AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
900 AM PDT MON JUL 28 2008
.SYNOPSIS...
FAIR WEATHER WITH A SLOW WARMING TREND IS EXPECTED THIS WEEK. THE
MARINE LAYER WILL PRODUCE COASTAL CLOUDS THAT EXTEND INTO SOME
VALLEYS EACH NIGHT...BUT WILL DECREASE AS THE WEEK PROGRESSES.
MONSOONAL MOISTURE AND A SLIGHT CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS FOR THE MOUNTAINS AND DESERTS MAY RETURN NEXT WEEKEND.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
THE MARINE LAYER DEEPENED ENOUGH TO GET CLOUDS INTO THE ENTIRE
COASTAL BASIN THIS MORNING IN RESPONSE TO A WEAK UPPER LEVEL LOW
OVER SOCAL. THE LOW WILL MOVE EAST AND THE DOMINATING UPPER HIGH
OVER THE SOUTHWEST WILL BE ALLOWED TO EXPAND JUST A LITTLE OVER THE
NEXT SEVERAL DAYS. THIS WILL MEAN THE MARINE INFLUENCE AND COASTAL
CLOUDS WILL NOT BE AS EXTENSIVE. ALSO TEMPS WILL BE A FEW DEGREES
HIGHER...BUT ONLY CLOSE TO NORMAL...AND NOT SO MUCH HIGHER AT THE
COAST. NO MONSOON MOISTURE IS IN SIGHT THIS WEEK UNTIL REALLY THE
WEEKEND. A TRICKLE OF MOISTURE COMES UP FROM THE SOUTH ON FRI...WITH
A LITTLE MORE SAT...SUN AND MON. THIS WOULD BRING SMALL CHANCES OF
AFTERNOON AND EVE THUNDERSTORMS MAINLY IN THE MTNS.
&&
.AVIATION...
281415Z...MORNING TOP REPORTS FROM AIRCRAFT NEAR KSAN AND KONT
INDICATE THE MARINE LAYER DEPTH THIS MORNING WAS 2500 FEET. MARINE
LAYER DEPTH WILL SHOW LITTLE CHANGE THROUGH TUESDAY.
STRATUS WHICH EXTENDS INLAND OVER THE INLAND VALLEY AREAS AND THE
INLAND EMPIRE OVER KONT AND KSBD SHOULD BEGIN TO BREAK UP OVER THE
INLAND AREAS BETWEEN 16Z AND 17Z AND PULL BACK TO THE COASTLINE
BETWEEN 17Z AND 19Z. NOT MUCH BREAKUP IS EXPECTED ALONG THE
IMMEDIATE COAST AND STRATUS COULD LINGER OVER COASTAL AIRPORTS SUCH
AS KSAN AND KCRQ THROUGH THE AFTERNOON. STRATUS WILL SPREAD BACK
INLAND AFTER SUNSET REACHING THE FAR INLAND AREAS AFTER MIDNIGHT.
SIMILAR BREAKUP IS EXPECTED ON TUESDAY.
ABOVE THE MARINE LAYER INCLUDING THE MOUNTAINS AND DESERTS...A
MOSTLY CLEAR SKY WITH UNRESTRICTED VISIBILITIES WILL CONTINUE
THROUGH TUESDAY.
MAX TEMPS FOR TODAY AND TUESDAY FOR KPSP AND KTRM...40 TO 42C.
HORTON
&&
.SGX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
PUBLIC...MM
AVIATION/MARINE...HORTON
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
610 AM PDT MON JUL 28 2008
.SHORT TERM (TODAY-WEDNESDAY)...LOOKS A LIKE A VERY SIMILAR PATTERN
ON TAP FOR TODAY COMPARED TO YESTERDAY. TO THE NORTH...AN UPPER LVL
TROF CONTINUES TO PERSIST ACROSS NRN CAL TODAY...WITH AN AREA OF
HIGH PRESSURE CONTINUES TO HOLD STRONG ACROSS SO CAL AND AZ. LATEST
AMDAR SOUNDING NEAR KLAX INDICATED THE MARINE LAYER AT 2100 FT THIS
MORNING AND ONSHORE SFC GRADS SHOULD BE SIMILAR AS WELL. LATEST FOG
PRODUCT IMAGERY SHOWED LOW CLOUDS PUSHING INTO THE COASTAL SLOPES OF
ENTIRE FORECAST AREA...EXCEPT THE SANTA CLARITA VALLEY FOR NOW...BUT
SHOULD BE AFFECTED BY SUNRISE WITH AT LEAST PATCHY MORNING STRATUS.
WITH SUCH A DEEP MARINE LAYER INFLUENCE OVER THE AREA...THIS SHOULD
KEEP TEMPS ACROSS THE REGION RELATIVELY COOL ONCE AGAIN FOR THIS
TIME OF YEAR. EXPECT HIGHS ACROSS THE LA/VTU COUNTY VALLEYS TO
REMAIN IN THE 80S WITH THE ANTELOPE VALLEY REACHING THE MID 90S.
EXPECT PASO ROBLES TO REMAIN IN THE 80S ANOTHER DAY AS WELL.
HOWEVER...THE CUYAMA VALLEY SHOULD REACH WELL IN THE 90S ONCE AGAIN
TODAY. AS EXPECTED...GUSTY SOUTHWEST WINDS AFFECTED THE SOUTHWEST
PORTIONS OF THE ANTELOPE VALLEY YESTERDAY WITH GUSTS TO 50 MPH WITH
LAKE PALMDALE RECEIVING THE STRONGEST WIND GUSTS FROM THE INLET OF
THE SOLEDAD CYN PASS ON HWY 14 INTO THE ANTELOPE VALLEY. THE LAX-DAG
SFC GRADS ARE EXPECTED TO BE NEARLY IDENTICAL (NEAR +9 TO 10M THIS
AFTERNOON) TODAY...THEREFORE WILL RE-ISSUE A WIND ADVISORY FOR THE
ANTELOPE VALLEY ONCE AGAIN VALID LATER THIS MORNING THROUGH THIS
EVENING. WITH THE FOCUS ON THE AREA MENTIONED BETWEEN LAKE
PALMDALE...POPPY PARK AND THE SOLEDAD CYN PASS.
FOR TUE AND WED...ONSHORE FLOW SHOULD BE SOMEWHAT WEAKER EACH DAY
ALLOWING FOR A FEW DEGREES OF HEATING ACROSS THE INTERIOR SECTIONS.
THE UPPER LVL RIDGE WILL STRENGTHEN OVER THE AREA HELPING TO SQUASH
THE INVERSION SOME. THIS WILL REINFORCE SOME HEATING ACROSS THE
INTERIOR SECTIONS OF THE FORECAST AREA WITH SOME VALLEY
TEMPS...LOWER MOUNTAIN ELEVATIONS REACHING INTO THE LOWER TO MID
90S. THE ANTELOPE VALLEY SHOULD REACH THE LOWER TRIPLE TRIPLE DIGITS
BY WED AS WELL.
.LONG TERM (THU-SUN)...BOTH THE GFS AND ECMWF MODELS ARE IN
AGREEMENT KEEPING RIDGE OF HIGH PRESSURE OVER THE AREA THRU FRI.
WITH SW FLOW ALOFT OVER THE REGION...NO CHANCE OF MONSOONAL MOISTURE
TO AFFECT SO CAL THROUGH SAT. TEMPS SHOULD CONTINUE TO CLIMB
SLIGHTLY EACH DAY FROM THU THROUGH FRI...WITH VALLEYS NEARING TRIPLE
DIGITS AND THE ANTELOPE VALLEY SHOULD REACH NEAR 105 DEGREES BOTH
THU AND FRI. THE UPPER HIGH BEGINS TO PUSH FARTHER EAST SETTING UP
OVER THE 4 CORNERS REGION BY SAT. BOTH GFS AND ECMWF ARE NOW HINTING
AT DECENT SOUTHEAST MOIST FLOW AT 700 MB MOVING ACROSS THE SO CAL
DESERTS AND MTNS BY SUNDAY...AND INTO EARLY NEXT WEEK. FOR NOW WILL
GO WITH PARTLY CLOUDY ACROSS THE MTNS AND ANTELOPE VALLEY LATE
WEEKEND. HOWEVER...THERE COULD BE THE PENITENTIAL OF DESERT AND MTN
THUNDERSTORMS RETURNING BY EARLY NEXT WEEK.
&&
.AVIATION...
28/1300Z
1900 FOOT MARINE LAYER AND A 5.5 MB ONSHORE PUSH HAS BROUGHT MARINE
LAYER INTO ALL COASTS AND VLYS. EVERYTHING IS SIMILAR TO YDY AND
EXPECT SIMILAR BURN OFF...PERHAPS A HOUR LATER.
.KLAX...GOOD CONFIDENCE IN TAF. BURN OFF COULD BE A HOUR LATER THAN
FORECAST.
.KBUR...GOOD CONFIDENCE IN TAF.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
NONE
&&
$$
PUBLIC...KAPLAN
AVIATION...RORKE
WWW.WEATHER.GOV/LOSANGELES
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
320 AM PDT MON JUL 28 2008
.SHORT TERM (TODAY-WEDNESDAY)...LOOKS A LIKE A VERY SIMILAR PATTERN
ON TAP FOR TODAY COMPARED TO YESTERDAY. TO THE NORTH...AN UPPER LVL
TROF CONTINUES TO PERSIST ACROSS NRN CAL TODAY...WITH AN AREA OF
HIGH PRESSURE CONTINUES TO HOLD STRONG ACROSS SO CAL AND AZ. LATEST
AMDAR SOUNDING NEAR KLAX INDICATED THE MARINE LAYER AT 2100 FT THIS
MORNING AND ONSHORE SFC GRADS SHOULD BE SIMILAR AS WELL. LATEST FOG
PRODUCT IMAGERY SHOWED LOW CLOUDS PUSHING INTO THE COASTAL SLOPES OF
ENTIRE FORECAST AREA...EXCEPT THE SANTA CLARITA VALLEY FOR NOW...BUT
SHOULD BE AFFECTED BY SUNRISE WITH AT LEAST PATCHY MORNING STRATUS.
WITH SUCH A DEEP MARINE LAYER INFLUENCE OVER THE AREA...THIS SHOULD
KEEP TEMPS ACROSS THE REGION RELATIVELY COOL ONCE AGAIN FOR THIS
TIME OF YEAR. EXPECT HIGHS ACROSS THE LA/VTU COUNTY VALLEYS TO
REMAIN IN THE 80S WITH THE ANTELOPE VALLEY REACHING THE MID 90S.
EXPECT PASO ROBLES TO REMAIN IN THE 80S ANOTHER DAY AS WELL.
HOWEVER...THE CUYAMA VALLEY SHOULD REACH WELL IN THE 90S ONCE AGAIN
TODAY. AS EXPECTED...GUSTY SOUTHWEST WINDS AFFECTED THE SOUTHWEST
PORTIONS OF THE ANTELOPE VALLEY YESTERDAY WITH GUSTS TO 50 MPH WITH
LAKE PALMDALE RECEIVING THE STRONGEST WIND GUSTS FROM THE INLET OF
THE SOLEDAD CYN PASS ON HWY 14 INTO THE ANTELOPE VALLEY. THE LAX-DAG
SFC GRADS ARE EXPECTED TO BE NEARLY IDENTICAL (NEAR +9 TO 1OMB THIS
AFTERNOON) TODAY...THEREFORE WILL RE-ISSUE A WIND ADVISORY FOR THE
ANTELOPE VALLEY ONCE AGAIN VALID LATER THIS MORNING THROUGH THIS
EVENING. WITH THE FOCUS ON THE AREA MENTIONED BETWEEN LAKE
PALMDALE...POPPY PARK AND THE SOLEDAD CYN PASS.
FOR TUE AND WED...ONSHORE FLOW SHOULD BE SOMEWHAT WEAKER EACH DAY
ALLOWING FOR A FEW DEGREES OF HEATING ACROSS THE INTERIOR SECTIONS.
THE UPPER LVL RIDGE WILL STRENGTHEN OVER THE AREA HELPING TO SQUASH
THE INVERSION SOME. THIS WILL REINFORCE SOME HEATING ACROSS THE
INTERIOR SECTIONS OF THE FORECAST AREA WITH SOME VALLEY
TEMPS...LOWER MOUNTAIN ELEVATIONS REACHING INTO THE LOWER TO MID
90S. THE ANTELOPE VALLEY SHOULD REACH THE LOWER TRIPLE TRIPLE DIGITS
BY WED AS WELL.
.LONG TERM (THU-SUN)...BOTH THE GFS AND ECMWF MODELS ARE IN
AGREEMENT KEEPING RIDGE OF HIGH PRESSURE OVER THE AREA THRU FRI.
WITH SW FLOW ALOFT OVER THE REGION...NO CHANCE OF MONSOONAL MOISTURE
TO AFFECT SO CAL THROUGH SAT. TEMPS SHOULD CONTINUE TO CLIMB
SLIGHTLY EACH DAY FROM THU THROUGH FRI...WITH VALLEYS NEARING TRIPLE
DIGITS AND THE ANTELOPE VALLEY SHOULD REACH NEAR 105 DEGREES BOTH
THU AND FRI. THE UPPER HIGH BEGINS TO PUSH FARTHER EAST SETTING UP
OVER THE 4 CORNERS REGION BY SAT. BOTH GFS AND ECMWF ARE NOW HINTING
AT DECENT SOUTHEAST MOIST FLOW AT 700 MB MOVING ACROSS THE SO CAL
DESERTS AND MTNS BY SUNDAY...AND INTO EARLY NEXT WEEK. FOR NOW WILL
GO WITH PARTLY CLOUDY ACROSS THE MTNS AND ANTELOPE VALLEY LATE
WEEKEND. HOWEVER...THERE COULD BE THE PENITENTIAL OF DESERT AND MTN
THUNDERSTORMS RETURNING BY EARLY NEXT WEEK.
&&
.AVIATION...DISCUSSION TO COME AFTER 12Z TAF PACKAGE.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
NONE
&&
$$
PUBLIC...KAPLAN
AVIATION...RORKE
WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
635 PM CDT TUE JUL 29 2008
.DISCUSSION...
311 PM CDT
THERE IS A CHANCE OF THUNDERSTORMS TONIGHT AND WEDNESDAY. SOME OF
THE THUNDERSTORMS MAY PRODUCE SMALL HAIL AND HEAVY RAINS. THE HIGH
TEMPERATURES ARE FORECAST TO BE IN THE UPPER 90S SATURDAY AND
SUNDAY. THERE MAY SOME DANGEROUS HEAT INDEX FOR THOSE DAYS.
A SURFACE TROUGH WILL MOVE INTO ILLINOIS THIS EVENING. THIS IS A
WIND SHIFT LINE THAT MAY BE A RESULT OF AGEOSTROPHIC CIRCULATION
FROM THE APPROACHING 500 MB TROUGH OVER KANSAS AND OKLAHOMA. THIS
TROUGH CAN BE SEEN ON THE VISIBLE SATELLITE IMAGERY AS A
CIRCULATION. THE VERTICAL MOTION FROM THIS THE ADJUSTMENT CAN BE
INFERRED BY THE POTENTIAL TEMPERATURE CHANGES AS THE VORTICITY
MAXIMUM MOVES INTO MISSOURI AND ILLINOIS. THERE IS SOME
INSTABILITY AS THE LEVEL OF FREE CONVECTION IS AROUND 6,977 FEET
AS SEEN ON THE FORECAST SOUNDING AT 2 AM CDT. THE LIFTED
CONDENSATION LEVEL IS FORECAST TO BE AROUND 1,858 FEET. THE
INSTABILITY IS RATHER DEEP. WE WILL KEEP THE THUNDERSTORM CHANCES
TONIGHT WITH THE HIGHEST PROBABILITY BEFORE AND DURING WEDNESDAY
MORNING. WE EXPECT SCATTERED THUNDERSTORMS. A COLD FRONT WILL MOVE
SOUTH INTO NORTHERN ILLINOIS BY LATE WEDNESDAY MORNING. WE USED
THE 12 UTC RUN OF LOCAL WRF MODEL AND 12 UTC RUN OF THE NAM
MODELS.
FOR WEDNESDAY THIS FRONT WILL WASH OUT OVER NORTHERN ILLINOIS.
THERE MAY BE ENOUGH LIFT FOR A CHANCE OF THUNDERSTORMS
WEDNESDAY. THE HIGH TEMPERATES ARE EXPECTED TO CLIMB INTO THE
UPPER 80S WEDNESDAY AND THURSDAY.
