Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 04/07/13
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
911 PM MDT SAT APR 6 2013
.UPDATE...SCATTERED SHOWERS DEVELOPING IN THE MOUNTAINS THIS
EVENING WITH ISOLATED RAIN SHOWERS OVER THE URBAN CORRIDOR AND
NORTHEAST PLAINS. OVERALL CHANGES MINOR...WILL INCREASE POPS FM 10
TO 20 ACROSS THE LOWER ELEVATIONS.
&&
.AVIATION...GUSTY SE WINDS AT KDEN THE RESULT OF AN AREA OF LGT
RAIN SHOWERS TO THE SOUTH AND SOUTHEAST. WILL KEEP TEMPO G25 KTS
AT KDEN AND KAPA OVER THROUGH 04Z THEN DCRS IT TO LESS THAN 10
KTS. WILL ALSO HAVE VCSH IN THE TAF THE REMAINDER OF THE EVENING
AND OVERNIGHT.
&&
.PREV DISCUSSION... /ISSUED 317 PM MDT SAT APR 6 2013/
SHORT TERM...QG LIFT ASSOCIATED WITH UPPER TROUGH TO OUR WEST IS
JUST BEGINNING TO IMPINGE ON THE WESTERN SECTIONS OF THE CWA PER
THE LATEST RAP ANALYSES. THIS ASCENT WILL SPREAD OVER THE
REMAINDER OF THE CWA OVERNIGHT BRINGING A THREAT OF PRECIPITATION
TO ALL AREAS...THE HIGHEST IN THE MOUNTAINS. HOWEVER...SATELLITE
AND RADAR TRENDS ARE LESS THAN IMPRESSIVE WITH THIS SYSTEM AND
HAVE CUT BACK ON POPS/QPFS ACCORDINGLY. AS THE SYSTEM HEADS EAST
LATER TONIGHT SOME DESCENT SUBSIDENCE WILL COVER THE CWA FOR MUCH
OF SUNDAY`S DAYLIGHT HOURS. LATEST HIRES WINDOW RUNS SHOW ONLY
ISOLATED CONVECTIVE ACTIVITY EAST OF THE MOUNTAINS SUNDAY
AFTERNOON AND HAVE BACKED OFF POPS THERE DUE TO THIS. MOREOVER...
NOT EXPECTING MORE THAN SCATTERED CONVECTIVE ACTIVITY IN THE
MOUNTAINS SUNDAY AFTERNOON EITHER. MAXIMUM TEMPERATURES TOMORROW
LOOK TO BE CLOSE TO THOSE EXPERIENCED TODAY.
LONG TERM...SKIES WILL BE CLEARING SUNDAY NIGHT AS SUBSIDENCE
MOVES IN WITH NEAR NORMAL MINIMUM TEMPERATURES.
FOCUS TURNS TO MONDAY THROUGH TUESDAY AS AN EARLY SPRING STORM
AFFECTS THE STATE. MODELS IN MUCH BETTER AGREEMENT THAN THEY WERE
24 HOURS AGO...BUT STILL HAVE DIFFERENCES THAT MAY AFFECT HOW
MUCH SNOW WE SEE. HOWEVER...NO MATTER WHAT SOLUTION IS
FOLLOWED...HAVE HIGH CONFIDENCE IN GETTING PRECIPITATION AND GOOD
CONFIDENCE IN SIGNIFICANT SNOWFALL TOTALS.
WILL START MONDAY MORNING OUT DRY WITH INCREASING HIGH CLOUDS.
TEMPERATURES WILL AGAIN CLIMB INTO THE 60S FOR THE PLAINS AND NEAR
50 FOR THE MOUNTAINS. LATE MORNING INTO THE EARLY AFTERNOON...GOOD
INSTABILITY WILL ALLOW SHOWERS AND SOME THUNDERSTORMS BEGIN
FORMING. A RIDGE OF THETA E WILL BE SLIDING NORTH INTO EASTERN
COLORADO AND WESTERN KANSAS WITH CAPES IN THE 800-1200 J/KG RANGE.
GOOD SHEAR WILL COMBINE WITH THESE PARAMETERS TO BRING A CHANCE
OF STRONG THUNDERSTORMS OVER THE EASTERN PLAINS....MAINLY EAST OF
A LINE FROM STERLING TO LIMON. THE STORMS WILL HAVE THE POTENTIAL
TO PRODUCE LARGE HAIL AND PERHAPS A TORNADO...THOUGH RIGHT NOW
THIS LOOKS TO HAVE A BETTER CHANCE JUST EAST OF OUR FORECAST AREA.
MONDAY EVENING...THE STORMS 500 MB LOW CENTER WILL BE OVER THE
UT/AZ BORDER MOVING TOWARD THE FOUR CORNERS AREA...WITH THE
DEEPENING SURFACE LOW MOVING INTO SOUTHEASTERN COLORADO. THIS WILL
BEGIN TO DRAW IN THE COLD AIRMASS FROM THE NORTH. LOW LEVEL
MOISTURE FROM THE GULF THAT MOVED IN FROM THE SOUTH EARLIER IN THE
DAY WILL COMBINE WITH THE MID LEVEL MOISTURE FROM THE PACIFIC WITH
THIS SYSTEM AS THE STORM MOVES OVERHEAD MONDAY NIGHT.
PRECIPITATION WILL BEGIN OVER THE PLAINS AS RAIN...AND DEPENDING
ON HOW FAST THE COLD AIR MOVES IN...WILL DETERMINE WHEN THE RAIN
CHANGES OVER TO SNOW. FOR NOW...FOLLOWING MORE OF THE GFS AND
ECMWF SOLUTIONS FOR A QUICKER COOL DOWN COMPARED TO THE NAM. THE
NAM SOLUTION OVERALL SEEMS A LITTLE TOO FAR NORTH. SNOW...HEAVY AT
TIMES...IS EXPECTED TO SPREAD SOUTH OVER THE AREA MONDAY NIGHT
INTO EARLY TUESDAY MORNING. THE BEST UPSLOPE LOOKS TO OCCUR OVER
THE NORTHERN HALF OF THE FORECAST AREA...SO WILL EXPECT TO SEE THE
HIGHER AMOUNTS NORTH OF I-70...AND LIKELY EAST OF I-76. RIGHT
NOW...EXPECT A BROAD BRUSH 5-12 INCHES WITH SOME HIGHER AMOUNTS
POSSIBLE OVER THE NORTHERN FOOTHILLS AND URBAN CORRIDOR. HOWEVER
DOWN OVER SOUTHERN LINCOLN COUNTY AND IN THE HIGH MOUNTAIN
VALLEYS...WILL SEE 2-5 INCHES WHERE THERE WILL BE SLIGHT
DOWNSLOPING EFFECTS. THE HARD PART OF THE SNOW FORECAST IS THE
TEMPERATURES...AS THE WARM TEMPERATURES OF MONDAY WILL DEFINITELY
MELT THE INITIAL SNOW AND AREAS OVER THE EASTERN TO CENTRAL
EASTERN PLAINS MAY TAKE A LOT LONGER TO CHANGE OVER TO SNOW. IF WE
WERE IN THE DEAD OF WINTER...WE WOULD BE TALKING ABOUT ALMOST 2
FEET OF SNOW. BUT HERE WE ARE IN SPRING WITH WARMING GROUND
TEMPERATURES AND PRE-STORM AIR TEMPS IN THE 60S. THIS WILL PLAY
WITH THE SNOW- AMOUNT FORECAST COMPARED TO THE QPF.
TUESDAY...AS COLD AIR CONTINUES TO POUR IN...NORTH WINDS WILL BE
BLOWING AT 15 TO 25 MPH WITH GUSTS UP TO 35 MPH...WHICH WILL
PRODUCE BLOWING AND DRIFTING SNOW OVER THE PLAINS. AS THIS EVENT
GETS CLOSER...WILL HAVE TO SEE IF AND WHAT KIND OF A HIGHLIGHT
WILL BE NEEDED...AS THE WINDS COULD BE STRONG ENOUGH FOR A
BLIZZARD...DEPENDING ON HOW THE SYSTEM WRAPS UP.
SNOW SHOULD DIMINISH TUESDAY EVENING AS THE SYSTEM MOVES
NORTHEAST INTO NEBRASKA. AS SKIES CLEAR AND COLD AIR CONTINUES TO
MOVE IN IN NORTHERLY FLOW ALOFT...LOW TEMPERATURES TUESDAY NIGHT
WILL LIKELY BE IN THE SINGLE DIGITS TO TEENS AND HIGHS WEDNESDAY
WILL STRUGGLE TO GET MUCH ABOVE FREEZING. GFS IS STILL HANGING ON
TO ANOTHER WEAK DISTURBANCE MOVING THOUGH THURSDAY....HAVE KEPT
THE SLIGHT CHANCE POPS IN THE FORECAST. WILL BEGIN TO RETURN TO
NORMAL TEMPERATURES INTO THE WEEKEND WITH A GENERALLY DRY
PATTERN...EXCEPT FOR MOUNTAIN SHOWERS IN NORTHWEST FLOW ALOFT.
AVIATION...VFR CONDITIONS ARE EXPECTED AT AREA TERMINALS
OVERNIGHT AND TOMORROW. THERE STILL MAY BE PUSH OF WESTERLY WINDS
LATE THIS AFTERNOON AND EARLY EVENING WITH SPEEDS PERHAPS TOUCHING
25 KNOTS FOR A WHILE. DIURNAL WINDS EXPECTED OVERNIGHT WITH
WESTERLY COMPONENTS MOST OF SUNDAY. AS THE UPPER TROUGH MOVES
OVERHEAD TONIGHT AND EARLY SUNDAY THERE MAY BE SOME CEILINGS
AROUND 8000 FEET ALONG WITH ISOLATED SHOWERS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...COOPER
LONG TERM....KRIEDERMAN
AVIATION...COOPER
AREA FORECAST DISCUSSION
NWS PUEBLO CO
558 PM MDT SAT APR 6 2013
.UPDATE...
ISSUED AT 558 PM MDT SAT APR 6 2013
ADDED ISOLATED POPS TO SOUTHERN PORTIONS OF THE I-25 CORRIDOR WITH
CURRENT RADAR TRENDS INDICATING ECHOES ACROSS THE AREA...THOUGH
NOT SURE HOW MUCH IF ANY IS MAKING IT TO THE GROUND WITH DEW PT
DEPRESSIONS IN EXCESS OF 20 DEGREE. WILL CONTINUE TO MONITOR RADAR
TRENDS THROUGH THE EVENING WITH EMBEDDED SHORT WAVE ACROSS WESTERN
COLORADO TRANSLATING ACROSS THE STATE AND LATEST HRRR DATA
SPREADING A FEW SHOWERS ACROSS THE PIKES PEAK AND PALMER DVD
AROUND MIDNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 323 PM MDT SAT APR 6 2013
CURRENTLY...UPPER 60S TO NR 70 FOR THE PLAINS...AND 40S-50S FOR THE
MT AREAS. WINDS GENERALLY ARE WELL BEHAVED...BUT WILL SEE A FEW
ISOLD WIND GUSTS INT EH 30KT RANGE DUE TO VIRGA. UPSTREAM SHORTWAVE
TO OUR N IS EASILY SEEN IN IR IMAGERY ACROSS NRN UT AND ID. THIS
WILL CROSS OUR AREA FROM AROUND 03Z-09Z TONIGHT...SO EXPECT THIS TO
COINCIDE WITH HIGHEST POPS OVR THE MTS. BEST CHANCE FOR SHOWERS WILL
BE OVER THE CONTDVD N OF KMYP...WHERE THE HIGHER ELEVATIONS COULD
PICK UP ONE TO THREE INCHES OF SNOW THROUGH TOMORROW FROM SCT SHSN.
TOMORROW...WILL START OFF FAIRLY QUIET...THEN COULD SEE A FEW
SHOWERS DEVELOP ACROSS THE AREA AFTER ABOUT 21Z...IN RESPONSE TO
INCREASING UPPER LIFT FROM THE APPROACHING STORM SYSTEM NOW OVER
THE N PACIFIC. INCREASING LAPSE RATES WILL LEAD TO LIFTED INDICES IN
THE MINUS TWO RANGE IN THE AFTERNOON...WHICH COULD LEAD TO A FEW LTG
STRIKES ACROSS THE AREA. BELIEVE LTG WILL BE RATHER LIMITED...BUT
WILL LEAVE MENTION IN THE FORECAST FOR NOW TO PRESERVE CONTINUITY
AND COORDINATION WITH SURROUNDING WFOS. TEMPS SHOULD BE FAIRLY CLOSE
TO TODAY`S READINGS...MAYBE A COUPLE DEGREES HIGHER AS WRLY FLOW
INCREASES.
FIRE WX DANGER ALSO IS ON THE INCREASE TOMORROW DUE TO THE INCREASE
IN WINDS AND CONTINUED DRY CONDITIONS OVERALL. BEST BET FOR CRITICAL
FIRE WX WILL BE OVER THE SAN LUIS VALLEY...WHICH SHOULD SEE GUSTS IN
THE 25-35 KT RANGE IN THE AFTERNOON AND EARLY EVE. WILL HOIST THE
RED FLAG FOR THE VALLEY FOR THIS PERIOD. ALSO COULD SEE SOME
CRITICAL FIRE WX CONDITIONS ACROSS THE LOWER ARKANSAS FROM FREMONT
INTO NRN PUEBLO COUNTY...AND IN HUERFANO COUNTY DUE TO GAP FLOW
THROUGH LA VETA PASS. AT THIS TIME...LOOKS TOO LIMITED IN SCOPE TO
INCLUDE IN THE RED FLAG...BUT MAY HAVE TO BE ADDED BY LATER SHIFTS
IF IT APPEARS THAT WINDS WILL BE MORE WIDESPREAD.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 323 PM MDT SAT APR 6 2013
...POSSIBLE WEATHER TRIFECTA ACROSS SOUTHERN COLORADO MONDAY...
MONDAY HAS A LOT OF WEATHER HAZARD POTENTIAL...INCLUDING POSSIBLE
SEVERE WEATHER ON THE FAR EASTERN PLAINS...FIRE WEATHER OVER MOST
OF THE REST OF THE PLAINS AND WINTER WEATHER IN THE MOUNTAINS.
FIRST THE FIRE WEATHER. MONDAY AFTERNOON INTO EARLY EVENING DEFINITELY
LOOKS LIKE A HIGH FIRE DANGER PERIOD ACROSS MUCH OF THE SOUTHEAST
PLAINS...WITH WINDS...HUMIDITIES AND FUELS ALL MEETING CRITERIA.
WITH GUSTS TO 40 MPH...HUMIDITIES BELOW 15 PERCENT AND DRY FUELS...
THIS IS DAY WHEN OUTDOOR BURNING SHOULD BE SUSPENDED AND ANY OTHER
ACTIVITIES THAT MIGHT SPARK A FIRE SHOULD BE AVOIDED.
NOW THE SEVERE POTENTIAL. PARAMETERS ON BOTH MAJOR MODELS USED FOR THIS
TIME FRAME ARE INDICATING POSSIBLE SEVERE CONVECTION ACROSS THE FAR
EASTERN PLAINS MONDAY AFTERNOON AND EVENING. PARAMETERS INDICATE
TORNADO AS WELL AS LARGE HAIL POTENTIAL. THE THREAT AREA CURRENTLY
LOOKS EAST OF NORTH-SOUTH LINE THROUGH LA JUNTA. THUNDERSTORMS
POSSIBLE ELSEWHERE THIS DAY AS WELL BUT LIKELY NOT SEVERE.
NOW THE SNOW. IT WILL SPREAD INTO THE HIGH COUNTRY MONDAY AFTERNOON
AND START TO SPREAD ONTO THE ADJACENT PLAINS BY TUESDAY MORNING.
STILL BIG UNCERTAINTIES REGARDING THE STORM TRACK. CONTINUES TO
LOOK PRETTY CERTAIN FOR GOOD SNOW AND WIND POTENTIAL OVER THE
MOUNTAINS AND ALONG THE PALMER DIVIDE...WITH MORE IFFY POTENTIAL
ELSEWHERE. REGARDLESS OF THE MODEL...STILL LOOKS LIKE A PERIOD OF
AT LEAST SOME SNOW AND WIND FOR MOST OF SOUTHERN COLORADO...INCLUDING
THE HIGH MOUNTAIN VALLEYS AND THE SOUTHEAST PLAINS FROM LATE
MONDAY NIGHT INTO TUESDAY EVENING. AS WE GET CLOSER...WINTER
WEATHER HIGHLIGHTS WILL LIKELY BE NEEDED FOR THE MOUNTAINS AND
PALMER DIVIDE AND POSSIBLY ELSEWHERE. STORM SHOULD BE MOSTLY EAST
OF THE AREA BY WEDNESDAY EXCEPT FOR LINGERING WIND...COLD AND
MOUNTAIN SNOW SHOWERS. STAY TUNED. LW
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 323 PM MDT SAT APR 6 2013
VFR CONDITIONS WILL CONTINUE FOR THE TAF SITES THROUGH
TOMORROW. EXPECT SOME ISOLD-SCT SHOWERS PRIMARILY OVER THE MTS TONIGHT
AND THEN AGAIN SUN AFTERNOON. AN ISOLD TS IS ALSO POSSIBLE ACROSS THE
AREA LATE SUN AFTERNOON...WHICH COULD RESULT IN SOME LOCALIZED STRONG
WIND GUSTS.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
FIRE WEATHER WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING
FOR COZ228>233-235-237.
RED FLAG WARNING FROM 1 PM TO 9 PM MDT SUNDAY FOR COZ224.
&&
$$
UPDATE...MW
SHORT TERM...ROSE
LONG TERM...LW
AVIATION...ROSE
AREA FORECAST DISCUSSION
NWS TAUNTON MA
719 PM EDT SAT APR 6 2013
.SYNOPSIS...
HIGH PRESSURE BUILDS OVER NEW ENGLAND TONIGHT AND MOVES OFF TO THE
EAST ON SUNDAY. INCREASING SOUTH TO SOUTHWEST WIND WILL BRING
MILDER TEMPERATURES FOR THE FIRST PART OF THE WEEK. A COLD FRONT
MOVES THROUGH THE REGION TUESDAY. COOLER CONDITIONS WILL THEN MOVE
INTO THE REGION MIDWEEK...PRIOR TO ANOTHER STRONGER DISTURBANCE
FOR FRIDAY INTO SATURDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
730 PM UPDATE...
FIRE WEATHER HEADLINES HAVE BEEN ALLOWED TO EXPIRE AS WINDS
SUBSIDE ACROSS THE REGION. MINOR TWEAKS TO THE FORECAST WITH THE
LATEST NEAR-TERM RAP GUIDANCE AND 06.18Z NAM. TRENDS LOOK TO BE ON
TRACK. SOME MINOR CHANGES WERE MADE TO THE WIND AND WIND GUSTS FOR
SUNDAY...NOTHING MAJOR.
PREVIOUS DISCUSSION...
PRESSURE RISES ARE ENDING AS HIGH PRESSURE BUILDS OVER NEW
ENGLAND. THIS WILL ALLOW FOR MOSTLY CLEAR SKIES THROUGH MIDNIGHT
ALONG WITH WINDS BECOMING LIGHT. THIS PERIOD OF RADIATIONAL
COOLING COMBINED WITH LOW DEWPOINTS WILL ALLOW TEMPERATURES TO
DROP INTO THE 20S AWAY FROM THE COAST. THERE IS A SMALL POTENTIAL
FOR MIN TEMPS IN THE UPPER TEENS AROUND THE MONADNOCKS AND PARTS
OF NORTHWEST MASS.
MID AND HIGH CLOUDS OVER THE GREAT LAKES MARK THE LEADING EDGE OF
WARMER AIR MOVING UP THE TRAILING SIDE OF THE HIGH. PER SATELLITE
LOOPS...THESE CLOUDS EXTRAPOLATE TO WESTERN NEW ENGLAND AROUND 05Z
AND ACROSS THE REMAINDER OF OUR AREA BY MORNING. IF THEY THICKEN
FAST ENOUGH...IT MAY KEEP TEMPS FROM COOLING TO THEIR FULL
POTENTIAL.
GIVEN THE DRYNESS OF THE AIR...ANY SHOWERS FROM THE WARM
ADVECTION ALOFT WOULD QUICKLY TURN TO VIRGA.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
SUNDAY...
HIGH PRESSURE OFFSHORE AND LOW PRESSURE APPROACHING FROM THE UPPER
MIDWEST. THIS WILL BRING FALLING PRESSURE...VALUES OF 1-2 MB/HOUR
ARE CURRENTLY OBSERVED OVER THE GREAT LAKES. THIS WILL BRING
INCREASING SOUTH AND SOUTHWEST WINDS. THE STRONGEST WINDS ALOFT
DON/T REACH SOUTHERN NEW ENGLAND UNTIL LATE AFTERNOON. BUFKIT AND
AWIPS SOUNDINGS SHOW 40 KNOTS ALOFT AT THAT TIME...BUT ONLY 30-35
KNOTS OF WIND REACHING THE SURFACE. WE ARE NOT CONSIDERING ANY
WIND HEADLINES AT THIS TIME...BUT WILL BE MONITORING. THE BEST
CHANCE WOULD BE IN THE WORCESTER HILLS AND EAST SLOPES OF THE
BERKSHIRES IN AREAS AT OR ABOVE 2000 FEET MSL.
TEMPS IN THE MIXED LAYER AT 925 MB REACH 2-5C...WHICH WOULD
SUPPORT MAX TEMPS IN THE 50S.
SUNDAY NIGHT...
AN APPROACHING COLD FRONT MOVES THROUGH THE REGION OVERNIGHT. THE
GFS TIMING SEEMED A TAD FAST...BUT THE OTHER MODELS ALSO DEPICTED
A SUNDAY OVERNIGHT/EARLY MONDAY PASSAGE. WITH A WEST-EAST UPPER
FLOW AND LIMITED MOISTURE...NOT A LOT OF SUPPORT FOR PCPN. BUT ALL
MODELS SHOW A LITTLE PCPN DURING THIS TIME. SO WE HAVE POPS FROM
SLIGHT CHANCE TO LOW-END CHANCE DURING THE NIGHT.
GUSTY SOUTHWEST WINDS LINGER THE FIRST PART OF THE NIGHT BUT THEN
DIMINISH AS THE FRONT MOVES THROUGH.
TEMPS ARE A BLEND OF MOS.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
HEADLINES...
* COLD FRONT WITH SHOWERS FOR TUESDAY INTO TUESDAY NIGHT
* WET WEATHER REMAINING SOUTH OF NEW ENGLAND FOR MIDWEEK
* STRONGER DISTURBANCE FOR FRIDAY INTO SATURDAY
*/OVERVIEW AND MODEL CONSENSUS...
EXCUSING NAO/AO TELECONNECTIONS WITH THEIR WIDESPREAD VARIABILITY
THOUGH POSITIVE TREND...OF NOTE IN THE LATEST CPC CLIMATE BRIEFING
WERE ROSSBY WAVES INDICATING ANOMALOUS CONVERGENCE AT H2 ACROSS
NORTH AMERICA. WHILE BROAD...THIS DOES SUGGEST WEAKER POLAR VORTEX
INFLUENCE OVER CANADA AND A MILDER TREND ACROSS THE MID-LATITUDES.
IT WOULD SEEM THE ECMWF/ECENS LEANS IN THIS DIRECTION WITH GREATER
INFLUENCE OF HIGH PRESSURE. BUT OF NOTE IS HOW OUT OF PHASE IT IS
WITH THE 06.12Z GFS/GEFS/CANADIAN BY TUESDAY...WHICH SUPPORT A QUASI-
STATIONARY POLAR VORTEX OVER THE SOUTHERN HUDSON BAY REGION OVER THE
PROGRESSIVE ECMWF. AS NOTED BY PREVIOUS FORECASTERS...FAVORABILITY IS
GIVEN TO THE TUESDAY NIGHT FRONTAL BOUNDARY REMAINING SOUTH WITH
CONFLUENT FLOW OVER NEW ENGLAND RATHER THAN ANOMALOUS RIDGING. IT
IS MORE IN-LINE WITH WHAT WOULD BE EXPECTED CLIMATOLOGICALLY FOR
THIS TIME OF YEAR.
WITH THE WPC /WEATHER PREDICTION CENTER/ NOTING THE INCONSISTENT GFS
AND GEFS MEAN IN COMPARISON TO THE ECMWF/ECENS...HAVE GONE WITH A
BLEND OF NON-GFS DETERMINISTIC GUIDANCE OUT TO 12Z TUESDAY. FROM
THEN ON...SUPPORT THE 06.0Z ECMWF WITH HPC/WPC GUIDANCE.
*/DAY-TO-DAY DETAILS...
*/MONDAY AND MONDAY NIGHT...
DRIVING S/SW FLOW SHOULD MAKE FOR A MILD DAY AHEAD OF THE
APPROACHING COLD FRONTAL BOUNDARY. ANTICIPATING A FEW GUSTS DURING
THE DAY WITH A WELL-MIXED BOUNDARY LAYER. WILL KEEP INCREASING
CLOUDS TOWARDS THE LATTER HALF OF MONDAY...WITH RAIN CHANCES LATE
INTO MONDAY NIGHT /06.12Z NAM ESPECIALLY LATE/.
*/TUESDAY AND TUESDAY NIGHT...
COLD FRONT SWEEPS THROUGH THE REGION AND OFFSHORE INTO THE EVENING
PERIOD. GUSTY SOUTHWEST WINDS AHEAD WITH WINDS BACKED OUT OF THE
NORTHWEST AND POTENTIALLY GUSTING IN WAKE OF THE COLD FRONT
/ESPECIALLY CLOSER TO THE SHORES/. VERY FLAT PATTERN THROUGH THE MID-
LEVELS WITH LITTLE EVIDENCE OF STRONG LIFT...SCATTERED SHOWERS...
LESS INTO WEDNESDAY MORNING. MAY NOT GET TOO MILD DURING THE DAY
TUESDAY AS CLOUDS AND SHOWERS COULD PUT A HAMPER ON MIXING-DOWN
SIGNIFICANT MID-LEVEL WARMING AT H85 /AROUND +8C BY 18Z TUESDAY/.
*/WEDNESDAY INTO THURSDAY...
IN GOING WITH THE ECMWF...THE COLD FRONT SHOULD BECOME STATIONARY
SOUTH OF NEW ENGLAND. ADDITIONAL DISTURBANCES ALONG THE FRONT WILL
MAKE FOR CLOUDY AND WET WEATHER...ESPECIALLY ACROSS THE SOUTHERN
TIER OF NEW ENGLAND. OTHERWISE...INFLUENTIAL HIGH PRESSURE FROM THE
SOUTHERN HUDSON BAY REGION WILL KEEP CONDITIONS DRY AND COOLER WITH
PREVAILING NORTHERLY FLOW.
*/FRIDAY INTO SATURDAY...
INSIDE-RUNNER WITH A POSSIBLE TRIPLE POINT LOW ACROSS SOUTHEAST NEW
ENGLAND WILL MAKE FOR A WET PERIOD. MILD CONDITIONS ANTICIPATED
ALONG AND AHEAD WITH GUSTY SOUTHERLY FLOW. COLDER AND DRIER AIR WITH
GUSTY WESTERLY WINDS EXPECTED LATE SATURDAY INTO SATURDAY NIGHT WITH
HIGH PRESSURE BUILDING BACK OVER THE REGION FOR THE REMAINDER OF THE
WEEKEND.
&&
.AVIATION /23Z SATURDAY THROUGH THURSDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW...HIGH CONFIDENCE THROUGH SUNDAY. MODERATE TO HIGH
CONFIDENCE SUNDAY NIGHT.
TONIGHT...VFR. MID TO HIGH CLOUDS MOVE IN FROM W-E.
SUNDAY...VFR. MID CLOUDS THICKENING AND LOWERING 6-9 KFT. GUSTY SW
WINDS 25-30 KTS BY 22Z.
SUNDAY NIGHT...VFR. CLOUD BASES 4-6 KFT WITH SCT -RA ALONG A WEAK
COLD FRONT. SW WINDS BECOMING W/NW. LOW CONFIDENCE MVFR.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK...MONDAY THROUGH WEDNESDAY...
MONDAY INTO MONDAY NIGHT...MODERATE CONFIDENCE.
VFR. CLOUDS WITH SHOWERS LATE WILL MAKE FOR MVFR CONDITIONS.
TUESDAY INTO TUESDAY NIGHT...MODERATE CONFIDENCE.
MVFR. CLOUDS AND SHOWERS. GUSTY SW WINDS AHEAD OF A COLD FRONT
SWEEPING DURING THE DAY...OFFSHORE OVERNIGHT. GUSTY NW WINDS TO THE
REAR. RETURNING VFR.
WEDNESDAY...MODERATE CONFIDENCE.
VFR. MVFR POSSIBLE ALONG THE SOUTH-SHORE OF NEW ENGLAND.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
HIGH CONFIDENCE THROUGH SUNDAY NIGHT.
THIS EVENING...
HIGH PRESSURE BUILDS OVER THE WATERS BRINGING DIMINISHING WIND.
SEAS OF 5 FEET HAVE LINGERED OVER THE OUTER WATERS AND SO THE
SMALL CRAFT ADVISORY REMAINS FOR A LITTLE WHILE LONGER.
TONIGHT...
HIGH PRESSURE OVER THE WATERS. EXPECT WINDS AND SEAS WILL BE BELOW
SMALL CRAFT LEVELS.
SUNDAY AND SUNDAY NIGHT...
HIGH PRESSURE MOVES OFFSHORE. STRONG PRESSURE FALLS NOTED OVER
THE GREAT LAKES WITH SOUTH WINDS GUSTING TO 30 KNOTS IN PARTS OF
THE MIDWEST. MODELS SHOW WINDS OF 30-35 KNOTS MOVING OVER THE
WATERS DURING THE DAY AND 40 KNOTS TOWARD EVENING. THE COOL OCEAN
WATER MAY STABILIZE THE LOWEST LEVELS FROM GETTING THE FULL
WIND...BUT SPEEDS OVER 25 KNOTS ARE REASONABLE AND A FEW GUSTS
NEAR GALE FORCE ARE POSSIBLE.
A COLD FRONT MOVES TO THE COASTLINE BY DAYBREAK MONDAY. EXPECT
SOUTHWEST WINDS AHEAD OF THE FRONT...DIMINISHING LATE AT NIGHT.
OUTLOOK...MONDAY THROUGH WEDNESDAY...
MONDAY INTO MONDAY NIGHT...MODERATE CONFIDENCE.
GUSTY SW WINDS AHEAD OF AN APPROACHING COLD FRONT WILL REMAIN BELOW
25 KTS BUT KEEP SEAS ABOVE 5 FT FOR THE OUTER WATERS.
TUESDAY INTO TUESDAY NIGHT...MODERATE CONFIDENCE.
COLD FRONT SWEEPS ACROSS THE WATERS TUESDAY NIGHT. GUSTY SW WINDS
BELOW 25 KTS AHEAD...TURNING NW TO THE REAR GUSTING BELOW 25 KTS.
SEAS ABOVE 5 FT ON THE OUTER WATERS. ATTENDANT SHOWERS BUT NO
VISIBILITY RESTRICTIONS.
WEDNESDAY...MODERATE CONFIDENCE.
FRONT STALLS SOUTH OF THE WATERS. WINDS AND SEAS TO REMAIN BELOW
SMALL CRAFT ADVISORY LEVELS. SHOWERS POSSIBLE ACROSS THE SOUTHERN
WATERS. NO VISIBILITY RESTRICTIONS.
&&
.FIRE WEATHER...
SUNDAY...
THE DRIEST OF THE AIR IS EXPECTED TO MOVE OFF ON SUNDAY. DEWPOINTS
WILL INCREASE THROUGH THE DAY WITH VALUES REACHING THE 20S DURING
THE AFTERNOON. EVEN SO...WARMER AIR MOVING IN WILL ALLOW FOR
WARMER HIGH TEMPERATURES DURING THE AFTERNOON. THE COMBINATION OF
TEMPERATURES IN THE 50S AND DEWPOINTS IN THE 20S STILL BRINGS
MINIMUM RELATIVE HUMIDITY VALUES IN THE 20S NORTH OF THE MASS PIKE
AND UPPER 20S TO LOWER 30S TO THE SOUTH. SOUTH WINDS WILL INCREASE
DURING THE AFTERNOON WITH POTENTIAL FOR GUSTS OF 30-35 MPH...
POSSIBLY A LITTLE STRONGER. A CLOUDIER DAY MAY HOLD BACK THE
HEATING...THIS WILL NEED TO BE MONITORED.
AFTER SPEAKING WITH OUR FIRE WEATHER CONTACTS...WE HAVE DECIDED TO
ISSUE A SPECIAL WEATHER STATEMENT HIGHLIGHTED THE ELEVATED FIRE
WEATHER POTENTIAL. IF A WARNING IS NEEDED...IT WILL BE ISSUED
SUNDAY MORNING.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 11 AM SUNDAY TO 6 AM EDT MONDAY FOR
ANZ231>235-237-251.
SMALL CRAFT ADVISORY FROM 11 AM SUNDAY TO 4 AM EDT MONDAY FOR
ANZ230-236.
SMALL CRAFT ADVISORY UNTIL 6 AM EDT MONDAY FOR ANZ250-254>256.
&&
$$
SYNOPSIS...WTB/SIPPRELL
NEAR TERM...WTB/SIPPRELL
SHORT TERM...WTB
LONG TERM...SIPPRELL
AVIATION...WTB/SIPPRELL
MARINE...WTB/SIPPRELL
FIRE WEATHER...WTB
AREA FORECAST DISCUSSION...UPDATED
NWS TAMPA BAY RUSKIN FL
924 PM EDT SAT APR 6 2013
.UPDATE...THE WEST COAST SEA BREEZE WENT INLAND SLIGHTLY FURTHER
THAN ANTICIPATED BY THE MODELS SOUTH OF TAMPA BAY...BUT THE ERLY
SURGE WILL TURN WINDS BACK AROUND FOR ALL AREAS IN NEXT HOUR OR
TWO. OTHERWISE CURRENT FORECAST IS ON TRACK. ONLY REAL QUESTION
IS HOW MUCH MIGHT THE ATL STRATUS HOLD TOGETHER BUT WILL CONTINUE
THINKING THAT WILL WILL MOSTLY DISSIPATE ACROSS WRN HALF OF THE
PENINSULA. TEMPS WILL REACH THE 50S ACROSS ALL BUT IMMEDIATE
COASTAL AREAS AND THEN A WARM DAY INTO THE 80S AREA WIDE TOMORROW.
NO UPDATES ARE NEEDED TO GRIDS OR TEXT PRODUCTS.
&&
.AVIATION...MOSTLY VFR CONDITIONS WILL CONTINUE THROUGH THE NEXT
24 HOURS. SCT LOW CLOUDS AND MAYBE SOME PATCHY FOG COULD LEAD TO
BRIEF PERIODS OF MVFR OVERNIGHT...WITH CONDITIONS CLEARING AFTER
SUNRISE. NORTHEAST FLOW WILL VEER TO MORE EASTERLY OVERNIGHT...
WITH A SEABREEZE TURNING WINDS ONSHORE NEAR THE COAST SUNDAY
AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 240 PM EDT SAT APR 6 2013/
SYNOPSIS...
18Z WATER VAPOR AND H4 RAP ANALYSIS SHOW THE IMPRESSIVE APRIL TROUGH
RESPONSIBLE FOR THE RAIN AND COLD FRONT ON FRIDAY CONTINUES TO PULL
EAST OF THE FL PENINSULA. ASSOCIATED COOL POOL ALOFT IS ALSO
QUICKLY TRANSLATING EASTWARD. BEHIND THIS TROUGH...HEIGHT FIELDS ARE
REBOUNDING RAPIDLY RESULTING IN MID/UPPER LEVEL RIDGING OVERHEAD BY
THIS EVENING. AT THE SURFACE...FORECAST AREA RESIDES ON THE SOUTHERN
PERIPHERY OF A LARGE RIDGE EXTENDING DOWN THE EASTERN SEABOARD.
TEMPERATURES ARE CLIMBING THROUGH THE 70S UNDER A MIX OF SUN AND A
SCT-BKN CUMULUS FIELD. THIS CU FIELD IS FORCED BY THE DIURNAL
HEATING INTERACTING WITH A SHALLOW MOIST LAYER BELOW 825MB...AND
SHOULD GENERALLY DISSIPATE AS WE HEAD TOWARD MID/LATE EVENING.
SHORT TERM (TONIGHT THROUGH MONDAY NIGHT)...
NOT MUCH IN THE WAY OF SENSIBLE WEATHER ON THE WAY THROUGH THE EARLY
PORTION OF THE FORECAST PERIOD...WITH NO SIGNIFICANT WEATHER
POTENTIAL UNTIL NEAR THE END OF THE WEEK.
TONIGHT/SUNDAY/SUNDAY NIGHT...
WEAK MID/UPPER RIDGE WILL PASS OVER AND EAST OF THE REGION BY SUNDAY
MORNING WITH A MORE ZONAL FLOW DEVELOPING ALONG THE NORTHERN GULF
COAST AND FL PENINSULA IN IT WAKE. AT THE SURFACE...THE REGION WILL
REMAIN ON THE SOUTHERN SIDE OF A RIDGE AXIS EXTENDING DOWN/JUST OFF
THE EASTERN CONUS SEABOARD. DRY CONDITIONS WILL BE THE RULE WITH
LITTLE TO NO SYNOPTIC FORCING OR AVAILABLE MOISTURE KEEPING POPS
NEAR ZERO FOR THE REST OF THE WEEKEND. LOW TEMPERATURES BY LATE
TONIGHT WILL BE SEASONABLY COOL WITH MANY INLAND LOCATIONS DROPPING
INTO THE 50S...AND THE IMMEDIATE COAST FROM PINELLAS COUNTY
SOUTHWARD HOLDING IN THE 60S.
SUNDAY WILL FEATURE OF MIX OF SUN AND CLOUDS WITH ANOTHER LATE
MORNING/AFTERNOON EXPANDING CU FIELD. EFFICIENT MIXING UP TO AROUND
850-825MB WHERE TEMPS WILL BE AROUND 10-12C SHOULD ALLOW MANY
LOCATIONS AWAY FROM THE BEACHES TO APPROACH 80 OR EVEN CLIMB INTO
THE LOWER 80S SOUTH OF I-4. THE IMMEDIATE COAST MAY END UP SEVERAL
DEGREES COOLER WHERE FEEBLE AFTERNOON SEA-BREEZE CIRCULATIONS WILL
TURN WINDS ONSHORE FOR PART OF THE PEAK HEATING PERIOD.
SUNDAY NIGHT WILL FEATURE MOSTLY CLEAR SKIES AND TEMPERATURES A FEW
DEGREES COOLER THAN TONIGHT. MAINLY LOOKING FOR LOWS DROPPING INTO
THE UPPER 50S TO LOWER 60S BY SUNRISE...WITH SOME MIDDLE 50S FOR THE
NORMALLY COLDER SPOTS ALONG THE NATURE COAST.
MONDAY-TUESDAY...
THE WARMING TREND CONTINUES INTO THE EARLY PORTION OF THE WEEK.
TEMPERATURES WILL QUICKLY RISE BACK ABOVE NORMAL FOR MANY
SPOTS...ESPECIALLY BY TUESDAY. GFS/ECMWF SHOW ZONAL FLOW AGAIN
BECOMING WEAKLY RIDGED IN THE MID/UPPER LEVELS WHILE THE SURFACE
RIDGE AXIS SINKS EVER SO SLOWLY SOUTHWARD TOWARD THE GA/SC COAST.
EFFICIENT MIXING...STRONG APRIL SUN...AND A WARMING LOW LEVEL COLUMN
(850MB TEMPS 12-14C) WILL ALLOW MANY LOCATIONS AWAY FROM THE COAST
TO MIX OUT INTO THE LOWER 80...AND EVEN SO MIDDLE 80S SOUTH OF TAMPA
MONDAY AFTERNOON. MANY SPOTS ARE FORECAST TO REACH THE MIDDLE 80S
AWAY FROM THE BEACHES FOR TUESDAY AFTERNOON. ENJOY THE PLEASANT
APRIL WEATHER!
LONG TERM (TUESDAY THROUGH NEXT SATURDAY)...
MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT THROUGH WEDNESDAY OR
WEDNESDAY NIGHT...WITH SOLUTIONS THEN DIVERGING SIGNIFICANTLY WITH
RESPECT TO THE NEXT COLD FRONT LATE NEXT WEEK AND INTO THE UPCOMING
WEEKEND. THE 00Z CANADIAN AND 00Z ECMWF SOLUTIONS SHOW A MUCH LESS
PROGRESSIVE PATTERN...WITH THE 00Z GFS AND 00Z UKMET SOLUTIONS MUCH
MORE AGGRESSIVE MOVING THE NEXT COLD FRONT INTO THE FORECAST AREA AS
EARLY AS THURSDAY NIGHT. WILL TAKE A BLENDED FORECAST APPROACH FOR
NOW AS BOTH SOLUTIONS SEEM TO HAVE SOME MERIT GIVEN THE SPREAD IN
THE GFS ENSEMBLE SUITE. OVERALL...WILL KEEP THE FORECAST RAIN FREE
THROUGH TUESDAY NIGHT...WITH SLIGHT CHANCE LOW CHANCE POPS IN THE
FORECAST EACH DAY WEDNESDAY THROUGH SATURDAY FOR PRIMARILY
AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS. TEMPERATURES ARE
EXPECTED TO RUN ABOVE NORMAL THROUGH FRIDAY BEFORE SETTLING BACK
CLOSER TO SEASONAL LEVELS NEXT WEEKEND.
AVIATION...
VFR CONDITIONS WITH OCNL BKN VFR CIGS. LIMITED LATE NIGHT BR
POSSIBLE AT LAL/PGD/RSW. NE OR NORTH WINDS AND GUST AT TIMES
DIMINISH OVER NIGHT AND BECOME NE AND EAST.
MARINE...
THE REGION WILL REMAIN ON THE SOUTHERN SIDE OF A RIDGE AXIS ALONG
THE EASTERN SEABOARD THROUGH THE EARLY PORTION OF NEXT WEEK. THIS
POSITION WITH RESPECT TO THE RIDGE WILL PROVIDE A GENERAL EAST TO
SOUTHEAST FLOW REGIME ACROSS THE EASTERN GULF OF MEXICO...OUTSIDE
OF LOCAL ONSHORE FLOW DURING THE AFTERNOON ASSOCIATED WITH ANY
SEA-BREEZE CIRCULATIONS.
FIRE WEATHER...
NO SIGNIFICANT FIRE WEATHER CONCERNS ARE ANTICIPATED OVER THE NEXT
COUPLE OF DAYS. RELATIVE HUMIDITY VALUES AWAY FROM THE COAST ARE
FORECAST TO BRIEFLY APPROACH 35 PERCENT BOTH SUNDAY AND MONDAY
DURING THE AFTERNOON...HOWEVER NO CRITICAL DURATIONS OF LOW RELATIVE
HUMIDITY ARE EXPECTED AND RED FLAG CONDITIONS APPEAR UNLIKELY.
INCREASING LOW LEVEL MOISTURE FOR THE MIDDLE PORTION OF THE WEEK
SHOULD PREVENT CRITICAL LEVELS OF RELATIVE HUMIDITY FOR ALL ZONES.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 61 78 63 83 / 10 0 10 0
FMY 61 82 63 85 / 10 10 0 0
GIF 59 82 61 85 / 10 10 0 10
SRQ 60 80 61 82 / 10 10 0 0
BKV 52 82 55 84 / 10 10 10 10
SPG 64 79 66 83 / 10 10 0 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SHORT TERM/MARINE/FIRE WEATHER...88/GITTINGER
LONG TERM/AVIATION...18/FLEMING
AREA FORECAST DISCUSSION
NWS MIAMI FL
134 PM EDT FRI APR 5 2013
.AVIATION...
MOSTLY VFR CONDITIONS WITH BKN-OVC100 AND OCCASIONAL BKN035 WITH A
PASSING SHRA. SOME LIGHT RAIN IS ALSO POSSIBLE UNTIL EARLY EVENING
WHEN CLOUDS MOVE OUT TO THE EAST OF THE PENINSULA. SURFACE WIND
HAS BEEN WEAKER THAN EARLIER THINKING DUE TO RAIN COOLED AIRMASS
ALONG WITH OVERCAST MID TO HIGH CLOUDS. COULD HAVE SOME GUSTS OVER
12KT WITH SW FLOW THEN VEERING TO THE NW BEHIND THE COLD FRONT
BECOMING NNE AFT 12-13Z SATURDAY.
KOB
&&
.PREV DISCUSSION... /ISSUED 953 AM EDT FRI APR 5 2013/
UPDATE...
CURRENT WAVE OF PRECIPITATION THIS MORNING ACROSS LAKE OKEECHOBEE
TO SOUTHWEST FLORIDA, THEN DOWN INTO THE SE GULF OF MEXICO MAKING
STEADY EASTWARD PROGRESS AHEAD OF THE POWERFUL SHORTWAVE TROUGH OVER
THE EASTERN GULF OF MEXICO. ATMOSPHERE HAS STABILIZED IN THE LOW
LEVELS IN THE WAKE OF THE OVERNIGHT AND EARLY MORNING CONVECTION,
WHICH IS ACTING TO LIMIT THE INTENSITY OF THE ACTIVITY CURRENTLY
MOVING OVER THE AREA. SOUTHERLY FLOW TRYING TO DESTABILIZE THE
LOW LEVELS THIS MORNING, BUT OVERCAST CLOUD SHIELD WILL MITIGATE
ANY SIGNIFICANT WARMING AND SPC HAS APPROPRIATELY DOWNPLAYED THE
SEVERE THREAT ACROSS SOUTH FLORIDA TODAY.
FORECAST UPDATE HAS NUMEROUS SHOWERS AND ISOLATED TSTMS,
GRADUALLY TAPERING OFF FROM NW TO SE AS THE COLD FRONT CURRENTLY
APPROACHING THE TAMPA BAY REGION MOVES INTO THE AREA THIS
AFTERNOON. LOWERED TEMPERATURES A FEW DEGREES DUE TO COOLER
READINGS THIS MORNING AND EXTENSIVE CLOUD COVER.
INTERESTING TIDBIT: A "WAKE LOW" FEATURE WAS NOTED EARLY THIS
MORNING OVER PARTS OF SOUTH FLORIDA WHICH HELPED TO PRODUCE NON-
THUNDERSTORM WIND GUSTS OF 35 TO 45 MPH IN THE NAPLES AREA AS WELL
AS LAKE OKEECHOBEE AND PARTS OF THE PALM BEACHES. THIS IS THE SAME
TYPE OF FEATURE WHICH PRODUCED THE STRONG WINDS IN THE MOBILE AREA
BACK ON WEDNESDAY, AND THIS HAS BEEN NOTED IN PAST SPRINGTIME
CONVECTION EVENTS OVER SOUTH FLORIDA AND OTHER PARTS OF THE
SOUTHERN UNITED STATES. /MOLLEDA
PREV DISCUSSION... /ISSUED 831 AM EDT FRI APR 5 2013/
AVIATION...
A BAND OF LIGHT RAIN WILL MOVE ACROSS SOUTH FLORIDA INTO EARLY
THIS AFTERNOON WITH SOME MVFR CIGS/VISIBILITIES BUT MOSTLY VFR. IT
IS POSSIBLE DEPENDING ON ANY BREAKS IN THE CLOUD COVER THAT A FEW
THUNDERSTORMS COULD ALSO DEVELOP BY EARLY THIS AFTERNOON AHEAD OF
THE FRONT. THESE CONDITIONS WILL DIMINISH THIS AFTERNOON AS THE
COLD FRONT CLEARS THE PENINSULA. SURFACE WIND WILL BE SSW TO SW
INCREASING IN SPEEDS AND OCCASIONALLY GUSTING OVER 20KT AFT 13-14Z
SHIFTING TO THE NORTHWEST BEHIND THE FRONT.
KOB
PREV DISCUSSION... /ISSUED 343 AM EDT FRI APR 5 2013/
DISCUSSION...
AN MCS WAS MOVING ACROSS THE EASTERN GULF AND SOUTH FLORIDA EARLY
THIS MORNING. AN UPPER LEVEL LOW WAS MOVING EAST ACROSS
ALABAMA...WITH BROAD SURFACE LOW PRESSURE AREAS FROM NORTHERN
FLORIDA NORTHWARD TO OFF THE COAST OF NORTH CAROLINA. GLOBAL
MODELS ARE NOT HANDLING THE CURRENT SITUATION WELL...SO FOLLOWED
CLOSER TO THE HRRR OUTPUT THROUGH THE AFTERNOON.
THE ATMOSPHERE OVER SOUTH FLORIDA IS EXPECTED TO BECOME WORKED
OVER FROM THIS MCS...WITH MUCH MORE STABLE CONDITIONS. CLOUD
COVER WILL BLANKET THE REGION FOR MUCH OF THE DAY. SO THE SEVERE
THREAT APPEARS TO HAVE DIMINISHED...WITH THE LAST STRONG STORMS
ACROSS THE FAR SOUTHEASTERN PORTIONS OF MIAMI DADE COUNTY EARLY
THIS MORNING. SO LIGHT/MODERATE RAIN WITH A FEW EMBEDDED
THUNDERSTORMS ARE ALL THAT IS EXPECTED THROUGH THE MID/LATE
AFTERNOON...BEFORE THE COLD FRONT PUSHES THROUGH THE REGION.
UNDERCUT MAV/MET TEMPERATURES AT MOST LOCATIONS TODAY DUE TO THE
EXPECTED CLOUD COVER AND RAIN.
A FEW LINGERING SHOWERS ARE POSSIBLE INTO THE EARLY EVENING.
OTHERWISE...DRIER AND COOLER CONDITIONS ARE EXPECTED OVER SOUTH
FLORIDA TONIGHT. THE WEEKEND LOOKS LIKE IT WILL BE A PLEASANT
ONE WITH TEMPERATURES NEAR NORMAL FOR EARLY APRIL. A LIGHT TO
MODERATE NORTHEASTERLY FLOW WILL PREVAIL ON SATURDAY...WITH WINDS
SHIFTING TO THE EAST ON SUNDAY AS HIGH PRESSURE MOVES INTO THE
WESTERN ATLANTIC OFF THE EASTERN CONUS.
HIGH PRESSURE WILL REMAIN OVER THE WESTERN ATLANTIC THROUGH THE
MIDDLE OF THE WEEK...WITH LOW LEVEL MOISTURE RETURNING TO THE
REGION. HIGHS WILL REMAIN IN THE LOW 80S EAST TO THE MID TO UPPER
80S TOWARD THE GULF COAST. OVERNIGHT LOW TEMPERATURES WILL
INCREASE TO THE LOWER 70S FOR THE EAST COAST METRO AREAS. A FEW
STREAMER SHOWERS WILL BE POSSIBLE EACH DAY FROM TUESDAY THROUGH
THE END OF THE WEEK.
AVIATION...06Z TAFS.
MATURE MCS MOVING ACROSS THE EASTERN GULF AND
ACROSS SOUTH FLORIDA EARLY THIS MORNING. STRONG TO SEVERE STORMS
ARE POSSIBLE AT KFXE SOUTHWARD ON THE EAST COAST OVER THE NEXT FEW
HOURS. PREVAILING MVFR CONDITIONS ARE EXPECTED FOR MOST OF THE
EAST COAST TAF SITES THROUGH THE OVERNIGHT HOURS...WITH IFR
CONDITIONS POSSIBLE IN THUNDERSTORMS. KAPF IS IN THE RAIN SHIELD
ON THE NORTH SIDE OF THE MCS...AND LIGHT/MODERATE RAIN WITH A FEW
HIGH BASED LIGHTNING STRIKES WILL CONTINUE THROUGH THE MORNING
HOURS. LIGHT/MODERATE RAIN IS EXPECTED AFTER 10-12Z ACROSS THE
REGION AS THE MCS MOVES THROUGH AND SOUTH FLORIDA GETS WORKED
OVER. AT THIS TIME IS IT DIFFICULT TO SAY WHETHER THERE WILL BE
ANY REGENERATION OF THUNDERSTORMS BY THE AFTERNOON HOURS DUE TO
ALL THE CLOUD COVER. BASED OFF OF LATEST GUIDANCE...WILL ONLY SHOW
RAIN AFTER 12-14Z...WITH CONDITIONS IMPROVING BY MID/LATE
AFTERNOON. THE FRONT IS EXPECTED TO PASS THROUGH THE REGION
18-21Z...WITH LIGHT/MODERATE NORTHWESTERLY FLOW THROUGH THE END OF
THE TAF PERIOD.
MARINE...
LATEST GUIDANCE INDICATES THAT WINDS ACROSS THE LOCAL GULF AND
ATLANTIC WATERS COULD REACH AROUND 20 KNOTS THIS MORNING AND SEAS
ACROSS THE OFF SHORE GULF WATERS COULD REACH NEAR 7 FEET. A SMALL
CRAFT ADVISORY IS IN EFFECT THROUGH 00Z THIS EVENING FOR ALL OF
THE LOCAL WATERS. A COLD FRONT WILL MOVE THROUGH THE REGION LATE
THIS AFTERNOON...WITH WINDS SHIFTING TO THE NORTHWEST BEHIND THE
FRONT. NORTHEAST WINDS 15-20 KNOTS ARE EXPECTED ON SATURDAY...WITH
EASTERLY WINDS 10-15 KNOTS ON SUNDAY. EAST TO SOUTHEAST WINDS ARE
THEN EXPECTED THROUGH THE WEEK AS HIGH PRESSURE BUILDS ACROSS THE
WESTERN ATLANTIC.
FIRE WEATHER...
MUCH NEEDED RAINFALL WILL CONTINUE TO FALL ACROSS MUCH OF THE
REGION THROUGH THE DAY TODAY. A FEW EMBEDDED THUNDERSTORMS ARE
POSSIBLE INTO THE AFTERNOON. A COLD FRONT WILL MOVE THROUGH THE
REGION LATE THIS AFTERNOON INTO THIS EVENING...WITH DRIER AND
COOLER CONDITIONS EXPECTED TONIGHT. MINIMUM RELATIVE HUMIDITY
VALUES AND SATURDAY ARE EXPECTED TO REMAIN JUST ABOVE CRITICAL
VALUES ACROSS THE INTERIOR WEST. HIGH PRESSURE WILL THEN BUILD
ACROSS THE WESTERN ATLANTIC SUNDAY THROUGH THE MIDDLE OF THE
WEEK...WITH LOW LEVEL MOISTURE RETURNING TO SOUTH FLORIDA.
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR BISCAYNE
BAY-COASTAL WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL
OUT 20 NM-COASTAL WATERS FROM JUPITER INLET TO DEERFIELD
BEACH, FL OUT 20 NM-LAKE OKEECHOBEE-WATERS FROM DEERFIELD
BEACH TO OCEAN REEF, FL EXTENDING FROM 20 NM TO THE
TERRITORIAL WATERS OF THE BAHAMAS-WATERS FROM JUPITER INLET
TO DEERFIELD BEACH, FL EXTENDING FROM 20 NM TO 60 NM.
GM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR COASTAL
WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM-
COASTAL WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT
20 NM-GULF WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL
EXTENDING FROM 20 TO 60 NM.
&&
$$
AREA FORECAST DISCUSSION
NWS MIAMI FL
953 AM EDT FRI APR 5 2013
.UPDATE...
CURRENT WAVE OF PRECIPITATION THIS MORNING ACROSS LAKE OKEECHOBEE
TO SOUTHWEST FLORIDA, THEN DOWN INTO THE SE GULF OF MEXICO MAKING
STEADY EASTWARD PROGRESS AHEAD OF THE POWERFUL SHORTWAVE TROUGH OVER
THE EASTERN GULF OF MEXICO. ATMOSPHERE HAS STABILIZED IN THE LOW
LEVELS IN THE WAKE OF THE OVERNIGHT AND EARLY MORNING CONVECTION,
WHICH IS ACTING TO LIMIT THE INTENSITY OF THE ACTIVITY CURRENTLY
MOVING OVER THE AREA. SOUTHERLY FLOW TRYING TO DESTABILIZE THE
LOW LEVELS THIS MORNING, BUT OVERCAST CLOUD SHIELD WILL MITIGATE
ANY SIGNIFICANT WARMING AND SPC HAS APPROPRIATELY DOWNPLAYED THE
SEVERE THREAT ACROSS SOUTH FLORIDA TODAY.
FORECAST UPDATE HAS NUMEROUS SHOWERS AND ISOLATED TSTMS,
GRADUALLY TAPERING OFF FROM NW TO SE AS THE COLD FRONT CURRENTLY
APPROACHING THE TAMPA BAY REGION MOVES INTO THE AREA THIS
AFTERNOON. LOWERED TEMPERATURES A FEW DEGREES DUE TO COOLER
READINGS THIS MORNING AND EXTENSIVE CLOUD COVER.
INTERESTING TIDBIT: A "WAKE LOW" FEATURE WAS NOTED EARLY THIS
MORNING OVER PARTS OF SOUTH FLORIDA WHICH HELPED TO PRODUCE NON-
THUNDERSTORM WIND GUSTS OF 35 TO 45 MPH IN THE NAPLES AREA AS WELL
AS LAKE OKEECHOBEE AND PARTS OF THE PALM BEACHES. THIS IS THE SAME
TYPE OF FEATURE WHICH PRODUCED THE STRONG WINDS IN THE MOBILE AREA
BACK ON WEDNESDAY, AND THIS HAS BEEN NOTED IN PAST SPRINGTIME
CONVECTION EVENTS OVER SOUTH FLORIDA AND OTHER PARTS OF THE
SOUTHERN UNITED STATES. /MOLLEDA
&&
.PREV DISCUSSION... /ISSUED 831 AM EDT FRI APR 5 2013/
AVIATION...
A BAND OF LIGHT RAIN WILL MOVE ACROSS SOUTH FLORIDA INTO EARLY
THIS AFTERNOON WITH SOME MVFR CIGS/VISIBILITIES BUT MOSTLY VFR. IT
IS POSSIBLE DEPENDING ON ANY BREAKS IN THE CLOUD COVER THAT A FEW
THUNDERSTORMS COULD ALSO DEVELOP BY EARLY THIS AFTERNOON AHEAD OF
THE FRONT. THESE CONDITIONS WILL DIMINISH THIS AFTERNOON AS THE
COLD FRONT CLEARS THE PENINSULA. SURFACE WIND WILL BE SSW TO SW
INCREASING IN SPEEDS AND OCCASIONALLY GUSTING OVER 20KT AFT 13-14Z
SHIFTING TO THE NORTHWEST BEHIND THE FRONT.
KOB
PREV DISCUSSION... /ISSUED 343 AM EDT FRI APR 5 2013/
DISCUSSION...
AN MCS WAS MOVING ACROSS THE EASTERN GULF AND SOUTH FLORIDA EARLY
THIS MORNING. AN UPPER LEVEL LOW WAS MOVING EAST ACROSS
ALABAMA...WITH BROAD SURFACE LOW PRESSURE AREAS FROM NORTHERN
FLORIDA NORTHWARD TO OFF THE COAST OF NORTH CAROLINA. GLOBAL
MODELS ARE NOT HANDLING THE CURRENT SITUATION WELL...SO FOLLOWED
CLOSER TO THE HRRR OUTPUT THROUGH THE AFTERNOON.
THE ATMOSPHERE OVER SOUTH FLORIDA IS EXPECTED TO BECOME WORKED
OVER FROM THIS MCS...WITH MUCH MORE STABLE CONDITIONS. CLOUD
COVER WILL BLANKET THE REGION FOR MUCH OF THE DAY. SO THE SEVERE
THREAT APPEARS TO HAVE DIMINISHED...WITH THE LAST STRONG STORMS
ACROSS THE FAR SOUTHEASTERN PORTIONS OF MIAMI DADE COUNTY EARLY
THIS MORNING. SO LIGHT/MODERATE RAIN WITH A FEW EMBEDDED
THUNDERSTORMS ARE ALL THAT IS EXPECTED THROUGH THE MID/LATE
AFTERNOON...BEFORE THE COLD FRONT PUSHES THROUGH THE REGION.
UNDERCUT MAV/MET TEMPERATURES AT MOST LOCATIONS TODAY DUE TO THE
EXPECTED CLOUD COVER AND RAIN.
A FEW LINGERING SHOWERS ARE POSSIBLE INTO THE EARLY EVENING.
OTHERWISE...DRIER AND COOLER CONDITIONS ARE EXPECTED OVER SOUTH
FLORIDA TONIGHT. THE WEEKEND LOOKS LIKE IT WILL BE A PLEASANT
ONE WITH TEMPERATURES NEAR NORMAL FOR EARLY APRIL. A LIGHT TO
MODERATE NORTHEASTERLY FLOW WILL PREVAIL ON SATURDAY...WITH WINDS
SHIFTING TO THE EAST ON SUNDAY AS HIGH PRESSURE MOVES INTO THE
WESTERN ATLANTIC OFF THE EASTERN CONUS.
HIGH PRESSURE WILL REMAIN OVER THE WESTERN ATLANTIC THROUGH THE
MIDDLE OF THE WEEK...WITH LOW LEVEL MOISTURE RETURNING TO THE
REGION. HIGHS WILL REMAIN IN THE LOW 80S EAST TO THE MID TO UPPER
80S TOWARD THE GULF COAST. OVERNIGHT LOW TEMPERATURES WILL
INCREASE TO THE LOWER 70S FOR THE EAST COAST METRO AREAS. A FEW
STREAMER SHOWERS WILL BE POSSIBLE EACH DAY FROM TUESDAY THROUGH
THE END OF THE WEEK.
AVIATION...06Z TAFS.
MATURE MCS MOVING ACROSS THE EASTERN GULF AND
ACROSS SOUTH FLORIDA EARLY THIS MORNING. STRONG TO SEVERE STORMS
ARE POSSIBLE AT KFXE SOUTHWARD ON THE EAST COAST OVER THE NEXT FEW
HOURS. PREVAILING MVFR CONDITIONS ARE EXPECTED FOR MOST OF THE
EAST COAST TAF SITES THROUGH THE OVERNIGHT HOURS...WITH IFR
CONDITIONS POSSIBLE IN THUNDERSTORMS. KAPF IS IN THE RAIN SHIELD
ON THE NORTH SIDE OF THE MCS...AND LIGHT/MODERATE RAIN WITH A FEW
HIGH BASED LIGHTNING STRIKES WILL CONTINUE THROUGH THE MORNING
HOURS. LIGHT/MODERATE RAIN IS EXPECTED AFTER 10-12Z ACROSS THE
REGION AS THE MCS MOVES THROUGH AND SOUTH FLORIDA GETS WORKED
OVER. AT THIS TIME IS IT DIFFICULT TO SAY WHETHER THERE WILL BE
ANY REGENERATION OF THUNDERSTORMS BY THE AFTERNOON HOURS DUE TO
ALL THE CLOUD COVER. BASED OFF OF LATEST GUIDANCE...WILL ONLY SHOW
RAIN AFTER 12-14Z...WITH CONDITIONS IMPROVING BY MID/LATE
AFTERNOON. THE FRONT IS EXPECTED TO PASS THROUGH THE REGION
18-21Z...WITH LIGHT/MODERATE NORTHWESTERLY FLOW THROUGH THE END OF
THE TAF PERIOD.
MARINE...
LATEST GUIDANCE INDICATES THAT WINDS ACROSS THE LOCAL GULF AND
ATLANTIC WATERS COULD REACH AROUND 20 KNOTS THIS MORNING AND SEAS
ACROSS THE OFF SHORE GULF WATERS COULD REACH NEAR 7 FEET. A SMALL
CRAFT ADVISORY IS IN EFFECT THROUGH 00Z THIS EVENING FOR ALL OF
THE LOCAL WATERS. A COLD FRONT WILL MOVE THROUGH THE REGION LATE
THIS AFTERNOON...WITH WINDS SHIFTING TO THE NORTHWEST BEHIND THE
FRONT. NORTHEAST WINDS 15-20 KNOTS ARE EXPECTED ON SATURDAY...WITH
EASTERLY WINDS 10-15 KNOTS ON SUNDAY. EAST TO SOUTHEAST WINDS ARE
THEN EXPECTED THROUGH THE WEEK AS HIGH PRESSURE BUILDS ACROSS THE
WESTERN ATLANTIC.
FIRE WEATHER...
MUCH NEEDED RAINFALL WILL CONTINUE TO FALL ACROSS MUCH OF THE
REGION THROUGH THE DAY TODAY. A FEW EMBEDDED THUNDERSTORMS ARE
POSSIBLE INTO THE AFTERNOON. A COLD FRONT WILL MOVE THROUGH THE
REGION LATE THIS AFTERNOON INTO THIS EVENING...WITH DRIER AND
COOLER CONDITIONS EXPECTED TONIGHT. MINIMUM RELATIVE HUMIDITY
VALUES AND SATURDAY ARE EXPECTED TO REMAIN JUST ABOVE CRITICAL
VALUES ACROSS THE INTERIOR WEST. HIGH PRESSURE WILL THEN BUILD
ACROSS THE WESTERN ATLANTIC SUNDAY THROUGH THE MIDDLE OF THE
WEEK...WITH LOW LEVEL MOISTURE RETURNING TO SOUTH FLORIDA.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 77 61 77 67 / 70 10 0 -
FORT LAUDERDALE 78 65 79 69 / 70 10 0 -
MIAMI 77 64 79 68 / 70 20 0 -
NAPLES 73 58 81 62 / 70 10 0 -
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR BISCAYNE
BAY-COASTAL WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL
OUT 20 NM-COASTAL WATERS FROM JUPITER INLET TO DEERFIELD
BEACH, FL OUT 20 NM-LAKE OKEECHOBEE-WATERS FROM DEERFIELD
BEACH TO OCEAN REEF, FL EXTENDING FROM 20 NM TO THE
TERRITORIAL WATERS OF THE BAHAMAS-WATERS FROM JUPITER INLET
TO DEERFIELD BEACH, FL EXTENDING FROM 20 NM TO 60 NM.
GM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR COASTAL
WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM-
COASTAL WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT
20 NM-GULF WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL
EXTENDING FROM 20 TO 60 NM.
&&
$$
PUBLIC/MARINE...59/MOLLEDA
AVIATION/RADAR/FIRE...30/KOB
AREA FORECAST DISCUSSION
NWS MIAMI FL
831 AM EDT FRI APR 5 2013
.AVIATION...
A BAND OF LIGHT RAIN WILL MOVE ACROSS SOUTH FLORIDA INTO EARLY
THIS AFTERNOON WITH SOME MVFR CIGS/VISIBILITIES BUT MOSTLY VFR. IT
IS POSSIBLE DEPENDING ON ANY BREAKS IN THE CLOUD COVER THAT A FEW
THUNDERSTORMS COULD ALSO DEVELOP BY EARLY THIS AFTERNOON AHEAD OF
THE FRONT. THESE CONDITIONS WILL DIMINISH THIS AFTERNOON AS THE
COLD FRONT CLEARS THE PENINSULA. SURFACE WIND WILL BE SSW TO SW
INCREASING IN SPEEDS AND OCCASIONALLY GUSTING OVER 20KT AFT 13-14Z
SHIFTING TO THE NORTHWEST BEHIND THE FRONT.
KOB
&&
.PREV DISCUSSION... /ISSUED 343 AM EDT FRI APR 5 2013/
DISCUSSION...
AN MCS WAS MOVING ACROSS THE EASTERN GULF AND SOUTH FLORIDA EARLY
THIS MORNING. AN UPPER LEVEL LOW WAS MOVING EAST ACROSS
ALABAMA...WITH BROAD SURFACE LOW PRESSURE AREAS FROM NORTHERN
FLORIDA NORTHWARD TO OFF THE COAST OF NORTH CAROLINA. GLOBAL
MODELS ARE NOT HANDLING THE CURRENT SITUATION WELL...SO FOLLOWED
CLOSER TO THE HRRR OUTPUT THROUGH THE AFTERNOON.
THE ATMOSPHERE OVER SOUTH FLORIDA IS EXPECTED TO BECOME WORKED
OVER FROM THIS MCS...WITH MUCH MORE STABLE CONDITIONS. CLOUD
COVER WILL BLANKET THE REGION FOR MUCH OF THE DAY. SO THE SEVERE
THREAT APPEARS TO HAVE DIMINISHED...WITH THE LAST STRONG STORMS
ACROSS THE FAR SOUTHEASTERN PORTIONS OF MIAMI DADE COUNTY EARLY
THIS MORNING. SO LIGHT/MODERATE RAIN WITH A FEW EMBEDDED
THUNDERSTORMS ARE ALL THAT IS EXPECTED THROUGH THE MID/LATE
AFTERNOON...BEFORE THE COLD FRONT PUSHES THROUGH THE REGION.
UNDERCUT MAV/MET TEMPERATURES AT MOST LOCATIONS TODAY DUE TO THE
EXPECTED CLOUD COVER AND RAIN.
A FEW LINGERING SHOWERS ARE POSSIBLE INTO THE EARLY EVENING.
OTHERWISE...DRIER AND COOLER CONDITIONS ARE EXPECTED OVER SOUTH
FLORIDA TONIGHT. THE WEEKEND LOOKS LIKE IT WILL BE A PLEASANT
ONE WITH TEMPERATURES NEAR NORMAL FOR EARLY APRIL. A LIGHT TO
MODERATE NORTHEASTERLY FLOW WILL PREVAIL ON SATURDAY...WITH WINDS
SHIFTING TO THE EAST ON SUNDAY AS HIGH PRESSURE MOVES INTO THE
WESTERN ATLANTIC OFF THE EASTERN CONUS.
HIGH PRESSURE WILL REMAIN OVER THE WESTERN ATLANTIC THROUGH THE
MIDDLE OF THE WEEK...WITH LOW LEVEL MOISTURE RETURNING TO THE
REGION. HIGHS WILL REMAIN IN THE LOW 80S EAST TO THE MID TO UPPER
80S TOWARD THE GULF COAST. OVERNIGHT LOW TEMPERATURES WILL
INCREASE TO THE LOWER 70S FOR THE EAST COAST METRO AREAS. A FEW
STREAMER SHOWERS WILL BE POSSIBLE EACH DAY FROM TUESDAY THROUGH
THE END OF THE WEEK.
AVIATION...06Z TAFS.
MATURE MCS MOVING ACROSS THE EASTERN GULF AND
ACROSS SOUTH FLORIDA EARLY THIS MORNING. STRONG TO SEVERE STORMS
ARE POSSIBLE AT KFXE SOUTHWARD ON THE EAST COAST OVER THE NEXT FEW
HOURS. PREVAILING MVFR CONDITIONS ARE EXPECTED FOR MOST OF THE
EAST COAST TAF SITES THROUGH THE OVERNIGHT HOURS...WITH IFR
CONDITIONS POSSIBLE IN THUNDERSTORMS. KAPF IS IN THE RAIN SHIELD
ON THE NORTH SIDE OF THE MCS...AND LIGHT/MODERATE RAIN WITH A FEW
HIGH BASED LIGHTNING STRIKES WILL CONTINUE THROUGH THE MORNING
HOURS. LIGHT/MODERATE RAIN IS EXPECTED AFTER 10-12Z ACROSS THE
REGION AS THE MCS MOVES THROUGH AND SOUTH FLORIDA GETS WORKED
OVER. AT THIS TIME IS IT DIFFICULT TO SAY WHETHER THERE WILL BE
ANY REGENERATION OF THUNDERSTORMS BY THE AFTERNOON HOURS DUE TO
ALL THE CLOUD COVER. BASED OFF OF LATEST GUIDANCE...WILL ONLY SHOW
RAIN AFTER 12-14Z...WITH CONDITIONS IMPROVING BY MID/LATE
AFTERNOON. THE FRONT IS EXPECTED TO PASS THROUGH THE REGION
18-21Z...WITH LIGHT/MODERATE NORTHWESTERLY FLOW THROUGH THE END OF
THE TAF PERIOD.
MARINE...
LATEST GUIDANCE INDICATES THAT WINDS ACROSS THE LOCAL GULF AND
ATLANTIC WATERS COULD REACH AROUND 20 KNOTS THIS MORNING AND SEAS
ACROSS THE OFF SHORE GULF WATERS COULD REACH NEAR 7 FEET. A SMALL
CRAFT ADVISORY IS IN EFFECT THROUGH 00Z THIS EVENING FOR ALL OF
THE LOCAL WATERS. A COLD FRONT WILL MOVE THROUGH THE REGION LATE
THIS AFTERNOON...WITH WINDS SHIFTING TO THE NORTHWEST BEHIND THE
FRONT. NORTHEAST WINDS 15-20 KNOTS ARE EXPECTED ON SATURDAY...WITH
EASTERLY WINDS 10-15 KNOTS ON SUNDAY. EAST TO SOUTHEAST WINDS ARE
THEN EXPECTED THROUGH THE WEEK AS HIGH PRESSURE BUILDS ACROSS THE
WESTERN ATLANTIC.
FIRE WEATHER...
MUCH NEEDED RAINFALL WILL CONTINUE TO FALL ACROSS MUCH OF THE
REGION THROUGH THE DAY TODAY. A FEW EMBEDDED THUNDERSTORMS ARE
POSSIBLE INTO THE AFTERNOON. A COLD FRONT WILL MOVE THROUGH THE
REGION LATE THIS AFTERNOON INTO THIS EVENING...WITH DRIER AND
COOLER CONDITIONS EXPECTED TONIGHT. MINIMUM RELATIVE HUMIDITY
VALUES AND SATURDAY ARE EXPECTED TO REMAIN JUST ABOVE CRITICAL
VALUES ACROSS THE INTERIOR WEST. HIGH PRESSURE WILL THEN BUILD
ACROSS THE WESTERN ATLANTIC SUNDAY THROUGH THE MIDDLE OF THE
WEEK...WITH LOW LEVEL MOISTURE RETURNING TO SOUTH FLORIDA.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 79 61 77 67 / 60 10 0 -
FORT LAUDERDALE 78 65 79 69 / 70 10 0 -
MIAMI 78 64 79 68 / 70 20 0 -
NAPLES 75 58 81 62 / 50 10 0 -
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR BISCAYNE
BAY-COASTAL WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL
OUT 20 NM-COASTAL WATERS FROM JUPITER INLET TO DEERFIELD
BEACH, FL OUT 20 NM-LAKE OKEECHOBEE-WATERS FROM DEERFIELD
BEACH TO OCEAN REEF, FL EXTENDING FROM 20 NM TO THE
TERRITORIAL WATERS OF THE BAHAMAS-WATERS FROM JUPITER INLET
TO DEERFIELD BEACH, FL EXTENDING FROM 20 NM TO 60 NM.
GM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR COASTAL
WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM-
COASTAL WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT
20 NM-GULF WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL
EXTENDING FROM 20 TO 60 NM.
&&
$$
AREA FORECAST DISCUSSION
NWS MIAMI FL
343 AM EDT FRI APR 5 2013
.DISCUSSION...
AN MCS WAS MOVING ACROSS THE EASTERN GULF AND SOUTH FLORIDA EARLY
THIS MORNING. AN UPPER LEVEL LOW WAS MOVING EAST ACROSS
ALABAMA...WITH BROAD SURFACE LOW PRESSURE AREAS FROM NORTHERN
FLORIDA NORTHWARD TO OFF THE COAST OF NORTH CAROLINA. GLOBAL
MODELS ARE NOT HANDLING THE CURRENT SITUATION WELL...SO FOLLOWED
CLOSER TO THE HRRR OUTPUT THROUGH THE AFTERNOON.
THE ATMOSPHERE OVER SOUTH FLORIDA IS EXPECTED TO BECOME WORKED
OVER FROM THIS MCS...WITH MUCH MORE STABLE CONDITIONS. CLOUD
COVER WILL BLANKET THE REGION FOR MUCH OF THE DAY. SO THE SEVERE
THREAT APPEARS TO HAVE DIMINISHED...WITH THE LAST STRONG STORMS
ACROSS THE FAR SOUTHEASTERN PORTIONS OF MIAMI DADE COUNTY EARLY
THIS MORNING. SO LIGHT/MODERATE RAIN WITH A FEW EMBEDDED
THUNDERSTORMS ARE ALL THAT IS EXPECTED THROUGH THE MID/LATE
AFTERNOON...BEFORE THE COLD FRONT PUSHES THROUGH THE REGION.
UNDERCUT MAV/MET TEMPERATURES AT MOST LOCATIONS TODAY DUE TO THE
EXPECTED CLOUD COVER AND RAIN.
A FEW LINGERING SHOWERS ARE POSSIBLE INTO THE EARLY EVENING.
OTHERWISE...DRIER AND COOLER CONDITIONS ARE EXPECTED OVER SOUTH
FLORIDA TONIGHT. THE WEEKEND LOOKS LIKE IT WILL BE A PLEASANT
ONE WITH TEMPERATURES NEAR NORMAL FOR EARLY APRIL. A LIGHT TO
MODERATE NORTHEASTERLY FLOW WILL PREVAIL ON SATURDAY...WITH WINDS
SHIFTING TO THE EAST ON SUNDAY AS HIGH PRESSURE MOVES INTO THE
WESTERN ATLANTIC OFF THE EASTERN CONUS.
HIGH PRESSURE WILL REMAIN OVER THE WESTERN ATLANTIC THROUGH THE
MIDDLE OF THE WEEK...WITH LOW LEVEL MOISTURE RETURNING TO THE
REGION. HIGHS WILL REMAIN IN THE LOW 80S EAST TO THE MID TO UPPER
80S TOWARD THE GULF COAST. OVERNIGHT LOW TEMPERATURES WILL
INCREASE TO THE LOWER 70S FOR THE EAST COAST METRO AREAS. A FEW
STREAMER SHOWERS WILL BE POSSIBLE EACH DAY FROM TUESDAY THROUGH
THE END OF THE WEEK.
&&
.AVIATION...06Z TAFS.
MATURE MCS MOVING ACROSS THE EASTERN GULF AND
ACROSS SOUTH FLORIDA EARLY THIS MORNING. STRONG TO SEVERE STORMS
ARE POSSIBLE AT KFXE SOUTHWARD ON THE EAST COAST OVER THE NEXT FEW
HOURS. PREVAILING MVFR CONDITIONS ARE EXPECTED FOR MOST OF THE
EAST COAST TAF SITES THROUGH THE OVERNIGHT HOURS...WITH IFR
CONDITIONS POSSIBLE IN THUNDERSTORMS. KAPF IS IN THE RAIN SHIELD
ON THE NORTH SIDE OF THE MCS...AND LIGHT/MODERATE RAIN WITH A FEW
HIGH BASED LIGHTNING STRIKES WILL CONTINUE THROUGH THE MORNING
HOURS. LIGHT/MODERATE RAIN IS EXPECTED AFTER 10-12Z ACROSS THE
REGION AS THE MCS MOVES THROUGH AND SOUTH FLORIDA GETS WORKED
OVER. AT THIS TIME IS IT DIFFICULT TO SAY WHETHER THERE WILL BE
ANY REGENERATION OF THUNDERSTORMS BY THE AFTERNOON HOURS DUE TO
ALL THE CLOUD COVER. BASED OFF OF LATEST GUIDANCE...WILL ONLY SHOW
RAIN AFTER 12-14Z...WITH CONDITIONS IMPROVING BY MID/LATE
AFTERNOON. THE FRONT IS EXPECTED TO PASS THROUGH THE REGION
18-21Z...WITH LIGHT/MODERATE NORTHWESTERLY FLOW THROUGH THE END OF
THE TAF PERIOD.
&&
.MARINE...
LATEST GUIDANCE INDICATES THAT WINDS ACROSS THE LOCAL GULF AND
ATLANTIC WATERS COULD REACH AROUND 20 KNOTS THIS MORNING AND SEAS
ACROSS THE OFF SHORE GULF WATERS COULD REACH NEAR 7 FEET. A SMALL
CRAFT ADVISORY IS IN EFFECT THROUGH 00Z THIS EVENING FOR ALL OF
THE LOCAL WATERS. A COLD FRONT WILL MOVE THROUGH THE REGION LATE
THIS AFTERNOON...WITH WINDS SHIFTING TO THE NORTHWEST BEHIND THE
FRONT. NORTHEAST WINDS 15-20 KNOTS ARE EXPECTED ON SATURDAY...WITH
EASTERLY WINDS 10-15 KNOTS ON SUNDAY. EAST TO SOUTHEAST WINDS ARE
THEN EXPECTED THROUGH THE WEEK AS HIGH PRESSURE BUILDS ACROSS THE
WESTERN ATLANTIC.
&&
.FIRE WEATHER...
MUCH NEEDED RAINFALL WILL CONTINUE TO FALL ACROSS MUCH OF THE
REGION THROUGH THE DAY TODAY. A FEW EMBEDDED THUNDERSTORMS ARE
POSSIBLE INTO THE AFTERNOON. A COLD FRONT WILL MOVE THROUGH THE
REGION LATE THIS AFTERNOON INTO THIS EVENING...WITH DRIER AND
COOLER CONDITIONS EXPECTED TONIGHT. MINIMUM RELATIVE HUMIDITY
VALUES AND SATURDAY ARE EXPECTED TO REMAIN JUST ABOVE CRITICAL
VALUES ACROSS THE INTERIOR WEST. HIGH PRESSURE WILL THEN BUILD
ACROSS THE WESTERN ATLANTIC SUNDAY THROUGH THE MIDDLE OF THE
WEEK...WITH LOW LEVEL MOISTURE RETURNING TO SOUTH FLORIDA.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 79 61 77 67 / 60 10 0 -
FORT LAUDERDALE 78 65 79 69 / 70 10 0 -
MIAMI 78 64 79 68 / 70 20 0 -
NAPLES 75 58 81 62 / 50 10 0 -
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR BISCAYNE
BAY-COASTAL WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL
OUT 20 NM-COASTAL WATERS FROM JUPITER INLET TO DEERFIELD
BEACH, FL OUT 20 NM-LAKE OKEECHOBEE-WATERS FROM DEERFIELD
BEACH TO OCEAN REEF, FL EXTENDING FROM 20 NM TO THE
TERRITORIAL WATERS OF THE BAHAMAS-WATERS FROM JUPITER INLET
TO DEERFIELD BEACH, FL EXTENDING FROM 20 NM TO 60 NM.
GM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR COASTAL
WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM-
COASTAL WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT
20 NM-GULF WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL
EXTENDING FROM 20 TO 60 NM.
&&
$$
DISCUSSION/MARINE/FIRE...84/AK
AVIATION/RADAR...84/AK
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1013 PM CDT SAT APR 6 2013
.DISCUSSION...
912 PM CDT
SHOWERS CONTINUE TO MOVE ACROSS NORTHERN ILLINOIS THIS EVENING.
HOWEVER...A CLUSTER OF SHOWERS AND THUNDERSTORMS HAS DEVELOPED OVER
THE PAST COUPLE HOURS ACROSS EASTERN IOWA. THIS ACTIVITY IS FIRING
JUST AHEAD OF A SURFACE COLD FRONT IN AN AREA OF INCREASED ASCENT
AHEAD OF A RATHER STOUT MID LEVEL SHORT WAVE...CURRENTLY NOTED IN
THE WATER VAPOR IMAGERY MOVING EASTWARD ACROSS SOUTHEASTERN IOWA. THE
00 UTC SOUNDING OUT OF KDVN INDICATES THAT THE AIRMASS IN WHICH THIS
ACTIVITY IS DEVELOPING IN POSSES DECENT MID LEVEL LAPSE RATES.
HOWEVER...OVERALL INSTABILITY IS RATHER LACK LUSTER...WITH MUCAPE
VALUES ONLY UP TO AROUND 100 J/KG. IN SPITE OF THIS...THE STRONGER
FORCING FOR ASCENT COMPLEMENTS OF THE MID LEVEL WAVE AND MOISTURE
CONVERGENCE IN THE LOWER LEVELS...IS ABLE TO TAKE ADVANTAGE OF THE
STEEP LAPSE RATES TO RESULT IN THUNDERSTORMS. THIS ACTIVITY WILL
LIKELY MAINTAIN ITSELF FOR THE NEXT FEW HOURS AS IT PUSHES EASTWARD
ACROSS NORTHERN ILLINOIS. THERE COULD EVEN BE SOME SMALL HAIL AND
SOME GUSTY WINDS IN SOME OF THE STRONGEST STORMS GIVEN THE DRIER AIR
IN THE LOWEST FEW THOUSAND FEET. THIS ACTIVITY SHOULD END OVERNIGHT
WITH WINDS BECOMING WESTERLY IN THE WAKE OF THE FRONTAL PASSAGE.
KJB
//PREV DISCUSSION...
259 PM CDT
THERE ARE NUMEROUS CHALLENGES WITH THE FORECAST AS THE PATTERN
TRANSITIONS TO A MORE ACTIVE ONE...BEGINNING WITH SHOWERS AND
SOME SPORADIC THUNDER THIS EVENING AND THEN CARRYING THROUGH THE
MIDDLE OF NEXT WEEK. IN ADDITION...THE LIKELY LOCATION OF THE
AREA RELATIVE TO SYNOPTIC FEATURES WILL ALLOW FOR TEMPERATURES TO
BE HEAVILY DEPENDENT ON CLOUD COVER AND RAIN...ALONG WITH LAKE
INDUCED COOLING AT LEAST A FEW OF THE UPCOMING SEVERAL DAYS.
NEAR TERM INTO TONIGHT...A FAST PACED BUT MORE AMPLIFIED UPPER
LEVEL PATTERN IS ESTABLISHED OVER THE CENTRAL U.S. THIS AFTERNOON
WITH A WELL-DEFINED UPPER WAVE ON WATER VAPOR ADVANCING EASTWARD
FROM WESTERN IA. A 1000 MB SURFACE LOW REFLECTION ACROSS SOUTHERN
MN HAS DEVELOPED AND HELPED TO ESTABLISH STRONG RETURN FLOW WITH
WIND GUSTS TO 40 TO 45 MPH AT SEVERAL SITES. THESE WINDS SHOULD
DIMINISH GRADUALLY THROUGH THE EVENING HOURS.
MOISTURE RETURN HAS STRUGGLED HOWEVER...BOTH AT THE SURFACE AND IN
THE DEEP LAYER PER OBSERVATIONS AND PWAT ANALYSIS AND IS A REASON
SHOWER COVERAGE IS LIKELY TO BE MORE LIMITED THAN IT COULD BE
GIVEN THE UPPER FORCING AHEAD OF THIS WAVE...AND IT WILL TAKE SOME
TIME FOR THE VERY DRY LOWER ATMOSPHERE TO SATURATE. A NARROW
CORRIDOR OF 700-900 MB MOISTURE TRANSPORT ALONG A MID-LEVEL JET
HAS STILL HELPED TO INCREASE ECHOES UPSTREAM DURING THE FIRST HALF
OF THE AFTERNOON AND THIS WILL LIKELY BE JUST ENOUGH TO CONTINUE
DOING SUCH WITH STEEPENING MID-LEVEL LAPSE RATES IN CONCERT WITH
THE NARROW MOISTURE CONVERGENCE. MOST OF THE HIGH-RES CONVECTIVE
ALLOWING MODELS PREDICT AN INCREASE IN CONVECTIVE-TYPE ECHOES
ACROSS NORTH CENTRAL IL BETWEEN 23Z AND 03Z SHIFTING EASTWARD AND
FADING SLOWLY THROUGH EARLY OVERNIGHT AS THE FRONT SHIFTS EAST.
WITH SEVERAL OF THESE GUIDANCE MEMBERS INDICATING HIGHER
REFLECTIVITY AND A NARROW CORRIDOR OF 200-400 J/KG OF MUCAPE PER
THE RAP ALONG THE FRONT...WOULD EXPECT A FEW STORMS WITHIN THE
GENERAL SHOWERS. HAVE ADAPTED HOURLY POPS THROUGH THIS EVENING
PERIOD OF THE FORECAST. AS PREVIOUS FORECAST DID KEEP MOST OF
TONIGHTS TEMPERATURE DROP AFTER THE FRONTAL PASSAGE FROM WEST TO
EAST.
SUNDAY...HIGH PRESSURE STILL LOOKS TO BRIEFLY PREVAIL FOR THIS
PERIOD. THE MOST NOTEWORTHY ASPECT ABOUT THIS IS IT LOOKS TO LINE
UP DOWN THE AXIS OF LAKE MICHIGAN BY MIDDAY AND ALLOW FOR A FAIRLY
STOUT LAKE BREEZE. THIS WILL BE AIDED BY THE FACT THAT
TEMPERATURES SHOULD MODERATE NICELY ON SUNDAY OVER LAND DUE TO
ONLY A SMALL WINDOW OF COLD AIR ADVECTION BEHIND THE FRONT TONIGHT
AND A DRY AIR MASS AND PREDICTED SUNSHINE DURING SUNDAY. THE
TEMPERATURE AND PRESSURE DIFFERENCES WITHIN A LIGHT WIND FIELD
SHOULD DRIVE A STRONG LAKE BREEZE...AND THE AFTERNOON TEMPERATURE
DROP FOR DOWNTOWN CHICAGO AND OTHER NEAR LAKE AREAS MAY BE AS MUCH
AS 15 DEGREES.
SUNDAY NIGHT AND MONDAY...AN ACTIVE WEST-TO-EAST PACIFIC JET OVER
120 KT AS SEEN ON HEMISPHERIC WATER VAPOR TODAY WILL DIG ITS WAY
INTO THE WESTERN U.S. WITH TROUGH DEVELOPMENT AND UPSTREAM
SOUTHWEST FLOW OVER THE MIDWEST. A LEAD IMPULSE IN THIS FLOW IS
WELL PREDICTED ON GUIDANCE TO PASS OVER THE AREA DURING LATE
SUNDAY NIGHT INTO MONDAY MORNING. THIS LOOKS TO TIGHTEN AN UPPER
LEVEL WARM FRONT AND ALLOW FOR SATURATED ISENTROPIC LIFT FOR RAIN
SHOWERS. ELEVATED INSTABILITY DOES INCREASE AS THE WARM NOSE
BUILDS IN WITHIN THE LOWER LEVELS...AND START THUNDER IN THIS
FORECAST PERIOD ITS TOO TOUGH TO DISCERN A PERIOD WHERE THERE
WOULD NOT BE A THUNDER CHANCE ALL THE WAY THROUGH WEDNESDAY NIGHT.
IN THE WAKE OF THIS LEAD IMPULSE HEIGHTS LOOK TO BUILD ON MONDAY
AS THE PRIMARY TROUGH DEVELOPS. ITS A LITTLE INTERESTING AS THERE
SHOULD BE A SURFACE WARM FRONT...POSSIBLY DIABATICALLY
ENHANCED...LAID OUT SOMEWHERE IN THE CENTRAL IL TO NORTHERN IL
REGION. THE ONLY THING IS WITH SHORT WAVE RIDGING HINTED AT THIS
FEATURE APPEARS TO BE FAIRLY BENIGN...BUT SOMETHING TO KEEP AN
EYE ON.
MIDWEEK...AN ACTIVE PERIOD HERE AS PROLONGED SURFACE CYCLOGENESIS
BEGINS OVER THE SOUTHERN PLAINS MONDAY NIGHT AND CONTINUES THROUGH
TUESDAY WITH THE SURFACE WAVE ADVANCING ENE ON WED. MODEL
GUIDANCE HAS COME INTO BETTER AGREEMENT WITH THIS...LATCHING MORE
ONTO AN EC SOUTHERN SOLUTION. HAVE CONTINUED TO LEAN THAT WAY WITH
THE FORECAST WHICH MEANS INHIBITING TEMPERATURES ON WHAT COULD BE
GIVEN 850MB TEMPERATURES CLIMBING TO 8C-12C...ESPECIALLY NORTH OF
I-80. WITH FLOW OFF THE LAKE TUESDAY AND WEDNESDAY DUE TO THE LOW
BEING SOUTHWEST OF THE AREA...TEMPERATURES NEAR THE LAKE WILL
REMAIN COOLER. ALSO THIS FORECAST PATTERN MEANS LIKELY SEVERAL
BOUTS OF PRECIP WITH THE PROXIMITY OF THE ELEVATED WARM/STATIONARY
FRONT. THE 06.12 GFS AND EC RUNS BOTH HAVE OVER TWO AND A HALF
INCHES OF RAIN FORECAST AREA WIDE FROM SUNDAY NIGHT THROUGH
THURSDAY. WHILE IT IS CHALLENGING TO FOCUS ANY WINDOW FOR
CATEGORICAL POPS...IT WOULD SEEM WEDNESDAY AND WEDNESDAY NIGHT
WOULD BE THE MOST FAVORED PERIODS FOR STRONGER DYNAMIC FORCING AND
POSSIBLY MORE ROBUST ELEVATED CONVECTION WITH THE LARGE SCALE
UPPER TROUGH MOVING EASTWARD. COOLING BEHIND THE FRONT LOOKS
SOMEWHAT STRONG AND THERE IS A POTENTIAL TO SEE SOME MIX IN THE
WAKE OF THE FRONT...BUT CONFIDENCE IS VERY LOW ON HOW THIS SYSTEM
WILL EVOLVE AS IT LIFTS OUT.
BEYOND...HAVE GONE PRIMARILY WITH A MODEL CONSENSUS AT THE END OF
NEXT WEEK AS THE UPPER FLOW PATTERN WORKS FROM BRIEFLY NORTHWEST
BACK TO WEST. TEMPERATURES SHOULD GRADUALLY MODERATE BUT
CONFIDENCE IS LOW ON PRECIP CHANCES AS THE PATTERN STILL LOOKS
DISTURBED.
MTF
&&
.FIRE WEATHER...
328 AM...EASTERLY FLOW HAS MAINTAINED MUCH DRIER AIR ACROSS THE
REGION AND EXPECT A SLOW RETURN OF LOW LEVEL MOISTURE ACROSS THE
AREA TODAY. IT APPEARS DEWPOINTS WILL INCREASE BACK INTO THE
40S...BUT PROBABLY NOT UNTIL LATE AFTERNOON ACROSS WESTERN IL AND
THE REST OF THE AREA THIS EVENING. THUS MINIMUM RH VALUES TODAY
WILL LIKELY BE IN THE 35-40 PERCENT RANGE AND COULD POSSIBLY DIP
INTO THE 30-35 PERCENT RANGE. WHILE THESE EXPECTED VALUES WILL
REMAIN ABOVE RED FLAG CRITERIA OF 25 PERCENT...SOUTHERLY WINDS ARE
EXPECTED TO QUICKLY INCREASE THIS MORNING WITH GUSTS AS HIGH AS 40
MPH FROM LATE MORNING THROUGH SUNSET WITH THE POTENTIAL FOR HIGHER
GUSTS. WHILE THERE COULD BE A FEW LIGHT SHOWERS OR SPRINKLES
TODAY...THE BEST TIMING FOR SHOWERS AND A FEW THUNDERSTORMS WILL
BE FROM LATE AFTERNOON THROUGH MID/LATE EVENING. TEN HOUR FUEL
MOISTURE DIPPED TO 8-9 PERCENT ON FRIDAY AND SIMILAR VALUES ARE
POSSIBLE TODAY. AS A RESULT...THERE WILL BE AN INCREASED FIRE
DANGER AND WHILE MEETING RED FLAG CRITERIA IS NOT EXPECTED...
CONDITIONS WILL NEED TO BE MONITORED THROUGH DAY. CMS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* SOUTH-SOUTHWEST WINDS THROUGH THE REST OF THE EVENING SHIFTING WEST-
NORTHWEST AFTER 06Z WITH COLD FRONTAL PASSAGE.
* FREQUENT WIND GUSTS AROUND 25 KT WITH SPORADIC GUSTS CLOSER TO
30 KT STILL POSSIBLE UNTIL COLD FRONTAL PASSAGE.
* ISOLATED SHOWERS/TSRA DEVELOPING NEXT HOUR OR SO WITH BAND OF
SHRA/TSRA ARRIVING TOWARD 04Z. SMALL HAIL POSSIBLE.
* POTENTIAL FOR LOW END MVFR CIGS OVERNIGHT.
* LIGHTER NORTHWEST WINDS SUNDAY WITH LAKE BREEZE TURNING WINDS
NORTHEAST THEN EAST LATER SUNDAY AFTERNOON.
MDB
//DISCUSSION...UPDATED 03Z...
COLD FRONT NOW CROSSING THE MISSISSIPPI RIVER WITH A BAND OF
SHOWERS AND THUNDERSTORMS STRETCHING FROM KRFD TO KVYS AND POINTS
SOUTHWEST. SOME ADDITIONAL ISOLATED ACTIVITY HAS DEVELOPED AHEAD
OF THE LINE FROM KDKB TO KPWK WITH THIS SPOTTY ACTIVITY LIKELY
CONTINUING TO DEVELOP AHEAD OF THE MAIN BAND. HAVE ADJUSTED THE
TAFS TO TIME THE TS ACROSS OVER THE NEXT FEW HOURS. SOME SMALL
HAIL MAY OCCUR WITH THE STORMS. OTHERWISE...WIND GUSTS GENERALLY
REMAIN IN THE 20 TO 25 KT RANGE WITH SOME SPORADIC/INFREQUENT
GUSTS CLOSER TO 30 KT STILL OCCURRING. MAY NEED TO ADJUST TIMING
OF THE WIND SHIFT WITH THE FRONT SLIGHTLY. HAVE ALSO LOWERED CIGS
TO LOWER END MVFR FOLLOWING THE FRONTAL PASSAGE OVERNIGHT BASED ON
SATELLITE TRENDS TO THE WEST. EXPECT THESE CIGS TO SCATTER AROUND
OR SOON AFTER DAYBREAK.
MDB
FROM 00Z...
GUSTY SOUTH-SOUTHWEST WINDS CONTINUE...MAINLY FROM CHICAGO LAND
EASTWARD AS LOW PRESSURE TRACKS ACROSS WEST-CENTRAL WISCONSIN AND
A COLD FRONT MOVES INTO EASTERN IOWA. GUSTS TO AROUND 25 KT
CONTINUE WITH SOME INFREQUENT GUSTS TO AROUND 30 KT STILL POPPING
UP BUT THE OVERALL TREND APPEARS TO BE DOWNWARD. SHOWER ARE MOVING
IN FROM THE WEST AHEAD OF THE FRONT AND THESE MAY ACT TO BRING
STRONGER GUSTS BACK AS THEY PASS. SOME THUNDERSTORMS HAVE
DEVELOPED JUST AHEAD OF THE FRONT TOWARDS KCID/KIOW AND THIS
ACTIVITY MAY EXPAND IN COVERAGE AS IT MOVES EASTWARD. WILL LEAVE
TS MENTION OUT OF THE TAFS FOR NOW WITH POTENTIAL TOO LOW TO
INCLUDE...30-40 PERCENT...BUT WILL WATCH TRENDS OVER THE NEXT HOUR
OR SO AND AMEND TO ADD IF NECESSARY. THE FRONT WILL CROSS THE AREA
LATER THIS EVENING AND BRING A SHIFT TO WEST-NORTHWEST WINDS WITH
SPEEDS DIMINISHING. THERE IS STILL SOME POTENTIAL FOR LOWERING
CIGS BEHIND THE FRONT TONIGHT BUT CONFIDENCE IS LOW. IF THEY DO
OCCUR THEN THEY WILL LIKELY BE LOW END MVFR OR POSSIBLY HIGH END
IFR FOR A TIME. WILL ALSO MONITOR THIS TREND OVER THE NEXT FEW
HOURS AND LOWER TAF CIGS IF NEEDED. RELATIVELY LIGHT NORTHWEST
WINDS WILL OCCUR SUNDAY MORNING BUT HIGH PRESSURE WILL MOVE
OVERHEAD SO LIGHT AND VARIABLE WINDS MAY PREVAIL BY AFTERNOON. A
LAKE BREEZE WILL LIKELY DEVELOP AND TURN WINDS NORTHEASTWARD
ACROSS THE CHICAGO AREA TERMINALS DURING THE AFTERNOON. LOW
PRESSURE WILL DEVELOP OVER THE CENTRAL HIGH PLAINS LATER SUNDAY
ALLOWING A STEADY EAST WIND TO DEVELOP ACROSS ALL AREAS SUNDAY
EVENING WHICH WILL TURN SOUTHEASTERLY INTO MONDAY. SHOWER AND
THUNDERSTORM CHANCES INCREASE EARLY SUNDAY NIGHT.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* HIGH CONFIDENCE IN WIND DIRECTION TRENDS THROUGH TONIGHT.
* MEDIUM-HIGH CONFIDENCE IN FREQUENT GUSTS TO AROUND 25 KT WITH
SPORADIC GUSTS TO 30 KT THROUGH LATE EVENING.
* HIGH CONFIDENCE IN PRECIP TIMING/DURATION.
* MEDIUM CONFIDENCE IN LOW MVFR CIG POTENTIAL OVERNIGHT.
* HIGH CONFIDENCE IN WIND TRENDS/LAKE BREEZE SUNDAY.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY...SHRA/TSRA LIKELY EARLY. MVFR/BRIEF IFR POSSIBLE EARLY.
TUESDAY THROUGH THURSDAY NIGHT...PERIODIC CHANCE FOR SHRA/TSRA.
PERIODIC MVFR CIGS/VSBY LIKELY WITH BRIEF IFR POSSIBLE.
FRIDAY...PROBABLE VFR.
MDB
&&
.MARINE...
241 PM CDT
LOW PRESSURE OVER SOUTHERN MINNESOTA THIS AFTERNOON IS LIFTING A
STRONG WARM FRONT ACROSS LAKE MICHIGAN TODAY. WINDS OVER THE LAND
ARE TOPPING OUT AROUND 35 KT THIS AFTERNOON WITH THESE GALES
EXTENDING INTO THE NEARSHORE WATERS WHERE A GALE WARNING REMAINS
IN EFFECT THROUGH THIS EVENING. HOWEVER...WITH TEMPERATURES
PUSHING 70 ACROSS NORTHERN ILLINOIS/INDIANA...VERY STABLE
CONDITIONS ARE SETTING UP OVER THE OPEN WATERS OF THE LAKE AND
SHOULD BE INHIBITING THE STRONGER GUSTS FROM REACHING THE LAKE
SURFACE. THE LOW WILL MOVE ACROSS NORTHERN LAKE MICHIGAN LATE
THIS EVENING WITH A TRAILING COLD FRONT PUSHING ACROSS THE LAKE
SHORTLY THEREAFTER WITH WINDS TURNING WESTERLY AND DIMINISHING.
ANOTHER LOW PRESSURE SYSTEM IS FORECAST TO MOVE INTO THE REGION
MIDWEEK...THOUGH MODELS CONTINUE TO STRUGGLE WITH TRACK AND TIMING
MAKING IT DIFFICULT TO PIN DOWN DETAILS REGARDING OVER THE LAKE.
CONTINUE TO FAVOR A FARTHER SOUTH SOLUTION SUPPORTED BY THE
CONSISTENT ECMWF...WHICH THE LATEST GFS HAS TRENDED TOWARDS.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 4 AM SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
915 PM CDT SAT APR 6 2013
.DISCUSSION...
912 PM CDT
SHOWERS CONTINUE TO MOVE ACROSS NORTHERN ILLINOIS THIS EVENING.
HOWEVER...A CLUSTER OF SHOWERS AND THUNDERSTORMS HAS DEVELOPED OVER
THE PAST COUPLE HOURS ACROSS EASTERN IOWA. THIS ACTIVITY IS FIRING
JUST AHEAD OF A SURFACE COLD FRONT IN AN AREA OF INCREASED ASCENT
AHEAD OF A RATHER STOUT MID LEVEL SHORT WAVE...CURRENTLY NOTED IN
THE WATER VAPOR IMAGERY MOVING EASTWARD ACROSS SOUTHEASTERN IOWA. THE
00 UTC SOUNDING OUT OF KDVN INDICATES THAT THE AIRMASS IN WHICH THIS
ACTIVITY IS DEVELOPING IN POSSES DECENT MID LEVEL LAPSE RATES.
HOWEVER...OVERALL INSTABILITY IS RATHER LACK LUSTER...WITH MUCAPE
VALUES ONLY UP TO AROUND 100 J/KG. IN SPITE OF THIS...THE STRONGER
FORCING FOR ASCENT COMPLEMENTS OF THE MID LEVEL WAVE AND MOISTURE
CONVERGENCE IN THE LOWER LEVELS...IS ABLE TO TAKE ADVANTAGE OF THE
STEEP LAPSE RATES TO RESULT IN THUNDERSTORMS. THIS ACTIVITY WILL
LIKELY MAINTAIN ITSELF FOR THE NEXT FEW HOURS AS IT PUSHES EASTWARD
ACROSS NORTHERN ILLINOIS. THERE COULD EVEN BE SOME SMALL HAIL AND
SOME GUSTY WINDS IN SOME OF THE STRONGEST STORMS GIVEN THE DRIER AIR
IN THE LOWEST FEW THOUSAND FEET. THIS ACTIVITY SHOULD END OVERNIGHT
WITH WINDS BECOMING WESTERLY IN THE WAKE OF THE FRONTAL PASSAGE.
KJB
&&
.PREV DISCUSSION...
259 PM CDT
THERE ARE NUMEROUS CHALLENGES WITH THE FORECAST AS THE PATTERN
TRANSITIONS TO A MORE ACTIVE ONE...BEGINNING WITH SHOWERS AND
SOME SPORADIC THUNDER THIS EVENING AND THEN CARRYING THROUGH THE
MIDDLE OF NEXT WEEK. IN ADDITION...THE LIKELY LOCATION OF THE
AREA RELATIVE TO SYNOPTIC FEATURES WILL ALLOW FOR TEMPERATURES TO
BE HEAVILY DEPENDENT ON CLOUD COVER AND RAIN...ALONG WITH LAKE
INDUCED COOLING AT LEAST A FEW OF THE UPCOMING SEVERAL DAYS.
NEAR TERM INTO TONIGHT...A FAST PACED BUT MORE AMPLIFIED UPPER
LEVEL PATTERN IS ESTABLISHED OVER THE CENTRAL U.S. THIS AFTERNOON
WITH A WELL-DEFINED UPPER WAVE ON WATER VAPOR ADVANCING EASTWARD
FROM WESTERN IA. A 1000 MB SURFACE LOW REFLECTION ACROSS SOUTHERN
MN HAS DEVELOPED AND HELPED TO ESTABLISH STRONG RETURN FLOW WITH
WIND GUSTS TO 40 TO 45 MPH AT SEVERAL SITES. THESE WINDS SHOULD
DIMINISH GRADUALLY THROUGH THE EVENING HOURS.
MOISTURE RETURN HAS STRUGGLED HOWEVER...BOTH AT THE SURFACE AND IN
THE DEEP LAYER PER OBSERVATIONS AND PWAT ANALYSIS AND IS A REASON
SHOWER COVERAGE IS LIKELY TO BE MORE LIMITED THAN IT COULD BE
GIVEN THE UPPER FORCING AHEAD OF THIS WAVE...AND IT WILL TAKE SOME
TIME FOR THE VERY DRY LOWER ATMOSPHERE TO SATURATE. A NARROW
CORRIDOR OF 700-900 MB MOISTURE TRANSPORT ALONG A MID-LEVEL JET
HAS STILL HELPED TO INCREASE ECHOES UPSTREAM DURING THE FIRST HALF
OF THE AFTERNOON AND THIS WILL LIKELY BE JUST ENOUGH TO CONTINUE
DOING SUCH WITH STEEPENING MID-LEVEL LAPSE RATES IN CONCERT WITH
THE NARROW MOISTURE CONVERGENCE. MOST OF THE HIGH-RES CONVECTIVE
ALLOWING MODELS PREDICT AN INCREASE IN CONVECTIVE-TYPE ECHOES
ACROSS NORTH CENTRAL IL BETWEEN 23Z AND 03Z SHIFTING EASTWARD AND
FADING SLOWLY THROUGH EARLY OVERNIGHT AS THE FRONT SHIFTS EAST.
WITH SEVERAL OF THESE GUIDANCE MEMBERS INDICATING HIGHER
REFLECTIVITY AND A NARROW CORRIDOR OF 200-400 J/KG OF MUCAPE PER
THE RAP ALONG THE FRONT...WOULD EXPECT A FEW STORMS WITHIN THE
GENERAL SHOWERS. HAVE ADAPTED HOURLY POPS THROUGH THIS EVENING
PERIOD OF THE FORECAST. AS PREVIOUS FORECAST DID KEEP MOST OF
TONIGHTS TEMPERATURE DROP AFTER THE FRONTAL PASSAGE FROM WEST TO
EAST.
SUNDAY...HIGH PRESSURE STILL LOOKS TO BRIEFLY PREVAIL FOR THIS
PERIOD. THE MOST NOTEWORTHY ASPECT ABOUT THIS IS IT LOOKS TO LINE
UP DOWN THE AXIS OF LAKE MICHIGAN BY MIDDAY AND ALLOW FOR A FAIRLY
STOUT LAKE BREEZE. THIS WILL BE AIDED BY THE FACT THAT
TEMPERATURES SHOULD MODERATE NICELY ON SUNDAY OVER LAND DUE TO
ONLY A SMALL WINDOW OF COLD AIR ADVECTION BEHIND THE FRONT TONIGHT
AND A DRY AIR MASS AND PREDICTED SUNSHINE DURING SUNDAY. THE
TEMPERATURE AND PRESSURE DIFFERENCES WITHIN A LIGHT WIND FIELD
SHOULD DRIVE A STRONG LAKE BREEZE...AND THE AFTERNOON TEMPERATURE
DROP FOR DOWNTOWN CHICAGO AND OTHER NEAR LAKE AREAS MAY BE AS MUCH
AS 15 DEGREES.
SUNDAY NIGHT AND MONDAY...AN ACTIVE WEST-TO-EAST PACIFIC JET OVER
120 KT AS SEEN ON HEMISPHERIC WATER VAPOR TODAY WILL DIG ITS WAY
INTO THE WESTERN U.S. WITH TROUGH DEVELOPMENT AND UPSTREAM
SOUTHWEST FLOW OVER THE MIDWEST. A LEAD IMPULSE IN THIS FLOW IS
WELL PREDICTED ON GUIDANCE TO PASS OVER THE AREA DURING LATE
SUNDAY NIGHT INTO MONDAY MORNING. THIS LOOKS TO TIGHTEN AN UPPER
LEVEL WARM FRONT AND ALLOW FOR SATURATED ISENTROPIC LIFT FOR RAIN
SHOWERS. ELEVATED INSTABILITY DOES INCREASE AS THE WARM NOSE
BUILDS IN WITHIN THE LOWER LEVELS...AND START THUNDER IN THIS
FORECAST PERIOD ITS TOO TOUGH TO DISCERN A PERIOD WHERE THERE
WOULD NOT BE A THUNDER CHANCE ALL THE WAY THROUGH WEDNESDAY NIGHT.
IN THE WAKE OF THIS LEAD IMPULSE HEIGHTS LOOK TO BUILD ON MONDAY
AS THE PRIMARY TROUGH DEVELOPS. ITS A LITTLE INTERESTING AS THERE
SHOULD BE A SURFACE WARM FRONT...POSSIBLY DIABATICALLY
ENHANCED...LAID OUT SOMEWHERE IN THE CENTRAL IL TO NORTHERN IL
REGION. THE ONLY THING IS WITH SHORT WAVE RIDGING HINTED AT THIS
FEATURE APPEARS TO BE FAIRLY BENIGN...BUT SOMETHING TO KEEP AN
EYE ON.
MIDWEEK...AN ACTIVE PERIOD HERE AS PROLONGED SURFACE CYCLOGENESIS
BEGINS OVER THE SOUTHERN PLAINS MONDAY NIGHT AND CONTINUES THROUGH
TUESDAY WITH THE SURFACE WAVE ADVANCING ENE ON WED. MODEL
GUIDANCE HAS COME INTO BETTER AGREEMENT WITH THIS...LATCHING MORE
ONTO AN EC SOUTHERN SOLUTION. HAVE CONTINUED TO LEAN THAT WAY WITH
THE FORECAST WHICH MEANS INHIBITING TEMPERATURES ON WHAT COULD BE
GIVEN 850MB TEMPERATURES CLIMBING TO 8C-12C...ESPECIALLY NORTH OF
I-80. WITH FLOW OFF THE LAKE TUESDAY AND WEDNESDAY DUE TO THE LOW
BEING SOUTHWEST OF THE AREA...TEMPERATURES NEAR THE LAKE WILL
REMAIN COOLER. ALSO THIS FORECAST PATTERN MEANS LIKELY SEVERAL
BOUTS OF PRECIP WITH THE PROXIMITY OF THE ELEVATED WARM/STATIONARY
FRONT. THE 06.12 GFS AND EC RUNS BOTH HAVE OVER TWO AND A HALF
INCHES OF RAIN FORECAST AREA WIDE FROM SUNDAY NIGHT THROUGH
THURSDAY. WHILE IT IS CHALLENGING TO FOCUS ANY WINDOW FOR
CATEGORICAL POPS...IT WOULD SEEM WEDNESDAY AND WEDNESDAY NIGHT
WOULD BE THE MOST FAVORED PERIODS FOR STRONGER DYNAMIC FORCING AND
POSSIBLY MORE ROBUST ELEVATED CONVECTION WITH THE LARGE SCALE
UPPER TROUGH MOVING EASTWARD. COOLING BEHIND THE FRONT LOOKS
SOMEWHAT STRONG AND THERE IS A POTENTIAL TO SEE SOME MIX IN THE
WAKE OF THE FRONT...BUT CONFIDENCE IS VERY LOW ON HOW THIS SYSTEM
WILL EVOLVE AS IT LIFTS OUT.
BEYOND...HAVE GONE PRIMARILY WITH A MODEL CONSENSUS AT THE END OF
NEXT WEEK AS THE UPPER FLOW PATTERN WORKS FROM BRIEFLY NORTHWEST
BACK TO WEST. TEMPERATURES SHOULD GRADUALLY MODERATE BUT
CONFIDENCE IS LOW ON PRECIP CHANCES AS THE PATTERN STILL LOOKS
DISTURBED.
MTF
&&
.FIRE WEATHER...
328 AM...EASTERLY FLOW HAS MAINTAINED MUCH DRIER AIR ACROSS THE
REGION AND EXPECT A SLOW RETURN OF LOW LEVEL MOISTURE ACROSS THE
AREA TODAY. IT APPEARS DEWPOINTS WILL INCREASE BACK INTO THE
40S...BUT PROBABLY NOT UNTIL LATE AFTERNOON ACROSS WESTERN IL AND
THE REST OF THE AREA THIS EVENING. THUS MINIMUM RH VALUES TODAY
WILL LIKELY BE IN THE 35-40 PERCENT RANGE AND COULD POSSIBLY DIP
INTO THE 30-35 PERCENT RANGE. WHILE THESE EXPECTED VALUES WILL
REMAIN ABOVE RED FLAG CRITERIA OF 25 PERCENT...SOUTHERLY WINDS ARE
EXPECTED TO QUICKLY INCREASE THIS MORNING WITH GUSTS AS HIGH AS 40
MPH FROM LATE MORNING THROUGH SUNSET WITH THE POTENTIAL FOR HIGHER
GUSTS. WHILE THERE COULD BE A FEW LIGHT SHOWERS OR SPRINKLES
TODAY...THE BEST TIMING FOR SHOWERS AND A FEW THUNDERSTORMS WILL
BE FROM LATE AFTERNOON THROUGH MID/LATE EVENING. TEN HOUR FUEL
MOISTURE DIPPED TO 8-9 PERCENT ON FRIDAY AND SIMILAR VALUES ARE
POSSIBLE TODAY. AS A RESULT...THERE WILL BE AN INCREASED FIRE
DANGER AND WHILE MEETING RED FLAG CRITERIA IS NOT EXPECTED...
CONDITIONS WILL NEED TO BE MONITORED THROUGH DAY. CMS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* 180-210 DEGREE WINDS THROUGH MID EVENING WITH SOME VARIABILITY
TO 220-230 AFTER APPROX 03Z. WINDS SHIFT WEST-NORTHWEST AFTER
06Z WITH COLD FRONTAL PASSAGE.
* FREQUENT WIND GUSTS AROUND 25 KT WITH SPORADIC GUSTS CLOSER TO
30 KT MAINLY THROUGH SUNSET...APPROACHING SHOWERS MAY PRODUCE 30
KT GUSTS THROUGH THE EVENING.
* STEADIER RAIN SHOWERS ARRIVING TOWARD 01Z WITH A CHANCE FOR
SHORT PERIOD OF TS AFTER ABOUT 03Z.
* POTENTIAL FOR LOW END MVFR CIGS OVERNIGHT.
* LIGHTER NORTHWEST WINDS SUNDAY WITH LAKE BREEZE TURNING WINDS
NORTHEAST THEN EAST LATER SUNDAY AFTERNOON.
MDB
//DISCUSSION...UPDATED 00Z...
GUSTY SOUTH-SOUTHWEST WINDS CONTINUE...MAINLY FROM CHICAGO LAND
EASTWARD AS LOW PRESSURE TRACKS ACROSS WEST-CENTRAL WISCONSIN AND
A COLD FRONT MOVES INTO EASTERN IOWA. GUSTS TO AROUND 25 KT
CONTINUE WITH SOME INFREQUENT GUSTS TO AROUND 30 KT STILL POPPING
UP BUT THE OVERALL TREND APPEARS TO BE DOWNWARD. SHOWER ARE MOVING
IN FROM THE WEST AHEAD OF THE FRONT AND THESE MAY ACT TO BRING
STRONGER GUSTS BACK AS THEY PASS. SOME THUNDERSTORMS HAVE
DEVELOPED JUST AHEAD OF THE FRONT TOWARDS KCID/KIOW AND THIS
ACTIVITY MAY EXPAND IN COVERAGE AS IT MOVES EASTWARD. WILL LEAVE
TS MENTION OUT OF THE TAFS FOR NOW WITH POTENTIAL TOO LOW TO
INCLUDE...30-40 PERCENT...BUT WILL WATCH TRENDS OVER THE NEXT HOUR
OR SO AND AMEND TO ADD IF NECESSARY. THE FRONT WILL CROSS THE AREA
LATER THIS EVENING AND BRING A SHIFT TO WEST-NORTHWEST WINDS WITH
SPEEDS DIMINISHING. THERE IS STILL SOME POTENTIAL FOR LOWERING
CIGS BEHIND THE FRONT TONIGHT BUT CONFIDENCE IS LOW. IF THEY DO
OCCUR THEN THEY WILL LIKELY BE LOW END MVFR OR POSSIBLY HIGH END
IFR FOR A TIME. WILL ALSO MONITOR THIS TREND OVER THE NEXT FEW
HOURS AND LOWER TAF CIGS IF NEEDED. RELATIVELY LIGHT NORTHWEST
WINDS WILL OCCUR SUNDAY MORNING BUT HIGH PRESSURE WILL MOVE
OVERHEAD SO LIGHT AND VARIABLE WINDS MAY PREVAIL BY AFTERNOON. A
LAKE BREEZE WILL LIKELY DEVELOP AND TURN WINDS NORTHEASTWARD
ACROSS THE CHICAGO AREA TERMINALS DURING THE AFTERNOON. LOW
PRESSURE WILL DEVELOP OVER THE CENTRAL HIGH PLAINS LATER SUNDAY
ALLOWING A STEADY EAST WIND TO DEVELOP ACROSS ALL AREAS SUNDAY
EVENING WHICH WILL TURN SOUTHEASTERLY INTO MONDAY. SHOWER AND
THUNDERSTORM CHANCES INCREASE EARLY SUNDAY NIGHT.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* HIGH CONFIDENCE IN WIND DIRECTION TRENDS THROUGH TONIGHT.
* MEDIUM-HIGH CONFIDENCE IN FREQUENT GUSTS TO AROUND 25 KT WITH
SPORADIC GUSTS TO 30 KT THROUGH SUNSET.
* HIGH CONFIDENCE IN PRECIP TIMING/DURATION...MEDIUM CONFIDENCE IN
TS POTENTIAL AND TIMING BUT CHANCE IS TOO LOW TO MENTION IN TAF
RIGHT NOW.
* LOW CONFIDENCE IN LOW MVFR CIG POTENTIAL OVERNIGHT.
* HIGH CONFIDENCE IN WIND TRENDS/LAKE BREEZE SUNDAY.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY...SHRA/TSRA LIKELY EARLY. MVFR/BRIEF IFR POSSIBLE EARLY.
TUESDAY THROUGH THURSDAY NIGHT...PERIODIC CHANCE FOR SHRA/TSRA.
PERIODIC MVFR CIGS/VSBY LIKELY WITH BRIEF IFR POSSIBLE.
FRIDAY...PROBABLE VFR.
MDB
&&
.MARINE...
241 PM CDT
LOW PRESSURE OVER SOUTHERN MINNESOTA THIS AFTERNOON IS LIFTING A
STRONG WARM FRONT ACROSS LAKE MICHIGAN TODAY. WINDS OVER THE LAND
ARE TOPPING OUT AROUND 35 KT THIS AFTERNOON WITH THESE GALES
EXTENDING INTO THE NEARSHORE WATERS WHERE A GALE WARNING REMAINS
IN EFFECT THROUGH THIS EVENING. HOWEVER...WITH TEMPERATURES
PUSHING 70 ACROSS NORTHERN ILLINOIS/INDIANA...VERY STABLE
CONDITIONS ARE SETTING UP OVER THE OPEN WATERS OF THE LAKE AND
SHOULD BE INHIBITING THE STRONGER GUSTS FROM REACHING THE LAKE
SURFACE. THE LOW WILL MOVE ACROSS NORTHERN LAKE MICHIGAN LATE
THIS EVENING WITH A TRAILING COLD FRONT PUSHING ACROSS THE LAKE
SHORTLY THEREAFTER WITH WINDS TURNING WESTERLY AND DIMINISHING.
ANOTHER LOW PRESSURE SYSTEM IS FORECAST TO MOVE INTO THE REGION
MIDWEEK...THOUGH MODELS CONTINUE TO STRUGGLE WITH TRACK AND TIMING
MAKING IT DIFFICULT TO PIN DOWN DETAILS REGARDING OVER THE LAKE.
CONTINUE TO FAVOR A FARTHER SOUTH SOLUTION SUPPORTED BY THE
CONSISTENT ECMWF...WHICH THE LATEST GFS HAS TRENDED TOWARDS.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...NEARSHORE WATERS UNTIL
10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
909 PM CDT SAT APR 6 2013
.DISCUSSION...
ISSUED 900 PM CDT SAT APR 6 2013
A LINE OF SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE TO
PROGRESS EASTWARD ACROSS THE NORTHERN HALF OF THE CWA THIS EVENING
AHEAD OF A COLD FRONT. THE WINDOW OF OPPORTUNITY FOR THUNDER LOOKS
TO BE AROUND 2 HOURS WITH THUNDER JUST REPORTED IN PIA AHEAD OF
THE STRONGER LINE BACK NEAR GALESBURG. THE LOW LEVEL CONVERGENCE
AND INSTABILITY LOOKS TO BE GRADUALLY WEAKENING AFTER SUNSET...AND
THE FRONTAL CIRCULATIONS ARE FORECAST TO NEARLY DISSIPATE BY 12Z
WHEN THE FRONT REACHES OUR SOUTHEAST COUNTIES. WE MAINLY KEPT THE
HIGH CHANCE POPS ACROSS THE NORTH...AND PROGRESSED THEM TOWARD
CHAMPAIGN BY 06Z/1AM WITH ONLY SLIGHT CHANCE POPS IN THE SOUTHEAST
THIRD OF OUR COUNTIES AFTER 06Z/1AM.
THE GUSTY WINDS ARE MAINLY CONFINED TO AREAS EAST OF LINCOLN TO
BLOOMINGTON AT 9 PM. LIGHTER WINDS WILL ARRIVE WITH THE COLD FRONT
AND A WIND SHIFT TO THE WEST.
THE FRONT IS STILL EXPECTED TO RETURN NORTH AND BECOME ACTIVE
AGAIN SUNDAY AFTERNOON AND ESPECIALLY SUNDAY NIGHT IN THE WEST.
FOR TONIGHT...UPDATED THE POP/WEATHER AND WINDS TO MORE CLOSELY
MATCH CURRENT TRENDS. NO MAJOR CHANCES OVERALL. UPDATED INFO WILL
BE AVAILABLE SHORTLY.
SHIMON
&&
.AVIATION...
