AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
930 PM PDT SUN JUN 22 2008
.SYNOPSIS...WEAK UPPER LEVEL LOW PRESSURE WILL BRING COOLER WEATHER
THIS WEEK. THE MARINE LAYER AND ONSHORE FLOW WILL CAUSE COASTAL LOW
CLOUDS AND FOG DURING THE NIGHTS AND MORNINGS...EXTENDING LOCALLY
INLAND. LOCALLY WINDY IN THE MOUNTAINS AND DESERTS DURING THE
AFTERNOONS AND EVENINGS.
&&
.DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO...
ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES.
.SHORT TERM (TONIGHT-WED)...SKIES WERE MOSTLY CLEAR THIS EVENING
EXCEPT FOR AREAS OF STRATUS ALONG S COAST...A FEW HIGH CLOUDS AND A
LITTLE SMOKE FROM THE RANGE FIRE ON CAMP PENDLETON. THE 00Z NKX
SOUNDING HAD A WEAK INVERSION BASED NEAR 1200 FT WITH WLY WINDS
ALOFT BUT ACARS SOUNDINGS CLOSER TO THE COAST INDICATE A STRONGER
INVERSION BASED BELOW 1000 FT. MODERATELY STRONG ONSHORE GRADIENTS
WITH ABOUT 7 MB SAN-IPL.
A DEVELOPING WEAK UPPER LEVEL TROUGH OF LOW PRESSURE ALONG WITH
STRONGER ONSHORE GRADIENTS WILL BRING COOLER WEATHER THROUGH MID
WEEK. EVEN WITH 5 TO 10 DEGREES COOLING IN MOST AREAS MON...MAX
TEMPS WILL STILL BE ABOVE SEASONAL AVERAGES. TEMPS WILL LOWER TO
CLOSE TO NORMAL BY WED. THE MARINE LAYER WILL ALSO GRADUALLY DEEPEN
WITH LOW CLOUDS AND FOG GETTING A LITTLE FARTHER INLAND EACH NIGHT.
THERE WILL BE LOCAL DENSE FOG NEAR THE INLAND EXTENT OF THE STRATUS.
THE ONSHORE FLOW WILL CAUSE LOCAL GUSTY WINDS DURING THE AFTERNOONS
AND EVENINGS...MAINLY IN THE MOUNTAINS AND DESERTS. THERE COULD BE
JUST ENOUGH MOISTURE FOR THERMALS TO PRODUCE SHALLOW CU OVER THE
MOUNTAINS MON AFTERNOON.
CONTINUED LOW RH AT HIGHER ELEVATIONS AND IN THE DESERTS COMBINED
WITH OCCASIONAL BREEZY TO WINDY CONDITIONS WILL MAINTAIN AN ELEVATED
FIRE WEATHER HAZARD. HOWEVER...NO WIDESPREAD OR SUSTAINED CRITICAL
FIRE WEATHER CONDITIONS ARE EXPECTED.
&&
.LONG TERM (THU-SUN)...THE UPPER HIGH BUILDS BACK IN FROM THE E
TOWARD THE END OF THE WEEK BUT A LOW OFF THE COAST WILL KEEP LOCAL
HEIGHTS FROM INCREASING MUCH. AS A RESULT...THERE SHOULD BE SLIGHT
WARMING. MINOR CHANGES IN THE MARINE LAYER.
&&
.AVIATION...
230230Z...MDCRS SOUNDINGS SHOW THE MARINE LAYER DEPTH AROUND 500 FT
ALONG THE COAST AT 02Z. SOME DEEPENING IS POSSIBLE OVERNIGHT AND ON
MON.
STRATUS/FOG CONTINUES TO SPREAD NORTHWARD OFF THE COAST AND HAD JUST
REACHED THE SOUTHERN ORANGE COUNTY BEACHES AT 0215Z. SURFACE
PRESSURE GRADIENTS ARE INCREASING ONSHORE. THIS SHOULD FINALLY DRIVE
THE STRATUS/FOG UP TO 5 TO 8 MILES INLAND OVERNIGHT. EXPECT A PERIOD
OF VLIFR CIGS/VIS AT KSAN...KCRQ...KMYF...AND KSNA BETWEEN 10Z AND
15Z. WITH THE STRATUS LAYER BELOW 800 FT...SOME IMPACT TO COASTAL
AIRPORT OPERATIONS CAN BE EXPECTED UP UNTIL ABOUT 15Z ON MON. THE
SHALLOW LAYER SHOULD QUICKLY MIX OUT AND RETREAT TO THE BEACHES
BETWEEN 16Z AND 17Z.
ABOVE THE MARINE LAYER INCLUDING THE MOUNTAINS AND DESERTS...SKIES
WILL BE MOSTLY CLEAR WITH UNRESTRICTED VISIBILITY...EXCEPT IN THE
VICINITY OF WILDFIRES AND ASSOCIATED SMOKE PLUMES.
EXPECT MAX TEMPS FOR KPSP AND KTRM TO BE 41 TO 43C FOR FOR MONDAY
AFTERNOON. KONT SHOULD REACH 36C ON MONDAY. MAX TEMPS FOR COASTAL
AIRPORTS SUCH AS KSAN AND KSNA SHOULD BE 22 TO 24C ON MONDAY.
&&
.SGX WATCHES/WARNINGS/ADVISORIES/STATEMENTS...NONE.
&&
$$
PUBLIC...DA
AVIATION...JD
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
200 PM PDT SUN JUN 22 2008
.SYNOPSIS...WEAKENING HIGH PRESSURE WILL ALLOW THE COOLING MARINE
AIR TO GRADUALLY SPREAD INLAND THIS WEEK. A SHARP COOLING TREND IS
EXPECTED NEAR THE COAST WITH A MORE GRADUAL COOLING TREND IN THE
MOUNTAINS AND DESERTS. THE MARINE LAYER WILL BE QUITE SHALLOW
TONIGHT WITH DENSE FOG EXPECTED NEAR THE COAST. THE FOG WILL MOVE A
LITTLE FARTHER INLAND DURING THE NIGHTS THIS WEEK.
&&
.DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO...
ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES.
WHAT A DIFFERENCE A DAY MAKES. A FOG SURGE FROM BAJA HAS SPREAD A
SHALLOW FOG LAYER ALONG THE COAST NORTHWARD TODAY. SOUTH WINDS OF 20
MPH WERE RECORDED AT IMPERIAL BEACH PIER THIS MORNING WITH A HIGH OF
66 SO FAR TODAY. MAX TEMPS ALONG THE SOUTHERN SAN DIEGO CO COAST MAY
HAVE OCCURRED AT 9 AM JUST BEFORE THE FOG ARRIVED. IN THE DESERT
TEMPS TODAY ARE RUNNING SEVERAL DEGREES BELOW WHAT THEY WERE
YESTERDAY AT THIS TIME BECAUSE OF A GULF SURGE THAT HAS INCREASED
HUMIDITY. THE FOG AND THE GULF SURGE SURGING UP FROM THE SOUTH MAY
BE THE RESULT OF AN OUTFLOW BOUNDARY...A RUSH OF AIR THAT CAME FROM
A GIANT THUNDERSTORM COMPLEX OVER SONORA SAT EVE. MOISTURE ALOFT HAS
PRODUCED A FEW CUMULUS CLOUDS IN THE MTNS AND DESERTS TODAY...BUT NO
SHOWERS ARE EXPECTED. TONIGHT THE FOG WILL SPREAD A SHORT WAY INLAND
AS A RESULT OF INCREASED ONSHORE FLOW AND THE LOWER PRESSURE ALOFT.
DENSE FOG IS PROBABLE NEAR THE COAST...ESPECIALLY ON THE HIGHER
COASTAL TERRAIN AND MESAS. THE COOLER WEATHER AND FOG WILL
INCREMENTALLY MOVE FARTHER INLAND FOR THE NEXT COUPLE DAYS AS THE
UPPER HIGH OVER THE SOUTHWEST WEAKENS AND THE UPPER LOW OVER THE
NORTHWEST WEAKLY SAGS SOUTHWARD. LATER THIS WEEK THE LOW MEANDERS
OFF THE CA COAST WARDING OFF THE SOUTHWEST HIGH AND PROTECTING SOCAL
FROM THE EXTREME HEAT. THE WEATHER PATTERN WILL BE RATHER STATIC TUE
INTO NEXT WEEKEND. TEMPS AND NOCTURNAL COASTAL CLOUDINESS WILL BE
MUCH CLOSER TO NORMAL.
&&
.AVIATION...
221945Z...MDCRS SOUNDINGS SHOW THE MARINE LAYER DEPTH TO BE 500 FEET
OR LESS ALONG THE COAST. ONLY MINOR CHANGES IN THE DEPTH IS EXPECTED
THROUGH MONDAY.
STRATUS/FOG CONTINUES TO SPREAD NORTHWARD ALONG THE COAST AND IS
EXPECTED TO REACH THE SAN DIEGO/ORANGE COUNTY LINE BY 00Z AND
NORTHERN ORANGE COUNTY BY 06Z. STRATUS/FOG COULD MOVE OVER KSAN AT
ANY TIME BEFORE SUNSET. KCRQ SHOULD GET CEILINGS AROUND OR SHORTLY
AFTER SUNSET. TIMING FOR CEILINGS AT KSNA IS MORE LIKELY BETWEEN 06Z
AND 09Z. BREAKUP ON MONDAY SHOULD BE BETWEEN 15Z AND 16Z.
ABOVE THE MARINE LAYER INCLUDING THE MOUNTAINS AND DESERTS...A
MOSTLY CLEAR SKY WITH UNRESTRICTED VISIBILITIES WILL CONTINUE
THROUGH MONDAY EXCEPT FOR SOME AFTERNOON CUMULUS OVER THE MOUNTAINS.
A SHALLOW SURGE OF MOISTURE FROM THE GULF OF CALIFORNIA MOVED INTO
THE KTRM AND KPSP AREA THIS MORNING WHICH MODERATED TEMPERATURES.
EXPECT MAX TEMPS FOR KPSP AND KTRM TO BE 40 TO 43C FOR THIS
AFTERNOON WITH SIMILAR TEMPERATURES EXPECTED FOR MONDAY AFTERNOON.
KONT SHOULD REACH 37C ON MONDAY. MAX TEMPS FOR COASTAL AIRPORTS SUCH
AS KSAN AND KSNA SHOULD BE 22 TO 25C ON MONDAY. HORTON
&&
.SGX WATCHES/WARNINGS/ADVISORIES/STATEMENTS...NONE.
&&
$$
PUBLIC...MM
AVIATION/MARINE...HORTON
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
425 AM PDT SAT JUN 21 2008
...UPDATED AVIATION DISCUSSION...
...CONTINUED HOT TEMPERATURES ACROSS SOUTHWESTERN CALIFORNIA
TODAY...