THE WEEKEND WILL BE SIGNIFICANT WITH VERY WARM AND HUMID AIR
OVER NORTHERN ILLINOIS AND NORTHWEST INDIANA. THE GFS MODEL SHOW
A LARGE 500 MB RIDGE OVER NORTHERN ILLINOIS SATURDAY. THIS LESSER
DENSE AIR INDICATES VERY HIGH TEMPERATURES. WE HAVE FORECAST THE
HIGH TEMPERATURES IN THE UPPER 90S FOR SATURDAY AND SUNDAY. THIS
WILL GIVE HEAT INDEX AROUND 100 IN SOME LOCATIONS. WE WILL MONITOR
THIS FORECAST FOR POSSIBLE HEAT ADVISORIES AND WARNINGS FOR THE
WEEKEND.
&&
.AVIATION...
635 PM CDT
FOR THE 00Z TAFS...MAIN AVIATION CONCERNS WILL BE CONVECTIVE
POTENTIAL THIS EVENING...AND THEN WINDS. CONVECTIVE COMPLEX WHICH
DEVELOPED EARLIER THIS AFTERNOON ACROSS SOUTHERN IOWA/NORTHERN
MISSOURI HAS DEVELOPED STRONG OUTFLOW ACROSS WEST CENTRAL ILLINOIS.
TAMDAR DATA FROM THIS AREA INDICATING FAIRLY LARGE 850 HPA DEW PT
DEPRESSIONS WHICH SHOULD ACT TO MAINTAIN OUTFLOW STRENGTH OVER THE
NEXT FEW HOURS...BUT IT APPEARS AS THOUGH THE GREATER WIND THREAT
SHOULD REMAIN SOUTH OF THE TERMINALS. HOWEVER...SHOULD SEE PERIOD OF
SHOWERS AND THUNDERSTORMS THIS EVENING IN THE 01Z-04Z TIME PERIOD AS
A SHORT WAVE TROUGH ASSOCIATED WITH REMNANTS OF DOLLY MOVES INTO NRN
ILLINOIS. THIS DISTURBANCE WILL GRADUALLY WEAKEN TONIGHT AS IT LIFTS
NORTHEAST AND AS DIURNAL INSTABILITY WANES EXPECTING THREAT OF
PRECIP TO DIMINISH AFTER 04Z-05Z ONCE CONVECTIVE COMPLEX TO THE
SOUTH EXITS THE AREA. DID MAINTAIN MENTION OF MVFR VSBYS IN LIGHT
FOG/HAZE TONIGHT GIVEN WEAK WIND FIELD IN ADVANCE OF SFC FRONT THAT
WILL MOVE THROUGH NRN IL TOMORROW MORNING AND ABUNDANT LOW LEVEL
MOISTURE. WIND SHIFT TO THE WEST/NORTHWEST STILL LOOKS REASONABLE BY
MID MORNING TOMORROW WITH WIND DIRECTIONS IN THE 270-300 DEGREE
RANGE EXPECTED TOMORROW AFTERNOON AND WIND SPEEDS AROUND 10 KNOTS.
HAVE KEPT TAFS DRY FOR TOMORROW WITH NEXT UPPER LEVEL SHORT WAVE OF
SIGNIFICANCE NOT EXPECTED UNTIL TOMORROW EVENING.
MARSILI
&&
.MARINE...
303 PM CDT
RELATIVELY DEEP LOW PRESSURE ACROSS WESTERN ONTARIO FOR LATE JULY
WILL CONTINUE TO TRACK EASTWARD NORTH OF LAKE SUPERIOR TONIGHT
INTO EARLY WEDNESDAY...AND INTO SOUTHERN QUEBEC WEDNESDAY NIGHT.
IN THE PROCESS...A TRAILING COLD FRONT WILL MOVE SOUTHEAST ACROSS
NORTHERN LAKE MICHIGAN LATE TONIGHT...AND SAG ACROSS SOUTHERN LAKE
MICHIGAN WEDNESDAY. SURFACE PRESSURE FALLS ACROSS THE NORTHERN
LAKES IN ADVANCE OF THIS LOW WILL TIGHTEN THE PRESSURE GRADIENT
ESPECIALLY OVER NORTHERN LAKE MICHIGAN THIS EVENING...RESULTING IN
STRENGTHENING SOUTHERLY WINDS OVERNIGHT. WINDS WILL THEN SHIFT TO
THE WEST AND NORTHWEST WITH THE PASSAGE OF THE COLD FRONT
WEDNESDAY...WITH THE GRADIENT QUICKLY DECREASING AS WEAK HIGH
PRESSURE MOVES INTO THE WESTERN LAKES WEDNESDAY NIGHT AND
THURSDAY. THIS HIGH WILL MOVE SOUTHEAST OF THE LAKE BY
SATURDAY...WITH SOUTHERLY FLOW RETURNING AS LOW PRESSURE DEVELOPS
ACROSS THE NORTHERN PLAINS. THIS LOW WILL WEAKEN BY EARLY SUNDAY
AS ANOTHER LOW PUSHES ACROSS CENTRAL CANADA...AND DRAGS ANOTHER
COLD FRONT SOUTHEAST ACROSS THE WESTERN LAKES.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
314 PM CDT TUE JUL 29 2008
.DISCUSSION...
311 PM CDT
THERE IS A CHANCE OF THUNDERSTORMS TONIGHT AND WEDNESDAY. SOME OF
THE THUNDERSTORMS MAY PRODUCE SMALL HAIL AND HEAVY RAINS. THE HIGH
TEMPERATURES ARE FORECAST TO BE IN THE UPPER 90S SATURDAY AND
SUNDAY. THERE MAY SOME DANGEROUS HEAT INDEX FOR THOSE DAYS.
A SURFACE TROUGH WILL MOVE INTO ILLINOIS THIS EVENING. THIS IS A
WIND SHIFT LINE THAT MAY BE A RESULT OF AGEOSTROPHIC CIRCULATION
FROM THE APPROACHING 500 MB TROUGH OVER KANSAS AND OKLAHOMA. THIS
TROUGH CAN BE SEEN ON THE VISIBLE SATELLITE IMAGERY AS A
CIRCULATION. THE VERTICAL MOTION FROM THIS THE ADJUSTMENT CAN BE
INFERRED BY THE POTENTIAL TEMPERATURE CHANGES AS THE VORTICITY
MAXIMUM MOVES INTO MISSOURI AND ILLINOIS. THERE IS SOME
INSTABILITY AS THE LEVEL OF FREE CONVECTION IS AROUND 6,977 FEET
AS SEEN ON THE FORECAST SOUNDING AT 2 AM CDT. THE LIFTED
CONDENSATION LEVEL IS FORECAST TO BE AROUND 1,858 FEET. THE
INSTABILITY IS RATHER DEEP. WE WILL KEEP THE THUNDERSTORM CHANCES
TONIGHT WITH THE HIGHEST PROBABILITY BEFORE AND DURING WEDNESDAY
MORNING. WE EXPECT SCATTERED THUNDERSTORMS. A COLD FRONT WILL MOVE
SOUTH INTO NORTHERN ILLINOIS BY LATE WEDNESDAY MORNING. WE USED
THE 12 UTC RUN OF LOCAL WRF MODEL AND 12 UTC RUN OF THE NAM
MODELS.
FOR WEDNESDAY THIS FRONT WILL WASH OUT OVER NORTHERN ILLINOIS.
THERE MAY BE ENOUGH LIFT FOR A CHANCE OF THUNDERSTORMS
WEDNESDAY. THE HIGH TEMPERATES ARE EXPECTED TO CLIMB INTO THE
UPPER 80S WEDNESDAY AND THURSDAY.
THE WEEKEND WILL BE SIGNIFICANT WITH VERY WARM AND HUMID AIR
OVER NORTHERN ILLINOIS AND NORTHWEST INDIANA. THE GFS MODEL SHOW
A LARGE 500 MB RIDGE OVER NORTHERN ILLINOIS SATURDAY. THIS LESSER
DENSE AIR INDICATES VERY HIGH TEMPERATURES. WE HAVE FORECAST THE
HIGH TEMPERATURES IN THE UPPER 90S FOR SATURDAY AND SUNDAY. THIS
WILL GIVE HEAT INDEX AROUND 100 IN SOME LOCATIONS. WE WILL MONITOR
THIS FORECAST FOR POSSIBLE HEAT ADVISORIES AND WARNINGS FOR THE
WEEKEND.
&&
.AVIATION...
1236 PM CDT
FOR 18Z TAFS...MAIN CONCERN IS WINDS IN SHORT TERM AND CONVECTION
POTENTIAL AT TERMINALS NEXT 18 HOURS.
RELATIVELY STRONG...FOR LATE JULY...MID LEVEL CIRCULATION NOTED IN
RAOB/PROFILER/VAPOR DATA MOVING ACROSS LAKE WINNIPEG AREA OF
SOUTHEAST MANITOBA EARLY THIS AFTERNOON. MODEL GUIDANCE IN GOOD
AGREEMENT IN CONTINUING TO MOVE THIS FEATURE EAST THROUGH WEDNESDAY
MORNING WITH BEST MID LEVEL FORCING/HEIGHT FALLS TRANSLATING ACROSS
THE NORTHERN GREAT LAKES. RESULTING SURFACE PRESSURE FALLS ALSO
FOCUSED FROM NORTH CENTRAL WI TO LAKE SUPERIOR THIS AFTERNOON...
WITH WEAKER SOUTHEASTERLY GRADIENT ACROSS FORECAST AREA EXPECTED TO
TIGHTEN A BIT AND BECOME MORE SOUTHERLY WITH TIME. HIGHER RESOLUTION
SHORT TERM GUIDANCE INCLUDING NAM/RUC AND LOCALLY RUN NAM ALL
SUGGEST CURRENT SOUTHEAST FLOW/LAKE BREEZE WILL BE OVERCOME BY
SOUTHERLY WINDS BY MID AFTERNOON. MAIN AREA OF LOW PRESSURE MOVING
THROUGH ONTARIO OVERNIGHT/WEDNESDAY TRAILS ACTUAL COLD FRONT ACROSS
FORECAST AREA DURING THE MORNING HOURS WEDNESDAY...THOUGH GUIDANCE
SUGGESTS MORE OF A BROAD PRESSURE TROUGH AND GRADUAL WIND SHIFT FROM
SOUTHWEST TO WESTERLY WEDNESDAY MORNING. TRUE FROPA APPEARS 14-16Z
WITH WIND VEERING MORE NORTHWEST.
WITH RESPECT TO THUNDERSTORM POTENTIAL...UPSTREAM MORNING RAOBS
INDICATE RELATIVELY STEEP LAPSE RATES ABOVE 800 HPA OR SO...THOUGH
RECENT ACARS ASCENT SOUNDINGS FROM KORD/KRFD DEPICT MORE STABLE
THERMAL PROFILES FARTHER TO THE EAST. RUC/LOCAL NAM FORECAST
SOUNDINGS CONTINUE TO INDICATE RATHER MARGINAL LOW LEVEL LAPSE RATES
THROUGH THE AFTERNOON WHICH SUGGESTS ORGANIZED CONVECTION MAY HAVE A
TOUGH TIME DEVELOPING ACROSS TERMINALS. RADAR TRENDS HAVE INDICATED
A FEW RW/TRW THIS MORNING FROM IA/MO BORDER REGION INTO WESTERN IL
IN ISENTROPIC ASCENT REGION ALONG AXIS OF WEAK 20 KNOT LOW LEVEL
JET. 15Z SURFACE ANALYSIS INDICATES WEAK WARM FRONTAL FEATURE FROM
SOUTHEAST IA TO NEAR KSTL...WITH 925-850 HPA THERMAL
GRADIENT/ELEVATED WARM FRONT FROM IA TO CENTRAL IL WHICH HAS LIKELY
BEEN AIDING DEVELOPMENT OF ISOLATED CONVECTION...THOUGH THESE
FEATURES APPEAR TO BECOME MORE DIFFUSE WITH TIME PER RUC/NAM
FORECASTS. THUS WHILE ISOLATED/SCATTERED CONVECTION LIKELY TO OCCUR
NEAR AND ESPECIALLY WEST/SOUTHWEST OF TERMINALS THIS AFTERNOON...
LACK OF CLEAR LOW LEVEL FORCING/FOCUS YIELDS CONFIDENCE TOO LOW FOR
POINT FORECAST TAF INCLUSION AT THIS TIME. HAVE ELECTED HOWEVER TO
MENTION A VCSH WITH CB CLOUD GROUP FOR KRFD DURING PEAK DIURNAL
HEATING LATER THIS AFTERNOON.
FWC/MET GUIDANCE SUGGESTS SOME MVFR HAZE BEFORE/AROUND SUNRISE AND
THIS APPEARS REASONABLE GIVEN SURFACE DEW POINT TEMPS IN LOWER 70S
AND LIGHT SURFACE WINDS.
RATZER
&&
.MARINE...
303 PM CDT
RELATIVELY DEEP LOW PRESSURE ACROSS WESTERN ONTARIO FOR LATE JULY
WILL CONTINUE TO TRACK EASTWARD NORTH OF LAKE SUPERIOR TONIGHT
INTO EARLY WEDNESDAY...AND INTO SOUTHERN QUEBEC WEDNESDAY NIGHT.
IN THE PROCESS...A TRAILING COLD FRONT WILL MOVE SOUTHEAST ACROSS
NORTHERN LAKE MICHIGAN LATE TONIGHT...AND SAG ACROSS SOUTHERN LAKE
MICHIGAN WEDNESDAY. SURFACE PRESSURE FALLS ACROSS THE NORTHERN
LAKES IN ADVANCE OF THIS LOW WILL TIGHTEN THE PRESSURE GRADIENT
ESPECIALLY OVER NORTHERN LAKE MICHIGAN THIS EVENING...RESULTING IN
STRENGTHENING SOUTHERLY WINDS OVERNIGHT. WINDS WILL THEN SHIFT TO
THE WEST AND NORTHWEST WITH THE PASSAGE OF THE COLD FRONT
WEDNESDAY...WITH THE GRADIENT QUICKLY DECREASING AS WEAK HIGH
PRESSURE MOVES INTO THE WESTERN LAKES WEDNESDAY NIGHT AND
THURSDAY. THIS HIGH WILL MOVE SOUTHEAST OF THE LAKE BY
SATURDAY...WITH SOUTHERLY FLOW RETURNING AS LOW PRESSURE DEVELOPS
ACROSS THE NORTHERN PLAINS. THIS LOW WILL WEAKEN BY EARLY SUNDAY
AS ANOTHER LOW PUSHES ACROSS CENTRAL CANADA...AND DRAGS ANOTHER
COLD FRONT SOUTHEAST ACROSS THE WESTERN LAKES.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
303 PM CDT TUE JUL 29 2008
.DISCUSSION...
320 AM CDT
MAIN CONCERNS FOR THE SHORT TERM WILL FOCUS ON INCREASING
HEAT/HUMIDITY AND THUNDER POTENTIAL. THE REGION WILL SEE A RETURN
OF TEMPERATURES APPROACHING...AND IN SOME LOCATIONS...EXCEEDING 90
DEGREES TODAY. WITH 850MB TEMPS APPROACHING 20C BY THIS AFTERNOON
UNDER A BROAD...BUILDING RIDGE ALOFT...FEEL CONFIDENT THAT MANY
LOCATIONS SHOULD SEE 90F TODAY...PARTICULARLY URBANIZED AREAS...AS
THERE SHOULD BE LITTLE CLOUDINESS THROUGH THE AFTERNOON TO IMPEDE
INSOLATION. WHILE THE GFS BASED MOS PRODUCTS WANT TO BRING ORD/RFD UP
TO 93F TODAY...THE NAM BASED GUIDANCE IS MUCH LOWER...ONLY IN THE
MIDDLE 80S. THE MAIN DIFFERENCE BETWEEN THESE TWO MODELS IN HOW
THEY HANDLE THEIR RESPECTIVE LOW LEVEL MOISTURE FIELDS. THE NAM IS
MOISTER...THUS RETARDING THE HEATING...WHILE THE GFS IS
DRIER...ALLOWING TEMPS TO CLIMB HIGHER. BASED ON UPSTREAM TRENDS
IN LATEST SFC ANALYSIS...FEEL THAT THE MOISTER NAM BASED GUIDANCE
IS THE WAY TO GO AND HAVE INCREASED TEMPS A BIT OVER THE GOING
FORECAST. HAVE CARRIED THIS IDEA THROUGH THE REMAINDER OF THE
SHORT TERM PERIOD AND INTO THE LONGER TERM FORECAST PERIOD...