ISSUED 700 PM CDT SAT APR 6 2013...FOR THE 00Z TAFS
A COLD FRONT MOVING ACROSS CENTRAL ILLINOIS THIS EVENING SHOULD
HAVE ENOUGH INSTABILITY FOR AT LEAST A LINE OF SHOWERS AND
ISOLATED THUNDERSTORMS TO DEVELOP DURING A MOVING 2 TO 4 HOUR
WINDOW THIS EVENING. THE PRECIP SHOULD DEVELOP IN PIA SHORTLY
BETWEEN 00-01Z AND ADVANCE EASTWARD FROM THERE, REACHING CMI BY
04Z. THE HRRR MODEL OUTPUT SEEMS TO HAVE A GOOD HANDLE ON THE
CURRENT STATUS OF THE SYSTEM...AND GENERALLY FOLLOWED ITS OUTPUT
ON TIMING. I DECIDED TO LEAVE OUT THUNDER IN THE TAFS DUE TO THE
ISOLATED NATURE AND LOW CONFIDENCE THAT ANY STORM WILL COME WITHIN
5 MILES OF ANY TERMINAL SITE.
VERY GUSTY WINDS WILL DIMINISH SOME THIS EVENING...BUT A FEW GUSTS
IN THE 25-28KT RANGE WILL CONTINUE FOR AT LEAST A COUPLE HOURS
BEFORE THE FRONT ARRIVES FROM WEST TO EAST.
WINDS WILL SHIFT TO THE WEST BEHIND THE FRONT...AND BECOME MUCH
LIGHTER...AROUND 12-13KT. EVEN LIGHTER SOUTHWEST WINDS ARE
EXPECTED TOMORROW UNDER ADVANCING HIGH PRESSURE.
SHIMON
&&
.PREV DISCUSSION...
ISSUED 300 PM CDT SAT APR 6 2013
00Z MODELS CONTINUE A MILD AND UNSETTLED WEATHER PATTERN THROUGH
MID WEEK WITH COOLER AND DRIER CONDITIONS THE END OF NEXT WEEK.
WILL USE A MODEL BLEND THIS FORECAST PACKAGE. MET AND MAV GUIDANCE
TEMPS ARE SIMILAR THROUGH MON NIGHT AND STAYED FAIRLY CLOSE TO.
SHORT TERM...TODAY THROUGH TUESDAY NIGHT
STRONG SOUTH WINDS OF 20-35 MPH AND GUSTS OF 35-50 MPH THIS
AFTERNOON WITH STRONGEST WIND GUSTS FROM I-72 NORTH. A SPECIAL
WEATHER STATEMENT WAS ISSUED TO ADDRESS THESE HIGH WINDS THROUGH
8 PM. 999 MB LOW PRESSURE OVER SOUTHCENTRAL MN HAS A COLD FRONT
INTO CENTRAL IA...NW MO AND CENTRAL OK. WARM FRONT HAD LIFTED NE
OF IL WITH MILD TEMPS IN THE UPPER 60S AND LOWER 70S OVER CENTRAL
AND SE IL AND MILDEST TEMPS SINCE NOV 10TH.
LOW PRESSURE TO MOVE TOWARD NORTHERN LAKE MI BY 06Z TONIGHT AND
PULL COLD FRONT TOWARD I-55. LOW PRESSURE DEEPENS TO 996 MB JUST
EAST OF UPPER MI BY 12Z/SUN AND COLD FRONT SWEEPS THROUGH SE IL
LATE TONIGHT INTO MID MORNING SUNDAY. HAVE CHANCE OF SHOWERS AND
ISOLATED THUNDERSTORMS OVER CENTRAL IL THIS EVENING AND SHIFTING
INTO SE IL OVERNIGHT INTO MID MORNING SUNDAY. LIMITED MOISTURE
WITH COLD FRONT AND MODELS HAVE TRENDED LOWER WITH QPF AMOUNTS
TONIGHT INTO SUNDAY. LOWS TONIGHT RANGE FROM THE LOWER 40S NW OF
THE IL RIVER TO THE LOWER 50S IN SE IL.
FRONTAL BOUNDARY TO START LIFTING BACK NORTH TOWARD CENTRAL/SE IL
BY SUNSET SUNDAY AND RETURNING 20-40% CHANCE OF SHOWERS AND
ISOLATED THUNDERSTORMS LATE SUNDAY AFTERNOON INTO PARTS OF CENTRAL
AND SW IL. HIGHS TO RANGE FROM THE MID 60S NORTH OF PEORIA TO THE
LOWER 70S SOUTH OF I-72. WARM FRONT LIFTS NORTH THROUGH CENTRAL IL
SUNDAY NIGHT AND INTO NORTHERN IL MON AND LIKELY ACCOMPANIED BY A
SHOWERS AND A CHANCE OF THUNDERSTORMS ESPECIALLY NORTH OF I-70.
MILD HIGHS MON AGAIN IN THE UPPER 60S AND LOWER 70S WITH COOLEST
READINGS FROM I-74 NORTH.
CHANCES OF SHOWERS AND THUNDERSTORMS LINGERS TUE AND HIGHEST POPS
IN NORTHERN AREAS CLOSER TO FRONTAL BOUNDARY LINGERING OVER
NORTHERN IL.
LONG TERM...WEDNESDAY THROUGH SATURDAY
STRONG LOW PRESSURE TO EJECT NE AROUND WED WITH BEST CHANCES OF
SHOWERS AND THUNDERSTORMS AND SPC HAS RISK OF STRONG TO SEVERE
STORMS OVER SOUTHERN IL WED. GFS IS QUICKER WITH THIS STORM SYSTEM
THAN THE ECMWF MODEL AND USED A BLEND FOR NOW WITH PLENTY OF TIME TO
SORT OUT THE TIMING DIFFERENCES. MAY BE A GRADIENT OF TEMPS WED WITH
COOLER HIGHS IN THE UPPER 50S NW OF THE IL RIVER AND MILDER LOWER
70S SE OF I-70. STRONG UPPER LEVEL TROF OVER THE MIDWEST THU TO KEEP
LOW CLOUDS AROUND ALONG WITH LINGERING CHANCES OF SHOWERS AND COOLER
TEMPS. DRIER WEATHER EXPECTED FRIDAY ALONG WITH TEMPS BEING A BIT
COOLER THAN NORMAL THU/FRI WITH HIGHS IN THE 50S.
07
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
702 PM CDT SAT APR 6 2013
.DISCUSSION...
ISSUED 300 PM CDT SAT APR 6 2013
00Z MODELS CONTINUE A MILD AND UNSETTLED WEATHER PATTERN THROUGH
MID WEEK WITH COOLER AND DRIER CONDITIONS THE END OF NEXT WEEK.
WILL USE A MODEL BLEND THIS FORECAST PACKAGE. MET AND MAV GUIDANCE
TEMPS ARE SIMILAR THROUGH MON NIGHT AND STAYED FAIRLY CLOSE TO.
SHORT TERM...TODAY THROUGH TUESDAY NIGHT
STRONG SOUTH WINDS OF 20-35 MPH AND GUSTS OF 35-50 MPH THIS
AFTERNOON WITH STRONGEST WIND GUSTS FROM I-72 NORTH. A SPECIAL
WEATHER STATEMENT WAS ISSUED TO ADDRESS THESE HIGH WINDS THROUGH
8 PM. 999 MB LOW PRESSURE OVER SOUTHCENTRAL MN HAS A COLD FRONT
INTO CENTRAL IA...NW MO AND CENTRAL OK. WARM FRONT HAD LIFTED NE
OF IL WITH MILD TEMPS IN THE UPPER 60S AND LOWER 70S OVER CENTRAL
AND SE IL AND MILDEST TEMPS SINCE NOV 10TH.
LOW PRESSURE TO MOVE TOWARD NORTHERN LAKE MI BY 06Z TONIGHT AND
PULL COLD FRONT TOWARD I-55. LOW PRESSURE DEEPENS TO 996 MB JUST
EAST OF UPPER MI BY 12Z/SUN AND COLD FRONT SWEEPS THROUGH SE IL
LATE TONIGHT INTO MID MORNING SUNDAY. HAVE CHANCE OF SHOWERS AND
ISOLATED THUNDERSTORMS OVER CENTRAL IL THIS EVENING AND SHIFTING
INTO SE IL OVERNIGHT INTO MID MORNING SUNDAY. LIMITED MOISTURE
WITH COLD FRONT AND MODELS HAVE TRENDED LOWER WITH QPF AMOUNTS
TONIGHT INTO SUNDAY. LOWS TONIGHT RANGE FROM THE LOWER 40S NW OF
THE IL RIVER TO THE LOWER 50S IN SE IL.
FRONTAL BOUNDARY TO START LIFTING BACK NORTH TOWARD CENTRAL/SE IL
BY SUNSET SUNDAY AND RETURNING 20-40% CHANCE OF SHOWERS AND
ISOLATED THUNDERSTORMS LATE SUNDAY AFTERNOON INTO PARTS OF CENTRAL
AND SW IL. HIGHS TO RANGE FROM THE MID 60S NORTH OF PEORIA TO THE
LOWER 70S SOUTH OF I-72. WARM FRONT LIFTS NORTH THROUGH CENTRAL IL
SUNDAY NIGHT AND INTO NORTHERN IL MON AND LIKELY ACCOMPANIED BY A
SHOWERS AND A CHANCE OF THUNDERSTORMS ESPECIALLY NORTH OF I-70.
MILD HIGHS MON AGAIN IN THE UPPER 60S AND LOWER 70S WITH COOLEST
READINGS FROM I-74 NORTH.
CHANCES OF SHOWERS AND THUNDERSTORMS LINGERS TUE AND HIGHEST POPS
IN NORTHERN AREAS CLOSER TO FRONTAL BOUNDARY LINGERING OVER
NORTHERN IL.
LONG TERM...WEDNESDAY THROUGH SATURDAY
STRONG LOW PRESSURE TO EJECT NE AROUND WED WITH BEST CHANCES OF
SHOWERS AND THUNDERSTORMS AND SPC HAS RISK OF STRONG TO SEVERE
STORMS OVER SOUTHERN IL WED. GFS IS QUICKER WITH THIS STORM SYSTEM
THAN THE ECMWF MODEL AND USED A BLEND FOR NOW WITH PLENTY OF TIME TO
SORT OUT THE TIMING DIFFERENCES. MAY BE A GRADIENT OF TEMPS WED WITH
COOLER HIGHS IN THE UPPER 50S NW OF THE IL RIVER AND MILDER LOWER
70S SE OF I-70. STRONG UPPER LEVEL TROF OVER THE MIDWEST THU TO KEEP
LOW CLOUDS AROUND ALONG WITH LINGERING CHANCES OF SHOWERS AND COOLER
TEMPS. DRIER WEATHER EXPECTED FRIDAY ALONG WITH TEMPS BEING A BIT
COOLER THAN NORMAL THU/FRI WITH HIGHS IN THE 50S.
07
&&
.AVIATION...
ISSUED 700 PM CDT SAT APR 6 2013...FOR THE 00Z TAFS
A COLD FRONT MOVING ACROSS CENTRAL ILLINOIS THIS EVENING SHOULD
HAVE ENOUGH INSTABILITY FOR AT LEAST A LINE OF SHOWERS AND
ISOLATED THUNDERSTORMS TO DEVELOP DURING A MOVING 2 TO 4 HOUR
WINDOW THIS EVENING. THE PRECIP SHOULD DEVELOP IN PIA SHORTLY
BETWEEN 00-01Z AND ADVANCE EASTWARD FROM THERE, REACHING CMI BY
04Z. THE HRRR MODEL OUTPUT SEEMS TO HAVE A GOOD HANDLE ON THE
CURRENT STATUS OF THE SYSTEM...AND GENERALLY FOLLOWED ITS OUTPUT
ON TIMING. I DECIDED TO LEAVE OUT THUNDER IN THE TAFS DUE TO THE
ISOLATED NATURE AND LOW CONFIDENCE THAT ANY STORM WILL COME WITHIN
5 MILES OF ANY TERMINAL SITE.
VERY GUSTY WINDS WILL DIMINISH SOME THIS EVENING...BUT A FEW GUSTS
IN THE 25-28KT RANGE WILL CONTINUE FOR AT LEAST A COUPLE HOURS
BEFORE THE FRONT ARRIVES FROM WEST TO EAST.
WINDS WILL SHIFT TO THE WEST BEHIND THE FRONT...AND BECOME MUCH
LIGHTER...AROUND 12-13KT. EVEN LIGHTER SOUTHWEST WINDS ARE
EXPECTED TOMORROW UNDER ADVANCING HIGH PRESSURE.
SHIMON
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
649 PM CDT SAT APR 6 2013
.DISCUSSION...
259 PM CDT
THERE ARE NUMEROUS CHALLENGES WITH THE FORECAST AS THE PATTERN
TRANSITIONS TO A MORE ACTIVE ONE...BEGINNING WITH SHOWERS AND
SOME SPORADIC THUNDER THIS EVENING AND THEN CARRYING THROUGH THE
MIDDLE OF NEXT WEEK. IN ADDITION...THE LIKELY LOCATION OF THE
AREA RELATIVE TO SYNOPTIC FEATURES WILL ALLOW FOR TEMPERATURES TO
BE HEAVILY DEPENDENT ON CLOUD COVER AND RAIN...ALONG WITH LAKE
INDUCED COOLING AT LEAST A FEW OF THE UPCOMING SEVERAL DAYS.
NEAR TERM INTO TONIGHT...A FAST PACED BUT MORE AMPLIFIED UPPER
LEVEL PATTERN IS ESTABLISHED OVER THE CENTRAL U.S. THIS AFTERNOON
WITH A WELL-DEFINED UPPER WAVE ON WATER VAPOR ADVANCING EASTWARD
FROM WESTERN IA. A 1000 MB SURFACE LOW REFLECTION ACROSS SOUTHERN
MN HAS DEVELOPED AND HELPED TO ESTABLISH STRONG RETURN FLOW WITH
WIND GUSTS TO 40 TO 45 MPH AT SEVERAL SITES. THESE WINDS SHOULD
DIMINISH GRADUALLY THROUGH THE EVENING HOURS.
MOISTURE RETURN HAS STRUGGLED HOWEVER...BOTH AT THE SURFACE AND IN
THE DEEP LAYER PER OBSERVATIONS AND PWAT ANALYSIS AND IS A REASON
SHOWER COVERAGE IS LIKELY TO BE MORE LIMITED THAN IT COULD BE
GIVEN THE UPPER FORCING AHEAD OF THIS WAVE...AND IT WILL TAKE SOME
TIME FOR THE VERY DRY LOWER ATMOSPHERE TO SATURATE. A NARROW
CORRIDOR OF 700-900 MB MOISTURE TRANSPORT ALONG A MID-LEVEL JET
HAS STILL HELPED TO INCREASE ECHOES UPSTREAM DURING THE FIRST HALF
OF THE AFTERNOON AND THIS WILL LIKELY BE JUST ENOUGH TO CONTINUE
DOING SUCH WITH STEEPENING MID-LEVEL LAPSE RATES IN CONCERT WITH
THE NARROW MOISTURE CONVERGENCE. MOST OF THE HIGH-RES CONVECTIVE
ALLOWING MODELS PREDICT AN INCREASE IN CONVECTIVE-TYPE ECHOES
ACROSS NORTH CENTRAL IL BETWEEN 23Z AND 03Z SHIFTING EASTWARD AND
FADING SLOWLY THROUGH EARLY OVERNIGHT AS THE FRONT SHIFTS EAST.
WITH SEVERAL OF THESE GUIDANCE MEMBERS INDICATING HIGHER
REFLECTIVITY AND A NARROW CORRIDOR OF 200-400 J/KG OF MUCAPE PER
THE RAP ALONG THE FRONT...WOULD EXPECT A FEW STORMS WITHIN THE
GENERAL SHOWERS. HAVE ADAPTED HOURLY POPS THROUGH THIS EVENING
PERIOD OF THE FORECAST. AS PREVIOUS FORECAST DID KEEP MOST OF
TONIGHTS TEMPERATURE DROP AFTER THE FRONTAL PASSAGE FROM WEST TO
EAST.
SUNDAY...HIGH PRESSURE STILL LOOKS TO BRIEFLY PREVAIL FOR THIS
PERIOD. THE MOST NOTEWORTHY ASPECT ABOUT THIS IS IT LOOKS TO LINE
UP DOWN THE AXIS OF LAKE MICHIGAN BY MIDDAY AND ALLOW FOR A FAIRLY
STOUT LAKE BREEZE. THIS WILL BE AIDED BY THE FACT THAT
TEMPERATURES SHOULD MODERATE NICELY ON SUNDAY OVER LAND DUE TO
ONLY A SMALL WINDOW OF COLD AIR ADVECTION BEHIND THE FRONT TONIGHT
AND A DRY AIR MASS AND PREDICTED SUNSHINE DURING SUNDAY. THE
TEMPERATURE AND PRESSURE DIFFERENCES WITHIN A LIGHT WIND FIELD
SHOULD DRIVE A STRONG LAKE BREEZE...AND THE AFTERNOON TEMPERATURE
DROP FOR DOWNTOWN CHICAGO AND OTHER NEAR LAKE AREAS MAY BE AS MUCH
AS 15 DEGREES.
SUNDAY NIGHT AND MONDAY...AN ACTIVE WEST-TO-EAST PACIFIC JET OVER
120 KT AS SEEN ON HEMISPHERIC WATER VAPOR TODAY WILL DIG ITS WAY
INTO THE WESTERN U.S. WITH TROUGH DEVELOPMENT AND UPSTREAM
SOUTHWEST FLOW OVER THE MIDWEST. A LEAD IMPULSE IN THIS FLOW IS
WELL PREDICTED ON GUIDANCE TO PASS OVER THE AREA DURING LATE
SUNDAY NIGHT INTO MONDAY MORNING. THIS LOOKS TO TIGHTEN AN UPPER
LEVEL WARM FRONT AND ALLOW FOR SATURATED ISENTROPIC LIFT FOR RAIN
SHOWERS. ELEVATED INSTABILITY DOES INCREASE AS THE WARM NOSE
BUILDS IN WITHIN THE LOWER LEVELS...AND START THUNDER IN THIS
FORECAST PERIOD ITS TOO TOUGH TO DISCERN A PERIOD WHERE THERE
WOULD NOT BE A THUNDER CHANCE ALL THE WAY THROUGH WEDNESDAY NIGHT.
IN THE WAKE OF THIS LEAD IMPULSE HEIGHTS LOOK TO BUILD ON MONDAY
AS THE PRIMARY TROUGH DEVELOPS. ITS A LITTLE INTERESTING AS THERE
SHOULD BE A SURFACE WARM FRONT...POSSIBLY DIABATICALLY
ENHANCED...LAID OUT SOMEWHERE IN THE CENTRAL IL TO NORTHERN IL
REGION. THE ONLY THING IS WITH SHORT WAVE RIDGING HINTED AT THIS
FEATURE APPEARS TO BE FAIRLY BENIGN...BUT SOMETHING TO KEEP AN
EYE ON.
MIDWEEK...AN ACTIVE PERIOD HERE AS PROLONGED SURFACE CYCLOGENESIS
BEGINS OVER THE SOUTHERN PLAINS MONDAY NIGHT AND CONTINUES THROUGH
TUESDAY WITH THE SURFACE WAVE ADVANCING ENE ON WED. MODEL
GUIDANCE HAS COME INTO BETTER AGREEMENT WITH THIS...LATCHING MORE
ONTO AN EC SOUTHERN SOLUTION. HAVE CONTINUED TO LEAN THAT WAY WITH
THE FORECAST WHICH MEANS INHIBITING TEMPERATURES ON WHAT COULD BE
GIVEN 850MB TEMPERATURES CLIMBING TO 8C-12C...ESPECIALLY NORTH OF
I-80. WITH FLOW OFF THE LAKE TUESDAY AND WEDNESDAY DUE TO THE LOW
BEING SOUTHWEST OF THE AREA...TEMPERATURES NEAR THE LAKE WILL
REMAIN COOLER. ALSO THIS FORECAST PATTERN MEANS LIKELY SEVERAL
BOUTS OF PRECIP WITH THE PROXIMITY OF THE ELEVATED WARM/STATIONARY
FRONT. THE 06.12 GFS AND EC RUNS BOTH HAVE OVER TWO AND A HALF
INCHES OF RAIN FORECAST AREA WIDE FROM SUNDAY NIGHT THROUGH
THURSDAY. WHILE IT IS CHALLENGING TO FOCUS ANY WINDOW FOR
CATEGORICAL POPS...IT WOULD SEEM WEDNESDAY AND WEDNESDAY NIGHT
WOULD BE THE MOST FAVORED PERIODS FOR STRONGER DYNAMIC FORCING AND
POSSIBLY MORE ROBUST ELEVATED CONVECTION WITH THE LARGE SCALE
UPPER TROUGH MOVING EASTWARD. COOLING BEHIND THE FRONT LOOKS
SOMEWHAT STRONG AND THERE IS A POTENTIAL TO SEE SOME MIX IN THE
WAKE OF THE FRONT...BUT CONFIDENCE IS VERY LOW ON HOW THIS SYSTEM
WILL EVOLVE AS IT LIFTS OUT.
BEYOND...HAVE GONE PRIMARILY WITH A MODEL CONSENSUS AT THE END OF
NEXT WEEK AS THE UPPER FLOW PATTERN WORKS FROM BRIEFLY NORTHWEST
BACK TO WEST. TEMPERATURES SHOULD GRADUALLY MODERATE BUT
CONFIDENCE IS LOW ON PRECIP CHANCES AS THE PATTERN STILL LOOKS
DISTURBED.
MTF
&&
.FIRE WEATHER...
328 AM...EASTERLY FLOW HAS MAINTAINED MUCH DRIER AIR ACROSS THE
REGION AND EXPECT A SLOW RETURN OF LOW LEVEL MOISTURE ACROSS THE
AREA TODAY. IT APPEARS DEWPOINTS WILL INCREASE BACK INTO THE
40S...BUT PROBABLY NOT UNTIL LATE AFTERNOON ACROSS WESTERN IL AND
THE REST OF THE AREA THIS EVENING. THUS MINIMUM RH VALUES TODAY
WILL LIKELY BE IN THE 35-40 PERCENT RANGE AND COULD POSSIBLY DIP
INTO THE 30-35 PERCENT RANGE. WHILE THESE EXPECTED VALUES WILL
REMAIN ABOVE RED FLAG CRITERIA OF 25 PERCENT...SOUTHERLY WINDS ARE
EXPECTED TO QUICKLY INCREASE THIS MORNING WITH GUSTS AS HIGH AS 40
MPH FROM LATE MORNING THROUGH SUNSET WITH THE POTENTIAL FOR HIGHER
GUSTS. WHILE THERE COULD BE A FEW LIGHT SHOWERS OR SPRINKLES
TODAY...THE BEST TIMING FOR SHOWERS AND A FEW THUNDERSTORMS WILL
BE FROM LATE AFTERNOON THROUGH MID/LATE EVENING. TEN HOUR FUEL
MOISTURE DIPPED TO 8-9 PERCENT ON FRIDAY AND SIMILAR VALUES ARE
POSSIBLE TODAY. AS A RESULT...THERE WILL BE AN INCREASED FIRE
DANGER AND WHILE MEETING RED FLAG CRITERIA IS NOT EXPECTED...
CONDITIONS WILL NEED TO BE MONITORED THROUGH DAY. CMS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* 180-210 DEGREE WINDS THROUGH MID EVENING WITH SOME VARIABILITY
TO 220-230 AFTER APPROX 03Z. WINDS SHIFT WEST-NORTHWEST AFTER
06Z WITH COLD FRONTAL PASSAGE.
* FREQUENT WIND GUSTS AROUND 25 KT WITH SPORADIC GUSTS CLOSER TO
30 KT MAINLY THROUGH SUNSET...APPROACHING SHOWERS MAY PRODUCE 30
KT GUSTS THROUGH THE EVENING.
* STEADIER RAIN SHOWERS ARRIVING TOWARD 01Z WITH A CHANCE FOR
SHORT PERIOD OF TS AFTER ABOUT 03Z.
* POTENTIAL FOR LOW END MVFR CIGS OVERNIGHT.
* LIGHTER NORTHWEST WINDS SUNDAY WITH LAKE BREEZE TURNING WINDS
NORTHEAST THEN EAST LATER SUNDAY AFTERNOON.
MDB
//DISCUSSION...UPDATED 00Z...
GUSTY SOUTH-SOUTHWEST WINDS CONTINUE...MAINLY FROM CHICAGO LAND
EASTWARD AS LOW PRESSURE TRACKS ACROSS WEST-CENTRAL WISCONSIN AND
A COLD FRONT MOVES INTO EASTERN IOWA. GUSTS TO AROUND 25 KT
CONTINUE WITH SOME INFREQUENT GUSTS TO AROUND 30 KT STILL POPPING
UP BUT THE OVERALL TREND APPEARS TO BE DOWNWARD. SHOWER ARE MOVING
IN FROM THE WEST AHEAD OF THE FRONT AND THESE MAY ACT TO BRING
STRONGER GUSTS BACK AS THEY PASS. SOME THUNDERSTORMS HAVE
DEVELOPED JUST AHEAD OF THE FRONT TOWARDS KCID/KIOW AND THIS
ACTIVITY MAY EXPAND IN COVERAGE AS IT MOVES EASTWARD. WILL LEAVE
TS MENTION OUT OF THE TAFS FOR NOW WITH POTENTIAL TOO LOW TO
INCLUDE...30-40 PERCENT...BUT WILL WATCH TRENDS OVER THE NEXT HOUR
OR SO AND AMEND TO ADD IF NECESSARY. THE FRONT WILL CROSS THE AREA
LATER THIS EVENING AND BRING A SHIFT TO WEST-NORTHWEST WINDS WITH
SPEEDS DIMINISHING. THERE IS STILL SOME POTENTIAL FOR LOWERING
CIGS BEHIND THE FRONT TONIGHT BUT CONFIDENCE IS LOW. IF THEY DO
OCCUR THEN THEY WILL LIKELY BE LOW END MVFR OR POSSIBLY HIGH END
IFR FOR A TIME. WILL ALSO MONITOR THIS TREND OVER THE NEXT FEW
HOURS AND LOWER TAF CIGS IF NEEDED. RELATIVELY LIGHT NORTHWEST
WINDS WILL OCCUR SUNDAY MORNING BUT HIGH PRESSURE WILL MOVE
OVERHEAD SO LIGHT AND VARIABLE WINDS MAY PREVAIL BY AFTERNOON. A
LAKE BREEZE WILL LIKELY DEVELOP AND TURN WINDS NORTHEASTWARD
ACROSS THE CHICAGO AREA TERMINALS DURING THE AFTERNOON. LOW
PRESSURE WILL DEVELOP OVER THE CENTRAL HIGH PLAINS LATER SUNDAY
ALLOWING A STEADY EAST WIND TO DEVELOP ACROSS ALL AREAS SUNDAY
EVENING WHICH WILL TURN SOUTHEASTERLY INTO MONDAY. SHOWER AND
THUNDERSTORM CHANCES INCREASE EARLY SUNDAY NIGHT.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* HIGH CONFIDENCE IN WIND DIRECTION TRENDS THROUGH TONIGHT.
* MEDIUM-HIGH CONFIDENCE IN FREQUENT GUSTS TO AROUND 25 KT WITH
SPORADIC GUSTS TO 30 KT THROUGH SUNSET.
* HIGH CONFIDENCE IN PRECIP TIMING/DURATION...MEDIUM CONFIDENCE IN
TS POTENTIAL AND TIMING BUT CHANCE IS TOO LOW TO MENTION IN TAF
RIGHT NOW.
* LOW CONFIDENCE IN LOW MVFR CIG POTENTIAL OVERNIGHT.
* HIGH CONFIDENCE IN WIND TRENDS/LAKE BREEZE SUNDAY.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY...SHRA/TSRA LIKELY EARLY. MVFR/BRIEF IFR POSSIBLE EARLY.
TUESDAY THROUGH THURSDAY NIGHT...PERIODIC CHANCE FOR SHRA/TSRA.
PERIODIC MVFR CIGS/VSBY LIKELY WITH BRIEF IFR POSSIBLE.
FRIDAY...PROBABLE VFR.
MDB
&&
.MARINE...
241 PM CDT
LOW PRESSURE OVER SOUTHERN MINNESOTA THIS AFTERNOON IS LIFTING A
STRONG WARM FRONT ACROSS LAKE MICHIGAN TODAY. WINDS OVER THE LAND
ARE TOPPING OUT AROUND 35 KT THIS AFTERNOON WITH THESE GALES
EXTENDING INTO THE NEARSHORE WATERS WHERE A GALE WARNING REMAINS
IN EFFECT THROUGH THIS EVENING. HOWEVER...WITH TEMPERATURES
PUSHING 70 ACROSS NORTHERN ILLINOIS/INDIANA...VERY STABLE
CONDITIONS ARE SETTING UP OVER THE OPEN WATERS OF THE LAKE AND
SHOULD BE INHIBITING THE STRONGER GUSTS FROM REACHING THE LAKE
SURFACE. THE LOW WILL MOVE ACROSS NORTHERN LAKE MICHIGAN LATE
THIS EVENING WITH A TRAILING COLD FRONT PUSHING ACROSS THE LAKE
SHORTLY THEREAFTER WITH WINDS TURNING WESTERLY AND DIMINISHING.
ANOTHER LOW PRESSURE SYSTEM IS FORECAST TO MOVE INTO THE REGION
MIDWEEK...THOUGH MODELS CONTINUE TO STRUGGLE WITH TRACK AND TIMING
MAKING IT DIFFICULT TO PIN DOWN DETAILS REGARDING OVER THE LAKE.
CONTINUE TO FAVOR A FARTHER SOUTH SOLUTION SUPPORTED BY THE
CONSISTENT ECMWF...WHICH THE LATEST GFS HAS TRENDED TOWARDS.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...NEARSHORE WATERS UNTIL
10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
327 PM CDT FRI APR 5 2013
.SYNOPSIS...
ISSUED AT 109 PM CDT FRI APR 5 2013
12Z UA ANALYSIS HAS AN 850MB COLD FRONT FROM THE MID ATLANTIC STATES
INTO SOUTHEAST IOWA. A RIDGE RAN FROM SOUTHERN TEXAS TO LAKE
WINNIPEG IN CANADA AND A LLJ RAN FROM WEST TEXAS INTO WESTERN
NEBRASKA. SATELLITE TRENDS THROUGH MID DAY SHOW INCREASING MID AND
HIGH LEVEL CLOUDS ACROSS THE MID MISSISSIPPI VALLEY.
18Z SFC ANALYSIS HAS A LOW ALONG THE NE/SD BORDER NEAR KIEN WITH A
WARM FRONT INTO SOUTH DAKOTA AND THEN DROPPING SOUTH ALONG THE
MISSOURI RIVER. THE MODIFIED ARCTIC FRONT WAS INTO THE TENNESSEE
VALLEY AND SOUTHERN MISSOURI. DEW POINTS OVER THE GREAT LAKES WERE
IN THE TEENS AND 20S WITH 30S AND 40S IN THE CENTRAL AND SOUTHERN
PLAINS.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 109 PM CDT FRI APR 5 2013
THE DRY AIR IS HAMPERING THE DEVELOPMENT OF THE WAA PRECIPITATION
WING FROM MN INTO WISCONSIN. HOWEVER...RAP TRENDS WITH THE 850-700MB
CONDENSATION PRESSURE DEFICITS COMBINED WITH OVERALL
FORCING/CONVERGENCE AGREE QUITE NICELY WITH THE PRECIPITATION
APPROACHING THE MISSISSIPPI RIVER AROUND KMSP.
USING THIS AS A GUIDE THERE MAY BE SOME ISOLATED SHRA/SPRINKLES THAT
IMPINGE ALONG THE NORTHERN BORDER OF THE CWFA LATE THIS AFTERNOON
AND EARLY EVENING. ONCE THE FORCING SHIFTS NORTHEAST OF THE AREA BY
SUNSET...DRY CONDITIONS SHOULD THEN BE SEEN ACROSS THE AREA THROUGH
MIDNIGHT.
AFTER MIDNIGHT THINGS GET MORE INTERESTING.
THE MCS AND LIFT TOOLS ARE SUGGESTING CONVECTION DEVELOPING JUST
WEST OF I-35 IN THE STRENGTHENING LLJ BY MIDNIGHT. IF THE RAP TRENDS
ARE CORRECT THIS CONVECTION OF SHRA/TSRA SHOULD BE ON THE WESTERN
BORDER OF THE CWFA BY 09Z AND OVER THE WESTERN HALF OF THE CWFA BY
SUNRISE. THE COMBINATION OF THE LLJ AND STEEP MID LEVEL LAPSE RATES
SHOULD MAINTAIN THE CONVECTION AND ALSO RESULT IN WINDS INCREASING
DURING THE NIGHT.
THE ABOVE MENTIONED CONVECTION SHOULD EXIT THE CWFA BY LATE MORNING
AND THERE SHOULD BE A BRIEF PAUSE BEFORE NEW DIURNAL CONVECTION
DEVELOPS BY MID DAY AND CONTINUES THROUGH THE AFTERNOON HOURS.
LOW LEVEL LAPSE RATES BECOME QUITE STEEP AND THE WAA IS QUITE STRONG
ON SATURDAY WHICH WILL ALLOW THE HIGHER MOMENTUM AIR ALOFT TO MIX
DOWN. WINDS ARE EXPECTED TO PICK UP SIGNIFICANTLY BY LATE MORNING
AND CONTINUE THROUGH THE AFTERNOON.
THE SITUATION SATURDAY WILL NEED TO BE WATCHED CAREFULLY. THE
POTENTIAL DOES EXIST FOR A LOW END WIND ADVISORY FOR AREAS ALONG AND
EAST OF THE MISSISSIPPI FROM LATE MORNING THROUGH THE AFTERNOON
HOURS. ..08..
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 109 PM CDT FRI APR 5 2013
SATURDAY NIGHT AND SUNDAY SHOULD BE RELATIVELY QUIET AS A RIDGE OF
THE HIGH PRESSURE NOSES INTO THE REGION FROM THE NORTH. SOME LOW
CHANCE POPS WERE MAINTAINED EAST OF THE MISSISSIPPI RIVER SATURDAY
EVENING TO COVER ANY LINGERING SHOWERS BEHIND THE DEPARTING COLD
FRONT. BY SUNDAY MORNING THE COLD FRONT SHOULD BE STALLED OVER
CENTRAL OR NORTHERN MO WITH THE HIGH PRESSURE RIDGE OVER THE
NORTHERN CWFA. THIS SHOULD KEEP DRY WEATHER OVER MUCH OF THE AREA
THROUGH THE DAY SUNDAY. HOWEVER...KEPT SOME LOW POPS GOING IN THE
FAR SOUTH IN THE AFTERNOON WITH THE SURFACE FRONT JUST TO THE
SOUTH.
SUNDAY NIGHT A LOW AMPLITUDE S/W WILL MOVE THROUGH THE REGION
SPAWNING SHOWERS AND THUNDERSTORMS ALONG AND NORTH OF THE STALLED
FRONT. THE 00Z ECMWF WAS GENERATING SOME QPF WITH THIS FEATURE
OVER THE WESTERN CWFA AS EARLY AS SUNDAY AFTERNOON. BUT THE
FORCING SHOWN BY THE ECMWF WOULD SHOW MORE FAVORABLE CONDITIONS
OVER WESTERN IOWA BEFORE 00Z. OTHER THAN THE LOW CHANCE POPS IN
THE SOUTH SUNDAY AFTERNOON DISCUSSED ABOVE...THE SIGNIFICANT POPS
WERE LIMITED TO SUNDAY NIGHT WITH LIKELY/S OVER THEN ENTIRE AREA
WHEN AN AREA OF SHOWERS AND THUNDERSTORMS SHOULD MOVE EAST ACROSS
THE REGION AHEAD OF THE MID LEVEL SHORTWAVE. AT THIS POINT THE
SEVERE THUNDERSTORMS THREAT LOOKS NIL DUE LOW INSTABILITY AND
UNIMPRESSIVE FORCING. PW/S OVER THE AREA SUNDAY NIGHT ARE EXPECTED
TO BE AROUND AN INCH SUGGESTING GENERAL RAINFALL AMOUNTS OF A HALF
TO THREE QUARTERS OF AN INCH. THE HIGHER AMOUNTS WOULD FAVOR THE
SOUTH CLOSE TO THE SURFACE FRONT.
SHOWER AND THUNDERSTORM CHANCES WILL REMAIN OVER THE AREA MONDAY
THROUGH WEDNESDAY. THE LARGE TROF DEVELOPING OVER THE WESTERN U.S.
WILL CONTINUE TO FEED AMPLE MOISTURE INTO THE CENTRAL U.S. WHERE A
FRONTAL BOUNDARY WILL REMAIN. DURING THIS TIME FRAME...TUESDAY INTO
WEDNESDAY HAVE THE BEST CHANCE FOR SIGNIFICANT RAINS WHEN THE MODELS
SHOW A SURFACE LOW EJECTING NORTHEAST OUT OF THE SOUTHERN PLAINS
AHEAD OF THE UPPER TROF. EVEN THOUGH THIS FEATURE IS SHOWN BY ALL
MODELS THERE CONTINUES TO BE A VARIETY OF SOLUTIONS ON THE DETAILS
OF THE TRACK AND TIMING. THE 12Z ECMWF HAS SHIFTED THE TRACK
FURTHER SOUTHEAST SUGGESTING THE SIGNIFICANT RAINS WILL MISS THE
FORECAST AREA. THE GEM/GFS TRACK THE SYSTEM OVER IOWA TUESDAY OR
TUESDAY NIGHT SUPPORTING ANOTHER ROUND OF AT LEAST MODERATE RAINS.
GIVEN THE AMOUNT OF MOISTURE INPLACE AND A SURFACE BOUNDARY IN
THE AREA THE THREAT OF RAIN STILL LOOKS GOOD MONDAY THROUGH
WEDNESDAY WITH THE BIGGEST QUESTION NOW BEING THE RAINFALL
AMOUNTS. SO HAVE CONTINUED TO MENTION LIKELY POPS OVER MUCH OF THE
AREA FOR SHOWERS AND THUNDERSTORMS. THEN WEDNESDAY WHEN THE UPPER
TROF MOVES THROUGH...POPS WERE BACKED DOWN TO CHANCE CATEGORY.
COLDER AIR ADVECTING IN BEHIND THE TROF WEDNESDAY NIGHT COULD
PRODUCE A MIX OF RAIN AND SNOW ESPECIALLY NORTH. HOWEVER PRECIP
AMOUNTS SHOULD BE LIGHT MAKING IT UNLIKELY THAT ANY ACCUMULATION
WILL OCCUR. PRECIP COULD LINGER INTO THURSDAY AND THURSDAY NIGHT
WITH H8 TEMPS REMAINING BELOW ZERO. HOWEVER... TEMPERATURES NEAR
THE SURFACE SHOULD BE WARM ENOUGH FOR ALL RAIN.
DEEP SOUTHERLY FLOW AND HIGH MOISTURE LEVELS WILL KEEP
TEMPERATURES ON THE MILD SIDE EARLY NEXT WEEK...BUT BELOW NORMAL
READINGS WILL RETURN FOR THE END OF THE WEEK AS THE COLDER AIR
MOVES IN BEHIND THE DEPARTING UPPER TROF.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 109 PM CDT FRI APR 5 2013
VFR WX WILL BE SEEN THROUGH 06Z/06 WITH A POSSIBLE VCSH AT KDBQ
THROUGH SUNSET. AFT 06Z/06 MAINLY VFR WX IS EXPECTED TO CONTINUE
WITH POSSIBLE SHRA/TSRA AFFECTING ALL TAF SITES AFT 09Z/06. THE
POTENTIAL STILL EXISTS FOR LLWS IN THE 09Z-15Z/06 TIME FRAME. NEW
CONVECTION IS EXPECTED TO DEVELOP ACROSS IOWA/ILLINOIS AFT 15Z/06
AND BECOME MORE NUMEROUS AFT 18Z/06. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...08
SHORT TERM...08
LONG TERM...DLF
AVIATION...08
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1130 PM CDT THU APR 4 2013
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 306 PM CDT THU APR 4 2013
LIGHT SURFACE PRESSURE GRADIENT IS EVIDENT IN 20Z RAP ANALYSIS. THIS
LIGHT PRESSURE GRADIENT IS RESPONSIBLE FOR LIGHT WINDS WHICH ARE
EVIDENT IN SURFACE OBSERVATIONS ACROSS THE FORECAST AREA THIS
AFTERNOON. EXPECT THESE LIGHT WINDS TO EVENTUALLY SHIFT TO THE SOUTH
OVERNIGHT TONIGHT AS A SURFACE LOW COMES INTO FORMATION OVER THE
HIGH PLAINS. SOUTHERLY WINDS WILL INCREASE THROUGH THE DAY ON FRIDAY
TO AROUND 20 TO 25 MPH...WITH GUSTS TO AROUND 30 MPH. DEEP MIXING
WILL CAUSE ALLOW FOR LOW LEVEL WINDS AROUND 850 MB TO COME TO THE
SURFACE...WHICH MAY BRING WARMER/DRYER CONDITIONS AND STRONGER WIND
GUSTS. THIS WILL HAVE FIRE WEATHER IMPLICATIONS...WHICH ARE
DISCUSSED IN THE FIRE WEATHER DISCUSSION BELOW. AT THIS TIME EXPECT
VERY HIGH FIRE DANGER FOR MOST OF THE AREA THROUGH THE DAY ON
FRIDAY.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 306 PM CDT THU APR 4 2013
FRIDAY NIGHT THROUGH SUNDAY...FRIDAY NIGHT LEE SIDE LOW PRESSURE
DEEPENS OVER THE HIGH PLAINS INCREASING THE PRESSURE GRADIENT
ACROSS THE AREA. THEREFORE THE WINDS WILL CONTINUE TO BE GUSTY
THROUGH THE OVERNIGHT HOURS ESPECIALLY ACROSS EASTERN KANSAS. THIS
WILL KEEP LOW TEMPERATURES FRIDAY NIGHT IN THE LOW 50S. A
SOUTHWESTERLY LOW LEVEL JET INCREASES FRIDAY NIGHT BRINGING
LIMITED MOISTURE TO THE REGION. MEANWHILE A SHORTWAVE ADVANCES
EASTWARD INTO NEBRASKA AND EVENTUALLY IOWA ON SATURDAY. IT APPEARS
THAT THE STRONGER LIFT ASSOCIATED WITH THE WAVE WILL BE NORTH OF
THE AREA FRIDAY NIGHT AND SATURDAY MORNING. THERE IS SLIGHT CHANCE
OF SOME WEAK LIFT EXTENDING SOUTH INTO KANSAS SO COULD NOT RULE
OUT AN ISOLATED SHOWER FRIDAY NIGHT. A WEAK COLD FRONT ASSOCIATED
WITH THE WAVE WILL PUSH SOUTHWARD THROUGH THE AREA DURING THE DAY
ON SATURDAY SHIFTING THE WINDS TO THE NORTH. THE FRONT WILL
RETREAT BACK TO THE NORTH ON SUNDAY AND SETS UP SOMEWHERE IN
NORTHEAST KANSAS. A WEAK SHORTWAVE EMBEDDED IN THE ZONAL MID LEVEL
FLOW PROGRESSES EASTWARD ACROSS KANSAS DURING THE DAY PROVIDING
LAGER SCALE LIFT. SOUTHERLY LOW LEVEL FLOW WILL INCREASE THE
MOISTURE RETURN ACROSS THE AREA AS ML CAPE VALUES APPROACH 500
J/KG AIDING IN THUNDERSTORM DEVELOPMENT. MID LEVEL FLOW ALSO
INCREASES SUNDAY WITH 0-6 KM BULK SHEAR VALUES AROUND 40 KTS WHICH
SUPPORTS THE CHANCE OF STRONGER ORGANIZED THUNDERSTORMS SUNDAY
AFTERNOON AND OVERNIGHT.
EXTENDED FORECAST (SUN NIGHT-THURS)...AN ACTIVE PATTERN SETTING UP
THROUGH THIS PERIOD...AND SEVERE WEATHER APPEARS INCREASINGLY
LIKELY....HOWEVER TIMING AND PLACEMENT REMAINS SOMEWHAT
UNCERTAIN. SUNDAY NIGHT THE GFS AND A SOMEWHAT FASTER EC BRING A
SHORTWAVE OVER THE WARMFRONT PROGGED E/W OVER OUR AREA...WITH THE
EC HOLDING THE FRONT FARTHER SOUTH THAN THE GFS. ENOUGH CAPE AND
SHEAR PRESENT THAT SOME OF THE STORMS OVERNIGHT COULD BRING HAIL.
THE ENSUING WEATHER FOR MONDAY WILL BE DEPENDENT ON HOW FAR NORTH
THE WARMFRONT LIFTS DURING THE DAY. EC AND GFS BOTH BREAK OUT
CONVECTION NEAR THE BOUNDARY AND LESS SO IN THE WARM SECTOR MONDAY
EVENING THROUGH THE MORNING HOURS ON TUESDAY. SEVERE WEATHER
POTENTIAL CONTINUES TO INCREASE INTO TUESDAY AND TUESDAY
AFTERNOON AS WESTERN TROF APPROACHES...AND SHEAR AND INSTABILITY
ALSO INCREASE AND MOVE NORTH ACROSS THE CWA WITH THE WARM SECTOR.
DIFFERENCES INCREASE BEYOND TUESDAY AS GFS MOVES THE COLDFRONT
THROUGH QUICKLY WITH EC DROPPING A CLOSED UPPER LOW ACROSS EASTERN
KANSAS AND THE FRONT MOVING THROUGH WEDNESDAY EVENING. WHILE
WED/THURS WILL BRING A COOL END OF THE WEEK...MUCH UNCERTAINTY
WITH PRECIP AMOUNTS AND TYPES. 67
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1129 PM CDT THU APR 4 2013
VFR EXPECTED THROUGH THE PERIOD. WINDS WILL BE THE MAIN CONCERN
FOR THE FORECAST AS THEY WILL BEGIN TO INCREASE BY 16Z TO AROUND
16 KTS WITH GUSTS AS HIGH AS 29 KTS IN THE AFTERNOON. PRESSURE
GRADIENT WILL REMAIN TIGHT EVEN AFTER SUNSET WHERE THE GUSTS MY
SUBSIDE AFTER 02Z...BUT WINDS WILL REMAIN AROUND 15-19 KTS.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...LEIGHTON
LONG TERM...67
AVIATION...53
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
746 PM EDT SAT APR 6 2013
.SYNOPSIS...
HIGH PRESSURE AND DRY WEATHER WILL CONTINUE OVERNIGHT. A FRONTAL
SYSTEM WILL APPROACH ON SUNDAY BRINGING SCATTERED SHOWERS. THE
FRONT WILL LINGER NEARBY INTO NEXT WEEK WITH A CONTINUED CHANCE OF SHOWERS.
&&
.NEAR TERM /THROUGH SUNDAY/...
630 PM UPDATE...TEMPERATURES DROPPING EARLY THIS EVENING WITH
CONTINUED LOW DEW POINTS. HRRR SUGGESTING NO LOW CLOUDS OVERNIGHT
WITH LACK OF LOW LEVEL MOISTURE AND ONLY SCATTERED TO BROKEN MID
DECK AND CIRRUS. WILL ADJUST TEMPERATURE TREND AND LOWER MINIMUMS
SLIGHTLY GIVEN DEW POINTS AND EXPECTED CLOUDS.
PREVIOUS DISCUSSION FOLLOWS...
DEW POINTS HAVE LARGELY RUN IN THE SINGLE DIGITS THROUGH MOST OF
THE AFTERNOON TODAY...WITH A FEW LOCATIONS JUST SOUTH OF OUR AREA
IN WEST VIRGINIA RUNNING WELL BELOW ZERO. THE RESULT HAS BEEN AN
EXTREMELY DRY DAY ACROSS THE FORECAST AREA WITH ONLY CIRRUS
GENERALLY FILTERING THE SUN. AS THE NIGHT ENSUES...MORE
SIGNIFICANT LARGE SCALE LIFT AND MOISTURE SLOWLY ENCROACHES FROM
THE WEST...HOWEVER GIVEN THAT IT HAS FAILED TO EVEN REACH THE
MIDDLE AND UPPER MISSISSIPPI VALLEY THIS AFTERNOON...AND THE FACT
THAT THE BEST UPPER LEVEL RH FIELDS FAVOR CIRRUS AND MID-CLOUD
DEVELOPMENT LARGELY NORTH OF THE AREA...THE NIGH SHOULD BE DRY
ALMOST EVERYWHERE IN THE FORECAST AREA...WITH ONLY HIGH CLOUDS
FILTERING THE MOON OUT FROM TIME TO TIME. DUE TO THE RIDICULOUSLY
DRY IN SITU BOUNDARY LAYER AND LACK OF SIGNIFICANT LAYER RH COMING
INTO THE FORECAST AREA BEFORE MORNING...ALL POPS WERE REMOVED FOR
THE NIGHT.
WITH OUR EXTREMELY DRY BOUNDARY LAYER THIS AFTERNOON AND LESS
SIGNIFICANT CLOUD EXPECTATIONS...LOW TEMPERATURES WERE CUT A BIT
OVERNIGHT...HOWEVER IT WILL NOT BE ANYWHERE NEAR AS COLD AS RECENT
NIGHTS. ADDITIONALLY...SURFACE FLOW SHOULD SLOWLY TURN
SOUTHERLY...WHICH WILL ALSO WORK TO LIMIT THE DIURNAL FALL
POTENTIAL. FRIES
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
NAM AND GFS SOLUTIONS HAVE COME INTO DECENT AGREEMENT WITH A
FRONTAL PASSAGE THROUGH THE AREA ON SUNDAY. MOISTURE ALONG AND
AHEAD OF THE FRONT IS RATHER LIMITED AS IT MOVES INTO OUR BONE DRY
ENVIRONMENT...SO QPF VALUES WERE CUT BACK QUITE A BIT.
HOWEVER...DECENT FRONTOGENETICAL FORCING AS WELL AS SOME SHALLOW
INSTABILITY SHOULD BE ENOUGH TO GENERATE A LINE OF LIGHT SHOWERS
ALONG THE FRONT AS IT MOVES THROUGH SUNDAY.
THE MODEL CONSENSUS FAVORS A STALLING OF THE FRONT ACROSS NORTHERN
WEST VIRGINIA SUNDAY NIGHT BEFORE IT TURNS NORTHWARD AS A WARM
FRONT ON MONDAY. THIS BRINGS PROGRESSIVELY WARMER AIR INTO THE
AREA EARLY NEXT WEEK. POPS FOR SHOWERS WERE CONTINUE THROUGH
MONDAY NIGHT BEFORE BEING INCREASED AGAIN ON TUESDAY. WHILE
AGREEMENT ON THE PLACEMENT OF THE FRONT BY TUESDAY BECOMES LESS
PRONOUNCED...THE ECMWF/GFS/NAM ALL LIKE THE IDEA OF TRACKING A
WAVE DOWN THE FRONT BY THE AFTERNOON HOURS. THIS WOULD ADD
ADDITIONAL LIFT AND SHEAR ALONG THE FRONTAL ZONE. IN
ADDITION...SYNOPTIC LIFT MAY BE ENOUGH TO OVERCOME A MODERATELY
STRONG CAP ALONG THE FRONTAL BOUNDARY. IF THIS OCCURS...A FEW
HUNDRED J/KG OF CAPE ARE PRESENT BY TUESDAY THAT DOES MANAGE TO
REACH UP TOWARD THE -30C ISOTHERM. THIS WOULD YIELD A CHANCE OF
THUNDERSTORMS BY TUESDAY AFTERNOON. THUNDERSTORMS WERE THUS ADDED
TO THE FORECAST FOR TUESDAY AFTERNOON...HOWEVER REMAIN OUT OF THE
FORECAST BEFORE THAT TIME DUE TO SHALLOW INSTABILITY AND CAPPING.
FRIES
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
OVERALL...CONFIDENCE IN EXTENDED FORECAST IS LOWER THAN
NORMAL...SIMILAR TO YESTERDAY. FRONT WILL STILL BE HUNG UP TUESDAY
NIGHT THROUGH WEDNESDAY NIGHT...PROBABLY TO THE NORTH OF THE REGION.
ALTHOUGH COLD FRONT WILL LIKELY BEGIN TO CROSS THE REGION ON
THURSDAY...GFS/ECMWF CANNOT DECIDE WHETHER THE COLD FRONT WILL TAKE
24 OR 48 HOURS TO PUSH ALL THE WAY THROUGH. HAVE BUMPED UP POPS TO
LIKELY THURSDAY NIGHT...BUT OTHERWISE MADE LITTLE CHANGES TO POPS OR
TEMPERATURES. TEMPERATURES SHOULD BE ABOVE NORMAL
WED/THURS...DROPPING TO BELOW NORMAL FRI/SAT.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
EXPECT SCT TO BKN VFR MID AND HIGH CLOUDS THIS EVENING. LOW LEVEL
WIND SHEAR IN THE TAFS OVERNIGHT WITH LOW LEVEL JET DEVELOPING
FROM THE SOUTHWEST ALOFT WHILE SURFACE LOOKS TO DECOUPLE A BIT
WITH A LIGHTER SOUTH TO SOUTHEAST WIND. HAVE GONE WITH
SHOWERS/SPRINKLES MOST LOCATIONS BEGINNING LATE MORNING NORTH TO
LATE AFTERNOON SOUTH. FRONT CROSSING THE REGION BETWEEN 15Z- 21Z.
WHILE THERE IS SOME MODEL GUIDANCE THAT CIGS COULD DROP TO MVFR IN
SHOWERS...BELIEVE GENERAL VFR IS STILL BEST FORECAST.
.OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/...
THE BOUNDARY SHOULD SHIFT SOUTH OF THE REGION SUNDAY NIGHT...THEN
BE PULLED NORTHWARD ONCE AGAIN ON MONDAY AS LOW PRES DIGS ACRS THE
GREAT LAKES. FRONT POSITIONING IS QUESTIONABLE THROUGH MUCH OF THE
WEEK...SO OCCASIONAL RESTRICTIONS SHOULD BE ANTICIPATED.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
138 PM EDT FRI APR 5 2013
.UPDATE...
ISSUED AT 1254 PM EDT FRI APR 5 2013
GIVEN LARGER SPRING STORM IS QUICKLY ON THE APPROACH...THOUGHT
IT WOULD BE GOOD TO PROVIDE UPDATE IN TERMS OF EXPECTED STORM
INTENSITY/PTYPE AND HEADLINES.
SFC TROUGH THAT EVENTUALLY WILL DEVELOP INTO CLOSED OFF LOW OVER
WESTERN LAKES LATER SATURDAY IS CURRENTLY ALLIGNED FROM SOUTHERN
PORTIONS OF ALBERTA AND SASKATCHEWAN INTO NORTHERN US ROCKIES. 12Z
RAOBS AND WV LOOP SHOW H5 TROUGH PUSHING OUT OF WA/OR...WHILE TROUGH
AT H85 AND H7 IS CLOSER TO THE MAIN SFC LOW. SNOW IS AS CLOSE AS
ND/SASKATCHEAN BORDER ON EDGE OF H8-H7 FRONTOGENESIS. NAM/GFS AND
REGIONAL GEM INITIALIZED LARGER SCALE FEATURES WELL BUT DIFFER ON
CRITICAL THERMAL DETAILS FOR SATURDAY.
OVERALL...AT THE LEAST...WINTER WEATHER ADVISORIES WILL BE POSTED
LATER THIS AFTN FOR ALL OF CWA. ALREADY COORD WITH DLH AND GRB WHICH
HAVE ADVYS UP AND ALSO WITH APX. SOME AREAS MAY NEED WARNINGS BUT IT
WILL DEPEND ON WHERE PTYPE REMAINS MOSTLY SNOW FOR THE EVENT.
UNFORTUNATELY...THIS IS NOT CLEAR CUT EVEN WITHIN 24 HRS AS SOME
MODELS /GFS AND UKMET/ ARE PRETTY WARM AT H85-H8 DURING THE AFTN
HOURS ON SATURDAY /UP TO +3C AT H85/ WHILE NAM/REGIONAL GEM AND 00Z
ECMWF ARE NOT AS WARM. THIS IS ESPECIALLY TOUGH CONSIDERING THEY ARE
FAIRLY SIMILAR WITH H85/H7/H5 FEATURES. AS WOULD BE EXPECTED WITH
THERMAL PROFILES...GFS/SREF ARE SLIGHTLY FARTHER NORTH WITH SFC LOW.
GIVEN STEEP LAPSE RATES IN MID-LEVELS FEEDING INTO AREA OF
PRECIPITATION OVER UPR MICHIGAN...THERE IS ALSO CONCERN CONVECTION
WILL MODULATE INTENSITY AND PTYPE OVER THE CWA.
AT THIS POINT...FAR SOUTH SEEMS PRETTY CERTAIN TO SEE MAINLY RAIN BY
SATURDAY AFTN SO SNOW AMOUNTS WILL ULTIMATELY BE HELD DOWN FROM IMT
TO ESC AND CERTAINLY SOUTH TO MNM. GOGEBIC AND IRON TOUGH CALL AS
INITIAL WARM NOSE MAY RESULT IN MIX OF SLEET/SNOW AND EVEN RAIN LATE
TONIGHT INTO SATURDAY MORNING BUT PRECIP WOULD TURN BACK TO MAINLY
SNOW ON SATURDAY AFTN AS H7-H5 TROUGH/PRIMARY SHORTWAVES/LARGER
SCALE LIFTING AND DYNAMIC COOLING ARRIVE. MUCH MORE OF A QUESTION
IN THE TIER OF COUNTIES NORTH...FROM ONTONAGON/SOUTHERN HOUGHTON
THROUGH BARARA/MARQUETTE AND EAST TO ALGER/SCHOOLCRAFT/LUCE COUNTY.
IN THESE AREAS INITIAL SHOT OF PRECIP SATURDAY MORNING SHOULD REMAIN
MOSTLY SNOW AS THINK THAT DYNAMIC COOLING TIED TO STRONG H8-H5 FGEN
OFFSETS SHALLOW WARM LAYER H85-H8 AROUND +1C. INITIAL SURGE OF
PRECIP DRIVEN BY 295-305K /H85-H5/ ISENTROPIC ASCENT AND DIVERGENCE
ALOFT FROM LARGE JET STREAK OVER ONTARIO INTO QUEBEC COULD END AS
MIX OF SLEET/SNOW AS DYNAMIC COOLING FADES BTWN 15Z-18Z. STILL MANY
DETAILS TO BE SORTED OUT BUT WINTER WEATHER STATEMENT WITH FINAL
HEADLINE DECISIONS WILL BE OUT LATER THIS AFTN.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 622 AM EDT FRI APR 5 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW CONFLUENT NW FLOW
ALF OVER THE GRT LKS DOWNSTREAM OF RDG OVER THE ROCKIES. AT THE
LLVLS...THE CWA IS DOMINATING BY A NW FLOW OF COLDER AIR IN THE WAKE
OF THU COLD FROPA AND AHEAD OF SFC HI PRES NEAR LK WINNIPEG. SINCE
THE 00Z INL RAOB SHOWED A VERY DRY...INVERTED V PROFILE AND RECENT
SFC OBS INDICATE FAIRLY LARGE SFC T/TD SPREADS...SKIES ARE MOCLR
OVER UPR MI AS OF 06Z. BUT THE 00Z YPL RAOB DEPICTED A SOMEWHAT
MOISTER...BUT STILL WELL MIXED...SFC-H85 T/TD PROFILE WITH AN H85
TEMP DOWN TO -16C. FARTHER UPSTREAM...A SHRTWV IS MOVING INTO THE
PAC NW. WAD MID/HI CLDS WELL E OF THIS DISTURBANCE ARE SPREADING
INTO THE NRN PLAINS.
TODAY...ALTHOUGH SKIES ARE MOCLR EARLY THIS MRNG...SUSPECT SOME LK
CLDS/EVEN SOME -SHSN MIGHT DVLP OVER AREAS E OF MQT AS THE
MOISTER...COLDER AIRMASS SHOWN ON THE 00Z YPL RAOB WITH H85 TEMPS AS
LO AS -15C IMPACT THIS PART OF THE CWA. OVER THE W HALF...THE VERY
DRY 00Z INL RAOB IS MORE REPRESENTATIVE OF THE SOURCE AIRMASS. SO
REMOVED POPS/DIMINISHED FCST CLDS IN THIS AREA. BUT EVEN OVER THE
E...GENERALY ACYC NATURE OF THE FCST LLVL FLOW AS WELL AS HIER SFC
T/TD DEPRESSIONS EVEN FARTHER E N OF LK SUP SUG ANY SN ACCUMS WL BE
NEGLIGIBLE IF SHSN DO FORM AT ALL. WITH DAYTIME HEATING/LARGE SCALE
SUBSIDENCE AS SFC HI BLDS OVER THE W HALF OF THE CWA BY 18Z...EXPECT
ANY LES OVER THE E TO DIMINISH BY NOON. DIURNAL CU/SC THAT DVLP WITH
DAYTIME HEATING/MIXING UNDER LINGERING H85 THERMAL TROF WL TEND TO
DIMINISH OVER AT LEAST THE W AND CENTRAL WITH MORE EMPHATIC DRYING/
QUICKER TRANSITION TO MORE ACYC FLOW...BUT SC MAY LINGER LONGER OVER
THE E WHERE THE H85 TEMPS WARM ABV -10C ONLY TOWARD 00Z. MIXING TO
H85 AS OBSVD ON UPSTREAM 00Z RAOBS YIELDS HI TEMPS IN THE UPR 30S/
LO 40S OVER THE W...BUT ONLY 30 TO 35 OVER THE CNTRL AND E WHERE
LOWER H85 TEMPS LINGER LONGER. WITH WEAKER PRES GRADIENT ARRIVING
WITH SFC HI CENTER...LK BREEZES WL MAINTAIN LOCAL COOLING NEAR THE
SHORES. SOME HI CLDS WL ARRIVE OVER THE W IN THE AFTN WELL IN
ADVANCE OF PAC NW SHRTWV MOVING THRU THE NRN ROCKIES.
TNGT...AS SHRTWV MOVES THRU THE NRN PLAINS AND ASSOCIATED SFC LO
SHIFTS TO SW MN BY 12Z SAT...EXPECT THICKENING CLDS IN THE DVLPG WAD
PATTERN BTWN THE DEPARTING HI AND INCOMING LO PRES. VIGOROUS
ISENTROPIC ASCENT SHOWN ON THE 280-295K ISENTROPIC SFCS IS FCST TO
SPREAD W-E ACRS THE CWA AND SLOWLY SATURATE THE VERY DRY ANTECEDENT
LO-MID LVLS. FAVOR THE SOMEWHAT SLOWER 00Z NAM/CNDN AND 12Z ECMWF
FOR TIMING LEADING EDGE OF PCPN TIED TO H5-7 FGEN AXIS OVER THE
GFS...WHICH APPEARS TO GENERATE PCPN TOO DEEP INTO THE LINGERING DRY
AIR. THESE FAVORED MODELS INDICATE PCPN WL REACH A LINE FROM
MUNISING-MANISTIQUE BY 12Z SAT... SO RESTRICTED CATEGORICAL POPS TO
THE W OF THAT AXIS. FAVORED MODEL QPF INDICATES 2 TO 3 INCHES OF SN
OVER THE SW CWA BY 12Z SAT EVEN THOUGH RATHER NARROW/HI DGZ CENTERED
ARND 15K FT WL LIMIT SN/WATER RATIOS. EXPECT THE LOWEST MIN TEMPS
OVER THE INTERIOR E...WHERE THE CLDS WL ARRIVE LATEST AND WINDS BE
LGT IN THE EVNG TO ALLOW FOR GOOD RADIATIONAL COOLING. FOLLOWED A
NON-DIURNAL CURVE WITH TEMPS FALLING TO THE LOWEST LVL FAIRLY
EARLY...THEN STEADY OR SLOWLY RISING.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 622 AM EDT FRI APR 5 2013
MAIN FCST CONCERNS FOCUS ON SYSTEM FOR SATURDAY...PTYPE
CONCERNS...POSSIBLE HEADLINES AND SNOW AMTS.
ACTIVE SHORTWAVE NOW MOVING IN OFF THE PACIFIC NW AS NOTED ON WATER
VAPOR LOOP IS EXPECTED TO TRACK DUE E...REACHING THE WRN GREAT LAKES
SAT. WHILE MODELS HAVE COME INTO BETTER AGREEMENT WITH TRACK/TIMING
OF SHORTWAVE AND ASSOC SFC LOW SOME IMPORTANT MODEL DIFFERENCES
REMAIN IN THERMAL FIELDS. CONFIDENCE IS HIGH THAT ALL OF THE FCST
AREA WILL SEE PCPN...SO HIGH CATEGORICAL POPS WILL BE PAINTED ACROSS
THE CWA. RIGHT ENTRANCE OF UPPER JET ASSOCIATED WITH ERN CANADA TROF
WILL PROVIDE LARGER SCALE ENHANCEMENT TO UPWARD MOTION...AS A FAIRLY
VIGOROUS FRONTOGENESIS SIGNATURE WILL AID PCPN INTENSITY ON THE
SMALLER SCALE. IT APPEARS THAT THERE MAY BE 2 PERIODS OF FGEN
FORCING...ONE INITIALLY LATE TONIGHT/SAT MORNING THAT
TRANSLATES ACROSS THE AREA...THEN A SECOND SAT AFTN/EVENING THAT
WOULD FAVOR CNTRL/ERN UPPER MI FOR HEAVIER PCPN. WITH MIXING RATIOS
OF 4-5G/KG AND CLOSE TO 12HRS OF ASCENT...THERE COULD BE 6 TO
POSSIBLY AS MUCH AS LOCALLY 8-10 INCHES OF HVY/WET SNOW ALONG THE
AXIS OF HEAVIEST PCPN WHERE PTYPE IS ALL SNOW. SO...DETERMINING THE
CONFIGURATION OF PTYPES WILL BE CRITICAL. IS STILL APPEARS THAT
PTYPE WILL BE ALL SNOW ACROSS THE FCST AREA AS PCPN DEVELOPS TONIGHT
...AND THAT SNOW MAY FALL LONG ENOUGH SO THAT A FEW INCHES OF SNOW
ACCUMULATE EVEN IN AREAS THAT SEE A MIX OR CHANGE TO RAIN DURING THE
DAY SAT. DURING THE DAY SAT...UNCERTAINTY GROWS IN HOW FAR N WARMING
OCCURS. THE 06Z GFS AND NAM BRINGS 0C 850MB ISOTHERM AND CRITICAL
1000-850MB THICKNESS FAR ENOUGH N SO THAT PERHAPS ONLY WEST AND NW
UPPER MI REMAINS MOSTLY SNOW SAT AFTN/EVENING. THE LOCAL WRF-ARW AND
REG-GEM ARE FARTHER S WITH THESE TEMP PARAMETERS AND ARE GENERALLY
MORE IN LINE WITH THE ECMWF...SUGGESTING MUCH OF NRN UPPER MI WILL
STAY MOSTLY SNOW. FCST SOUNDINGS STILL SUGGEST THAT A NARROW ZONE OF
SLEET IS ALSO POSSIBLE IN THE TRANSITION ZONE BTWN MOSTLY SNOW NORTH
TO MOSTLY RAIN SOUTH ON SAT. CONSIDERED ISSUING A WATCH FOR SOME THE
NRN COUNTIES IN SWATH OF EXPECTED HEAVIER PCPN WHERE PTYPE WILL BE
MOSTLY SNOW...BUT GIVEN CONTINUED UNCERTAINTIES WITH PTYPE AND
ULTIMATE ACCUMS DECIDED TO KEEP AN SPS GOING HIGHLIGHTING THE
POTENTIAL FOR VERY HVY/WET SNOW THAT WILL BE DIFFICULT TO
SHOVEL/PLOW AND WILL LEAD TO VERY DIFFICULT TRAVEL CONDITIONS.
ON SUN...SFC HIGH PRES WILL NOSE INTO THE UPPER LAKES BEHIND
SYSTEM...BRINGING AN INFLUX OF DRIER AIR. DAYTIME TEMPS SHOULD
RECOVER WELL INTO THE 30S/LWR 40S IN THE AFTN WITH SOME INCREASE IN
SUNSHINE DURING THE DAY.
FCST FOR MON THRU THU REMAINS UNCERTAIN. MUCH OF THE FCST WILL HINGE
ON THE STRENGTH OF THE LINGERING ERN CANADA TROF UNDER THE WEAKENING
NEGATIVE AO/NAO PATTERN. OTHER THAN A SHOWING A WEAK NRN PLAINS
SHORTWAVE MOVING THROUGH THE AREA LATE SUNDAY NIGHT INTO
MONDAY...THE LATEST ECMWF IS SIMILAR TO RECENT RUNS SHOWING A
STRONGER AND MORE PERSISTENT ERN CANADIAN TROF WHICH KEEPS A DRIER
WNW FLOW ACROSS THE UPPER LAKES FOR THE EARLY PART OF NEXT WEEK.
THIS IDEA ALSO WOULD GO ALONG WITH THE GENERAL PERSISTENT PATTERN
WHICH HAS DOMINATED THE REGION FOR THE LAST SEVERAL WEEKS...ALTHOUGH
IT REMAINS TO BE SEEN HOW LONG PATTERN WILL PERSIST GIVEN EXPECT
WEAKENING OF HIGH LATITUDE BLOCKING. THE 12Z ECMWF DOES FINALLY
BRING PCPN INTO THE FCST AREA ON WED NIGHT AND THU...MAINLY IN FORM
OF SNOW...AS MAIN PIECE OF ENERGY FROM WRN CONUS TROF EJECTS NE
TOWARD THE GREAT LAKES. MEANWHILE...THE LATEST 00Z RUN OF THE GFS
QUICKLY WEAKENS THE ERN CANADIAN TROF AND PUSHES IT EAST ALLOWING
FOR A STRONG SRN STREAM SHORTWAVE TO EJECT TOWARD THE UPPER GREAT
LAKES FM BASE OF WRN CONUS TROF. THE GFS SHOWS 8H TEMPS RISING TO
10-12C BY TUE NIGHT INTO WED ACCOMPANIED BY A SLUG OF GULF MOISTURE
(250-300 PCT OF NORMAL PWAT VALUES) WHICH WOULD YIELD A THREAT OF
MODERATE TO HEAVY RAIN TO THE FCST AREA TUE NIGHT INTO WED. THE 12Z
GEM-NH GENERALLY LENDS MORE SUPPORT TO ECMWF SOLN ALTHOUGH IT ALSO
TENDS TO BREAK DOWN ERN CANADIAN TROF QUICKER THAN ECMWF. GIVEN
CONSIDERABLE MODEL UNCERTAINTY...WILL CONTINUE SIMPLE CONSENSUS
APPROACH TO FCST KEEPING ONLY SCHC POPS FOR MON INTO TUE THEN
INCREASE POPS TO 30-40 PCT CHC FOR WED AND THU WITH THE IDEA THAT
ERN CANADA TROF WILL WEAKEN ALLOWING FOR MORE ENERGY FROM WRN CONUS
TROF TO REACH UPPER GREAT LAKES. TEMPS SHOULD REMAIN BLO NORMAL THRU
THE PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 135 PM EDT FRI APR 5 2013
HIGH PRESSURE MOVING OVER THE AREA THIS AFTERNOON AND EVENING SHOULD
KEEP VFR CONDITIONS AT EACH TAF SITE. LATE TONIGHT THROUGH SATURDAY
A LOW PRESSURE SYSTEM OVER THE NORTHERN PLAINS WILL SHIFT EASTWARD
INTO THE AREA INTRODUCING A CHANCE OF SNOW TO ALL TAF SITE AS WELL
AS A MIXTURE OF SLEET AT THE IWD TAF SITE. THE BETTER MOISTURE AND
LIFT WILL MOVE INTO THE IWD SITE AROUND 06Z TONIGHT...REACHING THE
SAW SITE BY 10Z. AS THE BETTER LIFT/MOISTURE PASSES OVER THE TAF
SITES EXPECT SNOW TO INTENSIFY EFFECTIVELY REDUCING VISIBILITY TO
IFR CONDITIONS. IT WOULD NOT BE OUT OF THE QUESTION FOR VISIBILITY TO
FALL BELOW 2SM OVERNIGHT AND SATURDAY WITHIN THE HEAVIER SNOW BANDS.
RAISED VISIBILITY AT THE IWD TAF SITE FROM EARLIER THINKING AS SLEET
MAY HELP TO KEEP VISIBILITY A BIT HIGHER. HIGH CLOUDS WILL START TO
STREAM IN THIS AFTERNOON BEFORE DEEPER MOISTURE MOVES IN OVERNIGHT
REDUCING CEILING HEIGHTS TO 1500FT OR LOWER THROUGH THE DAY SATURDAY.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 622 AM EDT FRI APR 5 2013
NW WINDS UP TO 25 KTS EARLY THIS MORNING OVER THE E HALF WILL
DIMINISH STEADILY TODAY AS HI PRES IS FORECAST TO BUILD OVER UPR MI
BY THIS AFTERNOON. LIGHT WINDS WILL SHIFT TO THE ESE AND INCREASE UP
TO 20 KTS TONIGHT AS THE NEXT LO PRES SYSTEM IS FORECAST TO MOVE TO
SW MN BY SAT MORNING. AS THE PRES GRADIENT TIGHTENS OVER LAKE SUP ON
SAT/SAT NIGHT TO THE N OF THE LO TRACKING THRU THE CENTRAL LAKES...
E-SE BACKING NE WINDS WILL INCREASE UP TO 25 TO 30 KTS BEFORE
DIMINISHING AND FURTHER BACKING TO THE N ON SUN AS TRAILING HI PRES
SHIFTS TOWARD THE UPPER LAKES. FOR EARLY NEXT WEEK...PLAN ON NE
WINDS UP TO 20 KTS ON THE SE FLANK OF HI PRES OVER CENTRAL CANADA.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...JLA
SHORT TERM...KC
LONG TERM...VOSS
AVIATION...KEC
MARINE...KC
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1255 PM EDT FRI APR 5 2013
.UPDATE...
ISSUED AT 1254 PM EDT FRI APR 5 2013
GIVEN LARGER SPRING STORM IS QUICKLY ON THE APPROACH...THOUGHT
IT WOULD BE GOOD TO PROVIDE UPDATE IN TERMS OF EXPECTED STORM
INTENSITY/PTYPE AND HEADLINES.
SFC TROUGH THAT EVENTUALLY WILL DEVELOP INTO CLOSED OFF LOW OVER
WESTERN LAKES LATER SATURDAY IS CURRENTLY ALLIGNED FROM SOUTHERN
PORTIONS OF ALBERTA AND SASKATCHEWAN INTO NORTHERN US ROCKIES. 12Z
RAOBS AND WV LOOP SHOW H5 TROUGH PUSHING OUT OF WA/OR...WHILE TROUGH
AT H85 AND H7 IS CLOSER TO THE MAIN SFC LOW. SNOW IS AS CLOSE AS
ND/SASKATCHEAN BORDER ON EDGE OF H8-H7 FRONTOGENESIS. NAM/GFS AND
REGIONAL GEM INITIALIZED LARGER SCALE FEATURES WELL BUT DIFFER ON
CRITICAL THERMAL DETAILS FOR SATURDAY.
OVERALL...AT THE LEAST...WINTER WEATHER ADVISORIES WILL BE POSTED
LATER THIS AFTN FOR ALL OF CWA. ALREADY COORD WITH DLH AND GRB WHICH
HAVE ADVYS UP AND ALSO WITH APX. SOME AREAS MAY NEED WARNINGS BUT IT
WILL DEPEND ON WHERE PTYPE REMAINS MOSTLY SNOW FOR THE EVENT.
UNFORTUNATELY...THIS IS NOT CLEAR CUT EVEN WITHIN 24 HRS AS SOME
MODELS /GFS AND UKMET/ ARE PRETTY WARM AT H85-H8 DURING THE AFTN
HOURS ON SATURDAY /UP TO +3C AT H85/ WHILE NAM/REGIONAL GEM AND 00Z
ECMWF ARE NOT AS WARM. THIS IS ESPECIALLY TOUGH CONSIDERING THEY ARE
FAIRLY SIMILAR WITH H85/H7/H5 FEATURES. AS WOULD BE EXPECTED WITH
THERMAL PROFILES...GFS/SREF ARE SLIGHTLY FARTHER NORTH WITH SFC LOW.
GIVEN STEEP LAPSE RATES IN MID-LEVELS FEEDING INTO AREA OF
PRECIPITATION OVER UPR MICHIGAN...THERE IS ALSO CONCERN CONVECTION
WILL MODULATE INTENSITY AND PTYPE OVER THE CWA.
AT THIS POINT...FAR SOUTH SEEMS PRETTY CERTAIN TO SEE MAINLY RAIN BY
SATURDAY AFTN SO SNOW AMOUNTS WILL ULTIMATELY BE HELD DOWN FROM IMT
TO ESC AND CERTAINLY SOUTH TO MNM. GOGEBIC AND IRON TOUGH CALL AS
INITIAL WARM NOSE MAY RESULT IN MIX OF SLEET/SNOW AND EVEN RAIN LATE
TONIGHT INTO SATURDAY MORNING BUT PRECIP WOULD TURN BACK TO MAINLY
SNOW ON SATURDAY AFTN AS H7-H5 TROUGH/PRIMARY SHORTWAVES/LARGER
SCALE LIFTING AND DYNAMIC COOLING ARRIVE. MUCH MORE OF A QUESTION
IN THE TIER OF COUNTIES NORTH...FROM ONTONAGON/SOUTHERN HOUGHTON
THROUGH BARARA/MARQUETTE AND EAST TO ALGER/SCHOOLCRAFT/LUCE COUNTY.
IN THESE AREAS INITIAL SHOT OF PRECIP SATURDAY MORNING SHOULD REMAIN
MOSTLY SNOW AS THINK THAT DYNAMIC COOLING TIED TO STRONG H8-H5 FGEN
OFFSETS SHALLOW WARM LAYER H85-H8 AROUND +1C. INITIAL SURGE OF
PRECIP DRIVEN BY 295-305K /H85-H5/ ISENTROPIC ASCENT AND DIVERGENCE
ALOFT FROM LARGE JET STREAK OVER ONTARIO INTO QUEBEC COULD END AS
MIX OF SLEET/SNOW AS DYNAMIC COOLING FADES BTWN 15Z-18Z. STILL MANY
DETAILS TO BE SORTED OUT BUT WINTER WEATHER STATEMENT WITH FINAL
HEADLINE DECISIONS WILL BE OUT LATER THIS AFTN.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 622 AM EDT FRI APR 5 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW CONFLUENT NW FLOW
ALF OVER THE GRT LKS DOWNSTREAM OF RDG OVER THE ROCKIES. AT THE
LLVLS...THE CWA IS DOMINATING BY A NW FLOW OF COLDER AIR IN THE WAKE
OF THU COLD FROPA AND AHEAD OF SFC HI PRES NEAR LK WINNIPEG. SINCE
THE 00Z INL RAOB SHOWED A VERY DRY...INVERTED V PROFILE AND RECENT
SFC OBS INDICATE FAIRLY LARGE SFC T/TD SPREADS...SKIES ARE MOCLR
OVER UPR MI AS OF 06Z. BUT THE 00Z YPL RAOB DEPICTED A SOMEWHAT
MOISTER...BUT STILL WELL MIXED...SFC-H85 T/TD PROFILE WITH AN H85
TEMP DOWN TO -16C. FARTHER UPSTREAM...A SHRTWV IS MOVING INTO THE
PAC NW. WAD MID/HI CLDS WELL E OF THIS DISTURBANCE ARE SPREADING
INTO THE NRN PLAINS.
TODAY...ALTHOUGH SKIES ARE MOCLR EARLY THIS MRNG...SUSPECT SOME LK
CLDS/EVEN SOME -SHSN MIGHT DVLP OVER AREAS E OF MQT AS THE
MOISTER...COLDER AIRMASS SHOWN ON THE 00Z YPL RAOB WITH H85 TEMPS AS
LO AS -15C IMPACT THIS PART OF THE CWA. OVER THE W HALF...THE VERY
DRY 00Z INL RAOB IS MORE REPRESENTATIVE OF THE SOURCE AIRMASS. SO
REMOVED POPS/DIMINISHED FCST CLDS IN THIS AREA. BUT EVEN OVER THE
E...GENERALY ACYC NATURE OF THE FCST LLVL FLOW AS WELL AS HIER SFC
T/TD DEPRESSIONS EVEN FARTHER E N OF LK SUP SUG ANY SN ACCUMS WL BE
NEGLIGIBLE IF SHSN DO FORM AT ALL. WITH DAYTIME HEATING/LARGE SCALE
SUBSIDENCE AS SFC HI BLDS OVER THE W HALF OF THE CWA BY 18Z...EXPECT
ANY LES OVER THE E TO DIMINISH BY NOON. DIURNAL CU/SC THAT DVLP WITH
DAYTIME HEATING/MIXING UNDER LINGERING H85 THERMAL TROF WL TEND TO
DIMINISH OVER AT LEAST THE W AND CENTRAL WITH MORE EMPHATIC DRYING/
QUICKER TRANSITION TO MORE ACYC FLOW...BUT SC MAY LINGER LONGER OVER
THE E WHERE THE H85 TEMPS WARM ABV -10C ONLY TOWARD 00Z. MIXING TO
H85 AS OBSVD ON UPSTREAM 00Z RAOBS YIELDS HI TEMPS IN THE UPR 30S/
LO 40S OVER THE W...BUT ONLY 30 TO 35 OVER THE CNTRL AND E WHERE
LOWER H85 TEMPS LINGER LONGER. WITH WEAKER PRES GRADIENT ARRIVING
WITH SFC HI CENTER...LK BREEZES WL MAINTAIN LOCAL COOLING NEAR THE
SHORES. SOME HI CLDS WL ARRIVE OVER THE W IN THE AFTN WELL IN
ADVANCE OF PAC NW SHRTWV MOVING THRU THE NRN ROCKIES.
TNGT...AS SHRTWV MOVES THRU THE NRN PLAINS AND ASSOCIATED SFC LO
SHIFTS TO SW MN BY 12Z SAT...EXPECT THICKENING CLDS IN THE DVLPG WAD
PATTERN BTWN THE DEPARTING HI AND INCOMING LO PRES. VIGOROUS
ISENTROPIC ASCENT SHOWN ON THE 280-295K ISENTROPIC SFCS IS FCST TO
SPREAD W-E ACRS THE CWA AND SLOWLY SATURATE THE VERY DRY ANTECEDENT
LO-MID LVLS. FAVOR THE SOMEWHAT SLOWER 00Z NAM/CNDN AND 12Z ECMWF
FOR TIMING LEADING EDGE OF PCPN TIED TO H5-7 FGEN AXIS OVER THE
GFS...WHICH APPEARS TO GENERATE PCPN TOO DEEP INTO THE LINGERING DRY
AIR. THESE FAVORED MODELS INDICATE PCPN WL REACH A LINE FROM
MUNISING-MANISTIQUE BY 12Z SAT... SO RESTRICTED CATEGORICAL POPS TO
THE W OF THAT AXIS. FAVORED MODEL QPF INDICATES 2 TO 3 INCHES OF SN
OVER THE SW CWA BY 12Z SAT EVEN THOUGH RATHER NARROW/HI DGZ CENTERED
ARND 15K FT WL LIMIT SN/WATER RATIOS. EXPECT THE LOWEST MIN TEMPS
OVER THE INTERIOR E...WHERE THE CLDS WL ARRIVE LATEST AND WINDS BE
LGT IN THE EVNG TO ALLOW FOR GOOD RADIATIONAL COOLING. FOLLOWED A
NON-DIURNAL CURVE WITH TEMPS FALLING TO THE LOWEST LVL FAIRLY
EARLY...THEN STEADY OR SLOWLY RISING.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 622 AM EDT FRI APR 5 2013
MAIN FCST CONCERNS FOCUS ON SYSTEM FOR SATURDAY...PTYPE
CONCERNS...POSSIBLE HEADLINES AND SNOW AMTS.
ACTIVE SHORTWAVE NOW MOVING IN OFF THE PACIFIC NW AS NOTED ON WATER
VAPOR LOOP IS EXPECTED TO TRACK DUE E...REACHING THE WRN GREAT LAKES
SAT. WHILE MODELS HAVE COME INTO BETTER AGREEMENT WITH TRACK/TIMING
OF SHORTWAVE AND ASSOC SFC LOW SOME IMPORTANT MODEL DIFFERENCES
REMAIN IN THERMAL FIELDS. CONFIDENCE IS HIGH THAT ALL OF THE FCST
AREA WILL SEE PCPN...SO HIGH CATEGORICAL POPS WILL BE PAINTED ACROSS
THE CWA. RIGHT ENTRANCE OF UPPER JET ASSOCIATED WITH ERN CANADA TROF
WILL PROVIDE LARGER SCALE ENHANCEMENT TO UPWARD MOTION...AS A FAIRLY
VIGOROUS FRONTOGENESIS SIGNATURE WILL AID PCPN INTENSITY ON THE
SMALLER SCALE. IT APPEARS THAT THERE MAY BE 2 PERIODS OF FGEN
FORCING...ONE INITIALLY LATE TONIGHT/SAT MORNING THAT
TRANSLATES ACROSS THE AREA...THEN A SECOND SAT AFTN/EVENING THAT
WOULD FAVOR CNTRL/ERN UPPER MI FOR HEAVIER PCPN. WITH MIXING RATIOS
OF 4-5G/KG AND CLOSE TO 12HRS OF ASCENT...THERE COULD BE 6 TO
POSSIBLY AS MUCH AS LOCALLY 8-10 INCHES OF HVY/WET SNOW ALONG THE
AXIS OF HEAVIEST PCPN WHERE PTYPE IS ALL SNOW. SO...DETERMINING THE
CONFIGURATION OF PTYPES WILL BE CRITICAL. IS STILL APPEARS THAT
PTYPE WILL BE ALL SNOW ACROSS THE FCST AREA AS PCPN DEVELOPS TONIGHT
...AND THAT SNOW MAY FALL LONG ENOUGH SO THAT A FEW INCHES OF SNOW
ACCUMULATE EVEN IN AREAS THAT SEE A MIX OR CHANGE TO RAIN DURING THE
DAY SAT. DURING THE DAY SAT...UNCERTAINTY GROWS IN HOW FAR N WARMING
OCCURS. THE 06Z GFS AND NAM BRINGS 0C 850MB ISOTHERM AND CRITICAL
1000-850MB THICKNESS FAR ENOUGH N SO THAT PERHAPS ONLY WEST AND NW
UPPER MI REMAINS MOSTLY SNOW SAT AFTN/EVENING. THE LOCAL WRF-ARW AND
REG-GEM ARE FARTHER S WITH THESE TEMP PARAMETERS AND ARE GENERALLY
MORE IN LINE WITH THE ECMWF...SUGGESTING MUCH OF NRN UPPER MI WILL
STAY MOSTLY SNOW. FCST SOUNDINGS STILL SUGGEST THAT A NARROW ZONE OF
SLEET IS ALSO POSSIBLE IN THE TRANSITION ZONE BTWN MOSTLY SNOW NORTH
TO MOSTLY RAIN SOUTH ON SAT. CONSIDERED ISSUING A WATCH FOR SOME THE
NRN COUNTIES IN SWATH OF EXPECTED HEAVIER PCPN WHERE PTYPE WILL BE
MOSTLY SNOW...BUT GIVEN CONTINUED UNCERTAINTIES WITH PTYPE AND
ULTIMATE ACCUMS DECIDED TO KEEP AN SPS GOING HIGHLIGHTING THE
POTENTIAL FOR VERY HVY/WET SNOW THAT WILL BE DIFFICULT TO
SHOVEL/PLOW AND WILL LEAD TO VERY DIFFICULT TRAVEL CONDITIONS.
ON SUN...SFC HIGH PRES WILL NOSE INTO THE UPPER LAKES BEHIND
SYSTEM...BRINGING AN INFLUX OF DRIER AIR. DAYTIME TEMPS SHOULD
RECOVER WELL INTO THE 30S/LWR 40S IN THE AFTN WITH SOME INCREASE IN
SUNSHINE DURING THE DAY.
FCST FOR MON THRU THU REMAINS UNCERTAIN. MUCH OF THE FCST WILL HINGE
ON THE STRENGTH OF THE LINGERING ERN CANADA TROF UNDER THE WEAKENING
NEGATIVE AO/NAO PATTERN. OTHER THAN A SHOWING A WEAK NRN PLAINS
SHORTWAVE MOVING THROUGH THE AREA LATE SUNDAY NIGHT INTO
MONDAY...THE LATEST ECMWF IS SIMILAR TO RECENT RUNS SHOWING A
STRONGER AND MORE PERSISTENT ERN CANADIAN TROF WHICH KEEPS A DRIER
WNW FLOW ACROSS THE UPPER LAKES FOR THE EARLY PART OF NEXT WEEK.
THIS IDEA ALSO WOULD GO ALONG WITH THE GENERAL PERSISTENT PATTERN
WHICH HAS DOMINATED THE REGION FOR THE LAST SEVERAL WEEKS...ALTHOUGH
IT REMAINS TO BE SEEN HOW LONG PATTERN WILL PERSIST GIVEN EXPECT
WEAKENING OF HIGH LATITUDE BLOCKING. THE 12Z ECMWF DOES FINALLY
BRING PCPN INTO THE FCST AREA ON WED NIGHT AND THU...MAINLY IN FORM
OF SNOW...AS MAIN PIECE OF ENERGY FROM WRN CONUS TROF EJECTS NE
TOWARD THE GREAT LAKES. MEANWHILE...THE LATEST 00Z RUN OF THE GFS
QUICKLY WEAKENS THE ERN CANADIAN TROF AND PUSHES IT EAST ALLOWING
FOR A STRONG SRN STREAM SHORTWAVE TO EJECT TOWARD THE UPPER GREAT
LAKES FM BASE OF WRN CONUS TROF. THE GFS SHOWS 8H TEMPS RISING TO
10-12C BY TUE NIGHT INTO WED ACCOMPANIED BY A SLUG OF GULF MOISTURE
(250-300 PCT OF NORMAL PWAT VALUES) WHICH WOULD YIELD A THREAT OF
MODERATE TO HEAVY RAIN TO THE FCST AREA TUE NIGHT INTO WED. THE 12Z
GEM-NH GENERALLY LENDS MORE SUPPORT TO ECMWF SOLN ALTHOUGH IT ALSO
TENDS TO BREAK DOWN ERN CANADIAN TROF QUICKER THAN ECMWF. GIVEN
CONSIDERABLE MODEL UNCERTAINTY...WILL CONTINUE SIMPLE CONSENSUS
APPROACH TO FCST KEEPING ONLY SCHC POPS FOR MON INTO TUE THEN
INCREASE POPS TO 30-40 PCT CHC FOR WED AND THU WITH THE IDEA THAT
ERN CANADA TROF WILL WEAKEN ALLOWING FOR MORE ENERGY FROM WRN CONUS
TROF TO REACH UPPER GREAT LAKES. TEMPS SHOULD REMAIN BLO NORMAL THRU
THE PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 732 AM EDT FRI APR 5 2013
ALTHOUGH THERE WL BE SOME SC AT MAINLY SAW INTO THIS AFTN...DRY
NATURE OF THE INCOMING AIRMASS ASSOCIATED WITH HI PRES MOVING INTO
MN WL BRING VFR CONDITIONS AT ALL 3 LOCATIONS INTO THIS EVNG.
THICKER CLDS AND THEN SN WL ARRIVE TNGT IN ADVANCE OF A LO PRES
SYSTEM MOVING THRU THE NRN PLAINS. EVEN BEFORE THE SN ARRIVES...CIGS
AT SAW MAY FALL INTO THE MVFR RANGE WITH UPSLOPE SE FLOW BTWN THE
DEPARTING HI/INCOMING LO PRES. EXPECT VSBYS TO DROP INTO THE IFR
CATEGORY AT ALL 3 LOCATIONS AFTER MIDNGT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 622 AM EDT FRI APR 5 2013
NW WINDS UP TO 25 KTS EARLY THIS MORNING OVER THE E HALF WILL
DIMINISH STEADILY TODAY AS HI PRES IS FORECAST TO BUILD OVER UPR MI
BY THIS AFTERNOON. LIGHT WINDS WILL SHIFT TO THE ESE AND INCREASE UP
TO 20 KTS TONIGHT AS THE NEXT LO PRES SYSTEM IS FORECAST TO MOVE TO
SW MN BY SAT MORNING. AS THE PRES GRADIENT TIGHTENS OVER LAKE SUP ON
SAT/SAT NIGHT TO THE N OF THE LO TRACKING THRU THE CENTRAL LAKES...
E-SE BACKING NE WINDS WILL INCREASE UP TO 25 TO 30 KTS BEFORE
DIMINISHING AND FURTHER BACKING TO THE N ON SUN AS TRAILING HI PRES
SHIFTS TOWARD THE UPPER LAKES. FOR EARLY NEXT WEEK...PLAN ON NE
WINDS UP TO 20 KTS ON THE SE FLANK OF HI PRES OVER CENTRAL CANADA.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...JLA
SHORT TERM...KC
LONG TERM...VOSS
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
732 AM EDT FRI APR 5 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 622 AM EDT FRI APR 5 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW CONFLUENT NW FLOW
ALF OVER THE GRT LKS DOWNSTREAM OF RDG OVER THE ROCKIES. AT THE
LLVLS...THE CWA IS DOMINATING BY A NW FLOW OF COLDER AIR IN THE WAKE
OF THU COLD FROPA AND AHEAD OF SFC HI PRES NEAR LK WINNIPEG. SINCE
THE 00Z INL RAOB SHOWED A VERY DRY...INVERTED V PROFILE AND RECENT
SFC OBS INDICATE FAIRLY LARGE SFC T/TD SPREADS...SKIES ARE MOCLR
OVER UPR MI AS OF 06Z. BUT THE 00Z YPL RAOB DEPICTED A SOMEWHAT
MOISTER...BUT STILL WELL MIXED...SFC-H85 T/TD PROFILE WITH AN H85
TEMP DOWN TO -16C. FARTHER UPSTREAM...A SHRTWV IS MOVING INTO THE
PAC NW. WAD MID/HI CLDS WELL E OF THIS DISTURBANCE ARE SPREADING
INTO THE NRN PLAINS.
TODAY...ALTHOUGH SKIES ARE MOCLR EARLY THIS MRNG...SUSPECT SOME LK
CLDS/EVEN SOME -SHSN MIGHT DVLP OVER AREAS E OF MQT AS THE
MOISTER...COLDER AIRMASS SHOWN ON THE 00Z YPL RAOB WITH H85 TEMPS AS
LO AS -15C IMPACT THIS PART OF THE CWA. OVER THE W HALF...THE VERY
DRY 00Z INL RAOB IS MORE REPRESENTATIVE OF THE SOURCE AIRMASS. SO
REMOVED POPS/DIMINISHED FCST CLDS IN THIS AREA. BUT EVEN OVER THE
E...GENERALY ACYC NATURE OF THE FCST LLVL FLOW AS WELL AS HIER SFC
T/TD DEPRESSIONS EVEN FARTHER E N OF LK SUP SUG ANY SN ACCUMS WL BE
NEGLIGIBLE IF SHSN DO FORM AT ALL. WITH DAYTIME HEATING/LARGE SCALE
SUBSIDENCE AS SFC HI BLDS OVER THE W HALF OF THE CWA BY 18Z...EXPECT
ANY LES OVER THE E TO DIMINISH BY NOON. DIURNAL CU/SC THAT DVLP WITH
DAYTIME HEATING/MIXING UNDER LINGERING H85 THERMAL TROF WL TEND TO
DIMINISH OVER AT LEAST THE W AND CENTRAL WITH MORE EMPHATIC DRYING/
QUICKER TRANSITION TO MORE ACYC FLOW...BUT SC MAY LINGER LONGER OVER
THE E WHERE THE H85 TEMPS WARM ABV -10C ONLY TOWARD 00Z. MIXING TO
H85 AS OBSVD ON UPSTREAM 00Z RAOBS YIELDS HI TEMPS IN THE UPR 30S/
LO 40S OVER THE W...BUT ONLY 30 TO 35 OVER THE CNTRL AND E WHERE
LOWER H85 TEMPS LINGER LONGER. WITH WEAKER PRES GRADIENT ARRIVING
WITH SFC HI CENTER...LK BREEZES WL MAINTAIN LOCAL COOLING NEAR THE
SHORES. SOME HI CLDS WL ARRIVE OVER THE W IN THE AFTN WELL IN
ADVANCE OF PAC NW SHRTWV MOVING THRU THE NRN ROCKIES.
TNGT...AS SHRTWV MOVES THRU THE NRN PLAINS AND ASSOCIATED SFC LO
SHIFTS TO SW MN BY 12Z SAT...EXPECT THICKENING CLDS IN THE DVLPG WAD
PATTERN BTWN THE DEPARTING HI AND INCOMING LO PRES. VIGOROUS
ISENTROPIC ASCENT SHOWN ON THE 280-295K ISENTROPIC SFCS IS FCST TO
SPREAD W-E ACRS THE CWA AND SLOWLY SATURATE THE VERY DRY ANTECEDENT
LO-MID LVLS. FAVOR THE SOMEWHAT SLOWER 00Z NAM/CNDN AND 12Z ECMWF
FOR TIMING LEADING EDGE OF PCPN TIED TO H5-7 FGEN AXIS OVER THE
GFS...WHICH APPEARS TO GENERATE PCPN TOO DEEP INTO THE LINGERING DRY
AIR. THESE FAVORED MODELS INDICATE PCPN WL REACH A LINE FROM
MUNISING-MANISTIQUE BY 12Z SAT... SO RESTRICTED CATEGORICAL POPS TO
THE W OF THAT AXIS. FAVORED MODEL QPF INDICATES 2 TO 3 INCHES OF SN
OVER THE SW CWA BY 12Z SAT EVEN THOUGH RATHER NARROW/HI DGZ CENTERED
ARND 15K FT WL LIMIT SN/WATER RATIOS. EXPECT THE LOWEST MIN TEMPS
OVER THE INTERIOR E...WHERE THE CLDS WL ARRIVE LATEST AND WINDS BE
LGT IN THE EVNG TO ALLOW FOR GOOD RADIATIONAL COOLING. FOLLOWED A
NON-DIURNAL CURVE WITH TEMPS FALLING TO THE LOWEST LVL FAIRLY
EARLY...THEN STEADY OR SLOWLY RISING.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 622 AM EDT FRI APR 5 2013
MAIN FCST CONCERNS FOCUS ON SYSTEM FOR SATURDAY...PTYPE
CONCERNS...POSSIBLE HEADLINES AND SNOW AMTS.
ACTIVE SHORTWAVE NOW MOVING IN OFF THE PACIFIC NW AS NOTED ON WATER
VAPOR LOOP IS EXPECTED TO TRACK DUE E...REACHING THE WRN GREAT LAKES
SAT. WHILE MODELS HAVE COME INTO BETTER AGREEMENT WITH TRACK/TIMING
OF SHORTWAVE AND ASSOC SFC LOW SOME IMPORTANT MODEL DIFFERENCES
REMAIN IN THERMAL FIELDS. CONFIDENCE IS HIGH THAT ALL OF THE FCST
AREA WILL SEE PCPN...SO HIGH CATEGORICAL POPS WILL BE PAINTED ACROSS
THE CWA. RIGHT ENTRANCE OF UPPER JET ASSOCIATED WITH ERN CANADA TROF
WILL PROVIDE LARGER SCALE ENHANCEMENT TO UPWARD MOTION...AS A FAIRLY
VIGOROUS FRONTOGENESIS SIGNATURE WILL AID PCPN INTENSITY ON THE
SMALLER SCALE. IT APPEARS THAT THERE MAY BE 2 PERIODS OF FGEN
FORCING...ONE INITIALLY LATE TONIGHT/SAT MORNING THAT
TRANSLATES ACROSS THE AREA...THEN A SECOND SAT AFTN/EVENING THAT
WOULD FAVOR CNTRL/ERN UPPER MI FOR HEAVIER PCPN. WITH MIXING RATIOS
OF 4-5G/KG AND CLOSE TO 12HRS OF ASCENT...THERE COULD BE 6 TO
POSSIBLY AS MUCH AS LOCALLY 8-10 INCHES OF HVY/WET SNOW ALONG THE
AXIS OF HEAVIEST PCPN WHERE PTYPE IS ALL SNOW. SO...DETERMINING THE
CONFIGURATION OF PTYPES WILL BE CRITICAL. IS STILL APPEARS THAT
PTYPE WILL BE ALL SNOW ACROSS THE FCST AREA AS PCPN DEVELOPS TONIGHT
...AND THAT SNOW MAY FALL LONG ENOUGH SO THAT A FEW INCHES OF SNOW
ACCUMULATE EVEN IN AREAS THAT SEE A MIX OR CHANGE TO RAIN DURING THE
DAY SAT. DURING THE DAY SAT...UNCERTAINTY GROWS IN HOW FAR N WARMING
OCCURS. THE 06Z GFS AND NAM BRINGS 0C 850MB ISOTHERM AND CRITICAL
1000-850MB THICKNESS FAR ENOUGH N SO THAT PERHAPS ONLY WEST AND NW
UPPER MI REMAINS MOSTLY SNOW SAT AFTN/EVENING. THE LOCAL WRF-ARW AND
REG-GEM ARE FARTHER S WITH THESE TEMP PARAMETERS AND ARE GENERALLY
MORE IN LINE WITH THE ECMWF...SUGGESTING MUCH OF NRN UPPER MI WILL
STAY MOSTLY SNOW. FCST SOUNDINGS STILL SUGGEST THAT A NARROW ZONE OF
SLEET IS ALSO POSSIBLE IN THE TRANSITION ZONE BTWN MOSTLY SNOW NORTH
TO MOSTLY RAIN SOUTH ON SAT. CONSIDERED ISSUING A WATCH FOR SOME THE
NRN COUNTIES IN SWATH OF EXPECTED HEAVIER PCPN WHERE PTYPE WILL BE
MOSTLY SNOW...BUT GIVEN CONTINUED UNCERTAINTIES WITH PTYPE AND
ULTIMATE ACCUMS DECIDED TO KEEP AN SPS GOING HIGHLIGHTING THE
POTENTIAL FOR VERY HVY/WET SNOW THAT WILL BE DIFFICULT TO
SHOVEL/PLOW AND WILL LEAD TO VERY DIFFICULT TRAVEL CONDITIONS.
ON SUN...SFC HIGH PRES WILL NOSE INTO THE UPPER LAKES BEHIND
SYSTEM...BRINGING AN INFLUX OF DRIER AIR. DAYTIME TEMPS SHOULD
RECOVER WELL INTO THE 30S/LWR 40S IN THE AFTN WITH SOME INCREASE IN
SUNSHINE DURING THE DAY.
FCST FOR MON THRU THU REMAINS UNCERTAIN. MUCH OF THE FCST WILL HINGE
ON THE STRENGTH OF THE LINGERING ERN CANADA TROF UNDER THE WEAKENING
NEGATIVE AO/NAO PATTERN. OTHER THAN A SHOWING A WEAK NRN PLAINS
SHORTWAVE MOVING THROUGH THE AREA LATE SUNDAY NIGHT INTO
MONDAY...THE LATEST ECMWF IS SIMILAR TO RECENT RUNS SHOWING A
STRONGER AND MORE PERSISTENT ERN CANADIAN TROF WHICH KEEPS A DRIER
WNW FLOW ACROSS THE UPPER LAKES FOR THE EARLY PART OF NEXT WEEK.
THIS IDEA ALSO WOULD GO ALONG WITH THE GENERAL PERSISTENT PATTERN
WHICH HAS DOMINATED THE REGION FOR THE LAST SEVERAL WEEKS...ALTHOUGH
IT REMAINS TO BE SEEN HOW LONG PATTERN WILL PERSIST GIVEN EXPECT
WEAKENING OF HIGH LATITUDE BLOCKING. THE 12Z ECMWF DOES FINALLY
BRING PCPN INTO THE FCST AREA ON WED NIGHT AND THU...MAINLY IN FORM
OF SNOW...AS MAIN PIECE OF ENERGY FROM WRN CONUS TROF EJECTS NE
TOWARD THE GREAT LAKES. MEANWHILE...THE LATEST 00Z RUN OF THE GFS
QUICKLY WEAKENS THE ERN CANADIAN TROF AND PUSHES IT EAST ALLOWING
FOR A STRONG SRN STREAM SHORTWAVE TO EJECT TOWARD THE UPPER GREAT
LAKES FM BASE OF WRN CONUS TROF. THE GFS SHOWS 8H TEMPS RISING TO
10-12C BY TUE NIGHT INTO WED ACCOMPANIED BY A SLUG OF GULF MOISTURE
(250-300 PCT OF NORMAL PWAT VALUES) WHICH WOULD YIELD A THREAT OF
MODERATE TO HEAVY RAIN TO THE FCST AREA TUE NIGHT INTO WED. THE 12Z
GEM-NH GENERALLY LENDS MORE SUPPORT TO ECMWF SOLN ALTHOUGH IT ALSO
TENDS TO BREAK DOWN ERN CANADIAN TROF QUICKER THAN ECMWF. GIVEN
CONSIDERABLE MODEL UNCERTAINTY...WILL CONTINUE SIMPLE CONSENSUS
APPROACH TO FCST KEEPING ONLY SCHC POPS FOR MON INTO TUE THEN
INCREASE POPS TO 30-40 PCT CHC FOR WED AND THU WITH THE IDEA THAT
ERN CANADA TROF WILL WEAKEN ALLOWING FOR MORE ENERGY FROM WRN CONUS
TROF TO REACH UPPER GREAT LAKES. TEMPS SHOULD REMAIN BLO NORMAL THRU
THE PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 732 AM EDT FRI APR 5 2013
ALTHOUGH THERE WL BE SOME SC AT MAINLY SAW INTO THIS AFTN...DRY
NATURE OF THE INCOMING AIRMASS ASSOCIATED WITH HI PRES MOVING INTO
MN WL BRING VFR CONDITIONS AT ALL 3 LOCATIONS INTO THIS EVNG.
THICKER CLDS AND THEN SN WL ARRIVE TNGT IN ADVANCE OF A LO PRES
SYSTEM MOVING THRU THE NRN PLAINS. EVEN BEFORE THE SN ARRIVES...CIGS
AT SAW MAY FALL INTO THE MVFR RANGE WITH UPSLOPE SE FLOW BTWN THE
DEPARTING HI/INCOMING LO PRES. EXPECT VSBYS TO DROP INTO THE IFR
CATEGORY AT ALL 3 LOCATIONS AFTER MIDNGT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 622 AM EDT FRI APR 5 2013
NW WINDS UP TO 25 KTS EARLY THIS MORNING OVER THE E HALF WILL
DIMINISH STEADILY TODAY AS HI PRES IS FORECAST TO BUILD OVER UPR MI
BY THIS AFTERNOON. LIGHT WINDS WILL SHIFT TO THE ESE AND INCREASE UP
TO 20 KTS TONIGHT AS THE NEXT LO PRES SYSTEM IS FORECAST TO MOVE TO
SW MN BY SAT MORNING. AS THE PRES GRADIENT TIGHTENS OVER LAKE SUP ON
SAT/SAT NIGHT TO THE N OF THE LO TRACKING THRU THE CENTRAL LAKES...
E-SE BACKING NE WINDS WILL INCREASE UP TO 25 TO 30 KTS BEFORE
DIMINISHING AND FURTHER BACKING TO THE N ON SUN AS TRAILING HI PRES
SHIFTS TOWARD THE UPPER LAKES. FOR EARLY NEXT WEEK...PLAN ON NE
WINDS UP TO 20 KTS ON THE SE FLANK OF HI PRES OVER CENTRAL CANADA.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...VOSS
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
624 AM EDT FRI APR 5 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 622 AM EDT FRI APR 5 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW CONFLUENT NW FLOW
ALF OVER THE GRT LKS DOWNSTREAM OF RDG OVER THE ROCKIES. AT THE
LLVLS...THE CWA IS DOMINATING BY A NW FLOW OF COLDER AIR IN THE WAKE
OF THU COLD FROPA AND AHEAD OF SFC HI PRES NEAR LK WINNIPEG. SINCE
THE 00Z INL RAOB SHOWED A VERY DRY...INVERTED V PROFILE AND RECENT
SFC OBS INDICATE FAIRLY LARGE SFC T/TD SPREADS...SKIES ARE MOCLR
OVER UPR MI AS OF 06Z. BUT THE 00Z YPL RAOB DEPICTED A SOMEWHAT
MOISTER...BUT STILL WELL MIXED...SFC-H85 T/TD PROFILE WITH AN H85
TEMP DOWN TO -16C. FARTHER UPSTREAM...A SHRTWV IS MOVING INTO THE
PAC NW. WAD MID/HI CLDS WELL E OF THIS DISTURBANCE ARE SPREADING
INTO THE NRN PLAINS.
TODAY...ALTHOUGH SKIES ARE MOCLR EARLY THIS MRNG...SUSPECT SOME LK
CLDS/EVEN SOME -SHSN MIGHT DVLP OVER AREAS E OF MQT AS THE
MOISTER...COLDER AIRMASS SHOWN ON THE 00Z YPL RAOB WITH H85 TEMPS AS
LO AS -15C IMPACT THIS PART OF THE CWA. OVER THE W HALF...THE VERY
DRY 00Z INL RAOB IS MORE REPRESENTATIVE OF THE SOURCE AIRMASS. SO
REMOVED POPS/DIMINISHED FCST CLDS IN THIS AREA. BUT EVEN OVER THE
E...GENERALY ACYC NATURE OF THE FCST LLVL FLOW AS WELL AS HIER SFC
T/TD DEPRESSIONS EVEN FARTHER E N OF LK SUP SUG ANY SN ACCUMS WL BE
NEGLIGIBLE IF SHSN DO FORM AT ALL. WITH DAYTIME HEATING/LARGE SCALE
SUBSIDENCE AS SFC HI BLDS OVER THE W HALF OF THE CWA BY 18Z...EXPECT
ANY LES OVER THE E TO DIMINISH BY NOON. DIURNAL CU/SC THAT DVLP WITH
DAYTIME HEATING/MIXING UNDER LINGERING H85 THERMAL TROF WL TEND TO
DIMINISH OVER AT LEAST THE W AND CENTRAL WITH MORE EMPHATIC DRYING/
QUICKER TRANSITION TO MORE ACYC FLOW...BUT SC MAY LINGER LONGER OVER
THE E WHERE THE H85 TEMPS WARM ABV -10C ONLY TOWARD 00Z. MIXING TO
H85 AS OBSVD ON UPSTREAM 00Z RAOBS YIELDS HI TEMPS IN THE UPR 30S/
LO 40S OVER THE W...BUT ONLY 30 TO 35 OVER THE CNTRL AND E WHERE
LOWER H85 TEMPS LINGER LONGER. WITH WEAKER PRES GRADIENT ARRIVING
WITH SFC HI CENTER...LK BREEZES WL MAINTAIN LOCAL COOLING NEAR THE
SHORES. SOME HI CLDS WL ARRIVE OVER THE W IN THE AFTN WELL IN
ADVANCE OF PAC NW SHRTWV MOVING THRU THE NRN ROCKIES.
TNGT...AS SHRTWV MOVES THRU THE NRN PLAINS AND ASSOCIATED SFC LO
SHIFTS TO SW MN BY 12Z SAT...EXPECT THICKENING CLDS IN THE DVLPG WAD
PATTERN BTWN THE DEPARTING HI AND INCOMING LO PRES. VIGOROUS
ISENTROPIC ASCENT SHOWN ON THE 280-295K ISENTROPIC SFCS IS FCST TO
SPREAD W-E ACRS THE CWA AND SLOWLY SATURATE THE VERY DRY ANTECEDENT
LO-MID LVLS. FAVOR THE SOMEWHAT SLOWER 00Z NAM/CNDN AND 12Z ECMWF
FOR TIMING LEADING EDGE OF PCPN TIED TO H5-7 FGEN AXIS OVER THE
GFS...WHICH APPEARS TO GENERATE PCPN TOO DEEP INTO THE LINGERING DRY
AIR. THESE FAVORED MODELS INDICATE PCPN WL REACH A LINE FROM
MUNISING-MANISTIQUE BY 12Z SAT... SO RESTRICTED CATEGORICAL POPS TO
THE W OF THAT AXIS. FAVORED MODEL QPF INDICATES 2 TO 3 INCHES OF SN
OVER THE SW CWA BY 12Z SAT EVEN THOUGH RATHER NARROW/HI DGZ CENTERED
ARND 15K FT WL LIMIT SN/WATER RATIOS. EXPECT THE LOWEST MIN TEMPS
OVER THE INTERIOR E...WHERE THE CLDS WL ARRIVE LATEST AND WINDS BE
LGT IN THE EVNG TO ALLOW FOR GOOD RADIATIONAL COOLING. FOLLOWED A
NON-DIURNAL CURVE WITH TEMPS FALLING TO THE LOWEST LVL FAIRLY
EARLY...THEN STEADY OR SLOWLY RISING.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 622 AM EDT FRI APR 5 2013
MAIN FCST CONCERNS FOCUS ON SYSTEM FOR SATURDAY...PTYPE
CONCERNS...POSSIBLE HEADLINES AND SNOW AMTS.
ACTIVE SHORTWAVE NOW MOVING IN OFF THE PACIFIC NW AS NOTED ON WATER
VAPOR LOOP IS EXPECTED TO TRACK DUE E...REACHING THE WRN GREAT LAKES
SAT. WHILE MODELS HAVE COME INTO BETTER AGREEMENT WITH TRACK/TIMING
OF SHORTWAVE AND ASSOC SFC LOW SOME IMPORTANT MODEL DIFFERENCES
REMAIN IN THERMAL FIELDS. CONFIDENCE IS HIGH THAT ALL OF THE FCST
AREA WILL SEE PCPN...SO HIGH CATEGORICAL POPS WILL BE PAINTED ACROSS
THE CWA. RIGHT ENTRANCE OF UPPER JET ASSOCIATED WITH ERN CANADA TROF
WILL PROVIDE LARGER SCALE ENHANCEMENT TO UPWARD MOTION...AS A FAIRLY
VIGOROUS FRONTOGENESIS SIGNATURE WILL AID PCPN INTENSITY ON THE
SMALLER SCALE. IT APPEARS THAT THERE MAY BE 2 PERIODS OF FGEN
FORCING...ONE INITIALLY LATE TONIGHT/SAT MORNING THAT
TRANSLATES ACROSS THE AREA...THEN A SECOND SAT AFTN/EVENING THAT
WOULD FAVOR CNTRL/ERN UPPER MI FOR HEAVIER PCPN. WITH MIXING RATIOS
OF 4-5G/KG AND CLOSE TO 12HRS OF ASCENT...THERE COULD BE 6 TO
POSSIBLY AS MUCH AS LOCALLY 8-10 INCHES OF HVY/WET SNOW ALONG THE
AXIS OF HEAVIEST PCPN WHERE PTYPE IS ALL SNOW. SO...DETERMINING THE
CONFIGURATION OF PTYPES WILL BE CRITICAL. IS STILL APPEARS THAT
PTYPE WILL BE ALL SNOW ACROSS THE FCST AREA AS PCPN DEVELOPS TONIGHT
...AND THAT SNOW MAY FALL LONG ENOUGH SO THAT A FEW INCHES OF SNOW
ACCUMULATE EVEN IN AREAS THAT SEE A MIX OR CHANGE TO RAIN DURING THE
DAY SAT. DURING THE DAY SAT...UNCERTAINTY GROWS IN HOW FAR N WARMING
OCCURS. THE 06Z GFS AND NAM BRINGS 0C 850MB ISOTHERM AND CRITICAL
1000-850MB THICKNESS FAR ENOUGH N SO THAT PERHAPS ONLY WEST AND NW
UPPER MI REMAINS MOSTLY SNOW SAT AFTN/EVENING. THE LOCAL WRF-ARW AND
REG-GEM ARE FARTHER S WITH THESE TEMP PARAMETERS AND ARE GENERALLY
MORE IN LINE WITH THE ECMWF...SUGGESTING MUCH OF NRN UPPER MI WILL
STAY MOSTLY SNOW. FCST SOUNDINGS STILL SUGGEST THAT A NARROW ZONE OF
SLEET IS ALSO POSSIBLE IN THE TRANSITION ZONE BTWN MOSTLY SNOW NORTH
TO MOSTLY RAIN SOUTH ON SAT. CONSIDERED ISSUING A WATCH FOR SOME THE
NRN COUNTIES IN SWATH OF EXPECTED HEAVIER PCPN WHERE PTYPE WILL BE
MOSTLY SNOW...BUT GIVEN CONTINUED UNCERTAINTIES WITH PTYPE AND
ULTIMATE ACCUMS DECIDED TO KEEP AN SPS GOING HIGHLIGHTING THE
POTENTIAL FOR VERY HVY/WET SNOW THAT WILL BE DIFFICULT TO
SHOVEL/PLOW AND WILL LEAD TO VERY DIFFICULT TRAVEL CONDITIONS.
ON SUN...SFC HIGH PRES WILL NOSE INTO THE UPPER LAKES BEHIND
SYSTEM...BRINGING AN INFLUX OF DRIER AIR. DAYTIME TEMPS SHOULD
RECOVER WELL INTO THE 30S/LWR 40S IN THE AFTN WITH SOME INCREASE IN
SUNSHINE DURING THE DAY.
FCST FOR MON THRU THU REMAINS UNCERTAIN. MUCH OF THE FCST WILL HINGE
ON THE STRENGTH OF THE LINGERING ERN CANADA TROF UNDER THE WEAKENING
NEGATIVE AO/NAO PATTERN. OTHER THAN A SHOWING A WEAK NRN PLAINS
SHORTWAVE MOVING THROUGH THE AREA LATE SUNDAY NIGHT INTO
MONDAY...THE LATEST ECMWF IS SIMILAR TO RECENT RUNS SHOWING A
STRONGER AND MORE PERSISTENT ERN CANADIAN TROF WHICH KEEPS A DRIER
WNW FLOW ACROSS THE UPPER LAKES FOR THE EARLY PART OF NEXT WEEK.
THIS IDEA ALSO WOULD GO ALONG WITH THE GENERAL PERSISTENT PATTERN
WHICH HAS DOMINATED THE REGION FOR THE LAST SEVERAL WEEKS...ALTHOUGH
IT REMAINS TO BE SEEN HOW LONG PATTERN WILL PERSIST GIVEN EXPECT
WEAKENING OF HIGH LATITUDE BLOCKING. THE 12Z ECMWF DOES FINALLY
BRING PCPN INTO THE FCST AREA ON WED NIGHT AND THU...MAINLY IN FORM
OF SNOW...AS MAIN PIECE OF ENERGY FROM WRN CONUS TROF EJECTS NE
TOWARD THE GREAT LAKES. MEANWHILE...THE LATEST 00Z RUN OF THE GFS
QUICKLY WEAKENS THE ERN CANADIAN TROF AND PUSHES IT EAST ALLOWING
FOR A STRONG SRN STREAM SHORTWAVE TO EJECT TOWARD THE UPPER GREAT
LAKES FM BASE OF WRN CONUS TROF. THE GFS SHOWS 8H TEMPS RISING TO
10-12C BY TUE NIGHT INTO WED ACCOMPANIED BY A SLUG OF GULF MOISTURE
(250-300 PCT OF NORMAL PWAT VALUES) WHICH WOULD YIELD A THREAT OF
MODERATE TO HEAVY RAIN TO THE FCST AREA TUE NIGHT INTO WED. THE 12Z
GEM-NH GENERALLY LENDS MORE SUPPORT TO ECMWF SOLN ALTHOUGH IT ALSO
TENDS TO BREAK DOWN ERN CANADIAN TROF QUICKER THAN ECMWF. GIVEN
CONSIDERABLE MODEL UNCERTAINTY...WILL CONTINUE SIMPLE CONSENSUS
APPROACH TO FCST KEEPING ONLY SCHC POPS FOR MON INTO TUE THEN
INCREASE POPS TO 30-40 PCT CHC FOR WED AND THU WITH THE IDEA THAT
ERN CANADA TROF WILL WEAKEN ALLOWING FOR MORE ENERGY FROM WRN CONUS
TROF TO REACH UPPER GREAT LAKES. TEMPS SHOULD REMAIN BLO NORMAL THRU
THE PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 127 AM EDT FRI APR 5 2013
VFR CONDITIONS EXPECTED THROUGH THE PERIOD AT ALL TAF SITES. PUT IN
A CHANCE OF SOME SNOW LATE IN THE EVENING IN IWD WITH POSSIBILITY OF
MVFR CIGS AND VIS AS NEXT WEATHER SYSTEM NEARS. THIS WILL CAUSE
CLOUDS TO THICKEN AND LOWER AT CMX AND SAW IN THE EVENING.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 622 AM EDT FRI APR 5 2013
NW WINDS UP TO 25 KTS EARLY THIS MORNING OVER THE E HALF WILL
DIMINISH STEADILY TODAY AS HI PRES IS FORECAST TO BUILD OVER UPR MI
BY THIS AFTERNOON. LIGHT WINDS WILL SHIFT TO THE ESE AND INCREASE UP
TO 20 KTS TONIGHT AS THE NEXT LO PRES SYSTEM IS FORECAST TO MOVE TO
SW MN BY SAT MORNING. AS THE PRES GRADIENT TIGHTENS OVER LAKE SUP ON
SAT/SAT NIGHT TO THE N OF THE LO TRACKING THRU THE CENTRAL LAKES...
E-SE BACKING NE WINDS WILL INCREASE UP TO 25 TO 30 KTS BEFORE
DIMINISHING AND FURTHER BACKING TO THE N ON SUN AS TRAILING HI PRES
SHIFTS TOWARD THE UPPER LAKES. FOR EARLY NEXT WEEK...PLAN ON NE
WINDS UP TO 20 KTS ON THE SE FLANK OF HI PRES OVER CENTRAL CANADA.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...VOSS
AVIATION...07
MARINE...KC
AREA FORECAST DISCUSSION...UPDATED
NWS GAYLORD MI
122 AM EDT FRI APR 5 2013
.SYNOPSIS...
ISSUED AT 344 PM EDT THU APR 4 2013
A COLD FRONT IS MOVING THROUGH NORTHERN MICHIGAN...BRINGING A
PERIOD OF LIGHT RAIN AND SNOW FOR THIS AFTERNOON AND TONIGHT.
SETTLED WEATHER WILL RETURN FOR A SHORT TIME ON FRIDAY...BEFORE
ANOTHER STORM SYSTEM MOVES INTO NORTHERN MICHIGAN...BRINGING RAIN
AND SNOW MIXED FOR SATURDAY INTO SUNDAY.
&&
.UPDATE...
ISSUED AT 1246 AM EDT FRI APR 5 2013
CHANGES THIS HOUR: ONLY CHANGE AT THIS TIME IS TO END FOG MENTION
A LITTLE EARLIER OVERNIGHT AS VERY DRY UPSTREAM AIRMASS HAS
BROUGHT A QUICK END TO WHAT WAS LOCALLY DENSE FOG LATE LAST
EVENING. SHSN CHANCES TOWARDS DAYBREAK STILL LOOKING RATHER LOW
GIVEN THE PAUCITY OF MOISTURE UPSTREAM...BUT LOW END POPS STILL
ARE WARRANTED IN FAVORED NNW FLOW AREAS.
UPDATE ISSUED AT 1115 PM EDT THU APR 4 2013
ALL SYNOPTICALLY DRIVEN SNOW HAS EXITED OUT OF OUR CWA LATE THIS
EVENING ALONG THE DEPARTING COLD FRONT. RESIDUAL SCT/BKN LOW
CLOUDS BEHIND THE FRONT ARE SHOWING SIGNS OF BECOMING LAKE
ENHANCED PER LATEST 11U-3.9U SATELLITE LOOP. LAST FEW FRAMES FROM
KMQT 88D SHOWS THE BEGINNINGS OF SOME VERY LIGHT LAKE EFFECT
FLURRIES/SNOW SHOWERS THANKS TO CAA AND N/NW FLOW OFF OF LAKE
SUPERIOR. AIRMASS FILTERING IN BEHIND THE COLD FRONT IS QUITE
DRY...BUT WITH 850 MB TEMPS DROPPING INTO THE MID TEENS...EXPECT
AT LEAST SOME N/NW FLOW LAKE FLURRIES/LIGHT SNOW SHOWERS WILL
DEVELOP OVERNIGHT. LOW CLOUDS WILL DIMINISH OVERNIGHT AWAY FROM ANY
LAKE INFLUENCES AS DRIER SYNOPTIC AIR ADVECTS INTO THE REGION.
ALSO EXPECT AREAS OF FOG THAT DEVELOP ACROSS PORTIONS OF NRN LWR
MICHIGAN WILL EVENTUALLY DISSIPATE LATE TONIGHT/EARLY FRIDAY
THANKS TO THAT DRIER AIR. UPSTREAM DWPTS IN THE 20S CERTAINLY
SUPPORTS OVERNIGHT LOWS IN THE 20S.