SHORT TERM...(TODAY-MONDAY)
STRONG HIGH PRESSURE ALOFT AND WEAK OFFSHORE SFC GRADIENTS CONTINUE
TO KEEP RECORD OR NEAR RECORD HIGH TEMPS AROUND TODAY. THERE WAS
LITTLE RELIEF IN COOLING OVERNIGHT AS TEMPERATURES WERE DOWNRIGHT
UNCOMFORTABLE AS MANY AREAS ONLY LOWERED TO THE LOWER TO MID 70S
ACROSS SOME COASTAL AREAS WHILE SOME VALLEY TEMPS ARE STILL IN THE
MID TO UPPER 80S. AT 2 AM...VAN NUYS AIRPORT REPORTED 88 DEGREES
WITH A DEWPOINT OF 45. WHICH WAS 13 DEGREES WARMER THAN 24-HOURS
AGO. ALSO AT 2 AM...MALIBU HILLS WAS 94 DEGREES. THE LATEST
ACARS SOUNDING FROM LAX INDICATED A VERY STRONG INVERSION BEGINNING
AT 500 FT WITH A TEMP OF 73 DEGREES. AT THE TOP OF THE INVERSION
(2400 FT) THE TEMP WAS 94. THE BOTTOM LINE IS...UNLESS YOU ARE AT
THE IMMEDIATE COAST OR HAVE AIR CONDITIONING...YOU ARE PROBABLY NOT
A HAPPY CAMPER THIS MORNING. NEVERTHELESS...WE ARE ON TAP FOR
ANOTHER SCORCHER TODAY. AN EXCESSIVE HEAT WARNING HAS BEEN ISSUED
ONCE AGAIN FOR TODAY INCLUDING THE SAME LOCATIONS AS FRIDAY.
OVERALL...NORTH OF POINT CONCEPTION TEMPERATURES ACROSS THE CENTRAL
COAST SHOULD BE A FEW DEGREES COOLER TODAY AS OFFSHORE FLOW WILL
SHIFT TO SEABREEZE MUCH SOONER TODAY. HOWEVER TEMPS WILL CONTINUE TO
BE QUITE HOT INLAND WITH PASO ROBLES EXPECTED TO REACH 110 DEGREES.
THIS SAME TREND WILL BE LIKELY OCCUR ACROSS LA/VTU/SBA COUNTY
COASTAL AREAS AS WELL. DOWNTOWN LA SHOULD LOWER A DEGREE OR TWO
TODAY...BUT TEMPS WILL BE VERY SIMILAR TO YESTERDAY IN MANY OF THE
SAME LOCATIONS.
THERE WERE SEVERAL RECORD HIGH TEMPS RECORDED YESTERDAY INCLUDING
THE HOTTEST TEMPERATURE EVER RECORDED (110) AT SANTA MARIA SINCE
RECORDS WERE KEPT FROM 1929. AS MENTIONED EARLIER...THE FEELING IS
THAT HIGH TEMPS SHOULD LOWER 6 TO 10 DEGREES ALONG THE CENTRAL COAST
WITH A QUICKER RETURN OF THE SEABREEZE TODAY. SEE LAXPNSLOX FOR
UPDATED RECORDS FOR YESTERDAY.
BOTH WRF AND GFS INDICATE SOME WEAK VORTICITY ADVECTION AND LIMITED
MID LEVEL MOISTURE ACROSS THE MOUNTAINS OF SLO/SBA/VTU AND LA
COUNTIES LATER THIS AFTERNOON. THE BEST CONVECTIVE PARAMETERS APPEAR
TO BE OVER THE VTU COUNTY MTNS THIS AFTERNOON. WITH PWAT VALUES
BETWEEN .75 TO 1 INCH...AND A WEAK VORT PROGGED TO MOVE OVER THE
AREA THIS AFTERNOON...A FEW ELEVATED SHOWERS AND A SLIGHT CHANCE OF
A THUNDERSTORM HAVE BEEN ADDED TO THE MOUNTAIN ZONES THIS AFTERNOON.
OVERNIGHT TEMPERATURES WILL STILL REMAIN QUITE HIGH FOR MOST AREAS
WITH LOWS STILL ONLY LOWERING TO THE 70S...BUT MOST COASTAL AREAS
SHOULD LOWER TO AT LEAST THE 60S TONIGHT AS ONSHORE GRADIENTS WILL
BEGIN TO STRENGTHEN SOME.
FOR SUNDAY...THE UPPER HIGH BEGINS TO GET SQUASHED AND BECOME
ELONGATED TO OUR SOUTH AS A BROAD TROF BEGINS TO PUSH SOUTHEAST OUT
OF THE EASTERN PAC. THIS WILL HELP LOWER THICKNESS LVLS AND HIGHS
ACROSS MOST LOCATIONS WILL BE 5 TO 10 DEGREES COOLER AS MOST COASTAL
AREAS WILL BE IN THE MID 70S AND 80S. ALTHOUGH THERE WILL CONTINUE
TO BE HOT CONDITIONS ACROSS MANY PORTIONS OF THE INTERIOR VALLEYS
WITH TEMPS RANGING IN THE 90S TO LOWER 100S...AN EXCESSIVE HEAT
WATCH WAS NOT ISSUED FOR SUNDAY. THE THERMAL TROF WILL BEGIN TO
RE-ESTABLISH ACROSS THE INTERIOR OF SOUTHERN CALIFORNIA SUNDAY WHICH
WILL HELP TO INCREASE THE ONSHORE FLOW AND BRING A RETURN OF MORE
SEASONABLE CONDITIONS INCLUDING INCREASED LOW CLOUDS TO THE CENTRAL
COAST AND THE LA/VTU COUNTY COASTAL AREAS AS THE MARINE LAYER BEGINS
TO RE-ESTABLISH ITSELF SUNDAY NIGHT INTO MONDAY MORNING. MODELS
INDICATE A DECENT SUNDOWNER FOR THE USUAL PASSES AND CANYONS ACROSS
THE SBA SOUTH COAST AND FOOTHILLS WITH NORTHWEST TO NORTH WIND GUSTS
TO 45 MPH POSSIBLE. A CONTINUED COOLING TREND FOR MONDAY WHICH WILL
FEEL MORE TYPICAL FOR JUNE. EXPECT A MORE WIDESPREAD RETURN OF NIGHT
THROUGH MORNING LOW CLOUDS AFFECTING THE CENTRAL COAST AND LA/VTU
COUNTY COASTAL AREAS AS WELL.
.LONG TERM...(TUE-FRI)
BOTH GFS AND ECMWF ARE IN PRETTY GOOD AGREEMENT FOR SLIGHTLY COOLER
CONDITIONS TUESDAY AND CONTINUED SIMILAR CONDITIONS THROUGH FRIDAY
AS UPPER TROF HANGS AROUND CALIFORNIA. THE UPPER HIGH THAT IS
LOCATED OVER SOUTHERN AZ/NM AND MEXICO COULD SHIFT INTO A MORE
FAVORABLE POSITION TO BRING THE POTENTIAL OF SOME SUB-TROPIC
MOISTURE UP FROM MEXICO. BUT MODELS ARE NOT HANDLING THIS WELL AT
THIS POINT.
&&
.AVIATION...21/1130Z.
EXPECT VFR CONDS THROUGH TODAY WITH SOME STRATO CU DEVELOPING ACROSS
THE LOCAL MTNS AFTER 19Z. A SLIGHT CHANCE OF AN ELEVATED MTN SHOWER
OR THUNDERSTORM WILL BE POSSIBLE IN THE AFTERNOON.
KLAX...HIGH CONFIDENCE WITH TAF.
KBUR...HIGH CONFIDENCE WITH TAF.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
EXCESSIVE HEAT WARNING (SEE LAXNPWLOX).
RED FLAG WARNING (SEE LAXRFWLOX).
&&
$$
PUBLIC...KAPLAN
AVIATION...RORKE
WWW.WEATHER.GOV/LOSANGELES
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
340 AM PDT SAT JUN 21 2008
...CONTINUED HOT TEMPERATURES ACROSS SOUTHWESTERN CALIFORNIA
TODAY...
SHORT TERM...(TODAY-MONDAY)
STRONG HIGH PRESSURE ALOFT AND WEAK OFFSHORE SFC GRADIENTS CONTINUE
TO KEEP RECORD OR NEAR RECORD HIGH TEMPS AROUND TODAY. THERE WAS
LITTLE RELIEF IN COOLING OVERNIGHT AS TEMPERATURES WERE DOWNRIGHT
UNCOMFORTABLE AS MANY AREAS ONLY LOWERED TO THE LOWER TO MID 70S
ACROSS SOME COASTAL AREAS WHILE SOME VALLEY TEMPS ARE STILL IN THE
MID TO UPPER 80S. AT 2 AM...VAN NUYS AIRPORT REPORTED 88 DEGREES
WITH A DEWPOINT OF 45. WHICH WAS 13 DEGREES WARMER THAN 24-HOURS
AGO. ALSO AT 2 AM...MALIBU HILLS WAS 94 DEGREES. THE LATEST
ACARS SOUNDING FROM LAX INDICATED A VERY STRONG INVERSION BEGINNING
AT 500 FT WITH A TEMP OF 73 DEGREES. AT THE TOP OF THE INVERSION
(2400 FT) THE TEMP WAS 94. THE BOTTOM LINE IS...UNLESS YOU ARE AT
THE IMMEDIATE COAST OR HAVE AIR CONDITIONING...YOU ARE PROBABLY NOT
A HAPPY CAMPER THIS MORNING. NEVERTHELESS...WE ARE ON TAP FOR
ANOTHER SCORCHER TODAY. AN EXCESSIVE HEAT WARNING HAS BEEN ISSUED
ONCE AGAIN FOR TODAY INCLUDING THE SAME LOCATIONS AS FRIDAY.
OVERALL...NORTH OF POINT CONCEPTION TEMPERATURES ACROSS THE CENTRAL
COAST SHOULD BE A FEW DEGREES COOLER TODAY AS OFFSHORE FLOW WILL
SHIFT TO SEABREEZE MUCH SOONER TODAY. HOWEVER TEMPS WILL CONTINUE TO
BE QUITE HOT INLAND WITH PASO ROBLES EXPECTED TO REACH 110 DEGREES.
THIS SAME TREND WILL BE LIKELY OCCUR ACROSS LA/VTU/SBA COUNTY
COASTAL AREAS AS WELL. DOWNTOWN LA SHOULD LOWER A DEGREE OR TWO
TODAY...BUT TEMPS WILL BE VERY SIMILAR TO YESTERDAY IN MANY OF THE
SAME LOCATIONS.
THERE WERE SEVERAL RECORD HIGH TEMPS RECORDED YESTERDAY INCLUDING
THE HOTTEST TEMPERATURE EVER RECORDED (110) AT SANTA MARIA SINCE
RECORDS WERE KEPT FROM 1929. AS MENTIONED EARLIER...THE FEELING IS
THAT HIGH TEMPS SHOULD LOWER 6 TO 10 DEGREES ALONG THE CENTRAL COAST
WITH A QUICKER RETURN OF THE SEABREEZE TODAY. SEE LAXPNSLOX FOR
UPDATED RECORDS FOR YESTERDAY.