GENERALLY RAISING TEMPS FOR THE GOING FORECAST...INCLUDING
WIDESPREAD LOW 90S FOR THE COMING WEEKEND. WITH THE 00Z GFS
INDICATING 850MB TEMPS CLIMBING TO 23C...LOW 90S COULD EVEN BE
CONSERVATIVE. AS FOR THUNDER POTENTIAL FOR LATER TODAY...HAVE
DROPPED ANY MENTION OF POPS OVER THE ENTIRE CWA BEFORE 18Z AND
WILL SLOW THE PROGRESSION OF PCPN ACROSS THE CWA FOR 18Z-00Z
PERIOD...REMOVING POPS FROM THE ERN SECTIONS...PARTICULARLY THE
NWRN INDIANA COUNTIES...THRU 00Z. MODEL SOUNDING INDICATE SOME
WEAK CAPPING OVER THE ERN LOCATIONS...BUT A DEVELOPING WARM
FRONTAL BOUNDARY CROSSING THE MISSISSIPPI RIVER INTO NWRN IL LATE
THIS AFTERNOON SHOULD PROVIDE ADEQUATE FOCUS FOR TS DEVELOPMENT
OVER THE FAR WRN PORTIONS OF THE CWA LATE THIS AFTERNOON. THE NAM
HAS SHOWN GOOD CONTINUITY ON HANDLING THIS FEATURE AND THE
ASSOCIATED MID LEVEL SHORT WAVE MOVING ACROSS NRN IL THIS
EVENING...SO HAVE TRENDED TOWARD THIS SOLUTION FOR TIMING OF
SWEEPING POPS ACROSS THE AREA TONIGHT. HAVE LIMITED POPS TO HIGHER
END CHANCE AS THERE IS STILL A CHANCE FOR A SPLIT IN THE MOST
INTENSE AND MOST ORGANIZED CONVECTION AS THE SYSTEM CURRENTLY OVER
THE SOUTH HIGH PLAINS LOOKS TO BE TRENDING MORE SOUTHERLY...OVER
CNTRL AND SRN ILLINOIS...WHILE THE NRN STREAM MCS ACTIVITY WILL
LIKELY AFFECT WISCONSIN. HOWEVER...THE ENVIRONMENT WILL HAVE ADEQUATE
OF HEAT AND HUMIDITY IN PLACE TO JUSTIFY THE POP FORECAST. TEMPS
SHOULD MODERATE A BIT BY THURSDAY AS A STRONG UPPER LOW CROSSES
SRN CANADA...TURNING UPPER FLOW MORE NWLY...BUT STRONG RIDGING
WILL QUICKLY BUILD IN BEHIND...BRINGING A SIGNIFICANT WARM UP FOR
FRIDAY AND INTO THE WEEKEND.
KREIN
&&
.AVIATION...
1236 PM CDT
FOR 18Z TAFS...MAIN CONCERN IS WINDS IN SHORT TERM AND CONVECTION
POTENTIAL AT TERMINALS NEXT 18 HOURS.
RELATIVELY STRONG...FOR LATE JULY...MID LEVEL CIRCULATION NOTED IN
RAOB/PROFILER/VAPOR DATA MOVING ACROSS LAKE WINNIPEG AREA OF
SOUTHEAST MANITOBA EARLY THIS AFTERNOON. MODEL GUIDANCE IN GOOD
AGREEMENT IN CONTINUING TO MOVE THIS FEATURE EAST THROUGH WEDNESDAY
MORNING WITH BEST MID LEVEL FORCING/HEIGHT FALLS TRANSLATING ACROSS
THE NORTHERN GREAT LAKES. RESULTING SURFACE PRESSURE FALLS ALSO
FOCUSED FROM NORTH CENTRAL WI TO LAKE SUPERIOR THIS AFTERNOON...
WITH WEAKER SOUTHEASTERLY GRADIENT ACROSS FORECAST AREA EXPECTED TO
TIGHTEN A BIT AND BECOME MORE SOUTHERLY WITH TIME. HIGHER RESOLUTION
SHORT TERM GUIDANCE INCLUDING NAM/RUC AND LOCALLY RUN NAM ALL
SUGGEST CURRENT SOUTHEAST FLOW/LAKE BREEZE WILL BE OVERCOME BY
SOUTHERLY WINDS BY MID AFTERNOON. MAIN AREA OF LOW PRESSURE MOVING
THROUGH ONTARIO OVERNIGHT/WEDNESDAY TRAILS ACTUAL COLD FRONT ACROSS
FORECAST AREA DURING THE MORNING HOURS WEDNESDAY...THOUGH GUIDANCE
SUGGESTS MORE OF A BROAD PRESSURE TROUGH AND GRADUAL WIND SHIFT FROM
SOUTHWEST TO WESTERLY WEDNESDAY MORNING. TRUE FROPA APPEARS 14-16Z
WITH WIND VEERING MORE NORTHWEST.
WITH RESPECT TO THUNDERSTORM POTENTIAL...UPSTREAM MORNING RAOBS
INDICATE RELATIVELY STEEP LAPSE RATES ABOVE 800 HPA OR SO...THOUGH
RECENT ACARS ASCENT SOUNDINGS FROM KORD/KRFD DEPICT MORE STABLE
THERMAL PROFILES FARTHER TO THE EAST. RUC/LOCAL NAM FORECAST
SOUNDINGS CONTINUE TO INDICATE RATHER MARGINAL LOW LEVEL LAPSE RATES
THROUGH THE AFTERNOON WHICH SUGGESTS ORGANIZED CONVECTION MAY HAVE A
TOUGH TIME DEVELOPING ACROSS TERMINALS. RADAR TRENDS HAVE INDICATED
A FEW RW/TRW THIS MORNING FROM IA/MO BORDER REGION INTO WESTERN IL
IN ISENTROPIC ASCENT REGION ALONG AXIS OF WEAK 20 KNOT LOW LEVEL
JET. 15Z SURFACE ANALYSIS INDICATES WEAK WARM FRONTAL FEATURE FROM
SOUTHEAST IA TO NEAR KSTL...WITH 925-850 HPA THERMAL
GRADIENT/ELEVATED WARM FRONT FROM IA TO CENTRAL IL WHICH HAS LIKELY
BEEN AIDING DEVELOPMENT OF ISOLATED CONVECTION...THOUGH THESE
FEATURES APPEAR TO BECOME MORE DIFFUSE WITH TIME PER RUC/NAM
FORECASTS. THUS WHILE ISOLATED/SCATTERED CONVECTION LIKELY TO OCCUR
NEAR AND ESPECIALLY WEST/SOUTHWEST OF TERMINALS THIS AFTERNOON...
LACK OF CLEAR LOW LEVEL FORCING/FOCUS YIELDS CONFIDENCE TOO LOW FOR
POINT FORECAST TAF INCLUSION AT THIS TIME. HAVE ELECTED HOWEVER TO
MENTION A VCSH WITH CB CLOUD GROUP FOR KRFD DURING PEAK DIURNAL
HEATING LATER THIS AFTERNOON.
FWC/MET GUIDANCE SUGGESTS SOME MVFR HAZE BEFORE/AROUND SUNRISE AND
THIS APPEARS REASONABLE GIVEN SURFACE DEW POINT TEMPS IN LOWER 70S
AND LIGHT SURFACE WINDS.
RATZER
&&
.MARINE...
303 PM CDT
RELATIVELY DEEP LOW PRESSURE ACROSS WESTERN ONTARIO FOR LATE JULY
WILL CONTINUE TO TRACK EASTWARD NORTH OF LAKE SUPERIOR TONIGHT
INTO EARLY WEDNESDAY...AND INTO SOUTHERN QUEBEC WEDNESDAY NIGHT.
IN THE PROCESS...A TRAILING COLD FRONT WILL MOVE SOUTHEAST ACROSS
NORTHERN LAKE MICHIGAN LATE TONIGHT...AND SAG ACROSS SOUTHERN LAKE
MICHIGAN WEDNESDAY. SURFACE PRESSURE FALLS ACROSS THE NORTHERN
LAKES IN ADVANCE OF THIS LOW WILL TIGHTEN THE PRESSURE GRADIENT
ESPECIALLY OVER NORTHERN LAKE MICHIGAN THIS EVENING...RESULTING IN
STRENGTHENING SOUTHERLY WINDS OVERNIGHT. WINDS WILL THEN SHIFT TO
THE WEST AND NORTHWEST WITH THE PASSAGE OF THE COLD FRONT
WEDNESDAY...WITH THE GRADIENT QUICKLY DECREASING AS WEAK HIGH
PRESSURE MOVES INTO THE WESTERN LAKES WEDNESDAY NIGHT AND
THURSDAY. THIS HIGH WILL MOVE SOUTHEAST OF THE LAKE BY
SATURDAY...WITH SOUTHERLY FLOW RETURNING AS LOW PRESSURE DEVELOPS
ACROSS THE NORTHERN PLAINS. THIS LOW WILL WEAKEN BY EARLY SUNDAY
AS ANOTHER LOW PUSHES ACROSS CENTRAL CANADA...AND DRAGS ANOTHER
COLD FRONT SOUTHEAST ACROSS THE WESTERN LAKES.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1236 PM CDT TUE JUL 29 2008
.DISCUSSION...
320 AM CDT
MAIN CONCERNS FOR THE SHORT TERM WILL FOCUS ON INCREASING
HEAT/HUMIDITY AND THUNDER POTENTIAL. THE REGION WILL SEE A RETURN
OF TEMPERATURES APPROACHING...AND IN SOME LOCATIONS...EXCEEDING 90
DEGREES TODAY. WITH 850MB TEMPS APPROACHING 20C BY THIS AFTERNOON
UNDER A BROAD...BUILDING RIDGE ALOFT...FEEL CONFIDENT THAT MANY
LOCATIONS SHOULD SEE 90F TODAY...PARTICULARLY URBANIZED AREAS...AS
THERE SHOULD BE LITTLE CLOUDINESS THROUGH THE AFTERNOON TO IMPEDE
INSOLATION. WHILE THE GFS BASED MOS PRODUCTS WANT TO BRING ORD/RFD UP
TO 93F TODAY...THE NAM BASED GUIDANCE IS MUCH LOWER...ONLY IN THE
MIDDLE 80S. THE MAIN DIFFERENCE BETWEEN THESE TWO MODELS IN HOW
THEY HANDLE THEIR RESPECTIVE LOW LEVEL MOISTURE FIELDS. THE NAM IS
MOISTER...THUS RETARDING THE HEATING...WHILE THE GFS IS
DRIER...ALLOWING TEMPS TO CLIMB HIGHER. BASED ON UPSTREAM TRENDS
IN LATEST SFC ANALYSIS...FEEL THAT THE MOISTER NAM BASED GUIDANCE
IS THE WAY TO GO AND HAVE INCREASED TEMPS A BIT OVER THE GOING
FORECAST. HAVE CARRIED THIS IDEA THROUGH THE REMAINDER OF THE
SHORT TERM PERIOD AND INTO THE LONGER TERM FORECAST PERIOD...
GENERALLY RAISING TEMPS FOR THE GOING FORECAST...INCLUDING
WIDESPREAD LOW 90S FOR THE COMING WEEKEND. WITH THE 00Z GFS
INDICATING 850MB TEMPS CLIMBING TO 23C...LOW 90S COULD EVEN BE
CONSERVATIVE. AS FOR THUNDER POTENTIAL FOR LATER TODAY...HAVE
DROPPED ANY MENTION OF POPS OVER THE ENTIRE CWA BEFORE 18Z AND
WILL SLOW THE PROGRESSION OF PCPN ACROSS THE CWA FOR 18Z-00Z
PERIOD...REMOVING POPS FROM THE ERN SECTIONS...PARTICULARLY THE
NWRN INDIANA COUNTIES...THRU 00Z. MODEL SOUNDING INDICATE SOME
WEAK CAPPING OVER THE ERN LOCATIONS...BUT A DEVELOPING WARM
FRONTAL BOUNDARY CROSSING THE MISSISSIPPI RIVER INTO NWRN IL LATE
THIS AFTERNOON SHOULD PROVIDE ADEQUATE FOCUS FOR TS DEVELOPMENT
OVER THE FAR WRN PORTIONS OF THE CWA LATE THIS AFTERNOON. THE NAM
HAS SHOWN GOOD CONTINUITY ON HANDLING THIS FEATURE AND THE
ASSOCIATED MID LEVEL SHORT WAVE MOVING ACROSS NRN IL THIS
EVENING...SO HAVE TRENDED TOWARD THIS SOLUTION FOR TIMING OF
SWEEPING POPS ACROSS THE AREA TONIGHT. HAVE LIMITED POPS TO HIGHER
END CHANCE AS THERE IS STILL A CHANCE FOR A SPLIT IN THE MOST
INTENSE AND MOST ORGANIZED CONVECTION AS THE SYSTEM CURRENTLY OVER
THE SOUTH HIGH PLAINS LOOKS TO BE TRENDING MORE SOUTHERLY...OVER
CNTRL AND SRN ILLINOIS...WHILE THE NRN STREAM MCS ACTIVITY WILL
LIKELY AFFECT WISCONSIN. HOWEVER...THE ENVIRONMENT WILL HAVE ADEQUATE
OF HEAT AND HUMIDITY IN PLACE TO JUSTIFY THE POP FORECAST. TEMPS
SHOULD MODERATE A BIT BY THURSDAY AS A STRONG UPPER LOW CROSSES
SRN CANADA...TURNING UPPER FLOW MORE NWLY...BUT STRONG RIDGING
WILL QUICKLY BUILD IN BEHIND...BRINGING A SIGNIFICANT WARM UP FOR
FRIDAY AND INTO THE WEEKEND.
KREIN
&&
.AVIATION...
1236 PM CDT
FOR 18Z TAFS...MAIN CONCERN IS WINDS IN SHORT TERM AND CONVECTION
POTENTIAL AT TERMINALS NEXT 18 HOURS.
RELATIVELY STRONG...FOR LATE JULY...MID LEVEL CIRCULATION NOTED IN
RAOB/PROFILER/VAPOR DATA MOVING ACROSS LAKE WINNIPEG AREA OF
SOUTHEAST MANITOBA EARLY THIS AFTERNOON. MODEL GUIDANCE IN GOOD
AGREEMENT IN CONTINUING TO MOVE THIS FEATURE EAST THROUGH WEDNESDAY
MORNING WITH BEST MID LEVEL FORCING/HEIGHT FALLS TRANSLATING ACROSS
THE NORTHERN GREAT LAKES. RESULTING SURFACE PRESSURE FALLS ALSO
FOCUSED FROM NORTH CENTRAL WI TO LAKE SUPERIOR THIS AFTERNOON...
WITH WEAKER SOUTHEASTERLY GRADIENT ACROSS FORECAST AREA EXPECTED TO
TIGHTEN A BIT AND BECOME MORE SOUTHERLY WITH TIME. HIGHER RESOLUTION
SHORT TERM GUIDANCE INCLUDING NAM/RUC AND LOCALLY RUN NAM ALL
SUGGEST CURRENT SOUTHEAST FLOW/LAKE BREEZE WILL BE OVERCOME BY
SOUTHERLY WINDS BY MID AFTERNOON. MAIN AREA OF LOW PRESSURE MOVING
THROUGH ONTARIO OVERNIGHT/WEDNESDAY TRAILS ACTUAL COLD FRONT ACROSS
FORECAST AREA DURING THE MORNING HOURS WEDNESDAY...THOUGH GUIDANCE
SUGGESTS MORE OF A BROAD PRESSURE TROUGH AND GRADUAL WIND SHIFT FROM
SOUTHWEST TO WESTERLY WEDNESDAY MORNING. TRUE FROPA APPEARS 14-16Z
WITH WIND VEERING MORE NORTHWEST.
WITH RESPECT TO THUNDERSTORM POTENTIAL...UPSTREAM MORNING RAOBS
INDICATE RELATIVELY STEEP LAPSE RATES ABOVE 800 HPA OR SO...THOUGH
RECENT ACARS ASCENT SOUNDINGS FROM KORD/KRFD DEPICT MORE STABLE
THERMAL PROFILES FARTHER TO THE EAST. RUC/LOCAL NAM FORECAST
SOUNDINGS CONTINUE TO INDICATE RATHER MARGINAL LOW LEVEL LAPSE RATES
THROUGH THE AFTERNOON WHICH SUGGESTS ORGANIZED CONVECTION MAY HAVE A
TOUGH TIME DEVELOPING ACROSS TERMINALS. RADAR TRENDS HAVE INDICATED
A FEW RW/TRW THIS MORNING FROM IA/MO BORDER REGION INTO WESTERN IL
IN ISENTROPIC ASCENT REGION ALONG AXIS OF WEAK 20 KNOT LOW LEVEL
JET. 15Z SURFACE ANALYSIS INDICATES WEAK WARM FRONTAL FEATURE FROM
SOUTHEAST IA TO NEAR KSTL...WITH 925-850 HPA THERMAL
GRADIENT/ELEVATED WARM FRONT FROM IA TO CENTRAL IL WHICH HAS LIKELY
BEEN AIDING DEVELOPMENT OF ISOLATED CONVECTION...THOUGH THESE
FEATURES APPEAR TO BECOME MORE DIFFUSE WITH TIME PER RUC/NAM
FORECASTS. THUS WHILE ISOLATED/SCATTERED CONVECTION LIKELY TO OCCUR
NEAR AND ESPECIALLY WEST/SOUTHWEST OF TERMINALS THIS AFTERNOON...