UPDATE ISSUED AT 700 PM EDT THU APR 4 2013
LINE OF RAIN/SNOW SHOWERS ACCELERATED SE EARLY THIS EVENING IN
RESPONSE TO A 125 KT 300 MB JET MAX DIGGING INTO THE WRN GREAT
LAKES REGION. HAVE MADE SEVERAL MODIFICATIONS TO TIMING AS A
RESULT...AND ALL PRECIP ASSOCIATED WITH THE FRONT SHOULD CLEAR OUR
CWA WITHIN THE NEXT HOUR OR SO. SOME CLEARING WILL TAKE PLACE...
EXPECT FOR LOCATIONS DOWNSTREAM OF LAKES SUPERIOR AND MICHIGAN
UNDER THE DIRECTION OF N/NW FLOW. LAKE CLOUDS AND SOME
FLURRIES/LIGHT SNOW SHOWERS SHOULD DEVELOP WITHIN THESE AREAS AND
PERSIST THE REST OF THE NIGHT AND INTO FRIDAY.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 344 PM EDT THU APR 4 2013
THE CURRENT RADAR SHOWS A NARROW BAND OF PCPN SLOWLY DROPPING SOUTH
ACROSS NORTHERN LOWER MICHIGAN. THIS NARROW AREA OF PRECIPITATION IS
THE RESULT OF A COLD FRONT SINKING SOUTH OVER THE REGION. VIS SAT
AND SFC OBS SHOW LIMITED MOISTURE EITHER SIDE OF THE BOUNDARY...WITH
MOSTLY SUNNY SKIES OVER MUCH OF CENTRAL AND SOUTHERN MICHIGAN. SUN
OVER THE SRN CWA FROM EARLIER TODAY...HAS ALLOWED AFTERNOON TEMPS IN
THESE AREAS TO WARM QUICKLY INTO THE MID AND UPPER 40S...WHILE
TEMPS REMAIN IN THE 30S OVER ERN UPPER NORTH OF THE BOUNDARY.
OVERALL THE MAIN FORECAST CONCERNS TONIGHT THROUGH FRIDAY WILL BE
TIMING AND TYPE OF PCPN TONIGHT WITH THE APPROACHING FRONT...ALONG
WITH ANY LAKE INDUCED SNOWS FRIDAY ON THE BACKSIDE OF THE COLD
FRONT.
THE STORM SYSTEM CURRENTLY MOVING ACRS ONTARIO WILL QUICKLY EXIT
INTO QUEBEC THIS EVENING. A COLD FRONT ASSOCIATED WITH THIS SYSTEM...
WILL CONT TO DROP SOUTH ACRS NRN LWR MI THIS EVENING BEFORE EXITING
EAST. EXPECT THE FRONT TO HAVE CLEARED NORTHERN LOWER MICHIGAN
BTWN 03Z AND 06Z. THE ONLY PCPN ASSOCIATED WITH THIS BOUNDARY HAS
BEEN LOCATED RIGHT ALONG THE FRONT...DUE TO THE EXTREMELY DRY AIR
LOCATED OVER THE GREAT LAKES. HOWEVER SFC DEW PTS EVENTUALLY
INCREASED FROM THE TEENS INTO THE MID 20S OVER THE STRAITS AS THE
FRONT APPROACHED (ENOUGH TO GENERATE PCPN). HOWEVER PCPN TYPE AND
CHC OVER THE REST OF THE CWA WILL BE DIFFICULT THIS EVENING AS THE
FRONT DIPS SOUTH. TO THIS POINT...ALL OF THE PCPN HAS BEEN IN THE
FORM OF SNOW OVER ERN UPPER AND THE STRAITS. THE LATEST RUC MODEL
SOUNDINGS SHOW AN INVERTED V SIGNATURE IN THE LOWEST LAYERS FROM
GAYLORD SOUTH TO THE SAGINAW BAY THIS EVENING...WITH OTHERWISE
EXTREMELY DRY AIR ABOVE 850MB. ADDING COMPLICATIONS TO PCPN TYPE
THIS EVENING IS THE VERTICAL TEMP PROFILES...AS MOST OF NRN LWR
WARMED WELL INTO THE MID AND UPPER 40S DUE TO SOUTHWEST WINDS AND
FULL SUN IN ADVANCE OF THE FRONT. HOWEVER PROGGED 850MB WET BULB TEMPS
WOULD SUGGEST ENOUGH EVAP COOLING WITH ONSET OF ADVANCING MSTR TO AT
LEAST MENTION A RAIN/SNOW MIX. OVERALL WILL CONTINUE THE LATEST
TREND OF CHC POPS RAIN/SNOW MIXED OVER THE SRN HALF OF THE CWA AND
SAGINAW BAY INTO THIS EVENING.
COLDER AIR AND NORTHWEST FLOW RE-SETTLES INTO THE REGION OVERNIGHT
AND FRIDAY ON THE BACK SIDE OF THE EXITING BOUNDARY. 850MB TEMPS
QUICKLY DROP FROM ARND -4C THIS EVENING TO BETWEEN -12C AND -14C BY
12Z FRIDAY. SFC-850MB WINDS TURN FROM THE SOUTHWEST THIS EVENING IN
ADVANCE OF THE BOUNDARY TO NNW FRIDAY. MODEL SOUNDINGS SUGGEST INVERSION
HEIGHTS INCREASING TO NEAR 5K FT WHILE LINGERING LOW LVL MSTR EXTENDS
TO AROUND THE -12C ISOTHERM. OVERALL MENTION CHC POPS IN NORTH FLOW
SNOW BELTS EARLY FRIDAY. OTHERWISE WILL MENTION AT LEAST PARTLY
SUNNY SKIES OVER THE REST OF THE CWA FRIDAY. WILL MENTION COOLER AFTN
TEMPS FRIDAY...RANGING FROM AROUND FREEZING OVER ERN UPPER AND THE
STRAITS TO THE LOWER 40S NEAR SAGINAW BAY.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 344 PM EDT THU APR 4 2013
LITTLE CHANGE FROM WHAT WAS SEEN YESTERDAY...WITH STILL PLENTY OF
POTENTIAL FOR A VERY ACTIVE NEXT 7 DAYS OF WEATHER AS PERSISTENT
-AO RELAXES AND DEEP SOUTHWEST MOISTURE RICH FLOW DEVELOPS ON
FRONTSIDE OF DIGGING INTERMOUNTAIN WEST ENERGY. BIG WILD CARD
REMAINS POTENTIAL INTERACTION WITH POLAR LOW SET TO ROTATE ACROSS
EASTERN CANADA. EVENTUAL PLACEMENT OF THIS FEATURE WILL BE KEY IN
DETERMINING LOCATION OF INTENSE LOW LEVEL THERMAL BOUNDARY AND
SUBSEQUENT PATHWAY FOR ENERGY ROTATING OUT OF WESTERN TROUGH AXIS.
WHILE ABOVE REMAINS A VERY LOW CONFIDENCE PORTION OF THE
FORECAST...LEAD WAVE APPROACHING THE PACIFIC NORTHWEST (NICELY
ILLUSTRATED ON LATEST WATER VAPOR IMAGERY) NOW WELL AGREED UPON TO
IMPACT OUR WEATHER INTO THE START OF THIS WEEKEND. THIS WAVE WILL
BRING ANOTHER BOUT OF WINTRY WEATHER TO THE NORTH WOODS
SATURDAY...WITH INCREASING CONFIDENCE PARTS OF EASTERN UPPER WILL
SEE A PERIOD OF ACCUMULATING SNOW. FORECAST CONCERNS INITIALLY
DEAL WITH THIS LATTER SYSTEM...SPECIFICALLY SNOWFALL ACCUMULATIONS
FOR EASTERN UPPER. MUCH MORE OF PROBABILISTIC APPROACH TAKING FOR
THE REMAINDER OF THE FORECAST...WITH AT LEAST SOME ATTEMPT AT
ADDRESSING MULTI- PERIOD PRECIP CHANCES AND TEMPERATURE TRENDS.
GUIDANCE HAS LOCKED IN A SOLUTION SENDING PACIFIC NORTHWEST WAVE
RAPIDLY EAST INTO THE NORTHERN PLAIN FRIDAY NIGHT...AND THROUGH
NORTHERN MICHIGAN BY SATURDAY NIGHT. WEAKISH COUPLED JET STRUCTURE
AND LOW LEVEL THERMAL BOUNDARY EXPECTED TO ENTICE RESPECTABLE
SURFACE LOW PRESSURE DEVELOPMENT WITH THIS MID LEVEL WAVE...ITSELF
EXPECTED TO SLICE THROUGH THE HEART OF NORTHERN LOWER MICHIGAN
SATURDAY EVENING. ALTHOUGH WAVE ITSELF AND SURFACE FEATURE NOTHING
TO WRITE HOME ABOUT...ACCOMPANYING DYNAMICS REMAIN IMPRESSIVE INDEED.
MULTI-PERIOD TRENDS CONTINUE TO SUPPORT AGGRESSIVE WAA DRIVEN
DYNAMICS...WITH NEAR 60 KNOT SOUTHWEST FLOW LOW LEVEL JET
PERPENDICULAR TO THE 290K-295K PRESSURE SURFACES. DEEP LAYER FGEN
SIGNAL ALSO PRESENT ALONG RETREATING COLD DOME...COLLOCATED NICELY
WITH MAX WAA UPGLIDE ON NOSE OF LOW LEVEL JET. BEST JUXTAPOSITION OF
THE ABOVE EXPECTED ACROSS FAR NORTHERN LOWER AND AREAS NORTH OF THE
BRIDGE SATURDAY INTO SATURDAY EVENING. SYSTEM HAS A NICE SUBTROPICAL
PACIFIC MOISTURE PLUME ALREADY ASSOCIATED WITH IT...SOME OF WHICH
WILL BE ADVECTED INTO OUR AREA AS SYSTEM APPROACHES. COMBINE THIS
WITH BRIEF WINDOW FOR SOME WESTERN GULF OF MEXICO MOISTURE
CONTRIBUTION...AND PWAT VALUES SURGE TO AOA 0.75 INCHES LEVELS BY
LATER SATURDAY. SAID ISENTROPIC SURFACES ALSO SHOW VERY RESPECTABLE
MOISTURE...WITH MIXING RATIOS EXCEEDING 4 G/KG. LITTLE DOUBT SYSTEM
HAS ALL THE EARMARKS TO BE A RATHER SUBSTANTIAL PRECIP PRODUCER...
ALTHOUGH EXACTLY WHAT TYPE THAT PRECIP TAKES REMAINS A FORMIDABLE
CHALLENGE. WILL USE ROCK-STEADY ECMWF DEPICTIONS FOR THERMAL FIELDS.
THIS CONTINUES TO SUGGEST MAINLY SNOW AT THE ONSET EARLY
SATURDAY...RAPIDLY CHANGING OVER TO LIQUID FROM SOUTHWEST TO
NORTHEAST ACROSS NORTHERN LOWER MICHIGAN DURING THE MORNING. COULD
SEE SOME MINOR SNOW ACCUMULATIONS...ON THE ORDER OF AN INCH OR
SO...ESPECIALLY ACROSS THE HIGHER TERRAIN AREAS. WILL NEED TO WATCH
FOR A PERIOD OF FREEZING RAIN AS WAA STRENGTHENS JUST OFF THE DECK.
THIS SHOULD BE SHORT-LIVED EVENT (IF IT OCCURS AT ALL) AND NOT
WORTHY OF A MENTION IN THE FORECAST. MUCH BIGGER PRECIP TYPE
CHALLENGE ACROSS EASTERN UPPER...WITH STRONG DYNAMICS POSSIBLY
OVERCOMING MARGINAL THERMAL PROFILES TO KEEP PRECIP MAINLY ALL
SNOW...ESPECIALLY ALONG AND NORTH OF M-28. MODEL QPF FIELDS SOMEWHAT
DISCONCERTING...WITH PROGS SUPPORTING A HALF INCH OR MORE OF LIQUID
EQUIVALENT PRECIP BY LATER SATURDAY NIGHT. HEAVIER AMOUNTS NO DOUBT
POSSIBLE GIVEN AMOUNT OF EARLIER MENTIONED DYNAMICS. SNOW RATIOS
WILL NOT BE GREAT...ESPECIALLY SATURDAY AFTERNOON...WHEN SURFACE
READINGS WILL LIKELY EXCEED FREEZING AND HIGH APRIL SUN ANGLE TAKES
HOLD. STILL...COULD EASILY SEE SEVERAL INCHES OF HEAVY WET SNOW
ACCUMULATION BY LATER SATURDAY NIGHT...WITH PERIODS OF HIGH
INTENSITY SNOWFALL. NO HEADLINES FORTHCOMING ON THIS SHIFT...BUT IF
ABOVE COMES TO FRUITION...COULD SEE ADVISORY LEVEL SNOW AMOUNTS FOR
AT LEAST PARTS OF EASTERN UPPER. STAY TUNED! SYSTEM WINDS DOWN
QUICKLY LATE SATURDAY NIGHT...LEAVING BEHIND A DRY SUNDAY AND SUNDAY
EVENING.
CONFIDENCE DROPS REMARKABLY HEADING THROUGH NEXT WORK WEEK...WITH
GUIDANCE STRUGGLING WITH KEY INTERACTIONS TALKED ABOUT IN THE LEAD
PARAGRAPH. PLENTY OF POTENTIAL FOR ADDITIONAL SIGNIFICANT
SYSTEMS...WITH SOME DECENT SUPPORT FOR ONE SUCH SYSTEM TO IMPACT OUR
AREA TO KICK OFF THE WEEK. EXACTLY HOW FAR NORTH THIS SYSTEM RIDES UP
THROUGH THE OHIO VALLEY/SOUTHERN LAKES STILL FAR FROM BEING
DETERMINED. DEPENDING ON SUCH...MAY SEE ENOUGH COLD AIR ALONG THE
NORTHERN PERIPHERY OF ITS PRECIP SHIELD TO SUPPORT SOME WINTRY
WEATHER. NO NEED TO GET TOO SPECIFIC...AND WILL BE FORCED TO RUN
WITH A GUIDANCE CONSENSUS BLEND UNTIL A MORE DETERMINISTIC APPROACH
CAN BE UTILIZED. SAME STORY HEADING THROUGH THE REMAINDER OF THE
WEEK...WITH AGAIN THE POTENTIAL FOR ANOTHER WAVE TO ROTATE NORTHEAST
OUT OF THE SOUTHERN PLAINS. TIMING AND PLACEMENT OF SUCH ALL OVER
THE BOARD...AS IT WILL LIKELY REMAIN WITH BAROCLINIC AXIS SUBJECT TO
MANY CHANGES PER CANADIAN TROUGHING AND PASSAGE OF EARLIER IN THE
WEEK SYSTEMS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 121 AM EDT FRI APR 5 2013
SUMMARY: HIGH PRESSURE WILL BUILD INTO THE GREAT LAKES REGION TODAY
WITH SOME MORNING LAKE ENHANCED CLOUDINESS GIVING WAY TO AMPLE
SUNSHINE UNDER DIMINISHING NORTHWESTERLY WINDS.
RESTRICTIONS: VFR CONDITIONS EXPECTED THROUGH THE UPCOMING TAF
PERIOD. CAN/T RULE OUT A FEW FLURRIES FROM THE PRE-DAWN HOURS
THROUGH MID MORNING AT TVC/MBL...BUT INCOMING AIRMASS IS TOO DRY TOO
SUPPORT SIGNIFICANT SHSN DEVELOPMENT. CIGS MAY DROP TO 3-4KFT FOR A
TIME AT TVC /AND POTENTIALLY AT MBL-PLN/...BUT EXPECT THESE TO
REMAIN VFR BEFORE SCATTERING OUT BY LATE MORNING.
WINDS: NORTHWEST WINDS 5-10KTS WILL CONTINUE THROUGH THE OVERNIGHT
BEFORE INCREASING TO 10G16KTS FOR THE DAY ON FRIDAY WHILE VEERING
NORTH NORTHWEST. WINDS WILL DIMINISH TO CALM OR LIGHT/VARIABLE THIS
EVENING.
&&
.MARINE...
ISSUED AT 344 PM EDT THU APR 4 2013
GUSTY SOUTHWEST WINDS IN ADVANCE OF A FRONTAL BOUNDARY DROPPING
SOUTH OVER NRN MI...WILL TURN NORTHWEST OVERNIGHT AND REMAIN BREEZY
ON THE BACKSIDE OF THE EXITING BOUNDARY. RAIN/SNOW MIXED PCPN WILL
AFFECT NRN MI NEARSHORE WATERS THIS EVENING AS BOUNDARY DROPS
SOUTH...WITH SOME LAKE SNOWS POSSIBLE FRIDAY BEHIND THE FRONT.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...ARNOTT
SYNOPSIS...KAB
SHORT TERM...SWR
LONG TERM...MSB
AVIATION...ARNOTT
MARINE...SWR
AREA FORECAST DISCUSSION...UPDATED
NWS GAYLORD MI
1248 AM EDT FRI APR 5 2013
.SYNOPSIS...
ISSUED AT 344 PM EDT THU APR 4 2013
A COLD FRONT IS MOVING THROUGH NORTHERN MICHIGAN...BRINGING A
PERIOD OF LIGHT RAIN AND SNOW FOR THIS AFTERNOON AND TONIGHT.
SETTLED WEATHER WILL RETURN FOR A SHORT TIME ON FRIDAY...BEFORE
ANOTHER STORM SYSTEM MOVES INTO NORTHERN MICHIGAN...BRINGING RAIN
AND SNOW MIXED FOR SATURDAY INTO SUNDAY.
&&
.UPDATE...
ISSUED AT 1246 AM EDT FRI APR 5 2013
CHANGES THIS HOUR: ONLY CHANGE AT THIS TIME IS TO END FOG MENTION
A LITTLE EARLIER OVERNIGHT AS VERY DRY UPSTREAM AIRMASS HAS
BROUGHT A QUICK END TO WHAT WAS LOCALLY DENSE FOG LATE LAST
EVENING. SHSN CHANCES TOWARDS DAYBREAK STILL LOOKING RATHER LOW
GIVEN THE PAUCITY OF MOISTURE UPSTREAM...BUT LOW END POPS STILL
ARE WARRANTED IN FAVORED NNW FLOW AREAS.
UPDATE ISSUED AT 1115 PM EDT THU APR 4 2013
ALL SYNOPTICALLY DRIVEN SNOW HAS EXITED OUT OF OUR CWA LATE THIS
EVENING ALONG THE DEPARTING COLD FRONT. RESIDUAL SCT/BKN LOW
CLOUDS BEHIND THE FRONT ARE SHOWING SIGNS OF BECOMING LAKE
ENHANCED PER LATEST 11U-3.9U SATELLITE LOOP. LAST FEW FRAMES FROM
KMQT 88D SHOWS THE BEGINNINGS OF SOME VERY LIGHT LAKE EFFECT
FLURRIES/SNOW SHOWERS THANKS TO CAA AND N/NW FLOW OFF OF LAKE
SUPERIOR. AIRMASS FILTERING IN BEHIND THE COLD FRONT IS QUITE
DRY...BUT WITH 850 MB TEMPS DROPPING INTO THE MID TEENS...EXPECT
AT LEAST SOME N/NW FLOW LAKE FLURRIES/LIGHT SNOW SHOWERS WILL
DEVELOP OVERNIGHT. LOW CLOUDS WILL DIMINISH OVERNIGHT AWAY FROM ANY
LAKE INFLUENCES AS DRIER SYNOPTIC AIR ADVECTS INTO THE REGION.
ALSO EXPECT AREAS OF FOG THAT DEVELOP ACROSS PORTIONS OF NRN LWR
MICHIGAN WILL EVENTUALLY DISSIPATE LATE TONIGHT/EARLY FRIDAY
THANKS TO THAT DRIER AIR. UPSTREAM DWPTS IN THE 20S CERTAINLY
SUPPORTS OVERNIGHT LOWS IN THE 20S.
UPDATE ISSUED AT 700 PM EDT THU APR 4 2013
LINE OF RAIN/SNOW SHOWERS ACCELERATED SE EARLY THIS EVENING IN
RESPONSE TO A 125 KT 300 MB JET MAX DIGGING INTO THE WRN GREAT
LAKES REGION. HAVE MADE SEVERAL MODIFICATIONS TO TIMING AS A
RESULT...AND ALL PRECIP ASSOCIATED WITH THE FRONT SHOULD CLEAR OUR
CWA WITHIN THE NEXT HOUR OR SO. SOME CLEARING WILL TAKE PLACE...
EXPECT FOR LOCATIONS DOWNSTREAM OF LAKES SUPERIOR AND MICHIGAN
UNDER THE DIRECTION OF N/NW FLOW. LAKE CLOUDS AND SOME
FLURRIES/LIGHT SNOW SHOWERS SHOULD DEVELOP WITHIN THESE AREAS AND
PERSIST THE REST OF THE NIGHT AND INTO FRIDAY.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 344 PM EDT THU APR 4 2013
THE CURRENT RADAR SHOWS A NARROW BAND OF PCPN SLOWLY DROPPING SOUTH
ACROSS NORTHERN LOWER MICHIGAN. THIS NARROW AREA OF PRECIPITATION IS
THE RESULT OF A COLD FRONT SINKING SOUTH OVER THE REGION. VIS SAT
AND SFC OBS SHOW LIMITED MOISTURE EITHER SIDE OF THE BOUNDARY...WITH
MOSTLY SUNNY SKIES OVER MUCH OF CENTRAL AND SOUTHERN MICHIGAN. SUN
OVER THE SRN CWA FROM EARLIER TODAY...HAS ALLOWED AFTERNOON TEMPS IN
THESE AREAS TO WARM QUICKLY INTO THE MID AND UPPER 40S...WHILE
TEMPS REMAIN IN THE 30S OVER ERN UPPER NORTH OF THE BOUNDARY.
OVERALL THE MAIN FORECAST CONCERNS TONIGHT THROUGH FRIDAY WILL BE
TIMING AND TYPE OF PCPN TONIGHT WITH THE APPROACHING FRONT...ALONG
WITH ANY LAKE INDUCED SNOWS FRIDAY ON THE BACKSIDE OF THE COLD
FRONT.
THE STORM SYSTEM CURRENTLY MOVING ACRS ONTARIO WILL QUICKLY EXIT
INTO QUEBEC THIS EVENING. A COLD FRONT ASSOCIATED WITH THIS SYSTEM...
WILL CONT TO DROP SOUTH ACRS NRN LWR MI THIS EVENING BEFORE EXITING
EAST. EXPECT THE FRONT TO HAVE CLEARED NORTHERN LOWER MICHIGAN
BTWN 03Z AND 06Z. THE ONLY PCPN ASSOCIATED WITH THIS BOUNDARY HAS
BEEN LOCATED RIGHT ALONG THE FRONT...DUE TO THE EXTREMELY DRY AIR
LOCATED OVER THE GREAT LAKES. HOWEVER SFC DEW PTS EVENTUALLY
INCREASED FROM THE TEENS INTO THE MID 20S OVER THE STRAITS AS THE
FRONT APPROACHED (ENOUGH TO GENERATE PCPN). HOWEVER PCPN TYPE AND
CHC OVER THE REST OF THE CWA WILL BE DIFFICULT THIS EVENING AS THE
FRONT DIPS SOUTH. TO THIS POINT...ALL OF THE PCPN HAS BEEN IN THE
FORM OF SNOW OVER ERN UPPER AND THE STRAITS. THE LATEST RUC MODEL
SOUNDINGS SHOW AN INVERTED V SIGNATURE IN THE LOWEST LAYERS FROM
GAYLORD SOUTH TO THE SAGINAW BAY THIS EVENING...WITH OTHERWISE
EXTREMELY DRY AIR ABOVE 850MB. ADDING COMPLICATIONS TO PCPN TYPE
THIS EVENING IS THE VERTICAL TEMP PROFILES...AS MOST OF NRN LWR
WARMED WELL INTO THE MID AND UPPER 40S DUE TO SOUTHWEST WINDS AND
FULL SUN IN ADVANCE OF THE FRONT. HOWEVER PROGGED 850MB WET BULB TEMPS
WOULD SUGGEST ENOUGH EVAP COOLING WITH ONSET OF ADVANCING MSTR TO AT
LEAST MENTION A RAIN/SNOW MIX. OVERALL WILL CONTINUE THE LATEST
TREND OF CHC POPS RAIN/SNOW MIXED OVER THE SRN HALF OF THE CWA AND
SAGINAW BAY INTO THIS EVENING.
COLDER AIR AND NORTHWEST FLOW RE-SETTLES INTO THE REGION OVERNIGHT
AND FRIDAY ON THE BACK SIDE OF THE EXITING BOUNDARY. 850MB TEMPS
QUICKLY DROP FROM ARND -4C THIS EVENING TO BETWEEN -12C AND -14C BY
12Z FRIDAY. SFC-850MB WINDS TURN FROM THE SOUTHWEST THIS EVENING IN
ADVANCE OF THE BOUNDARY TO NNW FRIDAY. MODEL SOUNDINGS SUGGEST INVERSION
HEIGHTS INCREASING TO NEAR 5K FT WHILE LINGERING LOW LVL MSTR EXTENDS
TO AROUND THE -12C ISOTHERM. OVERALL MENTION CHC POPS IN NORTH FLOW
SNOW BELTS EARLY FRIDAY. OTHERWISE WILL MENTION AT LEAST PARTLY
SUNNY SKIES OVER THE REST OF THE CWA FRIDAY. WILL MENTION COOLER AFTN
TEMPS FRIDAY...RANGING FROM AROUND FREEZING OVER ERN UPPER AND THE
STRAITS TO THE LOWER 40S NEAR SAGINAW BAY.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 344 PM EDT THU APR 4 2013
LITTLE CHANGE FROM WHAT WAS SEEN YESTERDAY...WITH STILL PLENTY OF
POTENTIAL FOR A VERY ACTIVE NEXT 7 DAYS OF WEATHER AS PERSISTENT
-AO RELAXES AND DEEP SOUTHWEST MOISTURE RICH FLOW DEVELOPS ON
FRONTSIDE OF DIGGING INTERMOUNTAIN WEST ENERGY. BIG WILD CARD
REMAINS POTENTIAL INTERACTION WITH POLAR LOW SET TO ROTATE ACROSS
EASTERN CANADA. EVENTUAL PLACEMENT OF THIS FEATURE WILL BE KEY IN
DETERMINING LOCATION OF INTENSE LOW LEVEL THERMAL BOUNDARY AND
SUBSEQUENT PATHWAY FOR ENERGY ROTATING OUT OF WESTERN TROUGH AXIS.
WHILE ABOVE REMAINS A VERY LOW CONFIDENCE PORTION OF THE
FORECAST...LEAD WAVE APPROACHING THE PACIFIC NORTHWEST (NICELY
ILLUSTRATED ON LATEST WATER VAPOR IMAGERY) NOW WELL AGREED UPON TO
IMPACT OUR WEATHER INTO THE START OF THIS WEEKEND. THIS WAVE WILL
BRING ANOTHER BOUT OF WINTRY WEATHER TO THE NORTH WOODS
SATURDAY...WITH INCREASING CONFIDENCE PARTS OF EASTERN UPPER WILL
SEE A PERIOD OF ACCUMULATING SNOW. FORECAST CONCERNS INITIALLY
DEAL WITH THIS LATTER SYSTEM...SPECIFICALLY SNOWFALL ACCUMULATIONS
FOR EASTERN UPPER. MUCH MORE OF PROBABILISTIC APPROACH TAKING FOR
THE REMAINDER OF THE FORECAST...WITH AT LEAST SOME ATTEMPT AT
ADDRESSING MULTI- PERIOD PRECIP CHANCES AND TEMPERATURE TRENDS.
GUIDANCE HAS LOCKED IN A SOLUTION SENDING PACIFIC NORTHWEST WAVE
RAPIDLY EAST INTO THE NORTHERN PLAIN FRIDAY NIGHT...AND THROUGH
NORTHERN MICHIGAN BY SATURDAY NIGHT. WEAKISH COUPLED JET STRUCTURE
AND LOW LEVEL THERMAL BOUNDARY EXPECTED TO ENTICE RESPECTABLE
SURFACE LOW PRESSURE DEVELOPMENT WITH THIS MID LEVEL WAVE...ITSELF
EXPECTED TO SLICE THROUGH THE HEART OF NORTHERN LOWER MICHIGAN
SATURDAY EVENING. ALTHOUGH WAVE ITSELF AND SURFACE FEATURE NOTHING
TO WRITE HOME ABOUT...ACCOMPANYING DYNAMICS REMAIN IMPRESSIVE INDEED.
MULTI-PERIOD TRENDS CONTINUE TO SUPPORT AGGRESSIVE WAA DRIVEN
DYNAMICS...WITH NEAR 60 KNOT SOUTHWEST FLOW LOW LEVEL JET
PERPENDICULAR TO THE 290K-295K PRESSURE SURFACES. DEEP LAYER FGEN
SIGNAL ALSO PRESENT ALONG RETREATING COLD DOME...COLLOCATED NICELY
WITH MAX WAA UPGLIDE ON NOSE OF LOW LEVEL JET. BEST JUXTAPOSITION OF
THE ABOVE EXPECTED ACROSS FAR NORTHERN LOWER AND AREAS NORTH OF THE
BRIDGE SATURDAY INTO SATURDAY EVENING. SYSTEM HAS A NICE SUBTROPICAL
PACIFIC MOISTURE PLUME ALREADY ASSOCIATED WITH IT...SOME OF WHICH
WILL BE ADVECTED INTO OUR AREA AS SYSTEM APPROACHES. COMBINE THIS
WITH BRIEF WINDOW FOR SOME WESTERN GULF OF MEXICO MOISTURE
CONTRIBUTION...AND PWAT VALUES SURGE TO AOA 0.75 INCHES LEVELS BY
LATER SATURDAY. SAID ISENTROPIC SURFACES ALSO SHOW VERY RESPECTABLE
MOISTURE...WITH MIXING RATIOS EXCEEDING 4 G/KG. LITTLE DOUBT SYSTEM
HAS ALL THE EARMARKS TO BE A RATHER SUBSTANTIAL PRECIP PRODUCER...
ALTHOUGH EXACTLY WHAT TYPE THAT PRECIP TAKES REMAINS A FORMIDABLE
CHALLENGE. WILL USE ROCK-STEADY ECMWF DEPICTIONS FOR THERMAL FIELDS.
THIS CONTINUES TO SUGGEST MAINLY SNOW AT THE ONSET EARLY
SATURDAY...RAPIDLY CHANGING OVER TO LIQUID FROM SOUTHWEST TO
NORTHEAST ACROSS NORTHERN LOWER MICHIGAN DURING THE MORNING. COULD
SEE SOME MINOR SNOW ACCUMULATIONS...ON THE ORDER OF AN INCH OR
SO...ESPECIALLY ACROSS THE HIGHER TERRAIN AREAS. WILL NEED TO WATCH
FOR A PERIOD OF FREEZING RAIN AS WAA STRENGTHENS JUST OFF THE DECK.
THIS SHOULD BE SHORT-LIVED EVENT (IF IT OCCURS AT ALL) AND NOT
WORTHY OF A MENTION IN THE FORECAST. MUCH BIGGER PRECIP TYPE
CHALLENGE ACROSS EASTERN UPPER...WITH STRONG DYNAMICS POSSIBLY
OVERCOMING MARGINAL THERMAL PROFILES TO KEEP PRECIP MAINLY ALL
SNOW...ESPECIALLY ALONG AND NORTH OF M-28. MODEL QPF FIELDS SOMEWHAT
DISCONCERTING...WITH PROGS SUPPORTING A HALF INCH OR MORE OF LIQUID
EQUIVALENT PRECIP BY LATER SATURDAY NIGHT. HEAVIER AMOUNTS NO DOUBT
POSSIBLE GIVEN AMOUNT OF EARLIER MENTIONED DYNAMICS. SNOW RATIOS
WILL NOT BE GREAT...ESPECIALLY SATURDAY AFTERNOON...WHEN SURFACE
READINGS WILL LIKELY EXCEED FREEZING AND HIGH APRIL SUN ANGLE TAKES
HOLD. STILL...COULD EASILY SEE SEVERAL INCHES OF HEAVY WET SNOW
ACCUMULATION BY LATER SATURDAY NIGHT...WITH PERIODS OF HIGH
INTENSITY SNOWFALL. NO HEADLINES FORTHCOMING ON THIS SHIFT...BUT IF
ABOVE COMES TO FRUITION...COULD SEE ADVISORY LEVEL SNOW AMOUNTS FOR
AT LEAST PARTS OF EASTERN UPPER. STAY TUNED! SYSTEM WINDS DOWN
QUICKLY LATE SATURDAY NIGHT...LEAVING BEHIND A DRY SUNDAY AND SUNDAY
EVENING.
CONFIDENCE DROPS REMARKABLY HEADING THROUGH NEXT WORK WEEK...WITH
GUIDANCE STRUGGLING WITH KEY INTERACTIONS TALKED ABOUT IN THE LEAD
PARAGRAPH. PLENTY OF POTENTIAL FOR ADDITIONAL SIGNIFICANT
SYSTEMS...WITH SOME DECENT SUPPORT FOR ONE SUCH SYSTEM TO IMPACT OUR
AREA TO KICK OFF THE WEEK. EXACTLY HOW FAR NORTH THIS SYSTEM RIDES UP
THROUGH THE OHIO VALLEY/SOUTHERN LAKES STILL FAR FROM BEING
DETERMINED. DEPENDING ON SUCH...MAY SEE ENOUGH COLD AIR ALONG THE
NORTHERN PERIPHERY OF ITS PRECIP SHIELD TO SUPPORT SOME WINTRY
WEATHER. NO NEED TO GET TOO SPECIFIC...AND WILL BE FORCED TO RUN
WITH A GUIDANCE CONSENSUS BLEND UNTIL A MORE DETERMINISTIC APPROACH
CAN BE UTILIZED. SAME STORY HEADING THROUGH THE REMAINDER OF THE
WEEK...WITH AGAIN THE POTENTIAL FOR ANOTHER WAVE TO ROTATE NORTHEAST
OUT OF THE SOUTHERN PLAINS. TIMING AND PLACEMENT OF SUCH ALL OVER
THE BOARD...AS IT WILL LIKELY REMAIN WITH BAROCLINIC AXIS SUBJECT TO
MANY CHANGES PER CANADIAN TROUGHING AND PASSAGE OF EARLIER IN THE
WEEK SYSTEMS.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 700 PM EDT THU APR 4 2013
OVERALL CONDITIONS WILL REMAIN VFR THRU FRIDAY EVENING AS HIGH
PRESSURE...SUBSIDENCE AND DRY AIR SLOWLY BUILD INTO NRN MICHIGAN.
RESIDUAL LOW CLOUDS BEHIND THE COLD FRONT CURRENTLY TRACKING THRU
NRN LWR MICHIGAN WILL DIMINISH THIS EVENING...EXCEPT FOR LOCATIONS
DOWNWIND OF LAKES SUPERIOR AND MICHIGAN UNDER THE DIRECTION OF
N/NW FLOW. A FEW FLURRIES OR LIGHT LAKE SNOW SHOWERS ARE POSSIBLE
FOR TVC AND MBL TONIGHT...BUT CHANCES ARE LOW AND WILL LEAVE OUT
OF THE TAF FOR NOW. N/NW WINDS BEHIND THE COLD FRONT WILL
PERIODICALLY GUST TO 20 KTS.
&&
.MARINE...
ISSUED AT 344 PM EDT THU APR 4 2013
GUSTY SOUTHWEST WINDS IN ADVANCE OF A FRONTAL BOUNDARY DROPPING
SOUTH OVER NRN MI...WILL TURN NORTHWEST OVERNIGHT AND REMAIN BREEZY
ON THE BACKSIDE OF THE EXITING BOUNDARY. RAIN/SNOW MIXED PCPN WILL
AFFECT NRN MI NEARSHORE WATERS THIS EVENING AS BOUNDARY DROPS
SOUTH...WITH SOME LAKE SNOWS POSSIBLE FRIDAY BEHIND THE FRONT.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...ARNOTT
SYNOPSIS...KAB
SHORT TERM...SWR
LONG TERM...MSB
AVIATION...MR
MARINE...SWR
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
912 PM CDT SAT APR 6 2013
.UPDATE...
ISSUED AT 852 PM CDT SAT APR 6 2013
A WEAK COLD FRONT NOW EXTENDING FROM EASTERN IOWA SWWD THROUGH
CENTRAL MO HAS BEEN THE FOCUS OF SOME SHOWERS THIS EVENING IN
OUR CWA...WITH THUNDERSTORMS OVER EASTERN IOWA AND NW ILLINOIS.
MODELS THIS EVENING...INCLUDING THE HRRR AND RUC...HAVE
CONTINUED TO INDICATE A NARROW BAND OF SHOWERS TO PERSIST ALONG
AND JUST AHEAD OF THE FRONT AS IT MOVES THROUGH OUR CWA TONIGHT.
HAVE UPPED POPS ACROSS WEST CENTRAL IL THROUGH MIDNIGHT AND
INCLUDED A MENTION OF THUNDER GIVEN MUCAPE VALUES BETWEEN 100-200
J/KG OVER EASTERN IOWA AND NW ILLINOIS WHICH HAVE BEEN ENOUGH TO
RESULT IN A FAIRLY SOLID LINE OF THUNDERSTORMS THIS EVENING OVER
THAT AREA. HOWEVER...GIVEN MUCH OF THE FORCING REMAINS ANCHORED
NORTH OF THE CWA...A CONTINUED MENTION OF SOME SPOTTY SHOWERS
REMAINS SUFFICIENT FOR THE REMAINDER OF THE AREA. ASIDE FROM THE
AFOREMENTIONED CHANGES...THE REST OF THE FORECAST REMAINS ON TRACK
THIS EVENING...WITH ONLY MINOR CHANGES NEEDED TO ACCOUNT FOR NEAR
TERM TEMPERATURE TRENDS.
JP
&&
.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 322 PM CDT SAT APR 6 2013
THE WEAK COLD FRONT NOW EXTENDING THROUGH NW MO WILL MOVE SEWD
INTO THE REGION TONIGHT AS THE ASSOCIATED SHORT WAVE TROF TRACKS
ACROSS THE UPPER MS VALLEY INTO THE GREAT LAKES. MODEL CONSENSUS
IS THE FRONT SHOULD BE IN THE VICINITY OF THE I-70 CORRIDOR AT 12Z
SUNDAY. PRESENTLY THERE IS NOT MUCH MORE THAN MID CLOUDS AND
SPINKLES OR A SPOT SHOWER AHEAD OF THE FRONT. SOME OF THE EXPLICIT
GUIDANCE SUGGESTS A NARROW BROKEN LINE OF SHOWERS/THUNDERSTORMS
WILL DEVELOP ALONG THE FRONT AS IT PUSHES INTO THE CWA. THIS LOOKS
A BIT OVERDONE HOWEVER...AS THE FORCING IS WEAK AND OBSERVED
MUCAPES ARE LESS THAN 100 J/KJ. CURRENT THINKING IS THERE MAY BE
SOME SPOTTY SHOWERS WITH THE FRONT...PRIMARILY FROM EASTERN MO
INTO WESTERN ILLINOIS. TEMPERTURES ON SUNDAY SHOULD BE AT LEAST
COMPARABLE TO TODAY.
THE EAST-WEST ORIENTED FRONT MAY OOZE A TAD FURTHER SOUTH ON
SUNDAY MORNING BUT IS EXPECTED TO BECOME QUASI-STATIONARY IN THE
VICINITY OF THE I-70 CORRIDOR IN THE AFTERNOON. THE PRECIPITATION
THREAT SEEMS TO LARGELY BE DEPENDENT ON THE INSTABILITY WHICH
LOOKS A BIT OVERDONE IN THESE INITIAL STAGES OF THE RETURN FLOW
OWING TO TOO HIGH OF SURFACE DEW POINTS. THINKING AT THIS TIME IS
THERE COULD BE SOME SCATTERED SHOWERS OR THUNDERSTORMS WITHIN THE
BROAD FRONTAL ZONE...ESPECIALLY IN CENTRAL MO. THE PRECIPITATION
CHANCES ARE EXPECTED TO RAMP UP CONSIDERABLY ON SUNDAY NIGHT
ASSOCIATED WITH FORCING VIA A MIGRATORY SHORT WAVE WITHIN THE WSW
FLOW ALOFT AND INTENSIFYING AND VEERING SWLY LLJ. THE MAIN FOCUS
SHOULD BE ALONG AND NORTH OF I-70 WITHIN THE COOL SECTOR NORTH OF
THE RETREATING BOUNDARY.
GLASS
.LONG TERM...(MONDAY THROUGH NEXT SATURDAY)
ISSUED AT 322 PM CDT SAT APR 6 2013
FROM MONDAY INTO TUESDAY THE DETAILS IN THE FORECAST BECOME A BIT
MORE DIFFICULT TO RESOLVE DUE TO MARKED DIFFERENCES IN THE POSITION
AN EAST-WEST BOUNDARY THAT WILL RESIDE ACROSS EITHER NORTHERN MO
OR FURTHER NORTH INTO IOWA. THE ECMWF HAS BEEN THE MOST INSISTENT
WITH THE MORE SRN POSITION AND THUS MUCH WETTER...WHILE THE
REMAINDER OF THE GUIDANCE SUITE KEEPS THE BOUNDARY ALONG OR NORTH
OF THE IOWA/MISSOURI BORDER WITH LESSER PRECIPITATION CHANCES. ON
MONDAY MORNING I THINK THAT ANY LINGERING THREAT OF SHOWERS AND
THUNDERSTORMS WILL BE ALIGNED WITH THE SWLY LLJ AXIS AND BY
AFTERNOON THE EML BUILDS IN STRONGLY AND RESULTS IN SUBSTANTIAL
CAPPING OF THE WARM SECTOR. THE WARM SECTOR WILL CONTINUE TO
MOISTEN AND DESTABILIZE INTO TUESDAY AND SHOULD REMAIN CAPPED TO
SURFACE BASED STORMS SOUTH OF THE FRONT. AT THIS TIME I HAVE KEPT
MY HIGHEST POPS IN THE MONDAY-TUESDAY TIME FRAME ACROSS NRN MO
INTO WEST CENTRAL ILLINOIS WHERE THE FRONT MAY EXIST...WITH POPS
TAPPERED SOUTHWARD. DEPENDING ON WHERE THE FRONT EVENTUALLY
RESIDES I COULD BE UNDERDONE OR OVERDONE WITH THE PRECIPITATION
THREAT. THE MAIN SHOW WITH THE DEEP PROGRESSIVE LONGWAVE TROF AND
ASSOCIATED SURFACE FRONT ALSO REMAINS PROBLEMATIC WITH TIMING
DIFFERENCES IN THE EASTWARD PROGRESSION AMONGST THE SLOWEST
ECMWF...AND FASTER GFS...GEFS AND CANADIAN. ONE PLAUSIBLE SCENARIO
IS THAT THE PLAINS SEVERE WEATHER EVENT ON TUESDAY WILL GROW
UPSCALE INTO A LINE/QLCS AND SHIFT EASTWARD INTO THE AREA
OVERNIGHT TUESDAY INTO WEDNESDAY MORNING. ANOTHER IS THAT THIS
LINE MAY REACH INTO WESTERN MO IN A WEAKENING STATE LATE TUESDAY
NIGHT AND THE MAIN EVENT MAYBE WED AFTERNOON AND EVENING IN THE
CWA PER THE ECMWF. THUS SOMEWHERE IN THE LATE TUESDAY NIGHT-
WEDNESDAY NIGHT TIME FRAME WE ARE LIKELY TO SEE SIGNIFICANT
CONVECTION...SOME OF WHICH COULD BE SEVERE.
A COOL DOWN IS FORECAST IN THE WAKE OF THE FRONT THURSDAY INTO
FRIDAY WITH BROAD CYCLONIC FLOW ALOFT.
GLASS
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 626 PM CDT SAT APR 6 2013
COLD FRONT HAS MOVED INTO NORTHWESTERN MO EARLY THIS EVENING AND
SHOULD PROGRESS THROUGH THE FORECAST AREA BEFORE STALLING OUT
ALONG THE I-70 CORRIDOR AFTER 08Z. FOR NOW WILL SEE GUSTY SOUTH
WINDS DIMINISH BY 01Z. AS FOR CLOUDS...JUST MID AND HIGH CLOUDS
EXPECTED THROUGH THE FORECAST PERIOD. ONCE FRONTAL BOUNDARY STALLS
OUT...WINDS TO BECOME LIGHT AND VARIABLE AT TAF SITES WITH SOME
PATCHY FOG POSSIBLE AT KCOU...KSUS AND KCPS BETWEEN 09Z AND 12Z.
THEN FRONTAL BOUNDARY TO BEGIN TO SLIDE BACK TO THE NORTH...SO
WINDS TO PICKUP FROM THE SOUTHEAST TO SOUTH ALONG I-70 CORRIDOR BY
16Z AND AROUND 21Z SUNDAY AT KUIN.
SPECIFICS FOR KSTL...COLD FRONT HAS MOVED INTO NORTHWESTERN MO
EARLY THIS EVENING AND SHOULD PROGRESS THROUGH THE FORECAST AREA
BEFORE STALLING OUT ALONG THE I-70 CORRIDOR AFTER 08Z. FOR NOW
WILL SEE GUSTY SOUTH WINDS DIMINISH BY 01Z. AS FOR CLOUDS...JUST
MID AND HIGH CLOUDS EXPECTED THROUGH THE FORECAST PERIOD. ONCE
FRONTAL BOUNDARY STALLS OUT...WINDS TO BECOME LIGHT AND VARIABLE
AT KSTL BY 08Z SUNDAY. THEN FRONTAL BOUNDARY TO BEGIN TO SLIDE BACK
TO THE NORTH...SO WINDS TO PICKUP FROM THE SOUTH BY 16Z SUNDAY.
BEST CHANCE FOR RAIN THROUGH THE FORECAST PERIOD WILL BE AFTER 00Z
MONDAY...FOR NOW TIMING HARD TO PIN DOWN...SO JUST ADDED PROB30
GROUP BETWEEN 02Z AND 06Z MONDAY.
BYRD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1230 PM CDT FRI APR 5 2013
.UPDATE...
ISSUED AT 1116 AM CDT FRI APR 5 2013
AREAS OF CLOUD COVER HAVE THUS FAR LIMITED THE RISE IN
TEMPERATURES THIS MORNING. WENT AHEAD AND UPDATED THE FORECAST
TO LOWER MAX T/S A COUPLE DEGREES ACROSS THE BOARD. OTHERWISE NO
CHANGES TO OUR CURRENT RED FLAG WARNING...EVEN WITH THE SLIGHTLY
COOLER TEMPERATURES...STILL LOOKING AT WIDESPREAD SUB 20 PERCENT
RH ACROSS FIRE ZONES 204 AND 210...WITH LOCALIZED AREAS OF 15
PERCENT. CRITICAL WIND SPEEDS ARE NOT THERE YET...BUT STILL
ANTICIPATING GUSTS AOA 25 MPH DURING PEAK HEATING.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 356 AM CDT FRI APR 5 2013
A MODIFIED ARCTIC FRONT IS LINED UP FROM ROUGHLY KFNB TO KLBF TO
E-KIEN. THE FRONT WILL LIFT NORTH TODAY AS LOW
PRESSURE...CURRENTLY ACROSS NERN WY...MOVES EAST THROUGH SRN SD.
THE TEMPERATURE FCST USES 50 PERCENT OF THE RAP13 AND A BLEND OF
OTHER MODELS. THE RAP IS VERY WARM BUT GIVEN THE CLOUDS MOVING
IN...IT IS PROBABLY TOO WARM.
THE NAM RADAR AND THUNDERSTORM PRODUCTS SUGGEST ISOLATED HIGH
BASED SHRA AND TSTM THIS AFTN AND THIS EVENING. LITTLE OR NO
RAINFALL IS EXPECTED. AS THE SFC LOW TRACKS THROUGH SD TODAY AND
INTO SRN MN TONIGHT...A PACIFIC COLD FRONT WILL DROP THROUGH THE
FCST AREA. THIS WILL KEEP LOWS ON THE WARM SIDE WITH LOWS MAINLY
IN THE 40S.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 356 AM CDT FRI APR 5 2013
SATURDAY WILL STILL BE ANOTHER MILD DAY AS MOSTLY SUNNY SKIES
BEHIND THE PACIFIC COLD FRONT PREVAIL. HIGHS SHOULD PUSH IN THE
60S WHICH IS DOWN ABOUT 10 TO 15 DEGREES FROM FRIDAY...BUT STILL
ABOVE NORMAL. SATURDAY NIGHT A TROUGH DEVELOPS ALONG THE FRONT
RANGE AND WILL BRING A SLIGHT CHANCE FOR SHOWERS TO THE EASTERN
PANHANDLE. MOISTURE IS LIMITED AND WILL HAVE TO OVERCOME A DRY
LOWER LAYER THUS EXPECT AMOUNTS LIGHT.
SUNDAY WILL SEE THE NEXT WAVE PUSH ONTO THE HIGH PLAINS. MOISTURE
IS LIMITED WITH PRECIP WATER ONLY AROUND 75 PERCENT OF
NORMAL...FOR APRIL. INSTABILITY INCREASES DURING THE AFTERNOON
WITH HEATING...AND SHOULD BE ENOUGH TO SET OFF SOME THUNDERSTORMS.
CAPE VALUES ONLY A FEW HUNDRED J/KG...HOWEVER GREATER VALUES NOT TO
FAR TO THE SOUTH IN KS.
NEXT WEEK WILL SEE A MAJOR LOW DIG TOWARDS THE 4 CORNERS THEN
EJECT ONTO THE PLAINS BY MID WEEK. THE MODELS CONTINUE TO
STRUGGLE ON TIMING AND STRENGTH OF THE SYSTEM...WHICH LEADS TO A
LOWER THAN AVERAGE CONFIDENCE IN FORECAST.
THE GFS CONTINUES TO BE A FASTER SOLUTION...WHILE THE ECMWF BRINGS
UP THE REAR. INITIALLY THINK AS THE LOW PUSHES TOWARDS THE
ROCKIES...SOME MOISTURE WILL ADVECT NORTH. WE MAY GET DRY SLOTTED
SUNDAY NIGHT INTO MONDAY...AHEAD OF THE LOW. HOWEVER PRECIP WATER
INCREASES TO AROUND AN INCH...WHICH IS CLOSER TO 2 SD...LATE
MONDAY. NEG LI/S SHOULD LEAD TO SOME SHOWERS AND THUNDER ACROSS
MOST OF THE AREA.
THEN AS THE UPPER LOW EJECTS ONTO THE PLAINS...WILL SEE SOME COLD
AIR DEVELOP ON THE BACK SIDE. THIS WILL ALSO WORK IN TANDEM WITH
COOL TEMPS AT NIGHT. WILL NEED TO MENTION SOME SN IN THE NW AND A
MIX TO THE SOUTH AND EAST. LATEST MEX GUIDANCE FOR TUES AND WED
HOLD DAYTIME HIGHS IN THE NW IN THE 30S. WHICH IS POSSIBLE AS THE
CLOUDS WILL LIMIT DIURNAL SWING. ANOTHER CONCERN IS THE TIGHT
PRESSURE GRADIENT...WHICH WILL CREATE SOME WINDY CONDITIONS. THE
SYSTEM IS VERY SLOW TO PUSH ACROSS THE PLAINS...WITH IMPACT
THROUGH AT LEAST EARLY WEDNESDAY.
FOR THE LATER PART OF THE WEEK A SECONDARY UPPER LEVEL DISTURBANCE
ROTATES DOWN ACROSS THE WESTERN PLAINS. ALTHOUGH MODELS HAVE HIGH
PRESSURE AT THE SURFACE...THE UPPER LEVEL WAVE SHOULD HAVE ENOUGH
MOISTURE TO STILL PRODUCE CLOUDS AND SOME LIGHT RAIN OR SNOW.
LONG WAY TROUGH FINALLY SHOULD BE EAST BY THURSDAY OR
FRIDAY...WITH A RIDGE TO THE WEST. THIS WILL RESULT IN NW FLOW AND
A TRAIN OF UPPER LEVEL SHORT WAVES. WILL LIKELY NEED TO MENTION AT
LEAST SOME LIGHT PRECIP TOWARDS THE END OF THE WEEK...HOWEVER
TIMING ISSUES ARE COMMON THIS FAR OUT AND WILL NOT BLANKET POPS.
WILL MONITOR AND ADD WHEN CONFIDENCE IS HIGHER ON LOCATION AND
TIMING.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1230 PM CDT FRI APR 5 2013
VFR EXPECTED FOR ALL TERMINALS TODAY AND TONIGHT. STILL SEE AN
OPPORTUNITY FOR A STRAY TSTM OR TWO THIS AFTERNOON/EVENING ACROSS
NORTHERN NEBRASKA...BUT OVERALL COVERAGE WILL BE ISOLATED AT BEST.
DUE TO THE DRY LOWER LEVELS OF THE ATMOSPHERE...ERRATIC GUSTY WIND
WOULD ACCOMPANY ANY STORM THAT WERE TO DEVELOP. OTHERWISE A STRONG
PACIFIC COLD FRONT WILL CROSS THE REGION THIS EVENING/OVERNIGHT...A
WIND SHIFT WILL ACCOMPANY THE PASSAGE WITH SFC WINDS VEERING FROM
SOUTHERLY TO NORTHWESTERLY...AND STAYING GUSTY THROUGH MUCH OF THE
FORECAST PERIOD. MODEL GUIDANCE INDICATES THE FRONT THROUGH KVTN
AND KLBF FROM THE 04-06Z TIME FRAME.
&&
.FIRE WEATHER...
ISSUED AT 356 AM CDT FRI APR 5 2013
A WEAKNESS IN THE WIND FIELDS IS SHOWING UP ACROSS SWRN NEB.
THUS...RELATIVE HUMIDITY WILL BE VERY LOW IN THAT AREA BUT WINDS
MAY NOT BE STRONG ENOUGH FOR CRITICAL FIRE DANGER. STRONGER WEST
WINDS SHOW UP ACROSS THE ERN NEB PANHANDLE. THESE WEST WINDS WILL
SWEEP EAST THIS AFTN TO NEAR KVTN AND KTIF. SOUTH WINDS CONTINUE
EAST OF HIGHWAY 83. PRESUMABLY...THIS WILL DRAW MORE MOIST AIR
NORTH FROM KS AND OKLAHOMA.
THE RAP MODEL IS VERY DRY AND SUGGESTS CRITICAL FIRE CONDITIONS
COULD SPREAD THROUGHOUT WESTERN AND NORTH CENTRAL NEB THIS
AFTERNOON. THIS IS AN OCCASIONAL BIAS THAT SHOWS IN THE MODEL BUT
IT SENSES THE DRYNESS OF THE ARCTIC AIR AND INCORPORATES IT INTO
THE AFTN WEATHER. THE MODEL COULD BE CORRECT TO A DEGREE. THE
BEST FORECAST IS A BLEND OF THE RAP WHICH IS VERY DRY AND THE
OTHER MODELS WHICH TEND TO BE TOO MOIST.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 8 PM CDT /7 PM MDT/ THIS EVENING FOR
NEZ204-210.
&&
$$
UPDATE...JACOBS
SHORT TERM...CDC
LONG TERM...MASEK
AVIATION...JACOBS
FIRE WEATHER...CDC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1116 AM CDT FRI APR 5 2013
.UPDATE...
ISSUED AT 1116 AM CDT FRI APR 5 2013
AREAS OF CLOUD COVER HAVE THUS FAR LIMITED THE RISE IN
TEMPERATURES THIS MORNING. WENT AHEAD AND UPDATED THE FORECAST
TO LOWER MAX T/S A COUPLE DEGREES ACROSS THE BOARD. OTHERWISE NO
CHANGES TO OUR CURRENT RED FLAG WARNING...EVEN WITH THE SLIGHTLY
COOLER TEMPERATURES...STILL LOOKING AT WIDESPREAD SUB 20 PERCENT
RH ACROSS FIRE ZONES 204 AND 210...WITH LOCALIZED AREAS OF 15
PERCENT. CRITICAL WIND SPEEDS ARE NOT THERE YET...BUT STILL
ANTICIPATING GUSTS AOA 25 MPH DURING PEAK HEATING.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 356 AM CDT FRI APR 5 2013
A MODIFIED ARCTIC FRONT IS LINED UP FROM ROUGHLY KFNB TO KLBF TO
E-KIEN. THE FRONT WILL LIFT NORTH TODAY AS LOW
PRESSURE...CURRENTLY ACROSS NERN WY...MOVES EAST THROUGH SRN SD.
THE TEMPERATURE FCST USES 50 PERCENT OF THE RAP13 AND A BLEND OF
OTHER MODELS. THE RAP IS VERY WARM BUT GIVEN THE CLOUDS MOVING
IN...IT IS PROBABLY TOO WARM.
THE NAM RADAR AND THUNDERSTORM PRODUCTS SUGGEST ISOLATED HIGH
BASED SHRA AND TSTM THIS AFTN AND THIS EVENING. LITTLE OR NO
RAINFALL IS EXPECTED. AS THE SFC LOW TRACKS THROUGH SD TODAY AND
INTO SRN MN TONIGHT...A PACIFIC COLD FRONT WILL DROP THROUGH THE
FCST AREA. THIS WILL KEEP LOWS ON THE WARM SIDE WITH LOWS MAINLY
IN THE 40S.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 356 AM CDT FRI APR 5 2013
SATURDAY WILL STILL BE ANOTHER MILD DAY AS MOSTLY SUNNY SKIES
BEHIND THE PACIFIC COLD FRONT PREVAIL. HIGHS SHOULD PUSH IN THE
60S WHICH IS DOWN ABOUT 10 TO 15 DEGREES FROM FRIDAY...BUT STILL
ABOVE NORMAL. SATURDAY NIGHT A TROUGH DEVELOPS ALONG THE FRONT
RANGE AND WILL BRING A SLIGHT CHANCE FOR SHOWERS TO THE EASTERN
PANHANDLE. MOISTURE IS LIMITED AND WILL HAVE TO OVERCOME A DRY
LOWER LAYER THUS EXPECT AMOUNTS LIGHT.
SUNDAY WILL SEE THE NEXT WAVE PUSH ONTO THE HIGH PLAINS. MOISTURE
IS LIMITED WITH PRECIP WATER ONLY AROUND 75 PERCENT OF
NORMAL...FOR APRIL. INSTABILITY INCREASES DURING THE AFTERNOON
WITH HEATING...AND SHOULD BE ENOUGH TO SET OFF SOME THUNDERSTORMS.
CAPE VALUES ONLY A FEW HUNDRED J/KG...HOWEVER GREATER VALUES NOT TO
FAR TO THE SOUTH IN KS.
NEXT WEEK WILL SEE A MAJOR LOW DIG TOWARDS THE 4 CORNERS THEN
EJECT ONTO THE PLAINS BY MID WEEK. THE MODELS CONTINUE TO
STRUGGLE ON TIMING AND STRENGTH OF THE SYSTEM...WHICH LEADS TO A
LOWER THAN AVERAGE CONFIDENCE IN FORECAST.
THE GFS CONTINUES TO BE A FASTER SOLUTION...WHILE THE ECMWF BRINGS
UP THE REAR. INITIALLY THINK AS THE LOW PUSHES TOWARDS THE
ROCKIES...SOME MOISTURE WILL ADVECT NORTH. WE MAY GET DRY SLOTTED
SUNDAY NIGHT INTO MONDAY...AHEAD OF THE LOW. HOWEVER PRECIP WATER
INCREASES TO AROUND AN INCH...WHICH IS CLOSER TO 2 SD...LATE
MONDAY. NEG LI/S SHOULD LEAD TO SOME SHOWERS AND THUNDER ACROSS
MOST OF THE AREA.
THEN AS THE UPPER LOW EJECTS ONTO THE PLAINS...WILL SEE SOME COLD
AIR DEVELOP ON THE BACK SIDE. THIS WILL ALSO WORK IN TANDEM WITH
COOL TEMPS AT NIGHT. WILL NEED TO MENTION SOME SN IN THE NW AND A
MIX TO THE SOUTH AND EAST. LATEST MEX GUIDANCE FOR TUES AND WED
HOLD DAYTIME HIGHS IN THE NW IN THE 30S. WHICH IS POSSIBLE AS THE
CLOUDS WILL LIMIT DIURNAL SWING. ANOTHER CONCERN IS THE TIGHT
PRESSURE GRADIENT...WHICH WILL CREATE SOME WINDY CONDITIONS. THE
SYSTEM IS VERY SLOW TO PUSH ACROSS THE PLAINS...WITH IMPACT
THROUGH AT LEAST EARLY WEDNESDAY.
FOR THE LATER PART OF THE WEEK A SECONDARY UPPER LEVEL DISTURBANCE
ROTATES DOWN ACROSS THE WESTERN PLAINS. ALTHOUGH MODELS HAVE HIGH
PRESSURE AT THE SURFACE...THE UPPER LEVEL WAVE SHOULD HAVE ENOUGH
MOISTURE TO STILL PRODUCE CLOUDS AND SOME LIGHT RAIN OR SNOW.
LONG WAY TROUGH FINALLY SHOULD BE EAST BY THURSDAY OR
FRIDAY...WITH A RIDGE TO THE WEST. THIS WILL RESULT IN NW FLOW AND
A TRAIN OF UPPER LEVEL SHORT WAVES. WILL LIKELY NEED TO MENTION AT
LEAST SOME LIGHT PRECIP TOWARDS THE END OF THE WEEK...HOWEVER
TIMING ISSUES ARE COMMON THIS FAR OUT AND WILL NOT BLANKET POPS.
WILL MONITOR AND ADD WHEN CONFIDENCE IS HIGHER ON LOCATION AND
TIMING.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 619 AM CDT FRI APR 5 2013
VFR IS EXPECTED ALL AREAS TODAY AND TONIGHT. ISOLATED AFTERNOON
AND EVENING THUNDERSTORMS ARE POSSIBLE WITH THE APPROACH OF A
STRONG PACIFIC COLD FRONT. THE FRONT IS EXPECTED TO PRODUCE A
PERIOD OF GUSTY WINDS ACROSS NRN NEB TONIGHT. OTHERWISE SCT-BKN120-200
CIGS WILL CONTINUE THROUGH 06Z TONIGHT.
&&
.FIRE WEATHER...
ISSUED AT 356 AM CDT FRI APR 5 2013
A WEAKNESS IN THE WIND FIELDS IS SHOWING UP ACROSS SWRN NEB.
THUS...RELATIVE HUMIDITY WILL BE VERY LOW IN THAT AREA BUT WINDS
MAY NOT BE STRONG ENOUGH FOR CRITICAL FIRE DANGER. STRONGER WEST
WINDS SHOW UP ACROSS THE ERN NEB PANHANDLE. THESE WEST WINDS WILL
SWEEP EAST THIS AFTN TO NEAR KVTN AND KTIF. SOUTH WINDS CONTINUE
EAST OF HIGHWAY 83. PRESUMABLY...THIS WILL DRAW MORE MOIST AIR
NORTH FROM KS AND OKLAHOMA.
THE RAP MODEL IS VERY DRY AND SUGGESTS CRITICAL FIRE CONDITIONS
COULD SPREAD THROUGHOUT WESTERN AND NORTH CENTRAL NEB THIS
AFTERNOON. THIS IS AN OCCASIONAL BIAS THAT SHOWS IN THE MODEL BUT
IT SENSES THE DRYNESS OF THE ARCTIC AIR AND INCORPORATES IT INTO
THE AFTN WEATHER. THE MODEL COULD BE CORRECT TO A DEGREE. THE
BEST FORECAST IS A BLEND OF THE RAP WHICH IS VERY DRY AND THE
OTHER MODELS WHICH TEND TO BE TOO MOIST.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 8 PM CDT /7 PM MDT/ THIS EVENING FOR
NEZ204-210.
&&
$$
UPDATE...JACOBS
SHORT TERM...CDC
LONG TERM...MASEK
AVIATION...CDC
FIRE WEATHER...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
623 AM CDT FRI APR 5 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 356 AM CDT FRI APR 5 2013
A MODIFIED ARCTIC FRONT IS LINED UP FROM ROUGHLY KFNB TO KLBF TO
E-KIEN. THE FRONT WILL LIFT NORTH TODAY AS LOW
PRESSURE...CURRENTLY ACROSS NERN WY...MOVES EAST THROUGH SRN SD.
THE TEMPERATURE FCST USES 50 PERCENT OF THE RAP13 AND A BLEND OF
OTHER MODELS. THE RAP IS VERY WARM BUT GIVEN THE CLOUDS MOVING
IN...IT IS PROBABLY TOO WARM.
THE NAM RADAR AND THUNDERSTORM PRODUCTS SUGGEST ISOLATED HIGH
BASED SHRA AND TSTM THIS AFTN AND THIS EVENING. LITTLE OR NO
RAINFALL IS EXPECTED. AS THE SFC LOW TRACKS THROUGH SD TODAY AND
INTO SRN MN TONIGHT...A PACIFIC COLD FRONT WILL DROP THROUGH THE
FCST AREA. THIS WILL KEEP LOWS ON THE WARM SIDE WITH LOWS MAINLY
IN THE 40S.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 356 AM CDT FRI APR 5 2013
SATURDAY WILL STILL BE ANOTHER MILD DAY AS MOSTLY SUNNY SKIES
BEHIND THE PACIFIC COLD FRONT PREVAIL. HIGHS SHOULD PUSH IN THE
60S WHICH IS DOWN ABOUT 10 TO 15 DEGREES FROM FRIDAY...BUT STILL
ABOVE NORMAL. SATURDAY NIGHT A TROUGH DEVELOPS ALONG THE FRONT
RANGE AND WILL BRING A SLIGHT CHANCE FOR SHOWERS TO THE EASTERN
PANHANDLE. MOISTURE IS LIMITED AND WILL HAVE TO OVERCOME A DRY
LOWER LAYER THUS EXPECT AMOUNTS LIGHT.
SUNDAY WILL SEE THE NEXT WAVE PUSH ONTO THE HIGH PLAINS. MOISTURE
IS LIMITED WITH PRECIP WATER ONLY AROUND 75 PERCENT OF
NORMAL...FOR APRIL. INSTABILITY INCREASES DURING THE AFTERNOON
WITH HEATING...AND SHOULD BE ENOUGH TO SET OFF SOME THUNDERSTORMS.
CAPE VALUES ONLY A FEW HUNDRED J/KG...HOWEVER GREATER VALUES NOT TO
FAR TO THE SOUTH IN KS.
NEXT WEEK WILL SEE A MAJOR LOW DIG TOWARDS THE 4 CORNERS THEN
EJECT ONTO THE PLAINS BY MID WEEK. THE MODELS CONTINUE TO
STRUGGLE ON TIMING AND STRENGTH OF THE SYSTEM...WHICH LEADS TO A
LOWER THAN AVERAGE CONFIDENCE IN FORECAST.
THE GFS CONTINUES TO BE A FASTER SOLUTION...WHILE THE ECMWF BRINGS
UP THE REAR. INITIALLY THINK AS THE LOW PUSHES TOWARDS THE
ROCKIES...SOME MOISTURE WILL ADVECT NORTH. WE MAY GET DRY SLOTTED
SUNDAY NIGHT INTO MONDAY...AHEAD OF THE LOW. HOWEVER PRECIP WATER
INCREASES TO AROUND AN INCH...WHICH IS CLOSER TO 2 SD...LATE
MONDAY. NEG LI/S SHOULD LEAD TO SOME SHOWERS AND THUNDER ACROSS
MOST OF THE AREA.
THEN AS THE UPPER LOW EJECTS ONTO THE PLAINS...WILL SEE SOME COLD
AIR DEVELOP ON THE BACK SIDE. THIS WILL ALSO WORK IN TANDEM WITH
COOL TEMPS AT NIGHT. WILL NEED TO MENTION SOME SN IN THE NW AND A
MIX TO THE SOUTH AND EAST. LATEST MEX GUIDANCE FOR TUES AND WED
HOLD DAYTIME HIGHS IN THE NW IN THE 30S. WHICH IS POSSIBLE AS THE
CLOUDS WILL LIMIT DIURNAL SWING. ANOTHER CONCERN IS THE TIGHT
PRESSURE GRADIENT...WHICH WILL CREATE SOME WINDY CONDITIONS. THE
SYSTEM IS VERY SLOW TO PUSH ACROSS THE PLAINS...WITH IMPACT
THROUGH AT LEAST EARLY WEDNESDAY.
FOR THE LATER PART OF THE WEEK A SECONDARY UPPER LEVEL DISTURBANCE
ROTATES DOWN ACROSS THE WESTERN PLAINS. ALTHOUGH MODELS HAVE HIGH
PRESSURE AT THE SURFACE...THE UPPER LEVEL WAVE SHOULD HAVE ENOUGH
MOISTURE TO STILL PRODUCE CLOUDS AND SOME LIGHT RAIN OR SNOW.
LONG WAY TROUGH FINALLY SHOULD BE EAST BY THURSDAY OR
FRIDAY...WITH A RIDGE TO THE WEST. THIS WILL RESULT IN NW FLOW AND
A TRAIN OF UPPER LEVEL SHORT WAVES. WILL LIKELY NEED TO MENTION AT
LEAST SOME LIGHT PRECIP TOWARDS THE END OF THE WEEK...HOWEVER
TIMING ISSUES ARE COMMON THIS FAR OUT AND WILL NOT BLANKET POPS.
WILL MONITOR AND ADD WHEN CONFIDENCE IS HIGHER ON LOCATION AND
TIMING.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 619 AM CDT FRI APR 5 2013
VFR IS EXPECTED ALL AREAS TODAY AND TONIGHT. ISOLATED AFTERNOON
AND EVENING THUNDERSTORMS ARE POSSIBLE WITH THE APPROACH OF A
STRONG PACIFIC COLD FRONT. THE FRONT IS EXPECTED TO PRODUCE A
PERIOD OF GUSTY WINDS ACROSS NRN NEB TONIGHT. OTHERWISE SCT-BKN120-200
CIGS WILL CONTINUE THROUGH 06Z TONIGHT.
&&
.FIRE WEATHER...
ISSUED AT 356 AM CDT FRI APR 5 2013
A WEAKNESS IN THE WIND FIELDS IS SHOWING UP ACROSS SWRN NEB.
THUS...RELATIVE HUMIDITY WILL BE VERY LOW IN THAT AREA BUT WINDS
MAY NOT BE STRONG ENOUGH FOR CRITICAL FIRE DANGER. STRONGER WEST
WINDS SHOW UP ACROSS THE ERN NEB PANHANDLE. THESE WEST WINDS WILL
SWEEP EAST THIS AFTN TO NEAR KVTN AND KTIF. SOUTH WINDS CONTINUE
EAST OF HIGHWAY 83. PRESUMABLY...THIS WILL DRAW MORE MOIST AIR
NORTH FROM KS AND OKLAHOMA.
THE RAP MODEL IS VERY DRY AND SUGGESTS CRITICAL FIRE CONDITIONS
COULD SPREAD THROUGHOUT WESTERN AND NORTH CENTRAL NEB THIS
AFTERNOON. THIS IS AN OCCASIONAL BIAS THAT SHOWS IN THE MODEL BUT
IT SENSES THE DRYNESS OF THE ARCTIC AIR AND INCORPORATES IT INTO
THE AFTN WEATHER. THE MODEL COULD BE CORRECT TO A DEGREE. THE
BEST FORECAST IS A BLEND OF THE RAP WHICH IS VERY DRY AND THE
OTHER MODELS WHICH TEND TO BE TOO MOIST.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM 1 PM CDT /NOON MDT/ THIS AFTERNOON TO 8 PM
CDT /7 PM MDT/ THIS EVENING FOR NEZ204-210.
&&
$$
SHORT TERM...CDC
LONG TERM...MASEK
AVIATION...CDC
FIRE WEATHER...CDC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
357 AM CDT FRI APR 5 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 356 AM CDT FRI APR 5 2013
A MODIFIED ARCTIC FRONT IS LINED UP FROM ROUGHLY KFNB TO KLBF TO
E-KIEN. THE FRONT WILL LIFT NORTH TODAY AS LOW
PRESSURE...CURRENTLY ACROSS NERN WY...MOVES EAST THROUGH SRN SD.
THE TEMPERATURE FCST USES 50 PERCENT OF THE RAP13 AND A BLEND OF
OTHER MODELS. THE RAP IS VERY WARM BUT GIVEN THE CLOUDS MOVING
IN...IT IS PROBABLY TOO WARM.
THE NAM RADAR AND THUNDERSTORM PRODUCTS SUGGEST ISOLATED HIGH
BASED SHRA AND TSTM THIS AFTN AND THIS EVENING. LITTLE OR NO
RAINFALL IS EXPECTED. AS THE SFC LOW TRACKS THROUGH SD TODAY AND
INTO SRN MN TONIGHT...A PACIFIC COLD FRONT WILL DROP THROUGH THE
FCST AREA. THIS WILL KEEP LOWS ON THE WARM SIDE WITH LOWS MAINLY
IN THE 40S.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 356 AM CDT FRI APR 5 2013
SATURDAY WILL STILL BE ANOTHER MILD DAY AS MOSTLY SUNNY SKIES
BEHIND THE PACIFIC COLD FRONT PREVAIL. HIGHS SHOULD PUSH IN THE
60S WHICH IS DOWN ABOUT 10 TO 15 DEGREES FROM FRIDAY...BUT STILL
ABOVE NORMAL. SATURDAY NIGHT A TROUGH DEVELOPS ALONG THE FRONT
RANGE AND WILL BRING A SLIGHT CHANCE FOR SHOWERS TO THE EASTERN
PANHANDLE. MOISTURE IS LIMITED AND WILL HAVE TO OVERCOME A DRY
LOWER LAYER THUS EXPECT AMOUNTS LIGHT.
SUNDAY WILL SEE THE NEXT WAVE PUSH ONTO THE HIGH PLAINS. MOISTURE
IS LIMITED WITH PRECIP WATER ONLY AROUND 75 PERCENT OF
NORMAL...FOR APRIL. INSTABILITY INCREASES DURING THE AFTERNOON
WITH HEATING...AND SHOULD BE ENOUGH TO SET OFF SOME THUNDERSTORMS.
CAPE VALUES ONLY A FEW HUNDRED J/KG...HOWEVER GREATER VALUES NOT TO
FAR TO THE SOUTH IN KS.
NEXT WEEK WILL SEE A MAJOR LOW DIG TOWARDS THE 4 CORNERS THEN
EJECT ONTO THE PLAINS BY MID WEEK. THE MODELS CONTINUE TO
STRUGGLE ON TIMING AND STRENGTH OF THE SYSTEM...WHICH LEADS TO A
LOWER THAN AVERAGE CONFIDENCE IN FORECAST.
THE GFS CONTINUES TO BE A FASTER SOLUTION...WHILE THE ECMWF BRINGS
UP THE REAR. INITIALLY THINK AS THE LOW PUSHES TOWARDS THE
ROCKIES...SOME MOISTURE WILL ADVECT NORTH. WE MAY GET DRY SLOTTED
SUNDAY NIGHT INTO MONDAY...AHEAD OF THE LOW. HOWEVER PRECIP WATER
INCREASES TO AROUND AN INCH...WHICH IS CLOSER TO 2 SD...LATE
MONDAY. NEG LI/S SHOULD LEAD TO SOME SHOWERS AND THUNDER ACROSS
MOST OF THE AREA.
THEN AS THE UPPER LOW EJECTS ONTO THE PLAINS...WILL SEE SOME COLD
AIR DEVELOP ON THE BACK SIDE. THIS WILL ALSO WORK IN TANDEM WITH
COOL TEMPS AT NIGHT. WILL NEED TO MENTION SOME SN IN THE NW AND A
MIX TO THE SOUTH AND EAST. LATEST MEX GUIDANCE FOR TUES AND WED
HOLD DAYTIME HIGHS IN THE NW IN THE 30S. WHICH IS POSSIBLE AS THE
CLOUDS WILL LIMIT DIURNAL SWING. ANOTHER CONCERN IS THE TIGHT
PRESSURE GRADIENT...WHICH WILL CREATE SOME WINDY CONDITIONS. THE
SYSTEM IS VERY SLOW TO PUSH ACROSS THE PLAINS...WITH IMPACT
THROUGH AT LEAST EARLY WEDNESDAY.
FOR THE LATER PART OF THE WEEK A SECONDARY UPPER LEVEL DISTURBANCE
ROTATES DOWN ACROSS THE WESTERN PLAINS. ALTHOUGH MODELS HAVE HIGH
PRESSURE AT THE SURFACE...THE UPPER LEVEL WAVE SHOULD HAVE ENOUGH
MOISTURE TO STILL PRODUCE CLOUDS AND SOME LIGHT RAIN OR SNOW.
LONG WAY TROUGH FINALLY SHOULD BE EAST BY THURSDAY OR
FRIDAY...WITH A RIDGE TO THE WEST. THIS WILL RESULT IN NW FLOW AND
A TRAIN OF UPPER LEVEL SHORT WAVES. WILL LIKELY NEED TO MENTION AT
LEAST SOME LIGHT PRECIP TOWARDS THE END OF THE WEEK...HOWEVER
TIMING ISSUES ARE COMMON THIS FAR OUT AND WILL NOT BLANKET POPS.
WILL MONITOR AND ADD WHEN CONFIDENCE IS HIGHER ON LOCATION AND
TIMING.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1234 AM CDT FRI APR 5 2013
HIGH LEVEL CLOUDINESS AON 20000 FT AGL WILL BEGIN TO MOVE INTO
WESTERN AND NORTH CENTRAL NEBRASKA OVERNIGHT WITH BROKEN CIGS
EXPECTED FRIDAY MORNING. BROKEN CLOUD COVERAGE WILL PERSIST THROUGH
FRIDAY EVENING. CIGS MAY LOWER TO 12000 TO 15000 FT AGL FRIDAY
EVENING AS A FRONTAL BOUNDARY APPROACHES WESTERN AND NORTH CENTRAL
NEBRASKA. SOUTHERLY WINDS FRIDAY WILL BEGIN TO SHIFT TO THE
SOUTHWEST...THEN WEST FRIDAY EVENING. WIND SPEEDS FRIDAY AND FRIDAY
EVENING WILL RANGE FROM 10 TO 20 KTS WITH SOME GUSTS UP TO 25 KTS
POSSIBLE FRIDAY EVENING.
&&
.FIRE WEATHER...
ISSUED AT 356 AM CDT FRI APR 5 2013
A WEAKNESS IN THE WIND FIELDS IS SHOWING UP ACROSS SWRN NEB.
THUS...RELATIVE HUMIDITY WILL BE VERY LOW IN THAT AREA BUT WINDS
MAY NOT BE STRONG ENOUGH FOR CRITICAL FIRE DANGER. STRONGER WEST
WINDS SHOW UP ACROSS THE ERN NEB PANHANDLE. THESE WEST WINDS WILL
SWEEP EAST THIS AFTN TO NEAR KVTN AND KTIF. SOUTH WINDS CONTINUE
EAST OF HIGHWAY 83. PRESUMABLY...THIS WILL DRAW MORE MOIST AIR
NORTH FROM KS AND OKLAHOMA.
THE RAP MODEL IS VERY DRY AND SUGGESTS CRITICAL FIRE CONDITIONS
COULD SPREAD THROUGHOUT WESTERN AND NORTH CENTRAL NEB THIS
AFTERNOON. THIS IS AN OCCASIONAL BIAS THAT SHOWS IN THE MODEL BUT
IT SENSES THE DRYNESS OF THE ARCTIC AIR AND INCORPORATES IT INTO
THE AFTN WEATHER. THE MODEL COULD BE CORRECT TO A DEGREE. THE
BEST FORECAST IS A BLEND OF THE RAP WHICH IS VERY DRY AND THE
OTHER MODELS WHICH TEND TO BE TOO MOIST.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM 1 PM CDT /NOON MDT/ THIS AFTERNOON TO 8 PM
CDT /7 PM MDT/ THIS EVENING FOR NEZ204-210.
&&
$$
SHORT TERM...CDC
LONG TERM...MASEK
AVIATION...CDC
FIRE WEATHER...CDC
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
126 PM EDT FRI APR 5 2013
.SYNOPSIS...
LOW PRESSURE SYSTEM JUST OFF THE NORTH CAROLINA COAST WILL
CONTINUE TO LIFT OFF TO THE NORTHEAST AWAY FROM THE AREA THROUGH
TODAY. HIGH PRESSURE WILL BUILD IN BEHIND THIS STORM SYSTEM...
BRINGING A WARMING TREND AND SPRING-LIKE TEMPERATURES THROUGH NEXT
WEEK. A MORE SUMMER-LIKE PATTERN SETS UP THROUGH MID WEEK AS BERMUDA
HIGH PRESSURE DOMINATES BEFORE A COLD FRONT APPROACHES FROM THE WEST
TOWARD LATE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 12:30 PM FRIDAY...OTHER THAN FOR GEORGETOWN COUNTY THE
LATEST GUIDANCE AND RADAR LOOPS SUGGEST THAT PRECIP HAS ENDED FOR
THE DAY. HAVE ALREADY CUT BACK ON POPS WITH THE LATEST
ISSUANCES...AND WILL LIKELY MAY DROP POPS COMPLETELY WITH THE NEXT
FORECAST PACKAGE. PREVIOUS DISCUSSION FOLLOWS:
AN UPPER LEVEL DISTURBANCE MOVING RAPIDLY NORTH THROUGH GEORGIA
AND NOW SOUTH CAROLINA HAS PRODUCED AN IMPRESSIVE AREA OF SHOWERS
AND THUNDERSTORMS EXTENDING FROM GEORGETOWN SC SOUTH BACK INTO
WAYCROSS AND AMERICUS GA VICINITY. THIS CONVECTION IS ELEVATED
WITH THE LIFTING PARCEL LEVEL PROBABLY IN THE VICINITY OF 10000 FT
AGL OR 700 MB. LATEST RUC ANALYSIS SHOWS LAPSE RATES IN THE
700-500 MB LAYER ARE EXCEEDING 7C/KM...AND FORECAST SOUNDINGS FROM
VIRTUALLY ANY MODEL SHOW STEEP LAPSE RATES CONTINUING FOR AT LEAST
ANOTHER 100 MB HIGHER IN THE ATMOSPHERE.
I HAVE INCREASED POPS MAINLY ALONG THE SC COAST AND OFFSHORE FOR THE
MORNING HOURS TO ACCOUNT FOR THIS ACTIVITY. FORTUNATELY THERE IS NO
SEVERE WEATHER THREAT OWNING TO THE DEEP FRONTAL INVERSION BELOW THE
STORMS AND SMALL CAPE VALUES ALOFT LIMITING POTENTIAL HAIL
PRODUCTION. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
SURFACE LOW PRESSURE MOVED ALMOST DIRECTLY OVER ILM AROUND MIDNIGHT.
NOW THAT THE LOW IS RACING NORTHEAST ACROSS EXTREME EASTERN NC COOL
AIR HAS RUSHED DOWN TO THE CAPE FEAR AND GRAND STRAND BEACHES. LOW
STRATUS CLOUDS WILL BE VERY TOUGH TO ERODE TODAY...AND IN FACT
MODELS SUGGEST A SOLID GRAY OVERCAST WILL PERSIST THROUGH THE
MORNING HOURS...RELUCTANTLY LIFTING INTO A SCT-BKN STRATOCUMULUS
DECK SOMETIME IN THE 11 AM TO 2 PM PERIOD. IT APPEARS THE NAM HAS A
BETTER HANDLE ON THE LATER CLOUD BURNOFF THAN THE GFS...THEREFORE MY
FORECAST HIGHS ARE CLOSE THE NAM AND RANGE FROM THE UPPER 50S NEAR
THE COAST TO AROUND 60 INLAND...10-13 DEGREES BELOW NORMAL.
OF MORE IMMEDIATE CONCERN IS A CLUSTER OF THUNDERSTORMS ACROSS
SOUTHERN GEORGIA ASSOCIATED WITH AN 500 MB VORT MAX ROTATING
NORTHEASTWARD AROUND THE MAIN UPPER LOW STILL BACK ON THE
MISSISSIPPI-ALABAMA BORDER. THIS CONVECTION APPEARS TO BE BASED
AROUND 700 MB AND IS TAKING ADVANTAGE OF STEEPENING LAPSE RATES IN
THE 700-400 MB LAYER AS COLD AIR WITH THE UPPER LOW ADVECTS ACROSS
THE SOUTHEAST. IT IS POSSIBLE THESE SHOWERS AND THUNDERSTORMS WILL
AFFECT COASTAL SOUTH CAROLINA LATER THIS MORNING...WHERE I HAVE A
30-40 PERCENT POP IN THE FORECAST. POPS ELSEWHERE ARE IN THE 10-20
PERCENT RANGE HEDGING FOR ANY EXPANSION IN THIS AREA OF ELEVATED
CONVECTION.
THE AFOREMENTIONED UPPER LOW WILL MOVE EAST ACROSS ALABAMA AND
GEORGIA THIS MORNING...THEN INTO SOUTH CAROLINA BY MID AFTERNOON.
LOW AND MID CLOUDS MAY CONTINUE ALONG THE COAST INTO THE EVENING
HOURS BUT CLEARING SKIES SHOULD DEVELOP FROM WEST TO EAST AS THE
UPPER LOW MOVES ACROSS. A NEW AREA OF SURFACE LOW PRESSURE WILL
DEVELOP WELL OFF THE GA/SC COAST LATE THIS AFTERNOON IN ADVANCE OF
THE UPPER SYSTEM. THIS NEW LOW SHOULD REMAIN TOO FAR AWAY FOR ANY
DIRECT IMPACTS ON OUR AREA...BUT NORTHERLY FLOW BEHIND THIS LOW WILL
HELP MAINLY A CHILLY AIRMASS ACROSS THE CAROLINAS TONIGHT WITH LOWS
FALLING TO 40-45...A FEW DEGREES BELOW NORMAL.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...HIGH PRESSURE WILL BUILD DOWN OVER THE
SOUTHEAST THROUGH THE WEEKEND. A COOLER NORTHERLY FLOW INITIALLY
WILL WEAKEN AND BECOME LIGHT AS IT VEERS AROUND THROUGH SAT NIGHT AS
CENTER OF HIGH SHIFTS CLOSER OVERHEAD AND THEN OFF SHORE BY
MORNING. THE MAX CAA WILL CUT OFF EARLY SATURDAY AS 850 TEMPS DROP
CLOSE TO 3C. EXPECT AFTERNOON HIGHS TO ONCE AGAIN REMAIN BELOW
NORMAL REACHING INTO THE LOW TO MID 60S. CALM WINDS AND CLEAR
SKIES SATURDAY NIGHT WILL PROVIDE MORE IDEAL RADIATIONAL COOLING
CONDITIONS WITH TEMPS DROPPING INTO THE LOWER END OF THE 40S MOST
PLACES...BUT SLIGHTLY WARMER AT THE BEACHES.
BY SUNDAY A RETURN FLOW WILL SET UP WITH LIGHT SOUTHERLY WINDS
BEGINNING A WARMING TREND INTO NEXT WEEK. TEMPS WILL APPROACH
NORMAL VALUES FOR THIS TIME OF YEAR WITH HIGH TEMPS JUST REACHING
INTO THE 70S UNDER PLENTY OF SUNSHINE.
OVERALL A BEAUTIFUL WEEKEND WITH LOTS OF SPRING SUNSHINE BUT
SLIGHTLY COOLER TEMPS.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 3 AM FRIDAY...HEADING INTO A MORE SUMMER LIKE PATTERN FOR
THIS TIME OF YEAR. BERMUDA HIGH PRESSURE WITH A WARMER MOISTER
SOUTHERLY RETURN FLOW THROUGH THE PERIOD. A DEEP RIDGE BUILDS
ALOFT WITH HEIGHT RISES PEAKING MID WEEK UP CLOSE TO 585 DM.
AS THE MID TO UPPER RIDGE BUILDS UP THE EAST COAST A DEEPENING
TROUGH WILL DIG DOWN THROUGH THE MID WEST. ALTHOUGH THE RIDGE
HOLDS ON TIGHT THROUGH MUCH OF THE WORK WEEK...THE TROUGH FINALLY
MOVES EAST TOWARD THE AREA PUSHING A COLD FRONT OUR WAY BY THURS
NIGHT INTO FRIDAY. MODELS HAVE PUSHED THE TIMING BACK A BIT AND
THEREFORE LOOKS LIKE NICE WEATHER WILL HOLD OUT THROUGH THURSDAY.
OVERALL A RAIN FREE WEEK WITH A SHARP WARMING TREND BRINGING TEMPS
TO SEVERAL DEGREES ABOVE NORMAL WITH HIGH TEMPS FLIRTING WITH 80
OR SLIGHTLY ABOVE IN PLACES AND MIN TEMPS CLOSE TO WHAT WE HAVE
BEEN EXPERIENCING FOR HIGH TEMPS LATELY. THE COOLER OCEAN TEMPS
WILL MAXIMIZE THE DIFFERENTIAL HEATING ALLOWING FOR A STRONG SEA
BREEZE TO CARRY FAR INLAND MOST AFTERNOONS. THIS WILL BRING COOLER
AIR INLAND BUT WILL ALSO KEEP THE BEACHES MUCH COOLER.
THE SEA BREEZE WILL ALSO PROVIDE A FOCAL POINT FOR ENOUGH
CONVERGENCE TO PRODUCE CU EACH AFTERNOON AND MAY SEE SOME PASSING
HIGH CLOUDS BUT OTHERWISE SHOULD SEE A GOOD DEAL OF SUNSHINE
THROUGH THE WEEK WITH ANY PCP HOLDING OFF UNTIL LATE THURS INTO
FRIDAY.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 18Z...VISIBLE SATELLITE IMAGERY SHOWS THE LOW CLOUD DECK IS
THINNING NEAR KFLO/KLBT AS THE STRATUS IS BEGINNING TO ERODE. ALONG
THE COAST...LOW MVFR CIGS ARE STILL IN PLACE AND WILL LIKELY PERSIST
FOR THE NEXT COUPLE HOURS. ANY LINGERING MVFR CIGS SHOULD LIFT TO
VFR BY LATE AFTERNOON. NORTH WINDS AOB 10 KTS TODAY WILL DIMINISH TO
AROUND 5 KTS TONIGHT. THE SKIES WILL BEGIN CLEARING AFTER 00Z
SATURDAY AS AN UPPER TROUGH CLEARS THE CAROLINA COAST. SFC HIGH
PRESSURE WILL BUILD IN FROM THE NORTH TOMORROW MORNING...BRINGING
SUNNY SKIES AND NORTHEAST WINDS 8-12 KTS ACROSS OUR CWA.
EXTENDED OUTLOOK...VFR CONDITIONS WILL PREVAIL THROUGH WEDNESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 12:30 PM FRIDAY...LATEST OBS AND GUIDANCE SUGGEST THAT WE
CAN DROP SMALL CRAFT ADVISORIES EARLY FOR ALL THE REMAINING
COASTAL WATERS. IT IS LIKELY WE ARE NOW ONLY SEEING 6 FOOTERS OVER
THE OUTER EDGES OF THE COASTAL WATERS. PREVIOUS DISCUSSION
FOLLOWS:
TWO CHANGES HAVE BEEN MADE TO THE MARINE FORECAST THIS MORNING.
THE FIRST IS TO INCREASE SHOWER AND T-STORM CHANCES THROUGH THE
MORNING HOURS AS THE WILMINGTON AND CHARLESTON RADARS ARE SHOWING
AN IMPRESSIVE AREA OF SHOWERS AND STORMS MOVING RAPIDLY NORTHEAST
ALONG THE COAST. THE SOUTH CAROLINA COASTAL WATERS WILL BE MOST
STRONGLY AFFECTED BY THIS ACTIVITY...WHICH SHOULD TAPER OFF BY
NOON. ALSO...OBSERVED WIND SPEEDS ARE ABOUT 5 KNOTS STRONGER THAN
EXPECTED ACROSS THE WATERS NORTH OF CAPE FEAR...WHERE RECENTLY
GUSTS AT BOTH WRIGHTSVILLE BEACH AND THE FRYING PAN SHOALS BUOY
OFFSHORE HAVE BEEN AROUND 20 KNOTS. NO OTHER SIGNIFICANT CHANGES
HAVE BEEN MADE. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
SURFACE LOW PRESSURE MOVED OVER WILMINGTON AROUND MIDNIGHT AND IS
NOW RACING NORTHEAST ACROSS THE PAMLICO SOUND. NORTHWESTERLY WINDS
BEHIND THIS LOW HAVE PUSHED THE COLD FRONT A CONSIDERABLE DISTANCE
FROM SHORE...AND COOL NORTHWEST TO NORTH WINDS SHOULD CONTINUE
THROUGH THE DAY. STRONG WINDS YESTERDAY STILL HAVE THE SEA STATE
QUITE AGITATED AND IT WILL TAKE MOST OF THE DAY FOR SEAS TO DECAY
BELOW 6 FEET. FOR THIS REASON THE SMALL CRAFT ADVISORY WILL REMAIN
POSTED INTO THE AFTERNOON HOURS FOR THE SC COASTAL WATERS...AND
UNTIL THIS EVENING FOR THE NC WATERS.
AN APPROACHING UPPER LEVEL LOW WILL INDUCE A NEW LOW TO DEVELOP WELL
OFF THE SC COAST LATE THIS AFTERNOON. WHILE THIS NEW LOW WILL HAVE
NO DIRECT IMPACTS LOCALLY...IT WILL HELP TO ENHANCE THE NORTHERLY
WINDS SOMEWHAT WITH WIND SPEEDS PERHAPS ECLIPSING 15 KNOTS
OVERNIGHT...ESPECIALLY AWAY FROM SHORE.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...HIGH PRESSURE WILL BUILD DOWN INTO THE LOCAL
WATERS THROUGH SATURDAY BEFORE SHIFTING CLOSER OVERHEAD SAT NIGHT
AND THEN OFF SHORE THROUGH SUNDAY. WINDS ON THE FRONT END OF THE
SYSTEM WILL BE NORTHEAST INITIALLY UP TO 15 TO 20 KTS BUT WILL VEER
AROUND THROUGH THE WEEKEND AND LIGHTEN TO 10 KTS OR SO AS GRADIENT
RELAXES. BY SATURDAY EVENING WINDS WILL BE VERY LIGHT OUT OF THE
E-NE AND BY SUNDAY A RETURN FLOW WILL SET UP AS WINDS VEER AROUND
TO THE SOUTH REMAINING 10 KTS OR LESS.
SEAS WILL JUST BE COMING DOWN FROM NEAR SCA CONDITIONS SAT
MORNING IN OUTER WATERS AND WILL CONTINUE TO SUBSIDE THROUGH THE
WEEKEND AS THEY VEER AROUND FROM NORTHEAST TO SOUTHEAST AND
LIGHTEN. BY SUNDAY SEAS WILL BE 3 FT OR LESS.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 3 AM FRIDAY...A MORE SUMMER LIKE PATTERN WILL BE SETTING
UP THROUGH NEXT WEEK AS RETURN FLOW PERSISTS AROUND BERMUDA HIGH
PRESSURE. WINDS WILL REMAIN SOUTHERLY AROUND 10 KTS OR SO. WINDS
AND SEAS WILL SPIKE UP NEAR SHORE IN FAIRLY POTENT SEA BREEZE EACH
AFTERNOON...BUT OTHERWISE EXPECT SEAS 3 FT OR LESS.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 3 PM EDT THIS AFTERNOON FOR AMZ256.
SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR AMZ250-
252.
&&
$$
NEAR TERM...REK/TRA
SHORT TERM...
LONG TERM...
AVIATION...BJR
MARINE...REK/TRA
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1235 PM EDT FRI APR 5 2013
.SYNOPSIS...
LOW PRESSURE SYSTEM JUST OFF THE NORTH CAROLINA COAST WILL
CONTINUE TO LIFT OFF TO THE NORTHEAST AWAY FROM THE AREA THROUGH
TODAY. HIGH PRESSURE WILL BUILD IN BEHIND THIS STORM SYSTEM...
BRINGING A WARMING TREND AND SPRING-LIKE TEMPERATURES THROUGH NEXT
WEEK. A MORE SUMMER-LIKE PATTERN SETS UP THROUGH MID WEEK AS BERMUDA
HIGH PRESSURE DOMINATES BEFORE A COLD FRONT APPROACHES FROM THE WEST
TOWARD LATE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 12:30 PM FRIDAY...OTHER THAN FOR GEORGETOWN COUNTY THE
LATEST GUIDANCE AND RADAR LOOPS SUGGEST THAT PRECIP HAS ENDED FOR
THE DAY. HAVE ALREADY CUT BACK ON POPS WITH THE LATEST
ISSUANCES...AND WILL LIKELY MAY DROP POPS COMPLETELY WITH THE NEXT
FORECAST PACKAGE. PREVIOUS DISCUSSION FOLLOWS:
AN UPPER LEVEL DISTURBANCE MOVING RAPIDLY NORTH THROUGH GEORGIA
AND NOW SOUTH CAROLINA HAS PRODUCED AN IMPRESSIVE AREA OF SHOWERS
AND THUNDERSTORMS EXTENDING FROM GEORGETOWN SC SOUTH BACK INTO
WAYCROSS AND AMERICUS GA VICINITY. THIS CONVECTION IS ELEVATED
WITH THE LIFTING PARCEL LEVEL PROBABLY IN THE VICINITY OF 10000 FT
AGL OR 700 MB. LATEST RUC ANALYSIS SHOWS LAPSE RATES IN THE
700-500 MB LAYER ARE EXCEEDING 7C/KM...AND FORECAST SOUNDINGS FROM
VIRTUALLY ANY MODEL SHOW STEEP LAPSE RATES CONTINUING FOR AT LEAST
ANOTHER 100 MB HIGHER IN THE ATMOSPHERE.
I HAVE INCREASED POPS MAINLY ALONG THE SC COAST AND OFFSHORE FOR THE
MORNING HOURS TO ACCOUNT FOR THIS ACTIVITY. FORTUNATELY THERE IS NO
SEVERE WEATHER THREAT OWNING TO THE DEEP FRONTAL INVERSION BELOW THE
STORMS AND SMALL CAPE VALUES ALOFT LIMITING POTENTIAL HAIL
PRODUCTION. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
SURFACE LOW PRESSURE MOVED ALMOST DIRECTLY OVER ILM AROUND MIDNIGHT.
NOW THAT THE LOW IS RACING NORTHEAST ACROSS EXTREME EASTERN NC COOL
AIR HAS RUSHED DOWN TO THE CAPE FEAR AND GRAND STRAND BEACHES. LOW
STRATUS CLOUDS WILL BE VERY TOUGH TO ERODE TODAY...AND IN FACT
MODELS SUGGEST A SOLID GRAY OVERCAST WILL PERSIST THROUGH THE
MORNING HOURS...RELUCTANTLY LIFTING INTO A SCT-BKN STRATOCUMULUS
DECK SOMETIME IN THE 11 AM TO 2 PM PERIOD. IT APPEARS THE NAM HAS A
BETTER HANDLE ON THE LATER CLOUD BURNOFF THAN THE GFS...THEREFORE MY
FORECAST HIGHS ARE CLOSE THE NAM AND RANGE FROM THE UPPER 50S NEAR
THE COAST TO AROUND 60 INLAND...10-13 DEGREES BELOW NORMAL.
OF MORE IMMEDIATE CONCERN IS A CLUSTER OF THUNDERSTORMS ACROSS
SOUTHERN GEORGIA ASSOCIATED WITH AN 500 MB VORT MAX ROTATING
NORTHEASTWARD AROUND THE MAIN UPPER LOW STILL BACK ON THE
MISSISSIPPI-ALABAMA BORDER. THIS CONVECTION APPEARS TO BE BASED
AROUND 700 MB AND IS TAKING ADVANTAGE OF STEEPENING LAPSE RATES IN
THE 700-400 MB LAYER AS COLD AIR WITH THE UPPER LOW ADVECTS ACROSS
THE SOUTHEAST. IT IS POSSIBLE THESE SHOWERS AND THUNDERSTORMS WILL
AFFECT COASTAL SOUTH CAROLINA LATER THIS MORNING...WHERE I HAVE A
30-40 PERCENT POP IN THE FORECAST. POPS ELSEWHERE ARE IN THE 10-20
PERCENT RANGE HEDGING FOR ANY EXPANSION IN THIS AREA OF ELEVATED
CONVECTION.
THE AFOREMENTIONED UPPER LOW WILL MOVE EAST ACROSS ALABAMA AND
GEORGIA THIS MORNING...THEN INTO SOUTH CAROLINA BY MID AFTERNOON.
LOW AND MID CLOUDS MAY CONTINUE ALONG THE COAST INTO THE EVENING
HOURS BUT CLEARING SKIES SHOULD DEVELOP FROM WEST TO EAST AS THE
UPPER LOW MOVES ACROSS. A NEW AREA OF SURFACE LOW PRESSURE WILL
DEVELOP WELL OFF THE GA/SC COAST LATE THIS AFTERNOON IN ADVANCE OF
THE UPPER SYSTEM. THIS NEW LOW SHOULD REMAIN TOO FAR AWAY FOR ANY
DIRECT IMPACTS ON OUR AREA...BUT NORTHERLY FLOW BEHIND THIS LOW WILL
HELP MAINLY A CHILLY AIRMASS ACROSS THE CAROLINAS TONIGHT WITH LOWS
FALLING TO 40-45...A FEW DEGREES BELOW NORMAL.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...HIGH PRESSURE WILL BUILD DOWN OVER THE
SOUTHEAST THROUGH THE WEEKEND. A COOLER NORTHERLY FLOW INITIALLY
WILL WEAKEN AND BECOME LIGHT AS IT VEERS AROUND THROUGH SAT NIGHT AS
CENTER OF HIGH SHIFTS CLOSER OVERHEAD AND THEN OFF SHORE BY
MORNING. THE MAX CAA WILL CUT OFF EARLY SATURDAY AS 850 TEMPS DROP
CLOSE TO 3C. EXPECT AFTERNOON HIGHS TO ONCE AGAIN REMAIN BELOW
NORMAL REACHING INTO THE LOW TO MID 60S. CALM WINDS AND CLEAR
SKIES SATURDAY NIGHT WILL PROVIDE MORE IDEAL RADIATIONAL COOLING
CONDITIONS WITH TEMPS DROPPING INTO THE LOWER END OF THE 40S MOST
PLACES...BUT SLIGHTLY WARMER AT THE BEACHES.
BY SUNDAY A RETURN FLOW WILL SET UP WITH LIGHT SOUTHERLY WINDS
BEGINNING A WARMING TREND INTO NEXT WEEK. TEMPS WILL APPROACH
NORMAL VALUES FOR THIS TIME OF YEAR WITH HIGH TEMPS JUST REACHING
INTO THE 70S UNDER PLENTY OF SUNSHINE.
OVERALL A BEAUTIFUL WEEKEND WITH LOTS OF SPRING SUNSHINE BUT
SLIGHTLY COOLER TEMPS.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 3 AM FRIDAY...HEADING INTO A MORE SUMMER LIKE PATTERN FOR
THIS TIME OF YEAR. BERMUDA HIGH PRESSURE WITH A WARMER MOISTER
SOUTHERLY RETURN FLOW THROUGH THE PERIOD. A DEEP RIDGE BUILDS
ALOFT WITH HEIGHT RISES PEAKING MID WEEK UP CLOSE TO 585 DM.
AS THE MID TO UPPER RIDGE BUILDS UP THE EAST COAST A DEEPENING
TROUGH WILL DIG DOWN THROUGH THE MID WEST. ALTHOUGH THE RIDGE
HOLDS ON TIGHT THROUGH MUCH OF THE WORK WEEK...THE TROUGH FINALLY
MOVES EAST TOWARD THE AREA PUSHING A COLD FRONT OUR WAY BY THURS
NIGHT INTO FRIDAY. MODELS HAVE PUSHED THE TIMING BACK A BIT AND
THEREFORE LOOKS LIKE NICE WEATHER WILL HOLD OUT THROUGH THURSDAY.
OVERALL A RAIN FREE WEEK WITH A SHARP WARMING TREND BRINGING TEMPS
TO SEVERAL DEGREES ABOVE NORMAL WITH HIGH TEMPS FLIRTING WITH 80
OR SLIGHTLY ABOVE IN PLACES AND MIN TEMPS CLOSE TO WHAT WE HAVE
BEEN EXPERIENCING FOR HIGH TEMPS LATELY. THE COOLER OCEAN TEMPS
WILL MAXIMIZE THE DIFFERENTIAL HEATING ALLOWING FOR A STRONG SEA
BREEZE TO CARRY FAR INLAND MOST AFTERNOONS. THIS WILL BRING COOLER
AIR INLAND BUT WILL ALSO KEEP THE BEACHES MUCH COOLER.
THE SEA BREEZE WILL ALSO PROVIDE A FOCAL POINT FOR ENOUGH
CONVERGENCE TO PRODUCE CU EACH AFTERNOON AND MAY SEE SOME PASSING
HIGH CLOUDS BUT OTHERWISE SHOULD SEE A GOOD DEAL OF SUNSHINE
THROUGH THE WEEK WITH ANY PCP HOLDING OFF UNTIL LATE THURS INTO
FRIDAY.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 12Z...RADAR INDICATES SOME SHOWER ACTIVITY NEAR KMYR/KCRE IS
MOVING NORTHEAST UP THE CAROLINA COAST. MOST OF THE ACTIVITY IS
REMAINING OFFSHORE...AND DO NOT EXPECT ANY PCPN FOR KILM ATTM.
WIDESPREAD IFR CIGS ARE BEING REPORTED AT ALL TERMS THIS MORNING.
GFS AND NAM GUIDANCE IN GOOD AGREEMENT THAT IFR WILL PERSIST FOR
MUCH OF THE MORNING...ESPECIALLY ALONG THE COAST. KFLO/KLBT CIGS
WILL LIKELY LIFT ABOVE 1KFT BY MID TO LATE MORNING...WHEREAS
KILM/KMYR/KCRE COULD SEE IFR CONDITIONS LINGER UNTIL MIDDAY. ONCE
THE STRATUS FINALLY LIFTS...EXPECT MVFR IN THE EARLY AFTERNOON TO
BECOME VFR BY LATE AFTERNOON THROUGH THE END OF THE TAF PERIOD.
NORTHWEST WINDS AOB 12 KTS THIS MORNING WILL VEER TO THE NORTH LATER
TODAY...REMAINING AOB 10 KTS. THE SKIES WILL CLEAR OUT OVERNIGHT AS
AN UPPER LOW PUSHES THROUGH THE CAROLINAS.
EXTENDED OUTLOOK...VFR EXPECTED SATURDAY THROUGH TUESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 12:30 PM FRIDAY...LATEST OBS AND GUIDANCE SUGGEST THAT WE
CAN DROP SMALL CRAFT ADVISORIES EARLY FOR ALL THE REMAINING
COASTAL WATERS. IT IS LIKELY WE ARE NOW ONLY SEEING 6 FOOTERS OVER
THE OUTER EDGES OF THE COASTAL WATERS. PREVIOUS DISCUSSION
FOLLOWS:
TWO CHANGES HAVE BEEN MADE TO THE MARINE FORECAST THIS MORNING.
THE FIRST IS TO INCREASE SHOWER AND T-STORM CHANCES THROUGH THE
MORNING HOURS AS THE WILMINGTON AND CHARLESTON RADARS ARE SHOWING
AN IMPRESSIVE AREA OF SHOWERS AND STORMS MOVING RAPIDLY NORTHEAST
ALONG THE COAST. THE SOUTH CAROLINA COASTAL WATERS WILL BE MOST
STRONGLY AFFECTED BY THIS ACTIVITY...WHICH SHOULD TAPER OFF BY
NOON. ALSO...OBSERVED WIND SPEEDS ARE ABOUT 5 KNOTS STRONGER THAN
EXPECTED ACROSS THE WATERS NORTH OF CAPE FEAR...WHERE RECENTLY
GUSTS AT BOTH WRIGHTSVILLE BEACH AND THE FRYING PAN SHOALS BUOY
OFFSHORE HAVE BEEN AROUND 20 KNOTS. NO OTHER SIGNIFICANT CHANGES
HAVE BEEN MADE. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
SURFACE LOW PRESSURE MOVED OVER WILMINGTON AROUND MIDNIGHT AND IS
NOW RACING NORTHEAST ACROSS THE PAMLICO SOUND. NORTHWESTERLY WINDS
BEHIND THIS LOW HAVE PUSHED THE COLD FRONT A CONSIDERABLE DISTANCE
FROM SHORE...AND COOL NORTHWEST TO NORTH WINDS SHOULD CONTINUE
THROUGH THE DAY. STRONG WINDS YESTERDAY STILL HAVE THE SEA STATE
QUITE AGITATED AND IT WILL TAKE MOST OF THE DAY FOR SEAS TO DECAY
BELOW 6 FEET. FOR THIS REASON THE SMALL CRAFT ADVISORY WILL REMAIN
POSTED INTO THE AFTERNOON HOURS FOR THE SC COASTAL WATERS...AND
UNTIL THIS EVENING FOR THE NC WATERS.
AN APPROACHING UPPER LEVEL LOW WILL INDUCE A NEW LOW TO DEVELOP WELL
OFF THE SC COAST LATE THIS AFTERNOON. WHILE THIS NEW LOW WILL HAVE
NO DIRECT IMPACTS LOCALLY...IT WILL HELP TO ENHANCE THE NORTHERLY
WINDS SOMEWHAT WITH WIND SPEEDS PERHAPS ECLIPSING 15 KNOTS
OVERNIGHT...ESPECIALLY AWAY FROM SHORE.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...HIGH PRESSURE WILL BUILD DOWN INTO THE LOCAL
WATERS THROUGH SATURDAY BEFORE SHIFTING CLOSER OVERHEAD SAT NIGHT
AND THEN OFF SHORE THROUGH SUNDAY. WINDS ON THE FRONT END OF THE
SYSTEM WILL BE NORTHEAST INITIALLY UP TO 15 TO 20 KTS BUT WILL VEER
AROUND THROUGH THE WEEKEND AND LIGHTEN TO 10 KTS OR SO AS GRADIENT
RELAXES. BY SATURDAY EVENING WINDS WILL BE VERY LIGHT OUT OF THE
E-NE AND BY SUNDAY A RETURN FLOW WILL SET UP AS WINDS VEER AROUND
TO THE SOUTH REMAINING 10 KTS OR LESS.
SEAS WILL JUST BE COMING DOWN FROM NEAR SCA CONDITIONS SAT
MORNING IN OUTER WATERS AND WILL CONTINUE TO SUBSIDE THROUGH THE
WEEKEND AS THEY VEER AROUND FROM NORTHEAST TO SOUTHEAST AND
LIGHTEN. BY SUNDAY SEAS WILL BE 3 FT OR LESS.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 3 AM FRIDAY...A MORE SUMMER LIKE PATTERN WILL BE SETTING
UP THROUGH NEXT WEEK AS RETURN FLOW PERSISTS AROUND BERMUDA HIGH
PRESSURE. WINDS WILL REMAIN SOUTHERLY AROUND 10 KTS OR SO. WINDS
AND SEAS WILL SPIKE UP NEAR SHORE IN FAIRLY POTENT SEA BREEZE EACH
AFTERNOON...BUT OTHERWISE EXPECT SEAS 3 FT OR LESS.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 3 PM EDT THIS AFTERNOON FOR AMZ256.
SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR AMZ250-
252.
&&
$$
NEAR TERM...TRA
SHORT TERM...REK
LONG TERM...
AVIATION...BJR
MARINE...REK/TRA
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
738 AM EDT FRI APR 5 2013
.SYNOPSIS...
LOW PRESSURE SYSTEM JUST OFF THE NORTH CAROLINA COAST WILL
CONTINUE TO LIFT OFF TO THE NORTHEAST AWAY FROM THE AREA THROUGH
TODAY. HIGH PRESSURE WILL BUILD IN BEHIND THIS STORM SYSTEM...
BRINGING A WARMING TREND AND SPRING-LIKE TEMPERATURES THROUGH NEXT
WEEK. A MORE SUMMER-LIKE PATTERN SETS UP THROUGH MID WEEK AS BERMUDA
HIGH PRESSURE DOMINATES BEFORE A COLD FRONT APPROACHES FROM THE WEST
TOWARD LATE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM FRIDAY...AN UPPER LEVEL DISTURBANCE MOVING RAPIDLY
NORTH THROUGH GEORGIA AND NOW SOUTH CAROLINA HAS PRODUCED AN
IMPRESSIVE AREA OF SHOWERS AND THUNDERSTORMS EXTENDING FROM
GEORGETOWN SC SOUTH BACK INTO WAYCROSS AND AMERICUS GA VICINITY.
THIS CONVECTION IS ELEVATED WITH THE LIFTING PARCEL LEVEL PROBABLY
IN THE VICINITY OF 10000 FT AGL OR 700 MB. LATEST RUC ANALYSIS SHOWS
LAPSE RATES IN THE 700-500 MB LAYER ARE EXCEEDING 7C/KM...AND
FORECAST SOUNDINGS FROM VIRTUALLY ANY MODEL SHOW STEEP LAPSE RATES
CONTINUING FOR AT LEAST ANOTHER 100 MB HIGHER IN THE ATMOSPHERE.
I HAVE INCREASED POPS MAINLY ALONG THE SC COAST AND OFFSHORE FOR THE
MORNING HOURS TO ACCOUNT FOR THIS ACTIVITY. FORTUNATELY THERE IS NO
SEVERE WEATHER THREAT OWNING TO THE DEEP FRONTAL INVERSION BELOW THE
STORMS AND SMALL CAPE VALUES ALOFT LIMITING POTENTIAL HAIL
PRODUCTION. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
SURFACE LOW PRESSURE MOVED ALMOST DIRECTLY OVER ILM AROUND MIDNIGHT.
NOW THAT THE LOW IS RACING NORTHEAST ACROSS EXTREME EASTERN NC COOL
AIR HAS RUSHED DOWN TO THE CAPE FEAR AND GRAND STRAND BEACHES. LOW
STRATUS CLOUDS WILL BE VERY TOUGH TO ERODE TODAY...AND IN FACT
MODELS SUGGEST A SOLID GRAY OVERCAST WILL PERSIST THROUGH THE
MORNING HOURS...RELUCTANTLY LIFTING INTO A SCT-BKN STRATOCUMULUS
DECK SOMETIME IN THE 11 AM TO 2 PM PERIOD. IT APPEARS THE NAM HAS A
BETTER HANDLE ON THE LATER CLOUD BURNOFF THAN THE GFS...THEREFORE MY
FORECAST HIGHS ARE CLOSE THE NAM AND RANGE FROM THE UPPER 50S NEAR
THE COAST TO AROUND 60 INLAND...10-13 DEGREES BELOW NORMAL.
OF MORE IMMEDIATE CONCERN IS A CLUSTER OF THUNDERSTORMS ACROSS
SOUTHERN GEORGIA ASSOCIATED WITH AN 500 MB VORT MAX ROTATING
NORTHEASTWARD AROUND THE MAIN UPPER LOW STILL BACK ON THE
MISSISSIPPI-ALABAMA BORDER. THIS CONVECTION APPEARS TO BE BASED
AROUND 700 MB AND IS TAKING ADVANTAGE OF STEEPENING LAPSE RATES IN
THE 700-400 MB LAYER AS COLD AIR WITH THE UPPER LOW ADVECTS ACROSS
THE SOUTHEAST. IT IS POSSIBLE THESE SHOWERS AND THUNDERSTORMS WILL
AFFECT COASTAL SOUTH CAROLINA LATER THIS MORNING...WHERE I HAVE A
30-40 PERCENT POP IN THE FORECAST. POPS ELSEWHERE ARE IN THE 10-20
PERCENT RANGE HEDGING FOR ANY EXPANSION IN THIS AREA OF ELEVATED
CONVECTION.
THE AFOREMENTIONED UPPER LOW WILL MOVE EAST ACROSS ALABAMA AND
GEORGIA THIS MORNING...THEN INTO SOUTH CAROLINA BY MID AFTERNOON.
LOW AND MID CLOUDS MAY CONTINUE ALONG THE COAST INTO THE EVENING
HOURS BUT CLEARING SKIES SHOULD DEVELOP FROM WEST TO EAST AS THE
UPPER LOW MOVES ACROSS. A NEW AREA OF SURFACE LOW PRESSURE WILL
DEVELOP WELL OFF THE GA/SC COAST LATE THIS AFTERNOON IN ADVANCE OF
THE UPPER SYSTEM. THIS NEW LOW SHOULD REMAIN TOO FAR AWAY FOR ANY
DIRECT IMPACTS ON OUR AREA...BUT NORTHERLY FLOW BEHIND THIS LOW WILL
HELP MAINLY A CHILLY AIRMASS ACROSS THE CAROLINAS TONIGHT WITH LOWS
FALLING TO 40-45...A FEW DEGREES BELOW NORMAL.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...HIGH PRESSURE WILL BUILD DOWN OVER THE
SOUTHEAST THROUGH THE WEEKEND. A COOLER NORTHERLY FLOW INITIALLY
WILL WEAKEN AND BECOME LIGHT AS IT VEERS AROUND THROUGH SAT NIGHT AS
CENTER OF HIGH SHIFTS CLOSER OVERHEAD AND THEN OFF SHORE BY
MORNING. THE MAX CAA WILL CUT OFF EARLY SATURDAY AS 850 TEMPS DROP
CLOSE TO 3C. EXPECT AFTERNOON HIGHS TO ONCE AGAIN REMAIN BELOW
NORMAL REACHING INTO THE LOW TO MID 60S. CALM WINDS AND CLEAR
SKIES SATURDAY NIGHT WILL PROVIDE MORE IDEAL RADIATIONAL COOLING
CONDITIONS WITH TEMPS DROPPING INTO THE LOWER END OF THE 40S MOST
PLACES...BUT SLIGHTLY WARMER AT THE BEACHES.
BY SUNDAY A RETURN FLOW WILL SET UP WITH LIGHT SOUTHERLY WINDS
BEGINNING A WARMING TREND INTO NEXT WEEK. TEMPS WILL APPROACH
NORMAL VALUES FOR THIS TIME OF YEAR WITH HIGH TEMPS JUST REACHING
INTO THE 70S UNDER PLENTY OF SUNSHINE.
OVERALL A BEAUTIFUL WEEKEND WITH LOTS OF SPRING SUNSHINE BUT
SLIGHTLY COOLER TEMPS.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 3 AM FRIDAY...HEADING INTO A MORE SUMMER LIKE PATTERN FOR
THIS TIME OF YEAR. BERMUDA HIGH PRESSURE WITH A WARMER MOISTER
SOUTHERLY RETURN FLOW THROUGH THE PERIOD. A DEEP RIDGE BUILDS
ALOFT WITH HEIGHT RISES PEAKING MID WEEK UP CLOSE TO 585 DM.
AS THE MID TO UPPER RIDGE BUILDS UP THE EAST COAST A DEEPENING
TROUGH WILL DIG DOWN THROUGH THE MID WEST. ALTHOUGH THE RIDGE
HOLDS ON TIGHT THROUGH MUCH OF THE WORK WEEK...THE TROUGH FINALLY
MOVES EAST TOWARD THE AREA PUSHING A COLD FRONT OUR WAY BY THURS
NIGHT INTO FRIDAY. MODELS HAVE PUSHED THE TIMING BACK A BIT AND
THEREFORE LOOKS LIKE NICE WEATHER WILL HOLD OUT THROUGH THURSDAY.
OVERALL A RAIN FREE WEEK WITH A SHARP WARMING TREND BRINGING TEMPS
TO SEVERAL DEGREES ABOVE NORMAL WITH HIGH TEMPS FLIRTING WITH 80
OR SLIGHTLY ABOVE IN PLACES AND MIN TEMPS CLOSE TO WHAT WE HAVE
BEEN EXPERIENCING FOR HIGH TEMPS LATELY. THE COOLER OCEAN TEMPS
WILL MAXIMIZE THE DIFFERENTIAL HEATING ALLOWING FOR A STRONG SEA
BREEZE TO CARRY FAR INLAND MOST AFTERNOONS. THIS WILL BRING COOLER
AIR INLAND BUT WILL ALSO KEEP THE BEACHES MUCH COOLER.
THE SEA BREEZE WILL ALSO PROVIDE A FOCAL POINT FOR ENOUGH
CONVERGENCE TO PRODUCE CU EACH AFTERNOON AND MAY SEE SOME PASSING
HIGH CLOUDS BUT OTHERWISE SHOULD SEE A GOOD DEAL OF SUNSHINE
THROUGH THE WEEK WITH ANY PCP HOLDING OFF UNTIL LATE THURS INTO
FRIDAY.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AS OF 12Z...RADAR INDICATES SOME SHOWER ACTIVITY NEAR KMYR/KCRE IS
MOVING NORTHEAST UP THE CAROLINA COAST. MOST OF THE ACTIVITY IS
REMAINING OFFSHORE...AND DO NOT EXPECT ANY PCPN FOR KILM ATTM.
WIDESPREAD IFR CIGS ARE BEING REPORTED AT ALL TERMS THIS MORNING.
GFS AND NAM GUIDANCE IN GOOD AGREEMENT THAT IFR WILL PERSIST FOR
MUCH OF THE MORNING...ESPECIALLY ALONG THE COAST. KFLO/KLBT CIGS
WILL LIKELY LIFT ABOVE 1KFT BY MID TO LATE MORNING...WHEREAS
KILM/KMYR/KCRE COULD SEE IFR CONDITIONS LINGER UNTIL MIDDAY. ONCE
THE STRATUS FINALLY LIFTS...EXPECT MVFR IN THE EARLY AFTERNOON TO
BECOME VFR BY LATE AFTERNOON THROUGH THE END OF THE TAF PERIOD.
NORTHWEST WINDS AOB 12 KTS THIS MORNING WILL VEER TO THE NORTH LATER
TODAY...REMAINING AOB 10 KTS. THE SKIES WILL CLEAR OUT OVERNIGHT AS
AN UPPER LOW PUSHES THROUGH THE CAROLINAS.
EXTENDED OUTLOOK...VFR EXPECTED SATURDAY THROUGH TUESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM FRIDAY...TWO CHANGES HAVE BEEN MADE TO THE MARINE
FORECAST THIS MORNING. THE FIRST IS TO INCREASE SHOWER AND T-STORM
CHANCES THROUGH THE MORNING HOURS AS THE WILMINGTON AND CHARLESTON
RADARS ARE SHOWING AN IMPRESSIVE AREA OF SHOWERS AND STORMS MOVING
RAPIDLY NORTHEAST ALONG THE COAST. THE SOUTH CAROLINA COASTAL WATERS
WILL BE MOST STRONGLY AFFECTED BY THIS ACTIVITY...WHICH SHOULD TAPER
OFF BY NOON. ALSO...OBSERVED WIND SPEEDS ARE ABOUT 5 KNOTS STRONGER
THAN EXPECTED ACROSS THE WATERS NORTH OF CAPE FEAR...WHERE RECENTLY
GUSTS AT BOTH WRIGHTSVILLE BEACH AND THE FRYING PAN SHOALS BUOY
OFFSHORE HAVE BEEN AROUND 20 KNOTS. NO OTHER SIGNIFICANT CHANGES
HAVE BEEN MADE. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
SURFACE LOW PRESSURE MOVED OVER WILMINGTON AROUND MIDNIGHT AND IS
NOW RACING NORTHEAST ACROSS THE PAMLICO SOUND. NORTHWESTERLY WINDS
BEHIND THIS LOW HAVE PUSHED THE COLD FRONT A CONSIDERABLE DISTANCE
FROM SHORE...AND COOL NORTHWEST TO NORTH WINDS SHOULD CONTINUE
THROUGH THE DAY. STRONG WINDS YESTERDAY STILL HAVE THE SEA STATE
QUITE AGITATED AND IT WILL TAKE MOST OF THE DAY FOR SEAS TO DECAY
BELOW 6 FEET. FOR THIS REASON THE SMALL CRAFT ADVISORY WILL REMAIN
POSTED INTO THE AFTERNOON HOURS FOR THE SC COASTAL WATERS...AND
UNTIL THIS EVENING FOR THE NC WATERS.