BOTH WRF AND GFS INDICATE SOME WEAK VORTICITY ADVECTION AND LIMITED
MID LEVEL MOISTURE ACROSS THE MOUNTAINS OF SLO/SBA/VTU AND LA
COUNTIES LATER THIS AFTERNOON. THE BEST CONVECTIVE PARAMETERS APPEAR
TO BE OVER THE VTU COUNTY MTNS THIS AFTERNOON. WITH PWAT VALUES
BETWEEN .75 TO 1 INCH...AND A WEAK VORT PROGGED TO MOVE OVER THE
AREA THIS AFTERNOON...A FEW ELEVATED SHOWERS AND A SLIGHT CHANCE OF
A THUNDERSTORM HAVE BEEN ADDED TO THE MOUNTAIN ZONES THIS AFTERNOON.
OVERNIGHT TEMPERATURES WILL STILL REMAIN QUITE HIGH FOR MOST AREAS
WITH LOWS STILL ONLY LOWERING TO THE 70S...BUT MOST COASTAL AREAS
SHOULD LOWER TO AT LEAST THE 60S TONIGHT AS ONSHORE GRADIENTS WILL
BEGIN TO STRENGTHEN SOME.
FOR SUNDAY...THE UPPER HIGH BEGINS TO GET SQUASHED AND BECOME
ELONGATED TO OUR SOUTH AS A BROAD TROF BEGINS TO PUSH SOUTHEAST OUT
OF THE EASTERN PAC. THIS WILL HELP LOWER THICKNESS LVLS AND HIGHS
ACROSS MOST LOCATIONS WILL BE 5 TO 10 DEGREES COOLER AS MOST COASTAL
AREAS WILL BE IN THE MID 70S AND 80S. ALTHOUGH THERE WILL CONTINUE
TO BE HOT CONDITIONS ACROSS MANY PORTIONS OF THE INTERIOR VALLEYS
WITH TEMPS RANGING IN THE 90S TO LOWER 100S...AN EXCESSIVE HEAT
WATCH WAS NOT ISSUED FOR SUNDAY. THE THERMAL TROF WILL BEGIN TO
RE-ESTABLISH ACROSS THE INTERIOR OF SOUTHERN CALIFORNIA SUNDAY WHICH
WILL HELP TO INCREASE THE ONSHORE FLOW AND BRING A RETURN OF MORE
SEASONABLE CONDITIONS INCLUDING INCREASED LOW CLOUDS TO THE CENTRAL
COAST AND THE LA/VTU COUNTY COASTAL AREAS AS THE MARINE LAYER BEGINS
TO RE-ESTABLISH ITSELF SUNDAY NIGHT INTO MONDAY MORNING. A CONTINUED
COOLING TREND FOR MONDAY WHICH WILL FEEL MORE TYPICAL FOR JUNE.
EXPECT A MORE WIDESPREAD RETURN OF NIGHT THROUGH MORNING LOW CLOUDS
AFFECTING THE CENTRAL COAST AND LA/VTU COUNTY COASTAL AREAS AS WELL.
.LONG TERM...(TUE-FRI)
BOTH GFS AND ECMWF ARE IN PRETTY GOOD AGREEMENT FOR SLIGHTLY COOLER
CONDITIONS TUESDAY AND CONTINUED SIMILAR CONDITIONS THROUGH FRIDAY
AS UPPER TROF HANGS AROUND CALIFORNIA. THE UPPER HIGH THAT IS
LOCATED OVER SOUTHERN AZ/NM AND MEXICO COULD SHIFT INTO A MORE
FAVORABLE POSITION TO BRING THE POTENTIAL OF SOME SUB-TROPIC
MOISTURE UP FROM MEXICO. BUT MODELS ARE NOT HANDLING THIS WELL AT
THIS POINT.
&&
.AVIATION...WILL BE UPDATED WITH 12Z PACKAGE.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
EXCESSIVE HEAT WARNING (SEE LAXNPWLOX).
RED FLAG WARNING (SEE LAXRFWLOX).
&&
$$
PUBLIC...KAPLAN
AVIATION...RORKE
WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NWS KEY WEST FL
1101 AM EDT SAT JUN 21 2008
.DISCUSSION...
THE KEY WEST MORNING SOUNDING REVEALED A SEASONABLY MOIST AND
MODERATELY UNSTABLE STRATIFICATION WITH LITTLE CONVECTIVE INHIBITION.
HOWEVER...A FEW SIGNIFICANT DRY POCKETS WERE OBSERVED BETWEEN 700 AND
925MB. GEOPOTENTIAL HEIGHT RISES HAVE OCCURRED THROUGHOUT MOST OF THE
TROPOSPHERE ACROSS THE FLORIDA KEYS DURING THE LAST 24 HOURS...AND
MSL PRESSURES ARE UP ABOUT 2MB SINCE YESTERDAY MORNING. THE STRUCTURE
OF THE TROPOSPHERE OVER THE KEYS THIS MORNING IS CHARACTERIZED BY
TWO LEVELS OF NON-DIVERGENCE...WITH UPPER-TROPOSPHERIC LIFT AND LOWER-
TROPOSPHERIC SUBSIDENCE DETECTED. THE UPPER LIFT IS OCCURRING IN THE
FAVORED REGION EAST OF AN UPPER TROUGH AXIS WHICH WAS LOCATED OVER
THE WESTERN GULF BASIN. A MEAN LOWER-TROPOSPHERIC RIDGE WAS
POSITIONED NEARLY OVER THE KEYS THIS MORNING WITH WEAK DIFLUENT FLOW
PREVAILING IN THE BOUNDARY LAYER.
AS LONG AS THE ATMOSPHERE REMAINS DECOUPLED VERTICALLY...IT WILL BE
DIFFICULT TO ATTAIN ANY SIGNIFICANT CONVECTIVE COVERAGE...DESPITE
FAVORABLE BOUNDARY LAYER MOISTURE AND CONDITIONAL INSTABILITY.
RAINFALL WILL BE MOST LIKELY OVER AND NEAR LARGER ISLAND LAND MASSES
LATER THIS AFTERNOON AS ISLAND SEA-BREEZE CIRCULATIONS ATTAIN MAXIMUM
INTENSITY AND ASSOCIATED MESOSCALE LIFT. DRY POCKETS IN THE LOW
LEVELS ARE NOT LIKELY TO BE ERASED BY LAYERED LIFT...SO DRY AIR
ENTRAINMENT WILL BE A LIMITING FACTOR.
THE CURRENTLY ADVERTISED SLIGHT MEASURABLE RAIN CHANCES ARE ON
TARGET...AND NO UPDATES WILL BE FORTHCOMING.
&&
.MARINE...
LIGHT BREEZES WILL PREVAIL THIS AFTERNOON AS THE ATLANTIC SURFACE
RIDGE REMAINS NEARBY. THEREAFTER...A SLOW BUT GRADUAL FRESHENING OF
BREEZES IS EXPECTED AS WINDS TURN OUT OF THE EAST IN THE WAKE OF THE
NORTHWARD MOVING RIDGE.
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL TODAY AT THE KEY WEST AND MARATHON
TERMINALS. WE HAVE A LOT OF HIGHER CLOUDS PRESENT BUT THESE ARE NOT
SIGNIFICANT WITH RESPECT TO AIRCRAFT OPERATIONS SO WE HAVE NOT
REFERENCED THEM IN OUR TAFS.
ISOLATED SHOWERS ARE POSSIBLE TODAY. IF THUNDER THREATENS ONE OF THE
TERMINALS WE WILL ISSUE A TIMELY AMENDMENT.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...NONE.
&&
$$
PUBLIC/MARINE.........KASPER
AVIATION/NOWCASTS.....DFM
DATA COLLECTION.......ROSS
VISIT US ON THE WEB AT WWW.WEATHER.GOV/KEYWEST
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
142 PM EDT SUN JUN 22 2008
.SYNOPSIS...
A WEAK SURFACE TROUGH WILL MOVE THROUGH THE AREA TODAY CREATING
ANOTHER CHANCE OF THUNDERSTORMS. A SERIES OF DISTURBANCES WILL
CROSS THE REGION TONIGHT THROUGH MONDAY NIGHT CONTINUING THE
CHANCES OF THUNDERSTORMS. HIGH PRESSURE WILL BUILD OVER THE AREA
TUESDAY AFTERNOON AND REMAIN THROUGH WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WEAK SURFACE TROUGH WITH SATELLITE IMAGERY SHOWING THE UPPER LEVEL
SHORTWAVE SLOWLY MOVING INTO THE UPSTATE. SHOWERS WHICH POPPED UP
EARLIER HAVE DISSIPATED FOR THE TIME BEING WITH MODELS INDICATING
CHANCES OF THUNDERSTORMS THIS AFTERNOON. LAPS SOUNDINGS FROM CAE
AND MDCRS FROM CLT INDICATE PLENTY OF INSTABILITY ALONG WITH A BIT
HIGHER P/WATS THAN YESTERDAY. AS SUCH BELIEVE THERE WILL BE A
SLIGHT INCREASE IN COVERAGE OF THUNDERSTORMS THIS AFTERNOON VERSUS
YESTERDAY. THERE IS A SLIGHT CHANCE OF SEVERE THUNDERSTORMS THIS
AFTERNOON...WITH THE MAIN THREAT BEING WIND GUSTS (SHEAR IS VERY
WEAK) AND TO A LESSER EXTENT HAIL (FZL LEVEL AND WET BULB ZERO
HEIGHTS BETWEEN 12.5 AND 13.5 KFT). EXPECT CUMULUS TO BEGIN
DEVELOPING SHORTLY WITH CB/S BY 2 PM. UPDATE OUT SHORTLY TO ADJUST
CLOUDS AND POPS WITH ONLY COSMETIC CHANGES TO OTHER ELEMENTS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
CONVECTIVE ACTIVITY SHOULD CONTINUE INTO THE EVENING HOURS. WILL
GO SLIGHT CHANCE AFTER SUN GOES DOWN UNTIL MIDNIGHT WHEN CONDITIONS
BECOME MORE STABLE.
AGREE WITH NAM AND GFS BRINGING ANOTHER WEAK SHORT WAVE AND
TROUGH THROUGH AREA MONDAY. AIRMASS BECOMES CONDITIONALLY UNSTABLE
AGAIN IN THE AFTERNOON AND EVENING DURING THE HEAT OF THE DAY.
NAM AND GFS CAPES AROUND 1500 J/KG AND LIS -3/-4. WILL GO 20-30
PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS UNTIL NEAR MIDNIGHT.
