDICES ARE AGAIN EXPECTED TO CLIMB INTO THE 90 TO 100
RANGE...HIGHEST IN NORTHEAST IOWA...BUT STILL NOT HIGH ENOUGH TO
WARRANT A HEAT ADVISORY MENTION.
2. STORMS. BULK OF THE STORM ACTION IS EXPECTED NORTH OF THE
FORECAST AREA THROUGH TONIGHT. HOWEVER...THERE IS A SMALL CHANCE
SOME OF THE STORMS COULD ROLL THROUGH LOCATIONS NORTHEAST OF I-94
TONIGHT AND PRODUCE LARGE HAIL AND DAMAGING WINDS.
..SYNOPTIC OVERVIEW..
29.00Z MODEL GUIDANCE IS IN GOOD AGREEMENT SHOWING A RETROGRESSION
WESTWARD OF THE SUBTROPICAL RIDGE INTO COLORADO BY 12Z FRIDAY.
MEANWHILE...THE CLUSTER OF SHORTWAVES PRESENTLY TOPPING THE GENERAL
RIDGING ARE PROGGED TO CONTINUE MARCHING EAST...REACHING LAKE
SUPERIOR AND UPPER MICHIGAN BY 12Z FRIDAY. AS THESE SHORTWAVES PRESS
EAST...THE WARM FRONTAL BOUNDARY IN IOWA GETS LIFTED NORTHEAST...
PERHAPS ALL THE WAY INTO UPPER MI BY 12Z FRIDAY. ADDITIONALLY...ALL
INDICATIONS ARE THAT A LOW PRESSURE AREA WILL ACCOMPANY THE
SHORTWAVES...WHICH IS ALREADY EVIDENT OVER FAR SOUTHWEST NORTH
DAKOTA.
..DETAILS..
29.00Z MODEL GUIDANCE HAS DEFINITELY TRENDED DRIER FOR THE FORECAST
AREA FOR BOTH TODAY AND TONIGHT...A TREND THAT STARTED WITH THE
28.12Z MODEL GUIDANCE AND PREVIOUS FORECAST. IN FACT...THE 29.00Z
REGIONAL CANADIAN IS COMPLETELY DRY. CERTAINLY GIVEN THE TRACK OF
THE SHORTWAVES AND SURFACE LOW...CONFIDENCE IS VERY HIGH THAT
LOCATIONS NORTH OF HERE FROM NORTHERN MN THROUGH NORTHWEST WI AND
UPPER MI WILL SEE SHOWERS AND STORMS. THE ONLY QUESTION MARK IS IF
THE WARM FRONT LIFTING THROUGH THE AREA CAN SPARK ANY CONVECTION...
EITHER DRIVEN BY 310-315K ISENTROPIC LIFT / 850MB MOISTURE
TRANSPORT...OR THROUGH SURFACE BASED CONVECTION. THERE IS A THIRD
SCENARIO PRESENTED BY THE 29.00Z NAM...WHERE SOME OF THE CONVECTION
COMING OUT OF NORTH DAKOTA THIS MORNING ROLLS DOWN ALONG THE
FRONT...IMPACTING LOCATIONS ALONG/WEST OF THE MS RIVER. HOWEVER...
HRRR TRENDS SUGGEST THIS WILL NOT HAPPEN...WHICH MAKES SENSE TOO AS
THE STRONGEST LOW LEVEL MOISTURE TRANSPORT REMAINS AIMED NORTHWEST
AND NORTH OF THE AREA. CHECKING OUT SURFACE BASED CONVECTION
POTENTIAL...MODIFYING A VARIETY OF SOUNDINGS FROM THE RAP AS WELL AS
THE 29.00Z GFS ALL SHOW A CAP HOLDING IN PLACE...LOCATED AROUND
775MB. THIS CAP ORIGINATES FROM WARM AIR BEING ADVECTED IN SOUTH OF
THE SHORTWAVE TRACK. IMPRESSIVE TO SEE THAT ALL OF TODAY THE 29.00Z
GFS DOES NOT PRODUCE ANY PRECIPITATION...WHICH THAT SIGNAL ALONE
LENDS MORE CONFIDENCE TO A DRY FORECAST. TO HELP BLEND WITH
NEIGHBORING OFFICES TO THE NORTH...HAVE MAINTAINED 20 PERCENT
CHANCES ACROSS FAR NORTHERN PORTIONS OF THE FORECAST AREA.
AS WE HEAD INTO TONIGHT...THE 29.00Z GFS/NAM/ECMWF INDICATE
POTENTIAL FOR SOME CONVECTION NORTHEAST OF I-94 AS THE LOW LEVEL JET
STRENGTHENS. FEEL IT IS PRUDENT TO HAVE A 20-40 PERCENT CHANCE IN THIS
AREA. OTHERWISE CAPPING AND DRY CONDITIONS SHOULD DOMINATE THE REST
OF THE FORECAST AREA.
MUCH OF THE WARM ADVECTION TODAY OCCURRING SOUTH OF THE TRACK OF THE
SHORTWAVES IS PROGGED TO OCCUR UP IN THAT 700-800MB LAYER. 925MB
TEMPERATURES REALLY DO NOT RESPOND IN OUR FORECAST AREA UNTIL AFTER
00Z. 925MB READINGS ARE PROGGED VERY SIMILAR TO YESTERDAY...
THEREFORE...ANTICIPATING SIMILAR HIGHS. WITH DEWPOINTS RUNNING IN
THE UPPER 60S TO MID 70S...WE SHOULD SEE YET AGAIN ANOTHER DAY OF
HEAT INDICES IN THE 90-100 RANGE...HIGHEST OVER NORTHEAST IA WHERE
HIGHEST TEMPERATURES AND DEWPOINTS ARE EXPECTED. ANOTHER WARM NIGHT
ON TAP TONIGHT AS WARMER 925MB SURGES IN AND DEWPOINTS REMAIN UP.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 300 AM CDT THU AUG 29 2013
..HAZARDS..
1. HEAT. HEAT INDICES HAVE COME DOWN SLIGHTLY ACROSS NORTHEAST IOWA
FOR FRIDAY...NOW IN THE 95-100 RANGE. SATURDAY HAS ALSO COME
DOWN...NOW MOSTLY AT OR BELOW 90. SO IT IS POSSIBLE NOW THAT WE CAN
GET THROUGH LABOR DAY WEEKEND WITHOUT ANY HEAT ADVISORIES...A BIG
CHANGE FROM WHAT THINGS LOOKED LIKE 4-7 DAYS AGO.
..SYNOPTIC OVERVIEW..
FOCUS FOR MUCH OF THE LONG TERM PERIOD IS THE IMPACT THE TROUGH
CURRENTLY JUST OFF THE PACIFIC NORTHWEST WILL HAVE ON THE FORECAST
AREA. THIS TROUGH IS PROGGED TO BEGIN EJECTING OUT ON FRIDAY...
CAUSING RIDGING TO BUILD OVER THE NORTHERN PLAINS...AND IN RESPONSE
TURNING THE UPPER FLOW MORE NORTHWESTERLY OVER THE FORECAST AREA.
THIS NORTHWEST FLOW WILL HELP DRIVE A COLD FRONT THROUGH THE AREA ON
FRIDAY. HEADING INTO THE WEEKEND...THE TROUGH IS EXPECTED TO MARCH
ACROSS SOUTHERN CANADA...WITH GOOD MODEL AGREEMENT FOR IT TO DIG
INTO THE WESTERN GREAT LAKES REGION ON SUNDAY. A WARM FRONTAL
PASSAGE IS LIKELY AHEAD OF THE TROUGH LATE SATURDAY...FOLLOWED BY A
FAIRLY STRONG COLD FRONTAL PASSAGE SUNDAY MORNING. ALL INDICATIONS
ARE THAT THIS TROUGH WILL EVENTUALLY ENCOMPASS MUCH OF THE EASTERN
THIRD OF THE U.S. BY TUESDAY...ALLOWING HIGH PRESSURE TO COME INTO
THE FORECAST AREA AT THE SURFACE. THE FORECAST BEYOND TUESDAY IS
MORE UNCERTAIN...PARTICULARLY DRIVEN BY THE ECMWF WHICH SHOWS A VERY
POTENT NORTHERN STREAM SHORTWAVE TROUGH DROPPING DOWN INTO THE
WESTERN GREAT LAKES REGION ON WEDNESDAY. THE 29.00Z GFS/CANADIAN
SHOW THIS SAME FEATURE TOO...BUT KEEP IT MORE PROGRESSIVE AND
IMPACTING SOUTHEAST CANADA INSTEAD. THE TWO SCENARIOS ARE
DRAMATICALLY DIFFERENT WHEN IT COMES TO BOTH PRECIPITATION AND
TEMPERATURE FORECASTS.
..DETAILS..
WITH A COLD FRONT COMING THROUGH ON FRIDAY...THERE ARE QUESTIONS ON
CAN IT PRODUCE ANY PRECIPITATION...AS WELL AS ITS TIMING FOR IMPACT
ON TEMPERATURES. MODELS HAVE DEFINITELY SPED UP ON THE COLD FRONTAL
TIMING...ESPECIALLY THE 29.00Z ECMWF/CANADIAN...HAVING IT NOW REACH
DVN BY 00Z SATURDAY. IF THIS TREND CONTINUES...WE MAY NOT HAVE ANY
CONVECTION ON FRIDAY. HOWEVER...THE 29.00Z GFS/REGIONAL CANADIAN/NAM
DEPICT A SLOWER TIMING...SO HAVE KEPT SOME 20-30 PERCENT CHANCES
GOING FOR NOW. THE SPEEDING UP OF THE FRONT ALSO HELPS TO PUSH THE
SURGE OF WARM AIR COMING IN HERE TONIGHT SOUTHEAST QUICKER. AS A
RESULT...HIGHS HAVE BEEN LOWERED SLIGHTLY...WHICH ALSO LOWERS HEAT
INDICES.
MAINLY DRY CONDITIONS LOOK TO PREVAIL FRIDAY NIGHT THROUGH SATURDAY
AS HIGH PRESSURE BECOMES FIRMLY IN CONTROL. LOWERED TEMPERATURES A
BIT DURING THIS PERIOD AS THE AIR COMING IN IS A LITTLE COOLER THAN
PREVIOUSLY FORECAST.
THE WARM AIR SURGE AS WELL AS MOISTURE TRANSPORT AHEAD OF THE POTENT
SHORTWAVE CROSSING SOUTHERN CANADA COMES ACROSS THE AREA SATURDAY
NIGHT. 29.00Z GFS/ECMWF/NAM/CANADIAN ARE ALL IN GOOD AGREEMENT
SHOWING SOME SHOWERS AND THUNDERSTORMS IN THIS WARM ADVECTION SURGE
COMING INTO THE FORECAST AREA...ESPECIALLY AFTER MIDNIGHT. RAISED
CHANCES TO 40-50...HIGHEST OVER WESTERN PORTIONS OF THE FORECAST
AREA. SOME OF THESE CHANCES PERSIST INTO SUNDAY WITH THE COLD FRONT
COMING THROUGH. AS IT STANDS RIGHT NOW...THE BULK OF THE COLD
ADVECTION BEHIND THE FRONT APPEARS TO WAIT UNTIL AFTER SUNSET SUNDAY.
BEYOND SUNDAY...HIGH PRESSURE DOMINATES FOR THE MOST PART EXCEPT FOR
POSSIBLY A COLD FRONTAL PASSAGE ON WEDNESDAY PER 28.12Z/29.00Z
ECMWF. BOTH ECMWF MODELS SUGGEST THE FRONT WILL HAVE LITTLE MOISTURE
TO WORK WITH SO IT COMES THROUGH DRY. THEREFORE...DRY CONDITIONS ARE
FORECAST BEYOND SUNDAY. THE BIGGER THING WILL BE TEMPERATURES. 925MB
TEMPS PLUMMET FROM 22-25C ON SATURDAY...TO 18-22C ON SUNDAY...AND
14-17C ON MONDAY. GRADUAL WARMING IS EXPECTED FOR TUESDAY AND
POSSIBLY WEDNESDAY AS WELL...DEPENDING ON IF THAT COLD FRONT COMES
THROUGH OR NOT. LAST NOTE WOULD BE POTENTIAL FOR VALLEY FOG TUESDAY
MORNING...BUT TOO EARLY TO PUT THAT IN THE FORECAST AT THIS TIME
GIVEN HOW SENSITIVE VALLEY FOG CAN BE TO OTHER VARIABLES.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 642 AM CDT THU AUG 29 2013
MVFR CLOUDS DEVELOPED ALONG THE INTERSTATE 90 CORRIDOR OVERNIGHT.
THESE CLOUDS ARE AFFECTING KLSE AND VERY NEAR KRST. HRRR AND RAP
SUGGEST THAT THESE CLOUDS WILL DISSIPATE BETWEEN 29.15Z AND
29.17Z. A WARM FRONT WILL PRODUCE A BROKEN DECK OF 5K FOOT CLOUD
BETWEEN 29.21Z AND 30.03Z AT BOTH TAF SITES. THERE MAY BE SOME
SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THIS FRONT...BUT IT
LOOKS LIKE THE CAP WILL BE STRONG TO PROHIBIT THEM FROM OCCURRING
AT THE TAF SITES.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
300 AM CDT THU AUG 29 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 300 AM CDT THU AUG 29 2013
..CURRENTLY AS OF 08Z..
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED A POTENT UPPER
TROUGH JUST OFF THE PACIFIC NORTHWEST COAST...STRONG SUBTROPICAL
RIDGING OVER THE CENTRAL PLAINS AND TROUGHING ALONG THE EAST COAST
OF THE U.S.. ROUNDING THE SUBTROPICAL RIDGE WAS A CLUSTER OF
SHORTWAVES OVER SOUTHERN SASKATCHEWAN AND NORTHERN NORTH DAKOTA.
SHOWERS AND THUNDERSTORMS HAVE BEEN ACCOMPANYING THESE SHORTWAVES...
WHICH ALSO ARE BEING AIDED BY MOISTURE TRANSPORT FROM SOUTHERLY
20-30 KT 850MB WINDS PER RADAR VWP DATA ACROSS THE WESTERN DAKOTAS.
EASTERN EXTENT OF THIS MOISTURE TRANSPORT HAS PRODUCED SOME STORMS
NEAR FARGO. FARTHER EAST OVER THE FORECAST AREA...CONDITIONS HAVE
REMAINED DRY THUS FAR DUE TO LITTLE IF ANY FORCING AS WELL AS STILL
SOME DRY AIR ABOVE THE SURFACE LINGERING AROUND AS SEEN IN THE 00Z
MPX SOUNDING. SURFACE MOISTURE REMAINS HIGH...ESPECIALLY OVER
NORTHERN IOWA AND SOUTHERN MN WHERE DEWPOINTS ARE IN THE LOW 70S.
THIS HIGHER MOISTURE IS POOLED ALONG A WARM FRONTAL BOUNDARY
BISECTING IOWA NORTHWEST TO SOUTHEAST. AIRMASS REMAINS WARM ACROSS
THE UPPER MIDWEST...WITH 925MB TEMPS AT 00Z RANGING FROM 22C AT
GRB...TO 25C AT MPX AND DVN...AND 27-29C AT ABR...BIS AND OAX.
..HAZARDS..
1. HEAT. HEAT INDICES ARE AGAIN EXPECTED TO CLIMB INTO THE 90 TO 100
RANGE...HIGHEST IN NORTHEAST IOWA...BUT STILL NOT HIGH ENOUGH TO
WARRANT A HEAT ADVISORY MENTION.
2. STORMS. BULK OF THE STORM ACTION IS EXPECTED NORTH OF THE
FORECAST AREA THROUGH TONIGHT. HOWEVER...THERE IS A SMALL CHANCE
SOME OF THE STORMS COULD ROLL THROUGH LOCATIONS NORTHEAST OF I-94
TONIGHT AND PRODUCE LARGE HAIL AND DAMAGING WINDS.
..SYNOPTIC OVERVIEW..
29.00Z MODEL GUIDANCE IS IN GOOD AGREEMENT SHOWING A RETROGRESSION
WESTWARD OF THE SUBTROPICAL RIDGE INTO COLORADO BY 12Z FRIDAY.
MEANWHILE...THE CLUSTER OF SHORTWAVES PRESENTLY TOPPING THE GENERAL
RIDGING ARE PROGGED TO CONTINUE MARCHING EAST...REACHING LAKE
SUPERIOR AND UPPER MICHIGAN BY 12Z FRIDAY. AS THESE SHORTWAVES PRESS
EAST...THE WARM FRONTAL BOUNDARY IN IOWA GETS LIFTED NORTHEAST...
PERHAPS ALL THE WAY INTO UPPER MI BY 12Z FRIDAY. ADDITIONALLY...ALL
INDICATIONS ARE THAT A LOW PRESSURE AREA WILL ACCOMPANY THE
SHORTWAVES...WHICH IS ALREADY EVIDENT OVER FAR SOUTHWEST NORTH
DAKOTA.
..DETAILS..
29.00Z MODEL GUIDANCE HAS DEFINITELY TRENDED DRIER FOR THE FORECAST
AREA FOR BOTH TODAY AND TONIGHT...A TREND THAT STARTED WITH THE
28.12Z MODEL GUIDANCE AND PREVIOUS FORECAST. IN FACT...THE 29.00Z
REGIONAL CANADIAN IS COMPLETELY DRY. CERTAINLY GIVEN THE TRACK OF
THE SHORTWAVES AND SURFACE LOW...CONFIDENCE IS VERY HIGH THAT
LOCATIONS NORTH OF HERE FROM NORTHERN MN THROUGH NORTHWEST WI AND
UPPER MI WILL SEE SHOWERS AND STORMS. THE ONLY QUESTION MARK IS IF
THE WARM FRONT LIFTING THROUGH THE AREA CAN SPARK ANY CONVECTION...
EITHER DRIVEN BY 310-315K ISENTROPIC LIFT / 850MB MOISTURE
TRANSPORT...OR THROUGH SURFACE BASED CONVECTION. THERE IS A THIRD
SCENARIO PRESENTED BY THE 29.00Z NAM...WHERE SOME OF THE CONVECTION
COMING OUT OF NORTH DAKOTA THIS MORNING ROLLS DOWN ALONG THE
FRONT...IMPACTING LOCATIONS ALONG/WEST OF THE MS RIVER. HOWEVER...
HRRR TRENDS SUGGEST THIS WILL NOT HAPPEN...WHICH MAKES SENSE TOO AS
THE STRONGEST LOW LEVEL MOISTURE TRANSPORT REMAINS AIMED NORTHWEST
AND NORTH OF THE AREA. CHECKING OUT SURFACE BASED CONVECTION
POTENTIAL...MODIFYING A VARIETY OF SOUNDINGS FROM THE RAP AS WELL AS
THE 29.00Z GFS ALL SHOW A CAP HOLDING IN PLACE...LOCATED AROUND
775MB. THIS CAP ORIGINATES FROM WARM AIR BEING ADVECTED IN SOUTH OF
THE SHORTWAVE TRACK. IMPRESSIVE TO SEE THAT ALL OF TODAY THE 29.00Z
GFS DOES NOT PRODUCE ANY PRECIPITATION...WHICH THAT SIGNAL ALONE
LENDS MORE CONFIDENCE TO A DRY FORECAST. TO HELP BLEND WITH
NEIGHBORING OFFICES TO THE NORTH...HAVE MAINTAINED 20 PERCENT
CHANCES ACROSS FAR NORTHERN PORTIONS OF THE FORECAST AREA.
AS WE HEAD INTO TONIGHT...THE 29.00Z GFS/NAM/ECMWF INDICATE
POTENTIAL FOR SOME CONVECTION NORTHEAST OF I-94 AS THE LOW LEVEL JET
STRENGTHENS. FEEL IT IS PRUDENT TO HAVE A 20-40 PERCENT CHANCE IN THIS
AREA. OTHERWISE CAPPING AND DRY CONDITIONS SHOULD DOMINATE THE REST
OF THE FORECAST AREA.
MUCH OF THE WARM ADVECTION TODAY OCCURRING SOUTH OF THE TRACK OF THE
SHORTWAVES IS PROGGED TO OCCUR UP IN THAT 700-800MB LAYER. 925MB
TEMPERATURES REALLY DO NOT RESPOND IN OUR FORECAST AREA UNTIL AFTER
00Z. 925MB READINGS ARE PROGGED VERY SIMILAR TO YESTERDAY...
THEREFORE...ANTICIPATING SIMILAR HIGHS. WITH DEWPOINTS RUNNING IN
THE UPPER 60S TO MID 70S...WE SHOULD SEE YET AGAIN ANOTHER DAY OF
HEAT INDICES IN THE 90-100 RANGE...HIGHEST OVER NORTHEAST IA WHERE
HIGHEST TEMPERATURES AND DEWPOINTS ARE EXPECTED. ANOTHER WARM NIGHT
ON TAP TONIGHT AS WARMER 925MB SURGES IN AND DEWPOINTS REMAIN UP.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 300 AM CDT THU AUG 29 2013
..HAZARDS..
1. HEAT. HEAT INDICES HAVE COME DOWN SLIGHTLY ACROSS NORTHEAST IOWA
FOR FRIDAY...NOW IN THE 95-100 RANGE. SATURDAY HAS ALSO COME
DOWN...NOW MOSTLY AT OR BELOW 90. SO IT IS POSSIBLE NOW THAT WE CAN
GET THROUGH LABOR DAY WEEKEND WITHOUT ANY HEAT ADVISORIES...A BIG
CHANGE FROM WHAT THINGS LOOKED LIKE 4-7 DAYS AGO.
..SYNOPTIC OVERVIEW..
FOCUS FOR MUCH OF THE LONG TERM PERIOD IS THE IMPACT THE TROUGH
CURRENTLY JUST OFF THE PACIFIC NORTHWEST WILL HAVE ON THE FORECAST
AREA. THIS TROUGH IS PROGGED TO BEGIN EJECTING OUT ON FRIDAY...
CAUSING RIDGING TO BUILD OVER THE NORTHERN PLAINS...AND IN RESPONSE
TURNING THE UPPER FLOW MORE NORTHWESTERLY OVER THE FORECAST AREA.
THIS NORTHWEST FLOW WILL HELP DRIVE A COLD FRONT THROUGH THE AREA ON
FRIDAY. HEADING INTO THE WEEKEND...THE TROUGH IS EXPECTED TO MARCH
ACROSS SOUTHERN CANADA...WITH GOOD MODEL AGREEMENT FOR IT TO DIG
INTO THE WESTERN GREAT LAKES REGION ON SUNDAY. A WARM FRONTAL
PASSAGE IS LIKELY AHEAD OF THE TROUGH LATE SATURDAY...FOLLOWED BY A
FAIRLY STRONG COLD FRONTAL PASSAGE SUNDAY MORNING. ALL INDICATIONS
ARE THAT THIS TROUGH WILL EVENTUALLY ENCOMPASS MUCH OF THE EASTERN
THIRD OF THE U.S. BY TUESDAY...ALLOWING HIGH PRESSURE TO COME INTO
THE FORECAST AREA AT THE SURFACE. THE FORECAST BEYOND TUESDAY IS
MORE UNCERTAIN...PARTICULARLY DRIVEN BY THE ECMWF WHICH SHOWS A VERY
POTENT NORTHERN STREAM SHORTWAVE TROUGH DROPPING DOWN INTO THE
WESTERN GREAT LAKES REGION ON WEDNESDAY. THE 29.00Z GFS/CANADIAN
SHOW THIS SAME FEATURE TOO...BUT KEEP IT MORE PROGRESSIVE AND
IMPACTING SOUTHEAST CANADA INSTEAD. THE TWO SCENARIOS ARE
DRAMATICALLY DIFFERENT WHEN IT COMES TO BOTH PRECIPITATION AND
TEMPERATURE FORECASTS.
..DETAILS..
WITH A COLD FRONT COMING THROUGH ON FRIDAY...THERE ARE QUESTIONS ON
CAN IT PRODUCE ANY PRECIPITATION...AS WELL AS ITS TIMING FOR IMPACT
ON TEMPERATURES. MODELS HAVE DEFINITELY SPED UP ON THE COLD FRONTAL
TIMING...ESPECIALLY THE 29.00Z ECMWF/CANADIAN...HAVING IT NOW REACH
DVN BY 00Z SATURDAY. IF THIS TREND CONTINUES...WE MAY NOT HAVE ANY
CONVECTION ON FRIDAY. HOWEVER...THE 29.00Z GFS/REGIONAL CANADIAN/NAM
DEPICT A SLOWER TIMING...SO HAVE KEPT SOME 20-30 PERCENT CHANCES
GOING FOR NOW. THE SPEEDING UP OF THE FRONT ALSO HELPS TO PUSH THE
SURGE OF WARM AIR COMING IN HERE TONIGHT SOUTHEAST QUICKER. AS A
RESULT...HIGHS HAVE BEEN LOWERED SLIGHTLY...WHICH ALSO LOWERS HEAT
INDICES.
MAINLY DRY CONDITIONS LOOK TO PREVAIL FRIDAY NIGHT THROUGH SATURDAY
AS HIGH PRESSURE BECOMES FIRMLY IN CONTROL. LOWERED TEMPERATURES A
BIT DURING THIS PERIOD AS THE AIR COMING IN IS A LITTLE COOLER THAN
PREVIOUSLY FORECAST.
THE WARM AIR SURGE AS WELL AS MOISTURE TRANSPORT AHEAD OF THE POTENT
SHORTWAVE CROSSING SOUTHERN CANADA COMES ACROSS THE AREA SATURDAY
NIGHT. 29.00Z GFS/ECMWF/NAM/CANADIAN ARE ALL IN GOOD AGREEMENT
SHOWING SOME SHOWERS AND THUNDERSTORMS IN THIS WARM ADVECTION SURGE
COMING INTO THE FORECAST AREA...ESPECIALLY AFTER MIDNIGHT. RAISED
CHANCES TO 40-50...HIGHEST OVER WESTERN PORTIONS OF THE FORECAST
AREA. SOME OF THESE CHANCES PERSIST INTO SUNDAY WITH THE COLD FRONT
COMING THROUGH. AS IT STANDS RIGHT NOW...THE BULK OF THE COLD
ADVECTION BEHIND THE FRONT APPEARS TO WAIT UNTIL AFTER SUNSET SUNDAY.
BEYOND SUNDAY...HIGH PRESSURE DOMINATES FOR THE MOST PART EXCEPT FOR
POSSIBLY A COLD FRONTAL PASSAGE ON WEDNESDAY PER 28.12Z/29.00Z
ECMWF. BOTH ECMWF MODELS SUGGEST THE FRONT WILL HAVE LITTLE MOISTURE
TO WORK WITH SO IT COMES THROUGH DRY. THEREFORE...DRY CONDITIONS ARE
FORECAST BEYOND SUNDAY. THE BIGGER THING WILL BE TEMPERATURES. 925MB
TEMPS PLUMMET FROM 22-25C ON SATURDAY...TO 18-22C ON SUNDAY...AND
14-17C ON MONDAY. GRADUAL WARMING IS EXPECTED FOR TUESDAY AND
POSSIBLY WEDNESDAY AS WELL...DEPENDING ON IF THAT COLD FRONT COMES
THROUGH OR NOT. LAST NOTE WOULD BE POTENTIAL FOR VALLEY FOG TUESDAY
MORNING...BUT TOO EARLY TO PUT THAT IN THE FORECAST AT THIS TIME
GIVEN HOW SENSITIVE VALLEY FOG CAN BE TO OTHER VARIABLES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1138 PM CDT WED AUG 28 2013
BAND OF MID LEVEL CLOUDS IS MOVING OFF TO THE EAST OF THE TAF
SITES...BUT SOME SCATTERED CLOUDS STILL REMAIN BACK ACROSS
SOUTHERN MINNESOTA INTO SOUTH DAKOTA. BOTH THE 29.00Z NAM AND
29.02Z RAP SOUNDINGS SHOW THIS MOISTURE LEVEL REMAINING THROUGH
THE NIGHT WHICH SHOULD HELP TO KEEP SOME CLOUDS FLOATING OVER.
THIS WILL HINDER THE FOG DEVELOPMENT SOME AS WILL THE LIGHT
SOUTHEAST WINDS THAT WILL PERSIST THROUGH THE NIGHT AS THE WEAK
SURFACE HIGH HAS BECOME CENTERED OVER EASTERN WISCONSIN AND LAKE
MICHIGAN. STILL EXPECT TO SEE SOME FOG FORM...BUT WITH THE IN AND
OUT CLOUDS AND LIGHT WINDS...WILL HOLD THE VISIBILITY RESTRICTION
TO MVFR. THIS FOG SHOULD BURN OFF RAPIDLY THURSDAY MORNING WITH
SOME DIURNAL CUMULUS FORMING IN THE LATE MORNING AND THEN
DISSIPATING IN THE EVENING. AS A SHORT WAVE TROUGH PASSES BY TO
THE NORTH...THE MID LEVEL CAP WILL REMAIN IN PLACE AND KEEP ANY
CONVECTION WELL TO THE NORTH.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1138 PM CDT WED AUG 28 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 321 PM CDT WED AUG 28 2013
THE MAIN FOCUS TONIGHT INTO TOMORROW IS WITH THE CHANCES OF
PRECIPITATION AND WHETHER ANY FOG WILL DEVELOP OVERNIGHT AGAIN.
THE UPPER LEVEL FLOW CONTINUES TO BE SHAPED BY BROAD RIDGING THAT
IS CENTERED OVER THE PLAINS AND EXTENDS FROM THE SOUTHEASTERN US
TO THE SOUTHWESTERN US. ANY PRECIPITATION HAS COME ALONG THE NORTHERN
PERIPHERY OF THIS RIDGE AS MID LEVEL SHORT WAVE TROUGHS TRACK
ALONG THE RIM. THERE CURRENTLY ARE A PAIR OF SHORT WAVE TROUGHS
THAT WILL NEED MONITORING INTO TOMORROW...ONE WEAK ONE IN THE
DAKOTAS/WESTERN MINNESOTA AND ANOTHER RUNNING INTO MONTANA. AT THE
SURFACE...A COLD FRONT HAS STALLED OUT ACROSS CENTRAL IOWA WITH
RIDGING ACROSS THE NORTHERN GREAT LAKES. DEW POINTS HAVE REALLY
POOLED ALONG THE NORTHERN SIDE OF THIS FRONT WITH MID/UPPER 70S
ANALYZED FROM CENTRAL ILLINOIS THROUGH EASTERN/NORTHERN IOWA.
EARLIER STRATUS HAS ALSO BECOME MORE MIXED AS THE DAY HAS GONE ON
TODAY...WHICH HAS LEAD TO SOME QUICK WARM UPS AS WELL.
GOING INTO TONIGHT...THE FIRST SHORTWAVE IN THE DAKOTAS/MINNESOTA
WILL PROPAGATE TO THE EAST AND WILL HELP TO LIFT THE FRONT BACK TO
THE NORTH AS A WARM FRONT ACROSS SOUTHERN MINNESOTA. THE 18.12Z
NAM/GFS AND 18.18Z RAP SHOWS THE POOL OF HIGHEST 0-3KM MUCAPE
LIFTING NORTH AS WELL IN MINNESOTA AND BECOMING ORIENTED MORE
NORTH TO SOUTH FROM CENTRAL MINNESOTA TO EASTERN IOWA OVERNIGHT.
THE BEST LOW LEVEL MOISTURE TRANSPORT APPEARS TO BE IN CENTRAL
MINNESOTA AS WELL WHERE THE STRONGER PUSH/CONVERGENCE IS FROM THE
SOUTH. HAVE KEPT SOME LOW CHANCES OF SHOWERS/STORMS OVERNIGHT IN
PORTIONS OF SOUTHEAST MINNESOTA/NORTHEAST IOWA TO ACCOUNT FOR
THIS...BUT CONFIDENCE IS NOT OVERLY HIGH THAT THE FORCING WILL BE
ENOUGH TO PRODUCE SOME CONVECTION.
THE HIGHER CHANCES FOR PRECIPITATION WILL COME ON THURSDAY AS THE
SECOND MID LEVEL SHORT WAVE TROUGH PROPAGATES EAST FROM MONTANA
THROUGH THE DAKOTAS ON TOWARD THE UPPER GREAT LAKES. IT APPEARS
THAT AN MCS WILL DEVELOP OVER THE DAKOTAS FROM THIS FEATURE AND
TRACK TO THE EAST INTO MINNESOTA TOMORROW MORNING. AS THE
SHORTWAVE ENTERS MINNESOTA/NORTHERN WISCONSIN LATE TOMORROW
MORNING/AFTERNOON...CONVECTION MAY DEVELOP ALONG THE WARM FRONT
WHICH WILL BE LIFTING TO THE NORTH AS A LOW MOVES INTO CENTRAL
MINNESOTA. WITH THE HIGH INSTABILITY ON THE ORDER OF 2000-4000
J/KG AND DECENT SHEAR...CAN NOT RULE OUT SOME SEVERE WEATHER
ACROSS NORTHERN WISCONSIN THE AFTERNOON HOURS WITH LARGE
HAIL/DAMAGING WINDS THE MAIN THREATS. NORTHERN WISCONSIN IS ALSO
THE LOCATION OF THE HIGHEST PRECIPITATION CHANCES AS THIS TROUGH
MOVES THROUGH GOING INTO THURSDAY NIGHT.
WITH LIGHT WINDS AND HIGH AMOUNTS OF LOW LEVEL MOISTURE STILL IN
THE REGION...CAN NOT RULE OUT SOME FOG TONIGHT...PARTICULARLY IN
WESTERN WISCONSIN WHICH WILL BE CLOSER TO THE HIGH AND FURTHER
FROM ANY CLOUD COVER.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 321 PM CDT WED AUG 28 2013
THE COMPLEX WILL MOVE THROUGH ON THURSDAY NIGHT WITH A COLD FRONT
DROPPING DOWN ACROSS THE REGION ON FRIDAY. THE 28.12Z NAM/GFS
FORECAST SOUNDINGS DIFFER ON THE AMOUNT OF CAPPING THAT WILL BE IN
PLACE AHEAD OF THIS FRONT WITH THE NAM SHOWING MORE OF IT AND THE
GFS LESS. THUS...THE NAM IS MAINLY DRY WITH THE FROPA WHILE THE
GFS PRODUCES SOME QPF. KEPT SOME PRECIPITATION CHANCES IN THERE
FOR NOW...MAINLY IN WESTERN WISCONSIN.
TEMPERATURES WARM UP AHEAD OF THIS FRONT WITH HIGHS GOING BACK
INTO THE 90S ACROSS MUCH OF NORTHEAST IOWA AND FAR SOUTHWEST
WISCONSIN. WITH HEAT INDICES AROUND 100F IN THE AFTERNOON...MAY
HAVE TO DO A HEAT ADVISORY FOR THIS REGION.
BEYOND THIS...A BIG PATTERN CHANGE IS ON THE WAY FOR SUNDAY AS A
MID LEVEL TROUGH DIGS DOWN FROM CANADA AND BRINGS A MUCH COOLER
AIR MASS DOWN INTO THE REGION. 850MB TEMPERATURES...WHICH
GENERALLY HAVE BEEN IN THE +15C TO +25C RANGE THE PAST WEEK...WILL
DROP TO ABOUT +7C SUNDAY NIGHT AFTER THE COLD FRONT SWINGS
THROUGH. WHILE STORMS LOOK POSSIBLE WITH THE COLD FRONT COMING
THROUGH...THE TIME OF THE DAY DOES NOT LOOK FAVORABLE FOR SEEING
SEVERE WEATHER AS THE FRONT WILL LIKELY COME THROUGH IN THE
MORNING BEFORE ANY HIGH INSTABILITY CAN BUILD. HIGH PRESSURE THEN
SETTLES IN FOR THE EARLY PART OF NEXT WEEK WITH MUCH COOLER AND
SEASONABLE TEMPERATURES ON TAP.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1138 PM CDT WED AUG 28 2013
BAND OF MID LEVEL CLOUDS IS MOVING OFF TO THE EAST OF THE TAF
SITES...BUT SOME SCATTERED CLOUDS STILL REMAIN BACK ACROSS
SOUTHERN MINNESOTA INTO SOUTH DAKOTA. BOTH THE 29.00Z NAM AND
29.02Z RAP SOUNDINGS SHOW THIS MOISTURE LEVEL REMAINING THROUGH
THE NIGHT WHICH SHOULD HELP TO KEEP SOME CLOUDS FLOATING OVER.
THIS WILL HINDER THE FOG DEVELOPMENT SOME AS WILL THE LIGHT
SOUTHEAST WINDS THAT WILL PERSIST THROUGH THE NIGHT AS THE WEAK
SURFACE HIGH HAS BECOME CENTERED OVER EASTERN WISCONSIN AND LAKE
MICHIGAN. STILL EXPECT TO SEE SOME FOG FORM...BUT WITH THE IN AND
OUT CLOUDS AND LIGHT WINDS...WILL HOLD THE VISIBILITY RESTRICTION
TO MVFR. THIS FOG SHOULD BURN OFF RAPIDLY THURSDAY MORNING WITH
SOME DIURNAL CUMULUS FORMING IN THE LATE MORNING AND THEN
DISSIPATING IN THE EVENING. AS A SHORT WAVE TROUGH PASSES BY TO
THE NORTH...THE MID LEVEL CAP WILL REMAIN IN PLACE AND KEEP ANY
CONVECTION WELL TO THE NORTH.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...04
AREA FORECAST DISCUSSION
NWS ALBANY NY
432 AM EDT SAT AUG 31 2013
.SYNOPSIS...
A WARM AND HUMID AIR MASS WILL IMPACT EASTERN NEW YORK
AND WESTERN NEW ENGLAND THROUGH THE HOLIDAY WEEKEND. A SERIES OF
WEAK DISTURBANCES MOVING ALONG A FRONTAL BOUNDARY NEAR THE SAINT
LAWRENCE RIVER VALLEY WILL PRODUCE SHOWERS AND THUNDERSTORMS TODAY
WITH SOME LOCALLY HEAVY RAINFALL. THE UNSETTLED WEATHER CONTINUES
LATE SUNDAY INTO LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE
WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TO THE REGION.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 432 AM EDT...THE LAST FULL DAY OF METEOROLOGICAL SUMMER
BEGAN WITH SHOWERS AND SCT THUNDERSTORMS ACROSS PORTIONS OF THE
ALY FCST AREA...ESPECIALLY FROM THE NRN CATSKILLS...CAPITAL REGION
AND SRN VT NORTHWARD. A COUPLE OF WEAK SFC LOWS ARE MOVING ALONG A
STATIONARY FRONT NEAR THE ST LAWRENCE RIVER VALLEY THIS MORNING.
LOW-LEVEL CONVERGENCE WITH THE SFC LOWS HAS HELPED THE SHOWERS AND
THUNDERSTORMS BE THE MOST PERSISTENT IN THE MOHAWK RIVER
VALLEY...SRN DACKS...AND THE LAKE GEORGE SARATOGA REGION. THIS
ACTIVITY WILL CONTINUE TOWARDS SUNRISE...AND A BRIEF LOW WILL
OCCUR TOWARDS NOONTIME.
A MAJORITY OF THE GUIDANCE SHOWS ANOTHER WEAK RIPPLE OF LOW
PRESSURE MOVING ALONG THE BOUNDARY IN THE AFTERNOON WITH A MID
LEVEL SHORT-WAVE IN THE W/SW FLOW ALOFT. IT IS QUESTIONABLE IF ANY
SIGNIFICANT HEATING WILL OCCUR EXCEPT PERHAPS ALONG THE SRN TIER
OF THE FCST AREA /MID HUDSON VALLEY AND NW CT/. THE 0-6 KM DEEP
SHEAR IS WEAK WITH WEAK MID LEVEL LAPSE RATES ALOFT...SO
WIDESPREAD SEVERE CONVECTION IS NOT ANTICIPATED DESPITE SBCAPE
VALUES OF 1000-2000 J/KG ACCORDING THE NAM/GFS. H850 THETA-E
VALUES WILL BE GENERALLY IN THE 335-340K RANGE. THE PWATS WILL BE
IN THE 1.25-1.75 INCH RANGE /1 TO 2 STANDARD DEVIATIONS ABOVE
NORMAL/...SO LOCALLY HVY RAINFALL WILL BE THE MAIN ISSUE. THE
ENHANCED WORDING WAS PUT IN THE GRIDS...AND WILL BE MENTIONED IN
THE HWO. IF THE HIGHER CAPE VALUES ARE REALIZED...AN ISOLATED WET
MICROBURST MAY BE POSSIBLE. THE MAIN THREAT CONTINUES TO BE HEAVY
RAINFALL. THE HIGHEST POPS IN THE LIKELY RANGE WERE USED ACROSS
THE NRN HALF OF THE FCST AREA.
THE LATEST 3KM HRRR COLUMN REF PRODUCT SHOWS DISCRETE CONVECTIVE
ELEMENTS FORMING INTO A LINE OVER THE HUDSON RIVER VALLEY IN THE
MID AFTERNOON. IN A WEAK SHEAR ENVIRONMENT THIS APPEARS TO BE OFF
SOME...BUT WILL HAVE TO BE MONITORED.
THE SFC DEWPTS WILL REMAIN IN THE 60S WITH PERHAPS SOME SPOTTY
LOWER 70S OVER THE SRN TIER. THE AIR MASS WILL BE STICKY FOR THE
LAST DAY OF AUGUST. MINIMAL HEATING SHOULD ALLOW FOR U70S TO L80S
IN THE VALLEYS...WITH 70S OVER THE HILLS AND MTNS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
TONIGHT...THE SHOWERS AND THUNDERSTORMS SHOULD DIMINISH IN THE
EARLY EVENING WITH THE WEAK SFC WAVE MOVING EAST/NORTHEAST OF THE
REGION...AND THE MID LEVEL SHORT-WAVE PASSING DOWNSTREAM. THE
FRONTAL BOUNDARY MAY MOVE OVER THE NRN HALF OF THE FCST AREA AND
FALL APART. THE POPS WERE LOWERED TO SLIGHT CHC VALUES AFTER
MIDNIGHT. IT WILL REMAIN VERY HUMID WITH LOWS IN THE MID AND U60S
OVER MOST OF THE REGION...EXCEPT OVER THE MTNS.
SUNDAY...THE ENTIRE DAY SHOULD NOT BE A WASHOUT WITH AN AMPLIFYING
UPPER LEVEL TROUGH OVER ONTARIO AND THE GREAT LAKES REGION. THE
MID LEVEL FLOW WILL BECOME SOUTHWESTERLY OVER NY AND NEW ENGLAND
WITH WEAK RIDGING ALOFT. THEIR ARE NOT ANY REAL ROBUST SYNOPTIC
TRIGGER MECHANISMS DURING THE DAY. AIR MASS OR DIFFERENTIAL
HEATING THUNDERSTORMS ARE POSSIBLE. A SLIGHT TO LOW CHANCE OF
SHOWERS AND THUNDERSTORMS WAS INCLUDED IN THE GRIDS. H850 TEMPS
INCREASE TO +16C TO +17C WITH PARTLY SUNNY CONDITIONS. MAX TEMPS
WILL RUN ABOUT 5-10 DEGREES ABOVE NORMAL TO OPEN SEPT.
SUNDAY NIGHT INTO LABOR DAY...A LARGE TROUGH OF LOW PRESSURE
IMPACTS THE REGION. SEVERAL MID LEVEL SHORT-WAVES ROTATING AROUND
THE CLOSED LOW SOUTH OF JAMES BAY WILL YIELD UNSETTLED WX DURING
THIS TIME FRAME. IT IS DIFFICULT TO DETERMINE IF ANY ROBUST SFC
HEATING WILL OCCUR AT THIS TIME. THE STRONG SYNOPTIC LIFT WITH THE
TROUGH WILL LIKELY YIELD PERIODS OF SHOWERS AND SCT THUNDERSTORMS.
SOME HVY RAINFALL LOOKS LIKE A GOOD BET. THE QG LIFT INCREASES
LABOR DAY AFTERNOON...AS THE NRN HALF OF THE FCST AREA GETS NEAR
THE RIGHT ENTRANCE REGION OF A H250 JET STREAK WITH STRONG UPPER
LEVEL DIVERGENCE ALOFT. PWATS CONTINUE ABOVE NORMAL FOR EARLY
SEPT. LIKELY POPS WERE CONTINUED ON MONDAY. THE COOLER NAM MOS
TEMPS WERE ALSO FOLLOWED CLOSELY WITH THE AMOUNT OF CLOUD COVER
AND NUMEROUS SHOWERS EXPECTED. MAX TEMPS WILL BE HARD PRESSED TO
GET OUT OF THE 70S WITH PERHAPS SOME 80F READINGS FROM THE CAPITAL
REGION SOUTH IN THE MID HUDSON VALLEY.
MONDAY NIGHT...LOW AND MID LEVEL HEIGHT CONTINUE TO FALL...AS THE
TROUGH OF LOW PRESSURE AND ITS ASSOCIATED COLD FRONT MIGRATE EAST
OF THE REGION. A CHC OF SHOWERS WAS KEPT IN MOST OF THE OVERNIGHT.
LOW LEVEL COLD ADVECTION IS EXPECTED WITH TEMPS FALLING INTO THE
50S OVER THE MTNS WITH LOWER TO MID 60S IN THE VALLEYS.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
COOLER AND LESS ACTIVITY WEATHER AS WE HEAD THROUGH THE FIRST WEEK
OF SEPTEMBER.
THE MODEL GUIDANCE IS IN FAIRLY GOOD AGREEMENT REGARDING THE
LONGWAVE PATTERN WITH THE NORTHEAST REMAINING UNDER A TROUGH AND
THE RIDGE HOLDING ON OVER THE PLAIN STATES.
A COUPLE OF COLD FRONTS WILL MOVE ACROSS THE REGION. THE FIRST ONE
IS EXPECTED TO MOVE OFF TO OUR EAST ON TUESDAY WITH SOME LINGERING
SHOWERS POSSIBLE MAINLY DURING THE MORNING. A PLEASANT DAY EXPECTED
WEDNESDAY AS HIGHER PRESSURE BUILDS IN WITH SEASONABLE WARM
TEMPERATURES. A SECONDARY COLD FRONT IS EXPECTED TO MOVE THROUGH
THURSDAY WITH ISOLATED SHOWERS. A MORE AUTUMN-LIKE AIRMASS WILL BE
USHERED IN AS CANADIAN HIGH PRESSURE BUILDS IN ITS WAKE OF THE FRONT
TO CLOSE OUT THE WEEK. TEMPERATURES THURSDAY AND FRIDAY ARE
ANTICIPATED TO RUN ABOUT 5 DEGREES BELOW NORMAL.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
SHOWERS AND ISOLATED THUNDERSTORMS CONTINUE TO MOVE EASTERLY ACROSS
THE FORECAST AREA EARLY THIS MORNING IN ASSOCIATION WITH AN
APPROACHING SHORT WAVE TROUGH AND WEAK SURFACE LOW MOVING INTO THE
SAINT LAWRENCE RIVER VALLEY. EXPECTING A LULL IS THE PRECIPITATION
FOR A BIT THIS MORNING MAINLY AFTER SUNRISE AS THE SHORT WAVE TROUGH
MOVES OFF TO THE EAST. HOWEVER...CHANCES FOR CONVECTION WILL
INCREASE LATER THIS MORNING AND ESPECIALLY DURING THE AFTERNOON
HOURS AS THE SURFACE LOW PASSES TO OUR NORTH AND ANOTHER SHORT WAVE
TROUGH APPROACHES. WITH THE HELP OF DAYTIME HEATING AND INCREASED
INSTABILITY THERE WILL BETTER AND WIDESPREAD CHANCES FOR
THUNDERSTORMS SO HAVE INCLUDED MENTION IN THE TAFS.
EXPECTING SOME MVFR FOG AND CIGS EARLY THIS MORNING WITH CONDITIONS
IMPROVING AFTER SUNRISE. EXPECTING MAINLY VFR CONDITIONS DURING THE
DAY WITH MVFR/BRIEF IFR CONDITIONS WITH ANY CONVECTION THAT IMPACTS
TAF SITES. MVFR FIG IS EXPECTED TO DEVELOP AGAIN THIS EVENING
ESPECIALLY WHERE IT RAINS.
OUTLOOK...
SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
LABOR DAY: HIGH OPERATIONAL IMPACT. LIKELY SHRA...TSRA.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
TUESDAY: LOW OPERATIONAL IMPACT. CHANCE OF SHRA.
TUESDAY NIGHT-WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.FIRE WEATHER...
NO FIRE WEATHER PROBLEMS ARE EXPECTED IN THE HUMID AIR MASS WITH
SEVERAL CHANCES OF RAINFALL.
A SERIES OF WEAK DISTURBANCES MOVING ALONG A FRONTAL BOUNDARY
NEAR THE SAINT LAWRENCE RIVER VALLEY WILL PRODUCE SHOWERS AND
THUNDERSTORMS TODAY WITH SOME LOCALLY HEAVY RAINFALL. THE
UNSETTLED WEATHER CONTINUES LATE SUNDAY INTO LABOR DAY WHEN A
STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND
SCATTERED THUNDERSTORMS TO THE REGION.
THE RH VALUES WILL ONLY DROP TO BETWEEN 50 AND 85 PERCENT THIS
AFTERNOON...AND RECOVER TO CLOSE TO 100 PERCENT SUNDAY MORNING.
HIGH RH VALUES OF 55 TO 75 PERCENT WILL OCCUR SUNDAY AFTERNOON.
THE WINDS WILL BE FROM THE SOUTH TO SOUTHWEST AT 5 TO 15 MPH TODAY
AND TOMORROW... AND BECOME LIGHT TO CALM TONIGHT.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON
THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE
POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS.
THE BEST CHANCE FOR WIDESPREAD RAINFALL WILL BE TODAY AND ON
LABOR DAY.
HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE
EXPECTED WITH THUNDERSTORMS. ISOLATED URBAN...SMALL STREAM...AND
POOR DRAINAGE FLOODING WILL BE POSSIBLE DURING THE HOLIDAY
WEEKEND. SOME WITHIN BANK RISES ARE POSSIBLE ON LARGER STREAMS
WHERE SHOWERS AND STORMS OCCUR. ZONAL FFG VALUES REMAIN HIGH
DURING THIS TIME FRAME. HOWEVER...A QUICK INCH OR TWO OF RAINFALL
FROM A SLOW MOVING THUNDERSTORM MAY PRODUCE AN ISOLATED FLASH
FLOOD DURING THE HOLIDAY WEEKEND.
RAINFALL AMOUNTS WILL BE QUITE VARIABLE DUE TO THE SHOWERY NATURE
OF THE RAIN...WITH SOME LOCATIONS RECEIVING OVER AN INCH OF RAIN
WHILE OTHERS REMAIN DRY. SOME AREAS NORTH OF THE CAPITAL REGION
HAVE RECEIVED A HALF AN INCH TO AN INCH OF RAINFALL THIS MORNING.
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...WASULA
NEAR TERM...WASULA
SHORT TERM...WASULA
LONG TERM...IAA
AVIATION...IAA
FIRE WEATHER...WASULA
HYDROLOGY...SND/WASULA
AREA FORECAST DISCUSSION
NWS TAUNTON MA
414 AM EDT SAT AUG 31 2013
.SYNOPSIS...
A STALLED FRONTAL BOUNDARY STRETCHING FROM NEW YORK STATE INTO NEW
ENGLAND WILL RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS AT TIMES
SATURDAY AND SUNDAY. SHOWERS AND THUNDERSTORMS MAY BECOME MORE
WIDESPREAD MONDAY INTO EARLY TUESDAY AS A COLD FRONT MOVES ACROSS
THE REGION. DRIER...COOLER AND MUCH LESS HUMID WEATHER ARRIVES
MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SHORT WAVE TROUGH OVER THE EASTERN GREAT LAKES AND NY STATE EARLY
THIS MORNING DEAMPLIFIES AS IT APPROACHES AND MOVES ACROSS NEW
ENGLAND TODAY. THIS IS EVIDENT IN WEAKENING WIND FIELDS
ALOFT...LESS CURVATURE IN THE MID LEVEL FLOW/STREAMLINES AND
WEAKENING Q-VECTOR CONVERGENCE ALONG AND AHEAD OF THE MID LEVEL
TROUGH. LAST FEW RUNS OF THE HRRR OFFER THE SAME THEME WITH
WEAKENING REFLECTIVITY AS CONVECTION APPROACHES NEW ENGLAND.
THEREFORE EXPECTING UPSTREAM CONVECTION ACROSS NY STATE AND VT TO
SLOWLY WEAKEN AS IT APPROACHES AND ENTERS SOUTHERN NEW ENGLAND.
HOWEVER THINK NEW CONVECTION WILL REFIRE OVER THE AREA THIS
AFTERNOON AS SOME SUNSHINE TODAY DESTABILIZES THE ATMOSPHERE WITH
THE MORE CONSERVATIVE ECMWF AND GEFS OFFERING CAPES ON THE ORDER OF
1200-1800J/KG. FAIRLY CONFIDENT IN THIS SCENARIO AS ALL MOS GUIDANCE
HAVE HIGH TEMPS TODAY IN THE LOW TO MID 80S...WITH WARMEST
READINGS ACROSS NORTHEAST MA AND SOUTHEAST NH. THIS INSTABILITY
COMBINED WITH WEAK BUT MOIST CYCLONIC FLOW ALOFT SHOULD BE
SUFFICIENT TO YIELD SCATTERED THUNDERSTORMS. HIGHEST PROBABILITY
WILL BE ACROSS THE INTERIOR...CLOSER TO FRONTAL BOUNDARY AND
SURFACE CONVERGENCE. THUS CONVECTION SHOULD BE LESS NUMEROUS ACROSS
SOUTHEAST MA /INCLUDING CAPE COD AND THE ISLANDS/ AND POSSIBLY INTO
BOSTON-PROVIDENCE CORRIDOR. MAIN ISSUE WITH ANY TSTMS TODAY WILL BE
HEAVY DOWNPOURS/FLOOD POTENTIAL WITH PWATS JUST UNDER 2 INCHES ALONG
WITH WEAK WINDS ALOFT RESULTING IN SLOW MOVING STORMS. TIMING OF
STORMS WILL BE AFTER 16Z AND SPECIFICALLY DURING PEAK HEATING FROM
18Z-21Z.
IT WILL BE WARM AND HUMID TODAY AS SOUTHERN NEW ENGLAND WILL BE IN
THE WARM SECTOR OF THE APPROACHING FRONTAL SYSTEM. DEW PTS WILL
CLIMB INTO THE U60S AND L70S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
TONIGHT...
EARLY EVENING SHOWERS/TSTMS ACROSS THE INTERIOR SHOULD DISSIPATE
WITHIN A FEW HOURS OF SUNSET GIVEN THE LACK OF DEEP LAYER SHEAR
AND MID LEVEL LAPSE RATES NEEDED TO SUSTAIN NOCTURNAL CONVECTION.
HOWEVER CAN/T RULE OUT ISOLATED OR WIDELY SCATTERED SHOWERS
OVERNIGHT GIVEN THE WEAK BUT MOIST CYCLONIC FLOW ALOFT.
SOUTHERN NEW ENGLAND REMAINS IN THE WARM SECTOR SO EXPECT PATCHY FOG
AND LOW CLOUDS. HIGH DEW PTS WILL YIELD ANOTHER MILD TO WARM NIGHT.
SUNDAY...
WEAK SHORT WAVE RIDGING MAY MOVE ACROSS THE REGION BEHIND
DEPARTING SHORT WAVE TROUGH OF TODAY AND BEFORE NEXT TROUGH
APPROACHES SUN NGT AND MON. THIS IS EVIDENT ON MODEL CROSS AND
TIME SECTIONS WITH COLUMN DRYING OUT IN THE MID AND UPPER LEVELS.
SO WHILE THERE IS STILL SOME UNCERTAINTY TO SUNDAY/S
FORECAST...THERE IS INCREASING CONFIDENCE THAT ANY SHOWER/TSTM
ACTIVITY WILL NOT BE WIDESPREAD. THUS NOT EXPECTING A WASHOUT
SUNDAY.
THE AREA REMAINS IN THE WARM SECTOR SO ANOTHER WARM AND MUGGY DAY
WITH HIGHS 80-85 AWAY FROM THE COAST ALONG WITH DEW PTS IN THE U60S
AND L70S.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
HIGHLIGHTS...
* SHOWERS AND THUNDERSTORMS LIKELY ON MONDAY AND INTO TUESDAY
* SLOW MOVING COLD FRONT WILL CROSS THE REGION ON TUESDAY
* FALL LIKE CONDITIONS FOR THE SECOND HALF OF THE WORK WEEK
CONFIDENCE LEVEL/MODEL GUIDANCE...
MODERATE CONFIDENCE IN OVERALL FORECAST. CONTINUE TO HAVE
INCREASING CONFIDENCE FOR THE TEMPERATURE ASPECT IN THE FORECAST.
MODERATE CONFIDENCE IN TIMING OF PRECIPITATION WITH HIGH
CONFIDENCE THAT PRECIP WILL OCCUR MONDAY AND EARLY TUESDAY. THE
00Z MODELS MAINTAIN A NEARLY STEADY-STATE TO SLIGHTLY RETROGRADING
PATTERN IN THE LOWER HALF OF THE CONUS WITH AN UPPER HIGH OVER THE
CENTRAL/SOUTHERN PLAINS. WHILE ACROSS THE NORTHEAST A PROGRESSIVE
FLOW INFLUENCED BY MULTIPLE SHORTWAVES AND FRONTAL PASSAGES WILL
RESULT IN GENERALLY COOLER TEMPERATURES. HOWEVER THE
DETAILS/TIMINGS ARE AN ISSUE DUE TO THE PATTERNS SHORT WAVELENGTH
AND POSSIBILITY OF PHASING. THAT BEING SAID FELT PERSISENT WAS A
GOOD WAY TO GO FOR THIS MORNINGS FORECAST. BLENDED PREVIOUS
FORECAST WITH WPC AND THE ENSEMBLES.
DETAILS...
MONDAY...
LONG WAVE TROUGH WILL SHARPEN UP ON MONDAY AS HUDSON BAY LOW
PRESSURE STRENGTHENS. THIS WILL KEEP THE REGION IN A SOUTHWEST
FLOW WITH INCREASING MOISTURE CAUSING VERY MUGGY CONDITIONS. MAIN
FOCUS IS A COLD FRONT ACROSS THE GREAT LAKES THAT WILL APPROACH
THE REGION. HOWEVER A SHORTWAVE WILL MOVE THROUGH THE FLOW ON
MONDAY WHICH WILL SPARK SOME SHOWERS AND THUNDERSTORMS. THE REGION
WILL BE IN THE WARM...MOIST SECTOR AS WELL AS THE BETTER JET
DYNAMICS. MAIN THREAT WITH THESE STORMS WILL BE HEAVY RAIN AS PWAT
VALUES WILL BE ABOVE 2 INCHES. THESE STORMS WILL BE SLOW MOVING
AND/OR TRAINING AS CORFIDI VECTORS ARE AROUND 0-5 KTS. NOTICED SPC
PUT THE REGION IN A SEE TEXT FOR DAY THREE OUTLOOK. HAVE LOW
CONFIDENCE IN OVERALL SEVERE WEATHER AS INSTABILITY VALUES WILL BE
LOWER THAN MODELS SUGGEST DUE TO THE AMOUNT OF CLOUDS ACROSS THE
AREA. THIS IDEA IS ALSO SUPPORTED BY THE ENSEMBLES. THEREFORE
BELIEVE THAT THE MAIN THREAT WILL STILL BE HEAVY RAIN CAUSING SOME
URBAN AND POOR DRAINAGE FLOODING. SMALL STREAMS MAY ALSO BE IN A
THREAT IF THUNDERSTORMS TRAIN OVER A CERTAIN REGION. THIS PORTION
OF THE FORECAST WILL NEED TO BE WATCHED CLOSELY OVER THE WEEKEND.
TUESDAY...
COLD FRONT WILL MOVE THROUGH SOUTHERN NEW ENGLAND ON TUESDAY.
MAIN QUESTION IS THE TIMING. IF THE FRONT SLOWS DOWN THEN THERE IS
A CHANCE FOR SHOWERS AND THUNDERSTORMS TO DEVELOP ESP ACROSS THE
EASTERN HALF OF THE REGION. IF THE FRONT SPEEDS UP THEN ONLY A FEW
SHOWERS MAY OCCUR AS THE FRONT EXITS OFFSHORE. REGARDLESS HAVE A
LOWER CONFIDENCE ON ANY STRONG STORMS ON TUESDAY AS BETTER JET
DYNAMICS WILL BE OFFSHORE. BOTH THE ENSEMBLES INDICATE THE BETTER
MOISTURE IS OFFSHORE AS WELL. TRENDED TOWARDS A FASTER SOLUTION ON
TUESDAY. A FEW HEAVY SHOWERS ARE STILL POSSIBLE WITH MAIN CONCERN
BEING NUISANCE FLOODING.
WEDNESDAY THROUGH FRIDAY...
LARGE-SCALE SUBSTANCES WILL FILTER IN BEHIND THE FRONT ON
WEDNESDAY. THIS WILL DROP DEWPOINTS DOWN INTO THE 40/50S MAKING IT
VERY COMFORTABLE. A FEW SHOWERS ARE POSSIBLE ACROSS THE NW ZONES
FROM WRAP AROUND MOISTURE FROM THE LOW. OTHERWISE EXPECT MOSTLY
DRY CONDITIONS. MODELS ARE INDICATING A POLAR FRONT WILL MOVE
THROUGH ON THURSDAY BRINGING SOME ISOLATED/SCATTERED SHOWERS. HAVE
A LOWER CONFIDENCE AS THERE IS A GOOD AMOUNT OF DRY AIR ACROSS THE
AREA. BEHIND THIS FRONT IS A MORE FALL LIKE AIRMASS BRINGING
OVERNIGHT LOWS IN THE 40S AND HIGHS ONLY IN THE 60S.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW...LOW TO MODERATE CONFIDENCE ON EXACT DETAILS INCLUDING
TIMING...BUT HIGHER CONFIDENCE ON OVERALL FORECAST THEME. CIGS AND
VSBYS WERE DERIVED FROM A BLEND OF NAM AND GFS MOS.
TODAY...
IFR CIGS SHOULD BE CONFINED TO SOUTHEAST MA AND RI. THIS SHOULD
IMPROVE TO VFR 14Z-16Z. SHOWERS AND TSTMS ENTERING WESTERN NEW
ENGLAND AT 2 AM IS EXPECTED TO WEAKEN AS IT TRAVERSES EASTWARD.
ADDITIONAL SHOWERS AND TSTMS WILL DEVELOP AFTER 16Z MAINLY INLAND
WITH DAYTIME HEATING COMMENCING. LESS SHOWER/TSTM ACTIVITY ACROSS
SOUTHEAST MA/CAPE COD AND ISLANDS.
TONIGHT...
ALMOST A REPEAT PERFORMANCE...IFR IN LOW CLOUDS CONFINED TO
SOUTHEAST MA AND RI WITH MVFR/VFR ELSEWHERE. ISOLATED/SCATTERED
SHOWERS SHOULD BE MOST NUMEROUS WELL INLAND.
SUNDAY...
IFR SOUTHEAST MA AND RHODE ISLAND BUT IMPROVING TOWARD MIDDAY TO
VFR. VFR ELSEWHERE. NOT EXPECTING WIDESPREAD SHOWERS/TSTMS...MORE
ISOLATED TO WIDELY SCATTERED.
KBOS TERMINAL...IFR CIGS ACROSS SOUTHEAST MA MAY CLIP LOGAN 09Z-
13Z BUT BULK OF LOW CLOUDS SHOULD SLIDE SOUTH OF THE AIRPORT. MOST
SHOWER ACTIVITY SHOULD BE WEST AND NORTH OF BOSTON.
KBDL TERMINAL...SHOWERS/TSTMS WILL BECOME MORE NUMEROUS 16Z-22Z.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...
SUNDAY NIGHT...MODERATE CONFIDENCE. EXPECT MAINLY MVFR CIGS/VFR
VSBYS. AREAS MVFR VSBYS IN ANY SHOWERS/TSTMS. LOCAL IFR VSBYS IN
ANY HEAVIER RAINFALL.
MONDAY-TUESDAY...LOW CONFIDENCE MAINLY FOR TIMING. MVFR
CONDITIONS WITH IFR IN SHOWERS/TSTMS. PERIODS OF HEAVY RAINFALL
WILL REDUCE VSBYS AS WELL.
WEDNESDAY...HIGH CONFIDENCE. MVFR TO START...IMPROVING TO VFR BY
THE AFTERNOON HOURS.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
TODAY THROUGH SUNDAY...
MODEST SW WIND 10-15 KT WITH LOW RISK OF 20 KT GUST. WARM/MUGGY
AIRMASS WILL YIELD LATE NIGHT/EARLY MORNING FOG. SHOWERS/TSTMS WILL
BE MAINLY INLAND. FORECAST CONFIDENCE MODERATE TO HIGH.
OUTLOOK...MONDAY THROUGH WEDNESDAY...
PERSISTENT SOUTHERLY SWELL COMBINED WITH AN APPROACHING COLD
FRONT WILL CAUSE SEAS TO BUILD UP TO 5 FT ESP ACROSS THE OUTER
WATERS THROUGH TUESDAY. BELIEVE THIS IS A LITTLE HIGH SO HAVE
UNDERCUT WAVE GUIDANCE TO TOP OUT AT 4FT. LOW PROB FOR GUSTS UP TO
25 KT AHEAD OF COLD FRONT MON NIGHT AND EARLY TUE. EXPECT COLD
FRONT TO MOVE ACROSS WATERS LATE TUE/TUE NIGHT. WINDS/SEAS SHOULD
SLOWLY DIMINISH DURING WED. BEST CHANCE FOR THUNDERSTORMS WILL BE
MONDAY INTO TUESDAY MORNING.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...NOCERA/DUNTEN
NEAR TERM...NOCERA
SHORT TERM...NOCERA
LONG TERM...DUNTEN
AVIATION...NOCERA/DUNTEN
MARINE...NOCERA/DUNTEN
AREA FORECAST DISCUSSION
NWS ALBANY NY
152 AM EDT SAT AUG 31 2013
.SYNOPSIS...
A SOUTHWEST FLOW OF WARM AND HUMID AIR...WILL COMBINE
WITH A WEAK LOW PRESSURE SYSTEM SLOWLY TRACKING EASTWARD THROUGH THE
SAINT LAWRENCE VALLEY TO PRODUCE ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS THIS MORNING THROUGH SUNDAY. A MUCH STRONGER SYSTEM
WILL BRING A THREAT FOR MORE NUMEROUS SHOWERS AND THUNDERSTORMS ON
LABOR DAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 137 AM EDT...THE NRN HALF OF THE FCST AREA CONTINUES TO HAVE
SCT-NUMEROUS SHOWERS AND SOME THUNDERSTORMS AHEAD OF A MID-LEVEL
SHORT-WAVE AND A SFC TROUGH ASSOCIATED WITH RIPPLES OF LOW PRESSURE
MOVING ALONG THE ST LAWRENCE RIVER VALLEY. A FEW STRONGER
THUNDERSTORMS HAVE MOVED ACROSS THE SARATOGA REGION WITH FQT LTG
BRIEF BURSTS OF HVY RAIN...AND POSSIBLY SOME SMALL HAIL.
THE LATEST RUC HAS SHOWALTER VALUES OF 0 TO -2C. THE ELEVATED
INSTABILITY WILL LINGER WITH A SLIGHT TO LOW CHC OF THUNDERSTORMS
THIS MORNING...ESPECIALLY NEAR THE LOW-LEVEL CONVERGENT BOUNDARY.
THERE IS LESS LTG UPSTREAM AND SOME OF THE SHOWERS ARE STARTING
MOVE SOUTH OF THE MOHAWK VALLEY. SLIGHT OR LOW CHC POPS WERE USED
HERE...BUT SOME LOCATIONS MAY REMAIN DRY SOUTH AND EAST OF THE
CAPITAL REGION.
MUGGY CONDITIONS WILL CONTINUE WILL DEWPTS IN THE 60S. OVERNIGHT
LOWS WILL BE ABOVE NORMAL IN THE 60S ACROSS THE FCST AREA.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/...
FOR SATURDAY...WEAK LOW PRESSURE AT THE SURFACE AND
ALOFT WILL REMAIN OVER AND NORTH OF THE AREA. WITH WARM AND HUMID
AIRMASS IN PLACE...ONLY A WEAK TRIGGER NEEDED TO START SHOWERS AND
STORMS. MODELS DON`T INDICATE ANY PARTICULAR FORCING FOR THE
SHOWERS/STORMS SO PARTLY SUNNY CONDITIONS WITH A CHANCE OF
AFTERNOON SHOWERS AND THUNDERSTORMS LOOKS GOOD. FOR
SUNDAY...STRONG IMPULSE HAS REACHED THE WESTERN GREAT LAKES. THIS
WORKS TO INDUCE WEAK RIDGING ACROSS THE ALBANY FORECAST AREA.
THIS WEAK RIDGING/HIGH PRESSURE SHOULD KEEP GENERALLY FAIR WEATHER
OVER THE AREA WITH AGAIN A CHANCE FOR SHOWERS AND THUNDERSTORMS...
MAINLY SUNDAY AFTERNOON. BY LATE SUNDAY NIGHT...AN UPPER LEVEL
TROUGH...ASSOCIATED WITH DEEP GREAT LAKES LOW MAY BRING AN
INCREASED THREAT OF SHOWERS AND STORMS.
MAX/MIN TEMPERATURES GENERALLY A MOS BLEND. AREAS OF FOG EXPECTED
EACH MORNING WITH STEAMY AIRMASS IN PLACE.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
THE LONG TERM PERIOD WILL COINCIDE WITH THE BEGINNING OF
METEOROLOGICAL FALL (WHICH STARTS RIGHT ON LABOR DAY). THIS
YEAR...ALMOST ON QUE...OUR WEATHER WILL BECOME MUCH MORE AUTUMNAL
FEELING. HAVE LEANED HEAVILY WITH THE 12Z EUROPEAN MODEL...WHICH IS
FAIRLY CLOSE TO THE HPC GUIDANCE.
ON LABOR DAY ITSELF...WE WILL REMAIN IN A FAIRLY HUMID AND WARM AIR
MASS. A PRE-FRONTAL TROUGH LOOKS TO BE THE INITIAL TRIGGER EARLY ON
LABOR DAY. THE ACTUAL COLD FRONT...A FAIRLY STRONG ONE AT
THAT...WILL MOVE THROUGH OUR REGION LATE IN THE DAY OR MONDAY NIGHT
WITH THE POSSIBILITY OF ADDITIONAL SHOWERS OR THUNDERSTORMS. AT THIS
POINT IT IS VERY HARD TO NAIL DOWN THE EXACT TIMING OF THE
SYSTEMS...OR WHICH ONE WOULD BRING THE BULK OF CONVECTIVE ACTIVITY.
BY TUESDAY...THE 12Z EUROPEAN HAS THE COLD FRONT TO OUR EAST. THERE
IS STILL THE UPPER AIR TROUGH THAT NEEDS TO COME THROUGH TO OUR
NORTH...BUT THERE WILL BE LOT LESS AVAILABLE MOISTURE. THEREFORE WE
DROP POPS TO SLIGHT CHANCES (24 PERCENT BY TUESDAY).
MEANWHILE...H850 TEMPERATURES ARE FORECAST TO COOL FROM ABOUT +16C
TO +17C ON MONDAY...DOWN TO AROUND +9C BY LATE TUESDAY VIA A GUSTY
NORTHWEST BREEZE.
HIGH PRESSURE BUILDS INTO THE REGION BY WEDNESDAY. HOWEVER...IT WILL
BE DISPLACED TO THE SOUTH AND EAST AS YET ANOTHER COOLER COLD FRONT
MOVES THROUGH ON THURSDAY. THIS ONE SHOULD HAVE VERY LITTLE MOISTURE
TO WORK WITH AND SO WE ONLY ASSIGNED SLIGHT POPS FOR THURSDAY.
BEHIND THE SECOND COLD FRONT COMES THE COOLEST AIRMASS SINCE LAST
MAY! EVEN THOUGH FORECAST H850 TEMPS WERE NOT AS COOL ON THIS RUN
COMPARED TO PREVIOUS ONES...TE EUROPEAN MODEL STILL INDICATED THEY
WOULD BE COOLING DOWN TO A RANGE BETWEEN +2C IN OUR NORTHERN
ZONES...TO ABOUT +5C IN OUR SOUTHERN ZONES BY FRIDAY.
TEMPERATURES ON LABOR DAY LOOK TO MAX OUT BETWEEN THE UPPER 70S
ACROSS THE MOUNTAINS...TO 80-85 ACROSS THE MAJORITY OF OUR COUNTY
WARNING AREA. THIS ASSUMES PLENTY OF CLOUD COVER. IF WE WERE TO
RECEIVE MORE BREAKS OF SUNSHINE IT COULD BE A LITTLE WARMER THAN
WHAT WE ARE FORECASTING ALONG WITH AN INCREASED RISK OF STRONGER
THUNDERSTORMS. EITHER WAY...IT WILL BE HUMID.
LOWS MONDAY NIGHT WILL RANGE BETWEEN THE UPPER 50S TO MID 60S.
TUESDAY WILL SEE HIGHS NEAR 80 AROUND POUGHKEEPSIE...MAINLY IN THE
70S ELSEWHERE...EXCEPT UPPER 60S OVER THE HIGHEST MOUNTAIN AREAS. A
BREEZE ON TUESDAY NIGHT MIGHT KEEP TEMPERATURES FROM FALLING MORE
THAN THEY WOULD HAVE OTHERWISE. A LITTLE COOLER TUESDAY NIGHT WITH
LOWS RANGING FROM THE MID 40S TO MID 50S.
WEDNESDAY MIGHT BE THE PICK OF THE WEAK...WITH LOW HUMIDITY...LOTS
OF SUNSHINE AND TEMPERATURES IN THE 70S. WEDNESDAY NIGHT LOWS WILL
BE SIMILAR TO TUESDAY...45 TO 55.
THURSDAY...AS THE H850 TEMPERATURES DIP INTO THE SINGLE
NUMBERS...THERE COULD BE A LOT OF CLOUD COVER AROUND AND THOSE
ISOLATED SHOWERS. HIGH TEMPERATURES THAT DAY MIGHT NOT GET OUT OF
THE 60S FROM ALBANY NORTHWARD...EVEN UPPER 50S ACROSS MUCH OF THE
ADIRONDACK PARK. EVEN FURTHER SOUTH...ONLY LOWER 70S FOR A HIGH
ACROSS THE MID HUDSON VALLEY AND LOWER LITCHFIELD COUNTY.
ENOUGH COLD AIR ADVECTION CLOUDS AND A GRADIENT WOULD BE ONLY THING
PREVENTING TEMPERATURES FROM REACHING FROSTY LEVELS IN OUR
ADIRONDACKS BY THURSDAY NIGHT. WE EXPECT BOTH THE CLOUDS AND A BIT
BREEZE TO HOLD TEMPERATURES UP A LITTLE...AS THEY WILL RANGE FROM
THE LOWER 40S NORTHWEST TO THE LOWER 50S NORTHWEST BY FRIDAY
MORNING.
TEMPERATURES ONCE AGAIN LOOK TO BE HELD MAINLY TO THE 60S ON FRIDAY
DESPITE A GOOD DEAL OF SUNSHINE.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
A BATCH OF SHOWERS AND SOME THUNDERSTORMS CONTINUE TO MOVE EASTERLY
ACROSS THE NORTHERN PORTION OF THE FORECAST AREA...MAINLY NORTH
I-90...IN ASSOCIATION WITH AN APPROACHING SHORT WAVE TROUGH AND
WEAK SURFACE LOW MOVING INTO THE SAINT LAWRENCE RIVER VALLEY. KGFL
HAS BEEN DIRECTLY IMPACTED BY THE CONVECTION WHILE STORMS HAVE
PASSED JUST TO THE NORTH OF KALB. THE THREAT OF SHOWERS AND
POSSIBLY THUNDERSTORMS WILL CONTINUE THIS MORNING. CHANCES FOR
CONVECTION WILL INCREASE LATER THIS MORNING AND ESPECIALLY DURING
THE AFTERNOON INTO EARLY EVENING HOURS AS THE SURFACE LOW PASSES
TO OUR NORTH AND ANOTHER SHORT WAVE TROUGH APPROACHES. WITH THE
HELP OF DAYTIME HEATING AND INCREASED INSTABILITY THERE WILL
BETTER AND WIDESPREAD CHANCES FOR SHOWERS AND THUNDERSTORMS SO
HAVE CONTINUED WITH A PROB30 GROUP IN THE TAF FOR THE THREAT OF
THUNDERSTORMS.
EXPECTING SOME MVFR FOG EARLY THIS MORNING WITH MVFR CIGS POSSIBLE.
VISIBILITIES IMPROVE AFTER SUNRISE. EXPECTING MAINLY VFR CONDITIONS
DURING THE DAY. MVFR AND BRIEF IFR CONDITIONS CAN BE EXPECTED WITH
ANY CONVECTION THAT IMPACTS TAF SITES. MVFR FIG IS EXPECTED TO
DEVELOP AGAIN THIS EVENING ESPECIALLY WHERE IT RAINS.
OUTLOOK...
SUNDAY-SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF
SHRA...TSRA.
LABOR DAY: HIGH OPERATIONAL IMPACT. LIKELY SHRA...TSRA.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
TUESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
TUESDAY NIGHT AND WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.FIRE WEATHER...
A WARM HUMID SOUTHWEST FLOW OF AIR WILL REMAIN IN PLACE THROUGH
MONDAY. THE BEST CHANCE FOR SHOWERS AND THUNDERSTORMS TONIGHT INTO
SATURDAY WITH A WEAK LOW PRESSURE SYSTEM...AND AGAIN ON LABOR DAY AS
STRONGER COLD FRONT PUSHES INTO THE REGION.
MAXIMUM RELATIVE HUMIDITY VALUES RISE TO AROUND 80 TO 100 PERCENT
TONIGHT. RH VALUES WILL ONLY DROP TO BETWEEN 50 AND 70 PERCENT ON
SATURDAY. WINDS TONIGHT WILL BE SOUTHWEST AROUND 5 MPH...BECOMING
LIGHT AND VARIABLE LATER TONIGHT. WINDS ON SATURDAY WILL BECOME
SOUTHERLY AND INCREASE TO AROUND 10 MPH. LIGHT AND VARIABLE WINDS
EXPECTED AGAIN ON SATURDAY NIGHT.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS.
THE NEXT SEVERAL DAYS THROUGH THE LABOR DAY WEEKEND WILL
FEATURE PERIODS OF ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS.
THE BEST CHANCE WILL BE LATE TONIGHT THROUGH SATURDAY AND AGAIN ON
LABOR DAY.
HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE
EXPECTED WITH THUNDERSTORMS. ISOLATED URBAN...SMALL STREAM AND POOR
DRAINAGE FLOODING WILL BE POSSIBLE DURING THE HOLIDAY WEEKEND. SOME
WITHIN BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE SHOWERS
AND STORMS OCCUR.