AN APPROACHING UPPER LEVEL LOW WILL INDUCE A NEW LOW TO DEVELOP WELL
OFF THE SC COAST LATE THIS AFTERNOON. WHILE THIS NEW LOW WILL HAVE
NO DIRECT IMPACTS LOCALLY...IT WILL HELP TO ENHANCE THE NORTHERLY
WINDS SOMEWHAT WITH WIND SPEEDS PERHAPS ECLIPSING 15 KNOTS
OVERNIGHT...ESPECIALLY AWAY FROM SHORE.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...HIGH PRESSURE WILL BUILD DOWN INTO THE LOCAL
WATERS THROUGH SATURDAY BEFORE SHIFTING CLOSER OVERHEAD SAT NIGHT
AND THEN OFF SHORE THROUGH SUNDAY. WINDS ON THE FRONT END OF THE
SYSTEM WILL BE NORTHEAST INITIALLY UP TO 15 TO 20 KTS BUT WILL VEER
AROUND THROUGH THE WEEKEND AND LIGHTEN TO 10 KTS OR SO AS GRADIENT
RELAXES. BY SATURDAY EVENING WINDS WILL BE VERY LIGHT OUT OF THE
E-NE AND BY SUNDAY A RETURN FLOW WILL SET UP AS WINDS VEER AROUND
TO THE SOUTH REMAINING 10 KTS OR LESS.
SEAS WILL JUST BE COMING DOWN FROM NEAR SCA CONDITIONS SAT
MORNING IN OUTER WATERS AND WILL CONTINUE TO SUBSIDE THROUGH THE
WEEKEND AS THEY VEER AROUND FROM NORTHEAST TO SOUTHEAST AND
LIGHTEN. BY SUNDAY SEAS WILL BE 3 FT OR LESS.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 3 AM FRIDAY...A MORE SUMMER LIKE PATTERN WILL BE SETTING
UP THROUGH NEXT WEEK AS RETURN FLOW PERSISTS AROUND BERMUDA HIGH
PRESSURE. WINDS WILL REMAIN SOUTHERLY AROUND 10 KTS OR SO. WINDS
AND SEAS WILL SPIKE UP NEAR SHORE IN FAIRLY POTENT SEA BREEZE EACH
AFTERNOON...BUT OTHERWISE EXPECT SEAS 3 FT OR LESS.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 3 PM EDT THIS AFTERNOON FOR AMZ256.
SMALL CRAFT ADVISORY UNTIL NOON EDT TODAY FOR AMZ254.
SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR AMZ250-
252.
&&
$$
NEAR TERM...TRA
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
626 AM EDT FRI APR 5 2013
.SYNOPSIS...
LOW PRESSURE SYSTEM JUST OFF THE NORTH CAROLINA COAST WILL
CONTINUE TO LIFT OFF TO THE NORTHEAST AWAY FROM THE AREA THROUGH
TODAY. HIGH PRESSURE WILL BUILD IN BEHIND THIS STORM SYSTEM...
BRINGING A WARMING TREND AND SPRING-LIKE TEMPERATURES THROUGH NEXT
WEEK. A MORE SUMMER-LIKE PATTERN SETS UP THROUGH MID WEEK AS BERMUDA
HIGH PRESSURE DOMINATES BEFORE A COLD FRONT APPROACHES FROM THE WEST
TOWARD LATE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM FRIDAY...AN UPPER LEVEL DISTURBANCE MOVING RAPIDLY
NORTH THROUGH GEORGIA AND NOW SOUTH CAROLINA HAS PRODUCED AN
IMPRESSIVE AREA OF SHOWERS AND THUNDERSTORMS EXTENDING FROM
GEORGETOWN SC SOUTH BACK INTO WAYCROSS AND AMERICUS GA VICINITY.
THIS CONVECTION IS ELEVATED WITH THE LIFTING PARCEL LEVEL PROBABLY
IN THE VICINITY OF 10000 FT AGL OR 700 MB. LATEST RUC ANALYSIS SHOWS
LAPSE RATES IN THE 700-500 MB LAYER ARE EXCEEDING 7C/KM...AND
FORECAST SOUNDINGS FROM VIRTUALLY ANY MODEL SHOW STEEP LAPSE RATES
CONTINUING FOR AT LEAST ANOTHER 100 MB HIGHER IN THE ATMOSPHERE.
I HAVE INCREASED POPS MAINLY ALONG THE SC COAST AND OFFSHORE FOR THE
MORNING HOURS TO ACCOUNT FOR THIS ACTIVITY. FORTUNATELY THERE IS NO
SEVERE WEATHER THREAT OWNING TO THE DEEP FRONTAL INVERSION BELOW THE
STORMS AND SMALL CAPE VALUES ALOFT LIMITING POTENTIAL HAIL
PRODUCTION. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
SURFACE LOW PRESSURE MOVED ALMOST DIRECTLY OVER ILM AROUND MIDNIGHT.
NOW THAT THE LOW IS RACING NORTHEAST ACROSS EXTREME EASTERN NC COOL
AIR HAS RUSHED DOWN TO THE CAPE FEAR AND GRAND STRAND BEACHES. LOW
STRATUS CLOUDS WILL BE VERY TOUGH TO ERODE TODAY...AND IN FACT
MODELS SUGGEST A SOLID GRAY OVERCAST WILL PERSIST THROUGH THE
MORNING HOURS...RELUCTANTLY LIFTING INTO A SCT-BKN STRATOCUMULUS
DECK SOMETIME IN THE 11 AM TO 2 PM PERIOD. IT APPEARS THE NAM HAS A
BETTER HANDLE ON THE LATER CLOUD BURNOFF THAN THE GFS...THEREFORE MY
FORECAST HIGHS ARE CLOSE THE NAM AND RANGE FROM THE UPPER 50S NEAR
THE COAST TO AROUND 60 INLAND...10-13 DEGREES BELOW NORMAL.
OF MORE IMMEDIATE CONCERN IS A CLUSTER OF THUNDERSTORMS ACROSS
SOUTHERN GEORGIA ASSOCIATED WITH AN 500 MB VORT MAX ROTATING
NORTHEASTWARD AROUND THE MAIN UPPER LOW STILL BACK ON THE
MISSISSIPPI-ALABAMA BORDER. THIS CONVECTION APPEARS TO BE BASED
AROUND 700 MB AND IS TAKING ADVANTAGE OF STEEPENING LAPSE RATES IN
THE 700-400 MB LAYER AS COLD AIR WITH THE UPPER LOW ADVECTS ACROSS
THE SOUTHEAST. IT IS POSSIBLE THESE SHOWERS AND THUNDERSTORMS WILL
AFFECT COASTAL SOUTH CAROLINA LATER THIS MORNING...WHERE I HAVE A
30-40 PERCENT POP IN THE FORECAST. POPS ELSEWHERE ARE IN THE 10-20
PERCENT RANGE HEDGING FOR ANY EXPANSION IN THIS AREA OF ELEVATED
CONVECTION.
THE AFOREMENTIONED UPPER LOW WILL MOVE EAST ACROSS ALABAMA AND
GEORGIA THIS MORNING...THEN INTO SOUTH CAROLINA BY MID AFTERNOON.
LOW AND MID CLOUDS MAY CONTINUE ALONG THE COAST INTO THE EVENING
HOURS BUT CLEARING SKIES SHOULD DEVELOP FROM WEST TO EAST AS THE
UPPER LOW MOVES ACROSS. A NEW AREA OF SURFACE LOW PRESSURE WILL
DEVELOP WELL OFF THE GA/SC COAST LATE THIS AFTERNOON IN ADVANCE OF
THE UPPER SYSTEM. THIS NEW LOW SHOULD REMAIN TOO FAR AWAY FOR ANY
DIRECT IMPACTS ON OUR AREA...BUT NORTHERLY FLOW BEHIND THIS LOW WILL
HELP MAINLY A CHILLY AIRMASS ACROSS THE CAROLINAS TONIGHT WITH LOWS
FALLING TO 40-45...A FEW DEGREES BELOW NORMAL.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...HIGH PRESSURE WILL BUILD DOWN OVER THE
SOUTHEAST THROUGH THE WEEKEND. A COOLER NORTHERLY FLOW INITIALLY
WILL WEAKEN AND BECOME LIGHT AS IT VEERS AROUND THROUGH SAT NIGHT AS
CENTER OF HIGH SHIFTS CLOSER OVERHEAD AND THEN OFF SHORE BY
MORNING. THE MAX CAA WILL CUT OFF EARLY SATURDAY AS 850 TEMPS DROP
CLOSE TO 3C. EXPECT AFTERNOON HIGHS TO ONCE AGAIN REMAIN BELOW
NORMAL REACHING INTO THE LOW TO MID 60S. CALM WINDS AND CLEAR
SKIES SATURDAY NIGHT WILL PROVIDE MORE IDEAL RADIATIONAL COOLING
CONDITIONS WITH TEMPS DROPPING INTO THE LOWER END OF THE 40S MOST
PLACES...BUT SLIGHTLY WARMER AT THE BEACHES.
BY SUNDAY A RETURN FLOW WILL SET UP WITH LIGHT SOUTHERLY WINDS
BEGINNING A WARMING TREND INTO NEXT WEEK. TEMPS WILL APPROACH
NORMAL VALUES FOR THIS TIME OF YEAR WITH HIGH TEMPS JUST REACHING
INTO THE 70S UNDER PLENTY OF SUNSHINE.
OVERALL A BEAUTIFUL WEEKEND WITH LOTS OF SPRING SUNSHINE BUT
SLIGHTLY COOLER TEMPS.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 3 AM FRIDAY...HEADING INTO A MORE SUMMER LIKE PATTERN FOR
THIS TIME OF YEAR. BERMUDA HIGH PRESSURE WITH A WARMER MOISTER
SOUTHERLY RETURN FLOW THROUGH THE PERIOD. A DEEP RIDGE BUILDS
ALOFT WITH HEIGHT RISES PEAKING MID WEEK UP CLOSE TO 585 DM.
AS THE MID TO UPPER RIDGE BUILDS UP THE EAST COAST A DEEPENING
TROUGH WILL DIG DOWN THROUGH THE MID WEST. ALTHOUGH THE RIDGE
HOLDS ON TIGHT THROUGH MUCH OF THE WORK WEEK...THE TROUGH FINALLY
MOVES EAST TOWARD THE AREA PUSHING A COLD FRONT OUR WAY BY THURS
NIGHT INTO FRIDAY. MODELS HAVE PUSHED THE TIMING BACK A BIT AND
THEREFORE LOOKS LIKE NICE WEATHER WILL HOLD OUT THROUGH THURSDAY.
OVERALL A RAIN FREE WEEK WITH A SHARP WARMING TREND BRINGING TEMPS
TO SEVERAL DEGREES ABOVE NORMAL WITH HIGH TEMPS FLIRTING WITH 80
OR SLIGHTLY ABOVE IN PLACES AND MIN TEMPS CLOSE TO WHAT WE HAVE
BEEN EXPERIENCING FOR HIGH TEMPS LATELY. THE COOLER OCEAN TEMPS
WILL MAXIMIZE THE DIFFERENTIAL HEATING ALLOWING FOR A STRONG SEA
BREEZE TO CARRY FAR INLAND MOST AFTERNOONS. THIS WILL BRING COOLER
AIR INLAND BUT WILL ALSO KEEP THE BEACHES MUCH COOLER.
THE SEA BREEZE WILL ALSO PROVIDE A FOCAL POINT FOR ENOUGH
CONVERGENCE TO PRODUCE CU EACH AFTERNOON AND MAY SEE SOME PASSING
HIGH CLOUDS BUT OTHERWISE SHOULD SEE A GOOD DEAL OF SUNSHINE
THROUGH THE WEEK WITH ANY PCP HOLDING OFF UNTIL LATE THURS INTO
FRIDAY.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 06Z...THE SURFACE LOW MOVED ESSENTIALLY OVER ILM AROUND
MIDNIGHT AND IS NOW MOVING NE TOWARD THE NC OUTER BANKS. WINDS HAVE
SHIFTED TO NW ACROSS THE AREA AND SHOULD VEER MORE NORTHERLY AFTER
DAYBREAK. SOLID IFR/LIFR CIGS ARE EXPECTED TO PREVAIL THROUGH MUCH
OF THE MORNING HOURS. IFR/MVFR VSBYS DUE TO DZ SHOULD DISSIPATE BY
08Z AS THE CLOUD DEPTH THINS FROM ALOFT.
CIGS WILL BE SLOW TO LIFT LATER TODAY...PERHAPS TAKING UNTIL 14Z
INLAND AND 17Z AT THE COAST TO LIFT ABOVE 1000 FT AGL. VFR CIGS ARE
ANTICIPATED EVERYWHERE BY MID AFTERNOON. AN UPPER LEVEL LOW WILL
DRIFT OVER THE REGION EARLY IN THE EVENING...WITH NO FLIGHT CATEGORY
CHANGES ANTICIPATED. NORTHERLY SFC WINDS AROUND 10 KNOTS WILL
DIMINISH AFTER DARK.
EXTENDED OUTLOOK...EXPECT VFR SATURDAY THROUGH TUESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM FRIDAY...TWO CHANGES HAVE BEEN MADE TO THE MARINE
FORECAST THIS MORNING. THE FIRST IS TO INCREASE SHOWER AND T-STORM
CHANCES THROUGH THE MORNING HOURS AS THE WILMINGTON AND CHARLESTON
RADARS ARE SHOWING AN IMPRESSIVE AREA OF SHOWERS AND STORMS MOVING
RAPIDLY NORTHEAST ALONG THE COAST. THE SOUTH CAROLINA COASTAL WATERS
WILL BE MOST STRONGLY AFFECTED BY THIS ACTIVITY...WHICH SHOULD TAPER
OFF BY NOON. ALSO...OBSERVED WIND SPEEDS ARE ABOUT 5 KNOTS STRONGER
THAN EXPECTED ACROSS THE WATERS NORTH OF CAPE FEAR...WHERE RECENTLY
GUSTS AT BOTH WRIGHTSVILLE BEACH AND THE FRYING PAN SHOALS BUOY
OFFSHORE HAVE BEEN AROUND 20 KNOTS. NO OTHER SIGNIFICANT CHANGES
HAVE BEEN MADE. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
SURFACE LOW PRESSURE MOVED OVER WILMINGTON AROUND MIDNIGHT AND IS
NOW RACING NORTHEAST ACROSS THE PAMLICO SOUND. NORTHWESTERLY WINDS
BEHIND THIS LOW HAVE PUSHED THE COLD FRONT A CONSIDERABLE DISTANCE
FROM SHORE...AND COOL NORTHWEST TO NORTH WINDS SHOULD CONTINUE
THROUGH THE DAY. STRONG WINDS YESTERDAY STILL HAVE THE SEA STATE
QUITE AGITATED AND IT WILL TAKE MOST OF THE DAY FOR SEAS TO DECAY
BELOW 6 FEET. FOR THIS REASON THE SMALL CRAFT ADVISORY WILL REMAIN
POSTED INTO THE AFTERNOON HOURS FOR THE SC COASTAL WATERS...AND
UNTIL THIS EVENING FOR THE NC WATERS.
AN APPROACHING UPPER LEVEL LOW WILL INDUCE A NEW LOW TO DEVELOP WELL
OFF THE SC COAST LATE THIS AFTERNOON. WHILE THIS NEW LOW WILL HAVE
NO DIRECT IMPACTS LOCALLY...IT WILL HELP TO ENHANCE THE NORTHERLY
WINDS SOMEWHAT WITH WIND SPEEDS PERHAPS ECLIPSING 15 KNOTS
OVERNIGHT...ESPECIALLY AWAY FROM SHORE.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...HIGH PRESSURE WILL BUILD DOWN INTO THE LOCAL
WATERS THROUGH SATURDAY BEFORE SHIFTING CLOSER OVERHEAD SAT NIGHT
AND THEN OFF SHORE THROUGH SUNDAY. WINDS ON THE FRONT END OF THE
SYSTEM WILL BE NORTHEAST INITIALLY UP TO 15 TO 20 KTS BUT WILL VEER
AROUND THROUGH THE WEEKEND AND LIGHTEN TO 10 KTS OR SO AS GRADIENT
RELAXES. BY SATURDAY EVENING WINDS WILL BE VERY LIGHT OUT OF THE
E-NE AND BY SUNDAY A RETURN FLOW WILL SET UP AS WINDS VEER AROUND
TO THE SOUTH REMAINING 10 KTS OR LESS.
SEAS WILL JUST BE COMING DOWN FROM NEAR SCA CONDITIONS SAT
MORNING IN OUTER WATERS AND WILL CONTINUE TO SUBSIDE THROUGH THE
WEEKEND AS THEY VEER AROUND FROM NORTHEAST TO SOUTHEAST AND
LIGHTEN. BY SUNDAY SEAS WILL BE 3 FT OR LESS.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 3 AM FRIDAY...A MORE SUMMER LIKE PATTERN WILL BE SETTING
UP THROUGH NEXT WEEK AS RETURN FLOW PERSISTS AROUND BERMUDA HIGH
PRESSURE. WINDS WILL REMAIN SOUTHERLY AROUND 10 KTS OR SO. WINDS
AND SEAS WILL SPIKE UP NEAR SHORE IN FAIRLY POTENT SEA BREEZE EACH
AFTERNOON...BUT OTHERWISE EXPECT SEAS 3 FT OR LESS.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 3 PM EDT THIS AFTERNOON FOR AMZ256.
SMALL CRAFT ADVISORY UNTIL NOON EDT TODAY FOR AMZ254.
SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR AMZ250-
252.
&&
$$
NEAR TERM...TRA
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...TRA/DL
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
749 PM EDT SAT APR 6 2013
.SYNOPSIS...
LOW PRESSURE OVER MINNESOTA WILL MOVE EAST ACROSS THE CENTRAL
LAKES LATER TONIGHT. A COLD FRONT TRAILING THE LOW WILL MOVE
ACROSS THE LOCAL AREA ON SUNDAY MORNING. THE FRONT WILL STALL OVER
CENTRAL OHIO SUNDAY EVENING AND THEN MOVE LITTLE THROUGH MIDWEEK
AS WAVES OF LOW PRESSURE MOVE ALONG THE FRONT.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
A LAKE BREEZE STRETCHING FROM LAKE TO CRAWFORD (PA) COUNTIES HAS
KEPT TEMPS NOTABLY COOLER THAN INLAND. THE GRADIENT WIND WILL
INCREASE THIS EVENING AND BY 00Z THE WINDS SHOULD BE OUT OF THE
SOUTH/SOUTHEAST FOR ALL AREAS. THIS WILL HAVE THE EFFECT OF
WARMING TEMPERATURES IN ERIE PA OVERNIGHT...RESULTING IN WARMER
OVERNIGHT TEMPERATURES THAN TODAY`S MAX. WARM AIR
ADVECTION...CLOUDS...AND STRONG WINDS WILL PREVENT MUCH COOLING
ELSEWHERE WITH MOST AREAS STAYING IN THE 40S AND LOWER 50S. THE
NEW GUIDANCE IS SHOWING A BROKEN LINE OF SHOWERS DEVELOPING AHEAD
OF THE FRONT AS IT MOVES INTO NW OH AFTER 06Z. IT LOOKS LIKE THIS
LINE WILL REACH ABOUT THE I-77 CORRIDOR BY DAYBREAK. HAVE TRIMMED
AND ADJUSTED POPS TO ACCOUNT FOR THIS SCENARIO. THE NEW GUIDANCE
INCLUDING THE LATEST HRRR ARE NOW SIMILAR SO CONFIDENCE IS HIGH
TODAY. MOST LOCATIONS WILL SEE AN HOUR OR TWO OF LIGHT PRECIP WITH
QPF TOTALS LESS THAN A TENTH OF AN INCH. UNTIL THE PRECIP
ARRIVES...THE THICKENING CLOUDS SHOULD KEEP TEMPS FROM DROPPING
TOO MUCH. WINDS WILL INCREASE MOST IN ANY PRECIPITATION WITH THE
FROPA DURING THE EARLY MORNING HOURS WITH GUSTS AROUND 30 MPH.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY NIGHT/...
IT WILL BE AN ACTIVE PERIOD FOR WEATHER. THE COLD FRONT SHOULD
PUSH SE OF THE AREA ON SUNDAY AND THEN STALL JUST TO THE SOUTH.
THIS FEATURE WILL EVENTUALLY COME BACK NORTH AS A WARM FRONT. THE
BIG QUESTION IS WHEN THAT WILL HAPPEN. MOST OF THE GUIDANCE SHOWS
A WAVE INTERACTING WITH THE FRONT ON MONDAY. THIS WILL FORCE THE
FRONT NORTH TO NEAR LAKE ERIE. EXPECT INSTABILITY TO BUILD AS THIS
HAPPENS. WILL NEED TO STICK WITH HIGH POPS FOR MONDAY WITH A
MENTION OF THUNDER AS WELL. UNSETTLED WEATHER WILL CONTINUE MONDAY
NIGHT INTO TUESDAY NIGHT AS WELL AS THE FRONT LINGERS. THE
INSTABILITY REALLY BUILDS ON TUESDAY WITH SOME SURFACE BASED CAPE
AND LI`S DIPPING BELOW ZERO. FOR NOW WILL LIMIT THUNDER CHANCES TO
THE DAYLIGHT HOURS BUT THAT MAY NEED TO BE EXPANDED DEPENDING ON
WHAT THE FRONT DOES. THE PERIOD SHOULD BE WARM WITH HIGHS IN THE
60S EXPECT NEAR THE IMMEDIATE LAKE SHORE. OVERALL...THE CHANGES TO
THE FORECAST ARE PRETTY MINIMAL FROM THE PREVIOUS PACKAGE.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
BEGINNING AT 12Z WEDNESDAY THE GFS AND ECMWF MODELS BEGIN TO DIVERGE
WITH THE GFS SHOWING A CLOSED SURFACE LOW OVER KANSAS, WHILE THE
ECMWF RESOLVES AN INVERTED THERMAL TROUGH OVER THE EASTERN CENTRAL
PLAINS. THE GFS TRACKS THE LOW INTO WESTERN INDIANA BY THURSDAY
MORNING SPREADING RAIN SHOWERS OVER THE AREA. RAIN ALSO BEGINS TO
FALL WITH THE ECMWF SOLUTION AROUND THIS TIME ALONG A STATIONARY
BOUNDARY. IT APPEARS THE ECMWF IS STRUGGLING TO RESOLVE THE SYSTEM,
PERHAPS DUE TO A BROAD MID-LEVEL RIDGE DEVELOPING OVER THE NE
QUADRANT. NONETHELESS A BAROCLINIC ZONE WILL DEVELOP AS THE SYSTEM
MATURES THROUGH THE WEEKEND. THE TEMPERATURE FORECAST WILL BE A
CHALLENGE AND WILL DEPEND ON THE TRACK AND DEVELOPMENT OF THE LOW.
THE ECMWF SOLUTION WILL YIELD LOWER DAYTIME TEMPS AS A BOUNDARY SETS
UP ACROSS CENTRAL OHIO. THE GFS HAS A MUCH BETTER DEFINED WARM
SECTOR ADVECTING WARMER AIR INTO THE REGION. FOR NOW GOING WITH A
BLEND OF THE 2 SOLUTIONS. WILL CONTINUE TO ADJUST FORECAST AS MODELS
HOPEFULLY CONVERGE ON A SIMILAR SOLUTION. AT THE LATEST BOTH MODELS
SHOW THE SYSTEM PASSING THROUGH THE AREA BY SATURDAY AFTERNOON WITH
THE ECMWF HINTING AT A BRIEF SHOT OF COOLER AIR ON THE BACKSIDE OF
THE SYSTEM. A FLURRY MAY BE POSSIBLE ACROSS THE HIGHER TERRAIN THAT
EVENING.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
VFR WITH MID AND HIGH CLOUDS TONIGHT AND AN INCREASING SOUTH WIND
AHEAD OF A COLD FRONT. THE LOW LEVEL JET WILL INCREASE AND WILL
INCLUDE LOW LEVEL WIND SHEAR TONIGHT. THERE COULD BE A FEW SHOWERS
WITH THE FRONTAL PASSAGE ABOUT 10Z KTOL TO 15Z KERI BUT CONDITIONS
WILL LIKELY REMAIN VFR WITH A SLIGHT WIND SHIFT. PATCHES OF
STRATOCUMULUS (BKN050) SHOULD CLEAR OUT ON SUNDAY AS DRIER AIR
SPREADS IN FROM THE WEST. WSW WINDS WILL REMAIN RATHER GUSTY UNTIL
SUNDAY EVENING.
.OUTLOOK...NON VFR DEVELOPING MONDAY AND LASTING INTO WED MORNING.
&&
.MARINE...
A COLD FRONT WILL SWEEP ACROSS THE LAKE TOWARD MORNING WITH FAIRLY
STRONG SOUTHERLY FLOW AHEAD OF THE FEATURE. EXPECTED STRONG
DOWN SLOPE WINDS OVER NORTHWEST PA TO DEVELOP OVER THE LAKE SHORE
FROM THE CITY OF ERIE TO RIPLEY NEW YORK OF ABOUT 30 KNOTS AFTER
MIDNIGHT. WINDS WILL INCREASE TO 15 TO 25 KNOTS ELSEWHERE OVER THE
LAKE. WITH COLD WATER IN PLACE A SOMEWHAT STABLE BOUNDARY LAYER WILL
INHIBIT SOME MIXING OF HIGHER WINDS OFF THE SURFACE. WILL ISSUE A
SMALL CRAFT ADVISORY FOR THIS EVENING UNTIL THE MIDDLE OF SUNDAY
AFTERNOON.
THE GRADIENT WILL RELAX SUNDAY AFTERNOON AND EVENING AS WEAK HIGH
PRESSURE BRIEFLY BUILDS OVER THE LAKE. THE FRONTAL BOUNDARY WILL
LIFT NORTH BACK ACROSS THE LAKE MONDAY NIGHT AND REMAIN NEAR THE
LAKE THROUGH MUCH OF THE WEEK WITH WIND SHIFTS AT TIMES AS IT
MEANDERS NEARBY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 4 PM EDT
SUNDAY FOR LEZ142>149.
&&
$$
SYNOPSIS...KUBINA
NEAR TERM...JAMISON/KUBINA
SHORT TERM...KUBINA
LONG TERM...MAYERS
AVIATION...KOSARIK
MARINE...LAPLANTE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
311 PM CDT FRI APR 5 2013
.SHORT TERM...(TONIGHT THROUGH SATURDAY NIGHT)
ISSUED AT 311 PM CDT FRI APR 5 2013
WATER VAPOR IMAGERY THIS AFTERNOON SHOWING A MID-LEVEL SHORTWAVE
TROUGH MOVING THROUGH THE INTERMOUNTAIN WEST. AT THE SURFACE...
CYCLOGENESIS WAS TAKING PLACE EAST OF THE WY ROCKIES WITH A WARM
FRONT EXTENDING THROUGH NEBRASKA. LIFT AHEAD OF THE LOW AND OVER THE
WARM FRONT WAS PRODUCING INCREASING MID-LEVEL CLOUD WITH RADAR
MOSAIC/SURFACE OBSERVATIONS INDICATING SPORADIC -SN REACHING THE
GROUND FROM WEST CENTRAL-SOUTH CENTRAL MN. OTHERWISE...HIGH/MID
CLOUDS WERE INCREASING/THICKENING FROM WEST TO EAST ACROSS THE
FORECAST AREA WITH TEMPERATURES RANGING FROM THE UPPER 30S ACROSS
NORTH CENTRAL WI TO 50 ACROSS PORTIONS OF NORTHEAST IA/FAR SOUTHWEST
WI.
FOR TONIGHT...SURFACE LOW WILL CONTINUE TO DEVELOP AND MOVE OUT OF
THE PLAINS INTO SOUTHERN MN BY 12Z WITH INCREASING 850-700MB
MOISTURE TRANSPORT/ISENTROPIC LIFT AHEAD OF THE LOW FOCUSING INTO
AREAS NORTHEAST OF I-94. AS A RESULT...CONFIDENT ENOUGH TO CARRY
LIKELY TO CATEGORICAL POPS ACROSS THAT AREA...TAPERING OFF TO
CHANCES SOUTHWEST OF I-94. AS FAR AS PRECIPITATION TYPES...RAP
SOUNDINGS NORTHEAST OF I-94 SHOW EVAPORATIVE COOLING AS THE COLUMN
SATURATES...WITH BOUNDARY LAYER STILL WARM ENOUGH TO SUPPORT RAIN.
THE NAM ON THE OTHERHAND COOLS THE ENTIRE COLUMN BELOW 0C FOR ALL
SNOW WHICH SEEMS A BIT AGGRESSIVE. BOTTOM LINE...LOOKS LIKE A
RAIN/SNOW MIX MOVING IN MAINLY ALONG AND NORTH OF I-94 THIS EVENING.
LOOKS LIKE MAIN SNOW AREA WILL BE NORTH OF THE AREA...BUT TAYLOR
COUNTY COULD BE COLD ENOUGH TO SEE ACCUMULATIONS OF 1/2 TO PERHAPS
AS MUCH AS 2 INCHES ACROSS FAR NORTHERN PORTION OF THE COUNTY. AS
WARMER AIR ALOFT MOVES INTO THE AREA AFTER MIDNIGHT...LOOK FOR THE
SNOW TO BECOME MORE OF A RAIN/SLEET MIX...POSSIBLY ALL RAIN TOWARD
MORNING.
MODELS CONTINUE TO SHOW THE LOW MOVING EAST THROUGH CENTRAL WI ON
SATURDAY WITH AREAS ALONG AND SOUTH OF I-90 IN THE WARM SECTOR. RAIN
EXPECTED TO CONTINUE ALONG AND NORTH OF THE LOW. MEANWHILE...THE NAM
DEVELOPS SOME 0-3KM MUCAPE LATE MORNING/AFTERNOON IN THE WARM SECTOR
OF AROUND 400J/KG. THIS WILL BE AHEAD OF FAIRLY STRONG 925-700MB
FRONTOGENESIS ASSOCIATED WITH THE COLD FRONT OF THE LOW. BUFKIT
SHOWING THAT THIS IS LONG/SKINNY CAPE WHICH WILL LIKELY SUSTAIN A
FEW THUNDERSTORMS. BASED ON THIS SIGNAL...WILL CONTINUE THE THREAT
FOR A FEW STORMS IN THE FORECAST MAINLY ALONG/SOUTH OF I-90.
OTHERWISE...LOOK FOR TEMPERATURES TO CLIMB INTO THE 55-60 DEGREE
RANGE SOUTH OF THE WARM FRONT...AND IN THE 40S TO NEAR 50 ALONG AND
NORTH OF I-94. RAIN AND WARMTH FOR SNOWMELT MAY LEAD TO SOME HYDRO
ISSUES. DETAILS OF THIS IS COVERED IN THE HYDROLOGY SECTION BELOW.
THE LOW PULLS EAST INTO THE GREAT LAKES REGION SATURDAY NIGHT WITH
LINGERING RAIN CHANCES CONFINED TO THE EVENING HOURS ALONG AND EAST
OF THE MISSISSIPPI RIVER.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 311 PM CDT FRI APR 5 2013
SUNDAY EXPECTED TO BE DRY AS A RIDGE OF HIGH PRESSURE DRIFTS ACROSS
THE REGION. LOOK FOR IN THE MIDDLE 40S TO MIDDLE 50S.
FOR SUNDAY NIGHT INTO MONDAY...A DEEPENING UPPER LEVEL TROUGH OF LOW
PRESSURE OVER THE WESTERN STATES WILL PRODUCE INCREASING SOUTHWEST
FLOW ALOFT INTO THE UPPER MISSISSIPPI RIVER VALLEY REGION.
CYCLOGENESIS AND BROAD MOISTURE TRANSPORT ACROSS THE PLAINS INTO OUR
AREA WILL PRODUCE A CHANCE OF A RAIN OR RAIN/SNOW MIX SUNDAY NIGHT
AND ALL RAIN ON MONDAY. PLAN ON LOWS SUNDAY NIGHT IN THE 30S TO NEAR
40 WITH HIGHS ON MONDAY IN THE UPPER 40S TO THE MIDDLE 50S.
MEDIUM RANGE MODELS SHOWING A RATHER ACTIVE WEATHER PATTERN FOR THE
REST OF THE WORK WEEK. HOWEVER...THEY OFFER DIFFERING SOLUTIONS WITH
REGARD TO THE EVOLUTION OF THE WESTERN TROUGH AND SURFACE
CYCLOGENESIS AND IMPACT ON THE UPPER MISSISSIPPI RIVER VALLEY
REGION. THE GFS AND GEM SHOWING SOME SIMILARITY IN EJECTING THE
TROUGH/SURFACE LOW TOWARD THE AREA MONDAY NIGHT THROUGH TUESDAY
NIGHT WITH MORE PHASING WITH THE NORTHERN STREAM FLOW. THIS KEEPS US
IN AN OVERALL WARMER/RAIN SCENARIO. THE ECMWF ON THE OTHER HAND
WANTS TO KEEP THE FLOW SPLIT THROUGH TUESDAY WHICH KEEPS THE LOW
OVER THE PLAINS THUS KEEPING AREAS MAINLY NORTH OF I-90 DRY WITH
UPSTREAM RIDGING. THE ECMWF THEN TAKES THE MAIN SURFACE LOW TRACK
FARTHER SOUTH INTO THE OHIO RIVER VALLEY REGION WITH AN INVERTED
TROUGH OVER US. THIS MAY LEAD TO A COLDER RAIN OR RAIN SNOW MIX. WILL
GO WITH A MODEL CONSENSUS FOR NOW AND HOPE FOR BETTER RESOLUTION
WITH LATER RUNS. CONSENSUS YIELDS A CHANCE OF RAIN FROM MONDAY NIGHT
STRAIGHT THROUGH FRIDAY. TEMPERATURES THROUGH THE PERIOD LOOK TO BE
COLDER THAN NORMAL WITH GENERAL TROUGHINESS AND PRECIPITATION.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY)
ISSUED 1225 PM CDT FRI APR 5 2013
HIGH PRESSURE WAS RE-TREATING EASTWARD AS AN AREA OF LOW PRESSURE
WAS DEVELOPING OVER THE PLAINS. SWATH OF WARM
ADVECTION/FRONTOGENESIS PUSHING INTO SOUTH CENTRAL MINNESOTA.
05.15Z HRRR TAKES THIS BAND OF FRONTOGENESIS ACROSS THE AREA LATE
THIS AFTERNOON THROUGH EARLY EVENING. QUESTION WILL BE HOW MUCH
LOW LEVEL SATURATION THERE IS FOR LOWER CLOUDS AND SHOWERS. MODELS
SUGGEST VFR CEILINGS AND HAVE TAILORED THE TAFS WITH VFR CEILINGS
WITH SOME SHOWERS. FOCUS THEN LOOKS TO BE NORTH OF THE TAF SITES
THROUGH LATE EVENING AND OVERNIGHT....WITH THE NEXT BATCH OF
PRECIPITATION AFFECTING THE TAF SITES AFTER 12Z SATURDAY AS THE
CEILINGS LOWER INTO THE MVFR CATEGORY.
&&
.HYDROLOGY...
ISSUED AT 311 PM CDT FRI APR 5 2013
RIVER STATUS...
ICE JAM ISSUES NOW BEING REPORTED ON THE BLACK ON THE NORTH SIDE OF
NEILLSVILLE WITH THAWING. HYDROGRAPHS ACROSS THE REST OF AREA SHOW
TRIBUTARY RIVERS AND STREAMS INTO THE MISSISSIPPI RUNNING WITHIN
BANK BUT HIGHER THAN NORMAL GIVEN THE SNOW MELT. MOST OF THE HIGHER
RIVER FLOWS ARE CONFINED TO RIVERS NORTH OF I-90 WHERE SNOW PACK
STILL EXISTS. BESIDES THE BLACK RIVER...THE TREMPEALEAU IS ALSO A
CONCERN AT THE MOMENT.
SNOW PACK...
LATEST NOHRSC DATA SHOWED SNOW WATER EQUIVALENTS STILL IN THE 1-3
INCH RANGE OVER WINONA...BUFFALO...TREMPEALEAU AND JACKSON
COUNTIES...WHILE 2-4 INCH AMOUNTS WERE PRESENT IN CLARK AND TAYLOR
COUNTIES.
RAINFALL...
THE SYSTEM COMING IN FOR TONIGHT AND SATURDAY IS EXPECTED TO PRODUCE
1/4 OF AN INCH OR LESS SOUTHWEST OF I-94 AND AROUND 1/2 INCH
RAINFALL/LIQUID EQUIVALENT FROM ANY SNOW NORTH OF HIGHWAY 10 IN
WISCONSIN. ADDITIONAL RAINFALL IS POSSIBLE SUNDAY NIGHT WITH THE
POTENTIAL FOR MORE MODERATE RAINFALL MONDAY THROUGH WEDNESDAY OF NEXT WEEK.
TEMPERATURES...
TEMPERATURES IN THE MIDDLE 30S TO MIDDLE/UPPER 40S TODAY CONTINUES
TO PRODUCE SNOWMELT. TEMPERATURES MAY NOT FALL BELOW FREEZING
TONIGHT ALONG WITH WARMER CONDITIONS ANTICIPATED ON SATURDAY. THIS
WILL CAUSE ADDITIONAL SNOW MELT. MOST OF THE NEXT 7 DAYS LOOK TO
HAVE DAYTIME TEMPERATURES AT LEAST 40 FOR CONTINUED FAVORABLE SNOW MELT
CONDITIONS.
FROST DEPTH...
FROST DEPTHS ACROSS THE AREA REMAIN DEEP...AVERAGING AROUND 1 FOOT
TO 1 1/2 FEET SOUTH OF I-90...AND UP TO 3 FEET ACROSS PORTIONS OF
NORTH CENTRAL WISCONSIN. THIS WILL LIKELY CAUSE ADDITIONAL RUNOFF OF
SNOW MELT AND FALLEN PRECIPITATION INTO STREAMS AND RIVERS.
SUMMARY...
DUE TO LESS RAINFALL EXPECTED FOR TONIGHT THROUGH SATURDAY...MAIN
FLOODING CONCERN WOULD COME MOSTLY FROM SNOW MELT THE NEXT FEW DAYS.
RIVERS AND STREAMS FROM WINONA AND WABASHA COUNTIES INTO BUFFALO
TREMPEALEAU...JACKSON...CLARK AND TAYLOR CONTINUE BE FOCUS OF
CONCERN. WILL KEEP THE ESF GOING BASED ON THE LISTED FACTORS ABOVE.
POTENTIAL IS THERE FOR A FLOOD WATCH...BUT WILL CONTINUE ESF AND
CONTINUE ASSESSING THE SITUATION AT HAND WITH SNOWMELT AND FALLEN
PRECIPITATION. WILL ALSO CONTINUE TO KEEP A VIGILANT EYE ON ON THE
SITUATION FOR MODERATE RAINFALL POTENTIAL MONDAY THROUGH WEDNESDAY
OF NEXT WEEK.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM...DAS
AVIATION...RABERDING
HYDROLOGY...DAS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1225 PM CDT FRI APR 5 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT FRI APR 5 2013
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED A SHORTWAVE TROUGH OVER THE PACIFIC NORTHWEST...RIDGING FROM
WEST TEXAS INTO THE NORTHERN PLAINS...AND NORTHERN STREAM TROUGHING
IN THE GREAT LAKES. IN THE WAKE OF THIS TROUGHING...HIGH PRESSURE
HAS BEEN BUILDING IN AT THE SURFACE ACROSS MINNESOTA. 00Z MPX
SOUNDING SHOWED PLENTY OF SUBSIDENCE AND DRY AIR ACCOMPANYING THE
SURFACE HIGH...WITH PRECIPITABLE WATER VALUE AT 0.28 INCHES. AS A
RESULT...SKIES ARE CLEAR ACROSS THE FORECAST AREA. JUST OFF TO THE
WEST...MID AND HIGH LEVEL CLOUDS WERE INCREASING ACROSS THE NORTHERN
PLAINS INTO WESTERN MINNESOTA...WELL DOWNSTREAM OF THE PACIFIC
NORTHWEST SHORTWAVE. THESE CLOUDS ARE ASSOCIATED WITH A WARM
ADVECTION REGIME ON THE TOP OF THE RIDGE...AS WELL AS HELP FROM A
120KT JET STREAK FROM SOUTHERN MANITOBA INTO EASTERN MINNESOTA.
PROFILER AND VAD WIND DATA AT 850MB SHOWED A 30-50 KT SOUTH JET FROM
EASTERN COLORADO INTO THE WESTERN DAKOTAS. ALSO PRESENT AT 850MB WAS
A TIGHT TEMPERATURE GRADIENT...REFLECTED BY 00Z SOUNDINGS OF -6C AT
BISMARCK COMPARED TO +5C AT RAPID CITY AND +10C AT NORTH PLATTE.
DESPITE THE DECENT WARM ADVECTION PATTERN IN PLACE...SURFACE
DEWPOINTS HAVE BEEN SLOW TO RISE. DEWPOINTS WERE ONLY IN THE LOW TO
MID 30S OVER THE CENTRAL PLAINS...WHICH WAS AT LEAST HIGHER THAN IN
THE DAKOTAS WHICH WERE IN THE 20S.
THE FOCUS FOR THE SHORT TERM IS ON TWO PARTS...
1. WARM ADVECTION WELL DOWNSTREAM OF THE PACIFIC NORTHWEST SHORTWAVE
TROUGH
2. EVENTUAL APPROACH OF THE PACIFIC NORTHWEST SHORTWAVE TROUGH
SUBSIDENCE AND DRY AIR ASSOCIATED WITH THE SURFACE HIGH WILL
DOMINATE THIS MORNING. AS WE HEAD INTO THE AFTERNOON...THE UPPER
RIDGE AXIS OVER THE NORTHERN PLAINS IS PROGGED TO SLIDE INTO THE
FORECAST AREA. THUS...AN INCREASE OF THE MID AND HIGH LEVEL CLOUDS
IS LIKELY AS SEEN BACK IN THE DAKOTAS. THE QUESTIONS ARE WILL
PRECIPITATION DEVELOP...AND IF SO WHERE AND WHEN...AS THE WARM
ADVECTION INCREASES THROUGH THE AFTERNOON AND EVENING. THE 05.00Z
GFS/REGIONAL CANADIAN ARE BY FAR THE MOST AGGRESSIVE...DEVELOPING
RAIN ALONG/WEST OF THE MISSISSIPPI RIVER BETWEEN 18-00Z TODAY. THE
05.00Z NAM/05.00Z ECMWF/04.21Z SREF ALSO DEVELOP THE RAIN...BUT KEEP
IT CONFINED NORTHWEST OF THE FORECAST AREA PRIOR TO 00Z. THE LACK OF
MOISTURE CURRENTLY AVAILABLE WOULD SUPPORT THE DRIER SCENARIO...
HOWEVER...850MB MOISTURE TRANSPORT DOES INTENSIFY THROUGH THE DAY
AND BY 00Z IS POINTING ON THE WEST SIDE OF THE FORECAST AREA.
THUS...FELT AT LEAST KEEPING SOME 20-50 PERCENT CHANCES LATE IN THE
DAY ARE APPROPRIATE OVER THE WESTERN PORTIONS OF THE FORECAST
AREA...HIGHEST FROM WABASHA INTO DODGE COUNTIES.
FOR TONIGHT...MODELS PROG THE PACIFIC NORTHWEST SHORTWAVE TROUGH TO
ENTER WESTERN SOUTH DAKOTA...CAUSING A SURFACE LOW TO FORM AND
DEEPEN OVER SOUTHERN SOUTH DAKOTA. PERSISTENT AND INTENSIFYING WARM
ADVECTION AHEAD OF THIS SHORTWAVE TROUGH AND SURFACE LOW LOOKS TO
EXPAND THE AREA OF PRECIPITATION OVER MOST LOCATIONS EAST OF THE
MISSISSIPPI RIVER IN THE EVENING...WHICH THEN LIFTS NORTHEAST AFTER
MIDNIGHT. EVAPORATIVE COOLING MAY CAUSE THE PRECIPITATION TO SWITCH
FROM RAIN TO SNOW IN THE EVENING NORTHEAST OF I-94...BUT EVENTUALLY
WARMER AIR ADVECTS IN THERE AFTER MIDNIGHT ALOFT AND THEN SURFACE
TO CAUSE A CHANGE-OVER TO SLEET AND RAIN. IF TEMPERATURES CAN HOLD
BELOW FREEZING...A VERY BRIEF PERIOD OF FREEZING RAIN WOULD OCCUR.
MODEL CONSENSUS CONTINUES TO FAVOR ALONG/NORTHEAST OF I-94 TO HAVE
THE BULK OF THE PRECIPITATION...THUS PRECIPITATION CHANCES NEAR 100
SEEMS REASONABLE. REGARDING SNOWFALL ACCUMULATION...GIVEN THE
GENERAL WARM SENSE TO THIS WARM ADVECTION EVENT...NOTED BY 850MB
TEMPS THAT ARE ONLY -2 TO -4C WHEN IT IS SNOWING...SNOW TO WATER
RATIOS SHOULD ONLY MAX OUT AROUND 10 TO 1. WITH UPWARDS OF 0.1-0.3
INCHES OF QPF PROGGED...SNOW TOTALS COULD BE AS MUCH AS 3
INCHES...THOUGH THE MAJORITY SHOULD END UP IN THE 1 TO 2 INCH
RANGE...NOT ENOUGH FOR AN ADVISORY AT THIS POINT. COULD USE THE MIX
PRECIPITATION AS A NEED FOR THE ADVISORY...BUT CONFIDENCE ON THE
AMOUNT OF MIXED PRECIPITATION IS TOO LOW TO WARRANT ONE.
TEMPERATURES TODAY WILL END UP COOLER COMPARED TO YESTERDAY DUE TO
INCREASING CLOUDS AS WELL AS 850MB TEMPS BETWEEN -2 AND -6C AT 18Z.
FOR TONIGHT...INCREASING SOUTHERLY WINDS PLUS CLOUDS SHOULD HELP
KEEP TEMPERATURES UP AT OR ABOVE FREEZING. IN FACT...EXPECTING
TEMPERATURES TO CLIMB LATE IN THE NIGHT AS THE SURFACE WARM FRONT
LIFTS NORTH TOWARDS I-94.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 341 AM CDT FRI APR 5 2013
HIGHLIGHTS:
1. CURRENT PACIFIC NORTHWEST SHORTWAVE TROUGH PROGGED TO MOVE
THROUGH THE AREA ON SATURDAY
2. POTENTIAL FOR AN ACTIVE BUT HARD TO TIME PRECIPITATION PATTERN
SUNDAY NIGHT AND BEYOND.
MODELS ARE IN REALLY GOOD AGREEMENT TRACKING THE SHORTWAVE TROUGH
THAT WAS OVER SOUTH DAKOTA LATE TONIGHT INTO AND POSSIBLY THROUGH
THE FORECAST AREA ON SATURDAY. STRONG DYNAMIC FORCING WITH THIS
SHORTWAVE...NOTED SIMPLY BY 60-90 METER HEIGHT FALLS IN 12 HOURS AT
500MB...ALONG WITH THAT SURGE OF 850MB MOISTURE TRANSPORT AHEAD OF
THE SHORTWAVE PROVIDING MOISTURE SHOULD HELP PRODUCE RAIN ACROSS
MOST OF THE FORECAST AREA. THE ONLY MODEL NOT SHOWING THIS IS THE
05.00Z NAM...AT LEAST SOUTH OF I-90...WHICH SEEMS ODD GIVEN THE
FORCING. THE 05.00Z REGIONAL CANADIAN IS ACTUALLY QUITE ROBUST SOUTH
OF I-90 WITH QPF AMOUNTS OF 0.1-0.25 INCHES WITH A FEW ISOLATED 0.5
INCH AMOUNTS FROM VERNON INTO ADAMS COUNTIES. IT APPEARS THE HEAVIER
QPF IS A RESULT OF CONVECTIVE ELEMENTS FORMING AHEAD OF THE
SHORTWAVES ASSOCIATED COLD FRONT AT THE SURFACE. INSTABILITY IS
FAIRLY MEAGER DUE TO CAPPING AROUND 750MB AND LIMITED MOISTURE.
HOWEVER...THERE IS A ZONE OF NEGATIVE EPV DUE TO UPRIGHT INSTABILITY
IN CROSS-SECTIONS AROUND 700MB...THUS A FEW THUNDERSTORMS CANNOT BE
RULED OUT. PRECIPITATION SHOULD SHIFT OFF TO THE EAST PRETTY QUICK
LATE IN THE AFTERNOON INTO THE EARLY EVENING FOR MOST OF THE
AREA...AS STRONG SUBSIDENCE COMES IN BEHIND THE SHORTWAVE TROUGH.
ONLY PLACE THIS MAY NOT OCCUR AS FAST IS NORTH AND EAST OF
I-94...DUE TO THE SUGGESTION OF A SHORTWAVE COMING IN BEHIND THE
SHORTWAVE TROUGH AND A MID-LEVEL FRONTOGENESIS ZONE DROPPING
SOUTHEAST. TEMPERATURES MAY COOL ENOUGH TO ALLOW FOR SOME SNOW OUT
OF THIS PRECIPITATION BEFORE IT ENDS BY MIDNIGHT. VERY LITTLE
ACCUMULATION ANTICIPATED...THOUGH.
A MAJOR PATTERN CHANGE IS FORECAST TO TAKE PLACE SUNDAY AS A POTENT
SHORTWAVE TROUGH IMPACTS AND DIGS INTO THE PACIFIC NORTHWEST.
HEADING INTO THE EARLY PORTION OF THE WORK WEEK...MODELS ARE IN GOOD
AGREEMENT DIGGING THIS TROUGH SOUTH INTO THE FOUR CORNERS REGION...
SETTING UP A SOUTHWEST FLOW PATTERN INTO THE FORECAST AREA. THIS
MEANS HARD TO TIME SHORTWAVES AND THUS PLENTY OF UNCERTAINTY. TAKE
FOR EXAMPLE SUNDAY NIGHT WHERE THE 05.00Z ECMWF/NAM BRING A
SHORTWAVE THROUGH THE AREA WITH WIDESPREAD QPF. THE 05.00Z CANADIAN
IS EVEN MORE POTENT WITH THIS SHORTWAVE AND A BIT FARTHER SOUTHEAST.
ON THE OTHER HAND...THE 05.00Z GFS DOES NOT SHOW THE SHORTWAVE AT
ALL...THUS RESULTING IN A DRY FORECAST. MAJORITY HERE SUGGESTS AT
LEAST 30-50 PERCENT PRECIPITATION CHANCES ARE NEEDED. MOST OF THE
PRECIPITATION SHOULD FALL AS RAIN...BUT COULD MIX WITH SNOW
ALONG/NORTHEAST OF I-94.
THE MOST INTERESTING TIME PERIOD OF NEXT WEEK IS TUESDAY INTO
WEDNESDAY...AS THE UPPER TROUGH IN THE SOUTHWEST U.S. EJECTS OUT.
THERE REMAINS A WHOLE LOT OF UNCERTAINTY ON THE TIMING AND DETAILS
OF THIS EJECTION. HOWEVER...EVERY MODEL AVAILABLE AT THIS POINT HAS
SOME SYSTEM AFFECTING THE AREA. WE COULD END UP SEEING CONVECTION IN
THE GFS SCENARIO...POTENTIAL FOR MODERATE TO HEAVY RAINFALL IN ANY
MODEL...AND EVEN SOME SNOW ON THE BACK SIDE OF THE SYSTEM ONCE THE
UPPER TROUGH MOVES OVERHEAD. WE WILL HAVE TO KEEP A WATCH ON THIS
PERIOD. GIVEN THE CONSENSUS AGREEMENT FOR PRECIPITATION TUESDAY INTO
TUESDAY NIGHT...RAISED PRECIPITATION CHANCES DURING THIS PERIOD. MAY
NEED TO RAISE CHANCES FOR WEDNESDAY AS WELL.
&&
.AVIATION...THROUGH 18Z SATURDAY
1225 PM CDT FRI APR 5 2013
HIGH PRESSURE WAS RE-TREATING EASTWARD AS AN AREA OF LOW PRESSURE
WAS DEVELOPING OVER THE PLAINS. SWATH OF WARM
ADVECTION/FRONTOGENESIS PUSHING INTO SOUTH CENTRAL MINNESOTA.
05.15Z HRRR TAKES THIS BAND OF FRONTOGENESIS ACROSS THE AREA LATE
THIS AFTERNOON THROUGH EARLY EVENING. QUESTION WILL BE HOW MUCH
LOW LEVEL SATURATION THERE IS FOR LOWER CLOUDS AND SHOWERS. MODELS
SUGGEST VFR CEILINGS AND HAVE TAILORED THE TAFS WITH VFR CEILINGS
WITH SOME SHOWERS. FOCUS THEN LOOKS TO BE NORTH OF THE TAF SITES
THROUGH LATE EVENING AND OVERNIGHT....WITH THE NEXT BATCH OF
PRECIPITATION AFFECTING THE TAF SITES AFTER 12Z SATURDAY AS THE
CEILINGS LOWER INTO THE MVFR CATEGORY.
&&
.HYDROLOGY...
ISSUED AT 341 AM CDT FRI APR 5 2013
RIVER STATUS...
HYDROGRAPHS ACROSS THE AREA SHOW TRIBUTARY RIVERS AND STREAMS INTO
THE MISSISSIPPI RUNNING WITHIN BANK FLOWS WITH A FEW HIGHER THAN
NORMAL GIVEN THE SNOW MELT. MOST OF THE HIGH RIVER FLOWS ARE
CONFINED TO RIVERS NORTH OF I-90 WHERE SNOW PACK STILL EXISTS. THE
WHITEWATER...TREMPEALEAU AND BLACK RIVERS ARE OF CONCERN AT THE
MOMENT.
SNOW PACK...
LATEST NOHRSC DATA SHOWED SNOW WATER EQUIVALENTS STILL IN THE 1-2
INCH RANGE OVER WINONA...BUFFALO...TREMPEALEAU AND JACKSON
COUNTIES...WHILE 2-3 INCH AMOUNTS WERE PRESENT IN CLARK AND TAYLOR
COUNTIES.
RAINFALL...
THE SYSTEM COMING IN FOR TONIGHT AND SATURDAY NOW LOOKS TO NOT
PRODUCE AS MUCH RAINFALL AS PREVIOUSLY EXPECTED...MOSTLY LESS THAN
1/3 OF AN INCH SOUTHWEST OF I-94 TO 1/3 TO 1/2 INCH NORTH OF I-94.
NOTE THAT SOME SNOW IS FORECAST TONIGHT NORTH AND EAST OF
I-94...WHICH COULD TOTAL UP TO 0.3 OF LIQUID EQUIVALENT. ADDITIONAL
RAINFALL IS POSSIBLE SUNDAY NIGHT WITH POTENTIAL FOR MODERATE TO
HEAVY RAINFALL TUESDAY INTO WEDNESDAY OF NEXT WEEK.
TEMPERATURES...
A COOLER DAY BUT STILL PLENTY WARM ENOUGH FOR SNOW MELT IS EXPECTED
TODAY AS HIGHS CLIMB INTO THE 40S. PROBLEM TONIGHT IS THAT
TEMPERATURES MAY NOT FALL BELOW FREEZING AND WITH WARMER CONDITIONS
ANTICIPATED ON SATURDAY...WE COULD REALLY SEE SOME SNOW MELT. MOST
OF THE NEXT 7 DAYS LOOK TO HAVE DAYTIME TEMPERATURES AT LEAST
40...THUS FAVORABLE CONDITIONS ARE IN PLACE FOR SNOW MELT EVERY DAY.
FROST DEPTH...
FROST REMAINS FAIRLY DEEP IN THE GROUND STILL. AS OF 7 AM APRIL
4TH...CUBA CITY WI WAS AT 16 INCHES...WHITEHALL WAS AT 19
INCHES...AND BLOOMER IN CHIPPEWA COUNTY WAS AT 38 INCHES.
SUMMARY...
NOW THAT LESS RAINFALL IS FORECAST THAN EXPECTED FOR TONIGHT AND
SATURDAY...ANY FLOODING CONCERN WOULD COME MOSTLY FROM SNOW MELT THE
NEXT FEW DAYS. CERTAINLY ANY RIVERS AND STREAMS FROM WINONA AND
WABASHA COUNTIES INTO BUFFALO TREMPEALEAU...JACKSON...CLARK AND
TAYLOR WOULD BE OF CONCERN. HAVE DECIDED TO KEEP THE ESF GOING
AND EXPANDED IT INTO WINONA COUNTY GIVEN THE ISSUES BEING
EXPERIENCED ON THE WHITEWATER RIVER. CONSIDERED ISSUING A FLOOD
WATCH FOR JUST RIVERS...BUT GIVEN THAT LESS RAINFALL IS EXPECTED
AND WE ALREADY HAVE EXPERIENCED RIVERS IN AND OUT OF MINOR FLOOD
STAGE THE LAST FEW DAYS...FEEL THE ESF IS STILL VALID. MAY STILL
NEED A FLOOD WATCH...THOUGH...AS CERTAINTY INCREASES ABOUT THE
AMOUNT OF SNOW MELT THIS WEEKEND. EITHER WAY...DEFINITELY NEED TO
KEEP AN EYE ON TUESDAY INTO WEDNESDAY OF NEXT WEEK.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...RABERDING
HYDROLOGY...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
657 AM CDT FRI APR 5 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT FRI APR 5 2013
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED A SHORTWAVE TROUGH OVER THE PACIFIC NORTHWEST...RIDGING FROM
WEST TEXAS INTO THE NORTHERN PLAINS...AND NORTHERN STREAM TROUGHING
IN THE GREAT LAKES. IN THE WAKE OF THIS TROUGHING...HIGH PRESSURE
HAS BEEN BUILDING IN AT THE SURFACE ACROSS MINNESOTA. 00Z MPX
SOUNDING SHOWED PLENTY OF SUBSIDENCE AND DRY AIR ACCOMPANYING THE
SURFACE HIGH...WITH PRECIPITABLE WATER VALUE AT 0.28 INCHES. AS A
RESULT...SKIES ARE CLEAR ACROSS THE FORECAST AREA. JUST OFF TO THE
WEST...MID AND HIGH LEVEL CLOUDS WERE INCREASING ACROSS THE NORTHERN
PLAINS INTO WESTERN MINNESOTA...WELL DOWNSTREAM OF THE PACIFIC
NORTHWEST SHORTWAVE. THESE CLOUDS ARE ASSOCIATED WITH A WARM
ADVECTION REGIME ON THE TOP OF THE RIDGE...AS WELL AS HELP FROM A
120KT JET STREAK FROM SOUTHERN MANITOBA INTO EASTERN MINNESOTA.
PROFILER AND VAD WIND DATA AT 850MB SHOWED A 30-50 KT SOUTH JET FROM
EASTERN COLORADO INTO THE WESTERN DAKOTAS. ALSO PRESENT AT 850MB WAS
A TIGHT TEMPERATURE GRADIENT...REFLECTED BY 00Z SOUNDINGS OF -6C AT
BISMARCK COMPARED TO +5C AT RAPID CITY AND +10C AT NORTH PLATTE.
DESPITE THE DECENT WARM ADVECTION PATTERN IN PLACE...SURFACE
DEWPOINTS HAVE BEEN SLOW TO RISE. DEWPOINTS WERE ONLY IN THE LOW TO
MID 30S OVER THE CENTRAL PLAINS...WHICH WAS AT LEAST HIGHER THAN IN
THE DAKOTAS WHICH WERE IN THE 20S.
THE FOCUS FOR THE SHORT TERM IS ON TWO PARTS...
1. WARM ADVECTION WELL DOWNSTREAM OF THE PACIFIC NORTHWEST SHORTWAVE
TROUGH
2. EVENTUAL APPROACH OF THE PACIFIC NORTHWEST SHORTWAVE TROUGH
SUBSIDENCE AND DRY AIR ASSOCIATED WITH THE SURFACE HIGH WILL
DOMINATE THIS MORNING. AS WE HEAD INTO THE AFTERNOON...THE UPPER
RIDGE AXIS OVER THE NORTHERN PLAINS IS PROGGED TO SLIDE INTO THE
FORECAST AREA. THUS...AN INCREASE OF THE MID AND HIGH LEVEL CLOUDS
IS LIKELY AS SEEN BACK IN THE DAKOTAS. THE QUESTIONS ARE WILL
PRECIPITATION DEVELOP...AND IF SO WHERE AND WHEN...AS THE WARM
ADVECTION INCREASES THROUGH THE AFTERNOON AND EVENING. THE 05.00Z
GFS/REGIONAL CANADIAN ARE BY FAR THE MOST AGGRESSIVE...DEVELOPING
RAIN ALONG/WEST OF THE MISSISSIPPI RIVER BETWEEN 18-00Z TODAY. THE
05.00Z NAM/05.00Z ECMWF/04.21Z SREF ALSO DEVELOP THE RAIN...BUT KEEP
IT CONFINED NORTHWEST OF THE FORECAST AREA PRIOR TO 00Z. THE LACK OF
MOISTURE CURRENTLY AVAILABLE WOULD SUPPORT THE DRIER SCENARIO...
HOWEVER...850MB MOISTURE TRANSPORT DOES INTENSIFY THROUGH THE DAY
AND BY 00Z IS POINTING ON THE WEST SIDE OF THE FORECAST AREA.
THUS...FELT AT LEAST KEEPING SOME 20-50 PERCENT CHANCES LATE IN THE
DAY ARE APPROPRIATE OVER THE WESTERN PORTIONS OF THE FORECAST
AREA...HIGHEST FROM WABASHA INTO DODGE COUNTIES.
FOR TONIGHT...MODELS PROG THE PACIFIC NORTHWEST SHORTWAVE TROUGH TO
ENTER WESTERN SOUTH DAKOTA...CAUSING A SURFACE LOW TO FORM AND
DEEPEN OVER SOUTHERN SOUTH DAKOTA. PERSISTENT AND INTENSIFYING WARM
ADVECTION AHEAD OF THIS SHORTWAVE TROUGH AND SURFACE LOW LOOKS TO
EXPAND THE AREA OF PRECIPITATION OVER MOST LOCATIONS EAST OF THE
MISSISSIPPI RIVER IN THE EVENING...WHICH THEN LIFTS NORTHEAST AFTER
MIDNIGHT. EVAPORATIVE COOLING MAY CAUSE THE PRECIPITATION TO SWITCH
FROM RAIN TO SNOW IN THE EVENING NORTHEAST OF I-94...BUT EVENTUALLY
WARMER AIR ADVECTS IN THERE AFTER MIDNIGHT ALOFT AND THEN SURFACE
TO CAUSE A CHANGE-OVER TO SLEET AND RAIN. IF TEMPERATURES CAN HOLD
BELOW FREEZING...A VERY BRIEF PERIOD OF FREEZING RAIN WOULD OCCUR.
MODEL CONSENSUS CONTINUES TO FAVOR ALONG/NORTHEAST OF I-94 TO HAVE
THE BULK OF THE PRECIPITATION...THUS PRECIPITATION CHANCES NEAR 100
SEEMS REASONABLE. REGARDING SNOWFALL ACCUMULATION...GIVEN THE
GENERAL WARM SENSE TO THIS WARM ADVECTION EVENT...NOTED BY 850MB
TEMPS THAT ARE ONLY -2 TO -4C WHEN IT IS SNOWING...SNOW TO WATER
RATIOS SHOULD ONLY MAX OUT AROUND 10 TO 1. WITH UPWARDS OF 0.1-0.3
INCHES OF QPF PROGGED...SNOW TOTALS COULD BE AS MUCH AS 3
INCHES...THOUGH THE MAJORITY SHOULD END UP IN THE 1 TO 2 INCH
RANGE...NOT ENOUGH FOR AN ADVISORY AT THIS POINT. COULD USE THE MIX
PRECIPITATION AS A NEED FOR THE ADVISORY...BUT CONFIDENCE ON THE
AMOUNT OF MIXED PRECIPITATION IS TOO LOW TO WARRANT ONE.
TEMPERATURES TODAY WILL END UP COOLER COMPARED TO YESTERDAY DUE TO
INCREASING CLOUDS AS WELL AS 850MB TEMPS BETWEEN -2 AND -6C AT 18Z.
FOR TONIGHT...INCREASING SOUTHERLY WINDS PLUS CLOUDS SHOULD HELP
KEEP TEMPERATURES UP AT OR ABOVE FREEZING. IN FACT...EXPECTING
TEMPERATURES TO CLIMB LATE IN THE NIGHT AS THE SURFACE WARM FRONT
LIFTS NORTH TOWARDS I-94.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 341 AM CDT FRI APR 5 2013
HIGHLIGHTS:
1. CURRENT PACIFIC NORTHWEST SHORTWAVE TROUGH PROGGED TO MOVE
THROUGH THE AREA ON SATURDAY
2. POTENTIAL FOR AN ACTIVE BUT HARD TO TIME PRECIPITATION PATTERN
SUNDAY NIGHT AND BEYOND.
MODELS ARE IN REALLY GOOD AGREEMENT TRACKING THE SHORTWAVE TROUGH
THAT WAS OVER SOUTH DAKOTA LATE TONIGHT INTO AND POSSIBLY THROUGH
THE FORECAST AREA ON SATURDAY. STRONG DYNAMIC FORCING WITH THIS
SHORTWAVE...NOTED SIMPLY BY 60-90 METER HEIGHT FALLS IN 12 HOURS AT
500MB...ALONG WITH THAT SURGE OF 850MB MOISTURE TRANSPORT AHEAD OF
THE SHORTWAVE PROVIDING MOISTURE SHOULD HELP PRODUCE RAIN ACROSS
MOST OF THE FORECAST AREA. THE ONLY MODEL NOT SHOWING THIS IS THE
05.00Z NAM...AT LEAST SOUTH OF I-90...WHICH SEEMS ODD GIVEN THE
FORCING. THE 05.00Z REGIONAL CANADIAN IS ACTUALLY QUITE ROBUST SOUTH
OF I-90 WITH QPF AMOUNTS OF 0.1-0.25 INCHES WITH A FEW ISOLATED 0.5
INCH AMOUNTS FROM VERNON INTO ADAMS COUNTIES. IT APPEARS THE HEAVIER
QPF IS A RESULT OF CONVECTIVE ELEMENTS FORMING AHEAD OF THE
SHORTWAVES ASSOCIATED COLD FRONT AT THE SURFACE. INSTABILITY IS
FAIRLY MEAGER DUE TO CAPPING AROUND 750MB AND LIMITED MOISTURE.
HOWEVER...THERE IS A ZONE OF NEGATIVE EPV DUE TO UPRIGHT INSTABILITY
IN CROSS-SECTIONS AROUND 700MB...THUS A FEW THUNDERSTORMS CANNOT BE
RULED OUT. PRECIPITATION SHOULD SHIFT OFF TO THE EAST PRETTY QUICK
LATE IN THE AFTERNOON INTO THE EARLY EVENING FOR MOST OF THE
AREA...AS STRONG SUBSIDENCE COMES IN BEHIND THE SHORTWAVE TROUGH.
ONLY PLACE THIS MAY NOT OCCUR AS FAST IS NORTH AND EAST OF
I-94...DUE TO THE SUGGESTION OF A SHORTWAVE COMING IN BEHIND THE
SHORTWAVE TROUGH AND A MID-LEVEL FRONTOGENESIS ZONE DROPPING
SOUTHEAST. TEMPERATURES MAY COOL ENOUGH TO ALLOW FOR SOME SNOW OUT
OF THIS PRECIPITATION BEFORE IT ENDS BY MIDNIGHT. VERY LITTLE
ACCUMULATION ANTICIPATED...THOUGH.
A MAJOR PATTERN CHANGE IS FORECAST TO TAKE PLACE SUNDAY AS A POTENT
SHORTWAVE TROUGH IMPACTS AND DIGS INTO THE PACIFIC NORTHWEST.
HEADING INTO THE EARLY PORTION OF THE WORK WEEK...MODELS ARE IN GOOD
AGREEMENT DIGGING THIS TROUGH SOUTH INTO THE FOUR CORNERS REGION...
SETTING UP A SOUTHWEST FLOW PATTERN INTO THE FORECAST AREA. THIS
MEANS HARD TO TIME SHORTWAVES AND THUS PLENTY OF UNCERTAINTY. TAKE
FOR EXAMPLE SUNDAY NIGHT WHERE THE 05.00Z ECMWF/NAM BRING A
SHORTWAVE THROUGH THE AREA WITH WIDESPREAD QPF. THE 05.00Z CANADIAN
IS EVEN MORE POTENT WITH THIS SHORTWAVE AND A BIT FARTHER SOUTHEAST.
ON THE OTHER HAND...THE 05.00Z GFS DOES NOT SHOW THE SHORTWAVE AT
ALL...THUS RESULTING IN A DRY FORECAST. MAJORITY HERE SUGGESTS AT
LEAST 30-50 PERCENT PRECIPITATION CHANCES ARE NEEDED. MOST OF THE
PRECIPITATION SHOULD FALL AS RAIN...BUT COULD MIX WITH SNOW
ALONG/NORTHEAST OF I-94.
THE MOST INTERESTING TIME PERIOD OF NEXT WEEK IS TUESDAY INTO
WEDNESDAY...AS THE UPPER TROUGH IN THE SOUTHWEST U.S. EJECTS OUT.
THERE REMAINS A WHOLE LOT OF UNCERTAINTY ON THE TIMING AND DETAILS
OF THIS EJECTION. HOWEVER...EVERY MODEL AVAILABLE AT THIS POINT HAS
SOME SYSTEM AFFECTING THE AREA. WE COULD END UP SEEING CONVECTION IN
THE GFS SCENARIO...POTENTIAL FOR MODERATE TO HEAVY RAINFALL IN ANY
MODEL...AND EVEN SOME SNOW ON THE BACK SIDE OF THE SYSTEM ONCE THE
UPPER TROUGH MOVES OVERHEAD. WE WILL HAVE TO KEEP A WATCH ON THIS
PERIOD. GIVEN THE CONSENSUS AGREEMENT FOR PRECIPITATION TUESDAY INTO
TUESDAY NIGHT...RAISED PRECIPITATION CHANCES DURING THIS PERIOD. MAY
NEED TO RAISE CHANCES FOR WEDNESDAY AS WELL.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 652 AM CDT FRI APR 5 2013
CLOUDS WILL MOVE INTO THE AREA LATE THIS MORNING AND AFTERNOON
AHEAD OF A LOW PRESSURE SYSTEM MOVING OUT OF THE NORTHERN PLAINS.
CEILINGS WILL QUICKLY DROP FROM 10K FEET TO AROUND 3500 FEET.
THESE CEILINGS WILL REMAIN BETWEEN 2500 AND 3500 FEET FOR THE
REMAINDER OF THE PERIOD. SHOWERS WILL MOVE INTO KRST AROUND 05.19Z
AND KLSE 05.22Z. DUE TO MODEL INCONSISTENCY...THERE ARE SOME
QUESTIONS ON WHETHER THERE WILL BE SOME DRY PERIODS TONIGHT. SINCE
THIS WAS STILL A BIT UNCLEAR...JUST KEPT THE THREAT OF SHOWERS
GOING FOR THE REMAINDER OF THE FORECAST.
&&
.HYDROLOGY...
ISSUED AT 341 AM CDT FRI APR 5 2013
RIVER STATUS...
HYDROGRAPHS ACROSS THE AREA SHOW TRIBUTARY RIVERS AND STREAMS INTO
THE MISSISSIPPI RUNNING WITHIN BANK FLOWS WITH A FEW HIGHER THAN
NORMAL GIVEN THE SNOW MELT. MOST OF THE HIGH RIVER FLOWS ARE
CONFINED TO RIVERS NORTH OF I-90 WHERE SNOW PACK STILL EXISTS. THE
WHITEWATER...TREMPEALEAU AND BLACK RIVERS ARE OF CONCERN AT THE
MOMENT.
SNOW PACK...
LATEST NOHRSC DATA SHOWED SNOW WATER EQUIVALENTS STILL IN THE 1-2
INCH RANGE OVER WINONA...BUFFALO...TREMPEALEAU AND JACKSON
COUNTIES...WHILE 2-3 INCH AMOUNTS WERE PRESENT IN CLARK AND TAYLOR
COUNTIES.
RAINFALL...
THE SYSTEM COMING IN FOR TONIGHT AND SATURDAY NOW LOOKS TO NOT
PRODUCE AS MUCH RAINFALL AS PREVIOUSLY EXPECTED...MOSTLY LESS THAN
1/3 OF AN INCH SOUTHWEST OF I-94 TO 1/3 TO 1/2 INCH NORTH OF I-94.
NOTE THAT SOME SNOW IS FORECAST TONIGHT NORTH AND EAST OF
I-94...WHICH COULD TOTAL UP TO 0.3 OF LIQUID EQUIVALENT. ADDITIONAL
RAINFALL IS POSSIBLE SUNDAY NIGHT WITH POTENTIAL FOR MODERATE TO
HEAVY RAINFALL TUESDAY INTO WEDNESDAY OF NEXT WEEK.
TEMPERATURES...
A COOLER DAY BUT STILL PLENTY WARM ENOUGH FOR SNOW MELT IS EXPECTED
TODAY AS HIGHS CLIMB INTO THE 40S. PROBLEM TONIGHT IS THAT
TEMPERATURES MAY NOT FALL BELOW FREEZING AND WITH WARMER CONDITIONS
ANTICIPATED ON SATURDAY...WE COULD REALLY SEE SOME SNOW MELT. MOST
OF THE NEXT 7 DAYS LOOK TO HAVE DAYTIME TEMPERATURES AT LEAST
40...THUS FAVORABLE CONDITIONS ARE IN PLACE FOR SNOW MELT EVERY DAY.
FROST DEPTH...
FROST REMAINS FAIRLY DEEP IN THE GROUND STILL. AS OF 7 AM APRIL
4TH...CUBA CITY WI WAS AT 16 INCHES...WHITEHALL WAS AT 19
INCHES...AND BLOOMER IN CHIPPEWA COUNTY WAS AT 38 INCHES.
SUMMARY...
NOW THAT LESS RAINFALL IS FORECAST THAN EXPECTED FOR TONIGHT AND
SATURDAY...ANY FLOODING CONCERN WOULD COME MOSTLY FROM SNOW MELT THE
NEXT FEW DAYS. CERTAINLY ANY RIVERS AND STREAMS FROM WINONA AND
WABASHA COUNTIES INTO BUFFALO TREMPEALEAU...JACKSON...CLARK AND
TAYLOR WOULD BE OF CONCERN. HAVE DECIDED TO KEEP THE ESF GOING
AND EXPANDED IT INTO WINONA COUNTY GIVEN THE ISSUES BEING
EXPERIENCED ON THE WHITEWATER RIVER. CONSIDERED ISSUING A FLOOD
WATCH FOR JUST RIVERS...BUT GIVEN THAT LESS RAINFALL IS EXPECTED
AND WE ALREADY HAVE EXPERIENCED RIVERS IN AND OUT OF MINOR FLOOD
STAGE THE LAST FEW DAYS...FEEL THE ESF IS STILL VALID. MAY STILL
NEED A FLOOD WATCH...THOUGH...AS CERTAINTY INCREASES ABOUT THE
AMOUNT OF SNOW MELT THIS WEEKEND. EITHER WAY...DEFINITELY NEED TO
KEEP AN EYE ON TUESDAY INTO WEDNESDAY OF NEXT WEEK.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...BOYNE
HYDROLOGY...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
341 AM CDT FRI APR 5 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT FRI APR 5 2013
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED A SHORTWAVE TROUGH OVER THE PACIFIC NORTHWEST...RIDGING FROM
WEST TEXAS INTO THE NORTHERN PLAINS...AND NORTHERN STREAM TROUGHING
IN THE GREAT LAKES. IN THE WAKE OF THIS TROUGHING...HIGH PRESSURE
HAS BEEN BUILDING IN AT THE SURFACE ACROSS MINNESOTA. 00Z MPX
SOUNDING SHOWED PLENTY OF SUBSIDENCE AND DRY AIR ACCOMPANYING THE
SURFACE HIGH...WITH PRECIPITABLE WATER VALUE AT 0.28 INCHES. AS A
RESULT...SKIES ARE CLEAR ACROSS THE FORECAST AREA. JUST OFF TO THE
WEST...MID AND HIGH LEVEL CLOUDS WERE INCREASING ACROSS THE NORTHERN
PLAINS INTO WESTERN MINNESOTA...WELL DOWNSTREAM OF THE PACIFIC
NORTHWEST SHORTWAVE. THESE CLOUDS ARE ASSOCIATED WITH A WARM
ADVECTION REGIME ON THE TOP OF THE RIDGE...AS WELL AS HELP FROM A
120KT JET STREAK FROM SOUTHERN MANITOBA INTO EASTERN MINNESOTA.
PROFILER AND VAD WIND DATA AT 850MB SHOWED A 30-50 KT SOUTH JET FROM
EASTERN COLORADO INTO THE WESTERN DAKOTAS. ALSO PRESENT AT 850MB WAS
A TIGHT TEMPERATURE GRADIENT...REFLECTED BY 00Z SOUNDINGS OF -6C AT
BISMARCK COMPARED TO +5C AT RAPID CITY AND +10C AT NORTH PLATTE.
DESPITE THE DECENT WARM ADVECTION PATTERN IN PLACE...SURFACE
DEWPOINTS HAVE BEEN SLOW TO RISE. DEWPOINTS WERE ONLY IN THE LOW TO
MID 30S OVER THE CENTRAL PLAINS...WHICH WAS AT LEAST HIGHER THAN IN
THE DAKOTAS WHICH WERE IN THE 20S.
THE FOCUS FOR THE SHORT TERM IS ON TWO PARTS...
1. WARM ADVECTION WELL DOWNSTREAM OF THE PACIFIC NORTHWEST SHORTWAVE
TROUGH
2. EVENTUAL APPROACH OF THE PACIFIC NORTHWEST SHORTWAVE TROUGH
SUBSIDENCE AND DRY AIR ASSOCIATED WITH THE SURFACE HIGH WILL
DOMINATE THIS MORNING. AS WE HEAD INTO THE AFTERNOON...THE UPPER
RIDGE AXIS OVER THE NORTHERN PLAINS IS PROGGED TO SLIDE INTO THE
FORECAST AREA. THUS...AN INCREASE OF THE MID AND HIGH LEVEL CLOUDS
IS LIKELY AS SEEN BACK IN THE DAKOTAS. THE QUESTIONS ARE WILL
PRECIPITATION DEVELOP...AND IF SO WHERE AND WHEN...AS THE WARM
ADVECTION INCREASES THROUGH THE AFTERNOON AND EVENING. THE 05.00Z
GFS/REGIONAL CANADIAN ARE BY FAR THE MOST AGGRESSIVE...DEVELOPING
RAIN ALONG/WEST OF THE MISSISSIPPI RIVER BETWEEN 18-00Z TODAY. THE
05.00Z NAM/05.00Z ECMWF/04.21Z SREF ALSO DEVELOP THE RAIN...BUT KEEP
IT CONFINED NORTHWEST OF THE FORECAST AREA PRIOR TO 00Z. THE LACK OF
MOISTURE CURRENTLY AVAILABLE WOULD SUPPORT THE DRIER SCENARIO...
HOWEVER...850MB MOISTURE TRANSPORT DOES INTENSIFY THROUGH THE DAY
AND BY 00Z IS POINTING ON THE WEST SIDE OF THE FORECAST AREA.
THUS...FELT AT LEAST KEEPING SOME 20-50 PERCENT CHANCES LATE IN THE
DAY ARE APPROPRIATE OVER THE WESTERN PORTIONS OF THE FORECAST
AREA...HIGHEST FROM WABASHA INTO DODGE COUNTIES.
FOR TONIGHT...MODELS PROG THE PACIFIC NORTHWEST SHORTWAVE TROUGH TO
ENTER WESTERN SOUTH DAKOTA...CAUSING A SURFACE LOW TO FORM AND
DEEPEN OVER SOUTHERN SOUTH DAKOTA. PERSISTENT AND INTENSIFYING WARM
ADVECTION AHEAD OF THIS SHORTWAVE TROUGH AND SURFACE LOW LOOKS TO
EXPAND THE AREA OF PRECIPITATION OVER MOST LOCATIONS EAST OF THE
MISSISSIPPI RIVER IN THE EVENING...WHICH THEN LIFTS NORTHEAST AFTER
MIDNIGHT. EVAPORATIVE COOLING MAY CAUSE THE PRECIPITATION TO SWITCH
FROM RAIN TO SNOW IN THE EVENING NORTHEAST OF I-94...BUT EVENTUALLY
WARMER AIR ADVECTS IN THERE AFTER MIDNIGHT ALOFT AND THEN SURFACE
TO CAUSE A CHANGE-OVER TO SLEET AND RAIN. IF TEMPERATURES CAN HOLD
BELOW FREEZING...A VERY BRIEF PERIOD OF FREEZING RAIN WOULD OCCUR.
MODEL CONSENSUS CONTINUES TO FAVOR ALONG/NORTHEAST OF I-94 TO HAVE
THE BULK OF THE PRECIPITATION...THUS PRECIPITATION CHANCES NEAR 100
SEEMS REASONABLE. REGARDING SNOWFALL ACCUMULATION...GIVEN THE
GENERAL WARM SENSE TO THIS WARM ADVECTION EVENT...NOTED BY 850MB
TEMPS THAT ARE ONLY -2 TO -4C WHEN IT IS SNOWING...SNOW TO WATER
RATIOS SHOULD ONLY MAX OUT AROUND 10 TO 1. WITH UPWARDS OF 0.1-0.3
INCHES OF QPF PROGGED...SNOW TOTALS COULD BE AS MUCH AS 3
INCHES...THOUGH THE MAJORITY SHOULD END UP IN THE 1 TO 2 INCH
RANGE...NOT ENOUGH FOR AN ADVISORY AT THIS POINT. COULD USE THE MIX
PRECIPITATION AS A NEED FOR THE ADVISORY...BUT CONFIDENCE ON THE
AMOUNT OF MIXED PRECIPITATION IS TOO LOW TO WARRANT ONE.
TEMPERATURES TODAY WILL END UP COOLER COMPARED TO YESTERDAY DUE TO
INCREASING CLOUDS AS WELL AS 850MB TEMPS BETWEEN -2 AND -6C AT 18Z.
FOR TONIGHT...INCREASING SOUTHERLY WINDS PLUS CLOUDS SHOULD HELP
KEEP TEMPERATURES UP AT OR ABOVE FREEZING. IN FACT...EXPECTING
TEMPERATURES TO CLIMB LATE IN THE NIGHT AS THE SURFACE WARM FRONT
LIFTS NORTH TOWARDS I-94.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 341 AM CDT FRI APR 5 2013
HIGHLIGHTS:
1. CURRENT PACIFIC NORTHWEST SHORTWAVE TROUGH PROGGED TO MOVE
THROUGH THE AREA ON SATURDAY
2. POTENTIAL FOR AN ACTIVE BUT HARD TO TIME PRECIPITATION PATTERN
SUNDAY NIGHT AND BEYOND.
MODELS ARE IN REALLY GOOD AGREEMENT TRACKING THE SHORTWAVE TROUGH
THAT WAS OVER SOUTH DAKOTA LATE TONIGHT INTO AND POSSIBLY THROUGH
THE FORECAST AREA ON SATURDAY. STRONG DYNAMIC FORCING WITH THIS
SHORTWAVE...NOTED SIMPLY BY 60-90 METER HEIGHT FALLS IN 12 HOURS AT
500MB...ALONG WITH THAT SURGE OF 850MB MOISTURE TRANSPORT AHEAD OF
THE SHORTWAVE PROVIDING MOISTURE SHOULD HELP PRODUCE RAIN ACROSS
MOST OF THE FORECAST AREA. THE ONLY MODEL NOT SHOWING THIS IS THE
05.00Z NAM...AT LEAST SOUTH OF I-90...WHICH SEEMS ODD GIVEN THE
FORCING. THE 05.00Z REGIONAL CANADIAN IS ACTUALLY QUITE ROBUST SOUTH
OF I-90 WITH QPF AMOUNTS OF 0.1-0.25 INCHES WITH A FEW ISOLATED 0.5
INCH AMOUNTS FROM VERNON INTO ADAMS COUNTIES. IT APPEARS THE HEAVIER
QPF IS A RESULT OF CONVECTIVE ELEMENTS FORMING AHEAD OF THE
SHORTWAVES ASSOCIATED COLD FRONT AT THE SURFACE. INSTABILITY IS
FAIRLY MEAGER DUE TO CAPPING AROUND 750MB AND LIMITED MOISTURE.
HOWEVER...THERE IS A ZONE OF NEGATIVE EPV DUE TO UPRIGHT INSTABILITY
IN CROSS-SECTIONS AROUND 700MB...THUS A FEW THUNDERSTORMS CANNOT BE
RULED OUT. PRECIPITATION SHOULD SHIFT OFF TO THE EAST PRETTY QUICK
LATE IN THE AFTERNOON INTO THE EARLY EVENING FOR MOST OF THE
AREA...AS STRONG SUBSIDENCE COMES IN BEHIND THE SHORTWAVE TROUGH.
ONLY PLACE THIS MAY NOT OCCUR AS FAST IS NORTH AND EAST OF
I-94...DUE TO THE SUGGESTION OF A SHORTWAVE COMING IN BEHIND THE
SHORTWAVE TROUGH AND A MID-LEVEL FRONTOGENESIS ZONE DROPPING
SOUTHEAST. TEMPERATURES MAY COOL ENOUGH TO ALLOW FOR SOME SNOW OUT
OF THIS PRECIPITATION BEFORE IT ENDS BY MIDNIGHT. VERY LITTLE
ACCUMULATION ANTICIPATED...THOUGH.
A MAJOR PATTERN CHANGE IS FORECAST TO TAKE PLACE SUNDAY AS A POTENT
SHORTWAVE TROUGH IMPACTS AND DIGS INTO THE PACIFIC NORTHWEST.
HEADING INTO THE EARLY PORTION OF THE WORK WEEK...MODELS ARE IN GOOD
AGREEMENT DIGGING THIS TROUGH SOUTH INTO THE FOUR CORNERS REGION...
SETTING UP A SOUTHWEST FLOW PATTERN INTO THE FORECAST AREA. THIS
MEANS HARD TO TIME SHORTWAVES AND THUS PLENTY OF UNCERTAINTY. TAKE
FOR EXAMPLE SUNDAY NIGHT WHERE THE 05.00Z ECMWF/NAM BRING A
SHORTWAVE THROUGH THE AREA WITH WIDESPREAD QPF. THE 05.00Z CANADIAN
IS EVEN MORE POTENT WITH THIS SHORTWAVE AND A BIT FARTHER SOUTHEAST.
ON THE OTHER HAND...THE 05.00Z GFS DOES NOT SHOW THE SHORTWAVE AT
ALL...THUS RESULTING IN A DRY FORECAST. MAJORITY HERE SUGGESTS AT
LEAST 30-50 PERCENT PRECIPITATION CHANCES ARE NEEDED. MOST OF THE
PRECIPITATION SHOULD FALL AS RAIN...BUT COULD MIX WITH SNOW
ALONG/NORTHEAST OF I-94.
THE MOST INTERESTING TIME PERIOD OF NEXT WEEK IS TUESDAY INTO
WEDNESDAY...AS THE UPPER TROUGH IN THE SOUTHWEST U.S. EJECTS OUT.
THERE REMAINS A WHOLE LOT OF UNCERTAINTY ON THE TIMING AND DETAILS
OF THIS EJECTION. HOWEVER...EVERY MODEL AVAILABLE AT THIS POINT HAS
SOME SYSTEM AFFECTING THE AREA. WE COULD END UP SEEING CONVECTION IN
THE GFS SCENARIO...POTENTIAL FOR MODERATE TO HEAVY RAINFALL IN ANY
MODEL...AND EVEN SOME SNOW ON THE BACK SIDE OF THE SYSTEM ONCE THE
UPPER TROUGH MOVES OVERHEAD. WE WILL HAVE TO KEEP A WATCH ON THIS
PERIOD. GIVEN THE CONSENSUS AGREEMENT FOR PRECIPITATION TUESDAY INTO
TUESDAY NIGHT...RAISED PRECIPITATION CHANCES DURING THIS PERIOD. MAY
NEED TO RAISE CHANCES FOR WEDNESDAY AS WELL.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1100 PM CDT THU APR 4 2013
HIGH PRESSURE WILL SETTLE ACROSS THE UPPER MISSISSIPPI RIVER VALLEY
OVERNIGHT...WITH VFR SKC CONDITIONS AND GENERALLY LIGHT/VRB
WINDS. HIGH/MID LEVEL CLOUDS WILL BE ON THE INCREASE FRIDAY
AFTERNOON...AHEAD OF AN APPROACHING NORTHERN PLAINS SHORTWAVE
TROUGH. WINDS WILL INCREASE AND BECOME SOUTHERLY BEHIND THE
DEPARTING HIGH. VFR WILL CONTINUE.
FRIDAY NIGHT/SAT POSES SOME DIFFICULTIES FOR CIGS AND RAIN
POTENTIAL. OVERALL...THE NAM/GFS/EC FAVOR KEEPING THE DEEPER
SATURATION AND PCPN CHANCES JUST NORTH OF KRST/KLSE. HOWEVER...SOME
SIGNS THAT THE MOISTURE COULD BE A BIT FARTHER SOUTH...BRINGING A
THREAT FOR MVFR CIGS. ALSO...A GOOD SLUG OF 925-850 MB WARM AIR
ADVECTION/MOISTURE TRANSPORT...WHICH COULD RESULT IN SOME PCPN
CHANCES. THINK THE BEST CHANCES WILL COME WITH THE SYSTEM/S COLD
FRONT...WHICH MOVES EAST ACROSS THE REGION LATE SAT
MORNING/AFTERNOON. THAT SAID...ENOUGH FORCING FRI EVENING TO ADD
-SHRA TO THE TAFS.
&&
.HYDROLOGY...
ISSUED AT 341 AM CDT FRI APR 5 2013
RIVER STATUS...
HYDROGRAPHS ACROSS THE AREA SHOW TRIBUTARY RIVERS AND STREAMS INTO
THE MISSISSIPPI RUNNING WITHIN BANK FLOWS WITH A FEW HIGHER THAN
NORMAL GIVEN THE SNOW MELT. MOST OF THE HIGH RIVER FLOWS ARE
CONFINED TO RIVERS NORTH OF I-90 WHERE SNOW PACK STILL EXISTS. THE
WHITEWATER...TREMPEALEAU AND BLACK RIVERS ARE OF CONCERN AT THE
MOMENT.
SNOW PACK...
LATEST NOHRSC DATA SHOWED SNOW WATER EQUIVALENTS STILL IN THE 1-2
INCH RANGE OVER WINONA...BUFFALO...TREMPEALEAU AND JACKSON
COUNTIES...WHILE 2-3 INCH AMOUNTS WERE PRESENT IN CLARK AND TAYLOR
COUNTIES.
RAINFALL...
THE SYSTEM COMING IN FOR TONIGHT AND SATURDAY NOW LOOKS TO NOT
PRODUCE AS MUCH RAINFALL AS PREVIOUSLY EXPECTED...MOSTLY LESS THAN
1/3 OF AN INCH SOUTHWEST OF I-94 TO 1/3 TO 1/2 INCH NORTH OF I-94.
NOTE THAT SOME SNOW IS FORECAST TONIGHT NORTH AND EAST OF
I-94...WHICH COULD TOTAL UP TO 0.3 OF LIQUID EQUIVALENT. ADDITIONAL
RAINFALL IS POSSIBLE SUNDAY NIGHT WITH POTENTIAL FOR MODERATE TO
HEAVY RAINFALL TUESDAY INTO WEDNESDAY OF NEXT WEEK.
TEMPERATURES...
A COOLER DAY BUT STILL PLENTY WARM ENOUGH FOR SNOW MELT IS EXPECTED
TODAY AS HIGHS CLIMB INTO THE 40S. PROBLEM TONIGHT IS THAT
TEMPERATURES MAY NOT FALL BELOW FREEZING AND WITH WARMER CONDITIONS
ANTICIPATED ON SATURDAY...WE COULD REALLY SEE SOME SNOW MELT. MOST
OF THE NEXT 7 DAYS LOOK TO HAVE DAYTIME TEMPERATURES AT LEAST
40...THUS FAVORABLE CONDITIONS ARE IN PLACE FOR SNOW MELT EVERY DAY.
FROST DEPTH...
FROST REMAINS FAIRLY DEEP IN THE GROUND STILL. AS OF 7 AM APRIL
4TH...CUBA CITY WI WAS AT 16 INCHES...WHITEHALL WAS AT 19
INCHES...AND BLOOMER IN CHIPPEWA COUNTY WAS AT 38 INCHES.
SUMMARY...
NOW THAT LESS RAINFALL IS FORECAST THAN EXPECTED FOR TONIGHT AND
SATURDAY...ANY FLOODING CONCERN WOULD COME MOSTLY FROM SNOW MELT THE
NEXT FEW DAYS. CERTAINLY ANY RIVERS AND STREAMS FROM WINONA AND
WABASHA COUNTIES INTO BUFFALO TREMPEALEAU...JACKSON...CLARK AND
TAYLOR WOULD BE OF CONCERN. HAVE DECIDED TO KEEP THE ESF GOING
AND EXPANDED IT INTO WINONA COUNTY GIVEN THE ISSUES BEING
EXPERIENCED ON THE WHITEWATER RIVER. CONSIDERED ISSUING A FLOOD
WATCH FOR JUST RIVERS...BUT GIVEN THAT LESS RAINFALL IS EXPECTED
AND WE ALREADY HAVE EXPERIENCED RIVERS IN AND OUT OF MINOR FLOOD
STAGE THE LAST FEW DAYS...FEEL THE ESF IS STILL VALID. MAY STILL
NEED A FLOOD WATCH...THOUGH...AS CERTAINTY INCREASES ABOUT THE
AMOUNT OF SNOW MELT THIS WEEKEND. EITHER WAY...DEFINITELY NEED TO
KEEP AN EYE ON TUESDAY INTO WEDNESDAY OF NEXT WEEK.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....RIECK
HYDROLOGY...AJ
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1059 PM MDT SAT APR 6 2013
.UPDATE...
ISSUED AT 1059 PM MDT SAT APR 6 2013
CURRENT WATER VAPOR IMAGERY INDICATING SHORT WAVE EMBEDDED WITHIN
THE MODERATE WESTERLY FLOW ALOFT TRANLATING ACROSS EASTERN
COLORADO WITH DISTINCT CLEARING BEHIND SAID WAVE. REGIONAL RADARS
INDICATING ISOLATED TO SCATTERED ECHOES MOVING ACROSS THE EASTERN
PLAINS AS WELL...THOUGH WEB CAMS AND OBSERVATIONS INDICATING MAINLY
VIRGA WITH ONLY A FEW SPRINKLES MAKING IT TO THE GROUND WITH DRY
SUB CLOUD LAYER AND DEW PT DEPRESSIONS STILL 15-20F.
UPDATE ISSUED AT 558 PM MDT SAT APR 6 2013
ADDED ISOLATED POPS TO SOUTHERN PORTIONS OF THE I-25 CORRIDOR WITH
CURRENT RADAR TRENDS INDICATING ECHOES ACROSS THE AREA...THOUGH
NOT SURE HOW MUCH IF ANY IS MAKING IT TO THE GROUND WITH DEW PT
DEPRESSIONS IN EXCESS OF 20 DEGREE. WILL CONTINUE TO MONITOR RADAR
TRENDS THROUGH THE EVENING WITH EMBEDDED SHORT WAVE ACROSS WESTERN
COLORADO TRANSLATING ACROSS THE STATE AND LATEST HRRR DATA
SPREADING A FEW SHOWERS ACROSS THE PIKES PEAK AND PALMER DVD
AROUND MIDNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 323 PM MDT SAT APR 6 2013
CURRENTLY...UPPER 60S TO NR 70 FOR THE PLAINS...AND 40S-50S FOR THE
MT AREAS. WINDS GENERALLY ARE WELL BEHAVED...BUT WILL SEE A FEW
ISOLD WIND GUSTS INT EH 30KT RANGE DUE TO VIRGA. UPSTREAM SHORTWAVE
TO OUR N IS EASILY SEEN IN IR IMAGERY ACROSS NRN UT AND ID. THIS
WILL CROSS OUR AREA FROM AROUND 03Z-09Z TONIGHT...SO EXPECT THIS TO
COINCIDE WITH HIGHEST POPS OVR THE MTS. BEST CHANCE FOR SHOWERS WILL
BE OVER THE CONTDVD N OF KMYP...WHERE THE HIGHER ELEVATIONS COULD
PICK UP ONE TO THREE INCHES OF SNOW THROUGH TOMORROW FROM SCT SHSN.
TOMORROW...WILL START OFF FAIRLY QUIET...THEN COULD SEE A FEW
SHOWERS DEVELOP ACROSS THE AREA AFTER ABOUT 21Z...IN RESPONSE TO
INCREASING UPPER LIFT FROM THE APPROACHING STORM SYSTEM NOW OVER
THE N PACIFIC. INCREASING LAPSE RATES WILL LEAD TO LIFTED INDICES IN
THE MINUS TWO RANGE IN THE AFTERNOON...WHICH COULD LEAD TO A FEW LTG
STRIKES ACROSS THE AREA. BELIEVE LTG WILL BE RATHER LIMITED...BUT
WILL LEAVE MENTION IN THE FORECAST FOR NOW TO PRESERVE CONTINUITY
AND COORDINATION WITH SURROUNDING WFOS. TEMPS SHOULD BE FAIRLY CLOSE
TO TODAY`S READINGS...MAYBE A COUPLE DEGREES HIGHER AS WRLY FLOW
INCREASES.
FIRE WX DANGER ALSO IS ON THE INCREASE TOMORROW DUE TO THE INCREASE
IN WINDS AND CONTINUED DRY CONDITIONS OVERALL. BEST BET FOR CRITICAL
FIRE WX WILL BE OVER THE SAN LUIS VALLEY...WHICH SHOULD SEE GUSTS IN
THE 25-35 KT RANGE IN THE AFTERNOON AND EARLY EVE. WILL HOIST THE
RED FLAG FOR THE VALLEY FOR THIS PERIOD. ALSO COULD SEE SOME
CRITICAL FIRE WX CONDITIONS ACROSS THE LOWER ARKANSAS FROM FREMONT
INTO NRN PUEBLO COUNTY...AND IN HUERFANO COUNTY DUE TO GAP FLOW
THROUGH LA VETA PASS. AT THIS TIME...LOOKS TOO LIMITED IN SCOPE TO
INCLUDE IN THE RED FLAG...BUT MAY HAVE TO BE ADDED BY LATER SHIFTS
IF IT APPEARS THAT WINDS WILL BE MORE WIDESPREAD.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 323 PM MDT SAT APR 6 2013
...POSSIBLE WEATHER TRIFECTA ACROSS SOUTHERN COLORADO MONDAY...
MONDAY HAS A LOT OF WEATHER HAZARD POTENTIAL...INCLUDING POSSIBLE
SEVERE WEATHER ON THE FAR EASTERN PLAINS...FIRE WEATHER OVER MOST
OF THE REST OF THE PLAINS AND WINTER WEATHER IN THE MOUNTAINS.
FIRST THE FIRE WEATHER. MONDAY AFTERNOON INTO EARLY EVENING DEFINITELY
LOOKS LIKE A HIGH FIRE DANGER PERIOD ACROSS MUCH OF THE SOUTHEAST
PLAINS...WITH WINDS...HUMIDITIES AND FUELS ALL MEETING CRITERIA.
WITH GUSTS TO 40 MPH...HUMIDITIES BELOW 15 PERCENT AND DRY FUELS...
THIS IS DAY WHEN OUTDOOR BURNING SHOULD BE SUSPENDED AND ANY OTHER
ACTIVITIES THAT MIGHT SPARK A FIRE SHOULD BE AVOIDED.
NOW THE SEVERE POTENTIAL. PARAMETERS ON BOTH MAJOR MODELS USED FOR THIS
TIME FRAME ARE INDICATING POSSIBLE SEVERE CONVECTION ACROSS THE FAR
EASTERN PLAINS MONDAY AFTERNOON AND EVENING. PARAMETERS INDICATE
TORNADO AS WELL AS LARGE HAIL POTENTIAL. THE THREAT AREA CURRENTLY
LOOKS EAST OF NORTH-SOUTH LINE THROUGH LA JUNTA. THUNDERSTORMS
POSSIBLE ELSEWHERE THIS DAY AS WELL BUT LIKELY NOT SEVERE.
NOW THE SNOW. IT WILL SPREAD INTO THE HIGH COUNTRY MONDAY AFTERNOON
AND START TO SPREAD ONTO THE ADJACENT PLAINS BY TUESDAY MORNING.
STILL BIG UNCERTAINTIES REGARDING THE STORM TRACK. CONTINUES TO
LOOK PRETTY CERTAIN FOR GOOD SNOW AND WIND POTENTIAL OVER THE
MOUNTAINS AND ALONG THE PALMER DIVIDE...WITH MORE IFFY POTENTIAL
ELSEWHERE. REGARDLESS OF THE MODEL...STILL LOOKS LIKE A PERIOD OF
AT LEAST SOME SNOW AND WIND FOR MOST OF SOUTHERN COLORADO...INCLUDING
THE HIGH MOUNTAIN VALLEYS AND THE SOUTHEAST PLAINS FROM LATE
MONDAY NIGHT INTO TUESDAY EVENING. AS WE GET CLOSER...WINTER
WEATHER HIGHLIGHTS WILL LIKELY BE NEEDED FOR THE MOUNTAINS AND
PALMER DIVIDE AND POSSIBLY ELSEWHERE. STORM SHOULD BE MOSTLY EAST
OF THE AREA BY WEDNESDAY EXCEPT FOR LINGERING WIND...COLD AND
MOUNTAIN SNOW SHOWERS. STAY TUNED. LW
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY EVENING)
ISSUED AT 1059 PM MDT SAT APR 6 2013
SHORT WAVE EMBEDDED WITHIN THE MODERATE WESTERLY FLOW ALOFT
TRANLATING ACROSS EASTERN COLORADO WITH DISTINCT CLEARING BEHIND
SAID WAVE AT THIS TIME. WAVE PRODUCING MAINLY VIRGA WITH CIGS
RANGING BETWEEN 070-100 ACROSS THE PLAINS AT THIS TIME. WILL SEE
CLEARING FROM WEST TO EAST THROUGH THE REST OF THE EVENING WITH
VFR CONDITIONS CONTINUING FOR KCOS...KPUB AND KALS FOR THE NEXT
24 HOURS. COULD SEE ISOLD -TSRA DEVELOPING ACROSS THE HIGHER
TERRAIN TOMORROW AFTENROON...WHICH COULD RESULT IN SOME LOCALIZED
STRONG WIND GUSTS.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
FIRE WEATHER WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING
FOR COZ228>233-235-237.
RED FLAG WARNING FROM 1 PM TO 9 PM MDT SUNDAY FOR COZ224.
&&
$$
UPDATE...MW
SHORT TERM...ROSE
LONG TERM...LW
AVIATION...MW
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
410 AM EDT SUN APR 7 2013
...MODERATE RISK FOR RIP CURRENTS TODAY...
.SYNOPSIS...
HIGH PRESSURE WILL PERSIST THROUGH MID WEEK. A COLD FRONT WILL
APPROACH THE AREA LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THROUGH SUNRISE...LOW CLOUDS HAVE YET TO DEVELOP ACROSS THE AREA
EARLY THIS MORNING. KCLX VWP SHOWS WINDS ALOFT HAVE VEERED MORE
SOUTHERLY AS EXPECTED WHILE AT THE SURFACE WINDS REMAIN LIGHT
NORTHEAST. IT APPEARS ANY ISENTROPIC ASSENT THAT IS OCCURRING IS
JUST NOT STRONG ENOUGH TO PRODUCE MUCH CLOUD COVER YET AND
INCOMING RAP GUIDANCE CONTINUES TO SUGGEST THIS WILL BE THE CASE
THROUGH SUNRISE. HAVE ADJUSTED SKY COVER DOWN TO MOSTLY CLEAR TO
PARTLY CLOUDY AND REMOVED ALL INDICATIONS OF MOSTLY CLOUDY SKIES.
HOWEVER...A BRIEF PERIOD OF MOSTLY CLOUDY CONDITIONS CAN NOT BE
RULED OUT MAINLY ACROSS INTERIOR SOUTHEAST GEORGIA. LOWS FROM THE
MID 40S WELL INLAND TO THE LOWER-MID 50S ALONG THE IMMEDIATE COAST
LOOK ON TRACK.
TODAY...LARGE SOUTHWEST-NORTHEAST ORIENTED HIGH PRESSURE CENTERED
OFF NEW ENGLAND WILL STEADILY SHIFT FARTHER OFFSHORE TODAY AS A
FAIRLY ZONAL FLOW DOMINATES ALOFT. ONGOING WEAK WARM ADVECTION
WILL PUSH H8 TEMPERATURES INTO THE 8-9C RANGE WHICH WILL YIELD
SLIGHTLY WARMER HIGH TEMPERATURES COMPARED TO SATURDAY. LOW-LEVEL
THICKNESSES SCHEMES AND MODEL BUFR SOUNDINGS GENERALLY SUPPORT
HIGHS IN THE LOWER-MID 70S WITH CONSIDERABLY COOLER TEMPERATURES
IN THE LOWER 60S AT THE BEACHES WHERE OCEANIC INFLUENCES WILL BE
THE GREATEST. EXPECT ANOTHER RATHER ROBUST SEA BREEZE CIRCULATION
TO FORM ALONG THE BEACHES LATER TODAY WHICH WILL MOVE STEADILY
INLAND DURING THE AFTERNOON HOURS. THIS WILL CAUSE TEMPERATURES TO
DROP ABOUT 5-8 DEGREES ACROSS THE COASTAL COUNTIES WITH ITS
PASSAGE...SIMILAR TO SATURDAY. WITH THE LACK OF STRATOCUMULUS
THIS MORNING...ITS UNCLEAR EXACTLY HOW MUCH CUMULUS WILL DEVELOP
LATER TODAY AS TEMPERATURES WARM INTO THE 70S. SUSPECT THERE WILL
BE AT LEAST A SHALLOW...SOMEWHAT SCATTERED CUMULUS FIELD AHEAD OF
THE SEA BREEZE SO WILL STICK WITH A PARTLY CLOUDY SKIES CHARACTER
FOR TODAY. SKIES WILL LIKELY CLEAR A BIT IN THE WAKE OF THE SEA
BREEZE AS MORE STABLE AIR IS DRAWN INLAND FROM OFF THE ATLANTIC.
THIS MAY RESULT IN A PERIOD OF MOSTLY SUNNY TO SUNNY SKIES PRIOR
TO SUNSET...MAINLY ACROSS THE COASTAL CORRIDORS. NO RAIN IS
EXPECTED EVEN AS THE COASTAL FRONT DRAWS CLOSER TO THE COAST AND
EVENTUALLY BECOMES ABSORBED IN THE BROADER SYNOPTIC FLOW.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
TONIGHT...THE AREA WILL REMAIN ALONG THE WESTERN FRINGES OF
ATLANTIC HIGH PRESSURE TONIGHT. EXPECT MAINLY CLEAR SKIES TO
DOMINATE WITH SOME PATCHY STRATOCUMULUS POSSIBLY MOVING INLAND
FROM OFF THE ATLANTIC. THE BOUNDARY LAYER SHOULD DECOUPLE FOR MOST
AREA AWAY FROM THE IMMEDIATE COAST A FEW HOURS AFTER SUNSET.
GENERALLY FAVORED THE COOLER SIDE OF GUIDANCE GIVEN THE DECENT
RADIATIONAL SETUP. LOWS WILL RANGE FROM THE LOWER 50S INLAND TO
THE MID 50S ALONG THE IMMEDIATE COAST. A FEW UPPER 40S CAN NOT BE
COMPLETELY RULED OUT...MAINLY IN THE NORMALLY COLDER LOCATIONS
SUCH AS ALLENDALE AND JAMESTOWN. COULD SEE SOME SHALLOW GROUND FOG
FORM AFTER MIDNIGHT...BUT ITS PROBABLY NOT WORTH MENTIONING GIVEN
THE LACK OF ANY SIGNIFICANT IMPACT.
MONDAY AND TUESDAY...THE FORECAST AREA WILL REMAIN ON THE PERIPHERY
OF SURFACE HIGH PRESSURE IN THE ATLANTIC EARLY NEXT WEEK. THE UPPER
LEVEL PATTERN WILL BECOME MORE AMPLIFIED BY TUESDAY...AS A DEEP
TROUGH SHIFTS INTO THE CENTRAL PLAINS AND RIDGING STRENGTHENS ACROSS
THE SOUTHEAST COAST. RISING HEIGHTS ALOFT AND SOUTH/SOUTHEAST FLOW
WILL SUPPORT UNSEASONABLY WARM CONDITIONS EACH AFTERNOON. HIGH
TEMPERATURES INLAND WILL RISE INTO THE UPPER 70S TO LOWER 80S ON
MONDAY...WHILE WARMING SOLIDLY INTO THE LOWER 80S BY TUESDAY. THE
ONSHORE COMPONENT TO THE SURFACE FLOW WILL KEEP COASTAL LOCATIONS
NOTABLY COOLER...SUPPRESSING HIGH TEMPERATURES IN THE LOWER TO MID
70S NEAR THE BEACHES. ALTHOUGH LOW LEVEL MOISTURE WILL BE
INCREASING...AND A SEABREEZE BOUNDARY WILL DEVELOP WITHIN MORE
SUMMER-LIKE CONDITIONS...DECENT SUBSIDENCE SHOULD PREVENT DIURNAL
SHOWER DEVELOPMENT. HAVE THUS CAPPED RAIN CHANCES BELOW 15 PERCENT.
WEDNESDAY...DEEP LAYER RIDGING WILL GRADUALLY SHIFT FARTHER INTO
THE ATLANTIC BY MID WEEK...WHILE THE ROBUST UPPER TROUGH
STRETCHING FROM THE NORTHERN PLAINS TO THE SOUTHWEST STATES MAKES
SOME PROGRESS EASTWARD. THIS SYSTEM WILL PROVIDE THE ENERGY TO
SPAWN A SURFACE LOW AND TRAILING COLD FRONT TO THE WEST OF THE
FORECAST AREA. THE GFS MODEL SOLUTIONS HAVE BEEN CONSISTENTLY MORE
AGGRESSIVE IN BREAKING DOWN THE DEEP RIDGING...DECREASING
SUBSIDENCE ENOUGH TO SUPPORT DIURNAL SHOWER DEVELOPMENT WEDNESDAY
AFTERNOON. PREFER TO LEAN TOWARD A MORE CONSERVATIVE AND SLOWER
SCENARIO...THUS CONTINUING TO KEEP RAIN CHANCES BELOW 15 PERCENT.
WILL ALSO CONTINUE TO INDICATE UNSEASONABLY WARM HIGH
TEMPERATURES...REACHING THE LOWER 80S AWAY FROM THE LOCALLY COOLER
COASTLINE DURING THE AFTERNOON HOURS.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
MEDIUM RANGE MODEL SOLUTIONS MAINTAIN SIGNIFICANT DISCREPANCIES IN
THE TIMING OF A COLD FRONT APPROACHING FROM THE WEST LATE IN THE
WEEK. AN ELONGATED UPPER TROUGH OVER THE CENTRAL PLAINS WEDNESDAY
NIGHT WILL BREAK INTO A MORE SPLIT FLOW FEATURE BY THURSDAY.
SLOWER MODEL SOLUTIONS SUGGEST THE SOUTHERN SHORTWAVE ENERGY WILL
SPIN UP A SECONDARY SURFACE LOW ALONG THE GULF COAST STATES THAT
COULD DELAY THE PROGRESS OF THE FRONTAL SYSTEM. IN ADDITION...THERE
IS SOME QUESTION AS TO THE RESILIENCY OF THE UPPER RIDGE AND
SUBSEQUENT IMPACTS ON PRECIPITATION TIMING AND COVERAGE. UPON
COLLABORATION WITH NEIGHBORING FORECAST OFFICES...PREFER TO LEAN
TOWARD THE SLOWER MODELS SOLUTIONS AT THIS TIME. WILL INTRODUCE A
SLIGHT CHANCE OF RAIN FROM WEST TO EAST AS EARLY AS THURSDAY...YET
SUGGEST THE HIGHEST POTENTIAL FOR SHOWER/THUNDERSTORM COVERAGE
FRIDAY AFTERNOON AND EVENING...WHEN THE SOUTHERN STREAM SHORTWAVE
AND SURFACE LOW LIFT INTO THE AREA. REGARDLESS OF MODEL
SOLUTION...THE UNSEASONABLY WARM CONDITIONS AHEAD OF THE FRONTAL
SYSTEM WILL SUPPORT DECENT INSTABILITY AND SUBSEQUENT THUNDERSTORM
DEVELOPMENT. THIS INSTABILITY...WHEN COMBINED WITH A POTENTIAL 40
TO 50 KT LOW LEVEL JET...COULD ALSO ALLOW THUNDERSTORMS TO BECOME
STRONG AND ORGANIZED. HOWEVER...CONFIDENCE IN SUCH DETAILS THIS
FAR OUT REMAINS LOW...ESPECIALLY CONSIDERING CURRENT MODEL
CONSISTENCY ISSUES.
EXPECT THE COLD FRONT TO HAVE CROSSED THE EAST COAST BY FRIDAY
NIGHT...WITH SURFACE HIGH PRESSURE RAPIDLY REBUILDING FROM THE WEST
IN ITS WAKE. HAVE MAINTAINED JUST A SLIGHT CHANCE FOR
SHOWERS/THUNDERSTORMS INTO EARLY SATURDAY...WITH POPS FALLING
BELOW 15 PERCENT FOR THE REMAINDER OF THE WEEKEND. HIGH
TEMPERATURES WILL BE A FEW DEGREES COOLER FROM FRIDAY AFTERNOON
THROUGH SUNDAY...BECOMING CLOSER TO SEASONAL NORMALS IN THE MID
70S BY THE WEEKEND.
&&
.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
GENERALLY VFR. INCREASING MOISTURE FROM OFF THE ATLANTIC WILL
LIKELY SUPPORT SOME STRATOCUMULUS THROUGH SUNRISE. ITS STILL
UNCLEAR AT THIS POINT HOW WIDESPREAD THESE CLOUDS WILL BECOME BUT
LATEST RAP DATA SUGGESTS ANY CIGS THAT ARE ESTABLISHED WILL LIKELY
REMAIN LOW-END VFR...MAINLY AT KSAV WHERE THE RISK FOR LOW CLOUDS
WILL BE THE GREATEST. WILL CARRY VFR CONDITIONS AT BOTH KCHS/KSAV
FOR THE NEXT 24 HOURS. WILL LIKELY SEE A PERIOD OF GUSTY WINDS IN
THE WAKE OF THE AFTERNOON...POSSIBLY REACHING AS HIGH AS 15-18 KT.
EXTENDED AVIATION OUTLOOK...POSSIBLE FLIGHT RESTRICTIONS IN LIGHT
FOG/MIST LATE AT NIGHT AND IN THE MORNING SUNDAY NIGHT THROUGH
WEDNESDAY.
&&
.MARINE...
TODAY...NORTHEAST WINDS WILL GRADUALLY TURN SOUTHEAST TODAY AS THE
COASTAL TROUGH DRIFTS CLOSER TO THE COAST AND GRADUALLY BECOMES
ABSORBED IN THE BROADER SYNOPTIC FLOW. WINDS WILL GENERALLY REMAIN
10-15 KT THROUGH THE DAY...ALTHOUGH THERE WILL LIKELY BE COME
ENHANCEMENT NEAR THE LAND/SEA INTERFACE AND IN THE CHARLESTON
HARBOR AS THE SEA BREEZE DEVELOPS AND MOVES INLAND. SEAS WILL
RANGE FROM 2-4 FT NEARSHORE WATERS WITH 4-5 FT OFFSHORE WATERS.
TONIGHT...THERE ARE NO CONCERNS TONIGHT WITH SOUTHEAST WINDS
DOMINATING. WINDS WILL REMAIN 10-15 KT WITH SEAS 2-4 FT...
HIGHEST OVER THE GEORGIA OFFSHORE WATERS
MONDAY THROUGH FRIDAY...THE MARINE ZONES WILL REMAIN ALONG THE
WESTERN PERIPHERY OF A LARGE AND FAIRLY STRONG RIDGE OF ATLANTIC
HIGH PRESSURE THROUGH THE UPCOMING WEEK. SOUTHEAST/SOUTH
CIRCULATION AROUND THE HIGH WILL BECOME ENHANCED AT TIMES BY
AFTERNOON/EVENING SEA BREEZE CIRCULATIONS...BUT EXPECT WINDS TO BE
CAPPED AT 10 OR 15 KT. SEAS WILL GENERALLY RANGE FROM 2 TO 4 FT
THROUGH MID WEEK. THE GRADIENT WILL LIKELY TIGHTEN BETWEEN THE
ATLANTIC HIGH AND AN APPROACHING COLD FRONT BY THURSDAY. WINDS
AND/OR SEAS COULD THEREFORE BUILD CLOSE TO ADVISORY LEVELS LATE IN
THE FORECAST PERIOD.
RIP CURRENTS...OPTED TO UPGRADE TO A MODERATE RISK FOR RIP
CURRENTS FOR ALL BEACHES TODAY. WW4 OUTPUT SHOWS 8 TO OCCASIONAL 9
SECOND SWELLS DOMINATING FOR MUCH OF THE DAY. TYBEE ISLAND
LIFEGUARDS REPORTED RIP CURRENTS ALONG WITH SEVERAL ASSISTS AND
ONE RESCUE YESTERDAY AFTERNOON. CONSIDERING SIMILAR CONDITIONS
WILL BE IN PLACE TODAY...THERE IS ENOUGH EVIDENCE TO SUPPORT A
MODERATE RISK...DESPITE THE FAIRLY MODEST ONSHORE WIND REGIME.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
ST/79
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
120 AM EDT SUN APR 7 2013
.SYNOPSIS...
HIGH PRESSURE WILL PERSIST THROUGH THE MIDDLE OF NEXT WEEK. A COLD
FRONT WILL APPROACH THE AREA LATE NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
ADJUSTED LOW TEMPERATURES DOWN IN A SEVERAL AREAS PER GOING
TRENDS. HAVING DOUBTS ON THE DEVELOPMENT OF WIDESPREAD
STRATOCUMULUS AS SOME OF THE VARIOUS GUIDANCE SUGGESTS. LOWERED
SKY COVER A CATEGORY IN SOME AREAS PER LATEST RAP SOUNDINGS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/...
SUNDAY...THE FLOW ALOFT IS PRETTY MUCH ZONAL ACROSS THE LOWER 48
STATES...INCLUDING THE LOCAL ZONES. A LARGE AND ELONGATED RIDGE OF
SURFACE HIGH PRESSURE WILL STRETCH FROM EAST OF NEW ENGLAND TO
ACROSS THE SE STATES AND INTO THE GULF OF MEXICO AND BAY OF
CAMPECHE. THE RESULTING SYNOPTIC FLOW VEERS AROUND TO THE SE AND
SOUTH...WHICH PRODUCES TWO IMPORTANT FACTORS IN THE FORECAST
PROCESS. FIRST IT PROVIDES THE AREA WITH SLIGHTLY WARMER CONDITIONS
THAN TODAY...WHILE IT ALSO ALLOWS FOR A NOTICEABLE INCREASE IN LOWER
LEVEL MOISTURE. AS 850 MB TEMPS CLIMB TO 8-9C AND LOW LEVEL
THICKNESS VALUES RISE TO BETWEEN 1362 AND 1372 METERS FROM NE TO
SW...IT ALLOWS FOR MAX TEMPS TO ACTUALLY RISE ABOVE EARLY APRIL
NORMS. LOWER AND MIDDLE 70S WILL BE FAIRLY UNIFORM...EXCEPT FOR THE
SHORELINE SECTIONS WHERE THE COOLING SEA BREEZE/ONSHORE TRAJECTORIES
WILL LIMIT HIGHS TO ONLY THE MID OR UPPER 60S. THE MAJORITY OF THE
MOISTURE IS TRAPPED BENEATH A STRONG SUBSIDENCE INVERSION AND
RESTRICTED TO THE LOWEST 1-1.5 MILES OF THE ATMOSPHERE. WITH THE LOW
AND MID LEVEL LAPSE RATES STEEPENING QUICKLY IN THE MORNING...WE/RE
CONFIDENT THAT THIS WILL PRODUCE PERIODS OF STRATOCUMULUS AND FLAT
CUMULUS CLOUD COVER THROUGHOUT THE DAY...EQUATING TO A PARTLY TO
PERIODICALLY MOSTLY CLOUDY SKY COVER FORECAST. THERE ARE HINTS AT A
COUPLE OF BRIEF SHOWERS FORMING ALONG THE INLAND PENETRATING SEA
BREEZE WITH WEAK ISENTROPIC LIFT AND SOME UPWARD OMEGA FIELDS. BUT
GIVEN LARGE DEW POINT DEPRESSIONS MOSTLY 15 DEGREES OR MORE...POPS
WILL BE LIMITED TO ONLY A SILENT 10 PERCENT.
SUNDAY NIGHT...ATLANTIC RIDGING WILL PERSIST OVERHEAD FROM THE EAST
AND NE...WITH ZONAL FLOW UPSTAIRS. A WARM SE TO SOUTH SYNOPTIC FLOW
AND AT LEAST SOME LOWER STRATOCUMULUS AND/OR STRATUS WILL PREVENT
TEMPS FROM FALLING ANY LOWER THAN THE LOWER OR MIDDLE 50S INLAND
FROM THE INTRACOASTAL...WITH A FEW UPPER 50S ON THE ISLANDS. FOG
COULD BECOME A REALITY WITH HIGHER DEW POINTS...CONDENSATION
PRESSURE DEFICITS FALLING TO 30-50 MB AND GEOSTROPHIC WINDS 10 KT
OR LESS. HOWEVER...WE/LL BE HARD-PRESSED TO REACH OUR CROSS-OVER
TEMPS IN MANY AREAS...THUS NO MORE THAN PATCHY FOG INLAND WELL
LATE.
MONDAY...THE MID AND UPPER PATTERN WILL START TO UNDERGO SOME
CHANGES IN THE LARGER SCALE...AS A MORE AMPLIFIED TROUGH DEVELOPS
OUT WEST. THE QUASI-ZONAL FLOW OVERHEAD LOCALLY WILL TRANSITION TO
SHORT WAVE RIDGING DURING THE SECOND HALF OF THE DAY...RESULTING IN
SOME NOTICEABLE MID LEVEL HEIGHT RISES. THAT ALONG WITH A CONTINUED
INCREASE IN BOTH 850 MB TEMPS AND LOW LEVEL THICKNESSES WILL YIELD
AN EVEN WARMER DAY. HIGHS WILL MAX OUT WITHIN A DEGREE OR TWO EITHER
SIDE OF 80...ALTHOUGH THE ONSHORE FETCH AND SEA BREEZE CIRCULATION
HOLDS COASTAL AREAS TO ONLY THE UPPER 60S TO PERHAPS 70. THE
SYNOPTIC PATTERN WILL EXPERIENCE THE FORMATION OF A TYPICAL WARM
SEASON RIDGE OF BERMUDA HIGH PRESSURE...THAT STRETCHES ACROSS MOST
OF THE EAST AND SE PARTS OF THE NATION. THE SOUTHERLY LOW LEVEL FLOW
AROUND THIS FEATURE WILL CONTINUE TO ADVECT SOME LOW LEVEL MOISTURE
INTO THE REGION...BUT WITH THE LARGE SCALE SINKING AIR WE/LL BE
HARD-PRESSED TO OBTAIN ANY SHOWER ACTIVITY ALONG THE SEA BREEZE.
MONDAY NIGHT...ODDS FAVOR A GREATER POTENTIAL FOR FOG AS
CONDENSATION PRESSURE DEFICITS LOWER TO AROUND 10-30 MB...DEW POINTS
ARE EVEN HIGHER AND CROSS-OVER TEMPS WILL BE ACHIEVED IN MANY
LOCALES. WEAK WARM ADVECTION WILL LIMIT MINIMUM TEMPS TO ONLY THE
MID AND UPPER 50S MOST COMMUNITIES.
