Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 04/27/13
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
852 AM MDT THU APR 25 2013
.UPDATE...TEMPERATURES WILL BE WARMER TODAY AND BE NEAR NORMAL FOR
THIS TIME OF YEAR. AN UPPER LEVEL TROUGH WILL MOVE FROM THE
DESERT SOUTHWEST AND CROSS THE SOUTHERN ROCKIES TONIGHT. MODELS
MAY BE A TINY BIT TOO FAR NORTH ON PLACEMENT OF THIS TROUGH WHEN
COMPARING IT WITH SATELLITE. CURRENT FORECAST CALLS FOR A SLIGHT
CHANCE OF THUNDERSTORMS THIS AFTERNOON AND EVENING SOUTH OF I-70.
THIS LOOKS GOOD AT THIS TIME. WILL ONLY MAKE A FEW MINOR CHANGES
TO LINE UP WITH CURRENT TRENDS.
&&
.AVIATION...LIGHT WINDS THIS MORNING WILL TURN EASTERLY AFTER 18Z.
ONLY EXPECT MID AND HIGH CLOUDS ACROSS THE DENVER AREA THROUGH
TODAY AND TONIGHT. A FEW SHOWERS AND PERHAPS WEAK THUNDERSTORMS
MAY FORM OVER THE SOUTHERN HALF OF COLORADO. THESE ARE EXPECTED TO
STAY SOUTH OF THE DENVER AREA. A WEAK COLD FRONT WILL CAUSE WINDS
TO SHIFT TO THE NORTH AFTER 06Z TONIGHT. HOWEVER WINDS SPEEDS ARE
EXPECTED TO REMAIN LESS THEN 20 KNOTS THROUGH THE NEXT 24 HOURS.
&&
.PREV DISCUSSION... /ISSUED 402 AM MDT THU APR 25 2013/
SHORT TERM...A WK CLOSED LOW OVR SRN CALIFORNIA WILL EJECT ENE
TOWARDS SRN CO BY TONIGHT. AHEAD OF THIS FEATURE THERE WILL BE AN
INCREASE IN MID AND HIGH LEVEL MOISTURE HOWEVER LOWER LEVELS ARE
RELATIVELY DRY. ENOUGH MOISTURE AND INSTABILITY MAY EXIST FOR A
FEW SHOWERS AND ISOLD TSTMS LATE THIS AFTN INTO THE EARLY EVENING
HOURS IN THE MTNS SOUTH OF I-70 AND ACROSS THE PALMER DIVIDE.
OTHERWISE ACROSS THE NRN HALF OF THE FORECAST AREA THRU TONIGHT.
AS FOR HIGH TEMPS LATEST RAP AND GFS SHOW HIGHS IN THE UPPER 60S
TO LOWER 70S ACROSS NERN CO WHILE THE NAM HAS HIGHS IN THE LOWER
TO MID 60S. AT THIS TIME WILL KEEP READINGS IN THE MID TO UPPER
60S ACROSS THE PLAINS.
LONG TERM...MODELS SHOW A WEAK UPPER TROUGH AXIS TO MOVE EASTWARD
ACROSS THE FORECAST AREA ON FRIDAY. BY FRIDAY AFTERNOON THROUGH
FRIDAY NIGHT...THE FLOW ALOFT IS WEAK AND NORTH-NORTHEASTERLY.
THE FLOW ALOFT STAYS WEAK SATURDAY AND SATURDAY NIGHT AND IS
MAINLY NORTHERLY. THERE IS WEAK DOWNWARD SYNOPTIC SCALE ENERGY FOR
THE CWA FRIDAY...THEN NEUTRAL ENERGY THROUGH SATURDAY NIGHT.
MODELS STILL HAVE WEAK UPSLOPE FLOW IN THE BOUNDARY LAYER ON
FRIDAY...THEN NORMAL DRAINAGE PATTERNS FRIDAY NIGHT. WEAK
DOWNSLOPING FLOW IS PROGGED ON SATURDAY. FOR MOISTURE...THERE IS
NOT A LOT COMPARED TO WHAT WE`VE SEEN FOR THE LAST MANY WEEKS.
THERE IS A BIT OF MID LEVEL MOISTURE PROGGED FRIDAY INTO
SATURDAY...BUT OVERALL IT IS PRETTY DRY. THERE IS A SMIDGEN OF
CAPE IN THE MOUNTAINS AND FOOTHILLS LATE DAY FRIDAY. THERE IS EVEN
LESS LATE DAY SATURDAY...AND IT IS STILL OVER THE HIGH COUNTY
ONLY. THE QPF FIELDS HAVE SLIGHT AMOUNTS OF MEASURABLE
PRECIPITATION OVER THE MOUNTAINS AND FOOTHILLS LATE DAY
FRIDAY...THEN NOTHING THROUGH SATURDAY NIGHT. WILL KEEP POPS OUT
FRIDAY THROUGH SATURDAY NIGHT. FOR TEMPERATURES...FRIDAY`S HIGHS
ARE SIMILAR TO TODAY`S. SATURDAY`S WARM-UP 3-5 C FROM FRIDAY`S.
FOR THE LATER DAYS...SUNDAY THROUGH WEDNESDAY...WEAK FLOW ALOFT IS
EXPECTED SUNDAY AND MONDAY. BY TUESDAY AND WEDNESDAY...A BROAD
UPPER TROUGH IS PROGGED TO MOVE ACROSS COLORADO. THE MAJORITY OF
ITS ENERGY STAYS TO OUR NORTH. THE ECMWF HAS BETTER UPSLOPE AND
MORE MOISTURE FOR A LONGER PERIOD OF TIME WITH THIS SYSTEM
COMPARED TO THE GFS. WILL KEEP POPS IN THE 20-30% RANGE FOR NOW.
AVIATION...THERE WILL BE SOME INCREASE IN MID AND HIGH LEVEL
CLOUDS HOWEVER ANY PCPN LATE THIS AFTN AND EVENING SHOULD STAY
OVER THE PALMER DIVIDE AND NOT AFFECT THE AIRPORT. WINDS WILL
REMAIN SSW EARLY THIS MORNING...BY LATE MORNING THRU EARLY AFTN
THE RAP IS SHOWING A WK DENVER CYCLONE WITH LIGHT AND VARIABLE
WINDS MUCH OF THE AFTN. BY 00Z THE RAP SHOWS INCREASING SELY WINDS
POSSIBLY DUE TO HIGH BASED SHOWER ACTIVITY OVER THE PALMER DIVIDE
WHILE THE NAM HAS LIGHT N WINDS AT THE SAME TIME. FOR NOW WILL
KEEP WINDS LIGHT N AND THEN TRANSITION THEM TO MORE SSW BY 05Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...MEIER
SHORT TERM...RPK
LONG TERM....RJK
AVIATION...MEIER
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
402 AM MDT THU APR 25 2013
.SHORT TERM...A WK CLOSED LOW OVR SRN CALIFORNIA WILL EJECT ENE
TOWARDS SRN CO BY TONIGHT. AHEAD OF THIS FEATURE THERE WILL BE AN
INCREASE IN MID AND HIGH LEVEL MOISTURE HOWEVER LOWER LEVELS ARE
RELATIVELY DRY. ENOUGH MOISTURE AND INSTABILITY MAY EXIST FOR A
FEW SHOWERS AND ISOLD TSTMS LATE THIS AFTN INTO THE EARLY EVENING
HOURS IN THE MTNS SOUTH OF I-70 AND ACROSS THE PALMER DIVIDE.
OTHERWISE ACROSS THE NRN HALF OF THE FORECAST AREA THRU TONIGHT.
AS FOR HIGH TEMPS LATEST RAP AND GFS SHOW HIGHS IN THE UPPER 60S
TO LOWER 70S ACROSS NERN CO WHILE THE NAM HAS HIGHS IN THE LOWER
TO MID 60S. AT THIS TIME WILL KEEP READINGS IN THE MID TO UPPER
60S ACROSS THE PLAINS.
.LONG TERM...MODELS SHOW A WEAK UPPER TROUGH AXIS TO MOVE EASTWARD
ACROSS THE FORECAST AREA ON FRIDAY. BY FRIDAY AFTERNOON THROUGH
FRIDAY NIGHT...THE FLOW ALOFT IS WEAK AND NORTH-NORTHEASTERLY.
THE FLOW ALOFT STAYS WEAK SATURDAY AND SATURDAY NIGHT AND IS
MAINLY NORTHERLY. THERE IS WEAK DOWNWARD SYNOPTIC SCALE ENERGY FOR
THE CWA FRIDAY...THEN NEUTRAL ENERGY THROUGH SATURDAY NIGHT.
MODELS STILL HAVE WEAK UPSLOPE FLOW IN THE BOUNDARY LAYER ON
FRIDAY...THEN NORMAL DRAINAGE PATTERNS FRIDAY NIGHT. WEAK
DOWNSLOPING FLOW IS PROGGED ON SATURDAY. FOR MOISTURE...THERE IS
NOT A LOT COMPARED TO WHAT WE`VE SEEN FOR THE LAST MANY WEEKS.
THERE IS A BIT OF MID LEVEL MOISTURE PROGGED FRIDAY INTO
SATURDAY...BUT OVERALL IT IS PRETTY DRY. THERE IS A SMIDGEN OF
CAPE IN THE MOUNTAINS AND FOOTHILLS LATE DAY FRIDAY. THERE IS EVEN
LESS LATE DAY SATURDAY...AND IT IS STILL OVER THE HIGH COUNTY
ONLY. THE QPF FIELDS HAVE SLIGHT AMOUNTS OF MEASURABLE
PRECIPITATION OVER THE MOUNTAINS AND FOOTHILLS LATE DAY
FRIDAY...THEN NOTHING THROUGH SATURDAY NIGHT. WILL KEEP POPS OUT
FRIDAY THROUGH SATURDAY NIGHT. FOR TEMPERATURES...FRIDAY`S HIGHS
ARE SIMILAR TO TODAY`S. SATURDAY`S WARM-UP 3-5 C FROM FRIDAY`S.
FOR THE LATER DAYS...SUNDAY THROUGH WEDNESDAY...WEAK FLOW ALOFT IS
EXPECTED SUNDAY AND MONDAY. BY TUESDAY AND WEDNESDAY...A BROAD
UPPER TROUGH IS PROGGED TO MOVE ACROSS COLORADO. THE MAJORITY OF
ITS ENERGY STAYS TO OUR NORTH. THE ECMWF HAS BETTER UPSLOPE AND
MORE MOISTURE FOR A LONGER PERIOD OF TIME WITH THIS SYSTEM
COMPARED TO THE GFS. WILL KEEP POPS IN THE 20-30% RANGE FOR NOW.
&&
.AVIATION...THERE WILL BE SOME INCREASE IN MID AND HIGH LEVEL
CLOUDS HOWEVER ANY PCPN LATE THIS AFTN AND EVENING SHOULD STAY
OVER THE PALMER DIVIDE AND NOT AFFECT THE AIRPORT. WINDS WILL
REMAIN SSW EARLY THIS MORNING...BY LATE MORNING THRU EARLY AFTN
THE RAP IS SHOWING A WK DENVER CYCLONE WITH LIGHT AND VARIABLE
WINDS MUCH OF THE AFTN. BY 00Z THE RAP SHOWS INCREASING SELY WINDS
POSSIBLY DUE TO HIGH BASED SHOWER ACTIVITY OVER THE PALMER DIVIDE
WHILE THE NAM HAS LIGHT N WINDS AT THE SAME TIME. FOR NOW WILL
KEEP WINDS LIGHT N AND THEN TRANSITON THEM TO MORE SSW BY 05Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....RJK
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1013 PM EDT FRI APR 26 2013
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN ANCHORED OVER THE REGION THROUGH NEXT
WEEK. DRY WEATHER WILL DOMINATE WITH MILD DAYS AND COOL
NIGHTS...THOUGH TEMPERATURES MAY BECOME COOLER LATE IN THE WEEK
WITH ONSHORE WINDS. NO APPRECIABLE RAINFALL WILL OCCUR THROUGH
NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
LOOKS LIKE THE SHOWERS ARE DIMINISHING AND MOVING OFF TO THE EAST.
SATELLITE IMAGERY SHOWS THE CLOUDS FRACTURING/DISSIPATING. SO WE
EXPECT A TREND TOWARD MOSTLY CLEAR SKIES OVERNIGHT. MODEL RH
FIELDS ALSO INDICATE THIS TREND...SO THEORY AND OBSERVATION SEEM
TO BE IN ACCORD!
WE HAVE ADJUSTED TEMPS AND DEWPOINTS BASED ON EVENING
OBSERVATIONS...AND USED A BLEND OF GLAMP AND RAP GRIDS TO TREND
THESE VALUES OVERNIGHT. WITH /DEVELOPING/ MOSTLY CLEAR SKIES AND
LIGHT WINDS...EXPECT TEMPS TO RADIATE OVERNIGHT. SURFACE DEWPOINTS
25-35F SUGGEST MIN TEMPS IN A SIMILAR RANGE OR JUST A COUPLE OF
DEGREES MILDER THAN THIS RANGE. SO EXISTING MIN TEMP FORECAST
LOOKS FINE.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
SATURDAY...
PLENTY OF SUNSHINE TO START ALONG WITH A DRY AIRMASS IN PLACE
WILL ALLOW FOR A QUICK TEMPERATURE RECOVERY AFTER A CHILLY START.
HIGHS SHOULD REBOUND IN THE UPPER 60S TO AROUND 70 INLAND FROM THE
COAST. MAY SEE SOME MID/HIGH CLOUDS MOVE IN FOR A TIME LATE IN THE
MORNING OR AFTERNOON...BUT STILL EXPECT PARTIAL SUNSHINE INTO THE
AFTERNOON. HIGH PRESSURE OVERHEAD WILL ALSO RESULT IN LIGHT WINDS
MAKING THE AFTERNOON FEEL QUITE COMFORTABLE FOR OUTDOOR
ACTIVITIES.
WEAK PRESSURE GRADIENT WILL ALLOW FOR SEA BREEZES TO DEVELOP ALONG
THE IMMEDIATE COAST...HOLDING HIGH TEMPS IN THIS REGION TO THE
UPPER 50S AND LOWER 60S.
SATURDAY NIGHT...
HIGH PRESSURE WILL REMAIN ANCHORED ACROSS THE EAST
COAST. THIS WILL RESULT IN MAINLY CLEAR SKIES ALONG WITH ANOTHER
GOOD NIGHT OF RADIATIONAL COOLING. TEMPERATURES ACROSS THE OUTLYING
LOCATIONS WILL QUICKLY DROP AFTER SUNSET. LOW TEMPS BY DAYBREAK
SUNDAY SHOULD BE WELL DOWN INTO THE 30S ACROSS MOST OUTLYING
LOCATIONS...TO THE MIDDLE AND UPPER 40S IN THE URBAN HEAT ISLANDS
OF DOWNTOWN BOSTON/PROVIDENCE.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
HIGHLIGHTS...
* STRONG HIGH PRESSURE REMAINS ACROSS THE REGION THROUGH THE PERIOD
* MILD TEMPERATURES SUNDAY AND MONDAY...THEN LOWERING TO BELOW
NORMAL BY LATE NEXT WEEK
OVERVIEW AND MODEL PREFERENCES...
MEDIUM RANGE MODELS STARTING TO SIGNAL A BREAKDOWN OF THE BLOCKING
PATTERN ACROSS THE NORTHERN PACIFIC...BUT EVOLVES INTO AN OMEGA
BLOCK ACROSS THE LOWER 48 BY LATE NEXT WEEK. H5 CUTOFF LOW APPEARS
TO DEVELOP ACROSS THE CENTRAL U.S. WHILE BLOCKING ACROSS THE
NORTHERN ATLANTIC LOOKS TO REMAIN STRONG...SO SURFACE RIDGING
SHOULD BLOCK PRECIP FROM WORKING INTO THE REGION THROUGH MOST IF
NOT ALL OF THIS TIMEFRAME.
AS THE RIDGE BUILDS DOWN THE EASTERN SEABOARD...MODELS ALSO
SIGNALING DEVELOPMENT OF AN INVERTED TROUGH WITH ONSHORE FLOW INTO
THE SE U.S. EARLY NEXT WEEK...WHICH WILL FEED OCEAN MOISTURE ACROSS
THAT REGION. MODELS TRY TO WORK THIS N INTO NY STATE AND EVEN INTO
FAR WESTERN NEW ENGLAND...BUT HIGH SHOULD BLOCK ANY APPRECIABLE
MOISTURE FROM WORKING IN. FURTHER DOWNSTREAM...MOISTURE EVENTUALLY
WORKS NWWD INTO A SLOWLY MOVING SURFACE FRONT INTO THE CENTRAL U.S.
AS THE UPPER LEVEL PATTERN BEGINS TO AMPLIFY BY MID TO LATE NEXT
WEEK...EFFECTIVELY SLOWING THE PROGRESSION OF THE SURFACE SYSTEM
OUT WEST.
FROM WEDNESDAY ONWARD...MODEL SOLUTION SPREAD INCREASES. OP RUNS OF
THE GFS TRY TO BRING COLD FRONT AND MOISTURE IN FASTER THAN THE
ECMWF...WHILE THE ENSEMBLES ARE SLOWER WITH ANY PROGRESSION
EASTWARD.
PLAN ON USING WPC GUIDANCE ESPECIALLY AFTER TUESDAY...WHICH IS A
BLEND OF GFS/EC ENSEMBLES WITH SOME INCORPORATION OF THEIR OP RUNS
MAINLY FROM MON-WED DUE TO GOOD CONTINUITY DURING THAT TIMEFRAME.
DETAILS...
SUNDAY-MONDAY...APPEARS THAT HIGH PRES WILL WORK OFF THE COAST WITH
WEAK S-SW FLOW IN PLACE. THIS WILL BRING TEMPS UP...WITH HIGHS IN
THE LOWER-MID 70S WELL INLAND BUT WILL HOLD BACK IN THE 60S ALONG
THE COAST WITH SEA BREEZES FOR SUNDAY.
ON MONDAY...WITH THE HIGH JUST OFFSHORE...LOOKS LIKE SOME MOISTURE
TRIES TO WORK AROUND THE WESTERN PERIPHERY INTO NY STATE. STILL A
VERY DRY AIRMASS AND GOOD SUBSIDENCE ACROSS NEW ENGLAND...SO ANY
PRECIP THAT TRIES TO WORK IN SHOULD DISSIPATE. HAVE KEPT SLIGHT
CHANCE POPS JUST W OF THE REGION...THOUGH CLOUDS WILL WORK IN AS FAR
E AS S CENTRAL NH/CENTRAL MA AND WESTERN RI LATE MON/MON NIGHT.
STILL A CHANCE OF PATCHY LATE NIGHT/EARLY MORNING FOG MAINLY MON
NIGHT OVER WESTERN AREAS.
TUESDAY-WEDNESDAY...HIGH PRES STARTS TO BUILD BACK A BIT FURTHER W
WHILE AN INVERTED TROUGH TAKES SHAPE ACROSS THE SE U.S. BRINGING
MOISTURE INTO THE MID ATLC/SE. THE RIDGE AXIS PUSHES THE WESTERN
ATLC MOISTURE FURTHER INLAND...KEEPING DRY CONDITIONS BUT COOLER
TEMPS AS WINDS BECOME MORE ONSHORE AND A BIT STRONGER. TEMPS
START TO TREND DOWNWARD...MAINLY IN THE 60S THOUGH APPEARS TO BE
COOLER ON WEDNESDAY WITH HIGHS UP TO 5 DEGREES BELOW SEASONAL
NORMS ALONG THE E COAST. MAY START TO SEE SOME NIGHTTIME/EARLY
MORNING LOW CLOUDS DEVELOP ALONG THE COAST EACH NIGHT ALONG WITH
PATCHY FOG.
THURSDAY-FRIDAY...HIGH REMAINS DOMINANT WEATHER FEATURE ACROSS THE
REGION. HOWEVER...IT WILL BE COOL WITH A STEADY E FETCH AROUND THE
BASE OF THE HIGH WHICH RE-POSITIONS ACROSS NOVA SCOTIA AND LABRADOR.
OP RUN OF GFS ALSO TRIES TO PUSH LOW PRES AND A FRONT CLOSER TO THE
REGION DURING THIS TIMEFRAME...WHICH MAY INCREASE THE PRES GRADIENT
AND WINDS. WILL PROBABLY SEE OCEAN CLOUDS DEVELOP AND MOVE ONSHORE
ESPECIALLY ALONG THE COAST BUT CAN NOT RULE OUT MOVING FURTHER
INLAND BY FRIDAY. WILL SEE HIGHS ONLY BE IN THE MID 50S TO MID 60S
BY FRIDAY...MILDEST ACROSS THE CT VALLEY...BUT WILL REMAIN DRY.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
SHORT TERM...
HIGH CONFIDENCE IN VFR CONDITIONS THROUGH SATURDAY NIGHT. SEA
BREEZES EXPECTED TO DEVELOP ON THE COAST LATE SAT MORNING INTO THE
AFTERNOON.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF. E-NE WIND WILL DIMINISH BY
03Z OR SO. EXPECT E-SE SEA BREEZE TO RETURN SATURDAY AFTERNOON.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.
OUTLOOK...SUNDAY THROUGH WEDNESDAY...
SUNDAY-WEDNESDAY...HIGH CONFIDENCE.
MAINLY VFR THROUGH PERIOD. MAY SEE BRIEF LOCAL MVFR-IFR
CIGS/VSBYS DURING THE NIGHT/EARLY MORNING HOURS STARTING MONDAY
NIGHT/TUE MAINLY ALONG THE COAST IN LOW OCEAN CLOUDS AND PATCHY
FOG. EXPECT SEA BREEZES SUNDAY AND MONDAY.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
LONG PERIOD SWELL HAS DIMINISHED AT JEFFREYS LEDGE WITH 930 PM
OBSERVATION AT 4.3 FEET...DOWN HALF A FOOT FROM THE PREVIOUS HOUR.
THE VALUE AND THE TREND BOTH SUPPORT AN END TO THE SMALL CRAFT
HEADLINE OFF CAPE ANN.
HIGH CONFIDENCE THROUGH SATURDAY NIGHT. HIGH PRESSURE OVERHEAD
WILL KEEP WINDS/SEAS BELOW SCA THRESHOLDS THROUGH SATURDAY NIGHT.
OUTLOOK...SUNDAY THROUGH WEDNESDAY...
HIGH CONFIDENCE THROUGH THE PERIOD.
EXPECT CONDITIONS BELOW SMALL CRAFT CRITERIA THROUGH THE PERIOD.
MAY SEE BRIEF PERIODS OF SEAS UP TO 5 FT TUE-WED ON THE EASTERN
OUTER WATERS WITH INCREASING E FETCH.
&&
.FIRE WEATHER...
MAINLY DRY WEATHER WITH NO APPRECIABLE RAINFALL IS ANTICIPATED
THROUGH NEXT WEEK. MINIMUM AFTERNOON RELATIVE HUMIDITIES MAY DROP
BELOW 30 PERCENT AT TIMES ACROSS THE INTERIOR. UPPER LEVEL RIDGING
WILL KEEP WIND SPEEDS BELOW FIRE WEATHER HEADLINE CRITERIA MUCH OF
THE TIME...BUT CAN/T RULE OUT A DAY OR TWO WHERE IT GETS CLOSE.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...WTB/FRANK/EVT
NEAR TERM...WTB/FRANK/EVT
SHORT TERM...FRANK
LONG TERM...EVT
AVIATION...FRANK/EVT
MARINE...WTB/FRANK/EVT
FIRE WEATHER...
AREA FORECAST DISCUSSION
NWS NEW YORK NY
130 PM EDT THU APR 25 2013
.SYNOPSIS...
HIGH PRESSURE THEN BUILDS INTO THE REGION THROUGH THE WEEKEND AND
WILL PERSIST INTO THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
ADJUSTED HIGH TEMPERATURES DOWN FROM PREVIOUS FORECAST DUE TO
COLD ADVECTION CONTINUING THROUGH THE DAY AND RELATIVELY WEAK
WINDS IN THE LOWER LEVELS. USED THE LATEST 12Z NAM AND
INCORPORATED MIXING TO H85. ALONG THE COAST WHERE AFTERNOON SEA
BREEZE DEVELOPMENT IS ANTICIPATED...BLENDED IN THE LATEST RAP MODEL
MAX TEMPERATURES. THIS GIVES HIGHS IN THE UPPER 50S INLAND TO
LOWER 60S IN NYC AND LONG ISLAND. TEMPERATURES SHOULD BEGIN TO LEVEL
OFF ONCE THE SEA BREEZE PASSES AND BEGIN TO COOL WITH WINDS
TURNING TO THE SOUTH.
WINDS ARE STILL EXPECTED TO DIMINISH BY THE AFTERNOON TO 10 TO 15
MPH WITH A SUNNY SKY CONDITION.
OTHERWISE...FORECAST REMAINS ON TRACK.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
UPPER LEVEL TROUGH PASSES TO THE N TONIGHT. DO NOT EXPECT ANY
PCPN THIS FAR S...JUST A TEMPORARY INCREASE IN CLOUD COVER...
THEREFORE REMOVED SCHC POPS. LIGHT WINDS AND MOSTLY CLEAR SKIES
TONIGHT WILL ALLOW FOR GOOD RADIATIONAL COOLING CONDITIONS. IT
WILL BE CHILLY ONE ACROSS THE INTERIOR AND PINE BARRENS OF LONG
ISLAND...DROPPING INTO THE LOWER 30S. ELSEWHERE...OVERNIGHT LOWS
WILL BE SLIGHTLY BELOW NORMAL LEVELS IN THE UPPER 30S TO LOWER
40S...MID 40S IN METRO NYC/NJ.
FAIR AND DRY CONDS THEN PREVAIL THROUGH FRI AS HIGH PRES BUILDS
TOWARDS THE AREA. A LIGHT W-NW WIND IS EXPECTED TO ONCE AGAIN GIVE
WAY TO A SEABREEZE AT THE COAST DURING THE AFTN. HIGHS WILL BE A
FEW DEGREES WARMER THAN TODAY...GENERALLY MID TO UPPER 60S.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
H5 TROUGH/SHORTWAVE DEPARTS FRIDAY NIGHT. MODELS FAIRLY CONSISTENT
IN KEEPING THE REGION DRY...SO WILL NOT CARRY ANY POPS. STRONG SFC
HIGH PRES BUILDS OVER THE AREA SATURDAY...AND THEN MOVES OFFSHORE ON
SUNDAY. SEVERAL H5 TROUGHS/SHORTWAVES WILL MOVE INTO THE SOUTHEAST
U.S. FOR THE START OF THE NEW WEEK. HOWEVER...WITH THE HIGH OVER THE
GULF OF MAINE ON MONDAY...AND THEN OVER THE CANADIAN MARITIMES ON
TUESDAY...DO NOT THINK THE SHOWERS WILL MAKE IT TO MUCH OF THE
FORECAST AREA. BEST CHANCES WILL BE FOR ISOLATED SHOWERS OVER
WESTERN PORTIONS OF THE FORECAST AREA...BUT WILL KEEP THE FORECAST
DRY.
WITH THE HIGH BUILDING INTO THE AREA SATURDAY...A MODERATING AIRMASS
WILL ALLOW TEMPS TO WARM TO NEAR AND SLIGHTLY ABOVE NORMAL LEVELS
FOR THE WEEKEND AND INTO THE MIDDLE OF THE NEW WEEK. HIGHS WILL WARM
INTO THE MID/UPPER 60S...AND POSSIBLY INTO THE LOWER 70S OVER
WESTERN AREAS. SEABREEZES LIKELY EACH AFTERNOON ACROSS COASTAL AREAS
SATURDAY AND SUNDAY...AND THEN SEABREEZE ENHANCEMENTS LIKELY INTO
THE NEW WEEK DUE TO THE COMBINATION OF LIGHT GRADIENT WINDS...WARM
SFC TEMPS...AND RELATIVELY COLDER OCEAN/SOUND WATER TEMPS.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
HIGH PRESSURE BUILDS INTO THE REGION THIS AFTERNOON AND TONIGHT.
SEA BREEZES EXPECTED DURING THE 2ND HALF OF THIS AFTN WITH TYPICAL
SEA BREEZE WIND DIRECTIONS.
...NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KJFK FCSTER COMMENTS: WIND MOSTLY SOUTH OF 310 MAGNETIC. OCCASIONAL
GUSTS OF 16-19KT POSSIBLE BEFORE 19Z. MODERATE TO HIGH CONFIDENCE IN
SEA BREEZE OCCURRENCE. SEA BREEZE TIMING COULD BE AN HOUR OFF IN
EITHER DIRECTION.
KLGA FCSTER COMMENTS: WIND MOSTLY SOUTH OF 310 MAGNETIC. MODERATE
CONFIDENCE IN SEA BREEZE OCCURRENCE. SEA BREEZE TIMING COULD BE AN
HOUR OFF IN EITHER DIRECTION.
KEWR FCSTER COMMENTS: WIND MOSTLY SOUTH OF 310 MAGNETIC. MODERATE
CONFIDENCE IN SEA BREEZE OCCURRENCE. SEA BREEZE TIMING COULD BE AN
HOUR OFF IN EITHER DIRECTION..
KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
KHPN FCSTER COMMENTS: NO TACTICAL AMENDMENTS SCHEDULED AND NO
STRATEGIC AMENDMENTS EXPECTED.
KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
.OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...
.FRI NIGHT-SUN...VFR.
.MON...CHC CIGS BELOW 3000FT MAINLY AM HOURS.
.TUE...CHC CIGS BELOW 3000FT MAINLY AM HOURS.
&&
.MARINE...
NO CHANGES TO PREVIOUS HEADLINES. SEAS ON THE EXTREME EASTERN
PORTION OF ANZ350 MAY LINGER INTO THE EVE...BUT CONFIDENCE NOT
HIGH ENOUGH TO EXTEND AT THIS TIME.
A RELAXING PRESSURE GRADIENT OVER THE WATERS WILL PROMOTE SUB-SCA
CONDITIONS THEREAFTER.
HIGH PRES BUILDS OVER THE WATERS THIS WEEKEND AND WILL PERSIST
INTO THE START OF THE NEW WEEK. TRANQUIL CONDS EXPECTED ON ALL
WATERS AS A RESULT.
&&
.HYDROLOGY...
NO SIGNIFICANT PRECIPITATION IS EXPECTED INTO EARLY NEXT WEEK.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ350-
353-355.
&&
$$
SYNOPSIS...DS
NEAR TERM...DS
SHORT TERM...24
LONG TERM...MPS
AVIATION...JC
MARINE...24/MPS
HYDROLOGY...24/MPS
AREA FORECAST DISCUSSION...CORRECTED
NWS NEW YORK NY
1241 PM EDT THU APR 25 2013
.SYNOPSIS...
HIGH PRESSURE THEN BUILDS INTO THE REGION THROUGH THE WEEKEND AND
WILL PERSIST INTO THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
ADJUSTED HIGH TEMPERATURES DOWN FROM PREVIOUS FORECAST DUE TO
COLD ADVECTION CONTINUING THROUGH THE DAY AND RELATIVELY WEAK
WINDS IN THE LOWER LEVELS. USED THE LATEST 12Z NAM AND
INCORPORATED MIXING TO H85. ALONG THE COAST WHERE AFTERNOON SEA
BREEZE DEVELOPMENT IS ANTICIPATED...BLENDED IN THE LATEST RAP MODEL
MAX TEMPERATURES. THIS GIVES HIGHS IN THE UPPER 50S INLAND TO
LOWER 60S IN NYC AND LONG ISLAND. TEMPERATURES SHOULD BEGIN TO LEVEL
OFF ONCE THE SEA BREEZE PASSES AND BEGIN TO COOL WITH WINDS
TURNING TO THE SOUTH.
WINDS ARE STILL EXPECTED TO DIMINISH BY THE AFTERNOON TO 10 TO 15
MPH WITH A SUNNY SKY CONDITION.
OTHERWISE...FORECAST REMAINS ON TRACK.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
UPPER LEVEL TROUGH PASSES TO THE N TONIGHT. DO NOT EXPECT ANY
PCPN THIS FAR S...JUST A TEMPORARY INCREASE IN CLOUD COVER...
THEREFORE REMOVED SCHC POPS. LIGHT WINDS AND MOSTLY CLEAR SKIES
TONIGHT WILL ALLOW FOR GOOD RADIATIONAL COOLING CONDITIONS. IT
WILL BE CHILLY ONE ACROSS THE INTERIOR AND PINE BARRENS OF LONG
ISLAND...DROPPING INTO THE LOWER 30S. ELSEWHERE...OVERNIGHT LOWS
WILL BE SLIGHTLY BELOW NORMAL LEVELS IN THE UPPER 30S TO LOWER
40S...MID 40S IN METRO NYC/NJ.
FAIR AND DRY CONDS THEN PREVAIL THROUGH FRI AS HIGH PRES BUILDS
TOWARDS THE AREA. A LIGHT W-NW WIND IS EXPECTED TO ONCE AGAIN GIVE
WAY TO A SEABREEZE AT THE COAST DURING THE AFTN. HIGHS WILL BE A
FEW DEGREES WARMER THAN TODAY...GENERALLY MID TO UPPER 60S.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
H5 TROUGH/SHORTWAVE DEPARTS FRIDAY NIGHT. MODELS FAIRLY CONSISTENT
IN KEEPING THE REGION DRY...SO WILL NOT CARRY ANY POPS. STRONG SFC
HIGH PRES BUILDS OVER THE AREA SATURDAY...AND THEN MOVES OFFSHORE ON
SUNDAY. SEVERAL H5 TROUGHS/SHORTWAVES WILL MOVE INTO THE SOUTHEAST
U.S. FOR THE START OF THE NEW WEEK. HOWEVER...WITH THE HIGH OVER THE
GULF OF MAINE ON MONDAY...AND THEN OVER THE CANADIAN MARITIMES ON
TUESDAY...DO NOT THINK THE SHOWERS WILL MAKE IT TO MUCH OF THE
FORECAST AREA. BEST CHANCES WILL BE FOR ISOLATED SHOWERS OVER
WESTERN PORTIONS OF THE FORECAST AREA...BUT WILL KEEP THE FORECAST
DRY.
WITH THE HIGH BUILDING INTO THE AREA SATURDAY...A MODERATING AIRMASS
WILL ALLOW TEMPS TO WARM TO NEAR AND SLIGHTLY ABOVE NORMAL LEVELS
FOR THE WEEKEND AND INTO THE MIDDLE OF THE NEW WEEK. HIGHS WILL WARM
INTO THE MID/UPPER 60S...AND POSSIBLY INTO THE LOWER 70S OVER
WESTERN AREAS. SEABREEZES LIKELY EACH AFTERNOON ACROSS COASTAL AREAS
SATURDAY AND SUNDAY...AND THEN SEABREEZE ENHANCEMENTS LIKELY INTO
THE NEW WEEK DUE TO THE COMBINATION OF LIGHT GRADIENT WINDS...WARM
SFC TEMPS...AND RELATIVELY COLDER OCEAN/SOUND WATER TEMPS.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
HIGH PRESSURE BUILDS INTO THE REGION TODAY AND TONIGHT.
VFR. NW GUSTS SHOULD END BY AROUND 18Z. SEA BREEZES EXPECTED TO
DEVELOP DURING THE 2ND HALF OF THE AFTN FOR MOST TERMINALS WITH
TYPICAL SEA BREEZE WIND DIRECTIONS.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KJFK FCSTER COMMENTS: WIND MOSTLY NORTH OF 310 MAGNETIC UNTIL AROUND
17Z...THEN SOUTH OF IT THEREAFTER. GUSTS MIGHT BE ONLY OCCASIONAL
FROM 16-18Z. MODERATE TO HIGH CONFIDENCE IN SEA BREEZE OCCURRENCE.
SEA BREEZE TIMING COULD BE AN HOUR OFF IN EITHER DIRECTION.
KLGA FCSTER COMMENTS: WIND MOSTLY NORTH OF 310 MAGNETIC UNTIL AROUND
21-22Z...THEN SOUTH OF IT THEREAFTER. GUSTS MIGHT BE ONLY OCCASIONAL
FROM 16-18Z. MODERATE CONFIDENCE IN SEA BREEZE OCCURRENCE. SEA
BREEZE TIMING COULD BE AN HOUR OFF IN EITHER DIRECTION.
KEWR FCSTER COMMENTS: WIND MOSTLY NORTH OF 310 MAGNETIC UNTIL AROUND
17-18Z...THEN SOUTH OF IT THEREAFTER. GUSTS MIGHT BE ONLY OCCASIONAL
FROM 16-18Z. MODERATE CONFIDENCE IN SEA BREEZE OCCURRENCE. SEA
BREEZE TIMING COULD BE AN HOUR OFF IN EITHER DIRECTION..
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES
SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.
KTEB FCSTER COMMENTS: GUSTS MIGHT BE ONLY OCCASIONAL THROUGH 17Z.
KHPN FCSTER COMMENTS: GUSTS MIGHT BE ONLY OCCASIONAL THROUGH 17-18Z.
KISP FCSTER COMMENTS: GUSTY MIGHT BE ONLY OCCASIONAL FROM 16-18Z AND
MAY END ALTOGETHER NEAR 18Z. MODERATE TO HIGH CONFIDENCE IN SEA
BREEZE DEVELOPMENT.
.OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...
.FRI-MON...VFR.
&&
.MARINE...
SEAS WILL REMAIN ABOVE SCA LEVELS THROUGH MUCH OF THE DAY ON THE
OCEAN WATERS WITH GUSTS NEAR SCA LEVELS THIS MORNING BEHIND THE
FRONT. OCNL GUSTS UP TO 25 KT POSSIBLE FOR AN HOUR OR TWO ON
REMAINING WATERS. THEREFORE...NO CHANGES TO PREVIOUS HEADLINES.
SEAS ON THE EXTREME EASTERN PORTION OF ANZ350 MAY LINGER INTO THE
EVE...BUT CONFIDENCE NOT HIGH ENOUGH TO EXTEND AT THIS TIME.
A RELAXING PRESSURE GRADIENT OVER THE WATERS WILL PROMOTE SUB-SCA
CONDITIONS THEREAFTER.
HIGH PRES BUILDS OVER THE WATERS THIS WEEKEND AND WILL PERSIST
INTO THE START OF THE NEW WEEK. TRANQUIL CONDS EXPECTED ON ALL
WATERS AS A RESULT.
&&
.HYDROLOGY...
NO SIGNIFICANT PRECIPITATION IS EXPECTED INTO EARLY NEXT WEEK.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ350-
353-355.
&&
$$
SYNOPSIS...DS
NEAR TERM...DS
SHORT TERM...24
LONG TERM...MPS
AVIATION...JC
MARINE...24/MPS
HYDROLOGY...24/MPS
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1240 PM EDT THU APR 25 2013
.SYNOPSIS...