RAINFALL AMOUNTS WILL BE QUITE VARIABLE DUE TO THE SHOWERY NATURE
OF THE RAIN...WITH SOME LOCATIONS RECEIVING OVER AN INCH OF RAIN
WHILE OTHERS REMAIN DRY.
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...HWJIV/WASULA
NEAR TERM...WASULA
SHORT TERM...SND
LONG TERM...HWJIV
AVIATION...IAA
FIRE WEATHER...SND
HYDROLOGY...SND/JPV
AREA FORECAST DISCUSSION
NWS ALBANY NY
137 AM EDT SAT AUG 31 2013
.SYNOPSIS...
A SOUTHWEST FLOW OF WARM AND HUMID AIR...WILL COMBINE
WITH A WEAK LOW PRESSURE SYSTEM SLOWLY TRACKING EASTWARD THROUGH THE
SAINT LAWRENCE VALLEY TO PRODUCE ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS THIS MORNING THROUGH SUNDAY. A MUCH STRONGER SYSTEM
WILL BRING A THREAT FOR MORE NUMEROUS SHOWERS AND THUNDERSTORMS ON
LABOR DAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 137 AM EDT...THE NRN HALF OF THE FCST AREA CONTINUES TO HAVE
SCT-NUMEROUS SHOWERS AND SOME THUNDERSTORMS AHEAD OF A MID-LEVEL
SHORT-WAVE AND A SFC TROUGH ASSOCIATED WITH RIPPLES OF LOW PRESSUE
MOVING ALONG THE ST LAWRENCE RIVER VALLEY. A FEW STRONGER
THUNDERSTORMS HAVE MOVED ACROSS THE SARATOGA REGION WITH FQT LTG
BRIEF BURSTS OF HVY RAIN...AND POSSIBLY SOME SMALL HAIL.
THE LATEST RUC HAS SHOWALTER VALUES OF 0 TO -2C. THE ELEVATED
INSTABILITY WILL LINGER WITH A SLIGHT TO LOW CHC OF THUNDERSTORMS
THIS MORNING...ESPECIALLY NEAR THE LOW-LEVEL CONVERGENT BOUNDARY.
THERE IS LESS LTG UPSTREAM AND SOME OF THE SHOWERS ARE STARTING
MOVE SOUTH OF THE MOHAWK VALLEY. SLIGHT OR LOW CHC POPS WERE USED
HERE...BUT SOME LOCATIONS MAY REMAIN DRY SOUTH AND EAST OF THE
CAPITAL REGION.
MUGGY CONDITIONS WILL CONTINUE WILL DEWPTS IN THE 60S. OVERNIGHT
LOWS WILL BE ABOVE NORMAL IN THE 60S ACROSS THE FCST AREA.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/...
FOR SATURDAY...WEAK LOW PRESSURE AT THE SURFACE AND
ALOFT WILL REMAIN OVER AND NORTH OF THE AREA. WITH WARM AND HUMID
AIRMASS IN PLACE...ONLY A WEAK TRIGGER NEEDED TO START SHOWERS AND
STORMS. MODELS DON`T INDICATE ANY PARTICULAR FORCING FOR THE
SHOWERS/STORMS SO PARTLY SUNNY CONDITIONS WITH A CHANCE OF
AFTERNOON SHOWERS AND THUNDERSTORMS LOOKS GOOD. FOR
SUNDAY...STRONG IMPULSE HAS REACHED THE WESTERN GREAT LAKES. THIS
WORKS TO INDUCE WEAK RIDGING ACROSS THE ALBANY FORECAST AREA.
THIS WEAK RIDGING/HIGH PRESSURE SHOULD KEEP GENERALLY FAIR WEATHER
OVER THE AREA WITH AGAIN A CHANCE FOR SHOWERS AND THUNDERSTORMS...
MAINLY SUNDAY AFTERNOON. BY LATE SUNDAY NIGHT...AN UPPER LEVEL
TROUGH...ASSOCIATED WITH DEEP GREAT LAKES LOW MAY BRING AN
INCREASED THREAT OF SHOWERS AND STORMS.
MAX/MIN TEMPERATURES GENERALLY A MOS BLEND. AREAS OF FOG EXPECTED
EACH MORNING WITH STEAMY AIRMASS IN PLACE.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
THE LONG TERM PERIOD WILL COINCIDE WITH THE BEGINNING OF
METEOROLOGICAL FALL (WHICH STARTS RIGHT ON LABOR DAY). THIS
YEAR...ALMOST ON QUE...OUR WEATHER WILL BECOME MUCH MORE AUTUMNAL
FEELING. HAVE LEANED HEAVILY WITH THE 12Z EUROPEAN MODEL...WHICH IS
FAIRLY CLOSE TO THE HPC GUIDANCE.
ON LABOR DAY ITSELF...WE WILL REMAIN IN A FAIRLY HUMID AND WARM AIR
MASS. A PRE-FRONTAL TROUGH LOOKS TO BE THE INITIAL TRIGGER EARLY ON
LABOR DAY. THE ACTUAL COLD FRONT...A FAIRLY STRONG ONE AT
THAT...WILL MOVE THROUGH OUR REGION LATE IN THE DAY OR MONDAY NIGHT
WITH THE POSSIBILITY OF ADDITIONAL SHOWERS OR THUNDERSTORMS. AT THIS
POINT IT IS VERY HARD TO NAIL DOWN THE EXACT TIMING OF THE
SYSTEMS...OR WHICH ONE WOULD BRING THE BULK OF CONVECTIVE ACTIVITY.
BY TUESDAY...THE 12Z EUROPEAN HAS THE COLD FRONT TO OUR EAST. THERE
IS STILL THE UPPER AIR TROUGH THAT NEEDS TO COME THROUGH TO OUR
NORTH...BUT THERE WILL BE LOT LESS AVAILABLE MOISTURE. THEREFORE WE
DROP POPS TO SLIGHT CHANCES (24 PERCENT BY TUESDAY).
MEANWHILE...H850 TEMPERATURES ARE FORECAST TO COOL FROM ABOUT +16C
TO +17C ON MONDAY...DOWN TO AROUND +9C BY LATE TUESDAY VIA A GUSTY
NORTHWEST BREEZE.
HIGH PRESSURE BUILDS INTO THE REGION BY WEDNESDAY. HOWEVER...IT WILL
BE DISPLACED TO THE SOUTH AND EAST AS YET ANOTHER COOLER COLD FRONT
MOVES THROUGH ON THURSDAY. THIS ONE SHOULD HAVE VERY LITTLE MOISTURE
TO WORK WITH AND SO WE ONLY ASSIGNED SLIGHT POPS FOR THURSDAY.
BEHIND THE SECOND COLD FRONT COMES THE COOLEST AIRMASS SINCE LAST
MAY! EVEN THOUGH FORECAST H850 TEMPS WERE NOT AS COOL ON THIS RUN
COMPARED TO PREVIOUS ONES...TE EUROPEAN MODEL STILL INDICATED THEY
WOULD BE COOLING DOWN TO A RANGE BETWEEN +2C IN OUR NORTHERN
ZONES...TO ABOUT +5C IN OUR SOUTHERN ZONES BY FRIDAY.
TEMPERATURES ON LABOR DAY LOOK TO MAX OUT BETWEEN THE UPPER 70S
ACROSS THE MOUNTAINS...TO 80-85 ACROSS THE MAJORITY OF OUR COUNTY
WARNING AREA. THIS ASSUMES PLENTY OF CLOUD COVER. IF WE WERE TO
RECEIVE MORE BREAKS OF SUNSHINE IT COULD BE A LITTLE WARMER THAN
WHAT WE ARE FORECASTING ALONG WITH AN INCREASED RISK OF STRONGER
THUNDERSTORMS. EITHER WAY...IT WILL BE HUMID.
LOWS MONDAY NIGHT WILL RANGE BETWEEN THE UPPER 50S TO MID 60S.
TUESDAY WILL SEE HIGHS NEAR 80 AROUND POUGHKEEPSIE...MAINLY IN THE
70S ELSEWHERE...EXCEPT UPPER 60S OVER THE HIGHEST MOUNTAIN AREAS. A
BREEZE ON TUESDAY NIGHT MIGHT KEEP TEMPERATURES FROM FALLING MORE
THAN THEY WOULD HAVE OTHERWISE. A LITTLE COOLER TUESDAY NIGHT WITH
LOWS RANGING FROM THE MID 40S TO MID 50S.
WEDNESDAY MIGHT BE THE PICK OF THE WEAK...WITH LOW HUMIDITY...LOTS
OF SUNSHINE AND TEMPERATURES IN THE 70S. WEDNESDAY NIGHT LOWS WILL
BE SIMILAR TO TUESDAY...45 TO 55.
THURSDAY...AS THE H850 TEMPERATURES DIP INTO THE SINGLE
NUMBERS...THERE COULD BE A LOT OF CLOUD COVER AROUND AND THOSE
ISOLATED SHOWERS. HIGH TEMPERATURES THAT DAY MIGHT NOT GET OUT OF
THE 60S FROM ALBANY NORTHWARD...EVEN UPPER 50S ACROSS MUCH OF THE
ADIRONDACK PARK. EVEN FURTHER SOUTH...ONLY LOWER 70S FOR A HIGH
ACROSS THE MID HUDSON VALLEY AND LOWER LITCHFIELD COUNTY.
ENOUGH COLD AIR ADVECTION CLOUDS AND A GRADIENT WOULD BE ONLY THING
PREVENTING TEMPERATURES FROM REACHING FROSTY LEVELS IN OUR
ADIRONDACKS BY THURSDAY NIGHT. WE EXPECT BOTH THE CLOUDS AND A BIT
BREEZE TO HOLD TEMPERATURES UP A LITTLE...AS THEY WILL RANGE FROM
THE LOWER 40S NORTHWEST TO THE LOWER 50S NORTHWEST BY FRIDAY
MORNING.
TEMPERATURES ONCE AGAIN LOOK TO BE HELD MAINLY TO THE 60S ON FRIDAY
DESPITE A GOOD DEAL OF SUNSHINE.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
A LOT OF DEBRIS HIGH AND MID LEVEL CLOUDS SHOULD PREVENT THE
FORMATION OF IFR FOG TONIGHT. HOWEVER...SHOWERS AND EVEN
THUNDERSTORMS MIGHT IMPACT THE TAFS LATER OVERNIGHT.
WE ARE FOLLOWING A LINE OF SHOWERS AND THUNDERSTORMS WELL TO THE
WEST OF THE TERMINALS AS OF 745 PM EDT. WE EXPECT NO PROBLEMS
THROUGH THE EVENING HOURS AND ALL OF OUR SITES LOOK TO REMAIN VFR.
AS OF 930 PM EDT...WE HAD TO PLACE VCSH IN THE KALB AND KGFL CLOSER
TO 03Z BASED ON WHAT WE ON RADAR. SHOWERS WERE WORKING INTO THE
MOHAWK VALLEY TOWARD HERKIMER COUNTY.
CONFIDENCE REMAINED TOO LOW TO INCLUDE THUNDER (EVEN AS A TEMPO) AS
THE PROBABILITY OF THESE DIRECTLY IMPACTING A TAF SITE WAS ABOUT 25
PERCENT. WE WILL MONITOR THROUGHOUT THE EVENING HOURS...AND IF
CONFIDENCE INCREASES WE WILL UPDATE THE TAFS.
ASSUMING NOT A WHOLE LOT OF RAIN AND THE CLOUD COVER...SOME KGFL AND
KPSF MIGHT GO MVFR WITH SOME HAZE AND MVFR CIGS. HOWEVER...FOR
NOW...WE KEPT KALB AND KPOU VFR THROUGHOUT THE NIGHT (ADDING A
LITTLE HAZE BUT ONLY LOWERING VSBY TO 6SM).
LATER ON SATURDAY...THE CONVECTION THREAT LOOKS TO INCREASE AS A
SYSTEM OUT IN THE GREAT LAKES HEADS OUR WAY INCREASING INSTABILITY.
WE DECIDED TO INCLUDE A PROB30 GROUP FOR THUNDER AND MVFR MAINLY
DURING SATURDAY AFTERNOON AS THE THREAT OF A THUNDERSTORM IMPACTING
ANY TAF SITE IS ABOUT 30-49 PERCENT...UP TO HALF OF THE TIME.
THE SURFACE WIND WILL BE LIGHT OR SOUTH UNDER 5KTS
TONIGHT...INCREASING TO NEAR 10KTS LATER ON SATURDAY.
OUTLOOK...
SATURDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
SUNDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
LABOR DAY: HIGH OPERATIONAL IMPACT. LIKELY SHRA...TSRA.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
TUESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
TUESDAY NIGHT AND WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.FIRE WEATHER...
A WARM HUMID SOUTHWEST FLOW OF AIR WILL REMAIN IN PLACE THROUGH
MONDAY. THE BEST CHANCE FOR SHOWERS AND THUNDERSTORMS TONIGHT INTO
SATURDAY WITH A WEAK LOW PRESSURE SYSTEM...AND AGAIN ON LABOR DAY AS
STRONGER COLD FRONT PUSHES INTO THE REGION.
MAXIMUM RELATIVE HUMIDITY VALUES RISE TO AROUND 80 TO 100 PERCENT
TONIGHT. RH VALUES WILL ONLY DROP TO BETWEEN 50 AND 70 PERCENT ON
SATURDAY. WINDS TONIGHT WILL BE SOUTHWEST AROUND 5 MPH...BECOMING
LIGHT AND VARIABLE LATER TONIGHT. WINDS ON SATURDAY WILL BECOME
SOUTHERLY AND INCREASE TO AROUND 10 MPH. LIGHT AND VARIABLE WINDS
EXPECTED AGAIN ON SATURDAY NIGHT.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS.
THE NEXT SEVERAL DAYS THROUGH THE LABOR DAY WEEKEND WILL
FEATURE PERIODS OF ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS.
THE BEST CHANCE WILL BE LATE TONIGHT THROUGH SATURDAY AND AGAIN ON
LABOR DAY.
HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE
EXPECTED WITH THUNDERSTORMS. ISOLATED URBAN...SMALL STREAM AND POOR
DRAINAGE FLOODING WILL BE POSSIBLE DURING THE HOLIDAY WEEKEND. SOME
WITHIN BANK RISES ARE POSSIBLE ON LARGER STREAMS WHERE SHOWERS
AND STORMS OCCUR.
RAINFALL AMOUNTS WILL BE QUITE VARIABLE DUE TO THE SHOWERY NATURE
OF THE RAIN...WITH SOME LOCATIONS RECEIVING OVER AN INCH OF RAIN
WHILE OTHERS REMAIN DRY.
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...HWJIV/WASULA
NEAR TERM...WASULA
SHORT TERM...SND
LONG TERM...HWJIV
AVIATION...HWJIV
FIRE WEATHER...SND
HYDROLOGY...SND/JPV
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
240 AM EDT SAT AUG 31 2013
.UPDATE...
ISSUED AT 225 AM EDT SAT AUG 31 2013
DID A QUICK UPDATE TO THE GRIDS TO REFLECT THE LATEST RADAR TRENDS
AND POPS FROM THE HIGH RESOLUTION HRRR MODEL. THIS ENTAILED A RAMP
UP TO THE POPS A BIT EARLIER IN THE CUMBERLAND VALLEY ALONG WITH A
MORE IN THE WAY OF SKY COVER. ALSO ADJUSTED THE HOURLY T/TD GRIDS
BASED ON VARIANCES WITH THE LATEST OBS AND EXTENDED THEM FORWARD IN A
DAMPENING MANNER FOR THE NEXT SEVERAL HOURS. DID ALSO FINE TUNE THE
FOG IN THE WX GRIDS...INCLUDING SOME DENSE PATCHES IN THE DEEPER
VALLEYS OF THE EAST. UPDATES HAVE BEEN SENT TO THE NDFD AND WEB
SERVERS WHILE THE CURRENT ZONES STILL COVER THE OVERNIGHT PORTION OF
THE FORECAST.
UPDATE ISSUED AT 1026 PM EDT FRI AUG 30 2013
THE FORECAST CONTINUES TO BE ON TRACK SO FAR THIS EVENING IN ALL
REGARDS. TEMPERATURES...SKY COVER...AND WINDS WERE VERY CLOSE TO
ACTUAL OBSERVED CONDITIONS ACROSS THE ENTIRE FORECAST. THEREFORE...NO
UPDATED TO THE FORECAST IS PLANNED AT THIS TIME.
UPDATE ISSUED AT 725 PM EDT FRI AUG 30 2013
THE FORECAST IS RIGHT ON TRACK...SO NO UPDATE IS PLANNED AT THIS TIME.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 335 PM EDT FRI AUG 30 2013
A LARGE UPPER LEVEL RIDGE OF HIGH PRESSURE CENTERED ACROSS THE DESERT
SOUTHWEST HAS BEEN MAINTAINING DRY WEATHER ACROSS EASTERN KENTUCKY
FOR THE PAST FEW DAYS. SOME CONVECTION HAS MANAGED TO POP UP DOWN
ALONG THE TERRAIN IN TENNESSEE THIS AFTERNOON...HOWEVER THE CAP SEEMS
TO BE HOLDING ACROSS OUR SOUTHEAST COUNTIES THUS FAR. STILL...CAN NOT
COMPLETELY RULE OUT A FEW BUILD UPS THROUGH DUSK.
THE MODELS ARE IN GOOD AGREEMENT WITH THE LONG WAVE PATTERN THROUGH
THE SHORT TERM...WITH THE DESERT SOUTHWEST RIDGE GRADUALLY WEAKENING
AS SHORT WAVE ENERGY MOVES IN FROM CANADA AND TRAVERSES THE GREAT
LAKES AND OHIO VALLEY. THERE ARE MODEL DIFFERENCES CONCERNING THE
TIMING ON THE INTERMITTENT SHORT WAVE ENERGY...SO WILL CONTINUE TO
RELY ON THE CONTINUITY OF THE PREVIOUS FORECAST...BRINGING THE THREAT
OF SOME ISOLATED CONVECTION IN TOWARDS DAWN TONIGHT AS THE FIRST WEAK
WAVE APPROACHES. ONCE HEATING TAKES PLACE ON SATURDAY...EXPECT SCATTERED
CONVECTION TO FIRE UP. HIGHS WILL BE SIMILAR TO TODAY...WITH MID TO
UPPER 80S...ALTHOUGH THERE WILL LIKELY BE MORE CLOUD COVER IN THE
AFTERNOON...SO SOME LOCATIONS MAY NOT GET QUITE AS WARM.
ON SATURDAY NIGHT...THERE IS A LITTLE MORE TROUGHINESS THAT TAKES
SHAPE ACROSS THE OHIO VALLEY...SO STILL LIKE THE IDEA OF A LESS STEEP
DIURNAL DROP OFF IN THE POPS...AS THERE MAY BE SOME SCATTERED
CONVECTION FROM TIME TO TIME THROUGH THE NIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 335 PM EDT FRI AUG 30 2013
THE PERIOD WILL BEGIN WITH AN UPPER LEVEL RIDGE OF HIGH PRESSURE
OVER THE SOUTHERN ROCKIES/FOUR CORNERS REGION WITH TROUGHING FROM
THE HUDSON/JAMES BAY REGION SOUTH INTO THE GULF OF MEXICO REGION.
THIS TROUGH WAS BETWEEN THE TROUGH OVER THE ROCKIES AND ANOTHER
RIDGE CENTERED EAST OF THE BAHAMAS. A FEW SHORTWAVES ARE PROGGED TO
BE WORKING THROUGH THE OH VALLEY AT THAT TIME...ONE WORKING THROUGH
THE OH VALLEY LATE IN THE SHORT TERM PERIOD...POSSIBLY EXITING TO
THE EAST OF THE JKL CWA EARLY ON SUNDAY AND ANOTHER WORKING INTO THE
OH VALLEY ON SUNDAY. BEHIND THIS SECOND ONE...A SHORTWAVE ASSOCIATED
WITH AN UPPER LEVEL LOW WORKING ACROSS ONTARIO AND INTO QUEBEC AND
SHOULD HELP TO AMPLIFY THE EASTERN CONUS EARLY IN THE NEW WEEK AS IT
WORKS THROUGH THE GREAT LAKES AND OH VALLEY REGION INTO THE
NORTHEAST AND MID ATLANTIC THROUGH TUE AND WED. A SFC COLD FRONT
SHOULD PRECEDE THIS FINAL SHORTWAVE MENTIONED ABOVE AND MOVE SOUTH OF
THE OH RIVER MON EVENING/MONDAY NIGHT BEFORE EXITING THE CWA ON
TUESDAY.
BY MIDWEEK...THE CONSENSUS IS FOR UPPER LEVEL RIDGING TO BE CENTERED
OVER COLORADO WITH AN UPPER LEVEL LOW OFF THE PACIFIC NORTHWEST COAST
AND THE EASTERN TROUGH GRADUALLY LIFTING OUT TO THE NORTHEAST.
ANOTHER CLOSED LOW PASSING ACROSS THE HUDSON/JAMES BAY REGION INTO
THE CANADIAN MARITIMES FROM MID TO LATE WEEK SHOULD SEND ANOTHER
COLD FRONT THAT WILL BE BECOMING INCREASINGLY SHEARED AS IT REACHES
THE JKL CWA DURING THE SECOND HALF OF THE WEEK. MOISTURE SHOULD BE
LIMITED WITH THE SECOND BOUNDARY WITH LITTLE TIME FOR RETURN FLOW.
OVERALL...THE START OF THE WEEK SHOULD BE MOST ACTIVE AND UNSETTLED
WITH ROUNDS OF SCATTERED SHOWERS OR THUNDERSTORMS POSSIBLE AT TIMES
WITH EACH PASSING SHORTWAVE UNTIL THE COLD FRONT MOVES ACROSS
EASTERN AND SOUTH CENTRAL KY. COVERAGE SHOULD BE GREATEST DIURNALLY
ON AVERAGE...FOR SUNDAY AND MONDAY. A FEW HEAVY DOWNPOURS CANNOT BE
RULED OUT WITH THESE...ON SUN INTO SUN EVENING AS SHEAR AND WIND
FIELDS WILL BE WEAKEST SO STORM MOTIONS SHOULD BE LEAST WHILE PW WILL
BE A BIT ABOVE AVERAGE. PW IS FORECAST TO BE HIGHER ON MONDAY...BUT
AHEAD OF THE FRONT AND APPROACHING TROUGH STORM MOTIONS SHOULD BE
HIGHER.
AFTER SLIGHT CHANCE TO LIKELY POPS FOR THE SUN THROUGH TUESDAY
PERIOD...WE CONTINUED WITH A DRY FORECAST FOR THE REMAINDER OF THE
WEEK. WITH THE SECOND FRONT DURING THE SECOND HALF OF THE WEEK A
SHOWER OR THUNDERSTORM CANNOT BE RULED OUT FROM THU AFTERNOON
THROUGH FRIDAY...BUT THE BEST FORCING SHOULD REMAIN TO OUR NORTH AND
EAST.
INCREASING MOISTURE AND ASSOCIATED CLOUD COVER AND PRECIP IN THE
AREA SHOULD HOLD TEMPS WELL BELOW THE WARM MAV NUMBERS AND PROBABLY
BELOW THE MET NUMBERS AS WELL. THE HIGHS ON SUN AND MON WERE TRENDED
TOWARD THE COLDER CONSALL AND ECMWF MOS GUIDANCE. AFTER MONDAY...
HIGH TEMPERATURES SHOULD AVERAGE AS MUCH AS 5 DEGREES BELOW NORMAL
WITH MIN TEMPS ANTICIPATED TO BE A COUPLE OF DEGREES BELOW NORMAL.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 240 AM EDT SAT AUG 31 2013
ASIDE FROM SOME MVFR FOG AT LOZ...CONDITIONS WERE VFR AT THE TAF
SITES AND MOST OTHER PLACES. EXPECT SOME PATCHY FOG TO AFFECT JKL AND
LOZ THROUGH DAWN...BUT SME WILL PROBABLY BE SPARED SIMILAR TO LAST
NIGHT. THERE IS A POTENTIAL FOR A FEW SHOWERS TO POP UP IN THE
VICINITY OF THE TAF SITES TOWARDS DAWN. A THREAT OF THUNDERSTORMS
WILL EXIST FROM THEN ON INTO THE DAY AND NIGHT SATURDAY AS A LOW
PRESSURE AREA APPROACHES AND ACTIVATES OUR CURRENT WARM AND MOIST
AIR MASS. HAVE GONE WITH PREVAILING SHOWERS AND VCTS AT THE SITES BY
EARLY AFTERNOON. HAVE BACKED THESE OFF TO JUST A MENTION OF VCTS
AFTER 00Z AS COVERAGE SHOULD BECOME MORE SCATTERED. LATE NIGHT VISBY
RESTRICTIONS WILL BE POSSIBLE AT LOCATIONS THAT SEE RAIN...BUT HAVE
LEFT THAT OUT OF THE TAFS FOR NOW. WINDS THROUGH THE PERIOD...OUTSIDE
OF ANY STORM...WILL BE LIGHT AND VARIABLE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...GEOGERIAN
LONG TERM...JP
AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
339 AM CDT SAT AUG 31 2013
.DISCUSSION...
THE WEAK CDFNT THAT MOVED THROUGH THE FA ON FRI IS CURRENTLY
STATIONARY OVER NE KS/NRN MO AND WILL WASH OUT THIS MORNING AS THE
LOW-LEVEL FLOW BEGINS TO RESPOND TO THE NEXT MORE POTENT WEATHER
SYSTEM FOR THE FA. THIS SHORTWAVE TROUGH /CURRENTLY OVER SRN SASK
PER EARLY MRNG WV IMAGERY/ WILL TRACK EWD TODAY AND INTO THE
GREAT LAKES TONIGHT. THIS WILL ALLOW FOR A MUCH STRONGER CDFNT TO
MOVE ACROSS THE AREA TONIGHT LEADING TO SIGNIFICANTLY COOLER AIR
FOR THE CWA TO END THE WEEKEND AND START THE NEW WORK WEEK. UNTIL
THEN WE HAVE TO DEAL WITH ONE MORE HOT DAY. THE MODELS ARE
CONSISTENT IN THE HOT H85 TEMPERATURES RECOVERING TODAY...BUT
MIXING WILL BE A TOUCH LOWER THAN ON FRI AND THUS SURFACE
TEMPERATURES ARE EXPECTED TO BE A COUPLE DEGREES COOLER.
NEVERTHELESS WE STILL EXPECT HIGHS IN THE MID 90S CNTRL/SRN AND
AROUND 90 NORTH. THIS ALONG WITH THE DEWPOINTS REMAINING AROUND 70
FOR MOST AREAS WILL LEAD TO HEAT INDEX VALUES OF 95 TO 102 FOR
THIS AFTN...BUT WILL NOT ISSUE AN ADVRY FOR TODAY.
TSRA ARE LIKELY TO DEVELOP THIS AFTN ALONG THE COLD
FRONT...INITIALLY FM NE SD INTO NRN NEB. THESE LOOK TO MAKE IT
INTO THE FA RIGHT AT 00Z IN KNOX/CEDAR COUNTIES AND THUS HAVE
REMOVED POPS FOR THE DAY TIME HOURS. POINT FORECAST SOUNDINGS INDC
AROUND 3000 J/KG OF MLCAPE WILL BE AVAILABLE OVER NE NEB THIS
EVENING ALONG WITH AROUND 30 KT OF EFFECTIVE SHEAR. THIS MAY BE
SUFFICIENT FOR SOME STRONG STORMS TO MAKE IT INTO THE CWA.
RELATIVELY HIGH TEMPERATURE-DEWPOINT SPREADS /LOW SUB-CLOUD RH/
SHOULD KEEP CLOUD BASES HIGH AND BE EFFECTIVE FOR STRONG
DOWNDRAFTS. GIVEN A SCATTERING OF SEMI-ORGANIZED CONVECTION WITH
OUTFLOW...THIS COULD LEAD TO A SMALL FORWARD PROPAGATING MCS THIS
EVENING TRACKING SEWD THROUGH THE FA. SOME OF THE CONVECTION
ALLOWING MODELS INDICATING THIS REACHING I80 BY 03-05Z WHILE
OTHERS INDC LITTLE CONVECTION MAKING IT THAT FAR SOUTH. ALTHOUGH
A SMALL MCS IS POSSIBLE...THE CONFIDENCE IN COVERAGE AND
INTENSITY DECREASES WITH SOUTHWARD EXTEND INTO THE FA DUE
INCREASING CIN...DECREASING CAPE AND SHEAR. WE WILL INCREASE POPS
INTO THE LIKELY CAT OVER THE N THIS EVENING DECREASING TO CHC OVER
THE CNTRL/SRN CWA OVERNIGHT.
THE CDFNT WILL CLEAR THE FA SUN MORNING WITH BREEZY N WINDS
INCREASING...DEWPOINTS DROPPING AND TEMPERATURES MORE SEASONABLE.
THE DRY WX AND SEASONABLE TEMPERATURES ARE EXPECTED TO LAST INTO
TUE BEFORE THE UPPER LEVEL RIDGE BEGINS TO RECOVER INTO THE CNTRL
PLAINS AND TEMPERATURES INCREASE. AS THE MOISTURE RETURNS TO THE
AREA WE MAY SEE AN ISO TSRA ON WED NIGHT BUT MOST OF THIS ACTIVITY
WILL REMAIN OVER THE HIGH PLAINS. TEMPERATURES WILL GET BACK TO
AROUND 90 BY FRI AND WILL LIKELY CONT INTO NEXT WEEKEND.
BOUSTEAD
&&
.AVIATION...
06Z TAFS FOR KOFK...KOMA AND KLNK.
CONVECTION HAD MOVED INTO CENTRAL NEBRASKA AND WAS APPROACHING
EASTERN NEBRASKA AT 05Z. HRRR INDICATES SOME POTENTIAL SHOWERS
AT KOFK THROUGH 09Z OTHERWISE PRECIP DISSIPATES BEFORE REACHING
KLNK AND KOMA. MOIST BOUNDARY LAYER AND LIGHT WINDS MAY ALLOW
FOR A PERIOD OF FOG AND MVFR VSBY AT ALL THREE SITES 10Z-14Z.
FOBERT
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1250 AM CDT SAT AUG 31 2013
.UPDATE...
ISSUED AT 1143 PM CDT FRI AUG 30 2013
CONTINUE TO MONITOR THE AREA OF SHOWERS AND THUNDERSTORMS
SPREADING ACROSS CENTRAL NEBRASKA AT THIS HOUR. WHILE SEVERE
WEATHER IS NOT ANTICIPATED WITH THIS ACTIVITY...LATEST MODEL
GUIDANCE AS WELL AS RADAR TRENDS ARE TRYING TO HOLD THIS AREA OF
SHOWERS AND ISOLATED THUNDERSTORMS TOGETHER AS IT CROSSES THE
FORECAST AREA. AS A RESULT...WENT AHEAD AND INCREASED CHANCES FOR
PRECIPITATION OVERNIGHT TO CLOSELY FOLLOW 02Z HRRR FOR THE NEXT
FEW HOURS...WITH SHOWERS DIMINISHING AROUND 12Z. EVEN SO...EXPECT
LITTLE MORE THAN A FEW HUNDREDTHS OF AN INCH OF PRECIPITATION WITH
THIS ACTIVITY.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 430 PM CDT FRI AUG 30 2013
THE MAIN HIGHLIGHTS OF THE NEXT 36 HOURS INCLUDE ONE MORE DAY OF
NOTABLE LATE SUMMER HEAT ON SATURDAY BEFORE READINGS RETURN TO
MORE SEASONAL LEVELS FOR SUNDAY...ALONG WITH STILL HIGHLY-
UNCERTAIN THUNDERSTORM CHANCES BOTH TONIGHT AND ESPECIALLY FOR
SATURDAY NIGHT. WANT TO STATE OFF THE TOP THAT MODELS VARY
CONSIDERABLY ON THE PROBABILITY/COVERAGE OF CONVECTION SATURDAY
NIGHT...AND THUS POPS CONTINUE TO BE CAPPED AT NO MORE THAN 30-40
PERCENT ACROSS THE CWA.
STARTING OFF LATE THIS AFTERNOON...20Z OBJECTIVE SURFACE ANALYSIS
DEPICTS A SURFACE TROUGH/VERY WEAK COLD FRONT STRETCHED FROM
NORTHWEST KS INTO CENTRAL IA...WITH THE VAST MAJORITY OF THE CWA
POSITIONED JUST NORTH OF THIS BOUNDARY. AS A RESULT...BREEZES THIS
AFTERNOON HAVE PREVAILED FROM THE EAST-NORTHEAST AT SPEEDS
GENERALLY AROUND 10 MPH WITH OCCASIONAL HIGHER GUSTS.
HOWEVER...THIS HAS BY NO MEANS BEEN A COOLING NORTHERLY WIND
COMPONENT...AS HIGH TEMPS ARE ON TARGET TO RANGE FROM THE LOW-MID
90S CENTRAL/NORTHEAST...TO THE UPPER 90S TO AROUND 104 IN
SOUTHERN ZONES. FURTHERMORE...THE FAIRLY LIGHT EAST-NORTHEAST
BREEZE HAS ALLOWED DEWPOINTS ACROSS MAINLY THE NORTHEAST 2/3 OF
THE CWA TO REMAIN WELL UP AROUND 70...RESULTING IN POSSIBLY THE
MOST WIDESPREAD COVERAGE OF 100-105 HEAT INDEX VALUES WE HAVE SEEN
ALL WEEK...WITH VALUES IN ALL AREAS LIKELY SAFELY UNDER 100 BY
01Z/8PM. ALOFT...WATER VAPOR IMAGERY SHOWS THE CWA LOCATED
NORTHEAST OF THE CENTER OF THE EXPANSIVE MID/UPPER RIDGE AXIS
CENTERED OVER CO...RESULTING IN NORTH/NORTHWEST FLOW OVERHEAD.
WHILE WATER VAPOR AND MODELED VORTICITY FIELDS HINT AT SOME SUBTLE
PERTURBATIONS HELPING KICK OFF HIGH PLAINS CONVECTION OFF TO OUR
WEST AT THIS HOUR...BY FAR THE MOST NOTABLE SHORTWAVE OF INTEREST
FOR THE NEXT FEW DAYS WEATHER IS SHIFTING EAST INTO SOUTHERN
ALBERTA AT THIS TIME. VISIBLE SATELLITE LATE THIS AFTERNOON SHOWS
ESSENTIALLY CLOUD-FREE SKIES OVER THE VAST MAJORITY OF THE
CWA...WITH ONLY SOME VERY HIGH BASED CUMULUS DEVELOPING FROM
INTENSE HEATING IN OUR FAR SOUTHERN KS ZONES.
TURNING TO THE EVENING/OVERNIGHT HOURS...FROM A BASIC SENSE HAVE
MADE VERY LITTLE CHANGE TO THE PREVIOUS FORECAST. HAVE KEPT LOW
END 20-30 PERCENT STORM CHANCES CONFINED TO ROUGHLY THE NORTHWEST
1/3 OF THE CWA...WITH TWO POSSIBLE SCENARIOS ENVISIONED AND
PORTRAYED BY VARIOUS MODELS. STARTING WITH THE BIG PICTURE
ALOFT...VERY SUBTLE HEIGHT FALLS WILL OCCUR AS THE LARGE RIDGE
AXIS FLATTENS JUST A BIT IN RESPONSE TO THE AFOREMENTIONED CANADIAN
SHORTWAVE TROUGH SHIFTING EAST TO JUST NORTH OF THE MT/ND BORDER
BY SUNRISE. CLOSER TO HOME...VERY SUBTLE MID LEVEL
PERTURBATIONS...POSSIBLY CONVECTIVELY DRIVEN...WILL CONTINUE
SHIFTING EAST TOWARD/INTO THE CWA FROM THE CENTRAL HIGH PLAINS.
SOME MODELS...NAMELY THE HRRR AND 12Z 4KM WRF-NMM...ARE
SURPRISINGLY AGGRESSIVE IN DRIVING HIGH PLAINS CONVECTION EASTWARD
INTO AT LEAST WESTERN PORTIONS OF THE CWA THIS EVENING...BUT WITH
A GENERAL TREND OF KILLING OFF CONVECTION AS IT GETS TOWARD
CENTRAL PORTIONS OF THE CWA LIKELY IN RESPONSE TO INCREASING CINH.
ALTHOUGH A FEW STORMS ARE ALREADY EVIDENT 100+ MILES WEST OF THE
CWA...UNCERTAINTY IS QUITE HIGH WHETHER OR NOT ANY OF THIS WILL
ACTUALLY SLIP INTO OUR AREA...AND THUS OPTED TO KEEP LOW POPS
CONFINED TO WESTERN COUNTIES AND NOT ADVERTISE ANYTHING ACROSS THE
MAJORITY OF THE AREA...BUT THIS WILL NEED WATCHED. LATER IN THE
NIGHT...MODELS SUCH AS THE RAP KICK OFF A POTENTIALLY SEPARATE
AREA OF HIGH-BASED CONVECTION IN OUR NORTHWEST COUNTIES POSSIBLY
IN RESPONSE TO MID-LEVEL THETA-E ADVECTION...BUT AGAIN THIS IS
MAINLY IN THE AREA ALREADY COVERED WITH LOW POPS. IF STORMS
DEVELOP/MOVE IN THIS EVENING/OVERNIGHT...WOULD BE SURPRISED TO SEE
MORE THAN SMALL SUB-SEVERE HAIL. OTHERWISE...BREEZES TONIGHT WILL
AVERAGE VERY LIGHT/EASTERLY...AND MADE LITTLE IF ANY CHANGE TO
OVERNIGHT LOWS WITH MAINLY 66-71.
TURNING TO THE SATURDAY DAYTIME/SATURDAY NIGHT HOURS...AGAIN ON
THE SURFACE THERE HAS BEEN LITTLE NOTICEABLE CHANGE FROM THE
PREVIOUS FORECAST...WITH THE OVERALL BEST CHANCES FOR RAIN/STORMS
DURING THE CURRENT VALID 7-DAY FORECAST ARRIVING SATURDAY
NIGHT...ALTHOUGH BY FAR FROM A SURE THING. ON THE LARGE
SCALE...THE FAIRLY VIGOROUS SHORTWAVE TROUGH ALONG CENTRAL
PORTIONS OF THE U.S./CANADIAN BORDER ON SATURDAY MORNING WILL
SLIDE EAST-SOUTHEAST TO OVER/NEAR LAKE SUPERIOR BY SUNRISE SUNDAY
MORNING...WITH THIS WAVE LOWERING HEIGHTS FURTHER OVER THE LOCAL
AREA AND SHUNTING THE RIDGE SLIGHTLY OFF TO THE SOUTHWEST A BIT.
AT THE SURFACE...BY FAR THE BIG STORY IS A LEGITIMATE COLD FRONT
THAT WILL BE FORCED SOUTHWARD INTO THE CENTRAL PLAINS FROM THIS
WAVE. DURING THE DAYTIME HOURS...THERE IS GOOD AGREEMENT THIS
FRONT WILL BE POSITIONED AT LEAST SLIGHTLY NORTHWEST OF THE CWA
THROUGH LATE AFTERNOON...BEFORE PASSING THROUGH SOMEWHAT
AGGRESSIVELY DURING THE NIGHT AS FAR AS SUMMER COLD FRONTS
GO...WITH ALL AREAS EXPECTED TO HAVE A STEADY 10+ MPH NORTH BREEZE
AND INCREASINGLY COOLER/DRIER AIR BY SUNRISE SUNDAY MORNING. DUE
TO THE CWA REMAINING AHEAD OF THE FRONT DURING THE DAY...ONE MORE
HOT/STEAMY AFTERNOON IS IN STORE...WITH MAYBE ONLY A BIT MORE IN
THE WAY OF MID/HIGH CLOUDS POSSIBLE HOLDING SOME AREAS A TAD
COOLER THAN TODAY...BUT STILL AIMING FOR LOW-MID 90S
CENTRAL/NORTHEAST TO NEAR 100 SOUTH/SOUTHWEST...WITH HEAT INDEX
VALUES AGAIN AROUND 100 OR SLIGHTLY HIGHER. AS FOR DAYTIME
CONVECTIVE CHANCES...THERE IS ADMITTEDLY SOME UNCERTAINTY
HERE...AS SOME MODELS SUCH AS THE NAM SUGGEST THAT ESPECIALLY THE
WESTERN 1/2 OF THE CWA COULD SEE SOME LIKELY HIGH-BASED DAYTIME
CONVECTION...EVEN IN THE MORNING...POSSIBLY A CONTINUATION OF SOME
ACTIVITY THAT MIGHT DEVELOP LATE TONIGHT. HOWEVER...FORECAST
SOUNDINGS AND A CONCEPTUAL MODEL OF THIS PATTERN SUGGEST THAT VERY
WARM MID LEVEL TEMPERATURES ARE MORE LIKELY TO INHIBIT DAYTIME
CONVECTION THAN SUPPORT IT. SO ALTHOUGH ITS NO GUARANTEE...LEFT
POPS BELOW THE MENTIONABLE 15+ PERCENT THRESHOLD IN THE MORNING AND
THROUGH MID-AFTERNOON...BUT LEFT SLIGHT CHANCES MAINLY IN THE
WESTERN 1/2 DURING THE LATE AFTERNOON JUST IN CASE SOMETHING CAN
GET GOING IN THE HOT/DEEPLY MIXED AIRMASS AHEAD OF THE FRONT.
CERTAINLY THE BETTER LARGE-SCALE SUPPORT TO BREAK THROUGH THE CAP
AND SUPPORT CONVECTION COMES SATURDAY NIGHT...AS THE SURFACE COLD
FRONT PASSES THROUGH AND IS ACCOMPANIED/FOLLOWED BY A DECENT AXIS
OF MID LEVEL FRONTOGENESIS. EVEN SO...WITH THE MAIN TRACK OF THE
PARENT SHORTWAVE TROUGH TRACKING HUNDREDS OF MILES NORTHEAST OF
THE CWA...THERE ARE PLENTY OF QUESTIONS ABOUT HOW WIDESPREAD THIS
CONVECTION WILL BE. FOR EXAMPLE...WILL IT SWEEP THROUGH FROM
NORTHWEST-SOUTHEAST IN A FAIRLY SOLID LINE AS THE 12Z NAM WOULD
SUGGEST...OR WILL IT BE VERY HIT-AND-MISS AND IN FACT MISS THE
MAJORITY OF THE AREA ALTOGETHER AS THE 12Z 4KM-WRF NMM
REFLECTIVITY PROG WOULD SUGGEST. WITH THIS STILL BEING 24+ HOURS
OUT...OPTED TO PLAY POPS FAIRLY STATUS QUO FOR NOW...CAPPING THEM
IN THE 30-40 PERCENT RANGE GIVEN THIS DEGREE OF UNCERTAINTY.
IF/WHEN STORM FORM...CERTAINLY CANNOT RULE OUT AT LEAST A MARGINAL
SEVERE THREAT...WITH THE NAM ADVERTISING 2000+ J/KG OF CAPE IN THE
850-700MB LAYER IN THE EVENING...BUT IN THE PRESENCE OF ONLY
25-30KT OF DEEP LAYER SHEAR. ITS CERTAINLY POSSIBLE THAT IF ENOUGH
STORMS FORM AND DEVELOP INTO A FORWARD-PROPAGATING LINE THAT AN
ENHANCED WIND THREAT COULD MATERIALIZE...BUT THIS IS ALL
PREDICATED ON HOW WIDESPREAD DEVELOPMENT ULTIMATELY IS. NO MATTER
WHAT...ROUGHLY THE NORTHWEST 1/3 TO 1/2 OF THE CWA SHOULD BE CLEAR
OF STORM CHANCES BY AROUND MIDNIGHT OR SHORTLY THEREAFTER...WITH
THE LATE NIGHT FOCUS IN THE SOUTHEASTERN 1/2. LOW TEMPS BY SUNRISE
SUNDAY ARE FORECAST TO RANGE LOW 60S NORTH TO NEAR 70 FAR
SOUTHEAST.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 430 PM CDT FRI AUG 30 2013
MAIN CONCERNS ARE CHANCES FOR THUNDERSTORMS SUNDAY MORNING AND
WEDNESDAY EVENING.
ON THE LARGE SCALE...THE WEATHER PATTERN WILL BE SWINGING TO A
NORTHWEST FLOW REGIME AS THE UPPER LEVEL RIDGE THAT HAS BEEN
PERSISTENT OVER THE AREA THE LAST WEEK OR SO RETROGRADES WEST. THIS
CHANGE IN FLOW WILL RESULT IN TEMPERATURES ABOUT 10 DEGREES COOLER
THAN THIS WEEK AND SOME LOW CHANCES FOR RAIN AS FRONTAL BOUNDARIES
INTERMITTENTLY MOVE THROUGH THE AREA.
MODELS SUGGESTING LINGERING STORMS POSSIBLE EARLY SUNDAY MORNING
BEFORE CONVECTION EXITS SOUTHEAST OF THE AREA. WE LEFT SMALL CHANCES
OF RAIN IN OVER THE EXTREME SOUTHEAST CORNER OF THE CWA SUNDAY
MORNING AS THE FRONT SAGS OUT OF THE AREA. ALL MODELS SUGGEST A
CHANCE FOR STORMS WEDNESDAY EVENING AS ANOTHER COOL FRONT MOVES
THROUGH THE AREA. THERE IS A MARGINAL THREAT THAT A FEW OF THE
STORMS MAY PRODUCE SMALL HAIL AND GUSTY WINDS WEDNESDAY NIGHT
DUE TO LOW TO MARGINAL INSTABILITY AND WEAK SHEAR.
OTHER THAN THOSE TWO PERIODS...HIGH PRESSURE SHOULD BE THE DOMINANT
WEATHER FEATURE. SO DRY AND NEAR TO SLIGHTLY ABOVE NORMAL TEMPS WILL
BE THE RULE MOST DAYS.
&&
.AVIATION...(FOR THE 06Z KGRI TAF THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1245 AM CDT SAT AUG 31 2013
A SMALL LINE OF SHOWERS AND THUNDERSTORMS IS RAPIDLY EXPANDING
TOWARD KGRI THIS MORNING. WHILE VFR CONDITIONS ARE EXPECTED TO
PREVAIL AS THIS LINE MOVES ACROSS THE TERMINAL...MAY SEE A BRIEF
MVFR VSBY OR CIG IN A -SHRA OR -TSRA. EVEN SO...CONFIDENCE OF THIS
WAS LOW ENOUGH TO NOT INCLUDE A TEMPO GROUP IN THE TAF FOR THE
TIME BEING. ONCE THE OVERALL THREAT OF SHRAS DIMINISHES AROUND
09-10Z...SKIES WILL BEGIN TO CLEAR AND LIGHT WINDS WILL PREVAIL
THROUGH THE REMAINDER OF THE OVERNIGHT HOURS BEFORE INCREASING OUT
OF THE SOUTH DURING THE MORNING HOURS SATURDAY. SOUTHERLY WINDS
ARE THEN EXPECTED TO PREVAIL FOR THE DURATION OF THE DAY AHEAD OF
AN APPROACHING COLD FRONT...WHICH WILL BRING GUSTY NORTHWESTERLY
WINDS AND THE CHANCE FOR SHRSA/TSRAS AFT 01/04Z.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...SAR
SHORT TERM...PFANNKUCH
LONG TERM...EDDY
AVIATION...SAR
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1225 AM CDT SAT AUG 31 2013
.UPDATE...
ISSUED AT 1056 PM CDT FRI AUG 30 2013
SEVERE WEATHER THREAT HAS DIMINISHED AND WILL DROP THE EXTENDED
WATCH EARLY. REMAINDER OF FORECAST ON TRACK.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 307 PM CDT FRI AUG 30 2013
TONIGHT THROUGH SATURDAY...A WEAK UPPER LEVEL DISTURBANCE...
CURRENTLY ACROSS THE WYOMING...WILL MOVE ACROSS THE FCST AREA
TONIGHT SPAWNING A FAIRLY ORGANIZED AREA OF TSTMS. ALL MODELS SHOW
K INDICES INCREASING TO AROUND 40C OR GREATER. THE RAP AND OTHER
MODELS SHOW PRECIPITABLE WATER INCREASING TO 1.50 INCHES OR
GREATER. FCST STORM MOTION OF 10KT OR LESS WOULD SUPPORT LOCALLY
HEAVY RAINFALL AND WEAK WINDS ALOFT 30KT OR LESS AT AND BELOW
300MB SUGGEST OUTFLOW DOMINANT COLD POOL DRIVEN BOW SEGMENTS
CAPABLE OF GUSTY WINDS.
LOW LEVEL EASTERLIES AND WEAK WESTERLIES ALOFT PRODUCE BULK SHEAR OF
35 TO 40 KT SO SOME STORMS THIS EVENING COULD BECOME SEVERE WITH
WIND DAMAGE AND LARGE HAIL. SPC PROVIDED THIS DISCUSSION AT 227 PM
CDT...RECENT LIGHTNING WITHIN THE CONVECTION ALONG THE BLACK
HILLS AND LARAMIE MOUNTAINS HAS INCREASED CONFIDENCE THAT THE
ENVIRONMENT ACROSS THE CNTRL PLAINS IS GRADUALLY BECOMING MORE
SUPPORTIVE OF SURFACE-BASED CONVECTIVE INITIATION. 12Z RAP SOUNDING
MODIFIED FOR 19Z SURFACE OBSERVATION -- 93/62 -- YIELDS STRONG
SURFACE-BASED INSTABILITY /SBCAPE OVER 3000 J PER KG/ AND LITTLE
REMAINING CINH. INCREASED CONVERGENCE ALONG A WEAK SURFACE TROUGH
AND CONTINUED DESTABILIZATION FOSTERED BY ISOLATION IS EXPECTED TO
RESULT IN ADDITIONAL SURFACE-BASED CONVECTIVE DEVELOPMENT DURING THE
NEXT HOUR OR TWO.
THE STORM COMPLEX COULD MOVE MOSTLY EAST ACCORDING TO THE RAP MODEL
OR TAKE A SOUTHEAST TURN AS INDICATED BY THE HRRR. EITHER WAY THE
CONVECTION WILL AFFECT MOST OF THE FCST AREA AND EXIT SOUTH OR EAST
BY AROUND 12Z.
THIS TSTM COMPLEX SHOULD SET UP A FRONTAL BOUNDARY FOR ADDITIONAL
STORM DEVELOPMENT SATURDAY AFTN AND BEYOND WITH THE BEST SHEAR AND
INSTABILITY ACROSS NCNTL NEB NEAR KANW AND KONL. THE MODELS HAVE A
TOTALLY DIFFERENT IDEA IN MIND WITH THE FRONT AND LIFT IT RAPIDLY
NORTH BY 15Z SATURDAY MORNING AND THEN DROP ANOTHER COLD FRONT
THROUGH DURING THE AFTN. SO THERE IS A DISCONNECT IN CONVENTIONAL
STORM THEORY VS THE MODELS. IF THE FRONT IS DOES NOT RETREAT NORTH
AS QUICKLY THAN STORM DEVELOPMENT COULD BE MUCH FARTHER
SOUTH...PERHAPS OVER KS. THE FCST USES A BLEND OF NAM...GEMREG...GFS
AND ECM FOR A 30 POP FROM 20Z ONWARD...MAINLY SOUTH AND EAST OF
KVTN/KIML.
TEMPERATURES ARE A BLEND OF TRIED AND TRUE MODEL DATA PLUS BIAS
CORRECTION FOR HIGHS IN THE LOWER 90S NORTH TO UPPER 90S SOUTH.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 307 PM CDT FRI AUG 30 2013
SATURDAY NIGHT THROUGH LABOR DAY...
COLD FRONT SHOULD STRETCH FROM NEAR ANW THROUGH LBF AND IML EARLY
SATURDAY EVENING. DO EXPECT SCATTERED SHOWERS AND THUNDERSTORMS
ALONG AND AHEAD OF THE FRONT. COVERAGE MAY END UP LESS ACROSS SWRN
NEBR WHICH WILL BE FURTHER REMOVED FROM COOLER TEMPERATURES ALOFT
ASSOCIATED WITH MAIN UPPER TROUGH ACROSS MINNESOTA. ONLY A SLIGHT
CHANCE FOR THUNDERSTORMS FAR SOUTHEAST AFTER MIDNIGHT. DRY AND
LESS HOT SUNDAY AND LABOR DAY. HIGHS SUNDAY FORECAST VERY NEAR
PREVIOUS FROM NEAR 83 NCTRL AND 85 TO 88 SOUTHWEST. NORTHERLY WINDS
SUNDAY LOOK FAIRLY LIGHT FROM 5 TO 15 MPH WEST AND 10 TO 20 MPH
EAST. ON LABOR DAY...NORTHWEST FLOW ALOFT WILL CONTINUE WITH A
RETURN SOUTHEAST FLOW AT THE SURFACE AND HIGHS FROM NEAR 83
NORTHEAST TO NEAR 90 WEST TIER. SOUTHERLY WINDS MONDAY FROM 10 TO
20 MPH WEST TO 5 TO 15 MPH EAST.
ON TUESDAY THROUGH FRIDAY...
A HEAT UP AGAIN LIKELY AS UPPER RIDGE PERSISTS OVER COLORADO AND
TROUGHING INCREASES ACROSS THE PAC NW AND NORTHEASTERN U.S. A WEAK
COLD FRONT AND DISTURBANCE IN NORTHWEST FLOW ALOFT INDICATED BY
THE GFS AND ECMWF. THIS FRONT ASSOCIATED WITH A DEEP UPPER LOW
MOVING ACROSS HUDSON BAY. AS A RESULT OF ECMWF CONSISTENCY AND
FAIR AGREEMENT BY THE GFS...WILL INTRODUCE A SLIGHT CHANCE FOR
THUNDERSTORMS WEDNESDAY NIGHT. AN OTHERWISE DRY EXTENDED. HIGHS
FORECAST IN THE UPPER 80S TO LOW 90S MOST AREAS WITH MID 90S PARTS
OF SWRN NEBR.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1224 AM CDT SAT AUG 31 2013
THUNDERSTORMS WILL CONTINUE OVER WESTERN AND CENTRAL NEBRASKA
TONIGHT. SOME MVFR CEILINGS IN THE VICINITY OF THUNDERSTORMS WITH
GUSTY WINDS TO 35 KTS. HAVE INCLUDED THUNDERSTORMS IN THE TAF AT
KLBF WITH STORMS TO THE WEST BUT HAVE LEFT OUT OF KVTN. SOME PATCHY
FOG IS POSSIBLE OVER NORTHERN NEBRASKA AROUND SUNRISE. THUNDERSTORMS
ARE EXPECTED OVER SOUTHWEST NEBRASKA AGAIN SATURDAY AFTERNOON ALONG
THE COLD FRONT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...POWER
SHORT TERM...CDC
LONG TERM...ROBERG
AVIATION...POWER
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1150 PM CDT FRI AUG 30 2013
.UPDATE...
ISSUED AT 1143 PM CDT FRI AUG 30 2013
CONTINUE TO MONITOR THE AREA OF SHOWERS AND THUNDERSTORMS
SPREADING ACROSS CENTRAL NEBRASKA AT THIS HOUR. WHILE SEVERE
WEATHER IS NOT ANTICIPATED WITH THIS ACTIVITY...LATEST MODEL
GUIDANCE AS WELL AS RADAR TRENDS ARE TRYING TO HOLD THIS AREA OF
SHOWERS AND ISOLATED THUNDERSTORMS TOGETHER AS IT CROSSES THE
FORECAST AREA. AS A RESULT...WENT AHEAD AND INCREASED CHANCES FOR
PRECIPITATION OVERNIGHT TO CLOSELY FOLLOW 02Z HRRR FOR THE NEXT
FEW HOURS...WITH SHOWERS DIMINISHING AROUND 12Z. EVEN SO...EXPECT
LITTLE MORE THAN A FEW HUNDREDTHS OF AN INCH OF PRECIPITATION WITH
THIS ACTIVITY.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 430 PM CDT FRI AUG 30 2013
THE MAIN HIGHLIGHTS OF THE NEXT 36 HOURS INCLUDE ONE MORE DAY OF
NOTABLE LATE SUMMER HEAT ON SATURDAY BEFORE READINGS RETURN TO
MORE SEASONAL LEVELS FOR SUNDAY...ALONG WITH STILL HIGHLY-
UNCERTAIN THUNDERSTORM CHANCES BOTH TONIGHT AND ESPECIALLY FOR
SATURDAY NIGHT. WANT TO STATE OFF THE TOP THAT MODELS VARY
CONSIDERABLY ON THE PROBABILITY/COVERAGE OF CONVECTION SATURDAY
NIGHT...AND THUS POPS CONTINUE TO BE CAPPED AT NO MORE THAN 30-40
PERCENT ACROSS THE CWA.
STARTING OFF LATE THIS AFTERNOON...20Z OBJECTIVE SURFACE ANALYSIS
DEPICTS A SURFACE TROUGH/VERY WEAK COLD FRONT STRETCHED FROM
NORTHWEST KS INTO CENTRAL IA...WITH THE VAST MAJORITY OF THE CWA
POSITIONED JUST NORTH OF THIS BOUNDARY. AS A RESULT...BREEZES THIS
AFTERNOON HAVE PREVAILED FROM THE EAST-NORTHEAST AT SPEEDS
GENERALLY AROUND 10 MPH WITH OCCASIONAL HIGHER GUSTS.
HOWEVER...THIS HAS BY NO MEANS BEEN A COOLING NORTHERLY WIND
COMPONENT...AS HIGH TEMPS ARE ON TARGET TO RANGE FROM THE LOW-MID
90S CENTRAL/NORTHEAST...TO THE UPPER 90S TO AROUND 104 IN
SOUTHERN ZONES. FURTHERMORE...THE FAIRLY LIGHT EAST-NORTHEAST
BREEZE HAS ALLOWED DEWPOINTS ACROSS MAINLY THE NORTHEAST 2/3 OF
THE CWA TO REMAIN WELL UP AROUND 70...RESULTING IN POSSIBLY THE
MOST WIDESPREAD COVERAGE OF 100-105 HEAT INDEX VALUES WE HAVE SEEN
ALL WEEK...WITH VALUES IN ALL AREAS LIKELY SAFELY UNDER 100 BY
01Z/8PM. ALOFT...WATER VAPOR IMAGERY SHOWS THE CWA LOCATED
NORTHEAST OF THE CENTER OF THE EXPANSIVE MID/UPPER RIDGE AXIS
CENTERED OVER CO...RESULTING IN NORTH/NORTHWEST FLOW OVERHEAD.
WHILE WATER VAPOR AND MODELED VORTICITY FIELDS HINT AT SOME SUBTLE
PERTURBATIONS HELPING KICK OFF HIGH PLAINS CONVECTION OFF TO OUR
WEST AT THIS HOUR...BY FAR THE MOST NOTABLE SHORTWAVE OF INTEREST
FOR THE NEXT FEW DAYS WEATHER IS SHIFTING EAST INTO SOUTHERN
ALBERTA AT THIS TIME. VISIBLE SATELLITE LATE THIS AFTERNOON SHOWS
ESSENTIALLY CLOUD-FREE SKIES OVER THE VAST MAJORITY OF THE
CWA...WITH ONLY SOME VERY HIGH BASED CUMULUS DEVELOPING FROM
INTENSE HEATING IN OUR FAR SOUTHERN KS ZONES.
TURNING TO THE EVENING/OVERNIGHT HOURS...FROM A BASIC SENSE HAVE
MADE VERY LITTLE CHANGE TO THE PREVIOUS FORECAST. HAVE KEPT LOW
END 20-30 PERCENT STORM CHANCES CONFINED TO ROUGHLY THE NORTHWEST
1/3 OF THE CWA...WITH TWO POSSIBLE SCENARIOS ENVISIONED AND
PORTRAYED BY VARIOUS MODELS. STARTING WITH THE BIG PICTURE
ALOFT...VERY SUBTLE HEIGHT FALLS WILL OCCUR AS THE LARGE RIDGE
AXIS FLATTENS JUST A BIT IN RESPONSE TO THE AFOREMENTIONED CANADIAN
SHORTWAVE TROUGH SHIFTING EAST TO JUST NORTH OF THE MT/ND BORDER
BY SUNRISE. CLOSER TO HOME...VERY SUBTLE MID LEVEL
PERTURBATIONS...POSSIBLY CONVECTIVELY DRIVEN...WILL CONTINUE
SHIFTING EAST TOWARD/INTO THE CWA FROM THE CENTRAL HIGH PLAINS.
SOME MODELS...NAMELY THE HRRR AND 12Z 4KM WRF-NMM...ARE
SURPRISINGLY AGGRESSIVE IN DRIVING HIGH PLAINS CONVECTION EASTWARD
INTO AT LEAST WESTERN PORTIONS OF THE CWA THIS EVENING...BUT WITH
A GENERAL TREND OF KILLING OFF CONVECTION AS IT GETS TOWARD
CENTRAL PORTIONS OF THE CWA LIKELY IN RESPONSE TO INCREASING CINH.
ALTHOUGH A FEW STORMS ARE ALREADY EVIDENT 100+ MILES WEST OF THE
CWA...UNCERTAINTY IS QUITE HIGH WHETHER OR NOT ANY OF THIS WILL
ACTUALLY SLIP INTO OUR AREA...AND THUS OPTED TO KEEP LOW POPS
CONFINED TO WESTERN COUNTIES AND NOT ADVERTISE ANYTHING ACROSS THE
MAJORITY OF THE AREA...BUT THIS WILL NEED WATCHED. LATER IN THE
NIGHT...MODELS SUCH AS THE RAP KICK OFF A POTENTIALLY SEPARATE
AREA OF HIGH-BASED CONVECTION IN OUR NORTHWEST COUNTIES POSSIBLY
IN RESPONSE TO MID-LEVEL THETA-E ADVECTION...BUT AGAIN THIS IS
MAINLY IN THE AREA ALREADY COVERED WITH LOW POPS. IF STORMS
DEVELOP/MOVE IN THIS EVENING/OVERNIGHT...WOULD BE SURPRISED TO SEE
MORE THAN SMALL SUB-SEVERE HAIL. OTHERWISE...BREEZES TONIGHT WILL
AVERAGE VERY LIGHT/EASTERLY...AND MADE LITTLE IF ANY CHANGE TO
OVERNIGHT LOWS WITH MAINLY 66-71.
TURNING TO THE SATURDAY DAYTIME/SATURDAY NIGHT HOURS...AGAIN ON
THE SURFACE THERE HAS BEEN LITTLE NOTICEABLE CHANGE FROM THE
PREVIOUS FORECAST...WITH THE OVERALL BEST CHANCES FOR RAIN/STORMS
DURING THE CURRENT VALID 7-DAY FORECAST ARRIVING SATURDAY
NIGHT...ALTHOUGH BY FAR FROM A SURE THING. ON THE LARGE
SCALE...THE FAIRLY VIGOROUS SHORTWAVE TROUGH ALONG CENTRAL
PORTIONS OF THE U.S./CANADIAN BORDER ON SATURDAY MORNING WILL
SLIDE EAST-SOUTHEAST TO OVER/NEAR LAKE SUPERIOR BY SUNRISE SUNDAY
MORNING...WITH THIS WAVE LOWERING HEIGHTS FURTHER OVER THE LOCAL
AREA AND SHUNTING THE RIDGE SLIGHTLY OFF TO THE SOUTHWEST A BIT.
AT THE SURFACE...BY FAR THE BIG STORY IS A LEGITIMATE COLD FRONT
THAT WILL BE FORCED SOUTHWARD INTO THE CENTRAL PLAINS FROM THIS
WAVE. DURING THE DAYTIME HOURS...THERE IS GOOD AGREEMENT THIS
FRONT WILL BE POSITIONED AT LEAST SLIGHTLY NORTHWEST OF THE CWA
THROUGH LATE AFTERNOON...BEFORE PASSING THROUGH SOMEWHAT
AGGRESSIVELY DURING THE NIGHT AS FAR AS SUMMER COLD FRONTS
GO...WITH ALL AREAS EXPECTED TO HAVE A STEADY 10+ MPH NORTH BREEZE
AND INCREASINGLY COOLER/DRIER AIR BY SUNRISE SUNDAY MORNING. DUE
TO THE CWA REMAINING AHEAD OF THE FRONT DURING THE DAY...ONE MORE
HOT/STEAMY AFTERNOON IS IN STORE...WITH MAYBE ONLY A BIT MORE IN
THE WAY OF MID/HIGH CLOUDS POSSIBLE HOLDING SOME AREAS A TAD
COOLER THAN TODAY...BUT STILL AIMING FOR LOW-MID 90S
CENTRAL/NORTHEAST TO NEAR 100 SOUTH/SOUTHWEST...WITH HEAT INDEX
VALUES AGAIN AROUND 100 OR SLIGHTLY HIGHER. AS FOR DAYTIME
CONVECTIVE CHANCES...THERE IS ADMITTEDLY SOME UNCERTAINTY
HERE...AS SOME MODELS SUCH AS THE NAM SUGGEST THAT ESPECIALLY THE
WESTERN 1/2 OF THE CWA COULD SEE SOME LIKELY HIGH-BASED DAYTIME
CONVECTION...EVEN IN THE MORNING...POSSIBLY A CONTINUATION OF SOME
ACTIVITY THAT MIGHT DEVELOP LATE TONIGHT. HOWEVER...FORECAST
SOUNDINGS AND A CONCEPTUAL MODEL OF THIS PATTERN SUGGEST THAT VERY
WARM MID LEVEL TEMPERATURES ARE MORE LIKELY TO INHIBIT DAYTIME
CONVECTION THAN SUPPORT IT. SO ALTHOUGH ITS NO GUARANTEE...LEFT
POPS BELOW THE MENTIONABLE 15+ PERCENT THRESHOLD IN THE MORNING AND
THROUGH MID-AFTERNOON...BUT LEFT SLIGHT CHANCES MAINLY IN THE
WESTERN 1/2 DURING THE LATE AFTERNOON JUST IN CASE SOMETHING CAN
GET GOING IN THE HOT/DEEPLY MIXED AIRMASS AHEAD OF THE FRONT.
CERTAINLY THE BETTER LARGE-SCALE SUPPORT TO BREAK THROUGH THE CAP
AND SUPPORT CONVECTION COMES SATURDAY NIGHT...AS THE SURFACE COLD
FRONT PASSES THROUGH AND IS ACCOMPANIED/FOLLOWED BY A DECENT AXIS
OF MID LEVEL FRONTOGENESIS. EVEN SO...WITH THE MAIN TRACK OF THE
PARENT SHORTWAVE TROUGH TRACKING HUNDREDS OF MILES NORTHEAST OF
THE CWA...THERE ARE PLENTY OF QUESTIONS ABOUT HOW WIDESPREAD THIS
CONVECTION WILL BE. FOR EXAMPLE...WILL IT SWEEP THROUGH FROM
NORTHWEST-SOUTHEAST IN A FAIRLY SOLID LINE AS THE 12Z NAM WOULD
SUGGEST...OR WILL IT BE VERY HIT-AND-MISS AND IN FACT MISS THE
MAJORITY OF THE AREA ALTOGETHER AS THE 12Z 4KM-WRF NMM
REFLECTIVITY PROG WOULD SUGGEST. WITH THIS STILL BEING 24+ HOURS
OUT...OPTED TO PLAY POPS FAIRLY STATUS QUO FOR NOW...CAPPING THEM
IN THE 30-40 PERCENT RANGE GIVEN THIS DEGREE OF UNCERTAINTY.
IF/WHEN STORM FORM...CERTAINLY CANNOT RULE OUT AT LEAST A MARGINAL
SEVERE THREAT...WITH THE NAM ADVERTISING 2000+ J/KG OF CAPE IN THE
850-700MB LAYER IN THE EVENING...BUT IN THE PRESENCE OF ONLY
25-30KT OF DEEP LAYER SHEAR. ITS CERTAINLY POSSIBLE THAT IF ENOUGH
STORMS FORM AND DEVELOP INTO A FORWARD-PROPAGATING LINE THAT AN
ENHANCED WIND THREAT COULD MATERIALIZE...BUT THIS IS ALL
PREDICATED ON HOW WIDESPREAD DEVELOPMENT ULTIMATELY IS. NO MATTER
WHAT...ROUGHLY THE NORTHWEST 1/3 TO 1/2 OF THE CWA SHOULD BE CLEAR
OF STORM CHANCES BY AROUND MIDNIGHT OR SHORTLY THEREAFTER...WITH
THE LATE NIGHT FOCUS IN THE SOUTHEASTERN 1/2. LOW TEMPS BY SUNRISE
SUNDAY ARE FORECAST TO RANGE LOW 60S NORTH TO NEAR 70 FAR
SOUTHEAST.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 430 PM CDT FRI AUG 30 2013
MAIN CONCERNS ARE CHANCES FOR THUNDERSTORMS SUNDAY MORNING AND
WEDNESDAY EVENING.
ON THE LARGE SCALE...THE WEATHER PATTERN WILL BE SWINGING TO A
NORTHWEST FLOW REGIME AS THE UPPER LEVEL RIDGE THAT HAS BEEN
PERSISTENT OVER THE AREA THE LAST WEEK OR SO RETROGRADES WEST. THIS
CHANGE IN FLOW WILL RESULT IN TEMPERATURES ABOUT 10 DEGREES COOLER
THAN THIS WEEK AND SOME LOW CHANCES FOR RAIN AS FRONTAL BOUNDARIES
INTERMITTENTLY MOVE THROUGH THE AREA.
MODELS SUGGESTING LINGERING STORMS POSSIBLE EARLY SUNDAY MORNING
BEFORE CONVECTION EXITS SOUTHEAST OF THE AREA. WE LEFT SMALL CHANCES
OF RAIN IN OVER THE EXTREME SOUTHEAST CORNER OF THE CWA SUNDAY
MORNING AS THE FRONT SAGS OUT OF THE AREA. ALL MODELS SUGGEST A
CHANCE FOR STORMS WEDNESDAY EVENING AS ANOTHER COOL FRONT MOVES
THROUGH THE AREA. THERE IS A MARGINAL THREAT THAT A FEW OF THE
STORMS MAY PRODUCE SMALL HAIL AND GUSTY WINDS WEDNESDAY NIGHT
DUE TO LOW TO MARGINAL INSTABILITY AND WEAK SHEAR.
OTHER THAN THOSE TWO PERIODS...HIGH PRESSURE SHOULD BE THE DOMINANT
WEATHER FEATURE. SO DRY AND NEAR TO SLIGHTLY ABOVE NORMAL TEMPS WILL
BE THE RULE MOST DAYS.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 610 PM CDT FRI AUG 30 2013
VFR CONDITIONS FORECAST THROUGH THE NEXT 24 HOURS.
OCCASIONAL CLOUDS...WITH BASES BETWEEN 7000 AND 15000FT AGL...ARE
EXPECTED THROUGH THE NEXT 24 HOURS. THE SURFACE WIND IS EXPECTED
TO REMAIN LIGHT AND VARIABLE THROUGH EARLY SATURDAY AFTERNOON
BEFORE BECOMING MORE ESTABLISHED FROM THE SOUTH AT AROUND 08KTS.
VISIBILITY RESTRICTION IS NOT EXPECTED AT GRI THROUGH THE NEXT 24
HOURS.
AS OF 23Z...SHOWER AND THUNDERSTORM ACTIVITY CONTINUES ACROSS
WESTERN NEBRASKA. THE PROBABILITY OF THIS ACTIVITY IMPACTING GRI
THIS EVENING OR TONIGHT IS VERY LOW...TOO LOW IN FACT TO INTRODUCE
INTO THE TAF AT THIS TIME. THAT BEING SAID...TRENDS WILL NEED TO
BE MONITORED THROUGH THE NEXT 6-12 HOURS FOR THE POSSIBLE
INSERTION OF CONVECTIVE ACTIVITY INTO THE TAF.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...SAR
SHORT TERM...PFANNKUCH
LONG TERM...EDDY
AVIATION...BRYANT
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1134 PM CDT FRI AUG 30 2013
.AVIATION...
06Z TAFS FOR KOFK...KOMA AND KLNK.
CONVECTION HAD MOVED INTO CENTRAL NEBRASKA AND WAS APPROACHING
EASTERN NEBRASKA AT 05Z. HRRR INDICATES SOME POTENTIAL SHOWERS
AT KOFK THROUGH 09Z OTHERWISE PRECIP DISSIPATES BEFORE REACHING
KLNK AND KOMA. MOIST BOUNDARY LAYER AND LIGHT WINDS MAY ALLOW
FOR A PERIOD OF FOG AND MVFR VSBY AT ALL THREE SITES 10Z-14Z.
&&
.PREV DISCUSSION... /ISSUED 313 PM CDT FRI AUG 30 2013/
DISCUSSION...
LOOKS LIKE WE WILL HAVE ONE MORE DAY OF HEAT BEFORE A BRIEF
COOLDOWN INTO EARLY NEXT WEEK...AND A CHANCE FOR STORMS SATURDAY
NIGHT. THEN PATTERN REBOUNDS BACK TOWARD WARMER THAN NORMAL FOR THE
REST OF NEXT WEEK.
A WEAK COLD FRONT WAS LIMPING THROUGH THE CWA THIS AFTERNOON...WITH
THE ONLY REAL INDICATION OF THE BOUNDARY BEING WINDS SHIFTING FROM
SOUTHWEST TO NORTH. TEMPERATURES WERE STILL CLIMBING WELL INTO THE
90S...AND DEW POINTS STILL IN THE 60S OR LOWER 70S. INSTABILITY WAS
INCREASING TO NEAR 3000 J/KG OF MOST UNSTABLE CAPE...BUT WARM
TEMPERATURES ALOFT WERE KEEPING A LID ON CONVECTION. SHORT RANGE
MESOSCALE MODELS WERE HINTING AT ISOLATED CONVECTION POPPING UP THIS
AFTERNOON IN SOUTHEAST NEBRASKA OR SOUTHWEST IOWA AS FRONT MOVES
THROUGH...BUT LID WILL BE AWFULLY HARD TO OVERCOME. WILL WATCH
TRENDS AND MAY HAVE TO INSERT A SMALL POP IN OUR FAR SOUTHEAST IN
THE EARLY EVENING.
OTHERWISE THIS FRONT WILL WASHOUT OVERNIGHT AND SATURDAY AS WINDS
TURN BACK TO SOUTHERLY WITH THE APPROACH OF ANOTHER COLD FRONT. THAT
FRONT WILL BE DRIVEN BY A STRONG SHORTWAVE RIDING EAST TO SOUTHEAST
THROUGH THE SOUTHERN CANADIAN PLAINS SATURDAY AND INTO THE NORTHERN
GREAT LAKES ON SUNDAY. AHEAD OF THIS FRONT...MOST UNSTABLE CAPE WILL
AGAIN INCREASE TO OVER 2500 J/KG AS SURFACE DEWPOINTS REMAIN BETWEEN
65 AND 70. MID LEVEL TEMPERATURES AT 700MB WILL BE A COUPLE OF
DEGREES COOLER AS WELL. TIMING OF SURFACE CONVERGENCE LOOKS TO ENTER
THE CWA LATE IN THE DAY OVER NORTHEAST NEBRASKA...THEN MOVE STEADILY
THROUGH THE REST OF THE AREA OVERNIGHT. GIVEN DEGREE OF
INSTABILITY...COOLER MID LEVEL TEMPS AND STRONGER CONVERGENCE ALONG
FRONT...EXPECT AT LEAST SCATTERED STORMS TO FIRE ACROSS MUCH OF THE
CWA AS THE FRONT MOVES THROUGH...AND PERHAPS AS EARLY AS LATE
AFTERNOON IN THE NORTHEAST. SEVERE POTENTIAL LOOKS TO BE LOW AS
SHEAR PROFILES WILL BE MODERATE AT BEST AND MOST ACTIVITY WILL BE
OCCURRING DURING TIME OF DECLINING INSTABILITY WITH LOSS OF DAYTIME
HEATING. A FEW STORMS MAY LINGER IN OUR SOUTHEAST INTO SUNDAY
MORNING...BUT THE BEST SHOT OF CONVECTION WILL END BEFORE SUNRISE
FOR MOST OF OUR AREA.
DERGAN
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
FOBERT
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1057 PM CDT FRI AUG 30 2013
.UPDATE...
ISSUED AT 1056 PM CDT FRI AUG 30 2013
SEVERE WEATHER THREAT HAS DIMINISHED AND WILL DROP THE EXTENDED
WATCH EARLY. REMAINDER OF FORECAST ON TRACK.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 307 PM CDT FRI AUG 30 2013
TONIGHT THROUGH SATURDAY...A WEAK UPPER LEVEL DISTURBANCE...
CURRENTLY ACROSS THE WYOMING...WILL MOVE ACROSS THE FCST AREA
TONIGHT SPAWNING A FAIRLY ORGANIZED AREA OF TSTMS. ALL MODELS SHOW
K INDICES INCREASING TO AROUND 40C OR GREATER. THE RAP AND OTHER
MODELS SHOW PRECIPITABLE WATER INCREASING TO 1.50 INCHES OR
GREATER. FCST STORM MOTION OF 10KT OR LESS WOULD SUPPORT LOCALLY
HEAVY RAINFALL AND WEAK WINDS ALOFT 30KT OR LESS AT AND BELOW
300MB SUGGEST OUTFLOW DOMINANT COLD POOL DRIVEN BOW SEGMENTS
CAPABLE OF GUSTY WINDS.
LOW LEVEL EASTERLIES AND WEAK WESTERLIES ALOFT PRODUCE BULK SHEAR OF
35 TO 40 KT SO SOME STORMS THIS EVENING COULD BECOME SEVERE WITH
WIND DAMAGE AND LARGE HAIL. SPC PROVIDED THIS DISCUSSION AT 227 PM
CDT...RECENT LIGHTNING WITHIN THE CONVECTION ALONG THE BLACK
HILLS AND LARAMIE MOUNTAINS HAS INCREASED CONFIDENCE THAT THE
ENVIRONMENT ACROSS THE CNTRL PLAINS IS GRADUALLY BECOMING MORE
SUPPORTIVE OF SURFACE-BASED CONVECTIVE INITIATION. 12Z RAP SOUNDING
MODIFIED FOR 19Z SURFACE OBSERVATION -- 93/62 -- YIELDS STRONG
SURFACE-BASED INSTABILITY /SBCAPE OVER 3000 J PER KG/ AND LITTLE
REMAINING CINH. INCREASED CONVERGENCE ALONG A WEAK SURFACE TROUGH
AND CONTINUED DESTABILIZATION FOSTERED BY ISOLATION IS EXPECTED TO
RESULT IN ADDITIONAL SURFACE-BASED CONVECTIVE DEVELOPMENT DURING THE
NEXT HOUR OR TWO.
THE STORM COMPLEX COULD MOVE MOSTLY EAST ACCORDING TO THE RAP MODEL
OR TAKE A SOUTHEAST TURN AS INDICATED BY THE HRRR. EITHER WAY THE
CONVECTION WILL AFFECT MOST OF THE FCST AREA AND EXIT SOUTH OR EAST
BY AROUND 12Z.