TUESDAY...A MORE AMPLIFIED SCENARIO WILL UNFOLD ALOFT...WITH A DEEP
POSITIVELY TILTED TROUGH IN THE ROCKIES TO BAJA CALIFORNIA...WHILE
INCREASED RIDGING FORMS IN THE EAST. MID LEVEL HEIGHTS IN SOUTHERN
SC AND SE GA RISE TO AROUND 5840 METERS...WITH A CONTINUED WARMING
THROUGHOUT MUCH OF THE VERTICAL. BERMUDA HIGH PRESSURE IS AGAIN
FIRMLY IN CONTROL...AND WITH ONLY LIMITED MOISTURE CONFINED IN THE
LOWER LAYERS AND A STRONG SUBSIDENCE INVERSION OUR RAIN CHANCES ARE
CLOSE TO ZERO. THERE IS ONLY A SUBTLE INCREASE IN LOW LEVEL
THICKNESS...SO MAX TEMPS WILL BE A DEGREE OR TWO WARMER THAN ON
MONDAY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
DEEP LAYER RIDGING WILL SHIFT FARTHER INTO THE ATLANTIC WEDNESDAY
AND THURSDAY. THE UPPER TROUGH FAR TO THE WEST WILL ALSO RAPIDLY
SWING INTO THE MISSISSIPPI VALLEY AND SHIFT A COLD FRONT THROUGH
THE OHIO/TENNESSEE VALLEYS. THERE REMAINS CONSIDERABLE TIMING
DIFFERENCES IN MODEL SOLUTIONS REGARDING THE FRONTAL PASSAGE...
WHICH COULD OCCUR AS EARLY AS THURSDAY AFTERNOON OR AS LATE AS
FRIDAY NIGHT. DUE TO THIS UNCERTAINTY...PREFER TO KEEP MUCH OF THE
LONG RANGE FORECAST AS PERSISTENCE UNTIL MODELS COME INTO BETTER
AGREEMENT. HAVE THUS REMAINED RATHER GENERIC...INDICATING RAIN
CHANCES IN THE 20 TO 30 PERCENT RANGE THURSDAY AND FRIDAY. WITH
UNSEASONABLY WARM CONDITIONS CONTINUING PRIOR TO FRONTAL
PASSAGE...THERE WILL BE ENOUGH TIME FOR LOW LEVEL INSTABILITY TO
DEVELOP ACROSS THE AREA AS THE FRONT CROSSES THE REGION. THIS
UNSTABLE AIR...WHEN COMBINED WITH AN IMPRESSIVE 40 TO 50 KT LOW
LEVEL JET...COULD SUPPORT STRONG THUNDERSTORMS LATE THIS WEEK.
CONDITIONS BY SATURDAY COULD BE IMPROVING...AS EVEN THE SLOWEST
MODEL SOLUTIONS HAVE THE FRONT MOVING OFF THE COAST BY THE
AFTERNOON HOURS. EXPECT A SLIGHT COOL DOWN TOWARD SEASONAL NORMALS
IN THE MID 70S BEHIND THE FRONT LATE IN THE PERIOD.
&&
.AVIATION /05Z SUNDAY THROUGH THURSDAY/...
GENERALLY VFR. INCREASING MOISTURE FROM OFF THE ATLANTIC WILL
LIKELY SUPPORT SOME STRATOCUMULUS THROUGH SUNRISE. ITS STILL
UNCLEAR AT THIS POINT HOW WIDESPREAD THESE CLOUDS WILL BECOME BUT
LATEST RAP DATA SUGGESTS ANY CIGS THAT ARE ESTABLISHED WILL LIKELY
REMAIN LOW-END VFR...MAINLY AT KSAV WHERE THE RISK FOR LOW CLOUDS
WILL BE THE GREATEST. WILL CARRY VFR CONDITIONS AT BOTH KCHS/KSAV
FOR THE NEXT 24 HOURS. WILL LIKELY SEE A PERIOD OF GUSTY WINDS IN
THE WAKE OF THE AFTERNOON...POSSIBLY REACHING AS HIGH AS 15-18 KT.
EXTENDED AVIATION OUTLOOK...POSSIBLE FLIGHT RESTRICTIONS IN LIGHT
FOG/MIST LATE AT NIGHT AND IN THE MORNING SUNDAY NIGHT THROUGH
WEDNESDAY.
&&
.MARINE...
THE MAIN CONCERN OVERNIGHT IS SEA HEIGHTS OVER OUR OUTER GEORGIA
WATERS RUNNING POSSIBLY NEAR ADVISORY LEVELS FOR A WHILE. STEADY
NE-E FETCH AND SEAS OBSERVED GREATER THAN MODEL WAVE GUIDANCE WELL
OFF THE S CAROLINA COAST ARE PROBABLY TIPS WE HAVE SOME 6 FOOTERS
OUT THERE CLOSER TO THE GULF STREAM IN AMZ374. MODELS ALLOW THE
FLOW TO LAY DOWN OVERNIGHT AND WE HAVE OPTED NOT TO RAISE A SMALL
CRAFT ADVISORY DURING THIS EVENING GIVEN FORECAST MODEL TRENDS.
STILL A NICE SWELL COMPONENT AND 4-5 FT LOOKING COMMON OVERNIGHT
BEYOND 20 NM. OTHERWISE...FLOW LOCKED NE TONIGHT BY THE COLDER
SHELF WATERS WITH SPEEDS 15 KT OR LESS AND SEAS 3 TO 4 FT.
THE LOCAL WATERS WILL LIE UNDER THE WESTERN PORTION OF A LARGE
AND FAIRLY STRONG RIDGE OF ATLANTIC HIGH PRESSURE THROUGHOUT THE
UPCOMING WEEK. THE ANTICYCLONIC SE AND SOUTH CIRCULATION AROUND
THE HIGH WILL BECOME ENHANCED AT TIMES BY AFTERNOON/EVENING SEA
BREEZE CIRCULATIONS...BUT NOTHING MORE THAN ABOUT 10 OR 15 KT
WINDS AND 2-4 FOOT SEAS THROUGH WEDNESDAY. BY THURSDAY THERE DOES
APPEAR TO BE SOME TIGHTENING OF THE GRADIENT BETWEEN THE HIGH AND
AN APPROACHING COLD FRONT...AND WINDS AND/OR SEAS COULD BUILD
CLOSE TO ADVISORY LEVELS LATE IN THE FORECAST PERIOD.
RIP CURRENTS...DESPITE WATER TEMPS ONLY NEAR 60 AND AIR TEMPS NOT
MUCH HIGHER...THERE ARE STILL PEOPLE FLOCKING TO THE BEACH. AND SOME
ARE VENTURING INTO THE SURF...WITH REPORTS OF RIP CURRENTS AND
RESCUES AT TYBEE BEACH EARLIER TODAY. WITH ONSHORE WINDS AT 10-15
MPH AND AROUND 2 FOOT SWELLS EVERY 8 SECONDS WE/LL BE AT THE
HIGH-END RANGE OF THE LOW RISK OF RIP CURRENTS SUNDAY. IF SWELLS ARE
ABLE TO OBTAIN 3 FEET...A MODERATE RISK WOULD BE REQUIRED. BEACH
GOERS ARE REMINDED THAT EVEN DURING A LOW RISK THAT RIP CURRENTS CAN
STILL OCCUR.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
ST
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
258 AM CDT SUN APR 7 2013
.DISCUSSION...
912 PM CDT
SHOWERS CONTINUE TO MOVE ACROSS NORTHERN ILLINOIS THIS EVENING.
HOWEVER...A CLUSTER OF SHOWERS AND THUNDERSTORMS HAS DEVELOPED OVER
THE PAST COUPLE HOURS ACROSS EASTERN IOWA. THIS ACTIVITY IS FIRING
JUST AHEAD OF A SURFACE COLD FRONT IN AN AREA OF INCREASED ASCENT
AHEAD OF A RATHER STOUT MID LEVEL SHORT WAVE...CURRENTLY NOTED IN
THE WATER VAPOR IMAGERY MOVING EASTWARD ACROSS SOUTHEASTERN IOWA. THE
00 UTC SOUNDING OUT OF KDVN INDICATES THAT THE AIRMASS IN WHICH THIS
ACTIVITY IS DEVELOPING IN POSSES DECENT MID LEVEL LAPSE RATES.
HOWEVER...OVERALL INSTABILITY IS RATHER LACK LUSTER...WITH MUCAPE
VALUES ONLY UP TO AROUND 100 J/KG. IN SPITE OF THIS...THE STRONGER
FORCING FOR ASCENT COMPLEMENTS OF THE MID LEVEL WAVE AND MOISTURE
CONVERGENCE IN THE LOWER LEVELS...IS ABLE TO TAKE ADVANTAGE OF THE
STEEP LAPSE RATES TO RESULT IN THUNDERSTORMS. THIS ACTIVITY WILL
LIKELY MAINTAIN ITSELF FOR THE NEXT FEW HOURS AS IT PUSHES EASTWARD
ACROSS NORTHERN ILLINOIS. THERE COULD EVEN BE SOME SMALL HAIL AND
SOME GUSTY WINDS IN SOME OF THE STRONGEST STORMS GIVEN THE DRIER AIR
IN THE LOWEST FEW THOUSAND FEET. THIS ACTIVITY SHOULD END OVERNIGHT
WITH WINDS BECOMING WESTERLY IN THE WAKE OF THE FRONTAL PASSAGE.
KJB
//PREV DISCUSSION...
259 PM CDT
THERE ARE NUMEROUS CHALLENGES WITH THE FORECAST AS THE PATTERN
TRANSITIONS TO A MORE ACTIVE ONE...BEGINNING WITH SHOWERS AND
SOME SPORADIC THUNDER THIS EVENING AND THEN CARRYING THROUGH THE
MIDDLE OF NEXT WEEK. IN ADDITION...THE LIKELY LOCATION OF THE
AREA RELATIVE TO SYNOPTIC FEATURES WILL ALLOW FOR TEMPERATURES TO
BE HEAVILY DEPENDENT ON CLOUD COVER AND RAIN...ALONG WITH LAKE
INDUCED COOLING AT LEAST A FEW OF THE UPCOMING SEVERAL DAYS.
NEAR TERM INTO TONIGHT...A FAST PACED BUT MORE AMPLIFIED UPPER
LEVEL PATTERN IS ESTABLISHED OVER THE CENTRAL U.S. THIS AFTERNOON
WITH A WELL-DEFINED UPPER WAVE ON WATER VAPOR ADVANCING EASTWARD
FROM WESTERN IA. A 1000 MB SURFACE LOW REFLECTION ACROSS SOUTHERN
MN HAS DEVELOPED AND HELPED TO ESTABLISH STRONG RETURN FLOW WITH
WIND GUSTS TO 40 TO 45 MPH AT SEVERAL SITES. THESE WINDS SHOULD
DIMINISH GRADUALLY THROUGH THE EVENING HOURS.
MOISTURE RETURN HAS STRUGGLED HOWEVER...BOTH AT THE SURFACE AND IN
THE DEEP LAYER PER OBSERVATIONS AND PWAT ANALYSIS AND IS A REASON
SHOWER COVERAGE IS LIKELY TO BE MORE LIMITED THAN IT COULD BE
GIVEN THE UPPER FORCING AHEAD OF THIS WAVE...AND IT WILL TAKE SOME
TIME FOR THE VERY DRY LOWER ATMOSPHERE TO SATURATE. A NARROW
CORRIDOR OF 700-900 MB MOISTURE TRANSPORT ALONG A MID-LEVEL JET
HAS STILL HELPED TO INCREASE ECHOES UPSTREAM DURING THE FIRST HALF
OF THE AFTERNOON AND THIS WILL LIKELY BE JUST ENOUGH TO CONTINUE
DOING SUCH WITH STEEPENING MID-LEVEL LAPSE RATES IN CONCERT WITH
THE NARROW MOISTURE CONVERGENCE. MOST OF THE HIGH-RES CONVECTIVE
ALLOWING MODELS PREDICT AN INCREASE IN CONVECTIVE-TYPE ECHOES
ACROSS NORTH CENTRAL IL BETWEEN 23Z AND 03Z SHIFTING EASTWARD AND
FADING SLOWLY THROUGH EARLY OVERNIGHT AS THE FRONT SHIFTS EAST.
WITH SEVERAL OF THESE GUIDANCE MEMBERS INDICATING HIGHER
REFLECTIVITY AND A NARROW CORRIDOR OF 200-400 J/KG OF MUCAPE PER
THE RAP ALONG THE FRONT...WOULD EXPECT A FEW STORMS WITHIN THE
GENERAL SHOWERS. HAVE ADAPTED HOURLY POPS THROUGH THIS EVENING
PERIOD OF THE FORECAST. AS PREVIOUS FORECAST DID KEEP MOST OF
TONIGHTS TEMPERATURE DROP AFTER THE FRONTAL PASSAGE FROM WEST TO
EAST.
SUNDAY...HIGH PRESSURE STILL LOOKS TO BRIEFLY PREVAIL FOR THIS
PERIOD. THE MOST NOTEWORTHY ASPECT ABOUT THIS IS IT LOOKS TO LINE
UP DOWN THE AXIS OF LAKE MICHIGAN BY MIDDAY AND ALLOW FOR A FAIRLY
STOUT LAKE BREEZE. THIS WILL BE AIDED BY THE FACT THAT
TEMPERATURES SHOULD MODERATE NICELY ON SUNDAY OVER LAND DUE TO
ONLY A SMALL WINDOW OF COLD AIR ADVECTION BEHIND THE FRONT TONIGHT
AND A DRY AIR MASS AND PREDICTED SUNSHINE DURING SUNDAY. THE
TEMPERATURE AND PRESSURE DIFFERENCES WITHIN A LIGHT WIND FIELD
SHOULD DRIVE A STRONG LAKE BREEZE...AND THE AFTERNOON TEMPERATURE
DROP FOR DOWNTOWN CHICAGO AND OTHER NEAR LAKE AREAS MAY BE AS MUCH
AS 15 DEGREES.
SUNDAY NIGHT AND MONDAY...AN ACTIVE WEST-TO-EAST PACIFIC JET OVER
120 KT AS SEEN ON HEMISPHERIC WATER VAPOR TODAY WILL DIG ITS WAY
INTO THE WESTERN U.S. WITH TROUGH DEVELOPMENT AND UPSTREAM
SOUTHWEST FLOW OVER THE MIDWEST. A LEAD IMPULSE IN THIS FLOW IS
WELL PREDICTED ON GUIDANCE TO PASS OVER THE AREA DURING LATE
SUNDAY NIGHT INTO MONDAY MORNING. THIS LOOKS TO TIGHTEN AN UPPER
LEVEL WARM FRONT AND ALLOW FOR SATURATED ISENTROPIC LIFT FOR RAIN
SHOWERS. ELEVATED INSTABILITY DOES INCREASE AS THE WARM NOSE
BUILDS IN WITHIN THE LOWER LEVELS...AND START THUNDER IN THIS
FORECAST PERIOD ITS TOO TOUGH TO DISCERN A PERIOD WHERE THERE
WOULD NOT BE A THUNDER CHANCE ALL THE WAY THROUGH WEDNESDAY NIGHT.
IN THE WAKE OF THIS LEAD IMPULSE HEIGHTS LOOK TO BUILD ON MONDAY
AS THE PRIMARY TROUGH DEVELOPS. ITS A LITTLE INTERESTING AS THERE
SHOULD BE A SURFACE WARM FRONT...POSSIBLY DIABATICALLY
ENHANCED...LAID OUT SOMEWHERE IN THE CENTRAL IL TO NORTHERN IL
REGION. THE ONLY THING IS WITH SHORT WAVE RIDGING HINTED AT THIS
FEATURE APPEARS TO BE FAIRLY BENIGN...BUT SOMETHING TO KEEP AN
EYE ON.
MIDWEEK...AN ACTIVE PERIOD HERE AS PROLONGED SURFACE CYCLOGENESIS
BEGINS OVER THE SOUTHERN PLAINS MONDAY NIGHT AND CONTINUES THROUGH
TUESDAY WITH THE SURFACE WAVE ADVANCING ENE ON WED. MODEL
GUIDANCE HAS COME INTO BETTER AGREEMENT WITH THIS...LATCHING MORE
ONTO AN EC SOUTHERN SOLUTION. HAVE CONTINUED TO LEAN THAT WAY WITH
THE FORECAST WHICH MEANS INHIBITING TEMPERATURES ON WHAT COULD BE
GIVEN 850MB TEMPERATURES CLIMBING TO 8C-12C...ESPECIALLY NORTH OF
I-80. WITH FLOW OFF THE LAKE TUESDAY AND WEDNESDAY DUE TO THE LOW
BEING SOUTHWEST OF THE AREA...TEMPERATURES NEAR THE LAKE WILL
REMAIN COOLER. ALSO THIS FORECAST PATTERN MEANS LIKELY SEVERAL
BOUTS OF PRECIP WITH THE PROXIMITY OF THE ELEVATED WARM/STATIONARY
FRONT. THE 06.12 GFS AND EC RUNS BOTH HAVE OVER TWO AND A HALF
INCHES OF RAIN FORECAST AREA WIDE FROM SUNDAY NIGHT THROUGH
THURSDAY. WHILE IT IS CHALLENGING TO FOCUS ANY WINDOW FOR
CATEGORICAL POPS...IT WOULD SEEM WEDNESDAY AND WEDNESDAY NIGHT
WOULD BE THE MOST FAVORED PERIODS FOR STRONGER DYNAMIC FORCING AND
POSSIBLY MORE ROBUST ELEVATED CONVECTION WITH THE LARGE SCALE
UPPER TROUGH MOVING EASTWARD. COOLING BEHIND THE FRONT LOOKS
SOMEWHAT STRONG AND THERE IS A POTENTIAL TO SEE SOME MIX IN THE
WAKE OF THE FRONT...BUT CONFIDENCE IS VERY LOW ON HOW THIS SYSTEM
WILL EVOLVE AS IT LIFTS OUT.
BEYOND...HAVE GONE PRIMARILY WITH A MODEL CONSENSUS AT THE END OF
NEXT WEEK AS THE UPPER FLOW PATTERN WORKS FROM BRIEFLY NORTHWEST
BACK TO WEST. TEMPERATURES SHOULD GRADUALLY MODERATE BUT
CONFIDENCE IS LOW ON PRECIP CHANCES AS THE PATTERN STILL LOOKS
DISTURBED.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* MVFR CIGS OVERNIGHT INTO SUNDAY MORNING
* WIND SHIFT TO EASTERLY SUNDAY AFTERNOON
IZZI
//DISCUSSION...UPDATED 06Z...
COLD FRONT MOVING THROUGH THE REGION AT THIS TIME WITH SHRA/TSRA
MOVING EAST OF THE REGION. EXPANDING BANK OF STRATUS HAS BEEN
NOTED ON SATELLITE IMAGERY UPSTREAM OVER WI/IA INTO NW IL WITH
GUIDANCE SUGGESTING THIS SHOULD CONTINUE TO EXPAND EAST INTO THE
TERMINALS OVERNIGHT. DOES APPEAR THAT MIXING/HEATING SHOULD HELP
ERODE THE STRATUS SUNDAY MORNING...THOUGH TIMING OF SCATTERING OUT
CIGS IS UNCERTAIN. WESTERLY WINDS SHOULD GUST OCCASIONALLY TO
15-20KT OVERNIGHT BEFORE EASING SUNDAY MORNING. PRESSURE FALLS
OVER THE PLAINS EXPECTED TO RESULT IN AN ABRUPT SHIFT TO EASTERLY
WINDS SUNDAY EVENING...WITH THE TIMING OF THAT WIND SHIFT LIKELY A
BIT EARLIER AT ORD/MDW/GYY AS COLLAPSING GRADIENT IN THE AFTERNOON
SHOULD ALLOW FOR ROBUST LAKE BREEZE DEVELOPMENT. NEXT DISTURBANCE
LIKELY TO APPROACH THE REGION TOWARD THE END OF OR JUST BEYOND
THE ORD 30 TAF HOUR PERIOD WITH ADDITIONAL SHRA/TSRA EXPECTED AT
THAT TIME.
IZZI
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM-HIGH CONFIDENCE IN LOW END MVFR CIGS OVERNIGHT INTO SUN
AM
* LOW-MEDIUM CONFIDENCE ON TIMING OF IMPROVEMENT TO VFR SUNDAY
MORNING
* HIGH CONFIDENCE ON WIND SHIFT TO EAST SUN PM
IZZI
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY...SHRA/TSRA LIKELY EARLY. MVFR/BRIEF IFR POSSIBLE EARLY.
TUESDAY THROUGH THURSDAY NIGHT...PERIODIC CHANCE FOR SHRA/TSRA.
PERIODIC MVFR CIGS/VSBY LIKELY WITH BRIEF IFR POSSIBLE.
FRIDAY...PROBABLE VFR.
MDB
&&
.MARINE...
258 AM CDT
WEAK HIGH PRESSURE WILL BUILD INTO THE REGION TODAY WITH WINDS
SUBSIDING FAIRLY QUICKLY...BEFORE DEVELOPING LAKE BREEZE CIRCULATION
GETS A BOOST FROM GRADUALLY INCREASING SYNOPTIC EASTERLY GRADIENT
THIS AFTERNOON. EASTERLY WINDS LIKELY TO FRESHEN UP LATE TONIGHT
INTO MONDAY MORNING...ESPECIALLY SOUTHERN PORTIONS OF THE LAKE.
FRONT WILL ATTEMPT TO MOVE NORTH MONDAY...BUT MAY GET HUNG UP ALONG
OR JUST OFFSHORE WITH MORE OF AN EAST OR SOUTHEAST WIND LIKELY OVER
OPEN WATERS. SURGE OF HIGHER DEWPOINTS OVER THE COLD LAKE WITH THE
FRONT NEARBY COULD RESULT IN SOME DENSE MARINE FOG MONDAY NIGHT. FOG
SHOULD DISSIPATE TUESDAY ASSUMING THE NORTHEAST WINDS INCREASE AS
FORECAST. THERE REMAINS SOME DISAGREEMENT AMONG THE MODELS WITH
REGARDS TO FRONTAL PLACEMENT...BUT THE MOST RELIABLE MODELS ARE
GENERALLY KEEPING FRONT SOUTH OF THE LAKE MONDAY NIGHT THROUGH END
OF THE WEEK WITH FAIRLY STRONG NORTHEASTERLY FLOW EXPECTED TO
GENERALLY PREVAIL.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 4 AM SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
246 AM CDT SUN APR 7 2013
.DISCUSSION...
ISSUED 245 AM CDT SUN APR 7 2013
COLD FRONT HAS PUSHED THROUGH ABOUT THE NORTHWEST HALF OF THE CWA
AS OF 2 AM...EXTENDING ROUGHLY FROM BLOOMINGTON TO JACKSONVILLE.
NARROW BAND OF SHOWERS ALONG I-70 IS WHAT IS LEFT FROM THE PRE-
FRONTAL CONVECTION WHICH BROUGHT SOME LOCALLY HEAVY SHOWERS LAST
EVENING ACROSS THE NORTHERN CWA. LARGE STRATUS/STRATOCUMULUS DECK
BEHIND THE FRONT HAS BEEN OOZING SOUTHWARD PER FOG CHANNEL
SATELLITE IMAGERY AND HAS REACHED MARSHALL COUNTY...BUT HAS NOT
MADE MUCH FURTHER SOUTHWARD PROGRESSION OVER THE LAST COUPLE
HOURS.
TIMING OF RAIN CHANCES OVER THE NEXT FEW DAYS CONTINUES TO BE A
CHALLENGE...ALONG WITH THE WARM TEMPERATURES.
SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT...
LATEST MODEL GUIDANCE SHOWING WINDS ALREADY SWINGING BACK TO THE
SOUTHEAST BY AFTERNOON ACROSS MUCH OF THE FORECAST AREA...WITH THE
BOUNDARY LIFTING BACK INTO NORTHERN ILLINOIS OVERNIGHT. MOST OF
THE CWA SHOULD BE ABLE TO REACH 70 DEGREES EXCEPT FOR PERHAPS THE
NORTH...ALTHOUGH A FASTER FRONTAL PASSAGE WOULD ALLOW SUCH
TEMPERATURES THERE AS WELL. CURRENTLY LOOKS LIKE THE DAYTIME
SHOULD BE DRY WITH PERHAPS A COUPLE SHOWERS SOUTH OF I-70 LATE
AFTERNOON...WITH NEXT SURGE OF PRECIPITATION SPREADING IN FROM THE
SOUTHWEST IN THE EVENING AHEAD OF THE NEXT SHORTWAVE IN THE
PLAINS. HAVE RAMPED RAIN CHANCES UP INTO THE CATEGORICAL RANGE OF
NEAR 80 PERCENT ALONG AND WEST OF THE ILLINOIS RIVER AFTER
MIDNIGHT...WITH LIKELY POPS IN MOST OTHER AREAS NORTH OF I-70.
MUCH OF THE RAIN SHOULD EXIT THE AREA MONDAY MORNING...ALLOWING
TEMPS TO RISE BACK TO AROUND 70 WITH A DECENT SOUTHERLY FLOW.
UPPER LOW CURRENTLY SPINNING WEST OF BRITISH COLUMBIA SHOULD DROP
SOUTHEASTWARD INTO THE 4-CORNERS REGION BY MONDAY EVENING.
EVENING MODELS COMING INTO SOMEWHAT BETTER AGREEMENT WITH THE
EVOLUTION OF THIS FEATURE THROUGH THE MIDDLE OF THE WEEK...LIFTING
IT NORTHWARD TO NEAR SOUTH DAKOTA BY WEDNESDAY MORNING WITH A
SURFACE LOW TRACKING NORTHEAST INTO IOWA. CONVECTION EXPECTED TO
INCREASE AGAIN MONDAY NIGHT AND WANE TUESDAY AFTERNOON...BEFORE
RAMPING UP AGAIN AS THE MAIN COLD FRONT APPROACHES. HAVE GONE WITH
LIKELY POPS ACROSS THE WEST TUESDAY NIGHT...EVERYWHERE
WEDNESDAY...AND INCREASED THEM TO CATEGORICAL FROM I-57 EAST
WEDNESDAY EVENING AS THE FRONT PASSES. IN TERMS OF SEVERE
POTENTIAL...THE FRONT WILL BE CROSSING DURING A FAVORABLE TIME OF
THE DAY ON WEDNESDAY...WITH MUCAPES INCREASING TO AROUND 1500
J/KG WEDNESDAY AFTERNOON IN THE EASTERN CWA AND LOW-LEVEL WINDS
RAMPING UP TO AROUND 45 KNOTS AT 925 MB. LATEST SPC DAY3
CONVECTIVE OUTLOOK DOES SPREAD SLIGHT CHANCES OF SEVERE WEATHER
ACROSS THE WESTERN CWA WITH SLIGHTLY LOWER CHANCES ACROSS THE
EAST. FORECAST SOUNDINGS WOULD FAVOR MORE OF A WIND THREAT THIS
FAR EAST WITH UNIDIRECTIONAL WIND PROFILES IN THE LOWER LEVELS.
LONG TERM...THURSDAY THROUGH SATURDAY...
LINGERING SHOWERS ON THURSDAY WILL DECREASE FROM WEST TO EAST AS
THE FRONT PULLS AWAY. HOWEVER...LATEST GFS AND ECMWF MODELS SWING
THE REMAINING UPPER LOW THROUGH IOWA AND WISCONSIN...SO SOME
POTENTIAL FOR COLD-CORE SHOWERS CONTINUES MAINLY ACROSS THE
NORTHERN CWA INTO AFTERNOON...ALTHOUGH BEST CHANCES WILL BE CLOSER
TO THE LOW. THE REMAINDER OF THE WEEK WILL MAINLY BE QUIET...AS
HIGH PRESSURE SLOWLY PUSHES EASTWARD THROUGH THE REGION. WILL SEE
A COUPLE OF COOL DAYS THURSDAY AND FRIDAY...WITH TEMPERATURES
FRIDAY MORNING GETTING CLOSE TO FREEZING ACROSS THE NORTHWEST CWA.
GEELHART
&&
.AVIATION...
ISSUED 1154 PM CDT SAT APR 6 2013...FOR THE 06Z TAFS
SOME SHOWERS MAY AFFECT CMI FOR THE FIRST HALF HOUR OF THE TAF
PERIOD...OTHERWISE THE TERMINAL SITES SHOULD REMAIN DRY OVER
THE NEXT 24 HOURS.
THE COLD FRONT WILL PASS ACROSS DEC/CMI OVER THE NEXT HOUR OR
TWO...SO WINDS SHOULD DIMINISH FROM STRONG SOUTH TO LIGHTER
SOUTHWEST AROUND 12-14KT. LATER TONIGHT ALL TAF SITES SHOULD SEE
WEST WINDS AROUND 10KT.
SOME MVFR CLOUDS ARE EXPECTED TO APPROACH OUR NORTHERN
COUNTIES...WITH PIA AND BMI POSSIBLY SEEING SOME OF THAT. LIGHT
FOG MAY EVEN AFFECT PIA AND BMI. I ADDED A TEMPO FOR BKN015 FOR
12Z TO 15Z TO MATCH THE HRRR OUTPUT FOR THAT TIME FRAME.
SHIMON
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1231 AM CDT SUN APR 7 2013
.DISCUSSION...
912 PM CDT
SHOWERS CONTINUE TO MOVE ACROSS NORTHERN ILLINOIS THIS EVENING.
HOWEVER...A CLUSTER OF SHOWERS AND THUNDERSTORMS HAS DEVELOPED OVER
THE PAST COUPLE HOURS ACROSS EASTERN IOWA. THIS ACTIVITY IS FIRING
JUST AHEAD OF A SURFACE COLD FRONT IN AN AREA OF INCREASED ASCENT
AHEAD OF A RATHER STOUT MID LEVEL SHORT WAVE...CURRENTLY NOTED IN
THE WATER VAPOR IMAGERY MOVING EASTWARD ACROSS SOUTHEASTERN IOWA. THE
00 UTC SOUNDING OUT OF KDVN INDICATES THAT THE AIRMASS IN WHICH THIS
ACTIVITY IS DEVELOPING IN POSSES DECENT MID LEVEL LAPSE RATES.
HOWEVER...OVERALL INSTABILITY IS RATHER LACK LUSTER...WITH MUCAPE
VALUES ONLY UP TO AROUND 100 J/KG. IN SPITE OF THIS...THE STRONGER
FORCING FOR ASCENT COMPLEMENTS OF THE MID LEVEL WAVE AND MOISTURE
CONVERGENCE IN THE LOWER LEVELS...IS ABLE TO TAKE ADVANTAGE OF THE
STEEP LAPSE RATES TO RESULT IN THUNDERSTORMS. THIS ACTIVITY WILL
LIKELY MAINTAIN ITSELF FOR THE NEXT FEW HOURS AS IT PUSHES EASTWARD
ACROSS NORTHERN ILLINOIS. THERE COULD EVEN BE SOME SMALL HAIL AND
SOME GUSTY WINDS IN SOME OF THE STRONGEST STORMS GIVEN THE DRIER AIR
IN THE LOWEST FEW THOUSAND FEET. THIS ACTIVITY SHOULD END OVERNIGHT
WITH WINDS BECOMING WESTERLY IN THE WAKE OF THE FRONTAL PASSAGE.
KJB
//PREV DISCUSSION...
259 PM CDT
THERE ARE NUMEROUS CHALLENGES WITH THE FORECAST AS THE PATTERN
TRANSITIONS TO A MORE ACTIVE ONE...BEGINNING WITH SHOWERS AND
SOME SPORADIC THUNDER THIS EVENING AND THEN CARRYING THROUGH THE
MIDDLE OF NEXT WEEK. IN ADDITION...THE LIKELY LOCATION OF THE
AREA RELATIVE TO SYNOPTIC FEATURES WILL ALLOW FOR TEMPERATURES TO
BE HEAVILY DEPENDENT ON CLOUD COVER AND RAIN...ALONG WITH LAKE
INDUCED COOLING AT LEAST A FEW OF THE UPCOMING SEVERAL DAYS.
NEAR TERM INTO TONIGHT...A FAST PACED BUT MORE AMPLIFIED UPPER
LEVEL PATTERN IS ESTABLISHED OVER THE CENTRAL U.S. THIS AFTERNOON
WITH A WELL-DEFINED UPPER WAVE ON WATER VAPOR ADVANCING EASTWARD
FROM WESTERN IA. A 1000 MB SURFACE LOW REFLECTION ACROSS SOUTHERN
MN HAS DEVELOPED AND HELPED TO ESTABLISH STRONG RETURN FLOW WITH
WIND GUSTS TO 40 TO 45 MPH AT SEVERAL SITES. THESE WINDS SHOULD
DIMINISH GRADUALLY THROUGH THE EVENING HOURS.
MOISTURE RETURN HAS STRUGGLED HOWEVER...BOTH AT THE SURFACE AND IN
THE DEEP LAYER PER OBSERVATIONS AND PWAT ANALYSIS AND IS A REASON
SHOWER COVERAGE IS LIKELY TO BE MORE LIMITED THAN IT COULD BE
GIVEN THE UPPER FORCING AHEAD OF THIS WAVE...AND IT WILL TAKE SOME
TIME FOR THE VERY DRY LOWER ATMOSPHERE TO SATURATE. A NARROW
CORRIDOR OF 700-900 MB MOISTURE TRANSPORT ALONG A MID-LEVEL JET
HAS STILL HELPED TO INCREASE ECHOES UPSTREAM DURING THE FIRST HALF
OF THE AFTERNOON AND THIS WILL LIKELY BE JUST ENOUGH TO CONTINUE
DOING SUCH WITH STEEPENING MID-LEVEL LAPSE RATES IN CONCERT WITH
THE NARROW MOISTURE CONVERGENCE. MOST OF THE HIGH-RES CONVECTIVE
ALLOWING MODELS PREDICT AN INCREASE IN CONVECTIVE-TYPE ECHOES
ACROSS NORTH CENTRAL IL BETWEEN 23Z AND 03Z SHIFTING EASTWARD AND
FADING SLOWLY THROUGH EARLY OVERNIGHT AS THE FRONT SHIFTS EAST.
WITH SEVERAL OF THESE GUIDANCE MEMBERS INDICATING HIGHER
REFLECTIVITY AND A NARROW CORRIDOR OF 200-400 J/KG OF MUCAPE PER
THE RAP ALONG THE FRONT...WOULD EXPECT A FEW STORMS WITHIN THE
GENERAL SHOWERS. HAVE ADAPTED HOURLY POPS THROUGH THIS EVENING
PERIOD OF THE FORECAST. AS PREVIOUS FORECAST DID KEEP MOST OF
TONIGHTS TEMPERATURE DROP AFTER THE FRONTAL PASSAGE FROM WEST TO
EAST.
SUNDAY...HIGH PRESSURE STILL LOOKS TO BRIEFLY PREVAIL FOR THIS
PERIOD. THE MOST NOTEWORTHY ASPECT ABOUT THIS IS IT LOOKS TO LINE
UP DOWN THE AXIS OF LAKE MICHIGAN BY MIDDAY AND ALLOW FOR A FAIRLY
STOUT LAKE BREEZE. THIS WILL BE AIDED BY THE FACT THAT
TEMPERATURES SHOULD MODERATE NICELY ON SUNDAY OVER LAND DUE TO
ONLY A SMALL WINDOW OF COLD AIR ADVECTION BEHIND THE FRONT TONIGHT
AND A DRY AIR MASS AND PREDICTED SUNSHINE DURING SUNDAY. THE
TEMPERATURE AND PRESSURE DIFFERENCES WITHIN A LIGHT WIND FIELD
SHOULD DRIVE A STRONG LAKE BREEZE...AND THE AFTERNOON TEMPERATURE
DROP FOR DOWNTOWN CHICAGO AND OTHER NEAR LAKE AREAS MAY BE AS MUCH
AS 15 DEGREES.
SUNDAY NIGHT AND MONDAY...AN ACTIVE WEST-TO-EAST PACIFIC JET OVER
120 KT AS SEEN ON HEMISPHERIC WATER VAPOR TODAY WILL DIG ITS WAY
INTO THE WESTERN U.S. WITH TROUGH DEVELOPMENT AND UPSTREAM
SOUTHWEST FLOW OVER THE MIDWEST. A LEAD IMPULSE IN THIS FLOW IS
WELL PREDICTED ON GUIDANCE TO PASS OVER THE AREA DURING LATE
SUNDAY NIGHT INTO MONDAY MORNING. THIS LOOKS TO TIGHTEN AN UPPER
LEVEL WARM FRONT AND ALLOW FOR SATURATED ISENTROPIC LIFT FOR RAIN
SHOWERS. ELEVATED INSTABILITY DOES INCREASE AS THE WARM NOSE
BUILDS IN WITHIN THE LOWER LEVELS...AND START THUNDER IN THIS
FORECAST PERIOD ITS TOO TOUGH TO DISCERN A PERIOD WHERE THERE
WOULD NOT BE A THUNDER CHANCE ALL THE WAY THROUGH WEDNESDAY NIGHT.
IN THE WAKE OF THIS LEAD IMPULSE HEIGHTS LOOK TO BUILD ON MONDAY
AS THE PRIMARY TROUGH DEVELOPS. ITS A LITTLE INTERESTING AS THERE
SHOULD BE A SURFACE WARM FRONT...POSSIBLY DIABATICALLY
ENHANCED...LAID OUT SOMEWHERE IN THE CENTRAL IL TO NORTHERN IL
REGION. THE ONLY THING IS WITH SHORT WAVE RIDGING HINTED AT THIS
FEATURE APPEARS TO BE FAIRLY BENIGN...BUT SOMETHING TO KEEP AN
EYE ON.
MIDWEEK...AN ACTIVE PERIOD HERE AS PROLONGED SURFACE CYCLOGENESIS
BEGINS OVER THE SOUTHERN PLAINS MONDAY NIGHT AND CONTINUES THROUGH
TUESDAY WITH THE SURFACE WAVE ADVANCING ENE ON WED. MODEL
GUIDANCE HAS COME INTO BETTER AGREEMENT WITH THIS...LATCHING MORE
ONTO AN EC SOUTHERN SOLUTION. HAVE CONTINUED TO LEAN THAT WAY WITH
THE FORECAST WHICH MEANS INHIBITING TEMPERATURES ON WHAT COULD BE
GIVEN 850MB TEMPERATURES CLIMBING TO 8C-12C...ESPECIALLY NORTH OF
I-80. WITH FLOW OFF THE LAKE TUESDAY AND WEDNESDAY DUE TO THE LOW
BEING SOUTHWEST OF THE AREA...TEMPERATURES NEAR THE LAKE WILL
REMAIN COOLER. ALSO THIS FORECAST PATTERN MEANS LIKELY SEVERAL
BOUTS OF PRECIP WITH THE PROXIMITY OF THE ELEVATED WARM/STATIONARY
FRONT. THE 06.12 GFS AND EC RUNS BOTH HAVE OVER TWO AND A HALF
INCHES OF RAIN FORECAST AREA WIDE FROM SUNDAY NIGHT THROUGH
THURSDAY. WHILE IT IS CHALLENGING TO FOCUS ANY WINDOW FOR
CATEGORICAL POPS...IT WOULD SEEM WEDNESDAY AND WEDNESDAY NIGHT
WOULD BE THE MOST FAVORED PERIODS FOR STRONGER DYNAMIC FORCING AND
POSSIBLY MORE ROBUST ELEVATED CONVECTION WITH THE LARGE SCALE
UPPER TROUGH MOVING EASTWARD. COOLING BEHIND THE FRONT LOOKS
SOMEWHAT STRONG AND THERE IS A POTENTIAL TO SEE SOME MIX IN THE
WAKE OF THE FRONT...BUT CONFIDENCE IS VERY LOW ON HOW THIS SYSTEM
WILL EVOLVE AS IT LIFTS OUT.
BEYOND...HAVE GONE PRIMARILY WITH A MODEL CONSENSUS AT THE END OF
NEXT WEEK AS THE UPPER FLOW PATTERN WORKS FROM BRIEFLY NORTHWEST
BACK TO WEST. TEMPERATURES SHOULD GRADUALLY MODERATE BUT
CONFIDENCE IS LOW ON PRECIP CHANCES AS THE PATTERN STILL LOOKS
DISTURBED.
MTF
&&
.FIRE WEATHER...
328 AM...EASTERLY FLOW HAS MAINTAINED MUCH DRIER AIR ACROSS THE
REGION AND EXPECT A SLOW RETURN OF LOW LEVEL MOISTURE ACROSS THE
AREA TODAY. IT APPEARS DEWPOINTS WILL INCREASE BACK INTO THE
40S...BUT PROBABLY NOT UNTIL LATE AFTERNOON ACROSS WESTERN IL AND
THE REST OF THE AREA THIS EVENING. THUS MINIMUM RH VALUES TODAY
WILL LIKELY BE IN THE 35-40 PERCENT RANGE AND COULD POSSIBLY DIP
INTO THE 30-35 PERCENT RANGE. WHILE THESE EXPECTED VALUES WILL
REMAIN ABOVE RED FLAG CRITERIA OF 25 PERCENT...SOUTHERLY WINDS ARE
EXPECTED TO QUICKLY INCREASE THIS MORNING WITH GUSTS AS HIGH AS 40
MPH FROM LATE MORNING THROUGH SUNSET WITH THE POTENTIAL FOR HIGHER
GUSTS. WHILE THERE COULD BE A FEW LIGHT SHOWERS OR SPRINKLES
TODAY...THE BEST TIMING FOR SHOWERS AND A FEW THUNDERSTORMS WILL
BE FROM LATE AFTERNOON THROUGH MID/LATE EVENING. TEN HOUR FUEL
MOISTURE DIPPED TO 8-9 PERCENT ON FRIDAY AND SIMILAR VALUES ARE
POSSIBLE TODAY. AS A RESULT...THERE WILL BE AN INCREASED FIRE
DANGER AND WHILE MEETING RED FLAG CRITERIA IS NOT EXPECTED...
CONDITIONS WILL NEED TO BE MONITORED THROUGH DAY. CMS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* MVFR CIGS OVERNIGHT INTO SUNDAY MORNING
* WIND SHIFT TO EASTERLY SUNDAY AFTERNOON
IZZI
//DISCUSSION...UPDATED 06Z...
COLD FRONT MOVING THROUGH THE REGION AT THIS TIME WITH SHRA/TSRA
MOVING EAST OF THE REGION. EXPANDING BANK OF STRATUS HAS BEEN
NOTED ON SATELLITE IMAGERY UPSTREAM OVER WI/IA INTO NW IL WITH
GUIDANCE SUGGESTING THIS SHOULD CONTINUE TO EXPAND EAST INTO THE
TERMINALS OVERNIGHT. DOES APPEAR THAT MIXING/HEATING SHOULD HELP
ERODE THE STRATUS SUNDAY MORNING...THOUGH TIMING OF SCATTERING OUT
CIGS IS UNCERTAIN. WESTERLY WINDS SHOULD GUST OCCASIONALLY TO
15-20KT OVERNIGHT BEFORE EASING SUNDAY MORNING. PRESSURE FALLS
OVER THE PLAINS EXPECTED TO RESULT IN AN ABRUPT SHIFT TO EASTERLY
WINDS SUNDAY EVENING...WITH THE TIMING OF THAT WIND SHIFT LIKELY A
BIT EARLIER AT ORD/MDW/GYY AS COLLAPSING GRADIENT IN THE AFTERNOON
SHOULD ALLOW FOR ROBUST LAKE BREEZE DEVELOPMENT. NEXT DISTURBANCE
LIKELY TO APPROACH THE REGION TOWARD THE END OF OR JUST BEYOND
THE ORD 30 TAF HOUR PERIOD WITH ADDITIONAL SHRA/TSRA EXPECTED AT
THAT TIME.
IZZI
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM-HIGH CONFIDENCE IN LOW END MVFR CIGS OVERNIGHT INTO SUN
AM
* LOW-MEDIUM CONFIDENCE ON TIMING OF IMPROVEMENT TO VFR SUNDAY
MORNING
* HIGH CONFIDENCE ON WIND SHIFT TO EAST SUN PM
IZZI
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY...SHRA/TSRA LIKELY EARLY. MVFR/BRIEF IFR POSSIBLE EARLY.
TUESDAY THROUGH THURSDAY NIGHT...PERIODIC CHANCE FOR SHRA/TSRA.
PERIODIC MVFR CIGS/VSBY LIKELY WITH BRIEF IFR POSSIBLE.
FRIDAY...PROBABLE VFR.
MDB
&&
.MARINE...
241 PM CDT
LOW PRESSURE OVER SOUTHERN MINNESOTA THIS AFTERNOON IS LIFTING A
STRONG WARM FRONT ACROSS LAKE MICHIGAN TODAY. WINDS OVER THE LAND
ARE TOPPING OUT AROUND 35 KT THIS AFTERNOON WITH THESE GALES
EXTENDING INTO THE NEARSHORE WATERS WHERE A GALE WARNING REMAINS
IN EFFECT THROUGH THIS EVENING. HOWEVER...WITH TEMPERATURES
PUSHING 70 ACROSS NORTHERN ILLINOIS/INDIANA...VERY STABLE
CONDITIONS ARE SETTING UP OVER THE OPEN WATERS OF THE LAKE AND
SHOULD BE INHIBITING THE STRONGER GUSTS FROM REACHING THE LAKE
SURFACE. THE LOW WILL MOVE ACROSS NORTHERN LAKE MICHIGAN LATE
THIS EVENING WITH A TRAILING COLD FRONT PUSHING ACROSS THE LAKE
SHORTLY THEREAFTER WITH WINDS TURNING WESTERLY AND DIMINISHING.
ANOTHER LOW PRESSURE SYSTEM IS FORECAST TO MOVE INTO THE REGION
MIDWEEK...THOUGH MODELS CONTINUE TO STRUGGLE WITH TRACK AND TIMING
MAKING IT DIFFICULT TO PIN DOWN DETAILS REGARDING OVER THE LAKE.
CONTINUE TO FAVOR A FARTHER SOUTH SOLUTION SUPPORTED BY THE
CONSISTENT ECMWF...WHICH THE LATEST GFS HAS TRENDED TOWARDS.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 4 AM SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1154 PM CDT SAT APR 6 2013
.DISCUSSION...
ISSUED 900 PM CDT SAT APR 6 2013
A LINE OF SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE TO
PROGRESS EASTWARD ACROSS THE NORTHERN HALF OF THE CWA THIS EVENING
AHEAD OF A COLD FRONT. THE WINDOW OF OPPORTUNITY FOR THUNDER LOOKS
TO BE AROUND 2 HOURS WITH THUNDER JUST REPORTED IN PIA AHEAD OF
THE STRONGER LINE BACK NEAR GALESBURG. THE LOW LEVEL CONVERGENCE
AND INSTABILITY LOOKS TO BE GRADUALLY WEAKENING AFTER SUNSET...AND
THE FRONTAL CIRCULATIONS ARE FORECAST TO NEARLY DISSIPATE BY 12Z
WHEN THE FRONT REACHES OUR SOUTHEAST COUNTIES. WE MAINLY KEPT THE
HIGH CHANCE POPS ACROSS THE NORTH...AND PROGRESSED THEM TOWARD
CHAMPAIGN BY 06Z/1AM WITH ONLY SLIGHT CHANCE POPS IN THE SOUTHEAST
THIRD OF OUR COUNTIES AFTER 06Z/1AM.
THE GUSTY WINDS ARE MAINLY CONFINED TO AREAS EAST OF LINCOLN TO
BLOOMINGTON AT 9 PM. LIGHTER WINDS WILL ARRIVE WITH THE COLD FRONT
AND A WIND SHIFT TO THE WEST.
THE FRONT IS STILL EXPECTED TO RETURN NORTH AND BECOME ACTIVE
AGAIN SUNDAY AFTERNOON AND ESPECIALLY SUNDAY NIGHT IN THE WEST.
FOR TONIGHT...UPDATED THE POP/WEATHER AND WINDS TO MORE CLOSELY
MATCH CURRENT TRENDS. NO MAJOR CHANCES OVERALL. UPDATED INFO WILL
BE AVAILABLE SHORTLY.
SHIMON
&&
.AVIATION...
ISSUED 1154 PM CDT SAT APR 6 2013...FOR THE 06Z TAFS
SOME SHOWERS MAY AFFECT CMI FOR THE FIRST HALF HOUR OF THE TAF
PERIOD...OTHERWISE THE TERMINAL SITES SHOULD REMAIN DRY OVER
THE NEXT 24 HOURS.
THE COLD FRONT WILL PASS ACROSS DEC/CMI OVER THE NEXT HOUR OR
TWO...SO WINDS SHOULD DIMINISH FROM STRONG SOUTH TO LIGHTER
SOUTHWEST AROUND 12-14KT. LATER TONIGHT ALL TAF SITES SHOULD SEE
WEST WINDS AROUND 10KT.
SOME MVFR CLOUDS ARE EXPECTED TO APPROACH OUR NORTHERN
COUNTIES...WITH PIA AND BMI POSSIBLY SEEING SOME OF THAT. LIGHT
FOG MAY EVEN AFFECT PIA AND BMI. I ADDED A TEMPO FOR BKN015 FOR
12Z TO 15Z TO MATCH THE HRRR OUTPUT FOR THAT TIME FRAME.
SHIMON
&&
.PREV DISCUSSION...
ISSUED 300 PM CDT SAT APR 6 2013
00Z MODELS CONTINUE A MILD AND UNSETTLED WEATHER PATTERN THROUGH
MID WEEK WITH COOLER AND DRIER CONDITIONS THE END OF NEXT WEEK.
WILL USE A MODEL BLEND THIS FORECAST PACKAGE. MET AND MAV GUIDANCE
TEMPS ARE SIMILAR THROUGH MON NIGHT AND STAYED FAIRLY CLOSE TO.
SHORT TERM...TODAY THROUGH TUESDAY NIGHT
STRONG SOUTH WINDS OF 20-35 MPH AND GUSTS OF 35-50 MPH THIS
AFTERNOON WITH STRONGEST WIND GUSTS FROM I-72 NORTH. A SPECIAL
WEATHER STATEMENT WAS ISSUED TO ADDRESS THESE HIGH WINDS THROUGH
8 PM. 999 MB LOW PRESSURE OVER SOUTHCENTRAL MN HAS A COLD FRONT
INTO CENTRAL IA...NW MO AND CENTRAL OK. WARM FRONT HAD LIFTED NE
OF IL WITH MILD TEMPS IN THE UPPER 60S AND LOWER 70S OVER CENTRAL
AND SE IL AND MILDEST TEMPS SINCE NOV 10TH.
LOW PRESSURE TO MOVE TOWARD NORTHERN LAKE MI BY 06Z TONIGHT AND
PULL COLD FRONT TOWARD I-55. LOW PRESSURE DEEPENS TO 996 MB JUST
EAST OF UPPER MI BY 12Z/SUN AND COLD FRONT SWEEPS THROUGH SE IL
LATE TONIGHT INTO MID MORNING SUNDAY. HAVE CHANCE OF SHOWERS AND
ISOLATED THUNDERSTORMS OVER CENTRAL IL THIS EVENING AND SHIFTING
INTO SE IL OVERNIGHT INTO MID MORNING SUNDAY. LIMITED MOISTURE
WITH COLD FRONT AND MODELS HAVE TRENDED LOWER WITH QPF AMOUNTS
TONIGHT INTO SUNDAY. LOWS TONIGHT RANGE FROM THE LOWER 40S NW OF
THE IL RIVER TO THE LOWER 50S IN SE IL.
FRONTAL BOUNDARY TO START LIFTING BACK NORTH TOWARD CENTRAL/SE IL
BY SUNSET SUNDAY AND RETURNING 20-40% CHANCE OF SHOWERS AND
ISOLATED THUNDERSTORMS LATE SUNDAY AFTERNOON INTO PARTS OF CENTRAL
AND SW IL. HIGHS TO RANGE FROM THE MID 60S NORTH OF PEORIA TO THE
LOWER 70S SOUTH OF I-72. WARM FRONT LIFTS NORTH THROUGH CENTRAL IL
SUNDAY NIGHT AND INTO NORTHERN IL MON AND LIKELY ACCOMPANIED BY A
SHOWERS AND A CHANCE OF THUNDERSTORMS ESPECIALLY NORTH OF I-70.
MILD HIGHS MON AGAIN IN THE UPPER 60S AND LOWER 70S WITH COOLEST
READINGS FROM I-74 NORTH.
CHANCES OF SHOWERS AND THUNDERSTORMS LINGERS TUE AND HIGHEST POPS
IN NORTHERN AREAS CLOSER TO FRONTAL BOUNDARY LINGERING OVER
NORTHERN IL.
LONG TERM...WEDNESDAY THROUGH SATURDAY
STRONG LOW PRESSURE TO EJECT NE AROUND WED WITH BEST CHANCES OF
SHOWERS AND THUNDERSTORMS AND SPC HAS RISK OF STRONG TO SEVERE
STORMS OVER SOUTHERN IL WED. GFS IS QUICKER WITH THIS STORM SYSTEM
THAN THE ECMWF MODEL AND USED A BLEND FOR NOW WITH PLENTY OF TIME TO
SORT OUT THE TIMING DIFFERENCES. MAY BE A GRADIENT OF TEMPS WED WITH
COOLER HIGHS IN THE UPPER 50S NW OF THE IL RIVER AND MILDER LOWER
70S SE OF I-70. STRONG UPPER LEVEL TROF OVER THE MIDWEST THU TO KEEP
LOW CLOUDS AROUND ALONG WITH LINGERING CHANCES OF SHOWERS AND COOLER
TEMPS. DRIER WEATHER EXPECTED FRIDAY ALONG WITH TEMPS BEING A BIT
COOLER THAN NORMAL THU/FRI WITH HIGHS IN THE 50S.
07
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
447 AM CDT SUN APR 7 2013
.SHORT TERM...(TODAY)
ISSUED AT 442 AM CDT SUN APR 7 2013
TODAY...DEEPER MOISTURE ALONG EXTENDING FROM SOUTHERN OK AND EAST TX
WILL BE ADVECTED NORTHWARD AS A LEE SURFACE TROUGH DEEPENS ACROSS
THE CENTRAL AND WESTERN HIGH PLAINS. THE SOUTHERLY LOW-LEVEL FLOW
WILL ADVECT THIS DEEPER MOISTURE NORTHWARD ACROSS EASTERN KS LATE
THIS AFTERNOON.
THE WESTERN GULF OF MEXICO IS NOT AT EQUILIBRIUM EARLY THIS
MORNING...BUT THE RESIDUAL MOISTURE RETURN SHOULD BE SUFFICIENT TO
ALLOW MID TO UPPER 50 DEWPOINTS TO ADVECT NORTHWARD ACROSS THE CWA
BY LATER AFTERNOON.
MEANWHILE...A SHORTWAVE LENGTH H5 TROUGH WAS MOVING EASTWARD ACROSS
CENTRAL CO...SOUTHWARD INTO NORTHWEST NM. THE NAM...ECMWF AND GFS
SHOW THIS H5 TROUGH MOVING EAST ACROSS WESTERN AND CENTRAL KS TODAY.
STRONGER ASCENT AHEAD OF THIS H5 TROUGH AND THE STRONGER ISENTROPIC
LIFT ON THE NORTH SIDE OF DEEPER MOISTURE RETURN WILL ALLOW
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS TO DEVELOP FROM
SOUTH TO NORTH ACROSS THE CWA DURING THE MID AND LATE AFTERNOON
HOURS.
THE VERTICAL WINDSHEAR LOOKS TO BE STRONG WITH 0-6KM SHEAR OF 40 TO
60 KTS ACROSS THE CWA THROUGH THE LATE AFTERNOON HOURS. INSTABILITY
WILL INCREASE THROUGH THE AFTERNOON AS THE DEEPER MOISTURE ADVECTS
NORTHWARD TO AT LEAST I-70. GIVEN STEEP LAPSE RATES FROM 700MB TO
THE SURFACE...ONCE THE DEEPER MOISTURE ADVECT FAR ENOUGH NORTH WE
SHOULD SEE SBCAPE INCREASE TO 1,000 TO 1,500 J/KG FROM I-70 SOUTH.
THE NAM MODEL EVEN SHOWS AN ENHANCED BAND OF 0-1KM SRH OF 80-100
J/KG ALONG THE I-35 CORRIDOR BY 21Z AND LIFTING NORTHWARD TO I-70 BY
00Z. THIS WOULD BE SUFFICIENT FOR DISCRETE SUPERCELL TO POTENTIALLY
PRODUCE ISOLATED TORNADOES. HOWEVER...THE MODE OF CONVECTION IS
STILL IN QUESTION. THE ECMWF...GFS...AND NAM ALL SHOW NUMEROUS
THUNDERSTORMS DEVELOPING ALONG I-35 AFTER 21Z AND EXTENDING WESTWARD
TOWARDS ICT. IF A COMPLEX OR CLUSTER OF THUNDERSTORMS DEVELOPS LATE
IN THE AFTERNOON HOURS ALONG THE NORTHERN EDGE OF DEEPER MOISTURE
RETURN...THEN THE PRIMARY THREAT WILL LARGE HAIL AND SEVERE WIND
GUSTS. THIS COMPLEX OF STORMS WILL DEVELOP NORTHWARD ACROSS EAST
CENTRAL KS LATE IN THE AFTERNOON. IF THE THUNDERSTORMS REMAIN
DISCRETE...THEN GIVEN THE 0-1KM SRH AND INSTABILITY...THEN ISOLATED
TORNADOES COULD NOT BE RULED OUT FOR PORTIONS OF THE CWA...SOUTH OF
I-70. THE RAP AND (ARW) WRF...TWO OF OUR MESOSCALE MODELS...SHOW THE
INITIATION OF DEEP MOIST CONVECTION WEST AND SOUTHWEST OF THE CWA
THROUGH THE LATE AFTERNOON HOURS. THE INITIAL MODE LOOKS DISCRETE
WITH STORM MERGERS OCCURING AS THEY MOVE NORTHEAST ACROSS THE CWA
DURING THE EARLY EVENING HOURS. STAY TUNED TO LATER UPDATES ON THE
POTENTIAL FOR SEVERE WEATHER LATE THIS AFTERNOON AND EVENING.
TEMPERATURES WILL WARM INTO THE LOWER TO MID 70S WITH PATCHES OF
DENSE HIGH CLOUD COVER SPREADING ACROSS THE CWA THIS MORNING. CU
SHOULD BEGIN TO DEVELOP AS THE DEEPER MOISTURE SURGES NORTHWARD THIS
AFTERNOON.
GARGAN
.LONG TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 442 AM CDT SUN APR 7 2013
CONVECTIVE COMPLEX OF SHOWERS AND THUNDERSTORMS WILL CONTINUE TO
DEVELOP/EXPAND EAST AND NORTHEAST ACROSS PRIMARILY THE SOUTHEAST
HALF OF THE CWA THROUGH THE EARLY AND MID EVENING HOURS WITH A
THREAT FOR PRIMARILY LARGE HAIL WITH THE STRONGER STORMS.
HOWEVER...AS THE SHORTWAVE TROUGH MOVES THROUGH BY LATE
EVENING...THE LLVL FLOW WILL BEGIN TO VEER AND ALLOW FOR SOME DRIER
AIR TO ADVECT EASTWARD WHICH WILL FAVOR THE MORE EASTWARD
PROGRESSION OF THE POSSIBLE MCS. HAVE THEREFORE TRENDED THE HIGHER
POPS THROUGH THE EARLY/MID EVENING...THEN A GRADUAL DECREASED POP
THROUGH LATE EVENING/MIDNIGHT...THEN A MUCH MORE RAPID DROP IN POPS
AFTER MIDNIGHT WEST TO EAST ACROSS THE CWA. WILL KEEP THE SOUTHEAST
CWA WARMER WITH THE CLOUDS AND HIGHER DEWPOINTS IN THE UPPER 50S
WITH NEAR 50 IN THE FAR NORTH CENTRAL.
ON MONDAY...OVERALL LACK OF LARGE SCALE ASCENT/FORCING WITHIN AN
ENVIRONMENT EXHIBITING A RAPIDLY STRENGTHENING ELEVATED MIXED LAYER
(EML) DOES NOT INCREASE CONFIDENCE IN CARRYING POPS BEYOND LOW END
CHANCE CATEGORY. HAVE REMOVED POPS FOR MOST OF THE MORNING...BUT
CARRIED LOW POPS IN THE LATE MORNING/AFTERNOON...ALTHOUGH IMPRESSIVE
INHIBITION MAY WARRANT LOWERING/OR REMOVING POPS MORE. KEPT HIGHS IN
THE LOW TO MID 70S DUE TO EXPECTED STRATUS DECK BENEATH
INVERSION.
BY MONDAY NIGHT...MORE CONVECTION IS EXPECTED TO ADVANCE/DEVELOP
EASTWARD FROM WESTERN/CENTRAL KANSAS THROUGH THE NIGHT PRIMARILY
ALONG THE NORTH OF THE WARM FRONT AS LLVL JET INCREASES THROUGH THE
NIGHT. THE FOCUS FOR THIS HAS CONTINUES TO TREND NORTHWARD WITH
TIME AND STRONG CAPPING OVER THE CWA MAY ALSO INHIBIT THE SOUTH AND
EASTWARD EXTENT OF THE CONVECTION AS WELL. FOR NOW...HAVE KEPT
LIKELY POPS ACROSS THE NORTHERN 2/3 OF THE CWA...BUT IF MODEL TRENDS
CONTINUE...THE HIGHER POPS MAY NEED TO BE TRIMMED/SHIFTED MORE
NORTHWARD CLOSER TO THE NE BORDER.
TUESDAY AND TUESDAY NIGHT STILL APPEARS TO BE THE MOST ACTIVE
TIMEFRAME FOR THIS STORM SYSTEM ACROSS OUR CWA AS A DEEPENING SFC
LOW/COLD FRONT ADVANCES EASTWARD ACROSS THE AREA AS THE MAIN
SHORTWAVE ROTATES NORTHEAST OUT OF THE LONGER WAVE TROUGH IN THE
WEST INTO THE NORTHERN PLAINS EARLY WEDNESDAY. CONVECTION COULD
FIRST INITIATE OVER CENTRAL KS THEN CONGEAL INTO A POSSIBLE SQUALL
LINE AS IT MOVES EAST THROUGH THE AFTERNOON/EVENING WITH ALL MODES
OF SEVERE WEATHER POSSIBLE DURING THIS TIME FRAME BEFORE THE FRONT
USHERS IN COOLER AND DRIER AIR INTO EASTERN KS LATE IN THE NIGHT.
WILL KEEP A LINGERING CHANCE FOR DECREASING CONVECTION/RAIN
POTENTIAL ON WEDNESDAY WITH SHOWERS EXITING THE CWA WEDNESDAY
NIGHT...THEN DRY THURSDAY INTO FRIDAY NIGHT. A SLIGHT CHANCE FOR
SHOWERS WILL RETURN BY SATURDAY. AFTER HIGHS IN THE 60S/70S ON
TUESDAY...WEDNESDAY TEMPS WILL COOL INTO THE 40S AND 50S FOR
WEDNESDAY AND THURSDAY...THEN THE 50S FRIDAY AND THE 60S FOR
SATURDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1212 AM CDT SUN APR 7 2013
FOR THE 06Z TAFS...WINDS HAVE BECOME LIGHT AND VARIABLE ACROSS THE
AREA THIS EVENING AND WILL REMAIN LIGHT THROUGH AROUND SUNRISE.
WINDS ARE EXPECTED TO INCREASE OUT OF THE SOUTH-SOUTHEAST LATER THIS
MORNING WITH INCREASING MID-LEVEL CLOUDS THROUGH THE DAY AS A LOW
PRESSURE SYSTEM APPROACHES THE AREA. COULD SEE SOME SHOWERS AND
THUNDERSTORMS DEVELOP OVER THE AREA DURING THE EVENING HOURS...WHICH
COULD LOWER CIGS/VIS TO MVFR CONDITIONS AND POSSIBLY LOWER. THERE IS
STILL UNCERTAINTY IN THE TIMING AND SCALE OF THIS
SHOWER/THUNDERSTORM ACTIVITY...SO WILL LIKELY NEED TO FINE TUNE THE
TIMING WITH FUTURE TAF UPDATES. AT THIS TIME THOUGH...MOST OF THE
ACTIVITY LOOKS TO BE MOVING EAST OF THE AREA BY AROUND 06Z.
ACH
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GARGAN
LONG TERM...63
AVIATION...HENNECKE
AREA FORECAST DISCUSSION
NWS JACKSON KY
130 AM EDT SUN APR 7 2013
.UPDATE...
ISSUED AT 130 AM EDT SUN APR 7 2013
LATEST HRRR SHOWS A MUCH SLOWER PROGRESSION OF THE FRONTAL BOUNDARY
TOWARDS OUR AREA TOMORROW AND PENETRATING MUCH LESS INTO THE AREA.
THUS...HAVE TRIMMED BACK POPS ACROSS EAST CENTRAL KENTUCKY. A LITTLE
CONCERNED EARLIER BY THE AMOUNT OF DRY AIR STILL PRESENT ACROSS
EASTERN KENTUCKY WITH DEWPOINTS STILL HOLDING IN THE LOWER TO MIDDLE
30S IN MANY LOCATIONS. HAVE GONE AHEAD AND LOWERED DEWPOINTS THROUGH
THE DAY TODAY...ESPECIALLY ACROSS THE SOUTHEAST. MODELS APPEAR TO BE
TOO AGGRESSIVE WITH THE MOISTURE RECOVERY ONCE AGAIN.
FORTUNATELY...EVEN USING A WORST CASE SCENARIO...I CANNOT GET
RELATIVE HUMIDITIES TO FALL UNDER 25 PERCENT...SO THAT PUTS RED FLAG
CRITERIA OUT OF THE PICTURE. HOWEVER...STILL GOING TO SEE THE
POTENTIAL FOR DANGEROUS FIRE WEATHER CONDITIONS TODAY WITH MUCH
GUSTIER SOUTHWEST WINDS DEVELOPING BY MID MORNING. PLAN TO HIGHLIGHT
THIS FIRE DANGER IN THE FIRE WEATHER PLANNING FORECAST AND IN THE
HWO.
UPDATE ISSUED AT 1042 PM EDT SAT APR 6 2013
MADE A FEW ADJUSTMENTS TO THE LOW TEMPERATURES TONIGHT. THE FAR
EASTERN SHELTERED VALLEYS ARE ON THEIR WAY DOWN...WITH A FEW SPOTS
ALREADY DIPPING TO BELOW 50 DEGREES. AT THIS PACE...A FEW UPPER 30S
STILL LOOK ACHIEVABLE. FURTHER WEST...TEMPERATURES HAVE BEEN SLOW TO
COOL OFF WITH PERSISTENT HIGH CLOUDS THROUGH EARLY THIS EVENING AS
WELL SOUTH TO SOUTH SOUTHEAST WINDS AT AROUND 5 KTS. THERE WILL BE A
DECENT CLEAR SLOT FOR SEVERAL HOURS...SO A DROP OFF STILL LOOKS
GOOD...HOWEVER DID TWEAK UP SOME OF THE LOWS IN THE WESTERN HALF OF
THE AREA GIVEN THE SLOW START.
UPDATE ISSUED AT 705 PM EDT SAT APR 6 2013
AN AREA OF THICKER HIGH CLOUDS IS CURRENTLY MOVING EAST ACROSS THE
AREA. THE BACK EDGE OF THESE THICKER CLOUDS WILL EXIT THE FAR EAST
BEFORE MIDNIGHT BASED ON THE LATEST SATELLITE TRENDS. WILL THEREFORE
MENTION MOSTLY CLOUDY WORDING EARLY ON FOR SOME LOCATIONS.
CONSEQUENTLY...WILL TWEAK THE DIURNAL DROP OFF...HOWEVER WILL STICK
WITH THE FORECAST LOWS FOR NOW.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 302 PM EDT SAT APR 6 2013
HIGH THIN CLOUDS WILL STREAM INTO THE AREA TONIGHT...BUT THIS SHOULD
NOT PREVENT ANOTHER FAIRLY SIGNIFICANT RIDGE VALLEY TEMPERATURE SPLIT
SETTING UP. THIS WILL BE DEPICTED IN THE FORECAST GRIDS WITH CLOSE
TO A 10 DEGREE SPREAD IN SOME AREAS...ESPECIALLY IN THE EAST. A COLD
FRONT WILL DROP SOUTH INTO OHIO AND INDIANA ON SUNDAY. THE 12Z NAM
AND GFS HAVE TRENDED TOWARDS THE PRECIPITATION CHANCES EXTENDING A
LITTLE FURTHER SOUTH...AND THIS IS REFLECTED IN THEIR CORRESPONDING
MOS GUIDANCE AS WELL. THIS IDEA IS ALSO SUPPORTED BY THE 09Z SREF BUT
NOT BY THE 12Z GEM OR 00Z ECMWF. IT STILL APPEARS THERE WILL BE A
FAIRLY STRONG GRADIENT OF PRECIPITATION CHANCES ON SUNDAY...AND WILL
CARRY AROUND 10 PERCENT IN THE FAR SOUTHEAST TO 40 TO 50 PERCENT IN
THE FAR NORTH. BEST INSTABILITY...WITH LI/S DROPPING BELOW ZERO WILL
BE IN THE NORTH...AND WILL CARRY ISOLATED THUNDERSTORMS IN THE NORTH
AND NORTHWEST PART OF THE FORECAST AREA. RAIN CHANCES WILL BE
DECREASING SUNDAY NIGHT...BUT WILL STILL WARRANT A MENTION ACROSS THE
NORTH AND WEST PART OF THE FORECAST AREA.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 302 PM EDT SAT APR 6 2013
THE MODELS ARE IN DECENT AGREEMENT WITH THE GENERAL PATTERN AS THEY
TRY TO TRANSITION AN UPPER LOW NEAR FOUR CORNERS INTO THE GREAT
PLAINS ON WEDNESDAY AND THEN INTO THE OHIO VALLEY AND THEN EITHER
INTO THE GREAT LAKES ON FRIDAY AS WITH THE GFS OR INTO THE DAKOTAS
AS FORECAST BY THE ECMWF. MANY OF THE SOLUTIONS FAVOR THE FASTER
GFS...HOWEVER THEY HAVE BEEN PLAGUED BY SOME RUN TO RUN
INCONSISTENCIES. THE FORECAST FAVORS THE SLOWER ECMWF FORECAST. WITH
THIS TYPE OF SYNOPTIC SITUATION...THE MODELS ARE CONSISTENTLY TOO
QUICK IN KICKING OUT THE LOW. CONFIDENCE THROUGH THURSDAY IS FAIRLY
HIGH BUT THEN DROPS STEEPLY FOR FRIDAY AND BEYOND DUE TO THE TIMING
ISSUES FROM THE FRONT.
SOME SHORT WAVES WILL BE MOVING THROUGH THE UPPER LOW AND AS THEY DO
THEY WILL GENERATE WAVES ON THE QUASI STATIONARY FRONT WHICH WILL
SET UP JUST TO THE NORTH OF THE AREA. THE EXACT LOCATION WHERE THIS
FRONT SETS UP COULD MAKE A BIG DIFFERENCE IN HOW FAR SOUTH THE FRONT
SAGS. THIS WILL CONSEQUENCES AS TO THE WEATHER EXPECTED IN THE
NORTHERN PORTION OF THE FORECAST AREA. THE SOUTHERN AREA SHOULD NOT
REALLY BE THAT AFFECTED UNTIL THE FRONT ACTUALLY STARTS MOVING
ACROSS THE AREA ON EITHER ON FRIDAY.
FOR TEMPERATURES...STAYED CLOSE TO THE MODEL BLEND...HOWEVER HAD TO
MAKE CHANGES TO THE LOWS DUE TO THE RIDGE VALLEY TEMPERATURE
DIFFERENCES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 130 AM EDT SUN APR 7 2013
VFR CONDITIONS WILL HOLD ON THROUGH THE PERIOD. AN INCREASING LOW
LEVEL JET ACROSS THE OHIO VALLEY WILL ALLOW FOR THE THREAT OF LOW
LEVEL WIND SHEAR THROUGH DAWN. AN APPROACHING COLD FRONT WILL MOVE
INTO SOUTHERN OHIO TODAY. SOME SCATTERED SHOWERS AND A FEW
THUNDERSTORMS ARE POSSIBLE...MAINLY NORTH OF THE MOUNTAIN PARKWAY.
LOWER CLOUDS AND PRECIPITATION WILL NOT LIKELY MAKE IT SOUTH OF
I-64...KEEPING THE TAF SITES DRY WITH JUST SOME HIGH CLOUDS TO
CONTEND WITH.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KAS
SHORT TERM...SBH
LONG TERM...JJ
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
415 AM EDT SUN APR 7 2013
.SYNOPSIS...
WE EXPECT MILD, SPRING WEATHER TODAY, WITH A CHANCE OF SHOWERS.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
TEMPERATURE TREND THIS MORNING A BIT WARMER THAN PREVIOUS FCST, SO
MADE THE SMALL ADJUSTMENT. ALSO ADJUSTED DEW POINTS WAY DOWN. HIGH
TEMPS ON LOWER SIDE OF GUIDANCE. KEPT SOME GUSTY WINDS IN AS WE EXPECT
SOME OF THE MODERATE WIND JUST ABOVE THE SURFACE TO MIX DOWN.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
MODEL CONSENSUS FAVORS A STALLING OF THE FRONT ACROSS NORTHERN
WEST VIRGINIA SUNDAY NIGHT BEFORE IT TURNS NORTHWARD AS A WARM
FRONT ON MONDAY. POPS FOR SHOWERS WERE CONTINUED THROUGH MONDAY
NIGHT BEFORE BEING INCREASED AGAIN ON TUESDAY. KEPT THUNDER
MONDAY AFTERNOON/EVENING AS THE HIGHER CAPE SUGGESTS.
WHILE AGREEMENT ON THE PLACEMENT OF THE FRONT BY TUESDAY BECOMES
LESS PRONOUNCED...THE ECMWF/GFS/NAM ALL LIKE THE IDEA OF TRACKING
A SHRTWV ALONG THE BNDRY BY THE AFTERNOON HOURS. THIS WOULD INCRS
LIFT AND SHEAR ALONG THE FRONTAL ZONE. THESE INGREDIENTS WITH SOME
WEAK INSTABILITY MAY BE SUFFICIENT TO OVERCOME A MODERATELY
STRONG CAP ALONG THE BOUNDARY. THUS...A MENTION OF THUNDERSTORMS
WAS ADDED.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
OVERALL...CONFIDENCE IN EXTENDED FORECAST IS LOWER THAN
NORMAL...SIMILAR TO YESTERDAY. FRONT WILL STILL BE HUNG UP TUESDAY
NIGHT THROUGH WEDNESDAY NIGHT...PROBABLY TO THE NORTH OF THE REGION.
ALTHOUGH COLD FRONT WILL LIKELY BEGIN TO CROSS THE REGION ON
THURSDAY...GFS/ECMWF CANNOT DECIDE WHETHER THE COLD FRONT WILL TAKE
24 OR 48 HOURS TO PUSH ALL THE WAY THROUGH. HAVE BUMPED UP POPS TO
LIKELY THURSDAY NIGHT...BUT OTHERWISE MADE LITTLE CHANGES TO POPS OR
TEMPERATURES.
&&
.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS WL CONTINUE THIS MRNG ALTHOUGH BROAD SWATH OF MID
LVL CLDINESS CONTS TO FLOW OVR THE UPR OH VALLEY REGION. THE ONLY
AVIATION CONCERN THIS MRNG WILL LOW LEVEL WIND SHEAR AS LLVL JET
SURGES TWD LOW PRES CROSSING THE GREAT LAKES.
THAT SYSTEM WL DRAG A WEAK FRONT ACRS AREA PORTS ON SUNDAY...GIVEN
THE INITIALLY PALTRY BNDRY LAYER MSTR SUPPLY AND EXPECTED EWD
PROGRESS OF THE SPPRTG SHRTWV...FORECAST WL FEATURE -SHRA WITH
HIGH BASED CIGS AND VEERED WIND...GUSTS OF WHICH MAY APPRCH 30 KT
SHOULD NAM AND RAP MOMENTUM TRANSFER PROGNOSIS BE REALIZED. CONFIDENCE
IN MORE SIGNIFICANT OR WIDESPREAD DETERIORATION IS NOT SUFFICIENT
TO WARRANT TAF MENTION JUST YET.
.OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/...
THE BOUNDARY SHOULD SHIFT SOUTH OF THE REGION TONIGHT...THEN BE
PULLED NORTHWARD ONCE AGAIN ON MONDAY AS LOW PRES DIGS ACRS THE
GREAT LAKES. FRONT POSITIONING IS QUESTIONABLE THROUGH MUCH OF THE
WEEK...SO OCCASIONAL RESTRICTIONS SHOULD BE ANTICIPATED.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
137 AM EDT SUN APR 7 2013
.SYNOPSIS...
RAIN CHANCES WILL INCREASE TODAY AS A COLD FRONT SLIDES OVER THE
REGION.
&&
.NEAR TERM /THROUGH TODAY/...
TEMPERATURE TREND OVERNIGHT A BIT WARMER THAN PREVIOUS FCST, SO
MADE THE SMALL ADJUSTMENT. MOISTURE IS LIMITED AND THUNDER AHEAD
OF FRONT ALMOST GONE, SO WE REMOVED MENTION OF IT TODAY. HIGH
TEMPS ON LOWER SIDE OF GUIDANCE. ALSO UPPED WINDS AND ATTENDING
GUSTS BECAUSE OF LOW DEW POINTS AT SURFACE AND MODERATE WINDS
JUST ABOVE.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY/...
MODEL CONSENSUS FAVORS A STALLING OF THE FRONT ACROSS NORTHERN
WEST VIRGINIA SUNDAY NIGHT BEFORE IT TURNS NORTHWARD AS A WARM
FRONT ON MONDAY. POPS FOR SHOWERS WERE CONTINUED THROUGH MONDAY
NIGHT BEFORE BEING INCREASED AGAIN ON TUESDAY. WE ADDED THUNDER
TO MONDAY AFTERNOON/EVENING AS THE HIGHER CAPE SUGGESTS.
WHILE AGREEMENT ON THE PLACEMENT OF THE FRONT BY TUESDAY BECOMES
LESS PRONOUNCED...THE ECMWF/GFS/NAM ALL LIKE THE IDEA OF TRACKING
A SHRTWV ALONG THE BNDRY BY THE AFTERNOON HOURS. THIS WOULD INCRS
LIFT AND SHEAR ALONG THE FRONTAL ZONE. THESE INGREDIENTS WITH SOME
WEAK INSTABILITY MAY BE SUFFICIENT TO OVERCOME A MODERATELY
STRONG CAP ALONG THE BOUNDARY. THUS...A MENTION OF THUNDERSTORMS
WAS ADDED.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
OVERALL...CONFIDENCE IN EXTENDED FORECAST IS LOWER THAN
NORMAL...SIMILAR TO YESTERDAY. FRONT WILL STILL BE HUNG UP TUESDAY
NIGHT THROUGH WEDNESDAY NIGHT...PROBABLY TO THE NORTH OF THE REGION.
ALTHOUGH COLD FRONT WILL LIKELY BEGIN TO CROSS THE REGION ON
THURSDAY...GFS/ECMWF CANNOT DECIDE WHETHER THE COLD FRONT WILL TAKE
24 OR 48 HOURS TO PUSH ALL THE WAY THROUGH. HAVE BUMPED UP POPS TO
LIKELY THURSDAY NIGHT...BUT OTHERWISE MADE LITTLE CHANGES TO POPS OR
TEMPERATURES.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS WL CONTINUE THIS MRNG ALTHOUGH BROAD SWATH OF MID
LVL CLDINESS CONTS TO FLOW OVR THE UPR OH VALLEY REGION. THE ONLY
AVIATION CONCERN THIS MRNG WILL LOW LEVEL WIND SHEAR AS LLVL JET
SURGES TWD LOW PRES CROSSING THE GREAT LAKES.
THAT SYSTEM WL DRAG A WEAK FRONT ACRS AREA PORTS ON SUNDAY...GIVEN
THE INITIALLY PALTRY BNDRY LAYER MSTR SUPPLY AND EXPECTED EWD
PROGRESS OF THE SPPRTG SHRTWV...FORECAST WL FEATURE -SHRA WITH
HIGH BASED CIGS AND VEERED WIND...GUSTS OF WHICH MAY APPRCH 30 KT
SHOULD NAM AND RAP MOMENTUM TRANSFER PROGNOSIS BE REALIZED. CONFIDENCE
IN MORE SIGNIFICANT OR WIDESPREAD DETERIORATION IS NOT SUFFICIENT
TO WARRANT TAF MENTION JUST YET.
.OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/...
THE BOUNDARY SHOULD SHIFT SOUTH OF THE REGION TONIGHT...THEN BE
PULLED NORTHWARD ONCE AGAIN ON MONDAY AS LOW PRES DIGS ACRS THE
GREAT LAKES. FRONT POSITIONING IS QUESTIONABLE THROUGH MUCH OF THE
WEEK...SO OCCASIONAL RESTRICTIONS SHOULD BE ANTICIPATED.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
436 AM EDT SUN APR 7 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 507 PM EDT SAT APR 6 2013
FIGURING OUT THIS MESSY SPRING SYSTEM CONTINUES TO BE A DIFFICULT
PROPOSITION.
999MB SFC LOW CONTINUES TO TRACK EAST ACROSS MINNESOTA...JUST TO
SOUTH OF TWIN CITIES AS OF 19Z. SFC WARM FRONT WELL TO SOUTH ACROSS
SOUTHERN WI. TEMP OF 60F AT MSN. READINGS NEAR 40F ARE CLOSING IN ON
WI BORDER. REMAINS IN THE LOW-MID 30S ELSEWHERE...COLDEST OVR THE
KEWEENAW PENINSULA AND OUT IN THE FAR EASTERN CWA AROUND KERY.
LARGER SCALE QUITE THE MESS AS THERE ARE MULTIPLE SHORTWAVES AND
MORE OF A SPLIT TROUGH LOOK AT H7-H5. NORTHERN STREAM WAVE IS
STRONGER THAN EXPECTED AND THIS HAS ALLOWED FOR STRONGER H925-H85
TROUGH TO DRAW WARM AIR AT 975-850MB INTO UPR MICHIGAN. CURRENT
RADAR SHOWS INITIAL WARM AIR ADVECTION SNOW IS 1-2 HRS FROM ENDING
AT KERY AND THERE HAS BEEN A DECENT LULL THAT OCCURED THIS AFTN OVR
MUCH OF THE CWA...EXCEPT ACROSS THE KEWEENAW WHERE SNOW HAS BEEN
STEADY MOST OF THE DAY.
UPSTREAM THOSE MULTIPLE SHORTWAVE TROUGHS ARE RESULTING IN MANY
AREAS OF PRECIPITATION. STRONGEST AREA OF PRECIP IS TIED TO
NORTHERN WAVE...WITH WIDESPREAD PRECIPITATION OVER NORTHEAST
MINNESOTA. CLUSTERS OF PRECIP ARE ALSO FILLING IN AHEAD OF SOUTHERN
STREAM WAVE AND SFC LOW OVER ECNTRL MN AND ALONG SFC WARM FRONT OVER
SOUTHERN WI. GRADUALLY THESE TWO SHORTWAVE TROUGHS ARE SHOWN TO PHASE
OVER WI/LK MICHIGAN TONIGHT...ALLOWING PRECIPITATION TO EXPAND OVR
MUCH OF CWA. FOLLOWING 975-950MB TEMPS FROM RUC/NAM/GFS POINTS TO
RAIN BEING DOMINANT PTYPE EARLY THIS EVENING OVER ALL BUT KEWEENAW
PENINSULA. HEAVIER PRECIPITATION MOVING OVER KDLH IN LAST HOUR HAS
PRODUCED RA/FZRA/PL/SN...EVEN AS RUC WARM LAYER WAS WELL ABOVE 0C.
THIS IS CERTAINLY THE DYNAMIC COOLING THAT MODELS WERE HINTING AT
ON FRIDAY. HINTS FROM NAM/GFS AND HRRR...WHICH IS HANDLING CURRENT
PRECIP TRENDS QUITE WELL...THAT SIMILAR SITUATION MAY OCCUR MID-LATE
EVENING OVER WESTERN THIRD OF CWA. TRIED TO SHOW THIS IN PYTPE GRIDS
AND ALSO INCREASED SNOWFALL AMOUNTS INTO 2-4 INCH RANGE FROM IRONWOOD
TO HOUGHTON AND INTO THE HURON MOUNTANS. ELSEWHERE THOUGH LATE EVENING
DO NOT EXPECT MUCH SNOW AT ALL AS WARM AIR ALOFT DOMINATES.
LATE EVENING INTO THE EARLY OVERNIGHT CHANGEOVER FROM RAIN TO SNOW
OCCURS INTO THE CNTRL AND EASTERN CWA. A COUPLE INCHES OF SNOW MAY
OCCUR WITH THE CHANGE BUT DEFORMATION HINTS FROM THE MODEL QPF
FIELDS NOT AS STRIKING/PERSISTENT. BY LATE TONIGHT...ALL PRECIP WILL
BE IN THE FORM OF SNOW...BUT PRECIP INTENSITY WILL BE ON THE WANE AS
COMMA HEAD OF LOW PRESSURE DIMINISHES. IMPROVING WEATHER ON SUNDAY
WITH LINGERING CLOUDS GIVING WAY TO AFTERNOON SUNSHINE. ONSHORE FLOW
OFF LK SUPERIOR SHOULD KEEP TEMPS ON THE COOL SIDE OVER THE NORTH
HALF. READINGS INTO THE LOWER 40S SEEM REASONABLE IN THE SOUTH WITH
DOWNSLOPING FLOW AND MORE SUNSHINE.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 435 AM EDT SUN APR 7 2013
MUCH MORE ACTIVE PERIOD THIS WEEK ALTHOUGH THE BELOW NORMAL
TEMPERATURES WILL REMAIN OVER THE AREA. FIRST SYSTEM OF NOTE
AFFECTING THE REGION ON MONDAY IS IN RESPONSE TO ENERGY EJECTING OUT
OF A WESTERN CONUS TROUGH. THIS ACTUALLY LEADS TO THREE DIFFERENT
AREAS OF PRECIPITATION/FORCING. THE FIRST AREA IS OVER THE LOWER
GREAT LAKES AND ASSOCIATED WITH A SHORTWAVE MOVING THROUGH THAT
REGION. THE SECOND AREA IS FARTHER TO THE WEST ACROSS THE UPPER
MISSISSIPPI VALLEY AND NORTHERN PLAINS...ASSOCIATED WITH THE
TIGHTENING THERMAL GRADIENT BETWEEN THE LOW IN EASTERN COLORADO AND
A HIGH IN ALBERTA. THE THIRD AREA...THAT IS EXPECTED TO AFFECT OUR
AREA IS DUE TO AN INVERTED TROUGH FROM THE LOW IN COLORADO AND A
WEAKER SHORTWAVE MOVING THROUGH THE WSW FLOW ALOFT. THIS TROUGH WILL
SLOWLY SHIFT EAST ACROSS THE CWA ON MONDAY AND WITH THE AREA UNDER A
COUPLED JET AND BROAD SOUTHERLY WAA...WOULD EXPECT LIGHT TO MODERATE
PRECIPITATION TO OCCUR ACROSS THE AREA. THERMAL FIELD LOOKS TO SETUP
SIMILAR LOCATION WISE TO THE SYSTEM THAT AFFECT THE AREA THIS PAST
EVENING. ALL MODELS ARE SHOWING A STRONG NOSE OF WARM AIR...FROM 0C
OVER THE KEWEENAW TO 4-5C AT KMNM...AT 850MB. THIS WOULD LEAD TO
LIMITED TO NO MELTING OVER THE KEWEENAW AND COMPLETE MELTING OVER
THE SOUTH CENTRAL. PRECIPITATION TYPE THEN COMES DOWN TO LOW LEVEL
AND SURFACE TEMPS. AT THIS POINT...LOOKS LIKE INITIAL SNOW OVER THE
KEWEENAW BEFORE RAIN/SNOW IN THE AFTERNOON...AN INITIAL PERIOD OF
RAIN/SNOW/FZRA OVER THE REST OF THE WEST/CENTRAL BEFORE GOING TO
RAIN AND THEN MAINLY RAIN EAST WITH THE WARMER AIR COMING OFF LAKE
MICHIGAN WITH THE SOUTHEAST FLOW...WETBULB VALUES STAYING ABOVE
FREEZING...AND THE LATER ARRIVAL OF PRECIPITATION DURING THE DAY.
21Z SREF PROBABILITIES HAD A SIMILAR IDEA AND HAVE FOLLOWED A
COMBINED THICKNESS AND SREF PROBS FOR P-TYPE.
DECENT VARIABILITY IN QPF AMOUNTS FROM THE MODELS...ALTHOUGH THE
TREND HAS BEEN TOWARDS HIGHER AMOUNTS. GFS/NAM SHOWING A SWATH
OF 1 INCH QPF OVER A PORTION OF THE WESTERN CWA IN AN AREA THAT HAS
HAD A SIMILAR SIGNAL OVER THE LAST SEVERAL RUNS WITH THE FOCUS OF
THE 925-850MB WAA...SO WILL CONTINUE TO FOCUS ON THE CORRIDOR
BETWEEN KIWD/KCMX TO THE WEST AND KIMT/KP53 TO THE EAST FOR THE
HIGHEST POPS/QPF. ON A POSITIVE NOTE...THAT AREA IS ONE OF THE
LONGER TERM DRIER AREAS OF THE CWA...ESPECIALLY IN THE MICHIGAMME
RIVER BASIN...SO ADDITIONAL PRECIPITATION WILL BE GOOD FOR
HYDROLOGIC USES BUT NOT AS MUCH FOR SPRING SNOWMELT POTENTIAL. WITH
THE REGIONAL GEM ALSO SHOWING HEAVIER PRECIP DURING THAT TIME...WILL
MAKE A SIGNIFICANT JUMP TO THE QPF VALUES /MORE THAN DOUBLE IN SOME
AREAS/ ALTHOUGH NOT AS HIGH AS SOME OF THE MODELS ARE SHOWING. HAVE
MENTIONED A COUPLE HOUR PERIOD OF MAINLY FREEZING RAIN AROUND
DAYBREAK. WITH THIS OCCURRING AROUND THE MORNING COMMUTE...COULD BE
QUITE SLICK AND WILL CONTINUE TO MENTION THE FREEZING RAIN IN THE
HWO.
AS THE TROUGH SHIFTS TO THE EAST...EXPECT COOLER AIR TO SLIDE
SOUTHEAST ACROSS THE AREA AND TRANSITION THE PRECIPITATION TO SNOW.
BUT THE LOSS OF DEEP MOISTURE AND FORCING /SHORTWAVE HAS
DEPARTED/...THINK ANY SNOWFALL ACCUMULATIONS WILL BE LIGHT DURING
THE EVENING AND EARLY OVERNIGHT HOURS. IN ADDITION...THIS LOSS OF
MOISTURE COULD LEAD IT TO BE MORE OF A DRIZZLE/FREEZING DRIZZLE
SITUATION INSTEAD OF SNOW...SO ADDED THAT IN OVER THE NW HALF OF
THE CWA TOWARDS THE OVERNIGHT HOURS.
HIGH PRESSURE THEN SETTLES IN OVER THE UPPER GREAT LAKES FOR
TUESDAY AND SHOULD LEAD TO A QUIET...BUT ONCE AGAIN BELOW NORMAL
TEMPERATURES. EXPECT THERE TO BE LINGERING LOW CLOUDS IN THE
MORNING OVER MUCH OF THE AREA AND THEN AS THOSE CLOUDS DIMINISH THE
AREA WILL SEE INCREASING MID-HIGH CLOUDS AHEAD OF THE NEXT
SHORTWAVE APPROACHING THE AREA. SO ALL IN ALL...EXPECT A MOSTLY
CLOUDY DAY FOR MOST OF THE CWA. THERE IS ALSO THE POTENTIAL THAT
PRECIPITATION FROM THE NEXT WAVE COULD SLIDE IN DURING THE LATE
AFTERNOON HOURS AND HAVE SLIGHT CHANCES TO ACCOUNT FOR THAT.
THE UNCERTAIN PORTION OF THE FORECAST THEN SETS UP FOR TUESDAY
NIGHT THROUGH THE REST OF THE WORK WEEK. WITH A LARGE UPPER TROUGH
SETUP OVER THE SOUTHWESTERN CONUS...THE FORECAST DEPENDS ON
SEVERAL WAVES EJECTING OUT OF THE UPPER TROUGH AROUND MID WEEK AND
THEN THE TROUGH ITSELF SHIFTING EAST ON THURSDAY AND THURSDAY NIGHT.
SEEMS LIKE THE MODELS HAVE THE GENERAL IDEA OF THE UPPER GREAT
LAKES BEING ON THE NORTHERN FRINGE OF THESE WAVES AND THEIR
ASSOCIATED PRECIPITATION. THEIR DIFFERENCES LARGELY DEPEND ON
THE LOCATION OF THE UPPER TROUGH SPINNING EAST OF HUDSON BAY AND
THE ASSOCIATED HIGH TO THE SOUTHWEST OF THAT. THE 12Z ECMWF HAS A
FARTHER SOUTH SOLUTION...WHICH KEEPS MUCH OF THE PRECIPITATION AND
EXITING WAVES TO THE SOUTH...WHILE THE GEM/GFS ARE A LITTLE FARTHER
NORTH. LATE ARRIVING 00Z ECMWF DID TREND A LITTLE FARTHER NORTH AND
BRUSHES THE SOUTHEAST THIRD OF THE CWA WITH PRECIP. THESE
DIFFERENCES LEAD TO SOME CONCERN TO THE FORECAST...AS THE 00Z RUN OF
THE GFS/GEM PUTS OVER AN INCH OF QPF OVER KMNM FOR TUESDAY NIGHT
INTO WEDNESDAY MORNING...WHILE THE 12Z ECMWF HAD 0.00 AND THE 00Z
RUN AROUND 0.15IN. BASED OFF GFS BUFKIT SOUNDINGS...WOULD EXPECT A
MIX OF SLEET/SNOW/FREEZING RAIN OVER THE SOUTH CENTRAL IF THAT
SOLUTION WAS CORRECT.
THE FIRST TWO WAVES WILL AFFECT THE AREA ON TUESDAY NIGHT AND THEN
ON WEDNESDAY. WHILE HIGHLIGHT BOTH OF THESE WAVES WITH CHANCE POPS
OVER THE FAR SOUTHEAST AND THEN SLOWLY TAPER TO SLIGHT CHANCES TO
THE NORTHWEST. WILL HAVE SLIGHTLY HIGHER POPS FOR THURSDAY INTO
THURSDAY NIGHT SINCE THE MAIN TROUGH WILL BE PUSHING THROUGH THE
AREA...ALTHOUGH QPF AMOUNTS SHOULD BE ON THE LIGHT SIDE. 00Z
MODEL RUNS HAVE COME INTO BETTER AGREEMENT FOR FRIDAY INTO
SATURDAY...WITH A HIGH PRESSURE RIDGE SETTING UP OVER THE CWA.
HAVE SHIFTED THE FORECAST TOWARDS A DRY SOLUTION FOR FRIDAY
AND FRIDAY NIGHT...BUT DID LEAVE SOME SLIGHT CHANCES IN ON
SATURDAY AS THE NEXT WAVE APPROACHES THE AREA. AS FOR PRECIPITATION
TYPE FROM TUESDAY NIGHT ON...APPEARS THERE WILL BE ENOUGH COLD AIR
TO KEEP PRECIPITATION MAINLY AS SNOW AND HAVE FOLLOWED THICKNESS
FIELDS FOR PRECIP TYPES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 420 AM EDT SUN APR 7 2013
AN UPPER LEVEL DISTURBANCE AND ASSOCIATED SURFACE LOW OVER THE AREA
HAS CAUSED A WINTRY MIX OF RAIN AND SNOW THIS EVENING...WITH ALL TAF
SITES REPORTING PRECIP AND LOW CIGS AND VIS. BY THE BEGINNING OF THE
TAF PERIOD...RAIN WILL HAVE CHANGED OVER TO ALL SNOW...WITH LOW VIS
AND CIGS EXPECTED TO SLOWLY LIFT AS BEST MOISTURE MOVES EASTWARD /AS
IS REFLECTED IN LATEST OBS FROM KIWD WHERE INTENSITY OF SNOW HAS
DECREASED AND VIS HAS INCREASED...THOUGH CIGS STILL REMAIN LOW/
THROUGH SUNDAY MORNING. HAVE IFR CONDITIONS TO START OUT...THOUGH
SOME FLUCTUATIONS ABOVE AND BELOW ARE STILL POSSIBLE...SLOWLY
IMPROVING THROUGH THE NIGHT BEFORE -SHSN COMES TO AN END SUN MORN.
HIGH PRESSURE AND VFR CONDITIONS WILL MOVE IN OVERHEAD BRIEFLY
DURING THE DAY TOMORROW...BEFORE HIGH CLOUDS RETURN BY END OF TAF
PERIOD AHEAD OF NEXT SYSTEM.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 507 PM EDT SAT APR 6 2013
ACROSS LAKE SUPERIOR...SE TO E WINDS OF 15-30KT WILL BACK AROUND TO
THE N/NW TONIGHT IN THE WAKE OF LOW PRES PASSING JUST S OF LAKE
SUPERIOR. THE STRONGEST WINDS TONIGHT THRU SUN MORNING WILL BE OVER
ERN LAKE SUPERIOR. WINDS WILL THEN STEADILY DIMINISH W TO E SUN...
FALLING TO AOB 15KT...AS HIGH PRES RIDGE NOSES INTO THE UPPER LAKES.
AS THE RIDGE DEPARTS...E TO SE WINDS WILL INCREASE A BIT SUN
NIGHT/MON...BUT SHOULD REMAIN UNDER 20KT. TUE-THU...N TO NE WINDS
WILL DOMINATE AS THE UPPER LAKES WILL BE SITUATED BTWN HIGH PRES TO
THE N AND A LOW PRES TROF EXTENDING FROM THE SRN PLAINS TO THE OHIO
VALLEY. AT TIMES...WINDS WILL BE IN THE 15-25KT RANGE...DEPENDING ON
ANY WAVES OF LOW PRES TRACKING ALONG THE TROF TO THE S.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLA
LONG TERM...SRF
AVIATION...JMW
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
421 AM EDT SUN APR 7 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 507 PM EDT SAT APR 6 2013
FIGURING OUT THIS MESSY SPRING SYSTEM CONTINUES TO BE A DIFFICULT
PROPOSITION.
999MB SFC LOW CONTINUES TO TRACK EAST ACROSS MINNESOTA...JUST TO
SOUTH OF TWIN CITIES AS OF 19Z. SFC WARM FRONT WELL TO SOUTH ACROSS
SOUTHERN WI. TEMP OF 60F AT MSN. READINGS NEAR 40F ARE CLOSING IN ON
WI BORDER. REMAINS IN THE LOW-MID 30S ELSEWHERE...COLDEST OVR THE
KEWEENAW PENINSULA AND OUT IN THE FAR EASTERN CWA AROUND KERY.
LARGER SCALE QUITE THE MESS AS THERE ARE MULTIPLE SHORTWAVES AND
MORE OF A SPLIT TROUGH LOOK AT H7-H5. NORTHERN STREAM WAVE IS
STRONGER THAN EXPECTED AND THIS HAS ALLOWED FOR STRONGER H925-H85
TROUGH TO DRAW WARM AIR AT 975-850MB INTO UPR MICHIGAN. CURRENT
RADAR SHOWS INITIAL WARM AIR ADVECTION SNOW IS 1-2 HRS FROM ENDING
AT KERY AND THERE HAS BEEN A DECENT LULL THAT OCCURED THIS AFTN OVR
MUCH OF THE CWA...EXCEPT ACROSS THE KEWEENAW WHERE SNOW HAS BEEN
STEADY MOST OF THE DAY.
UPSTREAM THOSE MULTIPLE SHORTWAVE TROUGHS ARE RESULTING IN MANY
AREAS OF PRECIPITATION. STRONGEST AREA OF PRECIP IS TIED TO
NORTHERN WAVE...WITH WIDESPREAD PRECIPITATION OVER NORTHEAST
MINNESOTA. CLUSTERS OF PRECIP ARE ALSO FILLING IN AHEAD OF SOUTHERN
STREAM WAVE AND SFC LOW OVER ECNTRL MN AND ALONG SFC WARM FRONT OVER
SOUTHERN WI. GRADUALLY THESE TWO SHORTWAVE TROUGHS ARE SHOWN TO PHASE
OVER WI/LK MICHIGAN TONIGHT...ALLOWING PRECIPITATION TO EXPAND OVR
MUCH OF CWA. FOLLOWING 975-950MB TEMPS FROM RUC/NAM/GFS POINTS TO
RAIN BEING DOMINANT PTYPE EARLY THIS EVENING OVER ALL BUT KEWEENAW
PENINSULA. HEAVIER PRECIPITATION MOVING OVER KDLH IN LAST HOUR HAS
PRODUCED RA/FZRA/PL/SN...EVEN AS RUC WARM LAYER WAS WELL ABOVE 0C.
THIS IS CERTAINLY THE DYNAMIC COOLING THAT MODELS WERE HINTING AT
ON FRIDAY. HINTS FROM NAM/GFS AND HRRR...WHICH IS HANDLING CURRENT
PRECIP TRENDS QUITE WELL...THAT SIMILAR SITUATION MAY OCCUR MID-LATE
EVENING OVER WESTERN THIRD OF CWA. TRIED TO SHOW THIS IN PYTPE GRIDS
AND ALSO INCREASED SNOWFALL AMOUNTS INTO 2-4 INCH RANGE FROM IRONWOOD
TO HOUGHTON AND INTO THE HURON MOUNTANS. ELSEWHERE THOUGH LATE EVENING
DO NOT EXPECT MUCH SNOW AT ALL AS WARM AIR ALOFT DOMINATES.
LATE EVENING INTO THE EARLY OVERNIGHT CHANGEOVER FROM RAIN TO SNOW
OCCURS INTO THE CNTRL AND EASTERN CWA. A COUPLE INCHES OF SNOW MAY
OCCUR WITH THE CHANGE BUT DEFORMATION HINTS FROM THE MODEL QPF
FIELDS NOT AS STRIKING/PERSISTENT. BY LATE TONIGHT...ALL PRECIP WILL
BE IN THE FORM OF SNOW...BUT PRECIP INTENSITY WILL BE ON THE WANE AS
COMMA HEAD OF LOW PRESSURE DIMINISHES. IMPROVING WEATHER ON SUNDAY
WITH LINGERING CLOUDS GIVING WAY TO AFTERNOON SUNSHINE. ONSHORE FLOW
OFF LK SUPERIOR SHOULD KEEP TEMPS ON THE COOL SIDE OVER THE NORTH
HALF. READINGS INTO THE LOWER 40S SEEM REASONABLE IN THE SOUTH WITH
DOWNSLOPING FLOW AND MORE SUNSHINE.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 507 PM EDT SAT APR 6 2013
A PATTERN CHANGE STILL APPEARS TO BE IN THE OFFING OVER THE NEXT
COUPLE OF WEEKS THAT SHOULD TRANSITION THE PERSISTENT BELOW NORMAL
TEMP REGIME TOWARD A NORMAL OR ABOVE NORMAL ONE. HOWEVER...
CONFIDENCE IS NOT HIGH THAT ABOVE NORMAL TEMPS WILL ACTUALLY SET IN.
THE AO AND NAO WHICH HAVE BEEN IN A PREVAILING NEGATIVE PHASE SINCE
EARLY/MID FEB ARE STILL BOTH FORECAST TO TREND TO THE POSITIVE PHASE
WHICH SHOULD TRANSLATE TO WARMING. HOWEVER...THE GFS ENSEMBLES ARE
ROUGHLY SPLIT IN EITHER MAINTAINING A WEAK NEGATIVE NAO OR ONLY
GOING TO A SLIGHT POSITIVE PHASE. THE FORECASTED PHASE OF THE MJO
FAVORS BLO NORMAL TEMPS FOR THE UPPER LAKES THRU ABOUT MID MONTH
THEN ABOVE NORMAL LATE MONTH. SO...WHILE TEMPS OVERALL WILL LIKELY
FALL ON THE COLDER SIDE OF NORMAL FOR THE NEXT WEEK OR SO...THE
PROSPECT FOR NORMAL OR ABOVE NORMAL TEMPS SHOULD INCREASE FOR THE
LATTER PART OF APRIL. BOTH THE GFS AND ECMWF ARE SHOWING ANOTHER
TROF SETTLING INTO THE WRN CONUS IN THE 7-10DAY PERIOD...SO THAT MAY
BE THE HARBINGER OF THE POSSIBLE WARMER PATTERN TO FOLLOW...OR AT
LEAST ONE THAT IS MORE VARIABLE RATHER THAN PERSISTENTLY BLO NORMAL.
THE PATTERN WILL ALSO BE AN ACTIVE ONE ACROSS THE CONUS. AFTER
TODAYS SYSTEM AFFECTING THE UPPER LAKES...TROF AMPLIFICATION WILL
OCCUR OVER THE WRN CONUS OVER THE NEXT FEW DAYS WITH THE TROF THEN
SLOWLY TRANSLATING ACROSS THE CONUS DURING THE WEEK. THIS WILL
PROVIDE THE POTENTIAL FOR SIGNIFICANT PCPN EVENTS THRU MUCH OF THE
COMING WEEK FROM THE PLAINS EWD AS THE GULF FULLY OPENS UP. FOR
UPPER MI...THIS COULD MEAN ONE OR MORE UNWELCOMED RAIN EVENTS ON A
MELTING SNOWPACK WHICH IS STILL DEEP IN THE LAKE EFFECT AREAS OR
SIGNIFICANT SNOW COULD STILL BE ADDED. MUCH WILL DEPEND ON THE
STRENGTH OF THE ERN CANADA TROF THAT IS STILL IN PLACE UNDER THE
LINGERING...BUT WEAKENING NEGATIVE AO/NAO REGIME. IF THE TROF
REMAINS STRONG...EPISODES OF HVY PCPN ASSOCIATED WITH THE SLOWLY
PROGRESSIVE SRN STREAM TROF WILL PASS BY TO THE S...LEAVING DRIER
WEATHER TO DOMINATE HERE. WITH THE CONSIDERABLE SNOWPACK STILL IN
PLACE...A DRIER WEATHER REGIME WOULD BE HELPFUL BECAUSE THE LATER WE
GO THRU APRIL ADDING PCPN TO THE SNOWPACK WITHOUT MUCH MELTING
THE GREATER THE POTENTIAL WILL BECOME FOR A RAPID MELTDOWN AND
INCREASED FLOODING. AFTER THE FIRST WRN TROF LIFTS OUT...THE
PROSPECT OF ANOTHER DEVELOPING 7-10 DAYS DOWN THE ROAD IS A CONCERN
AS IT WOULD FAVOR THE POTENTIAL FOR MORE FREQUENT PCPN EVENTS ON THE
MELTING SNOWPACK.
AFTER SIGNIFICANT INCONSISTENCIES FOR SEVERAL DAYS AMONG ALL THE
MEDIUM RANGE GUIDANCE...MODELS ARE NOW ON BOARD WITH AN INITIAL
SHORTWAVE EJECTING INTO THE UPPER LAKES SUN NIGHT/MON AHEAD OF THE
DEVELOPING WRN TROF. WITH PRECIPITABLE WATER VALUES RISING TO
160-200 PCT OF NORMAL...A GOOD PUSH OF ISENTROPIC ASCENT PER 295K
SFC...AND FGEN FORCING UNDER RIGHT ENTRANCE REGION OF UPPER JET...
PCPN APPEARS LIKELY. BASED ON 850MB TEMPS/1000-850MB
THICKNESS...PTYPE SHOULD TRANSITION FROM SNOW OR SNOW/FZRA/RA WHEN
IT BEGINS OVERNIGHT SUN NIGHT TO MOSTLY RAIN DURING MON. THE ONLY
PLACE SOME SNOW MAY STILL MIX WITH RAIN MON AFTN IS OVER THE HIGHER
TERRAIN OF NW UPPER MI. MIGHT SEE A TRANSITION BACK TO SNOW OR A
RAIN/SNOW MIX AS THE PCPN EXITS MON NIGHT.
DURING THE MID AND LATE WEEK PERIOD...WILL LEAN FCST MORE STRONGLY
TOWARD THE ECMWF WHICH HAS NOW DEVELOPED GOOD RUN-TO-RUN CONSISTENCY
OVER THE LAST 5 RUNS WITH REGARD TO THE WRN TROF LIFTING OUT. THE
ECWMF ALSO SEEMS TO BETTER FIT THE PATTERN OF THE LINGERING BUT
WEAKENING NEGATIVE NAO WHICH HOLDS STRONGER TROFFING IN OVER SE
CANADA. IT IS ALSO ENCOURAGING TO SEE THE ONCE VERY INCONSISTENT AND
EXTREME GFS SHIFTING TOWARD SOMETHING MUCH MORE LIKE THE ECMWF (MANY
GFS RUNS SHOWED A STRONG SURGE OF SPRING WARMTH INTO UPPER LAKES
MIDWEEK AS IT TRACKED RATHER DEEP SFC LOWS THRU THE UPPER
MISSISSIPPI VALLEY). THE 00Z UKMET LENDS SUPPORT TO THE ECMWF THOUGH
IT DOES HAVE A STRONGER SFC LOW FARTHER N INTO NRN LWR MI THU IN
RESPONSE TO THE MAIN ENERGY LIFTING NE. THE GEM HAS BECOME MORE
INCONSISTENT...AND ITS 00Z/12Z RUNS APPEAR TOO FAST LIFTING TROF OUT
COMPARED TO OTHER GUIDANCE. SO...WHILE CONFIDENCE IN THE RESULTING
SENSIBLE WEATHER FOR THE FCST AREA IS STILL LOW...IT IS IMPROVED
FROM RECENT DAYS. IN INCORPORATING MORE OF THE ECMWF INTO THE
FCST...EXPECT DRY WEATHER TO PREVAIL TUE WITH SFC HIGH PRES RIDGE
NOSING INTO THE UPPER LAKES FROM THE NW. ALTHOUGH TIMING THE LIFTING
OUT OF THE WRN TROF AND ANY SHORTWAVES WILL CONTINUE TO BE
PROBLEMATIC...WILL SHOW SOME INCREASED POTENTIAL FOR PCPN WED...
MAINLY OVER THE S WHERE LOW CHC POPS WILL BE UTILIZED...BUT MORE SO
THU GIVEN THAT THE LAST 5 ECMWF RUNS HAVE BEEN POINTING TOWARD THU
AS THE DAY THE MAIN PIECE OF ENERGY AFFECTS THE AREA. PTYPE WOULD
PROBABLY BE MAINLY SNOW. GIVEN THE OPEN GULF...THE SNOW COULD BE
SIGNIFICANT...BUT THAT POTENTIAL APPEARS TO BE DIMINISHING AS THE
ECMWF HAS SHOWN A TENDENCY FOR ANY SFC LOWS TO BE WEAKER AND FARTHER
SE DUE TO THE STRONGER TROF AND CONFLUENCE ZONE IT HAS LINGERING
OVER SE CANADA...WHICH AGAIN DOES FIT THE RECENT PATTERN AS ALLUDED
TO ABOVE. THIS RESULTS IN THE BEST PUSH OF MOISTURE/WAA BEING
SUPPRESSED TO THE S AND E. WILL LINGER CHC POPS INTO FRI AS
MID/UPPER LEVEL TROF PASSES AND THEN SHOOT FOR A DRY SAT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 420 AM EDT SUN APR 7 2013
AN UPPER LEVEL DISTURBANCE AND ASSOCIATED SURFACE LOW OVER THE AREA
HAS CAUSED A WINTRY MIX OF RAIN AND SNOW THIS EVENING...WITH ALL TAF
SITES REPORTING PRECIP AND LOW CIGS AND VIS. BY THE BEGINNING OF THE
TAF PERIOD...RAIN WILL HAVE CHANGED OVER TO ALL SNOW...WITH LOW VIS
AND CIGS EXPECTED TO SLOWLY LIFT AS BEST MOISTURE MOVES EASTWARD /AS
IS REFLECTED IN LATEST OBS FROM KIWD WHERE INTENSITY OF SNOW HAS
DECREASED AND VIS HAS INCREASED...THOUGH CIGS STILL REMAIN LOW/
THROUGH SUNDAY MORNING. HAVE IFR CONDITIONS TO START OUT...THOUGH
SOME FLUCTUATIONS ABOVE AND BELOW ARE STILL POSSIBLE...SLOWLY
IMPROVING THROUGH THE NIGHT BEFORE -SHSN COMES TO AN END SUN MORN.
HIGH PRESSURE AND VFR CONDITIONS WILL MOVE IN OVERHEAD BRIEFLY
DURING THE DAY TOMORROW...BEFORE HIGH CLOUDS RETURN BY END OF TAF
PERIOD AHEAD OF NEXT SYSTEM.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 507 PM EDT SAT APR 6 2013
ACROSS LAKE SUPERIOR...SE TO E WINDS OF 15-30KT WILL BACK AROUND TO
THE N/NW TONIGHT IN THE WAKE OF LOW PRES PASSING JUST S OF LAKE
SUPERIOR. THE STRONGEST WINDS TONIGHT THRU SUN MORNING WILL BE OVER
ERN LAKE SUPERIOR. WINDS WILL THEN STEADILY DIMINISH W TO E SUN...
FALLING TO AOB 15KT...AS HIGH PRES RIDGE NOSES INTO THE UPPER LAKES.
AS THE RIDGE DEPARTS...E TO SE WINDS WILL INCREASE A BIT SUN
NIGHT/MON...BUT SHOULD REMAIN UNDER 20KT. TUE-THU...N TO NE WINDS
WILL DOMINATE AS THE UPPER LAKES WILL BE SITUATED BTWN HIGH PRES TO
THE N AND A LOW PRES TROF EXTENDING FROM THE SRN PLAINS TO THE OHIO
VALLEY. AT TIMES...WINDS WILL BE IN THE 15-25KT RANGE...DEPENDING ON
ANY WAVES OF LOW PRES TRACKING ALONG THE TROF TO THE S.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLA
LONG TERM...ROLFSON
AVIATION...JMW
MARINE...ROLFSON
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1139 PM CDT SAT APR 6 2013
.UPDATE...
ISSUED AT 852 PM CDT SAT APR 6 2013
A WEAK COLD FRONT NOW EXTENDING FROM EASTERN IOWA SWWD THROUGH
CENTRAL MO HAS BEEN THE FOCUS OF SOME SHOWERS THIS EVENING IN
OUR CWA...WITH THUNDERSTORMS OVER EASTERN IOWA AND NW ILLINOIS.
MODELS THIS EVENING...INCLUDING THE HRRR AND RUC...HAVE
CONTINUED TO INDICATE A NARROW BAND OF SHOWERS TO PERSIST ALONG
AND JUST AHEAD OF THE FRONT AS IT MOVES THROUGH OUR CWA TONIGHT.
HAVE UPPED POPS ACROSS WEST CENTRAL IL THROUGH MIDNIGHT AND
INCLUDED A MENTION OF THUNDER GIVEN MUCAPE VALUES BETWEEN 100-200
J/KG OVER EASTERN IOWA AND NW ILLINOIS WHICH HAVE BEEN ENOUGH TO
RESULT IN A FAIRLY SOLID LINE OF THUNDERSTORMS THIS EVENING OVER
THAT AREA. HOWEVER...GIVEN MUCH OF THE FORCING REMAINS ANCHORED
NORTH OF THE CWA...A CONTINUED MENTION OF SOME SPOTTY SHOWERS
REMAINS SUFFICIENT FOR THE REMAINDER OF THE AREA. ASIDE FROM THE
AFOREMENTIONED CHANGES...THE REST OF THE FORECAST REMAINS ON TRACK
THIS EVENING...WITH ONLY MINOR CHANGES NEEDED TO ACCOUNT FOR NEAR
TERM TEMPERATURE TRENDS.
JP
&&
.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 322 PM CDT SAT APR 6 2013
THE WEAK COLD FRONT NOW EXTENDING THROUGH NW MO WILL MOVE SEWD
INTO THE REGION TONIGHT AS THE ASSOCIATED SHORT WAVE TROF TRACKS
ACROSS THE UPPER MS VALLEY INTO THE GREAT LAKES. MODEL CONSENSUS
IS THE FRONT SHOULD BE IN THE VICINITY OF THE I-70 CORRIDOR AT 12Z
SUNDAY. PRESENTLY THERE IS NOT MUCH MORE THAN MID CLOUDS AND
SPINKLES OR A SPOT SHOWER AHEAD OF THE FRONT. SOME OF THE EXPLICIT
GUIDANCE SUGGESTS A NARROW BROKEN LINE OF SHOWERS/THUNDERSTORMS
WILL DEVELOP ALONG THE FRONT AS IT PUSHES INTO THE CWA. THIS LOOKS
A BIT OVERDONE HOWEVER...AS THE FORCING IS WEAK AND OBSERVED
MUCAPES ARE LESS THAN 100 J/KJ. CURRENT THINKING IS THERE MAY BE
SOME SPOTTY SHOWERS WITH THE FRONT...PRIMARILY FROM EASTERN MO
INTO WESTERN ILLINOIS. TEMPERTURES ON SUNDAY SHOULD BE AT LEAST
COMPARABLE TO TODAY.
THE EAST-WEST ORIENTED FRONT MAY OOZE A TAD FURTHER SOUTH ON
SUNDAY MORNING BUT IS EXPECTED TO BECOME QUASI-STATIONARY IN THE
VICINITY OF THE I-70 CORRIDOR IN THE AFTERNOON. THE PRECIPITATION
THREAT SEEMS TO LARGELY BE DEPENDENT ON THE INSTABILITY WHICH
LOOKS A BIT OVERDONE IN THESE INITIAL STAGES OF THE RETURN FLOW
OWING TO TOO HIGH OF SURFACE DEW POINTS. THINKING AT THIS TIME IS
THERE COULD BE SOME SCATTERED SHOWERS OR THUNDERSTORMS WITHIN THE
BROAD FRONTAL ZONE...ESPECIALLY IN CENTRAL MO. THE PRECIPITATION
CHANCES ARE EXPECTED TO RAMP UP CONSIDERABLY ON SUNDAY NIGHT
ASSOCIATED WITH FORCING VIA A MIGRATORY SHORT WAVE WITHIN THE WSW
FLOW ALOFT AND INTENSIFYING AND VEERING SWLY LLJ. THE MAIN FOCUS
SHOULD BE ALONG AND NORTH OF I-70 WITHIN THE COOL SECTOR NORTH OF
THE RETREATING BOUNDARY.
GLASS
.LONG TERM...(MONDAY THROUGH NEXT SATURDAY)
ISSUED AT 322 PM CDT SAT APR 6 2013
FROM MONDAY INTO TUESDAY THE DETAILS IN THE FORECAST BECOME A BIT
MORE DIFFICULT TO RESOLVE DUE TO MARKED DIFFERENCES IN THE POSITION
AN EAST-WEST BOUNDARY THAT WILL RESIDE ACROSS EITHER NORTHERN MO
OR FURTHER NORTH INTO IOWA. THE ECMWF HAS BEEN THE MOST INSISTENT
WITH THE MORE SRN POSITION AND THUS MUCH WETTER...WHILE THE
REMAINDER OF THE GUIDANCE SUITE KEEPS THE BOUNDARY ALONG OR NORTH
OF THE IOWA/MISSOURI BORDER WITH LESSER PRECIPITATION CHANCES. ON
MONDAY MORNING I THINK THAT ANY LINGERING THREAT OF SHOWERS AND
THUNDERSTORMS WILL BE ALIGNED WITH THE SWLY LLJ AXIS AND BY
AFTERNOON THE EML BUILDS IN STRONGLY AND RESULTS IN SUBSTANTIAL
CAPPING OF THE WARM SECTOR. THE WARM SECTOR WILL CONTINUE TO
MOISTEN AND DESTABILIZE INTO TUESDAY AND SHOULD REMAIN CAPPED TO
SURFACE BASED STORMS SOUTH OF THE FRONT. AT THIS TIME I HAVE KEPT
MY HIGHEST POPS IN THE MONDAY-TUESDAY TIME FRAME ACROSS NRN MO
INTO WEST CENTRAL ILLINOIS WHERE THE FRONT MAY EXIST...WITH POPS
TAPPERED SOUTHWARD. DEPENDING ON WHERE THE FRONT EVENTUALLY
RESIDES I COULD BE UNDERDONE OR OVERDONE WITH THE PRECIPITATION
THREAT. THE MAIN SHOW WITH THE DEEP PROGRESSIVE LONGWAVE TROF AND
ASSOCIATED SURFACE FRONT ALSO REMAINS PROBLEMATIC WITH TIMING
DIFFERENCES IN THE EASTWARD PROGRESSION AMONGST THE SLOWEST
ECMWF...AND FASTER GFS...GEFS AND CANADIAN. ONE PLAUSIBLE SCENARIO
IS THAT THE PLAINS SEVERE WEATHER EVENT ON TUESDAY WILL GROW
UPSCALE INTO A LINE/QLCS AND SHIFT EASTWARD INTO THE AREA
OVERNIGHT TUESDAY INTO WEDNESDAY MORNING. ANOTHER IS THAT THIS
LINE MAY REACH INTO WESTERN MO IN A WEAKENING STATE LATE TUESDAY
NIGHT AND THE MAIN EVENT MAYBE WED AFTERNOON AND EVENING IN THE
CWA PER THE ECMWF. THUS SOMEWHERE IN THE LATE TUESDAY NIGHT-
WEDNESDAY NIGHT TIME FRAME WE ARE LIKELY TO SEE SIGNIFICANT
CONVECTION...SOME OF WHICH COULD BE SEVERE.
A COOL DOWN IS FORECAST IN THE WAKE OF THE FRONT THURSDAY INTO
FRIDAY WITH BROAD CYCLONIC FLOW ALOFT.
GLASS
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1139 PM CDT SAT APR 6 2013
WEAK COLD FRONT IS SLIDING THROUGH REGION AND HAS MOVED THROUGH
KUIN AND KCOU...AND SHOULD BE MOVING THROUGH METRO AREA BETWEEN
06Z AND 08Z. WITH PASSAGE OF FRONTAL BOUNDARY...WINDS TO BECOME
LIGHT AND VARIABLE FOR THE REST OF THE OVERNIGHT HOURS. SOME
SHOWERS HAVE POPPED UP AHEAD OF FRONTAL BOUNDARY THIS
EVENING...BUT SHOULD REMAIN JUST NORTH OF METRO AREA AND MOVE OUT
BY 06Z...SO NO NEED TO MENTION IN TAFS. CIGS TO REMAIN VFR THROUGH
FORECAST PERIOD. OTHERWISE...WINDS TO PICKUP FROM THE SOUTHEAST
TO SOUTH BY MID MORNING SUNDAY AS FRONT SLIDES BACK NORTH AS A
WARM FRONT. AS FOR PCPN CHANCES...BEST CHANCES WILL BE SUNDAY
EVENING. BEST INSTABILITY AND LIFT WILL BE OVER CENTRAL MO...SO
ADDED TSTM MENTION THERE AFTER 00Z MONDAY. AS FOR REST OF TAF
SITES...NOT AS STRONG INSTABILITY...SO JUST ADDED PROB30 MENTION
FOR SHOWERS FOR SUNDAY EVENING.
SPECIFICS FOR KSTL...WEAK COLD FRONT IS SLIDING THROUGH REGION AND
SHOULD BE MOVING THROUGH METRO AREA BY 08Z. WITH PASSAGE OF
FRONTAL BOUNDARY...WINDS TO BECOME LIGHT AND VARIABLE FOR THE REST
OF THE OVERNIGHT HOURS. SOME SHOWERS HAVE POPPED UP AHEAD OF
FRONTAL BOUNDARY THIS EVENING...BUT SHOULD REMAIN JUST NORTH OF
METRO AREA AND MOVE OUT BY 06Z...SO NO NEED TO MENTION IN TAF.
CIGS TO REMAIN VFR THROUGH FORECAST PERIOD. OTHERWISE...WINDS TO
PICKUP FROM THE SOUTHEAST BY 16Z SUNDAY AS FRONT SLIDES BACK NORTH
AS A WARM FRONT. AS FOR PCPN CHANCES...BEST CHANCES WILL BE SUNDAY
EVENING. NOT AS STRONG INSTABILITY OVER METRO AREA AT THIS
TIME...SO JUST ADDED PROB30 MENTION FOR SHOWERS BETWEEN 01Z AND
05Z MONDAY.
BYRD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS BISMARCK ND
429 AM CDT SUN APR 7 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 329 AM CDT SUN APR 7 2013
THE MAIN FORECAST CHALLENGES FOR THE SHORT TERM INCLUDE
PRECIPITATION TIMING AND TYPE. THE 00Z MODEL SUITE IS IN
AGREEMENT...THUS HAVE UTILIZED A BLEND OF GUIDANCE.
LATEST RADAR IMAGERY AT 330 AM CDT IS SHOWING SOME SCATTERED LIGHT
RETURNS ACROSS THE SOUTHWEST....AND MORE WIDESPREAD LIGHT RETURNS
OVER NORTHEASTERN MONTANA ASSOCIATED WITH A WEAK UPPER LEVEL IMPULSE.