LACK OF CLEAR LOW LEVEL FORCING/FOCUS YIELDS CONFIDENCE TOO LOW FOR
POINT FORECAST TAF INCLUSION AT THIS TIME. HAVE ELECTED HOWEVER TO
MENTION A VCSH WITH CB CLOUD GROUP FOR KRFD DURING PEAK DIURNAL
HEATING LATER THIS AFTERNOON.
FWC/MET GUIDANCE SUGGESTS SOME MVFR HAZE BEFORE/AROUND SUNRISE AND
THIS APPEARS REASONABLE GIVEN SURFACE DEW POINT TEMPS IN LOWER 70S
AND LIGHT SURFACE WINDS.
RATZER
&&
.MARINE...
151 AM CDT
RATHER LIGHT EAST TO SE WINDS THIS
MRNG SHUD VEER MORE TO THE S
TODAY AND PICK UP RATHER BRISKLY 15 KTS AND OCNL GUSTS TO 20KT
WITH A STRONGER PRESS GRADIENT BLDG IN BEHIND THIS RIDGE. A TROF
MOVING THIS WAY THRU MIDWEEK WILL PROBLY ARRIVE WEDNESDAY EVENING
AND VEER WINDS TO THE NW TO NORTH FOR LATE IN THE WEEK THURS. BUT
ON FRIDAY...WINDS SHUD BE COMING AROUND TO THE SOUTH AGAIN AFTER
ANOTHER RIDGE PASSAGE AND ANOTHER TROF APPROACHING FROM THE MS VLY
ON SATURDAY. WINDS SHUD VEER BACK TO THE NORTH OVER THE WEEKEND.
WITH THE TYPICAL SUMMER PATTERN...NO GALES IN SIGHT FOR THE NEXT
WEEK.
RLB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
909 PM EDT TUE JUL 29 2008
.SYNOPSIS...
HIGH PRESSURE OFF THE COAST WILL ALLOW FOR A RETURN OF WARMER AND
MORE HUMID CONDITIONS. A COLD FRONT OVER THE UPPER GREAT LAKES WILL
APPROACH THE REGION WEDNESDAY BEFORE PASSING THROUGH ON THURSDAY.
THIS WILL BRING THE CHANCE FOR SHOWERS AND THUNDERSTORMS. DRIER
AIR IS EXPECTED BEHIND THE FRONT LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
WATER VAPOR LOOP SHOWS A TROUGH SWINGING EAST INTO THE CANADIAN
MARITIMES AS RIDING BUILDS ACROSS THE OHIO VALLEY. A DUAL STREAM
SYSTEM WAS MARCHING EAST ACROSS THE CENTRAL CONUS...WITH UPPER LOWS
NORTH OF THE GREAT LAKES AND OVER THE PLAINS. ACARS 400-250MB WIND
OBSERVATIONS REVEAL A 50-100KT WESTERLY JET OVER THE UPPER
MIDWEST...WHICH TROUGHS OVER NEW ENGLAND. 19Z SURFACE ANALYSIS
PLACED A FRONTAL BOUNDARY FROM THE MIDWEST INTO THE TENNESSEE
VALLEY...NORTHEAST INTO THE DELMARVA. A TROUGH WAS LOCATED IN THE
LEE OF THE CENTRAL APPALACHIANS...WITH 1040MB ANTICYCLONE OVER THE
MOUNTAINS. A SECONDARY BOUNDARY WAS STALLING ACROSS THE LOWER GREAT
LAKES AND NEW ENGLAND.
CONVECTION HAS SHOWED A DOWNWARD DIURNAL TREND THIS EVENING. WHILE
09Z SREF INDICATES A HIGH PROBABILITY OF RETAINING GREATER THAN 250
J/KG OF MUCAPE OVERNIGHT...DOES NOT APPEAR TO BE A TRIGGER AS
RIDGING ALOFT SPREADS INTO THE REGION FROM THE OHIO VALLEY.
WITH SKIES CLEARING THIS EVENING...AND MOISTURE INCREASING NORTH OF
THE BAROCLINIC ZONE...ANTICIPATE AREAS OF FOG TO DEVELOP ESPECIALLY
ACROSS THE SOUTHEAST FORECAST AREA (NORTH OF THE BOUNDARY) AND IN
CLIMATOLOGICALLY FAVORED VALLEYS OUT WEST.
CONVECTION ONGOING ACROSS MIDWEST AHEAD OF NEXT DUAL STREAM SYSTEM
IS EXPECTED TO MOVE INTO THE OHIO VALLEY LATER TONIGHT. NAM/GFS SEEM
TO BE STRUGGLING WITH THIS DEPICTION...SO HAVE RELIED ON
EXPERIMENTAL HIGH RESOLUTION RAPID REFRESH RUC WRF-ARW3 FOR GUIDANCE
THROUGH 08Z. THIS ACTIVITY EXPECTED TO INCREASE HIGH LEVEL
CLOUDINESS LATE TONIGHT. IF MCV CAN HOLD TOGETHER AND ENOUGH WARMING
OCCURS AHEAD OF FEATURE...ORGANIZED CONVECTION WOULD BE POSSIBLE
WEDNESDAY. NEXT SHIFT SHOULD HAVE A BETTER HANDLE AS THINGS EVOLVE
UPSTREAM.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
DEPENDING UPON WHICH MDL YOU LOOK AT WED AFTN COULD BE FULL OF
XCTMNT OR RATEHR QUIET. NAM GIVING CAPES INXS OF 2000 WED AFTN
GIVEN THE LATE JUL HEAT/HUMIDITY. I`M UNSURE IF THERE WL BE A
TRIGGER TO MAKE WED AFTN MORE THAN SCT HVY RAINERS...WE`LL KEEP AN
EYE ON LATER MDL RUNS FOR CLARIFICATION. HIGHS WED IN LM 90S XCPT
IN HIGHLANDS.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
CONVECTION WITH THE TROUGH WEDNESDAY AFTERNOON WILL LINGER INTO THE
EVENING HOURS...WEAKENING INTO THE OVERNIGHT. THE ACTUAL COLD
FRONTAL PASSAGE ON THURSDAY WILL BRING THE LAST MENTIONABLE CHANCES
OF SHOWERS AND THUNDERSTORMS THROUGH THE FORECAST PERIOD. WHILE
WEDNESDAY APPEARS TO BE THE BEST CHANCES FOR SEVERE
WEATHER...THURSDAY COULD PROVIDE ITS OWN SET OF WEATHER CONCERNS.
NOTABLE SHEAR WITH CONTINUED HEAT AND HUMIDITY ALONG WITH THE COLD
FRONT WILL SUPPORT THUNDERSTORM DEVELOPMENT ON THURSDAY. TIMING
THURSDAY SHOULD WAIT UNTIL THE AFTERNOON WITH THE BEST HEATING...BUT
ANY OVERNIGHT ACTIVITY COULD SIMPLY CONTINUE INTO THURSDAY MORNING.
SPC STILL HAS THE REGION UNDER A SLIGHT RISK AREA. WILL CARRY CHANCE
POPS FOR THURSDAY WITH THE FRONT. THE FRONT IS EXPECTED TO BE EAST
OF THE FORECAST AREA BY THURSDAY NIGHT...BRINGING NORTHWEST WINDS
AND GRADUALLY CLEARING SKIES.
HIGH PRESSURE AT THE SURFACE WILL BUILD THURSDAY NIGHT INTO FRIDAY
AND LAST THROUGH MUCH OF THE FORECAST PERIOD. AS HIGH PRESSURE
BUILDS ALOFT LATER IN THE PERIOD...INCREASING TEMPERATURES ARE
POSSIBLE BY EARLY NEXT WEEK. WENT WITH THE COOLER HPC GUIDANCE FOR
NOW...BUT THE MEX NUMBERS ARE WARMER AND MAY BE THE TREND IN LATER
FORECASTS.
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
INCREASING MOISTURE SHOULD PROVE FAVORABLE FOR FOG DEVELOPMENT
OVERNIGHT...ESPECIALLY ALONG AND SE OF CHO-BWI LINE JUST NORTH OF
FRONTAL ZONE...AND CLIMATOLOGICAL VALLEY LOCATIONS OUT WEST.
VISIBILITIES EXPECTED TO DROP INTO IFR LATE TONIGHT. THUNDERSTORMS
ACROSS OHIO VALLEY LATE TONIGHT EXPECTED TO ENCOURAGE HIGH CLOUDS TO
MOVE INTO THE REGION TOMORROW...WITH SCATTERED CONVECTION POSSIBLE
BY AFTERNOON. WITH NOT A LOT OF CONFIDENCE OF HOW THIS SCENARIO WILL
PLAY OUT YET...SO HAVE INDICATED CONVECTIVE CHANCES WITH A CB GROUP
AT THIS TIME.
CONVECTION WILL BE ONGOING WEDNESDAY NIGHT AS THE SURFACE TROUGH
MOVES THROUGH. CONVECTION CHANCES WILL RETURN ON THURSDAY AS THE
COLD FRONT MOVES EAST. MVFR AND IFR CONDITIONS ARE POSSIBLE WITH
STORMS WEDNESDAY NIGHT AND THURSDAY. HIGH PRESSURE WILL BUILD FOR
THE WEEKEND.
&&
.MARINE...
SOUTHERLY FLOW INCREASES OVERNIGHT BUT IS NOT EXPECTED TO CROSS INTO
SMALL CRAFT ADVISORY CRITERIA.
SHOWERS AND THUNDERSTORMS WILL REMAIN IN THE FORECAST WEDNESDAY
NIGHT AND THURSDAY. SOME STORMS WILL BE STRONG TO
SEVERE...ESPECIALLY WEDNESDAY EVENING...PROMPTING SPECIAL MARINE
WARNINGS. HIGH PRESSURE WILL BUILD OVER THE WATERS FOR FRIDAY AND
CONTINUE THROUGH THE WEEKEND.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...WOODY!
NEAR TERM...ROGOWSKI
SHORT TERM...WOODY!
LONG TERM...SAR
AVIATION...ROGOWSKI/SAR
MARINE...ROGOWSKI/SAR
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1218 AM EDT TUE JUL 29 2008
LATEST UPDATE...AVIATION...
.SYNOPSIS...(330 PM EDT TUE JUL 29 2008)
A COLD FRONT WILL SWING THROUGH THE REGION LATER TONIGHT INTO
WEDNESDAY. THIS SYSTEM WILL PRODUCE SOME SHOWERS AND THUNDERSTORMS
ACROSS THE REGION. A DRIER AIRMASS ARRIVES FOR THE END OF THE
WEEK. A WARMING TREND OVER THE WEEKEND WILL LIKELY SEND
TEMPERATURES INTO THE 90S.
&&
.SHORT TERM...(330 PM EDT TUE JUL 29 2008)
(TONIGHT THROUGH THURSDAY NIGHT)
WHEN AND HOW MUCH RAINFALL ALONG WITH THE SEVERE WEATHER POTENTIAL
TONIGHT INTO WEDNESDAY ARE THE PRIMARY CONCERNS.
UP TO THIS POINT WARM TEMPERATURES AROUND 700 MB HAVE LIMITED THE
SHOWER AND THUNDERSTORM POTENTIAL. TAMDAR SOUNDINGS SHOW THIS
NICELY. HOWEVER THE ENVIRONMENT CHANGES TONIGHT. PRECIPITABLE WATER
VALUES WILL MAKE A RUN AT 2 INCHES AHEAD OF A COLD FRONT. THE
ATMOSPHERE WILL DESTABILIZE AS THIS DEEPER MOISTURE MOVES IN. THE
FRONT WILL CROSS SOUTHWEST LOWER MICHIGAN TONIGHT INTO WED AM. THE
FORCING ALONG THE FRONT WILL BE RELATIVELY WEAK AND ALL FORECAST
SOUNDINGS SHOW SOME INHIBITION TO LIFTED SURFACE PARCELS. AS A
RESULT UNCERTAINTY EXISTS AS TO WHETHER ENOUGH LIFT IS THERE FOR
PRECIPITATION. NO SIGNIFICANT LLJ IS SEEN EITHER. LOOKS LIKE SOME
TROPICAL MOISTURE FROM DOLLY WILL BE RIDING UP THE FRONT FROM KS SO
IF PRECIPITATION DOES GET GOING...IT COULD BE RATHER EFFICIENT AND
HEAVY. MY FEELING IS THAT WE WILL SEE SOME STORMS DEVELOP AND THAT
LOCALLY HEAVY RAINFALL WILL OCCUR. I WILL THEREFORE KEEP THE
PRECIPITATION IN THE FORECAST...DESPITE SOME DRY MODEL SOLUTIONS.
AS FOR SEVERE WEATHER...THE POTENTIAL LOOKS LIMITED WITH RELATIVELY
LIGHT WINDS THROUGH 500 MB. HOWEVER MID LEVEL LAPSE RATES ARE
STEEPER AND DECENT INSTABILITY WILL BE ARRIVING SO I WILL MAINTAIN
THE ISOLATED SEVERE POTENTIAL.
WILL KEEP THE MENTION OF SHOWERS AND THUNDERSTORMS IN THE FORECAST
FOR WED AM WITH THE FRONT SLOWLY PUSHING THROUGH. WE WILL DRY OUT
BY WED EVENING AND STAY THAT WAY THROUGH THURSDAY.
&&
.LONG TERM...(330 PM EDT TUE JUL 29 2008)
(FRIDAY THROUGH TUESDAY)
UPPER RIDGE MOVES EAST FROM THE PLAINS AND BRINGS ONE OR TWO
ACTUALLY HOT DAYS TO SOUTHERN LOWER MICHIGAN ON SUNDAY AND MAYBE
MONDAY. TWEAKED MAXES LOWER FOR SATURDAY AND HIGHER FOR SUNDAY BASED
ON TRENDS IN THE 12Z GUIDANCE. COLD FRONT SLOWLY SAGGING SOUTH MAY
TOUCH OFF SOME CONVECTION BEGINNING MONDAY WITH MCS DEVELOPMENT
POSSIBLE. LOW CONFIDENCE FORECAST FOR TEMPS AND PRECIP MONDAY AND
TUESDAY WITH THE FRONT LINGERING IN THE AREA AS THE RIDGE BREAKS
DOWN AND COOLER WEATHER MOVES IN LATE TUESDAY.
&&
.MARINE...(330 PM EDT TUE JUL 29 2008)
THUNDERSTORMS TONIGHT WILL BE THE MAIN HAZARD WITH SOME CLOUD TO
WATER LIGHTNING STRIKES AND LOCALLY GUSTY WINDS. WINDS AND WAVES ARE
EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY THROUGH WEDNESDAY.
WITH THE HIGHER DEWPOINTS MOVING IN...FOG COULD DEVELOP ON LAKE MI.
&&
.AVIATION...(1218 AM EDT TUE JUL 29 2008)
OUTSIDE OF ANY ISOLATED SHOWERS/TSTMS OVERNIGHT AND WED MORNING...
VFR CONDITIONS WILL PREVAIL. A BAND OF STRATOCUMULUS... POSSIBLY
WITH MVFR CIGS... WILL LIKELY PRECEDE/ACCOMPANY THE SURFACE FRONT
FOR 4 TO 6 HOURS WEDNESDAY MORNING... BUT THAT WILL BE MIXED OUT BY
18Z OR SO AS DRIER AIR ARRIVES FROM THE WEST. WEST WINDS MAY BECOME
GUSTY AFTER 18Z WED AS DEEPER MIXING DEVELOPS WITHIN CYCLONIC FLOW.