HIGH PRESSURE THEN BUILDS INTO THE REGION THROUGH THE WEEKEND AND
WILL PERSIST INTO THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
ADJUSTED HIGH TEMPERATURES DOWN FROM PREVIOUS FORECAST DUE TO
COLD ADVECTION CONTINUING THROUGH THE DAY AND RELATIVELY WEAK
WINDS IN THE LOWER LEVELS. USED THE LATEST 12Z NAM AND
INCORPORATED MIXING TO H85. ALONG THE COAST WHERE AFTERNOON SEA
BREEZE DEVELOPMENT IS ANTICIPATED...BLENDED IN THE LATEST RAP MODEL
MAX TEMPERATURES. THIS GIVES HIGHS IN THE UPPER 50S INLAND TO
LOWER 60S IN NYC AND LONG ISLAND. TEMPERATURES SHOULD BEGIN TO LEVEL
OFF ONCE THE SEA BREEZE PASSES AND BEGIN TO COOL WITH WINDS
TURNING TO THE SOUTH.
WINDS ARE STILL EXPECTED TO DIMINISH BY THE AFTERNOON TO 10 TO 15
MPH WITH A MOSTLY SUNNY SKY CONDITION.
OTHERWISE...FORECAST REMAINS ON TRACK.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
UPPER LEVEL TROUGH PASSES TO THE N TONIGHT. DO NOT EXPECT ANY
PCPN THIS FAR S...JUST A TEMPORARY INCREASE IN CLOUD COVER...
THEREFORE REMOVED SCHC POPS. LIGHT WINDS AND MOSTLY CLEAR SKIES
TONIGHT WILL ALLOW FOR GOOD RADIATIONAL COOLING CONDITIONS. IT
WILL BE CHILLY ONE ACROSS THE INTERIOR AND PINE BARRENS OF LONG
ISLAND...DROPPING INTO THE LOWER 30S. ELSEWHERE...OVERNIGHT LOWS
WILL BE SLIGHTLY BELOW NORMAL LEVELS IN THE UPPER 30S TO LOWER
40S...MID 40S IN METRO NYC/NJ.
FAIR AND DRY CONDS THEN PREVAIL THROUGH FRI AS HIGH PRES BUILDS
TOWARDS THE AREA. A LIGHT W-NW WIND IS EXPECTED TO ONCE AGAIN GIVE
WAY TO A SEABREEZE AT THE COAST DURING THE AFTN. HIGHS WILL BE A
FEW DEGREES WARMER THAN TODAY...GENERALLY MID TO UPPER 60S.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
H5 TROUGH/SHORTWAVE DEPARTS FRIDAY NIGHT. MODELS FAIRLY CONSISTENT
IN KEEPING THE REGION DRY...SO WILL NOT CARRY ANY POPS. STRONG SFC
HIGH PRES BUILDS OVER THE AREA SATURDAY...AND THEN MOVES OFFSHORE ON
SUNDAY. SEVERAL H5 TROUGHS/SHORTWAVES WILL MOVE INTO THE SOUTHEAST
U.S. FOR THE START OF THE NEW WEEK. HOWEVER...WITH THE HIGH OVER THE
GULF OF MAINE ON MONDAY...AND THEN OVER THE CANADIAN MARITIMES ON
TUESDAY...DO NOT THINK THE SHOWERS WILL MAKE IT TO MUCH OF THE
FORECAST AREA. BEST CHANCES WILL BE FOR ISOLATED SHOWERS OVER
WESTERN PORTIONS OF THE FORECAST AREA...BUT WILL KEEP THE FORECAST
DRY.
WITH THE HIGH BUILDING INTO THE AREA SATURDAY...A MODERATING AIRMASS
WILL ALLOW TEMPS TO WARM TO NEAR AND SLIGHTLY ABOVE NORMAL LEVELS
FOR THE WEEKEND AND INTO THE MIDDLE OF THE NEW WEEK. HIGHS WILL WARM
INTO THE MID/UPPER 60S...AND POSSIBLY INTO THE LOWER 70S OVER
WESTERN AREAS. SEABREEZES LIKELY EACH AFTERNOON ACROSS COASTAL AREAS
SATURDAY AND SUNDAY...AND THEN SEABREEZE ENHANCEMENTS LIKELY INTO
THE NEW WEEK DUE TO THE COMBINATION OF LIGHT GRADIENT WINDS...WARM
SFC TEMPS...AND RELATIVELY COLDER OCEAN/SOUND WATER TEMPS.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
HIGH PRESSURE BUILDS INTO THE REGION TODAY AND TONIGHT.
VFR. NW GUSTS SHOULD END BY AROUND 18Z. SEA BREEZES EXPECTED TO
DEVELOP DURING THE 2ND HALF OF THE AFTN FOR MOST TERMINALS WITH
TYPICAL SEA BREEZE WIND DIRECTIONS.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KJFK FCSTER COMMENTS: WIND MOSTLY NORTH OF 310 MAGNETIC UNTIL AROUND
17Z...THEN SOUTH OF IT THEREAFTER. GUSTS MIGHT BE ONLY OCCASIONAL
FROM 16-18Z. MODERATE TO HIGH CONFIDENCE IN SEA BREEZE OCCURRENCE.
SEA BREEZE TIMING COULD BE AN HOUR OFF IN EITHER DIRECTION.
KLGA FCSTER COMMENTS: WIND MOSTLY NORTH OF 310 MAGNETIC UNTIL AROUND
21-22Z...THEN SOUTH OF IT THEREAFTER. GUSTS MIGHT BE ONLY OCCASIONAL
FROM 16-18Z. MODERATE CONFIDENCE IN SEA BREEZE OCCURRENCE. SEA
BREEZE TIMING COULD BE AN HOUR OFF IN EITHER DIRECTION.
KEWR FCSTER COMMENTS: WIND MOSTLY NORTH OF 310 MAGNETIC UNTIL AROUND
17-18Z...THEN SOUTH OF IT THEREAFTER. GUSTS MIGHT BE ONLY OCCASIONAL
FROM 16-18Z. MODERATE CONFIDENCE IN SEA BREEZE OCCURRENCE. SEA
BREEZE TIMING COULD BE AN HOUR OFF IN EITHER DIRECTION..
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES
SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.
KTEB FCSTER COMMENTS: GUSTS MIGHT BE ONLY OCCASIONAL THROUGH 17Z.
KHPN FCSTER COMMENTS: GUSTS MIGHT BE ONLY OCCASIONAL THROUGH 17-18Z.
KISP FCSTER COMMENTS: GUSTY MIGHT BE ONLY OCCASIONAL FROM 16-18Z AND
MAY END ALTOGETHER NEAR 18Z. MODERATE TO HIGH CONFIDENCE IN SEA
BREEZE DEVELOPMENT.
.OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...
.FRI-MON...VFR.
&&
.MARINE...
SEAS WILL REMAIN ABOVE SCA LEVELS THROUGH MUCH OF THE DAY ON THE
OCEAN WATERS WITH GUSTS NEAR SCA LEVELS THIS MORNING BEHIND THE
FRONT. OCNL GUSTS UP TO 25 KT POSSIBLE FOR AN HOUR OR TWO ON
REMAINING WATERS. THEREFORE...NO CHANGES TO PREVIOUS HEADLINES.
SEAS ON THE EXTREME EASTERN PORTION OF ANZ350 MAY LINGER INTO THE
EVE...BUT CONFIDENCE NOT HIGH ENOUGH TO EXTEND AT THIS TIME.
A RELAXING PRESSURE GRADIENT OVER THE WATERS WILL PROMOTE SUB-SCA
CONDITIONS THEREAFTER.
HIGH PRES BUILDS OVER THE WATERS THIS WEEKEND AND WILL PERSIST
INTO THE START OF THE NEW WEEK. TRANQUIL CONDS EXPECTED ON ALL
WATERS AS A RESULT.
&&
.HYDROLOGY...
NO SIGNIFICANT PRECIPITATION IS EXPECTED INTO EARLY NEXT WEEK.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ350-
353-355.
&&
$$
SYNOPSIS...DS
NEAR TERM...DS
SHORT TERM...24
LONG TERM...MPS
AVIATION...JC
MARINE...24/MPS
HYDROLOGY...24/MPS
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
1030 AM EDT Thu Apr 25 2013
.NEAR TERM [Today and Tonight]...
Updated at: 1030 AM EDT
There has been decent coverage of light rain showers in the
Apalachicola River vicinity this morning, per TLH radar, and these
showers have continued to drift east to near a TLH-AAF line by 1430
UTC. For this reason, PoPs were increased into the higher "chance"
range for the aforementioned areas this morning and early this
afternoon. Not every location is likely to get measurable rain, but
most people from the Apalachicola River over to the Florida Big Bend
should see at least some sprinkles or drizzle. Because of the
continued cloud cover this morning, the temperatures were trended a
little bit cooler. If cloud cover lingers into the Noon hour, these
may need to be adjusted down a bit further. The best rain chances
will shift into the Florida Big Bend in the afternoon with the slow
moving cold front. RAP forecast MLCAPE is on the order of 500 j/kg,
so some thunder was also mentioned with the chances of rain showers.
Tonight, showers will drift south into the northern Gulf and
dissipate rather quickly. Expect temps to fall to near seasonal
averages across the southeast Big Bend tonight, and as low as 5 to
10 degrees below average across portions of Alabama and Georgia.
Generally, expect upper 40s to the NW, and upper 50s to the SE.
&&
.SHORT TERM [Friday Through Saturday]...
After a seasonably cool start to Friday morning, a mostly sunny and
pleasantly warm day is in store for the region, with highs reaching
the lower to middle 80s. By Saturday, however, a fairly diffuse (to
begin with) low pressure system will be approaching the CWA from the
west, and it will bring gradually increasing chances for showers and
storms to the region as the day wears on. Highs should still reach
the lower 80s in most areas, but the latter half of the weekend
could be a bit more unsettled. Also, it should be noted that no
strong to severe storms are expected on Saturday
&&
.LONG TERM [Saturday Night through Tuesday]...
This weekend, a low-amplitude mid-upper level trough is expected
to eject east from the southern Plains to the south Appalachians.
This trough is likely to evolve out of a closed low currently
(around 18 UTC Wednesday) situated off the southern California
coast. The increase in forcing for ascent should cause showers and
storms to gradually spread back into our area this weekend. After
that, the precise evolution of surface fronts is uncertain, but
some lingering boundaries and a continued moist and unstable
boundary layer should continue to support some isolated to
scattered convection into the early part of next week. With deep
westerly flow aloft across much of the southern latitudes of North
America, we should see a plume of steeper mid-level lapse rates
(associated with an elevated mixed layer from the Mexican plateaus
and desert Southwest) arrive by Sunday. The combination of steep
lapse rates, moderate instability, and deep layer shear around
30-40 knots suggests the potential for some stronger storms with
hail for Sunday, although things can certainly change by then.
&&
.AVIATION ...
A mixture of fog, but primarily low ceilings has overspread our
terminals this morning. IFR restrictions will likely linger for a
couple of hours before giving way to MVFR ceilings, and later this
afternoon a return to VFR. Terminals to the north and west will be
quicker to clear. There is a very slight chance for showers at KTLH
both this morning and then again later this afternoon. The
probabilities are too low to mention in the TAF. Tonight, most
terminals will remain VFR under clear skies, however there is a
slight chance for MVFR ceilings late tonight at KVLD.
&&
.MARINE...
Behind the passage of a diffuse Cold Front today, a favorable setup
for nocturnal surges out of the Northeast and East is expected to
impact the Coastal Waters tonight and Friday night. This is likely
to create a period of Cautionary conditions over the Marine area
into Saturday.
&&
.FIRE WEATHER...
Red Flag conditions are not anticipated today. On Friday, long
durations of low relative humidity may pose problems across portions
of southeast Alabama and the Florida Panhandle. By the weekend,
southerly flow will transport enough moisture inland to quell any
Red Flag concerns.
&&
.HYDROLOGY...
Although not too much rain is expected at this time, conditions will
gradually become more unsettled over the weekend into early next
week. Is is still much too early to speculate if there will be
enough rainfall to have an impact on area rivers.
&&
Tallahassee 81 51 84 54 83 / 40 0 0 0 20
Panama City 77 58 80 61 78 / 20 0 0 0 30
Dothan 77 48 82 52 81 / 10 0 0 0 40
Albany 79 48 82 52 80 / 10 0 0 0 20
Valdosta 83 52 83 52 82 / 30 0 0 0 20
Cross City 84 57 85 54 84 / 20 10 10 0 20
Apalachicola 77 59 79 62 76 / 30 10 0 0 20
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...Lamers/Harrigan
SHORT TERM...Gould
LONG TERM...Lamers
AVIATION...Harrigan
MARINE...Gould
FIRE WEATHER...Harrigan
HYDROLOGY...Gould
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1202 AM CDT THU APR 25 2013
.SHORT TERM.../TONIGHT /...
ISSUED AT 419 PM CDT WED APR 24 2013
FORECAST CONCERN FOR LATE AFTERNOON AND TONIGHT WILL REVOLVE AROUND
PRECIPITATION CHANCES. APPROACHING COLD FRONT WITH STRONG PV
ANOMALY...CURRENTLY LEADING TO PRECIPITATION IN SOUTH DAKOTA...WILL
SPREAD SE INTO IOWA THIS EVENING. SYSTEM WILL BE QUICK MOVING...AND
ANTICIPATE BAND OF SHOWERS TO SWEEP QUICKLY ACROSS THE
AREA...SIMILAR TO HRRR TIMING/TREND. WITH SKIES REMAINING CLEAR
ACROSS CENTRAL IOWA...NO CU FIELD NOTED...AND HIGH DEW POINT
DEPRESSIONS...DO NOT ANTICIPATE DEVELOPMENT AHEAD OF LINE.
HOWEVER...SOME MU CAPE WILL LEAD TO ISOLATED THUNDER NEAR FRONT.
PRECIPITATION ENDS QUICKLY BEHIND FROPA WITH SUBSIDENCE. HAVE KEPT
TEMPERATURES COOLER ACROSS THE NORTH ESPECIALLY...DROPPING OFF
QUICKLY BEHIND FROPA...MAY SEE SOME LIGHT RN/SN MIX ACROSS THE NORTH
AFTER MIDNIGHT WITH ANY LINGERING PRECIPITATION.
.LONG TERM.../THURSDAY THROUGH WEDNESDAY/...
ISSUED AT 419 PM CDT WED APR 24 2013
A FAIRLY QUIET...AND MUCH...MUCH WARMER WEATHER PATTERN IS SETTING
UP ACROSS THE MIDWEST FOR THE NEXT COUPLE OF DAYS. UNDER THE
INFLUENCE OF HIGH PRESSURE...THURSDAY AFTERNOON LOOKS TO BE VERY
SIMILAR TO WEDNESDAY...JUST A FEW DEGREES WARMER AND A FEW MORE
CLOUDS.
HEADING INTO FRIDAY...A NOTABLE THERMAL RIDGE WILL BEGIN TO BUILD
ALL THE WAY UP OVER THE DAKOTAS AND INTO CANADA. 850MB TEMPERATURES
LOOK TO MAKE IT UP TO AROUND 8C...SETTING UP THE POTENTIAL FOR SOME
OF THE WARMEST TEMPERATURES THUS FAR OF 2013 TO BE ADVECTED INTO THE
CWA...WHEN THE THERMAL RIDGE SHIFTS EASTWARD BEGINNING SATURDAY.
STICKING TO FRIDAY...A WEAK SURFACE TROUGH WILL PUSH THROUGH THE
MIDWEST. THE GFS AND NAM BOTH HINT AT CAPE VALUES MAKING IT TO
AROUND 300 J/KG...BUT WINDS ALOFT ARE QUITE WEAK...AND THE BOUNDARY
ITSELF IS FAIRLY WEAK...SO NOT MUCH PRESENT IN TERMS OF FOCUSING
MECHANISMS TO GENERATE ANY CONFIDENCE IN THUNDERSTORM DEVELOPMENT.
SATURDAY AND SUNDAY...BOTH DAYS SHOULD BE SIMILAR WEATHER WISE AS
THE AFOREMENTIONED THERMAL RIDGE SHIFTS EASTWARD. 850 MB TEMPS WILL
GO FROM AROUND 8C IN CENTRAL IOWA...TO AROUND 10C ON SATURDAY...TO
AROUND 14C ON SUNDAY. LOTS OF DRY AIR ALOFT WILL SUPPORT MAINLY
SUNNY SKIES ON BOTH SATURDAY AND SUNDAY.
THE WEATHER PATTERN CHANGES AS WE HEAD INTO MONDAY AND TUESDAY. WE
WILL BE WATCHING FOR THE POTENTIAL FOR AFTERNOON THUNDERSTORMS ON
BOTH DAYS. AS OF NOW...TUESDAY LOOKS LIKE THE BETTER OF THE TWO DAYS
FOR THUNDERSTORM DEVELOPMENT. AS A SIZABLE AREA OF LOW PRESSURE SETS
UP TO MOVE THROUGH THE DAKOTAS...MONDAY FEATURES A WARM FRONT
PASSING THROUGH IOWA TOWARDS WISCONSIN. THERE IS SOME INSTABILITY
EXPECTED AS WE WILL CERTAINLY BE UNDER THE WAA ADVECTION OF THE
THERMAL RIDGE...BUT AS OF NOW...IT APPEARS THE CAP WILL BE DIFFICULT
TO BREAK. FOR TUESDAY INTO WEDNESDAY...A COLD FRONT IS PROGGED TO
PASS THROUGH IOWA. THE GFS SEEMS TO BE A BIT FAST VERSUS THE REST OF
THE MODELS...SO ARE TRENDING THE PASSING OF THE FROPA BACK INTO
WEDNESDAY.
&&
.AVIATION...25/06Z
ISSUED AT 1159 PM CDT WED APR 24 2013
CDFNT HAS CLEARED ALL BUT THE KOTM AREA AND WILL BE PAST THEM BY
07Z. A FEW LINGERING SHOWERS...BUT THAT WILL END. SOME MVFR STRATOCU
WILL MOVE THROUGH HE KMCW AND KALO AREAS BEFORE 09Z. THE REST OF
THE TAF PERIOD AT ALL SITES WILL BE VFR. HIGH PRESSURE RIDGE WILL
ACROSS THE STATE THU. WNWLY WINDS WILL BECOME SW-SLY IN THE
AFTERNOON AND SLY AFTER SUNSET.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...AWB
LONG TERM...KOTENBERG
AVIATION...MS APR 13
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
609 PM EDT THU APR 25 2013
.SYNOPSIS...
ISOLATED TO SCATTERED SHOWERS WILL QUICKLY SHIFT EASTWARD BEFORE
MIDNIGHT. AFTER A COOL MORNING...HIGH PRESSURE WITH SUNSHINE WILL
QUICKLY RETURN TEMPERATURES TO SEASONAL LEVELS FOR FRIDAY AND SATURDAY.
&&
.NEAR TERM /THROUGH FRIDAY/...
AREA OF SCT SHOWERS UNDER A CROSSING SHORTWAVE...BEST EXHIBITED
VIA UAA OR RAP MDL DEPICTION OF MID LVL THERMAL TROF...WL QUICKLY
SHIFT EWD AS THE EVE PROGRESSES.
DRY HIGH PRESSURE WL BUILD OVRNGT...CLEARING THE SKY AND CALMING THE
WIND. CONDITIONS LK TO BE SUFFICIENTLY LONG FOR A CPL HOURS OF
FREEZING TEMPS OR AREAS OF FROST. FROST ADVISORY THUS REMAINS IN
EFFECT FOR AREAS WHERE SPRING HEADLINES HAVE STARTED AFTER
CONSULTATIONS WITH LOCAL GROWERS...I.E. GENERALLY WEST OF THE
RIDGES AND SOUTH OF THE PA TURNPIKE.
WITH ABUNDANT INSOLATION...FRIDAY TEMPS ARE EXPECTED TO RECOVER TO
NEAR THE SEASONAL AVERAGES.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
DRY AND SEASONABLE WEA WL CONT AS SURFACE RIDGE SHIFTS EAST
THROUGH SATURDAY. FOR SATURDAY NIGHT AND SUNDAY...CLOUDS WILL BE
INCREASING AS A SOUTHERN STREAM SHORTWAVE MOVES TOWARD THE UPPER
OHIO VALLEY. POPS WERE LIMITED TO CHC NMBRS FOR SUNDAY AS BEST
MOISTURE AND LIFT ARE PROJECTED TO STAY SOUTH OF REGION.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
A WK SHRTWV WL MOVE ACRS THE OH VLY SUN NGT INTO MONDAY CONTG THE CHC
OF SHOWERS. HIGH PRESSURE IS THEN FORECAST TO BUILD WITH DRY WEA
AND WARMER TEMPS INTO MIDWEEK. RAIN CHCS WL INCRS THEREAFTER AS
TROFFING DVLPS OVR THE GREAT LAKES.
&&
.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
A FAST MOVING SHORTWAVE WL CONT TO SPPRT SCT -SHRA OVR THE REGION
THIS EVE...BUT RESTRICTIONS ARE EXPECTED TO BE ISOLD. BLDG HIGH
PRES IN THE WAKE OF THAT SYS WL LEAD TO GENL VFR FOR THE RMNDR OF
THE TAF PD.
.OUTLOOK.../TONIGHT THROUGH TUESDAY/...
GENL VFR CONDS ARE EXPECTED THRU SAT NGT. SHRA AND RESULTING RESTRICTIONS
ARE PSBL SUN INTO MONDAY WITH A WK WAVE OF LOW PRES...BUT HIGH
PRES IS FORECAST TO QUICKLY REBUILD AND RTN VFR FOR MON NGT INTO
TUE.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...FROST ADVISORY FROM 3 AM TO 9 AM EDT FRIDAY FOR OHZ039>041-
048>050-057>059-068-069.
PA...FROST ADVISORY FROM 3 AM TO 9 AM EDT FRIDAY FOR PAZ020-021-029-
031-073-075.
WV...FROST ADVISORY FROM 3 AM TO 9 AM EDT FRIDAY FOR WVZ001>004-012-
021-022.
&&
$$
15
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1230 PM EDT THU APR 25 2013
.SYNOPSIS...
ISSUED AT 330 AM EDT THU APR 25 2013
LOW PRESSURE WILL MOVE THROUGH LOWER MICHIGAN TODAY PRODUCING A
PERIOD OF MIXED RAIN AND SNOW. LITTLE IF ANY ACCUMULATION IS
EXPECTED AND SKIES WILL CLEAR LATE IN THE DAY. A CHILLY DAY IS
EXPECTED WITH HIGHS IN THE 40S. GENERALLY DRY WEATHER IS EXPECTED
THROUGH THE WEEKEND AND TEMPERATURES WILL CLIMB INTO THE 70S EARLY
NEXT WEEK.
&&
.UPDATE...
ISSUED AT 1159 AM EDT THU APR 25 2013
I ADDED ISOLATED THUNDERSTORMS TO OUR FORECAST FOR EASTERN CWA
THIS AFTERNOON. THAT WAS LARGELY BASED ON RAP AND NAM12 SOUNDING
WHICH SHOW ENOUGH INSTABILITY (200-400 J/KG) TO GET CLOUD TOPS TO
NEAR 20000 FT. THAT IS MORE THAN ENOUGH TO GET ECHO HEIGHTS ABOVE
THE -20C HEIGHT (12000 FT). DRY AIR AT MID LEVELS IS COMING IN
FROM THE WEST SO THERE IS ONLY A NARROW WINDOW OF TIME THEN THERE
IS ENOUGH MOISTURE AT MID LEVELS FOR THE CLOUDS TO DEVELOP
CONVECTION (MOSTLY PRIOR TO 21Z). ALSO THE SPC 09Z SREF SHOWS A 10
TO 20 PCT CHANCE OF THUNDERSTORMS WITHIN 3 HOURS OVER THE EASTERN
HALF OF LOWER MICHIGAN BETWEEN 2 PM AND 5 PM.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 330 AM EDT THU APR 25 2013
FORECAST CONCERNS DEAL WITH PCPN CHANCES TODAY. WV LOOP SHOWS A
STRONG SHORT WAVE MOVING ACROSS WISCONSIN. RADAR ISN/T TOO
IMPRESSIVE WITH THIS WAVE. HOWEVER WITH MODEL TRENDS SHOWING AN
UPTICK IN STRENGTH AS IT APPROACHES WE MAY SEE THAT REFLECTED IN AN
EXPANDED AREAL COVERAGE OF PCPN. THERE HAS BEEN SOME SNOW OVER NRN
WISCONSIN WITH RAIN EXTENDING SOUTH INTO ILLINOIS. FCST SOUNDINGS
WOULD SUGGEST THE POSSIBILITY OF MIXED RAIN AND SNOW TODAY. IF A
HEAVIER CONVECTIVE CELL DEVELOPS IT/S POSSIBLE THAT THE GROUND COULD
BECOME BRIEFLY WHITE IN LOCALIZED AREAS. LATEST HRRR SHOWS PCPN
ENDING SHORTLY AFTER 18Z OVER THE ERN CWA. TEMPS TODAY WILL TOP OUT
IN THE 40S.
ANOTHER WEAKER SHORTWAVE WILL MOVE ACROSS NRN LWR FRIDAY. I/M NOT
CONVINCED IT/S STRONG ENOUGH TO PRODUCE PCPN OVER THE CWA SO WE
OPTED FOR DRY GRIDS FRIDAY. A STRONGER WAVE WILL PASS BY TO THE
SOUTH SATURDAY. ATTM IT APPEARS AS THOUGH PCPN WILL FALL SOUTH OF
THE CWA. UNDER QUASI ZONAL FLOW...TEMPS WILL GRADUALLY WARM INTO THE
60S BY SATURDAY.
.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 330 AM EDT THU APR 25 2013
FINALLY A PERIOD OF ABOVE NORMAL TEMPERATURES CAN BE EXPECTED SUNDAY
THROUGH WEDNESDAY AS HEIGHTS RISE AHEAD OF A DIGGING/EVOLVING TROUGH
OVER THE NORTH CENTRAL UNITED STATES. HIGH TEMPERATURES OF 70 TO 75
ARE FORECAST.
WHILE MUCH OF THE LONG TERM PERIOD SHOULD BE DRY THERE ARE A FEW
THINGS TO WATCH. THE FIRST IS A SHORTWAVE WHICH IS PROGGED TO MOVE
THROUGH THE OHIO VALLEY REGION ON SUNDAY. MODELS HAVE BEEN TRYING TO
SQUEEZE OUT SOME LIGHT PRECIP ACROSS SRN LWR MI IN RESPONSE TO THIS
FEATURE BUT HAVE LEFT THE FCST DRY.
THE NEXT FEATURE WHICH COULD PRODUCE A FEW SHOWERS IS A FRONTAL
BOUNDARY APPROACHING FROM THE NORTHWEST ON MONDAY AND MONDAY NIGHT.
THIS WEAKENING/SLOWING FRONT MAY EVENTUALLY STALL OVERHEAD ON
TUESDAY BEFORE LIFTING BACK TO THE NORTH ON TUESDAY NIGHT/WEDNESDAY.
WILL HAVE SOME CHC POPS MONDAY AND MONDAY NIGHT... MAINLY IN THE
WRN AND NRN CWFA... BUT LEFT TUESDAY DRY FOR NOW SINCE RIDGING
ALOFT LOOKS TO BECOME BETTER ESTABLISHED DURING THIS TIME. THIS
RIDGING WILL PROBABLY RESULT IN A SLOWER ARRIVAL OF THE UPSTREAM
TROUGH DURING THE MID WEEK PERIOD...BUT WILL CARRY LOW CHC POPS ON
WEDNESDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY)
ISSUED AT 1230 PM EDT THU APR 25 2013
MVFR/VFR CONDITIONS ARE ANTICIPATED THIS AFTERNOON WITH SOME
LINGERING SHOWERS THROUGH MID AFTERNOON AT OUR SE TERMINALS (KLAN...
KJXN... KBTL AND KAZO). CONDITIONS WILL GRADUALLY IMPROVE TO VFR AT
ALL THE TERMINALS THIS EVENING AS SKIES CLEAR.
WEST WINDS WILL GUST TO AROUND 25 KTS THIS AFTN BEFORE SUBSIDING
QUICKLY THIS EVENING. WINDS WILL BACK TO THE SOUTH OVERNIGHT AND
THEN INCREASE TO 15 TO 20 KTS BY LATE FRIDAY MORNING.
&&
.MARINE...
ISSUED AT 330 AM EDT THU APR 25 2013
GUSTY WINDS EXPECTED WITH THE PASSAGE OF THE SHORT WAVE TODAY. THIS
WILL NECESSITATE THE ISSUANCE OF A SCA.
&&
.HYDROLOGY...
ISSUED AT 330 AM EDT THU APR 25 2013
RIVERS WILL CONTINUE TO FALL THROUGH THE WEEKEND. TODAY/S PCPN WILL
BE UNDER A TENTH AND WILL HAVE LITTLE EFFECT ON RIVER LEVELS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...93
SHORT TERM...93
LONG TERM...MEADE
AVIATION...LAURENS
HYDROLOGY...93
MARINE...93
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1158 AM EDT THU APR 25 2013
.SYNOPSIS...
ISSUED AT 330 AM EDT THU APR 25 2013
LOW PRESSURE WILL MOVE THROUGH LOWER MICHIGAN TODAY PRODUCING A
PERIOD OF MIXED RAIN AND SNOW. LITTLE IF ANY ACCUMULATION IS
EXPECTED AND SKIES WILL CLEAR LATE IN THE DAY. A CHILLY DAY IS
EXPECTED WITH HIGHS IN THE 40S. GENERALLY DRY WEATHER IS EXPECTED
THROUGH THE WEEKEND AND TEMPERATURES WILL CLIMB INTO THE 70S EARLY
NEXT WEEK.
&&
.UPDATE...
ISSUED AT 1159 AM EDT THU APR 25 2013
I ADDED ISOLATED THUNDERSTORMS TO OUR FORECAST FOR EASTERN CWA
THIS AFTERNOON. THAT WAS LARGELY BASED ON RAP AND NAM12 SOUNDING
WHICH SHOW ENOUGH INSTABILITY (200-400 J/KG) TO GET CLOUD TOPS TO
NEAR 20000 FT. THAT IS MORE THAN ENOUGH TO GET ECHO HEIGHTS ABOVE
THE -20C HEIGHT (12000 FT). DRY AIR AT MID LEVELS IS COMING IN
FROM THE WEST SO THERE IS ONLY A NARROW WINDOW OF TIME THEN THERE
IS ENOUGH MOISTURE AT MID LEVELS FOR THE CLOUDS TO DEVELOP
CONVECTION (MOSTLY PRIOR TO 21Z). ALSO THE SPC 09Z SREF SHOWS A 10
TO 20 PCT CHANCE OF THUNDERSTORMS WITHIN 3 HOURS OVER THE EASTERN
HALF OF LOWER MICHIGAN BETWEEN 2 PM AND 5 PM.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 330 AM EDT THU APR 25 2013
FORECAST CONCERNS DEAL WITH PCPN CHANCES TODAY. WV LOOP SHOWS A
STRONG SHORT WAVE MOVING ACROSS WISCONSIN. RADAR ISN/T TOO
IMPRESSIVE WITH THIS WAVE. HOWEVER WITH MODEL TRENDS SHOWING AN
UPTICK IN STRENGTH AS IT APPROACHES WE MAY SEE THAT REFLECTED IN AN
EXPANDED AREAL COVERAGE OF PCPN. THERE HAS BEEN SOME SNOW OVER NRN
WISCONSIN WITH RAIN EXTENDING SOUTH INTO ILLINOIS. FCST SOUNDINGS
WOULD SUGGEST THE POSSIBILITY OF MIXED RAIN AND SNOW TODAY. IF A
HEAVIER CONVECTIVE CELL DEVELOPS IT/S POSSIBLE THAT THE GROUND COULD
BECOME BRIEFLY WHITE IN LOCALIZED AREAS. LATEST HRRR SHOWS PCPN
ENDING SHORTLY AFTER 18Z OVER THE ERN CWA. TEMPS TODAY WILL TOP OUT
IN THE 40S.
ANOTHER WEAKER SHORTWAVE WILL MOVE ACROSS NRN LWR FRIDAY. I/M NOT
CONVINCED IT/S STRONG ENOUGH TO PRODUCE PCPN OVER THE CWA SO WE
OPTED FOR DRY GRIDS FRIDAY. A STRONGER WAVE WILL PASS BY TO THE
SOUTH SATURDAY. ATTM IT APPEARS AS THOUGH PCPN WILL FALL SOUTH OF
THE CWA. UNDER QUASI ZONAL FLOW...TEMPS WILL GRADUALLY WARM INTO THE
60S BY SATURDAY.
.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 330 AM EDT THU APR 25 2013
FINALLY A PERIOD OF ABOVE NORMAL TEMPERATURES CAN BE EXPECTED SUNDAY
THROUGH WEDNESDAY AS HEIGHTS RISE AHEAD OF A DIGGING/EVOLVING TROUGH
OVER THE NORTH CENTRAL UNITED STATES. HIGH TEMPERATURES OF 70 TO 75
ARE FORECAST.
WHILE MUCH OF THE LONG TERM PERIOD SHOULD BE DRY THERE ARE A FEW
THINGS TO WATCH. THE FIRST IS A SHORTWAVE WHICH IS PROGGED TO MOVE
THROUGH THE OHIO VALLEY REGION ON SUNDAY. MODELS HAVE BEEN TRYING TO
SQUEEZE OUT SOME LIGHT PRECIP ACROSS SRN LWR MI IN RESPONSE TO THIS
FEATURE BUT HAVE LEFT THE FCST DRY.
THE NEXT FEATURE WHICH COULD PRODUCE A FEW SHOWERS IS A FRONTAL
BOUNDARY APPROACHING FROM THE NORTHWEST ON MONDAY AND MONDAY NIGHT.
THIS WEAKENING/SLOWING FRONT MAY EVENTUALLY STALL OVERHEAD ON
TUESDAY BEFORE LIFTING BACK TO THE NORTH ON TUESDAY NIGHT/WEDNESDAY.
WILL HAVE SOME CHC POPS MONDAY AND MONDAY NIGHT... MAINLY IN THE
WRN AND NRN CWFA... BUT LEFT TUESDAY DRY FOR NOW SINCE RIDGING
ALOFT LOOKS TO BECOME BETTER ESTABLISHED DURING THIS TIME. THIS
RIDGING WILL PROBABLY RESULT IN A SLOWER ARRIVAL OF THE UPSTREAM
TROUGH DURING THE MID WEEK PERIOD...BUT WILL CARRY LOW CHC POPS ON
WEDNESDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 747 AM EDT THU APR 25 2013
NUMEROUS MVFR CIGS/VSBYS CAN BE EXPECTED THIS MORNING AS RAIN
SHOWERS MOVE FROM WEST TO EAST. A PERIOD OF IFR CANNOT BE RULED
OUT AS WELL... ESPECIALLY AT GRR FROM 12Z TO 14Z AS A BAND OF
HEAVIER PRECIP POSSIBLY MIXED WITH SNOW MOVES THROUGH.
CONDITIONS SHOULD TREND TOWARD VFR THIS AFTERNOON BEHIND THE SFC
COLD FRONT BUT WEST WINDS WILL REMAIN RATHER STRONG WITH GUSTS TO
25 KTS. VFR IS LIKELY TONIGHT AS WINDS DIMINISH TO UNDER 10KTS.
&&
.MARINE...
ISSUED AT 330 AM EDT THU APR 25 2013
GUSTY WINDS EXPECTED WITH THE PASSAGE OF THE SHORT WAVE TODAY. THIS
WILL NECESSITATE THE ISSUANCE OF A SCA.
&&
.HYDROLOGY...
ISSUED AT 330 AM EDT THU APR 25 2013
RIVERS WILL CONTINUE TO FALL THROUGH THE WEEKEND. TODAY/S PCPN WILL
BE UNDER A TENTH AND WILL HAVE LITTLE EFFECT ON RIVER LEVELS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...93
SHORT TERM...93
LONG TERM...MEADE
AVIATION...MEADE
HYDROLOGY...93
MARINE...93
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
748 AM EDT THU APR 25 2013
.SYNOPSIS...
ISSUED AT 330 AM EDT THU APR 25 2013
LOW PRESSURE WILL MOVE THROUGH LOWER MICHIGAN TODAY PRODUCING A
PERIOD OF MIXED RAIN AND SNOW. LITTLE IF ANY ACCUMULATION IS
EXPECTED AND SKIES WILL CLEAR LATE IN THE DAY. A CHILLY DAY IS
EXPECTED WITH HIGHS IN THE 40S. GENERALLY DRY WEATHER IS EXPECTED
THROUGH THE WEEKEND AND TEMPERATURES WILL CLIMB INTO THE 70S EARLY
NEXT WEEK.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 330 AM EDT THU APR 25 2013
FORECAST CONCERNS DEAL WITH PCPN CHANCES TODAY. WV LOOP SHOWS A
STRONG SHORT WAVE MOVING ACROSS WISCONSIN. RADAR ISN/T TOO
IMPRESSIVE WITH THIS WAVE. HOWEVER WITH MODEL TRENDS SHOWING AN
UPTICK IN STRENGTH AS IT APPROACHES WE MAY SEE THAT REFLECTED IN AN
EXPANDED AREAL COVERAGE OF PCPN. THERE HAS BEEN SOME SNOW OVER NRN
WISCONSIN WITH RAIN EXTENDING SOUTH INTO ILLINOIS. FCST SOUNDINGS
WOULD SUGGEST THE POSSIBILITY OF MIXED RAIN AND SNOW TODAY. IF A
HEAVIER CONVECTIVE CELL DEVELOPS IT/S POSSIBLE THAT THE GROUND COULD
BECOME BRIEFLY WHITE IN LOCALIZED AREAS. LATEST HRRR SHOWS PCPN
ENDING SHORTLY AFTER 18Z OVER THE ERN CWA. TEMPS TODAY WILL TOP OUT
IN THE 40S.
ANOTHER WEAKER SHORTWAVE WILL MOVE ACROSS NRN LWR FRIDAY. I/M NOT
CONVINCED IT/S STRONG ENOUGH TO PRODUCE PCPN OVER THE CWA SO WE
OPTED FOR DRY GRIDS FRIDAY. A STRONGER WAVE WILL PASS BY TO THE
SOUTH SATURDAY. ATTM IT APPEARS AS THOUGH PCPN WILL FALL SOUTH OF
THE CWA. UNDER QUASI ZONAL FLOW...TEMPS WILL GRADUALLY WARM INTO THE
60S BY SATURDAY.
.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 330 AM EDT THU APR 25 2013
FINALLY A PERIOD OF ABOVE NORMAL TEMPERATURES CAN BE EXPECTED SUNDAY
THROUGH WEDNESDAY AS HEIGHTS RISE AHEAD OF A DIGGING/EVOLVING TROUGH
OVER THE NORTH CENTRAL UNITED STATES. HIGH TEMPERATURES OF 70 TO 75
ARE FORECAST.