THIS TSTM COMPLEX SHOULD SET UP A FRONTAL BOUNDARY FOR ADDITIONAL
STORM DEVELOPMENT SATURDAY AFTN AND BEYOND WITH THE BEST SHEAR AND
INSTABILITY ACROSS NCNTL NEB NEAR KANW AND KONL. THE MODELS HAVE A
TOTALLY DIFFERENT IDEA IN MIND WITH THE FRONT AND LIFT IT RAPIDLY
NORTH BY 15Z SATURDAY MORNING AND THEN DROP ANOTHER COLD FRONT
THROUGH DURING THE AFTN. SO THERE IS A DISCONNECT IN CONVENTIONAL
STORM THEORY VS THE MODELS. IF THE FRONT IS DOES NOT RETREAT NORTH
AS QUICKLY THAN STORM DEVELOPMENT COULD BE MUCH FARTHER
SOUTH...PERHAPS OVER KS. THE FCST USES A BLEND OF NAM...GEMREG...GFS
AND ECM FOR A 30 POP FROM 20Z ONWARD...MAINLY SOUTH AND EAST OF
KVTN/KIML.
TEMPERATURES ARE A BLEND OF TRIED AND TRUE MODEL DATA PLUS BIAS
CORRECTION FOR HIGHS IN THE LOWER 90S NORTH TO UPPER 90S SOUTH.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 307 PM CDT FRI AUG 30 2013
SATURDAY NIGHT THROUGH LABOR DAY...
COLD FRONT SHOULD STRETCH FROM NEAR ANW THROUGH LBF AND IML EARLY
SATURDAY EVENING. DO EXPECT SCATTERED SHOWERS AND THUNDERSTORMS
ALONG AND AHEAD OF THE FRONT. COVERAGE MAY END UP LESS ACROSS SWRN
NEBR WHICH WILL BE FURTHER REMOVED FROM COOLER TEMPERATURES ALOFT
ASSOCIATED WITH MAIN UPPER TROUGH ACROSS MINNESOTA. ONLY A SLIGHT
CHANCE FOR THUNDERSTORMS FAR SOUTHEAST AFTER MIDNIGHT. DRY AND
LESS HOT SUNDAY AND LABOR DAY. HIGHS SUNDAY FORECAST VERY NEAR
PREVIOUS FROM NEAR 83 NCTRL AND 85 TO 88 SOUTHWEST. NORTHERLY WINDS
SUNDAY LOOK FAIRLY LIGHT FROM 5 TO 15 MPH WEST AND 10 TO 20 MPH
EAST. ON LABOR DAY...NORTHWEST FLOW ALOFT WILL CONTINUE WITH A
RETURN SOUTHEAST FLOW AT THE SURFACE AND HIGHS FROM NEAR 83
NORTHEAST TO NEAR 90 WEST TIER. SOUTHERLY WINDS MONDAY FROM 10 TO
20 MPH WEST TO 5 TO 15 MPH EAST.
ON TUESDAY THROUGH FRIDAY...
A HEAT UP AGAIN LIKELY AS UPPER RIDGE PERSISTS OVER COLORADO AND
TROUGHING INCREASES ACROSS THE PAC NW AND NORTHEASTERN U.S. A WEAK
COLD FRONT AND DISTURBANCE IN NORTHWEST FLOW ALOFT INDICATED BY
THE GFS AND ECMWF. THIS FRONT ASSOCIATED WITH A DEEP UPPER LOW
MOVING ACROSS HUDSON BAY. AS A RESULT OF ECMWF CONSISTENCY AND
FAIR AGREEMENT BY THE GFS...WILL INTRODUCE A SLIGHT CHANCE FOR
THUNDERSTORMS WEDNESDAY NIGHT. AN OTHERWISE DRY EXTENDED. HIGHS
FORECAST IN THE UPPER 80S TO LOW 90S MOST AREAS WITH MID 90S PARTS
OF SWRN NEBR.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1221 PM CDT FRI AUG 30 2013
ALL MODELS ARE DEVELOPING SCATTERED DEEP CONVECTION ACROSS WRN NEB
THIS AFTN AROUND 21Z-22Z. STORM ACTIVITY SHOULD MOVE EAST INTO NCNTL NEB
BY OR DURING THE EVENING. THE HRRR SUGGESTS STORMS COULD HIT KVTN
AND KLBF BETWEEN 01Z AND 04Z. THE HRRR AND RAP INDICATE BOWING
TSTM SEGMENTS DEVELOPING IN THE WEST WHICH COULD COALESCE NORTH
AND SOUTH ACROSS THE FCST AREA THIS EVENING. THE STORM ACTIVITY
SHOULD BE MOSTLY EAST OF THE FCST AREA BY 09Z WITH VFR THEREAFTER.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...POWER
SHORT TERM...CDC
LONG TERM...ROBERG
AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS ALBUQUERQUE NM
1121 PM MDT FRI AUG 30 2013
.AVIATION...
06Z TAF CYCLE
JUST A FEW SHRA/TSRA REMAIN BETWEEN KFMN AND KE33...AND MUCH OF
THIS ACTIVITY SHOULD DIMINISH BY 07Z. HAVE KEPT A PERIOD OF IFR
CIGS IN KGUP OVERNIGHT. OTHERWISE...VFR WILL BE THE RULE THROUGH
AT LEAST 18Z SAT. SHRA/TSRA WILL REDEVELOP SAT AFTN OVER THE HIGH
TERRAIN. THE NRN MTS WILL BE FAVORED...THOUGH SOME OF THIS
ACTIVITY MAY ROLL OFF INTO THE NE PLAINS. LOCALLY HEAVY RAIN WILL
BE THE MAIN THREAT WITH THESE STORMS. MUCH OF THE ACTIVITY WILL
AGAIN DIMINISH BY 06Z SUN.
34
&&
.PREV DISCUSSION...947 PM MDT FRI AUG 30 2013...
WILL ADJUST POPS DOWN CONSIDERABLY FOR THE REMAINDER OF THE NIGHT
BASED ON RADAR TRENDS AND HRRR MODEL. ZONES OUT SHORTLY. CHJ
.PREV DISCUSSION...334 PM MDT FRI AUG 30 2013...
LATEST BLENDED TOTAL PRECIPITABLE WATER SATELLITE IMAGERY
INDICATING A ROUGHLY THREE TENTHS OF AN INCH DROP IN SAME OVER
PAST ROUGHLY 18 HOURS ACROSS NE NM. THUS SOME OF THE SIGNIFICANTLY
DRIER AIR IN E CO EARLIER IS EASING SOUTHWARD INTO THE STATE.
THE RATON DEWPOINT HAS DROPPED TO 29 DEGREES AS OF MID AFTN AND
THIS DRIER AIR EXPECTED TO CONTINUE HEADING TO S AND TO SOME
DEGREE SW OVER NEXT 24 TO 36 HOURS.
CENTER OF THE UPPER HIGH NOW OVER FAR NE NM TODAY WILL SAG A BIT
FARTHER TO SW INTO OR VERY NEAR CENTRAL NM BY SAT AFTN. A SLIGHT
MOISTURE UPTICK MAY STILL OCCUR IN THE NW CORNER OF NM SAT...BUT
ELSEWHERE THE AIRMASS WILL SHOW LITTLE PWAT CHANGE AND IN MANY
CASES SOME DECREASE. LOWERED POPS A BIT MORE ACROSS MAINLY CENTRAL
AND NE NM FOR SAT GIVEN PWAT TREND OF TODAY SO FAR. EXPECT ANOTHER
VERY WARM TO HOT DAY IN EAST NM AGAIN SAT WITH UPPER 90S AND A FEW
TRIPLE DIGIT READINGS AGAIN. DECIDED TO GO AHEAD AT INCLUDE NEAR
RECORD TEMP HIGHLIGHTS IN HAZARD GRID FOR MUCH OF E CENTRAL AND NE
NM SAT.
HIGH PRESSURE WILL STAY OVER CENTRAL NM ON SUN...BUT HAVING LOST A
BIT OF STRENGTH. BACK DOOR COLD FRONT...FIRST IN QUITE SOME TIME...
TO DROP INTO NORTHEASTERN NM SUN MORN...SO SAY MAJORITY OF FCST
MODELS. IN ITS WAKE WILL COME HIGHER SFC DEWPOINTS AND SOME
UPSLOPE FORCING FOR A HEALTHY INCREASE IN SHOWER AND STORM ACTION
ALONG THE EAST SLOPES OF THE SANGRE DE CRISTOS AND INTO THE
NORTHEASTERN PLAINS. HAVE KEPT THE LIKELY POPS CATEGORY IN MUCH OF
THIS REGION...BUT TRIMMED ITS SOUTHERNMOST EXTENT JUST A HAIR.
WEAK STEERING FLOW WILL KEEP OVERALL MOVEMENT OF CELLS VERY SLOW...
BUT THAT MAY CAUSE ACTUAL OVERALL MOVEMENT TO BE MORE DRIVEN BY
FRONTAL MOVEMENT AND BOUNDARY INTERACTIONS.
THE FRONT WILL SURGE FARTHER SOUTH AND WEST SUN LATE AFTN AND
NIGHT...MOST LIKELY MAKING IT TO OR PERHAPS EVEN WEST OF THE
CONTINENTAL DIVIDE BY EARLY MON. SOME LEFTOVER UPSLOPE FLOW MAY
KEEP THINGS GOING ALONG THE CENTRAL MOUNTAIN CHAIN MONDAY...BUT
THE FOCUS MAY SHIFT TOWARD THE DIVIDE AND HIGH TERRAIN WEST OF THE
RIO GRANDE. SOME MODELS ARE LESSENING THEIR EARLIER FAVORING
THEIR MORE WESTWARD BIAS OF THE MON PCPN.
THERE IS STILL NO SIGNS OF THE UPPER HIGH BREAKING DOWN
SIGNIFICANTLY IN MID TO LATER PERIODS...THOUGH THE CENTER MAY EASE
A LITTLE WAYS OUT OF NM. GFS FAVORS AN EVEN STRONGER BACK DOOR
FRONT COMING INTO NM THE WEEKEND OF SEP 7TH...WHILE THE EUROPEAN
IS MUCH SLOWER AND WEAKER WITH IT...SHOWING IT STAYING NE OF THE
STATE THROUGH SUN NIGHT. 43
.FIRE WEATHER...
A DRIER AND MORE STABLE AIRMASS ALOFT HAS PUSHED OVER MORE OF THE
FORECAST AREA TODAY. SHOWERS AND THUNDERSTORMS ARE MUCH MORE MUTED
AS A RESULT. THE MAIN WETTING RAIN CHANCE WILL BE FOUND ALONG
AND WEST OF THE CONTINENTAL DIVIDE. TEMPERATURES ARE QUITE WARM
ACROSS THE EAST WITH NEAR RECORD LEVELS. HUMIDITY VALUES AS A RESULT
HAVE FALLEN INTO THE LOW/MID TEENS ACROSS THE NORTHEAST.
MODELS REMAIN CONSISTENT WITH THE DRIER AND MORE STABLE AIRMASS TO
REMAIN OVER MOST OF THE FORECAST AREA ON SATURDAY AS THE UPPER HIGH
CENTERS ITSELF OVER SOUTHERN NM. THE BEST WETTING RAIN POTENTIAL
WILL BE FOUND ACROSS THE NORTHWEST THIRD OR SO. THE MAIN MONSOONAL
PLUME WILL REMAIN OVER ARIZONA. NEAR RECORD HIGH TEMPERATURES ONCE
AGAIN POSSIBLE ACROSS THE NORTHEAST WITH ABOVE NORMAL TEMPERATURES
AREAWIDE DURING THE AFTERNOON. EXPECTING SOME TEEN HUMIDITY VALUES
ONCE AGAIN ACROSS THE NORTHEAST AND EAST CENTRAL AREAS. THIS WILL
ADD TO THE CURING GRASS PROCESS ACROSS THE EAST. A FEW SOUTHERLY
BREEZES...SIMILAR TO TODAY WILL BE FOUND ACROSS THE EAST.
THE UPPER HIGH IS EXPECTED TO WEAKEN SLIGHTLY AND MOVE NORTHWARD
SUNDAY INTO MONDAY. MODELS CONTINUE TO SHOW A MODERATELY STRONG BACK
DOOR COLD FRONT UNDERCUTTING THIS HIGH FROM THE EAST AND PUSHING
HIGHER SURFACE MOISTURE WESTWARD. WETTING RAINFALL COVERAGE SHOULD
INCREASE ACCORDINGLY...STARTING ACROSS THE NORTHEAST HALF ON SUNDAY
AND SPREADING INTO CENTRAL AND EVEN SOME WESTERN AREAS ON MONDAY.
MODELS STILL DIFFER A BIT ON THE RAINFALL COVERAGE ACROSS THE
EASTERN PLAINS ON MONDAY. SUSPECT IT WILL BE TOO STABLE THERE FOR
SIGNIFICANT ACTION BUT REALLY DEPENDENT ON THE STRENGTH OF THE BACK
DOOR COLD FRONT. IF IT COMES IN WEAKER THEN ALL BETS ARE OFF. EITHER
WAY...THE EASTERN PLAINS HAVE SOME POTENTIAL FOR WETTING RAIN AND
WOULD HELP EASE THE DRYING CONDITIONS THERE. GAP WINDS SHOULD
ENERGIZE ALONG THE CENTRAL MOUNTAINS SUNDAY NIGHT. HUMIDITY VALUES
WILL GO UP AREAWIDE WITH AN ACCOMPANYING COOLING EFFECT.
BASED ON THE LONGER RANGE MODELS...THE AREA SHOULD EXPERIENCE SOME
SORT OF RECYCLING MODE TUESDAY THROUGH THE END OF THE WEEK. DURING
THIS PERIOD...THE UPPER HIGH WOULD STRENGTHEN SLIGHTLY AND SLIDE A
LITTLE FURTHER TO THE NORTH. DRIER AND MORE STABLE AIR WOULD SLIDE
UNDERNEATH IT AND LOWER WETTING RAIN CHANCES. WILL CONTINUE TO
MONITOR MODEL TRENDS ON THIS BUT STARTING TO SEE RUN TO RUN
CONSISTENCY FOR THE DRIER SCENARIO AFTER MONDAY. TEMPERATURES WOULD WARM
AND HUMIDITY VALUES WOULD LOWER SOME AS A RESULT. VENTILATION RATES
WOULD VARY ACROSS THE AREA. READINGS APPEAR IN THE GRIDS AS BEING
THE LOWEST ON TUESDAY AND WEDNESDAY BUT SOME IMPROVEMENT EXPECTED AS
THE UPPER HIGH MIGRATES NORTHWARD DURING THE LATTER HALF OF THE
WEEK. 50
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS RALEIGH NC
305 AM EDT SAT AUG 31 2013
.SYNOPSIS...
A WARM MOIST SOUTHERLY FLOW WILL PERSIST THROUGH THE WEEKEND. A SLOW
MOVING COLD FRONT WILL APPROACH THE REGION ON MONDAY AND THEN PUSH
THROUGH THE AREA ON TUESDAY. HIGH PRESSURE WILL MOVE INTO THE REGION
ON WEDNESDAY AND LINGER ON THURSDAY. ANOTHER COLD FRONT WILL CROSS
THE REGION ON FRIDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 250 AM SATURDAY...
STILL LOOKS LIKE A FEW SHOWERS/STORMS OVER THE WRN/SRN PORTIONS OF
THE FORECAST AREA LATE TODAY... WHILE ERN SECTIONS SHOULD REMAIN
DRY. LATEST SURFACE MAP SHOWS THE WEAK OFFSHORE-CENTERED SURFACE
HIGH EXTENDING WESTWARD OVER NC... WHILE A COLD FRONT SITS WELL TO
OUR NW ACROSS THE LOWER GREAT LAKES. A PROMINENT BUT WEAKENING MID
LEVEL SHORTWAVE HAS DROPPED SE OVER THE ST LAWRENCE VALLEY/SRN MI
OVER THE LAST FEW HOURS AND SHOULD CONTINUE TO TRACK SE TOWARD THE
OH VALLEY AND CENTRAL APPALACHIANS THIS MORNING... BEFORE SHIFTING
EASTWARD ACROSS THE MIDATLANTIC REGION LATER TODAY AND TONIGHT. MID
LEVEL FLOW GETS MUCH WEAKER AS FAR SOUTH AS NC AND MUCH OF THE
BETTER DPVA SHIFTS BY WELL TO OUR NORTH... BUT THE APPROACH OF ANY
RESIDUAL OUTFLOW EMANATING FROM THE OH VALLEY CONVECTION WILL BE
MOVING INTO WRN NC LATE TODAY INTO AN AREA OF MODERATE INSTABILITY
(FORECAST MLCAPE OVER FAR WRN PIEDMONT OF 1000-1500 J/KG)... WHILE
NEAR-NORMAL PW VALUES INCREASE QUICKLY TODAY TO 1.8-2.0 INCHES...
WITH GOOD HEATING EXPECTED AND INCREASING 850 MB THETA-E OVER WRN
NC. WHILE THE ERN CWA SHOULD REMAIN FAIRLY STABLE TODAY WITH A LATER
INCREASE IN MOISTURE... MODEL OUTPUT (INCLUDING CONVECTION-ALLOWING
MODELS) AND EXTRAPOLATION OF UPSTREAM FEATURES WOULD CERTAINLY
SUPPORT 20-40% COVERAGE OF STORMS LATE TODAY THROUGH MID EVENING
OVER THE WRN/SRN PIEDMONT MAINLY WEST OF THE TRIANGLE. WEAK ELEVATED
INSTABILITY AROUND 500-600 J/KG PERSISTS OVER THE PIEDMONT
OVERNIGHT... WHICH IN CONJUNCTION WITH THE ABOVE-NORMAL PW VALUES
WARRANTS A MENTION OF ISOLATED SHOWERS LINGERING OVERNIGHT. DEEP
LAYER SHEAR REMAINS QUITE WEAK AND FORECAST SOUNDINGS DO NOT SUGGEST
A DOWNBURST WIND POTENTIAL... SO DO NOT EXPECT ANY STRONG OR SEVERE
STORMS. HIGHS 85-90 AND LOWS 67-71. -GIH
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
AS OF 305 AM SATURDAY...
SHOWER/STORM CHANCES AND COVERAGE APPEAR TO RISE FOR SUNDAY/SUNDAY
NIGHT... AS ENERGY FROM CONVECTION NOW OVER THE MIDWEST ALONG WITH A
STRONGER WAVE DROPPING THROUGH SW/S-CENTRAL CANADA THIS MORNING
HELPS TO SUBSTANTIALLY DEEPEN THE EASTERN CONUS MEAN TROUGH. DEEP
MOISTURE PERSISTS OVER CENTRAL NC WITH PREDICTED PW VALUES NEAR 2.0
INCHES... WELL ABOVE NORMAL... WITH STRENGTHENING LOW LEVEL MOISTURE
TRANSPORT. MODELS INDICATE INCREASING ASCENT AND MOISTURE FLUX
THROUGH THE COLUMN... AND IMPROVING INSTABILITY (MLCAPE OF 1000-2000
J/KG AREAWIDE WITH N-CAPE NEAR 0.15) WITH AT LEAST WEAK DPVA AND
INCREASINGLY CYCLONIC FLOW ALOFT DOES SUPPORT SCATTERED SHOWERS AND
STORMS OVER ALL OF CENTRAL NC. DEEP LAYER SHEAR REMAINS POOR AT 15
KTS OR LESS... SO DO NOT EXPECT A LOT OF STRONG AND/OR ORGANIZED
CONVECTION... BUT COVERAGE SHOULD BE A BIT BETTER IN THE NW WHERE
THE BULK SHEAR WILL BE MAXIMIZED. HIGHS 86-91. LOWS 68-72 WITH
GRADUALLY DECREASING SHOWER/STORM CHANCES WITH LOSS OF HEATING. -GIH
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 255 AM SATURDAY...
THE LONG TERM PERIOD OF THE FORECAST FEATURES A PERSISTENT RIDGE OF
HIGH PRESSURE ACROSS THE SOUTHERN ROCKIES AND AN EASTERN U.S. TROUGH
THAT INITIALLY AMPLIFIES EARLY IN THE WORK WEEK AND THEN DEAMPLIFIES
TOWARD THE END OF THE PERIOD.
ON MONDAY A COUPLE OF SHORT WAVE TROUGHS IN SERIES OF DISTURBANCES
MOVING THROUGH THE DEEPENING EASTERN U.S. TROUGH WILL MOVE ACROSS
THE REGION. THE AIR MASS ACROSS CENTRAL NC WILL BE MOIST WITH
PRECIPITABLE WATER VALUES JUST UNDER 2.0 INCHES. THE AIRMASS WILL
ALSO BE WEAKLY TO MODERATELY UNSTABLE. THIS SHOULD SUPPORT FAIRLY
GOOD CHANCES AND COVERAGE OF PRECIPITATION ON MONDAY AND MONDAY
NIGHT. WHILE CONVECTIVE ORGANIZATION IS LIKELY TO BE LIMITED GIVEN
BULK SHEAR VALUES IN THE 15-20KT RANGE...WEAK TO MODERATE
INSTABILITY AND WEAK FLOW WILL SUPPORT THE POTENTIAL FOR SLOW
MOVING THUNDERSTORMS WITH HEAVY RAIN AND POTENTIALLY GUSTY WINDS.
NAM/GFS GUIDANCE DIFFER ON MONDAY MAX TEMPERATURES BY 3-4 DEGREES IN
MOST LOCATIONS WITH THE GFS WARMER THAN THE NAM WHICH IS NOT
SURPRISING AS THE GFS LOW LEVEL THICKNESS VALUES ON MONDAY THAT ARE
10-15M LARGER. NOT READY TO JUMP ON THE LIKELY OVERDONE TEMPS FROM
THE GFS GIVEN CLOUDINESS AND POTENTIAL FOR PRECIPITATION AND WILL
FORECAST HIGHS IN THE 88-92 RANGE. IT WILL BE WARM AND MUGGY MONDAY
NIGHT WITH LOWS ONLY IN THE 69-73 RANGE.
ANOTHER SHORT WAVE TROUGH...THIS WAS ASSOCIATED WITH THE SURFACE
COLD FRONT WILL MOVE ACROSS OUR REGION TUESDAY AFTERNOON AND
EVENING. GUIDANCE IS BEGINNING TO SHOW A WEAK SURFACE WAVE MAY
DEVELOP ACROSS CENTRAL NC ON THE FRONT TUESDAY AFTERNOON AND
EVENING. EXPECT FAIRLY GOOD COVERAGE OF SHOWERS AND THUNDERSTORMS ON
TUESDAY WITH THE BEST COVERAGE EXPECTED ACROSS THE EASTERN PIEDMONT
AND COASTAL PLAIN AHEAD OF THE SURFACE WAVE AND IN A REGION OF
GREATER INSTABILITY. IT WILL BE A LITTLE COOLER ON TUESDAY WITH
HIGHS RANGING FROM THE MID 80S ACROSS THE WESTERN PIEDMONT TO THE
UPPER 80S ACROSS THE COASTAL PLAIN. LOWS TUESDAY NIGHT WILL RANGE
FROM THE LOW 60S ACROSS THE NORTHWEST PIEDMONT TO THE UPPER 60S IN
THE SOUTHERN COASTAL PLAIN.
THE FRONT WILL CONTINUE TO SHIFT SOUTH OF CENTRAL NC ON WEDNESDAY
BUT A FEW SHOWERS MAY LINGER INTO EARLY WEDNESDAY ACROSS THE
SOUTHERN COASTAL PLAIN AND SANDHILLS. OTHERWISE HIGH PRESSURE WILL
BUILD INTO THE REGION ON WEDNESDAY AND THURSDAY WITH GENERALLY FAIR
WEATHER AND SEASONABLE TEMPERATURES. A COLD FRONT WILL PUSH SOUTH
ACROSS THE MID ATLANTIC LATE THURSDAY AND EARLY FRIDAY BRINGING
ADDITIONAL CLOUDINESS AND EVEN COOLER TEMPERATURES. PRECIPITATION
CHANCES APPEAR LIMITED ACROSS CENTRAL NC WITH THIS FEATURE. HIGH
TEMPERATURES WILL RANGE IN THE LOWER TO MID 80S WITH FRIDAY BEING
THE COOLEST DAY. MORNING LOWS SHOULD RANGE IN THE LOWER TO MID 60S.
-BLAES
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 1245 AM SATURDAY...
ADVERSE AVIATION CONDITIONS IN FOG ARE EXPECTED AT FAY/RWI AND
POTENTIALLY RDU EARLY THIS MORNING (INT/GSO SHOULD REMAIN MOSTLY
VFR). THE NARROW WEAK SURFACE RIDGE CONTINUES TO EXTEND FROM
OFFSHORE WESTWARD ACROSS NC... RESULTING IN VERY LIGHT MAINLY
SOUTHERLY BREEZE. WITH THE LACK OF HIGHER CLOUDS FACILITATING
RADIATIONAL COOLING AND LOW LEVEL DECOUPLING... WINDS SHOULD BECOME
CALM OR NEARLY CALM. THE HRRR (AMONG OTHER MODELS) FAVORS IFR FOG
FORMING NEAR FAY/RWI AFTER 09Z AND POTENTIALLY EXPANDING TOWARD RDU
AFTER 11Z. THIS AGREES WELL WITH STATISTICAL GUIDANCE AS WELL AS
PERSISTENCE. WILL FAVOR FOG OVER STRATUS AT RWI/FAY/RDU GIVEN THAT
WINDS HAVE ALREADY DIMINISHED OVER MUCH OF THE AREA. THESE IFR
CONDITIONS ARE EXPECTED TO MIX OUT TO VFR BY 13Z-14Z. VFR CONDITIONS
WILL THEN DOMINATE ALL SITES THROUGH THE END OF THE TAF VALID PERIOD
(06Z EARLY SUNDAY MORNING)... ALTHOUGH INT/GSO WILL SEE A RISK OF
SCATTERED STORMS PRODUCING BRIEF SUB-VFR CONDITIONS AND A FEW WIND
GUSTS BETWEEN 21Z AND 03Z THIS AFTERNOON/EVENING... AS AN UPPER
LEVEL DISTURBANCE APPROACHES FROM THE NW.
LOOKING BEYOND 06Z EARLY SUNDAY MORNING... THERE IS ANOTHER CHANCE
OF SHALLOW PATCHY FOG 09Z-13Z SUNDAY MORNING AS HUMIDITY STEADILY
INCREASES WITH LIGHT SW FLOW... BUT THE CHANCE IS LOWER THAN IN PAST
COUPLE OF DAYS AS WE`LL SEE MORE MID/HIGH CLOUDS ROLLING IN.
OTHERWISE... VFR CONDITIONS WILL PREVAIL THROUGH THIS PERIOD... BUT
BETTER SHOWER/STORM COVERAGE IS EXPECTED ACROSS CENTRAL NC SUNDAY
AND MONDAY AFTERNOONS/EARLY EVENING AS A LOW PRESSURE TROUGH ALOFT
STRENGTHENS OVER THE EASTERN U.S. THESE STORMS MAY PRODUCE A PERIOD
OF SUB-VFR CONDITIONS AND GUSTY WINDS. STORM CHANCE COULD LINGER
INTO TUESDAY IN THE EAST... THEN COLD FRONT PASSAGE BY TUESDAY NIGHT
SHOULD BRING VFR CONDITIONS AND DRY WEATHER FOR WEDNESDAY. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...BLAES
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
255 AM EDT SAT AUG 31 2013
.SYNOPSIS...
A WARM MOIST SOUTHERLY FLOW WILL PERSIST THROUGH THE WEEKEND. A SLOW
MOVING COLD FRONT WILL APPROACH THE REGION ON MONDAY AND THEN PUSH
THROUGH THE AREA ON TUESDAY. HIGH PRESSURE WILL MOVE INTO THE REGION
ON WEDNESDAY AND LINGER ON THURSDAY. ANOTHER COLD FRONT WILL CROSS
THE REGION ON FRIDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 250 AM SATURDAY...
STILL LOOKS LIKE A FEW SHOWERS/STORMS OVER THE WRN/SRN PORTIONS OF
THE FORECAST AREA LATE TODAY... WHILE ERN SECTIONS SHOULD REMAIN
DRY. LATEST SURFACE MAP SHOWS THE WEAK OFFSHORE-CENTERED SURFACE
HIGH EXTENDING WESTWARD OVER NC... WHILE A COLD FRONT SITS WELL TO
OUR NW ACROSS THE LOWER GREAT LAKES. A PROMINENT BUT WEAKENING MID
LEVEL SHORTWAVE HAS DROPPED SE OVER THE ST LAWRENCE VALLEY/SRN MI
OVER THE LAST FEW HOURS AND SHOULD CONTINUE TO TRACK SE TOWARD THE
OH VALLEY AND CENTRAL APPALACHIANS THIS MORNING... BEFORE SHIFTING
EASTWARD ACROSS THE MIDATLANTIC REGION LATER TODAY AND TONIGHT. MID
LEVEL FLOW GETS MUCH WEAKER AS FAR SOUTH AS NC AND MUCH OF THE
BETTER DPVA SHIFTS BY WELL TO OUR NORTH... BUT THE APPROACH OF ANY
RESIDUAL OUTFLOW EMANATING FROM THE OH VALLEY CONVECTION WILL BE
MOVING INTO WRN NC LATE TODAY INTO AN AREA OF MODERATE INSTABILITY
(FORECAST MLCAPE OVER FAR WRN PIEDMONT OF 1000-1500 J/KG)... WHILE
NEAR-NORMAL PW VALUES INCREASE QUICKLY TODAY TO 1.8-2.0 INCHES...
WITH GOOD HEATING EXPECTED AND INCREASING 850 MB THETA-E OVER WRN
NC. WHILE THE ERN CWA SHOULD REMAIN FAIRLY STABLE TODAY WITH A LATER
INCREASE IN MOISTURE... MODEL OUTPUT (INCLUDING CONVECTION-ALLOWING
MODELS) AND EXTRAPOLATION OF UPSTREAM FEATURES WOULD CERTAINLY
SUPPORT 20-40% COVERAGE OF STORMS LATE TODAY THROUGH MID EVENING
OVER THE WRN/SRN PIEDMONT MAINLY WEST OF THE TRIANGLE. WEAK ELEVATED
INSTABILITY AROUND 500-600 J/KG PERSISTS OVER THE PIEDMONT
OVERNIGHT... WHICH IN CONJUNCTION WITH THE ABOVE-NORMAL PW VALUES
WARRANTS A MENTION OF ISOLATED SHOWERS LINGERING OVERNIGHT. DEEP
LAYER SHEAR REMAINS QUITE WEAK AND FORECAST SOUNDINGS DO NOT SUGGEST
A DOWNBURST WIND POTENTIAL... SO DO NOT EXPECT ANY STRONG OR SEVERE
STORMS. HIGHS 85-90 AND LOWS 67-71. -GIH
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
AS OF 315 PM FRIDAY...
TO BE UPDATED SHORTLY.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 255 AM SATURDAY...
THE LONG TERM PERIOD OF THE FORECAST FEATURES A PERSISTENT RIDGE OF
HIGH PRESSURE ACROSS THE SOUTHERN ROCKIES AND AN EASTERN U.S. TROUGH
THAT INITIALLY AMPLIFIES EARLY IN THE WORK WEEK AND THEN DEAMPLIFIES
TOWARD THE END OF THE PERIOD.
ON MONDAY A COUPLE OF SHORT WAVE TROUGHS IN SERIES OF DISTURBANCES
MOVING THROUGH THE DEEPENING EASTERN U.S. TROUGH WILL MOVE ACROSS
THE REGION. THE AIR MASS ACROSS CENTRAL NC WILL BE MOIST WITH
PRECIPITABLE WATER VALUES JUST UNDER 2.0 INCHES. THE AIRMASS WILL
ALSO BE WEAKLY TO MODERATELY UNSTABLE. THIS SHOULD SUPPORT FAIRLY
GOOD CHANCES AND COVERAGE OF PRECIPITATION ON MONDAY AND MONDAY
NIGHT. WHILE CONVECTIVE ORGANIZATION IS LIKELY TO BE LIMITED GIVEN
BULK SHEAR VALUES IN THE 15-20KT RANGE...WEAK TO MODERATE
INSTABILITY AND WEAK FLOW WILL SUPPORT THE POTENTIAL FOR SLOW
MOVING THUNDERSTORMS WITH HEAVY RAIN AND POTENTIALLY GUSTY WINDS.
NAM/GFS GUIDANCE DIFFER ON MONDAY MAX TEMPERATURES BY 3-4 DEGREES IN
MOST LOCATIONS WITH THE GFS WARMER THAN THE NAM WHICH IS NOT
SURPRISING AS THE GFS LOW LEVEL THICKNESS VALUES ON MONDAY THAT ARE
10-15M LARGER. NOT READY TO JUMP ON THE LIKELY OVERDONE TEMPS FROM
THE GFS GIVEN CLOUDINESS AND POTENTIAL FOR PRECIPITATION AND WILL
FORECAST HIGHS IN THE 88-92 RANGE. IT WILL BE WARM AND MUGGY MONDAY
NIGHT WITH LOWS ONLY IN THE 69-73 RANGE.
ANOTHER SHORT WAVE TROUGH...THIS WAS ASSOCIATED WITH THE SURFACE
COLD FRONT WILL MOVE ACROSS OUR REGION TUESDAY AFTERNOON AND
EVENING. GUIDANCE IS BEGINNING TO SHOW A WEAK SURFACE WAVE MAY
DEVELOP ACROSS CENTRAL NC ON THE FRONT TUESDAY AFTERNOON AND
EVENING. EXPECT FAIRLY GOOD COVERAGE OF SHOWERS AND THUNDERSTORMS ON
TUESDAY WITH THE BEST COVERAGE EXPECTED ACROSS THE EASTERN PIEDMONT
AND COASTAL PLAIN AHEAD OF THE SURFACE WAVE AND IN A REGION OF
GREATER INSTABILITY. IT WILL BE A LITTLE COOLER ON TUESDAY WITH
HIGHS RANGING FROM THE MID 80S ACROSS THE WESTERN PIEDMONT TO THE
UPPER 80S ACROSS THE COASTAL PLAIN. LOWS TUESDAY NIGHT WILL RANGE
FROM THE LOW 60S ACROSS THE NORTHWEST PIEDMONT TO THE UPPER 60S IN
THE SOUTHERN COASTAL PLAIN.
THE FRONT WILL CONTINUE TO SHIFT SOUTH OF CENTRAL NC ON WEDNESDAY
BUT A FEW SHOWERS MAY LINGER INTO EARLY WEDNESDAY ACROSS THE
SOUTHERN COASTAL PLAIN AND SANDHILLS. OTHERWISE HIGH PRESSURE WILL
BUILD INTO THE REGION ON WEDNESDAY AND THURSDAY WITH GENERALLY FAIR
WEATHER AND SEASONABLE TEMPERATURES. A COLD FRONT WILL PUSH SOUTH
ACROSS THE MID ATLANTIC LATE THURSDAY AND EARLY FRIDAY BRINGING
ADDITIONAL CLOUDINESS AND EVEN COOLER TEMPERATURES. PRECIPITATION
CHANCES APPEAR LIMITED ACROSS CENTRAL NC WITH THIS FEATURE. HIGH
TEMPERATURES WILL RANGE IN THE LOWER TO MID 80S WITH FRIDAY BEING
THE COOLEST DAY. MORNING LOWS SHOULD RANGE IN THE LOWER TO MID 60S.
-BLAES
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 1245 AM SATURDAY...
ADVERSE AVIATION CONDITIONS IN FOG ARE EXPECTED AT FAY/RWI AND
POTENTIALLY RDU EARLY THIS MORNING (INT/GSO SHOULD REMAIN MOSTLY
VFR). THE NARROW WEAK SURFACE RIDGE CONTINUES TO EXTEND FROM
OFFSHORE WESTWARD ACROSS NC... RESULTING IN VERY LIGHT MAINLY
SOUTHERLY BREEZE. WITH THE LACK OF HIGHER CLOUDS FACILITATING
RADIATIONAL COOLING AND LOW LEVEL DECOUPLING... WINDS SHOULD BECOME
CALM OR NEARLY CALM. THE HRRR (AMONG OTHER MODELS) FAVORS IFR FOG
FORMING NEAR FAY/RWI AFTER 09Z AND POTENTIALLY EXPANDING TOWARD RDU
AFTER 11Z. THIS AGREES WELL WITH STATISTICAL GUIDANCE AS WELL AS
PERSISTENCE. WILL FAVOR FOG OVER STRATUS AT RWI/FAY/RDU GIVEN THAT
WINDS HAVE ALREADY DIMINISHED OVER MUCH OF THE AREA. THESE IFR
CONDITIONS ARE EXPECTED TO MIX OUT TO VFR BY 13Z-14Z. VFR CONDITIONS
WILL THEN DOMINATE ALL SITES THROUGH THE END OF THE TAF VALID PERIOD
(06Z EARLY SUNDAY MORNING)... ALTHOUGH INT/GSO WILL SEE A RISK OF
SCATTERED STORMS PRODUCING BRIEF SUB-VFR CONDITIONS AND A FEW WIND
GUSTS BETWEEN 21Z AND 03Z THIS AFTERNOON/EVENING... AS AN UPPER
LEVEL DISTURBANCE APPROACHES FROM THE NW.
LOOKING BEYOND 06Z EARLY SUNDAY MORNING... THERE IS ANOTHER CHANCE
OF SHALLOW PATCHY FOG 09Z-13Z SUNDAY MORNING AS HUMIDITY STEADILY
INCREASES WITH LIGHT SW FLOW... BUT THE CHANCE IS LOWER THAN IN PAST
COUPLE OF DAYS AS WE`LL SEE MORE MID/HIGH CLOUDS ROLLING IN.
OTHERWISE... VFR CONDITIONS WILL PREVAIL THROUGH THIS PERIOD... BUT
BETTER SHOWER/STORM COVERAGE IS EXPECTED ACROSS CENTRAL NC SUNDAY
AND MONDAY AFTERNOONS/EARLY EVENING AS A LOW PRESSURE TROUGH ALOFT
STRENGTHENS OVER THE EASTERN U.S. THESE STORMS MAY PRODUCE A PERIOD
OF SUB-VFR CONDITIONS AND GUSTY WINDS. STORM CHANCE COULD LINGER
INTO TUESDAY IN THE EAST... THEN COLD FRONT PASSAGE BY TUESDAY NIGHT
SHOULD BRING VFR CONDITIONS AND DRY WEATHER FOR WEDNESDAY. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...HARTFIELD
SHORT TERM...VINCENT
LONG TERM...BLAES
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
250 AM EDT SAT AUG 31 2013
.SYNOPSIS...
A WARM MOIST SOUTHERLY FLOW WILL PERSIST THROUGH THE WEEKEND. A SLOW
MOVING COLD FRONT WILL APPROACH THE REGION ON MONDAY AND THEN PUSH
THROUGH THE AREA ON TUESDAY. HIGH PRESSURE WILL MOVE INTO THE REGION
ON WEDNESDAY AND LINGER ON THURSDAY. ANOTHER COLD FRONT WILL CROSS
THE REGION ON FRIDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 250 AM SATURDAY...
STILL LOOKS LIKE A FEW SHOWERS/STORMS OVER THE WRN/SRN PORTIONS OF
THE FORECAST AREA LATE TODAY... WHILE ERN SECTIONS SHOULD REMAIN
DRY. LATEST SURFACE MAP SHOWS THE WEAK OFFSHORE-CENTERED SURFACE
HIGH EXTENDING WESTWARD OVER NC... WHILE A COLD FRONT SITS WELL TO
OUR NW ACROSS THE LOWER GREAT LAKES. A PROMINENT BUT WEAKENING MID
LEVEL SHORTWAVE HAS DROPPED SE OVER THE ST LAWRENCE VALLEY/SRN MI
OVER THE LAST FEW HOURS AND SHOULD CONTINUE TO TRACK SE TOWARD THE
OH VALLEY AND CENTRAL APPALACHIANS THIS MORNING... BEFORE SHIFTING
EASTWARD ACROSS THE MIDATLANTIC REGION LATER TODAY AND TONIGHT. MID
LEVEL FLOW GETS MUCH WEAKER AS FAR SOUTH AS NC AND MUCH OF THE
BETTER DPVA SHIFTS BY WELL TO OUR NORTH... BUT THE APPROACH OF ANY
RESIDUAL OUTFLOW EMANATING FROM THE OH VALLEY CONVECTION WILL BE
MOVING INTO WRN NC LATE TODAY INTO AN AREA OF MODERATE INSTABILITY
(FORECAST MLCAPE OVER FAR WRN PIEDMONT OF 1000-1500 J/KG)... WHILE
NEAR-NORMAL PW VALUES INCREASE QUICKLY TODAY TO 1.8-2.0 INCHES...
WITH GOOD HEATING EXPECTED AND INCREASING 850 MB THETA-E OVER WRN
NC. WHILE THE ERN CWA SHOULD REMAIN FAIRLY STABLE TODAY WITH A LATER
INCREASE IN MOISTURE... MODEL OUTPUT (INCLUDING CONVECTION-ALLOWING
MODELS) AND EXTRAPOLATION OF UPSTREAM FEATURES WOULD CERTAINLY
SUPPORT 20-40% COVERAGE OF STORMS LATE TODAY THROUGH MID EVENING
OVER THE WRN/SRN PIEDMONT MAINLY WEST OF THE TRIANGLE. WEAK ELEVATED
INSTABILITY AROUND 500-600 J/KG PERSISTS OVER THE PIEDMONT
OVERNIGHT... WHICH IN CONJUNCTION WITH THE ABOVE-NORMAL PW VALUES
WARRANTS A MENTION OF ISOLATED SHOWERS LINGERING OVERNIGHT. DEEP
LAYER SHEAR REMAINS QUITE WEAK AND FORECAST SOUNDINGS DO NOT SUGGEST
A DOWNBURST WIND POTENTIAL... SO DO NOT EXPECT ANY STRONG OR SEVERE
STORMS. HIGHS 85-90 AND LOWS 67-71. -GIH
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
AS OF 315 PM FRIDAY...
TO BE UPDATED SHORTLY.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 230 PM FRIDAY...
DURING THE FIRST HALF OF THE LONG TERM (SUNDAY THROUGH TUESDAY)
WE`LL SEE A LONGWAVE TROUGH DEEPEN OVER THE EASTERN STATES. MOISTURE
WILL GRADUALLY INCREASE DURING THIS PERIOD GIVEN SW FLOW AHEAD OF A
COLD FRONT THATS PROGGED TO MOVE ACROSS OUR AREA LATE TUESDAY.
INDIVIDUAL SHORT WAVES EMBEDDED WITHIN THE LARGER TROUGH WILL
RESULT IN PERIODIC INCREASES IN RAIN CHANCES.
ON SUNDAY...THE FIRST OF THESE SHORT WAVES WILL APPROACH LATE IN THE
DAY...SO WILL CONTINUE FORECAST INDICATING 25-35 POPS...HIGHEST WEST
GIVEN TIMING OF THE APPROACH OF THIS WAVE. THE NEXT WAVE IS PROGGED
TO APPROACH LATE ON MONDAY AND MOVE ACROSS THE CAROLINAS MONDAY
NIGHT. THIS WAVE WILL HAVE ADDITIONAL MOISTURE TO WORK WITH...SO
LOOK FOR BETTER PRECIP CHANCES/COVERAGE LATE MONDAY AND MONDAY NIGHT
COMPARED TO THE PREVIOUS DAY. HOWEVER GIVEN LATE DAY OR NIGHT TIMING
AND 0-6KM BULK SHEAR LESS THAN 20KT...FEEL THE SEVERE THREAT WILL
REMAIN LIMITED.
THE LAST IN THIS SERIES OF SHORT WAVES...AND FINALLY THE COLD
FRONT...WILL MOVE ACROSS OUR REGION TUESDAY AFTERNOON AND EVENING.
LOOK FOR SCATTERED SHOWERS/TSTMS ALONG AND AHEAD OF THE FRONT DURING
THE AFTERNOON AND EVENING...WITH BEST CHANCES SHIFTING TO OUR
COASTAL PLAIN ZONES LATER IN THE DAY. WHILE MOISTURE AND INSTABILITY
WILL BE ADEQUATE FOR TSTMS...0-6KM SHEAR IS STILL PROGGED TO REMAIN
BELOW 30KT...SO WIDESPREAD SEVERE THUNDERSTORMS IS NOT EXPECTED
ATTM...BUT WILL CONTINUE TO MONITOR TRENDS.
HIGH PRESSURE WILL BUILD ACROSS THE AREA BEHIND THE FRONT ON
WEDNESDAY...PROVIDING FAIR AND SEASONABLE WEATHER WEDNESDAY AND
THURSDAY. A WEAK BACKDOOR COLD FRONT WILL THEN MOVE ACROSS OUR AREA
THURSDAY NIGHT INTO EARLY FRIDAY...BUT SHOULD MOVE THROUGH WITH
LITTLE OR NO PRECIP GIVEN DRY AIRMASS IN PLACE AHEAD OF THE FRONT.
TEMPS WILL REMAIN ABOVE NORMAL (HIGHS IN THE LOW 90S AND LOWS NEAR
70) SUNDAY THROUGH TUESDAY AHEAD OF THE COLD FRONT...THEN COOLING
BACK TO NEAR-NORMAL (HIGHS IN THE MID 80S AND LOWS IN THE MID 60S)
FOR THE MID TO LATTER PORTION OF THE WEEK.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 1245 AM SATURDAY...
ADVERSE AVIATION CONDITIONS IN FOG ARE EXPECTED AT FAY/RWI AND
POTENTIALLY RDU EARLY THIS MORNING (INT/GSO SHOULD REMAIN MOSTLY
VFR). THE NARROW WEAK SURFACE RIDGE CONTINUES TO EXTEND FROM
OFFSHORE WESTWARD ACROSS NC... RESULTING IN VERY LIGHT MAINLY
SOUTHERLY BREEZE. WITH THE LACK OF HIGHER CLOUDS FACILITATING
RADIATIONAL COOLING AND LOW LEVEL DECOUPLING... WINDS SHOULD BECOME
CALM OR NEARLY CALM. THE HRRR (AMONG OTHER MODELS) FAVORS IFR FOG
FORMING NEAR FAY/RWI AFTER 09Z AND POTENTIALLY EXPANDING TOWARD RDU
AFTER 11Z. THIS AGREES WELL WITH STATISTICAL GUIDANCE AS WELL AS
PERSISTENCE. WILL FAVOR FOG OVER STRATUS AT RWI/FAY/RDU GIVEN THAT
WINDS HAVE ALREADY DIMINISHED OVER MUCH OF THE AREA. THESE IFR
CONDITIONS ARE EXPECTED TO MIX OUT TO VFR BY 13Z-14Z. VFR CONDITIONS
WILL THEN DOMINATE ALL SITES THROUGH THE END OF THE TAF VALID PERIOD
(06Z EARLY SUNDAY MORNING)... ALTHOUGH INT/GSO WILL SEE A RISK OF
SCATTERED STORMS PRODUCING BRIEF SUB-VFR CONDITIONS AND A FEW WIND
GUSTS BETWEEN 21Z AND 03Z THIS AFTERNOON/EVENING... AS AN UPPER
LEVEL DISTURBANCE APPROACHES FROM THE NW.
LOOKING BEYOND 06Z EARLY SUNDAY MORNING... THERE IS ANOTHER CHANCE
OF SHALLOW PATCHY FOG 09Z-13Z SUNDAY MORNING AS HUMIDITY STEADILY
INCREASES WITH LIGHT SW FLOW... BUT THE CHANCE IS LOWER THAN IN PAST
COUPLE OF DAYS AS WE`LL SEE MORE MID/HIGH CLOUDS ROLLING IN.
OTHERWISE... VFR CONDITIONS WILL PREVAIL THROUGH THIS PERIOD... BUT
BETTER SHOWER/STORM COVERAGE IS EXPECTED ACROSS CENTRAL NC SUNDAY
AND MONDAY AFTERNOONS/EARLY EVENING AS A LOW PRESSURE TROUGH ALOFT
STRENGTHENS OVER THE EASTERN U.S. THESE STORMS MAY PRODUCE A PERIOD
OF SUB-VFR CONDITIONS AND GUSTY WINDS. STORM CHANCE COULD LINGER
INTO TUESDAY IN THE EAST... THEN COLD FRONT PASSAGE BY TUESDAY NIGHT
SHOULD BRING VFR CONDITIONS AND DRY WEATHER FOR WEDNESDAY. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...HARTFIELD
SHORT TERM...VINCENT
LONG TERM...NP
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1250 AM EDT SAT AUG 31 2013
.SYNOPSIS...
A WARM MOIST SOUTHERLY FLOW WILL PERSIST THROUGH THE WEEKEND. A SLOW
MOVING COLD FRONT WILL APPROACH THE REGION ON MONDAY AND THEN PUSH
THROUGH THE AREA ON TUESDAY. HIGH PRESSURE WILL MOVE INTO THE REGION
ON WEDNESDAY AND LINGER ON THURSDAY. ANOTHER COLD FRONT WILL CROSS
THE REGION ON FRIDAY.
&&
.NEAR TERM /OVERNIGHT/...
AS OF 1000 PM FRIDAY...
A RIDGE OF HIGH PRESSURE AT THE SURFACE AND ALOFT PROVIDING CENTRAL
NC WITH DRY AND STABLE CONDITIONS THIS EVENING. ASIDE FROM A FEW
PASSING CIRRUS...SKIES WILL REMAIN CLEAR OVERNIGHT. AS THE LOW LEVEL
AIR MASS COOLS...PATCHES OF FOG AND/OR LOW CLOUDS WILL DEVELOP. THIS
LAYER OF MOISTURE WILL REMAIN RELATIVELY THIN SO THE FOG AND/OR LOW
CLOUDS SHOULD LIFT AND DISSIPATE WITHIN AN HOUR OR TWO OF SUNRISE.
MIN TEMPS IN THE MID-UPPER 60S APPEAR ON TARGET AT THIS TIME.
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
AS OF 315 PM FRIDAY...
WEAK CYCLONIC FLOW ALOFT WILL PREVAIL ACROSS THE MID-ATLANTIC SAT
AND SAT NIGHT...BETWEEN AN H5 RIDGE UPSTREAM OVER THE CENTRAL
PLAINS/ROCKIES AND A DOWNSTREAM RIDGE OFFSHORE THE SOUTHEAST COAST.
WEAK (ALBEIT PERSISTENT) SOUTHERLY RETURN FLOW WILL RESULT IN STEADY
LOW-LEVEL MOISTENING ON SAT...WITH PWAT VALUES IN THE 1.50-2.00"
RANGE BY 00Z SUNDAY. THE DEEPEST MOISTURE IS EXPECTED OVER WESTERN
PORTIONS OF THE STATE...WITH A RELATIVELY DRIER AND WARMER MID-LEVEL
AIRMASS OVER EASTERN PORTIONS OF THE STATE IN CLOSER VICINITY TO THE
RIDGE OFFSHORE THE SOUTHEAST COAST. EXPECT SEASONAL DIURNAL
DESTABILIZATION DURING PEAK HEATING...WITH MLCAPE VALUES IN THE
1000-2000 J/KG RANGE...HIGHEST IN VICINITY OF THE HWY 1 CORRIDOR
WHERE THE MOST FAVORABLE JUXTAPOSITION OF LOW-LEVEL MOISTURE...
INSOLATION AND COOLER MID-LEVEL TEMPS ARE PROGGED. FORCING FOR
ASCENT WILL BE RATHER ANEMIC ON SAT...MOST LIKELY LIMITED TO
WEAK/SHALLOW CONVERGENCE ASSOC/W A LEE TROUGH IN THE WESTERN
PIEDMONT. THE BEST SHORTWAVE ENERGY /DPVA/ WILL MOST LIKELY REMAIN
FURTHER NORTH IN THE MID-ATLANTIC WHERE CYCLONIC FLOW ALOFT WILL BE
BETTER ESTABLISHED...THOUGH A SMALL AMPLITUDE DISTURBANCE CANNOT BE
RULED OUT DURING THE AFT/EVE HOURS. WITH THE ABOVE IN MIND...WILL
INDICATE A 20-30% CHANCE OF SHOWERS AND THUNDERSTORMS ALONG AND WEST
OF THE HIGHWAY 1 CORRIDOR...HIGHEST ACROSS THE NW PIEDMONT IN
VICINITY OF THE LEE TROUGH AND WHERE CAPPING/DRY AIR ENTRAINMENT
WILL BE LESS OF AN ISSUE THAN ACROSS EASTERN PORTIONS OF THE STATE.
EXPECT HIGHS IN THE MID TO UPPER 80S...WARMEST ALONG AND EAST OF
HIGHWAY 1 WHERE LESS CLOUD COVER IS ANTICIPATED. WILL REMOVE THE
AFOREMENTIONED CHANCES FOR CONVECTION BY MIDNIGHT GIVEN ANEMIC
FORCING COUPLED WITH NOCTURNAL STABILIZATION...WITH THE CAVEAT THAT
SMALL AMPLITUDE DISTURBANCES ALOFT (IF PRESENT) COULD PERHAPS
SUPPORT A FEW ISOLD SHOWERS OVERNIGHT GIVEN DEEP MOISTURE. LOWS SAT
NIGHT IN THE UPPER 60S TO LOWER 70S. -VINCENT
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
AS OF 230 PM FRIDAY...
DURING THE FIRST HALF OF THE LONG TERM (SUNDAY THROUGH TUESDAY)
WE`LL SEE A LONGWAVE TROUGH DEEPEN OVER THE EASTERN STATES. MOISTURE
WILL GRADUALLY INCREASE DURING THIS PERIOD GIVEN SW FLOW AHEAD OF A
COLD FRONT THATS PROGGED TO MOVE ACROSS OUR AREA LATE TUESDAY.
INDIVIDUAL SHORT WAVES EMBEDDED WITHIN THE LARGER TROUGH WILL
RESULT IN PERIODIC INCREASES IN RAIN CHANCES.
ON SUNDAY...THE FIRST OF THESE SHORT WAVES WILL APPROACH LATE IN THE
DAY...SO WILL CONTINUE FORECAST INDICATING 25-35 POPS...HIGHEST WEST
GIVEN TIMING OF THE APPROACH OF THIS WAVE. THE NEXT WAVE IS PROGGED
TO APPROACH LATE ON MONDAY AND MOVE ACROSS THE CAROLINAS MONDAY
NIGHT. THIS WAVE WILL HAVE ADDITIONAL MOISTURE TO WORK WITH...SO
LOOK FOR BETTER PRECIP CHANCES/COVERAGE LATE MONDAY AND MONDAY NIGHT
COMPARED TO THE PREVIOUS DAY. HOWEVER GIVEN LATE DAY OR NIGHT TIMING
AND 0-6KM BULK SHEAR LESS THAN 20KT...FEEL THE SEVERE THREAT WILL
REMAIN LIMITED.
THE LAST IN THIS SERIES OF SHORT WAVES...AND FINALLY THE COLD
FRONT...WILL MOVE ACROSS OUR REGION TUESDAY AFTERNOON AND EVENING.
LOOK FOR SCATTERED SHOWERS/TSTMS ALONG AND AHEAD OF THE FRONT DURING
THE AFTERNOON AND EVENING...WITH BEST CHANCES SHIFTING TO OUR
COASTAL PLAIN ZONES LATER IN THE DAY. WHILE MOISTURE AND INSTABILITY
WILL BE ADEQUATE FOR TSTMS...0-6KM SHEAR IS STILL PROGGED TO REMAIN
BELOW 30KT...SO WIDESPREAD SEVERE THUNDERSTORMS IS NOT EXPECTED
ATTM...BUT WILL CONTINUE TO MONITOR TRENDS.
HIGH PRESSURE WILL BUILD ACROSS THE AREA BEHIND THE FRONT ON
WEDNESDAY...PROVIDING FAIR AND SEASONABLE WEATHER WEDNESDAY AND
THURSDAY. A WEAK BACKDOOR COLD FRONT WILL THEN MOVE ACROSS OUR AREA
THURSDAY NIGHT INTO EARLY FRIDAY...BUT SHOULD MOVE THROUGH WITH
LITTLE OR NO PRECIP GIVEN DRY AIRMASS IN PLACE AHEAD OF THE FRONT.
TEMPS WILL REMAIN ABOVE NORMAL (HIGHS IN THE LOW 90S AND LOWS NEAR
70) SUNDAY THROUGH TUESDAY AHEAD OF THE COLD FRONT...THEN COOLING
BACK TO NEAR-NORMAL (HIGHS IN THE MID 80S AND LOWS IN THE MID 60S)
FOR THE MID TO LATTER PORTION OF THE WEEK.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 1245 AM SATURDAY...
ADVERSE AVIATION CONDITIONS IN FOG ARE EXPECTED AT FAY/RWI AND
POTENTIALLY RDU EARLY THIS MORNING (INT/GSO SHOULD REMAIN MOSTLY
VFR). THE NARROW WEAK SURFACE RIDGE CONTINUES TO EXTEND FROM
OFFSHORE WESTWARD ACROSS NC... RESULTING IN VERY LIGHT MAINLY
SOUTHERLY BREEZE. WITH THE LACK OF HIGHER CLOUDS FACILITATING
RADIATIONAL COOLING AND LOW LEVEL DECOUPLING... WINDS SHOULD BECOME
CALM OR NEARLY CALM. THE HRRR (AMONG OTHER MODELS) FAVORS IFR FOG
FORMING NEAR FAY/RWI AFTER 09Z AND POTENTIALLY EXPANDING TOWARD RDU
AFTER 11Z. THIS AGREES WELL WITH STATISTICAL GUIDANCE AS WELL AS
PERSISTENCE. WILL FAVOR FOG OVER STRATUS AT RWI/FAY/RDU GIVEN THAT
WINDS HAVE ALREADY DIMINISHED OVER MUCH OF THE AREA. THESE IFR
CONDITIONS ARE EXPECTED TO MIX OUT TO VFR BY 13Z-14Z. VFR CONDITIONS
WILL THEN DOMINATE ALL SITES THROUGH THE END OF THE TAF VALID PERIOD
(06Z EARLY SUNDAY MORNING)... ALTHOUGH INT/GSO WILL SEE A RISK OF
SCATTERED STORMS PRODUCING BRIEF SUB-VFR CONDITIONS AND A FEW WIND
GUSTS BETWEEN 21Z AND 03Z THIS AFTERNOON/EVENING... AS AN UPPER
LEVEL DISTURBANCE APPROACHES FROM THE NW.
LOOKING BEYOND 06Z EARLY SUNDAY MORNING... THERE IS ANOTHER CHANCE
OF SHALLOW PATCHY FOG 09Z-13Z SUNDAY MORNING AS HUMIDITY STEADILY
INCREASES WITH LIGHT SW FLOW... BUT THE CHANCE IS LOWER THAN IN PAST
COUPLE OF DAYS AS WE`LL SEE MORE MID/HIGH CLOUDS ROLLING IN.
OTHERWISE... VFR CONDITIONS WILL PREVAIL THROUGH THIS PERIOD... BUT
BETTER SHOWER/STORM COVERAGE IS EXPECTED ACROSS CENTRAL NC SUNDAY
AND MONDAY AFTERNOONS/EARLY EVENING AS A LOW PRESSURE TROUGH ALOFT
STRENGTHENS OVER THE EASTERN U.S. THESE STORMS MAY PRODUCE A PERIOD
OF SUB-VFR CONDITIONS AND GUSTY WINDS. STORM CHANCE COULD LINGER
INTO TUESDAY IN THE EAST... THEN COLD FRONT PASSAGE BY TUESDAY NIGHT
SHOULD BRING VFR CONDITIONS AND DRY WEATHER FOR WEDNESDAY. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...WSS
SHORT TERM...VINCENT
LONG TERM...NP
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1256 AM CDT SAT AUG 31 2013
.UPDATE...
ISSUED AT 224 AM CDT SAT AUG 31 2013
THE PRIMARY UPDATE THIS MORNING WAS TO ACCOUNT FOR CURRENT RADAR
TRENDS. THE LAST COUPLE RUNS OF THE HRRR SUGGEST THAT THE ONGOING
THUNDERSTORMS EAST OF BISMARCK. TRENDS AND MESOANALYSIS SUGGEST
THAT THE STORMS WILL REMAIN SUB-SEVERE.
THE MAIN FOCUS AFTER THUNDERSTORMS MOVE OUT WILL BE THE CHANCE FOR
A FEW THUNDERSTORMS SATURDAY AFTERNOON/EVENING BEFORE TEMPERATURES
FINALLY COOL DOWN ON SUNDAY.
UPDATE ISSUED AT 1115 PM CDT FRI AUG 30 2013
AFTER COORDINATING WITH SPC AND GIVEN THE DECREASING CONVECTIVE
TRENDS...ALLOWED THE WATCH TO EXPIRE AT 11 PM CDT. WILL CONTINUE
TO MONITOR ONGOING CONVECTION TONIGHT AND ISSUE APPROPRIATE SHORT-
FUSED WARNINGS AS NEEDED. GIVEN THE THREAT IS NOT ZERO...STILL
HIGHLIGHTED THE STRONG TO SEVERE THUNDERSTORM POTENTIAL IN THE
HWO. THE UPDATED PRODUCTS HAVE BEEN SENT.
UPDATE ISSUED AT 940 PM CDT FRI AUG 30 2013
UPDATED THE FORECAST TO REMOVE A TIER OF WESTERN COUNTIES FROM THE
SEVERE THUNDERSTORM WATCH...AND ADDED A TIER OF EASTERN COUNTIES
TO THE WATCH BASED ON CURRENT RADAR TRENDS.
LAPS ANALYSIS CONTINUES TO SHOW A DECREASING TREND IN CAPE. THE
WATCH IS STILL IS VALID UNTIL 11 PM CDT WITH LITTLE ADDITIONAL
CONVECTIVE DEVELOPMENT EXPECTED AFTER 11 PM. WILL CONTINUE TO
MONITOR TRENDS AND UPDATE THE FORECAST AS NEEDED. THE UPDATED
PRODUCTS HAVE BEEN SENT.
UPDATE ISSUED AT 707 PM CDT FRI AUG 30 2013
VISIBLE SATELLITE IMAGERY NICELY DEPICTS THE LOCATION OF A PRE-
FRONTAL TROUGH THAT IS SERVING AS A FOCUS FOR SEVERE CONVECTION.
THIS SURFACE BOUNDARY WILL CONTINUE TO PUSH EAST THROUGH THE
OVERNIGHT HOURS.
BEHIND THE FRONT...MORE STABLE AIR EXISTS OVER EXTREME WESTERN
NORTH DAKOTA. NOT EXPECTING ANY CONVECTION ALONG AND WEST OF
HIGHWAY 85 TONIGHT. AS A RESULT...CANCELLED THE SEVERE
THUNDERSTORM WATCH FOR AREAS ALONG AND WEST OF HIGHWAY 85. A
SEVERE THUNDERSTORM COULD IMPACT THE EXTREME SOUTHWESTERN PORTION
OF BOWMAN COUNTY BETWEEN 9 PM MDT AND 10 PM MDT. HOWEVER...NOT
REAL CONFIDENT THE STORM WILL HOLD TOGETHER FOR THAT LONG. STILL
CANCELLED THE WATCH FOR BOWMAN COUNTY...BUT MENTIONED THE THREAT
IN THE HWO. THE UPDATED PRODUCTS HAVE BEEN SENT.
UPDATE ISSUED AT 432 PM CDT FRI AUG 30 2013
UPDATED THE FORECAST FOR SEVERE THUNDERSTORM WATCH NUMBER 506.
CONVECTION IS ALREADY FIRING ALONG A PRE-FRONTAL TROUGH OVER
WESTERN NORTH DAKOTA. LAPS IS ANALYZING SURFACE-BASED CAPE VALUES
RANGING FROM 2000-2500 J/KG AHEAD OF THE BOUNDARY. THE ATMOSPHERE
IS PRIMED FOR SEVERE WEATHER DEVELOPMENT OVER WESTERN AND PORTIONS
OF CENTRAL NORTH DAKOTA LATER THIS AFTERNOON/EVENING. WILL
CONTINUE TO MONITOR TRENDS.
THE UPDATED PRODUCTS HAVE BEEN SENT.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 232 PM CDT FRI AUG 30 2013
THE HIGHLIGHT OF THE SHORT TERM IS SEVERE CONVECTIVE DEVELOPMENT
LATE THIS AFTERNOON AND INTO THE EVENING.
REALLY NOT MUCH CHANGE IN THINKING IN REGARDS TO THE EVOLUTION AND
ASSOCIATED THREATS WITH THE ANTICIPATED CONVECTION. THE 18 UTC
HRRR/RAP CONTINUE THE TRENDS OF INITIATING CONVECTION ALONG A
PRE-FRONTAL TROUGH FROM HETTINGER THROUGH SHERWOOD FROM BETWEEN
20-22 UTC. THIS IS IN LINE WITH THE 12 UTC NAM/GFS/GEM/WRF AND THE
00 UTC WRF AND SPC SSEO. -10 TO -30 HAIL CAPE VALUES OF 700-900 J/KG
WITH DEEP LAYER SHEAR OF 40-50 KTS SUGGESTS LARGE HAIL WILL BE A
PRIMARY THREAT...ALONG WITH DAMAGING WINDS WITH DOWNDRAFT CAPE
VALUES AOA 1000 J/KG. LOCALLY HEAVY RAINFALL IS ALSO EXPECTED WITH
PWATS NEAR 1.50 INCHES. WHILE THE TORNADIC THREAT IS LOW...ANY
SUPERCELLS THAT CAN INTERACT WITH THE TROUGH MAY PRESENT A LOCALIZED
THREAT FOR TORNADOES. STORMS ARE EXPECTED TO BE FOCUSED EAST OF
HIGHWAY 83 POST 00 UTC...SUSTAINED BY A 25 KT LOW LEVEL JET.
FOR SATURDAY...A COOLER AND NOTABLY DRIER DAY IS FORECAST ACROSS THE
AREA IN THE WAKE OF A COLD FRONT THAT WILL ENTER NORTHWEST NORTH
DAKOTA TONIGHT AND CLEAR THE SOUTHEAST PORTIONS OF THE CWA BY 18
UTC. BREEZY NORTHWEST WINDS AND DEWPOINTS DROPPING INTO THE 40S WILL
LEAD TO HIGH FIRE DANGER ACROSS THE SOUTHWEST...HOWEVER...CRITICAL
FIRE WEATHER CONDITIONS AND HEADLINES ARE NOT ANTICIPATED.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 232 PM CDT FRI AUG 30 2013
SURFACE COLD FRONT SWEEPING SOUTHEAST ACROSS THE STATE SATURDAY
MORNING/AFTERNOON SHOULD BE MOSTLY SOUTH AND EAST OF THE JAMES RIVER
VALLEY BY 00Z SUNDAY/EARLY SATURDAY EVENING. THERE STILL MAY BE SOME
LINGERING CONVECTION ACROSS PORTIONS OF THE JAMES RIVER VALLEY
AROUND 00Z...SO WILL MAINTAIN A SLIGHT CHANCE FOR THUNDERSTORMS
ACROSS LAMOURE AND DICKEY COUNTIES IN THE EVENING...DRY ALL AREAS
AFTER 06Z.
DRY...SUNNY...AND MUCH COOLER (HIGHS 70-80) FOR SUNDAY AS CANADIAN
HIGH PRESSURE BUILDS ACROSS THE NORTHERN PLAINS.
AFTER SUNDAY...WILL SEE A SLOW WARMING TREND BACK TO ABOVE NORMAL
TEMPERATURES THROUGH THE WORK WEEK AS THE UPPER RIDGE REBUILDS
ACROSS THE ROCKIES. HOT CONDITIONS POSSIBLE BY THE END OF THE WORK
WEEK/EARLY NEXT WEEKEND WITH THE 12Z GFS/EC INDICATING ANYWHERE FROM
26-30C 850MB ISOTHERMS OVER THE DAKOTAS. EXPECT MOSTLY DRY
CONDITIONS OVER NORTH DAKOTA MONDAY/MONDAY NIGHT WITH A DRY
NORTHWEST FLOW ALOFT. AFTERWARDS...WITH THE EXCEPTION OF POSSIBLE
EMBEDDED WAVES UNDERCUTTING THE RIDGE...SHOULD REMAIN MAINLY DRY
UNTIL THE END OF THE WORK WEEK/SOMETIME NEXT WEEKEND WHEN MODELS
PROJECT A STRONG COLD FRONTAL PASSAGE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1224 AM CDT SAT AUG 31 2013
VFR CONDITIONS WILL PREVAIL AT ALL AERODROMES. KJMS COULD STILL
SEE THUNDERSTORMS OVER THE NEXT FEW HOURS...BUT WILL CLEAR OUT BY
08Z.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SCHECK
SHORT TERM...AYD
LONG TERM...NH
AVIATION...SCHECK
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
128 AM EDT SAT AUG 31 2013
.SYNOPSIS...
LOW PRESSURE MOVING ACROSS THE CENTRAL GREAT LAKES WILL DRAG A
COLD FRONT ACROSS THE AREA LATE TONIGHT AND SATURDAY. THE FRONT
WILL STALL ACROSS CENTRAL OHIO SATURDAY NIGHT. A STRONGER COLD
FRONT WILL FOLLOW ON MONDAY USHERING COOLER AIR FOR MID WEEK.
&&
.NEAR TERM /UNTIL 7 AM THIS MORNING/...
THE UPPER LEVEL TROUGH CONTINUES TO MOVE TOWARD NORTHERN OHIO AND
NW PA. THIS UPPER LEVEL SUPPORT COMBINED WITH THE WEAK COLD FRONT
AND OUTFLOW BOUNDARIES HAS BEEN ENOUGH TO KEEP THE THUNDERSTORMS
GOING ACROSS SOUTHERN ONTARIO INTO MICHIGAN. THE CURRENT INCREASE
IN THE COVERAGE IS LIKELY CAUSED BY THE WARM ADVECTION AT 850 MB.
SO WE MAY SEE AN INCREASE OVER THE NEXT COUPLE HOURS ACROSS
SOUTHERN MICHIGAN INTO NW OHIO. STILL DONT BELIEVE IT WILL BE MORE
THAN SCATTERED COVERAGE AT THIS POINT.
PREVIOUS DISCUSSION...
FOR THE EARLY EVENING WILL HAVE SLIGHT CHANCE POPS NW RN PA. RADAR
HAS CONTINUED TO SHOW SMALL RAIN SHOWERS IMPACTING ERIE COUNTY FAR
NORTHEAST AND THIS COULD CONTINUE INTO THE EVENING. MOST AREAS
WILL REMAIN DRY HOWEVER. ELSEWHERE EXPECT PARTLY CLOUDY SKIES
THROUGH THE EVENING. OVERNIGHT A COLD FRONT TO OUR NORTH WILL
CONTINUE DROPPING SOUTH TOWARD THE AREA. CONVECTION IS OCCURRING
ON THE LINE WITH ONE DEVELOPING CLUSTER IN SERN WI WITH A BROKEN
LINE ACROSS NORTHERN LOWER MI. HRRR BRINGS THE WI CLUSTER INTO NRN
INDIANA BY 03Z WHILE THE ACTIVITY ACROSS NRN LOWER MI WEAKENS AND
BECOMES INCREASINGLY ISOLATED IN SERN LOWER MI AND ONTARIO JUST
NORTH OF THE LAKE. WILL BRING CHANCE POPS TO NW RN OHIO AND THE
LAKE MAINLY AFTER MIDNIGHT WITH POPS INCREASING TO CHANCE ACROSS
THE REMAINDER OF THE AREA TIER BETWEEN 06Z AND 12Z. FOLLOWED SREF
TIMING BUT GUIDANCE POPS WERE MUCH HIGHER THAN THE GFS MOS SO DID
SCALE BACK TOWARD THE GFS MOS CHANCE POPS. TEMPS AGAIN MILD WITH
LOWS IN THE UPPER 60S.
&&
.SHORT TERM /7 AM THIS MORNING THROUGH MONDAY NIGHT/...
WILL CONTINUE WITH CHANCE POPS THROUGH THE DAY AS THE WEAK COLD
FRONT SLOWLY SAGS SOUTH THROUGH THE AREA. BEST CHANCE LIKELY
SOUTHEAST COUNTIES GIVEN THAT THE FRONT WILL BE MOVING INTO THAT
AREA DURING THE AFTERNOON HOURS. SATURDAY NIGHT THE FRONT WILL
LIKELY STALL JUST TO OUR SOUTH AS LOW PRESSURE MOVES ALONG IT WEST
OF THE AREA. BOTH THE NAM AND GFS INDICATE MOISTURE INCREASES
AGAIN FROM THE SOUTHWEST AS THE FRONT WAFFLES BACK TOWARD OR INTO
THE AREA. BROUGHT CHANCE POPS BACK AFTER MIDNIGHT WEST AFTER
HAVING DRIED IT OUT FOR THE EVENING. SUNDAY THROUGH MONDAY MODELS
CONTINUE TO INCREASE MOISTURE ACROSS THE AREA AHEAD OF ANOTHER
APPROACHING COLD FRONT. THE FRONT WILL MOVE THROUGH THE AREA
MONDAY AND WITH FORECAST CAPES FROM 2-3000J/KG FOR THE AFTERNOON
TSTMS COULD GET STRONG. WILL CONTINUE TO WATCH SEVERE POTENTIAL
BUT FOR NOW WILL HAVE HIGH CHANCE TO LIKELY POPS THROUGH THE DAY.
TUESDAY NIGHT WILL ALLOW WESTERN COUNTIES TO DRY OUT AS HIGH
PRESSURE AND DRIER AIR MOVE IN. WILL KEEP CHANCE POPS FOR SHOWERS
IN THE EAST GIVEN THE MOISTURE AND THE FACT THAT COOLER AIR WILL
BE MOVING ACROSS THE LAKE. HIGHS ABOVE NORMAL MUCH OF THE PERIOD.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
HIGH PRESSURE WILL BUILD OVER THE AREA ON TUESDAY AS THE UPPER LEVEL
TROUGH AXIS SHIFTS EAST OF THE GREAT LAKES. THE AIRMASS WILL FEEL
NOTICEABLY DIFFERENT WITH DECREASING HUMIDITY AND TEMPERATURES
DROPPING BACK TO BELOW NORMAL VALUES. EXPECTING SCT-BKN CLOUDS WITH
THE GREATEST COVERAGE IN NE OH/NW PA. HIGHS WILL TOP OUT IN THE LOW
70S IN OHIO...STRUGGLING TO GET OUT OF THE 60S IN NW PA.
HIGH PRESSURE WILL BUILD SOUTHEAST ACROSS THE REGION ON
WEDNESDAY...SHIFTING TO THE OHIO VALLEY ON THURSDAY. TEMPERATURES
WILL REBOUND SEVERAL DEGREES WITH MOSTLY SUNNY SKIES AND GOOD
INSULATION ON WEDNESDAY.
12Z MODEL SUITE HAS COME INTO BETTER AGREEMENT WITH THE HANDLING OF
THE NEXT FRONT ON THURSDAY. THE 00Z ECMWF WHICH WAS FASTER AND
STRONGER WITH THE NEXT COLD FRONT HAS SLOWED DOWN WITH THE 12Z RUN
AND TRENDED TOWARDS A WEAKER FRONT. THIS IS CLOSER TO THE SOLUTION
OFFERED BY THE GFS SO WILL LEAN THE FORECAST TOWARDS JUST ANOTHER
MODEST DROP IN TEMPERATURES TOWARDS THE END OF THE WEEK INSTEAD OF
THE COLDER SOLUTION.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
SCATTERED TSRA WILL PUSH OF THE AREA OVERNIGHT AHEAD OF
APPROACHING COLD FRONT. FRONT CURRENTLY STRETCHES FROM LOW
PRESSURE OVER LAKE ONTARIO INTO EXTREME NW OH. MODELS CONTINUE TO
PUSH FRONT SOUTH OF THE LAKESHORE COUNTIES BY LATE MORNING EARLY
AFTERNOON. EXPECT WIDESPREAD MVFR PATCHY IFR WITH THE FRONT. EXPECT
TSRA TO REDEVELOP THIS AFTERNOON SOUTH OF FRONT...MAINLY SOUTH OF
A YNG TO FDY LINE.
OUTLOOK...NON VFR LIKELY INLAND LOCATIONS EACH MORNING IN PATCHY
FOG. NON VFR IN SCATTERED SHOWERS/THUNDERSTORMS SATURDAY THROUGH
MONDAY.
&&
.MARINE...
A LIGHT SOUTHWESTERLY FLOW WITH SOME DEGREE OF A LAKE BREEZE ON THE
EASTERN HALF OF THE LAKE IS IN PLACE TODAY. WINDS WILL INCREASE TO
10 TO 15 KNOTS AHEAD OF A COLD FRONT THAT WILL PUSH SOUTH ACROSS THE
LAKE LATE TONIGHT INTO SATURDAY MORNING. SCATTERED SHOWERS AND
THUNDERSTORMS ARE ALSO EXPECTED AHEAD OF THE FRONT. WINDS WILL SHIFT
TO THE NORTHWEST BEHIND THE FRONT ON SATURDAY BUT ARE NOT EXPECTED
TO BE MORE THAN 5 TO 15 KNOTS AS THE FRONT STALLS OVER CENTRAL
OHIO.
WIND WILL SHIFT AROUND TO THE SOUTH ON SUNDAY AS A WARM FRONT PUSHES
BACK NORTH OVER THE LAKE. THERE WILL BE A CHANCE OF THUNDERSTORMS
SUNDAY...INCREASING SUNDAY NIGHT INTO MONDAY AS LOW PRESSURE
APPROACHES THE GREAT LAKES FROM THE WEST. THIS SYSTEM WILL PULL A
STRONGER COLD FRONT ACROSS THE LAKE ON MONDAY WITH NORTHWESTERLY
WINDS INCREASING TO 10 TO 20 KNOTS DURING THE AFTERNOON. THE
NORTHWESTERLY FLOW WILL LEAD TO WAVES BUILDING TO 2 TO 4 FEET ON
MONDAY NIGHT AND TUESDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TK
NEAR TERM...TK/MULLEN
SHORT TERM...TK
LONG TERM...KEC
AVIATION...DJB
MARINE...KEC
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
300 AM EDT SAT AUG 31 2013
.SYNOPSIS...
HIGH PRESSURE WILL MOVE OFF TO THE SOUTHEAST OF THE REGION
THIS MORNING...WHILE A SLOW MOVING COLD FRONT SETTLES INTO THE
REGION FOR THE REMAINDER OF THE HOLIDAY WEEKEND. A SECOND COLD
FRONT IS EXPECTED TO FINALLY CLEAR THINGS OUT SOMETIME
TUESDAY...FOLLOWED BY SEVERAL DAYS OF COOLER AND DRIER CONDITIONS.
&&
.NEAR TERM /UNTIL 8 AM THIS MORNING/...
MUGGY AIR IN PLACE AND ADVANCING CLOUD COVER WILL KEEP OVERNIGHT TEMPS
VERY WARM FOR THE LAST DAY OF AUGUST. SHOWERS WEAKENING RAPIDLY AS
FCST AND SHOULD CONTINUE TO DO SO. RECENT RUC RUNS DO ALLOW FOR
SOME RAIN TO ROLL ALONG THE NRN MTS OVERNIGHT...BUT CONFIDENCE LOW
AT THIS POINT TO PUT MORE THAN CHC POPS - AND KEEP THEM WELL NORTH
OF I-80 - CONFINED TO MAINLY THE NORTHERN STRIPE OF COS.
&&
.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM SUNDAY/...