&&
.HYDROLOGY...(330 PM EDT TUE JUL 29 2008)
THE COMBINATION OF HIGH PRECIPITABLE WATER AIR...AN UNSTABLE
ENVIRONMENT AND A COLD FRONT PRESSING INTO THE REGION SUPPORTS
THUNDERSTORMS WITH LOCALLY HEAVY RAINFALL. WITH THE FRONT TO MOVE
RATHER SLOWLY...THIS SUGGESTS THAT SEVERAL IN INCHES OF RAIN COULD
FALL IN A SHORT PERIOD OF TIME. THIS MAY LEAD TO SOME URBAN AND
POOR DRAINAGE FLOODING.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
SYNOPSIS: MJS
SHORT TERM: MJS
LONG TERM: OSTUNO
MARINE: MJS
AVIATION: MEADE
HYDROLOGY: MJS
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
810 PM EDT TUE JUL 29 2008
LATEST UPDATE...AVIATION...
.SYNOPSIS...(330 PM EDT TUE JUL 29 2008)
A COLD FRONT WILL SWING THROUGH THE REGION LATER TONIGHT INTO
WEDNESDAY. THIS SYSTEM WILL PRODUCE SOME SHOWERS AND THUNDERSTORMS
ACROSS THE REGION. A DRIER AIRMASS ARRIVES FOR THE END OF THE
WEEK. A WARMING TREND OVER THE WEEKEND WILL LIKELY SEND
TEMPERATURES INTO THE 90S.
&&
.SHORT TERM...(330 PM EDT TUE JUL 29 2008)
(TONIGHT THROUGH THURSDAY NIGHT)
WHEN AND HOW MUCH RAINFALL ALONG WITH THE SEVERE WEATHER POTENTIAL
TONIGHT INTO WEDNESDAY ARE THE PRIMARY CONCERNS.
UP TO THIS POINT WARM TEMPERATURES AROUND 700 MB HAVE LIMITED THE
SHOWER AND THUNDERSTORM POTENTIAL. TAMDAR SOUNDINGS SHOW THIS
NICELY. HOWEVER THE ENVIRONMENT CHANGES TONIGHT. PRECIPITABLE WATER
VALUES WILL MAKE A RUN AT 2 INCHES AHEAD OF A COLD FRONT. THE
ATMOSPHERE WILL DESTABILIZE AS THIS DEEPER MOISTURE MOVES IN. THE
FRONT WILL CROSS SOUTHWEST LOWER MICHIGAN TONIGHT INTO WED AM. THE
FORCING ALONG THE FRONT WILL BE RELATIVELY WEAK AND ALL FORECAST
SOUNDINGS SHOW SOME INHIBITION TO LIFTED SURFACE PARCELS. AS A
RESULT UNCERTAINTY EXISTS AS TO WHETHER ENOUGH LIFT IS THERE FOR
PRECIPITATION. NO SIGNIFICANT LLJ IS SEEN EITHER. LOOKS LIKE SOME
TROPICAL MOISTURE FROM DOLLY WILL BE RIDING UP THE FRONT FROM KS SO
IF PRECIPITATION DOES GET GOING...IT COULD BE RATHER EFFICIENT AND
HEAVY. MY FEELING IS THAT WE WILL SEE SOME STORMS DEVELOP AND THAT
LOCALLY HEAVY RAINFALL WILL OCCUR. I WILL THEREFORE KEEP THE
PRECIPITATION IN THE FORECAST...DESPITE SOME DRY MODEL SOLUTIONS.
AS FOR SEVERE WEATHER...THE POTENTIAL LOOKS LIMITED WITH RELATIVELY
LIGHT WINDS THROUGH 500 MB. HOWEVER MID LEVEL LAPSE RATES ARE
STEEPER AND DECENT INSTABILITY WILL BE ARRIVING SO I WILL MAINTAIN
THE ISOLATED SEVERE POTENTIAL.
WILL KEEP THE MENTION OF SHOWERS AND THUNDERSTORMS IN THE FORECAST
FOR WED AM WITH THE FRONT SLOWLY PUSHING THROUGH. WE WILL DRY OUT
BY WED EVENING AND STAY THAT WAY THROUGH THURSDAY.
&&
.LONG TERM...(330 PM EDT TUE JUL 29 2008)
(FRIDAY THROUGH TUESDAY)
UPPER RIDGE MOVES EAST FROM THE PLAINS AND BRINGS ONE OR TWO
ACTUALLY HOT DAYS TO SOUTHERN LOWER MICHIGAN ON SUNDAY AND MAYBE
MONDAY. TWEAKED MAXES LOWER FOR SATURDAY AND HIGHER FOR SUNDAY BASED
ON TRENDS IN THE 12Z GUIDANCE. COLD FRONT SLOWLY SAGGING SOUTH MAY
TOUCH OFF SOME CONVECTION BEGINNING MONDAY WITH MCS DEVELOPMENT
POSSIBLE. LOW CONFIDENCE FORECAST FOR TEMPS AND PRECIP MONDAY AND
TUESDAY WITH THE FRONT LINGERING IN THE AREA AS THE RIDGE BREAKS
DOWN AND COOLER WEATHER MOVES IN LATE TUESDAY.
&&
.MARINE...(330 PM EDT TUE JUL 29 2008)
THUNDERSTORMS TONIGHT WILL BE THE MAIN HAZARD WITH SOME CLOUD TO
WATER LIGHTNING STRIKES AND LOCALLY GUSTY WINDS. WINDS AND WAVES ARE
EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY THROUGH WEDNESDAY.
WITH THE HIGHER DEWPOINTS MOVING IN...FOG COULD DEVELOP ON LAKE MI.
&&
.AVIATION...(810 PM EDT TUE JUL 29 2008)
PROBABILITY/TIMING OF TSTMS TONIGHT IS THE PRIMARY CONCERN... AND
UNFORTUNATELY CONFIDENCE IS STILL QUITE LOW IN THIS REGARD.
BELIEVE THAT SOME SCATTERED CONVECTION WILL INITIATE ALONG THE LAKE
MICHIGAN SHORELINE AROUND 02-03Z AS THE SHARP H8 DEW POINT/THETA-E
GRADIENT COMES IN. THIS OUGHT TO HELP BREAK DOWN THE STRONG
CONVECTIVE INHIBITION CURRENTLY IN PLACE. THEN AS THE POOL OF 16-17C
H8 DEW POINTS CONTINUES SPREADING EASTWARD THROUGH 06Z... THE
SCATTERED CONVECTION SHOULD AS WELL.
THE TROUBLING THING IS THAT THE H8 FLOW IS RATHER QUICK TO VEER
WESTERLY AFTER 06Z... WHICH ESSENTIALLY KILLS THE BETTER H8
CONVERGENCE AND SHUNS THE HIGHER H8 THETA-E AIR TO THE EAST. ALL
THINGS CONSIDERED... THERE WILL PROBABLY BE SOME SCATTERED
CONVECTION IN THE VICINITY OF THE TAF SITES TONIGHT... ENDING FROM
WEST TO EAST BETWEEN 08Z AND 12Z.
OUTSIDE OF ANY SHOWERS/TSTMS... VFR CONDITIONS WILL PREVAIL. A BAND
OF VFR BKN STRATOCUMULUS AROUND 5K FEET WILL LIKELY
PRECEDE/ACCOMPANY THE SURFACE FRONT... BUT THAT WILL BE MIXED OUT
WEDNESDAY AS DRIER AIR ARRIVES FROM THE WEST. WEST WINDS MAY BECOME
GUSTY AFTER 18Z WED AS DEEPER MIXING DEVELOPS WITHIN CYCLONIC FLOW.
&&
.HYDROLOGY...(330 PM EDT TUE JUL 29 2008)
THE COMBINATION OF HIGH PRECIPITABLE WATER AIR...AN UNSTABLE
ENVIRONMENT AND A COLD FRONT PRESSING INTO THE REGION SUPPORTS
THUNDERSTORMS WITH LOCALLY HEAVY RAINFALL. WITH THE FRONT TO MOVE
RATHER SLOWLY...THIS SUGGESTS THAT SEVERAL IN INCHES OF RAIN COULD
FALL IN A SHORT PERIOD OF TIME. THIS MAY LEAD TO SOME URBAN AND
POOR DRAINAGE FLOODING.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
SYNOPSIS: MJS
SHORT TERM: MJS
LONG TERM: OSTUNO
MARINE: MJS
AVIATION: MEADE
HYDROLOGY: MJS
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
721 PM EDT TUE JUL 29 2008
.AVIATION...
VFR CONDITIONS ARE EXPECTED THIS EVENING...BUT SCATTERED SHOWERS OR
THUNDERSTORMS WILL SPREAD INTO THE AREA LATE TONIGHT...BRINGING AT
LEAST A FEW HOURS OF MARGINAL MVFR CEILINGS AND/OR VISIBILITIES. BY
WEDNESDAY...THIS ACTIVITY WILL MOVE EAST OF THE REGION...WITH ONLY
SCATTERED TO BROKEN CU/STRATO-CU INTO THE MIDDLE OF THE DAY. WINDS
WILL INCREASE FROM THE SOUTHWEST INTO THE AFTERNOON AND THEN SHIFT
TO THE WEST/NORTHWEST AS A COLD FRONT PROGRESSES THROUGH THE AREA.
&&
.PREV DISCUSSION...ISSUED 358 PM EDT TUE JUL 29 2008
THE 12Z DTX SOUNDING SHOWED RELATIVELY WARM AND DRY MID
LEVELS...WITH A 10 C TEMP NOTED AROUND 740 MB. WATER VAPOR IMAGERY
SHOWED FURTHER MID LEVEL RIDGING DURING THE DAY...WHICH HAS
CONTINUED TO WARM THE MID LEVELS (PER DTW ACARS). THESE WARM MID
LEVELS (10C+ FROM 700-775 MB) SHOULD CONTINUE TO CAP/SUPPRESS
ACTIVITY INTO THE EVENING HOURS WITH MAX TEMPS REMAINING BELOW 90
DEGREES OVER MOSTLY LOW/MID 60 DEW POINTS. NONE-THE-LESS...THERE IS
AN OUTSIDE CHANCE SOMETHING COULD GO UP ALONG LINGERING SURFACE
TROUGH/POSSIBLE LAKE BREEZE OVER THE THUMB REGION...PROVIDING THE
NEEDED LOW LEVEL MOISTURE POOLING/CONVERGENCE BOOST NEEDED TO BYPASS
THE CAP WITH MLCAPES OF 500+ J/KG NOTED AT 19Z.
BETTER CHANCE OF THUNDERSTORMS OVERNIGHT AS WEAKENING COLD FRONT
ARRIVES LATE TONIGHT. EVEN THEN...DON`T SEE MUCH MORE THAN A
SCATTERED LINE OF CONVECTION WITH MODEST HEIGHT FALLS AND WEAK LOW
LEVEL CONVERGENCE. SURFACE BASED INSTABILITY WILL QUICKLY BE ON THE
WANE...BUT STILL WILL HAVE AROUND 1000 J/KG OF CAPE COMPUTED AT 850
MB (PER 12Z GFS). WITH FREEZING LEVELS IN EXCESS OF 14000 FEET AND
0-6 KM BULK SHEAR REMAINING PREDOMINATELY 25 KNOTS OR LESS...NOT
ANTICIPATING SEVERE STORMS. ALSO...DID BROAD BRUSH THE ENTIRE CWA
WITH A 40 POP OVERNIGHT...AS A JET STREAK/UPPER WAVE IS SEEN MOVING
THROUGH THE NORTHERN OHIO VALLEY.
LONG TERM...WEDNESDAY THROUGH NEXT TUESDAY
SURFACE TROUGH WILL EXIT EAST INTO ONTARIO BY EARLY WEDNESDAY
AFTERNOON. INSTABILITY WILL BE WANING FOR THE FIRST HALF OF THE DAY
TOMORROW PER GFS/NAM...AND EXPECT TO ONLY SEE SHOWERS AND A FEW
THUNDERSTORMS AROUND...WITH CHANCES FOR PRECIPITATION DECREASING
THROUGH THE DAY AS DRIER AIR ON WATER VAPOR OUT TO OUR WEST ADVECTS
INTO MICHIGAN. MAIN COLD FRONT ASSOCIATED WITH THE LOW PRESSURE
SYSTEM MOVING ACROSS ONTARIO WILL FINALLY PUSH DOWN THROUGH
SOUTHEAST MICHIGAN TOMORROW NIGHT. THE FRONT WILL ONLY PROVIDE WEAK
FORCING...AND CONSIDERING LIMITED MOISTURE AVAILABLE...FORECAST
AFTER 400 PM TOMORROW REMAINS DRY. TEMPERATURES TOMORROW AHEAD OF
THE MAIN COLD FRONT WILL PEAK AT NEAR 90 DEGREES.
UPPER RIDGING WILL START TO EXTEND OVER THE GREAT LAKES ON
THURSDAY...ALLOWING SURFACE HIGH PRESSURE TO BUILD OVERHEAD
THURSDAY/THURSDAY NIGHT. THIS WILL PROVIDE DRY WEATHER DURING THIS
PERIOD...WITH LOWER HUMIDITY ALLOWING ONLY SLIGHTLY COOLER
TEMPERATURES TO ACTUALLY FEEL COOLER.
SURFACE HIGH PRESSURE WILL REMAIN CENTERED JUST TO OUR EAST ON
FRIDAY...BUT MORNING RUNS OF THE NAM/GFS BOTH HINT AT AN MCS
CLIPPING SOUTHERN LOWER MICHIGAN AS IT DIVES DOWN THE PERIPHERY OF
THE UPPER RIDGE TO OUR WEST. WILL NOT ADD POPS TO THE FORECAST...BUT
KEEP AN EYE ON THIS SCENARIO AS WARM FRONT LOOKS TO BE APPROACHING
SOUTHWEST MICHIGAN BY FRIDAY MORNING.
FORECAST FOR THE WEEKEND BEYOND IS STILL LOOKING UNCERTAIN AS MODELS
STRUGGLE TO HANDLE EVOLUTION OF UPPER LEVEL ENERGY OVER CANADA.
EURO/GFS HAVE SOME IDEA OF A WARM FRONT LIFTING ACROSS LOWER
MICHIGAN SATURDAY/SATURDAY NIGHT...BUT WITH LITTLE FANFARE AS
MOISTURE FIELDS AND ISENTROPIC LIFT LOOK WEAK. LATEST CONSENSUS
PUSHES A COLD FRONT DOWN INTO THE REGION FROM THE NORTH LATE ON
SUNDAY...THEN STALL THE FRONT OVER LOWER MICHIGAN MONDAY AND
TUESDAY. THIS COULD BRING AN EXTENDED PERIOD OF HOT...HUMID...AND
POTENTIALLY ACTIVE WEATHER TO SOUTHEAST MICHIGAN FOR THE BEGINNING
OF NEXT WEEK. SINCE MODELS ARE JUST STARTING TO COME TO A CONSENSUS
FOR DAYS 6 AND 7...WILL KEEP POPS RELATIVELY LOW FOR NOW.
MARINE...
A WEAKENING COLD FRONT MOVING INTO THE CENTRAL GREAT LAKES WILL
BRING A CHANCE OF THUNDERSTORMS TONIGHT INTO TOMORROW. WINDS WILL
REMAIN PREDOMINATELY BELOW 20 KNOTS IN BEHIND THE FRONT AS THEY VEER
AROUND TO THE WEST ON WEDNESDAY...AND THEN NORTHWEST WEDNESDAY
NIGHT. WINDS WILL THEN BECOME LIGHT AND VARIABLE AS WE HEAD INTO
FRIDAY AS HIGH PRESSURE RETURNS.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....DG
SHORT TERM...SF
LONG TERM....HLO
MARINE.......SF
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
358 PM EDT TUE JUL 29 2008
.SHORT TERM...TONIGHT
THE 12Z DTX SOUNDING SHOWED RELATIVELY WARM AND DRY MID
LEVELS...WITH A 10 C TEMP NOTED AROUND 740 MB. WATER VAPOR IMAGERY
SHOWED FURTHER MID LEVEL RIDGING DURING THE DAY...WHICH HAS
CONTINUED TO WARM THE MID LEVELS (PER DTW ACARS). THESE WARM MID
LEVELS (10C+ FROM 700-775 MB) SHOULD CONTINUE TO CAP/SUPPRESS
ACTIVITY INTO THE EVENING HOURS WITH MAX TEMPS REMAINING BELOW 90
DEGREES OVER MOSTLY LOW/MID 60 DEW POINTS. NONE-THE-LESS...THERE IS
AN OUTSIDE CHANCE SOMETHING COULD GO UP ALONG LINGERING SURFACE
TROUGH/POSSIBLE LAKE BREEZE OVER THE THUMB REGION...PROVIDING THE
NEEDED LOW LEVEL MOISTURE POOLING/CONVERGENCE BOOST NEEDED TO BYPASS
THE CAP WITH MLCAPES OF 500+ J/KG NOTED AT 19Z.