WHILE MUCH OF THE LONG TERM PERIOD SHOULD BE DRY THERE ARE A FEW
THINGS TO WATCH. THE FIRST IS A SHORTWAVE WHICH IS PROGGED TO MOVE
THROUGH THE OHIO VALLEY REGION ON SUNDAY. MODELS HAVE BEEN TRYING TO
SQUEEZE OUT SOME LIGHT PRECIP ACROSS SRN LWR MI IN RESPONSE TO THIS
FEATURE BUT HAVE LEFT THE FCST DRY.
THE NEXT FEATURE WHICH COULD PRODUCE A FEW SHOWERS IS A FRONTAL
BOUNDARY APPROACHING FROM THE NORTHWEST ON MONDAY AND MONDAY NIGHT.
THIS WEAKENING/SLOWING FRONT MAY EVENTUALLY STALL OVERHEAD ON
TUESDAY BEFORE LIFTING BACK TO THE NORTH ON TUESDAY NIGHT/WEDNESDAY.
WILL HAVE SOME CHC POPS MONDAY AND MONDAY NIGHT... MAINLY IN THE
WRN AND NRN CWFA... BUT LEFT TUESDAY DRY FOR NOW SINCE RIDGING
ALOFT LOOKS TO BECOME BETTER ESTABLISHED DURING THIS TIME. THIS
RIDGING WILL PROBABLY RESULT IN A SLOWER ARRIVAL OF THE UPSTREAM
TROUGH DURING THE MID WEEK PERIOD...BUT WILL CARRY LOW CHC POPS ON
WEDNESDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 747 AM EDT THU APR 25 2013
NUMEROUS MVFR CIGS/VSBYS CAN BE EXPECTED THIS MORNING AS RAIN
SHOWERS MOVE FROM WEST TO EAST. A PERIOD OF IFR CANNOT BE RULED
OUT AS WELL... ESPECIALLY AT GRR FROM 12Z TO 14Z AS A BAND OF
HEAVIER PRECIP POSSIBLY MIXED WITH SNOW MOVES THROUGH.
CONDITIONS SHOULD TREND TOWARD VFR THIS AFTERNOON BEHIND THE SFC
COLD FRONT BUT WEST WINDS WILL REMAIN RATHER STRONG WITH GUSTS TO
25 KTS. VFR IS LIKELY TONIGHT AS WINDS DIMINISH TO UNDER 10KTS.
&&
.MARINE...
ISSUED AT 330 AM EDT THU APR 25 2013
GUSTY WINDS EXPECTED WITH THE PASSAGE OF THE SHORT WAVE TODAY. THIS
WILL NECESSITATE THE ISSUANCE OF A SCA.
&&
.HYDROLOGY...
ISSUED AT 330 AM EDT THU APR 25 2013
RIVERS WILL CONTINUE TO FALL THROUGH THE WEEKEND. TODAY/S PCPN WILL
BE UNDER A TENTH AND WILL HAVE LITTLE EFFECT ON RIVER LEVELS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR LMZ844>849.
&&
$$
SYNOPSIS...93
SHORT TERM...93
LONG TERM...MEADE
AVIATION...MEADE
HYDROLOGY...93
MARINE...93
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
330 AM EDT THU APR 25 2013
.SYNOPSIS...
ISSUED AT 330 AM EDT THU APR 25 2013
LOW PRESSURE WILL MOVE THROUGH LOWER MICHIGAN TODAY PRODUCING A
PERIOD OF MIXED RAIN AND SNOW. LITTLE IF ANY ACCUMULATION IS
EXPECTED AND SKIES WILL CLEAR LATE IN THE DAY. A CHILLY DAY IS
EXPECTED WITH HIGHS IN THE 40S. GENERALLY DRY WEATHER IS EXPECTED
THROUGH THE WEEKEND AND TEMPERATURES WILL CLIMB INTO THE 70S EARLY
NEXT WEEK.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 330 AM EDT THU APR 25 2013
FORECAST CONCERNS DEAL WITH PCPN CHANCES TODAY. WV LOOP SHOWS A
STRONG SHORT WAVE MOVING ACROSS WISCONSIN. RADAR ISN/T TOO
IMPRESSIVE WITH THIS WAVE. HOWEVER WITH MODEL TRENDS SHOWING AN
UPTICK IN STRENGTH AS IT APPROACHES WE MAY SEE THAT REFLECTED IN AN
EXPANDED AREAL COVERAGE OF PCPN. THERE HAS BEEN SOME SNOW OVER NRN
WISCONSIN WITH RAIN EXTENDING SOUTH INTO ILLINOIS. FCST SOUNDINGS
WOULD SUGGEST THE POSSIBILITY OF MIXED RAIN AND SNOW TODAY. IF A
HEAVIER CONVECTIVE CELL DEVELOPS IT/S POSSIBLE THAT THE GROUND COULD
BECOME BRIEFLY WHITE IN LOCALIZED AREAS. LATEST HRRR SHOWS PCPN
ENDING SHORTLY AFTER 18Z OVER THE ERN CWA. TEMPS TODAY WILL TOP OUT
IN THE 40S.
ANOTHER WEAKER SHORTWAVE WILL MOVE ACROSS NRN LWR FRIDAY. I/M NOT
CONVINCED IT/S STRONG ENOUGH TO PRODUCE PCPN OVER THE CWA SO WE
OPTED FOR DRY GRIDS FRIDAY. A STRONGER WAVE WILL PASS BY TO THE
SOUTH SATURDAY. ATTM IT APPEARS AS THOUGH PCPN WILL FALL SOUTH OF
THE CWA. UNDER QUASI ZONAL FLOW...TEMPS WILL GRADUALLY WARM INTO THE
60S BY SATURDAY.
.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 330 AM EDT THU APR 25 2013
FINALLY A PERIOD OF ABOVE NORMAL TEMPERATURES CAN BE EXPECTED SUNDAY
THROUGH WEDNESDAY AS HEIGHTS RISE AHEAD OF A DIGGING/EVOLVING TROUGH
OVER THE NORTH CENTRAL UNITED STATES. HIGH TEMPERATURES OF 70 TO 75
ARE FORECAST.
WHILE MUCH OF THE LONG TERM PERIOD SHOULD BE DRY THERE ARE A FEW
THINGS TO WATCH. THE FIRST IS A SHORTWAVE WHICH IS PROGGED TO MOVE
THROUGH THE OHIO VALLEY REGION ON SUNDAY. MODELS HAVE BEEN TRYING TO
SQUEEZE OUT SOME LIGHT PRECIP ACROSS SRN LWR MI IN RESPONSE TO THIS
FEATURE BUT HAVE THE LEFT THE FCST DRY.
THE NEXT FEATURE WHICH COULD PRODUCE A FEW SHOWERS IS A FRONTAL
BOUNDARY APPROACHING FROM THE NORTHWEST ON MONDAY AND MONDAY NIGHT.
THIS WEAKENING/SLOWING FRONT MAY EVENTUALLY STALL OVERHEAD ON
TUESDAY BEFORE LIFTING BACK TO THE NORTH ON TUESDAY NIGHT/WEDNESDAY.
WILL HAVE SOME POPS MONDAY AND MONDAY NIGHT... MAINLY IN THE WRN AND
NRN CWFA... BUT LEFT TUESDAY DRY FOR NOW SINCE RIDGING ALOFT LOOKS
TO BECOME BETTER ESTABLISHED DURING THIS TIME. THIS RIDGING WILL
PROBABLY RESULT IN A SLOWER ARRIVAL OF THE UPSTREAM TROUGH DURING
THE MID WEEK PERIOD...BUT WILL CARRY LOW CHC POPS ON WEDNESDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1156 PM EDT WED APR 24 2013
CONDITIONS START OUT VFR THEN SOME MVFR BY 12Z AS SOME RAIN MIXED
WITH WET SNOW ARRIVES. COULD BE PATCHY IFR WITH SNOW SHOWERS FROM
12Z TO 15Z THURSDAY...BUT THIS WAS LEFT OUT OF THE FORECAST FOR
NOW SINCE IT APPEARS TO BE VERY LOW CHANCE. WINDS WILL BE
SOUTHWEST IN THE MORNING GOING NORTHWEST BY LATE AFTERNOON.
WINDS WILL GUST OVER 20 KNOTS STARTING LATE TONIGHT AND THROUGH
THE AFTERNOON.
&&
.MARINE...
ISSUED AT 330 AM EDT THU APR 25 2013
GUSTY WINDS EXPECTED WITH THE PASSAGE OF THE SHORT WAVE TODAY. THIS
WILL NECESSITATE THE ISSUANCE OF A SCA.
&&
.HYDROLOGY...
ISSUED AT 330 AM EDT THU APR 25 2013
RIVERS WILL CONTINUE TO FALL THROUGH THE WEEKEND. TODAY/S PCPN WILL
BE UNDER A TENTH AND WILL HAVE LITTLE EFFECT ON RIVER LEVELS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR LMZ844>849.
&&
$$
SYNOPSIS...93
SHORT TERM...93
LONG TERM...MEADE
AVIATION...OSTUNO
HYDROLOGY...93
MARINE...93
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1213 AM EDT THU APR 25 2013
.UPDATE...
ISSUED AT 1002 PM EDT WED APR 24 2013
LATEST STLT IMAGERY AND RUC ANALYSIS SHOW A PAIR OF SHRTWVS ROTATING
THRU UPR TROF CENTERED FM HUDSON BAY INTO THE GREAT LKS. A BAND OF
SHRASN IS EVIDENT STRETCHING FM THE WRN CWA SWWD THRU NW WI INTO SE
MN RIGHT AHEAD OF THE FIRST DISTURBANCE. A MORE POTENT SHRTWV/70KT
H3 JET MAX ARE DIGGING SSEWD INTO WRN MN RIGHT BEHIND THE FIRST
SHRTWV. AS A RESULT...THE SRN END OF THE PCPN BAND IS TENDING TO
INTENSIFY AND TAKING ON A BOW ECHO APPEARANCE UNDER THE SHARPER
DPVA/H7-3 QVECTOR CNVGC ACCOMPANYING THE MORE POTENT SHRTWV. WIND
GUSTS IN THE WAKE OF THE PASSAGE OF THIS LINE OF SHRA/EMBEDDED TS
REACHED 42 KTS AT ROCHESTER MN. AT THE SAME TIME...CLD TOP TEMPS
OVER THE N END OF THE BAND ARE RISING...AND RADAR ECHOES ARE TENDING
TO DIMINISH OVER WRN UPR MI. THE LATEST RUC/HRRR MODELS APPEAR TO
HAVE THE BEST HANDLE ON THESE TRENDS...SO USED THEIR OUTPUT FOR FCST
UPDATE. THESE MODELS HINT THE MORE SGNFT PCPN...THE REMNANTS OF THE
LINE OF SHRA MOVING INTO WRN WI...WL IMPACT THE SCNTRL CWA AFT 06Z
CLOSER TO THE STRONGER DYNAMICS ASSOCIATED WITH THE SHRTWV FCST TO
DIG INTO THE UPR MIDWEST. SO TENDED TO CUT POPS/QPF/FCST SN AMOUNTS
A BIT OVER THE NW CWA WHILE DOING THE OPPOSITE OVER THE SCNTRL. DID
RETAIN HI LIKELY POPS AND UP TO 2 INCHES OF SN FOR THE NW CLOSER TO
BAND OF SHARPER H85-7 FGEN FCST BY SEVERAL MODELS OVER THIS AREA IN
THE PRESENCE OF FAIRLY UNSTABLE LAPSE RATES.
REMOVED MENTION OF -FZRA FM FCST EARLIER TO REFLECT UNSTABLE LLVL
LAPSE RATES SHOWN ON FCST/OBSVD 00Z RAOBS AND ABSENCE OF ELEVATED
WARM LYR IN FCST SDNGS.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 527 PM EDT WED APR 24 2013
A SHORTWAVE UPPER AND ASSOCIATED SFC TROUGH AREA OVER NW MN THIS
AFTERNOON...WITH PRECIP OUT AHEAD OF THE TROUGH MOVING INTO FAR WRN
LAKE SUPERIOR. AS THE SYSTEM MOVES ACROSS THE CWA TONIGHT INTO THU
MORNING...IT WILL DEEPEN AND CLOSE OFF...POSSIBLY LEADING TO AN FGEN
BAND OF SNOW OVER THE KEWEENAW/NW UP TONIGHT ALONG WITH THE REST OF
THE SYNOPTIC PRECIP OVER MUCH OF THE REST OF THE CWA. VERY UNCERTAIN
AS TO THE EXACT TRACK/INTENSITY OF THE THIN FGEN BAND...IF IT
DEVELOPS...SO WILL NOT ISSUE ANY HEADLINES FOR THAT RIGHT NOW...EVEN
THROUGH A NARROW BAND OF ADVISORY LEVEL SNOWFALL OF UP TO 4 INCHES
IS POSSIBLE WITH THE BAND. ELSEWHERE...PRECIP WILL BE MOSTLY
SNOW...EXCEPT OVER THE CENTRAL AND ERN CWA WHERE MORE RAIN AND SOME
FREEZING RAIN WILL BE POSSIBLE. TEMPS WILL NOT BE AS COLD TONIGHT AS
LAST NIGHT DUE TO THE PRECIP AND CLOUD COVER.
THU WILL SEE THE SYSTEM MOVING OUT IN THE MORNING...WITH DECREASING
CLOUDS THROUGHOUT THE DAY. EXPECT HIGHS IN THE 40S TO AROUND
50...COOLER NEAR LAKE SUPERIOR WITH ANY LAKE BREEZES THAT DEVELOP.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 527 PM EDT WED APR 24 2013
SPRING WARMUP LOOKS TO BE JUST AROUND THE CORNER AS A MAJOR PATTERN
CHANGE IS EXPECTED FOR LATE THIS WEEK INTO EARLY NEXT WEEK. THE
CNTRL TO ERN CONUS TROF THAT HAS MAINTAINED THE PERSISTENT COLDER
TEMPS OVER THE UPPER LAKES WILL QUICKLY RETREAT INTO NE CANADA AS
THE RIDGE ALONG THE W COAST BEGINS TO FLATTEN...ALLOWING WARMER
PACIFIC FLOW TO SPREAD ACROSS THE NRN CONUS. BY EARLY NEXT
WEEK...TROF WILL SHIFT INTO THE WRN CONUS...LEADING TO STRONG
RIDGING OVER THE E. THE SW FLOW BTWN THESE FEATURES WILL LEAD TO A
MAJOR WARMUP FOR THE UPPER LAKES AT LEAST FOR THE EARLY PORTION OF
NEXT WEEK. GIVEN THE RECORD DEEP LATE SEASON SPRING SNOWPACK AND
ASSOC HIGH SNOW WATER EQUIVALENTS (GENERALLY 5-11 INCHES) FOR
WESTERN AND NORTHERN PORTIONS OF THE CWA...THE ABOVE NORMAL TEMPS
WILL LEAD TO SIGNIFICANT/PERSISTENT MELTING...AND THE POTENTIAL FOR
FLOODING OF SOME RIVERS AND STREAMS NEXT WEEK. FORTUNATELY...IT
APPEARS THAT RAINFALL SHOULD GENERALLY BE ON THE LIGHT SIDE AT LEAST
THROUGH SUNDAY.
MAJOR PATTERN CHANGE BEGINS FRIDAY AS PACIFIC FLOW BEGINS TO SURGE
ACROSS THE NRN CONUS...FORCING TROFFING TO THE E AND NE. 850MB TEMPS
WILL REBOUND FROM -3/-5C THU EVENING TO 4/6C BY FRI EVENING.
STRONGEST WAA/ISENTROPIC ASCENT MOST EVIDENT ON 290K SFC SWINGS
ACROSS THE UPPER LAKES FRI...AND IT SHOULD BE SUFFICIENT TO GENERATE
SOME AN AREA OF -RA ACROSS MAINLY THE CENTRAL AND ERN FCST AREA.
GIVEN INITIAL DRYNESS OF AIRMASS...ONLY CHC POPS WARRANTED. PCPN MAY
BEGIN LATE THU NIGHT AS -RA/-SN OVER THE FAR W. EVEN WITH
CLOUDS...TEMPS SHOULD STILL BE ABLE TO RISE WELL INTO THE 50S
FRI...PERHAPS EVEN LOWER 60S OVER THE INTERIOR WEST WHERE SOME
AFTERNOON SUNSHINE IS POSSIBLE. HOWEVER...WITH BRISK S WINDS UP LAKE
MICHIGAN...TEMPS WILL BE HELD TO THE 40S OVER THE EAST HALF.
SATURDAY LOOKS DRY AND EVEN WARMER WITH A FAIR AMOUNT OF SUNSHINE.
850MB TEMPS OF 6-8C SHOULD YIELD MAX TEMPS IN THE LOWER TO MID 60S
OVER THE WEST HALF. AGAIN SOUTHERLY WINDS WILL KEEP THE EAST HALF
COOLER...ESPECIALLY NEAR THE SHORELINE AREAS WHERE HIGH TEMPS WILL
STRUGGLE TO REACH THE MID 40S.
AS ERN RIDGING BUILDS EARLY NEXT WEEK...THE UPPER LAKES MAY BE
BRUSHED BY A COUPLE OF SHORTWAVES LIFTING MAINLY W AND N OF THE AREA
SUN/MON. AS FIRST SHORTWAVE MOVES LATE SAT NIGHT INTO SUNDAY...ASSOC
FORCING IS PRETTY WEAK AS EVIDENCED BY Q-VECT CONV SO ONLY SLIGHT
CHC POPS WARRANTED OVER THE WRN COUNTIES LATE SAT NIGHT AND THEN
OVER THE NRN TIER ON SUNDAY. THERE SHOULD A BE A BETTER CHC OF RAIN
SHOWERS LATE SUN NIGHT INTO MONDAY AS SECOND SHORTWAVE LIFTING TO
THE NORTH PUSHES A WEAK COLD FRONT/TROUGH INTO THE AREA. FORCING
WITH THIS SECOND SHORTWAVE COULD BE AIDED BY UPR DIVERGENCE IN RIGHT
ENTRANCE REGION OF 80 KT 3K JET MAX LIFTING NORTH OF LAKE SUPERIOR.
HAVE INCLUDED HIGHER CHC 40-50 PCT POPS FOR RAIN SHOWERS AS FRONTAL
BOUNDARY SLOWLY WORKS ITS WAY ACROSS THE CWA LATE SUN NIGHT INTO
MONDAY. BOTH GFS AND ECMWF SHOW POTENTIAL FOR UP TO QUARTER INCH OF
RAINFALL. MODELS INDICATE FRONTAL BOUNDARY COULD STALL OUT OVER EAST
AND SCNTRL PORTIONS OF CWA LATE MONDAY AND THEN LIFT NORTH AS A WARM
FRONT ON MONDAY NIGHT. WL KEEP CHC POPS IN FOR POSSIBLE SCT SHOWERS
MON NIGHT AS WARM FRONT LIFTS NORTH.
TUESDAY LOOKS MAINLY DRY AND POTENTIALLY QUITE WARM AS 5H RIDGE HGTS
AMPLIFY ACROSS THE UPPER GREAT LAKES. STRONG SRLY FLOW SETS UP OVER
THE AREA AHEAD OF NEXT APPROACHING SHORTWAVE AND ASSOC FRONTAL
SYSTEM OVER THE NRN PLAINS. ECMWF AND GFS SHOWS 8H THERMAL RIDGE
WITH 12C TEMPS OR WARMER MOVING ACROSS THE AREA. DEPENDING ON THE
DEGREE OF CLOUD COVER/SUNSHINE...MAX TEMPS INTO THE 70S ARE
DEFINITELY POSSIBLE OVER THE WRN HALF OF THE CWA. AS THE NEXT
FRONTAL SYSTEM MOVES THROUGH TUE NIGHT INTO WED...PER
GFS/ECMWF...CHC POPS HAVE BEEN INTRODUCED. COULD SEE THE POTENTIAL
FOR HEAVIER RAINFALL WITH THIS SYSTEM AS MODELS HINT THAT THE FRONT
COULD STALL OUT JUST SOUTH AND EAST OF OUR FCST AREA LATE WED INTO
WED NIGHT. SHORTWAVES RIDING ALONG THE FRONT COULD BRING THE
POTENTIAL FOR MORE SIGNIFICANT RAINFALL LATE NEXT WEEK AS DEEPER
GULF MOISTURE COULD WORK ITS WAY INTO THE GREAT LAKES REGION. THIS
RAINFALL POTENTIAL WILL NEED TO BE CLOSELY MONITORED ON FUTURE MODEL
RUNS ESPECIALLY GIVEN INCREASING FLOOD POTENTIAL DUE TO SNOWMELT
RUNOFF.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1212 AM EDT THU APR 25 2013
EXPECT PREDOMINANT MVFR CONDITIONS ASSOCIATED WITH PASSING LO PRES
TROF CROSSING THE UPR LKS TO GIVE WAY TO VFR CONDITIONS THIS MRNG
AFTER SUNRISE WHEN DAYTIME HEATING WL TEND TO MIX OUT LINGERING LLVL
MSTR. ARRIVAL OF HI PRES RDG AXIS/DRIER AIR WL THEN BRING VFR
CONDITIONS THRU THE REST OF THE TAF PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 527 PM EDT WED APR 24 2013
OTHER THAN AN INCREASE IN SRLY WINDS TO 25 KTS OVER THE ERN HALF OF
LAKE SUPERIOR LATE SUNDAY INTO SUNDAY EVENING AHEAD OF APPROACHING
COLD FRONTAL SYSTEM...WINDS ARE EXPECTED TO STAY AT OR BELOW 20 KTS
THROUGH THE FCST PD.
&&
.HYDROLOGY...
ISSUED AT 527 PM EDT WED APR 24 2013
UPCOMING MAJOR PATTERN CHANGE WILL BRING A DRAMATIC WARMUP TO THE
UPPER GREAT LAKES LATE THIS WEEK THRU THE FIRST HALF OF NEXT WEEK.
TEMPS WILL SWING TO ABOVE/WELL ABOVE NORMAL...BEGINNING FRI WHEN
TEMPS WILL RISE WELL INTO THE 50S WEST HALF...PERHAPS EVEN LOWER
60S. HIGHS WILL REACH WELL INTO THE 60S OVER THE WEEKEND INTO EARLY
NEXT WEEK WITH HIGHS AROUND 70F POSSIBLE SUN-TUE FOR SOME WRN
LOCATIONS. SNOW MELT SHOULD CONTINUE FOR THE NIGHTTIME HRS AS
TEMPERATURES ARE EXPECTED TO STAY ABOVE FREEZING.
THE WARM AIR WILL LEAD TO A SIGNIFICANT MELT OF THE UNUSUALLY DEEP
LATE SPRING SEASON SNOW PACK ACROSS THE SNOWBELTS OF WRN AND NRN
UPPER MI...AND RIVER LEVELS WILL BEGIN RISING EARLY THIS WEEKEND.
BASED ON THE EXISTING SNOW WATER EQUIVALENT...THE MOST SIGNIFICANT
ISSUES ARE EXPECTED OVER THE WESTERN HALF OF UPPER MICHIGAN...WHERE
SOME RIVERS WILL LIKELY REACH FLOOD STAGE. FOR FURTHER DETAILS...SEE
THE HYDROLOGIC OUTLOOK /ESF/.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...KC
SHORT TERM...TITUS
LONG TERM...VOSS
AVIATION...KC
MARINE...VOSS
HYDROLOGY...VOSS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
908 PM CDT FRI APR 26 2013
.UPDATE...
ISSUED AT 902 PM CDT FRI APR 26 2013
WITH TEMPERATURES APPROACHING THE DEW POINTS ACROSS NORTH CENTRAL
KANSAS ALREADY THIS EVENING AND LIGHT SOUTHEASTERLY WINDS
ADVECTING ADDITIONAL MOISTURE NORTHWARD...DECIDED TO INSERT SOME
AREAS OF FOG INTO THE FORECAST DURING THE OVERNIGHT/EARLY MORNING
HOURS TOMORROW. 00Z HRRR IS VERY AGGRESSIVE WITH WIDESPREAD
VISIBILITIES DROPPING TO 1/4 SM...BUT SREF PROBS KEEP LOWER
VISIBILITIES SOUTH OF THE LOCAL AREA...SO WENT AHEAD WITH A
COMPROMISE...BRINGING FOG UP TO AROUND HIGHWAY 6 IN SOUTH CENTRAL
NEBRASKA OVERNIGHT. OTHERWISE...NO ADDITIONAL CHANGES MADE TO
PREVIOUS FORECAST AT THIS TIME.
UPDATE ISSUED AT 650 PM CDT FRI APR 26 2013
WENT AHEAD AND UPDATED THE FORECAST TO REMOVE THE SMALL CHANCES
FOR THUNDERSTORMS THIS EVENING AS WHILE THE SPC MESO ANALYSIS PAGE
INDICATES THERE ARE A COUPLE HUNDRED JOULES OF CAPE ACROSS OUR AREA
RIGHT NOW...THIS WILL DIMINISH OVER THE NEXT COUPLE OF HOURS AND
THUS FAR SHOWERS AND THUNDERSTORMS HAVE LACKED A TRIGGER FOR
DEVELOPMENT. OTHER THAN REMOVING THESE SMALL CHANCES FOR
PRECIPITATION...NO ADDITIONAL CHANGES WERE MADE TO THE PREVIOUS
FORECAST AT THIS TIME.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 320 PM CDT FRI APR 26 2013
MAIN FOCUS IN THE SHORT TERM WILL CENTER AROUND SLIGHT CHANCES FOR
THUNDERSTORMS AND HIGH TEMPERATURES SATURDAY.
A QUICK SYNOPTIC ANALYSIS REVEALS MOSTLY ZONAL FLOW ACROSS THE
CONUS WITH THE EXCEPTION OF AN OPEN WAVE TROUGH ACROSS THE
ROCKIES. AT THE SURFACE...HIGH PRESSURE REMAINED SITUATED ACROSS
BOTH COASTS WITH A WEAK LOW PRESSURE SYSTEM ACROSS THE TEXAS
PANHANDLE. THE OPEN WAVE BEGAN TO SHIFT JUST SOUTH OF THE PLAINS
THIS MORNING...WHICH BROUGHT SHOWERS AND THUNDERSTORMS TO PORTIONS
OF KANSAS. SATELLITE IMAGERY REVEALS A THICK CLOUD COVER OVER MUCH
OF SOUTHEAST KANSAS AND MISSOURI WITH THINNING CIRRUS DECK ACROSS
SOUTHERN NEBRASKA AND IOWA. A SURFACE TROUGH ASSOCIATED WITH THE
LOW IN THE PANHANDLE ALSO BEGAN SHIFTING ACROSS THE PLAINS THIS
AFTERNOON AS WELL. A STRONG 850 MB JET STREAK ON THE BACKSIDE OF
THIS TROUGH ALSO SHIFTED ACROSS NEBRASKA THIS AFTERNOON. COMBINED
WITH STRONG MIXING...THIS JET STREAK LED TO A BRIEF PERIOD OF
STRONGER WIND GUSTS NEAR 30 MPH AND LOW RH VALUES NEAR 20 PERCENT.
THESE CONDITIONS WERE SEEN OVER A FAIRLY SMALL LOCALIZED AREA
STRETCHING FROM MCCOOK TO ORD WESTWARD.
FOR THE REST OF THE AFTERNOON...SHORT TERM MODELS INDICATE THE
WEAKENING OF THE 850 JET STREAK WHICH SHOULD RELAX WINDS AND HELP
STEADY RH VALUES. CURRENT THINKING IS WINDS WILL REMAIN MARGINAL
AROUND 20 TO 25 MPH FOR THE NEXT FEW HOURS OR SO ESPECIALLY WEST
OF A LINE FROM MCCOOK TO KEARNEY TO ORD BEFORE DECREASING BY LATE
THIS AFTERNOON AND EARLY EVENING.
AS THE SURFACE TROUGH CONTINUES TO SHIFT EASTWARD...MODELS ALSO
HINT AT THE POSSIBILITY FOR SOME ADDITIONAL SHOWER DEVELOPMENT
NEAR THE BOUNDARY...MAINLY SOUTH OF LINE FROM CAMBRIDGE TO
FULLERTON. WITH INSTABILITY PARAMETERS NEAR 300 TO 500 J/KG KEPT
MENTION OF THUNDER IN THE FORECAST FROM 0Z TO 3Z WITH DIMINISHING
INSTABILITY THEREAFTER LIKELY DECREASING THUNDER THREAT. AT THIS
POINT...REALLY THINKING ISOLATED LIGHT SHOWERS WITH MAYBE A RUMBLE
OF THUNDER OR TWO. HRRR AND 4 KM WRF MODEL ALSO IN AGREEMENT WITH
THIS THINKING.
HEADING INTO SATURDAY...THE UPPER LEVEL RIDGE SLOWLY BEGINS TO
BUILD EASTWARD INTO THE PLAINS BEHIND THE TROUGH AXIS. WARMER 850
MB TEMPERATURES WILL ALSO SLIDE INTO THE REGION. SHOULD BE A
FAIRLY NICE AND BRIGHT DAY WITH SURFACE HIGH PRESSURE OVER THE
FORECAST AREA...LIGHT NORTH WINDS AND TEMPERATURES RANGING IN THE
70S.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 320 PM CDT FRI APR 26 2013
GUIDANCE SUGGESTS AN OVERALL LACK IN KINEMATIC FORCING SHOULD
PROVIDE DRY CONDITIONS TO OUR AREA SUNDAY INTO SUNDAY EVENING.
DURING THE EARLY MORNING HOURS ON MONDAY HOWEVER...THERE ARE
INDICATIONS OF A WEAK MID LEVEL PERTURBATION MOVING OVER THE
REGION WITH PERHAPS ENOUGH OMEGA FOR PRECIPITATION PRODUCTION.
THAT BEING SAID FORECAST PROXIMITY SOUNDINGS FROM ACROSS OUR
AREA...PER THE NAM AND OPERATIONAL GFS...SUGGEST THE LOWER
TROPOSPHERE WILL REMAIN FAIRLY DRY AND AS A RESULT...IT IS
CURRENTLY BELIEVED NOTHING MORE THAN A FEW SPRINKLES WILL BE
REALIZED ACROSS THE AREA EARLY MONDAY MORNING. GIVEN ALL
THIS...WENT AHEAD WITH A SPRINKLE MENTION IN THE
FORECAST...PRIMARILY FOR LOCATIONS ACROSS OUR NORTH/NORTHWEST
WHERE OMEGA IS EXPECTED TO BE STRONGEST. DRY CONDITIONS ARE THEN
FORECAST INTO THE DAY MONDAY AND MONDAY NIGHT AS A LACK IN
KINEMATIC FORCING OVERTAKES THE AREA ONCE AGAIN.
ANOTHER CHANCE AT PRECIPITATION IS THEN FORECAST TUESDAY THROUGH
WEDNESDAY NIGHT AS A MID LEVEL SHORT WAVE IS EXPECTED TO MOVE OVER
PORTIONS OF THE NORTHERN AND CENTRAL PLAINS. AN ASSOCIATED SURFACE
LOW IS ALSO EXPECTED TO MOVE ACROSS PORTIONS OF THE NORTHERN
PLAINS AND UPPER MISSISSIPPI VALLEY WITH A LOW LEVEL BAROCLINIC
ZONE FORECAST TO MOVE ACROSS OUR CWA AT SOME POINT DURING THE DAY
TUESDAY. TIMING THE PASSAGE OF THE LOW LEVEL BAROCLINIC ZONE IS
DIFFICULT GIVEN THIS SYSTEM IS STILL 4 DAYS OUT...BUT AT THIS TIME
IT APPEARS LOCATIONS AHEAD OF THE BAROCLINIC ZONE WILL OBSERVE A
SURFACE DEWPOINT IN THE MID TO UPPER 50S. THIS LOW LEVEL
MOISTURE...WORKING IN CONCERT WITH INCREASING MID LEVEL LAPSE
RATES WITH THE APPROACH OF THE MID LEVEL SHORT WAVE...COULD
POTENTIALLY PROMOTE 0-1KM MLCAPE VALUES ANYWHERE BETWEEN 500J/KG
AND 1500J/KG. INCREASING MID TO UPPER LEVEL FLOW IS ALSO EXPECTED
TO INCREASE DEEP LAYER BULK SHEAR TO BETWEEN 30KTS AND 40KTS.
GIVEN ALL THIS...IT CERTAINLY APPEARS SEVERE WEATHER COULD BE
REALIZED AT LOCATIONS STILL OUT AHEAD OF THE LOW LEVEL BAROCLINIC
ZONE TUESDAY AFTERNOON AND EVENING. AT THIS TIME IT ALSO APPEARS
THE SOUTHEASTERN ONE-THIRD OF OUR CWA STANDS THE BEST CHANCE AT
OBSERVING SEVERE WEATHER AND AS A RESULT...WILL CONTINUE SUCH
WORDING IN THE HWO.
ANY SEVERE WEATHER THAT IS REALIZED ACROSS THE AREA TUESDAY
AFTERNOON AND EVENING SHOULD QUICKLY DEPART TO THE EAST/SOUTHEAST
TUESDAY NIGHT AS THE LOW LEVEL BAROCLINIC ZONE DOES THE SAME.
DECREASING LOW LEVEL MOISTURE SHOULD ALLOW FOR DECREASING
POTENTIAL INSTABILITY BUT WITH INCREASING OMEGA DUE TO THE
APPROACHING MID LEVEL SHORT WAVE...CHANCES FOR PRECIPITATION
CONTINUE IN THE FORECAST FOR MOST ALL OF OUR CWA TUESDAY NIGHT
INTO WEDNESDAY...AND LINGERING ACROSS OUR EAST/SOUTHEAST WEDNESDAY
NIGHT. DRY CONDITIONS ARE THEN FORECAST THURSDAY ONWARD.
A VERY WARM LOW LEVEL AIRMASS WILL CONTINUE TO PROMOTE AN
AFTERNOON HIGH TEMPERATURE IN THE 70S TO LOW 80S SUNDAY THROUGH
TUESDAY. THE PASSAGE OF THE LOW LEVEL BAROCLINIC ZONE ON TUESDAY
HOWEVER WILL THEN BRING AN END TO THE WARM WEATHER...WITH A COOLER
LOW LEVEL AIRMASS LIKELY PROMOTING AN AFTERNOON HIGH TEMPERATURE
IN THE 50S AND 60S TO FINISH OUT THE FORECAST PERIOD. AN OVERNIGHT
LOW TEMPERATURE IN THE 40S AND 50S IS EXPECTED SUNDAY NIGHT
THROUGH TUESDAY NIGHT...WITH LOWS RANGING FROM THE MID 30S TO THE
LOW 40S WEDNESDAY NIGHT ONWARD.
&&
.AVIATION...(FOR THE 00Z KGRI TAF THROUGH 00Z SATURDAY EVENING)
ISSUED AT 650 PM CDT FRI APR 26 2013
VFR CONDITIONS ARE EXPECTED AT KGRI FOR AT LEAST THE NEXT 24
HOURS. NORTHEASTERLY WINDS WILL DIMINISH SIGNIFICANTLY AFTER
SUNSET...AND LIGHT AND VARIABLE WINDS ARE EXPECTED TO PREVAIL
THROUGH THE PERIOD AS A WEAK PRESSURE GRADIENT PERSISTS ACROSS THE
REGION. MAY SEE SOME MID LEVEL CLOUDS FROM TIME TO TIME ASSOCIATED
WITH THE PASSING DISTURBANCE TO OUR SOUTH...BUT ANY LOWERED
CEILINGS OR PRECIPITATION ARE EXPECTED TO REMAIN WELL SOUTH OF THE
TERMINAL THIS EVENING BEFORE THIS DISTURBANCE PUSHES FURTHER EAST
BY SATURDAY MORNING.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...SAR
SHORT TERM...SALTZMAN
LONG TERM...BRYANT
AVIATION...SAR
AREA FORECAST DISCUSSION
NWS HASTINGS NE
657 PM CDT FRI APR 26 2013
.UPDATE...
ISSUED AT 650 PM CDT FRI APR 26 2013
WENT AHEAD AND UPDATED THE FORECAST TO REMOVE THE SMALL CHANCES
FOR THUNDERSTORMS THIS EVENING AS WHILE THE SPC MESO ANALYSIS PAGE
INDICATES THERE ARE A COUPLE HUNDRED JOULES OF CAPE ACROSS OUR AREA
RIGHT NOW...THIS WILL DIMINISH OVER THE NEXT COUPLE OF HOURS AND
THUS FAR SHOWERS AND THUNDERSTORMS HAVE LACKED A TRIGGER FOR
DEVELOPMENT. OTHER THAN REMOVING THESE SMALL CHANCES FOR
PRECIPITATION...NO ADDITIONAL CHANGES WERE MADE TO THE PREVIOUS
FORECAST AT THIS TIME.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 320 PM CDT FRI APR 26 2013
MAIN FOCUS IN THE SHORT TERM WILL CENTER AROUND SLIGHT CHANCES FOR
THUNDERSTORMS AND HIGH TEMPERATURES SATURDAY.
A QUICK SYNOPTIC ANALYSIS REVEALS MOSTLY ZONAL FLOW ACROSS THE
CONUS WITH THE EXCEPTION OF AN OPEN WAVE TROUGH ACROSS THE
ROCKIES. AT THE SURFACE...HIGH PRESSURE REMAINED SITUATED ACROSS
BOTH COASTS WITH A WEAK LOW PRESSURE SYSTEM ACROSS THE TEXAS
PANHANDLE. THE OPEN WAVE BEGAN TO SHIFT JUST SOUTH OF THE PLAINS
THIS MORNING...WHICH BROUGHT SHOWERS AND THUNDERSTORMS TO PORTIONS
OF KANSAS. SATELLITE IMAGERY REVEALS A THICK CLOUD COVER OVER MUCH
OF SOUTHEAST KANSAS AND MISSOURI WITH THINNING CIRRUS DECK ACROSS
SOUTHERN NEBRASKA AND IOWA. A SURFACE TROUGH ASSOCIATED WITH THE
LOW IN THE PANHANDLE ALSO BEGAN SHIFTING ACROSS THE PLAINS THIS
AFTERNOON AS WELL. A STRONG 850 MB JET STREAK ON THE BACKSIDE OF
THIS TROUGH ALSO SHIFTED ACROSS NEBRASKA THIS AFTERNOON. COMBINED
WITH STRONG MIXING...THIS JET STREAK LED TO A BRIEF PERIOD OF
STRONGER WIND GUSTS NEAR 30 MPH AND LOW RH VALUES NEAR 20 PERCENT.
THESE CONDITIONS WERE SEEN OVER A FAIRLY SMALL LOCALIZED AREA
STRETCHING FROM MCCOOK TO ORD WESTWARD.