HIGH PRESSURE BUILDS IN TUESDAY WITH DRY WARM WEATHER EXPECTED.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
IN GOOD AGREEMENT WITH GFS AND ECMWF SHOWING WEAK HIGH PRESSURE
OVER AREA DURING PERIOD. DRY INITIALLY TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT WITH WESTERLY WINDS. HIGH SHIFTS MORE EAST
THURSDAY THROUGH SATURDAY ALLOWING SOUTHERLY WINDS AND MORE
MOISTURE WITH SLIGHT CHANCE OF MAINLY AFTERNOON AND EVENING
SHOWERS AND THUNDERSTORMS LATER PORTION OF EXTENDED. TEMPERATURES
REMAIN QUITE WARM WITH HIGHS IN THE LOWER TO MID 90S. LOW
TEMPERATURES IN THE 60S TUESDAY NIGHT AND WEDNESDAY NIGHT INCREASE
TO NEAR 70 LATE IN PERIOD.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
VFR AND MVFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. UPPER
LEVEL DISTURBANCE AND A SURFACE TROUGH HAVE COMBINED TO PRODUCE
SHOWERS AND THUNDERSTORMS ACROSS THE AREA. SATELLITE IMAGERY AND
CAE WSR-88D SHOW STORMS CURRENTLY DEVELOPING AROUND ALL TAF
SITES. EXPECT THIS TREND TO CONTINUE OVER THE NEXT SEVERAL HOURS
BEFORE DECREASING WITH SUNSET. AFTER 05Z WILL AGAIN EXPECT MVFR
FOG TO DEVELOP AND PERSIST THROUGH 14/15Z...WHEN CUMULUS WILL
AGAIN BEGIN DEVELOPING. HAVE NOT INCLUDED CB OR THUNDERSTORMS FOR
THE END OF THE TAF PERIOD AS CONFIDENCE IS TOO LOW IN COVERAGE AND
TIMING.
MVFR CONDITIONS POSSIBLE IN THUNDERSTORMS MONDAY AFTERNOON AND
EVENING...OTHERWISE NO SIGNIFICANT IMPACTS TO AVIATION EXPECTED
MONDAY NIGHT THROUGH FRIDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1247 PM CDT SUN JUN 22 2008
.DISCUSSION...
319 AM CDT
POTENTIALLY ACTIVE WEATHER DAY ONCE AGAIN ACROSS THE AREA AS MAIN
UPPER LEVEL LOW CONTINUES TO SPIN ACROSS THE NORTHERN LAKES WHILE
MAIN UPPER RIDGE AMPLIFIES ACROSS THE NORTHERN HIGH PLAINS. MAIN
SHORTWAVE OF INTEREST IN THE NEAR TERM IS HIGHLY EVIDENT ON WATER
VAPOR IMAGERY THIS MORNING AS IT CONTINUES TO DIVE INTO THE UPPER
MISS RVR VLY FROM THE NORTHERN PLAINS. ON THE SFC...07Z OBJECTIVE
ANALYSIS SHOWS WELL DEFINED WIND SHIFT LINE/TROUGH STRETCHED FROM
NORTH CENTRAL WI...SWWD THROUGH SE MN. THIS FEATURE COMBINED WITH
APPROACHING SHORTWAVE TROUGH WILL LEAD TO INITIAL ROUND OF
SHWRS/STORMS THIS MORNING...AS SFC TROUGH AXIS CONTINUES TO SLIDE
INTO AREA.
LATEST SPC DAY 1 OUTLOOK HAS TRIMMED BACK SLIGHT RISK TO SOUTHERN
CWA WHICH APPEARS RATHER ACCEPTABLE CONSIDERING BEST DYNAMICS FOR
ORGANIZED CONVECTION WILL GRADUALLY SINK SOUTH AS THE DAY CONTINUES
ON. SHORT TERM GUIDANCE IN FAIRLY GOOD AGREEMENT WITH MAIN VORTEX TO
THE NORTH GRADUALLY SINKING SOUTHWARD ACROSS NORTHERN LAKES AS THE
DAY PROGRESSES. WITH THAT IN MIND...SHEAR AND INSTABILITY WILL ALSO
GRADUALLY SHIFT SOUTHWARDS THROUGHOUT THE DAY...AS MAIN SFC TROUGH
NOTED ABOVE SKIRTS SOUTHWARD AND 40-50KT MID LEVEL JET ARRIVE FROM
THE WEST. HOWEVER ENTIRE AREA IS BY NO MEANS OUT OF THE WOODS FOR
T-STORM DEVELOPMENT THIS MORNING AS SHORTWAVE TROUGH AND SFC TROUGH
AXIS ARRIVE DURING THE MID MORNING HRS. FAIRLY UNIMPRESSIVE
RADIATIONAL INVERSION NOTED ON LATEST ACARS SOUNDING FROM ORD THIS
MORNING AND BASED ON THIS...EXPECT VERY LITTLE CIN TO PREVENT
CONVECTIVE UPDRAFT INITIATION. WITH SUCH LIMITED WIND SHEAR
AVAILABLE (0-6KM BULK SHEAR VALUES OF ROUGHLY 20KTS) AND FAVORABLE
WET BULB ZERO LEVELS (8-9KFT) FEEL PULSE STORMS WILL BE THE MAIN
CONCERN THIS MORNING WITH MARGINAL HAIL AND DAMAGING WIND POTENTIAL
BEING THE BIGGEST THREATS. WRF/GFS IN GOOD AGREEMENT IN SHOWING
STEEPENING LOW LEVEL LAPSE RATES THROUGH THE MORNING DUE TO SOLAR
INSULATION...WITH MID LEVEL LAPSE RATES ALSO EXPECTED TO INCREASE AS
COLDER AIR IN ASSOCIATION WITH MAIN VORTEX TO THE NORTH SINKS
SOUTHWARD. ONLY CAVEAT RIGHT NOW IS JUST HOW MUCH CLOUD COVER WILL
MOVE IN EARLY THIS MORNING WITH APPROACHING SHORTWAVE...POSSIBLY
LIMITING DEGREE OF HEATING/INSTABILITY THIS MORNING. FOR NOW...HAVE
BUMPED POPS UP TO LIKELY ACROSS MUCH OF CWA WITH PREMISE THAT
SHWRS/STORMS MAY ARRIVE IN TWO SEPARATE BATCHES TODAY...WITH THE
SECOND BATCH ARRIVING THIS AFTERNOON AS NEXT SHORTWAVE CURRENTLY
ANALYZED NEAR THE ARROWHEAD OF MN ARRIVES BY AFTERNOON. AM EXPECTING
SECOND ROUND TO BE LESS OF A MENACE AS COMPARED TO THE FIRST AS ATM
WILL LIKELY BE STABILIZED DUE TO EARLIER CONVECTION... HOWEVER
CANNOT RULE OUT SCT STORMS.
BIG CHANGE IN WEATHER PATTERN EXPECTED BY MONDAY AS UPPER LEVEL
RIDGE OFF TO THE WEST FINALLY BEGINS NOSING INTO AREA...EFFECTIVELY
SENDING PESKY UPPER LEVEL LOW OFF TO THE EAST. SFC HIGH PRESSURE
EXPECTED TO GRADUALLY BUILD ACROSS REGION ON MONDAY...WITH NORTHERLY
TO NORTHEASTERLY FLOW EXPECTED AREA WIDE. FLOW OFF THE LAKE WILL
LEAD TO NOTICEABLE COOLER TEMPS ALONG THE IMMEDIATE LAKE
SHORE...WHERE ONLY UPPER 60S WILL BE POSSIBLE NORTH OF DOWNTOWN.
HIGH PRESSURE SIDES OFF TO THE EAST BY TUESDAY...WITH SOUTHEASTERLY
FLOW KEEPING IMMEDIATE LAKESHORE LOCATIONS COOLER ONCE AGAIN. UPPER
LEVEL FLOW EXPECTED TO DEAMPLIFY ON TUESDAY WITH FLOW BECOMING MORE
PROGRESSIVE WITH TIME. SHORTWAVE THROUGH EXPECTED TO BEGIN EJECTING
OUT THE OF THE CENTRAL PLAINS LATE TUESDAY...WITH MCS DEVELOPMENT
LIKELY ACROSS THE EASTERN CENTRAL PLAINS/MID MISS RVR VLY TUE NIGHT.
MODELS SHOWING RATHER IMPRESSIVE MOISTURE RETURN INTO AREA...HOWEVER
AS IS USUALLY THE CASE WITH THESE SITUATIONS...AVAILABLE MOISTURE
MAY BE OVERDONE WITH RATHER NOTICEABLE RIDGE AXIS PRESENT ACROSS
NORTHERN HALF OF GULF OF MEXICO. REGARDLESS...THIS FEATURE IS BEEN
WELL ADVERTISED IN RECENT DAYS AND CONFIDENCE IS INCREASING.
SO...EXPECT INCREASED CLOUDINESS TUE NIGHT WITH SCT ELEVATED
SHWRS/STORMS POSSIBLE BY WEDNESDAY MORNING ACROSS THE AREA AS MAIN
WARM FRONT LIES TO THE WEST OF THE REGION. TEMPS EXPECTED TO BEGIN
REBOUNDING ON TUE WITH RETURN OF SOUTHERLY FLOW ON TUE...WITH TREND
CONTINUING THROUGH MIDDLE TO LATTER PORTIONS OF THE WEEK.
GITRO
&&
.AVIATION...
1241 PM CDT
1800 UTC TAFS...FAIRLY TURBULENT DAY COMING INTO THE REGION TODAY
AS THUNDERSTORMS DEVELOP ACROSS THE TAF REGION OVER THE NEXT HOUR
OR SO AND LINGER THROUGH EARLY THIS EVENING. THE ATMOSPHERE IS
CURRENTLY UNSTABLE ENOUGH THAT CLEAR SKIES HAVE RAPIDLY TURNED
INTO A WIDESPREAD CU FIELD WITH SOME TOWERING CU MIXED IN. CURRENT
THINKING IS THAT STORMS WILL MAINLY COME IN TWO WAVES...ONE
THROUGH MID-AFTERNOON AND ANOTHER TONIGHT AS AN UPPER LEVEL
DISTURBANCE DROPS DOWN FROM WISCONSIN. TRENDED A BIT MORE ON THE
PESSIMISTIC SIDE EVEN THOUGH FORECAST CONFIDENCE IN TIMING ISNT
THE BEST DUE TO HOW TURBULENT THE CURRENT AIRSPACE AND HOW FAST A
TCU COULD DEVELOP. WIND FIELD IS CURRENTLY A MESS WITH A LEFTOVER
OUTFLOW BOUNDARY ALONG THE LAKE MICHIGAN SHORELINE AND ANOTHER SFC
TROF EXTENDING FROM EASTERN WISCONSIN ON DOWN INTO NORTHERN
ILLINOIS. THESE FEATURES MAY BECOME THE FOCUS FOR FURTHER
STORM DEVELOPMENT THIS AFTERNOON. WINDS SHOULD EVENTUALLY BECOME
NORTHWEST THROUGHOUT THE REGION THIS AFTERNOON...GOING NORTH
TOMORROW MORNING.
EXPECT MAINLY VFR CONDITIONS THROUGHOUT THE PERIOD WITH SOME BRIEF
DROPS DOWN TO MVFR POSSIBLE WITHIN THUNDERSTORMS.
HALBACH
&&
.MARINE...
1246 PM CDT
OUTSIDE OF SCATTERED THUNDERSTORMS CROSSING THROUGH THE
LAKE...SHOULD BE A FAIRLY QUIET PERIOD ACROSS LAKE MICHIGAN WITH
NORTHWESTERLY WINDS BECOMING SOUTHERLY LATER IN THE PERIOD. WITH
WINDS REMAINING RATHER LOW...WAVES WILL STAY DOWN AS WELL.