A DIFFUSE COLD FRONT IS EXPECTED TO SAG INTO THE REGION AND
BASICALLY STALL OR WASH OUT OVER THE NEXT FEW DAYS. ENSEMBLES SHOW
A RIBBON OF ANOMALOUS PWATS MOVE IN FOR SATURDAY BEFORE SOMEWHAT
DRIER AIR RETURNS FOR SATURDAY NIGHT AND SUNDAY. BOTH THE SREF AND
GEFS SHOW A HIGH PROB OF MEASURABLE RAINS...BUT QPF ON THE ORDER
OF .25" OR LESS LOOKS LIKE THE BEST BET.
SATURDAY WILL BE ANOTHER HUMID AND WARM DAY WITH HIGHS IN THE 80S
JUST ABOUT EVERYWHERE IN CENTRAL PA.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
A WEAK DISTURBANCE WILL MOVE ACROSS THE REGION SUNDAY.
THE MAIN COLD FRONT WILL MOVE ACROSS LATE MONDAY INTO
EARLY TUE AM.
DID NOT CHANGE A LOT.
DID LOWER POPS SOME FOR SATURDAY NIGHT...AS WE ARE BETWEEN
WEAK SYSTEMS.
PRIOR TO TUE...DID UP TEMPS SOME. TOOK SHOWERS OUT AFT TUE
MORNING...AS SUPPORT FOR ANY ACTIVITY IS LOST.
WED LOOKS DRY.
CHC OF SHOWERS FOR THU...WITH STRONGER FRONT. DID NOT HAVE
THUNDER IN AT THIS POINT...MOISTURE WILL BE LIMITED.
00Z 8/30 EC RUN SHOWS A STRONGER FRONT FOR THU...DID GO COLDER
THAN THE GFS FOR FRIDAY...BUT NOT REAL COLD AT THIS POINT.
WHILE THE UPPER LVL TROUGH SLOWLY LIFTS WESTWARD...STILL THINK
WE ARE IN A A WARM PERIOD OVERALL FOR THE NEXT FEW WEEKS.
ENJOY THE HOLIDAY WEEKEND.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
RADAR TRENDS INDICATE THE BAND OF CONVECTION THAT PUSHED SEWD
ACRS LAKE ERIE /ASSOCD WITH WEAK SFC LOW/FRONTAL BOUNDARY OVER SRN
ONTARIO/ IS RAPIDLY WEAKENING/DISSIPATING AS IT MOVES INLAND OVR
NW PA. BFD COULD SEE A BRIEF -SHRA PRIOR TO 12Z WITH NO LCL
RESTRICTIONS XPCTD.
SCT-BKN MID AND HIGH CLOUDS WILL SPREAD SEWD INTO THE CENTRAL AND
SERN TAFS THROUGH THE MORNING...AS THE WEAK FRONTAL SYSTEM CROSSES
THE LWR LKS. A LGT SSW SFC WIND AND INC CLOUD COVER WILL KEEP
VISBYS IN THE VFR TO MVFR RANGE...WHICH IS MORE OPTIMISTIC THAN
THE GUIDANCE. THE EXCEPTION MIGHT BE ACROSS SOUTHEAST PA...WHERE
SKIES SHOULD REMAIN MCLEAR AND WINDS MAY BECOME CALM. THE LATEST
IR SAT LOOP IS ALREADY DETECTING FOG/ST FORMING IN THIS AREA.
STILL THINK LNS HAS THE BEST SHOT AT A BRIEF PERIOD OF IFR AROUND
DAYBREAK. RADAR NOW SHOWING SOME ISOLD SHOWERS DEVELOPING ENE OF
IPT.
THE SFC LOW OVER SRN ONTARIO WILL MOVE EWD INTO UPSTATE NY
TODAY...WITH ITS TRAILING FRONTAL SYSTEM PUSHING INTO CNTRL PA.
THE FRONT SHOULD TRIGGER SCT SHOWERS AND TSTMS WITH LCL IMPACTS
PSBL DURING THE AFTN AND EVE. KEPT VCSH FOR NOW BUT MAY CHANGE TO
VCTS WITH THE NEXT SCHEDULED ISSUANCE. CONVECTION SHOULD DISSOLVE
IN THE 00-03Z TIMEFRAME AS THE BLYR COOLS AND STABILIZES. A BAND
OF MVFR CIGS SEEMS PROBABLE BEHIND THE FRONT TONIGHT OVER NW PA.
OUTLOOK...
SUN...AM LOW CIGS/FOG. SCT PM TSRA IMPACTS.
MON...AM FOG. SCT PM TSRA IMPACTS. FROPA.
TUE...MVFR CIGS WEST/VFR CNTRL AND EAST.
WED...AM FOG PSBL WEST AND CNTRL. NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO/LA CORTE
NEAR TERM...DANGELO
SHORT TERM...LA CORTE
LONG TERM...MARTIN
AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
140 AM EDT SAT AUG 31 2013
.SYNOPSIS...
HIGH PRESSURE WILL MOVE OFF TO THE SOUTHEAST OF THE REGION
THIS MORNING...WHILE A SLOW MOVING COLD FRONT SETTLES INTO THE
REGION FOR THE REMAINDER OF THE HOLIDAY WEEKEND. A SECOND COLD
FRONT IS EXPECTED TO FINALLY CLEAR THINGS OUT SOMETIME
TUESDAY...FOLLOWED BY SEVERAL DAYS OF COOLER AND DRIER CONDITIONS.
&&
.NEAR TERM /UNTIL 8 AM THIS MORNING/...
MUGGY AIR IN PLACE AND ADVANCING CLOUD COVER WILL KEEP OVERNIGHT TEMPS
VERY WARM FOR THE LAST DAY OF AUGUST. SHOWERS WEAKENING RAPIDLY AS
FCST AND SHOULD CONTINUE TO DO SO. RECENT RUC RUNS DO ALLOW FOR
SOME RAIN TO ROLL ALONG THE NRN MTS OVERNIGHT...BUT CONFIDENCE LOW
AT THIS POINT TO PUT MORE THAN CHC POPS - AND KEEP THEM WELL NORTH
OF I-80 - CONFINED TO MAINLY THE NORTHERN STRIPE OF COS.
&&
.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM SUNDAY/...
A DIFFUSE COLD FRONT IS EXPECTED TO SAG INTO THE REGION AND
BASICALLY STALL OR WASH OUT OVER THE NEXT FEW DAYS. ENSEMBLES SHOW
A RIBBON OF ANOMALOUS PWATS MOVE IN FOR SATURDAY BEFORE SOMEWHAT
DRIER AIR RETURNS FOR SATURDAY NIGHT AND SUNDAY. BOTH THE SREF AND
GEFS SHOW A HIGH PROB OF MEASURABLE RAINS...BUT QPF ON THE ORDER
OF .25" OR LESS LOOKS LIKE THE BEST BET.
SATURDAY WILL BE ANOTHER HUMID AND WARM DAY WITH HIGHS IN THE 80S
JUST ABOUT EVERYWHERE IN CENTRAL PA.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
A WEAK DISTURBANCE WILL MOVE ACROSS THE REGION SUNDAY.
THE MAIN COLD FRONT WILL MOVE ACROSS LATE MONDAY INTO
EARLY TUE AM.
DID NOT CHANGE A LOT.
DID LOWER POPS SOME FOR SATURDAY NIGHT...AS WE ARE BETWEEN
WEAK SYSTEMS.
PRIOR TO TUE...DID UP TEMPS SOME. TOOK SHOWERS OUT AFT TUE
MORNING...AS SUPPORT FOR ANY ACTIVITY IS LOST.
WED LOOKS DRY.
CHC OF SHOWERS FOR THU...WITH STRONGER FRONT. DID NOT HAVE
THUNDER IN AT THIS POINT...MOISTURE WILL BE LIMITED.
00Z 8/30 EC RUN SHOWS A STRONGER FRONT FOR THU...DID GO COLDER
THAN THE GFS FOR FRIDAY...BUT NOT REAL COLD AT THIS POINT.
WHILE THE UPPER LVL TROUGH SLOWLY LIFTS WESTWARD...STILL THINK
WE ARE IN A A WARM PERIOD OVERALL FOR THE NEXT FEW WEEKS.
ENJOY THE HOLIDAY WEEKEND.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
BAND OF SHOWERS OVR LK ERIE IS DESTINED TO DISSIPATE AS IT
PUSHES INTO NW PA OVERNIGHT...AS AIR MASS COOLS AND STABILIZES. BIGGER
AVIATION CONCERN IS THE POSSIBILITY OF FOG EARLY SAT AM ACROSS SE
PA. A LIGHT SW BREEZE AND INCREASING CLOUD COVER SHOULD PRECLUDE
SIG VSBY RESTRICTIONS FROM RADIATION FOG OVER MOST OF CENTRAL
PA...DESPITE THE MORE PESSIMISTIC MOS GUIDANCE. THE EXCEPTION
MIGHT BE ACROSS SOUTHEAST PA...WHERE SKIES SHOULD REMAIN MCLEAR
AND WINDS MAY BECOME CALM. BOTH SREF AND MDL SFC RH FIELDS SUGGEST
IFR VSBYS ARE POSSIBLE ARND DAWN AT LNS AND TO A LESSER DEGREE
MDT.
A COLD FRONT WILL PUSH SOUTHEAST INTO THE REGION ON
SATURDAY...LIKELY PRODUCING ISOLD TSRA IMPACTS DURING THE AFTN
AND EVENING HOURS.
OUTLOOK...
SUN...AM LOW CIGS/FOG...ESP W MTNS. SCT PM TSRA IMPACTS POSS...ESP
SOUTH.
MON...AM FOG POSS. SCT PM TSRA IMPACTS POSS.
TUE-WED...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO/LA CORTE
NEAR TERM...DANGELO
SHORT TERM...LA CORTE
LONG TERM...MARTIN
AVIATION...FITZGERALD
FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND SUNDAY
ISSUED AT 432 AM CDT SAT AUG 31 2013
MAIN CONCERNS THIS PERIOD ON SKY TRENDS EARLY...THEN PCPN CHANCES
WITH EXPECTED FRONTAL PASSAGE.
OVERALL NO REAL CHANGE TO FORECAST. MODELS CONTINUE TO BE IN GOOD
AGREEMENT WITH SOME MINOR TIMING DIFFERENCES WITH FRONT. GFS AND
00Z ECMWF HAD FAIRLY GOOD HANDLE ON CURRENT PCPN TRENDS SO
FOLLOWED FOR MUCH OF THIS FORECAST.
LATEST MSAS ANALYSIS SHOWS WEAK HIGH PRESSURE OVER STATE...WITH
WEAK WAVE MOVING ALONG FRONT OVER NORTHERN IL. FURTHER TO THE
WEST..COLD FRONT EXTENDS SOUTHWEST THROUGH WESTERN DAKOTAS FROM
LOW OVER LAKE WINNEPEG AREA. SATELLITE IMAGERY SHOWING LOW CLOUDS
EXPANDING WESTWARD OFF LAKE AND BAY INTO CENTRAL WI. SOME HIGH
CLOUDS AND PATCHES OF LOW CLOUDS OUT OF UPPER MI MOVING THROUGH
FAR NORTHERN WI. FOG HAS REMAINED PATCHY...MAINLY OVER NORTH
CENTRAL WI. MOVEMENT OF WAVE ALONG FRONT TO SOUTH HAS HELPED TO
MAINTAIN GRADIENT OVER EASTERN AND CENTRAL WI. HAVE BACKED OFF ON
FOG COVERAGE. HRRR CURRENTLY HANDLING LOW CLOUD COVERAGE FAIRLY
WELL WITH CLOUDS SPREADING INTO PARTS OF CENTRAL WI BY 12Z...THEN
DIMINISHING THROUGH MID TO LATE MORNING. LOWERED FEW TEMPS TO
ACCOUNT FOR CLOUDS.
MODELS CONTINUE TO FOCUS PCPN OVER CWA BETWEEN 06-18Z AS DYNAMICS
WITH UPPER WAVE AND SURFACE FRONT MOVE THROUGH STATE. EXACT COVERAGE
IN QUESTION WITH CONVECTIVE ELEMENTS...SO DID NOT MAKE SIG CHANGE
TO POP CATEGORIES ONLY SLOWING DOWN TIMING BY FEW HOURS.
INSTABILITY OVER REGION MARGINAL LIMITING SEVERE POTENTIAL.
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY
ISSUED AT 432 AM CDT SAT AUG 31 2013
MODELS CONTINUED TO GENERATE SMALL AREAS OF QPF ON SUNDAY NIGHT
WITH THE AREA STILL IN CYCLONIC FLOW BEHIND DEPARTING LOW
PRESSURE. HAVE INCLUDED CHANCE/SLIGHT CHANCE FOR SHOWERS ACROSS
MAINLY THE EASTERN AND NORTHERN PARTS OF THE AREA AS A RESULT.
DRIER CONDITIONS ARE THEN EXPECTED AS SURFACE HIGH PRESSURE MOVES
IN AND AN UPPER LEVEL RIDGE AMPLIFIES OVER THE WESTERN
CONUS...LEAVING THE AREA IN NW/WNW FLOW ALOFT. A SHORT WAVE IN THE
UPPER FLOW IS EXPECTED TO PASS WELL TO THE NORTHEAST OF THE STATE
AROUND THE MIDDLE OF THE WEEK AS A SURFACE COLD FRONT MOVES
THROUGH WISCONSIN. A DRY FRONTAL PASSAGE IS FORECAST FOR NOW SINCE
THERE WILL BE LITTLE MOISTURE AHEAD OF THE FRONT.
TEMPERATURES ARE LIKELY TO BE NEAR OR A BIT ABOVE NORMAL...EXCEPT
FOR SUNDAY NIGHT THROUGH MONDAY NIGHT IN THE WAKE OF THE APPROACHING
COLD FRONT.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1048 PM CDT FRI AUG 30 2013
HIGH PRESSURE...SOME MVFR CIGS WILL LINGER NEAR THE LAKE MICHIGAN
SHORELINE AND THE WISCONSIN/UPPER MICHIGAN BORDER AT THE BEGINNING
OF THE TAF PERIOD...BUT THINK THEY WILL STAY EAST OF GRB/ATW AND
NORTH OF RHI. LIGHT WINDS...CLEAR TO PARTLY CLOUDY SKIES AND LOW
LEVEL MOISTURE FROM RECENT RAINFALL WILL LEAD TO FOG DEVELOPMENT
OVERNIGHT. WILL CARRY IFR/LIFR CONDITIONS AT MOST OF THE TAF SITES
OVERNIGHT INTO EARLY SATURDAY. HEAVY RAINFALL OCCURRED AT RHI OVER
THE PAST DAY...AND THE SFC HIGH WILL BE CENTERED OVER NORTH
CENTRAL WI...SO DENSE FOG APPEARS LIKELY THERE. CONDITIONS WILL
PROBABLY DROP BLO AIRPORT MINIMUMS AT RHI. IMPROVING CONDITIONS AT
ALL OF THE TAF SITES CAN BE ANTICIPATED BY AROUND 14Z/SAT...WITH
SCT CUMULUS AND SOME PATCHY CIRRUS EXPECTED FOR THE REST OF THE
DAY. AN APPROACHING COLD FRONT MAY BRING SOME SHOWERS OR EVEN A
THUNDERSTORM INTO NORTH CENTRAL WISCONSIN TOWARD MIDNIGHT
SATURDAY NIGHT. FOR NOW...HAVE ONLY ADDED A PROB30 GROUP FOR
SHOWERS AT RHI.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....TE
LONG TERM......MG
AVIATION.......KIECKBUSCH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
330 AM CDT SAT AUG 31 2013
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 330 AM CDT SAT AUG 31 2013
IMMEDIATE ISSUE TO DEAL WITH EARLY THIS MORNING IS ONGOING SHOWER
AND THUNDERSTORM ACTIVITY ACROSS FAR SOUTHWEST WI INTO NORTHEAST IA.
RAIN RATES HAVE BEEN FAIRLY HEAVY WITH THESE CLUSTERS OF SHOWERS AND
THUNDERSTORMS WITH 1-3 INCHES INDICATED IN 3-HRLY DUAL POL RADAR
ESTIMATES. THESE SHOWERS AND STORMS ARE THE RESULT OF A CLOSED 925MB
CYCLONIC CIRCULATION OVER CENTRAL IA AND WIND CONVERGENCE TO THE
NORTHEAST OF THIS LOW. THIS CONVERGENCE IN TURN IS WORKING ON HIGHER
PRECIPITABLE WATER VALUES ACROSS NORTHEAST IA INTO FAR SOUTHWEST WI.
RAP SHOWS THIS LOW AND CONVERGENCE/RESULTANT SHOWERS AND
THUNDERSTORMS SLIPPING SOUTH AND EAST OF THE AREA BY DAWN.
OTHERWISE...WATER VAPOR IMAGERY AND RAP 500MB ANALYSIS SHOWING
ANOTHER FAIRLY VIGOROUS MID-LEVEL SHORTWAVE TROUGH MOVING EAST
ACROSS CENTRAL DAKOTAS/NEBRASKA. RADAR MOSAIC SHOWING A CLUSTER OF
THUNDERSTORMS ALONG THE ND/SD BORDER WHERE SURGE OF 850MB MOISTURE
TRANSPORT WAS OCCURING AHEAD OF THE MID-LEVEL WAVE. THIS WILL BE OUR
WEATHER-MAKER FOR TONIGHT INTO SUNDAY.
FOR TODAY...ONCE THE SHOWERS AND STORMS DEPART FAR SOUTHERN PORTION
OF THE AREA THIS MORNING...WEAK RIDGE OF HIGH PRESSURE WILL PROVIDE
SLIGHTLY DRIER AND COOLER CONDITIONS. WILL SEE SOME LOW CLOUDS
ALONG/SOUTH OF I-90 THIS MORNING...BUT SHOULD BURN OFF BY LATE
MORNING. WITH MOSTLY SUNNY SKIES THROUGH THE REST OF THE DAY...LOOK
FOR HIGHS IN THE 80-85 DEGREE RANGE WITH DRIER DEW POINTS IN THE
LOWER TO MIDDLE 60S.
AFOREMENTIONED MID-LEVEL WAVE/SURFACE COLD FRONT MOVES TOWARD THE
AREA TONIGHT...AND MAKING PASSAGE ACROSS THE AREA SUNDAY MORNING FOR
A DECENT SHOT AT SOME SHOWERS AND THUNDERSTORMS. MODELS ARE SHOWING
BETTER MOISTURE TRANSPORT HEADING NORTH OF THE AREA...TIED TO BETTER
FORCING OF THE MID-LEVEL WAVE AND PROXIMITY TO SURFACE LOW OVER
SOUTHERN ONTARIO CANADA. FOR THIS REASON...KEPT LIKELY/HIGHER-END
CHANCE POPS NORTH OF I-94...AND TAPERING OFF SOUTH OF THIS. BEST
CHANCES SEEM TO CENTERED IN DURING THE 06-12Z TIME FRAME. THERE MAY
BE SOME UPSCALE IN THE INTENSITY OF THE SHOWERS/THUNDERSTORMS ACROSS
THE EAST IN THE 15Z-21Z TIME FRAME AS 0-1KM MLCAPE INCREASES INTO
THE 1500-2500J/KG RANGE ALONG WITH INCREASING 0-3KM BULK SHEAR. WILL
HAVE TO KEEP AND EYE ON THIS FOR SEVERE POTENTIAL...ESPECIALLY IF
THE FRONT SLOWS SOME AND INSTABILITY IS ALLOWED TO BUILD MORE AHEAD
OF THE FRONT.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 330 AM CDT SAT AUG 31 2013
GFS/ECMWF IN GOOD AGREEMENT SUNDAY NIGHT THROUGH TUESDAY IN BRINGING
HIGH PRESSURE ACROSS THE AREA IN NORTHWEST FLOW ALOFT FOR DRIER AND
COOLER WEATHER. LOOK FOR HIGHS SUNDAY AND MONDAY IN THE 70S WITH
OVERNIGHT LOWS SUNDAY NIGHT IN THE 50S AND IN THE UPPER 40S/NEAR 50
MONDAY NIGHT. ALSO...LOOKS LIKE A GOOD CHANCE OF PATCHY/AREAS OF FOG
MONDAY NIGHT ESPECIALLY IN THE RIVER VALLEYS AS THE HIGH SETTLES
OVERHEAD.
SOME WARMING EXPECTED ON WEDNESDAY AHEAD OF A COLD FRONT DROPPING
SOUTH OUT OF CANADA WITH HIGHS TOPPING OFF IN THE UPPER 70S TO THE
LOWER 80S. MODELS SHOW THIS FRONT CONTINUING TO SINK SOUTH ACROSS
THE AREA WEDNESDAY NIGHT. THE ECMWF IS MOSTLY DRY WITH THIS FROPA
WHILE THE GFS WANTS TO CONVECT ALONG/AHEAD OF THE FRONT. HAVE
INCLUDED A SLIGHT CHANCE OF SHOWERS/THUNDERSTORMS FOR NOW FOR AREAS
ALONG/SOUTH OF I-94.
FOR THURSDAY THROUGH FRIDAY...COOLER/OVERALL DRY NORTHWEST FLOW
ALOFT WILL PREVAIL AS UPPER LEVEL RIDGING BUILDS OVER THE PLAINS.
LOOKING FOR HIGHS IN THE 70S ON THURSDAY AND IN THE UPPER 70S/LOWER
80S FRIDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1145 PM CDT FRI AUG 30 2013
THE WEAK AREA OF SURFACE HIGH PRESSURE REMAINS OFF TO THE
NORTHEAST OF THE AREA AS A SECONDARY AREA OF LOW PRESSURE HAS
FORMED ALONG THE FRONT OVER SOUTHEAST IOWA. THIS IS HELPING TO
MAINTAIN A GRADIENT WITH EAST TO NORTHEAST WINDS AROUND 5 KNOTS.
DEW POINTS CONTINUE TO DROP IN THIS NORTHEAST FLOW WITH A 14
DEGREE TEMP/DEW POINT SPREAD AT KLSE AT 03Z. CONTINUES TO LOOK
MORE AND MORE UNLIKELY THAT FOG WILL FORM OVERNIGHT AS THE THE
TEMP AND DEW POINT SHOULD CONTINUE TO CHASE EACH OTHER DOWNWARD.
HAVE REMOVED THE IFR FOG FOR BOTH SITES WHILE MAINTAINING SOME
MVFR RESTRICTIONS FOR LATE TONIGHT. THE 31.03Z RAP CONTINUES TO
SUGGEST AN MVFR CLOUD DECK ADVECTING IN FROM THE EAST BUT NOW
TAKES THIS MOISTURE A LITTLE FARTHER SOUTH THAN PREVIOUS RUNS HAD
SHOWN. MVFR CEILINGS ARE IN PLACE ACROSS SOUTHEAST WISCONSIN AND
HAVE OPTED TO LEAVE THIS POSSIBILITY IN DUE TO THE CLOSE PROXIMITY
OF THESE IN THE LOW LEVEL EAST FLOW. ONCE CONDITIONS MIX OUT
SATURDAY MORNING...VFR CONDITIONS EXPECTED FOR THE REMAINDER OF
THE PERIOD.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1145 PM CDT FRI AUG 30 2013
.UPDATE...
ISSUED AT 649 PM CDT FRI AUG 30 2013
THE COLD FRONT HAS MOVED SOUTH OF THE AREA WITH DEW POINTS SLOWLY
DROPPING INTO THE LOWER 70S BEHIND IT. THAT COMBINED WITH THE
NORMAL DIURNAL COOLING OF THE AIR TEMPERATURE HAS ALLOWED THE HEAT
INDICES TO FALL BELOW 100 FOR ALL BUT THE KOLZ AREA...AND THIS
WILL OCCUR THERE OVER THE NEXT HOUR AS WELL. WILL ALLOW THE HEAT
ADVISORY TO EXPIRE AS SCHEDULED AT 7 PM.
&&
.SHORT TERM...(TONIGHT THROUGH SATURDAY NIGHT)
ISSUED AT 331 PM CDT FRI AUG 30 2013
MAIN FORECAST CONCERNS THIS PACKAGE...LINGERING SHRA/TSRA CHANCE THIS
EVENING ACROSS THE SOUTH END OF THE FCST AREA...FOG POTENTIAL LATER
TONIGHT/EARLY SAT...SHRA/TSRA CHANCES SAT NIGHT.
18Z DATA ANALYSIS HAD THE COLD FRONT NEAR A KMTW/KDLL/KPDC/KALO
LINE...MAKING STEADY PROGRESS SOUTH/EAST. FRONT QUIET ACROSS IA/
WESTERN WI...HOWEVER LAPS SOUNDINGS SHOWING SOME 3K-4K J/KG SB CAPE
AND LITTLE IF ANY CIN NEAR THE FRONT IN THESE AREAS. DRIER AIR
BEHIND THE FRONT LAGS ABOUT 100 MILES...WITH SFC DEW POINTS
REMAINING IN THE 70-75F RANGE ACROSS THE SOUTH 1/2 OF WI AND
SOUTHEAST CORNER OF MN. LOWER LEVEL STRATO-CU CONTINUED TO SPREAD
SOUTH ACROSS WI/MN BEHIND THE FRONT...BUT WERE SLOWLY LIFTING/MIXING/
DISSIPATING WITH DIURNAL WARMING/MIXING AND ANTI-CYCLONIC FLOW/
DIVERGENCE AROUND THE WEAK HIGH BUILDING SOUTH INTO THE REGION.
NO BIG PROBLEMS NOTED WITH 30.12Z MODEL INITIALIZATIONS. SOLUTIONS
CONTINUE TO CONVERGE TOWARD A TIGHTER CONSENSUS SOLUTION FOR
TONIGHT AND THRU THE HOLIDAY WEEKEND. DPROG/DT OF 500MB HGTS AT
30.12Z SHOWED THE MODEL RUNS OF 28.12Z AND 29.12Z VERIFIED QUITE
WELL ACROSS NOAM/EASTERN PAC...ESPECIALLY ACROSS CAN/AK AND EASTERN
PAC. TREND FOR TONIGHT/SAT IS TOWARD A COMPROMISE TIMING/STRENGTH
AS THE SHORTWAVE OVER SOUTHERN BC THIS MORNING TRACKS TO SOUTHERN
MANITOBA BY 00Z SUN...THEN TO NORTH OF LK SUPERIOR AND INTO/ACROSS
THE AREA LATER SAT NIGHT. ECMWF WITH SOMEWHAT BETTER RUN-TO-RUN
CONSISTENCY THAN THE OTHERS. CHECK OF OBS VS. MODEL DATA AT 18Z
SHOWED ALL WERE REASONABLE WITH THE SFC FRONT LOCATION ACROSS THE
REGION. GFS WAS LOW WITH SFC DEW POINTS POOLED EITHER SIDE OF THE
FRONT WHILE OTHER MODELS APPEARED QUITE GOOD WITH THESE. PER
WV IMAGERY...NAM/GEM/ECMWF APPEARED BETTER THAN GFS WITH THE
SHORTWAVE OVER SOUTHERN BC. ALL MODELS WITH TOO MUCH 12Z-18Z PRECIP
NEAR THE FRONT OVER EASTERN WI INTO SOUTHWEST WI AND NEARBY AREAS.
EVEN WITH THE GFS LOOKING A LITTLE OFF AT 18Z...ITS SOLUTION BY SAT
NIGHT/SUN MORNING STILL QUITE SIMILAR TO OTHER MODELS...THUS FAVORED
THE MODEL/ENSEMBLE CONSENSUS. SHORT-TERM FCST CONFIDENCE IS GOOD
THIS CYCLE.
IN THE SHORT TERM...FRONTAL BOUNDARY ALREADY NEARING THE SOUTH END
OF THE FCST AREA AT MID-AFTERNOON AND WILL BE INTO CENTRAL IA TO
NORTHERN IL BY THIS EVENING. ANY SHRA/TSRA CHANCE LATE THIS
AFTERNOON APPEARS TIED TO THE SFC-925MB CONVERGENCE WITH THE
FRONT. WITH DEW POINTS STILL IN THE LOW TO MID 70S SOME 50 MILES
OR SO BEHIND THE FRONT...WILL EXTEND THE HEAT ADVISORY ACROSS THE
SOUTH END OF THE FCST AREA THRU 7PM/00Z. ONCE THIS PASSES...FCST
TRENDS DRY FOR TONIGHT/SAT AS THE WEAK BUT DRYING HIGH BUILDS
SOUTH INTO MN/WI/IA. STRATO-CU CLOUDS OVER MUCH OF WI/EASTERN MN
CONTINUE TO DIMINISH/BREAK UP WITH DIURNAL WARMING/MIXING THIS
AFTERNOON. LOWER LEVEL ANTI-CYCLONIC FLOW/DIVERGENCE WITH THE HIGH
SHOULD HELP DIMINISH THE CLOUDS AS WELL THIS EVENING. MODELS ALSO
SHOWING MORE 925MB DRYING OVER THE AREA THRU TONIGHT. WILL
CONTINUE TO TREND SKIES TONIGHT TOWARD CLEAR/MOSTLY CLEAR...BUT
THIS THEN POSES A PROBLEM FOR RADIATIONAL FOG DEVELOPMENT AND VERY
LOW STRATUS FORMATION IN THE VALLEYS. BOUNDARY LAYER WIND BECOME
QUITE LIGHT BY MID EVENING. THIS AND DEVELOPMENT OF THE NOCTURNAL
INVERSION LIMIT INFLUX OF DRIER BOUNDARY LAYER AIR...WITH POST-
FRONTAL SFC DEW POINTS LOOKING TO REMAIN IN THE MID/UPPER 60S THIS
EVENING...THEN FALL WITH THE TEMPS OVERNIGHT. THIS ALONG WITH
GENERALLY LIGHT WINDS THRU 850MB REMAINS FAVORABLE FOR LATE
NIGHT/EARLY MORNING FOG. PREVIOUS GRID SET CARRIED PATCHY TO AREAS
OF FOG /MORE SO IN THE RIVER VALLEYS/ IN THE 06Z-14Z TIME FRAME
TONIGHT/SAT MORNING AND THIS CONTINUES TO LOOK GOOD.
ONCE ANY FOG BURNS OFF...A MORE COMFORTABLE DAY IN STORE FOR SAT
WITH DIURNAL WARMING/DEEPER MIXING OF DRIER AIR ALOFT HELPING TO
MIX/HOLD SFC DEW POINTS IN THE 60S. HEAT INDICES SAT LOOKING TO BE
IN THE 80S...VS. THE 90S TO LOW 100S THE PAST FEW DAYS. THE HIGH
GETS QUICKLY PUSHED EAST SAT NIGHT AS THE SFC-MID LEVEL FRONT/TROUGH
APPROACH AND MOVE INTO THE AREA. SFC FRONT ALREADY NEAR A KMDZ-KLSE-
KDSM LINE BY 12Z SUN. PW VALUES INCREASE INTO THE 1.5 TO 1.75 INCH
RANGE WITH THIS TROUGH. STRONGER OF THE DYNAMICS/FORCING/LIFT WITH
THE SHORTWAVE PASS NORTH OF THE FCST AREA...BUT A TIGHTENING/
IMPROVING SIGNAL FOR AT LEAST A MDT ROUND OF LOWER LEVEL THERMO-
DYNAMIC FORCING TO MOVE ACROSS THE AREA LATE SAT NIGHT/SUN MORNING.
THIS ALONG WITH MU CAPE VALUES AROUND 1K J/KG WHEN LIFTING ELEVATED
PARCELS. RAISED SHRA/TSRA CHANCES INTO THE 50-60 PERCENT RANGE FOR
THE FRONTAL APPROACH/PASSAGE LATE SAT NIGHT INTO SUN MORNING. USED A
MODEL/ENSEMBLE CONSENSUS OF THE NUMERICAL GUIDANCE LOWS/HIGHS FOR
TONIGHT THRU SAT NIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 331 PM CDT FRI AUG 30 2013
MAIN FORECAST CONCERNS FOR SUN THRU MON NIGHT INCLUDE SHRA/TSRA
CHANCES SUN AS THE FRONT MOVES ACROSS THE AREA...TEMPERATURES THRU
THE PERIOD.
MODELS CONTINUE WITH IMPROVING AGREEMENT IN THE SUN-MON NIGHT
PERIOD...FOR WHAT LOOKS TO BE A COOLER/QUIET PERIOD ONCE THE FRONT/
SHRA/TSRA ON SUN EXIT EAST OF THE AREA. TREND SUN THRU MON NIGHT
FAVORS FASTER OF THE EARLIER RUNS WITH THE TROUGH MOVING ACROSS/EAST
OF THE AREA THRU THIS PERIOD. WITH THE TIGHTER CONSENSUS...FAVORED
THE MODEL/ENSEMBLE CONSENSUS.
STRONGER/DEEPER OF LOWER LEVEL THERMO-DYNAMIC FORCING/LIFT TO BE
MOVING ACROSS THE FCST AREA SUN MORNING...ESPECIALLY THE EASTERN
SIDE. CARRIED 40-50+ PERCENT RANGE SHRA/TSRA CHANCES OVER THE
SOUTHEAST 1/2 OF THE FCST AREA SUN MORNING...TRENDING THESE DOWN
THRU THE AFTERNOON AS THE FRONT PUSHES EAST...THE MID LEVEL TROUGH
AXIS PASSES AND COOLER/DRIER CANADIAN HIGH PRESSURE BUILDS IN. DEW
POINTS WITH THIS HIGH/AIRMASS DROP THRU THE 60S SUN...INTO THE 50S
FOR SUN NIGHT/MON/MON NIGHT. TIGHTER SFC PRESSURE GRADIENT BEHIND
THE FRONT SUN COUPLE WITH SOUNDINGS SHOWING MIXING TO 850MB SUN
AFTERNOON...SHOULD MAKE FOR SOME BREEZY/GUSTY NORTHWEST WINDS SUN
AFTERNOON. HIGH CONTINUES TO BUILD SOUTHEAST SUN NIGHT THRU MON
NIGHT...ENDING UP CENTERED OVER WI BY 12Z TUE. 925MB TEMPS IN THE 8C-
12C RANGE MON MORNING...14C-18C RANGE MON AFTERNOON THEN 11C-15C TUE
MORNING. AFTER THE PAST WEEK...SUN NIGHT THRU MON NIGHT LIKELY TO
FEEL ON THE COOL SIDE WITH LOWS IN THE 50S AND HIGHS ONLY IN THE
70S. USED A BLEND OF THE NUMERICAL GUIDANCE FOR HIGHS/LOWS FOR SUN
THRU MON NIGHT.
FOR TUESDAY THROUGH FRIDAY /DAYS 4-7/...
LATEST MEDIUM RANGE MODELS IN DECENT AGREEMENT TUE FOR THE EASTERN
NOAM TROUGHING TO BE PROGRESSIVE WITH RISING HGTS/SHORTWAVE RIDGING
BUILDING OVER THE UPPER MIDWEST. LESSER AGREEMENT ALREADY WED ON A
SHORTWAVE DROPPING DOWN THE EAST SIDE OF CENTRAL NOAM RIDGING...BUT
30.12Z MODEL RUNS IN BETTER AGREEMENT THAN THE 30.00Z RUNS WERE.
SOME DIFFERENCES CONTINUE THU/FRI...WITH ECMWF HOLDING MORE NORTHWEST
FLOW OVER THE REGION AND OVERALL LESS PROGRESSIVE WITH THE FLOW
ACROSS NOAM FOR LATER NEXT WEEK. FCST CONFIDENCE IN THE DAY 4-7
PERIOD IS AVERAGE TO GOOD THIS CYCLE.
THE MODEL DIFFERENCES LOOK TO HAVE MINIMAL IMPACT ON ANY SHRA/TSRA
CHANCES IN THE DAY 4-7 PERIOD...WITH NEXT WEEK TRENDING DRY. MDT/
STRONG CAN HIGH REMAINS OVER THE WESTERN GREAT LAKES TUE...FOR A
DRY/SEASONABLE DAY. MODELS PUSH A WEAKENING COLD FRONT QUIETLY THRU
THE UPPER MIDWEST WED. THIS LOOKS TO BE LITTLE MORE THAN A WIND SHIFT
THAT USHERS IN ANOTHER CAN HIGH PRESSURE SYSTEM...AS MOISTURE/
INSTABILITY REMAIN ON THE LIMITED SIDE. CAN HIGH OF ONE FORM OR
ANOTHER CONTINUES TO BE THE MAIN INFLUENCE ON THE AREAS WEATHER
THU/FRI. WITH NO ONE MODEL SHOWING CLEARLY BETTER RUN-TO-RUN
CONSISTENCY THAN THE OTHERS...DID NOT STRAY FAR FROM THE MODEL/
ENSEMBLE CONSENSUS FOR HIGHS/LOWS IN THE TUE-FRI PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1145 PM CDT FRI AUG 30 2013
THE WEAK AREA OF SURFACE HIGH PRESSURE REMAINS OFF TO THE
NORTHEAST OF THE AREA AS A SECONDARY AREA OF LOW PRESSURE HAS
FORMED ALONG THE FRONT OVER SOUTHEAST IOWA. THIS IS HELPING TO
MAINTAIN A GRADIENT WITH EAST TO NORTHEAST WINDS AROUND 5 KNOTS.
DEW POINTS CONTINUE TO DROP IN THIS NORTHEAST FLOW WITH A 14
DEGREE TEMP/DEW POINT SPREAD AT KLSE AT 03Z. CONTINUES TO LOOK
MORE AND MORE UNLIKELY THAT FOG WILL FORM OVERNIGHT AS THE THE
TEMP AND DEW POINT SHOULD CONTINUE TO CHASE EACH OTHER DOWNWARD.
HAVE REMOVED THE IFR FOG FOR BOTH SITES WHILE MAINTAINING SOME
MVFR RESTRICTIONS FOR LATE TONIGHT. THE 31.03Z RAP CONTINUES TO
SUGGEST AN MVFR CLOUD DECK ADVECTING IN FROM THE EAST BUT NOW
TAKES THIS MOISTURE A LITTLE FARTHER SOUTH THAN PREVIOUS RUNS HAD
SHOWN. MVFR CEILINGS ARE IN PLACE ACROSS SOUTHEAST WISCONSIN AND
HAVE OPTED TO LEAVE THIS POSSIBILITY IN DUE TO THE CLOSE PROXIMITY
OF THESE IN THE LOW LEVEL EAST FLOW. ONCE CONDITIONS MIX OUT
SATURDAY MORNING...VFR CONDITIONS EXPECTED FOR THE REMAINDER OF
THE PERIOD.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
UPDATE...04
SHORT TERM...RRS
LONG TERM....RRS
AVIATION...04
AREA FORECAST DISCUSSION...UPDATE
NWS MILWAUKEE/SULLIVAN WI
1115 PM CDT FRI AUG 30 2013
.UPDATE...NELY FLOW AND LOW LEVEL COLD ADVECTION UNDERWAY. 60
DEWPOINTS ON COOL SIDE OF FRONT IS AIDING STRATUS DEVELOPMENT OVER
MUCH OF THE GREAT LAKES INTO SRN WI. STRATUS AND SOME WINDS SHOULD
KEEP ANY FOG ON THE LIGHT SIDE. TEMPS WILL REBOUND ON SAT AFTER
STRATUS AND FOG BURN OFF WITH HIGHS IN THE MID TO UPPER 70S LAKESIDE
TO LOWER TO MID 80S WELL INLAND.
&&
.AVIATION/06Z TAFS/...BROKEN STRATUS FROM 1.0-3.0 KFT IS EXPECTED
UNTIL LATE SAT AM OR EARLY AFTERNOON. AREAS OF MVFR AND IFR VSBYS
WILL OCCUR EARLY SAT AM AND IMPROVE BY 15Z. OTHERWISE VFR CONDITIONS
EXPECTED FOR SAT AFTERNOON INTO THE EVENING.
&&
.PREV DISCUSSION... /ISSUED 354 PM CDT FRI AUG 30 2013/
VERY SHORT TERM...TONIGHT AND SATURDAY.
TONIGHT - CONFIDENCE...MEDIUM
PLENTY OF CAPE POOLING AHEAD OF SOUTHWARD MOVING FRONTAL BOUNDARY.
STORMS ARE ORGAN ZING AS BEST AS THEY CAN GIVEN THE LACK OF DECENT
0-6KM SHEAR AND SUSPECT MID LEVEL LAPSE RATES. HOWEVER PLENTY OF
CAPE IN THE LOW LEVELS WITH GOOD LOW LEVEL LAPSE RATES WITH
SURFACE/925 CONVERGENCE ALLOWING FOR SOME STRONGER WINDS AND HAIL.
WATER VAPOR/RUC COMBO DOES SHOW A WEAK UPSTREAM WAVE RIDING IN
FROM SRN MN AND NRN IA. HRRR SHOWING STORMS CLEARING THE FAR SOUTH
AROUND 00Z OR SO. HOWEVER 4KM WRF-SPC AND 12Z ECMWF LINGER PRECIP
ACROSS PORTIONS OF SC WI DEEPER INTO THE EVENING. BASED ON FRONTAL
PROGRESSION WILL BANK ON A QUICKER EXIT OF PRECIP BASED ON OTHER
MODELS. SO FRONTAL BOUNDARY EXITS TO THE SOUTH THIS EVENING TAKING
ANY LINGERING STORMS WITH IT. WILL RETAIN HEAT ADVISORY FOR SOUTHERN
TIER ONLY AS I-94 CORRIDOR AFFECTED BY OUTFLOW AND STORMS.
SURFACE/925 COOL AIR ADVECTION THEN TAKES HOLD. NOT SO MUCH UP TO
850 MILLIBARS...BUT FROM 925 AND ON DOWN PRETTY STRONG SIGNAL AND
THIS IS PLAUSIBLE GIVEN CONDITIONS UPSTREAM IN NORTHERN WISCONSIN.
EXPECTING COOLER AND DRIER DEW POINTS TO ADVECT INTO THE AREA WITH
THE EVOLVING POST-FRONTAL NORTH WINDS. LOW LEVEL WIND FLOW/DEGREE OF
MIXING SUGGESTS THE EVOLUTION OF DENSE FOG NOT LIKELY. LOOKS MORE
LIKE STRATUS POTENTIAL.
SATURDAY - CONFIDENCE...MEDIUM HIGH PRESSURE SETTLES IN. MORNING
FOG/LOW STRATUS POTENTIAL WILL GRADUALLY BURN OFF. NOT A BIG
DROP OFF IN 850 TEMPS. NEVERTHELESS CU RULE SUPPORTIVE OF SCT
COVERAGE AFTER MORNING STRATUS. 925 TEMPS PROGGD TO 20-23C.
COMFORTABLY COOLER AND LESS HUMID. SO LOW TO MID 80S WITH
MID/UPPER 70S IN THE FAR EAST WITH THE SUSTAINED ONSHORE FLOW.
SHORT TERM...SATURDAY NIGHT THROUGH MONDAY.
SATURDAY NIGHT AND SUNDAY...FORECAST CONFIDENCE MEDIUM TO HIGH.
NEXT BEST CHANCE OF PRECIPITATION COMES WITH SHORT WAVE TROUGH AND
COLD FRONT. STILL SOME DIFFERENCES IN CONFIGURATION OF SHORT WAVE
THAT IMPACTS TIMING OF SURFACE TROUGH/COLD FRONT THROUGH REGION.
WILL GO WITH BLENDED SOLUTION THAT BRINGS A CHANCE TO THE NW CWA
BETWEEN 06Z AND 12Z SUNDAY...THEN HIGH CHANCE POPS ACROSS THE
ENTIRE FORECAST AREA DURING THE DAY SUNDAY. SHOULD SEE LOW TO MID
80S HIGHS PRIOR TO ONSET OF PCPN.
SUNDAY NIGHT AND MONDAY...FORECAST CONFIDENCE HIGH.
PRECIPITATION CHANCES LINGER INTO SUNDAY EVENING IN THE EAST WITH
HIGH PRESSURE BUILDING IN BEHIND. LABOR DAY MORE FALL-LIKE WITH
LOW TO MID 70 HIGHS.
LONG TERM...MONDAY NIGHT THROUGH FRIDAY...FORECAST CONFIDENCE
MEDIUM TO HIGH.
DRY WEATHER AS HIGH PRESSURE DOMINATES THE WESTERN GREAT LAKES REGION
UNDER NORTHWEST FLOW REGIME. MODELS TRY TO BRUSH SW/SOUTHERN CWA
WITH LIGHT QPF WITH A WEAK WAVE/WARM AIR ADVECTION BUT FOR NOW
WILL LEAVE DRY. BELOW NORMAL TEMPERATURES WILL WARM BACK TOWARD
NORMAL LEVELS...OR SLIGHTLY ABOVE...WEDNESDAY THROUGH THE REST OF
THE EXTENDED.
AVIATION/00Z TAFS/...
THUNDERSTORM POTENTIAL THROUGH 00Z WITH FRONTAL BOUNDARY DROPPING
IN FROM THE NORTH. WINDS WILL SHIFT TO THE NORTH IN THE WAKE OF
THE FRONT WITH THE EVENING FROPA. WILL MONITOR STRATUS TRENDS IN
THE COOL ADVECTION REGIME. EXPECT MVFR CEILINGS AND POTENTIAL FOR
IFR LATER TONIGHT INTO EARLY SATURDAY. THINKING ENOUGH MIXING WILL
INHIBIT DENSE FOG FORMATION.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...GEHRING
TONIGHT/SATURDAY AND AVIATION/MARINE...COLLAR
SATURDAY NIGHT THROUGH FRIDAY...REM
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1001 AM EDT SAT AUG 31 2013
.SYNOPSIS...
A STALLED FRONTAL BOUNDARY STRETCHING FROM NEW YORK STATE INTO NEW
ENGLAND WILL RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS AT TIMES
TODAY AND SUNDAY. SHOWERS AND THUNDERSTORMS MAY BECOME MORE
WIDESPREAD MONDAY INTO EARLY TUESDAY AS A COLD FRONT MOVES ACROSS
THE REGION. DRIER...COOLER AND MUCH LESS HUMID WEATHER ARRIVES
MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
10 AM UPDATE...SCATTERED SHOWERS CONTINUE MAINLY COMING OFF OF THE
BERKSHIRES THIS MORNING. PLENTY OF MOISTURE /PWATS 1.5 TO 1.8
INCHES/ AND DECENT INSTABILITY /MUCAPE VALUES AROUND 1000 J/KG/ WILL
ALLOW THESE SHOWERS TO CONTINUE AT LEAST FOR THE NEXT SEVERAL
HOURS. OVERCAST SKIES IN PLACE WILL LIMIT ANY FURTHER
DESTABILIZATION GOING INTO THE AFTERNOON. IF CLOUDS BREAK UP AT
ALL DURING THE AFTERNOON...SHOWERS AND THUNDERSTORMS MAY
REDEVELOP. MADE SOME MINOR UPDATES TO THE POP/WX GRIDS TO ACCOUNT
FOR THE LATEST TRENDS WITH THE SHOWERS THIS MORNING.
PREVIOUS DISCUSSION...
SHORTWAVE TROUGH OVER THE EASTERN GREAT LAKES AND NY STATE EARLY
THIS MORNING DEAMPLIFIES AS IT APPROACHES AND MOVES ACROSS NEW
ENGLAND TODAY. THIS IS EVIDENT IN WEAKENING WIND FIELDS
ALOFT...LESS CURVATURE IN THE MID LEVEL FLOW/STREAMLINES AND
WEAKENING Q-VECTOR CONVERGENCE ALONG AND AHEAD OF THE MID LEVEL
TROUGH. LAST FEW RUNS OF THE HRRR OFFER THE SAME THEME WITH
WEAKENING REFLECTIVITY AS CONVECTION APPROACHES NEW ENGLAND.
THEREFORE EXPECTING UPSTREAM CONVECTION ACROSS NY STATE AND VT TO
SLOWLY WEAKEN AS IT APPROACHES AND ENTERS SOUTHERN NEW ENGLAND.
HOWEVER THINK NEW CONVECTION WILL REFIRE OVER THE AREA THIS
AFTERNOON AS SOME SUNSHINE TODAY DESTABILIZES THE ATMOSPHERE WITH
THE MORE CONSERVATIVE ECMWF AND GEFS OFFERING CAPES ON THE ORDER OF
1200-1800J/KG. FAIRLY CONFIDENT IN THIS SCENARIO AS ALL MOS GUIDANCE
HAVE HIGH TEMPS TODAY IN THE LOW TO MID 80S...WITH WARMEST
READINGS ACROSS NORTHEAST MA AND SOUTHEAST NH. THIS INSTABILITY
COMBINED WITH WEAK BUT MOIST CYCLONIC FLOW ALOFT SHOULD BE
SUFFICIENT TO YIELD SCATTERED THUNDERSTORMS. HIGHEST PROBABILITY
WILL BE ACROSS THE INTERIOR...CLOSER TO FRONTAL BOUNDARY AND
SURFACE CONVERGENCE. THUS CONVECTION SHOULD BE LESS WIDESPREAD ACROSS
SOUTHEAST MA /INCLUDING CAPE COD AND THE ISLANDS/ AND POSSIBLY
INTO BOSTON-PROVIDENCE CORRIDOR. MAIN ISSUE WITH ANY TSTMS TODAY
WILL BE HEAVY DOWNPOURS/FLOOD POTENTIAL WITH PWATS JUST UNDER 2
INCHES ALONG WITH WEAK WINDS ALOFT RESULTING IN SLOW MOVING
STORMS. TIMING OF STORMS WILL BE AFTER 16Z AND SPECIFICALLY DURING
PEAK HEATING FROM 18Z-21Z.
IT WILL BE WARM AND HUMID TODAY AS SOUTHERN NEW ENGLAND WILL BE IN
THE WARM SECTOR OF THE APPROACHING FRONTAL SYSTEM. DEW PTS WILL
CLIMB INTO THE U60S AND L70S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
TONIGHT...
EARLY EVENING SHOWERS/TSTMS ACROSS THE INTERIOR SHOULD DISSIPATE
WITHIN A FEW HOURS OF SUNSET GIVEN THE LACK OF DEEP LAYER SHEAR
AND MID LEVEL LAPSE RATES NEEDED TO SUSTAIN NOCTURNAL CONVECTION.
HOWEVER CAN/T RULE OUT ISOLATED OR WIDELY SCATTERED SHOWERS
OVERNIGHT GIVEN THE WEAK BUT MOIST CYCLONIC FLOW ALOFT.
SOUTHERN NEW ENGLAND REMAINS IN THE WARM SECTOR SO EXPECT PATCHY FOG
AND LOW CLOUDS. HIGH DEW PTS WILL YIELD ANOTHER MILD TO WARM NIGHT.
SUNDAY...
WEAK SHORTWAVE RIDGING MAY MOVE ACROSS THE REGION BEHIND
DEPARTING SHORTWAVE TROUGH OF TODAY AND BEFORE NEXT TROUGH
APPROACHES SUN NGT AND MON. THIS IS EVIDENT ON MODEL CROSS AND
TIME SECTIONS WITH COLUMN DRYING OUT IN THE MID AND UPPER LEVELS.
SO WHILE THERE IS STILL SOME UNCERTAINTY TO SUNDAY/S
FORECAST...THERE IS INCREASING CONFIDENCE THAT ANY SHOWER/TSTM
ACTIVITY WILL NOT BE WIDESPREAD. THUS NOT EXPECTING A WASHOUT
SUNDAY.
THE AREA REMAINS IN THE WARM SECTOR SO ANOTHER WARM AND MUGGY DAY
WITH HIGHS 80-85 AWAY FROM THE COAST ALONG WITH DEW PTS IN THE U60S
AND L70S.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
HIGHLIGHTS...
* SHOWERS AND THUNDERSTORMS LIKELY ON MONDAY AND INTO TUESDAY
* SLOW MOVING COLD FRONT WILL CROSS THE REGION ON TUESDAY
* FALL LIKE CONDITIONS FOR THE SECOND HALF OF THE WORK WEEK
CONFIDENCE LEVEL/MODEL GUIDANCE...
MODERATE CONFIDENCE IN OVERALL FORECAST. CONTINUE TO HAVE
INCREASING CONFIDENCE FOR THE TEMPERATURE ASPECT IN THE FORECAST.
MODERATE CONFIDENCE IN TIMING OF PRECIPITATION WITH HIGH
CONFIDENCE THAT PRECIP WILL OCCUR MONDAY AND EARLY TUESDAY. THE
00Z MODELS MAINTAIN A NEARLY STEADY-STATE TO SLIGHTLY RETROGRADING
PATTERN IN THE LOWER HALF OF THE CONUS WITH AN UPPER HIGH OVER THE
CENTRAL/SOUTHERN PLAINS. WHILE ACROSS THE NORTHEAST A PROGRESSIVE
FLOW INFLUENCED BY MULTIPLE SHORTWAVES AND FRONTAL PASSAGES WILL
RESULT IN GENERALLY COOLER TEMPERATURES. HOWEVER THE
DETAILS/TIMING ARE AN ISSUE DUE TO THE PATTERNS SHORT WAVELENGTH
AND POSSIBILITY OF PHASING. THAT BEING SAID FELT PERSISTENCE WAS
A GOOD WAY TO GO FOR THIS MORNINGS FORECAST. BLENDED PREVIOUS
FORECAST WITH WPC AND THE ENSEMBLES.
DETAILS...
MONDAY...
LONG WAVE TROUGH WILL SHARPEN UP ON MONDAY AS HUDSON BAY LOW
PRESSURE STRENGTHENS. THIS WILL KEEP THE REGION IN A SOUTHWEST
FLOW WITH INCREASING MOISTURE CAUSING VERY MUGGY CONDITIONS. MAIN
FOCUS IS A COLD FRONT ACROSS THE GREAT LAKES THAT WILL APPROACH
THE REGION. HOWEVER A SHORTWAVE WILL MOVE THROUGH THE FLOW ON
MONDAY WHICH WILL SPARK SOME SHOWERS AND THUNDERSTORMS. THE REGION
WILL BE IN THE WARM...MOIST SECTOR AS WELL AS THE BETTER JET
DYNAMICS. MAIN THREAT WITH THESE STORMS WILL BE HEAVY RAIN AS PWAT
VALUES WILL BE ABOVE 2 INCHES. THESE STORMS WILL BE SLOW MOVING
AND/OR TRAINING AS CORFIDI VECTORS ARE AROUND 0-5 KTS. NOTICED SPC
PUT THE REGION IN A SEE TEXT FOR DAY THREE OUTLOOK. HAVE LOW
CONFIDENCE IN OVERALL SEVERE WEATHER THREAT AS INSTABILITY VALUES
WILL BE LOWER THAN MODELS SUGGEST DUE TO THE AMOUNT OF CLOUDS
ACROSS THE AREA. THIS IDEA IS ALSO SUPPORTED BY THE ENSEMBLES.
THEREFORE BELIEVE THAT THE MAIN THREAT WILL STILL BE HEAVY RAIN
CAUSING SOME URBAN AND POOR DRAINAGE FLOODING. SMALL STREAM LEVELS
MAY ALSO RISE IF THUNDERSTORMS TRAIN OVER CERTAIN REGIONS. THIS
PORTION OF THE FORECAST WILL NEED TO BE WATCHED CLOSELY OVER THE
WEEKEND.
TUESDAY...
COLD FRONT WILL MOVE THROUGH SOUTHERN NEW ENGLAND ON TUESDAY.
MAIN QUESTION IS THE TIMING. IF THE FRONT SLOWS DOWN THEN THERE IS
A CHANCE FOR SHOWERS AND THUNDERSTORMS TO DEVELOP ESP ACROSS THE
EASTERN HALF OF THE REGION. IF THE FRONT SPEEDS UP THEN ONLY A FEW
SHOWERS MAY OCCUR AS THE FRONT EXITS OFFSHORE. REGARDLESS HAVE A
LOWER CONFIDENCE ON ANY STRONG STORMS ON TUESDAY AS BETTER JET
DYNAMICS WILL BE OFFSHORE. BOTH THE ENSEMBLES INDICATE THE BETTER
MOISTURE IS OFFSHORE AS WELL. TRENDED TOWARDS A FASTER SOLUTION ON
TUESDAY. A FEW HEAVY SHOWERS ARE STILL POSSIBLE WITH MAIN CONCERN
BEING NUISANCE FLOODING.
WEDNESDAY THROUGH FRIDAY...
LARGE-SCALE SUBSIDENCE WILL FILTER IN BEHIND THE FRONT ON
WEDNESDAY. THIS WILL DROP DEWPOINTS DOWN INTO THE 40/50S MAKING IT
VERY COMFORTABLE. A FEW SHOWERS ARE POSSIBLE ACROSS THE NW ZONES
FROM WRAP AROUND MOISTURE FROM THE LOW. OTHERWISE EXPECT MOSTLY
DRY CONDITIONS. MODELS ARE INDICATING A POLAR FRONT WILL MOVE
THROUGH ON THURSDAY BRINGING SOME ISOLATED/SCATTERED SHOWERS. HAVE
A LOWER CONFIDENCE AS THERE IS A GOOD AMOUNT OF DRY AIR ACROSS THE
AREA. BEHIND THIS FRONT IS A MORE FALL LIKE AIRMASS BRINGING
OVERNIGHT LOWS IN THE 40S AND HIGHS ONLY IN THE 60S.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW...LOW TO MODERATE CONFIDENCE ON EXACT DETAILS INCLUDING
TIMING...BUT HIGHER CONFIDENCE ON OVERALL FORECAST THEME. CIGS AND
VSBYS WERE DERIVED FROM A BLEND OF NAM AND GFS MOS.
TODAY...
MVFR/IFR CONDITIONS ARE FAIRLY WIDESPREAD THIS MORNING WITH VFR
CONDITIONS LIMITED TO SOUTHEASTERN NEW HAMPSHIRE. VSBYS SHOULD
IMPROVE TO VFR BY 16Z WHILE CIGS WILL REMAIN MVFR/IFR FOR SEVERAL
MORE HOURS...PARTICULARLY ACROSS SE MA AND RI. SHOWERS CONTINUE
THIS MORNING. ADDITIONAL SHOWERS AND TSTMS WILL DEVELOP AFTER 16Z
MAINLY INLAND WITH DAYTIME HEATING SHOULD THE SUN BREAK THROUGH
THE CLOUDS AT ALL.
TONIGHT...
ALMOST A REPEAT PERFORMANCE...IFR IN LOW CLOUDS CONFINED TO
SOUTHEAST MA AND RI WITH MVFR/VFR ELSEWHERE. ISOLATED/SCATTERED
SHOWERS SHOULD BE MOST NUMEROUS WELL INLAND.
SUNDAY...
IFR SOUTHEAST MA AND RHODE ISLAND BUT IMPROVING TOWARD MIDDAY TO
VFR. VFR ELSEWHERE. NOT EXPECTING WIDESPREAD SHOWERS/TSTMS...MORE
ISOLATED TO WIDELY SCATTERED.
KBOS TERMINAL...HIGH CONFIDENCE ON TRENDS. LOW CONFIDENCE ON
TIMING. BULK OF LOW CLOUDS SHOULD SLIDE SOUTH OF THE AIRPORT.
SHOWERS THIS MORNING MAY AFFECT THE AIRPORT AT TIMES THROUGH THE
MORNING. ANY SHOWERS/THUNDERSTORMS THAT DEVELOP THIS AFTERNOON
SHOULD REMAIN NORTH AND WEST OF THE AIRPORT.
KBDL TERMINAL...HIGH CONFIDENCE ON TRENDS. LESS CONFIDENT ON
TIMING. SHOWERS/TSTMS WILL BECOME MORE NUMEROUS 16Z- 22Z.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...
SUNDAY NIGHT...MODERATE CONFIDENCE. EXPECT MAINLY MVFR CIGS/VFR
VSBYS. AREAS MVFR VSBYS IN ANY SHOWERS/TSTMS. LOCAL IFR VSBYS IN
ANY HEAVIER RAINFALL.
MONDAY-TUESDAY...LOW CONFIDENCE MAINLY FOR TIMING. MVFR
CONDITIONS WITH IFR IN SHOWERS/TSTMS. PERIODS OF HEAVY RAINFALL
WILL REDUCE VSBYS AS WELL.
WEDNESDAY...HIGH CONFIDENCE. MVFR TO START...IMPROVING TO VFR BY
THE AFTERNOON HOURS.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
TODAY THROUGH SUNDAY...
MODEST SW WIND 10-15 KT WITH GUSTS AROUND 20 KT LIKELY.
WARM/MUGGY AIRMASS WILL YIELD LATE NIGHT/EARLY MORNING FOG.
SHOWERS LIKELY ON THE EASTERN WATERS THIS MORNING INTO THIS
AFTERNOON. THEN SHOWERS/TSTMS WILL BE MAINLY INLAND. FORECAST
CONFIDENCE MODERATE TO HIGH.
OUTLOOK...MONDAY THROUGH WEDNESDAY...
PERSISTENT SOUTHERLY SWELL COMBINED WITH AN APPROACHING COLD
FRONT WILL CAUSE SEAS TO BUILD UP TO 5 FT ESP ACROSS THE OUTER
WATERS THROUGH TUESDAY. BELIEVE THIS IS A LITTLE HIGH SO HAVE
UNDERCUT WAVE GUIDANCE TO TOP OUT AT 4FT. LOW PROB FOR GUSTS UP TO
25 KT AHEAD OF COLD FRONT MON NIGHT AND EARLY TUE. EXPECT COLD
FRONT TO MOVE ACROSS WATERS LATE TUE/TUE NIGHT. WINDS/SEAS SHOULD
SLOWLY DIMINISH DURING WED. BEST CHANCE FOR THUNDERSTORMS WILL BE
MONDAY INTO TUESDAY MORNING.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...NOCERA/DUNTEN
NEAR TERM...NOCERA/DUNTEN/RLG
SHORT TERM...NOCERA
LONG TERM...DUNTEN
AVIATION...NOCERA/DUNTEN
MARINE...NOCERA/DUNTEN
AREA FORECAST DISCUSSION
NWS ALBANY NY
741 AM EDT SAT AUG 31 2013
.SYNOPSIS...
A WARM AND HUMID AIR MASS WILL IMPACT EASTERN NEW YORK
AND WESTERN NEW ENGLAND THROUGH THE HOLIDAY WEEKEND. A SERIES OF
WEAK DISTURBANCES MOVING ALONG A FRONTAL BOUNDARY NEAR THE SAINT
LAWRENCE RIVER VALLEY WILL PRODUCE SHOWERS AND THUNDERSTORMS TODAY
WITH SOME LOCALLY HEAVY RAINFALL. THE UNSETTLED WEATHER CONTINUES
LATE SUNDAY INTO LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE
WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TO THE REGION.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 655 AM EDT...THE LAST FULL DAY OF AUGUST AND METEOROLOGICAL
SUMMER BEGAN WITH SHOWERS AND SCT THUNDERSTORMS ACROSS PORTIONS OF
THE ALY FCST AREA...ESPECIALLY FROM THE NRN CATSKILLS...CAPITAL
REGION AND SRN VT NORTHWARD. A COUPLE OF WEAK SFC LOWS ARE MOVING
ALONG A STATIONARY FRONT NEAR THE ST LAWRENCE RIVER VALLEY AND ERN
GREAT LAKES THIS MORNING. LOW-LEVEL CONVERGENCE WITH THE SFC LOWS
HAS HELPED THE SHOWERS AND THUNDERSTORMS BE THE MOST PERSISTENT IN
THE MOHAWK RIVER VALLEY...SRN DACKS...AND THE LAKE GEORGE SARATOGA
REGION. THIS ACTIVITY WILL CONTINUE TO WANE EARLY THIS MORNING...AND
A BRIEF LOW WILL OCCUR TOWARDS NOONTIME. THE POPS WERE RETRENDED
THIS MORNING BASED ON THE RADAR TRENDS.
A MAJORITY OF THE GUIDANCE SHOWS ANOTHER WEAK RIPPLE OF LOW
PRESSURE MOVING ALONG THE BOUNDARY IN THE AFTERNOON WITH A MID
LEVEL SHORT-WAVE IN THE W/SW FLOW ALOFT. IT IS QUESTIONABLE IF ANY
SIGNIFICANT HEATING WILL OCCUR EXCEPT PERHAPS ALONG THE SRN TIER
OF THE FCST AREA /MID HUDSON VALLEY AND NW CT/. THE 0-6 KM DEEP
SHEAR IS WEAK WITH WEAK MID LEVEL LAPSE RATES ALOFT...SO
WIDESPREAD SEVERE CONVECTION IS NOT ANTICIPATED DESPITE SBCAPE
VALUES OF 1000-2000 J/KG ACCORDING THE NAM/GFS. H850 THETA-E
VALUES WILL BE GENERALLY IN THE 335-340K RANGE. THE PWATS WILL BE
IN THE 1.25-1.75 INCH RANGE /1 TO 2 STANDARD DEVIATIONS ABOVE
NORMAL/...SO LOCALLY HVY RAINFALL WILL BE THE MAIN ISSUE. THE
ENHANCED WORDING WAS PUT IN THE GRIDS...AND WILL BE MENTIONED IN
THE HWO. IF THE HIGHER CAPE VALUES ARE REALIZED...AN ISOLATED WET
MICROBURST MAY BE POSSIBLE. THE MAIN THREAT CONTINUES TO BE HEAVY
RAINFALL. THE HIGHEST POPS IN THE LIKELY RANGE WERE USED ACROSS
THE NRN HALF OF THE FCST AREA.
THE 07Z 3KM HRRR COLUMN REF PRODUCT SHOWS DISCRETE CONVECTIVE
ELEMENTS FORMING INTO A LINE OVER THE HUDSON RIVER VALLEY IN THE
MID AFTERNOON. IN A WEAK SHEAR ENVIRONMENT THIS APPEARS TO BE OFF
SOME...BUT WILL HAVE TO BE MONITORED. LATER RUNS HAVE SHOWN LESS
SIGNIFICANT COVERAGE AND ORGANIZATION.
THE SFC DEWPTS WILL REMAIN IN THE 60S WITH PERHAPS SOME SPOTTY
LOWER 70S OVER THE SRN TIER. THE AIR MASS WILL BE STICKY FOR THE
LAST DAY OF AUGUST. MINIMAL HEATING SHOULD ALLOW FOR U70S TO L80S
IN THE VALLEYS...WITH 70S OVER THE HILLS AND MTNS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
TONIGHT...THE SHOWERS AND THUNDERSTORMS SHOULD DIMINISH IN THE
EARLY EVENING WITH THE WEAK SFC WAVE MOVING EAST/NORTHEAST OF THE
REGION...AND THE MID LEVEL SHORT-WAVE PASSING DOWNSTREAM. THE
FRONTAL BOUNDARY MAY MOVE OVER THE NRN HALF OF THE FCST AREA AND
FALL APART. THE POPS WERE LOWERED TO SLIGHT CHC VALUES AFTER
MIDNIGHT. IT WILL REMAIN VERY HUMID WITH LOWS IN THE MID AND U60S
OVER MOST OF THE REGION...EXCEPT OVER THE MTNS.
SUNDAY...THE ENTIRE DAY SHOULD NOT BE A WASHOUT WITH AN AMPLIFYING
UPPER LEVEL TROUGH OVER ONTARIO AND THE GREAT LAKES REGION. THE
MID LEVEL FLOW WILL BECOME SOUTHWESTERLY OVER NY AND NEW ENGLAND
WITH WEAK RIDGING ALOFT. THEIR ARE NOT ANY REAL ROBUST SYNOPTIC
TRIGGER MECHANISMS DURING THE DAY. AIR MASS OR DIFFERENTIAL
HEATING THUNDERSTORMS ARE POSSIBLE. A SLIGHT TO LOW CHANCE OF
SHOWERS AND THUNDERSTORMS WAS INCLUDED IN THE GRIDS. H850 TEMPS
INCREASE TO +16C TO +17C WITH PARTLY SUNNY CONDITIONS. MAX TEMPS
WILL RUN ABOUT 5-10 DEGREES ABOVE NORMAL TO OPEN SEPT.
SUNDAY NIGHT INTO LABOR DAY...A LARGE TROUGH OF LOW PRESSURE
IMPACTS THE REGION. SEVERAL MID LEVEL SHORT-WAVES ROTATING AROUND
THE CLOSED LOW SOUTH OF JAMES BAY WILL YIELD UNSETTLED WX DURING
THIS TIME FRAME. IT IS DIFFICULT TO DETERMINE IF ANY ROBUST SFC
HEATING WILL OCCUR AT THIS TIME. THE STRONG SYNOPTIC LIFT WITH THE
TROUGH WILL LIKELY YIELD PERIODS OF SHOWERS AND SCT THUNDERSTORMS.
SOME HVY RAINFALL LOOKS LIKE A GOOD BET. THE QG LIFT INCREASES
LABOR DAY AFTERNOON...AS THE NRN HALF OF THE FCST AREA GETS NEAR
THE RIGHT ENTRANCE REGION OF A H250 JET STREAK WITH STRONG UPPER
LEVEL DIVERGENCE ALOFT. PWATS CONTINUE ABOVE NORMAL FOR EARLY
SEPT. LIKELY POPS WERE CONTINUED ON MONDAY. THE COOLER NAM MOS
TEMPS WERE ALSO FOLLOWED CLOSELY WITH THE AMOUNT OF CLOUD COVER
AND NUMEROUS SHOWERS EXPECTED. MAX TEMPS WILL BE HARD PRESSED TO
GET OUT OF THE 70S WITH PERHAPS SOME 80F READINGS FROM THE CAPITAL
REGION SOUTH IN THE MID HUDSON VALLEY.
MONDAY NIGHT...LOW AND MID LEVEL HEIGHTS CONTINUE TO FALL...AS THE
TROUGH OF LOW PRESSURE AND ITS ASSOCIATED COLD FRONT MIGRATE EAST
OF THE REGION. A CHC OF SHOWERS WAS KEPT IN MOST OF THE OVERNIGHT.
LOW LEVEL COLD ADVECTION IS EXPECTED WITH TEMPS FALLING INTO THE
50S OVER THE MTNS WITH LOWER TO MID 60S IN THE VALLEYS.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
COOLER AND LESS ACTIVITY WEATHER AS WE HEAD THROUGH THE FIRST WEEK
OF SEPTEMBER.
THE MODEL GUIDANCE IS IN FAIRLY GOOD AGREEMENT REGARDING THE
LONGWAVE PATTERN WITH THE NORTHEAST REMAINING UNDER A TROUGH AND
THE RIDGE HOLDING ON OVER THE PLAIN STATES.
A COUPLE OF COLD FRONTS WILL MOVE ACROSS THE REGION. THE FIRST ONE
IS EXPECTED TO MOVE OFF TO OUR EAST ON TUESDAY WITH SOME LINGERING
SHOWERS POSSIBLE MAINLY DURING THE MORNING. A PLEASANT DAY EXPECTED
WEDNESDAY AS HIGHER PRESSURE BUILDS IN WITH SEASONABLE WARM
TEMPERATURES. A SECONDARY COLD FRONT IS EXPECTED TO MOVE THROUGH
THURSDAY WITH ISOLATED SHOWERS. A MORE AUTUMN-LIKE AIRMASS WILL BE
USHERED IN AS CANADIAN HIGH PRESSURE BUILDS IN ITS WAKE OF THE FRONT
TO CLOSE OUT THE WEEK. TEMPERATURES THURSDAY AND FRIDAY ARE
ANTICIPATED TO RUN ABOUT 5 DEGREES BELOW NORMAL.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
SOME SHOWERS CONTINUE TO MOVE EASTERLY ACROSS THE FORECAST AREA
EARLY THIS MORNING IN ASSOCIATION WITH A PASSING SHORT WAVE TROUGH
AND WEAK SURFACE LOW MOVING INTO THE SAINT LAWRENCE RIVER VALLEY.
EXPECT A LULL IS THE PRECIPITATION FOR A BIT THIS MORNING AS THE
SHORT WAVE TROUGH MOVES OFF TO THE EAST. HOWEVER...CHANCES FOR
CONVECTION WILL INCREASE AS HEAD INTO THE AFTERNOON AS THE SURFACE
LOW PASSES TO OUR NORTH AND ANOTHER SHORT WAVE TROUGH APPROACHES.
WITH THE HELP OF DIURNAL HEATING AND INCREASED INSTABILITY THERE WILL
BETTER CHANCES FOR SHOWERS AND THUNDERSTORMS. DO NOT HAVE CONFIDENCE
TO TIME THUNDERSTORMS AT INDIVIDUAL TAF SITES SO HAVE RUN WITH A
TEMPO GROUP FOR SHOWERS TO HIGHLIGHT MOST LIKELY TIME FOR CONVECTION
TO OCCUR.
ALTHOUGH LOW VSBYS/CIGS ARE ALLOWING FOR OCCASIONAL IFR AND MVFR
CONDITIONS EARLY THIS MORNING...AN IMPROVEMENT TO VFR CONDITIONS
IS EXPECTED BY LATE THIS MORNING. MVFR WITH BRIEF IFR CONDITIONS
ARE EXPECTED WITH ANY CONVECTION THAT IMPACTS TAF SITES TODAY.
MVFR/IFR FOG/CIGS ARE EXPECTED TO DEVELOP TONIGHT...ESPECIALLY WHERE
IT RAINS.
OUTLOOK...
SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
LABOR DAY: HIGH OPERATIONAL IMPACT. LIKELY SHRA...TSRA.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
TUESDAY: LOW OPERATIONAL IMPACT. CHANCE OF SHRA.
TUESDAY NIGHT-WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.FIRE WEATHER...
NO FIRE WEATHER PROBLEMS ARE EXPECTED IN THE HUMID AIR MASS WITH
SEVERAL CHANCES OF RAINFALL.
A SERIES OF WEAK DISTURBANCES MOVING ALONG A FRONTAL BOUNDARY
NEAR THE SAINT LAWRENCE RIVER VALLEY WILL PRODUCE SHOWERS AND
THUNDERSTORMS TODAY WITH SOME LOCALLY HEAVY RAINFALL. THE
UNSETTLED WEATHER CONTINUES LATE SUNDAY INTO LABOR DAY WHEN A
STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND
SCATTERED THUNDERSTORMS TO THE REGION.
THE RH VALUES WILL ONLY DROP TO BETWEEN 50 AND 85 PERCENT THIS
AFTERNOON...AND RECOVER TO CLOSE TO 100 PERCENT SUNDAY MORNING.
HIGH RH VALUES OF 55 TO 75 PERCENT WILL OCCUR SUNDAY AFTERNOON.
THE WINDS WILL BE FROM THE SOUTH TO SOUTHWEST AT 5 TO 15 MPH TODAY
AND TOMORROW... AND BECOME LIGHT TO CALM TONIGHT.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON
THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE
POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS.
THE BEST CHANCE FOR WIDESPREAD RAINFALL WILL BE TODAY AND ON
LABOR DAY.
HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE
EXPECTED WITH THUNDERSTORMS. ISOLATED URBAN...SMALL STREAM...AND
POOR DRAINAGE FLOODING WILL BE POSSIBLE DURING THE HOLIDAY
WEEKEND. SOME WITHIN BANK RISES ARE POSSIBLE ON LARGER STREAMS
WHERE SHOWERS AND STORMS OCCUR. ZONAL FFG VALUES REMAIN HIGH
DURING THIS TIME FRAME. HOWEVER...A QUICK INCH OR TWO OF RAINFALL
FROM A SLOW MOVING THUNDERSTORM MAY PRODUCE AN ISOLATED FLASH
FLOOD DURING THE HOLIDAY WEEKEND.
RAINFALL AMOUNTS WILL BE QUITE VARIABLE DUE TO THE SHOWERY NATURE
OF THE RAIN...WITH SOME LOCATIONS RECEIVING OVER AN INCH OF RAIN
WHILE OTHERS REMAIN DRY. SOME AREAS NORTH OF THE CAPITAL REGION
HAVE RECEIVED A HALF AN INCH TO AN INCH OF RAINFALL THIS MORNING.
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...WASULA
NEAR TERM...WASULA
SHORT TERM...WASULA
LONG TERM...IAA
AVIATION...IAA/FRUGIS
FIRE WEATHER...WASULA
HYDROLOGY...SND/WASULA
AREA FORECAST DISCUSSION
NWS TAUNTON MA
713 AM EDT SAT AUG 31 2013
.SYNOPSIS...
A STALLED FRONTAL BOUNDARY STRETCHING FROM NEW YORK STATE INTO NEW
ENGLAND WILL RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS AT TIMES
SATURDAY AND SUNDAY. SHOWERS AND THUNDERSTORMS MAY BECOME MORE
WIDESPREAD MONDAY INTO EARLY TUESDAY AS A COLD FRONT MOVES ACROSS
THE REGION. DRIER...COOLER AND MUCH LESS HUMID WEATHER ARRIVES
MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
715 AM UPDATE...
TWO BATCHES OF SHOWERS TO MONITOR THIS MORNING. FIRST IS ACROSS
CAPE ANN WHICH IS PRODUCING SOME LIGHTNING. THE SECOND IS ACROSS
THE NW PORTION OF THE REGION WHICH IS GENERALLY JUST SHOWERS. THIS
STORMS ARE DEVELOPING ALONG THE EDGE OF THE 700MB MOISTURE REGION.
EXPECT STORM TO CONTINUE TO DEVELOP AS MU CAPE VALUES ARE ABOVE
1000 J/KG ALONG WITH COOLER TEMPS ALOFT. AS SHORTWAVE CONTINUES TO
FIZZLE OUT...THESE TEMPS ALOFT WILL WARM HOWEVER WITH BREAKS IN
THE CLOUDS EXPECT...DIURNAL HEATING WILL HELP AID IN STORM
REDEVELOP THIS AFTERNOON. MAIN BULK OF THE FORECAST REMAINS ON
TRACK...MADE MINOR ADJUSTMENTS TO ACCOUNT FOR CURRENT CONDITIONS.
PREVIOUS DISCUSSION...
SHORT WAVE TROUGH OVER THE EASTERN GREAT LAKES AND NY STATE EARLY
THIS MORNING DEAMPLIFIES AS IT APPROACHES AND MOVES ACROSS NEW
ENGLAND TODAY. THIS IS EVIDENT IN WEAKENING WIND FIELDS
ALOFT...LESS CURVATURE IN THE MID LEVEL FLOW/STREAMLINES AND
WEAKENING Q-VECTOR CONVERGENCE ALONG AND AHEAD OF THE MID LEVEL
TROUGH. LAST FEW RUNS OF THE HRRR OFFER THE SAME THEME WITH
WEAKENING REFLECTIVITY AS CONVECTION APPROACHES NEW ENGLAND.
THEREFORE EXPECTING UPSTREAM CONVECTION ACROSS NY STATE AND VT TO
SLOWLY WEAKEN AS IT APPROACHES AND ENTERS SOUTHERN NEW ENGLAND.