HOWEVER...SURFACE OBSERVATIONS HAVE NOT REFLECTED PRECIPITATION
REACHING THE GROUND OVER THE SOUTHWEST. THE 05/06Z RAP SOLUTIONS DO
NOT REFLECT THE LIGHT PRECIPITATION OVER THE NORTHEAST AT THIS
TIME...BUT IT DOES PAINT SOME LIGHT PRECIPITATION ACROSS THE
SOUTHWEST. THE 00Z GFS/ECMWF/NAM ALL SHOW LIGHT PRECIPITATION OVER
NORTHEAST MONTANA AT THIS TIME...AND THUS HAVE UTILIZED A BLEND OF
THE 00Z MODEL GUIDANCE IN ADDITION TO THE 05/06Z RAP GUIDANCE.
PRECIPITATION WILL CONTINUE TO SPREAD EAST WITH TIME...FILLING IN
OVER THE WEST OVER THE NEXT FEW HOURS...AND THEN OVER THE CENTRAL
BY LATER THIS MORNING...AS THE UPPER LEVEL IMPULSE MOVES OVER THE
AREA.
LATEST OBSERVATIONS AT 400 AM CDT SHOW THAT TEMPERATURES SOUTH AND
WEST OF THE MISSOURI RIVER REMAIN ABOVE FREEZING...WHILE NORTH AND
EAST...TEMPERATURES ARE IN THE MID TO UPPER 20S. FOLLOWING THE
COLD FRONTAL PASSAGE YESTERDAY...COLD AIR ADVECTION ALOFT IS
UNDERWAY...WITH A SHALLOW WARM LAYER JUST ABOVE THE SURFACE.
PRECIPITATION WILL START AS FREEZING RAIN...WITH SOME SNOW AND
SLEET MIXED IN ACROSS THE WEST...BUT AS TEMPERATURES WARM ACROSS
THE SOUTHWEST AND SOUTH CENTRAL...A TRANSITION TO RAIN WILL OCCUR.
FOR LOCATIONS ACROSS THE NORTH...WHERE TEMPERATURES ARE CURRENTLY
SUBFREEZING...PRECIPITATION WILL START AS SNOW...BUT AS
TEMPERATURES WARM NEAR THE SURFACE WITH COLDER AIR PRESENT ALOFT...A
TRANSITION TO FREEZING RAIN AND THEN TO A MIX OF FREEZING
RAIN...SLEET...AND SNOW AFTER MIDNIGHT.
EVEN THOUGH THE FORECAST PROCESS HAS LED TO INCREASED MIXED
PRECIPITATION (SNOW...SLEET AND FREEZING RAIN) AND DECREASED
COVERAGE OF FREEZING RAIN...HAVE DECIDED TO CONTINUE THE FREEZING RAIN
ADVISORY AT THIS TIME. WILL CONTINUE TO MONITOR AND MAKE CHANGES
IF WARRANTED.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 329 AM CDT SUN APR 7 2013
THE MAIN FORECAST PROBLEM IN THE EXTENDED PERIOD WILL MONDAY THROUGH
MONDAY NIGHT...ACTUALLY BEGINNING LATE SUNDAY NIGHT IN THE FAR WEST.
WILL LEAN MORE TOWARD A ECMWF/GEM SOLUTION OVER THE GFS/NAM FOR QPF
DETAILS.
ALTHOUGH THE STRONG UPPER LEVEL SYSTEM IN THE WEST DIVES SOUTH ON
MONDAY...THERE IS STILL A PIECE OF UPPER LEVEL ENERGY THAT MAKES IT
INTO THE NORTHERN PLAINS. DETERMINISTIC MODELS ARE IN REASONABLE
AGREEMENT IN BRINGING THIS INTO THE LOCAL AREA. ALTHOUGH RATHER
SIGNIFICANT DIFFERENCES IN THE RESULTING PLACEMENT OF THE QPF AS THE
WAVE INTERACT WITH A TIGHTENING BAROCLINIC ZONE ACROSS WESTERN AND
CENTRAL NORTH DAKOTA. THE NAM/GFS ARE FARTHER NORTH WITH THE QPF
THAN THE GEM/ECMWF...ALTHOUGH THE 00 UTC SUNDAY ECMWF HAS COME A
LITTLE FARTHER NORTH THAN PREVIOUS RUNS. LOOKING AT GFS BUFKIT
SOUNDINGS...THERE DOES APPEAR TO BE A 3 TO 6 HOUR PERIOD WITH STRONG
OMEGA OVER WITHIN THE SNOW GROWTH ZONE IN THE WEST CENTRAL AND
SOUTHWEST...WHICH SHOULD YIELD SOME DECENT SNOW AMOUNTS. THIS AREA
EXTENDS EAST ACROSS CENTRAL NORTH DAKOTA DURING THE DAY MONDAY BUT
STRONG HIGH PRESSURE DROPPING SOUTH FROM CANADA WILL INHIBIT FG
FORCING LATER IN THE DAY. THIS SHOULD REDUCE SNOW AMOUNTS AS THE
WAVE MOVES EASTWARD INTO CENTRAL AND EASTERN NORTH DAKOTA.
A COMBINATION OF HPC SNOW AMOUNTS WITH MODEL QPF YIELDS 3 TO 5
INCHES OF SNOW OVER MUCH OF WEST CENTRAL AND SOUTHWEST NORTH
DAKOTA...WITH 2 TO 3 INCHES EXTENDING EAST INTO GRANT AND MORTON
COUNTIES. SNOW TOTALS TAPER TO AN INCH OR TWO EAST OF THE MISSOURI
RIVER. THE NORTHERN EXTENT OF THE HEAVIER SNOW REMAINS ALONG AND
SOUTH OF LAKE SAKAKAWEA...WEST OF THE MISSOURI...THEN ALONG AND
SOUTH OF THE I94 CORRIDOR EAST OF THE MISSOURI. ALTHOUGH SIGNIFICANT
DIFFERENCES STILL REMAIN...FEEL CONFIDENT ENOUGH THAT A WINTER
WEATHER ADVISORY IS WARRANTED OVER THE SOUTHWEST AND WEST CENTRAL.
CONFIDENCE WANES AS YOU GO EAST...BUT WILL EXTEND THE ADVISORY
EAST TO COVER MOST OF THE AREA WEST OF THE MISSOURI AND SOUTH OF THE
LAKE.
AT THIS TIME IT APPEARS THAT THERE SHOULD BE A QUICK TRANSITION FROM
RAIN TO SNOW AS COLD AIR RUSHES SOUTH LATE SUNDAY NIGHT. HOWEVER...A
PERIOD OF MIXED PRECIPITATION CANNOT BE RULED OUT BEFORE THE COLD
AIR IS FIRMLY ENTRENCHED OVER THE AREA BY MONDAY MORNING. AS THE
CANADIAN HIGH DROPS SOUTH WE SHOULD SEE A NICE ISALLOBARIC COMPONENT
MOVE ACROSS THE WEST AND SOUTH CENTRAL ON MONDAY RESULTING IN
SUSTAINED WINDS OF 15 TO 20 MPH AND GUST OF 25 TO 30 MPH. ALTHOUGH
THERE IS NO LOOSE SNOW...WINDS WILL BE STRONG ENOUGH FOR SOME
BLOWING SNOW AS IT FALLS. THUS WILL MAKE THE ADVISORY FOR SNOW AND
BLOWING SNOW...LASTING FROM LATE SUNDAY NIGHT THROUGH LATE MONDAY
NIGHT.
AS THE MAIN UPPER LOW MOVES ONTO THE PLAINS ON TUESDAY...COLD HIGH
PRESSURE OVER SASKATCHEWAN INTO NORTH DAKOTA SHOULD KEEP THE
NORTHERN EXTEND OF THE SYSTEM RIGHT ALONG THE SOUTH DAKOTA BORDER
WITH ANY SIGNIFICANT PRECIPITATION REMAINING SOUTH OF THE STATE.
THEN AS THE SYSTEM BEGINS TO EJECT NORTHEAST TUESDAY NIGHT THE
PRECIPITATION SHIELD TRIES TO PUSH A BIT FARTHER NORTH AND MAY CLIP
THE FAR SOUTH AND SOUTHEAST COUNTIES WITH LIGHT SNOW. AT THIS TIME
WE ARE KEEPING HIGH CHANCE POPS ALONG THE SOUTH DAKOTA
BORDER...TAPERING TO SLIGHT CHANCE POPS AROUND INTERSTATE 94. THE
NORTHERN HALF OF THE CWA IS EXPECTED TO REMAIN DRY TUESDAY AND
TUESDAY NIGHT. TEMPERATURES DURING THIS PERIOD...MONDAY THROUGH
WEDNESDAY...WILL BE BELOW NORMAL WITH 20S NORTH TO 30S SOUTH. WE DO
SEE SOME SLIGHT WARMING BY AROUND THURSDAY AS THE SYSTEM EXITS TO
OUR EAST...BUT A PROGRESSIVE NORTHWEST FLOW WILL BRING A SERIES OF
UPPER LEVEL WAVES INTO THE AREA LATE IN THE WEEK KEEPING OUR WEATHER
UNSETTLED WITH TEMPERATURES NEAR OR BELOW NORMAL.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 329 AM CDT SUN APR 7 2013
WIDESPREAD STRATUS REMAINS OVER THE REGION THIS MORNING. THE MAIN
HAZARDS TO AVIATION INCLUDE THE MVFR/IFR CONDITIONS ASSOCIATED
WITH THE STRATUS...AND FREEZING RAIN AND MIXED PRECIPITATION
EXPECTED TO MOVE INTO WESTERN NORTH DAKOTA AND THEN SPREAD EAST
THROUGHOUT THE DAY. AS TEMPERATURES WARM AT KDIK...LIGHT FREEZING
RAIN WILL GIVE WAY TO LIGHT RAIN. A BRIEF BREAK IN PRECIPITATION
WILL BE POSSIBLE LATER THIS AFTERNOON...BEFORE THE NEXT ROUND OF
LIGHT RAIN AND MIXED PRECIPITATION ARRIVES SUNDAY EVENING AND
MONDAY MORNING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 1 AM CDT /MIDNIGHT MDT/ MONDAY TO 1
AM CDT /MIDNIGHT MDT/ TUESDAY FOR NDZ017>020-031>034-040>044.
FREEZING RAIN ADVISORY FROM 7 AM THIS MORNING TO 1 PM CDT THIS
AFTERNOON FOR NDZ002-010-019>021-034-035-046.
FREEZING RAIN ADVISORY UNTIL 11 AM CDT /10 AM MDT/ THIS MORNING
FOR NDZ001-009-017-018-033-041.
FREEZING RAIN ADVISORY FROM 11 AM THIS MORNING TO 7 PM CDT THIS
EVENING FOR NDZ003-011-012-022-023-036-037-047-048-050-051.
&&
$$
SHORT TERM...LTH
LONG TERM...TWH
AVIATION...LTH
AREA FORECAST DISCUSSION
NWS PORTLAND OR
305 AM PDT SUN APR 7 2013
.SYNOPSIS...A DEEPENING LOW PRESSURE SYSTEM IS MOVING ONSHORE NEAR
THE LONG BEACH PENINSULA OF SOUTHERN WA...BRINGING INCREASINGLY
STRONG WINDS TO THE OREGON COAST. GUSTY WINDS ARE BEGINNING TO SPREAD
ACROSS THE COAST RANGE AND INTO THE WILLAMETTE VALLEY...THIS WILL BE
THE TREND FOR THIS MORNING. SNOW IS FALLING IN THE HIGH CASCADES AND
WILL INCREASE TODAY AS FLOW TURNS WESTERLY. SNOW LEVELS WILL BE NEAR
OR BELOW THE CASCADE PASSES. ELSEWHERE RAIN WILL TAPER TO SHOWERS AND
SCATTERED THUNDERSTORMS AS A COLD UPPER LEVEL LOW MOVES ONSHORE THIS
AFTERNOON AND EVENING. THUNDERSTORMS MAY HAVE SMALL HAIL AND GUSTY
WINDS THROUGH THIS EVENING. SHOWERS WILL LINGER INTO MONDAY...THEN
TAPER OFF AS A RIDGE OF HIGH PRESSURE BUILDS FOR A DRIER AND WARMER
WEATHER TUESDAY. ANOTHER SYSTEM IS EXPECTED TO BRING MORE RAIN
WEDNESDAY.
&&
.SHORT TERM...TODAY THROUGH WEDNESDAY...THE CIRCULATION OF A
DEVELOPING LOW PRESSURE SYSTEM IS APPARENT ON KLGX/KRTX NWS DOPPLER
RADARS...PRESENTLY MOVING INTO THE LONG BEACH PENINSULA OF PACIFIC
COUNTY WA. THIS SYSTEM IS A LITTLE FARTHER NORTH AND A LITTLE
STRONGER THAN MOST MODELS SUGGESTED...WITH BUOY 46029 AND HOME
WEATHER STATIONS ON THE LONG BEACH PENINSULA REASONABLY SUGGESTING A
CENTRAL PRESSURE OF ABOUT 997 MB.
LATEST RUNS OF THE HRRR 3 KM MODEL DEPICT AN ELONGATED SHAPE TO THE
LOW... EXTENDING FROM THE S WA COAST SOUTHWESTWARD. THIS APPEARS
REASONABLE CONSIDERING THE WIND FIELD APPARENT ALONG THE COAST AND
SHOWN BY BUOYS IN THE COASTAL WATERS. THUS THERE MAY BE A BIT OF A
LULL TO THE WIND ALONG OUR NORTH COAST ZONES INITIALLY AS THE LOW
MOVES ONSHORE. BEHIND THE LOW...HRRR AND NAM HAVE BEEN VERY INSISTENT
ON A STRONG SURGE OF NW-W WIND IN THE BENT BACK OCCLUSION ON THE BACK
SIDE OF THE LOW. THIS WILL CAUSE A SURGE OF WIND FROM THE SW-W AND
EVENTUALLY NW WIND ALONG THE COAST IN THE COMING HOURS...SO IF ONE
SURGE OF WIND EASES IT DOES NOT NECESSARILY MEAN THE EVENT IS OVER.
THE CONSEQUENCES OF THE STRONGER LOW AND MORE NORTHERN TRACK WILL BE
INCREASED CONFIDENCE IN THE WIND ADVISORY FOR THE WILLAMETTE VALLEY
AND A LITTLE CONCERN THE STRONGER WINDS MAY PUSH INTO KELSO/LONGVIEW.
ADDITIONALLY...IT APPEARS A LOW-END HIGH WIND WARNING WILL VERIFY FOR
THE OREGON COAST AND COAST RANGE. WILL LEAVE ALL WIND HIGHLIGHTS AS
IS FOR NOW...THE OVERALL FORECAST LOOKS PRETTY WELL ON TRACK WITH
GUSTS 50-60 MPH WIDESPREAD FOR THE OR COAST AND LOCAL GUSTS TO 70 MPH
FOR THE MOST EXPOSED AREAS. SOUTH WIND GUSTS 25-35 MPH ARE ALREADY
DEVELOPING IN THE TUALATIN AND CENTRAL/SOUTH WILLAMETTE VALLEY. THESE
WILL GET STRONGER WITH 35-45 MPH GUSTS LIKELY TO DEVELOP FOR THE
WILLAMETTE VALLEY AND CLARK COUNTY WITHIN THE NEXT COUPLE HOURS.AS
PRESSURE RISES BEGIN IN EARNEST.
ASIDE FROM TRACKING THE LOW AND ASSOCIATED WIND PATTERN THE OTHER
FORECAST CHALLENGES OF THE DAY ARE...1. HOW PROLIFIC THUNDERSTORMS
WILL BE TODAY AND 2. HOW MUCH SNOW WILL FALL IN THE CASCADES.
THUNDERSTORMS...NAM BUFR SOUNDINGS SHOW A VERY STRONG DIRECTIONAL
SHEAR PROFILE WILL QUICKLY BECOME UNIDIRECTIONAL AS THE MORNING
PROGRESSES. HOWEVER A SECONDARY TROUGH IS EXPECTED TO MOVE IN LATER
THIS AFTERNOON AS THE COLD POOL ALOFT DIPS INTO WESTERN WA AND
NORTHWEST OREGON. LAPSE RATES LOOK MARGINAL FOR THUNDERSTORMS...BUT
IMPROVE AS THE AFTERNOON PROGRESSES. WITH SFC TEMPS IN THE LOW 50S WE
SHOULD BE ABLE TO MUSTER ABOUT 400-600 J/KG OF CAPE AND LIFTED
INDICES OF -2 TO -3 DEG C...WHICH WITH LITTLE TO NO CAPPING WOULD BE
PLENTY TO SUGGEST DEEP CONVECTION. SO WE INCREASED THUNDERSTORM
COVERAGE TO SCATTERED AS THIS SETUP IS ABOUT AS GOOD AS IT GETS IN A
POST-FRONTAL ENVIRONMENT. WITH 25-35 KT WESTERLY FLOW AT 850 MB ANY
ORGANIZED THUNDERSTORMS MAY MIX DOWN GUSTY WINDS. TERRAIN DRIVEN FLOW
MAY PRODUCE A LITTLE DIRECTIONAL SHEAR AS WELL...WHICH COULD LEAD TO
SOME WEAK ROTATION WITH THE STRONGER CELLS. ANY THUNDERSTORMS SHOULD
DIE DOWN QUICKLY AFTER SUNSET AS SFC TEMPS COOL AND THE AIR MASS
STABILIZES.
SNOW...SNOW AMOUNTS IN THE CASCADES HAVE THUS FAR BEEN UNIMPRESSIVE
WITH ABOUT 2-4 INCHES MOST LOCATIONS ABOVE 4000 FT. HOWEVER AS LOW
PRESSURE CROSSES THE CASCADES FLOW WILL BECOME MORE OROGRAPHIC. WEST
WINDS 25-35 KT AT 850 MB WILL ENHANCE SNOWFALL IN THE CASCADES...SO A
GOOD 6-12 INCHES LOOK LIKELY ABOVE 4500-5000 FT BY LATER TONIGHT.
SNOW LEVELS WILL BE LOWERING...SO THE PASSES COULD GET A FEW SLUSHY
INCHES OF SNOW THIS AFTERNOON AND TONIGHT. SNOW WILL GRADUALLY TAPER
OFF MONDAY.
A WEAK SHORTWAVE MAY KEEP A FEW SHOWERS IN THE REGION THROUGH MONDAY.
HOWEVER IT APPEARS WE WILL DRY OUT BY TUESDAY AS RIDGING BUILDS INTO
OREGON AND WASHINGTON. 850 MB TEMPS REBOUND TO ABOUT +5 DEG C TUE
AFTERNOON...PROBABLY ENOUGH FOR LOWER 60S IN THE VALLEYS. THIS RIDGE
PROBABLY WILL NOT BE STRONG TO KEEP CLOUD COVER TO OUR NORTH...AND
THE NORTH COAST MAY GET BRUSHED WITH SOME RAIN OR DRIZZLE TUE/TUE
NIGHT. THE RIDGE COLLAPSES WEDNESDAY...ALLOWING ANOTHER FRONT TO SAG
SOUTH AND SPREAD RAIN INTO OUR FORECAST AREA. WEAGLE
.LONG TERM...MAIN CHANGES TO THE EXTENDED FORECAST WERE TO INCREASE
POPS SLIGHTLY AS IT APPEARS WE REMAIN IN A ZONAL AND PROGRESSIVE
PATTERN AFTER WEDNESDAYS FRONTAL SYSTEM. THIS MEANS NEAR OR SLIGHTLY
BELOW NORMAL TEMPERATURES WITH RAIN AT TIMES FOR THE LATE WEEK
PERIOD. WEAGLE
&&
.AVIATION...EXPECT A MIX OF IFR AND MVFR CONDITIONS ALONG THE COAST
THIS MORNING WITH A MIX OF MVFR AND VFR CONDITIONS FOR THE INTERIOR
TAF SITES. A BURST OF HIGHER SOUTH WINDS SHOULD OCCUR FOR MOST TAF
SITES IN THE NEXT 1 TO 4 HOURS...BEFORE SLOWLY RELAXING THROUGH THE
DAY. CONDITIONS SHOULD BEGIN TO IMPROVE ON THE WHOLE AREA WIDE THIS
AFTERNOON AS THE AIRMASS DESTABILIZES. HOWEVER...WITH THE AIRMASS
DESTABILIZING...EXPECT SHOWERS TO PULSE UP AND DOWN...SOME OF WHICH
WILL PRODUCE BRIEF HEAVY RAIN...SMALL HAIL AND LIGHTNING. THIS
ACTIVITY SHOULD BEGIN TO WANE DURING THE EVENING HOURS. A RELATIVELY
UNSTABLE AIRMASS WILL PERSIST INTO TONIGHT KEEPING MANY LOCATIONS
VFR...WITH SOME PATCHY MVFR CIGS.
KPDX AND APPROACHES...EXPECT A MIX OF MVFR AND VFR CONDITIONS THIS
MORNING TO TRANSITION PRIMARILY TO VFR AROUND MIDDAY. EAST WINDS
SHOULD SHIFT TO EAST...AND GUST PRETTY STRONGLY OUT OF THE SOUTH
STARTING AROUND 5 AM. THERE IS A CHANCE FOR A THUNDERSTORM TO
IMPACT THE TERMINAL THIS AFTERNOON AND EARLY EVENING. OTHERWISE...A
RELATIVELY UNSTABLE AIRMASS TONIGHT SHOULD KEEP CIGS HIGH END MVFR
OR VFR OVERNIGHT. /NEUMAN
&&
.MARINE...AN ELONGATED BOOMERANG LOOKING LOW PRESSURE IS CURRENTLY
PUSHING ASHORE NEAR THE COLUMBIA RIVER MOUTH. GALE FORCE WINDS
HAVE PRIMARILY REMAINED SOUTH OF THE LOW PRESSURE...ALTHOUGH
EASTERLY WINDS REACHED INTO GALE FORCE BRIEFLY AT BUOY 29 EARLIER
THIS MORNING.
A HIGH RESOLUTION MODEL CONTINUES TO INSIST A BURST OF HIGHER
WINDS ON THE BACKSIDE OF THE LOW PRESSURE WILL SWING INTO THE
CENTRAL OREGON COAST AROUND 4 AM. AS A RESULT...WINDS MAY
TEMPORARILY SPIKE IN THE NEXT HOUR OR TWO ACROSS THE NORTH CENTRAL
OREGON WATERS BEFORE BEGINNING TO SUBSIDE BETWEEN 5 AM AND 8 AM.
EXPECT WIND GUSTS OF 20 TO 30 KT TO CONTINUE AREA WIDE TODAY WITH
SEAS REMAINING ABOVE 10 FT.
HIGH PRESSURE WILL THEN BEGIN TO BUILD INTO THE REGION
MONDAY...CAUSING WINDS TO SUBSIDE AND SEAS TO RELAX. THIS SHOULD
CONTINUE UNTIL MIDDAY TUESDAY WHEN A WEAKENING FRONT BRINGS A
BURST OF 20 TO 25 KT WINDS TO PRIMARILY THE NORTHERN WATERS.
ANOTHER STORM SYSTEM WILL SLIDE BY TO OUR NORTH WEDNESDAY...CAUSING
SOUTH WINDS TO INCREASE ONCE AGAIN AND SEAS TO BRIEFLY POP UP NEAR
10 FT.
HIGH PRESSURE SHOULD THEN CAUSE WINDS AND SEAS TO RELAX LATE IN
THE WORK WEEK. /NEUMAN
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL 11 PM PDT THIS EVENING FOR
CASCADES IN LANE COUNTY-NORTHERN OREGON CASCADES.
WIND ADVISORY UNTIL 11 AM PDT THIS MORNING FOR CENTRAL
WILLAMETTE VALLEY-GREATER PORTLAND METRO AREA-SOUTH
WILLAMETTE VALLEY.
HIGH WIND WARNING UNTIL 11 AM PDT THIS MORNING FOR CENTRAL COAST
RANGE OF WESTERN OREGON-COAST RANGE OF NORTHWEST OREGON.
HIGH WIND WARNING UNTIL 8 AM PDT THIS MORNING FOR CENTRAL OREGON
COAST-NORTH OREGON COAST.
WA...WINTER WEATHER ADVISORY UNTIL 11 PM PDT THIS EVENING FOR SOUTH
WASHINGTON CASCADES.
WIND ADVISORY UNTIL 11 AM PDT THIS MORNING FOR GREATER VANCOUVER
AREA.
PZ...GALE WARNING UNTIL 8 AM PDT THIS MORNING FOR COASTAL WATERS FROM
CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 10 PM
PDT THIS EVENING.
&&
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
342 AM CDT SUN APR 7 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 342 AM CDT SUN APR 7 2013
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT
ANALYSIS SHOWED UPPER TROUGHING APPROACHING THE PACIFIC
NORTHWEST...WEAK RIDGING OVER THE NORTHERN U.S. ROCKIES INTO THE
DAKOTAS...AND A SHORTWAVE TROUGH OVER EASTERN WISCONSIN. ALSO OF
NOTE ON WATER VAPOR WERE A PAIR OF SHORTWAVES MOVING THROUGH THE
WEAK RIDGING...ONE IN SOUTH CENTRAL WYOMING AND THE OTHER IN
NORTHWEST COLORADO. THE FORECAST AREA LIES IN SUBSIDENCE IN THE
WAKE OF THE EASTERN WISCONSIN SHORTWAVE TROUGH...SEEN AS AN
INVERSION BETWEEN 775 AND 850MB ON THE 00Z MPX SOUNDING. THIS
INVERSION WAS ALSO SATURATED... REFLECTED TOO BY PLENTY OF STRATUS
CLOUDS ON 11-3.9UM IMAGERY FROM THE EASTERN DAKOTAS INTO THE
FORECAST AREA. COOLER AIR HAS BEEN FILTERING IN BEHIND THE
SHORTWAVE AS WELL WITH 850MB TEMPS NOW DOWN TO +2 TO -3C ACROSS
THE FORECAST AREA PER RAP ANALYSIS...COLDEST OVER CENTRAL
WISCONSIN. AT THE SURFACE...HIGH PRESSURE WAS SEEN DROPPING SOUTH
INTO WESTERN MINNESOTA...IN THE WAKE OF LOW PRESSURE OVER NORTHERN
LAKE MICHIGAN AND ITS COLD FRONT WHICH EXTENDS SOUTHWEST TO KANSAS
CITY.
A PATTERN CHANGE IS FORECAST TO OCCUR ALOFT DURING THE NEXT 24 HOURS
AS THE UPPER TROUGH SEEN OFF THE PACIFIC NORTHWEST SHARPLY DIGS
SOUTH INTO CALIFORNIA AND NEVADA. IN RESPONSE...RIDGING WILL BUILD
DOWNSTREAM...ADJUSTING THE UPPER LEVEL FLOW TO SOUTHWESTERLY OVER
THE FORECAST AREA. THIS MEANS THAT THE RECENT LOW LEVEL COLD
ADVECTION WILL COME TO AN END SHORTLY...WITH WARM ADVECTION PROGGED
TO BEGIN BETWEEN 12-18Z TODAY AND CONTINUE THROUGH TONIGHT. IN
ADDITION...MODELS HAVE BEEN CONSISTENT IN SHOWING THE PAIR OF
SHORTWAVES SEEN IN WYOMING AND COLORADO TO AFFECT THE FORECAST AREA
LATE TONIGHT AS THEY RIDE THROUGH THE SOUTHWEST FLOW.
THE FIRST TWO ISSUES FOR THE SHORT TERM PERIOD ARE THE CLOUDS AND
HIGH TEMPERATURES TODAY. THE PRESENT STRATUS DECK DOES HAVE SOME
HOLES IN IT ON ITS SOUTHERN SIDE. THESE HOLES SHOULD EXPAND THROUGH
THE MORNING AS DIURNAL MIXING COMMENCES. 07.00Z NAM LOW LEVEL RH
FIELDS...WHICH GENERALLY TEND PESSIMISTIC...ALSO SUGGEST THAT THE
STRATUS DECK WILL MOSTLY MIX OUT BY 18Z SOUTH OF US HIGHWAY 10.
LATER IN THE AFTERNOON...SAY 21Z AND AFTER...MID AND HIGH CLOUDS
CURRENTLY SPREADING INTO THE PLAINS STATES ARE PROGGED TO MOVE INTO
THE FORECAST AREA. THUS WE SHOULD SEE AT LEAST A FEW HOURS OF MOSTLY
SUNNY SKIES TODAY. WITH 850MB TEMPS CLIMBING TO 0C NORTH AND 6C
SOUTH BY 18Z...ANTICIPATING THAT MOST LOCATIONS MINUS NORTH OF
HIGHWAY 10 WHERE MORE CLOUDS AND SNOW EXIST WILL CLIMB INTO THE 50S.
WARMEST TEMPERATURES...APPROACHING 60...ARE EXPECTED IN THE FAR
SOUTH.
THE NEXT ISSUE FOR THE SHORT TERM PERIOD IS THE POTENTIAL FOR
PRECIPITATION VERY LATE THIS AFTERNOON INTO TONIGHT...DUE TO THE
WARM ADVECTION PATTERN AND THE APPROACH OF THE PAIR OF SHORTWAVES.
THE 07.00Z GFS/06.12Z ECMWF ALREADY SHOW HINTS OF WARM ADVECTION /
ISENTROPICALLY INDUCED PRECIPITATION AFFECTING FAR WESTERN PORTIONS
OF THE FORECAST AREA BETWEEN 21-00Z TODAY. THINKING THIS MIGHT BE A
BIT FAST...WITH THE 07.00Z NAM/REGIONAL CANADIAN/HIRES-ARW AND
07.03Z SREF ALL SLOWER. THUS...PLAN ON KEEPING CONDITIONS DRY TIL
00Z. AS WE HEAD THROUGH TONIGHT...THERE IS A STRONG CONSENSUS
AMONGST ALL MODEL GUIDANCE OF A PRECIPITATION SPLIT. THE NORTHERN
AREA TRACKS FROM NORTHWEST IA/SOUTHERN MN INTO NORTHWEST
WISCONSIN. THE SOUTHERN AREA TRACKS FROM NORTHERN MISSOURI INTO
SOUTHEAST IA AND NORTHWEST IL. THIS SPLIT APPEARS TO BE A RESULT
OF HOW THE PAIR OF SHORTWAVES APPROACHING THE FORECAST AREA LATE
TONIGHT INTERACT WITH THE ISENTROPIC LIFT PATTERN IN PLACE. 850MB
MOISTURE TRANSPORT FIELDS SHOW THE SPLIT INTERACTION WITH THE
ISENTROPIC LIFT PATTERN NICELY. IN ADDITION...THERE ARE OTHER
SUPPORTING FEATURES. FOR EXAMPLE...THE NORTHERN AREA BECOMES
INFLUENECED BY A DEVELOPING AND STRENGTHENING UPPER JET STREAK
OVER UPPER MICHIGAN...PLACING IT IN THE FAVORABLE RIGHT ENTRANCE
REGION. MEANWHILE...THE SOUTHERN AREA HAS A STRONG LOW TO MID-
LEVEL FRONTOGENESIS FEATURE ALONG THE PRESENT COLD FRONT NEAR
I-70...WHICH FOR ALL INTENSIVE PUPROSES TURNS INTO A STATIONARY
BOUNDARY. SO FOR THE FORECAST...THIS WELL AGREED UPON SPLIT
PRECIPITATION SCENARIO POSES A PROBLEM FROM WHAT WE HAD GOING
PREVIOUSLY. HAVE ADJUSTED PRECIPITATION CHANCES AND QPF QUITE A
BIT LOWER SOUTH OF I-90...SINCE THIS AREA WILL BE ON THE SUBSIDENT
SIDE OF THE F-GEN CIRCULATION. NOTE THAT MODELS LIKE THE 07.00Z
GFS/REGIONAL CANADIAN EVEN SUGGEST THAT SOME LOCATIONS ACROSS
NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN COULD END UP DRY.
REGARDING PRECIPITATION TYPE...ALL OF IT SHOULD FALL AS RAIN WITH
WET-BULB ZERO HEIGHTS PROGGED WELL ABOVE 2000 FT. THE PREVIOUS
FORECAST INTRODUCED A CHANCE FOR THUNDER AND THIS STILL LOOKS
REASONABLE AFTER MIDNIGHT...WITH POTENTIAL FOR A FEW HUNDERED J/KG
OF SKINNY CAPE LIFTED FROM 850MB.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 342 AM CDT SUN APR 7 2013
OVERALL MUCH OF THE LONG TERM PERIOD LOOKS ACTIVE...THANKS TO THAT
TROUGH DIGGING INTO CALIFORNIA AND NEVADA TONIGHT. QUITE A FEW
DETAILS TO NOTE.
ON MONDAY...THE PAIR OF SHORTWAVES ARE PROGGED TO SHIFT EAST INTO
MICHIGAN DURING THE AFTERNOON...TAKING THE BULK OF THE SPLIT
PRECIPITATION TONIGHT WITH THEM. HOWEVER...THE STORY DOES NOT END
THERE. THE FOCUS TURNS TO THE FRONTAL BOUNDARY NEAR I-70...WHICH BY
ALL MODELS IS SUGGESTED TO LIFT NORTH INTO CENTRAL AND PERHAPS
NORTHERN IA DURING THE AFTERNOON. THE LIFTING NORTH IS A RESULT OF
THE UPPER TROUGHING DEEPENING AND DIGGING INTO THE FOUR CORNERS
REGION...ENHANCING THE WARM ADVECTION DOWNSTREAM. THE 07.00Z
REGIONAL CANADIAN AND NAM SUGGEST THERE IS POTENTIAL FOR SURFACE
BASED CONVECTION TO FIRE ON THIS FRONT. THE 07.00Z GFS...ON THE
OTHER HAND...HAS A FARTHER SOUTH FRONT AND KEEPS THINGS MORE CAPPED.
HOWEVER...ALL THREE MODELS INCLUDING THE 06.12Z ECMWF DEPICT
POTENTIAL FOR FRONTOGENETICALY INDUCED PRECIPITATION NORTH OF THE
FRONTAL BOUNDARY. THUS...A NEED CONTINUES FOR CHANCES OF SHOWERS
ALONG WITH THE THUNDERSTORM MENTION IN THE EVENT THE REGIONAL
CANADIAN/NAM PAN OUT. IF THE REGIONAL CANADIAN/NAM PAN OUT...
CERTAINLY COULD NOT RULE OUT SOME SEVERE POTENTIAL GIVEN 0-6 KM
SHEAR UPWARS OF 45-50 KT. HOWEVER...IT SEEMS LIKE THE BETTER
INSTABILITY IS WEST OF THE FORECAST AREA...THUS KEEPING THE BULK OF
THE SEVERE POTENTIAL TO THE WEST. SPC DAY 2 SEVERE PROBABILITIES
DEPICT THIS AS WELL. DEFINITELY SOMETHING TO KEEP AN EYE
ON....THOUGH. TEMPERATURE FORECAST IS TRICKY AS IT DEPENDS ON THE
FRONTAL POSITION. A NAM/REGIONAL CANADIAN OR EVEN ECMWF SOLUTION
WOULD ALLOW FOR HIGHS IN THE 60S TO POSSIBLY 70 ALONG/SOUTH OF I-90.
THE GFS IS A LITTLE COOLER BUT STILL HAS HIGHS IN THE 60S SOUTH OF
I-90. RAISED HIGHS 5 DEGREES OR SO TO COME BETTER IN AGREEMENT WITH
ALL 07.00Z GUIDANCE...BUT THEY MAY NEED TO BE RAISED MORE...
ESPECIALLY IF MORE SUN OCCURS IN THE AFTERNOON.
THINGS GET MORE INTERESTING HEADING INTO THE MONDAY NIGHT THROUGH
THURSDAY TIME PERIOD. DURING THIS PERIOD...ALL MODELS HAVE THE DEEP
UPPER TROUGH OVER THE FOUR CORNERS SLOWLY LIFTING TO THE
EAST-NORTHEAST. MEANWHILE...AT THE SAME TIME THERE IS A DEEP UPPER
TROUGH HANGING AROUND THE HUDSON BAY INTO NORTHERN ONTARIO AREA...
HELPING TO HOLD AN UPPER JET STREAK IN PLACE OVER THE NORTHERN GREAT
LAKES. THIS MEANS THE FORECAST AREA IS GOING TO BE PLACED IN THE
FAVORABLE RIGHT ENTRANCE REGION UNTIL THE UPPER TROUGH MOVES IN.
MONDAY NIGHT FOR THE MOST PART LOOKS QUIET...WITH ANY SHOWERS AND
POSSIBLE THUNDERSTORMS IN THE EVENING DISSIPATING WITH LOSS OF
DAYTIME HEATING. THE FRONTAL BOUNDARY...IF IT IS NEARBY...LOOKS TO
SLOWLY DROP SOUTH MONDAY NIGHT FORCED BY THAT DEEP UPPER TROUGH TO
OUR NORTH. IT APPEARS THERE MAY BE A MASS OF LOW LEVEL STRATUS THAT
MOVES IN BEHIND THE FRONT...AND WITH LOW LEVEL FRONTOGENESIS BEHIND
THE FRONT WE COULD DEAL WITH SOME LIGHT RAIN OR DRIZZLE.
PRECIPITATION CHANCES DEFINITELY GO ON THE INCREASE FROM SOUTHWEST
TO NORTHEAST THROUGH THE DAY TUESDAY AND INTO TUESDAY NIGHT...IN
RESPONSE TO ISENTROPIC LIFT STRENGTHENING DOWNSTREAM OF THE UPPER
TROUGH PUSHING TO THE EAST-NORTHEAST. SOME CONCERN FOR SOME HEAVIER
RAIN TUESDAY NIGHT...ESPECIALLY ACROSS THE SOUTH...AS PRECIPITABLE
WATER VALUES INCREASE OVER 1 INCH AND SOME WEAK ELEVATED INSTABILITY
MOVES IN FOR THUNDERSTORMS. RAISED BOTH PRECIPITATION CHANCES AND
QPF FOR TUESDAY AND ESPECIALLY TUESDAY NIGHT GIVEN THE STRONG SIGNAL
AMONGST THE 07.00Z ECMWF/GFS/CANADIAN MODELS. FROM WEDNESDAY INTO
THURSDAY...THE CORE OF THE UPPER TROUGH IS PROGGED TO SLOWLY
APPROACH THE FORECAST AREA. AS THIS OCCURS...THE FORECAST AREA
EVENTUALLY ENDS UP ON THE NORTHWEST / COLD SIDE OF A SURFACE LOW
TRACKING TO OUR SOUTH...PLACING THE AREA INTO THE TROWAL AND COLD
CONVEYOR BELT REGION. GIVEN THE GOOD MODEL AGREEMENT AGAIN...RAISED
PRECIPITATION CHANCES UP DURING THIS PERIOD. IN ADDITION...WILL HAVE
TO WATCH FOR SOME SNOW ACCUMULATIONS COME WEDNESDAY NIGHT AND
THURSDAY AS 850MB TEMPS DROP TO -4 TO -8C BY 12Z THURSDAY.
IT SHOULD BE NOTED THAT THE 07.00Z NAM IS AN OUTLIER SOLUTION TO THE
ABOVE SCENARIO...PARTICULARLY FOR TUESDAY THROUGH WEDNESDAY...SINCE
IT EJECTS THE CORE OF THE SOUTHWESTERN TROUGH MUCH QUICKER AND LIFTS
IT FARTHER NORTH. THE NAM WAS DISCOUNTED GIVEN GOOD MODEL AGREEMENT
BETWEEN ALL OTHER MODELS. THE 07.03Z SREF LOOKS LIKE A COMPROMISE
BETWEEN THE NAM AND GFS...BUT THE SREF IS NAM-BIASED DUE TO AN
OVERWHELMING AMOUNT OF NAM MEMBERS. THUS...THE SREF WAS DISCOUNTED
AS WELL.
LOOKING FARTHER AHEAD...GOOD MODEL AGREEMENT EXISTS AMONGST THE
07.00Z ECMWF/GFS/CANADIAN ON BRINGING COLD CANADIAN HIGH PRESSURE
INTO THE AREA THURSDAY NIGHT THROUGH FRIDAY NIGHT. THIS SHOULD HELP
DRY THINGS OUT. LEFT A CONSENUS 20 PERCENT CHANCE OF PRECIPITATION
IN THURSDAY NIGHT...BUT THIS PERIOD MAY EVENTUALLY END UP DRY. WILL
NEED TO WATCH SOME OF THE LOW TEMPERATURES TOO FOR BOTH THURSDAY
NIGHT AND FRIDAY NIGHT...DEPENDING ON HOW MUCH FRESH SNOW WE PICK UP
AND FOR FRIDAY NIGHT HOW MUCH IS STILL ON THE GROUND. A WARM
ADVECTION PATTERN SETS UP FOR SATURDAY AHEAD OF NEW TROUGHING
DROPPING INTO THE NORTHERN ROCKIES. FOLLOWED THE CONSENSUS HERE OF
BRINGING SOME 20-30 PERCENT CHANCES OF PRECIPITATION ACROSS THE AREA
ON SATURDAY. NEED TO MAINTAIN A RAIN/SNOW MIX BECAUSE 850MB TEMPS
ARE STILL SLOW TO WARM...ESPECIALLY IN THE ECMWF WHERE IT KEEPS THEM
BELOW 0C THROUGH 00Z SUNDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1015 PM CDT SAT APR 6 2013
THERE WILL BE A DECREASE IN THE WINDS OVERNIGHT AS THE PRESSURE
GRADIENT SLACKENS. MVFR CIGS FROM 1500-2500 WILL CONTINUE...BUT SEE
SOME THREAT FOR SUB 1 KFT CIGS AT KRST. NOT CONFIDENT ENOUGH TO ADD
TO THE FORECAST...BUT TRENDS WILL BE WATCHED CLOSELY. THE LOW CIGS
WILL HANG INTO SUNDAY MORNING. BUFKIT SOUNDINGS VIA THE
RAP13/NAM/GFS ALL SUGGEST SOME MIXING BY 18Z...WHICH WOULD HELP
BREAK UP THE CLOUDS...INCREASING THE CHANCES FOR SCT CONDITIONS FOR
THE AFTERNOON. WILL STAY WITH THIS TREND.
MORE UPPER LEVEL ENERGY WILL SPIN ACROSS THE REGION SUNDAY
NIGHT/MON. CLOUDS WILL QUICKLY RETURN SUNDAY EVENING AS A
RESULT...WITH RAIN CHANCES MOVING IN BETWEEN 06-12Z MONDAY. THERE
MIGHT BE ENOUGH INSTABILITY/FORCING FOR AN ISOLATED
THUNDERSTORM...BUT NOT ENOUGH OF A CHANCE TO INCLUDE IN THE
FORECAST. IT SHOULD BE NOTED THAT THE NAM/GFS/ECMWF ALL SUGGEST THAT
THERE COULD BE TWO MAIN REGIONS FOR PCPN...WHICH WOULD GO NORTH AND
SOUTH OF THE TAF SITES. STILL WOULD BE ENOUGH FORCING FOR SOME -SHRA
CHANCES...BUT ACCUMS AND IMPACTS TO VSBYS WOULD BE MUCH LESS.
&&
.HYDROLOGY...
ISSUED AT 342 AM CDT SUN APR 7 2013
RIVER STATUS...
THE TREMPEALEAU RIVER NEAR DODGE WILL REMAIN ABOVE FLOOD STAGE AND
ALLOW FOR MINOR FLOODING TO CONTINUE THROUGH MONDAY MORNING.
MEANWHILE ON THE BLACK...ANOTHER BRIEF ICE JAM LOOKS LIKE IT MAY
HAVE FORMED AROUND NEILLSVILLE...WITH A SPIKE UP OF 4 FEET BUT STILL
WELL WITHIN THE RIVER BANK. DOWNSTREAM...SO FAR THE BLACK REMAINS
WITHIN THE RIVER BANK.
SNOW PACK...
RECENT COOPERATIVE OBSERVER REPORTS SHOW SNOW PACK IS MAINLY ALONG
AND NORTHEAST OF THE INTERSTATE 94 CORRIDOR WITH 2 TO 7 INCHES OF
SNOW DEPTH IN PLACES. THE DEEPEST SNOW PACK IS OVER THE NORTHERN
MOST PARTS OF TAYLOR WHERE AROUND A FOOT OF SNOW REMAINS ON THE
GROUND. SNOW WATER EQUIVALENT OF 1 TO 2 INCHES IS MAINLY NORTH OF
THE INTERSTATE 94 CORRIDOR WITH THE GREATEST SNOW WATER EQUIVALENT
OF 2 TO 4 INCHES IN NORTHERN TAYLOR COUNTY.
RAINFALL...
LESS RAINFALL IS ANTICIPATED TONIGHT INTO MONDAY THAN PREVIOUSLY
EXPECTED...WITH UPWARDS OF 1/4 TO 1/2 INCH NORTH OF I-90 AND LESS
THAN A 1/4 INCH TO THE SOUTH. WILL STILL NEED TO WATCH TUESDAY
THROUGH WEDNESDAY...THOUGH. BY WEDNESDAY MORNING...CURRENTLY
ANTICIPATING AMOUNTS BETWEEN 3/4 INCH AND 1.25 INCHES SOUTH OF
HIGHWAY 10 TO LESS THAN A 1/2 INCH TO THE NORTH. IF THE SYSTEM
BRINGING THIS RAIN SHIFTS FARTHER NORTH...THE HEAVY RAIN AREA WILL
SHIFT NORTH AS WELL...PLACING IT WHERE RAIN IS NOT NEEDED.
TEMPERATURES...
HIGHS TODAY ARE GOING TO BE COOLER...IN THE THE MIDDLE 40S/AROUND 50
NORTH OF I-94 AND IN THE 50S SOUTH OF THERE. WARMER CONDITIONS LOOK
ON TAP FOR MONDAY...WITH MOSTLY 50S NORTH OF I-94 AND 60S SOUTH.
TEMPERATURES THEN COOL INTO THE 40S FOR TUESDAY AND WEDNESDAY AND
POSSIBLY STRUGGLE TO GET TO 40 BY THURSDAY. THE TEMPERATURE MAY NOT
MATTER IN A FEW DAYS AS MOST OF THE SNOW PACK MAY BE GONE...UNTIL
POTENTIALL A SMALL SNOW PACK RE-ESTABLISHES ITSELF THURSDAY MORNING.
FROST DEPTH...
AS OF APRIL 4TH...FROST DEPTHS //WHICH ARE OBSERVED EVERY MONDAY AND
THURSDAY//ACROSS THE AREA REMAIN DEEP...AVERAGING AROUND 1 FOOT TO 1
1/2 FEET SOUTH OF I-90...AND UP TO 3 FEET ACROSS PORTIONS OF NORTH
CENTRAL WISCONSIN. THIS FROST WILL ACT TO ENHANCE RUNOFF OF SNOW
MELT AND PRECIPITATION INTO STREAMS AND RIVERS.
SUMMARY...
MAIN CONCERN FOR FLOODING REMAINS ALONG THE TREMPEALEAU AND BLACK
RIVERS AS SNOW MELT CONTINUES...ALONG WITH THE PERIODS OF RAINFALL
TONIGHT INTO MONDAY AS WELL AS TUESDAY THROUGH WEDNESDAY. HAVE A
HYDROLOGIC OUTLOOK PRODUCT OUT TO HEIGHTEN THIS AWARENESS. ALTHOUGH
THE TUESDAY INTO WEDNESDAY MODERATE TO HEAVY RAIN IS FORECAST MAINLY
SOUTH OF I-90...CURRENTLY THINKING THAT THE RIVERS SHOULD BE ABLE TO
ABSORB IT. A QUICK MODEL OF THE TURKEY RIVER AT GARBER USING THE
FORECAST QPF WOULD BRING THE RIVER ABOVE ACTION STAGE BUT NOT TO
FLOOD. THUS...DID NOT EXPAND THE HYDROLOGIC OUTLOOK SOUTH.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....RIECK
HYDROLOGY...AJ
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
1120 AM EDT SUN APR 7 2013
.UPDATE (REST OF TODAY AND TONIGHT)...
BENIGN WEATHER WILL CONTINUE THROUGH TONIGHT WITH DRY CONDITIONS AND
SEASONABLE TEMPERATURES.
15Z WATER VAPOR AND H4 RAP ANALYSIS SHOW AN UNAMPLIFIED UPPER LEVEL
PATTERN IN PLACE OVER THE CONUS OUTSIDE OF A FEW MINOR SHORTWAVE
"KINKS" IN THE FLOW. ZONAL FLOW IS IN PLACE OVER THE NORTHERN GULF
COAST AND FLORIDA PENINSULA AND WILL HOLD FOR AT LEAST THE NEXT 24
HOURS. ONE VERY MINOR IMPULSE WITHIN THE ZONAL FLOW IS LOCATED OVER
THE CENTRAL/EASTERN GULF AND WILL PASS OVER THIS EVENING/TONIGHT. WE
HAVE SEEN A FEW HIGH LEVEL CIRRUS OUT AHEAD OF THIS FEATURE...
HOWEVER AS IT APPROACHES...THE SYNOPTIC SUPPORT FOR THIS CIRRUS IS
ALREADY BEGINNING TO PASS BY.
AT THE SURFACE...HIGH PRESSURE EXTENDS DOWN THE EASTERN SEABOARD AND
CONTINUES TO RIDGE ALL THE WAY TO THE FL PENINSULA AND
CENTRAL/EASTERN GULF. GRADIENT AROUND THIS RIDGE IS PROVIDING A
GENERAL EASTERLY WIND PATTERN. SIMILAR TO SATURDAY...STILL HAVE A
RATHER MOIST LAYER SEEN ON TIME HEIGHT/CROSS SECTION ANALYSIS
BETWEEN AROUND 950-985MB. THE 12Z KTBW SOUNDING PROFILE CONFIRMS
THIS NWP FORECAST. WITH THE MOISTURE IN PLACE...AS DIURNAL HEATING
CONTINUES TO MIX UP INTO THE COLUMN WE SHOULD AGAIN SEE A SHALLOW
SCT-BKN CU FIELD EXPANDING ACROSS THE PENINSULA FROM EAST TO WEST
DURING THE NEXT SEVERAL HOURS.
MIXED ON SATURDAY TO AROUND 800MB PER 00Z KTBW SOUNDING. EXPECT
SIMILAR MIXING TODAY...WHICH WITH 800-850MB TEMPS AROUND 9-10C WILL
MIX DOWN TO HIGH TEMPERATURES IN THE LOWER 80S FOR MANY
LOCATIONS...EVEN SOME MIDDLE 80S FOR THE FAR SOUTHERN ZONES WHERE
LOW LEVEL COLUMN IS EVEN WARMER. THE STRONG TERRESTRIAL HEATING
SHOULD FORCE AN ONSHORE COMPONENT SEA-BREEZE TO DEVELOP DURING THE
EARLY AFTERNOON...AND THIS WILL KEEP THE BEACHES SEVERAL DEGREES
COOLER WITH THE FLOW OFF THE SHELF WATERS.
QUIET AND SEASONABLE OVERNIGHT PERIOD ON TAP. MOSTLY CLEAR SKIES
EXPECTED WITH TEMPERATURES DROPPING TO THE MIDDLE AND UPPER 50S FOR
MANY INLAND LOCATIONS BY SUNRISE...AND HOLDING IN THE 60S AT THE
COAST FROM PINELLAS COUNTY SOUTHWARD ALONG THE SUN COAST. ENJOY!
&&
.AVIATION...
VFR CONDITIONS UNDER SCT CU/SC AND OCNL BKN CIRRUS. EAST AND SE WINDS
SHIFT TO WESTERLY AT COASTAL TERMINALS IN THE AFTERNOON...AT 10KT OR
LESS.
&&
.MARINE...
THE EASTERN GULF OF MEXICO WILL REMAIN ON THE SOUTHERN SIDE OF A
RIDGE AXIS EXTENDING OFF THE GA/SC COAST THROUGH THE NEXT SEVERAL
DAYS. RESULTING GRADIENT WILL PROVIDE A GENERAL EASTERLY FLOW TO THE
REGION...HOWEVER MARINERS SHOULD ANTICIPATE WINDS BECOMING LOCALLY
ONSHORE THE NEXT COUPLE OF AFTERNOON NEAR THE COAST WITH THE
DEVELOPMENT OF THE SEA-BREEZE. THE NEXT FRONT WILL NOT APPROACH THE
REGION UNTIL THE LATTER PORTION OF THE WEEK WITH SOUTHEAST AND SOUTH
WINDS INCREASING AHEAD OF THIS SYSTEM.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 79 63 83 65 / 0 10 0 0
FMY 82 63 85 63 / 10 0 0 0
GIF 82 61 85 62 / 10 0 10 10
SRQ 79 61 82 63 / 10 0 0 0
BKV 82 55 84 57 / 10 10 10 10
SPG 79 66 83 68 / 10 0 0 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE/MARINE...MROCZKA
AVIATION...RUDE
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
633 AM EDT SUN APR 7 2013
.SYNOPSIS...
HIGH PRESSURE WILL PERSIST THROUGH MID WEEK. A COLD FRONT WILL
APPROACH THE AREA LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THROUGH SUNRISE...SATELLITE...SOUTH CAROLINA DOT WEBCAMS AND
SURFACE OBSERVATIONS SHOW LOW CLOUDS AND DENSE FOG ARE EXPANDING
RAPIDLY SOUTH OUT OF BERKELEY COUNTY. THE BERKELEY COUNTY WARNING
POINT AS WELL AS AWOS OBSERVATIONS FROM KMKS AND KDYB INDICATE
VSBYS ARE RUNNING ABOUT 1/4-1/2 MILE. A DENSE FOG ADVISORY HAS
BEEN ISSUED FOR DORCHESTER AND BERKELEY COUNTIES UNTIL 9 AM...BUT
MAY NEED TO BE EXPANDED TO INCLUDE CHARLESTON AND COLLETON
COUNTIES PRIOR TO SUNRISE. UPDATED GRIDDED AND TEXT FORECASTS TO
REFLECT GOING TRENDS.
TODAY...LARGE SOUTHWEST-NORTHEAST ORIENTED HIGH PRESSURE CENTERED
OFF NEW ENGLAND WILL STEADILY SHIFT FARTHER OFFSHORE TODAY AS A
FAIRLY ZONAL FLOW DOMINATES ALOFT. ONGOING WEAK WARM ADVECTION
WILL PUSH H8 TEMPERATURES INTO THE 8-9C RANGE WHICH WILL YIELD
SLIGHTLY WARMER HIGH TEMPERATURES COMPARED TO SATURDAY. LOW-LEVEL
THICKNESSES SCHEMES AND MODEL BUFR SOUNDINGS GENERALLY SUPPORT
HIGHS IN THE LOWER-MID 70S WITH CONSIDERABLY COOLER TEMPERATURES
IN THE LOWER 60S AT THE BEACHES WHERE OCEANIC INFLUENCES WILL BE
THE GREATEST. EXPECT ANOTHER RATHER ROBUST SEA BREEZE CIRCULATION
TO FORM ALONG THE BEACHES LATER TODAY WHICH WILL MOVE STEADILY
INLAND DURING THE AFTERNOON HOURS. THIS WILL CAUSE TEMPERATURES TO
DROP ABOUT 5-8 DEGREES ACROSS THE COASTAL COUNTIES WITH ITS
PASSAGE...SIMILAR TO SATURDAY. WITH THE LACK OF STRATOCUMULUS
THIS MORNING...ITS UNCLEAR EXACTLY HOW MUCH CUMULUS WILL DEVELOP
LATER TODAY AS TEMPERATURES WARM INTO THE 70S. SUSPECT THERE WILL
BE AT LEAST A SHALLOW...SOMEWHAT SCATTERED CUMULUS FIELD AHEAD OF
THE SEA BREEZE SO WILL STICK WITH A PARTLY CLOUDY SKIES CHARACTER
FOR TODAY. SKIES WILL LIKELY CLEAR A BIT IN THE WAKE OF THE SEA
BREEZE AS MORE STABLE AIR IS DRAWN INLAND FROM OFF THE ATLANTIC.
THIS MAY RESULT IN A PERIOD OF MOSTLY SUNNY TO SUNNY SKIES PRIOR
TO SUNSET...MAINLY ACROSS THE COASTAL CORRIDORS. NO RAIN IS
EXPECTED EVEN AS THE COASTAL FRONT DRAWS CLOSER TO THE COAST AND
EVENTUALLY BECOMES ABSORBED IN THE BROADER SYNOPTIC FLOW.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
TONIGHT...THE AREA WILL REMAIN ALONG THE WESTERN FRINGES OF
ATLANTIC HIGH PRESSURE TONIGHT. EXPECT MAINLY CLEAR SKIES TO
DOMINATE WITH SOME PATCHY STRATOCUMULUS POSSIBLY MOVING INLAND
FROM OFF THE ATLANTIC. THE BOUNDARY LAYER SHOULD DECOUPLE FOR MOST
AREA AWAY FROM THE IMMEDIATE COAST A FEW HOURS AFTER SUNSET.
GENERALLY FAVORED THE COOLER SIDE OF GUIDANCE GIVEN THE DECENT
RADIATIONAL SETUP. LOWS WILL RANGE FROM THE LOWER 50S INLAND TO
THE MID 50S ALONG THE IMMEDIATE COAST. A FEW UPPER 40S CAN NOT BE
COMPLETELY RULED OUT...MAINLY IN THE NORMALLY COLDER LOCATIONS
SUCH AS ALLENDALE AND JAMESTOWN. COULD SEE SOME SHALLOW GROUND FOG
FORM AFTER MIDNIGHT...BUT ITS PROBABLY NOT WORTH MENTIONING GIVEN
THE LACK OF ANY SIGNIFICANT IMPACT.
MONDAY AND TUESDAY...THE FORECAST AREA WILL REMAIN ON THE PERIPHERY
OF SURFACE HIGH PRESSURE IN THE ATLANTIC EARLY NEXT WEEK. THE UPPER
LEVEL PATTERN WILL BECOME MORE AMPLIFIED BY TUESDAY...AS A DEEP
TROUGH SHIFTS INTO THE CENTRAL PLAINS AND RIDGING STRENGTHENS ACROSS
THE SOUTHEAST COAST. RISING HEIGHTS ALOFT AND SOUTH/SOUTHEAST FLOW
WILL SUPPORT UNSEASONABLY WARM CONDITIONS EACH AFTERNOON. HIGH
TEMPERATURES INLAND WILL RISE INTO THE UPPER 70S TO LOWER 80S ON
MONDAY...WHILE WARMING SOLIDLY INTO THE LOWER 80S BY TUESDAY. THE
ONSHORE COMPONENT TO THE SURFACE FLOW WILL KEEP COASTAL LOCATIONS
NOTABLY COOLER...SUPPRESSING HIGH TEMPERATURES IN THE LOWER TO MID
70S NEAR THE BEACHES. ALTHOUGH LOW LEVEL MOISTURE WILL BE
INCREASING...AND A SEABREEZE BOUNDARY WILL DEVELOP WITHIN MORE
SUMMER-LIKE CONDITIONS...DECENT SUBSIDENCE SHOULD PREVENT DIURNAL
SHOWER DEVELOPMENT. HAVE THUS CAPPED RAIN CHANCES BELOW 15 PERCENT.
WEDNESDAY...DEEP LAYER RIDGING WILL GRADUALLY SHIFT FARTHER INTO
THE ATLANTIC BY MID WEEK...WHILE THE ROBUST UPPER TROUGH
STRETCHING FROM THE NORTHERN PLAINS TO THE SOUTHWEST STATES MAKES
SOME PROGRESS EASTWARD. THIS SYSTEM WILL PROVIDE THE ENERGY TO
SPAWN A SURFACE LOW AND TRAILING COLD FRONT TO THE WEST OF THE
FORECAST AREA. THE GFS MODEL SOLUTIONS HAVE BEEN CONSISTENTLY MORE
AGGRESSIVE IN BREAKING DOWN THE DEEP RIDGING...DECREASING
SUBSIDENCE ENOUGH TO SUPPORT DIURNAL SHOWER DEVELOPMENT WEDNESDAY
AFTERNOON. PREFER TO LEAN TOWARD A MORE CONSERVATIVE AND SLOWER
SCENARIO...THUS CONTINUING TO KEEP RAIN CHANCES BELOW 15 PERCENT.
WILL ALSO CONTINUE TO INDICATE UNSEASONABLY WARM HIGH
TEMPERATURES...REACHING THE LOWER 80S AWAY FROM THE LOCALLY COOLER
COASTLINE DURING THE AFTERNOON HOURS.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
MEDIUM RANGE MODEL SOLUTIONS MAINTAIN SIGNIFICANT DISCREPANCIES IN
THE TIMING OF A COLD FRONT APPROACHING FROM THE WEST LATE IN THE
WEEK. AN ELONGATED UPPER TROUGH OVER THE CENTRAL PLAINS WEDNESDAY
NIGHT WILL BREAK INTO A MORE SPLIT FLOW FEATURE BY THURSDAY.
SLOWER MODEL SOLUTIONS SUGGEST THE SOUTHERN SHORTWAVE ENERGY WILL
SPIN UP A SECONDARY SURFACE LOW ALONG THE GULF COAST STATES THAT
COULD DELAY THE PROGRESS OF THE FRONTAL SYSTEM. IN ADDITION...THERE
IS SOME QUESTION AS TO THE RESILIENCY OF THE UPPER RIDGE AND
SUBSEQUENT IMPACTS ON PRECIPITATION TIMING AND COVERAGE. UPON
COLLABORATION WITH NEIGHBORING FORECAST OFFICES...PREFER TO LEAN
TOWARD THE SLOWER MODELS SOLUTIONS AT THIS TIME. WILL INTRODUCE A
SLIGHT CHANCE OF RAIN FROM WEST TO EAST AS EARLY AS THURSDAY...YET
SUGGEST THE HIGHEST POTENTIAL FOR SHOWER/THUNDERSTORM COVERAGE
FRIDAY AFTERNOON AND EVENING...WHEN THE SOUTHERN STREAM SHORTWAVE
AND SURFACE LOW LIFT INTO THE AREA. REGARDLESS OF MODEL
SOLUTION...THE UNSEASONABLY WARM CONDITIONS AHEAD OF THE FRONTAL
SYSTEM WILL SUPPORT DECENT INSTABILITY AND SUBSEQUENT THUNDERSTORM
DEVELOPMENT. THIS INSTABILITY...WHEN COMBINED WITH A POTENTIAL 40
TO 50 KT LOW LEVEL JET...COULD ALSO ALLOW THUNDERSTORMS TO BECOME
STRONG AND ORGANIZED. HOWEVER...CONFIDENCE IN SUCH DETAILS THIS
FAR OUT REMAINS LOW...ESPECIALLY CONSIDERING CURRENT MODEL
CONSISTENCY ISSUES.
EXPECT THE COLD FRONT TO HAVE CROSSED THE EAST COAST BY FRIDAY
NIGHT...WITH SURFACE HIGH PRESSURE RAPIDLY REBUILDING FROM THE WEST
IN ITS WAKE. HAVE MAINTAINED JUST A SLIGHT CHANCE FOR
SHOWERS/THUNDERSTORMS INTO EARLY SATURDAY...WITH POPS FALLING
BELOW 15 PERCENT FOR THE REMAINDER OF THE WEEKEND. HIGH
TEMPERATURES WILL BE A FEW DEGREES COOLER FROM FRIDAY AFTERNOON
THROUGH SUNDAY...BECOMING CLOSER TO SEASONAL NORMALS IN THE MID
70S BY THE WEEKEND.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
GENERALLY VFR. INCREASING MOISTURE FROM OFF THE ATLANTIC WILL
LIKELY SUPPORT SOME STRATOCUMULUS THROUGH SUNRISE. ITS STILL
UNCLEAR AT THIS POINT HOW WIDESPREAD THESE CLOUDS WILL BECOME BUT
LATEST RAP DATA SUGGESTS ANY CIGS THAT ARE ESTABLISHED WILL LIKELY
REMAIN LOW-END VFR...MAINLY AT KSAV WHERE THE RISK FOR LOW CLOUDS
WILL BE THE GREATEST. WILL CARRY VFR CONDITIONS AT BOTH KCHS/KSAV
FOR THE NEXT 24 HOURS. WILL LIKELY SEE A PERIOD OF GUSTY WINDS IN
THE WAKE OF THE AFTERNOON...POSSIBLY REACHING AS HIGH AS 15-18 KT.
EXTENDED AVIATION OUTLOOK...POSSIBLE FLIGHT RESTRICTIONS IN LIGHT
FOG/MIST LATE AT NIGHT AND IN THE MORNING SUNDAY NIGHT THROUGH
WEDNESDAY.
&&
.MARINE...
TODAY...NORTHEAST WINDS WILL GRADUALLY TURN SOUTHEAST TODAY AS THE
COASTAL TROUGH DRIFTS CLOSER TO THE COAST AND GRADUALLY BECOMES
ABSORBED IN THE BROADER SYNOPTIC FLOW. WINDS WILL GENERALLY REMAIN
10-15 KT THROUGH THE DAY...ALTHOUGH THERE WILL LIKELY BE COME
ENHANCEMENT NEAR THE LAND/SEA INTERFACE AND IN THE CHARLESTON
HARBOR AS THE SEA BREEZE DEVELOPS AND MOVES INLAND. SEAS WILL
RANGE FROM 2-4 FT NEARSHORE WATERS WITH 4-5 FT OFFSHORE WATERS.
TONIGHT...THERE ARE NO CONCERNS TONIGHT WITH SOUTHEAST WINDS
DOMINATING. WINDS WILL REMAIN 10-15 KT WITH SEAS 2-4 FT...
HIGHEST OVER THE GEORGIA OFFSHORE WATERS
MONDAY THROUGH FRIDAY...THE MARINE ZONES WILL REMAIN ALONG THE
WESTERN PERIPHERY OF A LARGE AND FAIRLY STRONG RIDGE OF ATLANTIC
HIGH PRESSURE THROUGH THE UPCOMING WEEK. SOUTHEAST/SOUTH
CIRCULATION AROUND THE HIGH WILL BECOME ENHANCED AT TIMES BY
AFTERNOON/EVENING SEA BREEZE CIRCULATIONS...BUT EXPECT WINDS TO BE
CAPPED AT 10 OR 15 KT. SEAS WILL GENERALLY RANGE FROM 2 TO 4 FT
THROUGH MID WEEK. THE GRADIENT WILL LIKELY TIGHTEN BETWEEN THE
ATLANTIC HIGH AND AN APPROACHING COLD FRONT BY THURSDAY. WINDS
AND/OR SEAS COULD THEREFORE BUILD CLOSE TO ADVISORY LEVELS LATE IN
THE FORECAST PERIOD.
RIP CURRENTS...OPTED TO UPGRADE TO A MODERATE RISK FOR RIP
CURRENTS FOR ALL BEACHES TODAY. WW4 OUTPUT SHOWS 8 TO OCCASIONAL 9
SECOND SWELLS DOMINATING FOR MUCH OF THE DAY. TYBEE ISLAND
LIFEGUARDS REPORTED RIP CURRENTS ALONG WITH SEVERAL ASSISTS AND
ONE RESCUE YESTERDAY AFTERNOON. CONSIDERING SIMILAR CONDITIONS
WILL BE IN PLACE TODAY...THERE IS ENOUGH EVIDENCE TO SUPPORT A
MODERATE RISK...DESPITE THE FAIRLY MODEST ONSHORE WIND REGIME.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR SCZ044-045-
052.
MARINE...NONE.
&&
$$
ST/79
AREA FORECAST DISCUSSION
NWS WICHITA KS
931 AM CDT SUN APR 7 2013
.UPDATE...
ISSUED AT 922 AM CDT SUN APR 7 2013
PERSISTENT WARM AIR ADVECTION CONTINUES GENERATE BANDS OF VERY
LIGHT RAIN ACROSS CENTRAL KANSAS. LOW LEVELS REMAIN SOMEWHAT
DRY...THUS MOST PRECIPITATION EVAPORATING BEFORE REACHING THE GROUND.
UPDATED FORECAST TO INCLUDE SLIGHT CHANCE POPS...THOUGH EXPECT MOST
LOCATIONS TO REMAIN DRY.
SUBSIDENCE BEHIND SHOWERS COMBINED WITH MIXING...PRODUCING A
TEMPORARY BOOST AREAR OF RAIN BANDS. TIMING AND AMOUNT OF WARMING DIFFICULT
TO FORECAST...AND ATTEMPTED TO EMULATE...WITH HRRR PROVIDING BEST GUIDANCE.
SF
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 300 AM CDT SUN APR 7 2013
CURRENT SATELLITE WATER VAPOR IMAGERY SHOWS UPPER WAVE OVER NORTHERN
NEVADA/SOUTHERN IDAHO RACING EASTWARD VIA ZONAL UPPER FLOW REGIME.
THE ENVIRONMENT LOOKS CAPPED FOR SURFACE BASED ACTIVITY AND NOT
SEEING ANY REAL GOOD LOW LEVEL CONVERGENCE...HOWEVER WARM AIR
ADVECTION IN THE MID-LEVELS AHEAD OF APPROACHING PV WAVE SHOULD
SPARK OFF SCATTERED ELEVATED SHOWERS/STORMS TODAY. ELEVATED
INSTABILITY/SHEAR COMBO SUGGESTS A FEW STRONG STORMS TO POSSIBLY
MARGINALLY SEVERE FOR THIS AFTERNOON/EVENING WITH HAIL BEING THE
MAIN HAZARD. THIS ACTIVITY WILL MOVE NORTHEAST TONIGHT WITH A LULL
IN THE ACTIVITY FOR MONDAY...AS SHORT WAVE RIDGING COMMENCES
ALOFT. STILL THINK MODELS MIGHT BE A LITTLE OVER ZEALOUS ON
QUALITY OF MOISTURE RETURN FOR MONDAY. GIVEN NO REAL LOW-LEVEL
FOCUS AND STRONG CAPPING OVER THE REGION ON MONDAY WOULD EXPECT
ANY AFTERNOON ACTIVITY TO DEVELOP OVER NORTHWEST KANSAS IN THE
UPSLOPE REGIME. THE BETTER CHANCES OF THUNDERSTORMS FOR LATE
MONDAY AFTERNOON/NIGHT WILL BE OVER CENTRAL KANSAS AND POINTS
NORTH...AS LIFT AND MOISTURE TRANSPORT IS FAVORED NEAR WARM FRONT
BOUNDARY. SEVERE WEATHER LOOKS MORE LIKELY ON TUESDAY AS MAIN
UPPER WAVE MOVES TOWARDS THE CENTRAL PLAINS. THE MOST LIKELY MODE
OF THUNDERSTORMS STILL SEEMS TO BE A LINE OF STRONG TO SEVERE
THUNDERSTORMS MATERIALIZING TUESDAY AFTERNOON ALONG THE FRONT...AS
DEEP MERIDIONAL TROUGHING AND STRONG UPPER DYNAMICS FAVOR LINEAR
ACTIVITY.
.LONG TERM...(WEDNESDAY THROUGH SATURDAY)
ISSUED AT 300 AM CDT SUN APR 7 2013
LINGERING PRECIPITATION FOR WEDNESDAY WITH POSSIBLE RAIN/SNOW
MIXTURE EARLY WEDNESDAY MORNING FOR CENTRAL KANSAS...FOLLOWED BY MUCH
COOLER TEMPERATURES FOR WEDNESDAY/THURSDAY AND WARMER WEATHER TO
RETURN FOR NEXT WEEKEND.
JAKUB
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 646 AM CDT SUN APR 7 2013
DIFFICULT AVIATION FORECAST. NOT MUCH AGREEMENT BETWEEN MODELS
WITH FINER DETAILS THAT WOULD SIGNIFICANTLY IMPACT AVIATION
FORECASTS. SOME CHANCE FOR LIGHT PRECIPITATION AT KRSL/KSLN THIS
MORNING FROM MID LEVEL CLOUD DECK. RAIN SHOWERS/THUNDERSTORMS ALSO
POSSIBLE LATE THIS AFTERNOON/EVENING AT KICT/KHUT/KCNU...BUT
UNCERTAINTY...TIMING AND COVERAGE PRECLUDE MENTIONING AT THIS
TIME. MODELS ALL SHOW LOW LEVEL MOISTURE ON THE INCREASE DURING
THE FORECAST...AND SUSPECT AT LEAST MVFR CEILINGS WILL BE LIKELY
AT ALL SITES BY END OF THE VALID PERIOD...IF NOT IFR. -HOWERTON
&&
.FIRE WEATHER...
ISSUED AT 646 AM CDT SUN APR 7 2013
GRASSLAND FIRE DANGER INDEX MAY BRIEFLY GO INTO THE VERY HIGH
CATEGORY ON TUESDAY AFTERNOON OVER PARTS OF CENTRAL AND SOUTH
CENTRAL KANSAS. HOWEVER PRECIPITATION MAY LIMIT THIS THREAT.
WINDS MAY BE GUSTY AT TIMES. CONFIDENCE IN FORECAST IS NOT
PARTICULARLY HIGH DUE TO MODEL UNCERTAINTY. -HOWERTON
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 72 58 75 60 / 40 30 10 30
HUTCHINSON 72 56 75 59 / 40 30 10 40
NEWTON 71 56 74 59 / 60 40 10 40
ELDORADO 72 58 74 60 / 50 40 10 30
WINFIELD-KWLD 72 58 76 61 / 30 20 10 20
RUSSELL 71 53 74 55 / 50 30 40 60
GREAT BEND 72 55 75 56 / 40 30 30 50
SALINA 72 55 72 58 / 60 50 30 60
MCPHERSON 72 56 74 58 / 50 40 20 50
COFFEYVILLE 72 59 74 62 / 30 40 10 20
CHANUTE 72 58 72 60 / 50 60 10 20
IOLA 72 58 72 60 / 60 70 10 30
PARSONS-KPPF 72 59 73 61 / 30 40 10 20
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
716 AM CDT SUN APR 7 2013
.SHORT TERM...(TODAY)
ISSUED AT 442 AM CDT SUN APR 7 2013
TODAY...DEEPER MOISTURE EXTENDING FROM SOUTHERN OK AND EAST TX
WILL BE ADVECTED NORTHWARD AS A LEE SURFACE TROUGH DEEPENS ACROSS
THE CENTRAL AND WESTERN HIGH PLAINS. THE SOUTHERLY LOW- LEVEL FLOW
WILL ADVECT THIS DEEPER MOISTURE NORTHWARD ACROSS EASTERN KS LATE
THIS AFTERNOON.
THE WESTERN GULF OF MEXICO IS NOT AT EQUILIBRIUM EARLY THIS
MORNING...BUT THE RESIDUAL MOISTURE RETURN SHOULD BE SUFFICIENT TO
ALLOW MID TO UPPER 50 DEWPOINTS TO ADVECT NORTHWARD ACROSS THE CWA
BY LATE AFTERNOON.
MEANWHILE...A SHORTWAVE LENGTH H5 TROUGH WAS MOVING EASTWARD ACROSS
CENTRAL CO...SOUTHWARD INTO NORTHWEST NM. THE NAM...ECMWF AND GFS
SHOW THIS H5 TROUGH MOVING EAST ACROSS WESTERN AND CENTRAL KS TODAY.
STRONGER ASCENT AHEAD OF THIS H5 TROUGH AND THE STRONGER ISENTROPIC
LIFT ON THE NORTH SIDE OF DEEPER MOISTURE RETURN WILL ALLOW
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS TO DEVELOP FROM
SOUTH TO NORTH ACROSS THE CWA DURING THE MID AND LATE AFTERNOON
HOURS.
THE VERTICAL WINDSHEAR LOOKS TO BE STRONG WITH 0-6KM SHEAR OF 40 TO
60 KTS ACROSS THE CWA THROUGH THE LATE AFTERNOON HOURS. INSTABILITY
WILL INCREASE THROUGH THE AFTERNOON AS THE DEEPER MOISTURE ADVECTS
NORTHWARD TO AT LEAST I-70. GIVEN STEEP LAPSE RATES FROM 700MB TO
THE SURFACE...ONCE THE DEEPER MOISTURE ADVECT FAR ENOUGH NORTH WE
SHOULD SEE SBCAPE INCREASE TO 1,000 TO 1,500 J/KG FROM I-70 SOUTH.
THE NAM MODEL EVEN SHOWS AN ENHANCED BAND OF 0-1KM SRH OF 80-100
J/KG ALONG THE I-35 CORRIDOR BY 21Z AND LIFTING NORTHWARD TO I-70 BY
00Z. THIS WOULD BE SUFFICIENT FOR DISCRETE SUPERCELL TO POTENTIALLY
PRODUCE ISOLATED TORNADOES. HOWEVER...THE MODE OF CONVECTION IS
STILL IN QUESTION. THE ECMWF...GFS...AND NAM ALL SHOW NUMEROUS
THUNDERSTORMS DEVELOPING ALONG I-35 AFTER 21Z AND EXTENDING WESTWARD
TOWARDS ICT. IF A COMPLEX OR CLUSTER OF THUNDERSTORMS DEVELOPS LATE
IN THE AFTERNOON HOURS ALONG THE NORTHERN EDGE OF DEEPER MOISTURE
RETURN...THEN THE PRIMARY THREAT WILL LARGE HAIL AND SEVERE WIND
GUSTS. THIS COMPLEX OF STORMS WILL DEVELOP NORTHWARD ACROSS EAST
CENTRAL KS LATE IN THE AFTERNOON. IF THE THUNDERSTORMS REMAIN
DISCRETE...THEN GIVEN THE 0-1KM SRH AND INSTABILITY...THEN ISOLATED
TORNADOES COULD NOT BE RULED OUT FOR PORTIONS OF THE CWA...SOUTH OF
I-70. THE RAP AND (ARW) WRF...TWO OF OUR MESOSCALE MODELS...SHOW THE
INITIATION OF DEEP MOIST CONVECTION WEST AND SOUTHWEST OF THE CWA
THROUGH THE LATE AFTERNOON HOURS. THE INITIAL MODE LOOKS DISCRETE
WITH STORM MERGERS OCCURING AS THEY MOVE NORTHEAST ACROSS THE CWA
DURING THE EARLY EVENING HOURS. STAY TUNED TO LATER UPDATES ON THE
POTENTIAL FOR SEVERE WEATHER LATE THIS AFTERNOON AND EVENING.
TEMPERATURES WILL WARM INTO THE LOWER TO MID 70S WITH PATCHES OF
DENSE HIGH CLOUD COVER SPREADING ACROSS THE CWA THIS MORNING. CU
SHOULD BEGIN TO DEVELOP AS THE DEEPER MOISTURE SURGES NORTHWARD THIS
AFTERNOON.
GARGAN
.LONG TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 442 AM CDT SUN APR 7 2013
CONVECTIVE COMPLEX OF SHOWERS AND THUNDERSTORMS WILL CONTINUE TO
DEVELOP/EXPAND EAST AND NORTHEAST ACROSS PRIMARILY THE SOUTHEAST
HALF OF THE CWA THROUGH THE EARLY AND MID EVENING HOURS WITH A
THREAT FOR PRIMARILY LARGE HAIL WITH THE STRONGER STORMS.
HOWEVER...AS THE SHORTWAVE TROUGH MOVES THROUGH BY LATE
EVENING...THE LLVL FLOW WILL BEGIN TO VEER AND ALLOW FOR SOME DRIER
AIR TO ADVECT EASTWARD WHICH WILL FAVOR THE MORE EASTWARD
PROGRESSION OF THE POSSIBLE MCS. HAVE THEREFORE TRENDED THE HIGHER
POPS THROUGH THE EARLY/MID EVENING...THEN A GRADUAL DECREASED POP
THROUGH LATE EVENING/MIDNIGHT...THEN A MUCH MORE RAPID DROP IN POPS
AFTER MIDNIGHT WEST TO EAST ACROSS THE CWA. WILL KEEP THE SOUTHEAST
CWA WARMER WITH THE CLOUDS AND HIGHER DEWPOINTS IN THE UPPER 50S
WITH NEAR 50 IN THE FAR NORTH CENTRAL.
ON MONDAY...OVERALL LACK OF LARGE SCALE ASCENT/FORCING WITHIN AN
ENVIRONMENT EXHIBITING A RAPIDLY STRENGTHENING ELEVATED MIXED LAYER
(EML) DOES NOT INCREASE CONFIDENCE IN CARRYING POPS BEYOND LOW END
CHANCE CATEGORY. HAVE REMOVED POPS FOR MOST OF THE MORNING...BUT
CARRIED LOW POPS IN THE LATE MORNING/AFTERNOON...ALTHOUGH IMPRESSIVE
INHIBITION MAY WARRANT LOWERING/OR REMOVING POPS MORE. KEPT HIGHS IN
THE LOW TO MID 70S DUE TO EXPECTED STRATUS DECK BENEATH
INVERSION.
BY MONDAY NIGHT...MORE CONVECTION IS EXPECTED TO ADVANCE/DEVELOP
EASTWARD FROM WESTERN/CENTRAL KANSAS THROUGH THE NIGHT PRIMARILY
ALONG THE NORTH OF THE WARM FRONT AS LLVL JET INCREASES THROUGH THE
NIGHT. THE FOCUS FOR THIS HAS CONTINUES TO TREND NORTHWARD WITH
TIME AND STRONG CAPPING OVER THE CWA MAY ALSO INHIBIT THE SOUTH AND
EASTWARD EXTENT OF THE CONVECTION AS WELL. FOR NOW...HAVE KEPT
LIKELY POPS ACROSS THE NORTHERN 2/3 OF THE CWA...BUT IF MODEL TRENDS
CONTINUE...THE HIGHER POPS MAY NEED TO BE TRIMMED/SHIFTED MORE
NORTHWARD CLOSER TO THE NE BORDER.
TUESDAY AND TUESDAY NIGHT STILL APPEARS TO BE THE MOST ACTIVE
TIMEFRAME FOR THIS STORM SYSTEM ACROSS OUR CWA AS A DEEPENING SFC
LOW/COLD FRONT ADVANCES EASTWARD ACROSS THE AREA AS THE MAIN
SHORTWAVE ROTATES NORTHEAST OUT OF THE LONGER WAVE TROUGH IN THE
WEST INTO THE NORTHERN PLAINS EARLY WEDNESDAY. CONVECTION COULD
FIRST INITIATE OVER CENTRAL KS THEN CONGEAL INTO A POSSIBLE SQUALL
LINE AS IT MOVES EAST THROUGH THE AFTERNOON/EVENING WITH ALL MODES
OF SEVERE WEATHER POSSIBLE DURING THIS TIME FRAME BEFORE THE FRONT
USHERS IN COOLER AND DRIER AIR INTO EASTERN KS LATE IN THE NIGHT.
WILL KEEP A LINGERING CHANCE FOR DECREASING CONVECTION/RAIN
POTENTIAL ON WEDNESDAY WITH SHOWERS EXITING THE CWA WEDNESDAY
NIGHT...THEN DRY THURSDAY INTO FRIDAY NIGHT. A SLIGHT CHANCE FOR
SHOWERS WILL RETURN BY SATURDAY. AFTER HIGHS IN THE 60S/70S ON
TUESDAY...WEDNESDAY TEMPS WILL COOL INTO THE 40S AND 50S FOR
WEDNESDAY AND THURSDAY...THEN THE 50S FRIDAY AND THE 60S FOR
SATURDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 711 AM CDT SUN APR 7 2013
EXPECT VFR CONDITIONS FOR THE NEXT 12 HOURS. THIS EVENING MVFR
CEILINGS SHOULD DEVELOP ALONG WITH SHOWER AND THUNDERSTORMS. THUNDERSTORMS
SHOULD MOVE EAST OF THE TAF SITES AFTER 6Z MON. THERE MAY BE SOME
BRIEF LOW MVFR OR IFR CONDITIONS MAY OCCUR WITH THE STRONGER
THUNDERSTORMS THIS EVENING. MVFR STRATUS WILL CONTINUE THROUGH 12Z
MON.
GARGAN
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GARGAN
LONG TERM...63
AVIATION...GARGAN
AREA FORECAST DISCUSSION
NWS JACKSON KY
1052 AM EDT SUN APR 7 2013
.UPDATE...
ISSUED AT 1027 AM EDT SUN APR 7 2013
TEMPERATURE RISE THIS MORNING HAS BEEN QUICKER THAN FORECAST...BUT AT
THE SAME TIME CLOUDS ARE ALSO INCREASING QUICKER. HAVE ADJUSTED THE
HOURLY TEMPERATURE FORECAST AND SKY COVER FORECAST TO ACCOUNT FOR
THIS. INCREASING CLOUDS SHOULD KEEP CURRENT MAXIMUM TEMPERATURE
FORECAST ON TARGET.
ANOTHER ITEM TO ADDRESS FOR THIS UPDATE ARE DEWPOINTS AND POTENTIAL
FIRE WEATHER CONCERNS. DEWPOINTS HAVE BEEN RESPONDING TO INCREASING
SOUTHWEST FLOW...AND DESPITE RELATIVE HUMIDITY CURRENTLY IN THE 30 TO
40 PERCENT RANGE...WE SHOULD SEE RELATIVE HUMIDITY STAY ABOVE CRITICAL
THRESHOLDS. THIS WILL BE MONITORED CLOSELY THOUGH AS WINDS ARE MUCH
STRONGER THAN YESTERDAY. PLAN TO ISSUE AN SPS FOR ENHANCED WILD FIRE
THREAT.
FINALLY HAVE MADE SOME ADJUSTMENTS TO SHOWER CHANCES THIS AFTERNOON.
LATEST HRRR POINTS TOWARDS DELAYING THE ONSET OF RAIN CHANCES AND
ALSO EXTENDING THE CHANCE FURTHER SOUTH. HOWEVER THEN HRRR IS
OVERPLAYING PRECIPITATION CHANCES THIS MORNING. HAVE FOLLOWED THE
IDEA OF DELAYING PRECIPITATION CHANCES...BUT DID NOT EXTEND THE
CHANCE FURTHER SOUTH. HAVE ACTUALLY LOWERED THE PROBABILITY FROM
LIKELY TO CHANCE IN THE NORTH AS WELL.
NDFD AND ZFP HAVE BEEN UPDATED.
UPDATE ISSUED AT 658 AM EDT SUN APR 7 2013
FRONTAL BOUNDARY IS JUST ABOUT TO THE CINCINNATI METRO AREA WITH THE
LINE OF SHOWERS PRETTY MUCH NON-EXISTENT AT THE TIME. HRRR IS ALSO
DOWNPLAYING ACTIVITY ALONG THIS BOUNDARY THROUGH THE MORNING HOURS
WHICH SEEMS VERY REASONABLE. STILL LOOKS LIKE WE COULD SEE AN UPTICK
IN SHOWER OR THUNDERSTORM ACTIVITY THIS AFTERNOON AS INSTABILITY
INCREASES JUST AHEAD OF THE STALLING BOUNDARY. MOST OF THE ACTIVITY
MAY BE TIED TO WHETHER OR NOT WE CAN GET ENOUGH INSTABILITY. GIVEN
DEWPOINTS MUCH LOWER THAN PREVIOUSLY ANTICIPATED...THIS COULD BE IN
JEOPARDY. HOWEVER...WILL MAINTAIN THE CURRENT POPS AND LET DAYSHIFT
RE-EVALUATE IF WE WILL SEE ANY SHOWER ACTIVITY IN THE FAR NORTH
TODAY. DEWPOINTS ARE FINALLY STARTING TO CREEP UP A BIT...BUT REMAIN
MUCH SLOWER THAN MODEL GUIDANCE.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 255 AM EDT SUN APR 7 2013
FAIRLY QUIET WEATHER EARLY THIS SUNDAY MORNING. A VIGOROUS SHORTWAVE
IS PUSHING EAST ACROSS MICHIGAN THIS MORNING WITH A WEAK SURFACE
BOUNDARY BEING DRAGGED ACROSS THE OHIO RIVER VALLEY. AT THE
MOMENT...NOT MUCH ACTIVITY OUTSIDE OF A NARROW LINE OF BROKEN SHOWERS
PUSHING EAST ACROSS NORTHERN INDIANA...BACK INTO SOUTHERN ILLINOIS.
HRRR SEEMS TO HAVE A DECENT HANDLE ON THE RADAR TRENDS THIS MORNING.
THE SHORTWAVE WILL EXIT TO THE EAST TODAY...WITH THE FRONTAL BOUNDARY
STALLING ACROSS NORTHERN WEST VIRGINIA AND NORTHERN KENTUCKY. MODELS
SEEM TO BE IN VERY GOOD AGREEMENT ON THIS PLACEMENT. THE BEST CHANCES
FOR ANY RAIN WITH THIS FRONT WILL RESIDE ALONG THIS BOUNDARY...AND
WILL LIKELY REMAIN ALONG AND NORTH OF I-64. MEANWHILE...DRY
CONDITIONS WILL LIKELY PERSIST ACROSS THE REST OF EASTERN KENTUCKY.
WITH MOISTURE RECOVERY VERY POOR AT BEST OVERNIGHT AND THE PROSPECTS
OF DECENT MIXING TODAY...HAVE GONE WELL BELOW GUIDANCE WITH DEWPOINTS
YET AGAIN TODAY. IN FACT...A FEW PLACES...ESPECIALLY IN SOUTHEAST
KENTUCKY COULD SEE AFTERNOON RELATIVE HUMIDITIES FALL TO UNDER 30
PERCENT. WITH STRONGER SOUTHWEST WINDS TODAY...AHEAD OF THE FRONTAL
BOUNDARY...THIS COULD CREATE A PERIOD OF DANGEROUS FIRE WEATHER
CONDITIONS. THIS THREAT WILL HIGHLIGHTED IN THE HWO AND FIRE WEATHER
PLANNING FORECAST. HIGHS TODAY WILL CLIMB EVEN HIGHER INTO THE LOW TO
MID 70S...EXCEPT IN THE NORTH...WHERE CLOUDS AND PERHAPS
PRECIPITATION MAY KEEP LOCATIONS IN THE 60S.
FRONTAL BOUNDARY WILL SLOWLY DRIFT BACK TO THE NORTH THIS
EVENING...WITH RAIN CHANCES DECREASING FROM SOUTH TO NORTH. SKIES
SHOULD REMAIN MOSTLY TO PARTLY CLEAR OVERNIGHT...ALLOWING SOME VALLEY
LOCATIONS TO DECOUPLE AND FALL BACK INTO THE 40S...WHILE RIDGES STAY
IN THE 50S. ANOTHER VIGOROUS SHORTWAVE WILL TRACK NORTHEAST THROUGH
THE PLAINS ON MONDAY...FURTHER PUSHING THE BOUNDARY TO THE NORTH AND
KEEPING EASTERN KENTUCKY DOMINATED BY STRONG RIDGING. A VERY WARM DAY
IS ON TAP WITH HIGHS SURGING WELL INTO THE 70S AREAWIDE.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 255 AM EDT SUN APR 7 2013
MODELS CONTINUE TO SHOW GENERAL AGREEMENT EARLY IN THE PERIOD IN
TERMS OF HOW SYSTEMS WILL AFFECT OUR LOCAL WEATHER. PATTERN
AMPLIFICATION WILL BE ONGOING...WITH A WESTERN CONUS UPPER TROUGH
AND AND A SOUTHEAST CONUS UPPER RIDGE. STRONG SURFACE LOW PRESSURE
WILL TRACK FROM CO AT THE START OF THE PERIOD TO THE VICINITY OF
IL/IN BY THURSDAY MORNING. A FRONTAL BOUNDARY EXTENDING EAST FROM
THE LOW WILL BE LAID OUT NORTH OF THE OHIO RIVER. MODELS DISAGREE ON
EXACTLY HOW FAR NORTH/SOUTH IT WILL BE POSITIONED. THE ECMWF MANAGES
TO BRING IT FURTHER SOUTH THAN ANY OTHER MODEL...MAKING IT INTO THE
NORTHERN PART OF THE JKL FORECAST AREA BY 12Z THURSDAY. WITH ALL
OTHER GUIDANCE SHOWING IT FURTHER NORTH...WILL GO WITH A FORECAST
THAT KEEPS OUR AREA IN THE WARM SECTOR. A BROAD ZONE OF WARM AIR
ADVECTION WILL BRING MOISTURE NORTH FROM THE GULF OF MEXICO AND LIFT
IT ACROSS THE FRONT. THE BEST CHANCE OF RAIN WITH THIS WILL BE WELL
TO OUR NORTH...BUT CAN NOT RULE OUT SOME SHOWERS MAKING IT INTO THE
NORTHERN PART OF THE AREA.
THE FORECAST BECOMES MORE PROBLEMATIC LATER IN THE WEEK DUE TO
CONTINUED DIFFERENCES IN MODEL TIMING OF THE SURFACE LOW AND ITS
TRAILING COLD FRONT. THE ECMWF IS THE SLOWEST...WITH LOCAL FROPA NOT
HAPPENING UNTIL FRIDAY AFTERNOON. THE END OF THE NAM RUN ON WED
MORNING LOOKS SIMILAR TO THE GFS...WHICH ENDS UP WITH FROPA DURING
THE DAY THURSDAY. THERE ARE SOME MEMBERS OF THE GFS ENSEMBLE WHICH
SHOW SIMILAR TIMING AS THE ECMWF...BUT THE GFS ENSEMBLE MEAN IS MORE
SUPPORTIVE OF THE OPERATIONAL GFS. WILL FAVOR A COMPROMISE SOLUTION
CLOSER TO THE GFS. WITH THAT SAID...HIGHEST POPS...IN LIKELY
CATEGORY...WILL BE ON THURSDAY AND THURSDAY NIGHT. WILL USE HIGH
CHANCE ON FRIDAY TO LEND SOME CREDENCE TO THE ECMWF. ALL MODELS SHOW
INSTABILITY AHEAD OF THE COLD FRONT...AND A CHANCE OF THUNDER WILL
BE USED WITH THE APPROACH AND PASSAGE OF THE COLD FRONT. WINDS ALOFT
LOOK TO BE QUITE STRONG...AND WOULD SUPPORT SEVERE WX. HOWEVER...THE
DEGREE OF INSTABILITY DOES NOT REALLY STAND OUT. THE SET-UP WILL
NEED TO CONTINUE TO BE WATCHED.
THE WARMEST AIR MASS OF THE SEASON SO FAR WILL BE IN PLACE UP UNTIL
COLD FROPA. NEEDLESS TO SAY...FRONTAL TIMING WILL PLAY A KEY ROLE IN
TEMPS LATE IN THE PERIOD...AND LEADS TO A LOWER CONFIDENCE IN THE
TEMPERATURE FORECAST FOR THURSDAY INTO FRIDAY...AND A POTENTIAL FOR
MORE SIZEABLE ERRORS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 658 AM EDT SUN APR 7 2013
VFR CONDITIONS WILL HOLD ON THROUGH THE PERIOD. AN APPROACHING COLD
FRONT WILL MOVE INTO NORTHERN KENTUCKY TODAY. SOME SCATTERED SHOWERS
AND A FEW THUNDERSTORMS ARE POSSIBLE...MAINLY NORTH OF I-64. LOWER
CLOUDS AND PRECIPITATION WILL NOT LIKELY MAKE IT SOUTH OF
I-64...KEEPING THE TAF SITES DRY WITH JUST SOME HIGH CLOUDS TO
CONTEND WITH.
&&
.FIRE WEATHER...
ISSUED AT 1051 AM EDT SUN APR 7 2013
DEWPOINTS HAVE BEEN RISING IN THE INCREASING SOUTHWEST FLOW...AND
DESPITE RELATIVE HUMIDITY CURRENTLY IN THE 30 TO 40 PERCENT
RANGE OVER SOUTHEAST KY...WE SHOULD SEE RELATIVE HUMIDITY STAY ABOVE
CRITICAL THRESHOLDS. HOWEVER SOME SPOTS WILL BE NEAR 25 PERCENT RH
THIS AFTERNOON. THIS WILL BE MONITORED CLOSELY AS WINDS ARE MUCH
STRONGER THAN YESTERDAY...WITH GUSTS TO 30 MPH EXPECTED FOR THIS
AFTERNOON. HAVE ISSUED AN SPS FOR ENHANCED WILD FIRE THREAT.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SBH
SHORT TERM...KAS
LONG TERM...HAL
AVIATION...KAS
FIRE WEATHER...SBH
AREA FORECAST DISCUSSION
NWS JACKSON KY
1028 AM EDT SUN APR 7 2013
.UPDATE...
ISSUED AT 1027 AM EDT SUN APR 7 2013
TEMPERATURE RISE THIS MORNING HAS BEEN QUICKER THAN FORECAST...BUT AT
THE SAME TIME CLOUDS ARE ALSO INCREASING QUICKER. HAVE ADJUSTED THE
HOURLY TEMPERATURE FORECAST AND SKY COVER FORECAST TO ACCOUNT FOR
THIS. INCREASING CLOUDS SHOULD KEEP CURRENT MAXIMUM TEMPERATURE
FORECAST ON TARGET.
ANOTHER ITEM TO ADDRESS FOR THIS UPDATE ARE DEWPOINTS AND POTENTIAL
FIRE WEATHER CONCERNS. DEWPOINTS HAVE BEEN RESPONDING TO INCREASING
SOUTHWEST FLOW...AND DESPITE RELATIVE HUMIDITY CURRENTLY IN THE 30 TO
40 PERCENT RANGE...WE SHOULD SEE RELATIVE HUMIDITY STAY ABOVE CRITICAL
THRESHOLDS. THIS WILL BE MONITORED CLOSELY THOUGH AS WINDS ARE MUCH
STRONGER THAN YESTERDAY. PLAN TO ISSUE AN SPS FOR ENHANCED WILD FIRE
THREAT.
FINALLY HAVE MADE SOME ADJUSTMENTS TO SHOWER CHANCES THIS AFTERNOON.
LATEST HRRR POINTS TOWARDS DELAYING THE ONSET OF RAIN CHANCES AND
ALSO EXTENDING THE CHANCE FURTHER SOUTH. HOWEVER THEN HRRR IS
OVERPLAYING PRECIPITATION CHANCES THIS MORNING. HAVE FOLLOWED THE
IDEA OF DELAYING PRECIPITATION CHANCES...BUT DID NOT EXTEND THE
CHANCE FURTHER SOUTH. HAVE ACTUALLY LOWERED THE PROBABILITY FROM
LIKELY TO CHANCE IN THE NORTH AS WELL.
NDFD AND ZFP HAVE BEEN UPDATED.
UPDATE ISSUED AT 658 AM EDT SUN APR 7 2013
FRONTAL BOUNDARY IS JUST ABOUT TO THE CINCINNATI METRO AREA WITH THE
LINE OF SHOWERS PRETTY MUCH NON-EXISTENT AT THE TIME. HRRR IS ALSO
DOWNPLAYING ACTIVITY ALONG THIS BOUNDARY THROUGH THE MORNING HOURS
WHICH SEEMS VERY REASONABLE. STILL LOOKS LIKE WE COULD SEE AN UPTICK
IN SHOWER OR THUNDERSTORM ACTIVITY THIS AFTERNOON AS INSTABILITY
INCREASES JUST AHEAD OF THE STALLING BOUNDARY. MOST OF THE ACTIVITY
MAY BE TIED TO WHETHER OR NOT WE CAN GET ENOUGH INSTABILITY. GIVEN
DEWPOINTS MUCH LOWER THAN PREVIOUSLY ANTICIPATED...THIS COULD BE IN
JEOPARDY. HOWEVER...WILL MAINTAIN THE CURRENT POPS AND LET DAYSHIFT
RE-EVALUATE IF WE WILL SEE ANY SHOWER ACTIVITY IN THE FAR NORTH
TODAY. DEWPOINTS ARE FINALLY STARTING TO CREEP UP A BIT...BUT REMAIN
MUCH SLOWER THAN MODEL GUIDANCE.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 255 AM EDT SUN APR 7 2013
FAIRLY QUIET WEATHER EARLY THIS SUNDAY MORNING. A VIGOROUS SHORTWAVE
IS PUSHING EAST ACROSS MICHIGAN THIS MORNING WITH A WEAK SURFACE
BOUNDARY BEING DRAGGED ACROSS THE OHIO RIVER VALLEY. AT THE
MOMENT...NOT MUCH ACTIVITY OUTSIDE OF A NARROW LINE OF BROKEN SHOWERS
PUSHING EAST ACROSS NORTHERN INDIANA...BACK INTO SOUTHERN ILLINOIS.
HRRR SEEMS TO HAVE A DECENT HANDLE ON THE RADAR TRENDS THIS MORNING.
THE SHORTWAVE WILL EXIT TO THE EAST TODAY...WITH THE FRONTAL BOUNDARY
STALLING ACROSS NORTHERN WEST VIRGINIA AND NORTHERN KENTUCKY. MODELS
SEEM TO BE IN VERY GOOD AGREEMENT ON THIS PLACEMENT. THE BEST CHANCES
FOR ANY RAIN WITH THIS FRONT WILL RESIDE ALONG THIS BOUNDARY...AND
WILL LIKELY REMAIN ALONG AND NORTH OF I-64. MEANWHILE...DRY
CONDITIONS WILL LIKELY PERSIST ACROSS THE REST OF EASTERN KENTUCKY.
WITH MOISTURE RECOVERY VERY POOR AT BEST OVERNIGHT AND THE PROSPECTS
OF DECENT MIXING TODAY...HAVE GONE WELL BELOW GUIDANCE WITH DEWPOINTS
YET AGAIN TODAY. IN FACT...A FEW PLACES...ESPECIALLY IN SOUTHEAST
KENTUCKY COULD SEE AFTERNOON RELATIVE HUMIDITIES FALL TO UNDER 30
PERCENT. WITH STRONGER SOUTHWEST WINDS TODAY...AHEAD OF THE FRONTAL
BOUNDARY...THIS COULD CREATE A PERIOD OF DANGEROUS FIRE WEATHER
CONDITIONS. THIS THREAT WILL HIGHLIGHTED IN THE HWO AND FIRE WEATHER
PLANNING FORECAST. HIGHS TODAY WILL CLIMB EVEN HIGHER INTO THE LOW TO
MID 70S...EXCEPT IN THE NORTH...WHERE CLOUDS AND PERHAPS
PRECIPITATION MAY KEEP LOCATIONS IN THE 60S.
FRONTAL BOUNDARY WILL SLOWLY DRIFT BACK TO THE NORTH THIS
EVENING...WITH RAIN CHANCES DECREASING FROM SOUTH TO NORTH. SKIES
SHOULD REMAIN MOSTLY TO PARTLY CLEAR OVERNIGHT...ALLOWING SOME VALLEY
LOCATIONS TO DECOUPLE AND FALL BACK INTO THE 40S...WHILE RIDGES STAY
IN THE 50S. ANOTHER VIGOROUS SHORTWAVE WILL TRACK NORTHEAST THROUGH
THE PLAINS ON MONDAY...FURTHER PUSHING THE BOUNDARY TO THE NORTH AND
KEEPING EASTERN KENTUCKY DOMINATED BY STRONG RIDGING. A VERY WARM DAY
IS ON TAP WITH HIGHS SURGING WELL INTO THE 70S AREAWIDE.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 255 AM EDT SUN APR 7 2013
MODELS CONTINUE TO SHOW GENERAL AGREEMENT EARLY IN THE PERIOD IN
TERMS OF HOW SYSTEMS WILL AFFECT OUR LOCAL WEATHER. PATTERN
AMPLIFICATION WILL BE ONGOING...WITH A WESTERN CONUS UPPER TROUGH
AND AND A SOUTHEAST CONUS UPPER RIDGE. STRONG SURFACE LOW PRESSURE
WILL TRACK FROM CO AT THE START OF THE PERIOD TO THE VICINITY OF
IL/IN BY THURSDAY MORNING. A FRONTAL BOUNDARY EXTENDING EAST FROM
THE LOW WILL BE LAID OUT NORTH OF THE OHIO RIVER. MODELS DISAGREE ON
EXACTLY HOW FAR NORTH/SOUTH IT WILL BE POSITIONED. THE ECMWF MANAGES
TO BRING IT FURTHER SOUTH THAN ANY OTHER MODEL...MAKING IT INTO THE
NORTHERN PART OF THE JKL FORECAST AREA BY 12Z THURSDAY. WITH ALL
OTHER GUIDANCE SHOWING IT FURTHER NORTH...WILL GO WITH A FORECAST
THAT KEEPS OUR AREA IN THE WARM SECTOR. A BROAD ZONE OF WARM AIR
ADVECTION WILL BRING MOISTURE NORTH FROM THE GULF OF MEXICO AND LIFT
IT ACROSS THE FRONT. THE BEST CHANCE OF RAIN WITH THIS WILL BE WELL
TO OUR NORTH...BUT CAN NOT RULE OUT SOME SHOWERS MAKING IT INTO THE
NORTHERN PART OF THE AREA.
THE FORECAST BECOMES MORE PROBLEMATIC LATER IN THE WEEK DUE TO
CONTINUED DIFFERENCES IN MODEL TIMING OF THE SURFACE LOW AND ITS
TRAILING COLD FRONT. THE ECMWF IS THE SLOWEST...WITH LOCAL FROPA NOT
HAPPENING UNTIL FRIDAY AFTERNOON. THE END OF THE NAM RUN ON WED
MORNING LOOKS SIMILAR TO THE GFS...WHICH ENDS UP WITH FROPA DURING
THE DAY THURSDAY. THERE ARE SOME MEMBERS OF THE GFS ENSEMBLE WHICH
SHOW SIMILAR TIMING AS THE ECMWF...BUT THE GFS ENSEMBLE MEAN IS MORE
SUPPORTIVE OF THE OPERATIONAL GFS. WILL FAVOR A COMPROMISE SOLUTION
CLOSER TO THE GFS. WITH THAT SAID...HIGHEST POPS...IN LIKELY
CATEGORY...WILL BE ON THURSDAY AND THURSDAY NIGHT. WILL USE HIGH
CHANCE ON FRIDAY TO LEND SOME CREDENCE TO THE ECMWF. ALL MODELS SHOW
INSTABILITY AHEAD OF THE COLD FRONT...AND A CHANCE OF THUNDER WILL
BE USED WITH THE APPROACH AND PASSAGE OF THE COLD FRONT. WINDS ALOFT
LOOK TO BE QUITE STRONG...AND WOULD SUPPORT SEVERE WX. HOWEVER...THE
DEGREE OF INSTABILITY DOES NOT REALLY STAND OUT. THE SET-UP WILL
NEED TO CONTINUE TO BE WATCHED.
THE WARMEST AIR MASS OF THE SEASON SO FAR WILL BE IN PLACE UP UNTIL
COLD FROPA. NEEDLESS TO SAY...FRONTAL TIMING WILL PLAY A KEY ROLE IN
TEMPS LATE IN THE PERIOD...AND LEADS TO A LOWER CONFIDENCE IN THE
TEMPERATURE FORECAST FOR THURSDAY INTO FRIDAY...AND A POTENTIAL FOR
MORE SIZEABLE ERRORS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 658 AM EDT SUN APR 7 2013
VFR CONDITIONS WILL HOLD ON THROUGH THE PERIOD. AN APPROACHING COLD
FRONT WILL MOVE INTO NORTHERN KENTUCKY TODAY. SOME SCATTERED SHOWERS
AND A FEW THUNDERSTORMS ARE POSSIBLE...MAINLY NORTH OF I-64. LOWER
CLOUDS AND PRECIPITATION WILL NOT LIKELY MAKE IT SOUTH OF
I-64...KEEPING THE TAF SITES DRY WITH JUST SOME HIGH CLOUDS TO
CONTEND WITH.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SBH
SHORT TERM...KAS
LONG TERM...HAL
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS JACKSON KY
658 AM EDT SUN APR 7 2013
.UPDATE...
ISSUED AT 658 AM EDT SUN APR 7 2013
FRONTAL BOUNDARY IS JUST ABOUT TO THE CINCINNATI METRO AREA WITH THE
LINE OF SHOWERS PRETTY MUCH NON-EXISTENT AT THE TIME. HRRR IS ALSO
DOWNPLAYING ACTIVITY ALONG THIS BOUNDARY THROUGH THE MORNING HOURS
WHICH SEEMS VERY REASONABLE. STILL LOOKS LIKE WE COULD SEE AN UPTICK
IN SHOWER OR THUNDERSTORM ACTIVITY THIS AFTERNOON AS INSTABILITY
INCREASES JUST AHEAD OF THE STALLING BOUNDARY. MOST OF THE ACTIVITY
MAY BE TIED TO WHETHER OR NOT WE CAN GET ENOUGH INSTABILITY. GIVEN
DEWPOINTS MUCH LOWER THAN PREVIOUSLY ANTICIPATED...THIS COULD BE IN
JEOPARDY. HOWEVER...WILL MAINTAIN THE CURRENT POPS AND LET DAYSHIFT
RE-EVALUATE IF WE WILL SEE ANY SHOWER ACTIVITY IN THE FAR NORTH
TODAY. DEWPOINTS ARE FINALLY STARTING TO CREEP UP A BIT...BUT REMAIN
MUCH SLOWER THAN MODEL GUIDANCE.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 255 AM EDT SUN APR 7 2013
FAIRLY QUIET WEATHER EARLY THIS SUNDAY MORNING. A VIGOROUS SHORTWAVE
IS PUSHING EAST ACROSS MICHIGAN THIS MORNING WITH A WEAK SURFACE
BOUNDARY BEING DRAGGED ACROSS THE OHIO RIVER VALLEY. AT THE
MOMENT...NOT MUCH ACTIVITY OUTSIDE OF A NARROW LINE OF BROKEN SHOWERS
PUSHING EAST ACROSS NORTHERN INDIANA...BACK INTO SOUTHERN ILLINOIS.
HRRR SEEMS TO HAVE A DECENT HANDLE ON THE RADAR TRENDS THIS MORNING.
THE SHORTWAVE WILL EXIT TO THE EAST TODAY...WITH THE FRONTAL BOUNDARY
STALLING ACROSS NORTHERN WEST VIRGINIA AND NORTHERN KENTUCKY. MODELS
SEEM TO BE IN VERY GOOD AGREEMENT ON THIS PLACEMENT. THE BEST CHANCES
FOR ANY RAIN WITH THIS FRONT WILL RESIDE ALONG THIS BOUNDARY...AND
WILL LIKELY REMAIN ALONG AND NORTH OF I-64. MEANWHILE...DRY
CONDITIONS WILL LIKELY PERSIST ACROSS THE REST OF EASTERN KENTUCKY.
WITH MOISTURE RECOVERY VERY POOR AT BEST OVERNIGHT AND THE PROSPECTS
OF DECENT MIXING TODAY...HAVE GONE WELL BELOW GUIDANCE WITH DEWPOINTS
YET AGAIN TODAY. IN FACT...A FEW PLACES...ESPECIALLY IN SOUTHEAST
KENTUCKY COULD SEE AFTERNOON RELATIVE HUMIDITIES FALL TO UNDER 30
PERCENT. WITH STRONGER SOUTHWEST WINDS TODAY...AHEAD OF THE FRONTAL
BOUNDARY...THIS COULD CREATE A PERIOD OF DANGEROUS FIRE WEATHER
CONDITIONS. THIS THREAT WILL HIGHLIGHTED IN THE HWO AND FIRE WEATHER
PLANNING FORECAST. HIGHS TODAY WILL CLIMB EVEN HIGHER INTO THE LOW TO
MID 70S...EXCEPT IN THE NORTH...WHERE CLOUDS AND PERHAPS
PRECIPITATION MAY KEEP LOCATIONS IN THE 60S.
FRONTAL BOUNDARY WILL SLOWLY DRIFT BACK TO THE NORTH THIS
EVENING...WITH RAIN CHANCES DECREASING FROM SOUTH TO NORTH. SKIES
SHOULD REMAIN MOSTLY TO PARTLY CLEAR OVERNIGHT...ALLOWING SOME VALLEY
LOCATIONS TO DECOUPLE AND FALL BACK INTO THE 40S...WHILE RIDGES STAY
IN THE 50S. ANOTHER VIGOROUS SHORTWAVE WILL TRACK NORTHEAST THROUGH
THE PLAINS ON MONDAY...FURTHER PUSHING THE BOUNDARY TO THE NORTH AND
KEEPING EASTERN KENTUCKY DOMINATED BY STRONG RIDGING. A VERY WARM DAY
IS ON TAP WITH HIGHS SURGING WELL INTO THE 70S AREAWIDE.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 255 AM EDT SUN APR 7 2013
MODELS CONTINUE TO SHOW GENERAL AGREEMENT EARLY IN THE PERIOD IN
TERMS OF HOW SYSTEMS WILL AFFECT OUR LOCAL WEATHER. PATTERN
AMPLIFICATION WILL BE ONGOING...WITH A WESTERN CONUS UPPER TROUGH
AND AND A SOUTHEAST CONUS UPPER RIDGE. STRONG SURFACE LOW PRESSURE
WILL TRACK FROM CO AT THE START OF THE PERIOD TO THE VICINITY OF
IL/IN BY THURSDAY MORNING. A FRONTAL BOUNDARY EXTENDING EAST FROM
THE LOW WILL BE LAID OUT NORTH OF THE OHIO RIVER. MODELS DISAGREE ON
EXACTLY HOW FAR NORTH/SOUTH IT WILL BE POSITIONED. THE ECMWF MANAGES
TO BRING IT FURTHER SOUTH THAN ANY OTHER MODEL...MAKING IT INTO THE
NORTHERN PART OF THE JKL FORECAST AREA BY 12Z THURSDAY. WITH ALL
OTHER GUIDANCE SHOWING IT FURTHER NORTH...WILL GO WITH A FORECAST
THAT KEEPS OUR AREA IN THE WARM SECTOR. A BROAD ZONE OF WARM AIR
ADVECTION WILL BRING MOISTURE NORTH FROM THE GULF OF MEXICO AND LIFT
IT ACROSS THE FRONT. THE BEST CHANCE OF RAIN WITH THIS WILL BE WELL
TO OUR NORTH...BUT CAN NOT RULE OUT SOME SHOWERS MAKING IT INTO THE
NORTHERN PART OF THE AREA.
THE FORECAST BECOMES MORE PROBLEMATIC LATER IN THE WEEK DUE TO
CONTINUED DIFFERENCES IN MODEL TIMING OF THE SURFACE LOW AND ITS
TRAILING COLD FRONT. THE ECMWF IS THE SLOWEST...WITH LOCAL FROPA NOT
HAPPENING UNTIL FRIDAY AFTERNOON. THE END OF THE NAM RUN ON WED
MORNING LOOKS SIMILAR TO THE GFS...WHICH ENDS UP WITH FROPA DURING
THE DAY THURSDAY. THERE ARE SOME MEMBERS OF THE GFS ENSEMBLE WHICH
SHOW SIMILAR TIMING AS THE ECMWF...BUT THE GFS ENSEMBLE MEAN IS MORE
SUPPORTIVE OF THE OPERATIONAL GFS. WILL FAVOR A COMPROMISE SOLUTION
CLOSER TO THE GFS. WITH THAT SAID...HIGHEST POPS...IN LIKELY
CATEGORY...WILL BE ON THURSDAY AND THURSDAY NIGHT. WILL USE HIGH
CHANCE ON FRIDAY TO LEND SOME CREDENCE TO THE ECMWF. ALL MODELS SHOW
INSTABILITY AHEAD OF THE COLD FRONT...AND A CHANCE OF THUNDER WILL
BE USED WITH THE APPROACH AND PASSAGE OF THE COLD FRONT. WINDS ALOFT
LOOK TO BE QUITE STRONG...AND WOULD SUPPORT SEVERE WX. HOWEVER...THE
DEGREE OF INSTABILITY DOES NOT REALLY STAND OUT. THE SET-UP WILL
NEED TO CONTINUE TO BE WATCHED.
THE WARMEST AIR MASS OF THE SEASON SO FAR WILL BE IN PLACE UP UNTIL
COLD FROPA. NEEDLESS TO SAY...FRONTAL TIMING WILL PLAY A KEY ROLE IN
TEMPS LATE IN THE PERIOD...AND LEADS TO A LOWER CONFIDENCE IN THE
TEMPERATURE FORECAST FOR THURSDAY INTO FRIDAY...AND A POTENTIAL FOR
MORE SIZEABLE ERRORS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 658 AM EDT SUN APR 7 2013
VFR CONDITIONS WILL HOLD ON THROUGH THE PERIOD. AN APPROACHING COLD
FRONT WILL MOVE INTO NORTHERN KENTUCKY TODAY. SOME SCATTERED SHOWERS
AND A FEW THUNDERSTORMS ARE POSSIBLE...MAINLY NORTH OF I-64. LOWER
CLOUDS AND PRECIPITATION WILL NOT LIKELY MAKE IT SOUTH OF
I-64...KEEPING THE TAF SITES DRY WITH JUST SOME HIGH CLOUDS TO
CONTEND WITH.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KAS
SHORT TERM...KAS
LONG TERM...HAL
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1029 AM EDT SUN APR 7 2013
.SYNOPSIS...
RAIN CHANCES WILL INCREASE TODAY AS A COLD FRONT SLIDES OVER THE REGION.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WHAT A DIFFERENCE 24 HOURS MAKES...SPRING HAS SEEMINGLY SPRUNG
OVER THE UPPER OHIO VALLEY. TEMPERATURES THIS MORNING HAVE ALREADY
SKYROCKETED INTO THE MID 60S AS PRE-FRONTAL MIXING COMBINED WITH
THE BONE DRY BOUNDARY LAYER HAS ALLOWED FOR 850 MB TEMPERATURES TO
MIX OUT EARLY TODAY. AS A RESULT...HIGH TEMPERATURES HAVE BEEN
RAISED ACROSS THE BOARD FOR THE AFTERNOON.
THE AFOREMENTIONED FRONTAL BOUNDARY HAS DEFINITELY FELT THE PINCH
FROM THE DRY BOUNDARY LAYER...AND IS HARDLY DISCERNIBLE ON THE
REGIONAL RADAR MOSAIC. AT THE MOMENT...ONLY A FEW ISOLATED SHOWERS
ARE NOTED ALONG THE BOUNDARY FROM CENTRAL OHIO TO NORTHWESTERN
PENNSYLVANIA. AS THE DAY CONTINUES...IT WOULD SEEM THIS SHOULD
INCREASE A BIT WITH DIURNAL INSTABILITY ADDED TO THE PICTURE.
HOWEVER...GIVEN THE DRY ENVIRONMENT...SIGNIFICANT RAINFALL ALONG
THE FRONT SEEMS INCREASINGLY UNLIKELY. AS A RESULT...QPF AND POPS
WERE CUT FOR THE AFTERNOON HOURS. AREAS SOUTHEAST OF PITTSBURGH
STILL STAND THE BEST SHOT AT SEEING SHOWERS THIS
AFTERNOON...HOWEVER WHATEVER DOES DEVELOP IS LIKELY TO BE QUITE
LIGHT. FRIES
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
MODEL CONSENSUS FAVORS A STALLING OF THE FRONT ACROSS NORTHERN
WEST VIRGINIA SUNDAY NIGHT BEFORE IT TURNS NORTHWARD AS A WARM
FRONT ON MONDAY. POPS FOR SHOWERS WERE CONTINUED THROUGH MONDAY
NIGHT BEFORE BEING INCREASED AGAIN ON TUESDAY. KEPT THUNDER
MONDAY AFTERNOON/EVENING AS THE HIGHER CAPE SUGGESTS.
WHILE AGREEMENT ON THE PLACEMENT OF THE FRONT BY TUESDAY BECOMES
LESS PRONOUNCED...THE ECMWF/GFS/NAM ALL LIKE THE IDEA OF TRACKING
A SHRTWV ALONG THE BNDRY BY THE AFTERNOON HOURS. THIS WOULD INCRS
LIFT AND SHEAR ALONG THE FRONTAL ZONE. THESE INGREDIENTS WITH SOME
WEAK INSTABILITY MAY BE SUFFICIENT TO OVERCOME A MODERATELY
STRONG CAP ALONG THE BOUNDARY. THUS...A MENTION OF THUNDERSTORMS
WAS ADDED.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
OVERALL...CONFIDENCE IN EXTENDED FORECAST IS LOWER THAN
NORMAL...SIMILAR TO YESTERDAY. FRONT WILL STILL BE HUNG UP TUESDAY
NIGHT THROUGH WEDNESDAY NIGHT...PROBABLY TO THE NORTH OF THE REGION.
ALTHOUGH COLD FRONT WILL LIKELY BEGIN TO CROSS THE REGION ON
THURSDAY...GFS/ECMWF CANNOT DECIDE WHETHER THE COLD FRONT WILL TAKE
24 OR 48 HOURS TO PUSH ALL THE WAY THROUGH. HAVE BUMPED UP POPS TO
LIKELY THURSDAY NIGHT...BUT OTHERWISE MADE LITTLE CHANGES TO POPS OR
TEMPERATURES.
&&
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS WL CONTINUE THIS MRNG ALTHOUGH BROAD SWATH OF MID
LVL CLDINESS CONTS TO FLOW OVR THE UPR OH VALLEY REGION. STRONG
LOW PRES CROSSING THE GREAT LAKES WL DRAG A WEAK FRONT ACRS AREA
PORTS TODAY. GIVEN THE INITIALLY PALTRY BNDRY LAYER MSTR SUPPLY
AND EXPECTED EWD PROGRESS OF THE SPPRTG SHRTWV...FORECAST WL
FEATURE -SHRA WITH HIGH BASED CIGS AND VEERED WIND...GUSTS OF
WHICH MAY APPRCH 30 KT SHOULD NAM AND RAP MOMENTUM TRANSFER
PROGNOSIS BE REALIZED. CONFIDENCE IN MORE SIGNIFICANT OR
WIDESPREAD DETERIORATION IS NOT SUFFICIENT TO WARRANT TAF MENTION
JUST YET.
.OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/...
THE BOUNDARY SHOULD SHIFT SOUTH OF THE REGION TONIGHT...THEN BE
PULLED NORTHWARD ONCE AGAIN ON MONDAY AS LOW PRES DIGS ACRS THE
GREAT LAKES. FRONT POSITIONING IS QUESTIONABLE THROUGH MUCH OF THE
WEEK...SO OCCASIONAL RESTRICTIONS SHOULD BE ANTICIPATED.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
618 AM EDT SUN APR 7 2013
.SYNOPSIS...
RAIN CHANCES WILL INCREASE TODAY AS A COLD FRONT SLIDES OVER THE REGION.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
TEMPERATURE TREND THIS MORNING IS A BIT WARMER THAN PREVIOUS
FCST...SO MADE SOME UPWARD ADJUSTMENT TO HOURLY NUMBERS. ALSO
ADJUSTED DEW POINTS DOWN...ALSO BASED ON LATEST TRENDS. HIGH TEMPS
WERE FORECAST USING WARMER NAM GUIDANCE. MAINTAINED WIND GUSTS NR
30 KTS GIVEN MOMENTUM TRANSFER FORECAST OF NAM AND RAP MDLS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
MODEL CONSENSUS FAVORS A STALLING OF THE FRONT ACROSS NORTHERN
WEST VIRGINIA SUNDAY NIGHT BEFORE IT TURNS NORTHWARD AS A WARM
FRONT ON MONDAY. POPS FOR SHOWERS WERE CONTINUED THROUGH MONDAY
NIGHT BEFORE BEING INCREASED AGAIN ON TUESDAY. KEPT THUNDER
MONDAY AFTERNOON/EVENING AS THE HIGHER CAPE SUGGESTS.
WHILE AGREEMENT ON THE PLACEMENT OF THE FRONT BY TUESDAY BECOMES
LESS PRONOUNCED...THE ECMWF/GFS/NAM ALL LIKE THE IDEA OF TRACKING
A SHRTWV ALONG THE BNDRY BY THE AFTERNOON HOURS. THIS WOULD INCRS
LIFT AND SHEAR ALONG THE FRONTAL ZONE. THESE INGREDIENTS WITH SOME
WEAK INSTABILITY MAY BE SUFFICIENT TO OVERCOME A MODERATELY
STRONG CAP ALONG THE BOUNDARY. THUS...A MENTION OF THUNDERSTORMS
WAS ADDED.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
OVERALL...CONFIDENCE IN EXTENDED FORECAST IS LOWER THAN
NORMAL...SIMILAR TO YESTERDAY. FRONT WILL STILL BE HUNG UP TUESDAY
NIGHT THROUGH WEDNESDAY NIGHT...PROBABLY TO THE NORTH OF THE REGION.
ALTHOUGH COLD FRONT WILL LIKELY BEGIN TO CROSS THE REGION ON
THURSDAY...GFS/ECMWF CANNOT DECIDE WHETHER THE COLD FRONT WILL TAKE
24 OR 48 HOURS TO PUSH ALL THE WAY THROUGH. HAVE BUMPED UP POPS TO
LIKELY THURSDAY NIGHT...BUT OTHERWISE MADE LITTLE CHANGES TO POPS OR
TEMPERATURES.