HALBACH
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
911 PM EDT SUN JUN 22 2008
.SHORT TERM UPDATE (TONIGHT)...
MINIMAL CHANGES TO OVERNIGHT FORECAST NEEDED. LOWERED POPS ACROSS
MUCH OF THE FORECAST AREA THROUGH MIDNIGHT AND DRIED OUT ENTIRE FA
THEREAFTER. SHOWERS AND THUNDERSTORMS CURRENTLY ACROSS CENTRAL
INDIANA APPEAR TO BE WEAKENING...HOWEVER CAN NOT RULE OUT ONE OF
THESE HOLDING TOGETHER AND AFFECTING PARTS OF SOUTH CENTRAL INDIANA
AND NORTH CENTRAL KENTUCKY THROUGH MIDNIGHT. EXPECT ANY SHOWERS OR
THUNDERSTORMS THAT MOVE INTO THESE AREAS TO QUICKLY WEAKEN AS
ENVIRONMENT BECOMES LESS FAVORABLE TO SUPPORT THUNDERSTORM ACTIVITY
FURTHER SOUTH.
OTHERWISE...EXPECT PARTLY CLOUDY SKIES OVERNIGHT WITH LOW
TEMPERATURES IN THE MID 50S TO LOW 60S.
PREVIOUS DISCUSSION...
.SHORT TERM (TONIGHT AND MONDAY)...
AS EXPECTED...CU FIELD HAS BEEN SUPPRESSED OVER CENTRAL KY EARLY
THIS AFTERNOON AS HEATING AND RESULTANT STEEPENING BOUNDARY LAYER
LAPSE RATES HAS CAUSED DRY LOW LEVEL AIR TO MIX DOWN TO SFC. AS A
RESULT...SFC DEWPOINTS WHICH WERE IN LOWER 60S THIS MORNING HAVE
DROPPED TO THE LOWER 50S AT THIS TIME...WITH SFC BASED LI VALUES
ONLY ABOUT -1 HERE. HOWEVER...SFC DEWPOINTS INCREASE AGAIN JUST TO
THE NORTH ASSOCIATED WITH BAND OF CLOUDS AND FORCING OVER SRN IN
AND SRN IL AHEAD OF SHORTWAVE TROF ALOFT. TSTMS HAVE BEGUN TO
DEVELOP ON LEADING EDGE OF THESE CLOUDS WITHIN LI GRADIENT ZONE OVER
SRN IN. ACTIVITY SHOULD CONTINUE TO INCREASE AND MOVE SEWD INTO
PARTS OF CNTRL KY LATE THIS AFTERNOON AND EVENING. GIVEN MORNING
SOUNDINGS AND A LOOK AT A COUPLE OF ACARS SOUNDINGS SUGGEST THAT
SEVERE MICROBURST POTENTIAL REMAINS POSSIBLE FROM THE STRONGEST
CELLS WITH HAIL AND STRONG WINDS.
MOST CELLS SHOULD DISSIPATE LATER THIS EVENING AS INSTABILITY WANES.
HOWEVER...BOTH 12Z NAM-WRF (AND NAM-NMM CORE) AND GFS SUGGEST
ELEVATED STEEP LAPSE RATES WILL REMAIN OVER S-CNTRL KY LATE TONIGHT
AND MONDAY MORNING WITH ISOLATED OR SCT ELEVATED TSTMS POSSIBLE.
ON MONDAY...STRONG TROFING ALOFT WILL CONTINUE OVER FORECAST AREA
WITH H5 TEMPS PREDICTED TO BE AROUND -16C. COLD MID LEVEL TEMPS
COMBINED WITH DIURNAL LOW-LEVEL HEATING AND PRESENCE OF A WEAK
FRONTAL/CONVERGENCE BOUNDARY SHOULD RESULT IN DEVELOPMENT OF SCT
AFTERNOON TSTMS...ESPECIALLY OVER ERN AREAS...WITH SMALL HAIL AND
LOCALLY GUSTY WINDS AGAIN A POSSIBILITY. ANY TSTMS SHOULD DISSIPATE
QUICKLY WITH LOSS OF HEATING BY MONDAY EVENING.
.LONG TERM (MONDAY NIGHT THROUGH SUNDAY)...
MONDAY NIGHT THROUGH TUESDAY NIGHT
SFC RIDGING WILL BUILD INTO THE REGION FROM THE WEST ALLOWING SKIES
TO CLEAR AND KEEP THE WEATHER DRY MONDAY NIGHT THROUGH TUESDAY
NIGHT. AFTER MORNING LOWS IN THE UPPER 50S...WE EXPECT TEMPERATURES
TO REBOUND INTO THE LOWER 80S ACROSS THE NORTHEAST WITH MID 80S
ACROSS THE CENTRAL AND SOUTHWEST PORTIONS OF THE FORECAST AREA
(FA). OVERNIGHT LOWS WILL DROP BACK INTO THE UPPER 50S TO THE LOWER
60S TUESDAY NIGHT.
WEDNESDAY THROUGH SUNDAY...
LONG TERM MODEL SOLUTIONS CONTINUE TO BE IN PRETTY GOOD AGREEMENT
THROUGH THE PD. OVERALL FLOW PATTERN LOOKS TO BE SIMILAR TO WHAT WE
SAW YESTERDAY. SYNOPTIC FLOW PATTERN WILL TAKE ON A RIDGE IN THE
WEST WITH A BROAD TROF IN THE EAST WHICH WILL RESULT IN A GENERAL
NORTHWEST TO WEST-NORTHWEST FLOW ACROSS THE OHIO VALLEY.
OVERALL WEATHER PATTERN WILL BECOME MORE ACTIVE AS THE WEEK GOES ON
WITH SEVERAL VORTICITY MAXIMA CRUISING THROUGH THE FLOW. THE EXACT
TIMING OF THESE WAVES IS RATHER DIFFICULT AT THIS TIME FRAME.
HOWEVER IT DOES APPEAR THAT ONE WAVE WILL AFFECT THE REGION LATE
WEDNESDAY WITH A SECONDARY ONE CRUISING IN AROUND FRIDAY AND THEN
YET ANOTHER ONE AROUND LATE SUNDAY. WITH EACH WAVE...WE EXPECT A
CLUSTER OF STORMS ASSOCIATED WITH THEM...HOWEVER...EVEN IN THE
ABSENCE OF THE VORTS...STRONG DAYTIME HEATING COMBINED WITH
INCREASING INSTABILITY WILL RESULT IN DIURNAL CONVECTION ACROSS THE
REGION. THEREFORE...WILL BE KEEPING A DAILY CHANCE OF SHOWERS AND
THUNDERSTORMS IN THE FCST FOR WED-SUN...WITH THE BEST CHANCES MAINLY
IN THE AFTERNOON AND EVENING HOURS.
WITH INCREASING HEIGHTS...AM EXPECTING ANOTHER MODERATING TREND IN
TEMPS. TEMPS SHOULD RUN SLIGHTLY ABOVE NORMAL FOR THE PERIOD WITH
AFTERNOON READINGS TOPPING OUT IN THE MID TO UPPER 80S AND OVERNIGHT
LOWS IN THE MID TO UPPER 60S. GENERALLY STAYED PRETTY CLOSE TO THE
GFS ENSEMBLE MOS THROUGH THE PD...WHICH MAINTAINS EXCELLENT
CONTINUITY WITH THE PREVIOUS FCST.
&&
.AVIATION (00Z TAFS)...
ISOLATED TO SCT TSTMS UPSTREAM WILL LIKELY DISSIPATE EARLY IN THIS
PERIOD...LEAVING SCT...MAINLY MID LEVEL DEBRIS CLOUDS FROM EARLIER
CONVECTION...PRIMARILY ACRS THE LEX AREA. SDF AND BWG SHUD BE MOSTLY
CLR OVERNIGHT. VSBYS EXPECTED TO FALL TO MVFR AGAIN IN FOG FOR LEX
AND BWG...DEVELOPING BY THE 07Z-09Z TIME FRAME. AFTER FOG DISSIPATES
BY 13Z...FEW CLOUDS EXPECTED UNTIL CU BECOME SCT TO BKN BY MIDDAY
FOR ALL TAF SITES.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
SHORT TERM...LS/TWF
LONG TERM....MJ
AVIATION.....11
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
730 PM EDT SUN JUN 22 2008
.SHORT TERM (TONIGHT AND MONDAY)...
AS EXPECTED...CU FIELD HAS BEEN SUPPRESSED OVER CENTRAL KY EARLY
THIS AFTERNOON AS HEATING AND RESULTANT STEEPENING BOUNDARY LAYER
LAPSE RATES HAS CAUSED DRY LOW LEVEL AIR TO MIX DOWN TO SFC. AS A
RESULT...SFC DEWPOINTS WHICH WERE IN LOWER 60S THIS MORNING HAVE
DROPPED TO THE LOWER 50S AT THIS TIME...WITH SFC BASED LI VALUES
ONLY ABOUT -1 HERE. HOWEVER...SFC DEWPOINTS INCREASE AGAIN JUST TO
THE NORRTH ASSOCIATED WITH BAND OF CLOUDS AND FORCING OVER SRN IN
AND SRN IL AHEAD OF SHORTWAVE TROF ALOFT. TSTMS HAVE BEGUN TO
DEVELOP ON LEADING EDGE OF THESE CLOUDS WITHIN LI GRADIENT ZONE OVER
SRN IN. ACTIVITY SHOULD CONTINUE TO INCREASE AND MOVE SEWD INTO
PARTS OF CNTRL KY LATE THIS AFTERNOON AND EVENING. GIVEN MORNING
SOUNDINGS AND A LOOK AT A COUPLE OF ACARS SOUNDINGS SUGGEST THAT
SEVERE MICROBURST POTENTIAL REMAINS POSSIBLE FROM THE STRONGEST
CELLS WITH HAIL AND STRONG WINDS.
MOST CELLS SHOULD DISSIPATE LATER THIS EVENING AS INSTABILITY WANES.
HOWEVER...BOTH 12Z NAM-WRF (AND NAM-NMM CORE) AND GFS SUGGEST
ELEVATED STEEP LAPSE RATES WILL REMAIN OVER S-CNTRL KY LATE TONIGHT
AND MONDAY MORNING WITH ISOLATED OR SCT ELEVATED TSTMS POSSIBLE.
ON MONDAY...STRONG TROFING ALOFT WILL CONTINUE OVER FORECAST AREA
WITH H5 TEMPS PREDICTED TO BE AROUND -16C. COLD MID LEVEL TEMPS
COMBINED WITH DIURNAL LOW-LEVEL HEATING AND PRESENCE OF A WEAK
FRONTAL/CONVERGENCE BOUNDARY SHOULD RESULT IN DEVELOPMENT OF SCT
AFTERNOON TSTMS...ESPECIALLY OVER ERN AREAS...WITH SMALL HAIL AND
LOCALLY GUSTY WINDS AGAIN A POSSIBILITY. ANY TSTMS SHOULD DISSIPATE
QUICKLY WITH LOSS OF HEATING BY MONDAY EVENING.