FOR THE REST OF THE AFTERNOON...SHORT TERM MODELS INDICATE THE
WEAKENING OF THE 850 JET STREAK WHICH SHOULD RELAX WINDS AND HELP
STEADY RH VALUES. CURRENT THINKING IS WINDS WILL REMAIN MARGINAL
AROUND 20 TO 25 MPH FOR THE NEXT FEW HOURS OR SO ESPECIALLY WEST
OF A LINE FROM MCCOOK TO KEARNEY TO ORD BEFORE DECREASING BY LATE
THIS AFTERNOON AND EARLY EVENING.
AS THE SURFACE TROUGH CONTINUES TO SHIFT EASTWARD...MODELS ALSO
HINT AT THE POSSIBILITY FOR SOME ADDITIONAL SHOWER DEVELOPMENT
NEAR THE BOUNDARY...MAINLY SOUTH OF LINE FROM CAMBRIDGE TO
FULLERTON. WITH INSTABILITY PARAMETERS NEAR 300 TO 500 J/KG KEPT
MENTION OF THUNDER IN THE FORECAST FROM 0Z TO 3Z WITH DIMINISHING
INSTABILITY THEREAFTER LIKELY DECREASING THUNDER THREAT. AT THIS
POINT...REALLY THINKING ISOLATED LIGHT SHOWERS WITH MAYBE A RUMBLE
OF THUNDER OR TWO. HRRR AND 4 KM WRF MODEL ALSO IN AGREEMENT WITH
THIS THINKING.
HEADING INTO SATURDAY...THE UPPER LEVEL RIDGE SLOWLY BEGINS TO
BUILD EASTWARD INTO THE PLAINS BEHIND THE TROUGH AXIS. WARMER 850
MB TEMPERATURES WILL ALSO SLIDE INTO THE REGION. SHOULD BE A
FAIRLY NICE AND BRIGHT DAY WITH SURFACE HIGH PRESSURE OVER THE
FORECAST AREA...LIGHT NORTH WINDS AND TEMPERATURES RANGING IN THE
70S.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 320 PM CDT FRI APR 26 2013
GUIDANCE SUGGESTS AN OVERALL LACK IN KINEMATIC FORCING SHOULD
PROVIDE DRY CONDITIONS TO OUR AREA SUNDAY INTO SUNDAY EVENING.
DURING THE EARLY MORNING HOURS ON MONDAY HOWEVER...THERE ARE
INDICATIONS OF A WEAK MID LEVEL PERTURBATION MOVING OVER THE
REGION WITH PERHAPS ENOUGH OMEGA FOR PRECIPITATION PRODUCTION.
THAT BEING SAID FORECAST PROXIMITY SOUNDINGS FROM ACROSS OUR
AREA...PER THE NAM AND OPERATIONAL GFS...SUGGEST THE LOWER
TROPOSPHERE WILL REMAIN FAIRLY DRY AND AS A RESULT...IT IS
CURRENTLY BELIEVED NOTHING MORE THAN A FEW SPRINKLES WILL BE
REALIZED ACROSS THE AREA EARLY MONDAY MORNING. GIVEN ALL
THIS...WENT AHEAD WITH A SPRINKLE MENTION IN THE
FORECAST...PRIMARILY FOR LOCATIONS ACROSS OUR NORTH/NORTHWEST
WHERE OMEGA IS EXPECTED TO BE STRONGEST. DRY CONDITIONS ARE THEN
FORECAST INTO THE DAY MONDAY AND MONDAY NIGHT AS A LACK IN
KINEMATIC FORCING OVERTAKES THE AREA ONCE AGAIN.
ANOTHER CHANCE AT PRECIPITATION IS THEN FORECAST TUESDAY THROUGH
WEDNESDAY NIGHT AS A MID LEVEL SHORT WAVE IS EXPECTED TO MOVE OVER
PORTIONS OF THE NORTHERN AND CENTRAL PLAINS. AN ASSOCIATED SURFACE
LOW IS ALSO EXPECTED TO MOVE ACROSS PORTIONS OF THE NORTHERN
PLAINS AND UPPER MISSISSIPPI VALLEY WITH A LOW LEVEL BAROCLINIC
ZONE FORECAST TO MOVE ACROSS OUR CWA AT SOME POINT DURING THE DAY
TUESDAY. TIMING THE PASSAGE OF THE LOW LEVEL BAROCLINIC ZONE IS
DIFFICULT GIVEN THIS SYSTEM IS STILL 4 DAYS OUT...BUT AT THIS TIME
IT APPEARS LOCATIONS AHEAD OF THE BAROCLINIC ZONE WILL OBSERVE A
SURFACE DEWPOINT IN THE MID TO UPPER 50S. THIS LOW LEVEL
MOISTURE...WORKING IN CONCERT WITH INCREASING MID LEVEL LAPSE
RATES WITH THE APPROACH OF THE MID LEVEL SHORT WAVE...COULD
POTENTIALLY PROMOTE 0-1KM MLCAPE VALUES ANYWHERE BETWEEN 500J/KG
AND 1500J/KG. INCREASING MID TO UPPER LEVEL FLOW IS ALSO EXPECTED
TO INCREASE DEEP LAYER BULK SHEAR TO BETWEEN 30KTS AND 40KTS.
GIVEN ALL THIS...IT CERTAINLY APPEARS SEVERE WEATHER COULD BE
REALIZED AT LOCATIONS STILL OUT AHEAD OF THE LOW LEVEL BAROCLINIC
ZONE TUESDAY AFTERNOON AND EVENING. AT THIS TIME IT ALSO APPEARS
THE SOUTHEASTERN ONE-THIRD OF OUR CWA STANDS THE BEST CHANCE AT
OBSERVING SEVERE WEATHER AND AS A RESULT...WILL CONTINUE SUCH
WORDING IN THE HWO.
ANY SEVERE WEATHER THAT IS REALIZED ACROSS THE AREA TUESDAY
AFTERNOON AND EVENING SHOULD QUICKLY DEPART TO THE EAST/SOUTHEAST
TUESDAY NIGHT AS THE LOW LEVEL BAROCLINIC ZONE DOES THE SAME.
DECREASING LOW LEVEL MOISTURE SHOULD ALLOW FOR DECREASING
POTENTIAL INSTABILITY BUT WITH INCREASING OMEGA DUE TO THE
APPROACHING MID LEVEL SHORT WAVE...CHANCES FOR PRECIPITATION
CONTINUE IN THE FORECAST FOR MOST ALL OF OUR CWA TUESDAY NIGHT
INTO WEDNESDAY...AND LINGERING ACROSS OUR EAST/SOUTHEAST WEDNESDAY
NIGHT. DRY CONDITIONS ARE THEN FORECAST THURSDAY ONWARD.
A VERY WARM LOW LEVEL AIRMASS WILL CONTINUE TO PROMOTE AN
AFTERNOON HIGH TEMPERATURE IN THE 70S TO LOW 80S SUNDAY THROUGH
TUESDAY. THE PASSAGE OF THE LOW LEVEL BAROCLINIC ZONE ON TUESDAY
HOWEVER WILL THEN BRING AN END TO THE WARM WEATHER...WITH A COOLER
LOW LEVEL AIRMASS LIKELY PROMOTING AN AFTERNOON HIGH TEMPERATURE
IN THE 50S AND 60S TO FINISH OUT THE FORECAST PERIOD. AN OVERNIGHT
LOW TEMPERATURE IN THE 40S AND 50S IS EXPECTED SUNDAY NIGHT
THROUGH TUESDAY NIGHT...WITH LOWS RANGING FROM THE MID 30S TO THE
LOW 40S WEDNESDAY NIGHT ONWARD.
&&
.AVIATION...(FOR THE 00Z KGRI TAF THROUGH 00Z SATURDAY EVENING)
ISSUED AT 650 PM CDT FRI APR 26 2013
VFR CONDITIONS ARE EXPECTED AT KGRI FOR AT LEAST THE NEXT 24
HOURS. NORTHEASTERLY WINDS WILL DIMINISH SIGNIFICANTLY AFTER
SUNSET...AND LIGHT AND VARIABLE WINDS ARE EXPECTED TO PREVAIL
THROUGH THE PERIOD AS A WEAK PRESSURE GRADIENT PERSISTS ACROSS THE
REGION. MAY SEE SOME MID LEVEL CLOUDS FROM TIME TO TIME ASSOCIATED
WITH THE PASSING DISTURBANCE TO OUR SOUTH...BUT ANY LOWERED
CEILINGS OR PRECIPITATION ARE EXPECTED TO REMAIN WELL SOUTH OF THE
TERMINAL THIS EVENING BEFORE THIS DISTURBANCE PUSHES FURTHER EAST
BY SATURDAY MORNING.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...SAR
SHORT TERM...SALTZMAN
LONG TERM...BRYANT
AVIATION...SAR
AREA FORECAST DISCUSSION...UPDATED
NWS WILMINGTON NC
527 PM EDT THU APR 25 2013
.SYNOPSIS...
A DRYING TREND IS EXPECTED FRIDAY INTO SATURDAY AS HIGH PRESSURE
REACHES DOWN FROM THE NORTH. AS THIS HIGH PRESSURE SHIFTS OFF
SHORE AN AREA OF LOW PRESSURE WILL AFFECT THE SOUTHEAST PRODUCING
AN EXTENDED PERIOD OF UNSETTLED WEATHER THROUGH THE LATTER HALF
OF THE WEEKEND INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 510 PM THURSDAY...UPDATED GRIDS DUE TO DEVELOPING COASTAL
CONVECTION. VARIOUS TEXT PRODUCTS UPDATED...INCLUDING THE HWO TO
EMPHASIZE THE SMALL HAIL AND BRIEF WIND GUSTS.
THE SHALLOW SEA BREEZE HAVING BARELY PUSHED 1 COUNTY INLAND DUE
TO STRONG WESTERLY FLOW ALOFT...THE DAYS LATE APRIL INSOLATION...
AND A BOUNDARY TRACKING SOUTHWARD WITH A NE SURGE BEHIND IT...HAVE
ALL COMBINED TO PRODUCE ISOLATED/SCATTERED CONVECTION ALONG THE
IMMEDIATE COAST OF THE ILM CWA. SVR PARAMETERS REMAIN
LACKING...HOWEVER THE STORMS HAVE PULSED UPWARDS AT TIMES
PRODUCING PEA-SIZE HAIL POSSIBLY UP TO DIME SIZE. POTENTIAL EXISTS
FOR WIND GUSTS FROM THIS ACTIVITY TO REACH 30 TO 40 MPH. MOVEMENT
OF THE ACTIVITY IS EASTWARD...AND ONCE IT REACHES THE IMMEDIATE
COASTLINE...THE ACTIVITY BASICALLY FALLS APART AS IT ENCOUNTERS
THE COOL SSTS WHICH EXHIBIT A RATHER STABLE OCEAN BASED MARINE
LAYER. WILL CONTINUE THE ACTIVITY THRU DUSK...WITH CONVECTION TO
QUICKLY CEASE THERE-AFTER.
PREVIOUS DISCUSSION..................................
AS OF 3 PM THURSDAY...AVAILABLE MOISTURE DEPICTED IN FORECAST
SOUNDINGS AND PARTIAL SUNSHINE COUPLED WITH A WEAK SEA BREEZE
MECHANISM IMPLY ISOLATED SHOWERS OR AN ISOLATED TSTM CANNOT BE
RULED OUT ENTIRELY THROUGH THE REMAINDER OF THE AFTERNOON...BUT
INTO EARLY EVENING DRYING WILL WIN OUT. FOR THIS REASON WILL
INITIATE THE TONIGHT PERIOD WITHOUT MENTIONABLE POP VALUES.
LOW-LEVEL THIN-LAYERED SATURATION MAY LINGER AROUND 2000 FT IN
ONSHORE MARITIME FLOW THROUGH THE EVENING HOURS SO WILL ADVERTISE
CLEARING MORE-SO OVERNIGHT VERSUS DIRECTLY AFTER DUSK.
ONCE CLEARING IN EARNEST COMMENCES LATER TONIGHT...RADIATIONAL
COOLING POTENTIAL WILL INCREASE. WIND HOWEVER IN THE BOUNDARY
LAYER WILL OFFSET THIS PARTIALLY. FOR THIS REASON AND CURRENT
SOIL TEMPERATURES...HAVE RAISED MINIMUM TEMPERATURES A DEGREE
OR TWO...WITH MIDDLE 40S WELL INLAND...AND UPPER 40S TO AROUND
50 ALONG THE COAST.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
AS OF 3 PM THURSDAY...HIGH PRESSURE EXTENDING DOWN FROM THE
GREAT LAKES ON FRIDAY WILL SHIFT EAST THROUGH SATURDAY REACHING
OFF THE MID ATLANTIC COAST BY EARLY SUN MORNING. IN THE UPPER
LEVELS A RIDGE TRIES TO BUILD UP FROM THE GULF COAST BUT A
SHORTWAVE WILL RIDE OVER THE TOP OF IT FROM THE CENTRAL STATES TO
THE OHIO VALLEY BY SUNDAY MORNING. OVERALL EXPECT FRIDAY TO REMAIN
DRY WITH A FEW HIGH CLOUDS MAKING IT INTO AREA BUT BY SATURDAY
INCREASING MID TO HIGH CLOUDS WILL REACH THE AREA FROM WEATHER
ASSOCIATED WITH SHORTWAVE AND ASSOCIATED SURFACE LOW TRACKING EAST
NORTHEAST. CLOUDS WILL CONTINUE TO INCREASE THROUGH LATE SATURDAY
INTO EARLY SUNDAY AS MID TO HIGH LEVEL FLOW INCREASES OUT OF THE
WEST NORTHWEST ADVECTING CLOUDS AND MOISTURE INTO AREA. BEST LIFT
AND MOISTURE WILL REMAIN TO THE WEST OF OUR LOCAL FORECAST AREA.
CAN NOT RULE OUT SOME PCP BUT OVERALL WILL KEEP LOW END POPS
LIMITED TO WESTERN ZONES LATE SAT AFTN AND INCREASING SLIGHTLY
THROUGH SAT NIGHT AS BEST SHORTWAVE ENERGY PASSES THROUGH.
A COOLER NORTHEAST TO EASTERLY FLOW WILL PERSIST THROUGH THE
PERIOD AS WINDS VEER AROUND AS THE HIGH SHIFTS EAST REMAINING
NORTH OF AREA. THE E-NE FLOW SHOULD HELP THE SEA BREEZE PENETRATE
INLAND FARTHER...ESPECIALLY ON SATURDAY WHEN WINDS ARE MORE
EASTERLY. TEMPS WILL WARM INTO THE 70S BUT MAY GET A COUPLE OF
DEGREES SHAVING OFF AS SEA BREEZE BRINGS COOLER OCEAN AIR INLAND
THROUGH THE AFTN AND CLOUDS INCREASE TO HELP FILTER OUT THE
SUN. OVERNIGHT LOWS WILL DROP JUST BELOW 50 INLAND AND LOWER 50S
ALONG THE COAST FRI NIGHT WITH FEWER CLOUDS AND LIGHTER WINDS
EXPECTED. BY SAT NIGHT...CLOUDS AND PCP WILL KEEP TEMPS IN THE 50S
MOST PLACES.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 3 PM THURSDAY...SPLIT FLOW ALOFT EARLY IN THE PERIOD WILL
TRANSITION TO A BLOCKING PATTERN AS WEAK REX BLOCK SETS UP. HIGH
PRESSURE NORTH OF THE AREA WILL MAINTAIN NORTHEAST FLOW FOR MUCH OF
THE PERIOD KEEPING TEMPERATURES NEAR TO BELOW CLIMO. LOW LEVEL
NORTHEAST TO EAST FLOW AND SOUTHERLY MID LEVEL FLOW WILL KEEP PLENTY
OF MOISTURE IN THE REGION. ALTHOUGH THERE ARE NO STRONGLY FORCED
FEATURES DIURNAL HEATING...DESPITE CONSIDERABLE CLOUD COVER...AND
DEVELOPING COASTAL TROUGH NEXT WEEK WILL HELP MAINTAIN SOME RAIN
CHANCES FOR MUCH OF THE PERIOD.
&&
.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
AS OF 18Z...LOCAL WRF AND HRRR MODELS STILL DEPICT A FAIRLY DECENT
CHANCE FOR CONVECTION ALONG THE COAST...ASSOCIATED WITH THE FRONT
INTERACTING WITH THE SEA BREEZE RESULTANT. ON SATELLITE...A
NORTHEAST SURGE CAN BE OBSERVED COMING DOWN THE COAST ON VISIBLE.
THE SHOWERS SHOULD NOT BE TOO HEAVY...HOWEVER VISIBILITIES COULD
BRIEFLY GO MVFR...ALONG WITH MVFR CEILINGS. THIS EVENING...TIME
HEIGHT INDICATE SOME SORT OF A MVFR CEILING THROUGH ABOUT 06Z...THEN
DRYING AT ALL LEVELS WITH VFR CONDITIONS EXPECTED. FRIDAY...A NICE
DAY IN STORE WITH SCATTERED SKIES AND NORTHEAST FLOW...GUSTY BY MID
TO LATE MORNING.
EXTENDED OUTLOOK...VFR THROUGH SATURDAY AFTERNOON. UNSETTLED WEATHER
SATURDAY NIGHT THROUGH TUESDAY AS A STATIONARY COASTAL TROUGH GIVES
US MOSTLY CLOUDY CONDITIONS THROUGH TUESDAY WITH PERIODS OF RAIN
AND IFR CONDITIONS.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 520 PM THURSDAY...UPDATED MAINLY THE EARLY EVENING PORTION
OF THE CWF TO TAKE INTO ACCOUNT THE ISOLATED TO SCATTERED
THUNDERSTORM ACTIVITY THAT QUICKLY DECAYS ONCE IT MOVES OFF THE
MAINLAND AND INTO THE COASTAL WATERS. THE NEAR SHORE WATERS...WITHIN
5 NM OF THE COAST COULD BRIEFLY EXPERIENCE 20 TO 30 KT WIND GUSTS
AND/OR SMALL HAIL LESS THAN PEA SIZE. WITH SSTS IN THE UPPER 50S
TO LOWER 60S...AN OCEAN BASED STABLE MARINE LAYER WILL EXIST
ACROSS THE AREA WATERS. THIS STABLE LAYER HAS PROTECTED THE LOCAL
WATERS BY WEAKENING/DISSIPATING THE STRONG THUNDERSTORMS THAT MOVE
OFF THE ADJACENT MAINLAND.
PREVIOUS DISCUSSION.............................................
AS OF 3 PM THURSDAY...THERE IS STILL QUITE A BIT OF SOUTHERLY
WAVE ENERGY IN THE WATERS THAT WILL INTERACT WITH POST-FRONTAL
NE WINDS LATE THIS AFTERNOON AND OVERNIGHT...SO ALTHOUGH NO
ADVISORIES ARE IN EFFECT...THE SEA WILL HAVE A BUMPY CHARACTER
AS OPPOSING WIND-CHOP CO-MINGLES WITH SOUTHERLY LONGER PERIOD
WAVES. A FEW SHOWERS MAY DOT THE WATERS THROUGH THE EARLY EVE
BUT ANY TSTMS WILL LIKELY REMAIN CONFINED TO THE GULF STREAM.
STRENGTHENING HIGH PRESSURE MOVING INTO THE MID-ATLANTIC RGN
WILL BRING 15-20 KT NE WINDS AFTER MIDNIGHT AND AN "EXERCISE
CAUTION" HEADLINE WILL INSERTED INTO THE CWF FOR OVERNIGHT
THROUGH FRIDAY MORNING WITH 5 FOOT SEAS A DECENT BET ACROSS
OUR OUTER WATERS.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 PM THURSDAY...HIGH PRESSURE WILL RIDGE DOWN FROM THE NORTH
THROUGH THE PERIOD PRODUCING A MODEST NORTHEAST FLOW ON FRIDAY
VEERING AROUND TO THE EAST AND LIGHTENING THROUGH SATURDAY AS CAA
AND GRADIENT WEAKENS. WINDS WILL START OUT 15 TO 20 KTS OUT OF THE
NORTHEAST BUT WILL DIMINISH THROUGH SAT NIGH INTO SUNDAY DOWN TO
10 TO 15 KTS.
SEAS WILL BE LOWEST JUST SOUTH OF CAPE FEAR THROUGH BRUNSWICK
COUNTY HAVING BEST PROTECTION FROM NORTHEAST FLOW...RUNNING AROUND
1 TO 2 FT. SEAS IN THE OUTER WATERS WILL BE GREATEST...UP AROUND
5 FT THROUGH SAT MORNING INTO SAT AFTN AND MAY SEE SOME 6 FOOTERS
HEADING OUT TOWARD FRYING PAN SHOALS...WITH NORTHEAST WINDS UP
CLOSE TO 20 KTS.
A DECENT NORTHEASTERLY FLOW WILL BE IN PLACE
AT THE BEGINNING OF THE PERIOD ON THE ORDER OF 10-15 KNOTS WITH A
FEW PLACES ACROSS THE OUTER WATERS SEEING JUST OVER 15. AS COLD
AIR ADVECTION WANES SO WILL THE WINDS BUT HIGH PRESSURE TO THE
NORTHEAST WILL KEEP THIS FLOW IN PLACE WITH A SLIGHT DIURNAL
VEERING VIA THE SEA BREEZE. SWAN SEAS ARE JUST UNDER SMALL CRAFT
CRITERIA EARLY FRIDAY...3-5 FEET DROPPING TO 2-4 FEET BY SATURDAY.
LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 3 PM THURSDAY...NORTHEAST TO EAST FLOW ACROSS THE WATERS SUN
WILL BECOME SOUTHEAST MON/TUE AS WEAK COASTAL TROUGH TAKES SHAPE.
WIND SPEEDS WILL BE 10 TO 15 KT FOR A MAJORITY OF THE PERIOD. SEAS
WILL RUN 2 TO 4 FT THROUGH THE PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...RGZ
NEAR TERM...DCH/MJC
SHORT TERM...RGZ
LONG TERM...III
AVIATION...SGL
AREA FORECAST DISCUSSION...UPDATED
NWS WILMINGTON NC
518 PM EDT THU APR 25 2013
.SYNOPSIS...
A DRYING TREND IS EXPECTED FRIDAY INTO SATURDAY AS HIGH PRESSURE
REACHES DOWN FROM THE NORTH. AS THIS HIGH PRESSURE SHIFTS OFF
SHORE AN AREA OF LOW PRESSURE WILL AFFECT THE SOUTHEAST PRODUCING
AN EXTENDED PERIOD OF UNSETTLED WEATHER THROUGH THE LATTER HALF
OF THE WEEKEND INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 510 PM THURSDAY...UPDATED GRIDS DUE TO DEVELOPING COASTAL
CONVECTION. VARIOUS TEXT PRODUCTS UPDATED...INCLUDING THE HWO TO
EMPHASIZE THE SMALL HAIL AND BRIEF WIND GUSTS.
THE SHALLOW SEA BREEZE HAVING BARELY PUSHED 1 COUNTY INLAND DUE
TO STRONG WESTERLY FLOW ALOFT...THE DAYS LATE APRIL INSOLATION...
AND A BOUNDARY TRACKING SOUTHWARD WITH A NE SURGE BEHIND IT...HAVE
ALL COMBINED TO PRODUCE ISOLATED/SCATTERED CONVECTION ALONG THE
IMMEDIATE COAST OF THE ILM CWA. SVR PARAMETERS REMAIN
LACKING...HOWEVER THE STORMS HAVE PULSED UPWARDS AT TIMES
PRODUCING PEA-SIZE HAIL POSSIBLY UP TO DIME SIZE. POTENTIAL EXISTS
FOR WIND GUSTS FROM THIS ACTIVITY TO REACH 30 TO 40 MPH. MOVEMENT
OF THE ACTIVITY IS EASTWARD...AND ONCE IT REACHES THE IMMEDIATE
COASTLINE...THE ACTIVITY BASICALLY FALLS APART AS IT ENCOUNTERS
THE COOL SSTS WHICH EXHIBIT A RATHER STABLE OCEAN BASED MARINE
LAYER. WILL CONTINUE THE ACTIVITY THRU DUSK...WITH CONVECTION TO
QUICKLY CEASE THERE-AFTER.
PREVIOUS DISCUSSION.............................................
AS OF 3 PM THURSDAY...AVAILABLE MOISTURE DEPICTED IN FORECAST
SOUNDINGS AND PARTIAL SUNSHINE COUPLED WITH A WEAK SEA BREEZE
MECHANISM IMPLY ISOLATED SHOWERS OR AN ISOLATED TSTM CANNOT BE
RULED OUT ENTIRELY THROUGH THE REMAINDER OF THE AFTERNOON...BUT
INTO EARLY EVENING DRYING WILL WIN OUT. FOR THIS REASON WILL
INITIATE THE TONIGHT PERIOD WITHOUT MENTIONABLE POP VALUES.
LOW-LEVEL THIN-LAYERED SATURATION MAY LINGER AROUND 2000 FT IN
ONSHORE MARITIME FLOW THROUGH THE EVENING HOURS SO WILL ADVERTISE
CLEARING MORE-SO OVERNIGHT VERSUS DIRECTLY AFTER DUSK.
ONCE CLEARING IN EARNEST COMMENCES LATER TONIGHT...RADIATIONAL
COOLING POTENTIAL WILL INCREASE. WIND HOWEVER IN THE BOUNDARY
LAYER WILL OFFSET THIS PARTIALLY. FOR THIS REASON AND CURRENT
SOIL TEMPERATURES...HAVE RAISED MINIMUM TEMPERATURES A DEGREE
OR TWO...WITH MIDDLE 40S WELL INLAND...AND UPPER 40S TO AROUND
50 ALONG THE COAST.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
AS OF 3 PM THURSDAY...HIGH PRESSURE EXTENDING DOWN FROM THE
GREAT LAKES ON FRIDAY WILL SHIFT EAST THROUGH SATURDAY REACHING
OFF THE MID ATLANTIC COAST BY EARLY SUN MORNING. IN THE UPPER
LEVELS A RIDGE TRIES TO BUILD UP FROM THE GULF COAST BUT A
SHORTWAVE WILL RIDE OVER THE TOP OF IT FROM THE CENTRAL STATES TO
THE OHIO VALLEY BY SUNDAY MORNING. OVERALL EXPECT FRIDAY TO REMAIN
DRY WITH A FEW HIGH CLOUDS MAKING IT INTO AREA BUT BY SATURDAY
INCREASING MID TO HIGH CLOUDS WILL REACH THE AREA FROM WEATHER
ASSOCIATED WITH SHORTWAVE AND ASSOCIATED SURFACE LOW TRACKING EAST
NORTHEAST. CLOUDS WILL CONTINUE TO INCREASE THROUGH LATE SATURDAY
INTO EARLY SUNDAY AS MID TO HIGH LEVEL FLOW INCREASES OUT OF THE
WEST NORTHWEST ADVECTING CLOUDS AND MOISTURE INTO AREA. BEST LIFT
AND MOISTURE WILL REMAIN TO THE WEST OF OUR LOCAL FORECAST AREA.
CAN NOT RULE OUT SOME PCP BUT OVERALL WILL KEEP LOW END POPS
LIMITED TO WESTERN ZONES LATE SAT AFTN AND INCREASING SLIGHTLY
THROUGH SAT NIGHT AS BEST SHORTWAVE ENERGY PASSES THROUGH.
A COOLER NORTHEAST TO EASTERLY FLOW WILL PERSIST THROUGH THE
PERIOD AS WINDS VEER AROUND AS THE HIGH SHIFTS EAST REMAINING
NORTH OF AREA. THE E-NE FLOW SHOULD HELP THE SEA BREEZE PENETRATE
INLAND FARTHER...ESPECIALLY ON SATURDAY WHEN WINDS ARE MORE
EASTERLY. TEMPS WILL WARM INTO THE 70S BUT MAY GET A COUPLE OF
DEGREES SHAVING OFF AS SEA BREEZE BRINGS COOLER OCEAN AIR INLAND
THROUGH THE AFTN AND CLOUDS INCREASE TO HELP FILTER OUT THE
SUN. OVERNIGHT LOWS WILL DROP JUST BELOW 50 INLAND AND LOWER 50S
ALONG THE COAST FRI NIGHT WITH FEWER CLOUDS AND LIGHTER WINDS
EXPECTED. BY SAT NIGHT...CLOUDS AND PCP WILL KEEP TEMPS IN THE 50S
MOST PLACES.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 3 PM THURSDAY...SPLIT FLOW ALOFT EARLY IN THE PERIOD WILL
TRANSITION TO A BLOCKING PATTERN AS WEAK REX BLOCK SETS UP. HIGH
PRESSURE NORTH OF THE AREA WILL MAINTAIN NORTHEAST FLOW FOR MUCH OF
THE PERIOD KEEPING TEMPERATURES NEAR TO BELOW CLIMO. LOW LEVEL
NORTHEAST TO EAST FLOW AND SOUTHERLY MID LEVEL FLOW WILL KEEP PLENTY
OF MOISTURE IN THE REGION. ALTHOUGH THERE ARE NO STRONGLY FORCED
FEATURES DIURNAL HEATING...DESPITE CONSIDERABLE CLOUD COVER...AND
DEVELOPING COASTAL TROUGH NEXT WEEK WILL HELP MAINTAIN SOME RAIN
CHANCES FOR MUCH OF THE PERIOD.
&&
.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
AS OF 18Z...LOCAL WRF AND HRRR MODELS STILL DEPICT A FAIRLY DECENT
CHANCE FOR CONVECTION ALONG THE COAST...ASSOCIATED WITH THE FRONT
INTERACTING WITH THE SEA BREEZE RESULTANT. ON SATELLITE...A
NORTHEAST SURGE CAN BE OBSERVED COMING DOWN THE COAST ON VISIBLE.
THE SHOWERS SHOULD NOT BE TOO HEAVY...HOWEVER VISIBILITIES COULD
BRIEFLY GO MVFR...ALONG WITH MVFR CEILINGS. THIS EVENING...TIME
HEIGHT INDICATE SOME SORT OF A MVFR CEILING THROUGH ABOUT 06Z...THEN
DRYING AT ALL LEVELS WITH VFR CONDITIONS EXPECTED. FRIDAY...A NICE
DAY IN STORE WITH SCATTERED SKIES AND NORTHEAST FLOW...GUSTY BY MID
TO LATE MORNING.
EXTENDED OUTLOOK...VFR THROUGH SATURDAY AFTERNOON. UNSETTLED WEATHER
SATURDAY NIGHT THROUGH TUESDAY AS A STATIONARY COASTAL TROUGH GIVES
US MOSTLY CLOUDY CONDITIONS THROUGH TUESDAY WITH PERIODS OF RAIN
AND IFR CONDITIONS.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 PM THURSDAY...THERE IS STILL QUITE A BIT OF SOUTHERLY
WAVE ENERGY IN THE WATERS THAT WILL INTERACT WITH POST-FRONTAL
NE WINDS LATE THIS AFTERNOON AND OVERNIGHT...SO ALTHOUGH NO
ADVISORIES ARE IN EFFECT...THE SEA WILL HAVE A BUMPY CHARACTER
AS OPPOSING WIND-CHOP CO-MINGLES WITH SOUTHERLY LONGER PERIOD
WAVES. A FEW SHOWERS MAY DOT THE WATERS THROUGH THE EARLY EVE
BUT ANY TSTMS WILL LIKELY REMAIN CONFINED TO THE GULF STREAM.
STRENGTHENING HIGH PRESSURE MOVING INTO THE MID-ATLANTIC RGN
WILL BRING 15-20 KT NE WINDS AFTER MIDNIGHT AND AN "EXERCISE
CAUTION" HEADLINE WILL INSERTED INTO THE CWF FOR OVERNIGHT
THROUGH FRIDAY MORNING WITH 5 FOOT SEAS A DECENT BET ACROSS
OUR OUTER WATERS.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 PM THURSDAY...HIGH PRESSURE WILL RIDGE DOWN FROM THE NORTH
THROUGH THE PERIOD PRODUCING A MODEST NORTHEAST FLOW ON FRIDAY
VEERING AROUND TO THE EAST AND LIGHTENING THROUGH SATURDAY AS CAA
AND GRADIENT WEAKENS. WINDS WILL START OUT 15 TO 20 KTS OUT OF THE
NORTHEAST BUT WILL DIMINISH THROUGH SAT NIGH INTO SUNDAY DOWN TO
10 TO 15 KTS.
SEAS WILL BE LOWEST JUST SOUTH OF CAPE FEAR THROUGH BRUNSWICK
COUNTY HAVING BEST PROTECTION FROM NORTHEAST FLOW...RUNNING AROUND
1 TO 2 FT. SEAS IN THE OUTER WATERS WILL BE GREATEST...UP AROUND
5 FT THROUGH SAT MORNING INTO SAT AFTN AND MAY SEE SOME 6 FOOTERS
HEADING OUT TOWARD FRYING PAN SHOALS...WITH NORTHEAST WINDS UP
CLOSE TO 20 KTS.
A DECENT NORTHEASTERLY FLOW WILL BE IN PLACE
AT THE BEGINNING OF THE PERIOD ON THE ORDER OF 10-15 KNOTS WITH A
FEW PLACES ACROSS THE OUTER WATERS SEEING JUST OVER 15. AS COLD
AIR ADVECTION WANES SO WILL THE WINDS BUT HIGH PRESSURE TO THE
NORTHEAST WILL KEEP THIS FLOW IN PLACE WITH A SLIGHT DIURNAL
VEERING VIA THE SEA BREEZE. SWAN SEAS ARE JUST UNDER SMALL CRAFT
CRITERIA EARLY FRIDAY...3-5 FEET DROPPING TO 2-4 FEET BY SATURDAY.
LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 3 PM THURSDAY...NORTHEAST TO EAST FLOW ACROSS THE WATERS SUN
WILL BECOME SOUTHEAST MON/TUE AS WEAK COASTAL TROUGH TAKES SHAPE.
WIND SPEEDS WILL BE 10 TO 15 KT FOR A MAJORITY OF THE PERIOD. SEAS
WILL RUN 2 TO 4 FT THROUGH THE PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...RGZ
NEAR TERM...DCH/MJC
SHORT TERM...RGZ
LONG TERM...III
AVIATION...SGL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
327 PM EDT THU APR 25 2013
.SYNOPSIS...
A DRYING TREND IS EXPECTED FRIDAY INTO SATURDAY AS HIGH PRESSURE
REACHES DOWN FROM THE NORTH. AS THIS HIGH PRESSURE SHIFTS OFF
SHORE AN AREA OF LOW PRESSURE WILL AFFECT THE SOUTHEAST PRODUCING
AN EXTENDED PERIOD OF UNSETTLED WEATHER THROUGH THE LATTER HALF
OF THE WEEKEND INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 3 PM THURSDAY...AVAILABLE MOISTURE DEPICTED IN FORECAST
SOUNDINGS AND PARTIAL SUNSHINE COUPLED WITH A WEAK SEA BREEZE
MECHANISM IMPLY ISOLATED SHOWERS OR AN ISOLATED TSTM CANNOT BE
RULED OUT ENTIRELY THROUGH THE REMAINDER OF THE AFTERNOON...BUT
INTO EARLY EVENING DRYING WILL WIN OUT. FOR THIS REASON WILL
INITIATE THE TONIGHT PERIOD WITHOUT MENTIONABLE POP VALUES.
LOW-LEVEL THIN-LAYERED SATURATION MAY LINGER AROUND 2000 FT IN
ONSHORE MARITIME FLOW THROUGH THE EVENING HOURS SO WILL ADVERTISE
CLEARING MORE-SO OVERNIGHT VERSUS DIRECTLY AFTER DUSK.
ONCE CLEARING IN EARNEST COMMENCES LATER TONIGHT...RADIATIONAL
COOLING POTENTIAL WILL INCREASE. WIND HOWEVER IN THE BOUNDARY
LAYER WILL OFFSET THIS PARTIALLY. FOR THIS REASON AND CURRENT
SOIL TEMPERATURES...HAVE RAISED MINIMUM TEMPERATURES A DEGREE
OR TWO...WITH MIDDLE 40S WELL INLAND...AND UPPER 40S TO AROUND
50 ALONG THE COAST.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 PM THURSDAY...HIGH PRESSURE EXTENDING DOWN FROM THE
GREAT LAKES ON FRIDAY WILL SHIFT EAST THROUGH SATURDAY REACHING
OFF THE MID ATLANTIC COAST BY EARLY SUN MORNING. IN THE UPPER
LEVELS A RIDGE TRIES TO BUILD UP FROM THE GULF COAST BUT A
SHORTWAVE WILL RIDE OVER THE TOP OF IT FROM THE CENTRAL STATES TO
THE OHIO VALLEY BY SUNDAY MORNING. OVERALL EXPECT FRIDAY TO REMAIN
DRY WITH A FEW HIGH CLOUDS MAKING IT INTO AREA BUT BY SATURDAY
INCREASING MID TO HIGH CLOUDS WILL REACH THE AREA FROM WEATHER
ASSOCIATED WITH SHORTWAVE AND ASSOCIATED SURFACE LOW TRACKING EAST
NORTHEAST. CLOUDS WILL CONTINUE TO INCREASE THROUGH LATE SATURDAY
INTO EARLY SUNDAY AS MID TO HIGH LEVEL FLOW INCREASES OUT OF THE
WEST NORTHWEST ADVECTING CLOUDS AND MOISTURE INTO AREA. BEST LIFT
AND MOISTURE WILL REMAIN TO THE WEST OF OUR LOCAL FORECAST AREA.
CAN NOT RULE OUT SOME PCP BUT OVERALL WILL KEEP LOW END POPS
LIMITED TO WESTERN ZONES LATE SAT AFTN AND INCREASING SLIGHTLY
THROUGH SAT NIGHT AS BEST SHORTWAVE ENERGY PASSES THROUGH.