HOWEVER THINK NEW CONVECTION WILL REFIRE OVER THE AREA THIS
AFTERNOON AS SOME SUNSHINE TODAY DESTABILIZES THE ATMOSPHERE WITH
THE MORE CONSERVATIVE ECMWF AND GEFS OFFERING CAPES ON THE ORDER OF
1200-1800J/KG. FAIRLY CONFIDENT IN THIS SCENARIO AS ALL MOS GUIDANCE
HAVE HIGH TEMPS TODAY IN THE LOW TO MID 80S...WITH WARMEST
READINGS ACROSS NORTHEAST MA AND SOUTHEAST NH. THIS INSTABILITY
COMBINED WITH WEAK BUT MOIST CYCLONIC FLOW ALOFT SHOULD BE
SUFFICIENT TO YIELD SCATTERED THUNDERSTORMS. HIGHEST PROBABILITY
WILL BE ACROSS THE INTERIOR...CLOSER TO FRONTAL BOUNDARY AND
SURFACE CONVERGENCE. THUS CONVECTION SHOULD BE LESS NUMEROUS ACROSS
SOUTHEAST MA /INCLUDING CAPE COD AND THE ISLANDS/ AND POSSIBLY INTO
BOSTON-PROVIDENCE CORRIDOR. MAIN ISSUE WITH ANY TSTMS TODAY WILL BE
HEAVY DOWNPOURS/FLOOD POTENTIAL WITH PWATS JUST UNDER 2 INCHES ALONG
WITH WEAK WINDS ALOFT RESULTING IN SLOW MOVING STORMS. TIMING OF
STORMS WILL BE AFTER 16Z AND SPECIFICALLY DURING PEAK HEATING FROM
18Z-21Z.
IT WILL BE WARM AND HUMID TODAY AS SOUTHERN NEW ENGLAND WILL BE IN
THE WARM SECTOR OF THE APPROACHING FRONTAL SYSTEM. DEW PTS WILL
CLIMB INTO THE U60S AND L70S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
TONIGHT...
EARLY EVENING SHOWERS/TSTMS ACROSS THE INTERIOR SHOULD DISSIPATE
WITHIN A FEW HOURS OF SUNSET GIVEN THE LACK OF DEEP LAYER SHEAR
AND MID LEVEL LAPSE RATES NEEDED TO SUSTAIN NOCTURNAL CONVECTION.
HOWEVER CAN/T RULE OUT ISOLATED OR WIDELY SCATTERED SHOWERS
OVERNIGHT GIVEN THE WEAK BUT MOIST CYCLONIC FLOW ALOFT.
SOUTHERN NEW ENGLAND REMAINS IN THE WARM SECTOR SO EXPECT PATCHY FOG
AND LOW CLOUDS. HIGH DEW PTS WILL YIELD ANOTHER MILD TO WARM NIGHT.
SUNDAY...
WEAK SHORT WAVE RIDGING MAY MOVE ACROSS THE REGION BEHIND
DEPARTING SHORT WAVE TROUGH OF TODAY AND BEFORE NEXT TROUGH
APPROACHES SUN NGT AND MON. THIS IS EVIDENT ON MODEL CROSS AND
TIME SECTIONS WITH COLUMN DRYING OUT IN THE MID AND UPPER LEVELS.
SO WHILE THERE IS STILL SOME UNCERTAINTY TO SUNDAY/S
FORECAST...THERE IS INCREASING CONFIDENCE THAT ANY SHOWER/TSTM
ACTIVITY WILL NOT BE WIDESPREAD. THUS NOT EXPECTING A WASHOUT
SUNDAY.
THE AREA REMAINS IN THE WARM SECTOR SO ANOTHER WARM AND MUGGY DAY
WITH HIGHS 80-85 AWAY FROM THE COAST ALONG WITH DEW PTS IN THE U60S
AND L70S.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
HIGHLIGHTS...
* SHOWERS AND THUNDERSTORMS LIKELY ON MONDAY AND INTO TUESDAY
* SLOW MOVING COLD FRONT WILL CROSS THE REGION ON TUESDAY
* FALL LIKE CONDITIONS FOR THE SECOND HALF OF THE WORK WEEK
CONFIDENCE LEVEL/MODEL GUIDANCE...
MODERATE CONFIDENCE IN OVERALL FORECAST. CONTINUE TO HAVE
INCREASING CONFIDENCE FOR THE TEMPERATURE ASPECT IN THE FORECAST.
MODERATE CONFIDENCE IN TIMING OF PRECIPITATION WITH HIGH
CONFIDENCE THAT PRECIP WILL OCCUR MONDAY AND EARLY TUESDAY. THE
00Z MODELS MAINTAIN A NEARLY STEADY-STATE TO SLIGHTLY RETROGRADING
PATTERN IN THE LOWER HALF OF THE CONUS WITH AN UPPER HIGH OVER THE
CENTRAL/SOUTHERN PLAINS. WHILE ACROSS THE NORTHEAST A PROGRESSIVE
FLOW INFLUENCED BY MULTIPLE SHORTWAVES AND FRONTAL PASSAGES WILL
RESULT IN GENERALLY COOLER TEMPERATURES. HOWEVER THE
DETAILS/TIMINGS ARE AN ISSUE DUE TO THE PATTERNS SHORT WAVELENGTH
AND POSSIBILITY OF PHASING. THAT BEING SAID FELT PERSISENT WAS A
GOOD WAY TO GO FOR THIS MORNINGS FORECAST. BLENDED PREVIOUS
FORECAST WITH WPC AND THE ENSEMBLES.
DETAILS...
MONDAY...
LONG WAVE TROUGH WILL SHARPEN UP ON MONDAY AS HUDSON BAY LOW
PRESSURE STRENGTHENS. THIS WILL KEEP THE REGION IN A SOUTHWEST
FLOW WITH INCREASING MOISTURE CAUSING VERY MUGGY CONDITIONS. MAIN
FOCUS IS A COLD FRONT ACROSS THE GREAT LAKES THAT WILL APPROACH
THE REGION. HOWEVER A SHORTWAVE WILL MOVE THROUGH THE FLOW ON
MONDAY WHICH WILL SPARK SOME SHOWERS AND THUNDERSTORMS. THE REGION
WILL BE IN THE WARM...MOIST SECTOR AS WELL AS THE BETTER JET
DYNAMICS. MAIN THREAT WITH THESE STORMS WILL BE HEAVY RAIN AS PWAT
VALUES WILL BE ABOVE 2 INCHES. THESE STORMS WILL BE SLOW MOVING
AND/OR TRAINING AS CORFIDI VECTORS ARE AROUND 0-5 KTS. NOTICED SPC
PUT THE REGION IN A SEE TEXT FOR DAY THREE OUTLOOK. HAVE LOW
CONFIDENCE IN OVERALL SEVERE WEATHER AS INSTABILITY VALUES WILL BE
LOWER THAN MODELS SUGGEST DUE TO THE AMOUNT OF CLOUDS ACROSS THE
AREA. THIS IDEA IS ALSO SUPPORTED BY THE ENSEMBLES. THEREFORE
BELIEVE THAT THE MAIN THREAT WILL STILL BE HEAVY RAIN CAUSING SOME
URBAN AND POOR DRAINAGE FLOODING. SMALL STREAMS MAY ALSO BE IN A
THREAT IF THUNDERSTORMS TRAIN OVER A CERTAIN REGION. THIS PORTION
OF THE FORECAST WILL NEED TO BE WATCHED CLOSELY OVER THE WEEKEND.
TUESDAY...
COLD FRONT WILL MOVE THROUGH SOUTHERN NEW ENGLAND ON TUESDAY.
MAIN QUESTION IS THE TIMING. IF THE FRONT SLOWS DOWN THEN THERE IS
A CHANCE FOR SHOWERS AND THUNDERSTORMS TO DEVELOP ESP ACROSS THE
EASTERN HALF OF THE REGION. IF THE FRONT SPEEDS UP THEN ONLY A FEW
SHOWERS MAY OCCUR AS THE FRONT EXITS OFFSHORE. REGARDLESS HAVE A
LOWER CONFIDENCE ON ANY STRONG STORMS ON TUESDAY AS BETTER JET
DYNAMICS WILL BE OFFSHORE. BOTH THE ENSEMBLES INDICATE THE BETTER
MOISTURE IS OFFSHORE AS WELL. TRENDED TOWARDS A FASTER SOLUTION ON
TUESDAY. A FEW HEAVY SHOWERS ARE STILL POSSIBLE WITH MAIN CONCERN
BEING NUISANCE FLOODING.
WEDNESDAY THROUGH FRIDAY...
LARGE-SCALE SUBSTANCES WILL FILTER IN BEHIND THE FRONT ON
WEDNESDAY. THIS WILL DROP DEWPOINTS DOWN INTO THE 40/50S MAKING IT
VERY COMFORTABLE. A FEW SHOWERS ARE POSSIBLE ACROSS THE NW ZONES
FROM WRAP AROUND MOISTURE FROM THE LOW. OTHERWISE EXPECT MOSTLY
DRY CONDITIONS. MODELS ARE INDICATING A POLAR FRONT WILL MOVE
THROUGH ON THURSDAY BRINGING SOME ISOLATED/SCATTERED SHOWERS. HAVE
A LOWER CONFIDENCE AS THERE IS A GOOD AMOUNT OF DRY AIR ACROSS THE
AREA. BEHIND THIS FRONT IS A MORE FALL LIKE AIRMASS BRINGING
OVERNIGHT LOWS IN THE 40S AND HIGHS ONLY IN THE 60S.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW...LOW TO MODERATE CONFIDENCE ON EXACT DETAILS INCLUDING
TIMING...BUT HIGHER CONFIDENCE ON OVERALL FORECAST THEME. CIGS AND
VSBYS WERE DERIVED FROM A BLEND OF NAM AND GFS MOS.
TODAY...
IFR CIGS SHOULD BE CONFINED TO SOUTHEAST MA AND RI. THIS SHOULD
IMPROVE TO VFR 14Z-16Z. SHOWERS AND TSTMS THIS MORNING WILL SLOWLY
WEAKEN. ADDITIONAL SHOWERS AND TSTMS WILL DEVELOP AFTER 16Z
MAINLY INLAND WITH DAYTIME HEATING COMMENCING. LESS SHOWER/TSTM
ACTIVITY ACROSS SOUTHEAST MA/CAPE COD AND ISLANDS.
TONIGHT...
ALMOST A REPEAT PERFORMANCE...IFR IN LOW CLOUDS CONFINED TO
SOUTHEAST MA AND RI WITH MVFR/VFR ELSEWHERE. ISOLATED/SCATTERED
SHOWERS SHOULD BE MOST NUMEROUS WELL INLAND.
SUNDAY...
IFR SOUTHEAST MA AND RHODE ISLAND BUT IMPROVING TOWARD MIDDAY TO
VFR. VFR ELSEWHERE. NOT EXPECTING WIDESPREAD SHOWERS/TSTMS...MORE
ISOLATED TO WIDELY SCATTERED.
KBOS TERMINAL...IFR CIGS ACROSS SOUTHEAST MA MAY CLIP LOGAN 09Z-
13Z BUT BULK OF LOW CLOUDS SHOULD SLIDE SOUTH OF THE AIRPORT. MOST
SHOWER ACTIVITY SHOULD BE WEST AND NORTH OF BOSTON.
KBDL TERMINAL...SHOWERS/TSTMS WILL BECOME MORE NUMEROUS 16Z-22Z.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...
SUNDAY NIGHT...MODERATE CONFIDENCE. EXPECT MAINLY MVFR CIGS/VFR
VSBYS. AREAS MVFR VSBYS IN ANY SHOWERS/TSTMS. LOCAL IFR VSBYS IN
ANY HEAVIER RAINFALL.
MONDAY-TUESDAY...LOW CONFIDENCE MAINLY FOR TIMING. MVFR
CONDITIONS WITH IFR IN SHOWERS/TSTMS. PERIODS OF HEAVY RAINFALL
WILL REDUCE VSBYS AS WELL.
WEDNESDAY...HIGH CONFIDENCE. MVFR TO START...IMPROVING TO VFR BY
THE AFTERNOON HOURS.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
TODAY THROUGH SUNDAY...
MODEST SW WIND 10-15 KT WITH LOW RISK OF 20 KT GUST. WARM/MUGGY
AIRMASS WILL YIELD LATE NIGHT/EARLY MORNING FOG. SHOWERS/TSTMS WILL
BE MAINLY INLAND. FORECAST CONFIDENCE MODERATE TO HIGH.
OUTLOOK...MONDAY THROUGH WEDNESDAY...
PERSISTENT SOUTHERLY SWELL COMBINED WITH AN APPROACHING COLD
FRONT WILL CAUSE SEAS TO BUILD UP TO 5 FT ESP ACROSS THE OUTER
WATERS THROUGH TUESDAY. BELIEVE THIS IS A LITTLE HIGH SO HAVE
UNDERCUT WAVE GUIDANCE TO TOP OUT AT 4FT. LOW PROB FOR GUSTS UP TO
25 KT AHEAD OF COLD FRONT MON NIGHT AND EARLY TUE. EXPECT COLD
FRONT TO MOVE ACROSS WATERS LATE TUE/TUE NIGHT. WINDS/SEAS SHOULD
SLOWLY DIMINISH DURING WED. BEST CHANCE FOR THUNDERSTORMS WILL BE
MONDAY INTO TUESDAY MORNING.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...NOCERA/DUNTEN
NEAR TERM...NOCERA/DUNTEN
SHORT TERM...NOCERA
LONG TERM...DUNTEN
AVIATION...NOCERA/DUNTEN
MARINE...NOCERA/DUNTEN
AREA FORECAST DISCUSSION
NWS ALBANY NY
656 AM EDT SAT AUG 31 2013
.SYNOPSIS...
A WARM AND HUMID AIR MASS WILL IMPACT EASTERN NEW YORK
AND WESTERN NEW ENGLAND THROUGH THE HOLIDAY WEEKEND. A SERIES OF
WEAK DISTURBANCES MOVING ALONG A FRONTAL BOUNDARY NEAR THE SAINT
LAWRENCE RIVER VALLEY WILL PRODUCE SHOWERS AND THUNDERSTORMS TODAY
WITH SOME LOCALLY HEAVY RAINFALL. THE UNSETTLED WEATHER CONTINUES
LATE SUNDAY INTO LABOR DAY WHEN A STRONG UPPER LEVEL LOW BRINGS MORE
WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS TO THE REGION.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 655 AM EDT...THE LAST FULL DAY OF AUGUST AND METEOROLOGICAL
SUMMER BEGAN WITH SHOWERS AND SCT THUNDERSTORMS ACROSS PORTIONS OF
THE ALY FCST AREA...ESPECIALLY FROM THE NRN CATSKILLS...CAPITAL
REGION AND SRN VT NORTHWARD. A COUPLE OF WEAK SFC LOWS ARE MOVING
ALONG A STATIONARY FRONT NEAR THE ST LAWRENCE RIVER VALLEY AND ERN
GREAT LAKES THIS MORNING. LOW-LEVEL CONVERGENCE WITH THE SFC LOWS
HAS HELPED THE SHOWERS AND THUNDERSTORMS BE THE MOST PERSISTENT IN
THE MOHAWK RIVER VALLEY...SRN DACKS...AND THE LAKE GEORGE SARATOGA
REGION. THIS ACTIVITY WILL CONTINUE TO WANE EARLY THIS MORNING...AND
A BRIEF LOW WILL OCCUR TOWARDS NOONTIME. THE POPS WERE RETRENDED
THIS MORNING BASED ON THE RADAR TRENDS.
A MAJORITY OF THE GUIDANCE SHOWS ANOTHER WEAK RIPPLE OF LOW
PRESSURE MOVING ALONG THE BOUNDARY IN THE AFTERNOON WITH A MID
LEVEL SHORT-WAVE IN THE W/SW FLOW ALOFT. IT IS QUESTIONABLE IF ANY
SIGNIFICANT HEATING WILL OCCUR EXCEPT PERHAPS ALONG THE SRN TIER
OF THE FCST AREA /MID HUDSON VALLEY AND NW CT/. THE 0-6 KM DEEP
SHEAR IS WEAK WITH WEAK MID LEVEL LAPSE RATES ALOFT...SO
WIDESPREAD SEVERE CONVECTION IS NOT ANTICIPATED DESPITE SBCAPE
VALUES OF 1000-2000 J/KG ACCORDING THE NAM/GFS. H850 THETA-E
VALUES WILL BE GENERALLY IN THE 335-340K RANGE. THE PWATS WILL BE
IN THE 1.25-1.75 INCH RANGE /1 TO 2 STANDARD DEVIATIONS ABOVE
NORMAL/...SO LOCALLY HVY RAINFALL WILL BE THE MAIN ISSUE. THE
ENHANCED WORDING WAS PUT IN THE GRIDS...AND WILL BE MENTIONED IN
THE HWO. IF THE HIGHER CAPE VALUES ARE REALIZED...AN ISOLATED WET
MICROBURST MAY BE POSSIBLE. THE MAIN THREAT CONTINUES TO BE HEAVY
RAINFALL. THE HIGHEST POPS IN THE LIKELY RANGE WERE USED ACROSS
THE NRN HALF OF THE FCST AREA.
THE 07Z 3KM HRRR COLUMN REF PRODUCT SHOWS DISCRETE CONVECTIVE
ELEMENTS FORMING INTO A LINE OVER THE HUDSON RIVER VALLEY IN THE
MID AFTERNOON. IN A WEAK SHEAR ENVIRONMENT THIS APPEARS TO BE OFF
SOME...BUT WILL HAVE TO BE MONITORED. LATER RUNS HAVE SHOWN LESS
SIGNIFICANT COVERAGE AND ORGANIZATION.
THE SFC DEWPTS WILL REMAIN IN THE 60S WITH PERHAPS SOME SPOTTY
LOWER 70S OVER THE SRN TIER. THE AIR MASS WILL BE STICKY FOR THE
LAST DAY OF AUGUST. MINIMAL HEATING SHOULD ALLOW FOR U70S TO L80S
IN THE VALLEYS...WITH 70S OVER THE HILLS AND MTNS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
TONIGHT...THE SHOWERS AND THUNDERSTORMS SHOULD DIMINISH IN THE
EARLY EVENING WITH THE WEAK SFC WAVE MOVING EAST/NORTHEAST OF THE
REGION...AND THE MID LEVEL SHORT-WAVE PASSING DOWNSTREAM. THE
FRONTAL BOUNDARY MAY MOVE OVER THE NRN HALF OF THE FCST AREA AND
FALL APART. THE POPS WERE LOWERED TO SLIGHT CHC VALUES AFTER
MIDNIGHT. IT WILL REMAIN VERY HUMID WITH LOWS IN THE MID AND U60S
OVER MOST OF THE REGION...EXCEPT OVER THE MTNS.
SUNDAY...THE ENTIRE DAY SHOULD NOT BE A WASHOUT WITH AN AMPLIFYING
UPPER LEVEL TROUGH OVER ONTARIO AND THE GREAT LAKES REGION. THE
MID LEVEL FLOW WILL BECOME SOUTHWESTERLY OVER NY AND NEW ENGLAND
WITH WEAK RIDGING ALOFT. THEIR ARE NOT ANY REAL ROBUST SYNOPTIC
TRIGGER MECHANISMS DURING THE DAY. AIR MASS OR DIFFERENTIAL
HEATING THUNDERSTORMS ARE POSSIBLE. A SLIGHT TO LOW CHANCE OF
SHOWERS AND THUNDERSTORMS WAS INCLUDED IN THE GRIDS. H850 TEMPS
INCREASE TO +16C TO +17C WITH PARTLY SUNNY CONDITIONS. MAX TEMPS
WILL RUN ABOUT 5-10 DEGREES ABOVE NORMAL TO OPEN SEPT.
SUNDAY NIGHT INTO LABOR DAY...A LARGE TROUGH OF LOW PRESSURE
IMPACTS THE REGION. SEVERAL MID LEVEL SHORT-WAVES ROTATING AROUND
THE CLOSED LOW SOUTH OF JAMES BAY WILL YIELD UNSETTLED WX DURING
THIS TIME FRAME. IT IS DIFFICULT TO DETERMINE IF ANY ROBUST SFC
HEATING WILL OCCUR AT THIS TIME. THE STRONG SYNOPTIC LIFT WITH THE
TROUGH WILL LIKELY YIELD PERIODS OF SHOWERS AND SCT THUNDERSTORMS.
SOME HVY RAINFALL LOOKS LIKE A GOOD BET. THE QG LIFT INCREASES
LABOR DAY AFTERNOON...AS THE NRN HALF OF THE FCST AREA GETS NEAR
THE RIGHT ENTRANCE REGION OF A H250 JET STREAK WITH STRONG UPPER
LEVEL DIVERGENCE ALOFT. PWATS CONTINUE ABOVE NORMAL FOR EARLY
SEPT. LIKELY POPS WERE CONTINUED ON MONDAY. THE COOLER NAM MOS
TEMPS WERE ALSO FOLLOWED CLOSELY WITH THE AMOUNT OF CLOUD COVER
AND NUMEROUS SHOWERS EXPECTED. MAX TEMPS WILL BE HARD PRESSED TO
GET OUT OF THE 70S WITH PERHAPS SOME 80F READINGS FROM THE CAPITAL
REGION SOUTH IN THE MID HUDSON VALLEY.
MONDAY NIGHT...LOW AND MID LEVEL HEIGHTS CONTINUE TO FALL...AS THE
TROUGH OF LOW PRESSURE AND ITS ASSOCIATED COLD FRONT MIGRATE EAST
OF THE REGION. A CHC OF SHOWERS WAS KEPT IN MOST OF THE OVERNIGHT.
LOW LEVEL COLD ADVECTION IS EXPECTED WITH TEMPS FALLING INTO THE
50S OVER THE MTNS WITH LOWER TO MID 60S IN THE VALLEYS.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
COOLER AND LESS ACTIVITY WEATHER AS WE HEAD THROUGH THE FIRST WEEK
OF SEPTEMBER.
THE MODEL GUIDANCE IS IN FAIRLY GOOD AGREEMENT REGARDING THE
LONGWAVE PATTERN WITH THE NORTHEAST REMAINING UNDER A TROUGH AND
THE RIDGE HOLDING ON OVER THE PLAIN STATES.
A COUPLE OF COLD FRONTS WILL MOVE ACROSS THE REGION. THE FIRST ONE
IS EXPECTED TO MOVE OFF TO OUR EAST ON TUESDAY WITH SOME LINGERING
SHOWERS POSSIBLE MAINLY DURING THE MORNING. A PLEASANT DAY EXPECTED
WEDNESDAY AS HIGHER PRESSURE BUILDS IN WITH SEASONABLE WARM
TEMPERATURES. A SECONDARY COLD FRONT IS EXPECTED TO MOVE THROUGH
THURSDAY WITH ISOLATED SHOWERS. A MORE AUTUMN-LIKE AIRMASS WILL BE
USHERED IN AS CANADIAN HIGH PRESSURE BUILDS IN ITS WAKE OF THE FRONT
TO CLOSE OUT THE WEEK. TEMPERATURES THURSDAY AND FRIDAY ARE
ANTICIPATED TO RUN ABOUT 5 DEGREES BELOW NORMAL.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
SHOWERS AND ISOLATED THUNDERSTORMS CONTINUE TO MOVE EASTERLY ACROSS
THE FORECAST AREA EARLY THIS MORNING IN ASSOCIATION WITH AN
APPROACHING SHORT WAVE TROUGH AND WEAK SURFACE LOW MOVING INTO THE
SAINT LAWRENCE RIVER VALLEY. EXPECTING A LULL IS THE PRECIPITATION
FOR A BIT THIS MORNING MAINLY AFTER SUNRISE AS THE SHORT WAVE TROUGH
MOVES OFF TO THE EAST. HOWEVER...CHANCES FOR CONVECTION WILL
INCREASE LATER THIS MORNING AND ESPECIALLY DURING THE AFTERNOON
HOURS AS THE SURFACE LOW PASSES TO OUR NORTH AND ANOTHER SHORT WAVE
TROUGH APPROACHES. WITH THE HELP OF DAYTIME HEATING AND INCREASED
INSTABILITY THERE WILL BETTER AND WIDESPREAD CHANCES FOR
THUNDERSTORMS SO HAVE INCLUDED MENTION IN THE TAFS.
EXPECTING SOME MVFR FOG AND CIGS EARLY THIS MORNING WITH CONDITIONS
IMPROVING AFTER SUNRISE. EXPECTING MAINLY VFR CONDITIONS DURING THE
DAY WITH MVFR/BRIEF IFR CONDITIONS WITH ANY CONVECTION THAT IMPACTS
TAF SITES. MVFR FIG IS EXPECTED TO DEVELOP AGAIN THIS EVENING
ESPECIALLY WHERE IT RAINS.
OUTLOOK...
SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
LABOR DAY: HIGH OPERATIONAL IMPACT. LIKELY SHRA...TSRA.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
TUESDAY: LOW OPERATIONAL IMPACT. CHANCE OF SHRA.
TUESDAY NIGHT-WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.FIRE WEATHER...
NO FIRE WEATHER PROBLEMS ARE EXPECTED IN THE HUMID AIR MASS WITH
SEVERAL CHANCES OF RAINFALL.
A SERIES OF WEAK DISTURBANCES MOVING ALONG A FRONTAL BOUNDARY
NEAR THE SAINT LAWRENCE RIVER VALLEY WILL PRODUCE SHOWERS AND
THUNDERSTORMS TODAY WITH SOME LOCALLY HEAVY RAINFALL. THE
UNSETTLED WEATHER CONTINUES LATE SUNDAY INTO LABOR DAY WHEN A
STRONG UPPER LEVEL LOW BRINGS MORE WIDESPREAD SHOWERS AND
SCATTERED THUNDERSTORMS TO THE REGION.
THE RH VALUES WILL ONLY DROP TO BETWEEN 50 AND 85 PERCENT THIS
AFTERNOON...AND RECOVER TO CLOSE TO 100 PERCENT SUNDAY MORNING.
HIGH RH VALUES OF 55 TO 75 PERCENT WILL OCCUR SUNDAY AFTERNOON.
THE WINDS WILL BE FROM THE SOUTH TO SOUTHWEST AT 5 TO 15 MPH TODAY
AND TOMORROW... AND BECOME LIGHT TO CALM TONIGHT.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO PROBLEMS ARE ANTICIPATED THE NEXT 5 DAYS ON
THE MAIN STEM RIVERS. HEAVY RAINFALL WITH LOCALIZED IMPACTS WILL BE
POSSIBLE TODAY THROUGH LABOR DAY FROM SHOWERS AND THUNDERSTORMS.
THE BEST CHANCE FOR WIDESPREAD RAINFALL WILL BE TODAY AND ON
LABOR DAY.
HUMID CONDITIONS WILL PERSIST...SO LOCALIZED DOWNPOURS CAN BE
EXPECTED WITH THUNDERSTORMS. ISOLATED URBAN...SMALL STREAM...AND
POOR DRAINAGE FLOODING WILL BE POSSIBLE DURING THE HOLIDAY
WEEKEND. SOME WITHIN BANK RISES ARE POSSIBLE ON LARGER STREAMS
WHERE SHOWERS AND STORMS OCCUR. ZONAL FFG VALUES REMAIN HIGH
DURING THIS TIME FRAME. HOWEVER...A QUICK INCH OR TWO OF RAINFALL
FROM A SLOW MOVING THUNDERSTORM MAY PRODUCE AN ISOLATED FLASH
FLOOD DURING THE HOLIDAY WEEKEND.
RAINFALL AMOUNTS WILL BE QUITE VARIABLE DUE TO THE SHOWERY NATURE
OF THE RAIN...WITH SOME LOCATIONS RECEIVING OVER AN INCH OF RAIN
WHILE OTHERS REMAIN DRY. SOME AREAS NORTH OF THE CAPITAL REGION
HAVE RECEIVED A HALF AN INCH TO AN INCH OF RAINFALL THIS MORNING.
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...WASULA
NEAR TERM...WASULA
SHORT TERM...WASULA
LONG TERM...IAA
AVIATION...IAA
FIRE WEATHER...WASULA
HYDROLOGY...SND/WASULA
AREA FORECAST DISCUSSION
NWS MIAMI FL
1002 AM EDT SAT AUG 31 2013
...MORE THUNDERSTORMS EXPECTED THIS AFTERNOON THAN RECENT DAYS...
.UPDATE...THE MORNING MIAMI SOUNDING SHOWS SUBSTANTIAL MOISTENING
HAS OCCURRED IN THE LOWEST 10K FT. SO THE DRY LAYER OF THE PAST
COUPLE OF DAYS HAS DIMINISHED. GIVEN THIS MOISTENING, THE
EXPECTATION FOR THIS AFTERNOON IS FOR A HIGHER COVERAGE OF SHOWERS
AND THUNDERSTORMS ACROSS SOUTH FL. HRRR SHOWS CONVECTION
DEVELOPING AFTER 1 PM ACROSS THE EAST COAST METRO AREAS JUST
INLAND FROM THE COAST WITH A TRANSITION OVER THE INTERIOR THROUGH
EARLY THIS EVENING WITH ACTIVITY BECOMING NUMEROUS THERE. THIS
LOOKS REASONABLE SO HAVE UPDATED THE FORECAST TO REFLECT THIS
TREND.
LAPSE RATES ARE RATHER WEAK AND INSTABILITY IS NOT TOO
HIGH, AND WITH NO PRONOUNCED DRY LAYER, WE ARE EXPECTING MAINLY
ORDINARY THUNDERSTORMS WITH LIGHTNING STRIKES AND HEAVY DOWNPOURS
BEING THE PRIMARY IMPACTS. /GREGORIA
&&
.PREV DISCUSSION... /ISSUED 643 AM EDT SAT AUG 31 2013/
AVIATION...
AN UPPER LEVEL LOW WILL CONTINUE TO BRING UNCERTAINTY IN THE
FORECAST FOR SOUTH FLORIDA. AS IT DRIFTS AROUND THE AREA, IT WILL
ALLOW SOME CONVECTION TO INITIATE THROUGH THE DAY, WITH THE BEST
CHANCES IN THE AFTERNOON. WHILE THE MOST LIKELY AREAS WILL BE THE
INTERIOR AND THE LAKE REGION, SOME MODELS ARE NOW INDICATING THE
ATLANTIC COASTAL TAF SITES MAY AT LEAST SEE SOME SHOWERS AROUND.
SO, HAVE ADDED VCSH BACK INTO THE FORECAST FOR THOSE SITES FOR
THIS AFTERNOON. VCTS IS STILL A SMALL POSSIBILITY, BUT CURRENTLY
TOO SMALL TO PUT IN THE TAF FORECAST AT THIS TIME.
GENERALLY SOUTHERLY WINDS WILL CONTINUE TODAY, PICKING UP TO 5 TO
10 KTS MID DAY. THEY WILL BECOME LIGHT AND VARIABLE AGAIN TONIGHT,
WITH MOST LIKELY SOUTHERLY DIRECTION SOMEWHAT FAVORED.
PREV DISCUSSION... /ISSUED 243 AM EDT SAT AUG 31 2013/
.ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS POSSIBLE FOR
THE HOLIDAY WEEKEND...
SHORT TERM...
AN UPPER LEVEL LOW WILL REMAIN OVER SOUTH FLORIDA TODAY INTO
SUNDAY...AS WEAK HIGH PRESSURE REMAINS OVER THE WESTERN ATLANTIC
WATERS. THIS WILL ALLOW FOR A STEERING FLOW OVER SOUTH FLORIDA TO
BE FROM THE SOUTHERLY DIRECTION WHICH WILL FOCUS THE SHOWER AND
THUNDERSTORM ACTIVITY OVER THE LAKE OKEECHOBEE REGION TODAY AND
AGAIN ON SUNDAY.
THE DRY AIR WAS STILL LOCATED BETWEEN THE 850 MB AND 700 MB IN
FRIDAY THE 00Z MIA SOUNDING. THIS DRY AIR WILL REMAIN IN PLACE
TODAY INTO SUNDAY HELPING TO REDUCE THE SHOWER AND THUNDERSTORM
ACTIVITY OVER SOUTH FLORIDA. THEREFORE...THE POPS OVER SOUTH
FLORIDA WILL RANGE FROM 20 PERCENT OVER THE SOUTHERN AREAS TO 40
PERCENT OVER THE LAKE OKEECHOBEE AREA FOR TODAY AND AGAIN ON
SUNDAY.
THE UPPER LEVEL LOW EXPECTED MOVE WEST ON LABOR DAY INTO THE GULF
WATERS OF MEXICO...AS THE HIGH OVER THE WESTERN ATLANTIC WATERS
BUILDS BACK INTO THE FLORIDA PENINSULA. THIS WILL ALLOW FOR THE
DRY AIR BETWEEN THE 700 MBS AND 850 MBS TO MOISTEN UP ALONG WITH
THE STEERING FLOW BECOMING MORE SOUTHEAST OVER THE AREA. THE SEA
BREEZES WILL ALSO DEVELOP AND PUSH INLAND. SO THE POPS WILL BE
INCREASED TO SCATTERED COVERAGE WITH THE HIGHEST POPS OVER THE
INTERIOR AREAS FOR LABOR DAY.
LONG TERM...
THE HIGH OVER THE WESTERN ATLANTIC WATERS WILL CONTINUE TO
STRENGTHEN OVER THE WESTERN ATLANTIC WATERS AND EXTEND INTO THE
FLORIDA PENINSULA MIDDLE TO END OF NEXT WEEK. THIS WILL ALLOW FOR
THE EASTERLY WIND FLOW TO REMAIN IN PLACE OVER SOUTH FLORIDA
FOR MIDDLE TO END OF NEXT WEEK ALONG WITH THE DAILY SEA BREEZE
DEVELOPMENT. SO WILL CONTINUE THE SCATTERED POPS OVER SOUTH
FLORIDA WITH THE BEST COVERAGE OVER THE INTERIOR AND WEST COAST
METRO AREAS FOR MIDDLE TO END OF NEXT WEEK.
THERE IS ALSO A TROPICAL WAVE OVER THE CENTRAL ATLANTIC WATERS
THAT IS FORECAST BY THE LONG RANGE MODELS TO MOVE WEST-NORTHWEST
NEXT WEEK...AND POSSIBILITY OVER SOUTH FLORIDA BY END OF NEXT
WEEK. IF THIS TREND CONDITIONS THEN THE POPS MAY HAVE TO BE RAISED
UP FOR END OF NEXT WEEK.
MARINE...
THE WINDS OVER SOUTH FLORIDA WATERS THIS LABOR DAY WEEKEND WILL BE
FROM THE SOUTH-SOUTHWEST DIRECTION AT 5 TO 10 KNOTS SWINGING TO A
EASTERLY DIRECTION BY LABOR DAY. THIS WILL KEEP THE SEAS IN BOTH
THE ATLANTIC AND GULF WATERS AT 2 FEET OR LESS. SO BOATING
CONDITIONS OVER SOUTH FLORIDA THIS LABOR DAY WEEKEND SHOULD BE
GOOD OUTSIDE OF ANY SHOWERS OR THUNDERSTORMS.
THE THREAT OF RIP CURRENTS THIS LABOR DAY WEEKEND AT BOTH THE
ATLANTIC AND GULF COAST BEACHES OF SOUTH FLORIDA LOOKS LOW AT
THIS TIME AS THE WINDS WILL BE 10 KNOTS OR LESS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 91 77 91 78 / 30 20 30 20
FORT LAUDERDALE 90 79 90 80 / 20 20 20 20
MIAMI 91 78 91 79 / 30 20 20 20
NAPLES 90 75 90 76 / 20 20 20 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
852 AM MDT SAT AUG 31 2013
.UPDATE...
ISSUED AT 852 AM MDT SAT AUG 31 2013
MAIN CHANGE WAS TO ADD MENTION OF THUNDERSTORMS TO FORECAST FOR
THE MORNING PERIOD. RADAR HAS BEEN SHOWING 20-35 DBZ RETURNS
ACROSS MUCH OF THE AREA THIS MORNING...HOWEVER THIS IS MAINLY
VIRGA. RECENT RETURNS HOWEVER HAVE SHOWN BRIEF/ISOLATED CORES OVER
40-45DBZ...WHICH WOULD PROBABLY BE ENOUGH FOR MEASURABLE PRECIP
IN THE CURRENT ENVIRONMENT. WITH SHORTWAVE STILL OVER CENTRAL
NEBRASKA (HIGHLIGHTED BY STRONG PV HEIGHT ANOMALY ON RAP ANALYSIS)
AND STALLED FRONT ALONG THE KS/NE BORDER WE COULD CONTINUE TO SEE
THIS ISOLATED ACTIVITY THROUGH MIDDAY. MODELS SHOW A GENERAL
CLEARING TREND THROUGH NOON BEFORE ACTIVITY BEGINS REDEVELOPING IN
THE WEST...SO I ONLY ADJUSTED TIMING OF CLOUD COVER AND MORNING
POPS. I WILL HAVE TO MONITOR WHAT IMPACT CLOUDS WILL HAVE ON
HIGHS TODAY IF THEY CONTINUE TO LINGER.
&&
.SHORT TERM...(TODAY THROUGH MONDAY NIGHT)
ISSUED AT 346 AM MDT SAT AUG 31 2013
MAIN FORECAST PROBLEM WILL BE PRECIPITATION THROUGH THE WEEKEND...
HOW HOT TO MAKE TODAY...AND HOW MUCH TO COOL DOWN TEMPERATURES
SUNDAY. SATELLITE SHOWING AN AMPLIFIED FLOW OVER THE EASTERN PACIFIC
WITH A FLATTER FLOW OVER THE COUNTRY. MID/UPPER LEVEL RIDGE THAT HAS
PERSISTED FOR A WHILE HAS BEEN FLATTENED AND PUSHED SOUTH BY
SHORTWAVES GOING ACROSS THE TOP OF IT. LOOKS LIKE WE HAVE A BETTER
SUBTROPICAL MOISTURE CONNECTION ACROSS THAN 24 HOURS AGO.
COMPLICATED SURFACE PATTERN WITH A FRONT THAT HAS SAGGED INTO THE
NORTHERN PORTION OF THE AREA. COMBINATION OF THIS BOUNDARY...WEAK
SHORTWAVE TROUGH...AND RIGHT REAR QUADRANT OF THE JET BROUGHT
THUNDERSTORMS TO THE NORTHERN HALF OF THE AREA WITH THE GREATEST
CONCENTRATION NEAR THE KANSAS AND NEBRASKA BORDER. THESE STORMS HAVE
THROWN OUT NUMEROUS OUTFLOW BOUNDARIES.
AT JET LEVEL...MODELS WERE HAVING A LITTLE TROUBLE WITH THE JET
SEGMENT JUST TO OUR NORTH. THEY DID NOT HAVE THE STRONGER WINDS FAR
ENOUGH SOUTH. HERE THE NAM WAS DOING A LITTLE BETTER THAN UKMET...
GFS..AND CANADIAN. AT MID LEVELS...THE CANADIAN AND UKMET WERE
DOING A LITTLE BETTER THAN THE GFS. OUTSIDE OF THE MESOSCALE
INFLUENCES THE CANADIAN WAS DOING THE BEST ON THE LOW LEVEL WIND
AND PRESSURE FIELD. THE GFS WAS DOING A LITTLE BETTER THAN THE
CANADIAN AND SREF ON THE LOW LEVEL THERMAL FIELD.
TODAY/TONIGHT...WEAK RIGHT REAR QUADRANT IS AFFECTING THE AREA NOW
AND IT MAY STILL BE NEAR OR OVER THE NORTHERN PORTION OF THE AREA AT
12Z. THIS WEAKENS OR PULLS AWAY FROM THE AREA AS STRONGER JET
DEVELOPS TO OUR NORTH WITH THE RIGHT FRONT QUADRANT AFFECTING THE
AREA IN THE AFTERNOON. INITIAL SHORTWAVE TROUGH ALSO LOOKS LIKE IT
MOVES EAST OF THE AREA THIS MORNING. BASED ON WHERE CURRENT
THUNDERSTORMS ARE OCCURRING BELIEVE THOSE STORMS SHOULD BE OUT OF
THE AREA BY 12Z. IT IS POSSIBLE THAT THERE MAY BE SOME
THUNDERSTORMS IN THE EAST EARLY. WILL MONITOR AS LONG AS POSSIBLE
BEFORE MAKING THE FINAL DECISION.
HOW MUCH DO CLOUDS HANG AROUND AND OVERNIGHT OUTFLOW BOUNDARIES WILL
AFFECT ALL PARAMETERS OF THE FORECAST. DAY SHIFT WILL HAVE TO PIN
WHERE OUTFLOW BOUNDARIES END UP AND MAY NEED TO ADJUST THE AREA OF
PRECIPITATION. TREND FOR THE INCOMING FRONT AND MID/UPPER LEVEL
SUPPORT HAS BEEN TO BE SLOWER. SO MADE ADJUSTMENTS TO THE
PRECIPITATION GRIDS TO REFLECT THIS. IF MESOSCALE DOES NOT CHANGE
THINGS...THEN EXPECT PRECIPITATION TO DEVELOP IN THE NORTHWEST HALF
IN THE AFTERNOON AND CONTINUE SOUTH AND EAST ACROSS THE AREA INTO
THE OVERNIGHT HOURS.
THIS INITIAL ROUND OF PRECIPITATION WILL BE TIED TO FRONT AND
SHORTWAVE TROUGH. THEN THE ABOVE MENTIONED JET LOOKS TO STAY NORTH OF
THE AREA THROUGH THE EVENING BEFORE COMING SOUTH AFTER 06Z. MOST OF
THE NORTHERN HALF LOOKS TO BE IN THE RIGHT REAR QUADRANT BY 12Z. THIS
IS FURTHER NORTH AT THIS TIME THAN WHAT THE MODELS WERE SHOWING
YESTERDAY. SO EXPECT SOME REDEVELOPMENT FURTHER NORTH BEHIND THE
FRONT.
IF CLOUDS HANG AROUND LONGER...WHICH RIGHT NOW THEY LOOK LIKE THEY
ARE THINNING...AND THE AIR MASS RECOVERS THE OVERNIGHT CONVECTION...
HOT TEMPERATURES ARE EXPECTED AGAIN...ESPECIALLY IN THE SOUTHEAST
PORTION.
SUNDAY/SUNDAY NIGHT...ABOVE MENTIONED JET MOVES ACROSS THE AREA
DURING THE DAY BUT MODELS DIFFER ON HOW FAST. MOST OF THEM HAVE THE
RIGHT REAR QUADRANT STILL AFFECT THE SOUTHERN PORTION OF THE AREA
AT 18Z WITH THE GFS FURTHER NORTH AND AFFECTING MOST OF THE AREA. BY
LATE IN THE AFTERNOON SOME KIND OF JET LIFT IS STILL AROUND OVER THE
SOUTHERN PORTION OF THE AREA. ALL THIS LOOKS TO MOVE SOUTH OF THE
AREA DURING THE EARLY EVENING. PER THE TRENDS AND REASONING MENTIONED
ABOVE...HELD ONTO HIGHER CHANCES PRECIPITATION CHANCES IN THE
MORNING WITH PRECIPITATION POSSIBLY LINGERING INTO THE EARLY
AFTERNOON IN THE FAR SOUTHERN PORTION.
HIGH TEMPERATURES WILL BE MUCH COOLER DUE TO LINGERING
PRECIPITATION/CLOUD COVER...AND UPSLOPE WINDS/COLD AIR ADVECTION.
BASED ON RECENT TRENDS/BEST PERFORMING GUIDANCE ALONG WITH THE
EXPECTED COOLING AT 850 MB...ADJUSTED THOSE TEMPERATURES A LITTLE...
ESPECIALLY COOLER WHERE CLOUDS HANG ON THE LONGEST. CLOUDS LOOK TO
CLEAR OUT OF MOST AREA EXCEPT POSSIBLY THE FAR SOUTHWEST. WINDS
BECOME LIGHT...ESPECIALLY IN THE EAST...SO LOWERED PREVIOUS MIN
FORECAST TO ACCOUNT FOR THIS.
MONDAY/MONDAY NIGHT...MID/UPPER LEVEL RIDGING AND DRIER AIR ALOFT
START BUILDING INTO THE AREA. ALSO PRESSURE GRADIENT INCREASES AS
SURFACE HIGH PULLS OFF TO THE EAST AND LEE TROUGH REDEVELOPS. SO
THIS AND PLENTY OF SUN SHOULD ALLOW TEMPERATURES TO RECOVER FROM
THE PREVIOUS DAY. A WEAK SHORTWAVE TROUGH AND INSTABILITY TRIES TO
SNEAK INTO THE FAR WESTERN PORTION OF THE AREA...ESPECIALLY DURING
THE NIGHT. DUE TO THE INCREASING HEIGHTS AND AIR MASS LOOKING TO BE
CAPPED THERE...KEPT IT DRY.
.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 211 AM MDT SAT AUG 31 2013
UPPER LEVEL BLOCKING PATTERN WILL CONTINUE OVER THE HIGH PLAINS FOR
THE EXTENDED FORECAST PERIOD...WHICH WILL KEEP WARM AND DRY
CONDITIONS OVER THE FORECAST AREA. THE 500 MB HIGH PRESSURE AREA
WILL BE CENTERED OVER COLORADO FOR TUESDAY AS RIDGE BECOMES MORE
AMPLIFIED INTO THE NORTHERN HIGH PLAINS. ZONAL FLOW WILL BEGIN TO
ENTER THE CENTRAL PLAINS FOR NEXT WEEKEND AS AN UPPER LEVEL LOW
MOVES OUT OF ALBERTA AND ACROSS THE NORTHERN PLAINS. SHORTWAVE
TROUGHS COULD DEVELOP AND MOVE THROUGH THE TRI STATE AREA SATURDAY
AND SUNDAY AS UPPER LEVEL HEIGHTS INCREASE AND RIDGE OF HIGH
PRESSURE BEGINS TO WEAKEN OVER THE SOUTHWEST REGION.
STRONG WARM AIR ADVECTION WILL CONTINUE AT THE SURFACE THROUGH THE
EXTENDED PERIOD...KEEPING SURFACE TEMPERATURES ABOVE AVERAGE IN THE
LOWER 90S. MODEL SOUNDINGS SHOW STABLE UPPER AIR PROFILE THROUGH THE
PERIOD...WITH A LACK OF INSTABILITY PARAMETERS AND AVAILABLE
MOISTURE. SURFACE TEMPERATURES COULD POSSIBLY REACH THE CONVECTIVE
TEMPERATURES...WHICH ARE FORECASTED TO BE IN THE MID TO UPPER 90S.
STRONG CAP COULD BE BROKEN FOR ISOLATED LOCATIONS ALLOWING FOR SOME
SMALL AREAS OF STORM DEVELOPMENT. CHANCES FOR PRECIPITATION ARE
VERY SLIM...WITH WARM AND DRY TREND CONTINUING INTO NEXT WEEKEND.
THE BEST CHANCE TO SEE PRECIPITATION ACROSS THE TRI STATE AREA WOULD
BE FOR NEXT WEEKEND AS UPPER LEVEL PATTERN BEGINS TO LOOK SUPPORTIVE
FOR STORM DEVELOPMENT...BUT MODEL RUNS STILL INDICATE DRY WEATHER AT
PRESENT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 536 AM MDT SAT AUG 31 2013
VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. ISOLATED TO
SCATTERED THUNDERSTORMS SHOULD DEVELOP TO THE WEST OF BOTH TAF
SITES LATER THIS AFTERNOON. SOME MODEL DISAGREEMENT ON IF THIS
WILL BE THE CASE. HOWEVER...DUE TO OVERNIGHT CONVECTION
STABILIZING THE AIR MASS AND THE NEXT LIFT NOT EXPECTED TO ARRIVE
UNTIL MUCH LATER...DECIDED TO GO IN THIS DIRECTION. SINCE MAIN
TIME OF CONVECTION LOOKS TO BE UNTIL MUCH LATER THIS AFTERNOON AND
THIS EVENING...CHOSE TO HANDLE THUNDERSTORMS WITH A MENTION OF
VCTS. IF A STORM WOULD HAPPEN TO AFFECT ONE OF THE SITES...
CONDITIONS COULD BE BARELY WITHIN VFR OR BRIEFLY MOVE INTO THE
MVFR CATEGORY.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...DR
SHORT TERM...BULLER
LONG TERM...MK
AVIATION...BULLER
AREA FORECAST DISCUSSION...UPDATED
NWS GRAY ME
657 AM EDT SAT AUG 31 2013
.SYNOPSIS...
A COLD FRONT OVER EASTERN CANADA WILL DROP SOUTHWARD TOWARDS THE
INTERNATIONAL BORDER TODAY. LOW PRESSURE IS FORECAST TO TRACK
EASTWARD ALONG THIS FRONTAL BOUNDARY TONIGHT. THE BOUNDARY WILL
REMAIN STALLED THROUGH SUNDAY. A WARM FRONT LIFTS THROUGH THE
REGION ON MONDAY WITH A COLD FRONT MOVING EAST TUESDAY NIGHT INTO
WEDNESDAY MORNING. A SECONDARY COLD FRONT SWEEPS THROUGH ON
THURSDAY. HIGH PRESSURE BUILDS IN FRIDAY AND SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE...HAVE GONE AHEAD AND TRIMMED BACK POP IN THE N BASED ON
CURRENT TRENDS THIS MORNING. STRONG PUSH OF DRY AIR ALOFT...PER
WATER VAPOR IMAGERY...HAS WORKED INTO NRN ZONES. INDICATIVE OF AT
LEAST SOME SUBSIDENCE ALOFT...THIS SHOULD LIMIT SHRA ACTIVITY AT
LEAST THRU THE FIRST PART OF THE DAY. THIS IS SUPPORTED WELL BY
08Z HRRR RUN...WHICH FAVORS CONVECTION RE-FIRING ALONG SAGGING
FRONTAL BOUNDARY DRAPED ACROSS THE SRN CWFA THIS AFTERNOON. HAVE
OPTED TO KEEP LIKELY POP GOING FOR THOSE AREAS OF SRN NH AND
ADJACENT SWRN ME AFTER 15Z OR SO.
PREVIOUS DISCUSSION...COMPLEX FORECAST IN STORE FOR TODAY...AS
WEAK FNT DROPS INTO THE REGION AND STALLS. ONE MCS HAS MOVED THRU
THE NORTH COUNTRY OF NH...AND REACHED PENOBSCOT BAY OVER THE
COURSE OF THE LAST SEVERAL HOURS. ANOTHER AREAS OF SHRA AND
EMBEDDED TSTMS FARTHER SW WILL MOVED EWD INTO THE CWFA OVER THE
NEXT COUPLE OF HOURS. THESE COMPLEXES WILL LEAVE BEHIND OUTFLOW
BOUNDARIES THAT WILL HELP ACT TO REINFORCE THE DIFFERENCE BETWEEN
THE WARM SECTOR AND THE RELATIVELY COOLER AIR TO THE N.
HAVE FAVORED A BLEND WITH THE GFS POP...AS IT SEEMS TO HAVE THE
RIGHT IDEA THAT COLD FNT WILL HANG UP ACROSS THE SRN ZONES TODAY.
EXPECT THAT WITH DIURNAL HEATING THIS FEATURE WILL BECOME THE
FOCUS FOR SHRA/TSTMS AND POSSIBLY MORE LOOSELY ORGANIZED MCS/S
LIKE TONIGHT. CANNOT RULE OUT AN ISOLD STRONGER STORM...AS DEEP
UNIDIRECTIONAL FLOW AND PCPN LOADING COULD PRODUCE SOME GUSTY
WINDS. PWAT VALUES APPROACHING 2 SD ABOVE NORMAL WILL MEAN HEAVY
RNFL IS POSSIBLE WITH ANY STRONGER CONVECTION AS WELL.
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
FRONTAL BOUNDARY WILL LIKELY WAFFLE BACK AND FORTH AS CONVECTION
MOVES ALONG IT TODAY AND TONIGHT. EXPECT THAT IT WILL REMAIN
NEARER THE COAST AND SRN NH VS THE MTNS. SAME IS TRUE FOR DURING
THE DAY SUN...WHERE EVENTUALLY S/WV APPROACHING FROM THE NW HELPS
LIFT BOUNDARY BACK N AS A WARM FNT.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
A FRONTAL BOUNDARY WILL REMAIN RELATIVELY STATIONARY OVER THE
FORECAST AREA SUNDAY NIGHT AS LOW PRESSURE DEVELOPS WEST OF OUR
REGION. THIS WILL ALLOW SCATTERED SHOWERS AND THUNDERSTORMS TO
CONTINUE ACROSS THE REGION.
BY MONDAY...A COLD FRONT WILL BEGIN TO APPROACH THE
REGION...ALLOW A MOIST...SOUTHERLY FLOW TO PICK UP OFF THE GULF OF
MAINE. SHOWERS AND PATCHY DRIZZLE WILL BECOME MORE NUMEROUS
DURING THE DAY. THERE MAY BE SUFFICIENT INSTABILITY OVER IN NEW
HAMPSHIRE TO ALLOW FOR GUSTY SHOWERS AND THUNDERSTORMS TO DEVELOP.
POPS WILL BE ON THE INCREASE MONDAY INTO INTO TUESDAY MORNING AS A
COLD FRONT SWEEPS ACROSS NEW HAMPSHIRE AND THEN MAINE. THIS TIMING
OF THIS FRONT WILL BE CRITICAL AS A SLOWER PROGRESSION OF THE
FRONT...SIMILAR TO THE GGEM MODEL...MAY ALLOW FOR SOME AFTERNOON
HEATING AND GUSTY STORM OVER SOUTHERN AREAS ONCE AGAIN.
HYDRO...WITH A WARM...HUMID AIRMASS IN PLACE...AND PRECIPITABLE WATER
VALUES NEAR TWO INCHES...ANY STORMS MAY PRODUCE LOCALLY HEAVY
RAINFALL. THIS WILL NEED TO BE MONITORED OVER THE WEEKEND.
A WEAK RIDGE OF HIGH PRESSURE WILL BUILD OVER NEW ENGLAND ON
WEDNESDAY. THEREAFTER...ANOTHER COLD FRONT WILL APPROACH FROM THE
SAINT LAWRENCE RIVER VALLEY AS A VERY CHILLY...CANADIAN HIGH
PRESSURE SYSTEM BUILDS QUICKLY SOUTH FOR LATE IN THE WEEK.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
SHORT TERM...FNT STALLING OVER THE AREA TODAY WILL LEAD TO ROUNDS
OF SHRA AND TSTMS. SCT MVFR OR LOWER CONDS WILL BE PSBL IN ANY
STORMS RIGHT THRU SUN.
LONG TERM...PERIODS OF MVFR/IFR ARE EXPECTED SUNDAY NIGHT THROUGH
TUESDAY IN THUNDERSTORMS...SHOWERS...AND FOG. TIMING OF INDIVIDUAL
DROPS IN CEILING/VISIBILITY WILL BE HARD TO PIN DOWN BUT WITH
AMPLE MOISTURE...LATE EVENING INTO THE EARLY MORNING HOURS EACH
DAY WILL SEE RESTRICTIONS.
&&
.MARINE...
SHORT TERM...WINDS AND SEAS WILL APPROACH SCA THRESHOLDS AT TIMES
TODAY...WITH SUSTAINED ONSHORE FLOW BUILDING SEAS TO NEAR 5 FT BY
SUN.
LONG TERM...SEAS WILL BE AROUND 3-5 FT SUNDAY NIGHT INTO MONDAY
MORNING OVER THE OUTER WATERS...DO TO A STALLED BOUNDARY JUST
NORTH OF THE WATERS.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
LEGRO/JC
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1058 AM EDT SAT AUG 31 2013
.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO DRIFT FARTHER OFFSHORE TODAY AS A
WEAK TROUGH DEVELOPS OVER THE PIEDMONT OF VIRGINIA. A COLD FRONT
WILL APPROACH THE REGION FROM THE WEST ON MONDAY...AND WILL PUSH
ACROSS THE AREA TUESDAY AND TUESDAY NIGHT. HIGH PRESSURE WILL BUILD
INTO THE MID ATLANTIC STATES ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE LATEST WX ANALYSIS SHOWS ~1016 MB SFC HIGH PRESSURE SITUATED
WELL OFF THE MID ATLC/SE COAST...WITH PRESSURE FALLS INDICATING A
DEVELOPING LEE TROUGH ALONG/WEST OF THE I-95 CORRIDOR. CURRENT
WV SATELLITE AND REGIONAL RADAR REVEALS A RATHER SMALL BUT SHARP
SHORTWAVE DIVING SE THROUGH OHIO WITH AN ASSOCIATED MCS SPREADING
THROUGH SE OHIO/ERN KY. MODELS TO A VARYING DEGREE BEGIN TO SPREAD
INCREASING MOISTURE INTO WRN PORTIONS OF THE CWA AFTER 18Z THIS
AFTN. WILL CONTINUE TO WATCH THE CURRENT ACTIVITY CLOSELY TO SEE
IF IT HOLDS TOGETHER UPON REACHING THE APPALACHIANS...CURRENT
THINKING IS THAT IT PROBABLY WILL NOT ALTHOUGH THE HRRR ACTUALLY
SPREADS SOME SCATTERED SHOWERS INTO WRN PORTIONS OF THE CWA BY 18Z
(BUT IT DEVELOPS THIS FROM AN AREA OF PRECIP OVER SOUTH CENTRAL VA
AND NCENTRAL NC WHICH THUS FAR HAS NOT OCCURRED).
OVERALL...FORECAST HAS BEEN CHANGED VERY LITTLE FOR THE AFTN...FAVORING
AREAS WEST OF I-95 FOR LOW CHC POPS BY LATE AFTN/EARLY EVENING WITH
20% OR LOWER POPS FARTHER EAST WHERE INSTABILITY PARAMETERS ARE LOWER
(ML CAPES 1000 J/KG OR LESS). GFS/NAM DO SHOW SOME DECENT MID
LEVEL LAPSE RATES > 6.5 C/KM THIS AFTN/EVENING BUT DEEP LAYER
BULK SHEAR WILL AVG 20-25 KT NORTH TO < 20 KT SOUTH SO ORGANIZED
STRONG STORMS ARE UNLIKELY ESPECIALLY OVER SOUTHERN 1/2 OF THE CWA.
PRECIPITABLE WATER VALUES RISE TO 1.50 TO 1.80" BY AFTN SO MAIN
ISSUE WOULD BE LOCALLY HEAVY RAIN. FOR TEMPS, EXPECT HIGHS TODAY
GENERALLY IN THE UPPER 80S TO AROUND 90...LOCALLY MID 80S ON THE
IMMEDIATE COAST.
CONSIDERING RATHER ANEMIC DYNAMICS/FORCING, RAIN CHCS END QUICKLY
TONIGHT. EXPECT A PARTLY CLOUDY AND DRY NIGHT ACROSS THE LOCAL
AREA WITH EARLY MORNING LOWS IN THE UPR 60S TO LOW 70S.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
RAIN CHCS INCREMENTALLY RAMP UPWARDS FOR THE LATTER HALF OF THE
HOLIDAY WEEKEND AS LONGWAVE TROUGH CONTINUES TO AMPLIFY/DEEPEN
OVER THE MID-ATLANTIC REGION. MOISTURE WL GRADUALLY INCREASE
THROUGH THIS PERIOD GIVEN SW FLOW AHEAD OF THE SLOW MOVING COLD
FRONT THAT IS PROGGED TO MOVE ACROSS THE LOCAL AREA BY TUESDAY.
HIGH END CHC (40%) POPS FOR SHRAS/TSTMS MOST AREAS BOTH DAYS
(LOWER FAR SE) AS SEVERAL ADDITIONAL SPOKES OF SHORTWAVE ENERGY
EMBEDDED WITHIN THE LARGER TROUGH ROTATE THROUGH. THREAT FOR SVR
WX APPEARS LOW ATTM GIVEN LACK OF SHEAR, THOUGH WITH PW ~2",
LOCALLY HVY RAINFALL IS ONCE AGAIN A CONCERN (OVER INLAND AREAS
SUNDAY, CLOSER TO THE COAST ON MONDAY). HIGHS SUN/MON UPR 80S TO
LOW 90S. LOWS SUN NIGHT IN THE UPR 60S TO LOW 70S.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
LARGE SCALE PATTERN DURING THE MEDIUM RANGE PERIOD CHARACTERIZED BY
LARGE MID LVL RIDGE IN THE SW U.S. AND A MID LEVEL TROUGH OVER THE
EASTERN CONUS. LATEST 12Z GFS/ECMWF NOW INTO BETTER AGREEMENT THAN
THEIR 00Z RUNS HAD BEEN WITH THE LATER PART OF NEXT WEEK. BOTH
MODELS NOW SHOW THE UPPER RIDGE EXPANDING NORTH INTO THE NORTHERN
ROCKIES BY MIDWEEK...EFFECTIVELY SENDING A REINFORCING SHOT OF COOL
AIR AND UPPER TROUGHING SE INTO THE GREAT LAKES AND NE CONUS BY
THU/FRI. FOR THE LOCAL AREA...THIS PATTERN WILL PUSH THE ACTUAL
FRONT THROUGH DURING THE DAY TUE...WITH MOISTURE AND INSTABILITY
PROFILES FAVORING HIGHEST POPS TUE AFTN OVER FAR SOUTHERN/SE VA AND
NC (30-50%) WITH SOMEWHAT DRIER AIR AND LESS COVERAGE OF STORMS
FARTHER N/W. HIGHS TUE GENLY HELD IN THE 80S DUE TO MORE CLOUD
COVER. HIGH PRESSURE BUILDS IN FROM THE WNW TUE NIGHT-WED...AND
PERSISTS OVER THE REGION INTO THU AS THE DEEP UPPER TROUGH BECOMES
ANCHORED OVER EASTERN CANADA. EXPECT COOLER AND DRIER/MORE
COMFORTABLE CONDITIONS WITH HIGHS MAINLY 80-85 AND LOWS IN THE UPPER
50S NW TO MID 60S FAR SE ON WED. FLOW BRIEFLY TURNS BACK TO THE SW
ON THU ALLOWING FOR SOMEWHAT WARMER TEMPS INTO THE MID OR POSSIBLY
UPPER 80S AHEAD OF THE NEXT FRONT. THIS FRONT LOOKS TO COME THROUGH
THU NIGHT/EARLY FRI WITH MINIMAL DYNAMICS SO WILL KEEP FORECAST DRY
WITH JUST SOME INCREASE IN CLOUDS. PARTLY TO MOSTLY SUNNY FRI W/
HIGHS IN THE UPPER 70S TO LOWER 80S.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
AREAS OF FOG HAVE DEVELOPED ACROSS NE NC AND EXTREME SE VA THIS
MORNING. LIMITED CEILINGS ARE AVERAGING 200-400 FT AGL AND
VISIBILITIES HAVE BEEN REDUCED TO THREE QUARTERS OF A MILE OR LESS
IN THESE AREAS. CONDITIONS SHOULD BEGIN TO LIFT/DISSIPATE AROUND
31/1300Z.
BY MID TO LATE MORNING...SURFACE HIGH PRESSURE CONTINUES TO MOVE
EAST OF THE MID ATLANTIC COAST AND A SURFACE LOW CROSSES THE EASTERN
GREAT LAKES. THE PRESSURE GRADIENT BTWN THESE FEATURES WILL BEGIN TO
TIGHTEN AND A LEE TROUGH IS EXPECTED TO DEVELOP. AS THIS
OCCURS...SOUTH WINDS WILL QUICKLY BECOME BREEZY WITH GUSTS TO AROUND
20 KT BY EARLY AFTERNOON. MEANWHILE...ENERGY AND MOISTURE ASSOCIATED
WITH THE MID LEVEL OHIO VALLEY TROUGH WILL INTERACT WITH THE LEE
TROUGH AND CAUSE SHOWERS/THUNDERSTORMS TO DEVELOP THIS
AFTERNOON/EVENING. PRECIPITATION CHANCES HAVE BEEN LIMITED TO AREAS
NW OF A LINE FROM KSBY-KRIC-KAVC...HOWEVER ISOLATED STORMS MAY BE
POSSIBLE CLOSER TO THE COAST. WILL NEED TO MONITOR.
A MORE SUBSTANTIAL SURFACE COLD FRONT APPROACHES FROM THE WEST ON
SUNDAY AND PUSHES A MORE BROAD-SCALE MID LEVEL TROUGH OVER THE MID
ATLANTIC REGION. THIS WILL RESULT IN INCREASED SHOWER/THUNDERSTORM
CHANCES AND COVERAGE ON SUNDAY...WHICH WILL BE EVEN HIGHER ON MONDAY
DURING THE FRONTAL PASSAGE. THE FRONT APPEARS TO STALL ALONG THE
COAST TUESDAY AND SHOWER/STORMS WILL ONCE AGAIN BE POSSIBLE. BREEZY
S-SW WINDS SHOULD BE ANTICIPATED EACH AFTERNOON FROM SATURDAY
THROUGH TUESDAY. WINDS THEN VEER TO THE W-NW BEHIND THE FRONT.
&&
.MARINE...
THE WATERS BECOME POSITIONED BTWN HIGH PRESSURE OFF THE MID
ATLANTIC COAST AND A LOW PRESSURE SYSTEM MOVING ACROSS THE ERN
GREAT LAKES TODAY..RESULTING IN A TIGHTENING PRESSURE GRADIENT.
SOUTH WINDS ON CHES BAY AND COASTAL WATERS NORTH OF THE VA/NC
BORDER WILL AVERAGE 10-15 KT THIS MORNING THROUGH EARLY AFTERNOON
AND THEN INCREASE TO 15-20 KT BY LATE AFTERNOON ON CHES BAY (A
SOLID 20 KT FOR COASTAL WATERS)...PERSISTING THROUGH THE OVERNIGHT
HOURS INTO SUNDAY MORNING. CURRITUCK SOUND MAY EXPERIENCE GUSTS
AROUND 20 KT LATE THIS AFTERNOON INTO EARLY EVENING...HOWEVER THE
DURATION OF THE WIND GUSTS SHOULD BE SHORT-LIVED. CONFIDENCE IS
NOT HIGH ENOUGH TO ISSUE SCA FLAGS FOR THE SOUND AND ANY GUSTY
WINDS DURING THIS TIME FRAME TODAY MAY BE COVERED WITH MARINE
WEATHER STATEMENTS INSTEAD. WILL NEED TO MONITOR. A SECONDARY SLY
SURGE IS EXPECT TO BEGIN AROUND MIDNIGHT...PUSHING GUSTS ON CHES
BAY UP TWD 25 KT. WAVES ON CHES BAY WILL AVERAGE 2-3 FT AND SEAS
WILL AVERAGE 3-4 FT. SCA FLAGS FOR CHES BAY HAVE BEEN ISSUED
BEGINNING LATE THIS AFTERNOON THROUGH 10 AM EDT SUNDAY MORNING.
MEANWHILE...A MID LEVEL TROUGH CROSSING THE REGION AND INTERACTING
WITH A LEE TROUGH WILL TRIGGER SHOWERS AND THUNDERSTORMS DURING
THIS AFTERNOON AND EVENING. A FEW STORMS MAY MOVE OVER THE BAY
NORTH OF NEW POINT COMFORT WHILE THE REST OF THE WATERS REMAIN
RAIN-FREE.
A COLD FRONT WILL APPROACH THE REGION FROM THE WEST ON SUNDAY INTO
MONDAY. THE FRONT IS EXPECTED TO MOVE INTO THE MID ATLANTIC REGION
MONDAY NIGHT AND THEN STALL ALONG THE COAST ON TUESDAY. WINDS ARE
EXPECTED TO BECOME MORE SWLY MONDAY INTO TUESDAY AND REMAIN AOB
15 KT. A COOL NW-N SURGE EITHER TUESDAY NIGHT OR EARLY WEDNESDAY MAY
RESULT IN A PERIOD OF SCA HEADLINES...ALTHOUGH TIMING ON THIS
CONTINUES TO BE UNCERTAIN.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 10 AM EDT
SUNDAY FOR ANZ630>632-634.
&&
$$
SYNOPSIS...LKB
NEAR TERM...LKB/MAM
SHORT TERM...JDM/MAM
LONG TERM...LKB
AVIATION...BMD
MARINE...BMD
AREA FORECAST DISCUSSION...UPDATED
NWS BALTIMORE MD/WASHINGTON DC
1011 AM EDT SAT AUG 31 2013
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN OFFSHORE THIS WEEKEND WHILE A SERIES OF
UPPER DISTURBANCES MOVE THROUGH THE AREA. A COLD FRONT WILL MOVE
THROUGH THE REGION MONDAY NIGHT. HIGH PRESSURE RETURNS MIDWEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
MONITORING THE INCOMING SHORTWAVE OVER THE ERN OHIO RVR VLY. THE
SRN - OR WRN - FLANK OF THE WAVE HAS BEEN AND CONTINUES TO DEVELOP
POCKETS OF STRONG CONVECTION ALONG IT BUT THE NRN END HAS LARGELY
STRATIFORMED OUT AND HAS BECOME MORE STABLE ARRIVING AT THE
APLCNS. NOW THAT WE`RE W/IN THE TIME RANGES OF LOCAL 1-HR
GUIDANCE...INTERESTING TO SEE THE VARIOUS DEPICTIONS OF THE
AFTN/EVE CONVECTIVE POTENTIAL FOR THE CWA. RECENT HRRR RUNS
CONTINUE TO DO WHAT SEEMS MOST PLAUSIBLE FOR AT LEAST THE FIRST
HALF OF THE DAY...PASSING THE CURRENT WV ACTIVITY DOWN ACROSS SWRN
VA AND JUST S OF THE SRN TIER CWA COUNTIES/I-64 CORRIDOR. ONLY
ISOLATED SHOWER AND WEAK TSTM ACTIVITY THEN DEVELOPS ACROSS THE
REST OF THE CWA DURING THE AFTN-EARLY EVE HRS. THE NRN FLANK OF
THE WAVE THEN REINVIGORATES SOME CONVECTION ACROSS NERN MD TOWARD
THE LATE EVE HRS.
PASSING BATCHES OF CIRRUS DEBRIS THIS MRNG INDICATE THAT EVEN W/
SOME INSTABILITY...THERE ARE ENOUGH PREVENTATIVE LAYERS IN THE
ATMOS TO HOLD OFF TSTMS UNTIL A BOUNDARY PASSES THRU AND ACTS ON
THE BUILDING MOISTURE/INSTABILITY. UNMODIFIED 12Z KIAD SNDG HAS
AROUND 1500 J/KG CAPE AVAILABLE W/ A COUPLE OF HEFTY INVERSIONS
BUT CERTAINLY AMENABLE TO DISSIPATING IF THE INCOMING SHORTWAVE
CAN COOL OFF THESE LEVELS IN A SHORT AMNT OF TIME. THE KEY TO
CONVECTIVE POTENTIAL AND STRENGTH THIS AFTN ANYWHERE IN THE AREA
WILL BE LOW LEVEL AND SMALL-SCALE BOUNDARY INTERACTION. THE SHEAR
PROFILES ARE NOT FAVORABLE SO THE INITIATION AND CONTINUATION WILL
BE ON THE SHOULDERS OF OUTFLOW BOUNDARIES AND THE DYNAMIC FORCING
OF THE SHORTWAVE ITSELF.
FROM PREV DISC...
POPS WERE KEPT LOW DUE TO THESE UNCERTAINTIES. ALSO DELAYED
MENTION OF SHOWERS OR STORMS FOR THE I-95 CORRIDOR UNTIL THE EVE
PERIOD BASED ON THE TIMING OF THE TROUGH. WITH SO MANY OUTDOOR
ACTIVITIES PLANNED FOR THE HOLIDAY WEEKEND...WE WANT PEOPLE TO PAY
EXTRA ATTENTION TO THE FCST.
SHOWERS AND STORMS SHOULD DIMINISH AFTER SUNSET WITH THE LOSS OF
HEATING. MOST IF NOT ALL OF THIS ACTIVITY SHOULD END BY THE OVNGT AS
THE SHORTWAVE TROUGH MOVES EAST OF THE CHSPK BAY. PATCHY FOG MAY
DEVELOP OVNGT IN AREAS THAT RECEIVE RAIN TDA AND WHERE SKIES CLEAR.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
PARADE OF SHORTWAVES WILL CONTINUE ON SUNDAY...WITH SFC TROUGHING
EXPECTED TO DEVELOP IN THE LEE OF THE BLUE RIDGE. THIS
COMBINATION...ALONG WITH COPIOUS MOISTURE /PWATS APPROACHING TWO
INCHES/ SHOULD BE SUFFICIENT FOR THE DEVELOPMENT OF NUMEROUS SHOWERS
AND THUNDERSTORMS DURING THE AFTERNOON AND EARLY EVENING. WENT WITH
LIKELY POPS IN MOST AREAS EAST OF THE BLUE RIDGE. CONVECTION MAY
PRODUCE LOCALLY HEAVY RAIN...BUT PROPAGATION OF STORMS IS LIKELY TO
PRECLUDE A WIDESPREAD FLOOD THREAT.
ACTIVITY SHOULD WANE WITH SUNSET SUNDAY NIGHT...HOWEVER...MODELS
KEEP A MOIST AIRMASS IN PLACE AND SHOW A SHORTWAVE PASSING NORTH OF
THE AREA. IT IS CLOSE ENOUGH TO KEEP AT LEAST SMALL POPS IN THE
FORECAST ALL NIGHT. WILL DEFINITELY BE A WARM AND HUMID NIGHT.
LABOR DAY IS CONSIDERED THE UNOFFICIAL END OF SUMMER. UNLIKE
MEMORIAL DAY...WHICH FELT ANYTHING BUT SUMMERLIKE...LABOR DAY SHOULD
BE PLENTY HOT AND HUMID WITH GOOD CHANCES FOR SHOWERS AND STORMS AS
SFC TROUGHING REMAINS IN PLACE...AND A COLD FRONT APPROACHES FROM
THE WEST. NOT QUITE CONFIDENT ENOUGH TO CARRY LIKELY POPS YET. IF
THERE ARE BREAKS IN THE CLOUDS...HIGHS COULD REACH THE LOWER
90S...BUT WILL HOLD GRIDS IN THE UPPER 80S GIVEN EXPECTED CLOUDS.
FROPA IS EXPECTED MONDAY NIGHT OVER MOST...IF NOT ALL...OF THE AREA.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
ALTHOUGH LINGERING SHOWERS CANNOT BE RULED OUT ON TUESDAY...I
LIMITED CHANCES TO THE FAR SE AND MARINE ZONES. HIGHS 5 TO 10
DEGREES COOLER THAN MONDAY. THE STRENGTH OF THE COOL AIRMASS BEHIND
THE FRONT REMAINS IN QUESTION...AND WILL ERR ON THE WARMER SIDE FOR
TUESDAY AND WEDNESDAY. A REINFORCING FRONT PUSHES THROUGH...LIKELY
DRY...ON THURSDAY. PRECIP CHANCES MAY RETURN BY NEXT WEEKEND WITH
ONSHORE FLOW FORECAST TO DEVELOP.
&&
.AVIATION /13Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS TDA...ALTHOUGH A BRIEF REDUCTION IN VSBY POSSIBLE
LATE THIS AFTN AND EVE AS SCT SHRA/TSRA MOVE THRU. CHANCES FOR
PRECIP TOO LOW THRU 18Z TO INCLUDE A VCTS IN THE TAFS. THERE IS
MORE UNCERTAINTY IF THIS ACTIVITY MAKES IT FARTHER EAST TOWARD THE
I-95 TERMINALS.
PATCHY FOG MAY DEVELOP AGAIN TNGT...ESPECIALLY AT TERMINALS THAT
RECEIVE APPRECIABLE RAINFALL TDA.
SCTD TO NUMEROUS SHRA/TSRA EXPECTED EACH AFTN/EVENING SUNDAY AND
MONDAY. HEAVY RAIN IN SOME CONVECTION COULD CREATE VSBY RESTRICTIONS
AT TIMES. FROPA ON MONDAY NIGHT SHOULD YIELD GENERALLY VFR
CONDITIONS AFTER THAT THROUGH MIDWEEK.
&&
.MARINE...
SLY CHANNELING HAS PRODUCED 20 KT GUSTS IN THE CHSPK BAY. WITH
HIPRES PARKED OFFSHORE...THE PRESSURE GRADIENT WILL REMAIN STRONG
ENOUGH TO YIELD A CONTINUATION OF THE SCA FOR THE CHSPK BAY AND
LOWER TIDAL POTOMAC INTO TNGT.
GUSTY WINDS WILL GRADUALLY SUBSIDE SUNDAY MORNING AS SLY CHANNELING
LESSENS AND WINDS TURN OUT OF THE SOUTHWEST. SCATTERED TO NUMEROUS
SHOWERS AND STORMS ARE EXPECTED SUNDAY AND MONDAY...MAINLY IN THE
AFTERNOON AND EVENING. A FRONTAL PASSAGE MONDAY NIGHT OR TUESDAY
MORNING WILL TURN WINDS OUT OF THE NORTH...BUT THE SYSTEM IS NOT
PARTICULARLY STRONG SO WINDS SHOULD REMAIN GENERALLY LIGHT.
&&
.TIDES/COASTAL FLOODING...
THE COASTAL FLOOD ADVISORY CONTINUES FOR ANNE ARUNDEL COUNTY FOR
THE AFTN HT CYCLE. POSITIVE ANOMALIES ALONG THE WRN SHORE OF THE
MD CHSPK BAY HAVE REMAINED STEADY AROUND 1.25 FT SINCE YDA. WITH
SLY FLOW CONTINUING UP THE BAY...EXPECT THIS STEADY STATE TO
CONTINUE TDA. ANOMALIES OF THIS MAGNITUDE WILL BE ENOUGH TO
PRODUCE COASTAL FLOODING AT ANNAPOLIS THIS AFTN DESPITE IT BEING
THE LOWER OF THE TWO HIGH TIDE CYCLES. THEREFORE...A COASTAL FLOOD
ADVISORY HAS BEEN ISSUED FOR ANNE ARUNDEL COUNTY FOR THIS AFTN.
THE LATEST CBOFS DOES NOT SHOW FLOODING PROBLEMS FOR TNGT. AM NOT
SOLD ON THIS YET WITH SLY FLOW CONTINUING. WILL KEEP THE POTENTIAL
FOR ANOTHER ROUND OF MINOR COASTAL FLOODING W/ TNGT`S HIGH TIDE
CYCLE.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...COASTAL FLOOD ADVISORY FROM NOON TODAY TO 4 PM EDT THIS
AFTERNOON FOR MDZ014.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EDT SUNDAY FOR ANZ530>534-537-
539>541-543.
&&
$$
UPDATE...GMS
PREV DISCUSSION...JRK/JE
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
609 AM EDT SAT AUG 31 2013
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN OFFSHORE THIS WEEKEND WHILE A SERIES OF
UPPER DISTURBANCES MOVE THROUGH THE AREA. A COLD FRONT WILL MOVE
THROUGH THE REGION MONDAY NIGHT. HIGH PRESSURE RETURNS MIDWEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
A LGT SLY RETURN FLOW HAS BEEN MAINTAINED OVNGT WITH HIPRES PARKED
OFF THE MID-ATLANTIC COAST. THIS LGT WINDS AND SCT CLOUDS HAVE
PREVENTED FOG DEVELOPMENT THUS FAR.