.LONG TERM (MONDAY NIGHT THROUGH SUNDAY)...
MONDAY NIGHT THROUGH TUESDAY NIGHT
SFC RIDGING WILL BUILD INTO THE REGION FROM THE WEST ALLOWING SKIES
TO CLEAR AND KEEP THE WEATHER DRY MONDAY NIGHT THROUGH TUESDAY
NIGHT. AFTER MORNING LOWS IN THE UPPER 50S...WE EXPECT TEMPERATURES
TO REBOUND INTO THE LOWER 80S ACROSS THE NORTHEAST WITH MID 80S
ACROSS THE CENTRAL AND SOUTHWEST PORTIONS OF THE FORECAT AREA (FA).
OVERNIGHT LOWS WILL DROP BACK INTO THE UPPER 50S TO THE LOWER 60S
TUESDAY NIGHT.
WEDNESDAY THROUGH SUNDAY...
LONG TERM MODEL SOLUTIONS CONTINUE TO BE IN PRETTY GOOD AGREEMENT
THROUGH THE PD. OVERALL FLOW PATTERN LOOKS TO BE SIMILAR TO WHAT WE
SAW YESTERDAY. SYNOPTIC FLOW PATTERN WILL TAKE ON A RIDGE IN THE
WEST WITH A BROAD TROF IN THE EAST WHICH WILL RESULT IN A GENERAL
NORTHWEST TO WEST-NORTHWEST FLOW ACROSS THE OHIO VALLEY.
OVERALL WEATHER PATTERN WILL BECOME MORE ACTIVE AS THE WEEK GOES ON
WITH SEVERAL VORTICITY MAXIMA CRUISING THROUGH THE FLOW. THE EXACT
TIMING OF THESE WAVES IS RATHER DIFFICULT AT THIS TIME FRAME.
HOWEVER IT DOES APPEAR THAT ONE WAVE WILL AFFECT THE REGION LATE
WEDNESDAY WITH A SECONDARY ONE CRUISING IN AROUND FRIDAY AND THEN
YET ANOTHER ONE AROUND LATE SUNDAY. WITH EACH WAVE...WE EXPECT A
CLUSTER OF STORMS ASSOCIATED WITH THEM...HOWEVER...EVEN IN THE
ABSENCE OF THE VORTS...STRONG DAYTIME HEATING COMBINED WITH
INCREASING INSTABILITY WILL RESULT IN DIURNAL CONVECTION ACROSS THE
REGION. THEREFORE...WILL BE KEEPING A DAILY CHANCE OF SHOWERS AND
THUNDERSTORMS IN THE FCST FOR WED-SUN...WITH THE BEST CHANCES MAINLY
IN THE AFTERNOON AND EVENING HOURS.
WITH INCREASING HEIGHTS...AM EXPECTING ANOTHER MODERATING TREND IN
TEMPS. TEMPS SHOULD RUN SLIGHTLY ABOVE NORMAL FOR THE PERIOD WITH
AFTERNOON READINGS TOPPING OUT IN THE MID TO UPPER 80S AND OVERNIGHT
LOWS IN THE MID TO UPPER 60S. GENERALLY STAYED PRETTY CLOSE TO THE
GFS ENSEMBLE MOS THROUGH THE PD...WHICH MAINTAINS EXCELLENT
CONTINUITY WITH THE PREVIOUS FCST.
&&
.AVIATION (00Z TAFS)...
ISOLATED TO SCT TSTMS UPSTREAM WILL LIKELY DISSIPATE EARLY IN THIS
PERIOD...LEAVING SCT...MAINLY MID LEVEL DEBRIS CLOUDS FROM EARLIER
CONVECTION...PRIMARILY ACRS THE LEX AREA. SDF AND BWG SHUD BE MOSTLY
CLR OVERNIGHT. VSBYS EXPECTED TO FALL TO MVFR AGAIN IN FOG FOR LEX
AND BWG...DEVELOPING BY THE 07Z-09Z TIME FRAME. AFTER FOG DISSIPATES
BY 13Z...FEW CLOUDS EXPECTED UNTIL CU BECOME SCT TO BKN BY MIDDAY
FOR ALL TAF SITES.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
SHORT TERM...TWF
LONG TERM....MJ
AVIATION.....11
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
300 PM EDT SUN JUN 22 2008
.SHORT TERM (TONIGHT AND MONDAY)...
AS EXPECTED...CU FIELD HAS BEEN SUPPRESSED OVER CENTRAL KY EARLY
THIS AFTERNOON AS HEATING AND RESULTANT STEEPENING BOUNDARY LAYER
LAPSE RATES HAS CAUSED DRY LOW LEVEL AIR TO MIX DOWN TO SFC. AS A
RESULT...SFC DEWPOINTS WHICH WERE IN LOWER 60S THIS MORNING HAVE
DROPPED TO THE LOWER 50S AT THIS TIME...WITH SFC BASED LI VALUES
ONLY ABOUT -1 HERE. HOWEVER...SFC DEWPOINTS INCREASE AGAIN JUST TO
THE NORRTH ASSOCIATED WITH BAND OF CLOUDS AND FORCING OVER SRN IN
AND SRN IL AHEAD OF SHORTWAVE TROF ALOFT. TSTMS HAVE BEGUN TO
DEVELOP ON LEADING EDGE OF THESE CLOUDS WITHIN LI GRADIENT ZONE OVER
SRN IN. ACTIVITY SHOULD CONTINUE TO INCREASE AND MOVE SEWD INTO
PARTS OF CNTRL KY LATE THIS AFTERNOON AND EVENING. GIVEN MORNING
SOUNDINGS AND A LOOK AT A COUPLE OF ACARS SOUNDINGS SUGGEST THAT
SEVERE MICROBURST POTENTIAL REMAINS POSSIBLE FROM THE STRONGEST
CELLS WITH HAIL AND STRONG WINDS.
MOST CELLS SHOULD DISSIPATE LATER THIS EVENING AS INSTABILITY WANES.
HOWEVER...BOTH 12Z NAM-WRF (AND NAM-NMM CORE) AND GFS SUGGEST
ELEVATED STEEP LAPSE RATES WILL REMAIN OVER S-CNTRL KY LATE TONIGHT
AND MONDAY MORNING WITH ISOLATED OR SCT ELEVATED TSTMS POSSIBLE.
ON MONDAY...STRONG TROFING ALOFT WILL CONTINUE OVER FORECAST AREA
WITH H5 TEMPS PREDICTED TO BE AROUND -16C. COLD MID LEVEL TEMPS
COMBINED WITH DIURNAL LOW-LEVEL HEATING AND PRESENCE OF A WEAK
FRONTAL/CONVERGENCE BOUNDARY SHOULD RESULT IN DEVELOPMENT OF SCT
AFTERNOON TSTMS...ESPECIALLY OVER ERN AREAS...WITH SMALL HAIL AND
LOCALLY GUSTY WINDS AGAIN A POSSIBILITY. ANY TSTMS SHOULD DISSIPATE
QUICKLY WITH LOSS OF HEATING BY MONDAY EVENING.
.LONG TERM (MONDAY NIGHT THROUGH SUNDAY)...
MONDAY NIGHT THROUGH TUESDAY NIGHT
SFC RIDGING WILL BUILD INTO THE REGION FROM THE WEST ALLOWING SKIES
TO CLEAR AND KEEP THE WEATHER DRY MONDAY NIGHT THROUGH TUESDAY
NIGHT. AFTER MORNING LOWS IN THE UPPER 50S...WE EXPECT TEMPERATURES
TO REBOUND INTO THE LOWER 80S ACROSS THE NORTHEAST WITH MID 80S
ACROSS THE CENTRAL AND SOUTHWEST PORTIONS OF THE FORECAT AREA (FA).
OVERNIGHT LOWS WILL DROP BACK INTO THE UPPER 50S TO THE LOWER 60S
TUESDAY NIGHT.
WEDNESDAY THROUGH SUNDAY...
LONG TERM MODEL SOLUTIONS CONTINUE TO BE IN PRETTY GOOD AGREEMENT
THROUGH THE PD. OVERALL FLOW PATTERN LOOKS TO BE SIMILAR TO WHAT WE
SAW YESTERDAY. SYNOPTIC FLOW PATTERN WILL TAKE ON A RIDGE IN THE
WEST WITH A BROAD TROF IN THE EAST WHICH WILL RESULT IN A GENERAL
NORTHWEST TO WEST-NORTHWEST FLOW ACROSS THE OHIO VALLEY.
OVERALL WEATHER PATTERN WILL BECOME MORE ACTIVE AS THE WEEK GOES ON
WITH SEVERAL VORTICITY MAXIMA CRUISING THROUGH THE FLOW. THE EXACT
TIMING OF THESE WAVES IS RATHER DIFFICULT AT THIS TIME FRAME.
HOWEVER IT DOES APPEAR THAT ONE WAVE WILL AFFECT THE REGION LATE
WEDNESDAY WITH A SECONDARY ONE CRUISING IN AROUND FRIDAY AND THEN
YET ANOTHER ONE AROUND LATE SUNDAY. WITH EACH WAVE...WE EXPECT A
CLUSTER OF STORMS ASSOCIATED WITH THEM...HOWEVER...EVEN IN THE
ABSENCE OF THE VORTS...STRONG DAYTIME HEATING COMBINED WITH
INCREASING INSTABILITY WILL RESULT IN DIURNAL CONVECTION ACROSS THE
REGION. THEREFORE...WILL BE KEEPING A DAILY CHANCE OF SHOWERS AND
THUNDERSTORMS IN THE FCST FOR WED-SUN...WITH THE BEST CHANCES MAINLY
IN THE AFTERNOON AND EVENING HOURS.
WITH INCREASING HEIGHTS...AM EXPECTING ANOTHER MODERATING TREND IN
TEMPS. TEMPS SHOULD RUN SLIGHTLY ABOVE NORMAL FOR THE PERIOD WITH
AFTERNOON READINGS TOPPING OUT IN THE MID TO UPPER 80S AND OVERNIGHT
LOWS IN THE MID TO UPPER 60S. GENERALLY STAYED PRETTY CLOSE TO THE
GFS ENSEMBLE MOS THROUGH THE PD...WHICH MAINTAINS EXCELLENT
CONTINUITY WITH THE PREVIOUS FCST.
&&
.AVIATION (18Z TAFS)...
CU FIELD DEVELOPING AT THIS TIME OVER MUCH OF FCST AREA...WITH MOST
PRONOUNCED CU S AND E OF BWG AND LEX. MEANWHILE...MORE SUBSTANTIAL
CLOUDS CURRENTLY MOVING SEWD OVER SRN IL AND WRN IN AHEAD OF A
SHORTWAVE TROF JUST TO W OF CLOUD AXIS. SCT TSTMS BEGINNING TO
DEVELOP JUST AHEAD OF CLOUD AXIS IN AREA OF HEATING. THESE WILL MOVE
SEWD WITH ADDITIONAL SCT TSTM DEVELOPMENT EXPECTED THIS AFTERNOON.