BETTER CHANCE OF THUNDERSTORMS OVERNIGHT AS WEAKENING COLD FRONT
ARRIVES LATE TONIGHT. EVEN THEN...DON`T SEE MUCH MORE THAN A
SCATTERED LINE OF CONVECTION WITH MODEST HEIGHT FALLS AND WEAK LOW
LEVEL CONVERGENCE. SURFACE BASED INSTABILITY WILL QUICKLY BE ON THE
WANE...BUT STILL WILL HAVE AROUND 1000 J/KG OF CAPE COMPUTED AT 850
MB (PER 12Z GFS). WITH FREEZING LEVELS IN EXCESS OF 14000 FEET AND
0-6 KM BULK SHEAR REMAINING PREDOMINATELY 25 KNOTS OR LESS...NOT
ANTICIPATING SEVERE STORMS. ALSO...DID BROAD BRUSH THE ENTIRE CWA
WITH A 40 POP OVERNIGHT...AS A JET STREAK/UPPER WAVE IS SEEN MOVING
THROUGH THE NORTHERN OHIO VALLEY.
&&
.LONG TERM...WEDNESDAY THROUGH NEXT TUESDAY
SURFACE TROUGH WILL EXIT EAST INTO ONTARIO BY EARLY WEDNESDAY
AFTERNOON. INSTABILITY WILL BE WANING FOR THE FIRST HALF OF THE DAY
TOMORROW PER GFS/NAM...AND EXPECT TO ONLY SEE SHOWERS AND A FEW
THUNDERSTORMS AROUND...WITH CHANCES FOR PRECIPITATION DECREASING
THROUGH THE DAY AS DRIER AIR ON WATER VAPOR OUT TO OUR WEST ADVECTS
INTO MICHIGAN. MAIN COLD FRONT ASSOCIATED WITH THE LOW PRESSURE
SYSTEM MOVING ACROSS ONTARIO WILL FINALLY PUSH DOWN THROUGH
SOUTHEAST MICHIGAN TOMORROW NIGHT. THE FRONT WILL ONLY PROVIDE WEAK
FORCING...AND CONSIDERING LIMITED MOISTURE AVAILABLE...FORECAST
AFTER 400 PM TOMORROW REMAINS DRY. TEMPERATURES TOMORROW AHEAD OF
THE MAIN COLD FRONT WILL PEAK AT NEAR 90 DEGREES.
UPPER RIDGING WILL START TO EXTEND OVER THE GREAT LAKES ON
THURSDAY...ALLOWING SURFACE HIGH PRESSURE TO BUILD OVERHEAD
THURSDAY/THURSDAY NIGHT. THIS WILL PROVIDE DRY WEATHER DURING THIS
PERIOD...WITH LOWER HUMIDITY ALLOWING ONLY SLIGHTLY COOLER
TEMPERATURES TO ACTUALLY FEEL COOLER.
SURFACE HIGH PRESSURE WILL REMAIN CENTERED JUST TO OUR EAST ON
FRIDAY...BUT MORNING RUNS OF THE NAM/GFS BOTH HINT AT AN MCS
CLIPPING SOUTHERN LOWER MICHIGAN AS IT DIVES DOWN THE PERIPHERY OF
THE UPPER RIDGE TO OUR WEST. WILL NOT ADD POPS TO THE FORECAST...BUT
KEEP AN EYE ON THIS SCENARIO AS WARM FRONT LOOKS TO BE APPROACHING
SOUTHWEST MICHIGAN BY FRIDAY MORNING.
FORECAST FOR THE WEEKEND BEYOND IS STILL LOOKING UNCERTAIN AS MODELS
STRUGGLE TO HANDLE EVOLUTION OF UPPER LEVEL ENERGY OVER CANADA.
EURO/GFS HAVE SOME IDEA OF A WARM FRONT LIFTING ACROSS LOWER
MICHIGAN SATURDAY/SATURDAY NIGHT...BUT WITH LITTLE FANFARE AS
MOISTURE FIELDS AND ISENTROPIC LIFT LOOK WEAK. LATEST CONSENSUS
PUSHES A COLD FRONT DOWN INTO THE REGION FROM THE NORTH LATE ON
SUNDAY...THEN STALL THE FRONT OVER LOWER MICHIGAN MONDAY AND
TUESDAY. THIS COULD BRING AN EXTENDED PERIOD OF HOT...HUMID...AND
POTENTIALLY ACTIVE WEATHER TO SOUTHEAST MICHIGAN FOR THE BEGINNING
OF NEXT WEEK. SINCE MODELS ARE JUST STARTING TO COME TO A CONSENSUS
FOR DAYS 6 AND 7...WILL KEEP POPS RELATIVELY LOW FOR NOW.
&&
.MARINE...
A WEAKENING COLD FRONT MOVING INTO THE CENTRAL GREAT LAKES WILL
BRING A CHANCE OF THUNDERSTORMS TONIGHT INTO TOMORROW. WINDS WILL
REMAIN PREDOMINATELY BELOW 20 KNOTS IN BEHIND THE FRONT AS THEY VEER
AROUND TO THE WEST ON WEDNESDAY...AND THEN NORTHWEST WEDNESDAY
NIGHT. WINDS WILL THEN BECOME LIGHT AND VARIABLE AS WE HEAD INTO
FRIDAY AS HIGH PRESSURE RETURNS.
&&
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
SHORT TERM...SF
LONG TERM....HLO
MARINE.......SF
AVIATION.....SF
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
330 PM EDT TUE JUL 29 2008
LATEST UPDATE...SYNOPSIS SHORT TERM MARINE HYDROLOGY LONG TERM...
.SYNOPSIS...(330 PM EDT TUE JUL 29 2008)
A COLD FRONT WILL SWING THROUGH THE REGION LATER TONIGHT INTO
WEDNESDAY. THIS SYSTEM WILL PRODUCE SOME SHOWERS AND THUNDERSTORMS
ACROSS THE REGION. A DRIER AIRMASS ARRIVES FOR THE END OF THE
WEEK. A WARMING TREND OVER THE WEEKEND WILL LIKELY SEND
TEMPERATURES INTO THE 90S.
&&
.SHORT TERM...(330 PM EDT TUE JUL 29 2008)
(TONIGHT THROUGH THURSDAY NIGHT)
WHEN AND HOW MUCH RAINFALL ALONG WITH THE SEVERE WEATHER POTENTIAL
TONIGHT INTO WEDNESDAY ARE THE PRIMARY CONCERNS.
UP TO THIS POINT WARM TEMPERATURES AROUND 700 MB HAVE LIMITED THE
SHOWER AND THUNDERSTORM POTENTIAL. TAMDAR SOUNDINGS SHOW THIS
NICELY. HOWEVER THE ENVIRONMENT CHANGES TONIGHT. PRECIPITABLE WATER
VALUES WILL MAKE A RUN AT 2 INCHES AHEAD OF A COLD FRONT. THE
ATMOSPHERE WILL DESTABILIZE AS THIS DEEPER MOISTURE MOVES IN. THE
FRONT WILL CROSS SOUTHWEST LOWER MICHIGAN TONIGHT INTO WED AM. THE
FORCING ALONG THE FRONT WILL BE RELATIVELY WEAK AND ALL FORECAST
SOUNDINGS SHOW SOME INHIBITION TO LIFTED SURFACE PARCELS. AS A
RESULT UNCERTAINTY EXISTS AS TO WHETHER ENOUGH LIFT IS THERE FOR
PRECIPITATION. NO SIGNIFICANT LLJ IS SEEN EITHER. LOOKS LIKE SOME
TROPICAL MOISTURE FROM DOLLY WILL BE RIDING UP THE FRONT FROM KS SO
IF PRECIPITATION DOES GET GOING...IT COULD BE RATHER EFFICIENT AND
HEAVY. MY FEELING IS THAT WE WILL SEE SOME STORMS DEVELOP AND THAT
LOCALLY HEAVY RAINFALL WILL OCCUR. I WILL THEREFORE KEEP THE
PRECIPITATION IN THE FORECAST...DESPITE SOME DRY MODEL SOLUTIONS.
AS FOR SEVERE WEATHER...THE POTENTIAL LOOKS LIMITED WITH RELATIVELY
LIGHT WINDS THROUGH 500 MB. HOWEVER MID LEVEL LAPSE RATES ARE
STEEPER AND DECENT INSTABILITY WILL BE ARRIVING SO I WILL MAINTAIN
THE ISOLATED SEVERE POTENTIAL.
WILL KEEP THE MENTION OF SHOWERS AND THUNDERSTORMS IN THE FORECAST
FOR WED AM WITH THE FRONT SLOWLY PUSHING THROUGH. WE WILL DRY OUT
BY WED EVENING AND STAY THAT WAY THROUGH THURSDAY.
&&
.LONG TERM...(330 PM EDT TUE JUL 29 2008)
(FRIDAY THROUGH TUESDAY)
UPPER RIDGE MOVES EAST FROM THE PLAINS AND BRINGS ONE OR TWO
ACTUALLY HOT DAYS TO SOUTHERN LOWER MICHIGAN ON SUNDAY AND MAYBE
MONDAY. TWEAKED MAXES LOWER FOR SATURDAY AND HIGHER FOR SUNDAY BASED
ON TRENDS IN THE 12Z GUIDANCE. COLD FRONT SLOWLY SAGGING SOUTH MAY
TOUCH OFF SOME CONVECTION BEGINNING MONDAY WITH MCS DEVELOPMENT
POSSIBLE. LOW CONFIDENCE FORECAST FOR TEMPS AND PRECIP MONDAY AND
TUESDAY WITH THE FRONT LINGERING IN THE AREA AS THE RIDGE BREAKS
DOWN AND COOLER WEATHER MOVES IN LATE TUESDAY.
&&
.MARINE...(330 PM EDT TUE JUL 29 2008)
THUNDERSTORMS TONIGHT WILL BE THE MAIN HAZARD WITH SOME CLOUD TO
WATER LIGHTNING STRIKES AND LOCALLY GUSTY WINDS. WINDS AND WAVES ARE
EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY THROUGH WEDNESDAY.
WITH THE HIGHER DEWPOINTS MOVING IN...FOG COULD DEVELOP ON LAKE MI.
&&
.AVIATION...(1225 PM EDT TUE JUL 29 2008)
VFR CONDITIONS WITH ONLY SOME HIGH CLOUDS THIS AFTERNOON THEN
SCATTERED THUNDERSTORMS BETWEEN 03Z AND 09Z. IT WILL BE HIT AND MISS
TYPE STORMS AS A COLD FRONT GOES THROUGH OVERNIGHT WITH CLEARING ON
WEDNESDAY.
&&
.HYDROLOGY...(330 PM EDT TUE JUL 29 2008)
THE COMBINATION OF HIGH PRECIPITABLE WATER AIR...AN UNSTABLE
ENVIRONMENT AND A COLD FRONT PRESSING INTO THE REGION SUPPORTS
THUNDERSTORMS WITH LOCALLY HEAVY RAINFALL. WITH THE FRONT TO MOVE
RATHER SLOWLY...THIS SUGGESTS THAT SEVERAL IN INCHES OF RAIN COULD
FALL IN A SHORT PERIOD OF TIME. THIS MAY LEAD TO SOME URBAN AND
POOR DRAINAGE FLOODING.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
SYNOPSIS: MJS
SHORT TERM: MJS
LONG TERM: OSTUNO
MARINE: MJS
AVIATION: OSTUNO
HYDROLOGY: MJS
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
154 PM EDT TUE JUL 29 2008
.SYNOPSIS...
HIGH PRESSURE WILL BRING WARM AND DRY CONDITIONS THROUGH TONIGHT.
BY TOMORROW AFTERNOON A TROUGH OF LOW PRESSURE IN THE UPPER ATMOSPHERE
WILL DIP INTO NEW YORK STATE. THIS WILL BRING SCATTERED
THUNDERSTORMS TO NY AND PA THROUGH EARLY THURSDAY. HIGH PRESSURE
WILL BUILD IN AGAIN BY THE WEEKEND WITH ABOVE NORMAL TEMPERATURES
POSSIBLE.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1045 AM EDT...
HIGH PRESSURE CONTINUES TO BUILD INTO CNTRL NY THIS MRNG. STILL
FEELING AFFECT OF TROF ACRS FAR NORTH WITH LOW CLDS ACRS THE
MOHAWK VALLEY THIS MRNG. AS HIGH BUILDS IN THEY SHUD GRADUALLY
SCATTER OUT BY EARLY AFTN. HV ADDED A FEW SPRINKLES TO THE GRIDS
FOR ONEIDA CNTY THIS MRNG BUT NOT EXPECTING MUCH MORE THAN THAT.
RISING HEIGHTS WILL EFFECTIVELY SHUT OFF ANY CHCS FOR PCPN
TODAY...AS ACARS DATA FROM THE REGION AND BUFKIT SNDGS INDICATE
GOOD CAPPING ARND H7 TODAY.
TEMPS STARTING OUT SIMILAR TO WHERE THEY WERE YESTERDAY SO
EXPECTING ANOTHER DAY IN THE L/M 80S. UPDATED GRIDS AND TEXT
PRODUCTS ARE OUT THE DOOR. ONLY MINOR TWEAKS NEEDED TO FCST THIS
MRNG AS EVERYTHING LOOKS TO BE IN GOOD SHAPE.
PREV DISCUSSION...
UL WAVE WHICH CROSSED SFC COLD FRONT/TROF LAST EVENING IS EXITING
EASTWARD. PRECIPITATION IS RAPIDLY DISSIPATING AS IT EJECTS INTO
NEW ENGLAND. WE FORECAST FAIR WEATHER THROUGH THIS MORNING, WITH
FOG BEGINNING TO FORM BETWEEN 8Z AND 12Z.
UL TROF SLIDES EASTWARD TODAY, ALLOWING BUILDING HEIGHTS ALOFT.
THIS SHOULD STABILIZE THE ATMOSPHERIC PROFILE, AND ALLOW FOR A
PRECIPITATION FREE DAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
MODELS ARE SLOWER AND FARTHER NORTH WITH THE ONSET OF NEXT WAVE.
WE HAVE PULLED BACK ON POPS FOR THE FIRST HALF OF WEDNESDAY, AND
STUCK TO SCT-CHC POPS DURING THE AFTERNOON AND EVENING. COLD POOL
IS NOT AS STRONG AS PREVIOUS EVENTS, SO DO NOT ANTICIPATE ANOTHER
WIDESPREAD SEVERE EVENT. HOWEVER IT DOES APPEAR COLD/DRY ENOUGH
ALOFT TO SUPPORT HAIL WITH ANY STRONG CONVECTION.
CAPES ARE FORECAST TO BE AROUND 1000 J/KG, BUT WITH A WEAK WIND
FIELD. A FEW PULSE SEVERE ARE ALWAYS POSSIBLE IN SUCH AN
ENVIRONMENT, BUT STRONG/SEVERE SHOULD BE RATHER ISOLATED THIS TIME
AROUND.
COLD FRONT PASSES ON THURSDAY WITH UL COLD POOL SLIDING ACROSS
NORTHERN NY STATE. THIS SHOULD PROVIDE ANOTHER ROUND OF
THUNDERSTORMS BEFORE DRIER AIR RETURNS LATE.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
FEW CHANGES TO THE EXTENDED THIS MORNING. SAME PATTERN AS THE PAST
WEEK. COUPLE DAYS OF SHOWERS THEN A BREAK. COOLER THAN NORMAL.
PREVIOUS DISCUSSION...EXTENDED PERIOD SEES THE PERSISTENT
NORTHEASTERN UL TROF SLIDE FROM THE GREAT LAKES REGION TO QUEBEC
AND NEW ENGLAND. THIS PATTERN WILL ALLOW FOR SCATTERED MAINLY
AFTERNOON AND EVENING THUNDERSTORMS EACH DAY THURSDAY THROUGH
SATURDAY WITH NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES. A HIGH
PRESSURE RIDGE MAY BUILD IN FROM THE WEST EARLY NEXT WEEK BRINGING
WARMER WEATHER.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
EXCEPT FOR MORNING FOG ISSUES TAF PERIOD WILL BE VFR. SCT/BKN CU
AROUND 4K FT THROUGH SUNSET THEN JUST CIRRUS OVERNIGHT. WEDNESDAY
WITH APPROACHING UPPER LEVEL DISTURBANCE EXPECT FEW/SCT CU WITH
SCT/BKN MID CLOUDS.