WE ARE MONITORING AN OVNGT COMPLEX OF STORMS OVER OH. THE MID-LVL
SHORTWAVE TROUGH ASSOCIATED WITH THIS REMNANT MCS IS FCST TO
PROGRESS E-SE TDA...REACHING THE CENTRAL APPALACHIANS BY MID
AFTN. THE LATER TIMING IN THE DAY OF THIS DISTURBANCE WILL ALLOW
FOR THE ATMOSPHERE TO DESTABILIZE ACROSS THE REGION AS TEMPS REACH
THE MID TO UPPER 80S FOR HIGHS. AS EVIDENT FROM THE 00Z RAOB
SOUNDINGS UPSTREAM OF THE AREA...A SIGNIFICANT MID-LVL INVERSION
WILL REACH OUR AREA THIS MRNG AND INITIALLY PROVIDE A LID FOR DEEP
CONVECTION TO OVERCOME...WHICH MAY DELAY INITIATION OF SHOWERS AND
STORMS OVER THE MTS UNTIL THE MID TO LATE AFTN. FCST SOUNDINGS
FROM THE LATEST RAP INDICATE ABOUT 2000 J/KG OF SBCAPE AVAILABLE
FOR CONVECTION THIS AFTN. A WEAK WIND FIELD WILL LIMIT EXTENT OF
SEVERE STORMS TDA...BUT A FEW PULSE SEVERE STORMS ARE POSSIBLE
GIVEN THE FAVORABLE ENIVRONMENT FOR WET MICROBURSTS.
THERE IS HIGHER UNCERTAINTY IF CONVECTION BREAKS THE CAP TDA EAST
OF THE MTS. THE 00Z NAM AND A FEW NMM MEMBERS OF THE 21Z SREF
DEPICT A STRONGER SHORTWAVE TROUGH MOVING THRU THIS AFTN...
ALLOWING THE MID-LVL CAP TO ERODE FASTER AND SHOWER/STORMS TO
DEVELOP FARTHER EAST INTO THE I-95 CORRIDOR DURING THE LATE AFTN.
MEANWHILE THE BULK OF OTHER OPERATIONAL MODEL GUIDANCE PROG A
WEAKER SHORTWAVE AND THUS A STRONGER SUBSIDENCE INVERSION...WHICH
WOULD INHIBIT ANY CONVECTION FROM DEVELOPING EAST OF THE MTS. POPS
WERE KEPT LOW DUE TO THESE UNCERTAINTIES. ALSO DELAYED MENTION OF
SHOWERS OR STORMS FOR THE I-95 CORRIDOR UNTIL THE EVE PERIOD BASED
ON THE TIMING OF THE TROUGH. WITH SO MANY OUTDOOR ACTIVITIES
PLANNED FOR THE HOLIDAY WEEKEND...WE WANT PEOPLE TO PAY EXTRA
ATTENTION TO THE FCST.
SHOWERS AND STORMS SHOULD DIMINISH AFTER SUNSET WITH THE LOSS OF
HEATING. MOST IF NOT ALL OF THIS ACTIVITY SHOULD END BY THE OVNGT AS
THE SHORTWAVE TROUGH MOVES EAST OF THE CHSPK BAY. PATCHY FOG MAY
DEVELOP OVNGT IN AREAS THAT RECEIVE RAIN TDA AND WHERE SKIES CLEAR.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
PARADE OF SHORTWAVES WILL CONTINUE ON SUNDAY...WITH SFC TROUGHING
EXPECTED TO DEVELOP IN THE LEE OF THE BLUE RIDGE. THIS
COMBINATION...ALONG WITH COPIOUS MOISTURE /PWATS APPROACHING TWO
INCHES/ SHOULD BE SUFFICIENT FOR THE DEVELOPMENT OF NUMEROUS SHOWERS
AND THUNDERSTORMS DURING THE AFTERNOON AND EARLY EVENING. WENT WITH
LIKELY POPS IN MOST AREAS EAST OF THE BLUE RIDGE. CONVECTION MAY
PRODUCE LOCALLY HEAVY RAIN...BUT PROPAGATION OF STORMS IS LIKELY TO
PRECLUDE A WIDESPREAD FLOOD THREAT.
ACTIVITY SHOULD WANE WITH SUNSET SUNDAY NIGHT...HOWEVER...MODELS
KEEP A MOIST AIRMASS IN PLACE AND SHOW A SHORTWAVE PASSING NORTH OF
THE AREA. IT IS CLOSE ENOUGH TO KEEP AT LEAST SMALL POPS IN THE
FORECAST ALL NIGHT. WILL DEFINITELY BE A WARM AND HUMID NIGHT.
LABOR DAY IS CONSIDERED THE UNOFFICIAL END OF SUMMER. UNLIKE
MEMORIAL DAY...WHICH FELT ANYTHING BUT SUMMERLIKE...LABOR DAY SHOULD
BE PLENTY HOT AND HUMID WITH GOOD CHANCES FOR SHOWERS AND STORMS AS
SFC TROUGHING REMAINS IN PLACE...AND A COLD FRONT APPROACHES FROM
THE WEST. NOT QUITE CONFIDENT ENOUGH TO CARRY LIKELY POPS YET. IF
THERE ARE BREAKS IN THE CLOUDS...HIGHS COULD REACH THE LOWER
90S...BUT WILL HOLD GRIDS IN THE UPPER 80S GIVEN EXPECTED CLOUDS.
FROPA IS EXPECTED MONDAY NIGHT OVER MOST...IF NOT ALL...OF THE AREA.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
ALTHOUGH LINGERING SHOWERS CANNOT BE RULED OUT ON TUESDAY...I
LIMITED CHANCES TO THE FAR SE AND MARINE ZONES. HIGHS 5 TO 10
DEGREES COOLER THAN MONDAY. THE STRENGTH OF THE COOL AIRMASS BEHIND
THE FRONT REMAINS IN QUESTION...AND WILL ERR ON THE WARMER SIDE FOR
TUESDAY AND WEDNESDAY. A REINFORCING FRONT PUSHES THROUGH...LIKELY
DRY...ON THURSDAY. PRECIP CHANCES MAY RETURN BY NEXT WEEKEND WITH
ONSHORE FLOW FORECAST TO DEVELOP.
&&
.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
PATCHY FOG POSSIBLE AT CHO...WITH MVFR VSBYS AROUND SUNRISE. VFR
CONDITIONS TDA...ALTHOUGH A BRIEF REDUCTION IN VSBY POSSIBLE LATE
THIS AFTN AND EVE AS SCT SHRA/TSRA MOVE THRU. CHANCES FOR PRECIP TOO
LOW THRU 18Z TO INCLUDE A VCTS IN THE TAFS. THERE IS MORE
UNCERTAINTY IF THIS ACTIVITY MAKES IT FARTHER EAST TOWARD THE I-95
TERMINALS.
PATCHY FOG MAY DEVELOP AGAIN TNGT...ESPECIALLY AT TERMINALS THAT
RECEIVE APPRECIABLE RAINFALL TDA.
SCTD TO NUMEROUS SHRA/TSRA EXPECTED EACH AFTN/EVENING SUNDAY AND
MONDAY. HEAVY RAIN IN SOME CONVECTION COULD CREATE VSBY RESTRICTIONS
AT TIMES. FROPA ON MONDAY NIGHT SHOULD YIELD GENERALLY VFR
CONDITIONS AFTER THAT THROUGH MIDWEEK.
&&
.MARINE...
SLY CHANNELING HAS PRODUCED 20 KT GUSTS IN THE CHSPK BAY. WITH
HIPRES PARKED OFFSHORE...THE PRESSURE GRADIENT WILL REMAIN STRONG
ENOUGH TO YIELD A CONTINUATION OF THE SCA FOR THE CHSPK BAY AND
LOWER TIDAL POTOMAC INTO TNGT.
GUSTY WINDS WILL GRADUALLY SUBSIDE SUNDAY MORNING AS SLY CHANNELING
LESSENS AND WINDS TURN OUT OF THE SOUTHWEST. SCATTERED TO NUMEROUS
SHOWERS AND STORMS ARE EXPECTED SUNDAY AND MONDAY...MAINLY IN THE
AFTERNOON AND EVENING. A FRONTAL PASSAGE MONDAY NIGHT OR TUESDAY
MORNING WILL TURN WINDS OUT OF THE NORTH...BUT THE SYSTEM IS NOT
PARTICULARLY STRONG SO WINDS SHOULD REMAIN GENERALLY LIGHT.
&&
.TIDES/COASTAL FLOODING...
THE COASTAL FLOOD ADVISORY CONTINUES FOR THE WRN BAY COUNTIES IN
CENTRAL MD. HIGH TIDE HAS PASSED IN ANNE ARUNDEL AND BALTIMORE
COUNTIES...BUT ANNAPOLIS IS STILL IN FLOOD STAGE. HIGH TIDE AT
HAVRE DE GRACE OCCURS JUST AFTER SUNRISE.
POSITIVE ANOMALIES ALONG THE WRN SHORE OF THE MD CHSPK BAY HAVE
REMAINED STEADY AROUND 1.25 FT SINCE YDA. WITH SLY FLOW CONTINUING
UP THE BAY...EXPECT THIS STEADY STATE TO CONTINUE TDA. ANOMALIES
OF THIS MAGNITUDE WILL BE ENOUGH TO PRODUCE COASTAL FLOODING AT
ANNAPOLIS THIS AFTN DESPITE IT BEING THE LOWER OF THE TWO HIGH
TIDE CYCLES. THEREFORE...A COASTAL FLOOD ADVISORY HAS BEEN ISSUED
FOR ANNE ARUNDEL COUNTY FOR THIS AFTN.
THE LATEST CBOFS DOES NOT SHOW FLOODING PROBLEMS FOR TNGT. AM NOT
SOLD ON THIS YET WITH SLY FLOW CONTINUING. WILL KEEP THE POTENTIAL
FOR ANOTHER ROUND OF MINOR COASTAL FLOODING W/ TNGT`S HIGH TIDE
CYCLE.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...COASTAL FLOOD ADVISORY UNTIL 8 AM EDT THIS MORNING FOR MDZ007-
011-014.
COASTAL FLOOD ADVISORY FROM NOON TODAY TO 4 PM EDT THIS
AFTERNOON FOR MDZ014.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EDT SUNDAY FOR ANZ530>534-537-
539>541-543.
SMALL CRAFT ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR
ANZ536-538.
&&
$$
SYNOPSIS...JRK
NEAR TERM...JRK
SHORT TERM...JCE
LONG TERM...JCE
AVIATION...JCE/JRK
MARINE...JCE/JRK
TIDES/COASTAL FLOODING...JRK
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1101 AM EDT SAT AUG 31 2013
.SYNOPSIS...
MUGGY AND UNSETTLED WEATHER WILL CONTINUE THROUGH LABOR DAY...WITH
AT LEAST SCATTERED SHOWERS AND THUNDERSTORMS EXPECTED ON A DAILY
BASIS. A COLD FRONT SHOULD CROSS THE REGION MONDAY NIGHT OR EARLY
TUESDAY...WITH COOLER TEMPERATURES TO FOLLOW BY THE MIDDLE OF NEXT
WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1045 AM UPDATE...
ONLY ISOLD SHOWERS THIS MRNG ACRS SUSQUEHANNA REGION UNDER CLDY
SKIES. 12Z MODELS SHOWING CLDS HANGING TUFF THRU THE DAY AS
MOISTURE CONTS TO PUMP UP ALONG BNDRY. SOME DRYING EXPECTED AT
MID-LEVELS THIS AFTN BUT MOISTURE WL RMN LOCKED INTO BLYR. THUS HV
GONE MORE PESSIMISTIC WITH SKY CVR, THO AREAS TO THE SOUTH MAY SEE
BREAKS AT SOME POINT TDA.
HV DROPPED POPS TO ISOLD-SCTD FOR THIS AFTN AS IT WL BE HARD TO
GET ANY THUNDER TO DVLP. HWVR WITH BNDRY LURKING NR THE AREA AND
DWPTS POOLING IN THE 70S ALONG IT AND TEMPS EXPECTED TO CLIMB TO
LWR 80S THIS AFTN, SEEING CAPES ALREADY ARND 1500 J/KG. WEAK MID-
LVL LAPSE RATES ALONG WITH LACK OF HTG AND ANY UL FRCG HARD TO
JUSTIFY LKLY POPS AT THIS POINT. ALSO LWRD MAX TEMPS BY A DEGREE
OR TWO.
PREV DISCO BLO...
5 AM SAT UPDATE... SHWRS/TSTMS CONTINUE TO GRADUALLY DIMINISH IN
COVERAGE EARLY THIS MRNG...AS A LEAD S/WV IMPULSE HAS MOVED TO THE
E...AND THE AMS HAS STABILIZED. WE EXPECT FAIRLY MINIMAL (ISOLD) COVERAGE
FOR THE REST OF THE MRNG...INTO THE EARLY AFTN HRS.
BY/AFTER 18Z...WE SHOULD SEE AN UPTICK IN CONVECTIVE ACTIVITY ONCE
AGN...OWING TO PEAK HEATING/RESULTANT DESTABILIZATION...AND THE
PASSAGE OF ANOTHER S/WV FROM THE ERN LAKES RGN. ML CAPE VALUES OF
1000-2000 J/KG ARE LIKELY...BUT PROGGED DEEP-LYRD SHEAR LOOKS
FAIRLY WEAK (15-20 KT). THUS...TRULY ORGANIZED STORMS SEEM
UNLIKELY...WITH MORE OF THE PULSE VARIETY ANTICIPATED. GIVEN PWAT
VALUES NEAR 1.75"...AND MBE VECTORS AOB 10 KT FOR A TIME LTR
TDY...LOCALIZED HEAVY DOWNPOURS WOULD APPEAR TO BE THE MAIN
CONSEQUENCE.
A FAIR AMT OF CONVECTIVE DEBRIS COVERS THE FA ATTM...AND ALTHOUGH
THESE CLDS MAY THIN OUT SOME TDY (SPCLY ACRS NE PA)...MORE
PERSISTENT CLOUD COVER SHOULD LIMIT HEATING A LTL BIT...AS
COMPARED TO RECENT DAYS. HIGH TEMPS SHOULD RANGE FROM THE MID 70S
ACROSS THE HIGHER TERRAIN OF THE SOUTHERN TUG AND CATSKILL
RGNS...TO THE MID 80S IN PARTS OF THE FINGER LKS RGN...AND DOWN
ACRS THE WYO/LACK VLYS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
530 AM SAT UPDATE... ONCE THE ABV REFERENCED S/WV PUSHES OFF TO
THE TNT...WE SHOULD SEE A DECREASE IN SHWR/TSTM ACTIVITY. THIS
LULL MAY WELL LAST THROUGH MUCH OF THE DAY SUN...GIVEN A RELATIVE
LACK OF MID TO UPR-LVL FORCING. THERE WILL...HOWEVER...CONTINUE
TO BE A FRNTL BNDRY PERCHED JUST TO OUR N AND W THIS PD...SO AN
ISOLD SHWR/TSTM CAN`T BE RULED OUT...AND WE`LL THUS CONTINUE TO
CARRY MOSTLY 15-25% POPS.
BY MON...MODEL AGREEMENT REMAINS FAIRLY GOOD...THAT THE MAIN L/WV
TROUGH WILL DEEPEN INTO THE GREAT LKS RGN...HELPING TO PUSH A
SOMEWHAT STGR COLD FRNT EWD TWDS NY/PA. AS THIS FRNT APPROACHES
FROM THE NW...AND IMPROVED UPR JET DYNAMICS EVOLVE ACRS CNY/NE PA
DURG THE DAY MON...WE SHOULD SEE MORE WIDESPREAD SHWRS/TSTMS ONCE
AGN. AS A RESULT...WE`LL CONTINUE TO ADVERTISE LIKELY POPS (NEAR
60%).
DEPENDING ON THE DEGREE OF HEATING/DESTABILIZATION...LOCALLY
STG/SVR STORMS WOULD BE PSBL...GIVEN BETTER FORCED LIFT AND VERT
SHEAR. THE AMT OF INSOLATION IS IN QUESTION...THOUGH...AS WE COULD
SEE A FAIR AMT OF PRE-FRNTL CLOUD COVER. ALSO...THE MODELS
CONTINUE TO ADVERTISE THE DVLPMT OF A PRE-FRNTL/LEE-SIDE TROUGH ON
MON AFTN...FROM ERN PA SWD INTO THE DELMARVA RGN. IT`S ALSO
UNCLEAR ATTM HOW MUCH OF AN IMPACT THIS FEATURE WILL HAVE ON TSTM
EVOLUTION/INTENSITY IN OUR CWA.
ALTHOUGH IT WILL REMAIN MUGGY ON MON (SFC DEW PTS 65-70F)...MAX
TEMPS MAY BE A LTL LWR THAN PREV DAYS (MID 70S-LWR 80S)...GIVEN
THE POTENTIAL FOR MORE CLOUD COVER.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
315 PM EDT UPDATE...
MADE MINOR ADJUSTMENTS TO PREVIOUS FORECASTS. MODELS THIS
AFTERNOON AGAIN ARE IN GOOD AGREEMENT WITH MID WEEK BUT DISAGREE
GREATLY IN THE EXTENDED. SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE THROUGH LATE TUESDAY NIGHT. WENT WITH MORE OF A ECMWF/CMC
BLEND. LEANED MORE TOWARDS ECMWF GUIDANCE SINCE THIS MODEL HAS
BEEN MOST CONSISTENT WITH PREVIOUS RUNS. TUESDAY A COLD FRONT WILL
PASS THROUGH THE REGION BRINGING CAA TO THE NE PA AND C NY. MODELS
STILL DIFFER GREATLY IN THE EXTENDED SO WENT WITH A CONSERVATIVE
PERSPECTIVE TO TEMPS WITH LOWS IN THE UPPER 40S TO LOW 50S AND
HIGHS IN THE UPPER 60S TO LOW 70S WED THRU FRIDAY.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
SHOWER ACTIVITY IS PULLING EAST THIS MORNING. TEMPERATURES
REMAINED UNUSUALLY MILD OVERNIGHT, RESULTING IN LARGER THAN
EXPECTED TDD SPREADS AND A LACK OF FOG DEVELOPMENT.
A BROKEN 5000 FT TO 10000 FT DECK WILL BE OVERHEAD TODAY. HRRR IS
PREDICTING SHOWERS TO BLOSSOM OVER TERMINALS BETWEEN 13Z AND 15Z,
BUT THERE APPEARS LITTLE SUPPORT FOR THIS. SO WILL STICK TO A
MAINLY DRY FORECAST THROUGH EARLY AFTERNOON WITH ISOLATED SHOWER
ACTIVITY NOT LIKELY TO DIRECTLY AFFECT TERMINALS.
THUNDERSTORMS MAY BRING MVFR RESTRICTIONS LATE THIS AFTERNOON. THE
BEST CHANCE FOR THUNDER WILL BE BETWEEN 18Z AND 22Z DURING PEAK
HEATING.
OUTLOOK...
SUN-WED...POTENTIAL FOR MVFR IN SCTD SHRA/TSRAS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...MLJ
NEAR TERM...MLJ/PVN
SHORT TERM...MLJ
LONG TERM...KAH
AVIATION...DJP
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
632 AM EDT SAT AUG 31 2013
.SYNOPSIS...
MUGGY AND UNSETTLED WEATHER WILL CONTINUE THROUGH LABOR DAY...WITH
AT LEAST SCATTERED SHOWERS AND THUNDERSTORMS EXPECTED ON A DAILY
BASIS. A COLD FRONT SHOULD CROSS THE REGION MONDAY NIGHT OR EARLY
TUESDAY...WITH COOLER TEMPERATURES TO FOLLOW BY THE MIDDLE OF NEXT
WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
5 AM SAT UPDATE... SHWRS/TSTMS CONTINUE TO GRADUALLY DIMINISH IN
COVERAGE EARLY THIS MRNG...AS A LEAD S/WV IMPULSE HAS MOVED TO THE
E...AND THE AMS HAS STABILIZED. WE EXPECT FAIRLY MINIMAL (ISOLD) COVERAGE
FOR THE REST OF THE MRNG...INTO THE EARLY AFTN HRS.
BY/AFTER 18Z...WE SHOULD SEE AN UPTICK IN CONVECTIVE ACTIVITY ONCE
AGN...OWING TO PEAK HEATING/RESULTANT DESTABILIZATION...AND THE
PASSAGE OF ANOTHER S/WV FROM THE ERN LAKES RGN. ML CAPE VALUES OF
1000-2000 J/KG ARE LIKELY...BUT PROGGED DEEP-LYRD SHEAR LOOKS
FAIRLY WEAK (15-20 KT). THUS...TRULY ORGANIZED STORMS SEEM
UNLIKELY...WITH MORE OF THE PULSE VARIETY ANTICIPATED. GIVEN PWAT
VALUES NEAR 1.75"...AND MBE VECTORS AOB 10 KT FOR A TIME LTR
TDY...LOCALIZED HEAVY DOWNPOURS WOULD APPEAR TO BE THE MAIN
CONSEQUENCE.
A FAIR AMT OF CONVECTIVE DEBRIS COVERS THE FA ATTM...AND ALTHOUGH
THESE CLDS MAY THIN OUT SOME TDY (SPCLY ACRS NE PA)...MORE
PERSISTENT CLOUD COVER SHOULD LIMIT HEATING A LTL BIT...AS
COMPARED TO RECENT DAYS. HIGH TEMPS SHOULD RANGE FROM THE MID 70S
ACROSS THE HIGHER TERRAIN OF THE SOUTHERN TUG AND CATSKILL
RGNS...TO THE MID 80S IN PARTS OF THE FINGER LKS RGN...AND DOWN
ACRS THE WYO/LACK VLYS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
530 AM SAT UPDATE... ONCE THE ABV REFERENCED S/WV PUSHES OFF TO
THE TNT...WE SHOULD SEE A DECREASE IN SHWR/TSTM ACTIVITY. THIS
LULL MAY WELL LAST THROUGH MUCH OF THE DAY SUN...GIVEN A RELATIVE
LACK OF MID TO UPR-LVL FORCING. THERE WILL...HOWEVER...CONTINUE
TO BE A FRNTL BNDRY PERCHED JUST TO OUR N AND W THIS PD...SO AN
ISOLD SHWR/TSTM CAN`T BE RULED OUT...AND WE`LL THUS CONTINUE TO
CARRY MOSTLY 15-25% POPS.
BY MON...MODEL AGREEMENT REMAINS FAIRLY GOOD...THAT THE MAIN L/WV
TROUGH WILL DEEPEN INTO THE GREAT LKS RGN...HELPING TO PUSH A
SOMEWHAT STGR COLD FRNT EWD TWDS NY/PA. AS THIS FRNT APPROACHES
FROM THE NW...AND IMPROVED UPR JET DYNAMICS EVOLVE ACRS CNY/NE PA
DURG THE DAY MON...WE SHOULD SEE MORE WIDESPREAD SHWRS/TSTMS ONCE
AGN. AS A RESULT...WE`LL CONTINUE TO ADVERTISE LIKELY POPS (NEAR
60%).
DEPENDING ON THE DEGREE OF HEATING/DESTABILIZATION...LOCALLY
STG/SVR STORMS WOULD BE PSBL...GIVEN BETTER FORCED LIFT AND VERT
SHEAR. THE AMT OF INSOLATION IS IN QUESTION...THOUGH...AS WE COULD
SEE A FAIR AMT OF PRE-FRNTL CLOUD COVER. ALSO...THE MODELS
CONTINUE TO ADVERTISE THE DVLPMT OF A PRE-FRNTL/LEE-SIDE TROUGH ON
MON AFTN...FROM ERN PA SWD INTO THE DELMARVA RGN. IT`S ALSO
UNCLEAR ATTM HOW MUCH OF AN IMPACT THIS FEATURE WILL HAVE ON TSTM
EVOLUTION/INTENSITY IN OUR CWA.
ALTHOUGH IT WILL REMAIN MUGGY ON MON (SFC DEW PTS 65-70F)...MAX
TEMPS MAY BE A LTL LWR THAN PREV DAYS (MID 70S-LWR 80S)...GIVEN
THE POTENTIAL FOR MORE CLOUD COVER.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
315 PM EDT UPDATE...
MADE MINOR ADJUSTMENTS TO PREVIOUS FORECASTS. MODELS THIS
AFTERNOON AGAIN ARE IN GOOD AGREEMENT WITH MID WEEK BUT DISAGREE
GREATLY IN THE EXTENDED. SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE THROUGH LATE TUESDAY NIGHT. WENT WITH MORE OF A ECMWF/CMC
BLEND. LEANED MORE TOWARDS ECMWF GUIDANCE SINCE THIS MODEL HAS
BEEN MOST CONSISTENT WITH PREVIOUS RUNS. TUESDAY A COLD FRONT WILL
PASS THROUGH THE REGION BRINGING CAA TO THE NE PA AND C NY. MODELS
STILL DIFFER GREATLY IN THE EXTENDED SO WENT WITH A CONSERVATIVE
PERSPECTIVE TO TEMPS WITH LOWS IN THE UPPER 40S TO LOW 50S AND
HIGHS IN THE UPPER 60S TO LOW 70S WED THRU FRIDAY.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
SHOWER ACTIVITY IS PULLING EAST THIS MORNING. TEMPERATURES
REMAINED UNUSUALLY MILD OVERNIGHT, RESULTING IN LARGER THAN
EXPECTED TDD SPREADS AND A LACK OF FOG DEVELOPMENT.
A BROKEN 5000 FT TO 10000 FT DECK WILL BE OVERHEAD TODAY. HRRR IS
PREDICTING SHOWERS TO BLOSSOM OVER TERMINALS BETWEEN 13Z AND 15Z,
BUT THERE APPEARS LITTLE SUPPORT FOR THIS. SO WILL STICK TO A
MAINLY DRY FORECAST THROUGH EARLY AFTERNOON WITH ISOLATED SHOWER
ACTIVITY NOT LIKELY TO DIRECTLY AFFECT TERMINALS.
THUNDERSTORMS MAY BRING MVFR RESTRICTIONS LATE THIS AFTERNOON. THE
BEST CHANCE FOR THUNDER WILL BE BETWEEN 18Z AND 22Z DURING PEAK
HEATING.
OUTLOOK...
SUN-WED...POTENTIAL FOR MVFR IN SCTD SHRA/TSRAS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...MLJ
NEAR TERM...MLJ
SHORT TERM...MLJ
LONG TERM...KAH
AVIATION...DJP
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
652 AM CDT SAT AUG 31 2013
UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND SUNDAY
ISSUED AT 432 AM CDT SAT AUG 31 2013
MAIN CONCERNS THIS PERIOD ON SKY TRENDS EARLY...THEN PCPN CHANCES
WITH EXPECTED FRONTAL PASSAGE.
OVERALL NO REAL CHANGE TO FORECAST. MODELS CONTINUE TO BE IN GOOD
AGREEMENT WITH SOME MINOR TIMING DIFFERENCES WITH FRONT. GFS AND
00Z ECMWF HAD FAIRLY GOOD HANDLE ON CURRENT PCPN TRENDS SO
FOLLOWED FOR MUCH OF THIS FORECAST.
LATEST MSAS ANALYSIS SHOWS WEAK HIGH PRESSURE OVER STATE...WITH
WEAK WAVE MOVING ALONG FRONT OVER NORTHERN IL. FURTHER TO THE
WEST..COLD FRONT EXTENDS SOUTHWEST THROUGH WESTERN DAKOTAS FROM
LOW OVER LAKE WINNEPEG AREA. SATELLITE IMAGERY SHOWING LOW CLOUDS
EXPANDING WESTWARD OFF LAKE AND BAY INTO CENTRAL WI. SOME HIGH
CLOUDS AND PATCHES OF LOW CLOUDS OUT OF UPPER MI MOVING THROUGH
FAR NORTHERN WI. FOG HAS REMAINED PATCHY...MAINLY OVER NORTH
CENTRAL WI. MOVEMENT OF WAVE ALONG FRONT TO SOUTH HAS HELPED TO
MAINTAIN GRADIENT OVER EASTERN AND CENTRAL WI. HAVE BACKED OFF ON
FOG COVERAGE. HRRR CURRENTLY HANDLING LOW CLOUD COVERAGE FAIRLY
WELL WITH CLOUDS SPREADING INTO PARTS OF CENTRAL WI BY 12Z...THEN
DIMINISHING THROUGH MID TO LATE MORNING. LOWERED FEW TEMPS TO
ACCOUNT FOR CLOUDS.
MODELS CONTINUE TO FOCUS PCPN OVER CWA BETWEEN 06-18Z AS DYNAMICS
WITH UPPER WAVE AND SURFACE FRONT MOVE THROUGH STATE. EXACT COVERAGE
IN QUESTION WITH CONVECTIVE ELEMENTS...SO DID NOT MAKE SIG CHANGE
TO POP CATEGORIES ONLY SLOWING DOWN TIMING BY FEW HOURS.
INSTABILITY OVER REGION MARGINAL LIMITING SEVERE POTENTIAL.
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY
ISSUED AT 432 AM CDT SAT AUG 31 2013
MODELS CONTINUED TO GENERATE SMALL AREAS OF QPF ON SUNDAY NIGHT
WITH THE AREA STILL IN CYCLONIC FLOW BEHIND DEPARTING LOW
PRESSURE. HAVE INCLUDED CHANCE/SLIGHT CHANCE FOR SHOWERS ACROSS
MAINLY THE EASTERN AND NORTHERN PARTS OF THE AREA AS A RESULT.
DRIER CONDITIONS ARE THEN EXPECTED AS SURFACE HIGH PRESSURE MOVES
IN AND AN UPPER LEVEL RIDGE AMPLIFIES OVER THE WESTERN
CONUS...LEAVING THE AREA IN NW/WNW FLOW ALOFT. A SHORT WAVE IN THE
UPPER FLOW IS EXPECTED TO PASS WELL TO THE NORTHEAST OF THE STATE
AROUND THE MIDDLE OF THE WEEK AS A SURFACE COLD FRONT MOVES
THROUGH WISCONSIN. A DRY FRONTAL PASSAGE IS FORECAST FOR NOW SINCE
THERE WILL BE LITTLE MOISTURE AHEAD OF THE FRONT.
TEMPERATURES ARE LIKELY TO BE NEAR OR A BIT ABOVE NORMAL...EXCEPT
FOR SUNDAY NIGHT THROUGH MONDAY NIGHT IN THE WAKE OF THE APPROACHING
COLD FRONT.
&&
.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 625 AM CDT SAT AUG 31 2013
CONCERNS THIS MORNING ON FOG AND LOW CLOUDS. WITH ONLY SCATTERED
HIGH CLOUDS OVER FAR NORTHERN WI THIS MORNING EXPECT VSBYS TO
QUICKLY IMPROVE. LOW CLOUDS OVER EASTERN TAF SITES WILL LINGER A
BIT LONGER...WITH INVERSION AND LIGHT WINDS. MODELS SUGGEST
DIMINISHING MID TO LATE MORNING. HIGH IFR OR MVFR CIGS EXPECTED
TIL THEN. UPPER DISTURBANCE AND COLD FRONT TO BRING CHANCE OF
THUNDERSTORMS LATE TONIGHT TO WESTERN TAF SITES.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....TE
LONG TERM......MG
AVIATION.......TE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
634 AM CDT SAT AUG 31 2013
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 330 AM CDT SAT AUG 31 2013
IMMEDIATE ISSUE TO DEAL WITH EARLY THIS MORNING IS ONGOING SHOWER
AND THUNDERSTORM ACTIVITY ACROSS FAR SOUTHWEST WI INTO NORTHEAST IA.
RAIN RATES HAVE BEEN FAIRLY HEAVY WITH THESE CLUSTERS OF SHOWERS AND
THUNDERSTORMS WITH 1-3 INCHES INDICATED IN 3-HRLY DUAL POL RADAR
ESTIMATES. THESE SHOWERS AND STORMS ARE THE RESULT OF A CLOSED 925MB
CYCLONIC CIRCULATION OVER CENTRAL IA AND WIND CONVERGENCE TO THE
NORTHEAST OF THIS LOW. THIS CONVERGENCE IN TURN IS WORKING ON HIGHER
PRECIPITABLE WATER VALUES ACROSS NORTHEAST IA INTO FAR SOUTHWEST WI.
RAP SHOWS THIS LOW AND CONVERGENCE/RESULTANT SHOWERS AND
THUNDERSTORMS SLIPPING SOUTH AND EAST OF THE AREA BY DAWN.
OTHERWISE...WATER VAPOR IMAGERY AND RAP 500MB ANALYSIS SHOWING
ANOTHER FAIRLY VIGOROUS MID-LEVEL SHORTWAVE TROUGH MOVING EAST
ACROSS CENTRAL DAKOTAS/NEBRASKA. RADAR MOSAIC SHOWING A CLUSTER OF
THUNDERSTORMS ALONG THE ND/SD BORDER WHERE SURGE OF 850MB MOISTURE
TRANSPORT WAS OCCURING AHEAD OF THE MID-LEVEL WAVE. THIS WILL BE OUR
WEATHER-MAKER FOR TONIGHT INTO SUNDAY.
FOR TODAY...ONCE THE SHOWERS AND STORMS DEPART FAR SOUTHERN PORTION
OF THE AREA THIS MORNING...WEAK RIDGE OF HIGH PRESSURE WILL PROVIDE
SLIGHTLY DRIER AND COOLER CONDITIONS. WILL SEE SOME LOW CLOUDS
ALONG/SOUTH OF I-90 THIS MORNING...BUT SHOULD BURN OFF BY LATE
MORNING. WITH MOSTLY SUNNY SKIES THROUGH THE REST OF THE DAY...LOOK
FOR HIGHS IN THE 80-85 DEGREE RANGE WITH DRIER DEW POINTS IN THE
LOWER TO MIDDLE 60S.
AFOREMENTIONED MID-LEVEL WAVE/SURFACE COLD FRONT MOVES TOWARD THE
AREA TONIGHT...AND MAKING PASSAGE ACROSS THE AREA SUNDAY MORNING FOR
A DECENT SHOT AT SOME SHOWERS AND THUNDERSTORMS. MODELS ARE SHOWING
BETTER MOISTURE TRANSPORT HEADING NORTH OF THE AREA...TIED TO BETTER
FORCING OF THE MID-LEVEL WAVE AND PROXIMITY TO SURFACE LOW OVER
SOUTHERN ONTARIO CANADA. FOR THIS REASON...KEPT LIKELY/HIGHER-END
CHANCE POPS NORTH OF I-94...AND TAPERING OFF SOUTH OF THIS. BEST
CHANCES SEEM TO CENTERED IN DURING THE 06-12Z TIME FRAME. THERE MAY
BE SOME UPSCALE IN THE INTENSITY OF THE SHOWERS/THUNDERSTORMS ACROSS
THE EAST IN THE 15Z-21Z TIME FRAME AS 0-1KM MLCAPE INCREASES INTO
THE 1500-2500J/KG RANGE ALONG WITH INCREASING 0-3KM BULK SHEAR. WILL
HAVE TO KEEP AND EYE ON THIS FOR SEVERE POTENTIAL...ESPECIALLY IF
THE FRONT SLOWS SOME AND INSTABILITY IS ALLOWED TO BUILD MORE AHEAD
OF THE FRONT.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 330 AM CDT SAT AUG 31 2013
GFS/ECMWF IN GOOD AGREEMENT SUNDAY NIGHT THROUGH TUESDAY IN BRINGING
HIGH PRESSURE ACROSS THE AREA IN NORTHWEST FLOW ALOFT FOR DRIER AND
COOLER WEATHER. LOOK FOR HIGHS SUNDAY AND MONDAY IN THE 70S WITH
OVERNIGHT LOWS SUNDAY NIGHT IN THE 50S AND IN THE UPPER 40S/NEAR 50
MONDAY NIGHT. ALSO...LOOKS LIKE A GOOD CHANCE OF PATCHY/AREAS OF FOG
MONDAY NIGHT ESPECIALLY IN THE RIVER VALLEYS AS THE HIGH SETTLES
OVERHEAD.
SOME WARMING EXPECTED ON WEDNESDAY AHEAD OF A COLD FRONT DROPPING
SOUTH OUT OF CANADA WITH HIGHS TOPPING OFF IN THE UPPER 70S TO THE
LOWER 80S. MODELS SHOW THIS FRONT CONTINUING TO SINK SOUTH ACROSS
THE AREA WEDNESDAY NIGHT. THE ECMWF IS MOSTLY DRY WITH THIS FROPA
WHILE THE GFS WANTS TO CONVECT ALONG/AHEAD OF THE FRONT. HAVE
INCLUDED A SLIGHT CHANCE OF SHOWERS/THUNDERSTORMS FOR NOW FOR AREAS
ALONG/SOUTH OF I-94.
FOR THURSDAY THROUGH FRIDAY...COOLER/OVERALL DRY NORTHWEST FLOW
ALOFT WILL PREVAIL AS UPPER LEVEL RIDGING BUILDS OVER THE PLAINS.
LOOKING FOR HIGHS IN THE 70S ON THURSDAY AND IN THE UPPER 70S/LOWER
80S FRIDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 633 AM CDT SAT AUG 31 2013
UNDER WEAK HIGH PRESSURE...SOME MORNING MVFR CLOUDS ARE AROUND THE
TAF SITES. THIS CLOUD DECK IS PATCHY AND IT MAY MOVE IN AND OUT OF
THE AIRFIELDS THIS MORNING BEFORE CLEARING. THERE ARE SOME HIGHER
IFR CLOUDS AROUND TOO...SO THIS MAY BOUNCE INTO KRST FOR PERIODS.
KLSE SHOULD REMAIN MVFR.
THE REMINDER OF THE PERIOD SHOULD BE VFR AS A COLD FRONT
APPROACHES THE AIRFIELDS FROM THE NORTHWEST TONIGHT. EVENING
THUNDERSTORMS NEAR THE DAKOTAS/MINNESOTA WILL BE QUITE STRONG AND
MOVE EAST TOWARD KRST DURING THE EVENING. HOWEVER...THEY ARE
EXPECTED TO RAPIDLY WEAKEN AS THE ATMOSPHERE STABILIZES.
THUS...HAVE INCLUDED A VCSH THIS EVENING FOR DEBRIS REMAINING FROM
THE THUNDERSTORMS SHIFTING EAST INTO KLSE/KRST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION...BAUMGARDT
AREA FORECAST DISCUSSION
NWS TUCSON AZ
910 AM MST SAT AUG 31 2013
.SYNOPSIS...EXPECT ISOLATED TO SCATTERED MAINLY AFTERNOON AND
EVENING THUNDERSTORMS THIS HOLIDAY WEEKEND AND DURING THE UPCOMING
WEEK. A WARMING TREND WILL ALSO OCCUR THROUGH TUESDAY FOLLOWED BY
ABOVE AVERAGE DAYTIME TEMPERATURES LATER IN THE WEEK.
&&
.DISCUSSION...CLEAR SKIES OR MOSTLY CLEAR SKIES WERE ONGOING ACROSS
GREENLEE/GRAHAM/COCHISE COUNTIES WITH PARTLY CLOUDY SKIES TO CLOUDY
SKIES FROM TUCSON WWD. AMPLE MOISTURE CONTINUES ACROSS SE AZ WITH
DEWPOINTS VALID 16Z GENERALLY IN THE 60S. 31/12Z KTWC SOUNDING TOTAL
PRECIP WATER WAS 1.64 INCHES...AND THE BLENDED TOTAL PRECIP WATER
IMAGERY PRODUCT DEPICTED VALUES RANGING FROM 1.25 INCHES NEAR THE
NEW MEXICO BORDER TO NEARLY 2.00 INCHES ACROSS FAR WRN PIMA COUNTY.
31/12Z UPPER AIR PLOTS DEPICTED EXPANSIVE RIDGE ALOFT ACROSS THE
WESTERN AND CENTRAL CONUS...AND A VERY WEAK MID-LEVEL STEERING FLOW
OVER SE AZ.
31/12Z NAM AND 31/14Z RUC HRRR WERE SIMILAR WITH DEPICTING SHOWERS/
TSTMS THIS AFTERNOON AND THIS EVENING TO BE CONFINED TO MAINLY NEAR
THE MOUNTAINS. ANOTHER SOMEWHAT PROMINENT AREA FOR SHOWERS/TSTMS IS
PROGGED TO BE ACROSS SANTA CRUZ/SWRN COCHISE COUNTIES. THE BULK OF
SHOWERS/TSTMS SHOULD END BY AROUND MIDNIGHT. HOWEVER...ENOUGH
MOISTURE EXISTS TO JUSTIFY A SLIGHT CHANCE OF SHOWERS ACROSS THE
AREA LATE TONIGHT.
HIGH TEMPS TODAY WILL BE SIMILAR TO FRI...AND WILL AVERAGE A FEW
DEGS BELOW NORMAL. PLEASE REFER TO THE PREVIOUS DISCUSSION SECTION
BELOW FOR ADDITIONAL DETAIL.
&&
.PREV DISCUSSION /333 AM MST SAT AUG 31 2013/...MUCH DRIER AND
WARMER ON SUNDAY...THE FIRST DAY OF METEOROLOGICAL FALL...WITH
PRECIPITABLE WATER VALUES PROGGED TO BE LESS THAN ONE INCH EAST OF
TUCSON TO 1.5" IN THE WEST, ONLY EXPECTING ISOLATED COVERAGE WITH
BEST CHANCES UP IN THE WHITES.
MONDAY...A LITTLE MORE AREAL COVERAGE IN STORMS AS SOME THE AREA
PICKS UP A BIT OF MOISTURE FROM THE SOUTH. HIGHS A COUPLE DEGREES
WARMER THAN SUNDAY.
TUESDAY...MID-LEVEL EASTERLY STEERING FLOW INCREASES ACROSS THE AREA
AS INVERTED TROF PUSHES ACROSS NORTHERN MEXICO. THIS SHOULD LEAD TO
AN INCREASE IN AREAL COVERAGE OF STORM. CURRENT POP FORECAST MAY BE
UNDERDONE.
WEDNESDAY THROUGH FRIDAY...DRIER AIR PUSHES BACK ACROSS THE AREA
LIMITING THUNDERSTORM ACTIVITY TO ISOLATED COVERAGE.
&&
.AVIATION...ISOLD-SCTD TSRA/SHRA INTO THIS EVENING FOLLOWED BY ISOLD
-SHRA LATE TONIGHT AND SUNDAY MORNING. THE STRONGER TSRA WILL
PRODUCE MVFR CIGS/VSBYS AND WIND GUSTS TO NEAR 40 KTS. OTHERWISE...
SURFACE WIND MOSTLY LESS THAN 10 KTS THRU SUNDAY MORNING OR 01/18Z.
AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...SCATTERED SHOWERS AND THUNDERSTORMS WILL PREVAIL
DURING THE UPCOMING WEEK. STRONG...GUSTY AND ERRATIC WINDS WILL
OCCUR WITH THE STRONGER AFTERNOON THUNDERSTORMS. OTHERWISE...EXPECT
NORMAL DIURNAL WIND TRENDS DURING THE UPCOMING WEEK.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
458 PM EDT SAT AUG 31 2013
.SYNOPSIS...
HIGH PRESSURE CENTERED OFF THE COAST WILL DIRECT A MOIST SOUTH
FLOW INTO THE FORECAST AREA THROUGH SUNDAY. A COLD FRONT WILL
MOVE INTO THE AREA TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
SOME SHOWER AND THUNDERSTORM ACTIVITY OVER OUR CENTRAL FA...WITH
SCATTERED THUNDERSTORMS ACROSS THE WESTERN CAROLINAS ALONG A WEAK
SURFACE TROUGH...DRIFTING SE. QUESTION AS TO HOW FAR SOUTH THIS
ACTIVITY WILL GET. LATEST HRRR APPEARS TO BRING SOME OF IT INTO OUR
NORTHERN FA BY WHILE INDICATING SLOW WEAKENING OF THE ACTIVITY. WILL
MAINTAIN HIGHER POPS NORTHERN FA THROUGH THIS EVENING.
TONIGHT...HIGH-LOW LEVEL MOISTURE AND DRY AIR ALOFT SHOULD RESULT
IN CONSIDERABLE STRATUS AND OR FOG LATE TONIGHT. TEMPERATURES NEAR
MOS CONSENSUS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
WV LOOP SHOWS RIDGE OF HIGH PRESSURE ANCHORED ACROSS THE FOUR
CORNERS REGION. THE MODELS HINT AT A WEAK CONVERGENCE AREA/TROUGH
ACROSS THE PIEDMONT THAT WILL LINGER ACROSS THE PIEDMONT/MIDLANDS
THROUGH MONDAY. MODEL TIME SECTIONS INDICATE INCREASING MOISTURE
THROUGH THE PERIOD. THERE WILL BE A SERIES OF SHORTWAVES THAT WILL
DEEPEN THE TROUGH ALONG THE EAST COAST THROUGH THE PERIOD. THIS
ALONG WITH THE EXPECTED COLD FRONT ARRIVING INTO THE REGION ON
TUESDAY. MODELS AND ENSEMBLES INDICATE SLIGHT CHANCE/CHANCE POPS
THROUGH MONDAY NIGHT. BEST CHANCE FOR SHOWERS/THUNDERSTORMS
APPEARS TO BE WITH FRONT ON TUESDAY. GUIDANCE NUMBERS SHOWING
QUITE A RANGE FOR DAYTIME HEIGHTS BUT REASONABLY CLOSE. HAVE
STAYED CLOSE TO A CONSENSUS OF THE GUIDANCE WHICH IS CLOSE TO
CLIMATOLOGY FOR HIGHS AND ABOVE CLIMO FOR LOWS.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
THE MODELS SHOW SOME DRYING BEHIND THE FRONT FOR TUESDAY NIGHT
THROUGH THURSDAY BUT THE FRONT DOES APPEAR TO STALL JUST SOUTH
AND EAST OF THE AREA. THE MODELS DISPLAY A MOISTURE INCREASE FOR
FRIDAY AS ANOTHER SHORTWAVE/SURFACE FRONT APPROACHES FROM THE NW.
THE GFS ENSEMBLE MEANS SUPPORT TEMPERATURES NEAR CLIMATOLOGY FOR
TEMPERATURES. POPS DIMINISHING TUESDAY NIGHT BEHIND THE COLD
FRONT. NEXT CHANCE FOR PRECIPITATION APPEARS TO BE FRIDAY AND
SATURDAY.
&&
.AVIATION /21Z SATURDAY THROUGH THURSDAY/...
MAINLY VFR WITH SCATTERED CUMULUS THROUGH THE AFTERNOON AND EVENING.
SCATTERED THUNDERSTORMS OVER THE MIDLANDS AFFECTING CAE/CUB/OGB
THROUGH 23Z. MVFR OR LOWER CONDITIONS DUE TO LOW CEILING AND OR
FOG AFTER 06Z...MORE LIKELY TOWARD 12Z. IMPROVING CONDITIONS TO
VFR BY 15Z. DIURNALLY DRIVEN SCATTERED CONVECTION EXPECTED SUNDAY
AFTERNOON.
EXTENDED AVIATION OUTLOOK...AFTERNOON CONVECTION IS EXPECTED TO
INCREASE IN COVERAGE MON/TUE WITH THE NEXT FRONT MOVING INTO THE
AREA.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
210 PM MDT SAT AUG 31 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 150 PM MDT SAT AUG 31 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW WEAKENED H5 RIDGE
EXTENDING ACROSS THE SW HALF OF THE CWA WITH WEST TO NORTHWEST FLOW
BEGINNING TO SHIFT SOUTH INTO SOUTHERN WYOMING AND MOST OF NEBRASKA.
A STRONG SHORTWAVE TROUGH HAS KICKED A COLD FRONT SOUTH TO THE NE
PANHANDLE. AHEAD OF THIS FEATURE WEAK MID LEVEL FRONTOGENETICAL
FORCING COMBINED WITH AN EXITING SHORTWAVE TROUGH OVER EASTERN
NEBRASKA LED TO LIGHT SHOWER/ISOLATED THUNDERSTORM DEVELOPMENT THIS
MORNING. LATEST RADAR TRENDS SHOW THIS ACTIVITY LINGERING OVER THE
CWA...WITH ADDITIONAL ACTIVITY DEVELOPING UPSTREAM OVER THE HIGHER
TERRAIN IN CENTRAL COLORADO AHEAD OF A WEAKER SHORTWAVE TROUGH OVER
EASTERN WYOMING.
AS THE SHORTWAVE TROUGH OVER WYOMING DROPS SOUTH TONIGHT IT WILL
HELP PUSH THE COLD FRONT SOUTH INTO NW KANSAS...WITH LARGE SCALE
FORCING OVERSPREADING OUR CWA. EARLY AFTERNOON SHOWER/THUNDERSTORM
ACTIVITY SHOULD INCREASE IN COVERAGE THROUGH 00Z IN RESPONSE TO THE
INCREASE IN LARGE SCALE SUPPORT AND FURTHER DESTABILIZATION. PWATS
REMAIN VERY HIGH THROUGH SUNDAY MORNING (1.3-1.5) SO THERE IS PLENTY
OF MOISTURE TO WORK WITH DURING THIS EVENT. AS SHORTWAVE DROPS SOUTH
THERE SHOULD BE AN INCREASE IN COVERAGE BEFORE SUBSIDENCE QUICKLY
MOVES IN FROM THE NORTH AFTER MIDNIGHT. MODELS DO SHOW COLD POOL
LINGERING IMMEDIATELY BEHIND COLD FRONT OVER OUR SOUTHERN CWA
THROUGH SUNDAY MORNING. THIS COLD POOL MAY ACTUALLY LINGER INTO THE
AFTERNOON...WHICH COULD HELP LEAD TO DIURNAL SHOWER/THUNDERSTORM
DEVELOPMENT BEFORE 00Z IN OUR SOUTH...SO I KEPT THUNDERSTORM MENTION
FOR THESE LOCATIONS. BASED ON LATEST HRRR/RUC...I AM STILL UNSURE
ABOUT WHERE BEST COVERAGE WILL DEVELOP...HOWEVER ONGOING 40 POPS
SEEMED REASONABLE RIGHT. INSTABILITY MAY BE MARGINAL ACROSS MUCH OF
OUR CWA THROUGH TONIGHT...SO WE ARE PROBABLY ONLY LOOKING AT AN
ISOLATED SEVERE THUNDERSTORM THREAT. WITH VERY MOIST AIR MASS AND
SLOW STORM MOTIONS I COULDNT HEAVY RAINFALL WITH ANY THUNDERSTORM
ACTIVITY. HOWEVER...IM NOT SURE ABOUT HOW WIDESPREAD THAT THREAT
WILL REALLY BE. WE MAY JUST END UP WITH A GOOD THREAT OF LIGHT
RAIN...WITH A FEW ISOLATED POCKETS OF MODERATE-HEAVY RAINFALL.
REGARDING TEMPS...WITH CLEARING SKIES IN THE NORTH TEMPS HAVE
FINALLY BEGUN TO WARM ACROSS MUCH OF THE CWA...HOWEVER A DOWNWARD
ADJUSTMENT WAS NEEDED TO CATCH CURRENT TRENDS THIS AFTERNOON. AFTER
THE COLD FRONT PUSHES SOUTH TONIGHT A MUCH MORE SEASONABLE AIR MASS
WILL SETTLE OVER OUR CWA. HIGH ARE CURRENTLY PROGGED TO BE IN THE
MID-UPPER 80S SUNDAY...WHICH IS RIGHT ABOUT WHERE WE WOULD EXPECT TO
BE FOR LABOR DAY WEEKEND.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 204 PM MDT SAT AUG 31 2013
THE UPPER RIDGE IS IN PLACE AGAIN OVER THE ROCKIES AND HIGH PLAINS
FROM SUNDAY NIGHT THROUGH ALL OF NEXT WEEK. DIFFERENCES BEGIN TO
SHOW UP IN MODEL PROGRESSIONS OF THE UPPER LOW CENTER RIDING UP
OVER THE RIDGE IN THE PACIFIC NORTHWEST AND THE OVERALL FLATTENING
OF THE RIDGE IN THE FRIDAY NIGHT THROUGH SATURDAY TIME PERIOD.
SURFACE COOLER HIGH PRESSURE AREA STAYS MOSTLY OVER THE CENTRAL
PLAINS AND CENTRAL HIGH PLAINS SUNDAY NIGHT AND MONDAY BEFORE
PUSHING FURTHER EAST WITH A DEEPENING LEE TROUGH THAT PERSISTS IN
THE VICINITY OF THE EASTERN COLORADO BORDER. WITH SOUTHERLY FLOW
ACROSS THE FORECAST AREA...EXPECT MORE DRY AND WARM CONDITIONS
THROUGH THE UPCOMING WORK WEEK AND NEXT WEEKEND WITH HIGHS IN THE
90S AND LOWS IN THE 60S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1130 AM MDT SAT AUG 31 2013
VFR CONDITIONS SHOULD PREVAIL THROUGH THE TAF PERIOD AT BOTH KGLD
AND KMCK. PRIMARY AVIATION CONCERN IS POTENTIAL FOR
SHOWERS/THUNDERSTORMS AT BOTH TERMINALS THIS AFTERNOON/EVENING
WITH COLD FRONT PASSAGE. I LEFT VCTS GROUP IN PLACE AND ADJUSTED
TIMING TO ACCOUNT FOR ACTIVITY INCREASING IN COVERAGE AT KGLD
FIRST AND THEN TRENDING SOUTH DURING THE EVENING. WINDS WILL
GENERALLY BE LESS THAN 10KT AT BOTH TERMINALS WITH FRONT JUST
NORTHEAST...HOWEVER AS THE FRONT MOVES SOUTH TONIGHT WINDS WILL
INCREASE OUT OF THE NORTHEAST WITH GUSTS TO 20KT POSSIBLE THROUGH
SUN MORNING.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...LOCKHART
AVIATION...DR
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
301 PM CDT Sat Aug 31 2013
...UPDATED SHORT TERM...
.SYNOPSIS...
ISSUED AT 300 PM CDT SAT AUG 31 2013
An upper level center of high pressure was located across New Mexico
and the extreme southern High Plains today, as the upper westerly
jet was positioned zonally across the northern Rockies and Northern
Plains. A shortwave was in place across southern Canada, on the
north side of the jet. A hot airmass still encompassed the central
part of the country. 850 mb level temperatures in excess of 20
degrees C extended from the entire great plains region eastward to
the the Ohio valley. at the surface...a cold front was moving
southward across western South Dakota and extreme western Nebraska.
Another weak stationary front was positioned from the Texas
panhandle northeast into south central Kansas. Easterly surface
winds became more southerly across western Kansas as surface low
pressure slowly filled across the oklahoma panhandle and temperatures
warmed into the 90`s by early afternoon.
&&
.SHORT TERM...(This evening through Sunday)
ISSUED AT 300 PM CDT SAT AUG 31 2013
The immediate concern will revolve around convective chances which
are not great, but non-zero as well. The best location appears along
the diffuse boundary across south central Kansas. The HRRR runs have
somewhat approximated isolated convection occurring by about 23 utc.
A lack of upper winds and lack of shear suggest little chances at
all of severe thunderstorms, and storms should have short life
cycles. A better chance for showers and thunderstorms exists well
into the overnight as the Northern Plains cold front enters the
area. Probabilities increase from north to south around 6z and
after.
Very warm temperatures will continue into this evening. The NAM
models surface temperatures sill around 100 degrees this evening
near the oklahoma line and low 80s persisting after midnight.
Morning lows will likely be warm across all of southwest Kansas,
with a few locations having lows in the upper 70s, however rain
cooled air form a few vigorous storm cluster might augment the
temperatures locally.
Thunderstorms chances are again in the forecast during the afternoon
Sunday as redevelopment is likely along the frontal boundary,
wherever it decides to stall out.
.LONG TERM...(Sunday night through Saturday)
ISSUED AT 235 PM CDT SAT AUG 31 2013
A cold front will move across Kansas tonight as a vigorous upper
level trough moves from southeast Saskatchewan to the Great Lakes,
and a brief period of near climatological temperatures should extend
into Monday. However, the anticyclone centered over the Rockies will
build back into the Central Plains early next week, and several days
of warm, quiet weather will follow. Unless rainfall tonight is more
widespread than appears likely, vegetation will become increasingly
drought stressed next week. Reduced evapotranspiration may allow
more solar radiation to covert into sensible heat, and temperatures
in the mid to upper 90s can be expected on most days.
Tropical thunderstorm activity has been strongly suppressed from
about 130E to the dateline, although an area of enhanced
thunderstorms has been persistent in the Indian Ocean southwest of
India. Most of the numerical models suggest that a coherent tropical
cluster that projects onto a Madden Julian Oscillation (MJO) will
amplify in Phase 1 of the Wheeler-Hendon Phase Space Diagram early
in September and propagate slowly east before losing identity in the
Indian Ocean. There is little correlation between the MJO and
sensible weather in the central plains at this time of the year, but
there may be in increased chance for tropical waves to come off
Africa into the eastern Atlantic next week.
Global relative angular momentum remains below climatology, but
mountain torque has increased in recent days. The atmosphere will be
best represented by Phase 4-5 of the Weickmann-Berry Global Wind
Oscillation, which correlates with anticyclonic flow in the western
and central United States. The deterministic model solutions all
favor ridging from the central Rockies across the central and
southern United States through the first ten days of September with
only minor synoptic scale differences. The 12Z GFS has trended
toward the 00Z ECMWF in handling the closed cyclone near 140W that
wallows into the northern plains 9-10 September and largely was
followed for grid adjustments, although confidence in behavior of
this cyclone is low.
Upslope flow into the foothills in eastern Colorado Sunday evening
should favor thunderstorm development, but the upper level flow will
be light and largely meridional over western Kansas. Most of the
thunderstorms will remain west of the Colorado border, but there is
a nonzero chance that a thunderstorm could reach far southwest
Kansas before midnight Sunday night. Cool high pressure with light
winds and low level dewpoints in the 50s will allow for strong
radiational cooling, and lows will drop into the upper 50s in most
areas Tuesday morning. Another minor trough dropping into the mean
long wave trough near 80W will support a weak boundary that may
survive into northern Kansas Wednesday night, but limited
instability and weak flow aloft do not favor an organized
thunderstorm event. As the upper level trough near 140W moves across
the Northern Plains around 9 September, a cold front will move into
Kansas and provide another opportunity for thunderstorm development
and a return to more seasonal temperatures.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 106 PM CDT SAT AUG 31 2013
A widespread scattered to broken field of altocumulus was present
over western Kansas and will continue to dissipate through the
afternoon. As surface temperatures rise toward the convective
temperature, isolated thunderstorms may develop around 22-23 utc.
The better chance for thunderstorms impacting the local terminals
will come later tonight as a cold front moves southward from the
dakotas. Although confidence is not particularly high, tempo
groups have been added to terminals for -TSRA after 6 UTC. With
weak steering flow in low surface based capes, the storm may decay
rapidly buy redevelop early Sunday afternoon along any surface
outflow of the synoptic front.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 69 88 60 89 / 20 20 10 0
GCK 68 88 58 90 / 30 20 10 0
EHA 69 88 64 91 / 20 20 10 10
LBL 70 88 60 92 / 20 20 10 0
HYS 69 88 57 90 / 40 20 0 0
P28 72 95 64 90 / 10 20 10 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...Russell
SHORT TERM...Russell
LONG TERM...Ruthi
AVIATION...Russell
AREA FORECAST DISCUSSION
NWS GOODLAND KS
151 PM MDT SAT AUG 31 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 150 PM MDT SAT AUG 31 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS SHOW WEAKENED H5 RIDGE
EXTENDING ACROSS THE SW HALF OF THE CWA WITH WEST TO NORTHWEST FLOW
BEGINNING TO SHIFT SOUTH INTO SOUTHERN WYOMING AND MOST OF NEBRASKA.
A STRONG SHORTWAVE TROUGH HAS KICKED A COLD FRONT SOUTH TO THE NE
PANHANDLE. AHEAD OF THIS FEATURE WEAK MID LEVEL FRONTOGENETICAL
FORCING COMBINED WITH AN EXITING SHORTWAVE TROUGH OVER EASTERN
NEBRASKA LED TO LIGHT SHOWER/ISOLATED THUNDERSTORM DEVELOPMENT THIS
MORNING. LATEST RADAR TRENDS SHOW THIS ACTIVITY LINGERING OVER THE
CWA...WITH ADDITIONAL ACTIVITY DEVELOPING UPSTREAM OVER THE HIGHER
TERRAIN IN CENTRAL COLORADO AHEAD OF A WEAKER SHORTWAVE TROUGH OVER
EASTERN WYOMING.
AS THE SHORTWAVE TROUGH OVER WYOMING DROPS SOUTH TONIGHT IT WILL
HELP PUSH THE COLD FRONT SOUTH INTO NW KANSAS...WITH LARGE SCALE
FORCING OVERSPREADING OUR CWA. EARLY AFTERNOON SHOWER/THUNDERSTORM
ACTIVITY SHOULD INCREASE IN COVERAGE THROUGH 00Z IN RESPONSE TO THE
INCREASE IN LARGE SCALE SUPPORT AND FURTHER DESTABILIZATION. PWATS
REMAIN VERY HIGH THROUGH SUNDAY MORNING (1.3-1.5) SO THERE IS PLENTY
OF MOISTURE TO WORK WITH DURING THIS EVENT. AS SHORTWAVE DROPS SOUTH
THERE SHOULD BE AN INCREASE IN COVERAGE BEFORE SUBSIDENCE QUICKLY
MOVES IN FROM THE NORTH AFTER MIDNIGHT. MODELS DO SHOW COLD POOL
LINGERING IMMEDIATELY BEHIND COLD FRONT OVER OUR SOUTHERN CWA
THROUGH SUNDAY MORNING. THIS COLD POOL MAY ACTUALLY LINGER INTO THE
AFTERNOON...WHICH COULD HELP LEAD TO DIURNAL SHOWER/THUNDERSTORM
DEVELOPMENT BEFORE 00Z IN OUR SOUTH...SO I KEPT THUNDERSTORM MENTION
FOR THESE LOCATIONS. BASED ON LATEST HRRR/RUC...I AM STILL UNSURE
ABOUT WHERE BEST COVERAGE WILL DEVELOP...HOWEVER ONGOING 40 POPS
SEEMED REASONABLE RIGHT. INSTABILITY MAY BE MARGINAL ACROSS MUCH OF
OUR CWA THROUGH TONIGHT...SO WE ARE PROBABLY ONLY LOOKING AT AN
ISOLATED SEVERE THUNDERSTORM THREAT. WITH VERY MOIST AIR MASS AND
SLOW STORM MOTIONS I COULDNT HEAVY RAINFALL WITH ANY THUNDERSTORM
ACTIVITY. HOWEVER...IM NOT SURE ABOUT HOW WIDESPREAD THAT THREAT
WILL REALLY BE. WE MAY JUST END UP WITH A GOOD THREAT OF LIGHT
RAIN...WITH A FEW ISOLATED POCKETS OF MODERATE-HEAVY RAINFALL.
REGARDING TEMPS...WITH CLEARING SKIES IN THE NORTH TEMPS HAVE
FINALLY BEGUN TO WARM ACROSS MUCH OF THE CWA...HOWEVER A DOWNWARD
ADJUSTMENT WAS NEEDED TO CATCH CURRENT TRENDS THIS AFTERNOON. AFTER
THE COLD FRONT PUSHES SOUTH TONIGHT A MUCH MORE SEASONABLE AIR MASS
WILL SETTLE OVER OUR CWA. HIGH ARE CURRENTLY PROGGED TO BE IN THE
MID-UPPER 80S SUNDAY...WHICH IS RIGHT ABOUT WHERE WE WOULD EXPECT TO
BE FOR LABOR DAY WEEKEND.
.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 211 AM MDT SAT AUG 31 2013
UPPER LEVEL BLOCKING PATTERN WILL CONTINUE OVER THE HIGH PLAINS FOR
THE EXTENDED FORECAST PERIOD...WHICH WILL KEEP WARM AND DRY
CONDITIONS OVER THE FORECAST AREA. THE 500 MB HIGH PRESSURE AREA
WILL BE CENTERED OVER COLORADO FOR TUESDAY AS RIDGE BECOMES MORE
AMPLIFIED INTO THE NORTHERN HIGH PLAINS. ZONAL FLOW WILL BEGIN TO
ENTER THE CENTRAL PLAINS FOR NEXT WEEKEND AS AN UPPER LEVEL LOW
MOVES OUT OF ALBERTA AND ACROSS THE NORTHERN PLAINS. SHORTWAVE
TROUGHS COULD DEVELOP AND MOVE THROUGH THE TRI STATE AREA SATURDAY
AND SUNDAY AS UPPER LEVEL HEIGHTS INCREASE AND RIDGE OF HIGH
PRESSURE BEGINS TO WEAKEN OVER THE SOUTHWEST REGION.
STRONG WARM AIR ADVECTION WILL CONTINUE AT THE SURFACE THROUGH THE
EXTENDED PERIOD...KEEPING SURFACE TEMPERATURES ABOVE AVERAGE IN THE
LOWER 90S. MODEL SOUNDINGS SHOW STABLE UPPER AIR PROFILE THROUGH THE
PERIOD...WITH A LACK OF INSTABILITY PARAMETERS AND AVAILABLE
MOISTURE. SURFACE TEMPERATURES COULD POSSIBLY REACH THE CONVECTIVE
TEMPERATURES...WHICH ARE FORECASTED TO BE IN THE MID TO UPPER 90S.
STRONG CAP COULD BE BROKEN FOR ISOLATED LOCATIONS ALLOWING FOR SOME
SMALL AREAS OF STORM DEVELOPMENT. CHANCES FOR PRECIPITATION ARE
VERY SLIM...WITH WARM AND DRY TREND CONTINUING INTO NEXT WEEKEND.
THE BEST CHANCE TO SEE PRECIPITATION ACROSS THE TRI STATE AREA WOULD
BE FOR NEXT WEEKEND AS UPPER LEVEL PATTERN BEGINS TO LOOK SUPPORTIVE
FOR STORM DEVELOPMENT...BUT MODEL RUNS STILL INDICATE DRY WEATHER AT
PRESENT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1130 AM MDT SAT AUG 31 2013
VFR CONDITIONS SHOULD PREVAIL THROUGH THE TAF PERIOD AT BOTH KGLD
AND KMCK. PRIMARY AVIATION CONCERN IS POTENTIAL FOR
SHOWERS/THUNDERSTORMS AT BOTH TERMINALS THIS AFTERNOON/EVENING
WITH COLD FRONT PASSAGE. I LEFT VCTS GROUP IN PLACE AND ADJUSTED
TIMING TO ACCOUNT FOR ACTIVITY INCREASING IN COVERAGE AT KGLD
FIRST AND THEN TRENDING SOUTH DURING THE EVENING. WINDS WILL
GENERALLY BE LESS THAN 10KT AT BOTH TERMINALS WITH FRONT JUST
NORTHEAST...HOWEVER AS THE FRONT MOVES SOUTH TONIGHT WINDS WILL
INCREASE OUT OF THE NORTHEAST WITH GUSTS TO 20KT POSSIBLE THROUGH
SUN MORNING.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...MK
AVIATION...DR
AREA FORECAST DISCUSSION
NWS WICHITA KS
1247 PM CDT SAT AUG 31 2013
UPDATED 18Z/AVIATION SECTION.
.UPDATE...
ISSUED AT 1141 AM CDT SAT AUG 31 2013
OUTFLOW BOUNDARY FROM OVERNIGHT CONVECTION IN NEB PUSHED ACROSS MOST
OF THE FORECAST AREA THIS MORNING...CURRENTLY WASHING OUT ALONG
HIGHWAY 54. CLOUD DEBRIS AND SOME HIGHER SFC DEWPOINTS PUSHED ACROSS
NE SECTIONS OF THE FORECAST AREA EARLY TODAY....WHICH HAD LED TO
SOME HIGHER SBCAPE VALUES ALONG OR JUST TO THE NORTH OF THIS REMNANT
BOUNDARY. NOT ALOT OF CONVERGENCE NOTED ALONG THIS BOUNDARY...SO
THINK CHANCES OF AN ISOLATED STORM DEVELOPING IN THIS UNSTABLE AIR
ARE SLIM. LATEST HIGH RES HRRR REFLECTIVITY MODEL SHOWS AN ISOLATED
STORM TRYING TO DEVELOP NEAR KEMP LATE THIS AFTERNOON. BUT THINK
THIS CHANCE IS TOO REMOTE FOR NOW TO MENTION IN THE GRIDS/ZONES.
THE MAIN CONCERN WILL BE THE HIGHER SFC DEWPOINTS STILL LOCATED
ACROSS CEN KS...ALONG I-70...WITH SOME CONCERN THAT THIS HIGHER
DEWPOINT AIR MAY REMAIN IN THE UPPER 60S THIS AFTERNOON. WITH
CLOUDS CLEARING OUT...THINK THAT SFC TEMPS WILL WARM TO NEAR THE
CENTURY MARK THIS AFTERNOON IN THIS AREA. SO WITH UPPER 60S
DWPTS...THIS GIVES HEAT INDEX VALUES IN THE 104-108 RANGE. SO THINK
THIS AREA MAY ALSO REACH DANGEROUS HEAT INDICE VALUE THAT WOULD
WARRANT AN EXPANSION OF THE HEAT ADVISORY ALONG I-70. ALSO THINK
THAT CURRENT HEAT ADVISORY OVER SE KS LOOKS FINE AS WELL...GIVEN SFC
DEWPOINTS WILL STAY HIGH IN THIS AREA AS WELL.
KETCHAM
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 300 AM CDT SAT AUG 31 2013
CONVECTION CONTINUES EARLY THIS MORNING FROM NORTHWEST KS TO SOUTH-
CENTRAL NEBRASKA ALONG AND BEHIND AN OUTFLOW BOUNDARY. WEAK
SOUTH-SOUTHWESTERLY WIND AT 850 MB OVERTOP OF THE OUTFLOW BOUNDARY
MAY SUSTAIN THIS ACTIVITY INTO EARLY THIS MORNING. THINK MOST OF IT
WILL STAY JUST NORTH/NORTHWEST OF OUR AREA...BUT WILL INCLUDE A
SLIGHT CHANCE POP BY RUSSELL/GREAT BEND/LINCOLN. CONVECTIVE DEBRIS
CLOUDINESS WILL LIKELY MOVE SOUTHEAST INTO CENTRAL KS THIS MORNING.
IF IT THINS OUT...THICKNESSES SUGGEST SIMILAR HIGHS TO YESTERDAY
AFTERNOON SO HAVE MAINTAINED FORECAST HIGHS OF 99-103. WITH VERY
LIGHT SOUTH WINDS...SOUTHEAST KS WILL PROBABLY BE ABLE TO MAINTAIN
DEWPOINTS AROUND 70 DEGREES INTO THIS AFTERNOON. THIS WILL PUT THEM
INTO HEAT ADVISORY CRITERIA WITH HEAT INDICES REACHING 104-107.
PLANNING A HEAT ADVISORY FROM 17Z-01Z THERE.
A SHORTWAVE TROUGH PRESENTLY OVER ALBERTA/SASKATCHEWAN WILL AMPLIFY
AS IT TRACKS EAST-SOUTHEASTWARD TO THE WESTERN GREAT LAKES BY SUNDAY
AFTERNOON. THE ASSOCIATED COLD FRONT IS STILL SLATED TO MOVE
SOUTHWARD THROUGH OUR AREA VERY LATE TONIGHT THROUGH SUNDAY.
LARGE-SCALE FORCING IS ON THE WEAK SIDE...ALTHOUGH A DECENT
PRECIPITABLE WATER AXIS (AROUND 1.5 INCHES) WILL ACCOMPANY THE
FRONTAL PASSAGE. WIDELY SEPARATED SHOWERS/STORMS WILL BE POSSIBLE
WITH THE FRONT MOVING THROUGH...ALTHOUGH NOT EXPECTING A
WIDESPREAD SOAKING RAIN EVENT. PLACES LUCKY ENOUGH TO RECEIVE RAIN
WILL PROBABLY GET 0.25 INCH OR LESS. COOLER AIR WILL SPREAD IN
BEHIND THE FRONT...FIRST FELT IN CENTRAL KS SUNDAY...AND AREA-WIDE
SUNDAY NIGHT INTO MONDAY.
JMC
.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 300 AM CDT SAT AUG 31 2013
THE RESILIENT UPPER HIGH CENTER WILL RE-STRENGTHEN OVER THE
CENTRAL ROCKIES/HIGH PLAINS TOWARD MID-LATE WEEK WITH LEE TROUGH
DEVELOPMENT IN THE LOW-LEVELS. TEMPERATURES ARE EXPECTED TO WARM
TO ABOUT 5-9 DEGREES ABOVE NORMAL BY THE END OF THE WEEK. RECENT
RUNS OF THE ECMWF HAVE COME AROUND TOWARD THE GFS WITH THIS
SCENARIO...INCREASING FORECAST CONFIDENCE. UNFORTUNATELY...RAIN
CHANCES LOOK NIL.
JMC
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1246 PM CDT SAT AUG 31 2013
VFR CONDITIONS ARE EXPECTED ACROSS THE AREA FOR THE NEXT 24 HOURS.
THE MAIN CONCERN WILL INCREASING MID CLOUDS LATE TONIGHT ACROSS CEN
KS AS CONVECTIVE DEBRIS FROM EXPECTED CONVECTION IN WRN KS DRIFTS
EAST LATE TONIGHT OR EARLY ON SUN. AS THE MID CLOUDS INCREASE...ALSO
WILL SEE A COLD FRONT DROP SOUTH OUT OF NEB EARLY ON SUN MORNING...
WHICH WILL LEAD TO A WIND SHIFT TO THE NORTH FOR CEN KS BY AROUND
12Z/SUN. LIFT ALONG THIS BOUNDARY MAY ALSO LEAD SOME ELEVATED
SHOWERS AND A FEW RUMBLES OF THUNDER FOR CEN KS...SO WILL ADD A VCTS
MENTION FOR CEN KS AROUND 12Z/SUN.
FRONTAL BOUNDARY WILL CONTINUE TO DROP SOUTH SUN MORNING...SHIFTING
THE WINDS TO THE NORTH AT KHUT AND KICT BY AROUND 14-15Z/SUN.
KETCHAM
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 102 73 93 66 / 10 20 20 10
HUTCHINSON 102 72 92 65 / 10 20 20 10
NEWTON 101 73 92 65 / 10 20 20 10
ELDORADO 101 74 93 66 / 10 20 20 10
WINFIELD-KWLD 101 73 96 68 / 10 10 20 10
RUSSELL 101 70 89 62 / 20 30 20 10
GREAT BEND 102 70 89 63 / 10 20 20 10
SALINA 101 72 90 63 / 10 30 20 10
MCPHERSON 101 72 91 64 / 10 20 20 10
COFFEYVILLE 99 73 96 68 / 0 10 20 10
CHANUTE 99 72 93 64 / 10 10 30 10
IOLA 99 74 93 64 / 10 20 30 10
PARSONS-KPPF 99 73 95 66 / 0 10 30 10
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR KSZ033-048-049-
051>053-069>072-094>096-098>100.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1130 AM MDT SAT AUG 31 2013
.UPDATE...
ISSUED AT 852 AM MDT SAT AUG 31 2013
MAIN CHANGE WAS TO ADD MENTION OF THUNDERSTORMS TO FORECAST FOR
THE MORNING PERIOD. RADAR HAS BEEN SHOWING 20-35 DBZ RETURNS
ACROSS MUCH OF THE AREA THIS MORNING...HOWEVER THIS IS MAINLY
VIRGA. RECENT RETURNS HOWEVER HAVE SHOWN BRIEF/ISOLATED CORES OVER
40-45DBZ...WHICH WOULD PROBABLY BE ENOUGH FOR MEASURABLE PRECIP
IN THE CURRENT ENVIRONMENT. WITH SHORTWAVE STILL OVER CENTRAL
NEBRASKA (HIGHLIGHTED BY STRONG PV HEIGHT ANOMALY ON RAP ANALYSIS)
AND STALLED FRONT ALONG THE KS/NE BORDER WE COULD CONTINUE TO SEE
THIS ISOLATED ACTIVITY THROUGH MIDDAY. MODELS SHOW A GENERAL
CLEARING TREND THROUGH NOON BEFORE ACTIVITY BEGINS REDEVELOPING IN
THE WEST...SO I ONLY ADJUSTED TIMING OF CLOUD COVER AND MORNING
POPS. I WILL HAVE TO MONITOR WHAT IMPACT CLOUDS WILL HAVE ON
HIGHS TODAY IF THEY CONTINUE TO LINGER.
&&
.SHORT TERM...(TODAY THROUGH MONDAY NIGHT)
ISSUED AT 346 AM MDT SAT AUG 31 2013
MAIN FORECAST PROBLEM WILL BE PRECIPITATION THROUGH THE WEEKEND...
HOW HOT TO MAKE TODAY...AND HOW MUCH TO COOL DOWN TEMPERATURES
SUNDAY. SATELLITE SHOWING AN AMPLIFIED FLOW OVER THE EASTERN PACIFIC
WITH A FLATTER FLOW OVER THE COUNTRY. MID/UPPER LEVEL RIDGE THAT HAS
PERSISTED FOR A WHILE HAS BEEN FLATTENED AND PUSHED SOUTH BY
SHORTWAVES GOING ACROSS THE TOP OF IT. LOOKS LIKE WE HAVE A BETTER
SUBTROPICAL MOISTURE CONNECTION ACROSS THAN 24 HOURS AGO.
COMPLICATED SURFACE PATTERN WITH A FRONT THAT HAS SAGGED INTO THE
NORTHERN PORTION OF THE AREA. COMBINATION OF THIS BOUNDARY...WEAK
SHORTWAVE TROUGH...AND RIGHT REAR QUADRANT OF THE JET BROUGHT
THUNDERSTORMS TO THE NORTHERN HALF OF THE AREA WITH THE GREATEST
CONCENTRATION NEAR THE KANSAS AND NEBRASKA BORDER. THESE STORMS HAVE
THROWN OUT NUMEROUS OUTFLOW BOUNDARIES.
AT JET LEVEL...MODELS WERE HAVING A LITTLE TROUBLE WITH THE JET
SEGMENT JUST TO OUR NORTH. THEY DID NOT HAVE THE STRONGER WINDS FAR
ENOUGH SOUTH. HERE THE NAM WAS DOING A LITTLE BETTER THAN UKMET...
GFS..AND CANADIAN. AT MID LEVELS...THE CANADIAN AND UKMET WERE
DOING A LITTLE BETTER THAN THE GFS. OUTSIDE OF THE MESOSCALE
INFLUENCES THE CANADIAN WAS DOING THE BEST ON THE LOW LEVEL WIND
AND PRESSURE FIELD. THE GFS WAS DOING A LITTLE BETTER THAN THE
CANADIAN AND SREF ON THE LOW LEVEL THERMAL FIELD.
TODAY/TONIGHT...WEAK RIGHT REAR QUADRANT IS AFFECTING THE AREA NOW
AND IT MAY STILL BE NEAR OR OVER THE NORTHERN PORTION OF THE AREA AT
12Z. THIS WEAKENS OR PULLS AWAY FROM THE AREA AS STRONGER JET
DEVELOPS TO OUR NORTH WITH THE RIGHT FRONT QUADRANT AFFECTING THE
AREA IN THE AFTERNOON. INITIAL SHORTWAVE TROUGH ALSO LOOKS LIKE IT
MOVES EAST OF THE AREA THIS MORNING. BASED ON WHERE CURRENT
THUNDERSTORMS ARE OCCURRING BELIEVE THOSE STORMS SHOULD BE OUT OF
THE AREA BY 12Z. IT IS POSSIBLE THAT THERE MAY BE SOME
THUNDERSTORMS IN THE EAST EARLY. WILL MONITOR AS LONG AS POSSIBLE
BEFORE MAKING THE FINAL DECISION.