TSTMS SHOULD REMAIN SCT FOR THE MOST PART...SO WILL INCLUDE VCTS IN
TAF SITES STARTING MID TO LATE AFTERNOON AND ENDING LATER THIS
EVENING. PREVAILING WIND WILL BE SW TO W AROUND 10 KTS OR LESS...BUT
ISOLATED WIND GUSTS OF 30-40 KTS ARE POSSIBLE WITH THE STRONGEST
CELLS. OVERNIGHT...COULD AGAIN SEE AREAS OF MVFR IN FOG/HAZE TOWARD
DAYBREAK.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
SHORT TERM...TWF
LONG TERM....MJ
AVIATION.....TWF
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
332 AM EDT SAT JUN 21 2008
.SYNOPSIS...
A TROUGH OF LOW PRESSURE WILL REMAIN ACROSS THIS AREA
TODAY...BRINGING SCATTERED THUNDERSTORMS IN THE AFTERNOON AND
NUMEROUS TSTMS THIS EVENING. A COLD FRONT WILL PRODUCE SCATTERED
THUNDERSTORMS ON SUNDAY. THE FRONT WILL GET HUNG UP ACROSS THE
AREA MONDAY...KEEPING UNSETTLED CONDITIONS IN THE FORECAST THROUGH
MON NIGHT. HIGH PRESSURE WILL BUILD OVER THE REGION TUESDAY. &&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WATER VAPOR LOOP SHOWS AN UPPER LOW OVER SOUTHEAST CANADA...WITH A
RIDGE OVER NORTHERN MEXICO AND THE SOUTHWEST CONUS. A TROUGH WAS
PASSING OVERHEAD...WITH A NOTABLE SHORTWAVE OVER THE MIDDLE
MISSISSIPPI RIVER VALLEY. THE NEXT TROUGH WAS SLIDING SOUTHEAST OVER
THE UPPER MIDWEST. ACARS 400-250MB WIND OBSERVATIONS INDICATE A
POSITIVELY TILTED UPPER TROUGH FROM THE EASTERN GREAT LAKES
SOUTHWEST TO THE PLAINS. A 80-100KT SOUTHWESTERLY JET EXTENDS FROM
THE BASE OF THE TROUGH EAST OVER THE MID ATLANTIC...WITH A 50-80KT
ANTICYCLONICALLY CURVED JET ON THE BACKSIDE OF THE TROUGH OVER THE
NORTHERN PLAINS. 03Z SURFACE ANALYSIS PLACED A 1018MB ANTICYCLONE
OVER THE TENNESSEE VALLEY. A WARM/STATIONARY BOUNDARY EXTENDED FROM
A TRIPLE POINT IN NORTHEAST IOWA SOUTHEAST ALONG THE EASTERN GULF
STATES. A COLD FRONT WAS STALLING ACROSS THE PLAINS...WITH A
SECONDARY COLD FRONT SLIDING SOUTHEAST ACROSS THE UPPER MIDWEST.
ISOLATED TO SCATTERED SHOWER AND THUNDERSTORM ACTIVITY IS SHOWING A
DOWNWARD TREND ACROSS THE EASTERN FORECAST AREA EARLY THIS MORNING.
CONVECTION WAS TRIGGERED AHEAD OF THE MID LEVEL TROUGH. THE 21Z SREF
MUCAPE AXIS ERODES ACROSS THE REGION EARLY THIS MORNING.
OTHERWISE...PATCHY FOG HAS DEVELOPED ACROSS CLIMATOLOGICALLY
FAVORED VALLEYS WITH THE INCREASE IN MOISTURE OVERNIGHT.
ANTICIPATE SKIES TO PARTIALLY CLEAR THIS MORNING...BEFORE CONVECTION
REDEVELOPS WITH BUILDING AFTERNOON INSTABILITY AHEAD OF THE MID
LEVEL TROUGH AXIS. A WARM FRONT CURRENTLY ACROSS THE CAROLINA COAST
IS FORECAST TO LIFT NORTHWARD THIS AFTERNOON...STRENGTHENING A
SOUTHERLY FLOW BY LATE AFTERNOON.
WIND COLUMN IS RATHER LIGHT TODAY...YIELDING LITTLE IN THE WAY OF
DEEP LAYER SHEAR. THIS HOWEVER WILL CONTRIBUTE TO STORM MOTIONS OF
LESS THAN 15 MPH. INVERTED-V BOUNDARY LAYER FORECAST SOUNDING SHOULD
SUPPORT GUSTY OUTFLOWS WHICH MAY SERVE TO CLUSTER STORMS. WITH
PRECIPITABLE WATER VALUES CLIMBING TO 1.25"...WILL HAVE TO MONITOR
FOR LOCALIZED HEAVY RAIN.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
EXPECT ACTIVITY TO INCREASE IN COVERAGE THIS EVENING WITH THE
APPROACH OF A SHORTWAVE CURRENTLY ACROSS THE TENNESSEE VALLEY. 00Z
NAM/GFS AND 21Z SREF ALL INDICATE PRESENCE OF ELEVATED INSTABILITY
THROUGH THE NIGHT.
PASSAGE OF THE SHORTWAVE SHOULD SERVE TO SUPPRESS CONVECTION SUNDAY
MORNING...BEFORE CONVECTIVE REDEVELOPMENT DURING THE AFTERNOON AS
THE MID LEVEL TROUGH DEEPENS ACROSS THE GREAT LAKES. WITH THE
STRENGTHENING WIND FIELD...DEEP LAYER EFFECTIVE SHEAR IS FORECAST TO
INCREASE ABOVE 30 KTS. THIS COULD FAVOR LONGER LIVED THUNDERSTORMS
WITH A SLIGHT RISK FOR LOCALLY DAMAGING WINDS AND LARGE HAIL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
UNDER INFLUENCE OF OH VALLEY TROF AT BEGINNING OF PD...WHICH THEN
MOVES EWD AND OFF THE COAST BY TUE NIGHT. THEN PD OF H5 HEIGHT
RISES UNTIL THU NIGHT WHEN H5 FLOW GOES ZONAL. AT SFC...WAVES AND
TROFS AND EVEN A CLOSED LOW SHOWS UP ON THE 00Z GFS SOLN FOR EARLY
IN THE LONG TERM...WHICH WILL GIVE US A PD OF SHOWERY WX UNTIL TUE
AS SFC HIGH OVER TN VALLEY FINALLY MAKES WAY INTO MID ATLC.
MAX/MIN TEMPS FOR THE LONG TERM WILL BE VERY SEASONABLE...WITH HIGHS
IN THE M/U80S AND LOWS L/M60S UNTIL LATE IN THE WEEK WHEN SFC DWPTS
AOA U60S COME IN AND CREATE SOME BALMY NIGHTS. XPCTNG TUE-THU TO BE
A STRING OF PCPN FREE DAYS.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
EXPECT PATCHY FOG TO DEVELOP AS DEWPOINT DEPRESSIONS FALL TO NEAR
ZERO LEADING UP TO SUNRISE. SCATTERED CONVECTION FORECAST TO DEVELOP
DURING THE AFTERNOON AS MOISTURE INCREASES AHEAD OF AN UPPER TROUGH.
AN APPROACHING SHORTWAVE ALONG WITH ELEVATED INSTABILITY SHOULD
ALLOW CONVECTION TO LINGER TONIGHT. HAVE REPRESENTED THIS ACTIVITY
WITH VCSH IN TAFS FOR NOW. THUNDER MAY HAVE TO BE INCLUDED TONIGHT
BASED ON TIMING OF ACTIVITY INTO THE REGION THIS EVENING.
TSTMS WILL BE PRESENT THROUGH MON NIGHT IMPACTING VSBYS AND
WIND...FOLLOWED BY A PERIOD OF BENIGN AVN WEATHER TUE THRU WED.
&&
.MARINE...
PERIODS OF SHOWERS AND THUNDERSTORMS EXPECTED THIS WEEKEND. SOME OF
THE STORMS MAY BECOME STRONG OR SEVERE...AND MAY WARRANT SPECIAL
MARINE WARNINGS...ESPECIALLY SUNDAY AFTERNOON.
SOUTHERLY WINDS INCREASE LATE THIS AFTERNOON AND TONIGHT AS A WARM
FRONT LIFTS INTO THE REGION. WINDS ARE CURRENTLY FORECAST JUST UNDER
SMALL CRAFT CRITERIA AT 15 KNOTS ACROSS THE MID BAY AND LOWER TIDAL
POTOMAC RIVER.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...LEE
NEAR TERM...SJR
SHORT TERM...SJR
LONG TERM...LEE
AVIATION...SJR/LEE
MARINE...SJR
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1110 AM EDT SAT JUN 21 2008
.SHORT TERM...
WATER VAPOR IMAGERY AND RUC SHOW A PAIR OF LOW CENTERS EMBEDDED
IN A LONGWAVE TROUGH AND ARE OVER ONTARIO AND QUEBEC...A RIDGE OVER
THE CANADIAN PRAIRIE...AND ANOTHER TROUGH OVER EASTERN PACIFIC JUST
WEST OF BRITISH COLUMBIA. A WEAK SHORTWAVE ROTATING AROUND THE BASE
OF THE ONTARIO LOW IS SWEEPING THROUGH THE FORECAST AREA. SURFACE
ANALYSIS DEPICTS A LOW OVER NORTHEAST ONTARIO WITH A COLD FRONT
DRAPED SOUTH THROUGH LOWER MICHIGAN INTO MIDDLE MISSISSIPPI RIVER
VALLEY. A LARGE HIGH IS OVER THE CENTRAL PLAINS AND ANOTHER IS OVER
SOUTHEAST SASKATCHEWAN. ANOTHER COLD FRONT STRETCHING ACROSS THE
SOUTHERN PLAINS ESSENTIALLY CUTS OFF GULF MOISTURE LIFTING NORTH
TOWARDS THE GREAT LAKES REGION. THE TROUGH OVER THE AREA IS
GENERATING A FEW THUNDERSTORMS OVER CENTRAL ONTARIO.