FOR KRME/KITH/KAVP WENT WITH MVFR FOG BTW 09Z-12Z. FOR ELM
CONDITIONS ONCE AGAIN LOOK FAVORABLE FOR FOG FORMATION. CROSS OVER
TEMP NEAR EXPECTED MINS WITH WEAK MIXING IN BOUNDARY LAYER. AT
08Z BROUGHT CONDITIONS TO IFR WITH LIFR CONDITIONS POSSIBLE BTW
09Z-12Z.
WINDS W/NW 5-10 KNOTS TIL SUNSET THEN LIGHT AND VARIABLE. S/SW
WINDS ON WEDNESDAY LESS THAN 10 KNOTS.
OUTLOOK...
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...CHC FOR SHRA/TSRA WITH
RESTRICTIONS.
FRIDAY THROUGH SUNDAY...PRIMARILY VFR WITH SOME FOG RESTRICTIONS
EACH MORNING ESPECIALLY AT KELM.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...PVB
NEAR TERM...PVB
SHORT TERM...DJP
LONG TERM...MSE/TAC
AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
1013 AM EDT MON JUL 28 2008
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE NORTH COUNTRY
TODAY RESULTING IN SOME SHOWERS AND POSSIBLE THUNDERSTORMS.
SHOWER ACTIVITY WILL DIMINISH TONIGHT AS THE DISTURBANCE DEPARTS.
HIGH PRESSURE WILL THEN PROVIDE THE REGION WITH DRY CONDITIONS ON
TUESDAY. UNSETTLED WEATHER RETURNS ON WEDNESDAY...AS ANOTHER UPPER
LEVEL DISTURBANCE APPROACHES FROM THE GREAT LAKES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1013 AM EDT MONDAY...MINOR UPDATE TO GOING FCST THIS
MORNING...MAINLY TO ADJUST SKY COVER/POPS THROUGH EARLY AFTERNOOON
AND TO REMOVE COSMETIC REFERENCES TO MORNING FOG. LATEST SAT IMAGERY
SHOWING STILL QUITE A BIT OF SUN ACROSS THE AREA THIS MORNING AND
HAVE TWEAKED AMOUNTS OF SUN UPWARDS SOMEWHAT BASED OFF THESE LATEST
TRENDS. FAIRLY PRONOUNCED SHORTWAVE ACROSS THE OTTAWA VALLEY STILL
ON TRACK TO CROSS AREA TODAY ALONG WITH SCT/NUMEROUS
SHOWERS/STORMS...ESP CENTRAL/NORTH. HOWEVER...ACTIVITY HAS BEEN A
BIT SLOW TO GET GOING THIS MORNING...MAINLY DUE TO WEAK CAPPING
INVERSION NEAR 650 HPA EVIDENT ON NAM FCST SOUNDINGS AND AVBL ACARS
DATA OUT OF CYUL. AS SHORTWAVE NEARS...FALLING HEIGHTS AND COOLING
TEMPS ALOFT SHOULD ERODE CAP BY THIS AFTERNOON ALLOWING CONVECTION
TO DEVELOP. INHERITED FCST HAS THIS IDEA WELL IN HAND...AND OTHER
THAN SMALL CHANGES NOTED ABOVE...NO OTHER ADJUSTMENTS NEEDED ATTTM.
PREVIOUS DISCUSSION...
AS OF 430 AM EDT MONDAY...UPPER LEVEL TROUGH WILL BE MOVING ACRS
THE REGION TODAY BRINGING WITH IT PARTLY TO MOSTLY CLOUDY SKIES
ALONG WITH SCATTERED TO NUMEROUS SHWRS AND PSBL THNDSTRMS. NOT
MUCH SHOWING UP ON RADAR ATTM...BUT EXPECT WITH DAYTIME HEATING
THE ACTIVITY WILL INCREASE...WITH COVERAGE GREATEST DURING THE PM
HRS. MARGINAL INSTABILITY WITH PROJECTED CAPES 500-1000 J/KG. HAVE
NOT INCLUDED ANY ENHANCED WORDING IN FCST ATTM...BUT ITS NOT OUT
OF THE QUESTION THAT A FEW STORMS MAY CONTAIN SOME GUSTY WINDS AND
SMALL HAIL.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
AS OF 430 AM EDT MONDAY...WE REMAIN UNDER INFLUENCE OF UPPER
TROUGH EARLY TONIGHT AS IT SLOWLY PROGRESSES EAST. EXPECT SHWR
ACTIVITY TO DECREASE AS ATMOS STABILIZES WITH LOSS OF DAYTIME
HEATING. WEAK SFC BOUNDARY ALSO MOVES THRU...ALLOWING FOR WNDS TO
BECOME MORE W-NW. EXPECT A GOOD DEAL OF CLOUD COVER TO
LINGER...AND THOSE AREAS THAT CLEAR MAY SEE SOME PTCHY FOG. DURING
TUESDAY...WEAK BUBBLE OF HIGH PRESSURE WILL BRING SOME SUNSHINE
AND MAINLY DRY CONDITIONS...ALTHOUGH WIDELY SCT SHWRS ARE PSBL
OVER NE VT...WHICH WILL REMAIN UNDER INFLUENCE OF DEPARTING ULVL
TROUGH. OUR RESPITE FROM THE SHOWERY WX WILL BE SHORT LIVED.
WRMFNT WILL BRING A RETURN OF CLOUDS AND PSBL SHWR/TSRA LATE TUES
NITE/WED AM...WITH CHANCES FOR SHWRS AND STORMS CONTINUING WED
PM/NIGHT AS YET ANOTHER UPPER LIVEL DISTURBANCE APRCHS FROM
GRTLKS.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 430 AM EDT MONDAY...UNSETTLED WX EXPECTED TO CONTINUE THRU
THE PERIOD AS UPPER LEVEL TROUGH DEEPENS OVER THE NORTHEAST
THURS/FRI AS INDICATED BY LATEST GFS/ECMWF. AT THE SFC...THE
REGION WILL BE UNDER A GENERAL AREA OF LOW PRESSURE. WHILE
MAGNITUDE OF THE UPPER LEVEL TROUGH IS DEBATABLE...THE END RESULT
IS THAT WE CAN EXPECT A CHC OF SHWRS AND PSBL THNDSTRMS BOTH
DAYS...FOCUSING ON SFC BOUNDARIES WHICH WILL EXIST OVER THE AREA.
NOT MUCH MODEL CONSENSUS AS TO POSITION OF UPPER LEVEL TROUGH THIS
WEEKEND...BUT IT APPEARS AS IF IT WILL CONTINUE TO INFLUENCE OUR
WX...SO HAVE CONTD WITH CHC SHWRS EACH DAY. TEMPS DURING THIS
PERIOD EXPECTED TO BE WITHIN A FEW DEGREES OF SEASONAL NORMS.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
THROUGH 12Z TUESDAY...VFR COND FOR MUCH OF THE MORNING HRS WITH
SCT-BKN120 AND SOME LOW CLD AROUND 040-050. AFT 16Z...MVFR -RW/-TRW
POSSIBLE RIGHT UP TO 04Z TUESDAY. AFT 04Z...ALL SITES WILL SEE SOME
FG AND VSBY WILL VARY FROM MVFR(4-5SM) DOWN TO VLIFR...ESPECIALLY
FOR SLK/MPV...WHICH MAY SEE CEILINGS OVC010 OR LWR AND VSBY 1SM OR
LESS. WINDS LGT/VAR BECM WESTERLY 10KTS OR LESS BY 12Z MON...BECM
LGT/VAR AFT 00Z TUES. HIR TRRN OBSCD AT TIMES.
12Z TUESDAY THROUGH THURSDAY...ON TUES...MID/UPPER LVL TROF LIFTS
OUT AND WEAK SUBSIDENCE/DRY AIR ALOFT DEVELOPS ACRS OUR TAF SITES.
THIS WL PROVIDE TAF SITES WITH VFR CONDITIONS. HOWEVER...PATCHY
FOG WL BE POSSIBLE AT MPV/SLK BTWN 07-12Z ON TUES AND WEDS
MORNINGS. A WEAK WARM FRONT COMBINED WITH A DISTURBANCE ALOFT MAY
PRODUCE MORE SHOWERS ON WEDS INTO THURS ACRS OUR REGION.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...RJS
NEAR TERM...JMG/RJS
SHORT TERM...RJS
LONG TERM...RJS
AVIATION...JN/LAHIFF
AREA FORECAST DISCUSSION
NWS RALEIGH NC
939 PM EDT TUE JUL 29 2008
.SYNOPSIS...A WARM AND HUMID AIR MASS WILL PERSIST OVER THE REGION
THROUGH MID WEEK. AN APPROACHING FRONT COMBINED WITH AN UPPER LEVEL
DISTURBANCE WILL RESULT IN A CHANCE OF SHOWERS AND THUNDERSTORMS
THROUGH THURSDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 924 PM...
FORECAST IS ON TRACK FOR THIS PERIOD AND NO UPDATES PLANNED AT
THIS TIME.
ISOLATED CONVECTION ALMOST COMPLETELY GONE AT 9 PM AS FORECAST.
SOME LIGHT FOG UNWORTHY OF MENTION IN THE TEXT PRODUCTS EXPECTED
TOWARD DAWN.
TEMPERATURES MOSTLY 80 TO 85 AT 9 PM. LOW TEMPERATURES OF 71 TO
75 ACCEPTED.
ALTHOUGH PARAMETERS SEEM TO FAVOR A BIT MORE CONVECTIVE COVERAGE
WEDNESDAY THAN TODAY...NO SIGNIFICANT LIFT MECHANISM OTHER THAN
AFTERNOON HEATING IS EXPECTED. THE CURRENT FORECAST RAIN CHANCES
ARE HIGHER THAN THE AREAL COVERAGE EXPERIENCED TODAY AND WILL
LEAVE THESE UNCHANGED. AFTERNOON HIGH TEMPERATURES SIMILAR TO
TODAY.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
AS OF 310 PM TUESDAY...
SCT CONVECTION WILL LIKELY BE ONGOING AT THE BEGINNING OF THIS
FORECAST PERIOD AS SURFACE AND LOW LEVEL TROUGHING INCREASES.
MIXED LAYER CAPE RANGES AROUND 1000 TO 1500 J/KG ON WEDNESDAY
AFTERNOON SHOULD DIMINISH FAIRLY QUICKLY AFTER SUNSET. THIS WILL
ALLOW THE CONVECTIVE COVERAGE TO DIMINISH ALTHOUGH THREAT OF
ISOLATED SHOWERS OR THUNDERSTORMS IS POSSIBLE OVERNIGHT WITH A
MOIST AIR MASS A SOME WEAK DISTURBANCES IN THE UPPER FLOW. WITH
LINGERING CLOUD COVER AND A LIGHT S FLOW LOWS IN THE LOWER 70S
LOOK GOOD.
THE 850 MILLIBAR TROUGH SLIPS INTO CENTRAL NORTH CAROLINA ON
THURSDAY MORNING AND A SURFACE REFLECTION DEVELOPS AS WELL ACROSS
THE PIEDMONT. THE RESULT IS A MORE WESTERLY LOW LEVEL FLOW ACROSS
MUCH OF THE CWA WHICH WILL LIKELY LIMIT CONVECTIVE COVERAGE TO
LOCATIONS FURTHER EAST. AFTERNOON INSTABILITY BUILDS INTO THE 1000
TO 1500 J/KG RANGE WITH PRECIPITABLE WATER VALUES JUST SHY OF 2
INCHES. WIND FIELD IS WEAK WITH A UNIDIRECTIONAL WEST TO NORTHWEST FLOW.
BULK SHEAR RANGES AROUND 20 KNOTS OR LESS. DESPITE THE MARGINAL
FACTORS THE REGION IS OUTLOOKED IN THE DAY 3 SPC OUTLOOK. WITH A
GOOD AMOUNT OF INSTABILITY AND FREEZING LEVEL AROUND 15000 FEET...
MAIN SEVERE THREAT IS FROM WIND DAMAGE.
SHOULD BE A FAIR AMOUNT OF CLOUDINESS AND SCATTERED CONVECTION ON
THURSDAY WHICH WILL KEEP TEMPERATURES IN THE LOWER 90S. CONVECTION
MAY LINGER INTO THE EVENING HOURS ESPECIALLY ACROSS THE EAST. LOW
TEMPERATURES IN THE LOWER 70S SHOULD BE FINE. FRIDAY SHOULD
FEATURE ONLY ISOLATED CONVECTION ACROSS THE COASTAL PLAIN AS LOW
LEVEL BOUNDARY LINGERS NEAR THE COAST. A GOOD DEAL OF SUNSHINE
SHOULD BE EXPECTED. HEIGHTS AND THICKNESSES RISE ON FRIDAY
AFTERNOON...SUPPORTIVE OF HIGH TEMPERATURES IN THE MID TO UPPER
90S.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 245 PM TUESDAY...
ABOVE NORMAL TEMPERATURES DURING THE EXTENDED PERIOD LOOK MORE
AND MORE LIKELY. BEFOREHAND A SOUTHWARD DRIFTING LOW LEVEL TROUGH LIES
ALONG THE CAROLINA COAST EARLY ON SATURDAY. BOTH THE GFS AND ECMWF
INDICATE A SHORTWAVE EMBEDDED IN THE NW FLOW SHOULD SWING ACROSS
CENTRAL NORTH CAROLINA ON SATURDAY. WITH LIMITED MOISTURE
PRECIPITATION CHANCES ARE PRETTY SMALL SO WILL KEEP POP CHANCES
OUT BUT WILL ENHANCE THE CLOUDINESS TO ACCOUNT FOR THE ENHANCE
MOISTURE AND SOME WEAK LIFT. HIGHS IN THE LOWER TO MID 90S LOOK
GOOD.
GUIDANCE FOR SUNDAY THROUGH TUESDAY IS IN FAIRLY GOOD AGREEMENT
REGARDING A TRANSIENT DEEP UPPER LEVEL RIDGE THAT MOVES ACROSS THE
MIDWEST ON SATURDAY AND SUNDAY INTO THE APPALACHIANS ON MONDAY AND
ACROSS THE MID ATLANTIC COAST ON TUESDAY. PLACEMENT OF THE 700
MILLIBAR RIDGE OVER THE OHIO AND TENNESSEE VALLEYS ON MONDAY SUGGEST
THAT IT WILL BE THE HOTTEST DAY. THE 700 MILLIBAR RIDGE SLIPS
EAST ON TUESDAY AND IS OFFSHORE BY TUESDAY EVENING. REGARDLESS
ABOVE NORMAL TEMPERATURES PERHAPS AS MUCH AS 10 DEGREES ABOVE
NORMAL CAN BE EXPECTED. LATEST MEX GUIDANCE SUPPORTS HIGHS NEAR
100 OR SLIGHTLY ABOVE ON MONDAY AND TUESDAY. WILL HOLD OFF GOING
TRIPLE DIGITS BUT IT SHOULD BE CLOSE. THIS WILL RESULT IN NEAR
RECORD HIGHS WHICH ARE IN THE UPPER 90S TO AROUND 100...RECORD
HIGHS ARE SHOWN IN THE TABLE AT THE BOTTOM OF THIS PRODUCT.
WITH RIDGING ALOFT PROVIDING A GOOD DEAL OF SUBSIDENCE...CHANCE OF
PRECIPITATION IS REMOTE AND SKIES SHOULD BE MAINLY CLEAR. WILL
INCLUDE A FEW MORE CLOUDS AND MASSAGE THE POPS SO THAT THEY ARE A
LITTLE HIGHER ALONG THE SOUTHERN AND CENTRAL COASTAL PLAIN. A
WEAKNESS IN THE UPPER AIR PATTERN AND LINGERING LOW LEVEL
TROFINESS MAY PROVIDE A FEW MORE CLOUDS.
INCREASED CLOUDS A BIT AND ADDED A LESS THEN 20 PERCENT CHANCE OF
THUNDERSTORMS ON TUESDAY AFTERNOON ACROSS WEST AND SOUTHWEST ZONES
WHERE UPPER RIDGE BREAKS DOWN AND LOW LEVEL MOISTURES INCREASES
WITH RETURN FLOW.
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
AS OF 800 PM TUESDAY...
WITH ALL AFTERNOON CONVECTION STEERING CLEAR OF THE TAF SITES THIS
AFTERNOON AND EVENING...THE OVERNIGHT PERIOD SHOULD BE RATHER BENIGN
FOR MOST AVIATION TRAVELERS. THE MOST IMPORTANT CONCERN...