&&
.AVIATION /10Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS WL CONTINUE THIS MRNG ALTHOUGH BROAD SWATH OF MID
LVL CLDINESS CONTS TO FLOW OVR THE UPR OH VALLEY REGION. STRONG
LOW PRES CROSSING THE GREAT LAKES WL DRAG A WEAK FRONT ACRS AREA
PORTS TODAY. GIVEN THE INITIALLY PALTRY BNDRY LAYER MSTR SUPPLY
AND EXPECTED EWD PROGRESS OF THE SPPRTG SHRTWV...FORECAST WL
FEATURE -SHRA WITH HIGH BASED CIGS AND VEERED WIND...GUSTS OF
WHICH MAY APPRCH 30 KT SHOULD NAM AND RAP MOMENTUM TRANSFER
PROGNOSIS BE REALIZED. CONFIDENCE IN MORE SIGNIFICANT OR
WIDESPREAD DETERIORATION IS NOT SUFFICIENT TO WARRANT TAF MENTION
JUST YET.
.OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/...
THE BOUNDARY SHOULD SHIFT SOUTH OF THE REGION TONIGHT...THEN BE
PULLED NORTHWARD ONCE AGAIN ON MONDAY AS LOW PRES DIGS ACRS THE
GREAT LAKES. FRONT POSITIONING IS QUESTIONABLE THROUGH MUCH OF THE
WEEK...SO OCCASIONAL RESTRICTIONS SHOULD BE ANTICIPATED.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BISMARCK ND
958 AM CDT SUN APR 7 2013
.UPDATE...
ISSUED AT 953 AM CDT SUN APR 7 2013
MAINLY CHANGES EARLY THIS MORNING...NOW GETTING SNOW FROM MINOT
AND EAST. THE PRECIPITATION HAS MOVED EAST OF WILLISTON AND
STANLEY. ALSO WARMING TEMPERATURES SOUTH CENTRAL KEEPING THE
PRECIPITATION AS RAIN. CANCELLED THE FREEZING RAIN ADVISORY FOR ALL
BUT MCLEAN COUNTY THROUGH NOON...AND EAST THROUGH HARVEY AND SOUTH
THROUGH THE JAMES RIVER VALLEY THROUGH 7 PM.
UPDATE ISSUED AT 708 AM CDT SUN APR 7 2013
UPDATE THIS MORNING MAINLY FOR TEMPERATURES. LOW PRESSURE OVER
EASTERN MONTANA WITH HIGH PRESSURE OVER EASTERN NORTH DAKOTA
EARLY THIS MORNING WITH A SOUTHEAST FLOW OVER WESTERN NORTH DAKOTA
AND LIGHT WINDS IN THE CENTRAL. EXTENSIVE MVFR-IFR STRATUS ACROSS
ALL OF WESTERN AND CENTRAL NORTH DAKOTA. THIS HAS KEPT
TEMPERATURES FROM FALLING AS FAR AS FORECAST...AND DO NOT EXPECT
TEMPERATURES TO DROP MUCH MORE THIS MORNING. THUS RAISED EARLY
MORNING TEMPERATURES IN THE EAST FROM THE LOW TO MID 20S INTO THE
UPPER 20S. BAND OF PRECIPITATION IS MOVING THROUGH THE WEST AND
INTO CENTRAL NORTH DAKOTA. REPORT OF SOME MIXED PRECIPITATION AT
WILLISTON AND A LITTLE UNDER AN INCH OF SNOW. THE WARMER THAN
EXPECTED TEMPERATURES COMBINED WITH ROAD SURFACE TEMPERATURES AT
OR ABOVE FREEZING IN MANY AREAS...SHOULD HELP TO DIMINISH THE
EFFECTS OF ANY FREEZING RAIN. HOWEVER...EXPECT SECONDARY ROADS...
SIDEWALKS AND PARKING LOTS MAY YET BECOME SLIPPERY. WILL HOLD OFF
ON ANY UPDATES TO THE CURRENT FREEZING RAIN ADVISORY AND SEE IF WE
CAN GET A FEW MORE REPORTS AFTER SUNRISE.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 329 AM CDT SUN APR 7 2013
THE MAIN FORECAST CHALLENGES FOR THE SHORT TERM INCLUDE
PRECIPITATION TIMING AND TYPE. THE 00Z MODEL SUITE IS IN
AGREEMENT...THUS HAVE UTILIZED A BLEND OF GUIDANCE.
LATEST RADAR IMAGERY AT 330 AM CDT IS SHOWING SOME SCATTERED LIGHT
RETURNS ACROSS THE SOUTHWEST....AND MORE WIDESPREAD LIGHT RETURNS
OVER NORTHEASTERN MONTANA ASSOCIATED WITH A WEAK UPPER LEVEL IMPULSE.
HOWEVER...SURFACE OBSERVATIONS HAVE NOT REFLECTED PRECIPITATION
REACHING THE GROUND OVER THE SOUTHWEST. THE 05/06Z RAP SOLUTIONS DO
NOT REFLECT THE LIGHT PRECIPITATION OVER THE NORTHEAST AT THIS
TIME...BUT IT DOES PAINT SOME LIGHT PRECIPITATION ACROSS THE
SOUTHWEST. THE 00Z GFS/ECMWF/NAM ALL SHOW LIGHT PRECIPITATION OVER
NORTHEAST MONTANA AT THIS TIME...AND THUS HAVE UTILIZED A BLEND OF
THE 00Z MODEL GUIDANCE IN ADDITION TO THE 05/06Z RAP GUIDANCE.
PRECIPITATION WILL CONTINUE TO SPREAD EAST WITH TIME...FILLING IN
OVER THE WEST OVER THE NEXT FEW HOURS...AND THEN OVER THE CENTRAL
BY LATER THIS MORNING...AS THE UPPER LEVEL IMPULSE MOVES OVER THE
AREA.
LATEST OBSERVATIONS AT 400 AM CDT SHOW THAT TEMPERATURES SOUTH AND
WEST OF THE MISSOURI RIVER REMAIN ABOVE FREEZING...WHILE NORTH AND
EAST...TEMPERATURES ARE IN THE MID TO UPPER 20S. FOLLOWING THE
COLD FRONTAL PASSAGE YESTERDAY...COLD AIR ADVECTION ALOFT IS
UNDERWAY...WITH A SHALLOW WARM LAYER JUST ABOVE THE SURFACE.
PRECIPITATION WILL START AS FREEZING RAIN...WITH SOME SNOW AND
SLEET MIXED IN ACROSS THE WEST...BUT AS TEMPERATURES WARM ACROSS
THE SOUTHWEST AND SOUTH CENTRAL...A TRANSITION TO RAIN WILL OCCUR.
FOR LOCATIONS ACROSS THE NORTH...WHERE TEMPERATURES ARE CURRENTLY
SUBFREEZING...PRECIPITATION WILL START AS SNOW...BUT AS
TEMPERATURES WARM NEAR THE SURFACE WITH COLDER AIR PRESENT ALOFT...A
TRANSITION TO FREEZING RAIN AND THEN TO A MIX OF FREEZING
RAIN...SLEET...AND SNOW AFTER MIDNIGHT.
EVEN THOUGH THE FORECAST PROCESS HAS LED TO INCREASED MIXED
PRECIPITATION (SNOW...SLEET AND FREEZING RAIN) AND DECREASED
COVERAGE OF FREEZING RAIN...HAVE DECIDED TO CONTINUE THE FREEZING RAIN
ADVISORY AT THIS TIME. WILL CONTINUE TO MONITOR AND MAKE CHANGES
IF WARRANTED.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 329 AM CDT SUN APR 7 2013
THE MAIN FORECAST PROBLEM IN THE EXTENDED PERIOD WILL MONDAY THROUGH
MONDAY NIGHT...ACTUALLY BEGINNING LATE SUNDAY NIGHT IN THE FAR WEST.
WILL LEAN MORE TOWARD A ECMWF/GEM SOLUTION OVER THE GFS/NAM FOR QPF
DETAILS.
ALTHOUGH THE STRONG UPPER LEVEL SYSTEM IN THE WEST DIVES SOUTH ON
MONDAY...THERE IS STILL A PIECE OF UPPER LEVEL ENERGY THAT MAKES IT
INTO THE NORTHERN PLAINS. DETERMINISTIC MODELS ARE IN REASONABLE
AGREEMENT IN BRINGING THIS INTO THE LOCAL AREA. ALTHOUGH RATHER
SIGNIFICANT DIFFERENCES IN THE RESULTING PLACEMENT OF THE QPF AS THE
WAVE INTERACT WITH A TIGHTENING BAROCLINIC ZONE ACROSS WESTERN AND
CENTRAL NORTH DAKOTA. THE NAM/GFS ARE FARTHER NORTH WITH THE QPF
THAN THE GEM/ECMWF...ALTHOUGH THE 00 UTC SUNDAY ECMWF HAS COME A
LITTLE FARTHER NORTH THAN PREVIOUS RUNS. LOOKING AT GFS BUFKIT
SOUNDINGS...THERE DOES APPEAR TO BE A 3 TO 6 HOUR PERIOD WITH STRONG
OMEGA OVER WITHIN THE SNOW GROWTH ZONE IN THE WEST CENTRAL AND
SOUTHWEST...WHICH SHOULD YIELD SOME DECENT SNOW AMOUNTS. THIS AREA
EXTENDS EAST ACROSS CENTRAL NORTH DAKOTA DURING THE DAY MONDAY BUT
STRONG HIGH PRESSURE DROPPING SOUTH FROM CANADA WILL INHIBIT FG
FORCING LATER IN THE DAY. THIS SHOULD REDUCE SNOW AMOUNTS AS THE
WAVE MOVES EASTWARD INTO CENTRAL AND EASTERN NORTH DAKOTA.
A COMBINATION OF HPC SNOW AMOUNTS WITH MODEL QPF YIELDS 3 TO 5
INCHES OF SNOW OVER MUCH OF WEST CENTRAL AND SOUTHWEST NORTH
DAKOTA...WITH 2 TO 3 INCHES EXTENDING EAST INTO GRANT AND MORTON
COUNTIES. SNOW TOTALS TAPER TO AN INCH OR TWO EAST OF THE MISSOURI
RIVER. THE NORTHERN EXTENT OF THE HEAVIER SNOW REMAINS ALONG AND
SOUTH OF LAKE SAKAKAWEA...WEST OF THE MISSOURI...THEN ALONG AND
SOUTH OF THE I94 CORRIDOR EAST OF THE MISSOURI. ALTHOUGH SIGNIFICANT
DIFFERENCES STILL REMAIN...FEEL CONFIDENT ENOUGH THAT A WINTER
WEATHER ADVISORY IS WARRANTED OVER THE SOUTHWEST AND WEST CENTRAL.
CONFIDENCE WANES AS YOU GO EAST...BUT WILL EXTEND THE ADVISORY
EAST TO COVER MOST OF THE AREA WEST OF THE MISSOURI AND SOUTH OF THE
LAKE.
AT THIS TIME IT APPEARS THAT THERE SHOULD BE A QUICK TRANSITION FROM
RAIN TO SNOW AS COLD AIR RUSHES SOUTH LATE SUNDAY NIGHT. HOWEVER...A
PERIOD OF MIXED PRECIPITATION CANNOT BE RULED OUT BEFORE THE COLD
AIR IS FIRMLY ENTRENCHED OVER THE AREA BY MONDAY MORNING. AS THE
CANADIAN HIGH DROPS SOUTH WE SHOULD SEE A NICE ISALLOBARIC COMPONENT
MOVE ACROSS THE WEST AND SOUTH CENTRAL ON MONDAY RESULTING IN
SUSTAINED WINDS OF 15 TO 20 MPH AND GUST OF 25 TO 30 MPH. ALTHOUGH
THERE IS NO LOOSE SNOW...WINDS WILL BE STRONG ENOUGH FOR SOME
BLOWING SNOW AS IT FALLS. THUS WILL MAKE THE ADVISORY FOR SNOW AND
BLOWING SNOW...LASTING FROM LATE SUNDAY NIGHT THROUGH LATE MONDAY
NIGHT.
AS THE MAIN UPPER LOW MOVES ONTO THE PLAINS ON TUESDAY...COLD HIGH
PRESSURE OVER SASKATCHEWAN INTO NORTH DAKOTA SHOULD KEEP THE
NORTHERN EXTEND OF THE SYSTEM RIGHT ALONG THE SOUTH DAKOTA BORDER
WITH ANY SIGNIFICANT PRECIPITATION REMAINING SOUTH OF THE STATE.
THEN AS THE SYSTEM BEGINS TO EJECT NORTHEAST TUESDAY NIGHT THE
PRECIPITATION SHIELD TRIES TO PUSH A BIT FARTHER NORTH AND MAY CLIP
THE FAR SOUTH AND SOUTHEAST COUNTIES WITH LIGHT SNOW. AT THIS TIME
WE ARE KEEPING HIGH CHANCE POPS ALONG THE SOUTH DAKOTA
BORDER...TAPERING TO SLIGHT CHANCE POPS AROUND INTERSTATE 94. THE
NORTHERN HALF OF THE CWA IS EXPECTED TO REMAIN DRY TUESDAY AND
TUESDAY NIGHT. TEMPERATURES DURING THIS PERIOD...MONDAY THROUGH
WEDNESDAY...WILL BE BELOW NORMAL WITH 20S NORTH TO 30S SOUTH. WE DO
SEE SOME SLIGHT WARMING BY AROUND THURSDAY AS THE SYSTEM EXITS TO
OUR EAST...BUT A PROGRESSIVE NORTHWEST FLOW WILL BRING A SERIES OF
UPPER LEVEL WAVES INTO THE AREA LATE IN THE WEEK KEEPING OUR WEATHER
UNSETTLED WITH TEMPERATURES NEAR OR BELOW NORMAL.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 708 AM CDT SUN APR 7 2013
WIDESPREAD STRATUS REMAINS OVER THE REGION THIS MORNING. THE MAIN
HAZARDS TO AVIATION INCLUDE THE MVFR/IFR CONDITIONS ASSOCIATED
WITH THE STRATUS...AND FREEZING RAIN AND MIXED PRECIPITATION
EXPECTED TO MOVE THROUGH SOUTH CENTRAL NORTH DAKOTA THROUGHOUT
THE DAY. TEMPERATURES WARMER AT KDIK/KBIS...LIGHT RAIN THERE. A BRIEF
BREAK IN PRECIPITATION WILL BE POSSIBLE LATER THIS
AFTERNOON...BEFORE THE NEXT ROUND OF LIGHT RAIN AND MIXED
PRECIPITATION ARRIVES SUNDAY EVENING AND MONDAY MORNING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 1 AM CDT /MIDNIGHT MDT/ MONDAY TO 1
AM CDT /MIDNIGHT MDT/ TUESDAY FOR NDZ017>020-031>034-040>044.
FREEZING RAIN ADVISORY UNTIL 7 PM CDT THIS EVENING FOR NDZ022-
023-036-037-047-048-050-051.
FREEZING RAIN ADVISORY UNTIL 1 PM CDT THIS AFTERNOON FOR NDZ021.
&&
$$
UPDATE...WAA
SHORT TERM...LTH
LONG TERM...TWH
AVIATION...WAA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
708 AM CDT SUN APR 7 2013
.UPDATE...
ISSUED AT 708 AM CDT SUN APR 7 2013
UPDATE THIS MORNING MAINLY FOR TEMPERATURES. LOW PRESSURE OVER
EASTERN MONTANA WITH HIGH PRESSURE OVER EASTERN NORTH DAKOTA
EARLY THIS MORNING WITH A SOUTHEAST FLOW OVER WESTERN NORTH DAKOTA
AND LIGHT WINDS IN THE CENTRAL. EXTENSIVE MVFR-IFR STRATUS ACROSS
ALL OF WESTERN AND CENTRAL NORTH DAKOTA. THIS HAS KEPT
TEMPERATURES FROM FALLING AS FAR AS FORECAST...AND DO NOT EXPECT
TEMPERATURES TO DROP MUCH MORE THIS MORNING. THUS RAISED EARLY
MORNING TEMPERATURES IN THE EAST FROM THE LOW TO MID 20S INTO THE
UPPER 20S. BAND OF PRECIPITATION IS MOVING THROUGH THE WEST AND
INTO CENTRAL NORTH DAKOTA. REPORT OF SOME MIXED PRECIPITATION AT
WILLISTON AND A LITTLE UNDER AN INCH OF SNOW. THE WARMER THAN
EXPECTED TEMPERATURES COMBINED WITH ROAD SURFACE TEMPERATURES AT
OR ABOVE FREEZING IN MANY AREAS...SHOULD HELP TO DIMINISH THE
EFFECTS OF ANY FREEZING RAIN. HOWEVER...EXPECT SECONDARY ROADS...
SIDEWALKS AND PARKING LOTS MAY YET BECOME SLIPPERY. WILL HOLD OFF
ON ANY UPDATES TO THE CURRENT FREEZING RAIN ADVISORY AND SEE IF WE
CAN GET A FEW MORE REPORTS AFTER SUNRISE.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 329 AM CDT SUN APR 7 2013
THE MAIN FORECAST CHALLENGES FOR THE SHORT TERM INCLUDE
PRECIPITATION TIMING AND TYPE. THE 00Z MODEL SUITE IS IN
AGREEMENT...THUS HAVE UTILIZED A BLEND OF GUIDANCE.
LATEST RADAR IMAGERY AT 330 AM CDT IS SHOWING SOME SCATTERED LIGHT
RETURNS ACROSS THE SOUTHWEST....AND MORE WIDESPREAD LIGHT RETURNS
OVER NORTHEASTERN MONTANA ASSOCIATED WITH A WEAK UPPER LEVEL IMPULSE.
HOWEVER...SURFACE OBSERVATIONS HAVE NOT REFLECTED PRECIPITATION
REACHING THE GROUND OVER THE SOUTHWEST. THE 05/06Z RAP SOLUTIONS DO
NOT REFLECT THE LIGHT PRECIPITATION OVER THE NORTHEAST AT THIS
TIME...BUT IT DOES PAINT SOME LIGHT PRECIPITATION ACROSS THE
SOUTHWEST. THE 00Z GFS/ECMWF/NAM ALL SHOW LIGHT PRECIPITATION OVER
NORTHEAST MONTANA AT THIS TIME...AND THUS HAVE UTILIZED A BLEND OF
THE 00Z MODEL GUIDANCE IN ADDITION TO THE 05/06Z RAP GUIDANCE.
PRECIPITATION WILL CONTINUE TO SPREAD EAST WITH TIME...FILLING IN
OVER THE WEST OVER THE NEXT FEW HOURS...AND THEN OVER THE CENTRAL
BY LATER THIS MORNING...AS THE UPPER LEVEL IMPULSE MOVES OVER THE
AREA.
LATEST OBSERVATIONS AT 400 AM CDT SHOW THAT TEMPERATURES SOUTH AND
WEST OF THE MISSOURI RIVER REMAIN ABOVE FREEZING...WHILE NORTH AND
EAST...TEMPERATURES ARE IN THE MID TO UPPER 20S. FOLLOWING THE
COLD FRONTAL PASSAGE YESTERDAY...COLD AIR ADVECTION ALOFT IS
UNDERWAY...WITH A SHALLOW WARM LAYER JUST ABOVE THE SURFACE.
PRECIPITATION WILL START AS FREEZING RAIN...WITH SOME SNOW AND
SLEET MIXED IN ACROSS THE WEST...BUT AS TEMPERATURES WARM ACROSS
THE SOUTHWEST AND SOUTH CENTRAL...A TRANSITION TO RAIN WILL OCCUR.
FOR LOCATIONS ACROSS THE NORTH...WHERE TEMPERATURES ARE CURRENTLY
SUBFREEZING...PRECIPITATION WILL START AS SNOW...BUT AS
TEMPERATURES WARM NEAR THE SURFACE WITH COLDER AIR PRESENT ALOFT...A
TRANSITION TO FREEZING RAIN AND THEN TO A MIX OF FREEZING
RAIN...SLEET...AND SNOW AFTER MIDNIGHT.
EVEN THOUGH THE FORECAST PROCESS HAS LED TO INCREASED MIXED
PRECIPITATION (SNOW...SLEET AND FREEZING RAIN) AND DECREASED
COVERAGE OF FREEZING RAIN...HAVE DECIDED TO CONTINUE THE FREEZING RAIN
ADVISORY AT THIS TIME. WILL CONTINUE TO MONITOR AND MAKE CHANGES
IF WARRANTED.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 329 AM CDT SUN APR 7 2013
THE MAIN FORECAST PROBLEM IN THE EXTENDED PERIOD WILL MONDAY THROUGH
MONDAY NIGHT...ACTUALLY BEGINNING LATE SUNDAY NIGHT IN THE FAR WEST.
WILL LEAN MORE TOWARD A ECMWF/GEM SOLUTION OVER THE GFS/NAM FOR QPF
DETAILS.
ALTHOUGH THE STRONG UPPER LEVEL SYSTEM IN THE WEST DIVES SOUTH ON
MONDAY...THERE IS STILL A PIECE OF UPPER LEVEL ENERGY THAT MAKES IT
INTO THE NORTHERN PLAINS. DETERMINISTIC MODELS ARE IN REASONABLE
AGREEMENT IN BRINGING THIS INTO THE LOCAL AREA. ALTHOUGH RATHER
SIGNIFICANT DIFFERENCES IN THE RESULTING PLACEMENT OF THE QPF AS THE
WAVE INTERACT WITH A TIGHTENING BAROCLINIC ZONE ACROSS WESTERN AND
CENTRAL NORTH DAKOTA. THE NAM/GFS ARE FARTHER NORTH WITH THE QPF
THAN THE GEM/ECMWF...ALTHOUGH THE 00 UTC SUNDAY ECMWF HAS COME A
LITTLE FARTHER NORTH THAN PREVIOUS RUNS. LOOKING AT GFS BUFKIT
SOUNDINGS...THERE DOES APPEAR TO BE A 3 TO 6 HOUR PERIOD WITH STRONG
OMEGA OVER WITHIN THE SNOW GROWTH ZONE IN THE WEST CENTRAL AND
SOUTHWEST...WHICH SHOULD YIELD SOME DECENT SNOW AMOUNTS. THIS AREA
EXTENDS EAST ACROSS CENTRAL NORTH DAKOTA DURING THE DAY MONDAY BUT
STRONG HIGH PRESSURE DROPPING SOUTH FROM CANADA WILL INHIBIT FG
FORCING LATER IN THE DAY. THIS SHOULD REDUCE SNOW AMOUNTS AS THE
WAVE MOVES EASTWARD INTO CENTRAL AND EASTERN NORTH DAKOTA.
A COMBINATION OF HPC SNOW AMOUNTS WITH MODEL QPF YIELDS 3 TO 5
INCHES OF SNOW OVER MUCH OF WEST CENTRAL AND SOUTHWEST NORTH
DAKOTA...WITH 2 TO 3 INCHES EXTENDING EAST INTO GRANT AND MORTON
COUNTIES. SNOW TOTALS TAPER TO AN INCH OR TWO EAST OF THE MISSOURI
RIVER. THE NORTHERN EXTENT OF THE HEAVIER SNOW REMAINS ALONG AND
SOUTH OF LAKE SAKAKAWEA...WEST OF THE MISSOURI...THEN ALONG AND
SOUTH OF THE I94 CORRIDOR EAST OF THE MISSOURI. ALTHOUGH SIGNIFICANT
DIFFERENCES STILL REMAIN...FEEL CONFIDENT ENOUGH THAT A WINTER
WEATHER ADVISORY IS WARRANTED OVER THE SOUTHWEST AND WEST CENTRAL.
CONFIDENCE WANES AS YOU GO EAST...BUT WILL EXTEND THE ADVISORY
EAST TO COVER MOST OF THE AREA WEST OF THE MISSOURI AND SOUTH OF THE
LAKE.
AT THIS TIME IT APPEARS THAT THERE SHOULD BE A QUICK TRANSITION FROM
RAIN TO SNOW AS COLD AIR RUSHES SOUTH LATE SUNDAY NIGHT. HOWEVER...A
PERIOD OF MIXED PRECIPITATION CANNOT BE RULED OUT BEFORE THE COLD
AIR IS FIRMLY ENTRENCHED OVER THE AREA BY MONDAY MORNING. AS THE
CANADIAN HIGH DROPS SOUTH WE SHOULD SEE A NICE ISALLOBARIC COMPONENT
MOVE ACROSS THE WEST AND SOUTH CENTRAL ON MONDAY RESULTING IN
SUSTAINED WINDS OF 15 TO 20 MPH AND GUST OF 25 TO 30 MPH. ALTHOUGH
THERE IS NO LOOSE SNOW...WINDS WILL BE STRONG ENOUGH FOR SOME
BLOWING SNOW AS IT FALLS. THUS WILL MAKE THE ADVISORY FOR SNOW AND
BLOWING SNOW...LASTING FROM LATE SUNDAY NIGHT THROUGH LATE MONDAY
NIGHT.
AS THE MAIN UPPER LOW MOVES ONTO THE PLAINS ON TUESDAY...COLD HIGH
PRESSURE OVER SASKATCHEWAN INTO NORTH DAKOTA SHOULD KEEP THE
NORTHERN EXTEND OF THE SYSTEM RIGHT ALONG THE SOUTH DAKOTA BORDER
WITH ANY SIGNIFICANT PRECIPITATION REMAINING SOUTH OF THE STATE.
THEN AS THE SYSTEM BEGINS TO EJECT NORTHEAST TUESDAY NIGHT THE
PRECIPITATION SHIELD TRIES TO PUSH A BIT FARTHER NORTH AND MAY CLIP
THE FAR SOUTH AND SOUTHEAST COUNTIES WITH LIGHT SNOW. AT THIS TIME
WE ARE KEEPING HIGH CHANCE POPS ALONG THE SOUTH DAKOTA
BORDER...TAPERING TO SLIGHT CHANCE POPS AROUND INTERSTATE 94. THE
NORTHERN HALF OF THE CWA IS EXPECTED TO REMAIN DRY TUESDAY AND
TUESDAY NIGHT. TEMPERATURES DURING THIS PERIOD...MONDAY THROUGH
WEDNESDAY...WILL BE BELOW NORMAL WITH 20S NORTH TO 30S SOUTH. WE DO
SEE SOME SLIGHT WARMING BY AROUND THURSDAY AS THE SYSTEM EXITS TO
OUR EAST...BUT A PROGRESSIVE NORTHWEST FLOW WILL BRING A SERIES OF
UPPER LEVEL WAVES INTO THE AREA LATE IN THE WEEK KEEPING OUR WEATHER
UNSETTLED WITH TEMPERATURES NEAR OR BELOW NORMAL.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 708 AM CDT SUN APR 7 2013
WIDESPREAD STRATUS REMAINS OVER THE REGION THIS MORNING. THE MAIN
HAZARDS TO AVIATION INCLUDE THE MVFR/IFR CONDITIONS ASSOCIATED
WITH THE STRATUS...AND FREEZING RAIN AND MIXED PRECIPITATION
EXPECTED TO MOVE FROM WESTERN...INTO CENTRAL NORTH DAKOTA
THROUGHOUT THE DAY. AS TEMPERATURES WARM AT KDIK...LIGHT
FREEZING RAIN WILL GIVE WAY TO LIGHT RAIN. A BRIEF BREAK IN
PRECIPITATION WILL BE POSSIBLE LATER THIS AFTERNOON...BEFORE THE
NEXT ROUND OF LIGHT RAIN AND MIXED PRECIPITATION ARRIVES SUNDAY
EVENING AND MONDAY MORNING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 1 AM CDT /MIDNIGHT MDT/ MONDAY TO 1
AM CDT /MIDNIGHT MDT/ TUESDAY FOR NDZ017>020-031>034-040>044.
FREEZING RAIN ADVISORY UNTIL 1 PM CDT THIS AFTERNOON FOR NDZ002-
010-019>021-034-035-046.
FREEZING RAIN ADVISORY UNTIL 11 AM CDT /10 AM MDT/ THIS MORNING
FOR NDZ001-009-017-018-033-041.
FREEZING RAIN ADVISORY FROM 11 AM THIS MORNING TO 7 PM CDT THIS
EVENING FOR NDZ003-011-012-022-023-036-037-047-048-050-051.
&&
$$
UPDATE...TWH
SHORT TERM...LTH
LONG TERM...TWH
AVIATION...LTH
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
652 AM EDT SUN APR 7 2013
.SYNOPSIS...
COLD FRONT STALLS ACROSS THE EXTREME NORTHERN SECTIONS OVERNIGHT...THEN
LIFTS BACK NORTH DURING THE DAY ON MONDAY. WEATHER REMAINS UNSETTLE
TUESDAY AND WEDNESDAY. A STRONG COLD FRONT PASSES THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
630 AM UPDATE...
CONTINUED TO NUDGE POPS DOWNWARD BETWEEN THE 12Z-18Z TIME FRAME
WITH VERY LIMITED MOISTURE PER LATEST RUC SOUNDINGS AND NEAR-TERM
CONVECTIVE OUTPUT. STILL WILL ALLOW FOR SOME LATE-DAY DEVELOPMENT
ACROSS THE NORTHERN ZONES AROUND THE 21Z SUN-00Z MON TIME FRAME.
ALSO...LATEST NAM12.06 GUIDANCE COMING IN WITH CONTINUED ELEVATED
INSTABILITY ACROSS THE NORTHERN ZONES BETWEEN 00Z-06Z TONIGHT.
EL/S AND CLOUD TOPS LOOK LOW ENOUGH TO LEAVE THUNDER OUT BUT
SOMETHING FOR THE NEXT SHIFT TO EXAMINE.
PREVIOUS FORECAST...
04Z SURFACE OBS DEPICTING SUBTLE WIND SHIFT ACROSS FORECAST AREA
ROUGHLY FROM THE NW OHIO ZONES SE-WARD TOWARDS NICHOLAS/FAYETTE
COUNTIES IN WV. SOUTH OF THIS FEATURE WIND DIRECTION S/SSW WITH
RECOVERING DEWPOINTS GENERALLY IN THE LOWER 30S WHILE NORTH OF
THIS BOUNDARY WIND DIRECTION MORE SSE WITH DEWPOINTS STILL DOWN IN
THE UPPER TEENS TO LOWER 20S. A WEAK LINE OF SHOWERS STRETCHED
FROM FAR NW OHIO INTO CENTRAL INDIANA AND WAS PUSHING ENE-WARD.
APPEARS HOWEVER VERY LITTLE PRECIP WAS ACTUALLY REACHING THE
SURFACE HOWEVER AS NOT FINDING ANY SFC OBS OUT THAT WAY REPORTING
ANY PRECIP WITH VERY HIGH CLOUD BASES STILL AROUND 10KFT. S/W
TROUGH AND SFC LOW PRESSURE TO AFFECT THE AREA TODAY STILL
CURRENTLY OUT OVER THE UPPER MIDWEST...WITH LOW PRESSURE CENTERED
OVER WESTERN WI. PRIMARY FORECAST CONCERN FOR THIS PERIOD REVOLVED
AROUND APPROACHING COLD FRONT AND SUBSEQUENT SHOWERS/THUNDERSTORMS
CHANCES.
OPERATIONAL NWP IN GOOD AGREEMENT WITH REGARD TO GENERAL FEATURES
SUNDAY. AFOREMENTIONED S/W TROUGH AND SFC LOW CONTINUING EASTWARD
TODAY FROM UPPER MICHIGAN AT 12Z TO SW QUEBEC BY 00Z MON. COLD FRONT
ASSOC WITH IT WILL PROGRESS EASTWARD AS WELL BUT WILL STALL OUT WEST
TO EAST NEAR OR JUST NORTH OF THE CWA BORDER BY 00Z MON AS IT
ENCOUNTERS INCREASING W/SW UNIDIRECTIONAL FLOW. INTERESTINGLY
ENOUGH...DESPITE THE PASSAGE OF THE S/W TROUGH TO THE NORTH HEIGHTS
ACTUALLY REMAIN CONSTANT OR EVEN RISE A BIT TODAY. PRECIP CHANCES
SOMEWHAT PROBLEMATIC TODAY WITH A COUPLE OF LIMITING FACTORS TO
CONSIDER. FIRST...AS THE COLD FRONT SLOWS ACROSS CENTRAL OHIO BEST
LLVL MOISTURE CONTINUES ESE-WARD AWAY FROM FRONTAL CONVERGENCE WHICH
MAY HINDER CONTINUED DEVELOPMENT. SECOND...DESPITE THE WARMER DEWPOINTS
TEMPS...A STOUT DRY LAYER STILL EXISTS. LATEST NAM STILL DEPICTING A
20-25F DEGREE DEWPOINTS DEPRESSION EARLY/MID AFTERNOON AT LOCATIONS
SUCH AS PKB...AND SUSPECT THAT THOSE PROGGED DEWPOINTS IN THE UPPER
40S STILL MAY BE ON THE HIGH SIDE. NEAR-TERM CONVECTIVE MODELS ALL
SHOW ANY POTENTIAL LINE OF SHOWERS LIMPING INTO THE AREA AND
DISSIPATING AS IT DOES SO. NOT GOING TO DRASTICALLY CUT POPS WITH
THIS FORECAST PACKAGE BUT WILL REDUCE THEM TO CHANCE CATEGORY AT
BEST. WILL ALSO CONTINUE TO KEEP THE SOUTHERN COALFIELDS AND VA
COUNTIES DRY. REGARDING ANY THUNDER POTENTIAL...AN AXIS OF INSTABILITY
MOVES IN BTWN 18Z SUN AND 00Z MON AHEAD OF FRONT WITH SFC-BASED CAPE
AROUND 300J/KG AND MUCAPE VALUES UP TO AROUND 600J/KG ACROSS THE NW
ZONES. WITH THAT IN MIND WILL CARRY CHANCE THUNDER DURING THIS TIME
ROUGHLY ALONG AND NW OF A LINE FROM CKB TO HTS. ANY CONVECTION WILL
BE HIGH-BASED OF COURSE AND WITH DCAPE VALUES 800-1000J...CAN/T RULE
OUT THE POSSIBILITY OF A BRIEF GUST HERE OR THERE AROUND 20-30KTS
WITH A STORM. OUTSIDE OF PRECIP POTENTIAL...MAX TEMPS ONCE AGAIN
CLIMB INTO THE UPPER 60S/LOWER 70S LOWLANDS WITH PERHAPS MID 60S FAR
NW ZONES WITH ADDITIONAL CLOUD COVER.
BETWEEN 00Z MON-12Z MON THE COLD FRONT REMAINS ESSENTIALLY
STALLED BUT MAY MAKE SOME INROADS JUST INTO THE NORTHERN ZONES
BEFORE RETREATING NORTHWARD TOWARDS DAWN MON. HIGHEST CHANCE POPS
WILL BE ACROSS NE ZONES BUT WILL GENERALLY BEGIN TO WANE DURING
THE OVERNIGHT HOURS...WITH ONLY A SLIGHT CHANCE OF PRECIP FOR
LOWLANDS NORTH OF INTERSTATE 64. A BIT MORE LLVL MOISTURE ARRIVES
ALONG WITH SOME ADDED LIFT FROM AN APPROACHING VORT MAX TO BUMP UP
PRECIP POTENTIAL TOWARDS THE DAWN HOURS.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
GFS/ECMWF MODELS IN AGREEMENT WITH H1000 KINK OF THE EAST TO WEST
QUASI STATIONARY FRONTAL BOUNDARY JUST NORTH OF THE AREA...AND THE
NAM FURTHER SOUTH JUST ALONG OUR BORDER BY 12Z MONDAY. EITHER
WAY...PCPN AHEAD OF THE FRONT COULD REACH OUR NORTHERN
SECTORS...SO KEPT HIGH CHANCE POPS THROUGH MONDAY NIGHT INCLUDING
NORTHEAST MOUNTAINS. THIS SCENARIO WILL KEEP MOST OF THE AREA
UNDER THE WARM SECTOR FOR WARMER THAN SEASONAL TEMPERATURES
THROUGH THE PERIOD.
THE CMC/ECMWF BRING A SHORT WAVE AND ASSOCIATED VORTICITY MAX
NORTH OF THE AREA...SUGGESTING MID LEVEL ENERGY COULD INFLUENCE
THE AFOREMENTIONED BOUNDARY TO PRODUCE SHOWERS OR STORMS NORTH OF
OUR CWA. HOWEVER...THE GFS VORT MAX MOVES ACROSS SOUTHEAST OH BY
12Z MONDAY...QUICKLY MOVING NORTHEAST AND A SECOND VORT MAX BY 00Z
TUESDAY. IF THE GFS SOLUTION MATERIALIZE...COULD SEE MORE
CONVECTION DEVELOPING AROUND THE QUASI STATIONARY BOUNDARY LATE
MONDAY...MAINLY ACROSS THE NORTH AND NORTHEAST MOUNTAINS.
ADJUSTED DOWN POPS ACROSS THE EXTREME SOUTHERN CWA AS MAY NOT SEE
MORE THAN AN ISOLATED SHOWER IF ANY MONDAY THROUGH TUESDAY.
KEPT TEMPERATURES AS PREVIOUS FORECAST AS THEY LOOK ON TRACK WITH
A WARMING TREND EXPECTED THROUGH MID WEEK UNDER SOUTHWEST FLOW.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
FLAT RIDGING EARLY ON GIVES WAY TO TROUGHINESS LATE IN THE WEEK.
STILL A QUESTION OF WHERE AN E-W FRONT BENEATH THE W FLOW ALOFT ENDS
UP. THE ECMWF SHOWS AN EASTERN CANADIAN TROUGH DIGGING INTO THE
NORTHEASTERN STATES...PUSHING A SURFACE FRONT INTO THE CWA TUE
NT-WED AND SO DOES HPC...EVEN AS OTHER MODELS HAVE STRONGER RIDGING
OVER THE AREA BY THAT TIME...PUSHING THE NORTHERN STREAM TROUGH
FARTHER N. AS SUCH...HAVE A SLIGHT CHANCE FOR SHOWERS N TUE NT
FOLLOWED BY A MODEST INCREASE IN POPS FROM THE W WED PER DIURNAL
CONSIDERATIONS IN THE INCREASINGLY WARM AND SOMEWHAT HUMID AIR...AND
A COLD FRONT APPROACHING FROM THE W. TIME OF YEAR AND RECENT TRENDS
DO FAVOR ECMWF/HPC HERE.
ECMWF AND HPC ARE ALSO ONLY SOLNS HOLDING BACK COLD FRONT FROM THE W
UNTIL FRI...GRANTED THE 12Z ECMWF LOOKS ALMOST EXACTLY LIKE HPC
DEPICTION FOR FRI. OPTED WITH A COMPROMISE AND SOMEWHAT SMOOTHED
SOLN WITH THE HIGHEST POPS THU AND THU NT WHEN SHOWERS ARE LIKELY.
POPS...TEMPERATURES AND DEW POINTS GRADUALLY DECREASE FRI AND FRI NT
/NOTWITHSTANDING THE DIURNAL RISE IN TEMPERATURES FRI/ WITH THE
FRONTAL PASSAGE IN AGREEMENT WITH THE HPC WIND FIELDS.
THE INCREASINGLY WARM AND HUMID AIR WILL EVENTUALLY PROVIDE
INSTABILITY ESPECIALLY BUT NOT EXCLUSIVELY WITH THE AFTERNOON
HEATING...AND AVAILABLE FOR STRENGTHENING FLOW AND FORCING TO ACT ON
AS THE FRONT APPROACHES. WHILE MODEL DIFFERENCES WITH THE SYNOPTIC
SCENARIO ARE STILL TO GREAT TO HONE IN ON SPECIFIC PARAMETERS...IT
SEEMS REASONABLE WE MAY BE LOOKING AT AT LEAST MARGINAL FAVORABILITY
FOR SEVERE WED AND / OR THU...AND WELL HONE HWO CONVECTIVE MENTION
INTRODUCED EARLY THIS MORNING IN ON THIS IDEA.
IN THE WAKE OF TH FRONT...THE WEATHER COOLS DOWN AND DRIES OUT FOR
THE START OF NEXT WEEKEND...ALTHOUGH NOT MUCH IF ANY BELOW NORMAL
GIVEN ZONAL FLOW OF PACIFIC ORIGIN.
BLENDED IN MOSGUIDE AND HPC FOR TEMPERATURES IN MOST CASES. THERE
WERE NO MAJOR CHANGES ALTHOUGH NOW HAVE CRW HITTING 80 FOR THE FIRST
TIME THIS YEAR ON WED...WHICH IS IN AGREEMENT WITH THE GFS ENSEMBLE
MEAN AND HPC.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
12Z SUNDAY THROUGH 12Z MONDAY... VFR CONDITIONS ARE EXPECTED TO
PREVAIL THROUGH THE VALID PERIOD. CIGS WILL LOWER AND THICKEN
TODAY ACROSS THE NORTHERN PORTIONS OF THE AREA...BUT ARE EXPECTED
TO REMAIN LOW VFR AROUND 5-7KFT AS A FRONTAL BOUNDARY APPROACHES
THE REGION. A CHANCE OF PRECIP WILL ALSO ACCOMPANY THE FRONT WITH
A CHANCE OF A THUNDERSTORM MAINLY THIS AFTERNOON ACROSS THE NORTH.
BRIEF MVFR VIS IS POSSIBLE WITH A HEAVIER SHOWER AND/OR THUNDERSTORM.
SURFACE WINDS WILL CONTINUE ON THE GUSTY SIDE TODAY OUT OF THE
SOUTHWEST...WITH OCCASIONAL GUSTS AROUND 20KTS LOWLANDS AND 20-25
KT RANGE ACROSS HIGHER TERRAIN COUNTIES. ANOTHER AVIATION CONCERN
AT THE OUTSET THIS MORNING IS A STRONG LOW LEVEL SOUTHWESTERLY JET
CENTERED AROUND 1500FT AGL...WHERE WIND SPEEDS ARE AROUND
35-40KTS. THESE WIND SPEEDS SHOULD BEGIN TO SUBSIDE AROUND 14Z-15Z.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z MONDAY...
FORECAST CONFIDENCE...MEDIUM.
ALTERNATE SCENARIOS: WIND GUSTS TODAY MAY BE STRONGER THAN FORECAST.
TIMING OF FRONTAL BOUNDARY AND SHOWERS MAY VARY FROM FORECAST.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22
EDT 1HRLY 07 08 09 10 11 12 13 14 15 16 17 18
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H M H
EKN CONSISTENCY H H H H H H H H H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 12Z MONDAY...
IFR POSSIBLE IN SHOWERS AND THUNDERSTORMS WEDNESDAY NIGHT AND THURSDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...ARJ/50
NEAR TERM...50
SHORT TERM...ARJ
LONG TERM...TRM
AVIATION...50
AREA FORECAST DISCUSSION...
NWS PORTLAND OR
855 AM PDT SUN APR 7 2013
.SYNOPSIS...A LOW PRESSURE SYSTEM IS NOW PUSHING EAST OF THE CASCADES
THIS MORNING. SNOW IS FALLING IN THE HIGH CASCADES AND WILL INCREASE
TODAY AS FLOW TURNS WESTERLY. SNOW LEVELS WILL BE NEAR OR BELOW THE
CASCADE PASSES. ELSEWHERE RAIN WILL TAPER TO SHOWERS AND SCATTERED
THUNDERSTORMS AS A COLD UPPER LEVEL LOW MOVES ONSHORE THIS AFTERNOON
AND EVENING. THUNDERSTORMS MAY HAVE SMALL HAIL AND GUSTY WINDS
THROUGH THIS EVENING. SHOWERS WILL LINGER INTO MONDAY...THEN TAPER
OFF AS A RIDGE OF HIGH PRESSURE BUILDS FOR A DRIER AND WARMER
WEATHER TUESDAY. ANOTHER SYSTEM IS EXPECTED TO BRING MORE RAIN
WEDNESDAY.
&&
.UPDATE...SURFACE LOW PRESSURE IS NOW FILLING AND MAKING A BEELINE
EAST OF THE CASCADES THIS MORNING. WE DO STILL HAVE A PERIOD OF
PRESSURE RISES BEHIND THE DEPARTING LOW...BUT WIND SUPPORT ALOFT HAS
EASED FROM EARLIER WHERE WE SAW GUSTS TO 60 MPH IN THE COAST RANGE
AND 52 MPH IN THE VALLEY. THIS WILL EASE THE GUST POTENTIAL
SUPPORTING GUSTS OF 30-35 MPH IN THE VALLEY...WITH GUSTS 40-45 MPH
IN THE HIGHER TERRAIN OF THE COAST RANGE. THEREFORE...WILL DROP THE
WIND ADVISORY FOR THE VALLEY AND THE HIGH WIND WARNING FOR THE COAST
RANGE. EXPECT IT TO REMAIN WINDY AT THE EAST END OF THE COLUMBIA
RIVER GORGE AND THE CASCADES TODAY.
COLD ADVECTION WILL CONTINUE TODAY...THUS DO NOT EXPECT MUCH WARMING
FROM CURRENT READINGS. HIGHER ELEVATION SNOTELS IN WASHINGTON HAVE
REPORTED ANYWHERE FROM 3-6 INCHES OF SNOWFALL SO FAR...2" AT THE
SANTIAM PASS SUMMIT WITH 4" OR SO AT THE HIGHER ELEVATION SNOTELS OF
NORTH OREGON...LIGHTER AMOUNTS IN LANE COUNTY WHERE FREEZING LEVELS
ARE STILL A BIT HIGHER. EXPECT ANOTHER 4-6" OF SNOW POSSIBLE IN S
WA...WITH 4-8" IN THE HIGHER ELEVATION CASCADE LOCATIONS TODAY.
WEBCAMS CONFIRM SNOW IS NOW FALLING AT THE PASSES AND EXPECT SNOW
LEVELS TO CONTINUE TO FALL.
WITH REGARDS TO THUNDERSTORMS...WITH CURRENT READINGS IN THE MID TO
UPPER 40S...WE DO NOT EXPECT SFC TEMPS TO RISE MUCH ABOVE 50 TODAY.
DO EXPECT LAPSE RATES TO GET BETTER THIS AFTERNOON AS THE COLD POOL
MOVES IN...AND STILL EXPECT SOME HEAVIER SHOWERS OR THUNDERSTORMS.
KMD
.SHORT TERM...DISCUSSION UNCHANGED....TODAY THROUGH WEDNESDAY...THE
CIRCULATION OF A DEVELOPING LOW PRESSURE SYSTEM IS APPARENT ON
KLGX/KRTX NWS DOPPLER RADARS...PRESENTLY MOVING INTO THE LONG BEACH
PENINSULA OF PACIFIC COUNTY WA. THIS SYSTEM IS A LITTLE FARTHER
NORTH AND A LITTLE STRONGER THAN MOST MODELS SUGGESTED...WITH BUOY
46029 AND HOME WEATHER STATIONS ON THE LONG BEACH PENINSULA
REASONABLY SUGGESTING A CENTRAL PRESSURE OF ABOUT 997 MB.
LATEST RUNS OF THE HRRR 3 KM MODEL DEPICT AN ELONGATED SHAPE TO THE
LOW... EXTENDING FROM THE S WA COAST SOUTHWESTWARD. THIS APPEARS
REASONABLE CONSIDERING THE WIND FIELD APPARENT ALONG THE COAST AND
SHOWN BY BUOYS IN THE COASTAL WATERS. THUS THERE MAY BE A BIT OF A
LULL TO THE WIND ALONG OUR NORTH COAST ZONES INITIALLY AS THE LOW
MOVES ONSHORE. BEHIND THE LOW...HRRR AND NAM HAVE BEEN VERY INSISTENT
ON A STRONG SURGE OF NW-W WIND IN THE BENT BACK OCCLUSION ON THE BACK
SIDE OF THE LOW. THIS WILL CAUSE A SURGE OF WIND FROM THE SW-W AND
EVENTUALLY NW WIND ALONG THE COAST IN THE COMING HOURS...SO IF ONE
SURGE OF WIND EASES IT DOES NOT NECESSARILY MEAN THE EVENT IS OVER.
THE CONSEQUENCES OF THE STRONGER LOW AND MORE NORTHERN TRACK WILL BE
INCREASED CONFIDENCE IN THE WIND ADVISORY FOR THE WILLAMETTE VALLEY
AND A LITTLE CONCERN THE STRONGER WINDS MAY PUSH INTO KELSO/LONGVIEW.
ADDITIONALLY...IT APPEARS A LOW-END HIGH WIND WARNING WILL VERIFY FOR
THE OREGON COAST AND COAST RANGE. WILL LEAVE ALL WIND HIGHLIGHTS AS
IS FOR NOW...THE OVERALL FORECAST LOOKS PRETTY WELL ON TRACK WITH
GUSTS 50-60 MPH WIDESPREAD FOR THE OR COAST AND LOCAL GUSTS TO 70 MPH
FOR THE MOST EXPOSED AREAS. SOUTH WIND GUSTS 25-35 MPH ARE ALREADY
DEVELOPING IN THE TUALATIN AND CENTRAL/SOUTH WILLAMETTE VALLEY. THESE
WILL GET STRONGER WITH 35-45 MPH GUSTS LIKELY TO DEVELOP FOR THE
WILLAMETTE VALLEY AND CLARK COUNTY WITHIN THE NEXT COUPLE HOURS AS
PRESSURE RISES BEGIN IN EARNEST.
ASIDE FROM TRACKING THE LOW AND ASSOCIATED WIND PATTERN THE OTHER
FORECAST CHALLENGES OF THE DAY ARE...1. HOW PROLIFIC THUNDERSTORMS
WILL BE TODAY AND 2. HOW MUCH SNOW WILL FALL IN THE CASCADES.
THUNDERSTORMS...NAM BUFR SOUNDINGS SHOW A VERY STRONG DIRECTIONAL
SHEAR PROFILE WILL QUICKLY BECOME UNIDIRECTIONAL AS THE MORNING
PROGRESSES. HOWEVER A SECONDARY TROUGH IS EXPECTED TO MOVE IN LATER
THIS AFTERNOON AS THE COLD POOL ALOFT DIPS INTO WESTERN WA AND
NORTHWEST OREGON. LAPSE RATES LOOK MARGINAL FOR THUNDERSTORMS...BUT
IMPROVE AS THE AFTERNOON PROGRESSES. WITH SFC TEMPS IN THE LOW 50S WE
SHOULD BE ABLE TO MUSTER ABOUT 400-600 J/KG OF CAPE AND LIFTED
INDICES OF -2 TO -3 DEG C...WHICH WITH LITTLE TO NO CAPPING WOULD BE
PLENTY TO SUGGEST DEEP CONVECTION. SO WE INCREASED THUNDERSTORM
COVERAGE TO SCATTERED AS THIS SETUP IS ABOUT AS GOOD AS IT GETS IN A
POST-FRONTAL ENVIRONMENT. WITH 25-35 KT WESTERLY FLOW AT 850 MB ANY
ORGANIZED THUNDERSTORMS MAY MIX DOWN GUSTY WINDS. TERRAIN DRIVEN FLOW
MAY PRODUCE A LITTLE DIRECTIONAL SHEAR AS WELL...WHICH COULD LEAD TO
SOME WEAK ROTATION WITH THE STRONGER CELLS. ANY THUNDERSTORMS SHOULD
DIE DOWN QUICKLY AFTER SUNSET AS SFC TEMPS COOL AND THE AIR MASS
STABILIZES.
SNOW...SNOW AMOUNTS IN THE CASCADES HAVE THUS FAR BEEN UNIMPRESSIVE
WITH ABOUT 2-4 INCHES MOST LOCATIONS ABOVE 4000 FT. HOWEVER AS LOW
PRESSURE CROSSES THE CASCADES FLOW WILL BECOME MORE OROGRAPHIC. WEST
WINDS 25-35 KT AT 850 MB WILL ENHANCE SNOWFALL IN THE CASCADES...SO A
GOOD 6-12 INCHES LOOK LIKELY ABOVE 4500-5000 FT BY LATER TONIGHT.
SNOW LEVELS WILL BE LOWERING...SO THE PASSES COULD GET A FEW SLUSHY
INCHES OF SNOW THIS AFTERNOON AND TONIGHT. SNOW WILL GRADUALLY TAPER
OFF MONDAY.
A WEAK SHORTWAVE MAY KEEP A FEW SHOWERS IN THE REGION THROUGH MONDAY.
HOWEVER IT APPEARS WE WILL DRY OUT BY TUESDAY AS RIDGING BUILDS INTO
OREGON AND WASHINGTON. 850 MB TEMPS REBOUND TO ABOUT +5 DEG C TUE
AFTERNOON...PROBABLY ENOUGH FOR LOWER 60S IN THE VALLEYS. THIS RIDGE
PROBABLY WILL NOT BE STRONG TO KEEP CLOUD COVER TO OUR NORTH...AND
THE NORTH COAST MAY GET BRUSHED WITH SOME RAIN OR DRIZZLE TUE/TUE
NIGHT. THE RIDGE COLLAPSES WEDNESDAY...ALLOWING ANOTHER FRONT TO SAG
SOUTH AND SPREAD RAIN INTO OUR FORECAST AREA. WEAGLE
.LONG TERM...MAIN CHANGES TO THE EXTENDED FORECAST WERE TO INCREASE
POPS SLIGHTLY AS IT APPEARS WE REMAIN IN A ZONAL AND PROGRESSIVE
PATTERN AFTER WEDNESDAYS FRONTAL SYSTEM. THIS MEANS NEAR OR SLIGHTLY
BELOW NORMAL TEMPERATURES WITH RAIN AT TIMES FOR THE LATE WEEK
PERIOD. WEAGLE
&&
.AVIATION...A MIX OF MVFR/VFR AND BREEZY CONDITIONS WILL CONTINUE
ACROSS MUCH OF THE FORECAST AREA THROUGH TODAY. CONDITIONS WILL
GRADUALLY RELAX BY THIS AFTERNOON AS THE AIR MASS DESTABILIZES...
WITH OCCASIONAL SHOWERS BRINGING A THREAT FOR BRIEF HEAVY
RAIN...SMALL HAIL AND LIGHTNING. THIS ACTIVITY SHOULD BEGIN TO
WANE BY THIS EVENING. A RELATIVELY UNSTABLE AIR MASS WILL PERSIST
INTO TONIGHT KEEPING MANY LOCATIONS VFR...WITH SOME PATCHY MVFR
CIGS.
KPDX AND APPROACHES...EXPECT PREDOMINANTLY VFR CONDITIONS THE NEXT
24 HRS. GUSTY WINDS CONTINUE THROUGH EARLY THIS AFTERNOON. THERE
IS A CHANCE FOR A THUNDERSTORM TO IMPACT THE TERMINAL THIS
AFTERNOON AND EARLY EVENING...BRINGING OCCASIONAL MVFR CIGS WITH
IT. /27
&&
.MARINE...THE SYSTEM THAT BROUGHT STRONG WINDS TO THE COASTAL
WATERS HAS NOW PUSHED FURTHER INLAND THIS MORNING. WESTERLY WINDS
WILL CONTINUE IN THE 20 TO 25 KT RANGE BEHIND THE FRONT THROUGH
LATE TONIGHT...BUT MAY SEE BRIEF PERIODS THIS MORNING WHERE WINDS
DROP BELOW CRITERIA. SEAS WILL ALSO REMAIN AROUND 10 TO 12 FT
TODAY AND TONIGHT.
HIGH PRESSURE WILL THEN BEGIN TO BUILD INTO THE REGION MONDAY...
CAUSING WINDS TO SUBSIDE AND SEAS TO RELAX. THIS SHOULD CONTINUE
UNTIL MIDDAY TUESDAY WHEN A WEAKENING FRONT BRINGS A BURST OF 20
TO 25 KT WINDS TO PRIMARILY THE NORTHERN WATERS. ANOTHER STORM
SYSTEM WILL SLIDE BY TO OUR NORTH WEDNESDAY...CAUSING SOUTH WINDS
TO INCREASE ONCE AGAIN AND SEAS TO BRIEFLY POP UP NEAR 10 FT.
HIGH PRESSURE SHOULD THEN CAUSE WINDS AND SEAS TO RELAX LATE IN
THE WORK WEEK. /NEUMAN /27
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL 11 PM PDT THIS EVENING FOR
CASCADES IN LANE COUNTY-NORTHERN OREGON CASCADES.
WA...WINTER WEATHER ADVISORY UNTIL 11 PM PDT THIS EVENING FOR SOUTH
WASHINGTON CASCADES.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 11 AM PDT MONDAY FOR
COASTAL WATERS FROM CAPE SHOALWATER TO FLORENCE OUT 60 NM.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM PDT MONDAY
FOR COASTAL WATERS FROM CAPE SHOALWATER TO FLORENCE OUT 60 NM.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 5 AM
PDT MONDAY.
&&
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
639 AM CDT SUN APR 7 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 342 AM CDT SUN APR 7 2013
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT
ANALYSIS SHOWED UPPER TROUGHING APPROACHING THE PACIFIC
NORTHWEST...WEAK RIDGING OVER THE NORTHERN U.S. ROCKIES INTO THE
DAKOTAS...AND A SHORTWAVE TROUGH OVER EASTERN WISCONSIN. ALSO OF
NOTE ON WATER VAPOR WERE A PAIR OF SHORTWAVES MOVING THROUGH THE
WEAK RIDGING...ONE IN SOUTH CENTRAL WYOMING AND THE OTHER IN
NORTHWEST COLORADO. THE FORECAST AREA LIES IN SUBSIDENCE IN THE
WAKE OF THE EASTERN WISCONSIN SHORTWAVE TROUGH...SEEN AS AN
INVERSION BETWEEN 775 AND 850MB ON THE 00Z MPX SOUNDING. THIS
INVERSION WAS ALSO SATURATED... REFLECTED TOO BY PLENTY OF STRATUS
CLOUDS ON 11-3.9UM IMAGERY FROM THE EASTERN DAKOTAS INTO THE
FORECAST AREA. COOLER AIR HAS BEEN FILTERING IN BEHIND THE
SHORTWAVE AS WELL WITH 850MB TEMPS NOW DOWN TO +2 TO -3C ACROSS
THE FORECAST AREA PER RAP ANALYSIS...COLDEST OVER CENTRAL
WISCONSIN. AT THE SURFACE...HIGH PRESSURE WAS SEEN DROPPING SOUTH
INTO WESTERN MINNESOTA...IN THE WAKE OF LOW PRESSURE OVER NORTHERN
LAKE MICHIGAN AND ITS COLD FRONT WHICH EXTENDS SOUTHWEST TO KANSAS
CITY.
A PATTERN CHANGE IS FORECAST TO OCCUR ALOFT DURING THE NEXT 24 HOURS
AS THE UPPER TROUGH SEEN OFF THE PACIFIC NORTHWEST SHARPLY DIGS
SOUTH INTO CALIFORNIA AND NEVADA. IN RESPONSE...RIDGING WILL BUILD
DOWNSTREAM...ADJUSTING THE UPPER LEVEL FLOW TO SOUTHWESTERLY OVER
THE FORECAST AREA. THIS MEANS THAT THE RECENT LOW LEVEL COLD
ADVECTION WILL COME TO AN END SHORTLY...WITH WARM ADVECTION PROGGED
TO BEGIN BETWEEN 12-18Z TODAY AND CONTINUE THROUGH TONIGHT. IN
ADDITION...MODELS HAVE BEEN CONSISTENT IN SHOWING THE PAIR OF
SHORTWAVES SEEN IN WYOMING AND COLORADO TO AFFECT THE FORECAST AREA
LATE TONIGHT AS THEY RIDE THROUGH THE SOUTHWEST FLOW.
THE FIRST TWO ISSUES FOR THE SHORT TERM PERIOD ARE THE CLOUDS AND
HIGH TEMPERATURES TODAY. THE PRESENT STRATUS DECK DOES HAVE SOME
HOLES IN IT ON ITS SOUTHERN SIDE. THESE HOLES SHOULD EXPAND THROUGH
THE MORNING AS DIURNAL MIXING COMMENCES. 07.00Z NAM LOW LEVEL RH
FIELDS...WHICH GENERALLY TEND PESSIMISTIC...ALSO SUGGEST THAT THE
STRATUS DECK WILL MOSTLY MIX OUT BY 18Z SOUTH OF US HIGHWAY 10.
LATER IN THE AFTERNOON...SAY 21Z AND AFTER...MID AND HIGH CLOUDS
CURRENTLY SPREADING INTO THE PLAINS STATES ARE PROGGED TO MOVE INTO
THE FORECAST AREA. THUS WE SHOULD SEE AT LEAST A FEW HOURS OF MOSTLY
SUNNY SKIES TODAY. WITH 850MB TEMPS CLIMBING TO 0C NORTH AND 6C
SOUTH BY 18Z...ANTICIPATING THAT MOST LOCATIONS MINUS NORTH OF
HIGHWAY 10 WHERE MORE CLOUDS AND SNOW EXIST WILL CLIMB INTO THE 50S.
WARMEST TEMPERATURES...APPROACHING 60...ARE EXPECTED IN THE FAR
SOUTH.
THE NEXT ISSUE FOR THE SHORT TERM PERIOD IS THE POTENTIAL FOR
PRECIPITATION VERY LATE THIS AFTERNOON INTO TONIGHT...DUE TO THE
WARM ADVECTION PATTERN AND THE APPROACH OF THE PAIR OF SHORTWAVES.
THE 07.00Z GFS/06.12Z ECMWF ALREADY SHOW HINTS OF WARM ADVECTION /
ISENTROPICALLY INDUCED PRECIPITATION AFFECTING FAR WESTERN PORTIONS
OF THE FORECAST AREA BETWEEN 21-00Z TODAY. THINKING THIS MIGHT BE A
BIT FAST...WITH THE 07.00Z NAM/REGIONAL CANADIAN/HIRES-ARW AND
07.03Z SREF ALL SLOWER. THUS...PLAN ON KEEPING CONDITIONS DRY TIL
00Z. AS WE HEAD THROUGH TONIGHT...THERE IS A STRONG CONSENSUS
AMONGST ALL MODEL GUIDANCE OF A PRECIPITATION SPLIT. THE NORTHERN
AREA TRACKS FROM NORTHWEST IA/SOUTHERN MN INTO NORTHWEST
WISCONSIN. THE SOUTHERN AREA TRACKS FROM NORTHERN MISSOURI INTO
SOUTHEAST IA AND NORTHWEST IL. THIS SPLIT APPEARS TO BE A RESULT
OF HOW THE PAIR OF SHORTWAVES APPROACHING THE FORECAST AREA LATE
TONIGHT INTERACT WITH THE ISENTROPIC LIFT PATTERN IN PLACE. 850MB
MOISTURE TRANSPORT FIELDS SHOW THE SPLIT INTERACTION WITH THE
ISENTROPIC LIFT PATTERN NICELY. IN ADDITION...THERE ARE OTHER
SUPPORTING FEATURES. FOR EXAMPLE...THE NORTHERN AREA BECOMES
INFLUENECED BY A DEVELOPING AND STRENGTHENING UPPER JET STREAK
OVER UPPER MICHIGAN...PLACING IT IN THE FAVORABLE RIGHT ENTRANCE
REGION. MEANWHILE...THE SOUTHERN AREA HAS A STRONG LOW TO MID-
LEVEL FRONTOGENESIS FEATURE ALONG THE PRESENT COLD FRONT NEAR
I-70...WHICH FOR ALL INTENSIVE PUPROSES TURNS INTO A STATIONARY
BOUNDARY. SO FOR THE FORECAST...THIS WELL AGREED UPON SPLIT
PRECIPITATION SCENARIO POSES A PROBLEM FROM WHAT WE HAD GOING
PREVIOUSLY. HAVE ADJUSTED PRECIPITATION CHANCES AND QPF QUITE A
BIT LOWER SOUTH OF I-90...SINCE THIS AREA WILL BE ON THE SUBSIDENT
SIDE OF THE F-GEN CIRCULATION. NOTE THAT MODELS LIKE THE 07.00Z
GFS/REGIONAL CANADIAN EVEN SUGGEST THAT SOME LOCATIONS ACROSS
NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN COULD END UP DRY.
REGARDING PRECIPITATION TYPE...ALL OF IT SHOULD FALL AS RAIN WITH
WET-BULB ZERO HEIGHTS PROGGED WELL ABOVE 2000 FT. THE PREVIOUS
FORECAST INTRODUCED A CHANCE FOR THUNDER AND THIS STILL LOOKS
REASONABLE AFTER MIDNIGHT...WITH POTENTIAL FOR A FEW HUNDERED J/KG
OF SKINNY CAPE LIFTED FROM 850MB.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 342 AM CDT SUN APR 7 2013
OVERALL MUCH OF THE LONG TERM PERIOD LOOKS ACTIVE...THANKS TO THAT
TROUGH DIGGING INTO CALIFORNIA AND NEVADA TONIGHT. QUITE A FEW
DETAILS TO NOTE.
ON MONDAY...THE PAIR OF SHORTWAVES ARE PROGGED TO SHIFT EAST INTO
MICHIGAN DURING THE AFTERNOON...TAKING THE BULK OF THE SPLIT
PRECIPITATION TONIGHT WITH THEM. HOWEVER...THE STORY DOES NOT END
THERE. THE FOCUS TURNS TO THE FRONTAL BOUNDARY NEAR I-70...WHICH BY
ALL MODELS IS SUGGESTED TO LIFT NORTH INTO CENTRAL AND PERHAPS
NORTHERN IA DURING THE AFTERNOON. THE LIFTING NORTH IS A RESULT OF
THE UPPER TROUGHING DEEPENING AND DIGGING INTO THE FOUR CORNERS
REGION...ENHANCING THE WARM ADVECTION DOWNSTREAM. THE 07.00Z
REGIONAL CANADIAN AND NAM SUGGEST THERE IS POTENTIAL FOR SURFACE
BASED CONVECTION TO FIRE ON THIS FRONT. THE 07.00Z GFS...ON THE
OTHER HAND...HAS A FARTHER SOUTH FRONT AND KEEPS THINGS MORE CAPPED.
HOWEVER...ALL THREE MODELS INCLUDING THE 06.12Z ECMWF DEPICT
POTENTIAL FOR FRONTOGENETICALY INDUCED PRECIPITATION NORTH OF THE
FRONTAL BOUNDARY. THUS...A NEED CONTINUES FOR CHANCES OF SHOWERS
ALONG WITH THE THUNDERSTORM MENTION IN THE EVENT THE REGIONAL
CANADIAN/NAM PAN OUT. IF THE REGIONAL CANADIAN/NAM PAN OUT...
CERTAINLY COULD NOT RULE OUT SOME SEVERE POTENTIAL GIVEN 0-6 KM
SHEAR UPWARS OF 45-50 KT. HOWEVER...IT SEEMS LIKE THE BETTER
INSTABILITY IS WEST OF THE FORECAST AREA...THUS KEEPING THE BULK OF
THE SEVERE POTENTIAL TO THE WEST. SPC DAY 2 SEVERE PROBABILITIES
DEPICT THIS AS WELL. DEFINITELY SOMETHING TO KEEP AN EYE
ON....THOUGH. TEMPERATURE FORECAST IS TRICKY AS IT DEPENDS ON THE
FRONTAL POSITION. A NAM/REGIONAL CANADIAN OR EVEN ECMWF SOLUTION
WOULD ALLOW FOR HIGHS IN THE 60S TO POSSIBLY 70 ALONG/SOUTH OF I-90.
THE GFS IS A LITTLE COOLER BUT STILL HAS HIGHS IN THE 60S SOUTH OF
I-90. RAISED HIGHS 5 DEGREES OR SO TO COME BETTER IN AGREEMENT WITH
ALL 07.00Z GUIDANCE...BUT THEY MAY NEED TO BE RAISED MORE...
ESPECIALLY IF MORE SUN OCCURS IN THE AFTERNOON.
THINGS GET MORE INTERESTING HEADING INTO THE MONDAY NIGHT THROUGH
THURSDAY TIME PERIOD. DURING THIS PERIOD...ALL MODELS HAVE THE DEEP
UPPER TROUGH OVER THE FOUR CORNERS SLOWLY LIFTING TO THE
EAST-NORTHEAST. MEANWHILE...AT THE SAME TIME THERE IS A DEEP UPPER
TROUGH HANGING AROUND THE HUDSON BAY INTO NORTHERN ONTARIO AREA...
HELPING TO HOLD AN UPPER JET STREAK IN PLACE OVER THE NORTHERN GREAT
LAKES. THIS MEANS THE FORECAST AREA IS GOING TO BE PLACED IN THE
FAVORABLE RIGHT ENTRANCE REGION UNTIL THE UPPER TROUGH MOVES IN.
MONDAY NIGHT FOR THE MOST PART LOOKS QUIET...WITH ANY SHOWERS AND
POSSIBLE THUNDERSTORMS IN THE EVENING DISSIPATING WITH LOSS OF
DAYTIME HEATING. THE FRONTAL BOUNDARY...IF IT IS NEARBY...LOOKS TO
SLOWLY DROP SOUTH MONDAY NIGHT FORCED BY THAT DEEP UPPER TROUGH TO
OUR NORTH. IT APPEARS THERE MAY BE A MASS OF LOW LEVEL STRATUS THAT
MOVES IN BEHIND THE FRONT...AND WITH LOW LEVEL FRONTOGENESIS BEHIND
THE FRONT WE COULD DEAL WITH SOME LIGHT RAIN OR DRIZZLE.
PRECIPITATION CHANCES DEFINITELY GO ON THE INCREASE FROM SOUTHWEST
TO NORTHEAST THROUGH THE DAY TUESDAY AND INTO TUESDAY NIGHT...IN
RESPONSE TO ISENTROPIC LIFT STRENGTHENING DOWNSTREAM OF THE UPPER
TROUGH PUSHING TO THE EAST-NORTHEAST. SOME CONCERN FOR SOME HEAVIER
RAIN TUESDAY NIGHT...ESPECIALLY ACROSS THE SOUTH...AS PRECIPITABLE
WATER VALUES INCREASE OVER 1 INCH AND SOME WEAK ELEVATED INSTABILITY
MOVES IN FOR THUNDERSTORMS. RAISED BOTH PRECIPITATION CHANCES AND
QPF FOR TUESDAY AND ESPECIALLY TUESDAY NIGHT GIVEN THE STRONG SIGNAL
AMONGST THE 07.00Z ECMWF/GFS/CANADIAN MODELS. FROM WEDNESDAY INTO
THURSDAY...THE CORE OF THE UPPER TROUGH IS PROGGED TO SLOWLY
APPROACH THE FORECAST AREA. AS THIS OCCURS...THE FORECAST AREA
EVENTUALLY ENDS UP ON THE NORTHWEST / COLD SIDE OF A SURFACE LOW
TRACKING TO OUR SOUTH...PLACING THE AREA INTO THE TROWAL AND COLD
CONVEYOR BELT REGION. GIVEN THE GOOD MODEL AGREEMENT AGAIN...RAISED
PRECIPITATION CHANCES UP DURING THIS PERIOD. IN ADDITION...WILL HAVE
TO WATCH FOR SOME SNOW ACCUMULATIONS COME WEDNESDAY NIGHT AND
THURSDAY AS 850MB TEMPS DROP TO -4 TO -8C BY 12Z THURSDAY.
IT SHOULD BE NOTED THAT THE 07.00Z NAM IS AN OUTLIER SOLUTION TO THE
ABOVE SCENARIO...PARTICULARLY FOR TUESDAY THROUGH WEDNESDAY...SINCE
IT EJECTS THE CORE OF THE SOUTHWESTERN TROUGH MUCH QUICKER AND LIFTS
IT FARTHER NORTH. THE NAM WAS DISCOUNTED GIVEN GOOD MODEL AGREEMENT
BETWEEN ALL OTHER MODELS. THE 07.03Z SREF LOOKS LIKE A COMPROMISE
BETWEEN THE NAM AND GFS...BUT THE SREF IS NAM-BIASED DUE TO AN
OVERWHELMING AMOUNT OF NAM MEMBERS. THUS...THE SREF WAS DISCOUNTED
AS WELL.
LOOKING FARTHER AHEAD...GOOD MODEL AGREEMENT EXISTS AMONGST THE
07.00Z ECMWF/GFS/CANADIAN ON BRINGING COLD CANADIAN HIGH PRESSURE
INTO THE AREA THURSDAY NIGHT THROUGH FRIDAY NIGHT. THIS SHOULD HELP
DRY THINGS OUT. LEFT A CONSENUS 20 PERCENT CHANCE OF PRECIPITATION
IN THURSDAY NIGHT...BUT THIS PERIOD MAY EVENTUALLY END UP DRY. WILL
NEED TO WATCH SOME OF THE LOW TEMPERATURES TOO FOR BOTH THURSDAY
NIGHT AND FRIDAY NIGHT...DEPENDING ON HOW MUCH FRESH SNOW WE PICK UP
AND FOR FRIDAY NIGHT HOW MUCH IS STILL ON THE GROUND. A WARM
ADVECTION PATTERN SETS UP FOR SATURDAY AHEAD OF NEW TROUGHING
DROPPING INTO THE NORTHERN ROCKIES. FOLLOWED THE CONSENSUS HERE OF
BRINGING SOME 20-30 PERCENT CHANCES OF PRECIPITATION ACROSS THE AREA
ON SATURDAY. NEED TO MAINTAIN A RAIN/SNOW MIX BECAUSE 850MB TEMPS
ARE STILL SLOW TO WARM...ESPECIALLY IN THE ECMWF WHERE IT KEEPS THEM
BELOW 0C THROUGH 00Z SUNDAY.
&&
.AVIATION...TODAY AND TONIGHT
638 AM CDT SUN APR 7 2013
BUFKIT SOUNDINGS SUGGEST THAT THE MVRF CLOUDS WILL LINGER THROUGH
THIS MORNING...AND THEN QUICKLY DISSIPATE BETWEEN 07.18Z AND
07.21Z. A 5 TO 10K CLOUD DECK WILL MOVE BACK INTO THE AREA BETWEEN
07.23Z AND 08.03Z AND THEN PERSIST THROUGH THE REMAINDER OF THE
NIGHT AS A LOW PRESSURE SYSTEM PASSES TO THE NORTHWEST OF THE TAF
SITES. SCATTERED SHOWERS WILL MOVE INTO THE AREA AFTER
08.06Z...BUT SHOULD NOT AFFECT THE VISIBILITIES TOO MUCH.
&&
.HYDROLOGY...
ISSUED AT 342 AM CDT SUN APR 7 2013
RIVER STATUS...
THE TREMPEALEAU RIVER NEAR DODGE WILL REMAIN ABOVE FLOOD STAGE AND
ALLOW FOR MINOR FLOODING TO CONTINUE THROUGH MONDAY MORNING.
MEANWHILE ON THE BLACK...ANOTHER BRIEF ICE JAM LOOKS LIKE IT MAY
HAVE FORMED AROUND NEILLSVILLE...WITH A SPIKE UP OF 4 FEET BUT STILL
WELL WITHIN THE RIVER BANK. DOWNSTREAM...SO FAR THE BLACK REMAINS
WITHIN THE RIVER BANK.
SNOW PACK...
RECENT COOPERATIVE OBSERVER REPORTS SHOW SNOW PACK IS MAINLY ALONG
AND NORTHEAST OF THE INTERSTATE 94 CORRIDOR WITH 2 TO 7 INCHES OF
SNOW DEPTH IN PLACES. THE DEEPEST SNOW PACK IS OVER THE NORTHERN
MOST PARTS OF TAYLOR WHERE AROUND A FOOT OF SNOW REMAINS ON THE
GROUND. SNOW WATER EQUIVALENT OF 1 TO 2 INCHES IS MAINLY NORTH OF
THE INTERSTATE 94 CORRIDOR WITH THE GREATEST SNOW WATER EQUIVALENT
OF 2 TO 4 INCHES IN NORTHERN TAYLOR COUNTY.
RAINFALL...
LESS RAINFALL IS ANTICIPATED TONIGHT INTO MONDAY THAN PREVIOUSLY
EXPECTED...WITH UPWARDS OF 1/4 TO 1/2 INCH NORTH OF I-90 AND LESS
THAN A 1/4 INCH TO THE SOUTH. WILL STILL NEED TO WATCH TUESDAY
THROUGH WEDNESDAY...THOUGH. BY WEDNESDAY MORNING...CURRENTLY
ANTICIPATING AMOUNTS BETWEEN 3/4 INCH AND 1.25 INCHES SOUTH OF
HIGHWAY 10 TO LESS THAN A 1/2 INCH TO THE NORTH. IF THE SYSTEM
BRINGING THIS RAIN SHIFTS FARTHER NORTH...THE HEAVY RAIN AREA WILL
SHIFT NORTH AS WELL...PLACING IT WHERE RAIN IS NOT NEEDED.
TEMPERATURES...
HIGHS TODAY ARE GOING TO BE COOLER...IN THE THE MIDDLE 40S/AROUND 50
NORTH OF I-94 AND IN THE 50S SOUTH OF THERE. WARMER CONDITIONS LOOK
ON TAP FOR MONDAY...WITH MOSTLY 50S NORTH OF I-94 AND 60S SOUTH.
TEMPERATURES THEN COOL INTO THE 40S FOR TUESDAY AND WEDNESDAY AND
POSSIBLY STRUGGLE TO GET TO 40 BY THURSDAY. THE TEMPERATURE MAY NOT
MATTER IN A FEW DAYS AS MOST OF THE SNOW PACK MAY BE GONE...UNTIL
POTENTIALL A SMALL SNOW PACK RE-ESTABLISHES ITSELF THURSDAY MORNING.
FROST DEPTH...
AS OF APRIL 4TH...FROST DEPTHS //WHICH ARE OBSERVED EVERY MONDAY AND
THURSDAY//ACROSS THE AREA REMAIN DEEP...AVERAGING AROUND 1 FOOT TO 1
1/2 FEET SOUTH OF I-90...AND UP TO 3 FEET ACROSS PORTIONS OF NORTH
CENTRAL WISCONSIN. THIS FROST WILL ACT TO ENHANCE RUNOFF OF SNOW
MELT AND PRECIPITATION INTO STREAMS AND RIVERS.
SUMMARY...
MAIN CONCERN FOR FLOODING REMAINS ALONG THE TREMPEALEAU AND BLACK
RIVERS AS SNOW MELT CONTINUES...ALONG WITH THE PERIODS OF RAINFALL
TONIGHT INTO MONDAY AS WELL AS TUESDAY THROUGH WEDNESDAY. HAVE A
HYDROLOGIC OUTLOOK PRODUCT OUT TO HEIGHTEN THIS AWARENESS. ALTHOUGH
THE TUESDAY INTO WEDNESDAY MODERATE TO HEAVY RAIN IS FORECAST MAINLY
SOUTH OF I-90...CURRENTLY THINKING THAT THE RIVERS SHOULD BE ABLE TO
ABSORB IT. A QUICK MODEL OF THE TURKEY RIVER AT GARBER USING THE
FORECAST QPF WOULD BRING THE RIVER ABOVE ACTION STAGE BUT NOT TO
FLOOD. THUS...DID NOT EXPAND THE HYDROLOGIC OUTLOOK SOUTH.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...BOYNE
HYDROLOGY...AJ
AREA FORECAST DISCUSSION
NWS ALBANY NY
423 PM EDT SUN APR 7 2013
.SYNOPSIS...
LOW PRESSURE WILL CONTINUE TO TRACK NORTHEAST ACROSS THE SAINT
LAWRENCE VALLEY TONIGHT. A BAND OF SHOWERS WILL TRACK ACROSS THE
REGION INTO THIS EARLY EVENING...THEN THE WINDS AND THE SHOWERS
WILL DIMINISH. A DRY START TO THE WORK WEEK BEFORE ANOTHER LOW
PRESSURE SYSTEM APPROACHES MONDAY NIGHT WITH ANOTHER CHANCE FOR
SHOWERS. RATHER UNSETTLED CONDITIONS ARE EXPECTED FOR THE
REMAINDER OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
H2O VAPOR LOOP SHOWS A RATHER STRONG UPPER LOW TRACKING NORTHEAST
ACROSS THE ST LAWRENCE VALLEY WITH AN IMPRESSIVE SURFACE PRESSURE
GRADIENT IN PLACE ACROSS EASTERN NY. THE VWP FROM THE WSR88D SHOWS
WINDS WITHIN THE BOUNDARY LAYER ARE AROUND 40KTS. WITH FUNNELING
UP THE HUDSON VALLEY...WIND SPEEDS HAVE INCREASED WITH SEVERAL
REPORTING STATIONS GUSTING INTO THE LOW-MID 40MPH RANGE. THE
ADDITIONAL INSOLATION WE RECEIVED ALSO ASSISTED WITH MOMENTUM
TRANSFER TODAY ALONG WITH TEMPERATURES CLIMBING A COUPLE DEGREES
OF FORECAST. A BAND OF SHOWERS ALONG THE COLD FRONT HAS DEVELOPED
AND WE EVEN HAD A FEW LIGHTNING STRIKES PER THE NLDN ACROSS THE
ADIRONDACKS. WHILE THE LIGHTNING HAS DIMINISHED...THE BAND OF
SHOWERS HAS INCREASED IN COVERAGE AND FORWARD MOMENTUM THE PAST
COUPLE OF HOURS. THE LATEST HRRR REFLECTIVITY FORECASTS SUGGEST
THIS LEADING EDGE OF PRECIP WILL DIMINISH WITH ANOTHER RENEW AREA
OF SHOWERS ACROSS LAKE ONTARIO AND WESTERN NY EXPECTED TOWARD THIS
EARLY EVENING AND QUICKLY MOVE ACROSS MAINLY EASTERN NY. WE WILL
KEEP POPS INTO CHC-SCT CATEGORY THROUGH THE REMAINDER OF TODAY AND
INTO THE EVENING. COLD ADVECTION WILL COMMENCE IN THE WAKE OF
FROPA AS H850 TEMPS SETTLE BACK INTO THE LOWER SINGLE DIGITS.
WESTERLY WINDS SHOULD KEEP SOME UPSLOPE CLOUDS...ESPECIALLY ACROSS
THE WESTERN NEW ENGLAND COUNTIES. AS FOR WINDS...COULD SEE SOME
SLIGHT ENHANCEMENT THRU THE MOHAWK RIVER LATER THIS EVENING...BUT
EXPECTATIONS ARE FOR THE SURFACE RIDGE TO BUILD IN AND RELAX THE
GRADIENT AND THOSE WINDS.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/...
MONDAY...INCREASING CONFIDENCE THAT THE RIDGE BOTH ALOFT AND THE
SURFACE WILL CREST OVER THE REGION FOR A NICE START TO THE WORK
WEEK. H850 TEMPS CLIMB A COUPLE OF DEGREES THROUGH THE DAY AND
COINCIDING WITH MIXING LAYER HEIGHTS BETWEEN H850-H900...WE SHOULD
BE ABLE TO OBTAIN AFTERNOON HIGHS L-M60S FOR VALLEY LOCATIONS AND
50S ELSEWHERE.
MONDAY NIGHT...INCREASING LOW LEVEL JET ACROSS THE LOWER AND MID
MISSISSIPPI RIVER VALLEY ALONG WITH A TIGHTENING BAROCLINIC ZONE
WILL LIKELY RESULT IN AN ORGANIZED CONVECTIVE EPISODE THAT WILL
TRACK TOWARD THE UPPER OHIO VALLEY AND LOWER GREAT LAKES REGION
MONDAY NIGHT. TRENDS FROM THE NCEP MODEL SUITE AND INTERNATIONAL
GUIDANCE ALL SUGGEST THIS SYSTEM TO TRACK ACROSS THE REGION DURING
THE EVENING AND EARLY OVERNIGHT PERIOD. AS PREVIOUS MENTIONED IN
THE EARLIER AFD/S...MID LEVEL INSTABILITY PER THE SHOWALTERS DROP
TO OR BELOW 0C TO CONTINUE TO THE MENTION OF THUNDER IN THE
FORECAST. AT THIS TIME...SEEMS THE RAINFALL AMOUNTS OF ONE QUARTER
TO ONE HALF OF AN INCH ARE TO BE EXPECTED /SEE HYDRO SECTION
BELOW/.
TUESDAY...THE STRENGTH OF THIS CONVECTIVE SYSTEM MAY JUST BE
ENOUGH TO ALLOW FOR INCREASED SUBSIDENCE FOR A RATHER NICE DAY IN
THE WAKE OF THE RAINFALL. WE WILL DECREASE POPS AND INCREASE THE
POTENTIAL FOR PARTIAL SUNSHINE. SINCE WE SHOULD BE RATHER MILD
START TO THE DAY...WE COULD SEE OUR FIRST REAL RUN AT 70F FOR THE
CAPITAL REGION WITH HIGHER CONFIDENCE OF 70S INTO THE MID HUDSON
VALLEY AND PORTIONS OF LITCHFIELD COUNTY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
MODEL CONSENSUS IS BETTER DURING THIS TIME FRAME COMPARED TO
EARLIER RUNS. ALL INDICATE AN UNSETTLED PATTERN DURING MUCH OF
THIS TIME FRAME AS A STRONG FRONTAL STALLS NEAR THE AREA.
THE 12Z OPERATIONAL GFS CONTINUES TO HAVE THIS FRONT STALLING THE
FURTHEST NORTH...CLOSE TO JUST NORTH OF INTERSTATE 90. THE 12Z
CANADIAN MODEL STALLED THE FRONT A LITTLE FURTHER SOUTH. THE 1Z
EUROPEAN WAS STILL THE FURTHEST SOUTH...STALLING THE FRONT CLOSER TO
THE MASON DIXON LINE.
WE HAVE LEANED WITH THE EUROPEAN SOLUTION WHICH HAPPENED TO THE
WEATHER PREDICTION CENTER (WPC) SOLUTION AS WELL.
TUESDAY NIGHT MOST MODELS FORECAST SOME SORT OF MESO-SCALE COMPLEX
(MCS) WORKING THROUGH THE AREA. THE 12Z GFS AND 12Z EUROPEAN
FORECAST MODELS INDICATE THIS WOULD TRACK FROM I-90 SOUTH...WHILE
THE CANADIAN MODEL INDICATED IT WOULD TRAVEL FURTHER NORTH. FOR
NOW...JUST WENT WITH 40 POPS OF SHOWERS EVERYWHERE ACROSS THE
REGION. OVERNIGHT LOWS WILL BE IN THE MID TO UPPER 30S NORTH...40S
MOST OTHER PLACES.
WEDNESDAY LOOKS AS IF IT MIGHT BE THE "DRIEST" OF THE PERIOD IN THAT
WE SHOULD BETWEEN AN EXISTING MCS AND PERHAPS ANOTHER LINE OF
SHOWERS APPROACHING AHEAD OF A COLD FRONT. DUE TO LACK OF CONFIDENCE
IN TIMING...WE CANNOT RULE OUT A STRAY SHOWER OR TWO...BUT MUCH OF
THE DAY COULD BE RAINFREE AND MILD WITH TEMPERATURES MAINLY IN THE
60S...EXCEPT 50S ACROSS THE ADIRONDACK PARK AND SOUTHERN GREENS. A
THUNDERSTORM CANNOT BE COMPLETELY RULED OUT (MENTIONED SLIGHT CHANCE
OF THUNDERSTORMS).
WEDNESDAY NIGHT...THE AFOREMENTIONED COLD FRONT LOOKS TO MOVE
THROUGH BRINGING AT LEAST SOME SCATTERED SHOWERS. TEMPERATURES LOOK
TO REMAIN MILD MAINLY IN THE 50S SOUTH...40S NORTH.
THEN FRONT LOOKS TO STALL...AGAIN PROBABLY SOUTH OF OUR
REGION...SOMETIME THURSDAY THROUGH FRIDAY. WAVES OF LOW PRESSURE
WILL LIKELY RIPPLE ALONG THIS FRONT...IMPOSSIBLE TO CORRECTLY TIME
THIS FAR OUT. WE MIGHT SQUEAK OUT ANOTHER MILD DAY THURSDAY WITH
HIGHS IN THE 60S FROM THE CAPITAL DISTRICT SOUTH...50S FURTHER
NORTH.
TEMPERATURES THEN COOL DOWN TO THE 40S THURSDAY NIGHT (30S NORTH).
IT WILL TURN COOLER FRIDAY WITH HIGHS ONLY 50-55 ALBANY SOUTH...40S
AND EVEN SOME UPPER 30S FURTHER TO THE NORTH.
IT DOES APPEAR A MORE SIGNIFICANT AREA OF LOW PRESSURE WILL RIDE THE
FRONT ON FRIDAY...BRINGING THE BEST CHANCE OF A SOAKING RAIN. THE
12Z EUROPEAN FORECAST MODEL STILL INSIST IT COULD BE COULD ENOUGH
FOR SOME MIXED PRECIPITATION TO FALL LATE FRIDAY INTO FRIDAY NIGHT
FROM THE CAPITAL DISTRICT NORTHWARD AS SHALLOW COLD AIR WEDGES IN
FROM THE NORTH THANKS TO A STRONG AGEOSTROPHIC NORTHERLY FLOW. H925
TEMPERATURES ON THAT MODEL DROP TO BELOW 0Z (FREEZING) WHILE H850
ARE INITIALLY WELL ABOVE 0C...BUT EVENTUALLY FALL BELOW FREEZING
LATER FRIDAY NIGHT.
FOR NOW...WE HAVE MAINLY RAIN IN THE GRIDS...BUT DO MENTION A
POSSIBLE CHANGEOVER TO SNOW MOST PLACES FRIDAY NIGHT. BEING THIS
EVENT IS STILL NEARLY A WEEK WAY...WE WILL HAVE PLENTY OF TIME TO
MONITOR THE LATEST TRENDS.
THE WHOLE DISTURBANCE SHOULD LIFT OUT TO OUR NORTHEAST SATURDAY. IN
ITS WAKE...A CHILLY BREEZY DAY AWAITS US SATURDAY...WITH SOME
MODERATION BY SUNDAY.
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
VFR CONDITIONS AND GUSTY WINDS WILL PREVAIL THROUGH THE REMAINDER OF
THE AFTERNOON. A WARM FRONT WILL APPROACH THE AREA FROM THE
SOUTH...LOWERING CEILINGS CLOSE TO MVFR LEVELS...BEFORE HIGH
PRESSURE BUILDS ACROSS THE REGION FOR MONDAY.
THIS AFTERNOON...GUSTY SOUTHERLY WINDS WILL CONTINUE THROUGH THE
REMAINDER OF THE AFTERNOON AS TERRAIN CHANNELING AND DEEP BOUNDARY
LAYER MIXING CONTINUE WITH NOW INCREASED DAYTIME HEATING DUE TO
CLEARING AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM PER THE LATEST
VISIBLE SATELLITE IMAGERY. CLOUD COVER WILL GRADUALLY FILL IN LATE
IN THE AFTERNOON WITH SCATTERED SHOWERS DEVELOPING AS WELL. HOWEVER
CONFIDENCE REMAINS LOW REGARDING THE AREAL COVERAGE OF THESE
SHOWERS...SO HAVE MENTIONED JUST VCSH IN THE TAFS.
TONIGHT INTO MONDAY...AS A LOW PRESSURE SYSTEM AND ITS ASSOCIATED
BOUNDARIES MOVE ACROSS THE REGION TONIGHT...CLOUD COVER WILL
CONTINUE TO INCREASE WITH LOWERED CEILINGS. MVFR CEILINGS WILL BE
POSSIBLE AT KPSF TOWARDS DAYBREAK...BUT SHOULD REMAIN AT VFR LEVELS
AT KGFL/KALB/KPOU. HIGH PRESSURE WILL BUILD IN ACROSS THE REGION FOR
MONDAY...ALLOWING SKIES TO CLEAR BY MONDAY AFTERNOON.
WINDS WILL DIMINISH THROUGH THE OVERNIGHT AND SHIFT WESTERLY TO
GENERALLY 5-10 KNOTS.
OUTLOOK...
MON NIGHT-THU....VFR/MVFR CHC SHOWERS.
&&
.FIRE WEATHER...
THE COLD FRONT WILL MOVE THROUGH TONIGHT WITH THE SHOWERS
ENDING...AND THE RH VALUES INCREASING TO 75 TO 95 PERCENT WITH THE
WINDS SHIFTING TO THE WEST NORTHWEST AT 5 TO 15 MPH...WITH A FEW
HIGHER GUSTS INTO THE MOHAWK VALLEY...CAPITAL REGION AND
BERKSHIRES THIS EVENING.
HIGH PRESSURE WILL BRING DRY WEATHER ON MONDAY WITH MUCH LIGHTER
WINDS. THE RH VALUES WILL DROP TO 30 TO 45 PERCENT BY THE MID TO
LATE AFTERNOON.
&&
.HYDROLOGY...
NO WIDESPREAD HYDROLOGY PROBLEMS ARE EXPECTED AT THIS TIME...HOWEVER
THERE IS MUCH UNCERTAINTY IN THE FORECAST AS WE HEAD THROUGH THE
WEEK WITH REGARDS TO PRECIPITATION AND THE AMOUNTS OF SNOWMELT THAT
WILL OCCUR. THE WEATHER WILL BE UNSETTLED MUCH OF THE WEEK.
A CONVECTIVE COMPLEX IS EXPECTED TO IMPACT THE REGION MONDAY
NIGHT. AT THIS TIME...RAINFALL AMOUNTS OF ONE QUARTER TO ONE HALF
AN INCH ARE EXPECTED. COMBINE THAT WITH MILD TEMPERATURES SHOULD
RESULT WITH AN INCREASE WATER FLOWS INTO AREA RIVERS AND STREAMS.
AT THIS TIME...EXPECTATIONS ARE FOR WITHIN BANK WATER RISES.
TEMPERATURES ARE EXPECTED TO WARM TO ABOVE NORMAL ESPECIALLY ON
TUESDAY WITH A RETURN TO MORE SEASONABLE READINGS LATER IN THE
WEEK. THE DEPARTURES FROM NORMAL ARE NOT EXPECTED TO BE AS
PRONOUNCED ACROSS THE HIGHER TERRAIN WHERE THE SNOWPACK IS...PLUS
TEMPERATURES AT NIGHT ARE EXPECTED TO COOL DOWN ENOUGH TO SLOW THE
SNOWMELT.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...RED FLAG WARNING UNTIL 8 PM EDT THIS EVENING FOR CTZ001-013.
NY...RED FLAG WARNING UNTIL 8 PM EDT THIS EVENING FOR NYZ038>041-
043-048>050-052>054-059>061-064>066-083-084.
WIND ADVISORY UNTIL 6 PM EDT THIS EVENING FOR NYZ041>043-049-
050-052-053-059-060-083-084.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...BGM
NEAR TERM...BGM
SHORT TERM...BGM
LONG TERM...HWJIV
AVIATION...IRL
FIRE WEATHER...BGM
HYDROLOGY...BGM
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
305 PM EDT SUN APR 7 2013
.SYNOPSIS...
19Z WATER VAPOR AND H4 RAP ANALYSIS SHOW AN UNAMPLIFIED UPPER LEVEL
PATTERN IN PLACE OVER THE CONUS OUTSIDE OF A FEW MINOR SHORTWAVE
"KINKS" IN THE FLOW. ZONAL FLOW IS IN PLACE OVER THE NORTHERN GULF
COAST AND FLORIDA PENINSULA AND WILL HOLD FOR AT LEAST THE NEXT 24
HOURS. ONE VERY MINOR IMPULSE WITHIN THE ZONAL FLOW IS LOCATED OVER
THE EASTERN GULF AND WILL PASS OVER THIS EVENING/TONIGHT WITH LITTLE
TO NO INFLUENCE ON OUR WEATHER.
AT THE SURFACE...HIGH PRESSURE EXTENDS DOWN THE EASTERN SEABOARD AND
CONTINUES TO RIDGE ALL THE WAY TO THE FL PENINSULA AND
CENTRAL/EASTERN GULF. GRADIENT AROUND THIS RIDGE IS PROVIDING A
GENERAL EASTERLY WIND PATTERN. SIMILAR TO SATURDAY...STILL HAVE A
RATHER MOIST LAYER SEEN ON TIME HEIGHT/CROSS SECTION ANALYSIS
BETWEEN AROUND 950-825MB. THE 12Z KTBW SOUNDING PROFILE CONFIRMS
THIS NWP FORECAST. WITH THE MOISTURE IN PLACE...DIURNAL HEATING
CONTINUES TO MIX UP INTO THE COLUMN RESULTING IN A SHALLOW SCT-BKN
CU FIELD EXPANDING ACROSS THE PENINSULA FROM EAST TO WEST. THIS CU
FIELD WILL DISSIPATE THIS EVENING WITH THE LOSS OF DAYTIME HEATING.
&&
.SHORT TERM (TONIGHT THROUGH TUESDAY NIGHT)...
TONIGHT...
QUIET AND SEASONABLE OVERNIGHT PERIOD ON TAP. MOSTLY CLEAR SKIES
EXPECTED WITH TEMPERATURES DROPPING TO THE MIDDLE AND UPPER 50S FOR
MANY INLAND LOCATIONS BY SUNRISE...AND HOLDING IN THE 60S AT THE
COAST FROM PINELLAS COUNTY SOUTHWARD ALONG THE SUN COAST.
MONDAY/MONDAY NIGHT...
ZONAL FLOW PATTERN ALOFT WILL SLOWLY BEGIN TO TRANSITION TOWARD
RIDGING THROUGH THE DAY...AND COMPLETE THE TRANSITION MONDAY NIGHT.
AT THE SURFACE...AN EAST TO SOUTHEAST FLOW PATTERN WILL HOLD IN
PLACE ON THE SOUTHERN SIDE OF A RIDGE AXIS OFF THE GA/SC COAST.
EFFICIENT DIURNAL MIXING AND 800-850MB TEMPS AROUND 12C SHOULD
EASILY ALLOW AFTERNOON TEMPS TO MIX OUT TO THE LOWER AND MIDDLE 80S
AWAY FROM THE BEACHES. SIMILAR TO TODAY...THE STRONG TERRESTRIAL
HEATING AND WEAKER AFTERNOON GRADIENT WILL ALLOW AN ONSHORE WIND
COMPONENT TO DEVELOP AT THE COAST AND HOLD TEMPS DOWN IN THE 70S
OFF THE SHELF WATERS. MOSTLY SUNNY SKIES TO START THE DAY WILL FILL
IN WITH A SCT-BKN CU FIELD FOR A GENERALLY PARTLY CLOUDY AFTERNOON
FORECAST. A SLOW INFLUX IN LOW LEVEL MOISTURE WILL CONTINUE THE RISE
IN OVERNIGHT LOWS. MANY SPOTS BY MONDAY NIGHT OUTSIDE OF THE NATURE
COAST WILL STRUGGLE TO FALL BELOW 60 BY SUNRISE. NORMALLY COLDER
NATURE COAST LOCATIONS SHOULD FALL NO LOWER THAN THE MID 50S.
TUESDAY/TUESDAY NIGHT...
A WARM APRIL DAY SEEMS ON TAP UNDER A MIX OF SUN AND CLOUDS. LOW
LEVEL COLUMN CONTINUES TO MODIFY UNDER STACKED RIDGING. AFTERNOON
HIGH TEMPERATURES AWAY FROM THE BEACHES SHOULD RISE WELL INTO THE
80S FOR MOST LOCATIONS...AND WOULD NOT BE SURPRISED TO SEE A FEW 90
DEGREE READINGS BY LATE IN THE DAY. A SLIGHTLY BETTER MOISTURE
PROFILE OVER THE SOUTHERN THIRD OF THE FORECAST AREA MAY BE JUST
ENOUGH TO SUPPORT AN ISOLATED AFTERNOON SHOWER OR 2 ALONG THE
SEA-BREEZE. HOWEVER...USUALLY THIS TIME OF YEAR...YOU NEED SOME
SYNOPTIC HELP TO GET ANY SEA-BREEZE INDUCED CONVECTION TO FIRE. THE
UPPER RIDGE OVERHEAD WILL CERTAINLY NOT PROVIDE THIS SUPPORT...AND
FOR NOW WILL KEEP POPS AT SILENT 10% DOWN TOWARD CHARLOTTE AND LEE
COUNTIES. TUESDAY NIGHT LOOKS WARM WITH OVERNIGHT LOW TEMPS HOLDING
AROUND 60S FAR NORTH AND IN THE LOWER/MIDDLE 60S SOUTH. ENJOY!
&&
.LONG TERM (WEDNESDAY-SUNDAY)...
MEDIUM RANGE GUIDANCE IS IN SLIGHTLY BETTER AGREEMENT COMPARED TO
PREVIOUS MODEL CYCLES...HOWEVER SOLUTIONS CONTINUE TO DIVERGE LATE
NEXT WEEK AND INTO THE UPCOMING WEEKEND WITH RESPECT TO THE
PROGRESSIVENESS OF A COLD FRONT THROUGH THE AREA. WILL CONTINUE TO
TAKE A BLENDED FORECAST APPROACH FOR NOW UNTIL THE MODEL SOLUTIONS
COME INTO BETTER AGREEMENT. AS A RESULT...WILL NEED TO KEEP SLIGHT
CHANCE OR LOW CHANCE POPS IN THE FORECAST EACH DAY THROUGH THE LONG
TERM PERIOD...FOR PRIMARILY AFTERNOON/EVENING SHOWERS AND
THUNDERSTORMS. TEMPERATURES ARE EXPECTED TO RUN ABOVE NORMAL THROUGH
FRIDAY BEFORE SETTLING BACK CLOSER TO SEASONAL LEVELS OVER THE
UPCOMING WEEKEND.
&&
.AVIATION...
VFR CONDITIONS WITH FEW-SCT CU/SC AND SOME CIRRUS. GENERALLY
EASTERLY WINDS WITH A LATE SEA BREEZE CLOSE TO THE COAST.
&&
.MARINE...
THE EASTERN GULF OF MEXICO WILL REMAIN ON THE SOUTHERN SIDE OF A
RIDGE AXIS EXTENDING OFF THE GA/SC COAST THROUGH THE NEXT SEVERAL
DAYS. RESULTING GRADIENT WILL PROVIDE A GENERAL EASTERLY FLOW TO THE
REGION...HOWEVER MARINERS SHOULD ANTICIPATE WINDS BECOMING LOCALLY
ONSHORE THE NEXT COUPLE OF AFTERNOON NEAR THE COAST WITH THE
DEVELOPMENT OF THE SEA-BREEZE. THE NEXT FRONT WILL NOT APPROACH THE
REGION UNTIL THE LATTER PORTION OF THE WEEK WITH SOUTHEAST AND SOUTH
WINDS INCREASING AHEAD OF THIS SYSTEM.
&&
.FIRE WEATHER...
RISING TEMPERATURES THE NEXT SEVERAL DAYS WILL ALSO BE ACCOMPANIED
BY A SLOW INCREASE IN LOW LEVEL MOISTURE. RELATIVE HUMIDITY VALUES
WILL BOTTOM OUT IN THE UPPER 30S TO AROUND 40 PERCENT THE NEXT
SEVERAL DAYS DURING THE AFTERNOON...AND NO RED FLAG CONDITIONS ARE
ANTICIPATED. PATCHY FOG WILL BE INTRODUCED TO THE FORECAST FOR LATE
MONDAY NIGHT AND EARLY TUESDAY MORNING.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 63 82 65 85 / 0 0 0 10
FMY 63 86 65 85 / 0 0 0 10
GIF 59 86 61 87 / 0 0 0 10
SRQ 62 79 62 83 / 0 0 0 10
BKV 54 85 57 86 / 0 0 0 0
SPG 64 82 66 82 / 0 0 0 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
AVIATION...RUDE
LONG TERM...JELSEMA
AREA FORECAST DISCUSSION
NWS MIAMI FL
219 PM EDT SUN APR 7 2013
.SHORT TERM (TONIGHT THROUGH TUESDAY NIGHT)...
PLACED AN ISOLATED POP GRID FOR ALL ZONES THE REMAINDER OF THIS
AFTERNOON. THE ONSHORE FLOW OF A FEW SHOWERS ALONG THE EAST COAST
HAS BEEN PERSISTENT AND THE HRRR DOES INDICATE A CONTINUATION OF
ISOLATED ACTIVITY DEVELOPING ACROSS THE INTERIOR AND COASTAL
COLLIER COUNTY UNTIL VERY EARLY THIS EVENING.
GLOBAL MODELS IN VERY GOOD AGREEMENT OVER THE NEXT 48-60 HOURS
WITH MID LEVEL ZONAL FLOW THROUGH EARLY TUESDAY AND SURFACE HIGH
PRESSURE ACROSS THE ATLANTIC AND NORTH FLORIDA. THIS WILL MAINTAIN
A MODEST EASTERLY LOW LEVEL WIND FLOW AND A MOSTLY DRY WEATHER
REGIME WITH STRONG SUBSIDENCE CAP REMAINING INTACT. THERE IS A
SMALL INCREASE IN PWAT VALUES THAT WILL BE ROTATING WESTWARD
BENEATH THE LARGE SCALE LOW LEVEL RIDGE OVER THE ATLANTIC THAT THE
MODELS SHOW ARRIVING ACROSS SOUTH FLORIDA BY LATE TUESDAY AND
TUESDAY NIGHT. FORECAST SOUNDINGS ALSO INDICATE THE CAP WILL BEGIN
TO ERODE BY THIS TIME AND THIS SHOULD ALLOW FOR A SLIGHT INCREASE
IN SHOWER ACTIVITY MOVING FROM THE ATLANTIC ONTO THE SOUTHEAST
COAST. FOR THIS REASON, WILL MAINTAIN A SLIGHT CHANCE POP ALONG
THE EAST COAST TUESDAY NIGHT AND SILENT POP ELSEWHERE AS RAIN
CHANCES OVER THE INTERIOR AND COASTAL COLLIER COUNTY WILL BE TOO
SMALL TO MENTION IN THOSE LOCATIONS. IN ADDITION, THE SHORT RANGE
ENSEMBLE (SREF) IS SHOWING A SUBSTANTIAL INCREASED CHANCE FOR FOG
OVER THE INTERIOR AND SOUTHWEST COAST FOR MONDAY NIGHT AND TUESDAY
NIGHT AS THE LOW LEVEL MOISTURE INCREASES SO WILL INTRODUCE PATCHY
FOG FOR THOSE LOCATIONS AT THAT TIME.
.LONG TERM (WEDNESDAY THROUGH SUNDAY)...
LOOKING AHEAD TOWARDS THE MIDDLE AND END OF THE WEEK, THE FORECAST
BECOMES INCREASINGLY UNCERTAIN AS THE GFS AND ECMWF CONTINUE TO
DIVERGE ON THE EVOLUTION OF THE POWERFUL MID LEVEL TROUGH THAT WILL
BE MOVING INTO THE CENTRAL PLAINS STATES MONDAY NIGHT AND TUESDAY
THEN SHIFTING EAST THROUGH THE WEEK. THE GFS PHASES IT IN WITH A
NORTHERN STREAM TROUGH BY LATE WEDNESDAY AND THURSDAY AS THE MAIN
SYSTEM LIFTS EAST INTO THE ATLANTIC. THIS BRINGS A TRAILING COLD
FRONT ACROSS SOUTH FLORIDA ON FRIDAY SLOWLY PUSHING THROUGH THE
REGION AND OFF THE SOUTHEAST COAST LATE SATURDAY AND SUNDAY. THIS
WOULD ALSO BRING AN INCREASED CHANCE FOR CONVECTION ON FRIDAY AND
POSSIBLY LINGERING INTO SATURDAY AS SHOWN BY THE LATEST MEX
GUIDANCE. HOWEVER, THE ECMWF IS ALSO HOLDING ONTO ITS SLOWER
SOLUTION WITH THE CENTRAL PLAINS TROUGH PHASING WITH THE UPSTREAM
SYSTEM BUT FARTHER TO THE NORTH. IT THEN SHOWS THE FRONT STALLING
ACROSS CENTRAL FLORIDA SATURDAY AND SUNDAY SO THE HIGHEST POPS WOULD
BE OVER NEXT WEEKEND. AT THIS TIME, IT IS A WAIT AND SEE APPROACH
WITH LITTLE CHANGE TO THE CURRENT FORECAST.
&&
.MARINE...
WIND AND SEAS WILL REMAIN BELOW ADVISORY LEVELS THROUGH THE END OF
THIS WEEK WITH A LIGHT TO MODERATE EAST TO SOUTHEAST WIND AND SEAS
OF 5 FEET OR LESS. THE WIND WILL INCREASE AND BECOME MORE
SOUTHERLY BY FRIDAY AS A COLD FRONT MOVES INTO NORTH FLORIDA AND
THE HIGH PRESSURE SHIFTS FARTHER EAST INTO THE ATLANTIC.
&&
.FIRE WEATHER...
RELATIVE HUMIDITY WILL REMAIN WELL ABOVE CRITICAL THRESHOLDS
THROUGH THE END OF THIS WEEK AS LOW LEVEL MOISTURE WILL CONTINUE
TO INCREASE. THIS WILL ALSO INCREASE THE LIKELIHOOD FOR SOME LATE
NIGHT FOG FORMATION OVER THE INTERIOR AND SOUTHWEST COAST AS THE
WEEK PROGRESSES.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 67 80 69 81 / - - 10 10
FORT LAUDERDALE 70 80 70 82 / - - 10 10
MIAMI 68 77 71 82 / - - 10 10
NAPLES 65 81 65 84 / - - - 10
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...30/KOB
AVIATION/RADAR...23/SK
AREA FORECAST DISCUSSION
NWS TOPEKA KS
324 PM CDT SUN APR 7 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 255 PM CDT SUN APR 7 2013
19Z WATER VAPOR IMAGERY SHOWS A QUASI-ZONAL FLOW ACROSS THE PLAINS
WITH A LOW AMPLITUDE SHORTWAVE MOVING ACROSS THE CO AND NM ROCKIES.
AT THE SURFACE A TROUGH OF LOW PRESSURE IN THE LEE OF THE ROCKIES
HAS STRENGTHENED AND CAUSED SOUTH AND SOUTHEAST WINDS TO INCREASE
BRINGING BETTER MOISTURE NORTH INTO SOUTHERN AND EASTERN KS.
THE UPPER WAVE IS EXPECTED TO MOVE ACROSS THE STATE THIS
EVENING...AND TRIGGER ADDITIONAL THUNDERSTORM DEVELOPMENT ACROSS
CENTRAL KS. THIS ACTIVITY SHOULD MOVE ACROSS NORTHEAST KS THROUGH
THE EVENING. 18Z RUC SHOWS THE BETTER INSTABILITY CURRENTLY OVER
SOUTHERN KS WHERE THE DEWPOINTS ARE IN THE UPPER 50S. AS THE
SOUTHERLY WINDS CONTINUE TO BRING THE MOISTURE AND INSTABILITY INTO
EAST CENTRAL KS...THERE IS THE POTENTIAL THAT ANY CONVECTION IN
SOUTH CENTRAL KS COULD MOVE INTO THE AREA AND REMAIN ORGANIZED
ENOUGH FOR A SEVERE THREAT. PERHAPS THE GREATER THREAT FOR SEVERE
WEATHER MAY COME FROM ANY THUNDERSTORM DEVELOPMENT IN CENTRAL KS
THAT MOVES IN FROM THE WEST THIS EVENING. MODELS SHOW LOW LEVEL
SHEER INCREASING AS THE LOW LEVEL JET INCREASES. HOWEVER THE RAP
CONTINUES TO SHOW THE BEST INSTABILITY REMAINING ACROSS CENTRAL AND
SOUTHERN KS AND ALONG THE SOUTHWESTERN EDGE OF THE FORECAST AREA.
THERE COULD BE A SHORT WINDOW FOR SEVERE WEATHER IF DISCRETE STORMS
WERE ABLE TO FORM AND MOVE INTO THE AREA. GIVEN THE INCREASING 0-1KM
SHEER PARAMETERS...A TORNADO CAN NOT BE RULED OUT EITHER. EVENTUALLY
STORMS SHOULD BECOME MORE ELEVATED WITH CELL MERGERS DISRUPTING
UPDRAFT ORGANIZATION.
THINK THAT AS THE UPPER LEVEL WAVE PASSES EAST AROUND
MIDNIGHT...PRECIP CHANCES WILL QUICKLY DIMINISH OVERNIGHT. OVERNIGHT
LOWS SHOULD BE PRETTY MILD WITH CONTINUED SOUTH WINDS AND MOSTLY
CLOUDY SKIES PREVENTING MUCH IN THE WAY OF RADIATIONAL COOLING. SOME
OF THE OBJECTIVE GUIDANCE HAS LOW STRATUS MOVING IN WITH CONTINUED
MOISTURE ADVECTION FROM THE SOUTH. THEREFORE KEPT AT LEAST MOSTLY
CLOUDY SKIES IN THE FORECAST FOR TONIGHT.
FOR MONDAY FORECAST SOUNDINGS SHOW AN ELEVATED MIXED LAYER MOVING
OVER THE FORECAST AREA WITH LITTLE IN THE WAY OF LARGE SCALE FORCING
OR SURFACE BASED LIFT. BECAUSE OF THIS HAVE REMOVED POPS FOR MUCH OF
THE DAY THINKING THE BOUNDARY LAYER WILL REMAIN CAPPED. THE FORECAST
DOES SHOW CHANCES BEGINNING TO INCREASE LATE IN THE DAY AS DAY TIME
HEATING COULD CAUSE THE CAP TO WEAKEN ACROSS NORTH CENTRAL KS.
DEPENDING ON WHETHER THE LOW CLOUDS DEVELOP OR NOT...HIGHS SHOULD
MAKE IT INTO THE 70S. DID LOWER HIGHS A COUPLE DEGREES ACROSS EAST
CENTRAL KS WHERE CLOUDS ARE EXPECTED TO PERSIST LONGER.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 255 PM CDT SUN APR 7 2013
BY THE EVENING HOURS ON MONDAY...A CONSIDERABLE EML MOVES OVER THE
MAJORITY OF THE CWA. HAVE BACKED OFF ON POPS AS A RESULT ALONG AND
SOUTH OF I70...AND MAY NEED TO BACK OFF EVEN MORE. TO THE
NORTH...THE CAP IS MUCH WEAKER...AND WOULD ANTICIPATE THAT BY
SUNRISE THERE WILL BE ENOUGH LIFT FROM THE LEADING WAVE AS WELL
AS CONVERGENCE IN THE LLJ AND THE SURFACE TROF FOR A LINE OF
THUNDERSTORMS ALONG THE KS NEBRASKA BORDER. COLD FRONT TO THE WEST
IS CONCURRENTLY SURGING TO THE SOUTHEAST AND MAY IMPINGE ON THE
FAR NW CORNER OF THE CWA BY AROUND 12Z TUESDAY...AND WILL CARRY
HIGHEST POPS TO THE NW.
CONDITIONS BY 12Z TUESDAY WILL BE IMPACTED BY PREVIOUS NIGHTS
WEATHER...BUT STILL APPEARS THAT LATE MORNING INTO THE EVENING
HOURS WILL BE THE GREATEST RISK FOR OUR FORECAST AREA FOR STRONG
TO SEVERE STORMS. THE DRYLINE AND FRONT COME TOGETHER OUT IN
WESTERN KANSAS IN THE MORNING AND BOTH MERGE AND MOVE INTO THE
WESTERN COUNTIES BY EARLY AFTERNOON. EC AND GFS SLIGHTLY SLOWER
AND COULD ALLOW FOR A BIT MORE BUILDUP OF INSTABILITY ACROSS THE
EAST BEFORE THE FRONT SURGES THROUGH LATE DAY. WITH WINDS THROUGH
THE COLUMN NEARLY RUNNING PARALLEL TO THE FRONT...DISCRETE CELLS
THAT INITIALLY FORM MAY EVOLVE QUICKLY INTO A LINE THAT ADVANCES
ACROSS THE CWA THROUGH THE EVENING HOURS. THIS WOULD MAKE SEVERE
WINDS THE PRIMARY CONCERN...ALTHOUGH WITH A QUICK INCREASE IN WIND
SPEEDS IN THE LOW LEVELS AND GOOD LOW LEVEL HELICITY CANT RULE OUT
ISOLATED TORNADOES...ESP IN EARLY ONSET OF THE CONVECTION AND IN
ANY STORMS THAT CAN FORM OUT IN THE WARM SECTOR.
TUESDAY NIGHT THROUGH FRIDAY BRING AN UNSEASONABLY COOL PERIOD AS
THE UPPER LOW CONTINUES TO DRAW COLDER AIR INTO THE PLAINS THROUGH
THE END OF THE WEEK. DAYTIME HIGHS WED WILL STRUGGLE TO REACH 40S
WHILE THURS AND FRI MAKE A SLOW CLIMB INTO THE MIDDLE 50S. BY THE
WEEKEND SOUTHERLY FLOW AT THE SURFACE AND WESTERLY FLOW ALOFT
BRING TEMPERATURES BACK TOWARD NORMAL WITH SOME CHANCES FOR RAIN
WITH SOME WEAK WAVES IN THE FLOW.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1234 PM CDT SUN APR 7 2013
TIMING OF CONVECTION DOSE NOT APPEAR TO BE MUCH DIFFERENT FROM THE
PREV FORECAST WITH THE UPPER DISTURBANCE EXPECTED TO MOVE ACROSS
THE AREA THROUGH THE EVENING. BIGGEST UNCERTAINTY IS WITH CIGS
OVERNIGHT. BOTH THE MET AND MAV OBJECTIVE GUIDANCE IS BRINGING
LIFT CIGS IN WITH CONTINUED LOW LEVEL MOISTURE ADVECTION.
CONFIDENCE IS MARGINAL...SO LEFT THE FORECAST FOR MVFR CIGS AFTER
THE PRECIP. LATER SHIFTS CAN REEVALUATE THE LIFR CIGS POTENTIAL.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...WOLTERS
LONG TERM...CRAVEN
AVIATION...WOLTERS
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1234 PM CDT SUN APR 7 2013
.SHORT TERM...(TODAY)
ISSUED AT 442 AM CDT SUN APR 7 2013
TODAY...DEEPER MOISTURE EXTENDING FROM SOUTHERN OK AND EAST TX
WILL BE ADVECTED NORTHWARD AS A LEE SURFACE TROUGH DEEPENS ACROSS
THE CENTRAL AND WESTERN HIGH PLAINS. THE SOUTHERLY LOW- LEVEL FLOW
WILL ADVECT THIS DEEPER MOISTURE NORTHWARD ACROSS EASTERN KS LATE
THIS AFTERNOON.
THE WESTERN GULF OF MEXICO IS NOT AT EQUILIBRIUM EARLY THIS
MORNING...BUT THE RESIDUAL MOISTURE RETURN SHOULD BE SUFFICIENT TO
ALLOW MID TO UPPER 50 DEWPOINTS TO ADVECT NORTHWARD ACROSS THE CWA
BY LATE AFTERNOON.
MEANWHILE...A SHORTWAVE LENGTH H5 TROUGH WAS MOVING EASTWARD ACROSS
CENTRAL CO...SOUTHWARD INTO NORTHWEST NM. THE NAM...ECMWF AND GFS
SHOW THIS H5 TROUGH MOVING EAST ACROSS WESTERN AND CENTRAL KS TODAY.
STRONGER ASCENT AHEAD OF THIS H5 TROUGH AND THE STRONGER ISENTROPIC
LIFT ON THE NORTH SIDE OF DEEPER MOISTURE RETURN WILL ALLOW
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS TO DEVELOP FROM
SOUTH TO NORTH ACROSS THE CWA DURING THE MID AND LATE AFTERNOON
HOURS.
THE VERTICAL WIND SHEAR LOOKS TO BE STRONG WITH 0-6KM SHEAR OF 40 TO
60 KTS ACROSS THE CWA THROUGH THE LATE AFTERNOON HOURS. INSTABILITY
WILL INCREASE THROUGH THE AFTERNOON AS THE DEEPER MOISTURE ADVECTS
NORTHWARD TO AT LEAST I-70. GIVEN STEEP LAPSE RATES FROM 700MB TO
THE SURFACE...ONCE THE DEEPER MOISTURE ADVECT FAR ENOUGH NORTH WE
SHOULD SEE SBCAPE INCREASE TO 1,000 TO 1,500 J/KG FROM I-70 SOUTH.
THE NAM MODEL EVEN SHOWS AN ENHANCED BAND OF 0-1KM SRH OF 80-100
J/KG ALONG THE I-35 CORRIDOR BY 21Z AND LIFTING NORTHWARD TO I-70 BY
00Z. THIS WOULD BE SUFFICIENT FOR DISCRETE SUPERCELL TO POTENTIALLY
PRODUCE ISOLATED TORNADOES. HOWEVER...THE MODE OF CONVECTION IS
STILL IN QUESTION. THE ECMWF...GFS...AND NAM ALL SHOW NUMEROUS
THUNDERSTORMS DEVELOPING ALONG I-35 AFTER 21Z AND EXTENDING WESTWARD
TOWARDS ICT. IF A COMPLEX OR CLUSTER OF THUNDERSTORMS DEVELOPS LATE
IN THE AFTERNOON HOURS ALONG THE NORTHERN EDGE OF DEEPER MOISTURE
RETURN...THEN THE PRIMARY THREAT WILL LARGE HAIL AND SEVERE WIND
GUSTS. THIS COMPLEX OF STORMS WILL DEVELOP NORTHWARD ACROSS EAST
CENTRAL KS LATE IN THE AFTERNOON. IF THE THUNDERSTORMS REMAIN
DISCRETE...THEN GIVEN THE 0-1KM SRH AND INSTABILITY...THEN ISOLATED
TORNADOES COULD NOT BE RULED OUT FOR PORTIONS OF THE CWA...SOUTH OF
I-70. THE RAP AND (ARW) WRF...TWO OF OUR MESOSCALE MODELS...SHOW THE
INITIATION OF DEEP MOIST CONVECTION WEST AND SOUTHWEST OF THE CWA
THROUGH THE LATE AFTERNOON HOURS. THE INITIAL MODE LOOKS DISCRETE
WITH STORM MERGERS OCCURRING AS THEY MOVE NORTHEAST ACROSS THE CWA
DURING THE EARLY EVENING HOURS. STAY TUNED TO LATER UPDATES ON THE
POTENTIAL FOR SEVERE WEATHER LATE THIS AFTERNOON AND EVENING.
TEMPERATURES WILL WARM INTO THE LOWER TO MID 70S WITH PATCHES OF
DENSE HIGH CLOUD COVER SPREADING ACROSS THE CWA THIS MORNING. CU
SHOULD BEGIN TO DEVELOP AS THE DEEPER MOISTURE SURGES NORTHWARD THIS
AFTERNOON.
GARGAN
.LONG TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 442 AM CDT SUN APR 7 2013
CONVECTIVE COMPLEX OF SHOWERS AND THUNDERSTORMS WILL CONTINUE TO
DEVELOP/EXPAND EAST AND NORTHEAST ACROSS PRIMARILY THE SOUTHEAST
HALF OF THE CWA THROUGH THE EARLY AND MID EVENING HOURS WITH A
THREAT FOR PRIMARILY LARGE HAIL WITH THE STRONGER STORMS.
HOWEVER...AS THE SHORTWAVE TROUGH MOVES THROUGH BY LATE
EVENING...THE LLVL FLOW WILL BEGIN TO VEER AND ALLOW FOR SOME DRIER
AIR TO ADVECT EASTWARD WHICH WILL FAVOR THE MORE EASTWARD
PROGRESSION OF THE POSSIBLE MCS. HAVE THEREFORE TRENDED THE HIGHER
POPS THROUGH THE EARLY/MID EVENING...THEN A GRADUAL DECREASED POP
THROUGH LATE EVENING/MIDNIGHT...THEN A MUCH MORE RAPID DROP IN POPS
AFTER MIDNIGHT WEST TO EAST ACROSS THE CWA. WILL KEEP THE SOUTHEAST
CWA WARMER WITH THE CLOUDS AND HIGHER DEWPOINTS IN THE UPPER 50S
WITH NEAR 50 IN THE FAR NORTH CENTRAL.
ON MONDAY...OVERALL LACK OF LARGE SCALE ASCENT/FORCING WITHIN AN
ENVIRONMENT EXHIBITING A RAPIDLY STRENGTHENING ELEVATED MIXED LAYER
(EML) DOES NOT INCREASE CONFIDENCE IN CARRYING POPS BEYOND LOW END
CHANCE CATEGORY. HAVE REMOVED POPS FOR MOST OF THE MORNING...BUT
CARRIED LOW POPS IN THE LATE MORNING/AFTERNOON...ALTHOUGH IMPRESSIVE
INHIBITION MAY WARRANT LOWERING/OR REMOVING POPS MORE. KEPT HIGHS IN
THE LOW TO MID 70S DUE TO EXPECTED STRATUS DECK BENEATH
INVERSION.