A COOLER NORTHEAST TO EASTERLY FLOW WILL PERSIST THROUGH THE
PERIOD AS WINDS VEER AROUND AS THE HIGH SHIFTS EAST REMAINING
NORTH OF AREA. THE E-NE FLOW SHOULD HELP THE SEA BREEZE PENETRATE
INLAND FARTHER...ESPECIALLY ON SATURDAY WHEN WINDS ARE MORE
EASTERLY. TEMPS WILL WARM INTO THE 70S BUT MAY GET A COUPLE OF
DEGREES SHAVEN OFF AS SEA BREEZE BRINGS COOLER OCEAN AIR INLAND
THROUGH THE AFTN AND CLOUDS INCREASE TO HELP FILTER OUT THE
SUN. OVERNIGHT LOWS WILL DROP JUST BELOW 50 INLAND AND LOWER 50S
ALONG THE COAST FRI NIGHT WITH FEWER CLOUDS AND LIGHTER WINDS
EXPECTED. BY SAT NIGHT...CLOUDS AND PCP WILL KEEP TEMPS IN THE 50S
MOST PLACES.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 3 PM THURSDAY...SPLIT FLOW ALOFT EARLY IN THE PERIOD WILL
TRANSITION TO A BLOCKING PATTERN AS WEAK REX BLOCK SETS UP. HIGH
PRESSURE NORTH OF THE AREA WILL MAINTAIN NORTHEAST FLOW FOR MUCH OF
THE PERIOD KEEPING TEMPERATURES NEAR TO BELOW CLIMO. LOW LEVEL
NORTHEAST TO EAST FLOW AND SOUTHERLY MID LEVEL FLOW WILL KEEP PLENTY
OF MOISTURE IN THE REGION. ALTHOUGH THERE ARE NO STRONGLY FORCED
FEATURES DIURNAL HEATING...DESPITE CONSIDERABLE CLOUD COVER...AND
DEVELOPING COASTAL TROUGH NEXT WEEK WILL HELP MAINTAIN SOME RAIN
CHANCES FOR MUCH OF THE PERIOD.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 18Z...LOCAL WRF AND HRRR MODELS STILL DEPICT A FAIRLY DECENT
CHANCE FOR CONVECTION ALONG THE COAST...ASSOCIATED WITH THE FRONT
INTERACTING WITH THE SEA BREEZE RESULTANT. ON SATELLITE...A
NORTHEAST SURGE CAN BE OBSERVED COMING DOWN THE COAST ON VISIBLE.
THE SHOWERS SHOULD NOT BE TOO HEAVY...HOWEVER VISIBILITIES COULD
BRIEFLY GO MVFR...ALONG WITH MVFR CEILINGS. THIS EVENING...TIME
HEIGHT INDICATE SOME SORT OF A MVFR CEILING THROUGH ABOUT 06Z...THEN
DRYING AT ALL LEVELS WITH VFR CONDITIONS EXPECTED. FRIDAY...A NICE
DAY IN STORE WITH SCATTERED SKIES AND NORTHEAST FLOW...GUSTY BY MID
TO LATE MORNING.
EXTENDED OUTLOOK...VFR THROUGH SATURDAY AFTERNOON. UNSETTLED WEATHER
SATURDAY NIGHT THROUGH TUESDAY AS A STATIONARY COASTAL TROUGH GIVES
US MOSTLY CLOUDY CONDITIONS THROUGH TUESDAY WITH PERIODS OF RAIN
AND IFR CONDITIONS.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 PM THURSDAY...THERE IS STILL QUITE A BIT OF SOUTHERLY
WAVE ENERGY IN THE WATERS THAT WILL INTERACT WITH POST-FRONTAL
NE WINDS LATE THIS AFTERNOON AND OVERNIGHT...SO ALTHOUGH NO
ADVISORIES ARE IN EFFECT...THE SEA WILL HAVE A BUMPY CHARACTER
AS OPPOSING WIND-CHOP CO-MINGLES WITH SOUTHERLY LONGER PERIOD
WAVES. A FEW SHOWERS MAY DOT THE WATERS THROUGH THE EARLY EVE
BUT ANY TSTMS WILL LIKELY REMAIN CONFINED TO THE GULF STREAM.
STRENGTHENING HIGH PRESSURE MOVING INTO THE MID-ATLANTIC RGN
WILL BRING 15-20 KT NE WINDS AFTER MIDNIGHT AND AN "EXERCISE
CAUTION" HEADLINE WILL INSERTED INTO THE CWF FOR OVERNIGHT
THROUGH FRIDAY MORNING WITH 5 FOOT SEAS A DECENT BET ACROSS
OUR OUTER WATERS.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 PM THURSDAY...HIGH PRESSURE WILL RIDGE DOWN FROM THE NORTH
THROUGH THE PERIOD PRODUCING A MODEST NORTHEAST FLOW ON FRIDAY VEERING
AROUND TO THE EAST AND LIGHTENING THROUGH SATURDAY AS CAA AND
GRADIENT WEAKENS. WINDS WILL START OUT 15 TO 20 KTS OUT OF THE
NORTHEAST BUT WILL DIMINISH THROUGH SAT NIGH INTO SUNDAY DOWN TO
10 TO 15 KTS.
SEAS WILL BE LOWEST JUST SOUTH OF CAPE FEAR THROUGH BRUNSWICK
COUNTY HAVING BEST PROTECTION FROM NORTHEAST FLOW...RUNNING AROUND
1 TO 2 FT. SEAS IN THE OUTER WATERS WILL BE GREATEST...UP AROUND
5 FT THROUGH SAT MORNING INTO SAT AFTN AND MAY SEE SOME 6 FTERS
HEADING OUT TOWARD FRYING PAN SHOALS....WITH NORTHEAST WINDS UP
CLOSE TO 20 KTS.
A DECENT NORTHEASTERLY FLOW WILL BE IN PLACE
AT THE BEGINNING OF THE PERIOD ON THE ORDER OF 10-15 KNOTS WITH A
FEW PLACES ACROSS THE OUTER WATERS SEEING JUST OVER 15. AS COLD
AIR ADVECTION WANES SO WILL THE WINDS BUT HIGH PRESSURE TO THE
NORTHEAST WILL KEEP THIS FLOW IN PLACE WITH A SLIGHT DIURNAL
VEERING VIA THE SEA BREEZE. SWAN SEAS ARE JUST UNDER SMALL CRAFT
CRITERIA EARLY FRIDAY...3-5 FEET DROPPING TO 2-4 FEET BY SATURDAY.
LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 3 PM THURSDAY...NORTHEAST TO EAST FLOW ACROSS THE WATERS SUN
WILL BECOME SOUTHEAST MON/TUE AS WEAK COASTAL TROUGH TAKES SHAPE.
WIND SPEEDS WILL BE 10 TO 15 KT FOR A MAJORITY OF THE PERIOD. SEAS
WILL RUN 2 TO 4 FT THROUGH THE PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...MJC
SHORT TERM...RGZ
LONG TERM...III
AVIATION...DL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
137 PM EDT THU APR 25 2013
.SYNOPSIS...
COOLER AIR WILL SETTLE IN OVERNIGHT. A DRYING TREND IS EXPECTED
FRIDAY INTO SATURDAY AS HIGH PRESSURE BUILDS NORTH OF THE REGION.
RAIN IS EXPECTED SUNDAY AND MONDAY AS SEVERAL DISTURBANCES OVER THE
NORTHERN GULF TRACK OVERHEAD.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1022 AM THURSDAY...14Z/10AM SURFACE ANALYSIS SHOWS THE
FRONTAL BOUNDARY HAS JUST ABOUT CLEARED OUR FAR SOUTHERN ZONES
WITH CKI AND GGE REPORTING NW WINDS. NORTH WINDS AROUND 10 MPH
WITH TEMPERATURES IN THE MIDDLE 60S WAS COMMON THIS HOUR NORTH OF
THE BOUNDARY WITH A FEW SIGHTS HAVING AN EARLY CREST TO 70 DEGREES
AHEAD OF THE LAGGING COOL AIR ADVECTION. LATEST FORECAST SOUNDINGS
INDICATE A MOIST LAYER FROM 2500 FT EXTENDING TO 12000 FT TODAY. A
LOW-LEVEL STABLE LAYER AROUND 950 MB WILL SERVE AS A WEAK MORNING
CAP...BUT WILL PARTIALLY ERODE DURING THE AFTERNOON. SEVERAL WEAK
RIPPLES ALOFT AHEAD OF THE MAIN TROUGH AXIS UPSTREAM WITH SURFACE
WARMING AND WEAK SEA BREEZE CONVERGENCE COULD POP A FEW SHOWERS
THROUGH AFTERNOON IN THE POST FRONTAL ATMOSPHERE. ADJUSTMENTS TO
THE GRIDS WERE MADE TO ACCOMMODATE THIS POTENTIAL.
MOISTURE PUSHES OFFSHORE BY THIS EVENING WITH CLEARING OVERNIGHT.
INITIALLY VERY LIGHT WINDS AT THE SURFACE AND 1000 FEET UP WILL
PROMOTE THE DEVELOPMENT OF A STRONG RADIATIONAL INVERSION WITH
TEMPERATURES FALLING INTO THE 40S BY 2 AM INLAND. AS HIGH PRESSURE
OVER THE OHIO VALLEY STRENGTHENS AND INCREASES OUR BOUNDARY LAYER
WINDS LATE...TEMPS WILL DRIFT ONLY ANOTHER FEW DEGREES DOWN BY
DAYBREAK WITH LOWS RANGING FROM THE LOW TO MID 40S INLAND...AND
UPPER 40S TO AROUND 50 ON THE BEACHES.
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...THE MAIN FEATURE FOR THE SHORT TERM PERIOD IS
THE SHORTWAVE NOW CLEARLY SEEN IN SATELLITE IMAGERY ENTERING THE
SOUTHWEST. THIS SYSTEM WILL MOVE QUICKLY ACROSS THE CONUS AS IT
TRANSITIONS FROM A CLOSED LOW TO OPEN WAVE.
MODEL GUIDANCE HAS TRENDED SLOWER WITH THE SYSTEM AND IT NOW APPEARS
SATURDAY WILL BE A RELATIVELY NICE DAY WITH HIGH LEVEL MOISTURE
STREAMING ACROSS. I HAVE ALL BUT REMOVED THE MENTION OF POPS. I
WALKED BACK CHANCE VALUES FOR OVERNIGHT SATURDAY INTO SUNDAY MORNING
AS WELL AND WOULD NOT BE SURPRISED TO SEE POPS DELAYED FURTHER WITH
SUBSEQUENT MODEL GUIDANCE.
COOL HIGH PRESSURE FROM THE NORTHEAST WILL KEEP TEMPERATURES
SLIGHTLY BELOW CLIMATOLOGY ALTHOUGH STRONG LATE APRIL INSOLATION
SHOULD PROVIDE A BOOST FRIDAY MITIGATED SOMEWHAT BY THE CLOUD COVER
SATURDAY. I DID INCREASE HIGHS FOR SATURDAY ALTHOUGH THEY REMAIN
COOLER THAN FRIDAY.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 3 AM WEDNESDAY...EXTENDED FORECAST REMAINS SOMEWHAT UNCERTAIN
MAINLY BEYOND SUNDAY WHEN CHANCE POPS REMAIN IN THE FORECAST VIA THE
SYSTEM NOW MOVING INTO THE SOUTHWEST. IT APPEARS A LOT OF THE
MOISTURE GENERATED BY FORECAST MODELS IS THE RESULT OF WEAK COLD AIR
DAMMING TO THE WEST. MORE SIGNIFICANT AND PROBABLY MORE REALISTIC
QPF IS ASSOCIATED WITH A LINGERING COASTAL TROUGH ACROSS MUCH OF OUR
AREA. I DID DECREASE POPS ALBEIT INCREMENTALLY MONDAY THROUGH
WEDNESDAY JUST TO REPRESENT THIS TREND. WE ARE GETTING INTO THE
SEASON WHERE MINIMAL FORCING CAN RESULT IN CONVECTION HOWEVER. NO
CHANGES TO TEMPERATURE FORECAST.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 18Z...LOCAL WRF AND HRRR MODELS STILL DEPICT A FAIRLY DECENT
CHANCE FOR CONVECTION ALONG THE COAST...ASSOCIATED WITH THE FRONT
INTERACTING WITH THE SEA BREEZE RESULTANT. ON SATELLITE...A
NORTHEAST SURGE CAN BE OBSERVED COMING DOWN THE COAST ON VISIBLE.
THE SHOWERS SHOULD NOT BE TOO HEAVY...HOWEVER VISIBILITIES COULD
BRIEFLY GO MVFR...ALONG WITH MVFR CEILINGS. THIS EVENING...TIME
HEIGHT INDICATE SOME SORT OF A MVFR CEILING THROUGH ABOUT 06Z...THEN
DRYING AT ALL LEVELS WITH VFR CONDITIONS EXPECTED. FRIDAY...A NICE
DAY IN STORE WITH SCATTERED SKIES AND NORTHEAST FLOW...GUSTY BY MID
TO LATE MORNING.
EXTENDED OUTLOOK...VFR THROUGH SATURDAY AFTERNOON. UNSETTLED WEATHER
SATURDAY NIGHT THROUGH TUESDAY AS A STATIONARY COASTAL TROUGH GIVES
US MOSTLY CLOUDY CONDITIONS THROUGH TUESDAY WITH PERIODS OF RAIN
AND IFR CONDITIONS.
&&
.MARINE...
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 1022 AM THURSDAY...A COLD FRONT IS CURRENTLY MOVING ACROSS
OUR COASTAL WATERS. NORTH WINDS TO INCREASE TO 15 KNOTS WITH
HIGHER GUSTS THROUGH MORNING. ISOLATED SHOWERS WILL DOT THE WATERS
TODAY BEHIND THE FRONT WITH NE WINDS AROUND 15 KT THIS AFTERNOON.
A FEW GUSTS TO 20 KT CAN BE EXPECTED. TONIGHT HIGH PRESSURE OVER
THE OHIO VALLEY WILL GAIN STRENGTH WITH ITS CENTRAL PRESSURE
INCREASING 6 MILLIBARS OVER A 12 HOUR PERIOD. THIS WILL BUILD THE
PRESSURE GRADIENT OVER THE CAROLINAS WITH THE COLD FRONT STALLING
A FEW HUNDRED MILES OFFSHORE...AND WINDS WILL REMAIN AT 15 KNOTS
WITH HIGHER GUSTS. THIS WILL BE A LONGER DURATION OF WINDIER
CONDITIONS COMPARED TO THIS MORNING...AND SEAS WILL BUILD TO 4-5
FEET AWAY FROM SHORE LATE TONIGHT.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...A DECENT NORTHEASTERLY FLOW WILL BE IN PLACE
AT THE BEGINNING OF THE PERIOD ON THE ORDER OF 10-15 KNOTS WITH A
FEW PLACES ACROSS THE OUTER WATERS SEEING JUST OVER 15. AS COLD AIR
ADVECTION WANES SO WILL THE WINDS BUT HIGH PRESSURE TO THE NORTHEAST
WILL KEEP THIS FLOW IN PLACE WITH A SLIGHT DIURNAL VEERING VIA THE
SEABREEZE. SWAN SEAS ARE JUST UNDER SMALL CRAFT CRITERIA EARLY
FRIDAY...3-5 FEET DROPPING TO 2-4 FEET BY SATURDAY.
LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM THURSDAY...WINDS AND SEAS WILL BE DICTATED BY THE
POSITION OF A COASTAL TROUGH/WARM FRONT LURKING JUST OFFSHORE. THE
SEA BREEZE...MORE LIKELY TO BE IN PLACE MONDAY WILL PLAY A ROLE AS
WELL. THE FORECAST HAS EASTERLY WINDS THROUGHOUT THE PERIOD
BASICALLY ON THE LOWER END OF A 10-15 KNOT RANGE. SEAS WILL HOVER IN
A 2-4 FT RANGE.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA/MJC
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...DL/MJC
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
116 PM EDT THU APR 25 2013
.SYNOPSIS...
A COLD FRONT WILL PASS ACROSS THE AREA TODAY BRINGING SLIGHTLY
COOLER AIR WITH ISOLATED SHOWERS. A DRYING TREND IS EXPECTED
FRIDAY INTO SATURDAY AS HIGH PRESSURE BUILDS NORTH OF THE REGION.
RAIN IS EXPECTED SUNDAY AND MONDAY AS SEVERAL DISTURBANCES OVER
THE NORTHERN GULF TRACK OVERHEAD.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1022 AM THURSDAY...14Z/10AM SURFACE ANALYSIS SHOWS THE
FRONTAL BOUNDARY HAS JUST ABOUT CLEARED OUR FAR SOUTHERN ZONES
WITH CKI AND GGE REPORTING NW WINDS. NORTH WINDS AROUND 10 MPH
WITH TEMPERATURES IN THE MIDDLE 60S WAS COMMON THIS HOUR NORTH OF
THE BOUNDARY WITH A FEW SIGHTS HAVING AN EARLY CREST TO 70 DEGREES
AHEAD OF THE LAGGING COOL AIR ADVECTION. LATEST FORECAST SOUNDINGS
INDICATE A MOIST LAYER FROM 2500 FT EXTENDING TO 12000 FT TODAY. A
LOW-LEVEL STABLE LAYER AROUND 950 MB WILL SERVE AS A WEAK MORNING
CAP...BUT WILL PARTIALLY ERODE DURING THE AFTERNOON. SEVERAL WEAK
RIPPLES ALOFT AHEAD OF THE MAIN TROUGH AXIS UPSTREAM WITH SURFACE
WARMING AND WEAK SEA BREEZE CONVERGENCE COULD POP A FEW SHOWERS
THROUGH AFTERNOON IN THE POST FRONTAL ATMOSPHERE. ADJUSTMENTS TO
THE GRIDS WERE MADE TO ACCOMMODATE THIS POTENTIAL.
MOISTURE PUSHES OFFSHORE BY THIS EVENING WITH CLEARING OVERNIGHT.
INITIALLY VERY LIGHT WINDS AT THE SURFACE AND 1000 FEET UP WILL
PROMOTE THE DEVELOPMENT OF A STRONG RADIATIONAL INVERSION WITH
TEMPERATURES FALLING INTO THE 40S BY 2 AM INLAND. AS HIGH PRESSURE
OVER THE OHIO VALLEY STRENGTHENS AND INCREASES OUR BOUNDARY LAYER
WINDS LATE...TEMPS WILL DRIFT ONLY ANOTHER FEW DEGREES DOWN BY
DAYBREAK WITH LOWS RANGING FROM THE LOW TO MID 40S INLAND...AND
UPPER 40S TO AROUND 50 ON THE BEACHES.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...THE MAIN FEATURE FOR THE SHORT TERM PERIOD IS
THE SHORTWAVE NOW CLEARLY SEEN IN SATELLITE IMAGERY ENTERING THE
SOUTHWEST. THIS SYSTEM WILL MOVE QUICKLY ACROSS THE CONUS AS IT
TRANSITIONS FROM A CLOSED LOW TO OPEN WAVE.
MODEL GUIDANCE HAS TRENDED SLOWER WITH THE SYSTEM AND IT NOW APPEARS
SATURDAY WILL BE A RELATIVELY NICE DAY WITH HIGH LEVEL MOISTURE
STREAMING ACROSS. I HAVE ALL BUT REMOVED THE MENTION OF POPS. I
WALKED BACK CHANCE VALUES FOR OVERNIGHT SATURDAY INTO SUNDAY MORNING
AS WELL AND WOULD NOT BE SURPRISED TO SEE POPS DELAYED FURTHER WITH
SUBSEQUENT MODEL GUIDANCE.
COOL HIGH PRESSURE FROM THE NORTHEAST WILL KEEP TEMPERATURES
SLIGHTLY BELOW CLIMATOLOGY ALTHOUGH STRONG LATE APRIL INSOLATION
SHOULD PROVIDE A BOOST FRIDAY MITIGATED SOMEWHAT BY THE CLOUD COVER
SATURDAY. I DID INCREASE HIGHS FOR SATURDAY ALTHOUGH THEY REMAIN
COOLER THAN FRIDAY.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 3 AM WEDNESDAY...EXTENDED FORECAST REMAINS SOMEWHAT UNCERTAIN
MAINLY BEYOND SUNDAY WHEN CHANCE POPS REMAIN IN THE FORECAST VIA THE
SYSTEM NOW MOVING INTO THE SOUTHWEST. IT APPEARS A LOT OF THE
MOISTURE GENERATED BY FORECAST MODELS IS THE RESULT OF WEAK COLD AIR
DAMMING TO THE WEST. MORE SIGNIFICANT AND PROBABLY MORE REALISTIC
QPF IS ASSOCIATED WITH A LINGERING COASTAL TROUGH ACROSS MUCH OF OUR
AREA. I DID DECREASE POPS ALBEIT INCREMENTALLY MONDAY THROUGH
WEDNESDAY JUST TO REPRESENT THIS TREND. WE ARE GETTING INTO THE
SEASON WHERE MINIMAL FORCING CAN RESULT IN CONVECTION HOWEVER. NO
CHANGES TO TEMPERATURE FORECAST.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 18Z...LOCAL WRF AND HRRR MODELS STILL DEPICT A FAIRLY DECENT
CHANCE FOR CONVECTION ALONG THE COAST...ASSOCIATED WITH THE FRONT
INTERACTING WITH THE SEA BREEZE RESULTANT. ON SATELLITE...A
NORTHEAST SURGE CAN BE OBSERVED COMING DOWN THE COAST ON VISIBLE.
THE SHOWERS SHOULD NOT BE TOO HEAVY...HOWEVER VISIBILITIES COULD
BRIEFLY GO MVFR...ALONG WITH MVFR CEILINGS. THIS EVENING...TIME
HEIGHT INDICATE SOME SORT OF A MVFR CEILING THROUGH ABOUT 06Z...THEN
DRYING AT ALL LEVELS WITH VFR CONDITIONS EXPECTED. FRIDAY...A NICE
DAY IN STORE WITH SCATTERED SKIES AND NORTHEAST FLOW...GUSTY BY MID
TO LATE MORNING.
EXTENDED OUTLOOK...VFR THROUGH SATURDAY AFTERNOON. UNSETTLED WEATHER
SATURDAY NIGHT THROUGH TUESDAY AS A STATIONARY COASTAL TROUGH GIVES
US MOSTLY CLOUDY CONDITIONS THROUGH TUESDAY WITH PERIODS OF RAIN
AND IFR CONDITIONS.
&&
.MARINE...
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 1022 AM THURSDAY...A COLD FRONT IS CURRENTLY MOVING ACROSS
OUR COASTAL WATERS. NORTH WINDS TO INCREASE TO 15 KNOTS WITH
HIGHER GUSTS THROUGH MORNING. ISOLATED SHOWERS WILL DOT THE WATERS
TODAY BEHIND THE FRONT WITH NE WINDS AROUND 15 KT THIS AFTERNOON.
A FEW GUSTS TO 20 KT CAN BE EXPECTED. TONIGHT HIGH PRESSURE OVER
THE OHIO VALLEY WILL GAIN STRENGTH WITH ITS CENTRAL PRESSURE
INCREASING 6 MILLIBARS OVER A 12 HOUR PERIOD. THIS WILL BUILD THE
PRESSURE GRADIENT OVER THE CAROLINAS WITH THE COLD FRONT STALLING
A FEW HUNDRED MILES OFFSHORE...AND WINDS WILL REMAIN AT 15 KNOTS
WITH HIGHER GUSTS. THIS WILL BE A LONGER DURATION OF WINDIER
CONDITIONS COMPARED TO THIS MORNING...AND SEAS WILL BUILD TO 4-5
FEET AWAY FROM SHORE LATE TONIGHT.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...A DECENT NORTHEASTERLY FLOW WILL BE IN PLACE
AT THE BEGINNING OF THE PERIOD ON THE ORDER OF 10-15 KNOTS WITH A
FEW PLACES ACROSS THE OUTER WATERS SEEING JUST OVER 15. AS COLD AIR
ADVECTION WANES SO WILL THE WINDS BUT HIGH PRESSURE TO THE NORTHEAST
WILL KEEP THIS FLOW IN PLACE WITH A SLIGHT DIURNAL VEERING VIA THE
SEABREEZE. SWAN SEAS ARE JUST UNDER SMALL CRAFT CRITERIA EARLY
FRIDAY...3-5 FEET DROPPING TO 2-4 FEET BY SATURDAY.
LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM THURSDAY...WINDS AND SEAS WILL BE DICTATED BY THE
POSITION OF A COASTAL TROUGH/WARM FRONT LURKING JUST OFFSHORE. THE
SEA BREEZE...MORE LIKELY TO BE IN PLACE MONDAY WILL PLAY A ROLE AS
WELL. THE FORECAST HAS EASTERLY WINDS THROUGHOUT THE PERIOD
BASICALLY ON THE LOWER END OF A 10-15 KNOT RANGE. SEAS WILL HOVER IN
A 2-4 FT RANGE.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA/MJC
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...DL/MJC
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
650 AM EDT THU APR 25 2013
.SYNOPSIS...
A COLD FRONT WILL MOVE ACROSS THE AREA THIS MORNING WITH THE
POSSIBILITY OF A FEW SHOWERS AND INCREASED CLOUD COVER. FRIDAY AND
SATURDAY LOOK GENERALLY NICE COURTESY OF HIGH PRESSURE TO THE
NORTHEAST. UNSETTLED CONDITIONS WILL RETURN SUNDAY AND CONTINUE
INTO THE NEW WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM THURSDAY...JUST IN THE PAST 30 MINUTES A FEW SHOWERS
HAVE DEVELOPED ON RADAR COMPOSITES JUST NORTH AND WEST OF COLUMBIA
SC. THIS APPEARS TO LINE UP WITH AN AREA OF VERY WEAK ISENTROPIC
LIFT ON AND NEAR THE 300K THETA SURFACE DEPICTED BY THE 06Z
MODELS...APPROXIMATELY 7000 FT AGL. MODELS SHOW HIGH RELATIVE
HUMIDITY AT THIS LEVEL ADVECTING EAST TO THE COAST DURING THE
MORNING HOURS...BUT SHOW ONLY SPOTTY AND INCONSISTENT ISENTROPIC
LIFT ACCOMPANYING IT. DESPITE WEAK FORCING THE BULK OF THE LATEST
MODEL GUIDANCE SHOWS AN EXPANSION OF QPF THROUGH 15 AND 18Z. NO
SIGNIFICANT CHANGES HAVE BEEN MADE TO THE FORECAST THIS MORNING.
PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
GENTLE SOUTHWEST BREEZES EARLY THIS MORNING WILL COME TO A CRASHING
END IN JUST A FEW HOURS AS A COLD FRONT PLOWS SOUTHEASTWARD OUT OF
CENTRAL NORTH CAROLINA. LINEAR EXTRAPOLATION OF THIS FRONT`S
MOVEMENT AGREES RATHER WELL WITH THE LATEST HRRR MODEL...WITH THE
WIND SHIFT REACHING LUMBERTON AROUND 630 AM...FLORENCE AROUND 700
AM...WILMINGTON AROUND 800 AM...AND THE MYRTLE BEACH AROUND BY 900
AM. THERE WILL BE A 2-3 HOUR PERIOD OF GUSTY NORTH WINDS IMMEDIATELY
BEHIND THE FRONT AS COLD ADVECTION PROMOTES MIXING UP INTO STRONGER
FLOW ALOFT...BUT THIS MOMENTUM WILL DISSIPATE BY NOON WITH LIGHTER
NORTHEAST WINDS EXPECTED THROUGH THE DAY.
BESIDES PATCHES OF ALTOCUMULUS ACROSS SOUTH CAROLINA THERE AREN`T
THAT MANY CLOUDS OUT AHEAD OF THE FRONT CURRENTLY. MODEL FORECAST
SOUNDINGS SHOW A MOISTURE INCREASING THROUGH AND ABOVE THE FRONTAL
INVERSION BETWEEN 2500-7000 FEET LATER THIS MORNING...BUT WITHOUT AN
INCOMING UPPER DISTURBANCE OR ANY FAVORABLY POSITIONED JET STREAKS
TO PROMOTE SYNOPTIC LIFTING WE MAY SEE SKIES CLEAR OUT EARLIER THAN
THE SKY LINE IN THE GFS/NAM MOS BULLETINS SUGGEST. THIS WILL HAVE
IMPLICATIONS ON THE HIGH TEMPERATURE FORECAST AS WELL...AND I TEND
TO THINK THE GFS MOS HIGHS WILL VERIFY BETTER THAN THE COOLER NAM
MOS TODAY. GIVEN THAT THERE IS ALMOST UNANIMOUS SUPPORT IN THE 00Z
MODELS FOR SOME LIGHT POST-FRONTAL RAIN THIS MORNING I AM KEEPING A
20 POP IN THE FORECAST...ALTHOUGH IT`S TOUGH TO PIN DOWN EXACTLY
WHAT THE CAUSATIVE FACTOR WILL BE.
MOISTURE PUSHES OFFSHORE BY THIS EVENING WITH CLEAR SKIES
DEVELOPING. INITIALLY VERY LIGHT WINDS AT THE SURFACE AND 1000 FEET
UP WILL PROMOTE THE DEVELOPMENT OF A STRONG RADIATIONAL INVERSION
WITH TEMPERATURES FALLING INTO THE 40S BY 2 AM INLAND. AS HIGH
PRESSURE OVER THE OHIO VALLEY STRENGTHENS AND INCREASES OUR BOUNDARY
LAYER WINDS LATE...TEMPS WILL DRIFT ONLY ANOTHER FEW DEGREES DOWN BY
DAYBREAK WITH LOWS RANGING FROM THE LOW TO MID 40S INLAND...AND
UPPER 40S TO AROUND 50 ON THE BEACHES.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...THE MAIN FEATURE FOR THE SHORT TERM PERIOD IS
THE SHORTWAVE NOW CLEARLY SEEN IN SATELLITE IMAGERY ENTERING THE
SOUTHWEST. THIS SYSTEM WILL MOVE QUICKLY ACROSS THE CONUS AS IT
TRANSITIONS FROM A CLOSED LOW TO OPEN WAVE.
MODEL GUIDANCE HAS TRENDED SLOWER WITH THE SYSTEM AND IT NOW APPEARS
SATURDAY WILL BE A RELATIVELY NICE DAY WITH HIGH LEVEL MOISTURE
STREAMING ACROSS. I HAVE ALL BUT REMOVED THE MENTION OF POPS. I
WALKED BACK CHANCE VALUES FOR OVERNIGHT SATURDAY INTO SUNDAY MORNING
AS WELL AND WOULD NOT BE SURPRISED TO SEE POPS DELAYED FURTHER WITH
SUBSEQUENT MODEL GUIDANCE.
COOL HIGH PRESSURE FROM THE NORTHEAST WILL KEEP TEMPERATURES
SLIGHTLY BELOW CLIMATOLOGY ALTHOUGH STRONG LATE APRIL INSOLATION
SHOULD PROVIDE A BOOST FRIDAY MITIGATED SOMEWHAT BY THE CLOUD COVER
SATURDAY. I DID INCREASE HIGHS FOR SATURDAY ALTHOUGH THEY REMAIN
COOLER THAN FRIDAY.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 3 AM WEDNESDAY...EXTENDED FORECAST REMAINS SOMEWHAT UNCERTAIN
MAINLY BEYOND SUNDAY WHEN CHANCE POPS REMAIN IN THE FORECAST VIA THE
SYSTEM NOW MOVING INTO THE SOUTHWEST. IT APPEARS A LOT OF THE
MOISTURE GENERATED BY FORECAST MODELS IS THE RESULT OF WEAK COLD AIR
DAMMING TO THE WEST. MORE SIGNIFICANT AND PROBABLY MORE REALISTIC
QPF IS ASSOCIATED WITH A LINGERING COASTAL TROUGH ACROSS MUCH OF OUR
AREA. I DID DECREASE POPS ALBEIT INCREMENTALLY MONDAY THROUGH
WEDNESDAY JUST TO REPRESENT THIS TREND. WE ARE GETTING INTO THE
SEASON WHERE MINIMAL FORCING CAN RESULT IN CONVECTION HOWEVER. NO
CHANGES TO TEMPERATURE FORECAST.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 12Z...A COUPLE OF OUR NORTHWEST SURFACE OBSERVATIONS ARE
SHOWING A WIND SHIFT TO THE NORTH AS A COLD FRONT SLOWLY DROPS IN
THIS MORNING. HAVE BACKED OFF A BIT OF THE GUSTY NATURE OF THE
SHIFT...BUT WE STILL SHOULD SEE WINDS ABOVE 15 KTS AT TIMES. A MVFR
CEILING IS POSSIBLE...BUT LEFT IT SCATTERED AT THIS TIME. ISOLATED
TO SCATTERED PRECIP IS EXPECTED TO DEVELOP ALONG THE FRONT LATER
THIS MORNING. THINK COVERAGE AT THIS TIME WILL BE LIMITED...WITH A
VCSH MENTION ONLY. ATMOSPHERE IS FAIRLY SATURATED TO 700 MB HOWEVER.
TONIGHT...ATMOSPHERE DRIES OUT WITH A CONTINUED NORTHERLY WIND...A
BIT MORE NORTHEASTERLY.
EXTENDED OUTLOOK...CHANCE OF SHOWERS/MVFR LATE SATURDAY THRU MONDAY.
OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 630 AM THURSDAY...NO SIGNIFICANT CHANGES ARE NEEDED TO THE
FORECAST. THE COLD FRONT IS RUNNING 30-45 MINUTES BEHIND SCHEDULE
ACROSS CENTRAL AND EASTERN NORTH CAROLINA WHICH SIMPLY DELAYS THE
VEERING TO NORTH WINDS A LITTLE LATER IN THE MORNING. PREVIOUS
DISCUSSION FROM 300 AM FOLLOWS...
A COLD FRONT ZIPPING SOUTHEASTWARD ACROSS CENTRAL NORTH CAROLINA
WILL MAKE IT INTO THE COASTAL WATERS BETWEEN 8 AND 11 AM...WITH
FAIRLY LIGHT SOUTHWEST WINDS SHIFTING TO THE NORTH AND INCREASING TO
15 KNOTS WITH HIGHER GUSTS. THIS FRONTAL SURGE WILL BE
SHORT-LIVED...AND WITHIN JUST A COUPLE OF HOURS NORTHEAST WINDS
SHOULD DIE DOWN TO 10-12 KNOTS. ALTHOUGH RADARS ACROSS THE CAROLINAS
SHOW LITTLE IF ANY RAIN ACCOMPANYING THE FRONT NOW MODELS SUGGEST AT
LEAST A FEW PATCHES OF RAIN WILL DEVELOP ACROSS THE COASTAL WATERS
LATE THIS MORNING...DISSIPATING DURING THE AFTERNOON HOURS.
FOR TONIGHT HIGH PRESSURE OVER THE OHIO VALLEY WILL GAIN STRENGTH
WITH ITS CENTRAL PRESSURE INCREASING 6 MILLIBARS OVER A 12 HOUR
PERIOD. THIS WILL BUILD THE PRESSURE GRADIENT OVER THE CAROLINAS
WITH THE COLD FRONT STALLING A FEW HUNDRED MILES OFFSHORE...AND
WINDS WILL AGAIN INCREASE TO 15 KNOTS WITH HIGHER GUSTS. THIS WILL
BE A LONGER DURATION OF WINDIER CONDITIONS COMPARED TO THIS
MORNING...AND SEAS WILL BUILD TO 4-5 FEET AWAY FROM SHORE LATE
TONIGHT.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...A DECENT NORTHEASTERLY FLOW WILL BE IN PLACE
AT THE BEGINNING OF THE PERIOD ON THE ORDER OF 10-15 KNOTS WITH A
FEW PLACES ACROSS THE OUTER WATERS SEEING JUST OVER 15. AS COLD AIR
ADVECTION WANES SO WILL THE WINDS BUT HIGH PRESSURE TO THE NORTHEAST
WILL KEEP THIS FLOW IN PLACE WITH A SLIGHT DIURNAL VEERING VIA THE
SEABREEZE. SWAN SEAS ARE JUST UNDER SMALL CRAFT CRITERIA EARLY
FRIDAY...3-5 FEET DROPPING TO 2-4 FEET BY SATURDAY.
LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM THURSDAY...WINDS AND SEAS WILL BE DICTATED BY THE
POSITION OF A COASTAL TROUGH/WARM FRONT LURKING JUST OFFSHORE. THE
SEA BREEZE...MORE LIKELY TO BE IN PLACE MONDAY WILL PLAY A ROLE AS
WELL. THE FORECAST HAS EASTERLY WINDS THROUGHOUT THE PERIOD
BASICALLY ON THE LOWER END OF A 10-15 KNOT RANGE. SEAS WILL HOVER IN
A 2-4 FT RANGE.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SHK
NEAR TERM...TRA
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
642 AM EDT THU APR 25 2013
.SYNOPSIS...
A COLD FRONT WILL MOVE ACROSS THE AREA THIS MORNING WITH THE
POSSIBILITY OF A FEW SHOWERS AND INCREASED CLOUD COVER. FRIDAY AND
SATURDAY LOOK GENERALLY NICE COURTESY OF HIGH PRESSURE TO THE
NORTHEAST. UNSETTLED CONDITIONS WILL RETURN SUNDAY AND CONTINUE
INTO THE NEW WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM THURSDAY...JUST IN THE PAST 30 MINUTES A FEW SHOWERS
HAVE DEVELOPED ON RADAR COMPOSITES JUST NORTH AND WEST OF COLUMBIA
SC. THIS APPEARS TO LINE UP WITH AN AREA OF VERY WEAK ISENTROPIC
LIFT ON AND NEAR THE 300K THETA SURFACE DEPICTED BY THE 06Z
MODELS...APPROXIMATELY 7000 FT AGL. MODELS SHOW HIGH RELATIVE
HUMIDITY AT THIS LEVEL ADVECTING EAST TO THE COAST DURING THE
MORNING HOURS...BUT SHOW ONLY SPOTTY AND INCONSISTENT ISENTROPIC
LIFT ACCOMPANYING IT. DESPITE WEAK FORCING THE BULK OF THE LATEST
MODEL GUIDANCE SHOWS AN EXPANSION OF QPF THROUGH 15 AND 18Z. NO
SIGNIFICANT CHANGES HAVE BEEN MADE TO THE FORECAST THIS MORNING.
PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
GENTLE SOUTHWEST BREEZES EARLY THIS MORNING WILL COME TO A CRASHING
END IN JUST A FEW HOURS AS A COLD FRONT PLOWS SOUTHEASTWARD OUT OF
CENTRAL NORTH CAROLINA. LINEAR EXTRAPOLATION OF THIS FRONT`S
MOVEMENT AGREES RATHER WELL WITH THE LATEST HRRR MODEL...WITH THE
WIND SHIFT REACHING LUMBERTON AROUND 630 AM...FLORENCE AROUND 700
AM...WILMINGTON AROUND 800 AM...AND THE MYRTLE BEACH AROUND BY 900
AM. THERE WILL BE A 2-3 HOUR PERIOD OF GUSTY NORTH WINDS IMMEDIATELY
BEHIND THE FRONT AS COLD ADVECTION PROMOTES MIXING UP INTO STRONGER
FLOW ALOFT...BUT THIS MOMENTUM WILL DISSIPATE BY NOON WITH LIGHTER
NORTHEAST WINDS EXPECTED THROUGH THE DAY.