ESPECIALLY FOR COMMUTERS IN LIGHTER AIRCRAFT...WILL BE THE
DEVELOPMENT OF MODEST LOW LEVEL JET OF 20KTS DEVELOPING AROUND 2
THOUSAND FEET AT THE TOP OF THE NOCTURNAL INVERSION. OBSERVATIONS
SHOW 15 KNOTS ALREADY AT 2 THOUSAND FEET AS OF 8PM. AS HAS BEEN
MENTIONED IN PREVIOUS DISCUSSIONS...THIS LOW LEVEL JET MAY DEVELOP
AGAIN ON WEDNESDAY NIGHT/THURSDAY MORNING. SKIES WILL ONLY FEATURE
A MID-LEVEL CLOUD DECK AROUND 10 THOUSAND FEET DRIFTING EAST-
NORTHEAST THROUGH CENTRAL NORTH CAROLINA OVERNIGHT. SURFACE
DEWPOINT TEMPERATURES ARE A LITTLE HIGHER THIS EVENING THAN 24
HOURS AGO...SO BRIEF MVFR VISIBILITY POSSIBLE...MAINLY ACROSS THE
SOUTH (FAY)...ALTHOUGH VISIBILITY MAY DROP LOW TO AROUND 3 MILES
AT RWI WHERE CLOUDS SHOULD BE LESS ABUNDANT. -SMITH
SCATTERED CUMULUS IN THE 5 TO 6 THOUSAND FEET LAYER WILL DEVELOP
WEDNESDAY AFTERNOON...AND WITH PLENTY OF INSTABILITY...CONVECTION
MAY BECOME AN ISSUE AT ANY TAF SITE. THE LIMITING FACTOR FOR
CONVECTION WILL LIKELY BE A LACK A STRONG TRIGGER MECHANISM. WITH
NO SIGNIFICANT FORECAST UPPER LEVEL PERTURBATIONS...AND NONE YET
NOTICEABLE ON SATELLITE IMAGERY... NO THUNDERSTORMS ARE FEATURED
IN THE TAFS. -SMITH
BY THURSDAY...DEEP WEST FLOW MAY ACT TO LIMIT CONVECTIVE COVERAGE
SOMEWHAT. ALSO APPEARS THAT BEST LOW LEVEL PARAMETERS AND LOW AND MID
LEVEL CONFLUENCE WILL BE OVER THE COASTAL PLAIN RATHER THAN THE
PIEDMONT. -WSS
FOR FRIDAY THROUGH SUNDAY...HIGH PRESSURE NEAR SURFACE AND ALOFT
WILL BUILD INTO THE REGION FROM THE WEST. THIS WEATHER FEATURE WILL
SERVE TO SUPPRESS CONVECTIVE DEVELOPMENT THROUGH THE PERIOD.
THUS...EXPECT A CONTINUATION OF VFR CONDITIONS. ANY MVFR CONDITIONS
WILL BE LIMITED TO THE EARLY MORNING HOURS WHEN FOG/HAZE WILL BE
MOST PROMINENT. -WSS
&&
.CLIMATE...
DAILY RECORD HIGH TEMPERATURES FOR AUGUST 2ND THROUGH 5TH.
RDU GSO
AUG 02 101(1953) 99(1953)
AUG 03 99(2006) 98(1942)
AUG 04 98(2006) 98(1987)
AUG 05 100(1953) 101(1930)
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
SHORT TERM...BLAES
LONG TERM...BLAES
AVIATION...SMITH/WSS
CLIMATE...PAGANO
AREA FORECAST DISCUSSION
NWS RALEIGH NC
800 PM EDT TUE JUL 29 2008
.SYNOPSIS...A LOW PRESSURE TROUGH WILL LINGER OVER CENTRAL NORTH CAROLINA
THROUGH MIDWEEK. THIS TROUGH...COMBINED WITH PASSING UPPER LEVEL
DISTURBANCES WILL RESULT IN A CHANCE OF SHOWERS AND THUNDERSTORMS.
A STRONGER UPPER LEVEL SYSTEM IS EXPECTED TO ENTER THE AREA ON
THURSDAY...BRINGING A BETTER CHANCE FOR SHOWERS AND STORMS.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 245 PM TUESDAY...
POCKET OF VERY DRY ALOFT DEPICTED ON WATER VAPOR IMAGERY LIKELY
SUPPRESSING CONVECTION ACROSS CENTRAL NC THIS AFTERNOON. THE
ISOLATED SHOWERS THAT HAVE DEVELOP QUICKLY DISSIPATED ONCE THE TOPS
GREW TO ABOUT 20000FT. THUS...APPEARS THAT ANY CONVECTION THAT
OCCURS THROUGH LATE EVENING WILL BE ISOLATED. HOWEVER...DUE TO
PRESENCE OF DRIER AIR ALOFT...ANY HEAVY SHOWERS OR STORMS THAT
DEVELOP WILL HAVE POTENTIAL TO PRODUCE STRONG GUSTY WINDS. AT THIS
TIME...THE WESTERN PIEDMONT STANDS THE BEST CHANCE OF SEEING A
SHOWER OR STORM AS THIS REGION SEEING THE BEST CONFLUENCE OF LOW
LEVEL MOISTURE AND INSTABILITY (PER TRENDS OBSERVED ON MSAS).
THUS...ANY SHOWERS OR STORMS THAT FORM ON THE BLUE RIDGE AND DRIFT
EAST WILL HAVE A FIGHTING CHANCE TO SURVIVE IN THE WESTERN PIEDMONT.
FOR WEDNESDAY...EXPECT TO SEE A LITTLE MORE COVERAGE OF CONVECTION.
PRECIP WATER VALUES PROJECTED TO HOVER BETWEEN 1.8 AND 2 INCHES.
SURFACE LIFTED INDICES DURING THE HEAT OF THE DAY SHOULD CLIMB INTO
THE MODERATE RANGE. BOTH THE NAM AND GFS DEPICT A 850MB TROUGH INTO
THE WESTERN PIEDMONT BETWEEN 18Z AND 00Z WITH A 850 THETA-E MAXIMA
OVER THE REGION. THESE FACTORS WOULD INDICATE DECENT COVERAGE
HOWEVER THE SUPPORT ALOFT IS LACKING WITH NOTHING MORE THAN A WEAK
SHEAR AXIS INTO THE WESTERN PIEDMONT BY 00Z THU WHILE BEST 300MB
WINDS WELL NORTH OF FORECAST AREA. DUE TO THE WEAK INDICATORS ALOFT.
WILL MAINTAIN A SMALL CHANCE POP AT THIS TIME. IF A BETTER DEFINED
FEATURE CAN BE DISCERNED ON THE WATER VAPOR IMAGERY...THEN THE POPS
WILL NEED TO BE INCREASED TO HIGH CHANCE.
LOW LEVEL THICKNESSES SUPPORT ABOVE NORMAL TEMPS TONIGHT AND WED.
WITH HUMID AIR MASS IN PLACE...MIN TEMPS 70-75 DEGREES WILL BE
COMMON. MAX TEMPS WED SHOULD BE COMPARABLE TO TODAY (90-95).
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
AS OF 310 PM TUESDAY...
SCT CONVECTION WILL LIKELY BE ONGOING AT THE BEGINNING OF THIS
FORECAST PERIOD AS SFC AND LOW LEVEL TROUGHING INCREASES. MIXED
LAYER CAPE RANGES AROUND 1000 TO 1500 J/KG ON WED AFTN SHOULD
DIMINISH FAIRLY QUICKLY AFTER SUNSET. THIS WILL ALLOW THE
CONVECTIVE COVERAGE TO DIMINISH ALTHOUGH THREAT OF ISOLATED
SHOWERS OR THUNDERSTORMS IS POSSIBLE OVERNIGHT WITH A MOIST
AIRMASS A SOME WEAK DISTURBANCES IN THE UPPER FLOW. WITH LINGERING
CLOUD COVER AND A LIGHT S FLOW LOWS IN THE LOWER 70S LOOK GOOD.
THE 850 MB TROF SLIPS INTO CENTRAL NC ON THURSDAY MORNING AND A SFC
REFLECTION DEVELOPS AS WELL ACROSS THE PIEDMONT. THE RESULT IS A MORE
WESTERLY LOW LEVEL FLOW ACROSS MUCH OF THE CWA WHICH WILL LIKELY
LIMIT CONVECTIVE COVERAGE TO LOCATIONS FURTHER EAST. AFTERNOON
INSTABILITY BUILDS INTO THE 1000 TO 1500 J/KG RANGE WITH PW VALUES
JUST SHY OF 2 INCHES. . WIND FIELD IS WEAK WITH A UNIDIRECTIONAL W
TO NW FLOW. BULK SHEAR RANGES AROUND 20 KTS OR LESS. DESPITE THE
MARGINAL FACTORS THE REGION IS OUTLOOKED IN THE DAY 3 SPC OUTLOOK.
WITH A GOOD AMOUNT OF INSTABILITY AND FREEZING LEVEL AROUND 15K
FEET... MAIN SVR THREAT IS FROM WIND DAMAGE.
SHOULD BE A FAIR AMOUNT OF CLOUDINESS AND SCT CONVECTION ON THURS WHICH
WILL KEEP TEMPS IN THE LOWER 90S. CONVECTION MAY LINGER INTO THE
EVENING HOURS ESPECIALLY ACROSS THE EAST. LOW TEMPS IN THE LOWER
70S SHOULD BE FINE. FRIDAY SHOULD FEATURE ONLY ISOLATED CONVECTION
ACROSS THE COASTAL PLAIN AS LOW LEVEL BOUNDARY LINGERS NEAR THE
COAST. A GOOD DEAL OF SUNSHINE SHOULD BE EXPECTED. HEIGHTS AND
THICKNESSES RISE ON FRIDAY AFTERNOON...SUPPORTIVE OF HIGH TEMPS IN
THE MID TO UPPER 90S.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 245 PM TUESDAY...
ABOVE NORMAL TEMPERATURES DURING THE EXTENDED PERIOD LOOK MORE
AND MORE LIKELY. BEFOREHAND A SOUTHWARD DRIFTING LOW LEVEL TROF
LIES ALONG THE CAROLINA COAST EARLY ON SATURDAY. BOTH THE GFS AND
ECMWF INDICATE A SHORTWAVE EMBEDDED IN THE NW FLOW SHOULD SWING
ACROSS CENTRAL NC ON SAT. WITH LIMITED MOISTURE PRECIP CHANCES
ARE PRETTY SMALL SO WILL KEEP POP CHANCES OUT BUT WILL ENHANCE THE
CLOUDINESS TO ACCOUNT FOR THE ENHANCE MOISTURE AND SOME WEAK LIFT.
HIGHS IN THE LOWER TO MID 90S LOOK GOOD.
GUIDANCE FOR SUN THROUGH TUE IS IN FAIRLY GOOD AGREEMENT
REGARDING A TRANSIENT DEEP UPPER LEVEL RIDGE THAT MOVES ACROSS THE
MIDWEST ON SAT/SUN INTO THE APPALACHIANS ON MON AND ACROSS THE MID
ATLANTIC COAST ON TUES. PLACEMENT OF THE 700 MB RIDGE OVER THE
OH/TN VALLEYS ON MON SUGGEST THAT IT WILL BE THE HOTTEST DAY. THE
H7 RIDGE SLIPS EAST ON TUESDAY AND IS OFFSHORE BY TUE EVE.
REGARDLESS ABOVE NORMAL TEMPS PERHAPS AS MUCH AS 10 DEGREES ABOVE
NORMAL CAN BE EXPECTED. LATEST MEX GUIDANCE SUPPORTS HIGHS NEAR
100 OR SLIGHTLY ABOVE ON MON AND TUES. WILL HOLD OFF GOING TRIPLE
DIGITS BUT IT SHOULD BE CLOSE. THIS WILL RESULT IN NEAR RECORD
HIGHS WHICH ARE IN THE UPPER 90S TO AROUND 100...RECORD HIGHS ARE
SHOWN IN THE TABLE AT THE BOTTOM OF THE AFD.
WITH RIDGING ALOFT PROVIDING A GOOD DEAL OF SUBSIDENCE...CHC OF
PRECIP IS REMOTE AND SKIES SHOULD BE MAINLY CLEAR. WILL INCLUDE A
FEW MORE CLOUDS AND MASSAGE THE POPS SO THAT THEY ARE A LITTLE
HIGHER ALONG THE SOUTHERN AND CENTRAL COASTAL PLAIN. A WEAKNESS IN
THE UPPER AIR PATTERN AND LINGERING LOW LEVEL TROFINESS MAY
PROVIDE A FEW MORE CLOUDS.
INCREASED CLOUDS A BIT AND ADDED A LESS THEN 20 PERCENT CHANCE OF
THUNDERSTORMS ON TUESDAY AFTERNOON ACROSS W AND SW ZONES WHERE
UPPER RIDGE BREAKS DOWN AND LOW LEVEL MOISTURES INCREASES WITH
RETURN FLOW.
&&
.AVIATION /00Z WEDNESDAY THROUGH SATURDAY/...
AS OF 800 PM TUESDAY...
WITH ALL AFTERNOON CONVECTION STEERING CLEAR OF THE TAF SITES THIS
AFTERNOON AND EVENING...THE OVERNIGHT PERIOD SHOULD BE RATHER BENIGN
FOR MOST AVIATION TRAVELERS. THE MOST IMPORTANT
CONCERN...ESPECIALLY FOR COMMUTERS IN LIGHTER AIRCRAFT...WILL BE THE
DEVELOPMENT OF MODEST LOW LEVEL JET OF 20KTS DEVELOPING AROUND 2 KFT
AT THE TOP OF THE NOCTURNAL INVERSION. OBSERVATIONS SHOW 15 KTS
ALREADY AT 2 KFT AS OF 8PM. AS HAS BEEN MENTIONED IN PREVIOUS
DISCUSSIONS...THIS LOW LEVEL JET MAY DEVELOP AGAIN ON WEDNESDAY
NIGHT/THURSDAY MORNING. SKIES WILL ONLY FEATURE A MID-LEVEL CLOUD
DECK AROUND 10 KFT DRIFTING EAST-NORTHEAST THROUGH CENTRAL NORTH
CAROLINA OVERNIGHT. SURFACE DEWPOINT TEMPERATURES ARE A LITTLE
HIGHER THIS EVENING THAN 24 HOURS AGO...SO BRIEF MVFR VISIBILITY
POSSIBLE...MAINLY ACROSS THE SOUTH (FAY)...ALTHOUGH VISIBILITY MAY
DROP LOW TO AROUND 3 MILES AT RWI WHERE CLOUDS SHOULD BE LESS
ABUNDANT. -SMITH
SCATTERED CUMULUS IN THE 5-6 KFT LAYER WILL DEVELOP WEDNESDAY
AFTERNOON...AND WITH PLENTY OF INSTABILITY...CONVECTION MAY BECOME
AN ISSUE AT ANY TAF SITE. THE LIMITING FACTOR FOR CONVECTION WILL
LIKELY BE A LACK A STRONG TRIGGER MECHANISM. WITH NO SIGNIFICANT
FORECAST UPPER LEVEL PERTURBATIONS...AND NONE YET NOTICEABLE ON
SATELLITE IMAGERY... NO CB`S ARE FEATURED IN THE TAFS. -SMITH
BY THU...DEEP WLY FLOW MAY ACT TO LIMIT CONVECTIVE COVERAGE
SOMEWHAT. ALSO APPEARS THAT BEST LOW LEVEL PARAMETERS AND LOW/MID
LEVEL CONFLUENCE WILL BE OVER THE COASTAL PLAIN RATHER THAN THE
PIEDMONT. -WSS
FOR FRIDAY THROUGH SUNDAY...HIGH PRESSURE NEAR SURFACE AND ALOFT
WILL BUILD INTO THE REGION FROM THE WEST. THIS WEATHER FEATURE WILL
SERVE TO SUPPRESS CONVECTIVE DEVELOPMENT THROUGH THE PERIOD.
THUS...EXPECT A CONTINUATION OF VFR CONDITIONS. ANY MVFR CONDITIONS
WILL BE LIMITED TO THE EARLY MORNING HOURS WHEN FOG/HAZE WILL BE
MOST PROMINENT. -WSS
&&
.CLIMATE...
DAILY RECORD HIGH TEMPERATURES FOR AUGUST 3RD THROUGH 5TH.
RDU GSO
AUG 02 101(1953) 99(1953)
AUG 03 99(2006) 98(1942)
AUG 04 98(2006) 98(1987)
AUG 05 100(1953) 101(1930)
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BLAES
NEAR TERM...WSS
SHORT TERM...BLAES
LONG TERM...BLAES
AVIATION...SMITH/WSS
CLIMATE...PAGANO
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