HOW MUCH DO CLOUDS HANG AROUND AND OVERNIGHT OUTFLOW BOUNDARIES WILL
AFFECT ALL PARAMETERS OF THE FORECAST. DAY SHIFT WILL HAVE TO PIN
WHERE OUTFLOW BOUNDARIES END UP AND MAY NEED TO ADJUST THE AREA OF
PRECIPITATION. TREND FOR THE INCOMING FRONT AND MID/UPPER LEVEL
SUPPORT HAS BEEN TO BE SLOWER. SO MADE ADJUSTMENTS TO THE
PRECIPITATION GRIDS TO REFLECT THIS. IF MESOSCALE DOES NOT CHANGE
THINGS...THEN EXPECT PRECIPITATION TO DEVELOP IN THE NORTHWEST HALF
IN THE AFTERNOON AND CONTINUE SOUTH AND EAST ACROSS THE AREA INTO
THE OVERNIGHT HOURS.
THIS INITIAL ROUND OF PRECIPITATION WILL BE TIED TO FRONT AND
SHORTWAVE TROUGH. THEN THE ABOVE MENTIONED JET LOOKS TO STAY NORTH OF
THE AREA THROUGH THE EVENING BEFORE COMING SOUTH AFTER 06Z. MOST OF
THE NORTHERN HALF LOOKS TO BE IN THE RIGHT REAR QUADRANT BY 12Z. THIS
IS FURTHER NORTH AT THIS TIME THAN WHAT THE MODELS WERE SHOWING
YESTERDAY. SO EXPECT SOME REDEVELOPMENT FURTHER NORTH BEHIND THE
FRONT.
IF CLOUDS HANG AROUND LONGER...WHICH RIGHT NOW THEY LOOK LIKE THEY
ARE THINNING...AND THE AIR MASS RECOVERS THE OVERNIGHT CONVECTION...
HOT TEMPERATURES ARE EXPECTED AGAIN...ESPECIALLY IN THE SOUTHEAST
PORTION.
SUNDAY/SUNDAY NIGHT...ABOVE MENTIONED JET MOVES ACROSS THE AREA
DURING THE DAY BUT MODELS DIFFER ON HOW FAST. MOST OF THEM HAVE THE
RIGHT REAR QUADRANT STILL AFFECT THE SOUTHERN PORTION OF THE AREA
AT 18Z WITH THE GFS FURTHER NORTH AND AFFECTING MOST OF THE AREA. BY
LATE IN THE AFTERNOON SOME KIND OF JET LIFT IS STILL AROUND OVER THE
SOUTHERN PORTION OF THE AREA. ALL THIS LOOKS TO MOVE SOUTH OF THE
AREA DURING THE EARLY EVENING. PER THE TRENDS AND REASONING MENTIONED
ABOVE...HELD ONTO HIGHER CHANCES PRECIPITATION CHANCES IN THE
MORNING WITH PRECIPITATION POSSIBLY LINGERING INTO THE EARLY
AFTERNOON IN THE FAR SOUTHERN PORTION.
HIGH TEMPERATURES WILL BE MUCH COOLER DUE TO LINGERING
PRECIPITATION/CLOUD COVER...AND UPSLOPE WINDS/COLD AIR ADVECTION.
BASED ON RECENT TRENDS/BEST PERFORMING GUIDANCE ALONG WITH THE
EXPECTED COOLING AT 850 MB...ADJUSTED THOSE TEMPERATURES A LITTLE...
ESPECIALLY COOLER WHERE CLOUDS HANG ON THE LONGEST. CLOUDS LOOK TO
CLEAR OUT OF MOST AREA EXCEPT POSSIBLY THE FAR SOUTHWEST. WINDS
BECOME LIGHT...ESPECIALLY IN THE EAST...SO LOWERED PREVIOUS MIN
FORECAST TO ACCOUNT FOR THIS.
MONDAY/MONDAY NIGHT...MID/UPPER LEVEL RIDGING AND DRIER AIR ALOFT
START BUILDING INTO THE AREA. ALSO PRESSURE GRADIENT INCREASES AS
SURFACE HIGH PULLS OFF TO THE EAST AND LEE TROUGH REDEVELOPS. SO
THIS AND PLENTY OF SUN SHOULD ALLOW TEMPERATURES TO RECOVER FROM
THE PREVIOUS DAY. A WEAK SHORTWAVE TROUGH AND INSTABILITY TRIES TO
SNEAK INTO THE FAR WESTERN PORTION OF THE AREA...ESPECIALLY DURING
THE NIGHT. DUE TO THE INCREASING HEIGHTS AND AIR MASS LOOKING TO BE
CAPPED THERE...KEPT IT DRY.
.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 211 AM MDT SAT AUG 31 2013
UPPER LEVEL BLOCKING PATTERN WILL CONTINUE OVER THE HIGH PLAINS FOR
THE EXTENDED FORECAST PERIOD...WHICH WILL KEEP WARM AND DRY
CONDITIONS OVER THE FORECAST AREA. THE 500 MB HIGH PRESSURE AREA
WILL BE CENTERED OVER COLORADO FOR TUESDAY AS RIDGE BECOMES MORE
AMPLIFIED INTO THE NORTHERN HIGH PLAINS. ZONAL FLOW WILL BEGIN TO
ENTER THE CENTRAL PLAINS FOR NEXT WEEKEND AS AN UPPER LEVEL LOW
MOVES OUT OF ALBERTA AND ACROSS THE NORTHERN PLAINS. SHORTWAVE
TROUGHS COULD DEVELOP AND MOVE THROUGH THE TRI STATE AREA SATURDAY
AND SUNDAY AS UPPER LEVEL HEIGHTS INCREASE AND RIDGE OF HIGH
PRESSURE BEGINS TO WEAKEN OVER THE SOUTHWEST REGION.
STRONG WARM AIR ADVECTION WILL CONTINUE AT THE SURFACE THROUGH THE
EXTENDED PERIOD...KEEPING SURFACE TEMPERATURES ABOVE AVERAGE IN THE
LOWER 90S. MODEL SOUNDINGS SHOW STABLE UPPER AIR PROFILE THROUGH THE
PERIOD...WITH A LACK OF INSTABILITY PARAMETERS AND AVAILABLE
MOISTURE. SURFACE TEMPERATURES COULD POSSIBLY REACH THE CONVECTIVE
TEMPERATURES...WHICH ARE FORECASTED TO BE IN THE MID TO UPPER 90S.
STRONG CAP COULD BE BROKEN FOR ISOLATED LOCATIONS ALLOWING FOR SOME
SMALL AREAS OF STORM DEVELOPMENT. CHANCES FOR PRECIPITATION ARE
VERY SLIM...WITH WARM AND DRY TREND CONTINUING INTO NEXT WEEKEND.
THE BEST CHANCE TO SEE PRECIPITATION ACROSS THE TRI STATE AREA WOULD
BE FOR NEXT WEEKEND AS UPPER LEVEL PATTERN BEGINS TO LOOK SUPPORTIVE
FOR STORM DEVELOPMENT...BUT MODEL RUNS STILL INDICATE DRY WEATHER AT
PRESENT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1130 AM MDT SAT AUG 31 2013
VFR CONDITIONS SHOULD PREVAIL THROUGH THE TAF PERIOD AT BOTH KGLD
AND KMCK. PRIMARY AVIATION CONCERN IS POTENTIAL FOR
SHOWERS/THUNDERSTORMS AT BOTH TERMINALS THIS AFTERNOON/EVENING
WITH COLD FRONT PASSAGE. I LEFT VCTS GROUP IN PLACE AND ADJUSTED
TIMING TO ACCOUNT FOR ACTIVITY INCREASING IN COVERAGE AT KGLD
FIRST AND THEN TRENDING SOUTH DURING THE EVENING. WINDS WILL
GENERALLY BE LESS THAN 10KT AT BOTH TERMINALS WITH FRONT JUST
NORTHEAST...HOWEVER AS THE FRONT MOVES SOUTH TONIGHT WINDS WILL
INCREASE OUT OF THE NORTHEAST WITH GUSTS TO 20KT POSSIBLE THROUGH
SUN MORNING.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...DR
SHORT TERM...BULLER
LONG TERM...MK
AVIATION...DR
AREA FORECAST DISCUSSION
NWS WICHITA KS
1142 AM CDT SAT AUG 31 2013
.UPDATE...
ISSUED AT 1141 AM CDT SAT AUG 31 2013
OUTFLOW BOUNDARY FROM OVERNIGHT CONVECTION IN NEB PUSHED ACROSS MOST
OF THE FORECAST AREA THIS MORNING...CURRENTLY WASHING OUT ALONG
HIGHWAY 54. CLOUD DEBRIS AND SOME HIGHER SFC DEWPOINTS PUSHED ACROSS
NE SECTIONS OF THE FORECAST AREA EARLY TODAY....WHICH HAD LED TO
SOME HIGHER SBCAPE VALUES ALONG OR JUST TO THE NORTH OF THIS REMNANT
BOUNDARY. NOT ALOT OF CONVERGENCE NOTED ALONG THIS BOUNDARY...SO
THINK CHANCES OF AN ISOLATED STORM DEVELOPING IN THIS UNSTABLE AIR
ARE SLIM. LATEST HIGH RES HRRR REFLECTIVITY MODEL SHOWS AN ISOLATED
STORM TRYING TO DEVELOP NEAR KEMP LATE THIS AFTERNOON. BUT THINK
THIS CHANCE IS TOO REMOTE FOR NOW TO MENTION IN THE GRIDS/ZONES.
THE MAIN CONCERN WILL BE THE HIGHER SFC DEWPOINTS STILL LOCATED
ACROSS CEN KS...ALONG I-70...WITH SOME CONCERN THAT THIS HIGHER
DEWPOINT AIR MAY REMAIN IN THE UPPER 60S THIS AFTERNOON. WITH
CLOUDS CLEARING OUT...THINK THAT SFC TEMPS WILL WARM TO NEAR THE
CENTURY MARK THIS AFTERNOON IN THIS AREA. SO WITH UPPER 60S
DWPTS...THIS GIVES HEAT INDEX VALUES IN THE 104-108 RANGE. SO THINK
THIS AREA MAY ALSO REACH DANGEROUS HEAT INDICE VALUE THAT WOULD
WARRANT AN EXPANSION OF THE HEAT ADVISORY ALONG I-70. ALSO THINK
THAT CURRENT HEAT ADVISORY OVER SE KS LOOKS FINE AS WELL...GIVEN SFC
DEWPOINTS WILL STAY HIGH IN THIS AREA AS WELL.
KETCHAM
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 300 AM CDT SAT AUG 31 2013
CONVECTION CONTINUES EARLY THIS MORNING FROM NORTHWEST KS TO SOUTH-
CENTRAL NEBRASKA ALONG AND BEHIND AN OUTFLOW BOUNDARY. WEAK
SOUTH-SOUTHWESTERLY WIND AT 850 MB OVERTOP OF THE OUTFLOW BOUNDARY
MAY SUSTAIN THIS ACTIVITY INTO EARLY THIS MORNING. THINK MOST OF IT
WILL STAY JUST NORTH/NORTHWEST OF OUR AREA...BUT WILL INCLUDE A
SLIGHT CHANCE POP BY RUSSELL/GREAT BEND/LINCOLN. CONVECTIVE DEBRIS
CLOUDINESS WILL LIKELY MOVE SOUTHEAST INTO CENTRAL KS THIS MORNING.
IF IT THINS OUT...THICKNESSES SUGGEST SIMILAR HIGHS TO YESTERDAY
AFTERNOON SO HAVE MAINTAINED FORECAST HIGHS OF 99-103. WITH VERY
LIGHT SOUTH WINDS...SOUTHEAST KS WILL PROBABLY BE ABLE TO MAINTAIN
DEWPOINTS AROUND 70 DEGREES INTO THIS AFTERNOON. THIS WILL PUT THEM
INTO HEAT ADVISORY CRITERIA WITH HEAT INDICES REACHING 104-107.
PLANNING A HEAT ADVISORY FROM 17Z-01Z THERE.
A SHORTWAVE TROUGH PRESENTLY OVER ALBERTA/SASKATCHEWAN WILL AMPLIFY
AS IT TRACKS EAST-SOUTHEASTWARD TO THE WESTERN GREAT LAKES BY SUNDAY
AFTERNOON. THE ASSOCIATED COLD FRONT IS STILL SLATED TO MOVE
SOUTHWARD THROUGH OUR AREA VERY LATE TONIGHT THROUGH SUNDAY.
LARGE-SCALE FORCING IS ON THE WEAK SIDE...ALTHOUGH A DECENT
PRECIPITABLE WATER AXIS (AROUND 1.5 INCHES) WILL ACCOMPANY THE
FRONTAL PASSAGE. WIDELY SEPARATED SHOWERS/STORMS WILL BE POSSIBLE
WITH THE FRONT MOVING THROUGH...ALTHOUGH NOT EXPECTING A
WIDESPREAD SOAKING RAIN EVENT. PLACES LUCKY ENOUGH TO RECEIVE RAIN
WILL PROBABLY GET 0.25 INCH OR LESS. COOLER AIR WILL SPREAD IN
BEHIND THE FRONT...FIRST FELT IN CENTRAL KS SUNDAY...AND AREA-WIDE
SUNDAY NIGHT INTO MONDAY.
JMC
.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 300 AM CDT SAT AUG 31 2013
THE RESILIENT UPPER HIGH CENTER WILL RE-STRENGTHEN OVER THE
CENTRAL ROCKIES/HIGH PLAINS TOWARD MID-LATE WEEK WITH LEE TROUGH
DEVELOPMENT IN THE LOW-LEVELS. TEMPERATURES ARE EXPECTED TO WARM
TO ABOUT 5-9 DEGREES ABOVE NORMAL BY THE END OF THE WEEK. RECENT
RUNS OF THE ECMWF HAVE COME AROUND TOWARD THE GFS WITH THIS
SCENARIO...INCREASING FORECAST CONFIDENCE. UNFORTUNATELY...RAIN
CHANCES LOOK NIL.
JMC
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 633 AM CDT SAT AUG 31 2013
VFR CONDITIONS EXPECTED TO PREVAIL. AN OUTFLOW BOUNDARY/GRAVITY
WAVE IS PROPAGATING ACROSS SOUTH CENTRAL KANSAS THIS MORNING,
TURNING WINDS AROUND TO THE NORTH...BRIEFLY GUSTY BEFORE
WEAKENING. THE HRRR...WHILE THE TIMING IS OFF HAS THE BEST HANDLE
ON THIS AND TRENDED THE FORECAST WINDS BY USING IT AS A GUIDELINE
FOR EVOLUTION OF THE WIND FIELD TODAY. EXPECTING THE WAVE TO WASH
OUT AND THE WINDS TO BE COME EASTERLY...SOUTHEASTERLY AND
EVENTUALLY SOUTHERLY BY AFTERNOON. HOWEVER...NOT EXPECTING MUCH
CHANGE AFTER THIS POINT...LIGHT SOUTHERLY WINDS WITH SOME
SCATTERED TO BROKEN MID-HIGH CLOUDS.
BILLINGS
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 102 73 93 66 / 10 20 20 10
HUTCHINSON 102 72 92 65 / 10 20 20 10
NEWTON 101 73 92 65 / 10 20 20 10
ELDORADO 101 74 93 66 / 10 20 20 10
WINFIELD-KWLD 101 73 96 68 / 10 10 20 10
RUSSELL 101 70 89 62 / 20 30 20 10
GREAT BEND 102 70 89 63 / 10 20 20 10
SALINA 101 72 90 63 / 10 30 20 10
MCPHERSON 101 72 91 64 / 10 20 20 10
COFFEYVILLE 99 73 96 68 / 0 10 20 10
CHANUTE 99 72 93 64 / 10 10 30 10
IOLA 99 74 93 64 / 10 20 30 10
PARSONS-KPPF 99 73 95 66 / 0 10 30 10
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR KSZ033-048-049-
051>053-069>072-094>096-098>100.
&&
$$
AREA FORECAST DISCUSSION
NWS JACKSON KY
540 PM EDT SAT AUG 31 2013
.MESOSCALE DISCUSSION...
ISSUED AT 540 PM EDT SAT AUG 31 2013
IN GENERAL...THE LINE ENTERING EASTERN KENTUCKY HAS BEEN WEAKENING.
JUST BEFORE THE LINE MOVED INTO THE AREA...AN OUTFLOW BOUNDARY MOVED
ACROSS THE AREA FROM NE TO SW AND AND HELPED TO DESTROY SOME OF THE
FAVORABLE STORM ENVIRONMENT. SOME TEMPERATURES STILL TO THE EAST OF
THE LINE ARE PRETTY WARM...SO DECIDED TO ISSUE A SPECIAL WEATHER
STATEMENT FOR THE LINE AS IT MAY STRENGTHEN AS THEY FIND MORE
FAVORABLE AIR. THE WARMER TEMPERATURES ARE GENERALLY WEST OF A LINE
FROM ROCKCASTLE TO BELL COUNTIES.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 420 PM EDT SAT AUG 31 2013
THE MAIN CLUSTER OF CONVECTION CONTINUES TO SLOWLY MOVE SOUTH ACROSS
PORTIONS OF EASTERN KENTUCKY. THIS CLUSTER WAS MORE ORGANIZED WHEN IT
WAS MOVING THROUGH THE I-64 CORRIDOR AND HAS SINCE BECOME MORE
CELLULAR. HEAVY RAINFALL IS THE MAIN CONCERN WITH THESE...HOWEVER
GIVEN THAT THE OUTFLOW HAS ALREADY SURGED SOUTH AWAY FROM THE
ACTIVITY...WOULD EXPECT THE STORMS TO CONTINUE TO GRADUALLY WEAKEN
WITH TIME.
ANOTHER MORE ORGANIZED AREA OF CONVECTION IS ALIGNED ACROSS NORTH
CENTRAL KENTUCKY ASSOCIATED MORE WITH A SUBTLE OUTFLOW BOUNDARY FROM
CONVECTION THAT HAD OCCURRED LAST NIGHT. THE LATEST HRRR HAS BEEN
KEEPING THIS CONVECTION MORE CONFINED TO SOUTHERN KENTUCKY WITH
TIME...ALTHOUGH IT IS NOT MAKING MUCH OF A TURN YET. CVG DOWN TO LEX
HAS RECOVERED WELL FROM EARLIER CLOUD COVER...HOWEVER THE AIR CLOSER
TOWARDS OUR BLUEGRASS COUNTIES IS NOT AS UNSTABLE. THE BEST
INSTABILITY REMAINS ACROSS OUR SOUTHWEST COUNTIES...WITH
TEMPERATURES IN THE UPPER 80S AND DEW POINTS IN THE UPPER 60S TO
LOWER 70S. THERE IS ALSO AN OUTFLOW BOUNDARY THAT APPEARS TO HAVE
STALLED FROM ALONG A MOUNT VERNON TO HARLAN LINE...WHICH MAY SERVE AS
A FOCUS FOR DEVELOPMENT THROUGH EARLY THIS EVENING. AS SUCH...WILL
HAVE SOME HIGHER POPS IN THE SOUTHWEST...WITH LOWER POPS IN THE
NORTHEAST WHERE CONVECTION HAS WORKED OVER THE AIR MASS.
WEAK SHORT WAVE TROUGHS WILL CONTINUE TO TRAVERSE THE OHIO VALLEY
THROUGH THE REST OF THE SHORT TERM...HOWEVER AS PREVIOUSLY STATED IN
EARLIER DISCUSSIONS...THE MESOSCALE WILL CONTINUE TO DRIVE THE
WEATHER. AS SUCH...HAVE STUCK WITH CONTINUITY...AND ALLOWED FOR A
GENERAL DIURNAL INCREASE IN CONVECTION THROUGH THE DAY ON SUNDAY...
HOWEVER COULD NOT DROP OFF THE POPS TOO MUCH AT NIGHT.
HEAVY RAINFALL WILL BE THE MAIN HAZARD THROUGH THE SHORT TERM...AND
WILL MENTION THE POTENTIAL FOR ISOLATED FLASH FLOODING NOW THAT SOME
LOCATIONS HAVE BEEN PRIMED. A FEW STRONGER STORMS COULD ALSO PRODUCE
SOME STRONG WIND GUSTS AND POSSIBLY SMALL HAIL AS WELL.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 437 PM EDT SAT AUG 31 2013
THE PREDOMINANT PATTERN DURING THE PERIOD WILL FEATURE A LARGE UPPER
LEVEL RIDGE CENTERED NEAR COLORADO...AND A BROAD TROUGH OVER THE
EASTERN CONUS WITH IMPULSES PASSING THROUGH IT. THIS RESULTS IN
GENERAL NW FLOW ALOFT FOR OUR AREA...WITH THE UPPER LEVEL IMPULSES
BRINGING SURFACE COLD FRONTS SOUTH AND SOUTHEAST. ONE OF THESE
IMPULSES AND FRONTS IS SLATED TO AFFECT US AT THE START OF THE
PERIOD...WITH FROPA ON MONDAY NIGHT. WITH GENERAL MODEL AGREEMENT ON
THIS...AND THE FRONT APPROACHING AT PEAK HEATING...HAVE USED LIKELY
POPS DURING THE DAY. WITH THE COLD FRONT EXPECTED TO PASS ON MONDAY
EVENING AND A LOSS OF HEATING...POPS DROP OFF FOR THE NIGHT. SURFACE
HIGH PRESSURE THEN BUILDS IN WITH A DRIER AIR MASS FOR TUESDAY.
ANOTHER COLD FRONT DROPS IN ON THURSDAY...BUT POOR MOISTURE RETURN
IS ANTICIPATED BEFORE FROPA...AND WILL GO WITH A DRY FORECAST.
ANOTHER COLD FRONT APPROACHES ON SATURDAY...BUT MODELS ARE NOT
CONSISTENT ON ITS STRENGTH OR TIMING. NONE OF THE MODELS SEEM TO
SHOW GOOD MOISTURE RETURN AT THIS POINT...AND HAVE LEFT THE FORECAST
DRY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 250 PM EDT SAT AUG 31 2013
ORGANIZED CONVECTION HAS STEERED CLEAR OF LOZ AND SME THUS FAR...SO
WILL CONTINUE TO MENTION A VCTS ONLY FOR THESE LOCATIONS. A CLUSTER
OF SHOWERS AND THUNDERSTORMS MAY SNEAK INTO JKL IN THE NEXT 30
MINUTES TO AN HOUR IF THEY CAN HOLD TOGETHER. OTHERWISE...EXPECT SOME
FOG TO FORM ONCE AGAIN TONIGHT...WITH A LINGERING THREAT OF AT LEAST
SCATTERED CONVECTION CARRYING THROUGH SUNDAY. SINCE JKL TOOK A DIRECT
HIT FROM EARLIER STORMS...HAVE GONE FOR IFR FOG CONDITIONS THERE. THE
FOG WILL MIX OUT BY AROUND 13Z.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE...JJ
SHORT TERM...GEOGERIAN
LONG TERM...HAL
AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS JACKSON KY
437 PM EDT SAT AUG 31 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 420 PM EDT SAT AUG 31 2013
THE MAIN CLUSTER OF CONVECTION CONTINUES TO SLOWLY MOVE SOUTH ACROSS
PORTIONS OF EASTERN KENTUCKY. THIS CLUSTER WAS MORE ORGANIZED WHEN IT
WAS MOVING THROUGH THE I-64 CORRIDOR AND HAS SINCE BECOME MORE
CELLULAR. HEAVY RAINFALL IS THE MAIN CONCERN WITH THESE...HOWEVER
GIVEN THAT THE OUTFLOW HAS ALREADY SURGED SOUTH AWAY FROM THE
ACTIVITY...WOULD EXPECT THE STORMS TO CONTINUE TO GRADUALLY WEAKEN
WITH TIME.
ANOTHER MORE ORGANIZED AREA OF CONVECTION IS ALIGNED ACROSS NORTH
CENTRAL KENTUCKY ASSOCIATED MORE WITH A SUBTLE OUTFLOW BOUNDARY FROM
CONVECTION THAT HAD OCCURRED LAST NIGHT. THE LATEST HRRR HAS BEEN
KEEPING THIS CONVECTION MORE CONFINED TO SOUTHERN KENTUCKY WITH
TIME...ALTHOUGH IT IS NOT MAKING MUCH OF A TURN YET. CVG DOWN TO LEX
HAS RECOVERED WELL FROM EARLIER CLOUD COVER...HOWEVER THE AIR CLOSER
TOWARDS OUR BLUEGRASS COUNTIES IS NOT AS UNSTABLE. THE BEST
INSTABILITY REMAINS ACROSS OUR SOUTHWEST COUNTIES...WITH
TEMPERATURES IN THE UPPER 80S AND DEW POINTS IN THE UPPER 60S TO
LOWER 70S. THERE IS ALSO AN OUTFLOW BOUNDARY THAT APPEARS TO HAVE
STALLED FROM ALONG A MOUNT VERNON TO HARLAN LINE...WHICH MAY SERVE AS
A FOCUS FOR DEVELOPMENT THROUGH EARLY THIS EVENING. AS SUCH...WILL
HAVE SOME HIGHER POPS IN THE SOUTHWEST...WITH LOWER POPS IN THE
NORTHEAST WHERE CONVECTION HAS WORKED OVER THE AIR MASS.
WEAK SHORT WAVE TROUGHS WILL CONTINUE TO TRAVERSE THE OHIO VALLEY
THROUGH THE REST OF THE SHORT TERM...HOWEVER AS PREVIOUSLY STATED IN
EARLIER DISCUSSIONS...THE MESOSCALE WILL CONTINUE TO DRIVE THE
WEATHER. AS SUCH...HAVE STUCK WITH CONTINUITY...AND ALLOWED FOR A
GENERAL DIURNAL INCREASE IN CONVECTION THROUGH THE DAY ON SUNDAY...
HOWEVER COULD NOT DROP OFF THE POPS TOO MUCH AT NIGHT.
HEAVY RAINFALL WILL BE THE MAIN HAZARD THROUGH THE SHORT TERM...AND
WILL MENTION THE POTENTIAL FOR ISOLATED FLASH FLOODING NOW THAT SOME
LOCATIONS HAVE BEEN PRIMED. A FEW STRONGER STORMS COULD ALSO PRODUCE
SOME STRONG WIND GUSTS AND POSSIBLY SMALL HAIL AS WELL.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 437 PM EDT SAT AUG 31 2013
THE PREDOMINANT PATTERN DURING THE PERIOD WILL FEATURE A LARGE UPPER
LEVEL RIDGE CENTERED NEAR COLORADO...AND A BROAD TROUGH OVER THE
EASTERN CONUS WITH IMPULSES PASSING THROUGH IT. THIS RESULTS IN
GENERAL NW FLOW ALOFT FOR OUR AREA...WITH THE UPPER LEVEL IMPULSES
BRINGING SURFACE COLD FRONTS SOUTH AND SOUTHEAST. ONE OF THESE
IMPULSES AND FRONTS IS SLATED TO AFFECT US AT THE START OF THE
PERIOD...WITH FROPA ON MONDAY NIGHT. WITH GENERAL MODEL AGREEMENT ON
THIS...AND THE FRONT APPROACHING AT PEAK HEATING...HAVE USED LIKELY
POPS DURING THE DAY. WITH THE COLD FRONT EXPECTED TO PASS ON MONDAY
EVENING AND A LOSS OF HEATING...POPS DROP OFF FOR THE NIGHT. SURFACE
HIGH PRESSURE THEN BUILDS IN WITH A DRIER AIR MASS FOR TUESDAY.
ANOTHER COLD FRONT DROPS IN ON THURSDAY...BUT POOR MOISTURE RETURN
IS ANTICIPATED BEFORE FROPA...AND WILL GO WITH A DRY FORECAST.
ANOTHER COLD FRONT APPROACHES ON SATURDAY...BUT MODELS ARE NOT
CONSISTENT ON ITS STRENGTH OR TIMING. NONE OF THE MODELS SEEM TO
SHOW GOOD MOISTURE RETURN AT THIS POINT...AND HAVE LEFT THE FORECAST
DRY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 250 PM EDT SAT AUG 31 2013
ORGANIZED CONVECTION HAS STEERED CLEAR OF LOZ AND SME THUS FAR...SO
WILL CONTINUE TO MENTION A VCTS ONLY FOR THESE LOCATIONS. A CLUSTER
OF SHOWERS AND THUNDERSTORMS MAY SNEAK INTO JKL IN THE NEXT 30
MINUTES TO AN HOUR IF THEY CAN HOLD TOGETHER. OTHERWISE...EXPECT SOME
FOG TO FORM ONCE AGAIN TONIGHT...WITH A LINGERING THREAT OF AT LEAST
SCATTERED CONVECTION CARRYING THROUGH SUNDAY. SINCE JKL TOOK A DIRECT
HIT FROM EARLIER STORMS...HAVE GONE FOR IFR FOG CONDITIONS THERE. THE
FOG WILL MIX OUT BY AROUND 13Z.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GEOGERIAN
LONG TERM...HAL
AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS JACKSON KY
420 PM EDT SAT AUG 31 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 420 PM EDT SAT AUG 31 2013
THE MAIN CLUSTER OF CONVECTION CONTINUES TO SLOWLY MOVE SOUTH ACROSS
PORTIONS OF EASTERN KENTUCKY. THIS CLUSTER WAS MORE ORGANIZED WHEN IT
WAS MOVING THROUGH THE I-64 CORRIDOR AND HAS SINCE BECOME MORE
CELLULAR. HEAVY RAINFALL IS THE MAIN CONCERN WITH THESE...HOWEVER
GIVEN THAT THE OUTFLOW HAS ALREADY SURGED SOUTH AWAY FROM THE
ACTIVITY...WOULD EXPECT THE STORMS TO CONTINUE TO GRADUALLY WEAKEN
WITH TIME.
ANOTHER MORE ORGANIZED AREA OF CONVECTION IS ALIGNED ACROSS NORTH
CENTRAL KENTUCKY ASSOCIATED MORE WITH A SUBTLE OUTFLOW BOUNDARY FROM
CONVECTION THAT HAD OCCURRED LAST NIGHT. THE LATEST HRRR HAS BEEN
KEEPING THIS CONVECTION MORE CONFINED TO SOUTHERN KENTUCKY WITH
TIME...ALTHOUGH IT IS NOT MAKING MUCH OF A TURN YET. CVG DOWN TO LEX
HAS RECOVERED WELL FROM EARLIER CLOUD COVER...HOWEVER THE AIR CLOSER
TOWARDS OUR BLUEGRASS COUNTIES IS NOT AS UNSTABLE. THE BEST
INSTABILITY REMAINS ACROSS OUR SOUTHWEST COUNTIES...WITH
TEMPERATURES IN THE UPPER 80S AND DEW POINTS IN THE UPPER 60S TO
LOWER 70S. THERE IS ALSO AN OUTFLOW BOUNDARY THAT APPEARS TO HAVE
STALLED FROM ALONG A MOUNT VERNON TO HARLAN LINE...WHICH MAY SERVE AS
A FOCUS FOR DEVELOPMENT THROUGH EARLY THIS EVENING. AS SUCH...WILL
HAVE SOME HIGHER POPS IN THE SOUTHWEST...WITH LOWER POPS IN THE
NORTHEAST WHERE CONVECTION HAS WORKED OVER THE AIR MASS.
WEAK SHORT WAVE TROUGHS WILL CONTINUE TO TRAVERSE THE OHIO VALLEY
THROUGH THE REST OF THE SHORT TERM...HOWEVER AS PREVIOUSLY STATED IN
EARLIER DISCUSSIONS...THE MESOSCALE WILL CONTINUE TO DRIVE THE
WEATHER. AS SUCH...HAVE STUCK WITH CONTINUITY...AND ALLOWED FOR A
GENERAL DIURNAL INCREASE IN CONVECTION THROUGH THE DAY ON SUNDAY...
HOWEVER COULD NOT DROP OFF THE POPS TOO MUCH AT NIGHT.
HEAVY RAINFALL WILL BE THE MAIN HAZARD THROUGH THE SHORT TERM...AND
WILL MENTION THE POTENTIAL FOR ISOLATED FLASH FLOODING NOW THAT SOME
LOCATIONS HAVE BEEN PRIMED. A FEW STRONGER STORMS COULD ALSO PRODUCE
SOME STRONG WIND GUSTS AND POSSIBLY SMALL HAIL AS WELL.
.LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 300 AM EDT SAT AUG 31 2013
A STRENGTHENING UPPER LEVEL SHORTWAVE OVER THE UPPER GREAT LAKES
WILL BE THE MAIN CONCERN TO START OUT THE FORECAST PERIOD. WHILE
HIGH PRESSURE CONTINUES TO LIE OVER THE SE...THIS SHORTWAVE OVER THE
GREAT LAKES WILL INTENSIFY AND MOVE EASTWARD SUNDAY NIGHT AND
THROUGH THE DAY MONDAY. THIS WILL PLACE UPPER LEVEL TROUGHING AND AN
ASSOCIATED SURFACE FRONTAL BOUNDARY ACROSS THE OHIO VALLEY. AHEAD OF
THIS COLD FRONTAL PASSAGE...ALREADY MOIST AIR WILL BE IN PLACE. SO
WITH CONTINUED HOT AND HUMID AIR FLOWING FROM THE SOUTH...EXPECT THE
CHANCES OF SHOWERS AND THUNDERSTORMS TO CONTINUE THROUGH SUNDAY
NIGHT. THE ACTUAL COLD FRONT IS PROGGED TO TRAVERSE EASTERN KY
MONDAY AFTERNOON. THIS COUPLED WITH DIURNAL HEATING WILL MAKE FOR
THE BEST CHANCES OF CONVECTIVE ACTIVITY. THE FACT PW VALUES ARE
STILL FORECASTED TO BE ABOVE NORMAL...AND STORM MOTION SLOW...SOME
HEAVY DOWNPOURS WILL NOT BE OUT OF THE QUESTION MONDAY AFTERNOON.
ONCE THE COLD FRONT PASSES THROUGH EASTERN KY...DRY AIR WILL BEGIN
WORKING IN ALOFT AND EVENTUALLY MAKE ITS WAY DOWN TO THE
SURFACE...CUTTING OFF ALL PRECIP CHANCES ACROSS EASTERN KY BY
TUESDAY MORNING. THIS DRY AIR WILL BE ASSOCIATED WITH A HIGH
PRESSURE CENTERED OVER THE UPPER MISSISSIPPI VALLEY TUESDAY. IN
TERMS OF WEATHER IMPACTS...THIS WILL PROVIDE A MUCH NEEDED BREAK
FROM NOT ONLY THE PRECIPITATION CHANCES...BUT THE HOT AND HUMID
WEATHER THAT WE HAVE BEEN EXPERIENCING. COLDER AND DRIER CONTINENTAL
AIR WILL REST OVER THE OHIO RIVER VALLEY...WITH HIGH TEMPS ONLY
EXPECTED AROUND 80 DEGREES FOR TUESDAY THROUGH THURSDAY. WITH LOW
DEW POINTS IN PLACE...AND MOSTLY CLEAR SKIES...THE DIURNAL SHIFT
WILL BE QUITE LARGE...WITH OVERNIGHT LOWS DIPPING DOWN INTO THE
UPPER 50S ACROSS PORTIONS OF THE REGION.
FOR THE REMAINDER OF THE FORECAST PERIOD...A FEW SUBTLE SHORTWAVES
WILL TRY TO MAKE THEIR WAY TOWARDS THE OHIO RIVER VALLEY...NAMELY
FRIDAY INTO SATURDAY. HOWEVER WITH SUCH STRONG SUBSIDENCE IN
PLACE...LATEST MODEL RUNS ARE SHOWING ANY PRECIP CHANCES DYING OFF
BEFORE THEY REACH EASTERN KY. OVERALL IT LOOKS TO BE A GREAT SECOND
HALF OF THE WORKWEEK AND START TO THE WEEKEND.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 250 PM EDT SAT AUG 31 2013
ORGANIZED CONVECTION HAS STEERED CLEAR OF LOZ AND SME THUS FAR...SO
WILL CONTINUE TO MENTION A VCTS ONLY FOR THESE LOCATIONS. A CLUSTER
OF SHOWERS AND THUNDERSTORMS MAY SNEAK INTO JKL IN THE NEXT 30
MINUTES TO AN HOUR IF THEY CAN HOLD TOGETHER. OTHERWISE...EXPECT SOME
FOG TO FORM ONCE AGAIN TONIGHT...WITH A LINGERING THREAT OF AT LEAST
SCATTERED CONVECTION CARRYING THROUGH SUNDAY. SINCE JKL TOOK A DIRECT
HIT FROM EARLIER STORMS...HAVE GONE FOR IFR FOG CONDITIONS THERE. THE
FOG WILL MIX OUT BY AROUND 13Z.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GEOGERIAN
LONG TERM...JMW
AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
321 PM EDT SAT AUG 31 2013
.SYNOPSIS...
WARM AND HUMID CONDITIONS WITH PERIODIC SHOWERS AND THUNDERSTORMS
WILL PREVAIL THROUGH THE LABOR DAY WEEKEND.
&&
.NEAR TERM /THROUGH SUNDAY/...
AS OF MID-AFTERNOON...CONVECTION HAS GENERALLY BEEN A BUST SO
FAR. EXCEPT FOR A FEW ISOLATED SHOWERS ALONG THE INTERSTATE 80
CORRIDOR...ALL LOCATIONS HAVE REMAINED DRY SINCE MID-MORNING.
CONSIDERING THE MAIN UPPER LEVEL SHORTWAVE HAS ALREADY PUSHED EAST
OF THE REGION...DO NOT REALLY SEE ANYTHING THAT WILL PROVIDE MUCH
OF A FORCING MECHANISM UNTIL THE NEXT SHORTWAVE AFFECTING THE AREA
LATE TONIGHT INTO SUNDAY. AS A RESULT...HAVE CUT WAY BACK ON POPS
EARLY...RAMPING THEM UP AGAIN BY LATE TONIGHT. HOWEVER...CANNOT
COMPLETELY DISCOUNT THE POSSIBILITY OF A LINE OF SHOWERS/STORMS
DEVELOPING FROM NORTHEAST TO SOUTHWEST ACROSS THE REGION WHICH
SEVERAL RUNS OF THE HRRR HAS BEEN INSISTENT WILL DEVELOP JUST
BEFORE SUNSET. ANOTHER STICKY NIGHT CAN BE EXPECTED WITH LOWS ONLY
DROPPING TO AROUND 70.
A BIT OF DISAGREEMENT BETWEEN MODELS FOR TOMORROWS FORECAST. ALL OF
THE SYNOPTIC MODELS BRING A DECENT SHORTWAVE FROM EASTERN OHIO IN
THE MORNING TO CENTRAL PENNSYLVANIA BY THE AFTERNOON...TRIGGERING
WIDESPREAD PRECIPITATION. ON THE OTHER HAND...ALL OF THE HIGH
RESOLUTION MODELS SHOW MUCH LESS COVERAGE WITH PRECIP. SEEING AS THE
SHORTWAVE IN QUESTION IS CURRENTLY OVER CHICAGO PRODUCING SHOWERS
AND THUNDERSTORMS...WILL STICK WITH THE SYNOPTIC MODEL SOLUTIONS. A
SCENARIO SIMILAR TO TODAY COULD OCCUR...WITH THE HIGHEST POPS
POTENTIALLY ARRIVING IN THE MORNING ACROSS WESTERN PORTIONS OF THE
AREA ALONG WITH THE SHORTWAVE AND REMNANT THUNDERSTORMS.
HOWEVER...WILL PUT IN LIKELY POPS ALONG THE RIDGES DURING THE EARLY
AFTERNOON WHILE THE SHORTWAVE IS PASSING THROUGH.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY/...
THERE SHOULD BE A BRIEF LULL IN PRECIPITATION SUNDAY EVENING WITH
THE UPPER LEVEL SHORTWAVE TO THE EAST AND THE NEXT COLD FRONT OUT
TO THE WEST. RAIN SHOULD BEGIN TO OVERTAKE THE EASTERN COUNTIES
VERY EARLY MONDAY...AND THE FRONT WILL BE HUGGING THE RIDGES BY
MONDAY EVENING. INSTABILITY AND WIND SHEAR SHOULD BE HIGH ENOUGH
THAT A FEW STRONGER THUNDERSTORMS ARE POSSIBLE...BUT OVERALL
SEVERE THREAT APPEARS TO BE LOW.TEMPERATURES SUNDAY NIGHT AND
MONDAY SHOULD BE SIMILAR TO THOSE THROUGH THE EARLIER PORTIONS OF
THE WEEKEND.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
THE CDFNT IS FORECAST TO EXIT THE RGN MON NGT AND END THE SHWR
CHCS. BLDG HIGH PRES SHOULD THEN MAINTAIN DRY WEATHER UNTIL
PASSAGE OF ANOTHER WEAK CDFNT ON THU. LTD MSTR IS PROGGED WITH
THAT FNT...SO ONLY SLGT CHC POPS WERE INCLUDED ATTM. UNDR ERN
CONUS TROFG ALOFT...SUB AVG TEMPS ARE EXPD INTO SATURDAY.
&&
.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
GENERAL VFR EXPECTED IS FORECAST TODAY ALTHOUGH SOME SHWRS AND
TSTMS MAY MAR UPR OH VALLEY WEA LTR THIS AFTN AND THIS EVE. THE
BTR CHC OF THIS OCCURRENCE LKS TO BE OVR AREAS E OF PIT AS PER
POSITIONING OF A SLOW-MOVG MID LVL TROF. TAFS HAVE THUS BEEN
AMENDED TO INCLUDED TSTM MENTION AT ONLY AT MGW FOR NOW.
OTHERWISE...A MORE SIGNIFICANT SHRTWV IS MDL-INDICATED FOR A
SUNDAY PASSAGE. GIVEN MSTR SUPPLY AND INCRSG ASCENT...HAVE
FORECAST DEGRADED CIGS/MVFR CONDITIONS FOR THE PREDAWN WITH IFR
AT FKL AND DUJ. MORE WIDESPREAD SHWRS AND CONTD RESTRICTIONS ARE
ANTICIPATED FOR SUNDAY.
.OUTLOOK.../SUNDAY THROUGH THURSDAY/...
A DECISIVE CDFNT PASSAGE IS STILL SLATED FOR MONDAY. RESTRICTIONS
MAY THUS BE EXPECTED UNTIL HIGH PRES BUILDS FOR TUESDAY THROUGH
THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
143 PM EDT SAT AUG 31 2013
.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO DRIFT FARTHER OFFSHORE TODAY AS A
WEAK TROUGH DEVELOPS OVER THE PIEDMONT OF VIRGINIA. A COLD FRONT
WILL APPROACH THE REGION FROM THE WEST ON MONDAY...AND WILL PUSH
ACROSS THE AREA TUESDAY AND TUESDAY NIGHT. HIGH PRESSURE WILL BUILD
INTO THE MID ATLANTIC STATES ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE LATEST WX ANALYSIS SHOWS ~1016 MB SFC HIGH PRESSURE SITUATED
WELL OFF THE MID ATLC/SE COAST...WITH PRESSURE FALLS INDICATING A
DEVELOPING LEE TROUGH ALONG/WEST OF THE I-95 CORRIDOR. CURRENT
WV SATELLITE AND REGIONAL RADAR REVEALS A RATHER SMALL BUT SHARP
SHORTWAVE DIVING SE THROUGH OHIO WITH AN ASSOCIATED MCS SPREADING
THROUGH SE OHIO/ERN KY. MODELS TO A VARYING DEGREE BEGIN TO SPREAD
INCREASING MOISTURE INTO WRN PORTIONS OF THE CWA AFTER 18Z THIS
AFTN. WILL CONTINUE TO WATCH THE CURRENT ACTIVITY CLOSELY TO SEE
IF IT HOLDS TOGETHER UPON REACHING THE APPALACHIANS...CURRENT
THINKING IS THAT IT PROBABLY WILL NOT ALTHOUGH THE HRRR ACTUALLY
SPREADS SOME SCATTERED SHOWERS INTO WRN PORTIONS OF THE CWA BY 18Z
(BUT IT DEVELOPS THIS FROM AN AREA OF PRECIP OVER SOUTH CENTRAL VA
AND NCENTRAL NC WHICH THUS FAR HAS NOT OCCURRED).
OVERALL...FORECAST HAS BEEN CHANGED VERY LITTLE FOR THE AFTN...FAVORING
AREAS WEST OF I-95 FOR LOW CHC POPS BY LATE AFTN/EARLY EVENING WITH
20% OR LOWER POPS FARTHER EAST WHERE INSTABILITY PARAMETERS ARE LOWER
(ML CAPES 1000 J/KG OR LESS). GFS/NAM DO SHOW SOME DECENT MID
LEVEL LAPSE RATES > 6.5 C/KM THIS AFTN/EVENING BUT DEEP LAYER
BULK SHEAR WILL AVG 20-25 KT NORTH TO < 20 KT SOUTH SO ORGANIZED
STRONG STORMS ARE UNLIKELY ESPECIALLY OVER SOUTHERN 1/2 OF THE CWA.
PRECIPITABLE WATER VALUES RISE TO 1.50 TO 1.80" BY AFTN SO MAIN
ISSUE WOULD BE LOCALLY HEAVY RAIN. FOR TEMPS, EXPECT HIGHS TODAY
GENERALLY IN THE UPPER 80S TO AROUND 90...LOCALLY MID 80S ON THE
IMMEDIATE COAST.
CONSIDERING RATHER ANEMIC DYNAMICS/FORCING, RAIN CHCS END QUICKLY
TONIGHT. EXPECT A PARTLY CLOUDY AND DRY NIGHT ACROSS THE LOCAL
AREA WITH EARLY MORNING LOWS IN THE UPR 60S TO LOW 70S.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
RAIN CHCS INCREMENTALLY RAMP UPWARDS FOR THE LATTER HALF OF THE
HOLIDAY WEEKEND AS LONGWAVE TROUGH CONTINUES TO AMPLIFY/DEEPEN
OVER THE MID-ATLANTIC REGION. MOISTURE WL GRADUALLY INCREASE
THROUGH THIS PERIOD GIVEN SW FLOW AHEAD OF THE SLOW MOVING COLD
FRONT THAT IS PROGGED TO MOVE ACROSS THE LOCAL AREA BY TUESDAY.
HIGH END CHC (40%) POPS FOR SHRAS/TSTMS MOST AREAS BOTH DAYS
(LOWER FAR SE) AS SEVERAL ADDITIONAL SPOKES OF SHORTWAVE ENERGY
EMBEDDED WITHIN THE LARGER TROUGH ROTATE THROUGH. THREAT FOR SVR
WX APPEARS LOW ATTM GIVEN LACK OF SHEAR, THOUGH WITH PW ~2",
LOCALLY HVY RAINFALL IS ONCE AGAIN A CONCERN (OVER INLAND AREAS
SUNDAY, CLOSER TO THE COAST ON MONDAY). HIGHS SUN/MON UPR 80S TO
LOW 90S. LOWS SUN NIGHT IN THE UPR 60S TO LOW 70S.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
LARGE SCALE PATTERN DURING THE MEDIUM RANGE PERIOD CHARACTERIZED BY
LARGE MID LVL RIDGE IN THE SW U.S. AND A MID LEVEL TROUGH OVER THE
EASTERN CONUS. LATEST 12Z GFS/ECMWF NOW INTO BETTER AGREEMENT THAN
THEIR 00Z RUNS HAD BEEN WITH THE LATER PART OF NEXT WEEK. BOTH
MODELS NOW SHOW THE UPPER RIDGE EXPANDING NORTH INTO THE NORTHERN
ROCKIES BY MIDWEEK...EFFECTIVELY SENDING A REINFORCING SHOT OF COOL
AIR AND UPPER TROUGHING SE INTO THE GREAT LAKES AND NE CONUS BY
THU/FRI. FOR THE LOCAL AREA...THIS PATTERN WILL PUSH THE ACTUAL
FRONT THROUGH DURING THE DAY TUE...WITH MOISTURE AND INSTABILITY
PROFILES FAVORING HIGHEST POPS TUE AFTN OVER FAR SOUTHERN/SE VA AND
NC (30-50%) WITH SOMEWHAT DRIER AIR AND LESS COVERAGE OF STORMS
FARTHER N/W. HIGHS TUE GENLY HELD IN THE 80S DUE TO MORE CLOUD
COVER. HIGH PRESSURE BUILDS IN FROM THE WNW TUE NIGHT-WED...AND
PERSISTS OVER THE REGION INTO THU AS THE DEEP UPPER TROUGH BECOMES
ANCHORED OVER EASTERN CANADA. EXPECT COOLER AND DRIER/MORE
COMFORTABLE CONDITIONS WITH HIGHS MAINLY 80-85 AND LOWS IN THE UPPER
50S NW TO MID 60S FAR SE ON WED. FLOW BRIEFLY TURNS BACK TO THE SW
ON THU ALLOWING FOR SOMEWHAT WARMER TEMPS INTO THE MID OR POSSIBLY
UPPER 80S AHEAD OF THE NEXT FRONT. THIS FRONT LOOKS TO COME THROUGH
THU NIGHT/EARLY FRI WITH MINIMAL DYNAMICS SO WILL KEEP FORECAST DRY
WITH JUST SOME INCREASE IN CLOUDS. PARTLY TO MOSTLY SUNNY FRI W/
HIGHS IN THE UPPER 70S TO LOWER 80S.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AS OF 17Z...SCT CU COVERED THE TAF SITES EARLY SATURDAY AFTN. A
SHORT WAVE MOVING THROUGH WEST VIRGINIA AND A LEESIDE TROUGH MAY
RESULT IN SOME CONVECTION OVER WESTERN VA LATER THIS AFTN. ANY TSTMS
THAT DO FORM HAVE A RATHER A LOW PROBABILITY OF AFFECTING THE TAF
SITES AND KEPT MENTION OF PCPN OUT OF TAFS FOR NOW. CLOUD COVER AND
A STEADY S/SW WIND SHOULD INHIBIT FOG FORMATION SUNDAY MORNING.
OUTLOOK...SHOWERS AND THUNDERSTORMS HAVE A BETTER CHANCE OF
AFFECTING THE AREA SUNDAY AFTN AND NIGHT AND AGAIN ON MONDAY. DRIER
WEATHER RETURNS TOWARD MIDWEEK. NO WIDESPREAD IFR IS INDICATED AT
THIS TIME.
&&
.MARINE...
THE WATERS BECOME POSITIONED BTWN HIGH PRESSURE OFF THE MID
ATLANTIC COAST AND A LOW PRESSURE SYSTEM MOVING ACROSS THE ERN
GREAT LAKES TODAY..RESULTING IN A TIGHTENING PRESSURE GRADIENT.
SOUTH WINDS ON CHES BAY AND COASTAL WATERS NORTH OF THE VA/NC
BORDER WILL AVERAGE 10-15 KT THIS MORNING THROUGH EARLY AFTERNOON
AND THEN INCREASE TO 15-20 KT BY LATE AFTERNOON ON CHES BAY (A
SOLID 20 KT FOR COASTAL WATERS)...PERSISTING THROUGH THE OVERNIGHT
HOURS INTO SUNDAY MORNING. CURRITUCK SOUND MAY EXPERIENCE GUSTS
AROUND 20 KT LATE THIS AFTERNOON INTO EARLY EVENING...HOWEVER THE
DURATION OF THE WIND GUSTS SHOULD BE SHORT-LIVED. CONFIDENCE IS
NOT HIGH ENOUGH TO ISSUE SCA FLAGS FOR THE SOUND AND ANY GUSTY
WINDS DURING THIS TIME FRAME TODAY MAY BE COVERED WITH MARINE
WEATHER STATEMENTS INSTEAD. WILL NEED TO MONITOR. A SECONDARY SLY
SURGE IS EXPECT TO BEGIN AROUND MIDNIGHT...PUSHING GUSTS ON CHES
BAY UP TWD 25 KT. WAVES ON CHES BAY WILL AVERAGE 2-3 FT AND SEAS
WILL AVERAGE 3-4 FT. SCA FLAGS FOR CHES BAY HAVE BEEN ISSUED
BEGINNING LATE THIS AFTERNOON THROUGH 10 AM EDT SUNDAY MORNING.
MEANWHILE...A MID LEVEL TROUGH CROSSING THE REGION AND INTERACTING
WITH A LEE TROUGH WILL TRIGGER SHOWERS AND THUNDERSTORMS DURING
THIS AFTERNOON AND EVENING. A FEW STORMS MAY MOVE OVER THE BAY
NORTH OF NEW POINT COMFORT WHILE THE REST OF THE WATERS REMAIN
RAIN-FREE.
A COLD FRONT WILL APPROACH THE REGION FROM THE WEST ON SUNDAY INTO
MONDAY. THE FRONT IS EXPECTED TO MOVE INTO THE MID ATLANTIC REGION
MONDAY NIGHT AND THEN STALL ALONG THE COAST ON TUESDAY. WINDS ARE
EXPECTED TO BECOME MORE SWLY MONDAY INTO TUESDAY AND REMAIN AOB
15 KT. A COOL NW-N SURGE EITHER TUESDAY NIGHT OR EARLY WEDNESDAY MAY
RESULT IN A PERIOD OF SCA HEADLINES...ALTHOUGH TIMING ON THIS
CONTINUES TO BE UNCERTAIN.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 10 AM EDT
SUNDAY FOR ANZ630>632-634.
&&
$$
SYNOPSIS...LKB
NEAR TERM...LKB/MAM
SHORT TERM...JDM/MAM
LONG TERM...LKB
AVIATION...LSA
MARINE...BMD
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
402 PM EDT SAT AUG 31 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 359 PM EDT SAT AUG 31 2013
MAIN FCST CONCERNS IN THE SHORT TERM INVOLVE SHRA/TS CHCS ASSOCIATED
WITH SHRTWV NOW NEAR LK WINNIPEG.
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW WNW FLOW ALF OVER
THE NRN CONUS ON THE NRN FLANK OF SPRAWLING HI PRES CENTERED OVER
THE SW CONUS. STUBBORN LO CLDS OVER THE SCENTRAL COUNTIES ARE
FINALLY BURNING OFF. THERE IS A SHRTWV TRACKING THRU ONTARIO...BUT
THIS DISTURBANCE IS PASSING FAR ENUF TO THE N THAT THE COMMA TAIL
-SHRA ARE JUST BRUSHING NEAR ISLE ROYALE. WEAK RDG OF HI PRES OVER
THE GRT LKS/SHARP SUBSIDENCE INVRN SHOWN ON LOCAL 12Z RAOBS IS
BRINGING QUIET WX TO THE CWA FOR NOW. A STRONGER SHRTWV IS PRESENT
ALONG THE NDAKOTA/CNDN BORDER AND MOVING QUICKLY TO THE ESE. WHERE
THE SHARP DPVA/DEEP LYR QVECTOR CNVGC IN ADVANCE OF THIS FEATURE IS
OVERSPREADING AXIS OF HIER MUCAPE/H85 THETA E AHEAD OF ATTENDANT
COLD FNT...NMRS SHRA/TS ARE BREAKING OUT IN MN.
TNGT...SHRTWV JUST SW OF LK WINNIPEG IS PROGGED TO MOVE ESE AND OVER
NCENTRAL LK SUP BY 12Z SUN. AS THE DPVA/DEEP LYR QVECTOR CNVGC AND
AXIS OF HIER INSTABILITY/H85 THETA E MOVE INTO WRN LK SUP THIS
EVNG...EXPECT SHRA/TS NOW OVER MN TO SHIFT INTO THE WRN LAND CWA BY
06Z. GIVEN FCST MUCAPE IN EXCESS OF 1000 J/KG...SFC-6KM SHEAR IN THE
40-50KT RANGE /FORTUNATELY THE STORMS WL BECOME ELEVATED SO THIS WL
NOT BE THE EFFECTIVE LYR SHEAR/...AND FAIRLY SHARP LLVL CNVGC ALONG
ATTENDANT COLD FNT...SOME OF THESE STORMS MAY BE STRONG. BUT WITH
LOSS OF DAYTIME HEATING AND WEAKENING H85 THETA E AXIS...EXPECT THE
INTENSITY OF THESE SHRA/TS TO DIMINISH AS THEY SPREAD INTO CENTRAL
UPR MI LATE. IN FACT...THE MOST RECENT SPC CONVECTIVE OUTLOOK THRU
12Z SUN CONFINES THE SLGT RISK FOR SVR TS TO MN AND FAR WRN LK SUP.
WHERE TEMPS HAVE A CHC TO COOL DOWN A BIT OVER THE E HALF BEFORE THE
ARRIVAL OF CLDS/A BIT SHARPER PRES GRADIENT...ADDED PATCHY FOG WITH
EXPECTATION THAT MIN TEMPS FALLING INTO THE UPR 50S WL FALL THRU THE
CROSSOVER DEWPT OBSVD THIS AFTN.
SUN...AS SHRTWV OVER NCENTRAL LK SUP IN THE MRNG SHIFTS INTO SE
ONTARIO IN THE AFTN...DNVA/DEEP LYR QVECTOR DVGC/VIGOROUS NEGATIVE
H85 THETA E ADVCTN IS FCST TO ARRIVE W-E FOLLOWING ATTENDANT COLD
FROPA. EXPECT BAND OF SHRA/TS AHD OF COLD FNT TO SHIFT FM THE CNTRL
ZNS INTO THE ERN ZNS DURING THE MRNG. SHRA/TS INTENSITY MAY PICK UP
OVER THE FAR ERN CWA IN THE EARLY AFTN WITH IMPACT OF DAYTIME
HEATING LIFTING MUCAPE TO 500-1000 J/KG AND DEEP LYR SHEAR 30 TO 40
KTS BEFORE THE MORE ROBUST QVECTOR DVGC ARRIVES IN THE AFTN AND
BEGINS TO SUPPRESS THE CONVECTION WITH STRENGTHENING INVRN FOLLOWING
COLD FROPA AT ERY NEAR 21Z. THIS THREAT WOULD BE GREATER IF THE
SOMEWHAT SLOWER GFS VERIFIES...BUT THE PRESENT STEADY SPEED OF
SHRTWV INDICATES THE FASTER MODEL FCSTS ARE ON THE RIGHT TRACK.
FOLLOWING THE COLD FROPA AND ARRIVAL OF LLVL COOLER AIR...NAM FCST
SDNGS SHOW SHARPENING LLVL INVRN/PROSPECT FOR LO CLDS AND SOME
SPRINKLES...ESPECIALLY OVER THE W AND NCENTRAL WITH UPSLOPE NW FLOW.
SFC TEMPS MAY ACTUALLY FALL AT THESE PLACES DURING THE AFTN.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 359 PM EDT SAT AUG 31 2013
MORE SEASONABLE WEATHER IS EXPECTED THROUGH MUCH OF THE UPCOMING
WEEK...WITH CHANCES OF PRECIPITATION MONDAY AND AGAIN WEDNESDAY.
SUNDAY NIGHT AND MONDAY...A STRONG AND SHARP MID-LEVEL SHORTWAVE
OVER NE LAKE SUPERIOR WILL BE STARTING TO EXIT TO THE EAST AT THE
START OF THE PERIOD. THE ASSOCIATED SFC LOW WILL ALSO BE TRACKING
EASTWARD AWAY FROM EASTERN LAKE SUPERIOR. THE MAIN FORECAST CONCERN
IS HOW LONG MOISTURE WILL LINGER BEHIND THIS SYSTEM...AND HOW
WIDESPREAD UPSLOPE DRIZZLE/SHOWERS WILL BE. WITH PLENTY OF LOW-LEVEL
MOISTURE WRAPPING BEHIND THE LOW...EXPECT PLENTY OF DRIZZLE AND
LIGHT SHOWERS FOR ANY AREA EXPOSED TO NNW WINDS OFF LAKE SUPERIOR.
SUBSIDENCE WILL LOWER INVERSION HEIGHTS TO AROUND 1KM ACROSS THE
AREA...SO THE SATURATED LAYER WILL BE QUITE SHALLOW. INSOLATION ON
MONDAY SHOULD BE STRONG ENOUGH TO START ERODING THIS MOIST LAYER
MONDAY MORNING. INCREASINGLY DRIER AIR ADVECTING IN FROM WESTERN
ONTARIO SHOULD THEN REMOVE REMAINING CLOUDS/PRECIP FROM WEST TO EAST
THROUGHOUT MONDAY AFTERNOON.
HAVE INCREASED WINDS SEVERAL KNOTS ACROSS THE EAST HALF OF THE CWA
GIVEN A 1020MB SFC HIGH IN THE UPPER MS VALLEY IMPINGING ON THE
BACKSIDE OF THE DEPARTING 1002MB LOW. COULD SEE QUITE A BREEZY DAY
FOR MUCH OF THE AREA...WITH WINDS GUSTING OVER 30MPH RIGHT NEAR THE
LAKE SUPERIOR SHORE FROM BIG BAY EASTWARD. WILL CONTINUE TO RAMP UP
WORDING ON A HIGH SWIM RISK GIVEN THE LABOR DAY HOLIDAY.
MONDAY NIGHT...AS THE SFC HIGH SETTLES OVER NORTHERN WI MONDAY
NIGHT...CLEAR SKIES AND LOW PWAT VALUES OF LESS THAN 0.5 INCHES WILL
ALLOW FOR GOOD RADIATIONAL COOLING. HAVE MAINTAINED PREVIOUS
FORECAST TEMPS OF LOW 40S INTERIOR WEST HALF TO LOW 50S NEAR THE
GREAT LAKES. RESIDUAL STRONGER NW GRADIENT FLOW ACROSS THE EAST HALF
SHOULD LIMIT COOLING TO SOME EXTENT.
TUESDAY THROUGH THURSDAY...A SHORTWAVE TROUGH CURRENTLY TRACKING
EASTWARD ALONG THE ALLUETIAN ISLANDS WILL STALL OVER WESTERN ALASKA
AND SEND A SERIES OF WEAK WAVES ACROSS WESTERN CANADA. THE MAIN WAVE
OF INTEREST WILL BECOME AMPLIFIED BY ANOTHER STRONGER WAVE OVER THE
NORTH SLOPE OF ALAKSA. TIMING AND STRENGTH OF THIS FEATURE HAVE BEEN
UNDERSTANDABLY DIFFICULT FOR THE MODELS TO PIN DOWN. THE GFS HAS
WAVERED IN STRENGTH OVER THE LAST SEVERAL RUNS...WITH THE LATEST TWO
RUNS INDICATING A SLOWER AND WETTER SOLUTION. THIS IS LIKELY A
RESULT OF A LONGER PRECEEDING PERIOD OF LOW-LEVEL MOISTURE RETURN.
THE GEM IS THE QUICKEST SOLUTION OF THE THREE. HAVE OPTED TO EMPLOY
THE ECMWF FOR THE REST OF THE FORECAST GIVEN ITS MIDDLE GROUND AND
CONTINUITY OVER THE LAST COUPLE DAYS.
THE MAIN MID-LEVEL AND SFC LOWS WILL TRACK WELL NORTH OF THE
CWA...POSSIBLY AS FAR NORTH AS SOUTHERN HUDSON BAY. THE 990MB SFC
LOW DEPICTED BY THE ECMWF WILL BE STRONG ENOUGH TO SEND A POTENT
COLD FRONT SSE-WARD ACROSS THE CWA WEDNESDAY MORNING.
HOWEVER...THERE WILL BE A SUBSTANTIAL AMOUNT OF DRY AIR WITH THIS
SYSTEM GIVEN ITS ORIGIN. WILL PLACE ONLY SLIGHT CHANCE POPS ACROSS
THE FAR NORTH AND EAST CLOSER TO THE STRONGEST FORCING VIA MID-LEVEL
Q-VECTOR CONVERGENCE AND THE LEFT EXIT OF A 120KT UPPER JET. MUCH OF
UPPER MI...ESPECIALLY THE SOUTHWEST...LOOKS TO BE UNDER SUBSIDENCE
FROM THE RIGHT ENTRANCE OF THE JET...AND MAY NOT EVEN SEE MUCH IN
THE WAY OF CLOUD COVER. MOST OF THE COOLER AIR BEHIND THE FRONT WILL
STAY EAST OF THE AREA...SO ONLY A SLIGHTLY COOLER DAY THAN WEDNESDAY
IS EXPECTED FOR THURSDAY.
FRIDAY AND SATURDAY...BESIDE DEVELOPING THE IDEA OF DEEPER TROUGHING
ACROSS EASTERN CANADA...MODEL AGREEMENT ON SMALLER SCALE FEATURES IS
POOR BY THIS POINT IN THE FORECAST. THE GFS/GEM INDICATE STRONG SFC
HIGH PRESSURE BUILDING ACROSS THE AREA...WHILE THE ECMWF KEEP THE
HIGH MUCH FARTHER NE NEAR JAMES BAY. A WEAK SHORTWAVE DEPICTED BY
BOTH THE ECMWF AND GFS COULD BRING SHOWER CHANCES FOR FRIDAY...BUT
TIMING THE GFS IS SOMEWHAT SLOWER WITH THIS IDEA. EITHER WAY...VERY
LIMITED MOISTURE WILL PRECLUDE ANYTHING MORE THAN SPOTTY SHOWER
COVERAGE. HAVE OPTED TO MAINTAIN CONCENSUS FORECAST AT THIS POINT
GIVEN UNCERTAINTY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 120 PM EDT SAT AUG 31 2013
EXPECT DRY WX/VFR CONDITIONS THRU THIS EVNG WITH RELATIVELY DRY/
STABLE AIRMASS IN PLACE. BUT APRCH OF COLD FNT/MORE UNSTABLE AIRMASS
WL BRING THE THREAT OF SHRA AND PERHAPS SOME TS LATER TNGT...
ESPECIALLY AT CMX AND IWD. RETAINED MENTION OF VCTS AT THESE SITES.
FOLLOWING THE COLD FROPA LATE TNGT/EARLY SUN MRNG...EXPECT SOME LO
CLDS/IFR CONDITIONS TO IMPACT IWD AND CMX WITH UPSLOPE NW FLOW UNDER
STRENGTHENING SHARP INVRN.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 359 PM EDT SAT AUG 31 2013
EXPECT SSW WINDS UP TO 20-25 KTS TONIGHT INTO SUN MORNING OVER THE E
HALF OF THE LAKE UNDER A SHARPENING PRES GRADIENT AHEAD OF AN
APPROACHING COLD FRONT. FOLLOWING THE PASSAGE OF THIS FRONT...THERE
WILL BE A WIND SHIFT TO THE NW...WITH WINDS INCREASING UP TO 25 KTS
IN THE AFTERNOON. THE COMBINATION OF DECREASING STABILITY WITH THE
ARRIVAL OF A COOL AIRMASS AND A SHARPENING PRES GRADIENT BETWEEN A
DEPARTING LO PRES SYSTEM AND AN APPROACHING HI WILL RESULT IN NW-N
WINDS UP TO 20-30 KTS ON SUN NIGHT INTO MON. THE ARRIVAL OF THE HI
AND WEAKER PRES GRADIENT WILL ALLOW WINDS TO DIMINISH UNDER 20 KTS
TUE THRU THU.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KLUBER
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS BUFFALO NY
218 PM EDT SAT AUG 31 2013
.SYNOPSIS...
A SLOW MOVING FRONTAL BOUNDARY WILL MOVE SLOWLY AWAY FROM THE AREA
TONIGHT WITH ANY SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ENDING
OVERNIGHT. ANOTHER WEAK AREA OF LOW PRESSURE WILL APPROACH LATER
SUNDAY THEN CROSS THE REGION SUNDAY NIGHT AND LABOR DAY WITH A FEW
MORE SHOWERS AND THUNDERSTORMS...ALTHOUGH THERE WILL BE PLENTY OF
RAIN FREE TIME AS WELL. COOLER AND LESS HUMID AIR WILL THEN ARRIVE
BY TUESDAY WITH EVEN COOLER AIR ARRIVING LATER IN THE WEEK.
&&
.NEAR TERM /THROUGH SUNDAY/...
RADAR IMAGERY THIS AFTERNOON SHOWING A FEW SCATTERED SHOWERS ACROSS
THE HIGHER TERRAIN OF THE SOUTHERN TIER AND EAST OF LAKE ONTARIO...
WITH BETTER COVERAGE ACROSS CENTRAL AND EASTERN NY. WATER VAPOR
IMAGERY AND OBJECTIVE RUC ANALYSIS NOW SHOWS THE AXIS OF THE MID
LEVEL TROUGH FROM CENTRAL NY TO CENTRAL PA...SO BETTER LARGE SCALE
ASCENT SHOULD CONTINUE TO DRIFT EAST TOWARDS EASTERN NY THROUGH LATE
AFTERNOON WITH THE BETTER SHOWER COVERAGE FOLLOWING THIS FEATURE.
BEHIND THE SHORTWAVE...EXTENSIVE MID LEVEL DRYING AND WARMING HAS
PRODUCED AN EFFECTIVE CAP SO FAR.
EVEN WITH THE CAP IN PLACE...PLENTY OF LOW LEVEL MOISTURE WILL STILL
ALLOW A FEW SCATTERED SHOWERS TO FORM BEHIND THE MAIN MID LEVEL
TROUGH. THESE WILL BE MOST PROBABLE ACROSS THE HIGHER TERRAIN OF THE
SOUTHERN TIER...FINGER LAKES...AND EASTERN LAKE ONTARIO REGION
THROUGH EARLY EVENING. AN ISOLATED SHOWER CANNOT BE RULED OUT ON THE
LAKE PLAINS EITHER...ESPECIALLY ALONG THE CONVERGENCE ZONE NOTED IN
LOW LEVEL WINDS FROM THE NIAGARA PENINSULA ACROSS THE NIAGARA
FRONTIER. EVEN SO...MOST AREAS WILL BE MAINLY DRY THROUGH EARLY
EVENING. EXTENSIVE LOW LEVEL MOISTURE WILL KEEP PLENTY OF CLOUDS IN
PLACE WITH ONLY A FEW BREAKS OF SUN AT TIMES. TEMPERATURES WILL TOP
OUT IN THE UPPER 70S TO LOWER 80S IN MOST AREAS WITH MID 70S ACROSS
THE HIGHER TERRAIN AND NORTH COUNTRY.
TONIGHT THE WEAK FRONTAL ZONE WILL CONTINUE TO SAG SLOWLY SOUTHEAST
AWAY FROM THE AREA WHILE THE WEAK WAVE OF LOW PRESSURE MOVES SLOWLY
EAST INTO NEW ENGLAND. THE MID LEVEL SHORTWAVE WILL ALSO WEAKEN
FURTHER AND SLOWLY EXIT THE AREA. WITH THE LOSS OF SUPPORT AND
DIURNAL COOLING EXPECT ANY SHOWERS FROM THE SOUTHERN TIER INTO THE
FINGER LAKES AND EASTERN LAKE ONTARIO REGION TO SLOWLY DRIFT EAST
AND END THROUGH THE FIRST HALF OF THE NIGHT.
MODEL GUIDANCE IS BULLISH WITH LOW LEVEL MOISTURE OVERNIGHT...AND
THIS SEEMS LIKE A REASONABLE SOLUTION GIVEN THE WEALTH OF LOW
STRATUS HANGING JUST NORTH OF LAKE ONTARIO THIS AFTERNOON. WITH A
VERY WEAK LOW LEVEL GRADIENT IN PLACE...THIS MOISTURE FIELD SHOULD
SPREAD SOUTHWARD OVERNIGHT AND INTO OUR REGION. THIS WILL SET THE
STAGE FOR WIDESPREAD STRATUS AND FOG DEVELOPMENT OVERNIGHT. UPS FOG
METHOD ALSO SUPPORTS FOG OVERNIGHT WITH FORECAST LOW TEMPERATURES
CROSSING OVER OUR AFTERNOON DEWPOINTS FAIRLY EARLY IN THE NIGHT.
EXPECT LOWS IN THE MID TO UPPER 60S ON THE LAKE PLAINS WITH LOWER
60S ACROSS THE INTERIOR SOUTHERN TIER AND EAST OF LAKE ONTARIO.
ON SUNDAY THE EXTENSIVE FOG AND LOW STRATUS WILL SLOWLY BURN OFF IN
THE MORNING WITH THE ONSET OF DAYTIME MIXING. THE NEW 12Z
GFS/NAM/GEM SOLUTIONS ARE ALL MUCH FASTER WITH THE NEXT SYSTEM...
ALL LIFTING A CONVECTIVELY AUGMENTED MID LEVEL SHORTWAVE INTO THE
SOUTHERN TIER AND FINGER LAKES DURING THE AFTERNOON. LARGE SCALE
ASCENT WILL INCREASE AHEAD OF THIS SHORTWAVE...AND PWAT WILL RISE TO
AROUND 1.75 INCHES AS A PLUME OF DEEPER MOISTURE ADVECTS NORTHEAST
OUT OF THE OHIO VALLEY IN ADVANCE OF A WEAK SURFACE LOW OVER THE
WESTERN LAKES.
GIVEN THE FASTER SOLUTION...HAVE INCREASED POPS FOR THE AFTERNOON
ESPECIALLY ACROSS THE INTERIOR SOUTHERN TIER AND WESTERN FINGER
LAKES WITH LIKELY POPS BY THE END OF THE AFTERNOON...AND CHANCE POPS
SPREADING NORTH TO KBUF-KROC LATE. OUTSIDE OF THIS BETTER CHANCE OF
RAIN...A FEW ISOLATED SHOWERS MAY DEVELOP EARLIER IN THE DAY FROM
CENTRAL NY INTO THE HIGHER TERRAIN EAST OF LAKE ONTARIO AS SOME
MESOSCALE MODEL GUIDANCE SUGGESTS A WEAK LOW LEVEL CONVERGENCE ZONE
LINGERING IN THAT AREA.
850MB TEMPS ARE STILL UP AROUND +16C...BUT THE EXTENSIVE EARLY
STRATUS AND ADDITIONAL AFTERNOON CLOUD COVER WILL KEEP US FROM
REACHING THE FULL POTENTIAL OF THE WARM AIRMASS. EXPECT HIGHS IN THE
LOWER 80S IN MOST AREAS...WITH MID TO UPPER 70S ACROSS HIGHER
TERRAIN.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
ON SUNDAY...OUR INITIAL WEAK AREA OF LOW PRESSURE WILL EXIT OUT
ACROSS NORTHERN NEW ENGLAND...WHILE A SECOND AND MORE ELONGATED
SURFACE WAVE WILL BE IN THE PROCESS OF PUSHING ACROSS THE WESTERN
AND CENTRAL GREAT LAKES...IN ASSOCIATION WITH A SHORTWAVE TROUGH
DIGGING SOUTHEAST FROM ONTARIO PROVINCE. IN BETWEEN ALL OF THIS...A
WEAK BUBBLE OF HIGH PRESSURE AND SOMEWHAT DRIER AIR WILL BRIEFLY
SETTLE ACROSS WESTERN AND NORTH CENTRAL NEW YORK...AND WILL PROVIDE
OUR REGION WITH THE DRIEST AND NICEST OVERALL DAY OF THE LONG
HOLIDAY WEEKEND. ANY CONVECTIVE POTENTIAL WILL BE FAIRLY LIMITED AND
LARGELY CONFINED TO OUR NORTHEASTERN AND SOUTHWESTERN EXTREMITIES
WHERE MOISTURE WILL BE SOMEWHAT GREATER AT POINTS...WITH THE NORTH
COUNTRY MAINLY SEEING LOWER-END CHANCES IN THE MORNING ON THE TAIL
END OF THE DEPARTING INITIAL WAVE...AND THE SOUTHERN TIER
EXPERIENCING A SIMILAR RISK IN THE AFTERNOON WITH DIURNAL HEATING.
WILL THUS KEEP SOME LOWER-END CHANCE POPS IN PLACE FOR BOTH OF THESE
AREAS...WITH THE REST OF THE REGION MORE LIKELY TO REMAIN MAINLY DRY
THROUGH THE DAY. WITH RESPECT TO TEMPS...850 MB READINGS OF +14C TO
+16C SHOULD YIELD FAIRLY WIDESPREAD HIGHS IN THE LOWER TO MID
80S...WITH THE WARMEST READINGS COMING ACROSS THE GENESEE VALLEY AND
FINGER LAKES.
DURING THE COURSE OF SUNDAY NIGHT AND MONDAY...THE UPSTREAM
SHORTWAVE TROUGH WILL CONTINUE TO DIG FURTHER SOUTHEASTWARD AND
EVENTUALLY ESTABLISH A LARGER-SCALE UPPER TROUGH OVER THE GREAT
LAKES AND NORTHEAST...WITH ITS ATTENDANT COMPLEX AREA OF LOW
PRESSURE GRADUALLY SLIDING EASTWARD ACROSS THE LOWER LAKES AND NEW
YORK STATE. INCREASING MOISTURE OUT AHEAD OF THESE FEATURES WILL
HELP PUSH PWAT LEVELS BACK UP TO AROUND 1.50" FOR A TIME...AND THIS
COUPLED WITH INCREASING SYNOPTIC-SCALE LIFT WILL RESULT IN A 6-12
HOUR WINDOW DURING WHICH CONVECTION WILL BE MORE LIKELY...WITH A
ROUGH MODEL CONSENSUS SUGGESTING THAT THIS SHOULD COME BETWEEN 06Z
AND 18Z MONDAY. HAVE THEREFORE CONTINUED WITH WIDESPREAD LIKELY POPS
FOR THIS TIME FRAME...ALONG WITH A MENTION OF THE POTENTIAL FOR SOME
LOCALLY HEAVIER RAINFALL GIVEN THE AFOREMENTIONED PRECIPITABLE WATER
VALUES.
FOLLOWING THIS...CONVECTIVE POTENTIAL SHOULD THEN WANE FROM WEST TO
EAST MONDAY AFTERNOON AND EVENING FOLLOWING THE PASSAGE OF THE MAIN
SURFACE TROUGH AXIS...WITH MAINLY DRY CONDITIONS RETURNING TO THE
BULK OF THE AREA FOR THE SECOND HALF OF MONDAY NIGHT. THIS SAID...
SKIES SHOULD REMAIN FAIRLY CLOUDY THROUGH THE NIGHT AS THE NAM/GFS/
ECMWF ALL SUGGEST THAT A FAIR AMOUNT OF MOISTURE WILL REMAIN IN
PLACE BELOW 850 MB...WHICH IN COMBINATION WITH A NORTHWESTERLY
UPSLOPE FLOW AND PROGRESSIVELY COOLER AIR ALOFT SHOULD BE SUPPORTIVE
OF A LINGERING STRATOCU DECK. WITH THIS IN MIND...HAVE BUMPED UP THE
AMOUNT OF SKY COVER SOME 20-30 PERCENT FOR MONDAY NIGHT.
OTHERWISE...EXPECT CONDITIONS TO TREND LESS HUMID AND NOTICEABLY
COOLER MONDAY NIGHT AS A MUCH COOLER AIRMASS INFILTRATES THE REGION
IN THE WAKE OF THE DEPARTING SURFACE TROUGH...WITH NIGHTTIME LOWS
FALLING BACK TO WITHIN A FEW DEGREES OF 60 AREAWIDE.
ON TUESDAY...OUR AREA WILL REMAIN FIRMLY UNDER THE INFLUENCE OF THE
LINGERING UPPER TROUGH AND ASSOCIATED COOL POOL...WITH 850 MB TEMPS
OF AROUND +8C SUPPORTING HIGHS RANGING WITHIN A FEW DEGREES OF 70.