AS ONE SHORTWAVE PASSING THROUGH THE AREA EDGES INTO THE EASTERN
U.P...ANOTHER WILL SHIFT INTO WESTERN ONTARIO...JUST NORTHWEST OF
LAKE SUPERIOR. THE SURFACE LOW WILL ROTATE TO NEAR CNWZ. LAKE
BREEZES WILL CAUSE SOME LOW LEVEL CONVERGENCE OVER THE SOUTHERN
COUNTIES THIS AFTERNOON. 0-6KM BULK SHEARS STILL EXPECTED TO BE 10
TO 15 KTS. THIS IS SUPPORTED BY THE LATEST TAMDAR SOUNDINGS. ALSO
THE DEEP MOISTURE ANALYSIS FAVORS THE SOUTHERN COUNTIES THIS
AFTERNOON. SURFACE DEW POINTS ARE EXPECTED TO REMAIN IN THE UPPER
40S TO LOW 50S OVER THE AREA THIS AFTERNOON...WITH THE HIGH ALONG
THE LAKE MICHIGAN SHORE. THIS IN CONJUNCTION WITH THE AREA OF
STRONGER 850-500MB Q-V CONVERGENCE WILL HELP TO GENERATE A SCATTERED
SHOWERS AND THUNDERSTORMS OVER THE AREA MAINLY OVER THE SOUTHERN
U.P. A THETA-E RIDGE ANALYSIS...MUCAPE VALUES OF 500 TO 1000 J/KG
AND LI`S AROUND -2 CONDITIONS ALSO LOOK FAVORABLE FOR SCATTERED
SHOWERS AND THUNDERSTORMS OVER THE CENTRAL AND SOUTHERN U.P. ALSO
WEAKER MUCAPE VALUES AND POSITIVE LI`S ALONG THE WESTERN LAKE
SUPERIOR SHORE AS WELL AS COOL SURFACE TEMPERATURES OFF OF LAKE
SUPERIOR SUGGEST THAT THUNDERSTORMS ARE LESS FAVORABLE IN THOSE
AREAS. GUIDANCE AND LATEST OBSERVATIONS VERIFY THE CURRENT GRIDS
VERY WELL. THUS WILL CONTINUE TO CALL FOR HIGHS THIS AFTERNOON IN
THE LOW TO MID 70S ACROSS THE U.P. EXCEPT OVER THE KEWEENAW
PENINSULA AND ALONG THE NORTH SHORE WHERE TEMPERATURES WILL ONLY
REACH INTO THE 60S DUE TO LAKE BREEZES. THUS SEE NO REASON TO MAKE
ANY CHANGES TO THIS AFTERNOON`S FORECAST GRIDS AT THIS TIME.
&&
.LONG TERM (455 AM EDT)...
FOR TONIGHT/SUNDAY...THE SECOND SHORTWAVE REACHING THE U.P. DURING
THE MORNING HOURS WILL KEEP THE STRONGEST FORCING OUT OF SYNC WITH
THE PEAK DAYTIME HEATING HOURS...THUS MINIMIZING THE CHANCE OF ANY
SEVERE THUNDERSTORMS. INCREASED POPS TONIGHT OVER THE FAR WEST TO
ACCOUNT FOR THIS SHORTWAVE...THEN KEPT BEST CHANCE FOR SHOWERS AND
THUNDERSTORMS OVER THE SOUTH CENTRAL CWA ALONG THE WI BORDER AND
CONCENTRATED OVER MENOMINEE AND DICKINSON COUNTIES. FOR SUNDAY
AFTERNOON SOUTH CENTRAL...LIFTED INDEX VALUES WILL BE AROUND
-4C...WITH 700 J/KG BLYR COMPUTED CAPE AND 2000 J/KG SFC COMPUTED
CAPE. MIXED LAYER CAPE WILL BE AROUND 1000 J/KG. THIS AREA IS ALSO
WHERE THE HIGHER DEWPTS (MID 50S) CAN BE EXPECTED. AGAIN...THERE
WILL BE LESS THAN 10KT BULK SHEAR OVER WHOLE U.P...SO VERY LITTLE
CHANCE FOR HAIL IN THESE THUNDERSTORMS.
SUNDAY NIGHT...ADDED LOW CHC POPS FOR FAR EAST TO ACCOUNT FOR
LINGERING SHOWERS FROM THE SUNDAY SHORTWAVE AND THE NEAR-BY UPPER
LEVEL LOW SITTING OVER THE ONTARIO/QUEBEC BORDER. KEPT MONDAY DRY
SINCE WEAK HIGH PRES AND SUBSIDENCE WILL COVER THE REGION. MADE VERY
FEW CHANGES FOR THE REMAINDER OF THE FORECAST.
&&
.AVIATION (FOR THE 12Z TAF ISSUANCE)...
OVERALL...EXPECT VFR CONDITIONS THROUGH THE FORECAST PERIOD AT
KCMX/KSAW. EVEN SO...CHANCES OF SHOWERS...AND EVEN THUNDER...
REMAIN. UPPER LEVEL DISTURBANCE AND LAKE BREEZE CONVERGENCE FOCUSES
BEST CHANCE OF THUNDER AT KSAW THIS AFTN...AFT 18Z. DID DROP MENTION
OF THUNDER AFT 20Z THOUGH AS LAKE BREEZE/STABILIZATION SHOULD HAVE
PUSHED THROUGH BY THAT TIME. ANOTHER DISTURBANCE COMES THROUGH
THE U.P. LATE THIS AFTN INTO THE EVENING. COULDN`T RULE OUT A SHOWER
AT KCMX...BUT DUE TO STABILIZING WEST FLOW OFF LAKE SUPERIOR...THINK
CHANCES WILL BE BETTER INTO THE EVENING AT KSAW. YET ANOTHER UPPER
DISTURBANCE ARRIVES LATE IN THE TAF PERIOD...AFT 06Z SUNDAY. BEST
CHANCE FOR ANY SHOWERS WILL SWITCH TO KCMX AS WESTERN UPR MI IS
CLOSER TO THE DISTURBANCE.
&&
.MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)...
LIGHT WEST WINDS LAST FEW DAYS BRIEFLY TRANSITION TO SLIGHTLY
STRONGER NORTHERLY IN WAKE OF A SFC TROUGH SUN AFTN INTO SUN NIGHT.
SFC HIGH PASSING TO THE SOUTH OF LAKE SUPERIOR ON MONDAY ALLOWS
WINDS TO BECOME WEST AGAIN. THROUGH TUE...EXPECT WINDS TO STAY IN
THE 10-20 KNOT RANGE. STRONGER SOUTH WINDS...25-30 KNOTS...MAY OCCUR
LATE TUE INTO TUE NIGHT WITHIN TIGHT PRESSURE GRADIENT BTWN HIGH
PRESSURE SINKING ACROSS OHIO VALLEY AND LOW PRESSURE SHIFTING ACROSS
ONTARIO.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...DLG
LONG TERM...MRC
AVIATION...JLA
MARINE...JLA
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1056 AM CDT SAT JUN 21 2008
.DISCUSSION...
ACCAS THUNDERSTORMS CONTINUING THROUGHOUT THE MORNING OVER CENTRAL
SD AND SLOWLY WORKING INTO THE CWA. MOST OF THIS ACTIVITY APPEARS TO
BE DEVELOPING FROM ABOUT 700-750MB AND EXPECT THIS TREND TO
CONTINUE...BUT WE SHOULD SEE A BETTER CHANCE FOR THUNDERSTORM
DEVELOPMENT CLOSER TO 925-850MB WHERE BETTER INSTABILITY AND SOME
VERY WEAK CONVERGENCE EXISTS THIS AFTERNOON. CAPE VALUES AROUND 1000
J/KG LIKELY AND COULD APPROACH ABOUT 1500 J/KG IF TEMPS DO CLIMB
INTO THE MID AND UPPER 80S. IN FACT...SUX TAMDAR SOUNDING SHOWS THAT
THE LOWER 80S WILL CREATE A FAVORABLE ENVIRONMENT FOR THUNDERSTORMS
AND UPPER LEVELS ALSO SUPPORTIVE...SO EXPECT A REPEAT OF THE PAST
COUPLE OF DAYS. THE SFC DELTA THETA E NOT VERY IMPRESSIVE AT 10-15
SO EXPECT MAINLY A HAIL THREAT WITH THE FREEZING LEVEL FAIRLY LOW AT
AROUND 9500 FEET AGL.
&&
.AVIATION...
VFR TDA THRU SUN. ISOLATED TO SCATTERED -TSRA DVLPG ALG WEAK CDFNT
MOVG SWD OVR AREA...ESPECIALLY AFTER 18Z AND THRU ABOUT 03Z...WITH
ISOLD MVFR CX PSBL.
&&
.PREV DISCUSSION...
TROUGH OVER THE NORTHERN GREAT LAKES REGION RESULTING IN CONTINUED
NORTHWEST FLOW ALOFT. ATMOSPHERE IS EXPECTED TO DESTABILIZE
THROUGHOUT THE DAY TODAY...RESULTING IN WIDELY SCATTERED
THUNDERSTORMS THIS AFTERNOON AND THIS EVENING.
WITH WEST TO NORTHWEST FLOW NEAR THE SURFACE...LOW LEVEL MOISTURE IS
GOING TO BE SOMEWHAT HARD TO COME BY. STILL EXPECT DEW POINTS TO
RISE INTO THE UPPER 50S APPROACHING 60 DEGREES IN THE JAMES RIVER
VALLEY...WITH MOISTURE MUCH HARDER TO COME BY TO THE NORTH AND
EAST. WEAK SECONDARY COLD FRONT CURRENTLY ACROSS SOUTHERN CANADA
EXPECTED TO PIVOT DOWN INTO THE NORTHERN PLAINS AND AID IN
THUNDERSTORM DEVELOPMENT. IN ADDITION...MID LEVEL SHORTWAVE AND
ASSOCIATED JET MAX EXPECTED TO MOVE SOUTHWARD AS WELL...WITH THE
GREATEST FOCUS OF DYNAMICS ON SOUTHWEST MINNESOTA AND AREAS FURTHER
EAST. HOWEVER...WITH LIMITED AMOUNTS OF MOISTURE...HAVE KEPT POPS IN
THE 20-30 PERCENT RANGE WITH GREATER COVERAGE TO THE SOUTH. WITH
FREEZING LEVEL AROUND 8500 FEET (WHICH IS AROUND 500 FEET LOWER THAN
YESTERDAY)...EXPECT STRONGER STORMS TO BE CAPABLE OF PRODUCING
MARGINALLY SEVERE HAIL UP TO THE SIZE OF HALF DOLLARS.
EXPECT STORMS TO FALL APART SHORTLY AFTER SUNSET THIS EVENING. WINDS
WILL REMAIN RELATIVELY LIGHT AS HIGH PRESSURE BUILDS INTO THE
NORTHERN PLAINS. WITH A FAIRLY DRY AIRMASS...EXPECT SUNDAY TO BE A
DRY DAY WITH HIGHS IN THE UPPER 70S AND LOWER 80S. SUNDAY NIGHT
SHOULD BE A FAIRLY GOOD RADIATIONAL EVENING BEFORE WINDS TURN
SOUTHERLY AND LOW LEVEL MOISTURE INCREASES ACROSS THE REGION.
THE UPPER LEVEL FLOW BECOMES FAIRLY ZONAL EARLY NEXT WEEK WITH THE
CORE OF THE JET ACROSS SOUTHERN CANADA FOCUSING MUCH OF THE ACTIVITY
UP TO THE NORTH. MODELS HAVE BEEN SUGGESTING A FRONTAL PASSAGE
MIDWEEK...HOWEVER...WAVE REALLY FALLS APART AS IT WORKS TO THE EAST
AND APPEARS AS THOUGH THE FRONTAL BOUNDARY WILL GET HUNG UP TO THE
WEST OF THE FORECAST AREA. THIS WILL RESULT IN A PROLONGED PERIOD OF
SOUTHERLY FLOW...BUT STILL NOT EXPECTING DEW POINTS TO GET INTO THE
UPPER 60S OR LOWER 70S DUE TO THE DELAYED PLANTING SEASON RESULTING
IN LIMITED EVAPOTRANSPIRATION THUS FAR.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
BT/RSR
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