BY MONDAY NIGHT...MORE CONVECTION IS EXPECTED TO ADVANCE/DEVELOP
EASTWARD FROM WESTERN/CENTRAL KANSAS THROUGH THE NIGHT PRIMARILY
ALONG THE NORTH OF THE WARM FRONT AS LLVL JET INCREASES THROUGH THE
NIGHT. THE FOCUS FOR THIS HAS CONTINUES TO TREND NORTHWARD WITH
TIME AND STRONG CAPPING OVER THE CWA MAY ALSO INHIBIT THE SOUTH AND
EASTWARD EXTENT OF THE CONVECTION AS WELL. FOR NOW...HAVE KEPT
LIKELY POPS ACROSS THE NORTHERN 2/3 OF THE CWA...BUT IF MODEL TRENDS
CONTINUE...THE HIGHER POPS MAY NEED TO BE TRIMMED/SHIFTED MORE
NORTHWARD CLOSER TO THE NE BORDER.
TUESDAY AND TUESDAY NIGHT STILL APPEARS TO BE THE MOST ACTIVE
TIME FRAME FOR THIS STORM SYSTEM ACROSS OUR CWA AS A DEEPENING SFC
LOW/COLD FRONT ADVANCES EASTWARD ACROSS THE AREA AS THE MAIN
SHORTWAVE ROTATES NORTHEAST OUT OF THE LONGER WAVE TROUGH IN THE
WEST INTO THE NORTHERN PLAINS EARLY WEDNESDAY. CONVECTION COULD
FIRST INITIATE OVER CENTRAL KS THEN CONGEAL INTO A POSSIBLE SQUALL
LINE AS IT MOVES EAST THROUGH THE AFTERNOON/EVENING WITH ALL MODES
OF SEVERE WEATHER POSSIBLE DURING THIS TIME FRAME BEFORE THE FRONT
USHERS IN COOLER AND DRIER AIR INTO EASTERN KS LATE IN THE NIGHT.
WILL KEEP A LINGERING CHANCE FOR DECREASING CONVECTION/RAIN
POTENTIAL ON WEDNESDAY WITH SHOWERS EXITING THE CWA WEDNESDAY
NIGHT...THEN DRY THURSDAY INTO FRIDAY NIGHT. A SLIGHT CHANCE FOR
SHOWERS WILL RETURN BY SATURDAY. AFTER HIGHS IN THE 60S/70S ON
TUESDAY...WEDNESDAY TEMPS WILL COOL INTO THE 40S AND 50S FOR
WEDNESDAY AND THURSDAY...THEN THE 50S FRIDAY AND THE 60S FOR
SATURDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1234 PM CDT SUN APR 7 2013
TIMING OF CONVECTION DOSE NOT APPEAR TO BE MUCH DIFFERENT FROM THE
PREV FORECAST WITH THE UPPER DISTURBANCE EXPECTED TO MOVE ACROSS
THE AREA THROUGH THE EVENING. BIGGEST UNCERTAINTY IS WITH CIGS
OVERNIGHT. BOTH THE MET AND MAV OBJECTIVE GUIDANCE IS BRINGING
LIFT CIGS IN WITH CONTINUED LOW LEVEL MOISTURE ADVECTION.
CONFIDENCE IS MARGINAL...SO LEFT THE FORECAST FOR MVFR CIGS AFTER
THE PRECIP. LATER SHIFTS CAN REEVALUATE THE LIFR CIGS POTENTIAL.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...GARGAN
LONG TERM...63
AVIATION...WOLTERS
AREA FORECAST DISCUSSION
NWS JACKSON KY
136 PM EDT SUN APR 7 2013
.UPDATE...
ISSUED AT 1256 PM EDT SUN APR 7 2013
UPDATED NDFD AND ZFP FOR LATEST OBSERVATIONAL TRENDS. HAVE DECREASED
RAIN CHANCES IN THE FAR NORTH AND INCREASED CLOUD COVER ACROSS THE
ENTIRE AREA. MINIMUM RELATIVE HUMIDITIES IN THE SOUTHEAST PART OF
FORECAST AREA HAVE REACHED 30 TO 35 PERCENT...BUT SHOULD NOT GO TOO
MUCH LOWER...WITH MINIMUMS 25 TO 30 PERCENT EXPECTED THIS AFTERNOON.
UPDATE ISSUED AT 1027 AM EDT SUN APR 7 2013
TEMPERATURE RISE THIS MORNING HAS BEEN QUICKER THAN FORECAST...BUT AT
THE SAME TIME CLOUDS ARE ALSO INCREASING QUICKER. HAVE ADJUSTED THE
HOURLY TEMPERATURE FORECAST AND SKY COVER FORECAST TO ACCOUNT FOR
THIS. INCREASING CLOUDS SHOULD KEEP CURRENT MAXIMUM TEMPERATURE
FORECAST ON TARGET.
ANOTHER ITEM TO ADDRESS FOR THIS UPDATE ARE DEWPOINTS AND POTENTIAL
FIRE WEATHER CONCERNS. DEWPOINTS HAVE BEEN RESPONDING TO INCREASING
SOUTHWEST FLOW...AND DESPITE RELATIVE HUMIDITY CURRENTLY IN THE 30 TO
40 PERCENT RANGE...WE SHOULD SEE RELATIVE HUMIDITY STAY ABOVE CRITICAL
THRESHOLDS. THIS WILL BE MONITORED CLOSELY THOUGH AS WINDS ARE MUCH
STRONGER THAN YESTERDAY. PLAN TO ISSUE AN SPS FOR ENHANCED WILD FIRE
THREAT.
FINALLY HAVE MADE SOME ADJUSTMENTS TO SHOWER CHANCES THIS AFTERNOON.
LATEST HRRR POINTS TOWARDS DELAYING THE ONSET OF RAIN CHANCES AND
ALSO EXTENDING THE CHANCE FURTHER SOUTH. HOWEVER THEN HRRR IS
OVERPLAYING PRECIPITATION CHANCES THIS MORNING. HAVE FOLLOWED THE
IDEA OF DELAYING PRECIPITATION CHANCES...BUT DID NOT EXTEND THE
CHANCE FURTHER SOUTH. HAVE ACTUALLY LOWERED THE PROBABILITY FROM
LIKELY TO CHANCE IN THE NORTH AS WELL.
NDFD AND ZFP HAVE BEEN UPDATED.
UPDATE ISSUED AT 658 AM EDT SUN APR 7 2013
FRONTAL BOUNDARY IS JUST ABOUT TO THE CINCINNATI METRO AREA WITH THE
LINE OF SHOWERS PRETTY MUCH NON-EXISTENT AT THE TIME. HRRR IS ALSO
DOWNPLAYING ACTIVITY ALONG THIS BOUNDARY THROUGH THE MORNING HOURS
WHICH SEEMS VERY REASONABLE. STILL LOOKS LIKE WE COULD SEE AN UPTICK
IN SHOWER OR THUNDERSTORM ACTIVITY THIS AFTERNOON AS INSTABILITY
INCREASES JUST AHEAD OF THE STALLING BOUNDARY. MOST OF THE ACTIVITY
MAY BE TIED TO WHETHER OR NOT WE CAN GET ENOUGH INSTABILITY. GIVEN
DEWPOINTS MUCH LOWER THAN PREVIOUSLY ANTICIPATED...THIS COULD BE IN
JEOPARDY. HOWEVER...WILL MAINTAIN THE CURRENT POPS AND LET DAYSHIFT
RE-EVALUATE IF WE WILL SEE ANY SHOWER ACTIVITY IN THE FAR NORTH
TODAY. DEWPOINTS ARE FINALLY STARTING TO CREEP UP A BIT...BUT REMAIN
MUCH SLOWER THAN MODEL GUIDANCE.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 255 AM EDT SUN APR 7 2013
FAIRLY QUIET WEATHER EARLY THIS SUNDAY MORNING. A VIGOROUS SHORTWAVE
IS PUSHING EAST ACROSS MICHIGAN THIS MORNING WITH A WEAK SURFACE
BOUNDARY BEING DRAGGED ACROSS THE OHIO RIVER VALLEY. AT THE
MOMENT...NOT MUCH ACTIVITY OUTSIDE OF A NARROW LINE OF BROKEN SHOWERS
PUSHING EAST ACROSS NORTHERN INDIANA...BACK INTO SOUTHERN ILLINOIS.
HRRR SEEMS TO HAVE A DECENT HANDLE ON THE RADAR TRENDS THIS MORNING.
THE SHORTWAVE WILL EXIT TO THE EAST TODAY...WITH THE FRONTAL BOUNDARY
STALLING ACROSS NORTHERN WEST VIRGINIA AND NORTHERN KENTUCKY. MODELS
SEEM TO BE IN VERY GOOD AGREEMENT ON THIS PLACEMENT. THE BEST CHANCES
FOR ANY RAIN WITH THIS FRONT WILL RESIDE ALONG THIS BOUNDARY...AND
WILL LIKELY REMAIN ALONG AND NORTH OF I-64. MEANWHILE...DRY
CONDITIONS WILL LIKELY PERSIST ACROSS THE REST OF EASTERN KENTUCKY.
WITH MOISTURE RECOVERY VERY POOR AT BEST OVERNIGHT AND THE PROSPECTS
OF DECENT MIXING TODAY...HAVE GONE WELL BELOW GUIDANCE WITH DEWPOINTS
YET AGAIN TODAY. IN FACT...A FEW PLACES...ESPECIALLY IN SOUTHEAST
KENTUCKY COULD SEE AFTERNOON RELATIVE HUMIDITIES FALL TO UNDER 30
PERCENT. WITH STRONGER SOUTHWEST WINDS TODAY...AHEAD OF THE FRONTAL
BOUNDARY...THIS COULD CREATE A PERIOD OF DANGEROUS FIRE WEATHER
CONDITIONS. THIS THREAT WILL HIGHLIGHTED IN THE HWO AND FIRE WEATHER
PLANNING FORECAST. HIGHS TODAY WILL CLIMB EVEN HIGHER INTO THE LOW TO
MID 70S...EXCEPT IN THE NORTH...WHERE CLOUDS AND PERHAPS
PRECIPITATION MAY KEEP LOCATIONS IN THE 60S.
FRONTAL BOUNDARY WILL SLOWLY DRIFT BACK TO THE NORTH THIS
EVENING...WITH RAIN CHANCES DECREASING FROM SOUTH TO NORTH. SKIES
SHOULD REMAIN MOSTLY TO PARTLY CLEAR OVERNIGHT...ALLOWING SOME VALLEY
LOCATIONS TO DECOUPLE AND FALL BACK INTO THE 40S...WHILE RIDGES STAY
IN THE 50S. ANOTHER VIGOROUS SHORTWAVE WILL TRACK NORTHEAST THROUGH
THE PLAINS ON MONDAY...FURTHER PUSHING THE BOUNDARY TO THE NORTH AND
KEEPING EASTERN KENTUCKY DOMINATED BY STRONG RIDGING. A VERY WARM DAY
IS ON TAP WITH HIGHS SURGING WELL INTO THE 70S AREAWIDE.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 255 AM EDT SUN APR 7 2013
MODELS CONTINUE TO SHOW GENERAL AGREEMENT EARLY IN THE PERIOD IN
TERMS OF HOW SYSTEMS WILL AFFECT OUR LOCAL WEATHER. PATTERN
AMPLIFICATION WILL BE ONGOING...WITH A WESTERN CONUS UPPER TROUGH
AND AND A SOUTHEAST CONUS UPPER RIDGE. STRONG SURFACE LOW PRESSURE
WILL TRACK FROM CO AT THE START OF THE PERIOD TO THE VICINITY OF
IL/IN BY THURSDAY MORNING. A FRONTAL BOUNDARY EXTENDING EAST FROM
THE LOW WILL BE LAID OUT NORTH OF THE OHIO RIVER. MODELS DISAGREE ON
EXACTLY HOW FAR NORTH/SOUTH IT WILL BE POSITIONED. THE ECMWF MANAGES
TO BRING IT FURTHER SOUTH THAN ANY OTHER MODEL...MAKING IT INTO THE
NORTHERN PART OF THE JKL FORECAST AREA BY 12Z THURSDAY. WITH ALL
OTHER GUIDANCE SHOWING IT FURTHER NORTH...WILL GO WITH A FORECAST
THAT KEEPS OUR AREA IN THE WARM SECTOR. A BROAD ZONE OF WARM AIR
ADVECTION WILL BRING MOISTURE NORTH FROM THE GULF OF MEXICO AND LIFT
IT ACROSS THE FRONT. THE BEST CHANCE OF RAIN WITH THIS WILL BE WELL
TO OUR NORTH...BUT CAN NOT RULE OUT SOME SHOWERS MAKING IT INTO THE
NORTHERN PART OF THE AREA.
THE FORECAST BECOMES MORE PROBLEMATIC LATER IN THE WEEK DUE TO
CONTINUED DIFFERENCES IN MODEL TIMING OF THE SURFACE LOW AND ITS
TRAILING COLD FRONT. THE ECMWF IS THE SLOWEST...WITH LOCAL FROPA NOT
HAPPENING UNTIL FRIDAY AFTERNOON. THE END OF THE NAM RUN ON WED
MORNING LOOKS SIMILAR TO THE GFS...WHICH ENDS UP WITH FROPA DURING
THE DAY THURSDAY. THERE ARE SOME MEMBERS OF THE GFS ENSEMBLE WHICH
SHOW SIMILAR TIMING AS THE ECMWF...BUT THE GFS ENSEMBLE MEAN IS MORE
SUPPORTIVE OF THE OPERATIONAL GFS. WILL FAVOR A COMPROMISE SOLUTION
CLOSER TO THE GFS. WITH THAT SAID...HIGHEST POPS...IN LIKELY
CATEGORY...WILL BE ON THURSDAY AND THURSDAY NIGHT. WILL USE HIGH
CHANCE ON FRIDAY TO LEND SOME CREDENCE TO THE ECMWF. ALL MODELS SHOW
INSTABILITY AHEAD OF THE COLD FRONT...AND A CHANCE OF THUNDER WILL
BE USED WITH THE APPROACH AND PASSAGE OF THE COLD FRONT. WINDS ALOFT
LOOK TO BE QUITE STRONG...AND WOULD SUPPORT SEVERE WX. HOWEVER...THE
DEGREE OF INSTABILITY DOES NOT REALLY STAND OUT. THE SET-UP WILL
NEED TO CONTINUE TO BE WATCHED.
THE WARMEST AIR MASS OF THE SEASON SO FAR WILL BE IN PLACE UP UNTIL
COLD FROPA. NEEDLESS TO SAY...FRONTAL TIMING WILL PLAY A KEY ROLE IN
TEMPS LATE IN THE PERIOD...AND LEADS TO A LOWER CONFIDENCE IN THE
TEMPERATURE FORECAST FOR THURSDAY INTO FRIDAY...AND A POTENTIAL FOR
MORE SIZEABLE ERRORS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 136 PM EDT SUN APR 7 2013
A COLD FRONT CONTINUES TO SLOWLY SAG SOUTH ACROSS OH AND INDIANA.
CLOUDS HAVE INCREASED AHEAD OF THE FRONT ACROSS KY...BUT CEILINGS ARE
EXPECTED TO REAMIN VFR THROUGH MONDAY. ISOLATED THUNDERSTORMS ARE STILL
POSSIBLE ACROSS FAR NORTHERN KY THIS AFTERNOON...BUT IF ANY OCCUR
THEY WILL BE WELL NORTH OF THE TAF SITES. GUSTY SOUTHWEST WINDS THIS
AFTERNOON WILL DIMINISH THIS EVENING.
&&
.FIRE WEATHER...
ISSUED AT 1051 AM EDT SUN APR 7 2013
DEWPOINTS HAVE BEEN RISING IN THE INCREASING SOUTHWEST FLOW...AND
DESPITE RELATIVE HUMIDITY CURRENTLY IN THE 30 TO 40 PERCENT
RANGE OVER SOUTHEAST KY...WE SHOULD SEE RELATIVE HUMIDITY STAY ABOVE
CRITICAL THRESHOLDS. HOWEVER SOME SPOTS WILL BE NEAR 25 PERCENT RH
THIS AFTERNOON. THIS WILL BE MONITORED CLOSELY AS WINDS ARE MUCH
STRONGER THAN YESTERDAY...WITH GUSTS TO 30 MPH EXPECTED FOR THIS
AFTERNOON. HAVE ISSUED AN SPS FOR ENHANCED WILD FIRE THREAT.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SBH
SHORT TERM...KAS
LONG TERM...HAL
AVIATION...SBH
FIRE WEATHER...SBH
AREA FORECAST DISCUSSION
NWS JACKSON KY
1257 PM EDT SUN APR 7 2013
.UPDATE...
ISSUED AT 1256 PM EDT SUN APR 7 2013
UPDATED NDFD AND ZFP FOR LATEST OBSERVATIONAL TRENDS. HAVE DECREASED
RAIN CHANCES IN THE FAR NORTH AND INCREASED CLOUD COVER ACROSS THE
ENTIRE AREA. MINIMUM RELATIVE HUMIDITIES IN THE SOUTHEAST PART OF
FORECAST AREA HAVE REACHED 30 TO 35 PERCENT...BUT SHOULD NOT GO TOO
MUCH LOWER...WITH MINIMUMS 25 TO 30 PERCENT EXPECTED THIS AFTERNOON.
UPDATE ISSUED AT 1027 AM EDT SUN APR 7 2013
TEMPERATURE RISE THIS MORNING HAS BEEN QUICKER THAN FORECAST...BUT AT
THE SAME TIME CLOUDS ARE ALSO INCREASING QUICKER. HAVE ADJUSTED THE
HOURLY TEMPERATURE FORECAST AND SKY COVER FORECAST TO ACCOUNT FOR
THIS. INCREASING CLOUDS SHOULD KEEP CURRENT MAXIMUM TEMPERATURE
FORECAST ON TARGET.
ANOTHER ITEM TO ADDRESS FOR THIS UPDATE ARE DEWPOINTS AND POTENTIAL
FIRE WEATHER CONCERNS. DEWPOINTS HAVE BEEN RESPONDING TO INCREASING
SOUTHWEST FLOW...AND DESPITE RELATIVE HUMIDITY CURRENTLY IN THE 30 TO
40 PERCENT RANGE...WE SHOULD SEE RELATIVE HUMIDITY STAY ABOVE CRITICAL
THRESHOLDS. THIS WILL BE MONITORED CLOSELY THOUGH AS WINDS ARE MUCH
STRONGER THAN YESTERDAY. PLAN TO ISSUE AN SPS FOR ENHANCED WILD FIRE
THREAT.
FINALLY HAVE MADE SOME ADJUSTMENTS TO SHOWER CHANCES THIS AFTERNOON.
LATEST HRRR POINTS TOWARDS DELAYING THE ONSET OF RAIN CHANCES AND
ALSO EXTENDING THE CHANCE FURTHER SOUTH. HOWEVER THEN HRRR IS
OVERPLAYING PRECIPITATION CHANCES THIS MORNING. HAVE FOLLOWED THE
IDEA OF DELAYING PRECIPITATION CHANCES...BUT DID NOT EXTEND THE
CHANCE FURTHER SOUTH. HAVE ACTUALLY LOWERED THE PROBABILITY FROM
LIKELY TO CHANCE IN THE NORTH AS WELL.
NDFD AND ZFP HAVE BEEN UPDATED.
UPDATE ISSUED AT 658 AM EDT SUN APR 7 2013
FRONTAL BOUNDARY IS JUST ABOUT TO THE CINCINNATI METRO AREA WITH THE
LINE OF SHOWERS PRETTY MUCH NON-EXISTENT AT THE TIME. HRRR IS ALSO
DOWNPLAYING ACTIVITY ALONG THIS BOUNDARY THROUGH THE MORNING HOURS
WHICH SEEMS VERY REASONABLE. STILL LOOKS LIKE WE COULD SEE AN UPTICK
IN SHOWER OR THUNDERSTORM ACTIVITY THIS AFTERNOON AS INSTABILITY
INCREASES JUST AHEAD OF THE STALLING BOUNDARY. MOST OF THE ACTIVITY
MAY BE TIED TO WHETHER OR NOT WE CAN GET ENOUGH INSTABILITY. GIVEN
DEWPOINTS MUCH LOWER THAN PREVIOUSLY ANTICIPATED...THIS COULD BE IN
JEOPARDY. HOWEVER...WILL MAINTAIN THE CURRENT POPS AND LET DAYSHIFT
RE-EVALUATE IF WE WILL SEE ANY SHOWER ACTIVITY IN THE FAR NORTH
TODAY. DEWPOINTS ARE FINALLY STARTING TO CREEP UP A BIT...BUT REMAIN
MUCH SLOWER THAN MODEL GUIDANCE.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 255 AM EDT SUN APR 7 2013
FAIRLY QUIET WEATHER EARLY THIS SUNDAY MORNING. A VIGOROUS SHORTWAVE
IS PUSHING EAST ACROSS MICHIGAN THIS MORNING WITH A WEAK SURFACE
BOUNDARY BEING DRAGGED ACROSS THE OHIO RIVER VALLEY. AT THE
MOMENT...NOT MUCH ACTIVITY OUTSIDE OF A NARROW LINE OF BROKEN SHOWERS
PUSHING EAST ACROSS NORTHERN INDIANA...BACK INTO SOUTHERN ILLINOIS.
HRRR SEEMS TO HAVE A DECENT HANDLE ON THE RADAR TRENDS THIS MORNING.
THE SHORTWAVE WILL EXIT TO THE EAST TODAY...WITH THE FRONTAL BOUNDARY
STALLING ACROSS NORTHERN WEST VIRGINIA AND NORTHERN KENTUCKY. MODELS
SEEM TO BE IN VERY GOOD AGREEMENT ON THIS PLACEMENT. THE BEST CHANCES
FOR ANY RAIN WITH THIS FRONT WILL RESIDE ALONG THIS BOUNDARY...AND
WILL LIKELY REMAIN ALONG AND NORTH OF I-64. MEANWHILE...DRY
CONDITIONS WILL LIKELY PERSIST ACROSS THE REST OF EASTERN KENTUCKY.
WITH MOISTURE RECOVERY VERY POOR AT BEST OVERNIGHT AND THE PROSPECTS
OF DECENT MIXING TODAY...HAVE GONE WELL BELOW GUIDANCE WITH DEWPOINTS
YET AGAIN TODAY. IN FACT...A FEW PLACES...ESPECIALLY IN SOUTHEAST
KENTUCKY COULD SEE AFTERNOON RELATIVE HUMIDITIES FALL TO UNDER 30
PERCENT. WITH STRONGER SOUTHWEST WINDS TODAY...AHEAD OF THE FRONTAL
BOUNDARY...THIS COULD CREATE A PERIOD OF DANGEROUS FIRE WEATHER
CONDITIONS. THIS THREAT WILL HIGHLIGHTED IN THE HWO AND FIRE WEATHER
PLANNING FORECAST. HIGHS TODAY WILL CLIMB EVEN HIGHER INTO THE LOW TO
MID 70S...EXCEPT IN THE NORTH...WHERE CLOUDS AND PERHAPS
PRECIPITATION MAY KEEP LOCATIONS IN THE 60S.
FRONTAL BOUNDARY WILL SLOWLY DRIFT BACK TO THE NORTH THIS
EVENING...WITH RAIN CHANCES DECREASING FROM SOUTH TO NORTH. SKIES
SHOULD REMAIN MOSTLY TO PARTLY CLEAR OVERNIGHT...ALLOWING SOME VALLEY
LOCATIONS TO DECOUPLE AND FALL BACK INTO THE 40S...WHILE RIDGES STAY
IN THE 50S. ANOTHER VIGOROUS SHORTWAVE WILL TRACK NORTHEAST THROUGH
THE PLAINS ON MONDAY...FURTHER PUSHING THE BOUNDARY TO THE NORTH AND
KEEPING EASTERN KENTUCKY DOMINATED BY STRONG RIDGING. A VERY WARM DAY
IS ON TAP WITH HIGHS SURGING WELL INTO THE 70S AREAWIDE.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 255 AM EDT SUN APR 7 2013
MODELS CONTINUE TO SHOW GENERAL AGREEMENT EARLY IN THE PERIOD IN
TERMS OF HOW SYSTEMS WILL AFFECT OUR LOCAL WEATHER. PATTERN
AMPLIFICATION WILL BE ONGOING...WITH A WESTERN CONUS UPPER TROUGH
AND AND A SOUTHEAST CONUS UPPER RIDGE. STRONG SURFACE LOW PRESSURE
WILL TRACK FROM CO AT THE START OF THE PERIOD TO THE VICINITY OF
IL/IN BY THURSDAY MORNING. A FRONTAL BOUNDARY EXTENDING EAST FROM
THE LOW WILL BE LAID OUT NORTH OF THE OHIO RIVER. MODELS DISAGREE ON
EXACTLY HOW FAR NORTH/SOUTH IT WILL BE POSITIONED. THE ECMWF MANAGES
TO BRING IT FURTHER SOUTH THAN ANY OTHER MODEL...MAKING IT INTO THE
NORTHERN PART OF THE JKL FORECAST AREA BY 12Z THURSDAY. WITH ALL
OTHER GUIDANCE SHOWING IT FURTHER NORTH...WILL GO WITH A FORECAST
THAT KEEPS OUR AREA IN THE WARM SECTOR. A BROAD ZONE OF WARM AIR
ADVECTION WILL BRING MOISTURE NORTH FROM THE GULF OF MEXICO AND LIFT
IT ACROSS THE FRONT. THE BEST CHANCE OF RAIN WITH THIS WILL BE WELL
TO OUR NORTH...BUT CAN NOT RULE OUT SOME SHOWERS MAKING IT INTO THE
NORTHERN PART OF THE AREA.
THE FORECAST BECOMES MORE PROBLEMATIC LATER IN THE WEEK DUE TO
CONTINUED DIFFERENCES IN MODEL TIMING OF THE SURFACE LOW AND ITS
TRAILING COLD FRONT. THE ECMWF IS THE SLOWEST...WITH LOCAL FROPA NOT
HAPPENING UNTIL FRIDAY AFTERNOON. THE END OF THE NAM RUN ON WED
MORNING LOOKS SIMILAR TO THE GFS...WHICH ENDS UP WITH FROPA DURING
THE DAY THURSDAY. THERE ARE SOME MEMBERS OF THE GFS ENSEMBLE WHICH
SHOW SIMILAR TIMING AS THE ECMWF...BUT THE GFS ENSEMBLE MEAN IS MORE
SUPPORTIVE OF THE OPERATIONAL GFS. WILL FAVOR A COMPROMISE SOLUTION
CLOSER TO THE GFS. WITH THAT SAID...HIGHEST POPS...IN LIKELY
CATEGORY...WILL BE ON THURSDAY AND THURSDAY NIGHT. WILL USE HIGH
CHANCE ON FRIDAY TO LEND SOME CREDENCE TO THE ECMWF. ALL MODELS SHOW
INSTABILITY AHEAD OF THE COLD FRONT...AND A CHANCE OF THUNDER WILL
BE USED WITH THE APPROACH AND PASSAGE OF THE COLD FRONT. WINDS ALOFT
LOOK TO BE QUITE STRONG...AND WOULD SUPPORT SEVERE WX. HOWEVER...THE
DEGREE OF INSTABILITY DOES NOT REALLY STAND OUT. THE SET-UP WILL
NEED TO CONTINUE TO BE WATCHED.
THE WARMEST AIR MASS OF THE SEASON SO FAR WILL BE IN PLACE UP UNTIL
COLD FROPA. NEEDLESS TO SAY...FRONTAL TIMING WILL PLAY A KEY ROLE IN
TEMPS LATE IN THE PERIOD...AND LEADS TO A LOWER CONFIDENCE IN THE
TEMPERATURE FORECAST FOR THURSDAY INTO FRIDAY...AND A POTENTIAL FOR
MORE SIZEABLE ERRORS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 658 AM EDT SUN APR 7 2013
VFR CONDITIONS WILL HOLD ON THROUGH THE PERIOD. AN APPROACHING COLD
FRONT WILL MOVE INTO NORTHERN KENTUCKY TODAY. SOME SCATTERED SHOWERS
AND A FEW THUNDERSTORMS ARE POSSIBLE...MAINLY NORTH OF I-64. LOWER
CLOUDS AND PRECIPITATION WILL NOT LIKELY MAKE IT SOUTH OF
I-64...KEEPING THE TAF SITES DRY WITH JUST SOME HIGH CLOUDS TO
CONTEND WITH.
&&
.FIRE WEATHER...
ISSUED AT 1051 AM EDT SUN APR 7 2013
DEWPOINTS HAVE BEEN RISING IN THE INCREASING SOUTHWEST FLOW...AND
DESPITE RELATIVE HUMIDITY CURRENTLY IN THE 30 TO 40 PERCENT
RANGE OVER SOUTHEAST KY...WE SHOULD SEE RELATIVE HUMIDITY STAY ABOVE
CRITICAL THRESHOLDS. HOWEVER SOME SPOTS WILL BE NEAR 25 PERCENT RH
THIS AFTERNOON. THIS WILL BE MONITORED CLOSELY AS WINDS ARE MUCH
STRONGER THAN YESTERDAY...WITH GUSTS TO 30 MPH EXPECTED FOR THIS
AFTERNOON. HAVE ISSUED AN SPS FOR ENHANCED WILD FIRE THREAT.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SBH
SHORT TERM...KAS
LONG TERM...HAL
AVIATION...KAS
FIRE WEATHER...SBH
AREA FORECAST DISCUSSION
NWS GRAY ME
433 PM EDT SUN APR 7 2013
.SYNOPSIS...
LOW PRESSURE CROSSING SOUTHERN CANADA WILL DRAG A COLD FRONT
THROUGH THE REGION OVERNIGHT. A WEAK AREA OF HIGH PRESSURE WILL
BUILD OVER THE REGION ON MONDAY. ANOTHER AREA OF LOW PRESSURE
WILL HEAD EAST FROM THE GREAT LAKES MONDAY NIGHT AND WILL MOVE
THROUGH SOUTHERN NEW ENGLAND AND OUT TO SEA ON TUESDAY. LOW
PRESSURE WILL ONCE AGAIN APPROACH FROM THE WEST TUESDAY NIGHT
LIFTING A WARM FRONT INTO CENTRAL NEW ENGLAND ON WEDNESDAY WHERE
IT WILL STALL. LOW PRESSURE MOVING NORTHEAST THROUGH THE ST
LAWRENCE VALLEY WILL LIFT THE WARM FRONT INTO NORTHERN NEW ENGLAND
ON THURSDAY. A TRAILING COLD FRONT WILL CROSS THE AREA THURSDAY
NIGHT AND WILL SLOWLY PUSH OFFSHORE ON FRIDAY. HIGH PRESSURE WILL
BUILD IN FROM THE WEST SATURDAY THROUGH SUNDAY.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
UPDATE...
HAVE UPDATED GRIDS TO ACCOUNT FOR CURRENT CONDITIONS. WINDS
CONTINUE TO GUST BETWEEN 20 AND 30 MPH ACROSS THE FORECAST
AREA...WITH HIGHEST GUSTS ALONG THE EXPOSED COASTLINE...AND ALSO
OVER IN NH WHERE TEMPERATURES CLIMBED WELL INTO THE 50S.
HAVE REMOVED FZRA FROM TNGTS FCST AS GROUND TEMPS SEEM A LITTLE
TOO WARM WITH READINGS CURRENTLY IN THE 50S IN THE MTNS. HAVE ALSO
USED THE "SHOWERIZE" TOOL FOR TNGTS PCPN.
LATEST RUC SOLUTION PICKS UP ON CONVECTIVE LINE ALONG THE VT/NH
BORDER (AS OF 2032Z) VERY WELL. HOWEVER...THIS LINE OF PCPN SHOULD
WEAKEN SIGNIFICANTLY AS IT ENTERS THE REGION OF MUCH LOWER SURFACE
DEW POINTS.
HAVE ADJUSTED DEW POINTS BASED ON CURRENT CONDITIONS. ALSO...USED
CLOUD COVER FROM STLT FOR THE INTIAL CONDS AS CLOUD DECKS ARE
RAPIDLY CHANGING.
PREV DISC...
LOW PRESSURE CROSSING SOUTHERN CANADA WILL DRAG A COLD FRONT
THROUGH THE REGION OVERNIGHT. SHOWERS AND A FEW THUNDERSTORMS
CURRENTLY PUSHING THROUGH EASTERN NEW YORK AHEAD OF THE FRONT AND
THIS LINE WILL BRING THE BEST CHANCE OF PRECIP TO THE REGION
DURING THE EVENING HOURS. MAY SEE SOME SLEET OR SNOW GRAINS MIXING
IN IN THE NORTH BUT NOT LOOKING FOR ANY ACCUMULATIONS. SHOULD SEE
PARTIAL CLEARING DOWNWIND OF THE MOUNTAINS DURING THE EARLY
MORNING HOURS WHILE CLOUDS PERSIST IN THE NORTH. WILL SEE A
RELATIVELY MILD NIGHT WITH LOWS IN THE LOWER TO MID 30S NORTH AND
UPPER 30S TO LOWER 40S IN THE SOUTH.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
MOUNTAIN CLOUDS WILL GRADUALLY DIMINISH MONDAY MORNING AND SHOULD
SEE MOSTLY SUNNY SKIES ACROSS THE REGION BY AFTERNOON AS A WEAK
RIDGE OF HIGH PRESSURE BUILDS OVER THE REGION. WILL SEE TEMPS
REBOUND TO ABOVE NORMAL...ALTHOUGH EXPECT AN AFTERNOON SEA BREEZE
TO CAP HIGHS IN THE MID TO UPPER 50S IN COASTAL AREAS. WARMER
SOUTHERN INTERIOR SECTIONS WILL ENJOY HIGHS IN THE LOWER TO MID 60S.
RAPID FIRE PROCESSION SHORTWAVES WILL CONTINUE MONDAY NIGHT AS LOW
PRESSURE QUICKLY HEADS EAST FROM THE GREAT LAKES. CLOUDS WILL
OVERSPREAD THE REGION FROM WEST TO EAST DURING THE EVENING HOURS
WITH RAIN MOVING INTO MUCH OF THE REGION AROUND MIDNIGHT. MAY SEE
ENOUGH COOLING FOR RAIN TO MIX WITH SLEET OR SNOW IN THE NORTH
WHERE AN INCH OR TWO OF WET SNOW MAY ACCUMULATE OVER THE HIGHER
TERRAIN. WILL ONCE AGAIN SEE MILD OVERNIGHT LOWS WITH MID TO UPPER
30S NORTH AND UPPER 30S TO LOWER 40S SOUTH.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
SFC LOW TRACKS ACROSS THE FCST AREA TUESDAY WITH RA/SHRA THRU THE
MORNING IN NH AND MIDDAY OVER ME...THEN AS THE LOW MOVES QUICKLY TO
THE E CLEARING FOLLOWS FROM W TO E. A TRAILING FNT DEVELOPS W OF THE
LOW ACROSS THE FCST AREA AND FURTHER TO THE W TUESDAY NGT. THIS FNT
SEPARATES MUCH WARMER AIR TO THE S FROM MUCH COLDER AIR TO THE N.
THE FNT SAGS SLOWLY TO THE S ON WEDNESDAY WITH VERY WEAK LOW PRES
SLIDING TO THE E ALONG THE BOUNDARY. THE FNT WAVERS WEDNESDAY NGT
THRU THURSDAY NGT AS OTHER WEAK LOWS TRACK EASTWARD ALONG IT. THE
EXACT LOCATION OF THE FNT VARIES AMONGST THE MODELS WITH THE ECMWF
THE COLDEST WITH THE BOUNDARY TO OUR S, GFS THE WARMEST WITH THE FNT
JUST TO OUR N AND THE CMC MODEL IN BETWEEN THOUGH CLOSER TO THE GFS.
EITHER WAY THE SYSTEM WILL GIVE US A PERIOD OF WET WX...MOSTLY
RA...THOUGH SOME MIX OR MAYBE SN OVER FAR NORTHERN AND MOUNTAIN ZONES
PSBL. THE GFS WARMS US UP CONSIDERABLY WITH H8 TEMPS OF PLUS 10 TO
NEARLY PLUS 15. THIS APPEARS OVERDONE THOUGH THE ECMWF WHICH IS MUCH
COLDER MAY ALSO BE OVERDONE... SO A COMPROMISE IS IN ORDER.
FINALLY THE LAST LOW MOVES E ON FRIDAY WITH A TRAILING CD FNT ALSO
PUSHING TO THE E. TIMING OF THIS SYSTEM STILL TO EARLY TO DETERMINE
WHETHER OR NOT WE SEE PRCP FOR MOST OF THE DAY OR IF IT COMES TO
AN END EARLIER ON. ALSO...THE ECMWF IS TRACKING THE LOW TO OUR S
RATHER THAN OVER US LIKE THE GFS THUS THE ECMWF MODEL PROVIDES A
BETTER CHC FOR MIXED/SN EVENT ON FRIDAY.
BEHIND THIS SYSTEM STRONG GUSTY NW WINDS USHER IN COLDER AND DRIER
AIR FRIDAY NGT AND SATURDAY. HIGH PRES BUILDS IN ON SUNDAY WITH
WEAKER WINDS AND WARMING TEMPS AS THE AIR MASS MODERATES.
GENERALLY USED BLEND OF ECMWF, GFS40, NAM, HPC GUIDANCE, GMOS AND
MEX MOS AND WNA4 FOR SEAS FOR THE LONG TERM FCST.
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
SHORT TERM...AREAS OF MVFR/IFR CEILINGS TONIGHT...BECOMING VFR ON
MONDAY. MORE MVFR/IFR CEILINGS DEVELOPING AFTER MIDNIGHT MONDAY NIGHT.
LONG TERM /TUESDAY THROUGH FRIDAY/...AN LENGTHY PERIOD OF UNSETTLED
WET WEATHER THRU THE LONG TERM PERIOD AS A FRONTAL BOUNDARY STAYS
NEARBY WHILE LOW PRES SYSTEMS TRACK E ALONG IT. THUS FREQUENT
IFR/LIFR CONDITIONS PSBL TUESDAY THRU FRIDAY.
&&
.MARINE...
SHORT TERM...CONTINUING SCA`S THROUGH TONIGHT.
LONG TERM /TUESDAY THROUGH FRIDAY/...
UPDATE...
HAVE EXTENDED THE SCAS INTO MONDAY FOR THE OUTER WATERS. THIS IS
MAINLY DUE TO SEAS.
PREV DISC...
CONDITIONS MAINLY BELOW SCA
LEVELS TUESDAY THRU WEDNESDAY NGT AS FNT REMAINS NEARBY AND PRES
GRADIENT FAIRLY WEAK AS WEAK LOW PRES MOVES ALONG THE FNT.
THURSDAY THRU FRIDAY...DEPENDING ON THE MODEL SOLUTION... THERE IS
THE POTENTIAL FOR A MORE SIGNIFICANT LOW TO FORM WHICH WOULD
INCREASE WINDS AND BUILD SEAS POSSIBLY TO SCA LEVELS...OR MAYBE
INTO MINIMAL GALE FORCE OVER THE OUTER WATERS.
&&
.FIRE WEATHER...
RAIN SHOWERS WILL HELP TO DAMPEN FIRE DANGER
OVERNIGHT. WARMER TEMPS AND HIGHER DEW POINTS WILL KEEP THE REGION
ABOVE RED FLAG CRITERIA MONDAY WITH ANOTHER ROUND OF SHOWERS
COMING THROUGH MONDAY NIGHT.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT MONDAY FOR ANZ150>154.
&&
$$
JC
AREA FORECAST DISCUSSION
NWS SPRINGFIELD MO
1242 PM CDT SUN APR 7 2013
.MESOSCALE DISCUSSION...
ISSUED AT 1241 PM CDT SUN APR 7 2013
MOISTURE CONTINUES TO SLOWLY INCREASE FROM SOUTHWEST TO NORTHEAST
INTO THE REGION. NOTICEABLY MORE HUMID WITH DECENT CUMULUS
DEVELOPMENT NOTED OVER THE PAST FEW HOURS. MID LEVEL FEATURES ARE
A BIT MESSY AT THIS POINT...WITH A MORE DEFINITIVE SHORTWAVE
OBSERVED VIA RAP INITIALIZATIONS ACROSS WESTERN PORTIONS OF
OKLAHOMA AND KANSAS. THIS FEATURE WILL BE MONITORED AS A
TRIGGERING MECHANISM FOR CONVECTION THIS AFTERNOON. EXPECTATIONS
ARE FOR A GENERAL INCREASE IN CONVECTIVE DEVELOPMENT AND COVERAGE
AS THE AFTERNOON PROGRESSES...WITH BETTER CHANCES FOR THE WESTERN
HALF OF THE OUTLOOK AREA DURING THE MID/LATE AFTERNOON HOURS.
MLCAPE IN THE 1000 TO 1250 J/KG RANGE AND MUCAPE AROUND 1500 J/KG
IS EXPECTED THIS AFTERNOON. WITH DEEP LAYER SHEAR ON THE AROUND OF
40 OR SO KNOTS...STORM MODE FAVOR SUPERCELLULAR STRUCTURES (THOUGH
A MIX OF MULTICELLS/LINE SEGMENTS IS PLAUSIBLE AS WELL). SLIGHT
RISK UPDATED AT MIDDAY BY SPC IS WELL PLACED AND WITH HAIL BEING
THE MAIN RISK. CANNOT RULE OUT LOCALIZED DAMAGING WIND GUSTS.
LATEST AVAILABLE 12Z MODEL OUTPUT AND MESOSCALE MODELS CONTINUE TO
DIFFER ON THE EVOLUTION OF CONVECTION THIS EVENING INTO THE
OVERNIGHT HOURS...THOUGH THE TREND OF HAVING STORMS FOCUSING
PROGRESSIVELY TO THE NORTH OF THE AREA IS THE OVERALL TREND. WILL
CONTINUE TO REFINE SPECIFIC EXPECTATIONS FOR THE OVERNIGHT
FORECAST SHORTLY.
&&
.SHORT TERM...(TODAY THROUGH MONDAY NIGHT)
ISSUED AT 307 AM CDT SUN APR 7 2013
WEAK FRONTAL BOUNDARY HAD PUSHED INTO NORTHERN MISSOURI EARLY THIS
MORNING. IT HAD SET OFF A FEW SHOWERS OVER MAINLY EAST CENTRAL
MISSOURI EARLIER IN THE EVENING BUT THOSE HAVE SINCE DISSIPATED.
THIS BOUNDARY SHOULD PUSH INTO SOUTHERN MISSOURI LATER THIS
MORNING AND WILL ACT AS A FOCUS FOR THUNDERSTORM ACTIVITY LATER
IN THE DAY.
A SHORT WAVE COMING OUT OF THE ROCKIES WILL ALLOW THIS FRONT TO
STALL OUT AND PUSH BACK NORTHWARD AS A WARM FRONT. MOISTURE WILL
BE ON THE INCREASE AS WELL WITH DEW POINTS CLIMBING INTO THE MID
50S BY THIS AFTERNOON. MUCAPES SHOULD BE CLOSE TO 2000 J/KG LATE
THIS AFTERNOON WITH 0-6KM SHEAR VALUES AROUND 40 KTS. THIS SHOULD
GET STORMS GOING LATE THIS AFTERNOON WITH A CONTINUATION INTO THE
EVENING HOURS AS THE LOW LEVEL JET INCREASES. BELIEVE THAT THE
PRIMARY THREAT WILL BE LARGE HAIL ALTHOUGH WINDS CANNOT BE RULED
OUT AS WELL IF WE GET SUPERCELLS.
MONDAY WILL BE A DIFFERENT STORY. A FAIRLY STRONG ELEVATED MIXED
LAYER WILL BE IN PLACE WHICH WILL TEND TO CAP THE ATMOSPHERE OVER
THE REGION. HAVE THEREFORE KEPT POPS IN THE SLIGHT CHANCE CATEGORY
FOR MONDAY.
HIGH TEMPERATURES SHOULD HAVE NO TROUBLE MAKING IT INTO THE 70S
WITH THE AREA IN THE WARM SECTOR. WITH THE ADDITION OF THE GULF
MOISTURE...OVERNIGHT LOWS WILL BE RATHER MILD JUST MAKING IT INTO
THE MID TO UPPER 50S.
.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 307 AM CDT SUN
APR 7 2013
THE MAIN CONCERN WILL BE SEVERE WEATHER AND HEAVY RAIN CHANCES LATE
TUE THROUGH WED. AN UPPER LEVEL JET NOW JUST OFF THE THE U.S. PAC NW
COAST AND BRITISH COLUMBIA WILL DIG SOUTHEAST INTO THE SW
U.S...CLOSE TO THE FOUR CORNERS REGION BY 12Z TUE. THE GENERAL MODEL
CONSENSUS IS THAT A LONG WAVE POSITIVELY TILTED TROUGH AXIS WILL
EXTEND FROM THE DAKOTAS TO NEW MEXICO BY MIDDAY WED LEAVING OUR
AREA IN A REGION OF SW FLOW ALOFT. A STRONG CAP/EML WILL BE IN
PLACE TUE. MID LEVEL HEIGHT FALLS/COOLING AND LIFT WITH THE
APPROACHING UPPER LEVEL SYSTEM SHOULD ALLOW STORMS TO DEVELOP
ALONG THE DRY LINE OVER CENTRAL KS/WESTERN OK TUE AFTERNOON...AND
WITH TIME THIS CONVECTION WILL SPREAD EAST INTO EASTERN KS AND
WESTERN MO LATE TUE OR TUE EVENING. THE GFS AND GEM CONTINUE TO BE
FASTER IN BRINGING THE SFC COLD FRONT INTO THE REGION...6-12
HOURS FASTER THAN THE ECMWF...SO TIMING AND DETAILS ARE STILL UP
IN THE AIR. GIVEN SW FLOW ALOFT NOT SURE HOW LONG CONVECTION CAN
REMAIN DISCRETE BEFORE FILLING IN AND BECOME MORE OF A LINEAR
CLUSTER(S)/COMPLEX...BUT GENERAL SHEAR AND INSTABILITY SUPPORT A
CONTINUED MENTION OF A CHANCE FOR SEVERE WX.
THE WAVY SFC FRONT MAY LINGER OVER THE MS VLY TO PRODUCE PERIODS OF
POST FRONTAL HEAVIER SHOWERS/TSTMS WED BEFORE CHILLY AIR ONCE AGAIN
MAKES ANOTHER APPEARANCE WED NIGHT AND THU. A N-S ORIENTED SFC RIDGE
WILL SHIFT THROUGH THE AREA LATE IN THE WEEK WITH GENERALLY
DRY...COOL...AND QUIET WEATHER.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1241 PM CDT SUN APR 7 2013
FOR THE 18Z TAFS (JLN/SGF/BBG)...PRIMARY FORECAST CONCERN IS THE
POTENTIAL FOR SCATTERED THUNDERSTORMS FROM THE MIDDLE OF THIS
AFTERNOON THROUGH THIS EVENING. CONFIDENCE IN EXACT COVERAGE IS
STILL LOW...AND HAVE OPTED TO USE VCTS AT JLN AND SGF FOR THE TIME
BEING UNTIL CONFIDENCE INCREASES. HAVE KEPT BBG DRY FOR NOW...AN
ISOLATED SHOWER OR STORM CANNOT BE RULED OUT HERE...HOWEVER IT
APPEARS THE BETTER OPPORTUNITY FOR ACTIVITY WILL BE TO THE
NORTHWEST OF THE BBG AERODROME. CHANCES FOR STORMS WILL PERSIST
THROUGH THIS EVENING...WITH THE FOCUSING LIFTING NORTH OF THE
AERODROMES OVERNIGHT TONIGHT. LOW LEVEL WIND SHEAR WILL BE
PREVALENT TONIGHT AS A MODERATE LOW LEVEL JET SPREADS OVER THE
REGION. LAMP AS WELL AS MAV/MET MOS GUIDANCE CONTINUE TO HINT AT
IFR CIG DEVELOPMENT AT ALL TAF SITES THIS EVENING AND PERSISTING
INTO MONDAY. UPSTREAM OBS IN OKLAHOMA DID FLIRT WITH IFR STRATUS
AT TIMES...THOUGH NOT QUITE READY TO BITE OFF ON WIDESPREAD IFR
AFTER LOOKING AT THE SREF PROBABILITIES. HAVE MAINTAINED
DEVELOPMENT OF LOW END MVFR CIGS.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
MESOSCALE...GAGAN
SHORT TERM...GAEDE
LONG TERM...DSA
AVIATION...GAGAN
AREA FORECAST DISCUSSION
NWS BILLINGS MT
310 PM MDT SUN APR 7 2013
.SHORT TERM...VALID FOR MON AND TUE...
WINTER WEATHER EVENT COMING TONIGHT INTO TUESDAY...WITH STRONG
COLD FRONTAL PASSAGE LATER TONIGHT. MUST CONTINUE TO STRESS GREAT
UNCERTAINTY IN THE DETAILS.
THERE ARE TWO PHASES WITH THIS EVENT. PHASE ONE INVOLVES
FRONTOGENETIC PCPN AS PACIFIC SHORTWAVE INTERACTS WITH CANADIAN
COLD FRONT...BEGINNING LATER THIS EVENING AND LASTING INTO
MONDAY. THIS WILL NOT BE AN UPSLOPE EVENT AS PCPN WILL BE DRIVEN
AT THE MID LEVELS...WITH BEST FORCING ACROSS OUR NORTH. TREMENDOUS
MODEL DIFFERENCES EXIST HERE...WITH NAM AND RAP KEEPING STRONGER
FRONTOGENESIS TO OUR NORTH...AND THE GFS/EC WRAPPING PCPN FURTHER
SOUTH AS MID LEVEL BAROCLINICITY DOES LIKEWISE. TOUGH FORECAST
HERE. BELIEVE ENERGY MOVING FROM SOUTHEAST OR INTO SOUTHERN ID IS
DYNAMIC AND FAR ENOUGH SOUTH TO ALLOW FOR A SOUTHERN PUSH OF
FORCING TO AN EXTENT GREATER THAN THE NAM/RAP...BUT NOT TO THE
EXTENT OF THE GFS WHICH SEEMS MUDDLED BY CONVECTIVE FEEDBACK.
INSTABILITY IS ANOTHER IMPORTANT FACTOR AS AIRMASS WILL BE FAIRLY
UNSTABLE THROUGH THE NIGHT...AGAIN SEE CONVECTIVE ACTIVITY
UPSTREAM NOW. SO...HAVE ISSUED WINTER WX ADVISORIES ACROSS OUR
NORTH FROM WHEATLAND TO FALLON COUNTIES...NORTH OF BILLINGS BUT
INCLUDING HIGHWAY 12 AND A PORTION OF I-94. GUSTY NORTH WINDS WITH
THE COLD ADVECTION WILL PRODUCE BLOWING SNOW ALONG WITH THE
ACCUMULATION...WHICH SHOULD GENERALLY RANGE FROM 1 TO 3 INCHES...
WITH MORE NORTH OF OUR CWA.
AS FOR THE CITY OF BILLINGS...MAYBE A LITTLE ACCUMULATION AFTER
MIDNIGHT BUT FEEL BRUNT OF PCPN WILL REMAIN NORTH...THOUGH WILL
SEE SCATTERED PREFRONTAL RAIN SHOWERS AND ISOLATED TSTMS THIS
EVENING. EXPECT UPSLOPE SNOW SHOWERS WITH LESS THAN AN INCH ON
MONDAY IN THE METRO AREA...WITH GUSTY WINDS AND A GENERALLY COLD
DAY.
AS A SIDE NOTE...IF MID LEVELS STAY DRY FROM BILLINGS SOUTH
TONIGHT...COULD BE SOME LIGHT FREEZING DRIZZLE ONCE TEMPS FALL
BELOW FREEZING AND LOW LEVELS MOISTEN WITH UPSLOPE NE WINDS
DEVELOPING. WILL NEED TO KEEP WATCH OF THIS.
PHASE TWO WILL BE INFLUENCED BY THE EVOLUTION OF PHASE ONE. THIS
WILL INVOLVE DEEP CENTRAL ROCKIES CLOSED LOW AS WE WILL BE NEAR
ITS NORTHERN EXTENT. A SOUTHERN PUSH OF FRONTOGENESIS TONIGHT
WOULD LIKELY RESULT IN A MORE SOUTHERN TRACK OF THE UPPER
LOW...WITH OUR AREA MORE INFLUENCED BY WEAKER/DRY NORTHERN TROF
CURRENTLY IN SOUTHERN CANADA. IF STRONGER FORCING STAYS NORTH
TONIGHT THAN WE COULD EXPECT A MORE NORTHWARD TRACK OF THE UPPER
LOW...AND STRONGER DIFFLUENCE OVER US...AND BETTER SNOW POTENTIAL
FOR OUR SOUTHERN UPSLOPE AREAS AND SOUTHEAST MT...AS THE ECMWF HAS
BEEN CONSISTENT IN SUGGESTING. LATEST GFS KEEPS THE LOW ENTIRELY
TO OUR SOUTH...SO PLENTY OF UNCERTAINTY HERE AS WELL. WILL KEEP A
MIDDLE GROUND...WITH LIKELY POPS AND SOME ACCUMULATION ACROSS OUR
SOUTH MONDAY NIGHT AND TUESDAY. WITH A MORE NORTHERN TRACK...DEEP
DENDRITIC LAYER AND UPSLOPE FLOW COULD BRING A SIGNIFICANT SNOW
EVENT TO SUCH PLACES AS SHERIDAN...BROADUS AND ALZADA...WITH PCPN
LASTING INTO TUESDAY NIGHT. OR WITH THE SOUTHERN TRACK THESE
AREAS WOULD RECEIVE VERY LITTLE PCPN WITH AN END BY TUESDAY.
PLEASE MONITOR THE FORECAST OVER THE NEXT DAY AS ADJUSTMENTS WILL
LIKELY BE NEEDED.
AS FOR THE CITY OF BILLINGS...IT DOES NOT LOOK AS IF WE WILL
RECEIVE MUCH SNOWFALL WITH PHASE TWO EITHER...AND POSSIBLY NONE.
AGAIN THIS WILL DEPEND ON EXACT TRACK OF THE UPPER LOW.
CANADIAN AIRMASS IS QUITE COLD AND TEMPS WILL BE WELL BELOW NORMAL
THE NEXT TWO DAYS. HAVE DROPPED EXPECTED TEMPS A BIT MORE. RECORD
LOWS COULD BE CHALLENGED AT BILLINGS AND MILES CITY MONDAY NIGHT.
JKL
.LONG TERM...VALID FOR WED...THU...FRI...SAT...SUN...
CONSENSUS OF THE EXTENDED IS FOR SLIGHTLY BELOW SEASONAL AVERAGES
FOR TEMPERATURES AND AN UNSETTLED NATURE FOR POPS. THE ONLY REAL
DRY DAY APPEARS TO BE WEDNESDAY AS A SHORT LIVED MESO RIDGE MOVES
IN. A DEEP UPPER TROUGH OVER THE GULF OF ALASKA AND THE NORTHERN
TERRITORIES DROPS SOUTHWARD TOWARD THE PACIFIC NORTHWEST THIS
WEEKEND. THIS PROCESS WILL CAUSE FALLING HEIGHTS FOR A RELATIVELY
UNSTABLE ATMOSPHERE WITH MOISTURE AND SHORTWAVES SHOOTING ACROSS
THE FORECAST AREA. IMPOSSIBLE AT THIS POINT TO PIN POINT THE BEST
DAY FOR POP CHANCES AS EXACT PLACEMENT OF APPROACHING WAVES WILL
BE CRITICAL FOR ASCENT. A BROAD BRUSHED SLIGHT CHANCE TO CHANCE
POPS SEEMS THE BEST WAY TO GO. THE WARMEST DAY SHOULD BE WEDNESDAY
WITH LESS CLOUD COVER ALLOWING A HIGH SUN ANGLE TO WORK. TWH
&&
.AVIATION...
SCATTERED SHOWERS WILL PUSH ACROSS THE AREA LATE THIS AFTERNOON
AND THIS EVENING. SOME WIND GUSTS TO 30KTS WILL ACCOMPANY THE
SHOWERS WITH MAINLY LIGHT RAIN. A STRONG COLD FRONT WILL PUSH INTO
NORTHERN TERMINALS THIS EVENING AND INTO SOUTHERN TERMINALS
OVERNIGHT. THIS FRONT WILL SWITCH WINDS TO THE NORTH WITH GUSTS TO
30KTS. RAIN AND SNOW WILL DEVELOP MAINLY NORTH OF A LIVINGSTON TO
BILLINGS TO BAKER LINE THIS EVENING. THE PRECIPITATION WILL CHANGE
TO SNOW BY LATE EVENING AND CONTINUE OVERNIGHT WITH CONDITIONS
LOWERING TO IFR NORTH OF THIS LINE. LOW CLOUDS WILL SPREAD SOUTH
OVERNIGHT WITH CEILINGS LOWERING TO MVFR CATEGORIES. LIGHT
SNOW...AND POSSIBLY LIGHT FREEZING DRIZZLE...WILL ACCOMPANY THE
LOWERING CEILINGS. LOW CLOUDS...SNOW AND GUSTY NORTH WINDS WILL
CONTINUE THROUGH MONDAY MORNING. TWH
&&
.PRELIMINARY POINT TEMP/POPS...
MON TUE WED THU FRI SAT SUN
-----------------------------------------------------------
BIL 028/034 018/036 022/048 033/056 033/053 032/053 029/052
67/S 31/B 01/B 33/W 22/W 33/W 33/W
LVM 028/039 018/038 022/048 032/053 029/051 029/050 026/049
66/S 41/B 01/B 32/W 22/W 33/W 33/W
HDN 030/035 019/035 019/047 029/057 028/054 027/054 026/054
67/S 41/B 11/B 33/W 22/W 33/W 33/W
MLS 030/032 016/033 018/044 027/052 027/052 028/052 025/052
88/S 21/B 11/B 23/W 22/W 33/W 32/W
4BQ 033/036 017/031 016/041 024/052 024/051 026/051 024/051
57/S 63/S 21/B 23/W 22/W 33/W 33/W
BHK 030/031 015/029 015/038 022/045 027/046 026/046 021/046
78/S 42/S 11/B 23/W 22/W 23/W 32/W
SHR 032/037 020/031 015/043 026/054 027/051 027/052 024/051
28/S 75/S 21/B 23/W 22/W 23/W 33/W
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY IN EFFECT FROM 9 PM THIS EVENING TO
NOON MDT MONDAY FOR ZONES 28-29-42-63.
WINTER WEATHER ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO 6
PM MDT MONDAY FOR ZONES 31>33.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1232 PM CDT SUN APR 7 2013
.UPDATE...
ISSUED AT 1223 PM CDT SUN APR 7 2013
CLEARED THE FREEZING RAIN ADVISORY ALL BUT JAMES RIVER VALLEY.
UPDATE ISSUED AT 953 AM CDT SUN APR 7 2013
MAINLY CHANGES EARLY THIS MORNING...NOW GETTING SNOW FROM MINOT
AND EAST. THE PRECIPITATION HAS MOVED EAST OF WILLISTON AND
STANLEY. ALSO WARMING TEMPERATURES SOUTH CENTRAL KEEPING THE
PRECIPITATION AS RAIN. CANCELLED THE FREEZING RAIN ADVISORY FOR ALL
BUT MCLEAN COUNTY THROUGH NOON...AND EAST THROUGH HARVEY AND SOUTH
THROUGH THE JAMES RIVER VALLEY THROUGH 7 PM.
UPDATE ISSUED AT 708 AM CDT SUN APR 7 2013
UPDATE THIS MORNING MAINLY FOR TEMPERATURES. LOW PRESSURE OVER
EASTERN MONTANA WITH HIGH PRESSURE OVER EASTERN NORTH DAKOTA
EARLY THIS MORNING WITH A SOUTHEAST FLOW OVER WESTERN NORTH DAKOTA
AND LIGHT WINDS IN THE CENTRAL. EXTENSIVE MVFR-IFR STRATUS ACROSS
ALL OF WESTERN AND CENTRAL NORTH DAKOTA. THIS HAS KEPT
TEMPERATURES FROM FALLING AS FAR AS FORECAST...AND DO NOT EXPECT
TEMPERATURES TO DROP MUCH MORE THIS MORNING. THUS RAISED EARLY
MORNING TEMPERATURES IN THE EAST FROM THE LOW TO MID 20S INTO THE
UPPER 20S. BAND OF PRECIPITATION IS MOVING THROUGH THE WEST AND
INTO CENTRAL NORTH DAKOTA. REPORT OF SOME MIXED PRECIPITATION AT
WILLISTON AND A LITTLE UNDER AN INCH OF SNOW. THE WARMER THAN
EXPECTED TEMPERATURES COMBINED WITH ROAD SURFACE TEMPERATURES AT
OR ABOVE FREEZING IN MANY AREAS...SHOULD HELP TO DIMINISH THE
EFFECTS OF ANY FREEZING RAIN. HOWEVER...EXPECT SECONDARY ROADS...
SIDEWALKS AND PARKING LOTS MAY YET BECOME SLIPPERY. WILL HOLD OFF
ON ANY UPDATES TO THE CURRENT FREEZING RAIN ADVISORY AND SEE IF WE
CAN GET A FEW MORE REPORTS AFTER SUNRISE.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 329 AM CDT SUN APR 7 2013
THE MAIN FORECAST CHALLENGES FOR THE SHORT TERM INCLUDE
PRECIPITATION TIMING AND TYPE. THE 00Z MODEL SUITE IS IN
AGREEMENT...THUS HAVE UTILIZED A BLEND OF GUIDANCE.
LATEST RADAR IMAGERY AT 330 AM CDT IS SHOWING SOME SCATTERED LIGHT
RETURNS ACROSS THE SOUTHWEST....AND MORE WIDESPREAD LIGHT RETURNS
OVER NORTHEASTERN MONTANA ASSOCIATED WITH A WEAK UPPER LEVEL IMPULSE.
HOWEVER...SURFACE OBSERVATIONS HAVE NOT REFLECTED PRECIPITATION
REACHING THE GROUND OVER THE SOUTHWEST. THE 05/06Z RAP SOLUTIONS DO
NOT REFLECT THE LIGHT PRECIPITATION OVER THE NORTHEAST AT THIS
TIME...BUT IT DOES PAINT SOME LIGHT PRECIPITATION ACROSS THE
SOUTHWEST. THE 00Z GFS/ECMWF/NAM ALL SHOW LIGHT PRECIPITATION OVER
NORTHEAST MONTANA AT THIS TIME...AND THUS HAVE UTILIZED A BLEND OF
THE 00Z MODEL GUIDANCE IN ADDITION TO THE 05/06Z RAP GUIDANCE.
PRECIPITATION WILL CONTINUE TO SPREAD EAST WITH TIME...FILLING IN
OVER THE WEST OVER THE NEXT FEW HOURS...AND THEN OVER THE CENTRAL
BY LATER THIS MORNING...AS THE UPPER LEVEL IMPULSE MOVES OVER THE
AREA.
LATEST OBSERVATIONS AT 400 AM CDT SHOW THAT TEMPERATURES SOUTH AND
WEST OF THE MISSOURI RIVER REMAIN ABOVE FREEZING...WHILE NORTH AND
EAST...TEMPERATURES ARE IN THE MID TO UPPER 20S. FOLLOWING THE
COLD FRONTAL PASSAGE YESTERDAY...COLD AIR ADVECTION ALOFT IS
UNDERWAY...WITH A SHALLOW WARM LAYER JUST ABOVE THE SURFACE.
PRECIPITATION WILL START AS FREEZING RAIN...WITH SOME SNOW AND
SLEET MIXED IN ACROSS THE WEST...BUT AS TEMPERATURES WARM ACROSS
THE SOUTHWEST AND SOUTH CENTRAL...A TRANSITION TO RAIN WILL OCCUR.
FOR LOCATIONS ACROSS THE NORTH...WHERE TEMPERATURES ARE CURRENTLY
SUBFREEZING...PRECIPITATION WILL START AS SNOW...BUT AS
TEMPERATURES WARM NEAR THE SURFACE WITH COLDER AIR PRESENT ALOFT...A
TRANSITION TO FREEZING RAIN AND THEN TO A MIX OF FREEZING
RAIN...SLEET...AND SNOW AFTER MIDNIGHT.
EVEN THOUGH THE FORECAST PROCESS HAS LED TO INCREASED MIXED
PRECIPITATION (SNOW...SLEET AND FREEZING RAIN) AND DECREASED
COVERAGE OF FREEZING RAIN...HAVE DECIDED TO CONTINUE THE FREEZING RAIN
ADVISORY AT THIS TIME. WILL CONTINUE TO MONITOR AND MAKE CHANGES
IF WARRANTED.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 329 AM CDT SUN APR 7 2013
THE MAIN FORECAST PROBLEM IN THE EXTENDED PERIOD WILL MONDAY THROUGH
MONDAY NIGHT...ACTUALLY BEGINNING LATE SUNDAY NIGHT IN THE FAR WEST.
WILL LEAN MORE TOWARD A ECMWF/GEM SOLUTION OVER THE GFS/NAM FOR QPF
DETAILS.
ALTHOUGH THE STRONG UPPER LEVEL SYSTEM IN THE WEST DIVES SOUTH ON
MONDAY...THERE IS STILL A PIECE OF UPPER LEVEL ENERGY THAT MAKES IT
INTO THE NORTHERN PLAINS. DETERMINISTIC MODELS ARE IN REASONABLE
AGREEMENT IN BRINGING THIS INTO THE LOCAL AREA. ALTHOUGH RATHER
SIGNIFICANT DIFFERENCES IN THE RESULTING PLACEMENT OF THE QPF AS THE
WAVE INTERACT WITH A TIGHTENING BAROCLINIC ZONE ACROSS WESTERN AND
CENTRAL NORTH DAKOTA. THE NAM/GFS ARE FARTHER NORTH WITH THE QPF
THAN THE GEM/ECMWF...ALTHOUGH THE 00 UTC SUNDAY ECMWF HAS COME A
LITTLE FARTHER NORTH THAN PREVIOUS RUNS. LOOKING AT GFS BUFKIT
SOUNDINGS...THERE DOES APPEAR TO BE A 3 TO 6 HOUR PERIOD WITH STRONG
OMEGA OVER WITHIN THE SNOW GROWTH ZONE IN THE WEST CENTRAL AND
SOUTHWEST...WHICH SHOULD YIELD SOME DECENT SNOW AMOUNTS. THIS AREA
EXTENDS EAST ACROSS CENTRAL NORTH DAKOTA DURING THE DAY MONDAY BUT
STRONG HIGH PRESSURE DROPPING SOUTH FROM CANADA WILL INHIBIT FG
FORCING LATER IN THE DAY. THIS SHOULD REDUCE SNOW AMOUNTS AS THE
WAVE MOVES EASTWARD INTO CENTRAL AND EASTERN NORTH DAKOTA.
A COMBINATION OF HPC SNOW AMOUNTS WITH MODEL QPF YIELDS 3 TO 5
INCHES OF SNOW OVER MUCH OF WEST CENTRAL AND SOUTHWEST NORTH
DAKOTA...WITH 2 TO 3 INCHES EXTENDING EAST INTO GRANT AND MORTON
COUNTIES. SNOW TOTALS TAPER TO AN INCH OR TWO EAST OF THE MISSOURI
RIVER. THE NORTHERN EXTENT OF THE HEAVIER SNOW REMAINS ALONG AND
SOUTH OF LAKE SAKAKAWEA...WEST OF THE MISSOURI...THEN ALONG AND
SOUTH OF THE I94 CORRIDOR EAST OF THE MISSOURI. ALTHOUGH SIGNIFICANT
DIFFERENCES STILL REMAIN...FEEL CONFIDENT ENOUGH THAT A WINTER
WEATHER ADVISORY IS WARRANTED OVER THE SOUTHWEST AND WEST CENTRAL.
CONFIDENCE WANES AS YOU GO EAST...BUT WILL EXTEND THE ADVISORY
EAST TO COVER MOST OF THE AREA WEST OF THE MISSOURI AND SOUTH OF THE
LAKE.
AT THIS TIME IT APPEARS THAT THERE SHOULD BE A QUICK TRANSITION FROM
RAIN TO SNOW AS COLD AIR RUSHES SOUTH LATE SUNDAY NIGHT. HOWEVER...A
PERIOD OF MIXED PRECIPITATION CANNOT BE RULED OUT BEFORE THE COLD
AIR IS FIRMLY ENTRENCHED OVER THE AREA BY MONDAY MORNING. AS THE
CANADIAN HIGH DROPS SOUTH WE SHOULD SEE A NICE ISALLOBARIC COMPONENT
MOVE ACROSS THE WEST AND SOUTH CENTRAL ON MONDAY RESULTING IN
SUSTAINED WINDS OF 15 TO 20 MPH AND GUST OF 25 TO 30 MPH. ALTHOUGH
THERE IS NO LOOSE SNOW...WINDS WILL BE STRONG ENOUGH FOR SOME
BLOWING SNOW AS IT FALLS. THUS WILL MAKE THE ADVISORY FOR SNOW AND
BLOWING SNOW...LASTING FROM LATE SUNDAY NIGHT THROUGH LATE MONDAY
NIGHT.
AS THE MAIN UPPER LOW MOVES ONTO THE PLAINS ON TUESDAY...COLD HIGH
PRESSURE OVER SASKATCHEWAN INTO NORTH DAKOTA SHOULD KEEP THE
NORTHERN EXTEND OF THE SYSTEM RIGHT ALONG THE SOUTH DAKOTA BORDER
WITH ANY SIGNIFICANT PRECIPITATION REMAINING SOUTH OF THE STATE.
THEN AS THE SYSTEM BEGINS TO EJECT NORTHEAST TUESDAY NIGHT THE
PRECIPITATION SHIELD TRIES TO PUSH A BIT FARTHER NORTH AND MAY CLIP
THE FAR SOUTH AND SOUTHEAST COUNTIES WITH LIGHT SNOW. AT THIS TIME
WE ARE KEEPING HIGH CHANCE POPS ALONG THE SOUTH DAKOTA
BORDER...TAPERING TO SLIGHT CHANCE POPS AROUND INTERSTATE 94. THE
NORTHERN HALF OF THE CWA IS EXPECTED TO REMAIN DRY TUESDAY AND
TUESDAY NIGHT. TEMPERATURES DURING THIS PERIOD...MONDAY THROUGH
WEDNESDAY...WILL BE BELOW NORMAL WITH 20S NORTH TO 30S SOUTH. WE DO
SEE SOME SLIGHT WARMING BY AROUND THURSDAY AS THE SYSTEM EXITS TO
OUR EAST...BUT A PROGRESSIVE NORTHWEST FLOW WILL BRING A SERIES OF
UPPER LEVEL WAVES INTO THE AREA LATE IN THE WEEK KEEPING OUR WEATHER
UNSETTLED WITH TEMPERATURES NEAR OR BELOW NORMAL.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY MORNING) ISSUED
AT 1225 PM CDT SUN APR 7 2013
A WARM FRONT EXTENDED ACROSS SOUTHWEST NORTH DAKOTA. MAIN HAZARD
TO AVIATION WILL BE FREEZING RAIN/SLEET AT KJMS THROUGH 21Z.
OTHERWISE MVFR FROM KMOT-KJMS. VFR WILL EXTEND FROM KISN-KDIK-
KBIS. ANOTHER ROUND OF WINTER WEATHER WILL MOVE INTO WESTERN NORTH
DAKOTA SUNDAY NIGHT AND MONDAY. MAIN IMPACTS TO AVIATION WILL
BE IFR CONDITIONS SPREADING INTO KDIK AFTER 09Z. MVFR RETURNING TO
KISN-KMOT-KBIS-KJMS AFTER 12Z.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 1 AM CDT /MIDNIGHT MDT/ MONDAY TO 1
AM CDT /MIDNIGHT MDT/ TUESDAY FOR NDZ017>020-031>034-040>044.
FREEZING RAIN ADVISORY UNTIL 7 PM CDT THIS EVENING FOR NDZ022-
023-037-048-051.
&&
$$
UPDATE...WAA
SHORT TERM...LTH
LONG TERM...TWH
AVIATION...WAA
AREA FORECAST DISCUSSION
NWS TULSA OK
337 PM CDT SUN APR 7 2013
.DISCUSSION...
CURRENT SURFACE ANALYSIS SHOWS A SUBTLE PRESSURE TROUGH THAT LIES
WEST-EAST ALONG THE KS BORDER. MEANWHILE...MOISTURE CONTINUES TO
SLOWLY INCREASE AND SURGE NORTH. AN ISOLATED SUPERCELL DEVELOPED
ON THE NORTH SIDE OF THIS FEATURE AND CONTINUES EAST ACROSS KS.
THERE IS POTENTIAL LATER THIS AFTERNOON FOR AN ISOLATED STORM TO
DEVELOP OVER FAR NW OK/SW-S CNTRL KS AND TRACK EAST TOWARD NE OK.
THE MOST RECENT AVAILABLE RUN OF THE HRRR HAS BACKED OFF ON THIS
POSSIBILITY BUT IT IS STILL WORTH WATCHING. ANY UPDRAFT THAT CAN
SUSTAIN ITSELF WILL LIKELY ROTATE...GIVEN ~50 KTS OF WESTERLY DEEP
LAYER SHEAR. THE RIGHT MOVING BUNKERS SUPERCELL VECTOR HAS A
MOTION JUST NORTH OF DUE EAST AT 20 KTS. THIS HAS BACKED FROM
EARLIER TODAY...MOST LIKELY DUE TO STRENGTHENING WSW FLOW IN
ADVANCE OF AN IMPULSE OVER NM PER WV IMAGERY. SO THE BEST
POTENTIAL FOR SEVERE STORMS WILL BE NEAR THE KS BORDER AND MAINLY
WEST OF HIGHWAY 75 THROUGH THIS EVENING. VERY LARGE HAIL TO
BASEBALL SIZE IS CERTAINLY POSSIBLE...AND DUE TO STRENGTHENING
0-1KM SHEAR AN ISOLATED TORNADO OR TWO COULD ACCOMPANY A SUPERCELL
IF IT HAPPENED TO PAY US A VISIT THIS EVENING. LOOKS LIKE MORE
WIDESPREAD AND MAINLY ELEVATED STORMS WILL GET ALONG AND NORTH OF
SURFACE TROUGH TOWARD 06Z AS STRENGTHENING LLJ FOCUSES ISENTROPIC
LIFT. THERE IS SOME UNCERTAINTY IN HOW FAR SOUTH TO PUT RAIN
CHANCES...AS OUR LOCAL MODEL DEVELOPS STORMS A BIT FARTHER SOUTH.
FOR NOW WILL HEDGE AND PUT SLIGHT CHCS DOWN TO NEAR I-40.
THE CAP STRENGTHENS ON MONDAY AND THE BOUNDARY TO OUR NORTH
CONSOLIDATES WITH A STRENGTHENING WARM FRONT NEAR THE KS/NEB
BORDER. CHANCES FOR ANY STORMS TOO LOW TO MENTION IN THE FORECAST.
IT IS A HIGHLY CONDITIONAL SETUP (PROBABLY THE BEST OF THE WEEK)...BUT
LOW PROB OF OCCURRENCE.
THE NEXT BIG CHALLENGE WILL BE LATE TUESDAY INTO WEDNESDAY. THE
DATA TODAY HAS NOT REALLY CHANGED MY FORECAST REASONING FROM
YESTERDAY MUCH AT ALL. MODEL SOUNDINGS STILL SHOW A DECENT CAP IN
THE WARM SECTOR TUESDAY...SO IT WILL BE DIFFICULT TO GET STORMS TO GO
WITH THE MAIN UPPER TROUGH STILL WELL WEST AND LACK OF ANY
FOCUSING BOUNDARIES IN OUR AREA. IF A STORM DOES GO IN THE WARM
SECTOR...IT WOULD LIKELY BE BAD...BUT ODDS ARE PRETTY LOW. THE
MOST LIKELY SCENARIO IS FRONTAL FORCING ALONG A SURGING COLD FRONT
WILL PROVIDE THE LIFT NEEDED FOR CONVECTION. HOWEVER...SINCE UPPER
TROUGH IS COMING OUT WITH A POSITIVE TILT...THE UPPER FLOW WILL BE
PARALLEL TO THE FRONT...THUS STORMS THAT DEVELOP WITH THE FRONT
WILL TEND TO BE UNDERCUT QUICKLY. THE ECMWF CONTINUES TO SHOW
ALMOST ALL QPF ON THE COOL SIDE OF THE FRONT...INDICATIVE OF THIS
VERY SCENARIO. I`M NOT SAYING THERE WILL NOT BE SEVERE
WEATHER...BUT THE TENDENCY FOR STORMS TO BE UNDERCUT WILL LIMIT
THE SEVERE POTENTIAL. POST-FRONTAL RAIN AND STORMS ARE FORECAST TO
CONTINUE THRU WEDNESDAY...TAPERING OFF BY THURSDAY MORNING.
TEMPS WILL COOL OFF BEHIND THE FRONT...AND WILL REMAIN THAT WAY
FOR THE LATTER HALF OF THE WEEK AND INTO THE FIRST PART OF THE
WEEKEND. A SUBTLE WAVE WILL PASS THRU THE PLAINS SATURDAY...WITH
THE MAIN EFFECT BEING MORE CLOUD COVER. ONCE THAT PASSES...UPPER
FLOW TRANSITIONS TO SW AND LEE SIDE LOW PRESSURE DEVELOPS OVER SW
KS/SE CO. SOUTHWEST WINDS WILL PREVAIL HERE AND TEMPS WILL REBOUND
QUICKLY BY NEXT SUNDAY.
LACY
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 61 75 62 75 / 30 10 10 30
FSM 59 74 62 77 / 10 10 10 20
MLC 61 74 63 75 / 10 0 10 20
BVO 60 76 61 74 / 30 10 10 30
FYV 57 71 60 73 / 30 10 10 20
BYV 57 71 59 73 / 30 10 10 20
MKO 59 75 62 74 / 20 10 10 20
MIO 60 74 61 75 / 40 10 10 20
F10 61 74 62 74 / 10 10 10 30
HHW 60 75 63 77 / 0 0 10 20
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&
$$
LONG TERM....30
AREA FORECAST DISCUSSION
NWS AMARILLO TX
1233 PM CDT SUN APR 7 2013
.AVIATION...
VFR CONDITIONS EXPECTED TO PREVAIL THROUGH THE NEXT 24 HOURS. THE
MAIN AVIATION CONCERNS WILL BE THE POTENTIAL FOR STORMS TO DEVELOP
NEAR KGUY AND WIND SHIFTS AT ALL TERMINALS. THE THREAT FOR STORMS AT
KGUY REMAINS TOO LOW TO MENTION IN PREVAILING AND IS BECOMING
INCREASINGLY LESS LIKELY GIVEN THE STRONG CAP ACROSS THE WESTERN
OKLAHOMA PANHANDLE. STORMS SHOULD REMAIN WELL AWAY FROM KAMA AND
KDHT. THERE AREA COUPLE OF WIND SHIFTS THROUGHOUT THE TAF BUT FOR THE
MOST PART WINDS WILL REMAIN LESS THAN 12 KTS.
&&
.PREV DISCUSSION... /ISSUED 1159 AM CDT SUN APR 7 2013/
UPDATE...
OVERALL...CHANCE OF STRONG TO SEVERE STORMS DEVELOPING STILL EXISTS
FOR THE EASTERN OKLAHOMA AND NORTHEASTERN TEXAS PANHANDLE BUT THESE
CHANCES ARE BECOMING LESS LIKELY.
STRONG CAPPING IS STILL EXPECTED TO PERSIST UNTIL 3 PM...WEAKEN
BETWEEN 3 PM TO 9 PM...AND THEN STRENGTHEN AGAIN AFTER 9 PM. AS SUCH
THE ADVERTISED 4 PM TO 9 PM TIME FRAME REMAINS VALID FOR ANY STRONG
TO SEVERE STORMS TO FORM. RECENT RUC HRRR AND TTU WRF RUNS HAVE
SHOWN A NORTH AND EAST SHIFT IN HIGHER MLCAPE VALUES FAVORING EAST
OF A DODGE CITY TO TX/OK STATE BORDER LINE. AS A RESULT THE NE TX
AND E OK PANHANDLE RANGES BETWEEN 500-1000 J/KG OF MLCAPE WITH THE
HIGHER VALUES IN THE EASTERN EXTREMES OF THE CWA. HOWEVER...SHORT
RANGE MODEL SURFACE DEWPOINTS REMAIN A FEW DEGREES TOO HIGH COMPARED
TO SURFACE OBSERVATIONS SO CAPE VALUES...SPECIFICALLY SURFACE BASED
VALUES...MAY BE A LITTLE OVERDONE. SO STORMS MAY INITIATE OVER THE
EXTREME EASTERN TX/OK PANHANDLE THIS AFTERNOON AND EVENING BUT THE
LIKELIHOOD OF THESE STORMS BECOMING STRONG TO SEVERE IN OUR FORECAST
AREA HAS DECREASED.
PREV DISCUSSION... /ISSUED 615 AM CDT SUN APR 7 2013/
AVIATION...
FOR THE 12Z TAFS...SFC DRYLINE AND RESIDUAL FRONTAL BOUNDARY ARE
EXPECTED TO MOVE INTO ERN SECTIONS OF FCST AREA TODAY. IF ANY
THUNDERSTORMS DEVELOP LATE THIS AFTERNOON AND EVENING...THEY SHOULD
REMAIN ISOLD AT BEST AND SHOULD NOT AFFECT KDHT OR KAMA. LOW
CONFIDENCE AS TO WHETHER OR NOT ANY STORMS WILL AFFECT KGUY SO HAVE
OPTED TO LEAVE OUT OF THIS TAF FCST ISSUANCE. OTHERWISE...PERIODS OF
MID AND HIGH LEVEL CLOUDS ANTICIPATED THROUGH 12Z MONDAY.
ANDRADE
PREV DISCUSSION... /ISSUED 331 AM CDT SUN APR 7 2013/
DISCUSSION...
AN ACTIVE...ALBEIT MOSTLY DRY...WEATHER PATTERN IS ON TAP FOR THE
REGION FOR THE NEXT WEEK.
TODAY AND TONIGHT...THE FOCUS IS ON THE POTENTIAL FOR SEVERE
THUNDERSTORMS LATE THIS AFTERNOON INTO THIS EVENING OVER THE OKLAHOMA
AND NORTHERN AND EASTERN TEXAS PANHANDLES. THE BIGGEST QUESTION IS
IF STORMS WILL EVEN DEVELOP. SURFACE AND LOW LEVEL CONFLUENCE ALONG A
WARM FRONT AND DRYLINE WILL NEED TO BE JUXTAPOSED WITH MEAGER MID AND
UPPER LEVEL SUPPORT AS A SMALL SHORTWAVE TROUGH SLIDES E OVER THE OK
PANHANDLE LATE TODAY. THIS IS FAR FROM A SURE THING AS MANY OF THE
SHORTER RANGE MODELS SHOW THE CENTER OF THE SURFACE LOW IN THE SW TX
PANHANDLE...WITH THE FRONT AND DRYLINE FEATURES WELL SOUTH OF THE
EXPECTED TRACK OF THE MID AN UPPER LEVEL TROUGH. IF THIS IS THE
CASE...AM NOT CONVINCED THAT THE LOW LEVEL CONFLUENCE IS ENOUGH TO
OVERCOME THE STRONG CAP. ADDITIONALLY...STILL CONCERNED THAT MODELS
ARE TOO AGGRESSIVE WITH LOW LEVEL MOISTURE RETURN. AT 08Z...UPSTREAM
OBS SHOW DEWPOINT TEMPERATURES GENERALLY IN THE40S AND 50S...BUT THE
NAM AND OTHER HIGH RESOLUTION MODELS SHOW A SURGE OF 60 OR HIGHER DEW
POINT TEMPERATURES BY 21Z. CAN/T SEE HOW WE WOULD HAVE THAT MUCH
MOISTURE ADVECTION IN SUCH A SHORT PERIOD OF TIME. HOWEVER IF STORMS
CAN DEVELOP...THERE IS A RISK THAT THEY WILL BECOME SEVERE. AS FOR
THE SEVERE THREATS...
HAIL SHOULD BE THE MAIN THREAT. MODEL SOUNDINGS SHOW ML CAPE VALUES
NEAR OR ABOVE 1000 J/KG. MUCH OF THAT IS IN THE HAIL GROWTH REGION.
IN ADDITION...BULK SHEAR VALUES...WHILE NOT AS HIGH AS WE/VE SEEN
WITH SOME OF THE SEVERE EVENTS LATELY...SHOULD STILL BE NEAR 40
KT...PLENTY ENOUGH TO SUPPORT SUSTAINED UPDRAFTS.
WIND...FOR A CHANGE THE WIND THREAT...WHILE NOT ZERO...IS LOWER
THAN THE HAIL THREAT. THE LOW AND MID LEVEL JETS SHOULD BE WELL EAST
OF THE REGION. THUS ANY STRONG WINDS WOULD EITHER HAVE TO BE MIXED
DOWN FROM THE UPPER LEVELS...OR WOULD HAVE TO SEE A DOWNBURST
ENHANCED BY PRECIPITATION LOADING.
TORNADO...THE TORNADO THREAT IS MINIMAL. THE MAIN REASONS IT IS SO
LOW IS MINIMAL HELICITY VALUES...HIGH LCL HEIGHTS...AND MODEST BULK
SHEAR VALUES...AND MOSTLY SPEED SHEAR AT THAT. HOWEVER...IT SHOULD BE
NOTED THAT THERE COULD BE SOME ENHANCED DIRECTIONAL SHEAR ALONG THE
BOUNDARIES BUT GIVEN THE WEST TO EAST STORM MOTIONS...DO NOT EXPECT
STORMS TO REMAIN CONNECTED TO EITHER THE FRONT OR DRY LINE FOR VERY
LONG.
FLOODING...FLOODING THREAT IS ALSO MINIMAL. THOUGH STORM MOTIONS WILL
BE RELATIVELY LOW...GENERALLY 15KT OR LESS...PRECIPITABLE WATER
VALUES ARE ONLY EXPECTED TO BE SLIGHTLY ABOVE NORMAL. IN
ADDITION...STORM MOTIONS AND BOUNDARY POSITIONS ARE NOT FAVORABLE FOR
TRAINING...AND GIVEN LIMITED COVERAGE DO NOT EXPECT MULTIPLE STORMS
TO MOVE OVER THE SAME LOCATIONS.
MONDAY...STILL LOOKING AT A WINDY DAY MAINLY DU TO INCREASING MID AND
UPPER LEVEL HEIGHT GRADIENTS AS THE MAIN TROUGH SLIDES INTO THE FOUR
CORNERS REGION. A COMBINATION OF A THICK CIRRUS DECK LIMITING
MIXING...AND A LATE DEVELOPMENT OF THE TIGHTEST HEIGHT AND PRESSURE
GRADIENTS WILL MEAN THAT WHILE IT WILL BE WINDY...WE WILL LIKELY STAY
BELOW WIND ADVISORY CRITERIA.
TUESDAY...THE MAIN STORY ON THIS DAY WILL BE THE COLD FRONT. THE
BIGGEST SOURCE OF UNCERTAINTY IS THE TIMING OF THE FRONT. WITH THE
00Z RUNS...THERE WAS RATHER GOOD AGREEMENT ON THE TIMING OF THE
FRONT...ARRIVING IN AMA BETWEEN 21 AND 00Z...BUT RATHER POOR RUN TO
RUN CONSISTENCY...AS THIS IS A BIT FASTER THAN THE 12Z RUNS. SOME
THINGS OF NOTE WITH THIS FRONT...FIRST...MODELS SHOW LARGE PRESSURE
RISES...ALMOST UNBELIEVABLY LARGE PRESSURE RISES...BEHIND THE
FRONT. THIS SHOULD LEAD STRONG POST FRONTAL WINDS...POSSIBLY NEAR
WIND ADVISORY. SECOND...THOUGH THE MAIN MID AND UPPER LEVEL TROUGH IS
QUICKLY LIFTING NE AT THIS TIME...LEAVING THE PANHANDLES IN A PRIME
LOCATION FOR THE DRY SLOT...SOME MODELS...MOST NOTABLY THE
ECMWF...CONTINUE TO SHOW PRECIPITATION BEHIND THE FRONT. IF ANY
PRECIP CAN DEVELOP...EXPECT THAT IT WILL BE THE RESULT OF RATHER
SHALLOW ISENTROPIC LIFT. THUS...EXPECT ONLY VERY LIGHT...IF
ANY...PRECIP.
WEDNESDAY THROUGH SUNDAY...REGION SHOULD SEE A RETURN TO A MORE ZONAL
FLOW PATTERN. FIRST A LEE SIDE SURFACE TROUGH IS EXPECTED TO DEVELOP
BY THURSDAY BRINGING A QUICK WARMING TREND. THERE COULD BE A FEW
EMBEDDED UPPER LEVEL SHORTWAVE TROUGHS TOWARDS THE END OF THE
WEEK...BUT UNCERTAINTY IN TIMING AND TRACK IS VERY HIGH AT THIS TIME.
JOHNSON
FIRE WEATHER...
DESPITE RELATIVE HUMIDITY VALUES NEAR OR BELOW 15 PERCENT...DO NOT
EXPECT ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS DUE TO RELATIVELY
LIGHT WINDS. ON MONDAY...CRITICAL FIRE WEATHER CONDITIONS ARE
POSSIBLE OVER THE WESTERN TEXAS PANHANDLE AND ELEVATED FIRE WEATHER
CONDITIONS ARE POSSIBLE ACROSS MUCH OF THE REST OF THE PANHANDLES DUE
TO SOUTHWESTERLY WINDS OF 15 TO 25 MPH...AND RELATIVE HUMIDITY VALUES
BETWEEN 10 AND 20 PERCENT. A COLD FRONT IS EXPECTED ON
TUESDAY...BRINGING AN ABRUPT SHIFT TO STRONG NORTHERLY WINDS.
DEPENDING ON HOW LATE IN THE DAY IT ARRIVES...ELEVATED TO NEAR
CRITICAL FIRE WEATHER CONDITIONS MAY BE POSSIBLE ACROSS THE SOUTHERN
TEXAS PANHANDLE.
JOHNSON
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
OK...NONE.
&&
$$
14/09
AREA FORECAST DISCUSSION
NWS AMARILLO TX
1159 AM CDT SUN APR 7 2013
.UPDATE...
OVERALL...CHANCE OF STRONG TO SEVERE STORMS DEVELOPING STILL EXISTS
FOR THE EASTERN OKLAHOMA AND NORTHEASTERN TEXAS PANHANDLE BUT THESE
CHANCES ARE BECOMING LESS LIKELY.
STRONG CAPPING IS STILL EXPECTED TO PERSIST UNTIL 3 PM...WEAKEN
BETWEEN 3 PM TO 9 PM...AND THEN STRENGTHEN AGAIN AFTER 9 PM. AS SUCH
THE ADVERTISED 4 PM TO 9 PM TIME FRAME REMAINS VALID FOR ANY STRONG
TO SEVERE STORMS TO FORM. RECENT RUC HRRR AND TTU WRF RUNS HAVE
SHOWN A NORTH AND EAST SHIFT IN HIGHER MLCAPE VALUES FAVORING EAST
OF A DODGE CITY TO TX/OK STATE BORDER LINE. AS A RESULT THE NE TX
AND E OK PANHANDLE RANGES BETWEEN 500-1000 J/KG OF MLCAPE WITH THE
HIGHER VALUES IN THE EASTERN EXTREMES OF THE CWA. HOWEVER...SHORT
RANGE MODEL SURFACE DEWPOINTS REMAIN A FEW DEGREES TOO HIGH COMPARED
TO SURFACE OBSERVATIONS SO CAPE VALUES...SPECIFICALLY SURFACE BASED
VALUES...MAY BE A LITTLE OVERDONE. SO STORMS MAY INITIATE OVER THE
EXTREME EASTERN TX/OK PANHANDLE THIS AFTERNOON AND EVENING BUT THE
LIKELIHOOD OF THESE STORMS BECOMING STRONG TO SEVERE IN OUR FORECAST
AREA HAS DECREASED.
&&
.PREV DISCUSSION... /ISSUED 615 AM CDT SUN APR 7 2013/
AVIATION...
FOR THE 12Z TAFS...SFC DRYLINE AND RESIDUAL FRONTAL BOUNDARY ARE
EXPECTED TO MOVE INTO ERN SECTIONS OF FCST AREA TODAY. IF ANY
THUNDERSTORMS DEVELOP LATE THIS AFTERNOON AND EVENING...THEY SHOULD
REMAIN ISOLD AT BEST AND SHOULD NOT AFFECT KDHT OR KAMA. LOW
CONFIDENCE AS TO WHETHER OR NOT ANY STORMS WILL AFFECT KGUY SO HAVE
OPTED TO LEAVE OUT OF THIS TAF FCST ISSUANCE. OTHERWISE...PERIODS OF
MID AND HIGH LEVEL CLOUDS ANTICIPATED THROUGH 12Z MONDAY.
ANDRADE
PREV DISCUSSION... /ISSUED 331 AM CDT SUN APR 7 2013/
DISCUSSION...
AN ACTIVE...ALBEIT MOSTLY DRY...WEATHER PATTERN IS ON TAP FOR THE
REGION FOR THE NEXT WEEK.
TODAY AND TONIGHT...THE FOCUS IS ON THE POTENTIAL FOR SEVERE
THUNDERSTORMS LATE THIS AFTERNOON INTO THIS EVENING OVER THE OKLAHOMA
AND NORTHERN AND EASTERN TEXAS PANHANDLES. THE BIGGEST QUESTION IS
IF STORMS WILL EVEN DEVELOP. SURFACE AND LOW LEVEL CONFLUENCE ALONG A
WARM FRONT AND DRYLINE WILL NEED TO BE JUXTAPOSED WITH MEAGER MID AND
UPPER LEVEL SUPPORT AS A SMALL SHORTWAVE TROUGH SLIDES E OVER THE OK
PANHANDLE LATE TODAY. THIS IS FAR FROM A SURE THING AS MANY OF THE
SHORTER RANGE MODELS SHOW THE CENTER OF THE SURFACE LOW IN THE SW TX
PANHANDLE...WITH THE FRONT AND DRYLINE FEATURES WELL SOUTH OF THE
EXPECTED TRACK OF THE MID AN UPPER LEVEL TROUGH. IF THIS IS THE
CASE...AM NOT CONVINCED THAT THE LOW LEVEL CONFLUENCE IS ENOUGH TO
OVERCOME THE STRONG CAP. ADDITIONALLY...STILL CONCERNED THAT MODELS
ARE TOO AGGRESSIVE WITH LOW LEVEL MOISTURE RETURN. AT 08Z...UPSTREAM
OBS SHOW DEWPOINT TEMPERATURES GENERALLY IN THE40S AND 50S...BUT THE
NAM AND OTHER HIGH RESOLUTION MODELS SHOW A SURGE OF 60 OR HIGHER DEW
POINT TEMPERATURES BY 21Z. CAN/T SEE HOW WE WOULD HAVE THAT MUCH
MOISTURE ADVECTION IN SUCH A SHORT PERIOD OF TIME. HOWEVER IF STORMS
CAN DEVELOP...THERE IS A RISK THAT THEY WILL BECOME SEVERE. AS FOR
THE SEVERE THREATS...
HAIL SHOULD BE THE MAIN THREAT. MODEL SOUNDINGS SHOW ML CAPE VALUES
NEAR OR ABOVE 1000 J/KG. MUCH OF THAT IS IN THE HAIL GROWTH REGION.
IN ADDITION...BULK SHEAR VALUES...WHILE NOT AS HIGH AS WE/VE SEEN
WITH SOME OF THE SEVERE EVENTS LATELY...SHOULD STILL BE NEAR 40
KT...PLENTY ENOUGH TO SUPPORT SUSTAINED UPDRAFTS.
WIND...FOR A CHANGE THE WIND THREAT...WHILE NOT ZERO...IS LOWER
THAN THE HAIL THREAT. THE LOW AND MID LEVEL JETS SHOULD BE WELL EAST
OF THE REGION. THUS ANY STRONG WINDS WOULD EITHER HAVE TO BE MIXED
DOWN FROM THE UPPER LEVELS...OR WOULD HAVE TO SEE A DOWNBURST
ENHANCED BY PRECIPITATION LOADING.
TORNADO...THE TORNADO THREAT IS MINIMAL. THE MAIN REASONS IT IS SO
LOW IS MINIMAL HELICITY VALUES...HIGH LCL HEIGHTS...AND MODEST BULK
SHEAR VALUES...AND MOSTLY SPEED SHEAR AT THAT. HOWEVER...IT SHOULD BE
NOTED THAT THERE COULD BE SOME ENHANCED DIRECTIONAL SHEAR ALONG THE
BOUNDARIES BUT GIVEN THE WEST TO EAST STORM MOTIONS...DO NOT EXPECT
STORMS TO REMAIN CONNECTED TO EITHER THE FRONT OR DRY LINE FOR VERY
LONG.
FLOODING...FLOODING THREAT IS ALSO MINIMAL. THOUGH STORM MOTIONS WILL
BE RELATIVELY LOW...GENERALLY 15KT OR LESS...PRECIPITABLE WATER
VALUES ARE ONLY EXPECTED TO BE SLIGHTLY ABOVE NORMAL. IN
ADDITION...STORM MOTIONS AND BOUNDARY POSITIONS ARE NOT FAVORABLE FOR
TRAINING...AND GIVEN LIMITED COVERAGE DO NOT EXPECT MULTIPLE STORMS
TO MOVE OVER THE SAME LOCATIONS.
MONDAY...STILL LOOKING AT A WINDY DAY MAINLY DU TO INCREASING MID AND
UPPER LEVEL HEIGHT GRADIENTS AS THE MAIN TROUGH SLIDES INTO THE FOUR
CORNERS REGION. A COMBINATION OF A THICK CIRRUS DECK LIMITING
MIXING...AND A LATE DEVELOPMENT OF THE TIGHTEST HEIGHT AND PRESSURE
GRADIENTS WILL MEAN THAT WHILE IT WILL BE WINDY...WE WILL LIKELY STAY
BELOW WIND ADVISORY CRITERIA.
TUESDAY...THE MAIN STORY ON THIS DAY WILL BE THE COLD FRONT. THE
BIGGEST SOURCE OF UNCERTAINTY IS THE TIMING OF THE FRONT. WITH THE
00Z RUNS...THERE WAS RATHER GOOD AGREEMENT ON THE TIMING OF THE
FRONT...ARRIVING IN AMA BETWEEN 21 AND 00Z...BUT RATHER POOR RUN TO
RUN CONSISTENCY...AS THIS IS A BIT FASTER THAN THE 12Z RUNS. SOME
THINGS OF NOTE WITH THIS FRONT...FIRST...MODELS SHOW LARGE PRESSURE
RISES...ALMOST UNBELIEVABLY LARGE PRESSURE RISES...BEHIND THE
FRONT. THIS SHOULD LEAD STRONG POST FRONTAL WINDS...POSSIBLY NEAR
WIND ADVISORY. SECOND...THOUGH THE MAIN MID AND UPPER LEVEL TROUGH IS
QUICKLY LIFTING NE AT THIS TIME...LEAVING THE PANHANDLES IN A PRIME
LOCATION FOR THE DRY SLOT...SOME MODELS...MOST NOTABLY THE
ECMWF...CONTINUE TO SHOW PRECIPITATION BEHIND THE FRONT. IF ANY
PRECIP CAN DEVELOP...EXPECT THAT IT WILL BE THE RESULT OF RATHER
SHALLOW ISENTROPIC LIFT. THUS...EXPECT ONLY VERY LIGHT...IF
ANY...PRECIP.
WEDNESDAY THROUGH SUNDAY...REGION SHOULD SEE A RETURN TO A MORE ZONAL
FLOW PATTERN. FIRST A LEE SIDE SURFACE TROUGH IS EXPECTED TO DEVELOP
BY THURSDAY BRINGING A QUICK WARMING TREND. THERE COULD BE A FEW
EMBEDDED UPPER LEVEL SHORTWAVE TROUGHS TOWARDS THE END OF THE
WEEK...BUT UNCERTAINTY IN TIMING AND TRACK IS VERY HIGH AT THIS TIME.
JOHNSON
FIRE WEATHER...
DESPITE RELATIVE HUMIDITY VALUES NEAR OR BELOW 15 PERCENT...DO NOT
EXPECT ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS DUE TO RELATIVELY
LIGHT WINDS. ON MONDAY...CRITICAL FIRE WEATHER CONDITIONS ARE
POSSIBLE OVER THE WESTERN TEXAS PANHANDLE AND ELEVATED FIRE WEATHER
CONDITIONS ARE POSSIBLE ACROSS MUCH OF THE REST OF THE PANHANDLES DUE
TO SOUTHWESTERLY WINDS OF 15 TO 25 MPH...AND RELATIVE HUMIDITY VALUES
BETWEEN 10 AND 20 PERCENT. A COLD FRONT IS EXPECTED ON
TUESDAY...BRINGING AN ABRUPT SHIFT TO STRONG NORTHERLY WINDS.
DEPENDING ON HOW LATE IN THE DAY IT ARRIVES...ELEVATED TO NEAR
CRITICAL FIRE WEATHER CONDITIONS MAY BE POSSIBLE ACROSS THE SOUTHERN
TEXAS PANHANDLE.
JOHNSON
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
OK...NONE.
&&
$$
14/09
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1226 PM CDT SUN APR 7 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 342 AM CDT SUN APR 7 2013
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT
ANALYSIS SHOWED UPPER TROUGHING APPROACHING THE PACIFIC
NORTHWEST...WEAK RIDGING OVER THE NORTHERN U.S. ROCKIES INTO THE
DAKOTAS...AND A SHORTWAVE TROUGH OVER EASTERN WISCONSIN. ALSO OF
NOTE ON WATER VAPOR WERE A PAIR OF SHORTWAVES MOVING THROUGH THE
WEAK RIDGING...ONE IN SOUTH CENTRAL WYOMING AND THE OTHER IN
NORTHWEST COLORADO. THE FORECAST AREA LIES IN SUBSIDENCE IN THE
WAKE OF THE EASTERN WISCONSIN SHORTWAVE TROUGH...SEEN AS AN
INVERSION BETWEEN 775 AND 850MB ON THE 00Z MPX SOUNDING. THIS
INVERSION WAS ALSO SATURATED... REFLECTED TOO BY PLENTY OF STRATUS
CLOUDS ON 11-3.9UM IMAGERY FROM THE EASTERN DAKOTAS INTO THE
FORECAST AREA. COOLER AIR HAS BEEN FILTERING IN BEHIND THE
SHORTWAVE AS WELL WITH 850MB TEMPS NOW DOWN TO +2 TO -3C ACROSS
THE FORECAST AREA PER RAP ANALYSIS...COLDEST OVER CENTRAL
WISCONSIN. AT THE SURFACE...HIGH PRESSURE WAS SEEN DROPPING SOUTH
INTO WESTERN MINNESOTA...IN THE WAKE OF LOW PRESSURE OVER NORTHERN
LAKE MICHIGAN AND ITS COLD FRONT WHICH EXTENDS SOUTHWEST TO KANSAS
CITY.
A PATTERN CHANGE IS FORECAST TO OCCUR ALOFT DURING THE NEXT 24 HOURS
AS THE UPPER TROUGH SEEN OFF THE PACIFIC NORTHWEST SHARPLY DIGS
SOUTH INTO CALIFORNIA AND NEVADA. IN RESPONSE...RIDGING WILL BUILD
DOWNSTREAM...ADJUSTING THE UPPER LEVEL FLOW TO SOUTHWESTERLY OVER
THE FORECAST AREA. THIS MEANS THAT THE RECENT LOW LEVEL COLD
ADVECTION WILL COME TO AN END SHORTLY...WITH WARM ADVECTION PROGGED
TO BEGIN BETWEEN 12-18Z TODAY AND CONTINUE THROUGH TONIGHT. IN
ADDITION...MODELS HAVE BEEN CONSISTENT IN SHOWING THE PAIR OF
SHORTWAVES SEEN IN WYOMING AND COLORADO TO AFFECT THE FORECAST AREA
LATE TONIGHT AS THEY RIDE THROUGH THE SOUTHWEST FLOW.
THE FIRST TWO ISSUES FOR THE SHORT TERM PERIOD ARE THE CLOUDS AND
HIGH TEMPERATURES TODAY. THE PRESENT STRATUS DECK DOES HAVE SOME
HOLES IN IT ON ITS SOUTHERN SIDE. THESE HOLES SHOULD EXPAND THROUGH
THE MORNING AS DIURNAL MIXING COMMENCES. 07.00Z NAM LOW LEVEL RH
FIELDS...WHICH GENERALLY TEND PESSIMISTIC...ALSO SUGGEST THAT THE
STRATUS DECK WILL MOSTLY MIX OUT BY 18Z SOUTH OF US HIGHWAY 10.
LATER IN THE AFTERNOON...SAY 21Z AND AFTER...MID AND HIGH CLOUDS
CURRENTLY SPREADING INTO THE PLAINS STATES ARE PROGGED TO MOVE INTO
THE FORECAST AREA. THUS WE SHOULD SEE AT LEAST A FEW HOURS OF MOSTLY
SUNNY SKIES TODAY. WITH 850MB TEMPS CLIMBING TO 0C NORTH AND 6C
SOUTH BY 18Z...ANTICIPATING THAT MOST LOCATIONS MINUS NORTH OF
HIGHWAY 10 WHERE MORE CLOUDS AND SNOW EXIST WILL CLIMB INTO THE 50S.
WARMEST TEMPERATURES...APPROACHING 60...ARE EXPECTED IN THE FAR
SOUTH.
THE NEXT ISSUE FOR THE SHORT TERM PERIOD IS THE POTENTIAL FOR
PRECIPITATION VERY LATE THIS AFTERNOON INTO TONIGHT...DUE TO THE
WARM ADVECTION PATTERN AND THE APPROACH OF THE PAIR OF SHORTWAVES.
THE 07.00Z GFS/06.12Z ECMWF ALREADY SHOW HINTS OF WARM ADVECTION /
ISENTROPICALLY INDUCED PRECIPITATION AFFECTING FAR WESTERN PORTIONS
OF THE FORECAST AREA BETWEEN 21-00Z TODAY. THINKING THIS MIGHT BE A
BIT FAST...WITH THE 07.00Z NAM/REGIONAL CANADIAN/HIRES-ARW AND
07.03Z SREF ALL SLOWER. THUS...PLAN ON KEEPING CONDITIONS DRY TIL
00Z. AS WE HEAD THROUGH TONIGHT...THERE IS A STRONG CONSENSUS
AMONGST ALL MODEL GUIDANCE OF A PRECIPITATION SPLIT. THE NORTHERN
AREA TRACKS FROM NORTHWEST IA/SOUTHERN MN INTO NORTHWEST
WISCONSIN. THE SOUTHERN AREA TRACKS FROM NORTHERN MISSOURI INTO
SOUTHEAST IA AND NORTHWEST IL. THIS SPLIT APPEARS TO BE A RESULT
OF HOW THE PAIR OF SHORTWAVES APPROACHING THE FORECAST AREA LATE
TONIGHT INTERACT WITH THE ISENTROPIC LIFT PATTERN IN PLACE. 850MB
MOISTURE TRANSPORT FIELDS SHOW THE SPLIT INTERACTION WITH THE
ISENTROPIC LIFT PATTERN NICELY. IN ADDITION...THERE ARE OTHER
SUPPORTING FEATURES. FOR EXAMPLE...THE NORTHERN AREA BECOMES
INFLUENECED BY A DEVELOPING AND STRENGTHENING UPPER JET STREAK
OVER UPPER MICHIGAN...PLACING IT IN THE FAVORABLE RIGHT ENTRANCE
REGION. MEANWHILE...THE SOUTHERN AREA HAS A STRONG LOW TO MID-
LEVEL FRONTOGENESIS FEATURE ALONG THE PRESENT COLD FRONT NEAR
I-70...WHICH FOR ALL INTENSIVE PUPROSES TURNS INTO A STATIONARY
BOUNDARY. SO FOR THE FORECAST...THIS WELL AGREED UPON SPLIT
PRECIPITATION SCENARIO POSES A PROBLEM FROM WHAT WE HAD GOING
PREVIOUSLY. HAVE ADJUSTED PRECIPITATION CHANCES AND QPF QUITE A
BIT LOWER SOUTH OF I-90...SINCE THIS AREA WILL BE ON THE SUBSIDENT
SIDE OF THE F-GEN CIRCULATION. NOTE THAT MODELS LIKE THE 07.00Z
GFS/REGIONAL CANADIAN EVEN SUGGEST THAT SOME LOCATIONS ACROSS
NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN COULD END UP DRY.
REGARDING PRECIPITATION TYPE...ALL OF IT SHOULD FALL AS RAIN WITH
WET-BULB ZERO HEIGHTS PROGGED WELL ABOVE 2000 FT. THE PREVIOUS
FORECAST INTRODUCED A CHANCE FOR THUNDER AND THIS STILL LOOKS
REASONABLE AFTER MIDNIGHT...WITH POTENTIAL FOR A FEW HUNDERED J/KG
OF SKINNY CAPE LIFTED FROM 850MB.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 342 AM CDT SUN APR 7 2013
OVERALL MUCH OF THE LONG TERM PERIOD LOOKS ACTIVE...THANKS TO THAT
TROUGH DIGGING INTO CALIFORNIA AND NEVADA TONIGHT. QUITE A FEW
DETAILS TO NOTE.
ON MONDAY...THE PAIR OF SHORTWAVES ARE PROGGED TO SHIFT EAST INTO
MICHIGAN DURING THE AFTERNOON...TAKING THE BULK OF THE SPLIT
PRECIPITATION TONIGHT WITH THEM. HOWEVER...THE STORY DOES NOT END
THERE. THE FOCUS TURNS TO THE FRONTAL BOUNDARY NEAR I-70...WHICH BY
ALL MODELS IS SUGGESTED TO LIFT NORTH INTO CENTRAL AND PERHAPS
NORTHERN IA DURING THE AFTERNOON. THE LIFTING NORTH IS A RESULT OF
THE UPPER TROUGHING DEEPENING AND DIGGING INTO THE FOUR CORNERS
REGION...ENHANCING THE WARM ADVECTION DOWNSTREAM. THE 07.00Z
REGIONAL CANADIAN AND NAM SUGGEST THERE IS POTENTIAL FOR SURFACE
BASED CONVECTION TO FIRE ON THIS FRONT. THE 07.00Z GFS...ON THE
OTHER HAND...HAS A FARTHER SOUTH FRONT AND KEEPS THINGS MORE CAPPED.
HOWEVER...ALL THREE MODELS INCLUDING THE 06.12Z ECMWF DEPICT
POTENTIAL FOR FRONTOGENETICALY INDUCED PRECIPITATION NORTH OF THE
FRONTAL BOUNDARY. THUS...A NEED CONTINUES FOR CHANCES OF SHOWERS
ALONG WITH THE THUNDERSTORM MENTION IN THE EVENT THE REGIONAL
CANADIAN/NAM PAN OUT. IF THE REGIONAL CANADIAN/NAM PAN OUT...
CERTAINLY COULD NOT RULE OUT SOME SEVERE POTENTIAL GIVEN 0-6 KM
SHEAR UPWARS OF 45-50 KT. HOWEVER...IT SEEMS LIKE THE BETTER
INSTABILITY IS WEST OF THE FORECAST AREA...THUS KEEPING THE BULK OF
THE SEVERE POTENTIAL TO THE WEST. SPC DAY 2 SEVERE PROBABILITIES
DEPICT THIS AS WELL. DEFINITELY SOMETHING TO KEEP AN EYE
ON....THOUGH. TEMPERATURE FORECAST IS TRICKY AS IT DEPENDS ON THE
FRONTAL POSITION. A NAM/REGIONAL CANADIAN OR EVEN ECMWF SOLUTION
WOULD ALLOW FOR HIGHS IN THE 60S TO POSSIBLY 70 ALONG/SOUTH OF I-90.
THE GFS IS A LITTLE COOLER BUT STILL HAS HIGHS IN THE 60S SOUTH OF
I-90. RAISED HIGHS 5 DEGREES OR SO TO COME BETTER IN AGREEMENT WITH
ALL 07.00Z GUIDANCE...BUT THEY MAY NEED TO BE RAISED MORE...
ESPECIALLY IF MORE SUN OCCURS IN THE AFTERNOON.
THINGS GET MORE INTERESTING HEADING INTO THE MONDAY NIGHT THROUGH
THURSDAY TIME PERIOD. DURING THIS PERIOD...ALL MODELS HAVE THE DEEP
UPPER TROUGH OVER THE FOUR CORNERS SLOWLY LIFTING TO THE
EAST-NORTHEAST. MEANWHILE...AT THE SAME TIME THERE IS A DEEP UPPER
TROUGH HANGING AROUND THE HUDSON BAY INTO NORTHERN ONTARIO AREA...
HELPING TO HOLD AN UPPER JET STREAK IN PLACE OVER THE NORTHERN GREAT
LAKES. THIS MEANS THE FORECAST AREA IS GOING TO BE PLACED IN THE
FAVORABLE RIGHT ENTRANCE REGION UNTIL THE UPPER TROUGH MOVES IN.
MONDAY NIGHT FOR THE MOST PART LOOKS QUIET...WITH ANY SHOWERS AND
POSSIBLE THUNDERSTORMS IN THE EVENING DISSIPATING WITH LOSS OF
DAYTIME HEATING. THE FRONTAL BOUNDARY...IF IT IS NEARBY...LOOKS TO
SLOWLY DROP SOUTH MONDAY NIGHT FORCED BY THAT DEEP UPPER TROUGH TO
OUR NORTH. IT APPEARS THERE MAY BE A MASS OF LOW LEVEL STRATUS THAT
MOVES IN BEHIND THE FRONT...AND WITH LOW LEVEL FRONTOGENESIS BEHIND
THE FRONT WE COULD DEAL WITH SOME LIGHT RAIN OR DRIZZLE.
PRECIPITATION CHANCES DEFINITELY GO ON THE INCREASE FROM SOUTHWEST
TO NORTHEAST THROUGH THE DAY TUESDAY AND INTO TUESDAY NIGHT...IN
RESPONSE TO ISENTROPIC LIFT STRENGTHENING DOWNSTREAM OF THE UPPER
TROUGH PUSHING TO THE EAST-NORTHEAST. SOME CONCERN FOR SOME HEAVIER
RAIN TUESDAY NIGHT...ESPECIALLY ACROSS THE SOUTH...AS PRECIPITABLE
WATER VALUES INCREASE OVER 1 INCH AND SOME WEAK ELEVATED INSTABILITY
MOVES IN FOR THUNDERSTORMS. RAISED BOTH PRECIPITATION CHANCES AND
QPF FOR TUESDAY AND ESPECIALLY TUESDAY NIGHT GIVEN THE STRONG SIGNAL
AMONGST THE 07.00Z ECMWF/GFS/CANADIAN MODELS. FROM WEDNESDAY INTO
THURSDAY...THE CORE OF THE UPPER TROUGH IS PROGGED TO SLOWLY
APPROACH THE FORECAST AREA. AS THIS OCCURS...THE FORECAST AREA
EVENTUALLY ENDS UP ON THE NORTHWEST / COLD SIDE OF A SURFACE LOW
TRACKING TO OUR SOUTH...PLACING THE AREA INTO THE TROWAL AND COLD
CONVEYOR BELT REGION. GIVEN THE GOOD MODEL AGREEMENT AGAIN...RAISED
PRECIPITATION CHANCES UP DURING THIS PERIOD. IN ADDITION...WILL HAVE
TO WATCH FOR SOME SNOW ACCUMULATIONS COME WEDNESDAY NIGHT AND
THURSDAY AS 850MB TEMPS DROP TO -4 TO -8C BY 12Z THURSDAY.
IT SHOULD BE NOTED THAT THE 07.00Z NAM IS AN OUTLIER SOLUTION TO THE
ABOVE SCENARIO...PARTICULARLY FOR TUESDAY THROUGH WEDNESDAY...SINCE
IT EJECTS THE CORE OF THE SOUTHWESTERN TROUGH MUCH QUICKER AND LIFTS
IT FARTHER NORTH. THE NAM WAS DISCOUNTED GIVEN GOOD MODEL AGREEMENT
BETWEEN ALL OTHER MODELS. THE 07.03Z SREF LOOKS LIKE A COMPROMISE
BETWEEN THE NAM AND GFS...BUT THE SREF IS NAM-BIASED DUE TO AN
OVERWHELMING AMOUNT OF NAM MEMBERS. THUS...THE SREF WAS DISCOUNTED
AS WELL.
LOOKING FARTHER AHEAD...GOOD MODEL AGREEMENT EXISTS AMONGST THE
07.00Z ECMWF/GFS/CANADIAN ON BRINGING COLD CANADIAN HIGH PRESSURE
INTO THE AREA THURSDAY NIGHT THROUGH FRIDAY NIGHT. THIS SHOULD HELP
DRY THINGS OUT. LEFT A CONSENUS 20 PERCENT CHANCE OF PRECIPITATION
IN THURSDAY NIGHT...BUT THIS PERIOD MAY EVENTUALLY END UP DRY. WILL
NEED TO WATCH SOME OF THE LOW TEMPERATURES TOO FOR BOTH THURSDAY
NIGHT AND FRIDAY NIGHT...DEPENDING ON HOW MUCH FRESH SNOW WE PICK UP
AND FOR FRIDAY NIGHT HOW MUCH IS STILL ON THE GROUND. A WARM
ADVECTION PATTERN SETS UP FOR SATURDAY AHEAD OF NEW TROUGHING
DROPPING INTO THE NORTHERN ROCKIES. FOLLOWED THE CONSENSUS HERE OF
BRINGING SOME 20-30 PERCENT CHANCES OF PRECIPITATION ACROSS THE AREA
ON SATURDAY. NEED TO MAINTAIN A RAIN/SNOW MIX BECAUSE 850MB TEMPS
ARE STILL SLOW TO WARM...ESPECIALLY IN THE ECMWF WHERE IT KEEPS THEM
BELOW 0C THROUGH 00Z SUNDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1226 PM CDT SUN APR 7 2013
MVFR STRATUS IN PLACE ACROSS THE REGION GOING INTO THIS AFTERNOON.
RAP/NAM BUFKIT SOUNDINGS INSIST THAT THIS STRATUS WILL DISPERSE
FROM SOUTH TO NORTH ACROSS THE AREA. LATEST VIS SATELLITE
LOOP...IN FACT...STARTING TO SHOW THIS TREND. BASED ON THIS...HAVE
KRST AND KLSE SCATTERING OUT IN THE 22-23Z TIME FRAME. THIS
CLEARING WILL BE SHORT-LIVED HOWEVER DUE TO VFR MID-CLOUD
SPREADING NORTHEAST OUT OF THE PLAINS AHEAD OF LOW PRESSURE
DEVELOPING OVER THE INTERMOUNTAIN WEST. LOOK FOR THE LOW TO SLOWLY
LIFT OUT OF THE INTERMOUNTAIN WEST INTO THE PLAINS TONIGHT INTO
MONDAY. THIS WILL LIFT A WARM FRONT NORTHEAST TOWARD THE AREA AND
PRODUCE SCATTERED/NUMEROUS SHOWERS LATER THIS EVENING THROUGH THE
OVERNIGHT HOURS. EXPECT DETERIORATING CLOUD CIGS AND VSBY INTO
MVFR/IFR RANGE AFTER 08Z...LASTING INTO MONDAY MORNING. MAY SEE
ENOUGH MID-LEVEL INSTABILITY FOR A FEW EMBEDDED THUNDERSTORMS
AFTER MIDNIGHT THROUGH MONDAY MORNING...BUT NOT CONFIDENT ENOUGH AT
THIS POINT TO INCLUDE IN THE BODY OF THE TAF.
&&
.HYDROLOGY...
ISSUED AT 342 AM CDT SUN APR 7 2013
RIVER STATUS...
THE TREMPEALEAU RIVER NEAR DODGE WILL REMAIN ABOVE FLOOD STAGE AND
ALLOW FOR MINOR FLOODING TO CONTINUE THROUGH MONDAY MORNING.
MEANWHILE ON THE BLACK...ANOTHER BRIEF ICE JAM LOOKS LIKE IT MAY
HAVE FORMED AROUND NEILLSVILLE...WITH A SPIKE UP OF 4 FEET BUT STILL
WELL WITHIN THE RIVER BANK. DOWNSTREAM...SO FAR THE BLACK REMAINS
WITHIN THE RIVER BANK.
SNOW PACK...
RECENT COOPERATIVE OBSERVER REPORTS SHOW SNOW PACK IS MAINLY ALONG
AND NORTHEAST OF THE INTERSTATE 94 CORRIDOR WITH 2 TO 7 INCHES OF
SNOW DEPTH IN PLACES. THE DEEPEST SNOW PACK IS OVER THE NORTHERN
MOST PARTS OF TAYLOR WHERE AROUND A FOOT OF SNOW REMAINS ON THE
GROUND. SNOW WATER EQUIVALENT OF 1 TO 2 INCHES IS MAINLY NORTH OF
THE INTERSTATE 94 CORRIDOR WITH THE GREATEST SNOW WATER EQUIVALENT
OF 2 TO 4 INCHES IN NORTHERN TAYLOR COUNTY.
RAINFALL...
LESS RAINFALL IS ANTICIPATED TONIGHT INTO MONDAY THAN PREVIOUSLY
EXPECTED...WITH UPWARDS OF 1/4 TO 1/2 INCH NORTH OF I-90 AND LESS
THAN A 1/4 INCH TO THE SOUTH. WILL STILL NEED TO WATCH TUESDAY
THROUGH WEDNESDAY...THOUGH. BY WEDNESDAY MORNING...CURRENTLY
ANTICIPATING AMOUNTS BETWEEN 3/4 INCH AND 1.25 INCHES SOUTH OF
HIGHWAY 10 TO LESS THAN A 1/2 INCH TO THE NORTH. IF THE SYSTEM
BRINGING THIS RAIN SHIFTS FARTHER NORTH...THE HEAVY RAIN AREA WILL
SHIFT NORTH AS WELL...PLACING IT WHERE RAIN IS NOT NEEDED.
TEMPERATURES...
HIGHS TODAY ARE GOING TO BE COOLER...IN THE THE MIDDLE 40S/AROUND 50
NORTH OF I-94 AND IN THE 50S SOUTH OF THERE. WARMER CONDITIONS LOOK
ON TAP FOR MONDAY...WITH MOSTLY 50S NORTH OF I-94 AND 60S SOUTH.
TEMPERATURES THEN COOL INTO THE 40S FOR TUESDAY AND WEDNESDAY AND
POSSIBLY STRUGGLE TO GET TO 40 BY THURSDAY. THE TEMPERATURE MAY NOT
MATTER IN A FEW DAYS AS MOST OF THE SNOW PACK MAY BE GONE...UNTIL
POTENTIALL A SMALL SNOW PACK RE-ESTABLISHES ITSELF THURSDAY MORNING.
FROST DEPTH...
AS OF APRIL 4TH...FROST DEPTHS //WHICH ARE OBSERVED EVERY MONDAY AND
THURSDAY//ACROSS THE AREA REMAIN DEEP...AVERAGING AROUND 1 FOOT TO 1
1/2 FEET SOUTH OF I-90...AND UP TO 3 FEET ACROSS PORTIONS OF NORTH
CENTRAL WISCONSIN. THIS FROST WILL ACT TO ENHANCE RUNOFF OF SNOW
MELT AND PRECIPITATION INTO STREAMS AND RIVERS.
SUMMARY...
MAIN CONCERN FOR FLOODING REMAINS ALONG THE TREMPEALEAU AND BLACK
RIVERS AS SNOW MELT CONTINUES...ALONG WITH THE PERIODS OF RAINFALL
TONIGHT INTO MONDAY AS WELL AS TUESDAY THROUGH WEDNESDAY. HAVE A
HYDROLOGIC OUTLOOK PRODUCT OUT TO HEIGHTEN THIS AWARENESS. ALTHOUGH
THE TUESDAY INTO WEDNESDAY MODERATE TO HEAVY RAIN IS FORECAST MAINLY
SOUTH OF I-90...CURRENTLY THINKING THAT THE RIVERS SHOULD BE ABLE TO
ABSORB IT. A QUICK MODEL OF THE TURKEY RIVER AT GARBER USING THE
FORECAST QPF WOULD BRING THE RIVER ABOVE ACTION STAGE BUT NOT TO
FLOOD. THUS...DID NOT EXPAND THE HYDROLOGIC OUTLOOK SOUTH.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...DAS
HYDROLOGY...AJ