WITH DIURNAL HEATING OF OUR MUCH COOLER AIRMASS AND THE UPPER TROUGH
AXIS REMAINING IN OUR VICINITY...EXPECT THAT THE LINGERING STRATOCU
DECK TUESDAY MORNING WILL MERELY TRANSITION TO A BROKEN CU FIELD
OVER TIME...WITH SOME OF THESE POSSIBLY DEVELOPING ENOUGH DURING THE
MIDDAY/AFTERNOON HOURS TO PRODUCE SOME SCATTERED LIGHT SHOWERS. HAVE
THUS RETAINED SOME LOW CHANCE POPS TO COVER THIS POTENTIAL...THOUGH
HAVE REMOVED ANY MENTION OF THUNDER AS INSTABILITY LEVELS APPEAR TO
BE FAR TOO LOW TO SUPPORT THIS.
ANY LIGHT SHOWERS AND DIURNALLY-DRIVEN CU SHOULD THEN QUICKLY
DISSIPATE LATE TUESDAY AFTERNOON/EARLY TUESDAY EVENING WITH THE LOSS
OF HEATING AND AS HIGH PRESSURE/MUCH DRIER AIR QUICKLY RIDGES
EASTWARD FROM THE OHIO VALLEY AND CENTRAL GREAT LAKES. THIS SHOULD
RESULT IN A RETURN TO PARTLY CLOUDY SKIES AND DRY WEATHER FOR THE
MAJORITY OF TUESDAY NIGHT...WITH NIGHTTIME LOWS SETTLING BACK TO
EVEN MORE COMFORTABLE LEVELS IN THE LOWER TO MID 50S.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
ON WEDNESDAY...A BRIEF PERIOD OF MODEST WARM AIR ADVECTION WILL
OVERSPREAD OUR REGION AS THE AFOREMENTIONED SURFACE RIDGE SETTLES
ACROSS THE CAROLINAS...AND A SECONDARY COLD FRONT DROPS
SOUTHEASTWARD ACROSS ONTARIO AND QUEBEC PROVINCES. UNDER THE
INFLUENCE OF THE RESULTANT BROAD WESTERLY FLOW...850 MB TEMPS LOOK
TO RECOVER BACK TO AROUND +12C...WHICH COUPLED WITH A DECENT
AMOUNT OF SUNSHINE SHOULD RESULT IN HIGH TEMPS CLIMBING BACK TO
NEAR NORMAL LEVELS IN THE MID 70S IN MOST LOCATIONS.
AFTER THAT...THE PAST FEW RUNS OF THE GFS/ECMWF HAVE BEEN IN GOOD
AGREEMENT THAT THE SECONDARY COLD FRONT WILL DROP SOUTHEAST ACROSS
OUR REGION BETWEEN WEDNESDAY NIGHT AND EARLY THURSDAY. AS THIS
FEATURE LOOKS TO BE RELATIVELY MOISTURE STARVED AND LACKING MUCH IN
THE WAY OF UPPER LEVEL SUPPORT...HAVE KEPT ASSOCIATED SHOWER
PROBABILITIES CONFINED TO THE SLIGHT CHANCE TO LOW-END CHANCE
RANGE...WITH THE BEST PRECIP CHANCES COMING ACROSS THE NORTH COUNTRY
AND FAR EASTERN FINGER LAKES WHERE MOISTURE WILL BE THE DEEPEST.
FOLLOWING THE PASSAGE OF THIS SECONDARY FRONT...A REINFORCING SHOT
OF MUCH COOLER/DRIER AIR WILL SETTLE SOUTH ACROSS OUR REGION FOR
BOTH THURSDAY AND FRIDAY. THIS WILL RESULT IN RETURN TO DRY WEATHER
FOR THE END OF THE WORK WEEK...WITH TEMPERATURES ALSO FALLING BACK
TO BELOW NORMAL BUT ALSO COMFORTABLE LEVELS. MORE SPECIFICALLY...
DAYTIME HIGHS WILL SETTLE BACK TO THE MID 60S TO LOWER 70S FOR BOTH
DAYS...WHILE NIGHTTIME LOWS DROP INTO THE MID 40S TO LOWER 50S
THURSDAY NIGHT.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
A SLOW MOVING FRONTAL ZONE AND WEAK WAVE OF LOW PRESSURE WILL
CONTINUE TO DRIFT ACROSS THE AREA THIS AFTERNOON. THIS WILL PRODUCE
A FEW SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS...MAINLY FROM THE
HIGHER TERRAIN OF THE SOUTHERN TIER THROUGH THE FINGER LAKES TO THE
EASTERN LAKE ONTARIO REGION...WITH VERY LOW COVERAGE IF ANYTHING AT
ALL FROM KBUF-KROC. A WEALTH OF LOW LEVEL MOISTURE WILL CONTINUE TO
SUPPORT PLENTY OF STRATUS AND STRATOCUMULUS THIS AFTERNOON WITH
MAINLY VFR CIGS ACROSS LOWER ELEVATIONS AND MVFR ACROSS THE HIGHER
TERRAIN AND NORTH COUNTRY.
TONIGHT ANY SHOWERS WILL GRADUALLY END FROM NORTHWEST TO SOUTHEAST
AS THE FRONTAL ZONE SLOWLY LEAVES THE AREA. MODEL GUIDANCE IS
BULLISH WITH LOW LEVEL MOISTURE OVERNIGHT...AND THIS SEEMS PLAUSIBLE
GIVEN THE AMOUNT OF LOW STRATUS JUST UPSTREAM ACROSS SOUTHERN
ONTARIO...POISED TO MOVE INTO OUR REGION OVERNIGHT. WITH THIS IN
MIND...EXPECT WIDESPREAD IFR DEVELOPMENT TONIGHT WITH BOTH STRATUS
AND FOG DEVELOPING. THE FOG AND STRATUS WILL SLOWLY BURN OFF SUNDAY
MORNING WITH A RETURN TO VFR BY MIDDAY.
LATER SUNDAY AFTERNOON MODEL GUIDANCE IS NOW MUCH FASTER IN BRINGING
IN THE NEXT WEAK SYSTEM...WITH SHOWER AND THUNDERSTORM CHANCES
INCREASING LATER IN THE DAY ESPECIALLY FROM THE SOUTHERN TIER INTO
THE GENESEE VALLEY AND FINGER LAKES WITH ASSOCIATED BRIEF MVFR/IFR
CONDITIONS WITH ANY HEAVIER RAINFALL.
OUTLOOK...
SUNDAY NIGHT...VFR/MVFR WITH A FEW SHOWERS AND THUNDERSTORMS LIKELY
WITH ASSOCIATED BRIEF MVFR/IFR.
MONDAY...A FEW SHOWERS AND THUNDERSTORMS LIKELY WITH ASSOCIATED
BRIEF IFR/MVFR.
TUESDAY...MAINLY VFR WITH A CHANCE OF A FEW SHOWERS.
WEDNESDAY...MAINLY VFR.
WEDNESDAY NIGHT...VFR/MVFR WITH A CHANCE OF SHOWERS.
THURSDAY...IMPROVING TO VFR.
&&
.MARINE...
NORTHERLY FLOW IN THE 5 TO 10 KNOT RANGE WILL CONTINUE TONIGHT ON
LAKES ERIE AND ONTARIO BEHIND A WEAK FRONTAL BOUNDARY WHICH WILL
SLOWLY EXIT THE AREA. SOME FOG MAY FORM OVERNIGHT INTO SUNDAY
MORNING LIMITING VISIBILITY IN SOME SPOTS.
LIGHT WINDS WILL CONTINUE ON SUNDAY WITH A WEAK PRESSURE GRADIENT IN
PLACE. SOUTHWEST WINDS WILL INCREASE SOME ON MONDAY AS A WEAK AREA
OF LOW PRESSURE CROSSES THE LOWER LAKES...BUT CONDITIONS ARE
EXPECTED TO REMAIN WELL BELOW SMALL CRAFT ADVISORY CRITERIA.
SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE AT TIMES FROM LATER
SUNDAY AFTERNOON THROUGH MONDAY...WITH LOCALLY HIGHER WINDS AND
WAVES POSSIBLE.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...HITCHCOCK
NEAR TERM...HITCHCOCK
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...HITCHCOCK
MARINE...HITCHCOCK
AREA FORECAST DISCUSSION
NWS RALEIGH NC
256 PM EDT SAT AUG 31 2013
.SYNOPSIS...
A WARM AND MOIST SOUTHERLY FLOW WILL PREVAIL THROUGH THE REST OF THE
WEEKEND. A COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST ON
MONDAY...THEN PUSH SLOWLY EAST THROUGH THE CAROLINAS ON TUESDAY. IN
THE WAKE OF THE FRONT...HIGH PRESSURE WILL BUILD INTO THE REGION ON
WEDNESDAY AND LINGER THROUGH THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 200 PM SATURDAY...
OVERVIEW:
LIGHT NW FLOW ALOFT WILL PREVAIL ACROSS THE REGION THROUGH
TONIGHT...IN A WEAKNESS BETWEEN AN UPSTREAM RIDGE OVER THE SOUTHERN
PLAINS/ROCKIES AND A DOWNSTREAM RIDGE OFFSHORE THE SOUTHEAST COAST.
17Z WV IMAGERY AND RAP DATA INDICATED SMALL AMPLITUDE DISTURBANCES
UPSTREAM ACROSS OH/KY/WV...TRACKING SOUTHEAST TOWARD THE MID-
ATLANTIC AND NORTHERN PORTIONS OF NC.
PRECIPITATION CHANCES:
THE LOW-LEVEL RIDGE EXTENDING WESTWARD INTO CENTRAL NC THIS MORNING
HAS FURTHER WEAKENED...GIVING WAY TO AN INCREASINGLY MOIST SOUTHERLY
RETURN FLOW FROM THE SFC-925 MB...WITH ADDITIONAL MOISTURE ADVECTING
INTO THE AREA FROM THE WEST/WNW AT H85. SEASONABLY STRONG INSOLATION
WILL RESULT IN MARGINAL TO MODERATE DIURNAL DESTABILIZATION BY PEAK
HEATING WITH MLCAPE VALUES RANGING FROM 1500-2000 J/KG IN THE
WESTERN PIEDMONT TO 500-1000 J/KG IN THE EAST WHERE THE LOW-LEVELS
ARE DRIER AS NOTED ABOVE. THE PRIMARY UNCERTAINTY W/REGARD TO
CONVECTION WILL BE FORCING. VERY LITTLE IF ANY LOW-LEVEL FORCING
WILL BE PRESENT THIS AFT/EVE WITH LARGELY UNIDIRECTIONAL SFC-925 MB
FLOW OVER CENTRAL NC. ADDITIONALLY...UPPER LEVEL FORCING /DPVA/ IS
EXPECTED TO REMAIN N/NW OF CENTRAL NC THIS AFT/EVE AS SMALL
AMPLITUDE DISTURBANCES TRACK SLOWLY E/ESE FROM THE OH VALLEY INTO
THE WV AND CENTRAL/WESTERN VA. AN MCV AND A ROBUST COLD POOL ASSOC/W
AN ONGOING MCS UPSTREAM OVER EASTERN KY AND SOUTHWEST VA AT 17Z IS
LIKELY TO TRACK SOUTHEASTWARD TOWARD NORTHWEST NC AND MAY PROVIDE
SUFFICIENT FORCING FOR CONVECTION TO DEVELOP IN THE NW PIEDMONT LATE
THIS AFT/EVE (22-04Z). WITH THE ABOVE IN MIND...WILL INDICATE PRECIP
CHANCES OF 20-30% WEST OF THE HWY 1 CORRIDOR WITH THE RELATIVE BEST
CHANCE IN THE TRIAD. EAST OF HWY 1...GIVEN A PROFOUND LACK OF
FORCING AND A DRIER LOW-LEVEL AIRMASS /MARGINAL DESTABILIZATION/...
WILL KEEP THE FCST DRY. CHANCES FOR CONVECTION WILL DECREASE BY
MIDNIGHT IN ASSOC/W INCREASING NOCTURNAL STABILIZATION...THOUGH IF
SMALL AMPLITUDE DISTURBANCES AND/OR THE AFOREMENTIONED MCV GRAZE OR
TRACK ACROSS NORTHERN PORTIONS OF CENTRAL NC THERE MAY BE SUFFICIENT
MOISTURE/INSTABILITY TO SUPPORT ISOLD CONVECTION OVERNIGHT...AND
THIS WILL BE THE BASIS FOR A 20% CHANCE OF SHOWERS NORTH OF HWY 64
AFTER MIDNIGHT.
TEMPERATURES:
EXPECT HIGHS TODAY SLIGHTLY ABOVE NORMAL...IN THE MID/UPPER 80S TO
NEAR 90F. LOWS TONIGHT A FEW DEGREES ABOVE NORMAL DUE TO INCREASING
LOW-LEVEL MOISTURE AND PERHAPS MID/UPPER LEVEL CLOUD COVER...IN THE
UPPER 60S TO NEAR 70F.
SEVERE POTENTIAL:
A VERY SMALL (ALBEIT CONDITIONAL) THREAT OF AN ISOLD SEVERE
DOWNBURST EXISTS IN THE FAR W/NW PIEDMONT LATE THIS AFT/EVE WHERE
MODERATE INSTABILITY (1500-2000 J/KG) AND MODERATE DCAPE (1000 J/KG)
ARE PRESENT IN ADVANCE OF THE MCS /COLD POOL/ APPROACHING THE
NORTHWEST NC MOUNTAINS. CONFIDENCE IS LOW WITH REGARD TO HOW THE
AFOREMENTIONED COLD POOL WILL EVOLVE AND WHETHER OR NOT IT WILL
AFFECT THE NW PIEDMONT IN VICINITY OF PEAK HEATING...AND HAVE OPTED
TO LEAVE OUT ANY MENTION OF SVR WX IN THE HWO. -VINCENT
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
AS OF 215 PM SATURDAY...
CYCLONIC FLOW ALOFT WILL STRENGTHEN ACROSS THE EASTERN CONUS AS
POTENT SHORTWAVE ENERGY TRACKING FROM SOUTHERN CANADA INTO THE UPPER
MIDWEST THIS AFTERNOON DIGS SOUTHEAST INTO THE UPPER GREAT LAKES ON
SUNDAY. AS A RESULT...A MOIST SOUTHWESTERLY LOW-LEVEL FLOW WILL
STRENGTHEN OVER THE CAROLINAS ON SUNDAY...WITH PWAT VALUES
INCREASING TO ABOVE NORMAL IN THE 1.75-2.00" RANGE AND DIURNAL
DESTABILIZATION YIELDING MARGINAL TO MODERATE INSTABILITY (1000-2000
J/KG MLCAPE) DURING PEAK HEATING. LOW-LEVEL FORCING ON SUNDAY WILL
BE ANEMIC ONCE AGAIN WITH LARGELY UNIDIRECTIONAL LOW-LEVEL FLOW...
THOUGH WITH STRONGER CYCLONIC FLOW ALOFT AND DEEPER MOISTURE ONE
WOULD EXPECT PRECIP CHANCES HIGHER THAN TODAY. ULTIMATELY...PRECIP
CHANCES WILL LIKELY DEPEND ON UPSTREAM DEVELOPMENT ACROSS THE HIGHER
TERRAIN IN WESTERN NC AND/OR THE TIMING OF SMALL AMPLITUDE
DISTURBANCES EMBEDDED IN CYCLONIC FLOW ALOFT. WILL INDICATE A 30-40%
CHANCE OF SHOWERS/STORMS SUNDAY AFT/EVE...HIGHEST IN NORTHERN
PORTIONS OF THE AREA...WITH A SLIGHT CHANCE OF SHOWERS PERSISTING
AFTER MIDNIGHT GIVEN CYCLONIC FLOW ALOFT AND DEEP MOISTURE IN THE
PRESENCE OF MARGINAL INSTABILITY. HIGHS ON SUN SIMILAR TO TODAY...
PERHAPS SLIGHTLY WARMER IF CLOUD COVER IS NOT PERVASIVE DURING THE
AFTERNOON...IN THE UPPER 80S TO NEAR 90F...WARMEST IN THE SANDHILLS
AND COASTAL PLAIN. LOWS SUN NIGHT A FEW DEGREES ABOVE NORMAL DUE TO
CLOUD COVER AND DEEP MOISTURE...IN THE LOWER 70S. -VINCENT
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
AS OF 255 PM SATURDAY...
THE LONG TERM WILL BE CHARACTERIZED BY A FAIRLY STAGNANT UPPER LEVEL
PATTERN CONSISTING OF STRONG HIGH PRESSURE OVER THE SOUTHWESTERN
UNITED STATES AND A NEAR STATIONARY UPPER LEVEL TROUGH OVER THE EAST
COAST. THE FIRST HALF OF THE LONG TERM WILL SEE A SLOW DEEPENING OF
THE TROUGH THROUGH WEDNESDAY BEFORE A GRADUAL LIFTING FOR THE END OF
THE WEEK AND INTO THE WEEKEND. AT THE SURFACE A LOW PRESSURE SYSTEM
OVER THE NORTHERN GREAT LAKES WILL TRACK VERY SLOWLY EASTWARD
THROUGH SOUTHERN QUEBEC WITH A COUPLE OF ASSOCIATED COLD FRONTS
STRETCHED ACROSS THE EASTERN CONUS. EARLY IN THE PERIOD THE BERMUDA
HIGH WILL HELP TRANSPORT MOISTURE OUT OF THE GULF OF MEXICO AND
CARIBBEAN SEA INTO THE SOUTHEASTERN US BEFORE IT MOVES FURTHER OUT
TO SEA...HELPING TO DRY CONDITIONS OUT BY THE END OF THE WEEK.
MONDAY WILL BEGIN WITH TWO FRONTAL SYSTEMS...ONE ON EITHER SIDE OF
THE CWA WITH THE LEAD FRONT OFF THE COAST AND THE TRAILING FRONT
BACK ACROSS THE OHIO AND LOWER MISSISSIPPI VALLEYS. MODEL FORECAST
SOUNDINGS VIEWED IN BUFKIT SHOW AN ELEVATED MIXED LAYER PRESENT FROM
ROUGHLY 800 MB UP TO 600 MB WHICH GREATLY INCREASES INSTABILITY...ON
THE ORDER OF 1500-2000 J/KG. MID-LEVEL LAPSE RATES OF 6-7 DEGREES
PER KM AND PRECIPITABLE WATER VALUES OF AROUND 1.75 INCHES ALL
INDICATE THE POTENTIAL FOR CONVECTION. HAIL AND WINDS COULD BOTH BE
A POSSIBILITY AS THE HAIL GROWTH ZONE BECOMES FAIRLY SATURATED BY
AFTERNOON. IN ADDITION DCAPE VALUES BETWEEN KRDU AND KGSO SHOULD BE
BETWEEN 1000 AND 1500 J/KG. DESPITE THIS...SHEAR WILL BE
MINIMAL...WITH BULK VALUES 15-20 KNOTS AT BEST. WHILE WIDESPREAD
CONVECTION IS NOT LIKELY...THE WILL BE A CHANCE OF SCATTERED STORMS
WITH A FEW OF THEM POTENTIALLY BECOMING SEVERE. HIGHS IN THE LOW
90S...LOWS UPPER 70S.
ALTHOUGH THERE IS SOME DISCREPANCIES IN MODEL TIMING AND
LOCATION...THE NEWEST RUN OF THE GFS SUGGESTS THE FRONT WILL BE
SOMEWHERE IN BETWEEN RALEIGH AND FAYETTEVILLE BY PEAK HEATING AND
WHILE ISOLATED TO SCATTERED CONVECTION CANT BE RULED OUT IN THE
EXTREME SOUTHEAST IT LOOKS LIKE A MUCH DRIER AIRMASS WILL TAKE OVER
MOST OF THE CWA WITH VERY LIMITED INSTABILITY AND SHEAR. COOLER AND
DRIER CONDITIONS WILL BEGIN TO FILTER INTO THE AREA...HIGHS MID TO
UPPER 80S. LOWS LOWER 60S NW TO UPPER 60S SE.
WEDNESDAY THROUGH FRIDAY SHOULD REMAIN QUIET AS SURFACE HIGH
PRESSURE OVER THE OHIO VALLEY KEEPS THE COLD FRONT EAST OF THE AREA.
A SUPPORTING MIGRATORY HIGH DROPPING SOUTHEASTWARD OUT OF THE
NORTHERN PLAINS WILL HELP TO PROPEL A SECONDARY COLD FRONT THROUGH
THE REGION THAT WILL REINFORCE DRY CONDITIONS THROUGH AT LEAST
FRIDAY MORNING. MOISTURE SLOWLY INCREASES FRIDAY AFTERNOON AND
EASTERLY FLOW OFF THE ATLANTIC COULD HELP AID SOME DIURNAL
CONVECTION FRIDAY AFTERNOON...PRIMARILY FOCUSED ON THE SEA BREEZE.
SATURDAY WILL FEATURE INCREASED MOISTURE WITH A GREATER CHANCE FOR
DIURNAL CONVECTION. HIGHS DURING THIS PERIOD WILL BE LOW TO MID 80S
WITH LOWS IN THE LOWER TO MID 60S.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AS OF 115 PM SATURDAY...
24-HR TAF PERIOD:
VFR CONDITIONS WILL LARGELY PREVAIL THROUGH MIDNIGHT WITH CEILINGS
RANGING FROM 3000-5000 FT AGL...THOUGH IT IS POSSIBLE THAT THE
INT/GSO TERMINALS COULD SEE SUB-VFR CONDITIONS IN ASSOCIATION WITH
ISOLD SHOWERS AND THUNDERSTORMS...PRIMARILY BETWEEN 20-03Z.
SOUTHWEST WINDS AT 5-10 KT WILL WEAKEN TO 5 KT OR LESS OVERNIGHT. A
PERIOD OF SUB-VFR FOG OR CEILINGS WILL BE POSSIBLE EARLY SUNDAY
MORNING IN ASSOCIATION WITH LOW-LEVEL WARM ADVECTION...PRIMARILY
BETWEEN 08-13Z. AT THIS TIME...WILL ACCOUNT FOR THE FOG/STRATUS
POTENTIAL BY ADDING A TEMPO GROUP /5SM BR BKN010/ FOR 08-12Z AT ALL
TERMINALS. EXPECT SOUTHWEST WINDS INCREASING TO ~10 KT BY MID/LATE
SUNDAY MORNING WITH A SOMEWHAT BETTER CHANCE FOR SHOWERS AND
THUNDERSTORMS AT ALL TERMINALS SUNDAY AFTERNOON AND EVENING.
LOOKING AHEAD:
THE PROBABILITY FOR SHOWERS AND THUNDERSTORMS WILL FURTHER INCREASE
MON/MON NIGHT AT ALL TERMINALS...IN ASSOCIATION WITH STRENGTHENING
CYCLONIC FLOW ALOFT AND A COLD FRONT APPROACHING THE REGION FROM THE
NORTHWEST. THE FRONT IS EXPECTED TO PROGRESS SOUTHEAST ACROSS
CENTRAL NC DURING THE DAY TUE...WITH THE BEST CHANCE OF SHOWERS AND
THUNDERSTORMS SHIFTING TO THE EASTERN TERMINALS (RDU/FAY/RWI) BY TUE
AFTERNOON. ASIDE FROM A CHANCE FOR FOG NEAR AND JUST PRIOR TO
SUNRISE (08-12Z) WED/THU...EXPECT VFR CONDITIONS IN THE WAKE OF THE
FRONT AS HIGH PRESSURE BUILDS INTO THE REGION. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...VINCENT
LONG TERM...ELLIS
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
210 PM EDT SAT AUG 31 2013
.SYNOPSIS...
A WARM AND MOIST SOUTHERLY FLOW WILL PREVAIL THROUGH THE REST OF THE
WEEKEND. A COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST ON
MONDAY...THEN PUSH SLOWLY EAST THROUGH THE CAROLINAS ON TUESDAY. IN
THE WAKE OF THE FRONT...HIGH PRESSURE WILL BUILD INTO THE REGION ON
WEDNESDAY AND LINGER THROUGH THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 200 PM SATURDAY...
OVERVIEW:
LIGHT NW FLOW ALOFT WILL PREVAIL ACROSS THE REGION THROUGH
TONIGHT...IN A WEAKNESS BETWEEN AN UPSTREAM RIDGE OVER THE SOUTHERN
PLAINS/ROCKIES AND A DOWNSTREAM RIDGE OFFSHORE THE SOUTHEAST COAST.
17Z WV IMAGERY AND RAP DATA INDICATED SMALL AMPLITUDE DISTURBANCES
UPSTREAM ACROSS OH/KY/WV...TRACKING SOUTHEAST TOWARD THE MID-
ATLANTIC AND NORTHERN PORTIONS OF NC.
PRECIPITATION CHANCES:
THE LOW-LEVEL RIDGE EXTENDING WESTWARD INTO CENTRAL NC THIS MORNING
HAS FURTHER WEAKENED...GIVING WAY TO AN INCREASINGLY MOIST SOUTHERLY
RETURN FLOW FROM THE SFC-925 MB...WITH ADDITIONAL MOISTURE ADVECTING
INTO THE AREA FROM THE WEST/WNW AT H85. SEASONABLY STRONG INSOLATION
WILL RESULT IN MARGINAL TO MODERATE DIURNAL DESTABILIZATION BY PEAK
HEATING WITH MLCAPE VALUES RANGING FROM 1500-2000 J/KG IN THE
WESTERN PIEDMONT TO 500-1000 J/KG IN THE EAST WHERE THE LOW-LEVELS
ARE DRIER AS NOTED ABOVE. THE PRIMARY UNCERTAINTY W/REGARD TO
CONVECTION WILL BE FORCING. VERY LITTLE IF ANY LOW-LEVEL FORCING
WILL BE PRESENT THIS AFT/EVE WITH LARGELY UNIDIRECTIONAL SFC-925 MB
FLOW OVER CENTRAL NC. ADDITIONALLY...UPPER LEVEL FORCING /DPVA/ IS
EXPECTED TO REMAIN N/NW OF CENTRAL NC THIS AFT/EVE AS SMALL
AMPLITUDE DISTURBANCES TRACK SLOWLY E/ESE FROM THE OH VALLEY INTO
THE WV AND CENTRAL/WESTERN VA. AN MCV AND A ROBUST COLD POOL ASSOC/W
AN ONGOING MCS UPSTREAM OVER EASTERN KY AND SOUTHWEST VA AT 17Z IS
LIKELY TO TRACK SOUTHEASTWARD TOWARD NORTHWEST NC AND MAY PROVIDE
SUFFICIENT FORCING FOR CONVECTION TO DEVELOP IN THE NW PIEDMONT LATE
THIS AFT/EVE (22-04Z). WITH THE ABOVE IN MIND...WILL INDICATE PRECIP
CHANCES OF 20-30% WEST OF THE HWY 1 CORRIDOR WITH THE RELATIVE BEST
CHANCE IN THE TRIAD. EAST OF HWY 1...GIVEN A PROFOUND LACK OF
FORCING AND A DRIER LOW-LEVEL AIRMASS /MARGINAL DESTABILIZATION/...
WILL KEEP THE FCST DRY. CHANCES FOR CONVECTION WILL DECREASE BY
MIDNIGHT IN ASSOC/W INCREASING NOCTURNAL STABILIZATION...THOUGH IF
SMALL AMPLITUDE DISTURBANCES AND/OR THE AFOREMENTIONED MCV GRAZE OR
TRACK ACROSS NORTHERN PORTIONS OF CENTRAL NC THERE MAY BE SUFFICIENT
MOISTURE/INSTABILITY TO SUPPORT ISOLD CONVECTION OVERNIGHT...AND
THIS WILL BE THE BASIS FOR A 20% CHANCE OF SHOWERS NORTH OF HWY 64
AFTER MIDNIGHT.
TEMPERATURES:
EXPECT HIGHS TODAY SLIGHTLY ABOVE NORMAL...IN THE MID/UPPER 80S TO
NEAR 90F. LOWS TONIGHT A FEW DEGREES ABOVE NORMAL DUE TO INCREASING
LOW-LEVEL MOISTURE AND PERHAPS MID/UPPER LEVEL CLOUD COVER...IN THE
UPPER 60S TO NEAR 70F.
SEVERE POTENTIAL:
A VERY SMALL (ALBEIT CONDITIONAL) THREAT OF AN ISOLD SEVERE
DOWNBURST EXISTS IN THE FAR W/NW PIEDMONT LATE THIS AFT/EVE WHERE
MODERATE INSTABILITY (1500-2000 J/KG) AND MODERATE DCAPE (1000 J/KG)
ARE PRESENT IN ADVANCE OF THE MCS /COLD POOL/ APPROACHING THE
NORTHWEST NC MOUNTAINS. CONFIDENCE IS LOW WITH REGARD TO HOW THE
AFOREMENTIONED COLD POOL WILL EVOLVE AND WHETHER OR NOT IT WILL
AFFECT THE NW PIEDMONT IN VICINITY OF PEAK HEATING...AND HAVE OPTED
TO LEAVE OUT ANY MENTION OF SVR WX IN THE HWO. -VINCENT
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
AS OF 215 PM SATURDAY...
CYCLONIC FLOW ALOFT WILL STRENGTHEN ACROSS THE EASTERN CONUS AS
POTENT SHORTWAVE ENERGY TRACKING FROM SOUTHERN CANADA INTO THE UPPER
MIDWEST THIS AFTERNOON DIGS SOUTHEAST INTO THE UPPER GREAT LAKES ON
SUNDAY. AS A RESULT...A MOIST SOUTHWESTERLY LOW-LEVEL FLOW WILL
STRENGTHEN OVER THE CAROLINAS ON SUNDAY...WITH PWAT VALUES
INCREASING TO ABOVE NORMAL IN THE 1.75-2.00" RANGE AND DIURNAL
DESTABILIZATION YIELDING MARGINAL TO MODERATE INSTABILITY (1000-2000
J/KG MLCAPE) DURING PEAK HEATING. LOW-LEVEL FORCING ON SUNDAY WILL
BE ANEMIC ONCE AGAIN WITH LARGELY UNIDIRECTIONAL LOW-LEVEL FLOW...
THOUGH WITH STRONGER CYCLONIC FLOW ALOFT AND DEEPER MOISTURE ONE
WOULD EXPECT PRECIP CHANCES HIGHER THAN TODAY. ULTIMATELY...PRECIP
CHANCES WILL LIKELY DEPEND ON UPSTREAM DEVELOPMENT ACROSS THE HIGHER
TERRAIN IN WESTERN NC AND/OR THE TIMING OF SMALL AMPLITUDE
DISTURBANCES EMBEDDED IN CYCLONIC FLOW ALOFT. WILL INDICATE A 30-40%
CHANCE OF SHOWERS/STORMS SUNDAY AFT/EVE...HIGHEST IN NORTHERN
PORTIONS OF THE AREA...WITH A SLIGHT CHANCE OF SHOWERS PERSISTING
AFTER MIDNIGHT GIVEN CYCLONIC FLOW ALOFT AND DEEP MOISTURE IN THE
PRESENCE OF MARGINAL INSTABILITY. HIGHS ON SUN SIMILAR TO TODAY...
PERHAPS SLIGHTLY WARMER IF CLOUD COVER IS NOT PERVASIVE DURING THE
AFTERNOON...IN THE UPPER 80S TO NEAR 90F...WARMEST IN THE SANDHILLS
AND COASTAL PLAIN. LOWS SUN NIGHT A FEW DEGREES ABOVE NORMAL DUE TO
CLOUD COVER AND DEEP MOISTURE...IN THE LOWER 70S. -VINCENT
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 255 AM SATURDAY...
THE LONG TERM PERIOD OF THE FORECAST FEATURES A PERSISTENT RIDGE OF
HIGH PRESSURE ACROSS THE SOUTHERN ROCKIES AND AN EASTERN U.S. TROUGH
THAT INITIALLY AMPLIFIES EARLY IN THE WORK WEEK AND THEN DEAMPLIFIES
TOWARD THE END OF THE PERIOD.
ON MONDAY A COUPLE OF SHORT WAVE TROUGHS IN SERIES OF DISTURBANCES
MOVING THROUGH THE DEEPENING EASTERN U.S. TROUGH WILL MOVE ACROSS
THE REGION. THE AIR MASS ACROSS CENTRAL NC WILL BE MOIST WITH
PRECIPITABLE WATER VALUES JUST UNDER 2.0 INCHES. THE AIRMASS WILL
ALSO BE WEAKLY TO MODERATELY UNSTABLE. THIS SHOULD SUPPORT FAIRLY
GOOD CHANCES AND COVERAGE OF PRECIPITATION ON MONDAY AND MONDAY
NIGHT. WHILE CONVECTIVE ORGANIZATION IS LIKELY TO BE LIMITED GIVEN
BULK SHEAR VALUES IN THE 15-20KT RANGE...WEAK TO MODERATE
INSTABILITY AND WEAK FLOW WILL SUPPORT THE POTENTIAL FOR SLOW
MOVING THUNDERSTORMS WITH HEAVY RAIN AND POTENTIALLY GUSTY WINDS.
NAM/GFS GUIDANCE DIFFER ON MONDAY MAX TEMPERATURES BY 3-4 DEGREES IN
MOST LOCATIONS WITH THE GFS WARMER THAN THE NAM WHICH IS NOT
SURPRISING AS THE GFS LOW LEVEL THICKNESS VALUES ON MONDAY THAT ARE
10-15M LARGER. NOT READY TO JUMP ON THE LIKELY OVERDONE TEMPS FROM
THE GFS GIVEN CLOUDINESS AND POTENTIAL FOR PRECIPITATION AND WILL
FORECAST HIGHS IN THE 88-92 RANGE. IT WILL BE WARM AND MUGGY MONDAY
NIGHT WITH LOWS ONLY IN THE 69-73 RANGE.
ANOTHER SHORT WAVE TROUGH...THIS WAS ASSOCIATED WITH THE SURFACE
COLD FRONT WILL MOVE ACROSS OUR REGION TUESDAY AFTERNOON AND
EVENING. GUIDANCE IS BEGINNING TO SHOW A WEAK SURFACE WAVE MAY
DEVELOP ACROSS CENTRAL NC ON THE FRONT TUESDAY AFTERNOON AND
EVENING. EXPECT FAIRLY GOOD COVERAGE OF SHOWERS AND THUNDERSTORMS ON
TUESDAY WITH THE BEST COVERAGE EXPECTED ACROSS THE EASTERN PIEDMONT
AND COASTAL PLAIN AHEAD OF THE SURFACE WAVE AND IN A REGION OF
GREATER INSTABILITY. IT WILL BE A LITTLE COOLER ON TUESDAY WITH
HIGHS RANGING FROM THE MID 80S ACROSS THE WESTERN PIEDMONT TO THE
UPPER 80S ACROSS THE COASTAL PLAIN. LOWS TUESDAY NIGHT WILL RANGE
FROM THE LOW 60S ACROSS THE NORTHWEST PIEDMONT TO THE UPPER 60S IN
THE SOUTHERN COASTAL PLAIN.
THE FRONT WILL CONTINUE TO SHIFT SOUTH OF CENTRAL NC ON WEDNESDAY
BUT A FEW SHOWERS MAY LINGER INTO EARLY WEDNESDAY ACROSS THE
SOUTHERN COASTAL PLAIN AND SANDHILLS. OTHERWISE HIGH PRESSURE WILL
BUILD INTO THE REGION ON WEDNESDAY AND THURSDAY WITH GENERALLY FAIR
WEATHER AND SEASONABLE TEMPERATURES. A COLD FRONT WILL PUSH SOUTH
ACROSS THE MID ATLANTIC LATE THURSDAY AND EARLY FRIDAY BRINGING
ADDITIONAL CLOUDINESS AND EVEN COOLER TEMPERATURES. PRECIPITATION
CHANCES APPEAR LIMITED ACROSS CENTRAL NC WITH THIS FEATURE. HIGH
TEMPERATURES WILL RANGE IN THE LOWER TO MID 80S WITH FRIDAY BEING
THE COOLEST DAY. MORNING LOWS SHOULD RANGE IN THE LOWER TO MID 60S.
-BLAES
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AS OF 115 PM SATURDAY...
24-HR TAF PERIOD:
VFR CONDITIONS WILL LARGELY PREVAIL THROUGH MIDNIGHT WITH CEILINGS
RANGING FROM 3000-5000 FT AGL...THOUGH IT IS POSSIBLE THAT THE
INT/GSO TERMINALS COULD SEE SUB-VFR CONDITIONS IN ASSOCIATION WITH
ISOLD SHOWERS AND THUNDERSTORMS...PRIMARILY BETWEEN 20-03Z.
SOUTHWEST WINDS AT 5-10 KT WILL WEAKEN TO 5 KT OR LESS OVERNIGHT. A
PERIOD OF SUB-VFR FOG OR CEILINGS WILL BE POSSIBLE EARLY SUNDAY
MORNING IN ASSOCIATION WITH LOW-LEVEL WARM ADVECTION...PRIMARILY
BETWEEN 08-13Z. AT THIS TIME...WILL ACCOUNT FOR THE FOG/STRATUS
POTENTIAL BY ADDING A TEMPO GROUP /5SM BR BKN010/ FOR 08-12Z AT ALL
TERMINALS. EXPECT SOUTHWEST WINDS INCREASING TO ~10 KT BY MID/LATE
SUNDAY MORNING WITH A SOMEWHAT BETTER CHANCE FOR SHOWERS AND
THUNDERSTORMS AT ALL TERMINALS SUNDAY AFTERNOON AND EVENING.
LOOKING AHEAD:
THE PROBABILITY FOR SHOWERS AND THUNDERSTORMS WILL FURTHER INCREASE
MON/MON NIGHT AT ALL TERMINALS...IN ASSOCIATION WITH STRENGTHENING
CYCLONIC FLOW ALOFT AND A COLD FRONT APPROACHING THE REGION FROM THE
NORTHWEST. THE FRONT IS EXPECTED TO PROGRESS SOUTHEAST ACROSS
CENTRAL NC DURING THE DAY TUE...WITH THE BEST CHANCE OF SHOWERS AND
THUNDERSTORMS SHIFTING TO THE EASTERN TERMINALS (RDU/FAY/RWI) BY TUE
AFTERNOON. ASIDE FROM A CHANCE FOR FOG NEAR AND JUST PRIOR TO
SUNRISE (08-12Z) WED/THU...EXPECT VFR CONDITIONS IN THE WAKE OF THE
FRONT AS HIGH PRESSURE BUILDS INTO THE REGION. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...VINCENT
LONG TERM...BLAES
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
156 PM EDT SAT AUG 31 2013
.SYNOPSIS...
A WARM AND MOIST SOUTHERLY FLOW WILL PREVAIL THROUGH THE REST OF THE
WEEKEND. A COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST ON
MONDAY...THEN PUSH SLOWLY EAST THROUGH THE CAROLINAS ON TUESDAY. IN
THE WAKE OF THE FRONT...HIGH PRESSURE WILL BUILD INTO THE REGION ON
WEDNESDAY AND LINGER THROUGH THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 200 PM SATURDAY...
OVERVIEW:
LIGHT NW FLOW ALOFT WILL PREVAIL ACROSS THE REGION THROUGH
TONIGHT...IN A WEAKNESS BETWEEN AN UPSTREAM RIDGE OVER THE SOUTHERN
PLAINS/ROCKIES AND A DOWNSTREAM RIDGE OFFSHORE THE SOUTHEAST COAST.
17Z WV IMAGERY AND RAP DATA INDICATED SMALL AMPLITUDE DISTURBANCES
UPSTREAM ACROSS OH/KY/WV...TRACKING SOUTHEAST TOWARD THE MID-
ATLANTIC AND NORTHERN PORTIONS OF NC.
PRECIPITATION CHANCES:
THE LOW-LEVEL RIDGE EXTENDING WESTWARD INTO CENTRAL NC THIS MORNING
HAS FURTHER WEAKENED...GIVING WAY TO AN INCREASINGLY MOIST SOUTHERLY
RETURN FLOW FROM THE SFC-925 MB...WITH ADDITIONAL MOISTURE ADVECTING
INTO THE AREA FROM THE WEST/WNW AT H85. SEASONABLY STRONG INSOLATION
WILL RESULT IN MARGINAL TO MODERATE DIURNAL DESTABILIZATION BY PEAK
HEATING WITH MLCAPE VALUES RANGING FROM 1500-2000 J/KG IN THE
WESTERN PIEDMONT TO 500-1000 J/KG IN THE EAST WHERE THE LOW-LEVELS
ARE DRIER AS NOTED ABOVE. THE PRIMARY UNCERTAINTY W/REGARD TO
CONVECTION WILL BE FORCING. VERY LITTLE IF ANY LOW-LEVEL FORCING
WILL BE PRESENT THIS AFT/EVE WITH LARGELY UNIDIRECTIONAL SFC-925 MB
FLOW OVER CENTRAL NC. ADDITIONALLY...UPPER LEVEL FORCING /DPVA/ IS
EXPECTED TO REMAIN N/NW OF CENTRAL NC THIS AFT/EVE AS SMALL
AMPLITUDE DISTURBANCES TRACK SLOWLY E/ESE FROM THE OH VALLEY INTO
THE WV AND CENTRAL/WESTERN VA. AN MCV AND A ROBUST COLD POOL ASSOC/W
AN ONGOING MCS UPSTREAM OVER EASTERN KY AND SOUTHWEST VA AT 17Z IS
LIKELY TO TRACK SOUTHEASTWARD TOWARD NORTHWEST NC AND MAY PROVIDE
SUFFICIENT FORCING FOR CONVECTION TO DEVELOP IN THE NW PIEDMONT LATE
THIS AFT/EVE (22-04Z). WITH THE ABOVE IN MIND...WILL INDICATE PRECIP
CHANCES OF 20-30% WEST OF THE HWY 1 CORRIDOR WITH THE RELATIVE BEST
CHANCE IN THE TRIAD. EAST OF HWY 1...GIVEN A PROFOUND LACK OF
FORCING AND A DRIER LOW-LEVEL AIRMASS /MARGINAL DESTABILIZATION/...
WILL KEEP THE FCST DRY. CHANCES FOR CONVECTION WILL DECREASE BY
MIDNIGHT IN ASSOC/W INCREASING NOCTURNAL STABILIZATION...THOUGH IF
SMALL AMPLITUDE DISTURBANCES AND/OR THE AFOREMENTIONED MCV GRAZE OR
TRACK ACROSS NORTHERN PORTIONS OF CENTRAL NC THERE MAY BE SUFFICIENT
MOISTURE/INSTABILITY TO SUPPORT ISOLD CONVECTION OVERNIGHT...AND
THIS WILL BE THE BASIS FOR A 20% CHANCE OF SHOWERS NORTH OF HWY 64
AFTER MIDNIGHT.
TEMPERATURES:
EXPECT HIGHS TODAY SLIGHTLY ABOVE NORMAL...IN THE MID/UPPER 80S TO
NEAR 90F. LOWS TONIGHT A FEW DEGREES ABOVE NORMAL DUE TO INCREASING
LOW-LEVEL MOISTURE AND PERHAPS MID/UPPER LEVEL CLOUD COVER...IN THE
UPPER 60S TO NEAR 70F.
SEVERE POTENTIAL:
A VERY SMALL (ALBEIT CONDITIONAL) THREAT OF AN ISOLD SEVERE
DOWNBURST EXISTS IN THE FAR W/NW PIEDMONT LATE THIS AFT/EVE WHERE
MODERATE INSTABILITY (1500-2000 J/KG) AND MODERATE DCAPE (1000 J/KG)
ARE PRESENT IN ADVANCE OF THE MCS /COLD POOL/ APPROACHING THE
NORTHWEST NC MOUNTAINS. CONFIDENCE IS LOW WITH REGARD TO HOW THE
AFOREMENTIONED COLD POOL WILL EVOLVE AND WHETHER OR NOT IT WILL
AFFECT THE NW PIEDMONT IN VICINITY OF PEAK HEATING...AND HAVE OPTED
TO LEAVE OUT ANY MENTION OF SVR WX IN THE HWO. -VINCENT
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
AS OF 305 AM SATURDAY...
SHOWER/STORM CHANCES AND COVERAGE APPEAR TO RISE FOR SUNDAY/SUNDAY
NIGHT... AS ENERGY FROM CONVECTION NOW OVER THE MIDWEST ALONG WITH A
STRONGER WAVE DROPPING THROUGH SW/S-CENTRAL CANADA THIS MORNING
HELPS TO SUBSTANTIALLY DEEPEN THE EASTERN CONUS MEAN TROUGH. DEEP
MOISTURE PERSISTS OVER CENTRAL NC WITH PREDICTED PW VALUES NEAR 2.0
INCHES... WELL ABOVE NORMAL... WITH STRENGTHENING LOW LEVEL MOISTURE
TRANSPORT. MODELS INDICATE INCREASING ASCENT AND MOISTURE FLUX
THROUGH THE COLUMN... AND IMPROVING INSTABILITY (MLCAPE OF 1000-2000
J/KG AREA WIDE WITH N-CAPE NEAR 0.15) WITH AT LEAST WEAK DPVA AND
INCREASINGLY CYCLONIC FLOW ALOFT DOES SUPPORT SCATTERED SHOWERS AND
STORMS OVER ALL OF CENTRAL NC. DEEP LAYER SHEAR REMAINS POOR AT 15
KTS OR LESS... SO DO NOT EXPECT A LOT OF STRONG AND/OR ORGANIZED
CONVECTION... BUT COVERAGE SHOULD BE A BIT BETTER IN THE NW WHERE
THE BULK SHEAR WILL BE MAXIMIZED. HIGHS 86-91. LOWS 68-72 WITH
GRADUALLY DECREASING SHOWER/STORM CHANCES WITH LOSS OF HEATING. -GIH
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 255 AM SATURDAY...
THE LONG TERM PERIOD OF THE FORECAST FEATURES A PERSISTENT RIDGE OF
HIGH PRESSURE ACROSS THE SOUTHERN ROCKIES AND AN EASTERN U.S. TROUGH
THAT INITIALLY AMPLIFIES EARLY IN THE WORK WEEK AND THEN DEAMPLIFIES
TOWARD THE END OF THE PERIOD.
ON MONDAY A COUPLE OF SHORT WAVE TROUGHS IN SERIES OF DISTURBANCES
MOVING THROUGH THE DEEPENING EASTERN U.S. TROUGH WILL MOVE ACROSS
THE REGION. THE AIR MASS ACROSS CENTRAL NC WILL BE MOIST WITH
PRECIPITABLE WATER VALUES JUST UNDER 2.0 INCHES. THE AIRMASS WILL
ALSO BE WEAKLY TO MODERATELY UNSTABLE. THIS SHOULD SUPPORT FAIRLY
GOOD CHANCES AND COVERAGE OF PRECIPITATION ON MONDAY AND MONDAY
NIGHT. WHILE CONVECTIVE ORGANIZATION IS LIKELY TO BE LIMITED GIVEN
BULK SHEAR VALUES IN THE 15-20KT RANGE...WEAK TO MODERATE
INSTABILITY AND WEAK FLOW WILL SUPPORT THE POTENTIAL FOR SLOW
MOVING THUNDERSTORMS WITH HEAVY RAIN AND POTENTIALLY GUSTY WINDS.
NAM/GFS GUIDANCE DIFFER ON MONDAY MAX TEMPERATURES BY 3-4 DEGREES IN
MOST LOCATIONS WITH THE GFS WARMER THAN THE NAM WHICH IS NOT
SURPRISING AS THE GFS LOW LEVEL THICKNESS VALUES ON MONDAY THAT ARE
10-15M LARGER. NOT READY TO JUMP ON THE LIKELY OVERDONE TEMPS FROM
THE GFS GIVEN CLOUDINESS AND POTENTIAL FOR PRECIPITATION AND WILL
FORECAST HIGHS IN THE 88-92 RANGE. IT WILL BE WARM AND MUGGY MONDAY
NIGHT WITH LOWS ONLY IN THE 69-73 RANGE.
ANOTHER SHORT WAVE TROUGH...THIS WAS ASSOCIATED WITH THE SURFACE
COLD FRONT WILL MOVE ACROSS OUR REGION TUESDAY AFTERNOON AND
EVENING. GUIDANCE IS BEGINNING TO SHOW A WEAK SURFACE WAVE MAY
DEVELOP ACROSS CENTRAL NC ON THE FRONT TUESDAY AFTERNOON AND
EVENING. EXPECT FAIRLY GOOD COVERAGE OF SHOWERS AND THUNDERSTORMS ON
TUESDAY WITH THE BEST COVERAGE EXPECTED ACROSS THE EASTERN PIEDMONT
AND COASTAL PLAIN AHEAD OF THE SURFACE WAVE AND IN A REGION OF
GREATER INSTABILITY. IT WILL BE A LITTLE COOLER ON TUESDAY WITH
HIGHS RANGING FROM THE MID 80S ACROSS THE WESTERN PIEDMONT TO THE
UPPER 80S ACROSS THE COASTAL PLAIN. LOWS TUESDAY NIGHT WILL RANGE
FROM THE LOW 60S ACROSS THE NORTHWEST PIEDMONT TO THE UPPER 60S IN
THE SOUTHERN COASTAL PLAIN.
THE FRONT WILL CONTINUE TO SHIFT SOUTH OF CENTRAL NC ON WEDNESDAY
BUT A FEW SHOWERS MAY LINGER INTO EARLY WEDNESDAY ACROSS THE
SOUTHERN COASTAL PLAIN AND SANDHILLS. OTHERWISE HIGH PRESSURE WILL
BUILD INTO THE REGION ON WEDNESDAY AND THURSDAY WITH GENERALLY FAIR
WEATHER AND SEASONABLE TEMPERATURES. A COLD FRONT WILL PUSH SOUTH
ACROSS THE MID ATLANTIC LATE THURSDAY AND EARLY FRIDAY BRINGING
ADDITIONAL CLOUDINESS AND EVEN COOLER TEMPERATURES. PRECIPITATION
CHANCES APPEAR LIMITED ACROSS CENTRAL NC WITH THIS FEATURE. HIGH
TEMPERATURES WILL RANGE IN THE LOWER TO MID 80S WITH FRIDAY BEING
THE COOLEST DAY. MORNING LOWS SHOULD RANGE IN THE LOWER TO MID 60S.
-BLAES
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AS OF 115 PM SATURDAY...
24-HR TAF PERIOD:
VFR CONDITIONS WILL LARGELY PREVAIL THROUGH MIDNIGHT WITH CEILINGS
RANGING FROM 3000-5000 FT AGL...THOUGH IT IS POSSIBLE THAT THE
INT/GSO TERMINALS COULD SEE SUB-VFR CONDITIONS IN ASSOCIATION WITH
ISOLD SHOWERS AND THUNDERSTORMS...PRIMARILY BETWEEN 20-03Z.
SOUTHWEST WINDS AT 5-10 KT WILL WEAKEN TO 5 KT OR LESS OVERNIGHT. A
PERIOD OF SUB-VFR FOG OR CEILINGS WILL BE POSSIBLE EARLY SUNDAY
MORNING IN ASSOCIATION WITH LOW-LEVEL WARM ADVECTION...PRIMARILY
BETWEEN 08-13Z. AT THIS TIME...WILL ACCOUNT FOR THE FOG/STRATUS
POTENTIAL BY ADDING A TEMPO GROUP /5SM BR BKN010/ FOR 08-12Z AT ALL
TERMINALS. EXPECT SOUTHWEST WINDS INCREASING TO ~10 KT BY MID/LATE
SUNDAY MORNING WITH A SOMEWHAT BETTER CHANCE FOR SHOWERS AND
THUNDERSTORMS AT ALL TERMINALS SUNDAY AFTERNOON AND EVENING.
LOOKING AHEAD:
THE PROBABILITY FOR SHOWERS AND THUNDERSTORMS WILL FURTHER INCREASE
MON/MON NIGHT AT ALL TERMINALS...IN ASSOCIATION WITH STRENGTHENING
CYCLONIC FLOW ALOFT AND A COLD FRONT APPROACHING THE REGION FROM THE
NORTHWEST. THE FRONT IS EXPECTED TO PROGRESS SOUTHEAST ACROSS
CENTRAL NC DURING THE DAY TUE...WITH THE BEST CHANCE OF SHOWERS AND
THUNDERSTORMS SHIFTING TO THE EASTERN TERMINALS (RDU/FAY/RWI) BY TUE
AFTERNOON. ASIDE FROM A CHANCE FOR FOG NEAR AND JUST PRIOR TO
SUNRISE (08-12Z) WED/THU...EXPECT VFR CONDITIONS IN THE WAKE OF THE
FRONT AS HIGH PRESSURE BUILDS INTO THE REGION. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...HARTFIELD
LONG TERM...BLAES
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
325 PM CDT SAT AUG 31 2013
.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 325 PM CDT SAT AUG 31 2013
MAIN FORECAST CONCERNS THIS PACKAGE...SHRA/TSRA CHANCES TONIGHT INTO
SUN...TEMPERATURES.
AT 18Z...WEAK HIGH PRESSURE WAS CENTERED OVER NORTHERN LOWER MI WITH
RIDGING SOUTHWEST INTO NORTHERN IA. LOW PRESSURE WAS OVER SOUTHEAST
MANITOBA WITH A TRAILING COLD FRONT INTO THE EASTERN DAKOTAS.
CONVECTION SLOWLY DEVELOPING ALONG THIS FRONT EARLY THIS AFTERNOON.
SHALLOW LOWER LEVEL MOISTURE/STRATO-CU TRAPPED UNDER AN INVERSION
NEAR 900MB CONTINUED TO PLAGUE SOUTHERN WI/SOUTHEAST MN/EASTERN IA...
BUT CONTINUED TO SLOWLY DISSIPATING WITH DIURNAL WARMING/MIXING AS OF
MID-DAY. MORE COMFORTABLE DAY ACROSS MUCH OF MN/IA/WI...WITH SFC DEW
POINTS IN THE 60S AND TEMPS IN THE MID 70S TO MID 80S.
FOR THE MOST PART...31.12Z MODELS INITIALIZED WELL. GFS WITH ITS
USUAL QUIRKY SFC DEW POINT ANALYSIS OVER THE MID/UPPER MS VALLEY
BUT NAM 850-500MB HGTS DO NOT PROVIDE THE BEST FIT TO THE RA-OBS
HGTS ACROSS MUCH OF CENTRAL NOAM THIS CYCLE. NAM WITH TOO MUCH 850-
500MB SHORTWAVE TROUGHING OVER NORTHEAST MT PER THE GLASGOW MT
RA-OB. DESPITE THIS...SOLUTIONS REMAIN QUITE SIMILAR FOR TONIGHT
THRU SUN NIGHT AS THE SOUTHERN SASKAT SHORTWAVE DROPS SOUTHEAST
ACROSS THE AREA AND INTO THE CENTRAL GREAT LAKES BY 12Z MON.
DPROG/DT OF 500MB HGTS AT 31.12Z SHOWED THE MODEL RUNS OF 29.12Z
AND VERIFIED WELL ACROSS NOAM/EASTERN PAC WITH BETTER RUN-TO-RUN
CONSISTENCY TO ECMWF. TREND THRU TONIGHT/SUN FAVORS FASTER OF AS
THE TROUGH DROPS ACROSS THE REGION THEN FAVORS A TIGHTENING
COMPROMISE OF THE EARLIER RUNS WITH THE TROUGH INTO THE CENTRAL
LAKES SUN NIGHT. CHECK OF OBS VS. MODEL DATA AT 18Z SHOWED ALL TO BE
REASONABLE WITH THE SOUTHEAST MAN LOW/EASTERN DAKOTAS COLD FRONT. GFS
REMAINED ON THE DRY SIDE WITH SFC DEW POINTS OVER THE MID/UPPER MS
VALLEY. PER WV IMAGERY...ECMWF/GFS/GEM APPEARED BETTER THAN NAM WITH
THE STRENGTH/ POSITION OF THE SOUTHEAST SASKAT SHORTWAVE. GIVEN THIS
AND THE INITIALIZATIONS...FAVORED A NON-NAM CONSENSUS OF THE MODELS
FOR TONIGHT THRU SUN NIGHT. SHORT TERM CONFIDENCE REMAINS ABOVE
AVERAGE.
IN THE SHORT TERM...MAIN SHORTWAVE AND MID/UPPER LEVEL DYNAMICS/LIFT
WITH IT TO PASS TO NORTH OF OR ACROSS THE NORTH END OF THE FCST
TONIGHT/EARLY SUNDAY. MAIN LOWER LEVEL THERMO-DYNAMIC FORCING WITH
THE COLD FRONT PEAKS AROUND 00Z THIS EVENING...THEN GRADUALLY
WEAKENS AS IT COMES EAST AND CROSSES THE FCST AREA LATER THIS
EVENING THRU SUN MORNING. MU CAPE OF 2K-3K J/KG COINCIDENT WITH THE
FRONT/THERMO-DYNAMIC FORCING EARLY THIS EVENING WANES AS WELL AS THE
FRONT/FORCING/LIFT APPROACH/CROSS THE FCST AREA. PW VALUES STILL
PROGGED TO BE AROUND 1.5 INCHES AHEAD OF THE FRONT TONIGHT. RATHER
CONTINUOUS LINE OF CONVECTION EXPECTED TO BE IN PROGRESS FROM NORTH-
CENTRAL MN TO EASTERN SD EARLY THIS EVENING...GRADUALLY WEAKENING/
BECOMING MORE SCT/BKN OVERNIGHT AS IT MOVES INTO ACROSS THE FCST
AREA. CARRIED HIGHEST SHRA/TSRA CHANCES DURING THE LATE EVENING
OVER THE NORTHWEST END OF THE FCST AREA WHEN/WHERE THE LINE OF
CONVECTION WOULD STILL HAVE MORE INSTABILITY/FORCING/LIFT TO WORK
WITH. CONTINUED/TRENDED SHRA/TSRA CHANCES MORE IN THE 20-40 PERCENT
RANGE AFTER MIDNIGHT/SUN MORNING WITH LESS INSTABILITY/FORCING. WITH
THE FASTER MOVEMENT OF THE MID LEVEL TROUGH...TRENDED SHRA/TSRA
CHANCES DOWN/OUT OF THE FCST AREA MORE QUICKLY SUN AFTERNOON.
QUESTION FOR SUN AFTERNOON ONCE THE FRONT/FORCING ARE EAST OF THE
AREA IS EXTENT OF CLOUDS WITH SOME 925-850MB MOISTURE WRAPPING AROUND
THE SFC-MID LEVEL LOW IN DEEP CYCLONIC FLOW...ESPECIALLY OVER THE
NORTH/EAST PORTIONS OF THE FCST AREA. INCREASED CLOUD COVER FOR SUN
AFTERNOON THESE AREAS. CLEARING SUN NIGHT AS THE MID LEVEL LOW
QUICKLY PULLS AWAY AND LOWER LEVEL ANTICYCLONIC FLOW/HIGH PRESSURE
BUILDS INTO THE AREA. 925MB TEMPS IN THE 10C-13C RANGE BY 12Z MON...
FOR COOLER...MORE NEAR NORMAL LOWS MON MORNING. USED A BLEND OF THE
NUMERICAL GUIDANCE LOWS/HIGHS FOR TONIGHT THRU SUN NIGHT.
.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 325 PM CDT SAT AUG 31 2013
MAIN FORECAST CONCERNS FOR MON THRU TUE NIGHT...FOG POTENTIAL
CENTERED ON DAYBREAK TUE...TEMPERATURES THRU THE PERIOD.
MODELS REMAIN IN GOOD AGREEMENT MON THRU TUE NIGHT AS THE TROUGH
PROGRESSES INTO THE EASTERN CONUS...HGTS RISE AND SHORTWAVE RIDGING
BUILDS INTO THE UPPER MIDWEST. FCST CONFIDENCE IN THIS PERIOD IS
GOOD.
THE CENTER OF THE CANADIAN HIGH DRIFTS FROM NORTHERN MN MON MORNING
TO IL/IN BY WED MORNING. A WEAKENING COLD FRONT SLIDES INTO NORTHERN
WI/CENTRAL MN BY WED MORNING...BUT LIMITED MOISTURE AND MINIMAL
INSTABILITY AHEAD OF IT. THE MON-TUE NIGHT PERIOD CONTINUES TO TREND
DRY/QUIET WITH COOLER/MORE SEASONABLE TEMPS. MONDAY STILL APPEARS AS
THE COOLEST DAY WITH SLOWLY MODERATING TEMPS TUE. COOLEST 925MB OVER
THE AREA AROUND 12Z MON...BUT SOME NORTH GRADIENTS TO KEEP THE
BOUNDARY LAYER STIRRED AND LOWS MON MORNING MOSTLY IN THE 50S. MON
NIGHT THE CENTER OF THE HIGH DRIFTS OVERHEAD WITH LIGHT WINDS/CLEAR
SKIES. 925MB TEMPS TUE MORNING IN THE 12C-15C RANGE...BUT THE
LIGHT/CALM WINDS AND STRONG RADIATIONAL COOLING LOOK TO MAKE TUE
MORNING THE COOLER OF THE MORNINGS...WITH LOWS IN THE MID 40S TO LOW
50S. RADIATIONAL LATE NIGHT/EARLY MORNING VALLEY FOG REMAINS A
CONCERN CENTERED ON 12Z TUE. PREVIOUS FCST GRID SET ALREADY INCLUDED
THIS AND APPEARS WELL TRENDED. USED A BLEND OF THE NUMERICAL
GUIDANCE HIGHS/LOWS FOR MON...TUE/TUE NIGHT. TRENDED TOWARD COOLER
OF GUIDANCE LOWS MON NIGHT WITH THE HIGH OVERHEAD.
FOR WEDNESDAY THROUGH SATURDAY.../DAYS 4-7/...
MEDIUM RANGE MODEL COMING INTO BETTER AGREEMENT WITH A SHORTWAVE TO
DROP SOUTHEAST ACROSS THE EASTERN GREAT LAKES WED...KEEPING THE
REGION UNDER NORTHWEST FLOW ALOFT AND THE RIDGE AXIS OVER THE WESTERN
PLAINS INTO ALB/SASKAT. PATTERN SLOWLY PROGRESSES THU-SAT WITH
RISING HGTS OVER THE UPPER MIDWEST...WHILE THE TROUGHING MOVING
ACROSS THE NORTHERN ROCKIES DEVELOP STRONGER LEE TROUGHING BY LATE
IN THE WEEK. DAY 4-7 FCST CONFIDENCE IS AVERAGE.
IMPROVING MODEL CONSENSUS MOVES A COLD FRONT INTO THE AREA ON WED...
DURING PEAK HEATING. MOISTURE REMAINS IN QUESTION...BUT TREND IS
TOWARD MORE OF AN 850-700MB MOISTURE TRANSPORT/THETA-E CONVERGENCE
SIGNAL...WITH INCREASING PW VALUES INTO THE AREA. MAY YET NEED A
SMALL SHRA/TSRA CHANCE CENTERED ON WED AFTERNOON/EVENING BUT LEFT
THESE PERIODS DRY FOR NOW. POST-FRONTAL CAN HIGH PRESSURE TO
SETTLE ACROSS THE REGION FOR THU. MIXED SIGNALS BY FRI/SAT WITH THE
STRENGTHENING LEE TROUGHING AND SOUTHWEST FLOW AHEAD OF IT PUSHING
INCREASING MOISTURE/INSTABILITY INTO THE UPPER MIDWEST. MAY YET NEED
SHRA/TSRA CHANCES FRI/SAT...DEPENDING ON WHERE ANY LOWER LEVEL
THERMAL/MOISTURE RIDGING AND LOWER LEVEL TOUGHS/BOUNDARIES MAY END
UP. LEFT THU NIGHT THRU SAT DRY FOR NOW PER THE MODEL/ENSEMBLE
CONSENSUS. A WARM-UP ON WED AHEAD OF THE FRONT THEN A BIT OF A COOL-
DOWN ON THU BEHIND THE FRONT...TEMPS GRADUALLY WARM FRI/SAT WITH THE
LOWER LEVEL FLOW BECOMING SOUTH/SOUTHWEST AND THE RISING HGTS ALOFT.
USED THE MODEL/ENSEMBLE CONSENSUS OF NUMERICAL GUIDANCE FOR HIGHS/
LOWS ON WED THRU SAT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1155 AM CDT SAT AUG 31 2013
ITS TAKING AWHILE FOR MORNING MVFR CIGS TO LIFT/BURN OFF...BUT OBS
AND SATELLITE TRENDS SHOWING HOLES AND AN INCREASE IN THE DECKS.
EXPECT MOSTLY SCT CONDITIONS BY 19Z...WITH VFR INTO THE EVENING
HOURS.
LINE OF SHRA/TS WILL BE APPROACHING FROM THE NORTHWEST THIS
EVENING...STRONG/SEVERE. HOWEVER...THEY SHOULD BE ON A WEAKENING
TREND AS THEY NEAR KRST/KLSE AS INSTABILITY WANES AND THE STRONGER
FORCING HOLDS TO THE NORTH. SOME MODELS SUGGEST THAT MUCH OF THE
PCPN MAY FALL APART BY THE TIME IT REACHES WESTERN WI.
MEANWHILE...LAST FEW RUNS OF THE HRRR TREND TOWARD HOLDING IT
TOGETHER THROUGH AT LEAST KRST. THINK THIS IS MORE LIKELY AND WILL
TREND THE TAFS THIS WAY. WILL HOLD WITH VCSH AT KLSE FOR THE TIME
BEING. NOT A LOT OF SATURATION PER BUFKIT SOUNDINGS...SO WILL HOLD
WITH VFR CONDITIONS.
FRONTAL PASSAGE NEAR OR SHORTLY AFTER 12Z SUN...WITH RH FIELDS THEN
POINTING TO SOME THREAT OF MVFR/IFR CIGS. LATEST SATELLITE/SFC OBS
DOES SUPPORT THIS WITH EXPANSIVE LOW CLOUD SHIELD WEST OF A SFC LOW.
THE LOW STAYS WELL NORTH OVERNIGHT/SUN...BUT THIS CLOUD SHIELD COULD
SINK SOUTH EARLY SUN MORNING...BRINGING A SHORT PERIOD OF MVFR CIGS.
GOING TO TREND TOWARD THIS FOR NOW.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RRS
LONG TERM....RRS
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1224 PM CDT SAT AUG 31 2013
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND SUNDAY
ISSUED AT 432 AM CDT SAT AUG 31 2013
MAIN CONCERNS THIS PERIOD ON SKY TRENDS EARLY...THEN PCPN CHANCES
WITH EXPECTED FRONTAL PASSAGE.
OVERALL NO REAL CHANGE TO FORECAST. MODELS CONTINUE TO BE IN GOOD
AGREEMENT WITH SOME MINOR TIMING DIFFERENCES WITH FRONT. GFS AND
00Z ECMWF HAD FAIRLY GOOD HANDLE ON CURRENT PCPN TRENDS SO
FOLLOWED FOR MUCH OF THIS FORECAST.
LATEST MSAS ANALYSIS SHOWS WEAK HIGH PRESSURE OVER STATE...WITH
WEAK WAVE MOVING ALONG FRONT OVER NORTHERN IL. FURTHER TO THE
WEST..COLD FRONT EXTENDS SOUTHWEST THROUGH WESTERN DAKOTAS FROM
LOW OVER LAKE WINNEPEG AREA. SATELLITE IMAGERY SHOWING LOW CLOUDS
EXPANDING WESTWARD OFF LAKE AND BAY INTO CENTRAL WI. SOME HIGH
CLOUDS AND PATCHES OF LOW CLOUDS OUT OF UPPER MI MOVING THROUGH
FAR NORTHERN WI. FOG HAS REMAINED PATCHY...MAINLY OVER NORTH
CENTRAL WI. MOVEMENT OF WAVE ALONG FRONT TO SOUTH HAS HELPED TO
MAINTAIN GRADIENT OVER EASTERN AND CENTRAL WI. HAVE BACKED OFF ON
FOG COVERAGE. HRRR CURRENTLY HANDLING LOW CLOUD COVERAGE FAIRLY
WELL WITH CLOUDS SPREADING INTO PARTS OF CENTRAL WI BY 12Z...THEN
DIMINISHING THROUGH MID TO LATE MORNING. LOWERED FEW TEMPS TO
ACCOUNT FOR CLOUDS.
MODELS CONTINUE TO FOCUS PCPN OVER CWA BETWEEN 06-18Z AS DYNAMICS
WITH UPPER WAVE AND SURFACE FRONT MOVE THROUGH STATE. EXACT COVERAGE
IN QUESTION WITH CONVECTIVE ELEMENTS...SO DID NOT MAKE SIG CHANGE
TO POP CATEGORIES ONLY SLOWING DOWN TIMING BY FEW HOURS.
INSTABILITY OVER REGION MARGINAL LIMITING SEVERE POTENTIAL.
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY
ISSUED AT 432 AM CDT SAT AUG 31 2013
MODELS CONTINUED TO GENERATE SMALL AREAS OF QPF ON SUNDAY NIGHT
WITH THE AREA STILL IN CYCLONIC FLOW BEHIND DEPARTING LOW
PRESSURE. HAVE INCLUDED CHANCE/SLIGHT CHANCE FOR SHOWERS ACROSS
MAINLY THE EASTERN AND NORTHERN PARTS OF THE AREA AS A RESULT.
DRIER CONDITIONS ARE THEN EXPECTED AS SURFACE HIGH PRESSURE MOVES
IN AND AN UPPER LEVEL RIDGE AMPLIFIES OVER THE WESTERN
CONUS...LEAVING THE AREA IN NW/WNW FLOW ALOFT. A SHORT WAVE IN THE
UPPER FLOW IS EXPECTED TO PASS WELL TO THE NORTHEAST OF THE STATE
AROUND THE MIDDLE OF THE WEEK AS A SURFACE COLD FRONT MOVES
THROUGH WISCONSIN. A DRY FRONTAL PASSAGE IS FORECAST FOR NOW SINCE
THERE WILL BE LITTLE MOISTURE AHEAD OF THE FRONT.
TEMPERATURES ARE LIKELY TO BE NEAR OR A BIT ABOVE NORMAL...EXCEPT
FOR SUNDAY NIGHT THROUGH MONDAY NIGHT IN THE WAKE OF THE APPROACHING
COLD FRONT.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1223 PM CDT SAT AUG 31 2013
STUBBORN MVFR STRATO-CU DECK OVER ERN WI TRAPPED UNDER
A STRONG INVERSION...DESPITE A STRONG LATE SUMMER SUN. MAY TAKE
TIL MID-AFTERNOON BEFORE WE ARE ABLE TO MIX THESE CLOUDS OUT.
OTHERWISE...WEAK SFC RDG OVER WI TO SLIDE EAST THIS EVENING AND
ALLOW FOR A CDFNT TO APPROACH THE REGION LATER TNGT. VFR
CONDITIONS ARE EXPECTED THIS EVENING...HOWEVER SOME PATCHY FOG IS
LIKELY TO PRECEDE THE LEADING EDGE OF PCPN MAINLY AFTER MIDNGT
WITH CIGS/VSBYS DROPPING TO AT LEAST MVFR CONDITIONS. THE THREAT
OF SHWRS/TSTMS WL THEN CONTINUE INTO SUNDAY MORNING WITH A
CONTINUATION OF MVFR CONDITIONS UNTIL THE CDFNT MOVES THROUGH
ROUGHLY LATE MORNING AND ALLOWS A VFR CONDITIONS TO RETURN.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....TE
LONG TERM......MG
AVIATION.......AK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1155 AM CDT SAT AUG 31 2013
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 330 AM CDT SAT AUG 31 2013
IMMEDIATE ISSUE TO DEAL WITH EARLY THIS MORNING IS ONGOING SHOWER
AND THUNDERSTORM ACTIVITY ACROSS FAR SOUTHWEST WI INTO NORTHEAST IA.
RAIN RATES HAVE BEEN FAIRLY HEAVY WITH THESE CLUSTERS OF SHOWERS AND
THUNDERSTORMS WITH 1-3 INCHES INDICATED IN 3-HRLY DUAL POL RADAR
ESTIMATES. THESE SHOWERS AND STORMS ARE THE RESULT OF A CLOSED 925MB
CYCLONIC CIRCULATION OVER CENTRAL IA AND WIND CONVERGENCE TO THE
NORTHEAST OF THIS LOW. THIS CONVERGENCE IN TURN IS WORKING ON HIGHER
PRECIPITABLE WATER VALUES ACROSS NORTHEAST IA INTO FAR SOUTHWEST WI.
RAP SHOWS THIS LOW AND CONVERGENCE/RESULTANT SHOWERS AND
THUNDERSTORMS SLIPPING SOUTH AND EAST OF THE AREA BY DAWN.
OTHERWISE...WATER VAPOR IMAGERY AND RAP 500MB ANALYSIS SHOWING
ANOTHER FAIRLY VIGOROUS MID-LEVEL SHORTWAVE TROUGH MOVING EAST
ACROSS CENTRAL DAKOTAS/NEBRASKA. RADAR MOSAIC SHOWING A CLUSTER OF
THUNDERSTORMS ALONG THE ND/SD BORDER WHERE SURGE OF 850MB MOISTURE
TRANSPORT WAS OCCURING AHEAD OF THE MID-LEVEL WAVE. THIS WILL BE OUR
WEATHER-MAKER FOR TONIGHT INTO SUNDAY.
FOR TODAY...ONCE THE SHOWERS AND STORMS DEPART FAR SOUTHERN PORTION
OF THE AREA THIS MORNING...WEAK RIDGE OF HIGH PRESSURE WILL PROVIDE
SLIGHTLY DRIER AND COOLER CONDITIONS. WILL SEE SOME LOW CLOUDS
ALONG/SOUTH OF I-90 THIS MORNING...BUT SHOULD BURN OFF BY LATE
MORNING. WITH MOSTLY SUNNY SKIES THROUGH THE REST OF THE DAY...LOOK
FOR HIGHS IN THE 80-85 DEGREE RANGE WITH DRIER DEW POINTS IN THE
LOWER TO MIDDLE 60S.
AFOREMENTIONED MID-LEVEL WAVE/SURFACE COLD FRONT MOVES TOWARD THE
AREA TONIGHT...AND MAKING PASSAGE ACROSS THE AREA SUNDAY MORNING FOR
A DECENT SHOT AT SOME SHOWERS AND THUNDERSTORMS. MODELS ARE SHOWING
BETTER MOISTURE TRANSPORT HEADING NORTH OF THE AREA...TIED TO BETTER
FORCING OF THE MID-LEVEL WAVE AND PROXIMITY TO SURFACE LOW OVER
SOUTHERN ONTARIO CANADA. FOR THIS REASON...KEPT LIKELY/HIGHER-END
CHANCE POPS NORTH OF I-94...AND TAPERING OFF SOUTH OF THIS. BEST
CHANCES SEEM TO CENTERED IN DURING THE 06-12Z TIME FRAME. THERE MAY
BE SOME UPSCALE IN THE INTENSITY OF THE SHOWERS/THUNDERSTORMS ACROSS
THE EAST IN THE 15Z-21Z TIME FRAME AS 0-1KM MLCAPE INCREASES INTO
THE 1500-2500J/KG RANGE ALONG WITH INCREASING 0-3KM BULK SHEAR. WILL
HAVE TO KEEP AND EYE ON THIS FOR SEVERE POTENTIAL...ESPECIALLY IF
THE FRONT SLOWS SOME AND INSTABILITY IS ALLOWED TO BUILD MORE AHEAD
OF THE FRONT.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 330 AM CDT SAT AUG 31 2013
GFS/ECMWF IN GOOD AGREEMENT SUNDAY NIGHT THROUGH TUESDAY IN BRINGING
HIGH PRESSURE ACROSS THE AREA IN NORTHWEST FLOW ALOFT FOR DRIER AND
COOLER WEATHER. LOOK FOR HIGHS SUNDAY AND MONDAY IN THE 70S WITH
OVERNIGHT LOWS SUNDAY NIGHT IN THE 50S AND IN THE UPPER 40S/NEAR 50
MONDAY NIGHT. ALSO...LOOKS LIKE A GOOD CHANCE OF PATCHY/AREAS OF FOG
MONDAY NIGHT ESPECIALLY IN THE RIVER VALLEYS AS THE HIGH SETTLES
OVERHEAD.
SOME WARMING EXPECTED ON WEDNESDAY AHEAD OF A COLD FRONT DROPPING
SOUTH OUT OF CANADA WITH HIGHS TOPPING OFF IN THE UPPER 70S TO THE
LOWER 80S. MODELS SHOW THIS FRONT CONTINUING TO SINK SOUTH ACROSS
THE AREA WEDNESDAY NIGHT. THE ECMWF IS MOSTLY DRY WITH THIS FROPA
WHILE THE GFS WANTS TO CONVECT ALONG/AHEAD OF THE FRONT. HAVE
INCLUDED A SLIGHT CHANCE OF SHOWERS/THUNDERSTORMS FOR NOW FOR AREAS
ALONG/SOUTH OF I-94.
FOR THURSDAY THROUGH FRIDAY...COOLER/OVERALL DRY NORTHWEST FLOW
ALOFT WILL PREVAIL AS UPPER LEVEL RIDGING BUILDS OVER THE PLAINS.
LOOKING FOR HIGHS IN THE 70S ON THURSDAY AND IN THE UPPER 70S/LOWER
80S FRIDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1155 AM CDT SAT AUG 31 2013
ITS TAKING AWHILE FOR MORNING MVFR CIGS TO LIFT/BURN OFF...BUT OBS
AND SATELLITE TRENDS SHOWING HOLES AND AN INCREASE IN THE DECKS.
EXPECT MOSTLY SCT CONDITIONS BY 19Z...WITH VFR INTO THE EVENING
HOURS.
LINE OF SHRA/TS WILL BE APPROACHING FROM THE NORTHWEST THIS
EVENING...STRONG/SEVERE. HOWEVER...THEY SHOULD BE ON A WEAKENING
TREND AS THEY NEAR KRST/KLSE AS INSTABILITY WANES AND THE STRONGER
FORCING HOLDS TO THE NORTH. SOME MODELS SUGGEST THAT MUCH OF THE
PCPN MAY FALL APART BY THE TIME IT REACHES WESTERN WI.
MEANWHILE...LAST FEW RUNS OF THE HRRR TREND TOWARD HOLDING IT
TOGETHER THROUGH AT LEAST KRST. THINK THIS IS MORE LIKELY AND WILL
TREND THE TAFS THIS WAY. WILL HOLD WITH VCSH AT KLSE FOR THE TIME
BEING. NOT A LOT OF SATURATION PER BUFKIT SOUNDINGS...SO WILL HOLD
WITH VFR CONDITIONS.
FRONTAL PASSAGE NEAR OR SHORTLY AFTER 12Z SUN...WITH RH FIELDS THEN
POINTING TO SOME THREAT OF MVFR/IFR CIGS. LATEST SATELLITE/SFC OBS
DOES SUPPORT THIS WITH EXPANSIVE LOW CLOUD SHIELD WEST OF A SFC LOW.
THE LOW STAYS WELL NORTH OVERNIGHT/SUN...BUT THIS CLOUD SHIELD COULD
SINK SOUTH EARLY SUN MORNING...BRINGING A SHORT PERIOD OF MVFR CIGS.
GOING TO TREND TOWARD THIS FOR NOW.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION.....RIECK