BESIDES PATCHES OF ALTOCUMULUS ACROSS SOUTH CAROLINA THERE AREN`T
THAT MANY CLOUDS OUT AHEAD OF THE FRONT CURRENTLY. MODEL FORECAST
SOUNDINGS SHOW A MOISTURE INCREASING THROUGH AND ABOVE THE FRONTAL
INVERSION BETWEEN 2500-7000 FEET LATER THIS MORNING...BUT WITHOUT AN
INCOMING UPPER DISTURBANCE OR ANY FAVORABLY POSITIONED JET STREAKS
TO PROMOTE SYNOPTIC LIFTING WE MAY SEE SKIES CLEAR OUT EARLIER THAN
THE SKY LINE IN THE GFS/NAM MOS BULLETINS SUGGEST. THIS WILL HAVE
IMPLICATIONS ON THE HIGH TEMPERATURE FORECAST AS WELL...AND I TEND
TO THINK THE GFS MOS HIGHS WILL VERIFY BETTER THAN THE COOLER NAM
MOS TODAY. GIVEN THAT THERE IS ALMOST UNANIMOUS SUPPORT IN THE 00Z
MODELS FOR SOME LIGHT POST-FRONTAL RAIN THIS MORNING I AM KEEPING A
20 POP IN THE FORECAST...ALTHOUGH IT`S TOUGH TO PIN DOWN EXACTLY
WHAT THE CAUSATIVE FACTOR WILL BE.
MOISTURE PUSHES OFFSHORE BY THIS EVENING WITH CLEAR SKIES
DEVELOPING. INITIALLY VERY LIGHT WINDS AT THE SURFACE AND 1000 FEET
UP WILL PROMOTE THE DEVELOPMENT OF A STRONG RADIATIONAL INVERSION
WITH TEMPERATURES FALLING INTO THE 40S BY 2 AM INLAND. AS HIGH
PRESSURE OVER THE OHIO VALLEY STRENGTHENS AND INCREASES OUR BOUNDARY
LAYER WINDS LATE...TEMPS WILL DRIFT ONLY ANOTHER FEW DEGREES DOWN BY
DAYBREAK WITH LOWS RANGING FROM THE LOW TO MID 40S INLAND...AND
UPPER 40S TO AROUND 50 ON THE BEACHES.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...THE MAIN FEATURE FOR THE SHORT TERM PERIOD IS
THE SHORTWAVE NOW CLEARLY SEEN IN SATELLITE IMAGERY ENTERING THE
SOUTHWEST. THIS SYSTEM WILL MOVE QUICKLY ACROSS THE CONUS AS IT
TRANSITIONS FROM A CLOSED LOW TO OPEN WAVE.
MODEL GUIDANCE HAS TRENDED SLOWER WITH THE SYSTEM AND IT NOW APPEARS
SATURDAY WILL BE A RELATIVELY NICE DAY WITH HIGH LEVEL MOISTURE
STREAMING ACROSS. I HAVE ALL BUT REMOVED THE MENTION OF POPS. I
WALKED BACK CHANCE VALUES FOR OVERNIGHT SATURDAY INTO SUNDAY MORNING
AS WELL AND WOULD NOT BE SURPRISED TO SEE POPS DELAYED FURTHER WITH
SUBSEQUENT MODEL GUIDANCE.
COOL HIGH PRESSURE FROM THE NORTHEAST WILL KEEP TEMPERATURES
SLIGHTLY BELOW CLIMATOLOGY ALTHOUGH STRONG LATE APRIL INSOLATION
SHOULD PROVIDE A BOOST FRIDAY MITIGATED SOMEWHAT BY THE CLOUD COVER
SATURDAY. I DID INCREASE HIGHS FOR SATURDAY ALTHOUGH THEY REMAIN
COOLER THAN FRIDAY.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 3 AM WEDNESDAY...EXTENDED FORECAST REMAINS SOMEWHAT UNCERTAIN
MAINLY BEYOND SUNDAY WHEN CHANCE POPS REMAIN IN THE FORECAST VIA THE
SYSTEM NOW MOVING INTO THE SOUTHWEST. IT APPEARS A LOT OF THE
MOISTURE GENERATED BY FORECAST MODELS IS THE RESULT OF WEAK COLD AIR
DAMMING TO THE WEST. MORE SIGNIFICANT AND PROBABLY MORE REALISTIC
QPF IS ASSOCIATED WITH A LINGERING COASTAL TROUGH ACROSS MUCH OF OUR
AREA. I DID DECREASE POPS ALBEIT INCREMENTALLY MONDAY THROUGH
WEDNESDAY JUST TO REPRESENT THIS TREND. WE ARE GETTING INTO THE
SEASON WHERE MINIMAL FORCING CAN RESULT IN CONVECTION HOWEVER. NO
CHANGES TO TEMPERATURE FORECAST.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
AS OF 06Z...THE COLD FRONT IS SLOWING MAKING ITS WAY TOWARDS THE
EASTERN CAROLINAS...BUT CURRENT RADAR MOSAIC SHOWS NO PCPN
ASSOCIATED WITH THE FRONT. I EXPECT FROPA AROUND 11Z AT
KFLO/KLBT AND 12-13Z AT KILM/KMYR/KCRE. HOWEVER...HAVE JUST INCLUDED
VCSH FOR ALL TERMS AS RAIN CHANCES HAVE DIMINISHED. IT APPEARS THAT
VFR CONDITIONS WILL PREVAIL ACROSS THE AREA TODAY. TEMPO MVFR CIGS
ARE STILL POSSIBLE...BUT GUIDANCE HAS BACKED OFF OF THIS AS WELL.
WINDS WILL VEER TO THE N/NW FOLLOWING FROPA...BECOMING NE 10-15 KTS
AFTER DAYBREAK. SKIES WILL BEGIN CLEARING AFTER 00Z FRIDAY...AND THE
WINDS WILL BECOME AOB 5 KTS AFTER SUNSET.
EXTENDED OUTLOOK...CHANCE OF SHOWERS/MVFR LATE SATURDAY THRU MONDAY.
OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 630 AM THURSDAY...NO SIGNIFICANT CHANGES ARE NEEDED TO THE
FORECAST. THE COLD FRONT IS RUNNING 30-45 MINUTES BEHIND SCHEDULE
ACROSS CENTRAL AND EASTERN NORTH CAROLINA WHICH SIMPLY DELAYS THE
VEERING TO NORTH WINDS A LITTLE LATER IN THE MORNING. PREVIOUS
DISCUSSION FROM 300 AM FOLLOWS...
A COLD FRONT ZIPPING SOUTHEASTWARD ACROSS CENTRAL NORTH CAROLINA
WILL MAKE IT INTO THE COASTAL WATERS BETWEEN 8 AND 11 AM...WITH
FAIRLY LIGHT SOUTHWEST WINDS SHIFTING TO THE NORTH AND INCREASING TO
15 KNOTS WITH HIGHER GUSTS. THIS FRONTAL SURGE WILL BE
SHORT-LIVED...AND WITHIN JUST A COUPLE OF HOURS NORTHEAST WINDS
SHOULD DIE DOWN TO 10-12 KNOTS. ALTHOUGH RADARS ACROSS THE CAROLINAS
SHOW LITTLE IF ANY RAIN ACCOMPANYING THE FRONT NOW MODELS SUGGEST AT
LEAST A FEW PATCHES OF RAIN WILL DEVELOP ACROSS THE COASTAL WATERS
LATE THIS MORNING...DISSIPATING DURING THE AFTERNOON HOURS.
FOR TONIGHT HIGH PRESSURE OVER THE OHIO VALLEY WILL GAIN STRENGTH
WITH ITS CENTRAL PRESSURE INCREASING 6 MILLIBARS OVER A 12 HOUR
PERIOD. THIS WILL BUILD THE PRESSURE GRADIENT OVER THE CAROLINAS
WITH THE COLD FRONT STALLING A FEW HUNDRED MILES OFFSHORE...AND
WINDS WILL AGAIN INCREASE TO 15 KNOTS WITH HIGHER GUSTS. THIS WILL
BE A LONGER DURATION OF WINDIER CONDITIONS COMPARED TO THIS
MORNING...AND SEAS WILL BUILD TO 4-5 FEET AWAY FROM SHORE LATE
TONIGHT.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...A DECENT NORTHEASTERLY FLOW WILL BE IN PLACE
AT THE BEGINNING OF THE PERIOD ON THE ORDER OF 10-15 KNOTS WITH A
FEW PLACES ACROSS THE OUTER WATERS SEEING JUST OVER 15. AS COLD AIR
ADVECTION WANES SO WILL THE WINDS BUT HIGH PRESSURE TO THE NORTHEAST
WILL KEEP THIS FLOW IN PLACE WITH A SLIGHT DIURNAL VEERING VIA THE
SEABREEZE. SWAN SEAS ARE JUST UNDER SMALL CRAFT CRITERIA EARLY
FRIDAY...3-5 FEET DROPPING TO 2-4 FEET BY SATURDAY.
LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM THURSDAY...WINDS AND SEAS WILL BE DICTATED BY THE
POSITION OF A COASTAL TROUGH/WARM FRONT LURKING JUST OFFSHORE. THE
SEA BREEZE...MORE LIKELY TO BE IN PLACE MONDAY WILL PLAY A ROLE AS
WELL. THE FORECAST HAS EASTERLY WINDS THROUGHOUT THE PERIOD
BASICALLY ON THE LOWER END OF A 10-15 KNOT RANGE. SEAS WILL HOVER IN
A 2-4 FT RANGE.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SHK
NEAR TERM...TRA
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
305 AM EDT THU APR 25 2013
.SYNOPSIS...
A COLD FRONT WILL MOVE ACROSS THE AREA THIS MORNING WITH THE
POSSIBILITY OF A FEW SHOWERS AND INCREASED CLOUD COVER. FRIDAY AND
SATURDAY LOOK GENERALLY NICE COURTESY OF HIGH PRESSURE TO THE
NORTHEAST. UNSETTLED CONDITIONS WILL RETURN SUNDAY AND CONTINUE
INTO THE NEW WORK WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM THURSDAY...GENTLE SOUTHWEST BREEZES EARLY THIS MORNING
WILL COME TO A CRASHING END IN JUST A FEW HOURS AS A COLD FRONT
PLOWS SOUTHEASTWARD OUT OF CENTRAL NORTH CAROLINA. LINEAR
EXTRAPOLATION OF THIS FRONT`S MOVEMENT AGREES RATHER WELL WITH THE
LATEST HRRR MODEL...WITH THE WIND SHIFT REACHING LUMBERTON AROUND
630 AM...FLORENCE AROUND 700 AM...WILMINGTON AROUND 800 AM...AND THE
MYRTLE BEACH AROUND BY 900 AM. THERE WILL BE A 2-3 HOUR PERIOD OF
GUSTY NORTH WINDS IMMEDIATELY BEHIND THE FRONT AS COLD ADVECTION
PROMOTES MIXING UP INTO STRONGER FLOW ALOFT...BUT THIS MOMENTUM WILL
DISSIPATE BY NOON WITH LIGHTER NORTHEAST WINDS EXPECTED THROUGH THE
DAY.
BESIDES PATCHES OF ALTOCUMULUS ACROSS SOUTH CAROLINA THERE AREN`T
THAT MANY CLOUDS OUT AHEAD OF THE FRONT CURRENTLY. MODEL FORECAST
SOUNDINGS SHOW A MOISTURE INCREASING THROUGH AND ABOVE THE FRONTAL
INVERSION BETWEEN 2500-7000 FEET LATER THIS MORNING...BUT WITHOUT AN
INCOMING UPPER DISTURBANCE OR ANY FAVORABLY POSITIONED JET STREAKS
TO PROMOTE SYNOPTIC LIFTING WE MAY SEE SKIES CLEAR OUT EARLIER THAN
THE SKY LINE IN THE GFS/NAM MOS BULLETINS SUGGEST. THIS WILL HAVE
IMPLICATIONS ON THE HIGH TEMPERATURE FORECAST AS WELL...AND I TEND
TO THINK THE GFS MOS HIGHS WILL VERIFY BETTER THAN THE COOLER NAM
MOS TODAY. GIVEN THAT THERE IS ALMOST UNANIMOUS SUPPORT IN THE 00Z
MODELS FOR SOME LIGHT POST-FRONTAL RAIN THIS MORNING I AM KEEPING A
20 POP IN THE FORECAST...ALTHOUGH IT`S TOUGH TO PIN DOWN EXACTLY
WHAT THE CAUSATIVE FACTOR WILL BE.
MOISTURE PUSHES OFFSHORE BY THIS EVENING WITH CLEAR SKIES
DEVELOPING. INITIALLY VERY LIGHT WINDS AT THE SURFACE AND 1000 FEET
UP WILL PROMOTE THE DEVELOPMENT OF A STRONG RADIATIONAL INVERSION
WITH TEMPERATURES FALLING INTO THE 40S BY 2 AM INLAND. AS HIGH
PRESSURE OVER THE OHIO VALLEY STRENGTHENS AND INCREASES OUR BOUNDARY
LAYER WINDS LATE...TEMPS WILL DRIFT ONLY ANOTHER FEW DEGREES DOWN BY
DAYBREAK WITH LOWS RANGING FROM THE LOW TO MID 40S INLAND...AND
UPPER 40S TO AROUND 50 ON THE BEACHES.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...THE MAIN FEATURE FOR THE SHORT TERM PERIOD IS THE
SHORTWAVE NOW CLEARLY SEEN IN SATELLITE IMAGERY ENTERING THE
SOUTHWEST. THIS SYSTEM WILL MOVE QUICKLY ACROSS THE CONUS AS IT
TRANSITIONS FROM A CLOSED LOW TO OPEN WAVE.
MODEL GUIDANCE HAS TRENDED SLOWER WITH THE SYSTEM AND IT NOW APPEARS
SATURDAY WILL BE A RELATIVELY NICE DAY WITH HIGH LEVEL MOISTURE
STREAMING ACROSS. I HAVE ALL BUT REMOVED THE MENTION OF POPS. I
WALKED BACK CHANCE VALUES FOR OVERNIGHT SATURDAY INTO SUNDAY MORNING
AS WELL AND WOULD NOT BE SURPRISED TO SEE POPS DELAYED FURTHER WITH
SUBSEQUENT MODEL GUIDANCE.
COOL HIGH PRESSURE FROM THE NORTHEAST WILL KEEP TEMPERATURES
SLIGHTLY BELOW CLIMATOLOGY ALTHOUGH STRONG LATE APRIL INSOLATION
SHOULD PROVIDE A BOOST FRIDAY MITIGATED SOMEWHAT BY THE CLOUD COVER
SATURDAY. I DID INCREASE HIGHS FOR SATURDAY ALTHOUGH THEY REMAIN
COOLER THAN FRIDAY.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 3 AM WEDNESDAY...EXTENDED FORECAST REMAINS SOMEWHAT UNCERTAIN MAINLY
BEYOND SUNDAY WHEN CHANCE POPS REMAIN IN THE FORECAST VIA THE SYSTEM
NOW MOVING INTO THE SOUTHWEST. IT APPEARS A LOT OF THE MOISTURE
GENERATED BY FORECAST MODELS IS THE RESULT OF WEAK COLD AIR DAMMING
TO THE WEST. MORE SIGNIFICANT AND PROBABLY MORE REALISTIC QPF IS
ASSOCIATED WITH A LINGERING COASTAL TROUGH ACROSS MUCH OF OUR AREA.
I DID DECREASE POPS ALBEIT INCREMENTALLY MONDAY THROUGH WEDNESDAY
JUST TO REPRESENT THIS TREND. WE ARE GETTING INTO THE SEASON WHERE
MINIMAL FORCING CAN RESULT IN CONVECTION HOWEVER. NO CHANGES TO
TEMPERATURE FORECAST.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
AS OF 06Z...THE COLD FRONT IS SLOWING MAKING ITS WAY TOWARDS THE
EASTERN CAROLINAS...BUT CURRENT RADAR MOSAIC SHOWS NO PCPN
ASSOCIATED WITH THE FRONT. I EXPECT FROPA AROUND 11Z AT
KFLO/KLBT AND 12-13Z AT KILM/KMYR/KCRE. HOWEVER...HAVE JUST INCLUDED
VCSH FOR ALL TERMS AS RAIN CHANCES HAVE DIMINISHED. IT APPEARS THAT
VFR CONDITIONS WILL PREVAIL ACROSS THE AREA TODAY. TEMPO MVFR CIGS
ARE STILL POSSIBLE...BUT GUIDANCE HAS BACKED OFF OF THIS AS WELL.
WINDS WILL VEER TO THE N/NW FOLLOWING FROPA...BECOMING NE 10-15 KTS
AFTER DAYBREAK. SKIES WILL BEGIN CLEARING AFTER 00Z FRIDAY...AND THE
WINDS WILL BECOME AOB 5 KTS AFTER SUNSET.
EXTENDED OUTLOOK...CHANCE OF SHOWERS/MVFR LATE SATURDAY THRU MONDAY.
OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 3 AM THURSDAY...A COLD FRONT ZIPPING SOUTHEASTWARD ACROSS
CENTRAL NORTH CAROLINA WILL MAKE IT INTO THE COASTAL WATERS BETWEEN
8 AND 11 AM...WITH FAIRLY LIGHT SOUTHWEST WINDS SHIFTING TO THE
NORTH AND INCREASING TO 15 KNOTS WITH HIGHER GUSTS. THIS FRONTAL
SURGE WILL BE SHORT-LIVED...AND WITHIN JUST A COUPLE OF HOURS
NORTHEAST WINDS SHOULD DIE DOWN TO 10-12 KNOTS. ALTHOUGH RADARS
ACROSS THE CAROLINAS SHOW LITTLE IF ANY RAIN ACCOMPANYING THE FRONT
NOW MODELS SUGGEST AT LEAST A FEW PATCHES OF RAIN WILL DEVELOP
ACROSS THE COASTAL WATERS LATE THIS MORNING...DISSIPATING DURING THE
AFTERNOON HOURS.
FOR TONIGHT HIGH PRESSURE OVER THE OHIO VALLEY WILL GAIN STRENGTH
WITH ITS CENTRAL PRESSURE INCREASING 6 MILLIBARS OVER A 12 HOUR
PERIOD. THIS WILL BUILD THE PRESSURE GRADIENT OVER THE CAROLINAS
WITH THE COLD FRONT STALLING A FEW HUNDRED MILES OFFSHORE...AND
WINDS WILL AGAIN INCREASE TO 15 KNOTS WITH HIGHER GUSTS. THIS WILL
BE A LONGER DURATION OF WINDIER CONDITIONS COMPARED TO THIS
MORNING...AND SEAS WILL BUILD TO 4-5 FEET AWAY FROM SHORE LATE
TONIGHT.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 3 AM THURSDAY...A DECENT NORTHEASTERLY FLOW WILL BE IN PLACE AT
THE BEGINNING OF THE PERIOD ON THE ORDER OF 10-15 KNOTS WITH A FEW
PLACES ACROSS THE OUTER WATERS SEEING JUST OVER 15. AS COLD AIR
ADVECTION WANES SO WILL THE WINDS BUT HIGH PRESSURE TO THE
NORTHEAST WILL KEEP THIS FLOW IN PLACE WITH A SLIGHT DIURNAL
VEERING VIA THE SEABREEZE. SWAN SEAS ARE JUST UNDER SMALL CRAFT
CRITERIA EARLY FRIDAY...3-5 FEET DROPPING TO 2-4 FEET BY SATURDAY.
LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 3 AM THURSDAY...WINDS AND SEAS WILL BE DICTATED BY THE POSITION
OF A COASTAL TROUGH/WARM FRONT LURKING JUST OFFSHORE. THE SEA
BREEZE...MORE LIKELY TO BE IN PLACE MONDAY WILL PLAY A ROLE AS WELL.
THE FORECAST HAS EASTERLY WINDS THROUGHOUT THE PERIOD BASICALLY ON
THE LOWER END OF A 10-15 KNOT RANGE. SEAS WILL HOVER IN A 2-4 FT
RANGE.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SHK
NEAR TERM...TRA
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
140 PM EDT THU APR 25 2013
.SYNOPSIS...
A WEAK DISTURBANCE CONTAINING LIMITED MOISTURE WILL CROSS THE
GREAT LAKES TODAY. HIGH PRESSURE AND DRY AIR WILL BUILD IN FOR
TONIGHT AND FRIDAY. LOW PRESSURE TRAVELING NEAR THE OHIO RIVER
WILL BRING A CHANCE OF SHOWERS ON SATURDAY AND SUNDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WEAK CDFNT AND H5 S/W ARE WORKING ACROSS THE REGION ATTM. LATEST
HRRR AND RAP RUNS ARE INDICATING THAT THE CHC OF SHOWERS MIGHT
DEVELOP MORE DURING THE AFTN IN THE BETTER INSTABILITY AND MIGHT
DEVELOP A LITTLE FARTHER S DOWN THE SCIOTO VALLEY. SO ADJUSTED THE
CHC OF SHRA LATE THIS MORNING TO ONLY THE EXTREME NW
COUNTIES...THEN AS THE AFTN HEATING KICKS IN DEVELOPED SHRA IN THE E
AND TOOK TO THE CHC DOWN TO ROSS COUNTY. KEPT THE POPS ONLY 20-30
HOWEVER.
MADE LITTLE ADJUSTMENT TO THE AFTN HIGHS. KEPT THE HIGHS IN THE UPPER
30S IN THE NW...RANGING TO THE UPPER 50S IN NRN KY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
THE CENTER OF HIGH PRESSURE WILL CROSS OHIO TONIGHT THEN INTO
PENNSYLVANIA ON FRIDAY. THIS WILL BRING A PERIOD OF DRY WEATHER
AND CLEAR SKIES. FROST WILL FORM AGAIN LATE TONIGHT THROUGH EARLY
FRIDAY MORNING WHEN TEMPERATURES WILL FALL INTO THE 30S. FROST
WILL MELT QUICKLY AFTER SUNRISE AND TEMPERATURES WILL RISE TO THE
LOWER 60S DURING FRIDAY AFTERNOON.
WEAK LOW PRESSURE WILL BE MOVING INTO THE LOWER OHIO RIVER
VALLEY ON SATURDAY. AIDED BY A COLD POOL ASSOCIATED WITH A 500 MB
TROUGH...THIS SYSTEM WILL CONTAIN ENOUGH FORCING AND MOISTURE TO
ALLOW A CHANCE OF SHOWERS ON SATURDAY...MAINLY FOR SOUTHERN
LOCATIONS. AFTER A MILDER FRIDAY NIGHT WITH LOWS IN THE
40S...TEMPERATURES ENHANCED BY WARM ADVECTION WILL TOP OUT IN THE
MID AND UPPER 60S ON SATURDAY.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
SURFACE HIGH PRESSURE WILL BE DEPARTING THE CWA AT THE START OF THE
EXTENDED FORECAST PERIOD. MODEL AGREEMENT IS RELATIVELY POOR IN
HANDLING THE EVOLUTION OF A SLOW-MOVING MID-LEVEL TROUGH OVER THE
WEEKEND. EVEN AT 72HR ON THE 12Z GFSE...THERE IS SIGNIFICANT SPREAD
BETWEEN THE ENSEMBLE MEMBERS ON THE STRENGTH AND PLACEMENT OF THE
TROUGH. THE OPERATIONAL GFS SEEMS TO BE STRONGER WITH THE TROUGH
THAN MOST OF ITS MEMBERS...WHILE THE OPERATIONAL 12Z ECMWF IS A BIT
CLOSER TO THE GFSE MEAN.
LEANING TOWARD THE SLIGHTLY WEAKER SOLUTION WOULD PROVIDE LESS IN
THE WAY OF PRECIPITATION THAN THE OPERATIONAL GFS INDICATES.
THUS...THE FORECAST WILL START DRY...AND POPS WILL GENERALLY BE HELD
IN THE 20-40 CATEGORY AND NO HIGHER (THOUGH IT WILL BE WETTER
FURTHER SOUTH IN THE TENNESSEE VALLEY). THE HIGHEST POPS WERE
ROUGHLY TIMED TO THE DIURNAL CYCLE.
BY MONDAY...THE AXIS OF THE TROUGH WILL BE MOVING EAST OF THE
REGION...AS A BIG CHANGE TO THE WEATHER PATTERN BEGINS. THERE IS
SOME DEGREE OF AGREEMENT REGARDING THE LARGE-SCALE EVOLUTION NEXT
WEEK...WITH SIGNS OF HIGHLY-AMPLIFIED HIGH PRESSURE DEVELOPING FROM
THE DEEP SOUTH THROUGH THE OHIO VALLEY AND INTO ONTARIO. IN
FACT...BY THE VERY END OF THE EXTENDED FORECAST (AND INTO LATE WEEK)
BOTH 12Z OPERATIONAL RUNS (GFS/ECMWF) AND THE 00Z ECMWF SHOW A
FULL-OUT OMEGA BLOCK DEVELOPING (TROUGH IN THE CENTRAL PLAINS /
RIDGE THROUGH THE EASTERN STATES / TROUGH OVER THE ATLANTIC). WITH
THIS AGREEMENT...THE 12Z CMC (WHICH DEVELOPS A CLOSED LOW OVER THE
DEEP SOUTH ON TUESDAY) WAS NOT USED FOR THE FORECAST.
THROUGH THE FIRST PART OF THE WEEK...DIURNALLY-DRIVEN POPS WERE
MAINTAINED (THOUGH GRADUALLY DECREASING EACH DAY AS THE RIDGE
BUILDS). SIGNIFICANT PRECIPITATION APPEARS TO REMAIN WEST OF THE ILN
CWA THROUGH AT LEAST WEDNESDAY. TEMPERATURES APPEAR TO SLOWLY RISE
THROUGH THIS PERIOD AS WELL...WITH NO SIGNIFICANT DIFFERENCES
OBSERVED IN THE RECENT MODEL RUNS (AND ONLY SMALL CHANGES MADE TO
THE GOING FORECAST). WITH THE ILN CWA LOOKING TO BE ON THE WEST SIDE
OF THE BUILDING RIDGE (AND ASSOCIATED SURFACE HIGH)...SUCH A PATTERN
WILL FAVOR SOUTHERLY FLOW.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
H5 S/W SWINGING THRU THE GREAT LAKES ATTM...IS PUSHING ANOTHER
WEAK SFC FRONT/TROF ACROSS THE REGION. WITH LIFT AND CAA...AN AREA
OF VFR CLOUDS HAVE DEVELOPED AND WILL MOVE ACROSS THE TAF SITES
DURING THE FIRST PART OF THE TAF PERIOD. WINDS WILL SHIFT FROM THE
SW TO W WITH FROPA...WHICH IS CURRENTLY TIMED TO 19Z-20Z IN THE W
AND 21-22Z IN THE E. A FEW SCT SHRA MIGHT DEVELOP WITH FROPA.
KEPT A MENTION OF A VCSH IN THE CMH/LCK TAFS...WHERE THE BEST
CHANCE OF PCPN IS.
THE S/W WILL SLIP E OF THE REGION BY 00Z AND SKIES SHOULD RAPIDLY
CLEAR WHILE WINDS GO LIGHT AND VARIABLE.
BY 12Z FRIDAY...SOME H5 AND H5 MOISTURE WILL BEGIN TO WORK INTO THE
TAFS...BRINGING SOME CI.
OUTLOOK...MVFR CONDITIONS POSSIBLE SATURDAY NIGHT INTO SUNDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...CONIGLIO
NEAR TERM...SITES
SHORT TERM...CONIGLIO
LONG TERM...HATZOS
AVIATION...SITES
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1055 AM EDT THU APR 25 2013
.SYNOPSIS...
A WEAK DISTURBANCE CONTAINING LIMITED MOISTURE WILL CROSS THE
GREAT LAKES TODAY. HIGH PRESSURE AND DRY AIR WILL BUILD IN FOR
TONIGHT AND FRIDAY. LOW PRESSURE TRAVELING NEAR THE OHIO RIVER
WILL BRING A CHANCE OF SHOWERS ON SATURDAY AND SUNDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WEAK CDFNT AND H5 S/W ARE WORKING ACROSS THE REGION ATTM. LATEST
HRRR AND RAP RUNS ARE INDICATING THAT THE CHC OF SHOWERS MIGHT
DEVELOP MORE DURING THE AFTN IN THE BETTER INSTABILITY AND MIGHT
DEVELOP A LITTLE FARTHER S DOWN THE SCIOTO VALLEY. SO ADJUSTED THE
CHC OF SHRA LATE THIS MORNING TO ONLY THE EXTREME NW
COUNTIES...THEN AS THE AFTN HEATING KICKS IN DEVELOPED SHRA IN THE E
AND TOOK TO THE CHC DOWN TO ROSS COUNTY. KEPT THE POPS ONLY 20-30
HOWEVER.
MADE LITTLE ADJUSTMENT TO THE AFTN HIGHS. KEPT THE HIGHS IN THE UPPER
30S IN THE NW...RANGING TO THE UPPER 50S IN NRN KY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
THE CENTER OF HIGH PRESSURE WILL CROSS OHIO TONIGHT THEN INTO
PENNSYLVANIA ON FRIDAY. THIS WILL BRING A PERIOD OF DRY WEATHER
AND CLEAR SKIES. FROST WILL FORM AGAIN LATE TONIGHT THROUGH EARLY
FRIDAY MORNING WHEN TEMPERATURES WILL FALL INTO THE 30S. FROST
WILL MELT QUICKLY AFTER SUNRISE AND TEMPERATURES WILL RISE TO THE
LOWER 60S DURING FRIDAY AFTERNOON.
WEAK LOW PRESSURE WILL BE MOVING INTO THE LOWER OHIO RIVER
VALLEY ON SATURDAY. AIDED BY A COLD POOL ASSOCIATED WITH A 500 MB
TROUGH...THIS SYSTEM WILL CONTAIN ENOUGH FORCING AND MOISTURE TO
ALLOW A CHANCE OF SHOWERS ON SATURDAY...MAINLY FOR SOUTHERN
LOCATIONS. AFTER A MILDER FRIDAY NIGHT WITH LOWS IN THE
40S...TEMPERATURES ENHANCED BY WARM ADVECTION WILL TOP OUT IN THE
MID AND UPPER 60S ON SATURDAY.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
SURFACE HIGH PRESSURE WILL BE DEPARTING THE CWA AT THE START OF THE
EXTENDED FORECAST PERIOD. MODEL AGREEMENT IS RELATIVELY POOR IN
HANDLING THE EVOLUTION OF A SLOW-MOVING MID-LEVEL TROUGH OVER THE
WEEKEND. EVEN AT 72HR ON THE 12Z GFSE...THERE IS SIGNIFICANT SPREAD
BETWEEN THE ENSEMBLE MEMBERS ON THE STRENGTH AND PLACEMENT OF THE
TROUGH. THE OPERATIONAL GFS SEEMS TO BE STRONGER WITH THE TROUGH
THAN MOST OF ITS MEMBERS...WHILE THE OPERATIONAL 12Z ECMWF IS A BIT
CLOSER TO THE GFSE MEAN.
LEANING TOWARD THE SLIGHTLY WEAKER SOLUTION WOULD PROVIDE LESS IN
THE WAY OF PRECIPITATION THAN THE OPERATIONAL GFS INDICATES.
THUS...THE FORECAST WILL START DRY...AND POPS WILL GENERALLY BE HELD
IN THE 20-40 CATEGORY AND NO HIGHER (THOUGH IT WILL BE WETTER
FURTHER SOUTH IN THE TENNESSEE VALLEY). THE HIGHEST POPS WERE
ROUGHLY TIMED TO THE DIURNAL CYCLE.
BY MONDAY...THE AXIS OF THE TROUGH WILL BE MOVING EAST OF THE
REGION...AS A BIG CHANGE TO THE WEATHER PATTERN BEGINS. THERE IS
SOME DEGREE OF AGREEMENT REGARDING THE LARGE-SCALE EVOLUTION NEXT
WEEK...WITH SIGNS OF HIGHLY-AMPLIFIED HIGH PRESSURE DEVELOPING FROM
THE DEEP SOUTH THROUGH THE OHIO VALLEY AND INTO ONTARIO. IN
FACT...BY THE VERY END OF THE EXTENDED FORECAST (AND INTO LATE WEEK)
BOTH 12Z OPERATIONAL RUNS (GFS/ECMWF) AND THE 00Z ECMWF SHOW A
FULL-OUT OMEGA BLOCK DEVELOPING (TROUGH IN THE CENTRAL PLAINS /
RIDGE THROUGH THE EASTERN STATES / TROUGH OVER THE ATLANTIC). WITH
THIS AGREEMENT...THE 12Z CMC (WHICH DEVELOPS A CLOSED LOW OVER THE
DEEP SOUTH ON TUESDAY) WAS NOT USED FOR THE FORECAST.
THROUGH THE FIRST PART OF THE WEEK...DIURNALLY-DRIVEN POPS WERE
MAINTAINED (THOUGH GRADUALLY DECREASING EACH DAY AS THE RIDGE
BUILDS). SIGNIFICANT PRECIPITATION APPEARS TO REMAIN WEST OF THE ILN
CWA THROUGH AT LEAST WEDNESDAY. TEMPERATURES APPEAR TO SLOWLY RISE
THROUGH THIS PERIOD AS WELL...WITH NO SIGNIFICANT DIFFERENCES
OBSERVED IN THE RECENT MODEL RUNS (AND ONLY SMALL CHANGES MADE TO
THE GOING FORECAST). WITH THE ILN CWA LOOKING TO BE ON THE WEST SIDE
OF THE BUILDING RIDGE (AND ASSOCIATED SURFACE HIGH)...SUCH A PATTERN
WILL FAVOR SOUTHERLY FLOW.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
SFC HIGH PRESSURE TO SLIDE EAST ACRS THE REGION THIS MORNING. THIS
HI HAS PROVIDED LIGHT WINDS...MAINLY CLEAR SKIES AND GOOD SETUP FOR
RADIATIONAL COOLING. WITH RECENT RAINFALL AND MOIST GROUND...
FOG HAS DEVELOPED THIS MORNING. HAVE MVFR VSBY RESTRICTIONS AT
KCVG...KCMH AND KLCK WITH IFR RESTRICTION AT FOG PRONE KLUK.
MID LEVEL S/W TO PIVOT THRU THE GREAT LAKES TODAY. ASSOCIATED SFC
LOW TO TRACK THRU THE GREAT LAKES WITH SFC COLD FRONT DROPPING SE
THRU THE TAF SITES THIS AFTN. HAVE BKN-OVC CLOUDS DEVELOPING
BETWEEN 4000 AND 5000. WITH THE BEST MSTR ACRS THE NORTH A PASSING
SPRINKLE OR SHOWER WILL BE PSBL MAINLY ACRS KDAY/KCMH/KLCK TAF
SITES BUT CONDITIONS SHUD REMAIN VFR. HAVE HANDLED THIS WITH A MENTION
OF VCSH AT THESE TAF SITES DUE TO THE LIMITED COVERAGE.
SW WINDS AT 12 TO 15 KTS WILL BE COMMON WITH AFTERNOON GUSTS UP
TO 22 KTS PSBL. HIGH PRESSURE WILL RE-ESTABLISH ITSELF OVER THE
REGION TONIGHT WITH WINDS BECOMING LIGHT AND SKIES CLEARING OUT.
OUTLOOK...NO SIGNIFICANT WEATHER EXPECTED.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...CONIGLIO
NEAR TERM...SITES
SHORT TERM...CONIGLIO
LONG TERM...HATZOS
AVIATION...AR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
556 PM EDT THU APR 25 2013
.SYNOPSIS...
A WEAKENING COLD FRONT WILL MOVE ACROSS CENTRAL PENNSYLVANIA THIS
EVENING...BRINGING SCATTERED SHOWERS TO MAINLY THE NORTHERN TIER.
HIGH PRESSURE WILL BUILD INTO THE AREA FROM THE SOUTHWEST ON
FRIDAY...BEGINNING A SLOW WARMING TREND THAT WILL CONTINUE
THROUGH THE WEEKEND. A CHANCE FOR SHOWERS RETURNS SUNDAY INTO
MONDAY.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
WEAKENING WAVE APPROACHING FROM THE WEST WILL SLIDE INTO NORTHERN
TIER THIS EVENING...BRINGING SCT TO LIKELY LIGHT SHOWERS.
INSTABILITY IS MARGINAL...BUT A RUMBLE OF THUNDER IS NOT OUT OF
THE QUESTION NEAR KBFD. TRAILING AND WEAKENING COLD FRONT PUSHES
THROUGH QUICKLY THIS EVENING...WITH HRRR INDICATING CHANCE FOR
QUICK SHOWER FOR WESTERN/CENTRAL SECTIONS...BUT THINK THIS IS
OVERDONE WITH DRIER AIR IN PLACE. LOWS AGAIN TURN
CHILLY...BOTTOMING OUT IN THE UPPER 20S TO UPPER 30S AS WINDS
DIMINISH AND CLOUDS THIN OUT OVERNIGHT.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
HIGH PRESSURE BUILDS IN FROM THE SW ON FRIDAY...BRINGING PLENTY
OF SUNSHINE AND LIGHTER WINDS. HIGHS WILL TOP OUT NEAR TODAY/S
VALUES...AGAIN REMAINING ABOUT 3-5F BELOW NORMAL.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
ZONAL UPPER FLOW PATTERN OVER NORTH AMERICA AT THE START OF THE LONG TERM
PERIOD IS FORECAST TO AMPLIFY THROUGH THE REMAINDER OF THE PERIOD.
AN UPPER RIDGE IS FORECAST TO BUILD FROM THE MID ATLANTIC STATES
NORTHWARD INTO THE CANADIAN MARITIMES...AS AN UPPER TROF DEVELOPS
OVER THE CENTRAL U.S. AS PART OF THE DEVELOPING UPPER TROF...BOTH
THE GFS AND ECMWF CLOSE OFF AN UPPER LOW CENTER OVER THE NRN/CENTRAL
PLAINS LATE NEXT WEEK...WHICH COULD HAVE FORECAST CONSEQUENCES
BEYOND THE LONG TERM PERIOD.
AT THE SFC...HIGH PRESSURE IS FORECAST TO REMAIN ANCHORED ALONG THE
NEW ENGLAND TO NOVA SCOTIA COAST THROUGH THE PERIOD. THIS WILL KEEP
PA IN GENERALLY LIGHT SERLY SFC FLOW THROUGH THE PERIOD WITH NO
SIGNIFICANT PCPN EVENTS DURING EXPECTED. HOWEVER...MODEL QPF FIELDS DEPICT
A GREAT DEAL OF LIGHT PCPN OVER AN EXPANSIVE REGION FROM NEW
ENGLAND SOUTH THRU THE CAROLINAS. WITHOUT A FOCUSING
METEOROLOGICAL MECHANISM BELIEVE IT TO BE MODEL PARAMETERIZATIONS
TRYING TO DEVELOP LIGHT PCPN ON THE TERRAIN IN THE SOUTHEAST
FLOW...AND BELIEVE THIS TO BE OVERDONE. THUS HAVE KEPT THE
MAJORITY OF THE FORECAST PERIOD DRY. THERE MAYBE SOME CHANCES FOR
ENHANCED CLOUDS AND LIGHT PCPN/DRIZZLE ON THE SE FLOW...ESPECIALLY OVER
SERN CENTRAL PA...DEPENDING GREATLY ON WHERE HIGH CENTER ENDS UP
DAY TO DAY...BUT AT THIS TIME RANGE IT TOO SOON TO TELL WHEN AND
WHERE BEYOND MINIMAL POPS.
&&
.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
A FAST-MOVING COLD FRONT WILL BRING A FEW RAIN SHOWERS TO
NORTHWEST PA THIS EVENING...PERHAPS RESULTING IN A BRIEF VSBY
REDUCTION AT BFD. THE FRONT AND IT/S ASSOC SHOWERS SHOULD FALL
APART AS IT PRESSES SOUTH THROUGH THE REST OF CENTRAL PA LATE THIS
EVENING. SO...ALTHOUGH MANY CENTRAL PA AIRFIELDS WILL SEE A
PERIOD OF BKN STRATO-CU WITH FROPA LATE THIS EVENING...IT/S VERY
LIKELY THAT CONDS REMAIN VFR.
HIGH PRESSURE BEGINS TO BUILD IN LATE TONIGHT AND CONTINUES
THROUGH FRIDAY...BRINGING WIDESPREAD VFR CONDITIONS AND EXCELLENT
FLYING WEATHER. WINDS WILL BE 10 MPH OR LESS.
.OUTLOOK...
FRI-SAT...VFR. NO SIG WX.
SUN-MON...GENERALLY VFR. NO SIG WX. ISO/SCT SHRA POSS.
TUE...VFR. NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...RXR
NEAR TERM...RXR
SHORT TERM...RXR
LONG TERM...GARTNER
AVIATION...FITZGERALD/RXR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
404 PM EDT THU APR 25 2013
.SYNOPSIS...
A WEAKENING COLD FRONT WILL MOVE ACROSS CENTRAL PENNSYLVANIA THIS
EVENING...BRINGING SCATTERED SHOWERS TO MAINLY THE NORTHERN TIER.
HIGH PRESSURE WILL BUILD INTO THE AREA FROM THE SOUTHWEST ON
FRIDAY...BEGINNING A SLOW WARMING TREND THAT WILL CONTINUE
THROUGH THE WEEKEND. A CHANCE FOR SHOWERS RETURNS SUNDAY INTO
MONDAY.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
WEAKENING WAVE APPROACHING FROM THE WEST WILL SLIDE INTO NORTHERN
TIER THIS EVENING...BRINGING SCT TO LIKELY LIGHT SHOWERS.
INSTABILITY IS MARGINAL...BUT A RUMBLE OF THUNDER IS NOT OUT OF
THE QUESTION NEAR KBFD. TRAILING AND WEAKENING COLD FRONT PUSHES
THROUGH QUICKLY THIS EVENING...WITH HRRR INDICATING CHANCE FOR
QUICK SHOWER FOR WESTERN/CENTRAL SECTIONS...BUT THINK THIS IS
OVERDONE WITH DRIER AIR IN PLACE. LOWS AGAIN TURN
CHILLY...BOTTOMING OUT IN THE UPPER 20S TO UPPER 30S AS WINDS
DIMINISH AND CLOUDS THIN OUT OVERNIGHT.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
HIGH PRESSURE BUILDS IN FROM THE SW ON FRIDAY...BRINGING PLENTY
OF SUNSHINE AND LIGHTER WINDS. HIGHS WILL TOP OUT NEAR TODAY/S
VALUES...AGAIN REMAINING ABOUT 3-5F BELOW NORMAL.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
ZONAL UPPER FLOW PATTERN OVER NORTH AMERICA AT THE START OF THE LONG TERM
PERIOD IS FORECAST TO AMPLIFY THROUGH THE REMAINDER OF THE PERIOD.
AN UPPER RIDGE IS FORECAST TO BUILD FROM THE MID ATLANTIC STATES
NORTHWARD INTO THE CANADIAN MARITIMES...AS AN UPPER TROF DEVELOPS
OVER THE CENTRAL U.S. AS PART OF THE DEVELOPING UPPER TROF...BOTH
THE GFS AND ECMWF CLOSE OFF AN UPPER LOW CENTER OVER THE NRN/CENTRAL
PLAINS LATE NEXT WEEK...WHICH COULD HAVE FORECAST CONSEQUENCES
BEYOND THE LONG TERM PERIOD.
AT THE SFC...HIGH PRESSURE IS FORECAST TO REMAIN ANCHORED ALONG THE
NEW ENGLAND TO NOVA SCOTIA COAST THROUGH THE PERIOD. THIS WILL KEEP
PA IN GENERALLY LIGHT SERLY SFC FLOW THROUGH THE PERIOD WITH NO
SIGNIFICANT PCPN EVENTS DURING EXPECTED. HOWEVER...MODEL QPF FIELDS DEPICT
A GREAT DEAL OF LIGHT PCPN OVER AN EXPANSIVE REGION FROM NEW
ENGLAND SOUTH THRU THE CAROLINAS. WITHOUT A FOCUSING
METEOROLOGICAL MECHANISM BELIEVE IT TO BE MODEL PARAMETERIZATIONS
TRYING TO DEVELOP LIGHT PCPN ON THE TERRAIN IN THE SOUTHEAST
FLOW...AND BELIEVE THIS TO BE OVERDONE. THUS HAVE KEPT THE
MAJORITY OF THE FORECAST PERIOD DRY. THERE MAYBE SOME CHANCES FOR
ENHANCED CLOUDS AND LIGHT PCPN/DRIZZLE ON THE SE FLOW...ESPECIALLY OVER
SERN CENTRAL PA...DEPENDING GREATLY ON WHERE HIGH CENTER ENDS UP
DAY TO DAY...BUT AT THIS TIME RANGE IT TOO SOON TO TELL WHEN AND
WHERE BEYOND MINIMAL POPS.
&&
.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
VFR CONDITIONS ACROSS CENTRAL PA THIS AFTERNOON. AS WEAKENING WAVE
SLIDES INTO THE NORTHERN TIER FROM THE WEST...INITIALLY WINDS WILL
BECOME GUSTY FROM THE SOUTHWEST /UP TO 20 MPH/. AFTER 00Z...SCT
SHOWERS WILL IMPACT KBFD FOR SEVERAL HOURS...WITH EVEN A SMALL
CHANCE FOR AN ISO THUNDERSHOWER. ISOLATED SHOWERS WILL BE POSSIBLE
FOR A SHORT TIME THIS MID EVENING FROM KJST-KAOO-KIPT...BUT
IMPACTS SHOULD BE MINIMAL.
HIGH PRESSURE BEGINS TO BUILD IN LATE TONIGHT AND CONTINUES
THROUGH FRIDAY...BRINGING WIDESPREAD VFR CONDITIONS AND EXCELLENT
FLYING WEATHER. WINDS WILL BE 10 MPH OR LESS.
.OUTLOOK...
FRI-SAT...VFR. NO SIG WX.
SUN-MON...GENERALLY VFR. NO SIG WX. ISO/SCT SHRA POSS.
TUE...VFR. NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...RXR
NEAR TERM...RXR
SHORT TERM...RXR
LONG TERM...GARTNER
AVIATION...RXR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
306 PM EDT THU APR 25 2013
.SYNOPSIS...
A WEAKENING COLD FRONT WILL MOVE ACROSS CENTRAL PENNSYLVANIA THIS
EVENING...BRINGING SCATTERED SHOWERS TO MAINLY THE NORTHERN TIER.
HIGH PRESSURE WILL BUILD INTO THE AREA FROM THE SOUTHWEST ON
FRIDAY...BEGINNING A SLOW WARMING TREND THAT WILL CONTINUE
THROUGH THE WEEKEND. A CHANCE FOR SHOWERS RETURNS SUNDAY INTO
MONDAY.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
WEAKENING WAVE APPROACHING FROM THE WEST WILL SLIDE INTO NORTHERN
TIER THIS EVENING...BRINGING SCT TO LIKELY LIGHT SHOWERS.
INSTABILITY IS MARGINAL...BUT A RUMBLE OF THUNDER IS NOT OUT OF
THE QUESTION NEAR KBFD. TRAILING AND WEAKENING COLD FRONT PUSHES
THROUGH QUICKLY THIS EVENING...WITH HRRR INDICATING CHANCE FOR
QUICK SHOWER FOR WESTERN/CENTRAL SECTIONS...BUT THINK THIS IS
OVERDONE WITH DRIER AIR IN PLACE. LOWS AGAIN TURN
CHILLY...BOTTOMING OUT IN THE UPPER 20S TO UPPER 30S AS WINDS
DIMINISH AND CLOUDS THIN OUT OVERNIGHT.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
HIGH PRESSURE BUILDS IN FROM THE SW ON FRIDAY...BRINGING PLENTY
OF SUNSHINE AND LIGHTER WINDS. HIGHS WILL TOP OUT NEAR TODAY/S
VALUES...AGAIN REMAINING ABOUT 3-5F BELOW NORMAL.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
BROAD CYCLONIC FLOW OVER MUCH OF NORTH AMERICA WILL BEGIN
TRANSITIONING INTO A ZONAL FLOW PATTERN AT THE START OF THE LONG
TERM PERIOD. THE UPPER FLOW PATTERN IS THEN FORECAST TO BEGIN
RE-AMPLIFYING BY LATE IN THE WEEKEND WITH A LONGWAVE RIDGE BUILDING
ALONG THE APPALACHIANS...DOWNSTREAM OF UPPER TROFFING DEVELOPING
ALONG THE NORTHERN AND CENTRAL ROCKIES.
THIS UPPER FLOW PATTERN WILL SUPPORT AN ELONGATED SFC HIGH FROM THE
CANADIAN MARITIMES SOUTHWARD INTO THE CAROLINAS THROUGH THE LONG
TERM PERIOD. THIS WILL PROVIDE NEAR TO SLIGHTLY BELOW NORMAL TEMPS
DEPENDING ON DAILY CLOUD COVER....AND NEAR TO SLIGHTLY ABOVE NORMAL
TEMPS ALONG WITH LITTLE TO IF ANY PRECIPITATION THROUGH THE PERIOD.
&&
.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
VFR CONDITIONS ACROSS CENTRAL PA THIS AFTERNOON. AS WEAKENING WAVE
SLIDES INTO THE NORTHERN TIER FROM THE WEST...INITIALLY WINDS WILL
BECOME GUSTY FROM THE SOUTHWEST /UP TO 20 MPH/. AFTER 00Z...SCT
SHOWERS WILL IMPACT KBFD FOR SEVERAL HOURS...WITH EVEN A SMALL
CHANCE FOR AN ISO THUNDERSHOWER. ISOLATED SHOWERS WILL BE POSSIBLE
FOR A SHORT TIME THIS MID EVENING FROM KJST-KAOO-KIPT...BUT
IMPACTS SHOULD BE MINIMAL.
HIGH PRESSURE BEGINS TO BUILD IN LATE TONIGHT AND CONTINUES
THROUGH FRIDAY...BRINGING WIDESPREAD VFR CONDTIONS AND EXCELLENT
FLYING WEATHER. WINDS WILL BE 10 MPH OR LESS.
.OUTLOOK...
FRI-SAT...VFR. NO SIF WX.
SUN-MON...GENERALLY VFR. NO SIG WX. ISO/SCT SHRA POSS.
TUE...VFR. NO SIF WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...RXR
NEAR TERM...RXR
SHORT TERM...RXR
LONG TERM...DEVOIR/GARTNER
AVIATION...RXR
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
949 PM EDT FRI APR 26 2013
.SYNOPSIS...
AN INCREASINGLY MOIST WEDGE OF COOLER AIR WILL OVERSPREAD THE REGION
THIS WEEKEND AS WEAK LOW PRESSURE MOVES ACROSS THE TENNESSEE VALLEY
ALONG A STALLED COLD FRONT. THE FRONT WILL SLOWLY DISSIPATE AND THE
COOL AIR WEDGE WILL GRADUALLY WEAKEN INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH SATURDAY/...
EVENING UPDATE...THE LATEST IR IMAGERY SHOWS SLOWLY LOWERING ACU
ACROSS THE WRN ZONES AND MORE COVERAGE OVERALL BEGINNING TO ENGULF
THE CWFA. SOME WEAK RETURNS WERE NOTED ON THE 88D ACROSS THE NRN
MTNS ALIGNED WITH STREAMLINED VORT...BUT THESE HAVE SINCE DISSIPATED.
DON/T SEE A REAL GOOD CHANCE OF PRECIP UNTIL THE H92-H85 FLOW
STRENGTHENS AND BRINGS IN HIGHER ATL/GOM MOISTURE TO THE SW/RN
UPSLOPE REGIONS. COMBINED WITH A DEVELOPING YET WEAK WARM FRONTAL
ZONE TO THE WEST AND CONTINUED POCKETS OF SRN STREAM ENERGY
TRAVERSING OVERHEAD...EXPECT SCT -SHRA TO DEVELOP ACROSS THE FAR
SW/RN ZONES AFT 06Z AND GRADUALLY INCREASE IN COVERAGE THROUGH THE
MORNING. THE GOING ABOVE NORMAL MIN TEMPS LOOK GOOD AND BLENDED IN
THE LATEST MAV...WHICH ONLY MADE SUBTLE CHANGES.
630 PM UPDATE...TEMPERATURES ARE RUNNING ABOVE THE FCST CURVE IN
SOME AREAS DUE TO THE LATE ONSET OF HIGH LEVEL BKN/OVC. THE SKY
COVER TRENDS MAY AFFECT OVERNIGHT MINS A LITTLE AND WILL BE
MONITORED. POPS WERE REALIGNED MORE NORTH ACROSS THE WRN MTNS BASED
ON THE FINGER OF PRECIP DISPLAYED ON THE COMP REFL AND HRRR COL MAX
PROGS.
430 PM UPDATE...FCST IS IN GOOD SHAPE. MADE MINOR TWEAKS TO TEMPS
AND TD/S. CLOUD COVER WAS ADJ INCORPORATING THE LATEST VIS
INDICATING BKN/OVC ACU/CI OVER THE WRN NC MTNS. WINDS WERE BUMPED UP
A LITTLE OVER THE MTNS AND BLENDED WITH THE 20Z RAP GUIDANCE.
AS OF 230 PM...LATEST SATELLITE IMAGES AND VIEW OUT OF THE WINDOW
INDICATE THAT THIN CIRRUS HAS STARTED TO SWEEP ACROSS THE FORECAST
AREA...ARRIVING FROM THE WEST. WITH THE ARRIVAL OF THE HIGH
CLOUDS...TEMPERATURES ACROSS THE REGION WILL LIKELY PEAK OVER THE
NEXT HOUR...ESPECIALLY ACROSS THE FOOTHILL AREAS. OVERNIGHT...1030MB
HIGH WILL BECOME CENTERED OVER NEW ENGLAND...RIDGING SW ACROSS THE
CWA. TO THE WEST...LOW PRESSURE IS EXPECTED TO TRACK NE...REACHING
THE ARKLATX BY 12Z SAT. THE ASSOCIATED WARM FRONT WILL LIKELY RUN
ACROSS TN INTO WESTERN NC BY DAYBREAK SAT. SHORT RANGE MODELS
INDICATE THAT A MID LEVEL S/W WILL RIPPLE ACROSS THE MID MISSISSIPPI
RIVER VALLEY THIS EVENING...REACHING KY/TN LATE TONIGHT. THE
COMBINATION OF THE MID LEVEL FORCING...WARM FRONT...AND INCREASING
MOISTURE SHOULD SUPPORT AN EXPANDING AREA OF RAIN WEST OF THE
SOUTHERN APPALACHIANS OVERNIGHT. A BAND OF SHRA IS EXPECTED TO
DEVELOP NORTH OF THE SFC WARM FRONT LATE TONIGHT...SLIDING ACROSS
THE WESTERN AND CENTRAL MOUNTAINS AND NRN SC UPSTATE DURING AROUND
SUNRISE. I WILL INCREASE POPS TO CHC TO LIKELY ACROSS THE NC MTNS
AND ADJACENT FOOTHILLS BY 12Z SAT.
ON SATURDAY...THE CENTER OF THE LOW PRESSURE IS FORECAST TO TRACK
ACROSS THE MID MISSISSIPPI RIVER VALLEY BY 0Z SUN. AS THE LOW TRACKS
NE...THE ASSOCIATED WARM FRONT WILL LIFT NORTH...PIVOTING ACROSS THE
WESTERN NC MTNS DURING THE DAY. I WILL FAVOR THE MTNS AND FOOTHILLS
FOR CATE AND LIKELY POPS. COVERAGE SHOULD PUSH EAST DURING THE MID
AND LATE AFTERNOON ACROSS THE I-77 CORRIDOR. QPF RANGES FROM NEAR
THREE-QUARTERS OF AN INCH ACROSS THE WESTERN NC MTNS TO LESS THAN A
TENTH OF AN INCH EAST OF I-77. BASED ON THE TIMING OF THE PRECIP...I
WILL KEEP HIGH TEMPS LIMITED ACROSS THE MTNS TO THE 50S...POSSIBLY
REACHING THE U60S ACROSS THE EASTERN PIEDMONT.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 230 PM FRI...THE UPSTREAM H5 LOW CENTER WILL SLOWLY OPEN UP
AND LIFT NE ACROSS IL/IN SAT NIGHT THROUGH SUNDAY. MODEL TIME
HEIGHTS AHEAD OF THIS FEATURE SHOW DEEP MOISTURE ARRIVING OVER THE
AREA...WITH UPPER DIVERGENCE DEVELOPING S OF A JETLET THROUGH THE
MID ATLANTIC AREA...AS WELL AS IMPROVING SRLY UPSLOPE FLOW INTO THE
MTNS AND UPGLIDE OVER AN IN SITU SFC CAD LAYER. THE CAD WILL ONLY
GRADUALLY SHALLOW OUT THROUGH SUNDAY GIVEN THE DEEP LAYER SRLY FLOW.
ANY INSTABILITY SUNDAY AFTN SHOULD BE CONFINED TO MAINLY THE SRN
PIEDMONT. THE BEST LOW LEVEL UPGLIDE WILL BE CENTERED OVER THE
FORECAST AREA MIDDAY SUNDAY...WITH A SECONDARY SURGE OF
MOISTURE/FORCING SUNDAY NIGHT AS A COLD FRONT APPROACHES FROM THE W.
QPF WILL BE THE MAIN FORECAST ISSUE DURING THIS PERIOD...WITH THE
SRLY UPSLOPE FLOW LIKELY PRODUCING A LOCAL MAXIMA ALONG S/SE UPSLOPE
PRONE AREAS OF THE SRN APPALACHIANS. THE GFS QPF IS A HIGH END
OUTLIER WITH STORM TOTALS OF 4 TO 5 INCHES IN THE SRN NC MTNS...DUE
MAINLY TO A WAVE RIDING UP THE SRN APPALACHIANS SUNDAY NIGHT. THE
OTHER MODELS/ENSEMBLES FEATURE A CONSENSUS MORE IN THE 3.0 TO 3.5
RANGE IN SRLY UPSLOPE AREAS...IN GOOD AGREEMENT WITH WPC.
PRECIPITABLE WATER ANOMALIES ARE FORECAST TO BE 1 TO 2 STANDARD
DEVIATIONS ABOVE NORMAL...AND ANTECEDENT CONDITIONS ARE FAIRLY DRY.
ALL THINGS CONSIDERED...WILL FEATURE AN HWO MENTION OF ISOLATED
HYDRO PROBLEMS LATE THIS WEEKEND.
DEEPER MOISTURE WILL GRADUALLY DIMINISH FROM THE WEST ON MONDAY AS
THE UPPER SUPPORT LIFTS AWAY NORTH OF THE AREA...BUT THERE WILL BE
PLENTY OF LINGERING SFC TO 850 MB MOISTURE AS THE FRONT WASHES OUT
AND THE LOW LEVEL FLOW VEERS MORE SOUTHWESTERLY. TEMPS WILL REMAIN
COOL OVER THE NW NC PIEDMONT MONDAY...BUT WITH GREATER INSTABILITY
DEVELOPING BACK TO THE SW. WILL FEATURE SHOTGUN CHANCE POPS ON
MAINLY A DIURNAL SCHEDULE FOR SHOWERS AND THUNDERSTORMS
MONDAY...WANING TO SCHC MONDAY NIGHT.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 110 PM FRIDAY...WILL CONTINUE TO GIVE PROPS TO THE 26/00 UTC OP
ECMWF WHICH LINGERS UPPER LEVEL WEAKNESS ATOP THE CWFA THROUGH
TUESDAY. BASED ON THIS...INHERITED SHOTGUN CHANCE POP WILL REMAIN
WITH MAX TEMPS CLOSE TO THE LATE APRIL CLIMO. THE LATEST MEDIUM
RANGE MODEL MASS FIELDS AND ASSOCIATED RESPONSE ARE NOT TOO TERRIBLY
DIFFERENT FOR WEDNESDAY...PROGGING AN INCREASE IN ATLANTIC FETCH
AROUND NEW ENGLAND HIPRES...LEADING TO ONGOING DECENT PCPN CHANCES.
AN INCREASINGLY TRICKY FCST LOOKS TO BE SHAPING UP FOR LATE WEEK AS
DIGGING MID-CONUS L/WV TROUGH SHOULD NUDGE POTENTIALLY WAVY
BAROCLINIC ZONE INTO THE SOUTHERN APPALACHIANS WHILE SOUTHERN STREAM
ENERGY IS PROGGED TO SPIN UP GULF LOW PRESSURE. ON THE 26/00 UTC
ECMWF...THE CWFA IS POSITIONED BETWEEN THE MAIN RESPONSE AREAS OF
THESE TWO FEATURES...WHILE THE NEW 26/12 UTC OP GFS HAS US WELL
WITHIN THE DEEP FORCING AND MOISTURE. AT THIS POINT...THE BEST
COURSE OF ACTION IS TO STICK CLOSE TO THE WPC FCST OF A SOLID
MID CHANCE POP AND SLIGHTLY BELOW NORMAL MAX TEMPERATURES. GIVEN
THE MODEL DIFFERENCES WITH RESPECT TO JUST HOW THE DYNAMIC PATTERN
WILL EVOLVE BY NEXT FRIDAY...FCST CONFIDENCE IS BELOW NORMAL AND
PLAN ON SIMPLY GOING WITH THE WPC FCST OF SOLID MID-CHANCE POP
AND COOLER THAN PERSISTENCE.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...DECENT CONFIDENCE IS HAD IN A VFR FCST THROUGH THE PERIOD.
THE NAMM BUFKIT SOUNDING SHOWS A LOWERING OF CIGS BUT ONLY TO LOW
VFR BY LATE IN THE PERIOD AND ALL MOS KEEPS THINGS LOW VFR AT WORSE
THROUGH 00Z. THIS MAKES SENS WITH THE WEDGE OF DRY AIR TO OVERCOME
BEFORE THE WEDGE BREAKS DOWN. THERE SHOULD BE SOME VICINITY -SHRA
LATE AND HAVE INTRODUCED A PROB30 AFT 20Z.
ELSEWHERE...EXPECT RESTRICTIONS AT KAVL AS THE PRECIP MOVES INTO THE
TERMINAL AREA AROUND DAYBREAK. MVFR AND AND POSSIBLY IFR CIGS SHOULD
PERSIST THROUGH THE PERIOD WITH SOME MVRF VSBY IN -SHRA. THE OTHER
TAF SITES WILL LIKELY SEE A LOWERING OF CIGS TO LOW VFR THROUGH THE
MORNING HRS AND THEN A DROP INTO MVFR THROUGH THE AFTERNOON AS A
WIDESPREAD ISENT PRECIP SHIELD BECOMES ESTABLISHED.
OUTLOOK...A WEDGE OF COLD AIR WILL PERSIST ACROSS THE REGION SUNDAY
AND MONDAY. PERIODIC PRECIPITATION INTO THIS WEDGE WILL CREATE THE
POSSIBILITY OF FLIGHT RESTRICTIONS.
CONFIDENCE TABLE...
01-07Z 07-13Z 13-19Z 19-01Z
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAVL HIGH 100% HIGH 95% MED 68% HIGH 90%
KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGMU HIGH 100% HIGH 100% HIGH 100% MED 79%
KAND HIGH 100% HIGH 100% HIGH 100% HIGH 90%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...CSH
NEAR TERM...NED/SBK
SHORT TERM...HG
LONG TERM...CSH
AVIATION...SBK
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
752 PM EDT FRI APR 26 2013
.SYNOPSIS...
AN INCREASINGLY MOIST WEDGE OF COOLER AIR WILL OVERSPREAD THE REGION
THIS WEEKEND AS WEAK LOW PRESSURE MOVES ACROSS THE TENNESSEE VALLEY
ALONG A STALLED COLD FRONT. THE FRONT WILL SLOWLY DISSIPATE AND THE
COOL AIR WEDGE WILL GRADUALLY WEAKEN INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH SATURDAY/...
630 PM UPDATE...TEMPERATURES ARE RUNNING ABOVE THE FCST CURVE IN
SOME AREAS DUE TO THE LATE ONSET OF HIGH LEVEL BKN/OVC. THE SKY
COVER TRENDS MAY AFFECT OVERNIGHT MINS A LITTLE AND WILL BE
MONITORED. POPS WERE REALIGNED MORE NORTH ACROSS THE WRN MTNS BASED
ON THE FINGER OF PRECIP DISPLAYED ON THE COMP REFL AND HRRR COL MAX
PROGS.
430 PM UPDATE...FCST IS IN GOOD SHAPE. MADE MINOR TWEAKS TO TEMPS
AND TD/S. CLOUD COVER WAS ADJ INCORPORATING THE LATEST VIS
INDICATING BKN/OVC ACU/CI OVER THE WRN NC MTNS. WINDS WERE BUMPED UP
A LITTLE OVER THE MTNS AND BLENDED WITH THE 20Z RAP GUIDANCE.
AS OF 230 PM...LATEST SATELLITE IMAGES AND VIEW OUT OF THE WINDOW
INDICATE THAT THIN CIRRUS HAS STARTED TO SWEEP ACROSS THE FORECAST
AREA...ARRIVING FROM THE WEST. WITH THE ARRIVAL OF THE HIGH
CLOUDS...TEMPERATURES ACROSS THE REGION WILL LIKELY PEAK OVER THE
NEXT HOUR...ESPECIALLY ACROSS THE FOOTHILL AREAS. OVERNIGHT...1030MB
HIGH WILL BECOME CENTERED OVER NEW ENGLAND...RIDGING SW ACROSS THE
CWA. TO THE WEST...LOW PRESSURE IS EXPECTED TO TRACK NE...REACHING
THE ARKLATX BY 12Z SAT. THE ASSOCIATED WARM FRONT WILL LIKELY RUN
ACROSS TN INTO WESTERN NC BY DAYBREAK SAT. SHORT RANGE MODELS
INDICATE THAT A MID LEVEL S/W WILL RIPPLE ACROSS THE MID MISSISSIPPI
RIVER VALLEY THIS EVENING...REACHING KY/TN LATE TONIGHT. THE
COMBINATION OF THE MID LEVEL FORCING...WARM FRONT...AND INCREASING
MOISTURE SHOULD SUPPORT AN EXPANDING AREA OF RAIN WEST OF THE
SOUTHERN APPALACHIANS OVERNIGHT. A BAND OF SHRA IS EXPECTED TO
DEVELOP NORTH OF THE SFC WARM FRONT LATE TONIGHT...SLIDING ACROSS
THE WESTERN AND CENTRAL MOUNTAINS AND NRN SC UPSTATE DURING AROUND
SUNRISE. I WILL INCREASE POPS TO CHC TO LIKELY ACROSS THE NC MTNS
AND ADJACENT FOOTHILLS BY 12Z SAT.
ON SATURDAY...THE CENTER OF THE LOW PRESSURE IS FORECAST TO TRACK
ACROSS THE MID MISSISSIPPI RIVER VALLEY BY 0Z SUN. AS THE LOW TRACKS
NE...THE ASSOCIATED WARM FRONT WILL LIFT NORTH...PIVOTING ACROSS THE
WESTERN NC MTNS DURING THE DAY. I WILL FAVOR THE MTNS AND FOOTHILLS
FOR CATE AND LIKELY POPS. COVERAGE SHOULD PUSH EAST DURING THE MID
AND LATE AFTERNOON ACROSS THE I-77 CORRIDOR. QPF RANGES FROM NEAR
THREE-QUARTERS OF AN INCH ACROSS THE WESTERN NC MTNS TO LESS THAN A
TENTH OF AN INCH EAST OF I-77. BASED ON THE TIMING OF THE PRECIP...I
WILL KEEP HIGH TEMPS LIMITED ACROSS THE MTNS TO THE 50S...POSSIBLY
REACHING THE U60S ACROSS THE EASTERN PIEDMONT.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 230 PM FRI...THE UPSTREAM H5 LOW CENTER WILL SLOWLY OPEN UP
AND LIFT NE ACROSS IL/IN SAT NIGHT THROUGH SUNDAY. MODEL TIME
HEIGHTS AHEAD OF THIS FEATURE SHOW DEEP MOISTURE ARRIVING OVER THE
AREA...WITH UPPER DIVERGENCE DEVELOPING S OF A JETLET THROUGH THE
MID ATLANTIC AREA...AS WELL AS IMPROVING SRLY UPSLOPE FLOW INTO THE
MTNS AND UPGLIDE OVER AN IN SITU SFC CAD LAYER. THE CAD WILL ONLY
GRADUALLY SHALLOW OUT THROUGH SUNDAY GIVEN THE DEEP LAYER SRLY FLOW.
ANY INSTABILITY SUNDAY AFTN SHOULD BE CONFINED TO MAINLY THE SRN
PIEDMONT. THE BEST LOW LEVEL UPGLIDE WILL BE CENTERED OVER THE
FORECAST AREA MIDDAY SUNDAY...WITH A SECONDARY SURGE OF
MOISTURE/FORCING SUNDAY NIGHT AS A COLD FRONT APPROACHES FROM THE W.
QPF WILL BE THE MAIN FORECAST ISSUE DURING THIS PERIOD...WITH THE
SRLY UPSLOPE FLOW LIKELY PRODUCING A LOCAL MAXIMA ALONG S/SE UPSLOPE
PRONE AREAS OF THE SRN APPALACHIANS. THE GFS QPF IS A HIGH END
OUTLIER WITH STORM TOTALS OF 4 TO 5 INCHES IN THE SRN NC MTNS...DUE
MAINLY TO A WAVE RIDING UP THE SRN APPALACHIANS SUNDAY NIGHT. THE
OTHER MODELS/ENSEMBLES FEATURE A CONSENSUS MORE IN THE 3.0 TO 3.5
RANGE IN SRLY UPSLOPE AREAS...IN GOOD AGREEMENT WITH WPC.
PRECIPITABLE WATER ANOMALIES ARE FORECAST TO BE 1 TO 2 STANDARD
DEVIATIONS ABOVE NORMAL...AND ANTECEDENT CONDITIONS ARE FAIRLY DRY.
ALL THINGS CONSIDERED...WILL FEATURE AN HWO MENTION OF ISOLATED
HYDRO PROBLEMS LATE THIS WEEKEND.
DEEPER MOISTURE WILL GRADUALLY DIMINISH FROM THE WEST ON MONDAY AS
THE UPPER SUPPORT LIFTS AWAY NORTH OF THE AREA...BUT THERE WILL BE
PLENTY OF LINGERING SFC TO 850 MB MOISTURE AS THE FRONT WASHES OUT
AND THE LOW LEVEL FLOW VEERS MORE SOUTHWESTERLY. TEMPS WILL REMAIN
COOL OVER THE NW NC PIEDMONT MONDAY...BUT WITH GREATER INSTABILITY
DEVELOPING BACK TO THE SW. WILL FEATURE SHOTGUN CHANCE POPS ON
MAINLY A DIURNAL SCHEDULE FOR SHOWERS AND THUNDERSTORMS
MONDAY...WANING TO SCHC MONDAY NIGHT.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 110 PM FRIDAY...WILL CONTINUE TO GIVE PROPS TO THE 26/00 UTC OP
ECMWF WHICH LINGERS UPPER LEVEL WEAKNESS ATOP THE CWFA THROUGH
TUESDAY. BASED ON THIS...INHERITED SHOTGUN CHANCE POP WILL REMAIN
WITH MAX TEMPS CLOSE TO THE LATE APRIL CLIMO. THE LATEST MEDIUM
RANGE MODEL MASS FIELDS AND ASSOCIATED RESPONSE ARE NOT TOO TERRIBLY
DIFFERENT FOR WEDNESDAY...PROGGING AN INCREASE IN ATLANTIC FETCH
AROUND NEW ENGLAND HIPRES...LEADING TO ONGOING DECENT PCPN CHANCES.
AN INCREASINGLY TRICKY FCST LOOKS TO BE SHAPING UP FOR LATE WEEK AS
DIGGING MID-CONUS L/WV TROUGH SHOULD NUDGE POTENTIALLY WAVY
BAROCLINIC ZONE INTO THE SOUTHERN APPALACHIANS WHILE SOUTHERN STREAM
ENERGY IS PROGGED TO SPIN UP GULF LOW PRESSURE. ON THE 26/00 UTC
ECMWF...THE CWFA IS POSITIONED BETWEEN THE MAIN RESPONSE AREAS OF
THESE TWO FEATURES...WHILE THE NEW 26/12 UTC OP GFS HAS US WELL
WITHIN THE DEEP FORCING AND MOISTURE. AT THIS POINT...THE BEST
COURSE OF ACTION IS TO STICK CLOSE TO THE WPC FCST OF A SOLID
MID CHANCE POP AND SLIGHTLY BELOW NORMAL MAX TEMPERATURES. GIVEN
THE MODEL DIFFERENCES WITH RESPECT TO JUST HOW THE DYNAMIC PATTERN
WILL EVOLVE BY NEXT FRIDAY...FCST CONFIDENCE IS BELOW NORMAL AND
PLAN ON SIMPLY GOING WITH THE WPC FCST OF SOLID MID-CHANCE POP
AND COOLER THAN PERSISTENCE.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...DECENT CONFIDENCE IS HAD IN A VFR FCST THROUGH THE PERIOD.
THE NAMM BUFKIT SOUNDING SHOWS A LOWERING OF CIGS BUT ONLY TO LOW
VFR BY LATE IN THE PERIOD AND ALL MOS KEEPS THINGS LOW VFR AT WORSE
THROUGH 00Z. THIS MAKES SENS WITH THE WEDGE OF DRY AIR TO OVERCOME
BEFORE THE WEDGE BREAKS DOWN. THERE SHOULD BE SOME VICINITY -SHRA
LATE AND HAVE INTRODUCED A PROB30 AFT 20Z.
ELSEWHERE...EXPECT RESTRICTIONS AT KAVL AS THE PRECIP MOVES INTO THE
TERMINAL AREA AROUND DAYBREAK. MVFR AND AND POSSIBLY IFR CIGS SHOULD
PERSIST THROUGH THE PERIOD WITH SOME MVRF VSBY IN -SHRA. THE OTHER
TAF SITES WILL LIKELY SEE A LOWERING OF CIGS TO LOW VFR THROUGH THE
MORNING HRS AND THEN A DROP INTO MVFR THROUGH THE AFTERNOON AS A
WIDESPREAD ISENT PRECIP SHIELD BECOMES ESTABLISHED.
OUTLOOK...A WEDGE OF COLD AIR WILL PERSIST ACROSS THE REGION SUNDAY
AND MONDAY. PERIODIC PRECIPITATION INTO THIS WEDGE WILL CREATE THE
POSSIBILITY OF FLIGHT RESTRICTIONS.
CONFIDENCE TABLE...
00-06Z 06-12Z 12-18Z 18-24Z
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAVL HIGH 100% HIGH 100% MED 71% HIGH 83%
KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 81%
KAND HIGH 100% HIGH 100% HIGH 100% HIGH 91%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...CSH
NEAR TERM...NED/SBK
SHORT TERM...HG
LONG TERM...CSH
AVIATION...SBK
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1033 PM CDT FRI APR 26 2013
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 259 PM CDT FRI APR 26 2013
VERY LITTLE OF SIGNIFICANCE TONIGHT AND SATURDAY ACROSS THE AREA AS
SYSTEMS DIVERT AROUND THE REGION. FRONTAL BOUNDARY HAS COMPLETELY
CLEARED THE FAR SOUTHEAST CWA AT MID AFTERNOON...WITH VERY MIXY
LOWER ATMOSPHERE DRIVING A DECENT NORTHWEST TO NORTHEAST WIND ACROSS
THE AREA. WINDS WILL DECOUPLE FAIRLY QUICKLY AS SUNSET...WITH WEAK
SURFACE RIDGE CENTERED OVER THE AREA OVERNIGHT. VERY DRY AIRMASS
OVER THE WESTERN HALF...SO EXPECT THAT WILL BE FAIRLY EFFICIENT IN
COOLING THIS EVENING AND IN THE OVERNIGHT WITH THE WEAK FLOW. NOT
EXPECTING ANY SIGNIFICANT FOG POTENTIAL...BUT MAY GET SOME 4-6SM
DEVELOPMENT IN SHALLOW AREAS THROUGH THE MID CWA. FRONTAL BOUNDARY
WILL WASH OUT TO THE SOUTH...WITH SOUTHERLY FLOW GRADUALLY BECOMING
ESTABLISHED...STRONGEST ACROSS THE WEST. MODELS HAVE REPEATEDLY BEEN
ABOUT 2C TOO COOL ON 925 HPA TEMPS FOR THE NEXT DAY...AND RAP HAS
PROVIDED A MUCH BETTER FORECAST ONCE IT HAS FALLEN INTO THE RANGE.
THEREFORE...ACTUALLY RAISED TEMPERATURES SOMEWHAT HIGHER THAN
GUIDANCE...BUT ONLY A COUPLE DEGREES AS WILL BE A MORE STABLE WARM
ADVECTIVE PROFILE INSTEAD OF THE WEAK COLD ADVECTION TODAY.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 259 PM CDT FRI APR 26 2013
SATURDAY NIGHT WILL SEE A DECENT SOUTHERLY GRADIENT THROUGH THE
NIGHT WHICH WILL KEEP MILD TEMPERATURES IN PLACE. THIS WILL KEEP
LOWS ABOVE NORMAL AND MAINLY IN THE UPPER 40S TO AROUND 50. COULD
ACTUALLY SEE THEM A LITTLE WARMER OF THE GRADIENT REMAINS STRONG
ENOUGH.
A COLD FRONT WILL SWING INTO THE AREA ON SUNDAY WHICH MAY SPARK A
FEW SHOWERS AND THUNDERSTORMS OVER THE EASTERN CWA DURING THE DAY
AND INTO THE EVENING. UPPER LEVEL SUPPORT WILL ALSO BRING A CHANCE
FOR SHOWERS INTO THE WESTERN AND SOUTHERN CWA DURING THE NIGHT.
AHEAD OF THIS FRONT TEMPERATURES WILL CLIMB WELL ABOVE NORMAL AND
MUCH OF THE AREA WILL CLIMB INTO THE UPPER 70S TO LOWER 80S.
SUNDAY NIGHT INTO MONDAY WILL BE A MILD PERIOD WITH THE FRONT
SETTLING IN AND COOLER TEMPERATURES. THE BETTER CHANCE FOR SHOWERS
WILL BE IN THE SOUTHERN CWA. INSTABILITY MARGINAL SO ONLY A MINOR
THREAT FOR THUNDERSTORMS...THE BETTER CHANCE WILL BE SUNDAY
AFTERNOON OVER THE EASTERN CWA. WHILE MONDAY WILL BE COOLER STILL
ANTICIPATING UPPER 60S TO LOWER 70S.
SOME UNFORTUNATE BIG CHANGES COMING IN THE EXTENDED AS A LARGE
TROUGH OF LOW PRESSURE GRADUALLY DIGS ACROSS THE NORTHERN AND
CENTRAL PLAINS. THIS WILL BRING AN END TO THE WARM STRETCH WITH
BELOW NORMAL TEMPERATURES AGAIN BLANKETING THE REGION FOR THE
REMAINDER OF THE WEEK. THE GFS COMES IN QUITE A BIT DEEPER WITH THE
CUT OFF LOW THAT DEVELOPS...DROPPING IT SOUTH INTO KENTUCKY BY THE
WEEKEND WHILE THE ECMWF CUTS THIS LOW OFF IN NORTHERN
WISCONSIN...ALTHOUGH THE NEW 12Z ECMWF NOW CUTS THIS LOW OFF IN
NEBRASKA. SO...THE MAIN STORY HERE IS A VERY UNPREDICTABLE CUT OFF
LOW BUT COLDER TEMPERATURES. THERE DOES APPEAR TO BE SOME DECENT
UPPER LEVEL SUPPORT THAT DROPS SOUTH MID WEEK AND WILL HAVE SOME
POPS IN TO COVER THIS OTHERWISE AT THIS TIME NOT LOOKING LIKE ANY
MAJOR SYSTEMS. CONFIDENCE AFTER WEDNESDAY LOW.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1032 PM CDT FRI APR 26 2013
VFR THROUGH 06Z SUNDAY.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...CHAPMAN
LONG TERM...08
AVIATION...
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
918 PM EDT FRI APR 26 2013
.SYNOPSIS...
HIGH PRESSURE ACROSS THE REGION TONIGHT WILL DRIFT OFF THE MID-
ATLANTIC COAST BY SATURDAY AS AN UPPER DISTURBANCE MOVES EAST FROM
THE MID-MISSISSIPPI VALLEY REGION INTO THE SOUTHERN APPALACHIANS.
THIS SYSTEM WILL SLOW AND LINGER ACROSS THE REGION THROUGH THE
MID-PART OF NEXT WEEK...KEEPING CLOUDS...LIGHT RAIN...AND
UNSEASONABLY COOL TEMPERATURES IN PLACE. A NEW WEATHER SYSTEM WILL
APPROACH FROM THE WEST BY THE END OF NEXT WEEK WITH MORE SHOWERS
AND POSSIBLY A FEW THUNDERSTORMS.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
AS OF 840 PM EDT FRIDAY...
SOUNDINGS SHOW VERY DRY AIR CONTINUING ESPCLY IN THE LOWER LEVELS
THIS EVENING WITH MOST ADVECTION OF MOISTURE COMING FROM THE WEST
ATTM. THIS DRY AIR HAS BASICALLY DRIED UP THE INITIAL BATCH OF
PRECIP HEADING IN FROM THE WEST WITH THE FIRST FAINT WAVE...WHILE
HAVE ANOTHER WEAK ARC OF ENERGY SET TO ARRIVE FROM TN/KY OVER THE
FAR WEST LATE. LATEST RAP PICKS UP ON THIS AFTER MIDNIGHT AND HAS
SOME SPOTTY -RA OVER THE NW NC RIDGES...AND AREAS WEST OF I-77 IN
VA LATE. MOST OTHER SHORT TERM GUIDANCE QUITE DRY SO ONLY
INCLUDING A SLIGHT POP FOR VERY -RA EXTREME SW BY DAWN. OTRW WILL
SEE VARYING AMOUNTS OF HIGH/MID CLOUDS...WITH A THICKER MID DECK
CANOPY DEVELOPING OVERNIGHT WEST...AND SOME THIN SPOTS OVER THE
NORTH/EAST. BUMPED UP LOW TEMPS A BIT SW DUE TO THICKER CLOUDS
WITH MOST SPOTS IN THE 40S BY MORNING...EXCEPT SOME 30S DEEPER
VALLEYS ACROSS THE NORTH.
HIGH PRESSURE WILL MOVE EAST OFF THE NEW ENGLAND COAST ON SATURDAY.
AN APPROACHING SHORTWAVE COMBINED WITH EASTERLY FLOW WILL INCREASE
MOISTURE ACROSS OUR REGION SATURDAY. PLACED THE HIGHEST POPS ON
SATURDAY ALONG THE SOUTHERN BLUE RIDGE MOUNTAINS...WITH LIGHTER
CHANCES IN THE EAST. HIGH SATURDAY VARY FROM THE LOW 50S ACROSS THE
SOUTHWEST MOUNTAINS TO AROUND 70 IN THE PIEDMONT. A FASTER SPREAD OF
MOISTURE COULD TRIM HIGHS SATURDAY MORE WITH ADDITIONAL CLOUD COVER
AND RAIN.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 345 PM EDT FRIDAY...
ECMWF/GFS IN GENERAL AGREEMENT ON THE EVOLUTION OF THE PATTERN
SUN THROUGH MON...BUT CONTINUE TO DIFFER ON TIMING. HOWEVER...MOST
OF THE TIMING ISSUES APPEAR TO BE RESOLVED BY THE BEGINNING OF THE
SHORT TERM PERIOD. THIS PERIOD CAN BEST BE CHARACTERIZED AS A
RATHER CONTINUOUS PERIOD OF LIGHT RAIN AS A SOUTHERN STREAM
DISTURBANCE SPREADS THROUGH THE REGION IN A FAVORABLE WEDGE AREA.
THE WEDGE WILL BE ENHANCED/REINFORCED AS THE PCPN FALLS INTO AN
INITIALLY DRY/COOL SFC AIR MASS. QPF THROUGH THE PERIOD SHOULD
RANGE FROM 0.25 INCH IN THE NE PART OF THE CWA TO PERHAPS NEAR AN
INCH IN THE NW NC MOUNTAINS AND FAR SW VA. BY SUN AFTERNOON...THE
WEDGE MAY ERODE ENOUGH ALONG THE WESTERN EDGE...FROM MERCER COUNTY
WV DOWN TOWARD NE TN TO SUPPORT ISOLD TSRA WITH DIURNAL HEATING.
THUS...HAVE REINTRODUCED THE MENTION OF TSRA ALONG OUR WESTERN
BORDER. EASTERN AREAS SHOULD REMAIN TOO STABLE/COOL TO SUPPORT
TSRA THROUGH THE SHORT TERM. HAVE NOT INCLUDED ANY MENTION OF DZ
THIS PERIOD AS WITH -RA LIKELY...IT JUST ADDS CONFUSION TO THE
PUBLIC FORECAST. TEMPERATURES WILL BE UNSEASONABLY COOL THROUGH
THE PERIOD WITH HIGHS IN THE 50S SUN ACROSS MUCH OF THE
REGION...EXCEPT THE PERIPHERY OF THE CWA WHERE IT WILL BE IN THE
60S. HAVE LEANED HEAVILY TOWARD THE MUCH COOLER ECMWF MOS THROUGH
THE PERIOD.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
CONSIDERABLE QUESTIONS REMAIN WITH RESPECT TO THE EVOLUTION OF
WEATHER FEATURES WITH THE EXTENDED PERIODS...ESPECIALLY THE LATER
PERIODS. THE BIG QUESTION...AS HAS BEEN THE CASE FOR DAYS NOW...IS
THE DEVELOPMENT/MOVEMENT/POSITION OF A POTENTIAL CLOSED UPPER LOW.
ECMWF/GFS CONTINUE TO COVER THE ENTIRE SPECTRUM WITH RESPECT TO
THE DETAILS. THUS...THERE IS LITTLE TO NO RELIABILITY OR
CONFIDENCE IN THE EXTENDED FORECAST...ESPECIALLY THE LATER
PERIODS. AT THE BEGINNING OF THE EXTENDED PERIODS...TUE-
WED...STILL DEALING WITH A LINGERING WEDGE ACROSS THE EASTERN
SECTIONS. GIVEN THE PERSISTENT PATTERN THIS PAST WINTER AND SPRING
SO FAR...HAVE LEANED HEAVILY TOWARD THE ECMWF WHICH IS MUCH SLOWER
TO ERODE THE WEDGE. BETTER PCPN CHANCES WITH BOTH THE GFS/ECMWF
SHIFT SOUTH AND EAST OF THE CWA EARLY...WITH PCPN TRENDING TOWARD
A MORE DIURNAL PATTERN FOCUSING ALONG THE MOUNTAINS IN AREAS OF
BETTER DIFFERENTIAL HEATING. TEMPERATURES SHOULD SLOWLY WARM
TOWARD MORE SEASONAL LEVELS...BUT LIKELY WILL REMAIN JUST BELOW
NORMAL THROUGH THE NEW RIVER VALLEY...SHENANDOAH VALLEY...AND
GREENBRIER VALLEY. DURING THE FINAL DAYS OF THE EXTENDED...NAMELY
THU-FRI...HAVE GONE NEARLY ENTIRELY WITH THE 00Z/12Z ECMWF
SOLUTION AND COMPLETELY IGNORED THE GFS SOLUTION OF A VERY DEEP
CLOSED LOW THROUGH THE SOUTHERN ABLUTIONS WITH ATTENDANT HEAVY
RAIN FOLLOWED BY SNOW AND RIDICULOUSLY COLD TEMPERATURES FOR
EARLY MAY. THE ECMWF OFFERS A MUCH MORE PLAUSIBLE FORECAST FROM
ALL ASPECTS...QPF...POPS...AND TEMPS. A COLD FRONT ON THE FORWARD
FLANK OF ANY LOW PRESSURE AREA ACROSS THE UPPER MID-WEST/OH VALLEY
MAY BEGIN TO APPROACH THE AREA BY SAT WITH INCREASING CHANCES OF
SHRA/TSRA AT THAT TIME.
&&
.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
AS OF 620 PM EDT FRIDAY...
HIGH AND MID DECK CANOPY ACROSS THE REGION WILL PERSIST OVERNIGHT
AHEAD OF A WEAK DISTURBANCE APPROACHING FROM THE WEST. LOW LEVELS
REMAIN TOO DRY FOR ANY RAINFALL TONIGHT SO KEEPING IT VFR WITH
CIGS MAINLY ABOVE 8K FEET. MOISTURE SHOULD CONTINUE TO DEEPEN
SATURDAY AS THE COMBO OF A WEAK IMPULSE...RETURN SOUTH/SE FLOW AND
A WARM FRONT TO THE SW AFFECT THE REGION. HOWEVER STILL APPEARS
ENOUGH SATURATION FOR PRECIP WONT OCCUR UNTIL SATURDAY AFTERNOON
AND MAINLY OVER THE WESTERN LOCATIONS. BEST CHANCE AT SEEING SOME
-RA APPEARS AT KBLF SO INCLUDING MENTION THERE WHILE MAINTAINING
VFR THROUGH THE DAY. WILL LEAVE OUT ELSW FOR NOW GIVEN TIMING
NEAR THE END OF THE VALID TAF PERIOD ESPCLY AROUND KBCB AND KLWB.
OTRW VFR WITH CIGS GRADUALLY LOWERING WITH THE DEVELOPMENT OF A
3-5K FT STRATO-CU LAYER DURING THE AFTERNOON. EXPECT WINDS TO
REMAIN LIGHT BUT EXPECT THEM TO PICK UP FROM THE SOUTH/SE AT 5-15
KTS LATER SATURDAY.
RAINFALL SHOULD BECOME MORE WIDESPREAD SAT NIGHT AS LOW PRESSURE
TRACKS TO THE WEST AND A WARM FRONT LIFTS NORTH INTO THE AREA.
THIS SHOULD RESULT IN MVFR/IFR CIGS AND MVFR VSBYS ESPCLY
MOUNTAINS DUE TO LIGHT RAINFALL.
EXTENDED AVIATION... LOOKS LIKE AN EXTENDED PERIOD OF SUB PAR FLYING
WEATHER IS ON TAP FOR THE NEXT SEVERAL DAYS. CLOSED UPPER LOW OVER
THE MIDWEST WILL GRADUALLY OPEN UP AS IT SLOWLY MOVES EAST. THIS
WILL ALLOW LOW PRESSURE TO MOVE OUT OF THE PLAINS AND INTO THE OHIO
VALLEY...WEAKENING AS IT GOES. NET RESULT WILL BE MOIST SOUTHERLY
FLOW AND PERIODS OF PCPN SETTING UP OVER THE AREA SUNDAY AND
MONDAY. HIGH PRESSURE WILL THEN WEDGE DOWN THE ERN SEABOARD FOR
THE MIDDLE OF THE WEEK AS A STRONG COLD FRONT APPROACHES ON
WEDNESDAY. NET RESULT WILL BE PREDOMINANT MVFR WITH PERIODS OF
IFR FOR THE BULK OF NEXT WEEK.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...RAB
NEAR TERM...JH/KK
SHORT TERM...RAB
LONG TERM...RAB
AVIATION...JH/MBS
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1053 PM CDT FRI APR 26 2013
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND SATURDAY
ISSUED AT 210 PM CDT FRI APR 26 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW THE WARM
ADVECTION PRECIP FROM EARLIER TODAY RACING OFF INTO SOUTHEAST ONTARIO
WHILE A WEAK FRONT IS NOW SLIDING INTO NORTHERN IOWA AND WESTERN
WISCONSIN. THE FRONT IS RELATIVELY INACTIVE EARLY THIS AFTERNOON
EXCEPT FOR A DEVELOPING CU FIELD OVER NORTHEAST IOWA. MEANWHILE...A
TRAILING LINE OF MID-CLOUDS IS LINGERING ACROSS NE WISCONSIN ALONG
THE TAIL END OF A SHORTWAVE MOVING ACROSS ONTARIO...WHICH IS KEEPING
SKIES PARTLY TO MOSTLY CLOUDY IN SPOTS. TEMPERATURES HAVE WARMED
INTO THE MID 50S NORTH TO MID 60S SOUTH AS WARMER AIR INVADES THE
REGION. AS THE FRONT SAGS INTO CENTRAL AND NE WISCONSIN LATER
TODAY...PRECIP CHANCES ARE THE MAIN FORECAST CONCERN.
TONIGHT...A WEAK FRONT WILL SAG ACROSS THE STATE FROM LA CROSSE TO
MARINETTE WHERE IT WILL STALL FOR MOST OF THE NIGHT. RATHER BAGGY
LOW LEVEL THETAE AXIS WILL RESIDE ABOVE THE FRONTAL BOUNDARY...BUT
PROGGED SOUNDINGS DO NOT SHOW MUCH SATURATION AND DEWPOINTS MIXED
OUT TOO MUCH TODAY FOR INSTABILITY TO DEVELOP. IN ADDITION...DO NOT THINK
WEAK FORCING ALONG THE FRONT WILL BE ENOUGH TO OVERCOME LOSS OF
HEATING AND INCREASING SUBSIDENCE ALOFT. MANY OF THE HI
RES MODELS SHOW PRECIP EXPANDING OVER NORTHEAST WISCONSIN THIS
EVENING...BUT THINK THIS WILL BE TOUGH DUE TO THE REASONS MENTIONED
ABOVE. NORTH OF THE FRONT...WINDS WILL TURN CALM...WHICH COMBINED
WITH SNOW MELT AND CLEAR SKIES...WILL PROMOTE FOG FORMATION LATE
TONIGHT. HAVE EXPANDED AREAS OF FOG INTO CENTRAL WISCONSIN. LOWS
FALLING INTO THE MID 30S NORTH OF THE FRONT...AND INTO THE MID OR
UPPER 40S SOUTH OF THE FRONT.
SATURDAY...THE FRONT WILL STILL BE AROUND AT THE START OF THE
MORNING BUT WILL EVENTUALLY WASH OUT BY MIDDAY OR SO. MOISTURE WILL
LINGER HOWEVER...AND SHOULD LEAD TO A DIURNAL CU FIELD. SOME MODELS
SPIT OUT LIGHT QPF TOMORROW AFTERNOON...BUT THAT IS LIKELY DUE TO
DEWPOINTS REACHING INTO THE UPPER 40S. JUDGING BY CONDITIONS
UPSTREAM...UPPER 30S TO LOW 40S DEWPOINTS ARE MORE
REASONABLE...WHICH WILL NOT BE ENOUGH TO GENERATE MUCH CAPE. SO
THINK MODELS ARE TOO PESSIMISTIC ONCE AGAIN AND WILL GO WITH A DRY
FORECAST. 925MB TEMPS ARGUE FOR HIGHS NEAR 70...AND WILL BUMP UP
TEMPS INTO THE UPPER 60S EXCEPT NEAR LAKE MICHIGAN.
.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
ISSUED AT 210 PM CDT FRI APR 26 2013
THE MAIN FCST CONCERNS INCLUDE PCPN TRENDS STARTING SUNDAY NIGHT...
THEN ABOVE NORMAL TEMPS TRENDING TOWARD BELOW NORMAL CONDITIONS
AGAIN BY THE LATTER HALF OF THE NEXT WORK WEEK.
DRY AND MILD CONDITIONS ARE EXPECTED AHEAD OF THE NEXT APPROACHING
COLD FRONT ON SATURDAY NIGHT AND SUNDAY. PARTLY CLOUDY SKIES AND
MIXING THROUGH 850-800 MB SHOULD YIELD MAX TEMPS IN THE UPPER 60S
AND LOWER 70S...EXCEPT NEAR LK MICH...WHERE READINGS WILL BE IN THE
50S AND LOWER 60S.
A COLD FRONT WILL PUSH INTO THE FORECAST AREA SUNDAY NIGHT AND
MONDAY...THEN LIFT BACK TO THE NORTH AS A WARM FRONT AS SOUTH
FLOW INCREASES ON MONDAY NIGHT. SCT SHRA/ISOLD TSRA ARE ANTICIPATED
THROUGH THIS PERIOD.
THE WARMEST DAY OF THE WEEK IS EXPECTED ON TUESDAY...WITH HIGHS
IN THE 70 TO 75 RANGE OVER MOST INLAND AREAS. A COLD FRONT WILL
MOVE INTO THE WSTRN PART OF THE FA LATE TUESDAY...THEN THROUGH
THE REST OF THE CWA TUESDAY NIGHT. THIS FRONT SHOULD PROVIDE OUR
BEST BET FOR ORGANIZED THUNDERSTORM ACTIVITY DURING THE NEXT WEEK.
SIGNIFICANT DIFFERENCES DEVELOP BY WEDNESDAY AND WEDNESDAY NIGHT...
AS THE GFS TAKES MOST OF THE PCPN EAST OF THE REGION WHILE THE ECMWF
DEVELOPS A BAND OF SIGNIFICANT POST-FRONTAL PCPN IN ASSOCIATION WITH
A STG RRQ OF AN UPPER JET AND INCOMING UPPER TROF. WILL JUST CARRY
MID-RANGE POPS FOR NOW...AND SEE HOW THIS EVOLVES.
MUCH COLDER AIR WILL PUSH INTO THE AREA WEDNESDAY NIGHT...AND LINGER
INTO FRIDAY. IN ADDITION...THE DEEP UPPER TROF IS EXPECTED TO DEVELOP
INTO A CUT-OFF LOW OVER THE GREAT LAKES BY THE END OF THE WORK WEEK.
DESPITE THE CALENDAR READING EARLY MAY...CAN`T IGNORE THE POSSIBILITY
OF SOME LIGHT SNOW SHOWERS...ESPECIALLY OVER NC WI LATE WEDS NGT/
EARLY THU...AND OVER MOST OF THE FA LATE THU NGT INTO EARLY FRIDAY.
TEMPERATURES WILL RETURN TO MUCH BELOW NORMAL LEVELS.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1046 PM CDT FRI APR 26 2013
A WEAK FRONT NOW INTO CENTRAL AND NORTHEAST WI. ISOLD TO SCT HIGH
BASED SHOWERS HAVE DEVELOPED AROUND 8PM ALONG FRONT...AND ARE NOW
STARTING TO WANE. EXPECT TO BE DONE BY START OF THIS FORECAST PERIOD. GIVEN
THE FRONT...LIGHT WINDS AND AVAILABLE LOW LEVEL MOISTURE...FOG
EXPECTED...ESPECIALLY OVER NORTH CENTRAL TAF SITES. UNCERTAINTY
THOUGH ON DENSE FOG CONTINUES...GIVEN TEMP/DEW POINTS SPREADS
ATTM. THE FOG WILL BURN OFF BY MID- MORNING TOMORROW WHICH WILL
LEAD TO BUILDING CUMULUS CLOUDS BY MIDDAY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......KIECKBUSCH
AVIATION.......TE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1017 PM CDT FRI APR 26 2013
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 345 PM CDT FRI APR 26 2013
AT 3 PM...A WEAK COLD FRONT WAS LOCATED JUST NORTH OF THE FORECAST
AREA FROM DULUTH SOUTHEAST THROUGH THE TWIN CITIES TO SIOUX CITY
IOWA. OTHER THAN A FEW CLOUDS AND A WIND SHIFT THERE WAS NO
SENSIBLE WEATHER ASSOCIATED WITH THIS FRONT. MEANWHILE FURTHER
SOUTH ACROSS NORTHEAST IOWA...AND SOUTHWEST AND CENTRAL WISCONSIN...
THERE WAS A 850 TO 700 MB THERMAL TROUGH. THE COMBINATION OF ML
CAPES RUNNING AROUND 200 J/KG AND VERY STEEP 900 TO 800 MB LAPSE
RATES HAVE RESULTED IN SOME INSTABILITY CLOUDS DEVELOPING ACROSS
THIS AREA. THE NMM AND SPC WRF GENERATE A LINE OF SHOWERS IN THIS
REGION FROM LATE THIS AFTERNOON INTO TONIGHT. THESE MODELS ARE
ABOUT 10F TOO HIGH ON THEIR SURFACE DEW POINTS. MEANWHILE THE ARW
WHICH HAS A BETTER HANDLE OF THE SURFACE DEW POINTS SHOWS NO
PRECIPITATION AT ALL. WITH THE LATEST RAP SOUNDINGS CONTINUING TO
SHOW A VERY SHALLOW MOISTURE LAYER AROUND 800 MB...TRENDED THE
FORECAST TOWARD THE ARW FOR TONIGHT.
ON SATURDAY...THE 26.12Z AND 26.18Z MODELS ARE IN VERY GOOD
AGREEMENT THAT THE COLD FRONT WILL MOVE NORTH AS A WARM FRONT
INITIALLY DURING THE MORNING...AND THEN QUICKLY WASHES IT OUT BY
THE AFTERNOON. THE NAM/WRF GENERATES 100 TO 200 J/KG OF ML CAPE
DURING THE AFTERNOON ALONG AND NORTH OF THE INTERSTATE 90 CORRIDOR.
MEANWHILE THE GFS SHOWS VERY LITTLE INSTABILITY AT ALL. THE
NAM/WRF LOOKS TOO HIGH ON ITS SURFACE DEW POINTS...SO PREFER THE
MORE STABLE GFS. IN ADDITION...THERE IS NO SURFACE TO 850 MB
MOISTURE TRANSPORT ANYWHERE IN THE FORECAST AREA. DUE TO
THIS...KEPT THE FORECAST DRY.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 345 PM CDT FRI APR 26 2013
ON SUNDAY AFTERNOON...THE 26.12Z GFS SLOWED UP ITS MOVEMENT OF
THE PRECIPITATION INTO SOUTHEAST MINNESOTA...AND IN WEST CENTRAL
AND NORTH CENTRAL WISCONSIN. THIS IS MORE IN AGREEMENT WITH THE
GEM AND ECMWF....THEREFORE...REMOVED THE PRECIPITATION CHANCES FOR
THIS TIME PERIOD.
FROM SUNDAY NIGHT INTO MONDAY...THE MODELS CONTINUE TO STRUGGLE
WITH A COLD FRONT MOVING INTO THE REGION AND THEN MOVING BACK
NORTH AS A WARM FRONT. DUE TO THESE UNCERTAINTIES...JUST WENT WITH
THE CONSALL PRECIPITATION CHANCES. WITH BOTH THE 0-3 KM AND 0-6 KM
SHEAR LESS THAN 30 KNOTS...NOT OVERLY CONCERNED ABOUT ANY SEVERE
WEATHER AT THIS TIME.
FROM TUESDAY INTO TUESDAY NIGHT...THE MODELS CONTINUE TO STRUGGLE
WITH THE SPEED OF A STRONG COLD FRONT MOVING THROUGH THE REGION.
ML CAPES AHEAD OF THIS CLIMB INTO THE 250 TO 750 J/KG RANGE. BOTH
THE 0-3 KM AND 0-6 KM SHEAR IS FAVORABLE FOR SEVERE WEATHER. HOWEVER
THERE IS A WARM LAYER BETWEEN 800 AND 700 MB WHICH MAY CAP OFF ANY
PRECIPITATION PRIOR TO THE FRONTAL PASSAGE.
IN THE WAKE OF THIS FRONT...TEMPERATURES WILL BE MUCH COLDER FROM
WEDNESDAY THROUGH FRIDAY. THE LATEST ECMWF SUGGEST HIGHS ONLY IN
THE 30S AND 40S. THE GFS IS A SLIGHTLY A BIT HIGHER. SINCE THE
MODELS HAVE BEEN SO INCONSISTENT WITH THIS SYSTEM OVER THE PAST
COUPLE OF DAYS...JUST STAYED WITH THE ALL BLEND FOR NOW.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1017 PM CDT FRI APR 26 2013
VFR CONDITIONS WITH LIGHTER WINDS ARE EXPECTED FOR THE NEXT 24
HOURS AS A TROUGH OF LOW PRESSURE STILL JUST WEST OF KRST WEAKENS.
THERE IS A STREAM OF MOISTURE AHEAD OF THIS TROUGH...WHICH WITH
DAYTIME MIXING SHOULD PRODUCE SOME VFR CUMULUS FOR THIS AFTERNOON.
ONE CONCERN REMAINS FROM VARIOUS MODELS IS SOME MVFR OR EVEN IFR
BR DEVELOPMENT BETWEEN 09-13Z THIS MORNING. DEWPOINTS THAT HAVE
CLIMBED UP INTO THE MID 40S WITH LOSS OF DAYTIME HEATING ARE
FAVORABLE. HOWEVER...DO NOT THINK WINDS WILL COMPLETELY GO
CALM...ALLOWING MIXING TO PERSIST AND KEEP THE TEMPERATURE FROM
REACHING THE DEWPOINT. THUS...HAVE CONTINUED TO KEEP THE BR
MENTION OUT OF THE TAFS.
&&
.HYDROLOGY...
ISSUED AT 345 PM CDT FRI APR 26 2013
TRIBUTARY STREAMS CONTINUE TO FALL FOR THE MOST PART. HIGH WATER
CONTINUES ALONG THE BLACK AND TREMPEALEAU RIVERS...WITH THE BLACK
STILL SEEING SOME IMPACTS FROM MELTING SNOW UP IN THE HEADWATER
AREAS OF CLARK/TAYLOR COUNTIES. EXPECT TO SEE SOME ADDITIONAL
RISES ALONG THE BLACK IN THE COMING DAYS DUE TO THE WARMING
TEMPERATURES.
FOR THE MISSISSIPPI RIVER...IT LOOKS TO CONTINUE RISING SLOWLY ALL
THE WAY INTO THE SECOND WEEK OF MAY. HOW HIGH IT GETS WILL DEPEND
GREATLY ON HOW MUCH RUNOFF MOVES DOWNSTREAM FROM THE SNOW COVERED
AREAS OF CENTRAL/NORTHERN MN...AND NORTHWEST WI. THE LATEST
FORECASTS ATTEMPT TO TAKE THIS SNOWMELT RUNOFF INTO ACCOUNT...BUT
MODIFICATIONS TO THE FORECAST ARE LIKELY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...AJ
HYDROLOGY...WELVAERT
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
655 PM CDT FRI APR 26 2013
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND SATURDAY
ISSUED AT 210 PM CDT FRI APR 26 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW THE WARM
ADVECTION PRECIP FROM EARLIER TODAY RACING OFF INTO SOUTHEAST ONTARIO
WHILE A WEAK FRONT IS NOW SLIDING INTO NORTHERN IOWA AND WESTERN
WISCONSIN. THE FRONT IS RELATIVELY INACTIVE EARLY THIS AFTERNOON
EXCEPT FOR A DEVELOPING CU FIELD OVER NORTHEAST IOWA. MEANWHILE...A
TRAILING LINE OF MID-CLOUDS IS LINGERING ACROSS NE WISCONSIN ALONG
THE TAIL END OF A SHORTWAVE MOVING ACROSS ONTARIO...WHICH IS KEEPING
SKIES PARTLY TO MOSTLY CLOUDY IN SPOTS. TEMPERATURES HAVE WARMED
INTO THE MID 50S NORTH TO MID 60S SOUTH AS WARMER AIR INVADES THE
REGION. AS THE FRONT SAGS INTO CENTRAL AND NE WISCONSIN LATER
TODAY...PRECIP CHANCES ARE THE MAIN FORECAST CONCERN.
TONIGHT...A WEAK FRONT WILL SAG ACROSS THE STATE FROM LA CROSSE TO
MARINETTE WHERE IT WILL STALL FOR MOST OF THE NIGHT. RATHER BAGGY
LOW LEVEL THETAE AXIS WILL RESIDE ABOVE THE FRONTAL BOUNDARY...BUT
PROGGED SOUNDINGS DO NOT SHOW MUCH SATURATION AND DEWPOINTS MIXED
OUT TOO MUCH TODAY FOR INSTABILITY TO DEVELOP. IN ADDITION...DO NOT THINK
WEAK FORCING ALONG THE FRONT WILL BE ENOUGH TO OVERCOME LOSS OF
HEATING AND INCREASING SUBSIDENCE ALOFT. MANY OF THE HI
RES MODELS SHOW PRECIP EXPANDING OVER NORTHEAST WISCONSIN THIS
EVENING...BUT THINK THIS WILL BE TOUGH DUE TO THE REASONS MENTIONED
ABOVE. NORTH OF THE FRONT...WINDS WILL TURN CALM...WHICH COMBINED
WITH SNOW MELT AND CLEAR SKIES...WILL PROMOTE FOG FORMATION LATE
TONIGHT. HAVE EXPANDED AREAS OF FOG INTO CENTRAL WISCONSIN. LOWS
FALLING INTO THE MID 30S NORTH OF THE FRONT...AND INTO THE MID OR
UPPER 40S SOUTH OF THE FRONT.
SATURDAY...THE FRONT WILL STILL BE AROUND AT THE START OF THE
MORNING BUT WILL EVENTUALLY WASH OUT BY MIDDAY OR SO. MOISTURE WILL
LINGER HOWEVER...AND SHOULD LEAD TO A DIURNAL CU FIELD. SOME MODELS
SPIT OUT LIGHT QPF TOMORROW AFTERNOON...BUT THAT IS LIKELY DUE TO
DEWPOINTS REACHING INTO THE UPPER 40S. JUDGING BY CONDITIONS
UPSTREAM...UPPER 30S TO LOW 40S DEWPOINTS ARE MORE
REASONABLE...WHICH WILL NOT BE ENOUGH TO GENERATE MUCH CAPE. SO
THINK MODELS ARE TOO PESSIMISTIC ONCE AGAIN AND WILL GO WITH A DRY
FORECAST. 925MB TEMPS ARGUE FOR HIGHS NEAR 70...AND WILL BUMP UP
TEMPS INTO THE UPPER 60S EXCEPT NEAR LAKE MICHIGAN.
.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
ISSUED AT 210 PM CDT FRI APR 26 2013
THE MAIN FCST CONCERNS INCLUDE PCPN TRENDS STARTING SUNDAY NIGHT...
THEN ABOVE NORMAL TEMPS TRENDING TOWARD BELOW NORMAL CONDITIONS
AGAIN BY THE LATTER HALF OF THE NEXT WORK WEEK.
DRY AND MILD CONDITIONS ARE EXPECTED AHEAD OF THE NEXT APPROACHING
COLD FRONT ON SATURDAY NIGHT AND SUNDAY. PARTLY CLOUDY SKIES AND
MIXING THROUGH 850-800 MB SHOULD YIELD MAX TEMPS IN THE UPPER 60S
AND LOWER 70S...EXCEPT NEAR LK MICH...WHERE READINGS WILL BE IN THE
50S AND LOWER 60S.
A COLD FRONT WILL PUSH INTO THE FORECAST AREA SUNDAY NIGHT AND
MONDAY...THEN LIFT BACK TO THE NORTH AS A WARM FRONT AS SOUTH
FLOW INCREASES ON MONDAY NIGHT. SCT SHRA/ISOLD TSRA ARE ANTICIPATED
THROUGH THIS PERIOD.
THE WARMEST DAY OF THE WEEK IS EXPECTED ON TUESDAY...WITH HIGHS
IN THE 70 TO 75 RANGE OVER MOST INLAND AREAS. A COLD FRONT WILL
MOVE INTO THE WSTRN PART OF THE FA LATE TUESDAY...THEN THROUGH
THE REST OF THE CWA TUESDAY NIGHT. THIS FRONT SHOULD PROVIDE OUR
BEST BET FOR ORGANIZED THUNDERSTORM ACTIVITY DURING THE NEXT WEEK.
SIGNIFICANT DIFFERENCES DEVELOP BY WEDNESDAY AND WEDNESDAY NIGHT...
AS THE GFS TAKES MOST OF THE PCPN EAST OF THE REGION WHILE THE ECMWF
DEVELOPS A BAND OF SIGNIFICANT POST-FRONTAL PCPN IN ASSOCIATION WITH
A STG RRQ OF AN UPPER JET AND INCOMING UPPER TROF. WILL JUST CARRY
MID-RANGE POPS FOR NOW...AND SEE HOW THIS EVOLVES.
MUCH COLDER AIR WILL PUSH INTO THE AREA WEDNESDAY NIGHT...AND LINGER
INTO FRIDAY. IN ADDITION...THE DEEP UPPER TROF IS EXPECTED TO DEVELOP
INTO A CUT-OFF LOW OVER THE GREAT LAKES BY THE END OF THE WORK WEEK.
DESPITE THE CALENDAR READING EARLY MAY...CAN`T IGNORE THE POSSIBILITY
OF SOME LIGHT SNOW SHOWERS...ESPECIALLY OVER NC WI LATE WEDS NGT/
EARLY THU...AND OVER MOST OF THE FA LATE THU NGT INTO EARLY FRIDAY.
TEMPERATURES WILL RETURN TO MUCH BELOW NORMAL LEVELS.
&&
.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 619 PM CDT FRI APR 26 2013
A WEAK FRONT NOW OVER NORTHWEST WI...WILL STALL OVER NORTHERN WI
OVERNIGHT. MODELS SUGGEST LIGHT PCPN THIS EVENING...THOUGH ONLY
MID LEVEL CLOUDINESS HAS DEVELOPED. GIVEN THE FRONT...LIGHT WINDS
AND AVAILABLE LOW LEVEL MOISTURE...FOG EXPECTED...ESPECIALLY OVER
NORTH CENTRAL TAF SITES. UNCERTAINTY THOUGH ON DENSE FOG
CONTINUES...AS FRONT SLOWER AND TEMP/DEW POINTS SPREADS MUCH
LARGER THAN MODELS SUGGEST. WILL ONLY MAINTAIN AT RHI AT THIS
TIME. THE FOG WILL BURN OFF BY MID-MORNING TOMORROW WHICH WILL
LEAD TO BUILDING CUMULUS CLOUDS BY MIDDAY. &&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......KIECKBUSCH
AVIATION.......TE
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
.SHORT TERM...TONIGHT AND FRIDAY
ISSUED AT 231 PM CDT THU APR 25 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW AN AREA OF LOW
PRESSURE MOVING INTO SE ONTARIO EARLY THIS AFTERNOON AND A SURFACE
RIDGE AXIS SHIFTING EAST INTO WESTERN WISCONSIN. PLENTY OF CLOUD
COVER LEFT OVER BEHIND THE SURFACE LOW OVER THE STATE...THANKS TO
RESIDUAL MOISTURE AND STEEP LOW LEVEL LAPSE RATES. EVEN SCATTERED
LIGHT RAIN SHOWERS OR SPRINKLES DEVELOPED OVER FAR NE WISCONSIN
EARLY THIS AFTERNOON. CLEARING IS BEGINNING TO MOVE ACROSS THE
MISSISSIPPI RIVER...AND SHOULD ACCELERATE NE THROUGH THE REST OF THE
AFTERNOON. FURTHER WEST...THE NEXT SHORTWAVE IS ENTERING THE
NORTHERN PLAINS...AND CLOUDS ARE PUSHING INTO THE DAKOTAS. PRECIP
CHANCES WITH THIS SHORTWAVE ARE THE MAIN FORECAST CONCERNS LATE
TONIGHT INTO TOMORROW MORNING.
TONIGHT...RATHER BAGGY SURFACE RIDGE AXIS WILL WORK FROM WEST TO
EAST ACROSS THE REGION LATE THIS AFTERNOON AND THIS EVENING. WITH
LOSS OF CYCLONIC FLOW AND DIURNAL HEATING...THINK CLOUDS WILL
DISSIPATE BY MID-EVENING WHICH WILL SETUP A FEW HOUR PERIOD OF
MOSTLY CLEAR SKIES AND LIGHT WINDS. THESE CONDITIONS WILL BE
CONDUCIVE FOR TEMPS TO TUMBLE FAIRLY QUICKLY THIS EVENING OVER N-C
WISCONSIN WHERE THERE REMAINS SNOW PACK. MEANWHILE
UPSTREAM...SHORTWAVE TROUGH OVER NE MONTANA WILL SWING SE TOWARDS
THE WESTERN GREAT LAKES BY MORNING. RATHER BEEFY 40-50KT LLJ WILL
DEVELOP AHEAD OF THE SHORTWAVE WITH ITS NOSE MOVING OVER
NORTH-CENTRAL WISCONSIN LATE TONIGHT. WILL INCREASE POPS INTO THE
LIKELY RANGE. TEMPS WILL BOTTOM OUT EARLY OVERNIGHT BEFORE WINDS
ALOFT PICK UP WITH THE APPROACH OF THE LLJ. WILL GO WITH MID 20S
NORTH TO MID 30S SOUTH.
FRIDAY...THE NOSE OF THE LLJ WILL PASS OVER NE WISCONSIN IN THE
12-15Z TIME PERIOD AND WILL INCREASE POPS TO LIKELY. PRECIP SHOULD
EXIT THE AREA BY MID MORNING AND WILL SEE A PARTIAL DECREASE IN
CLOUDS AS LIFT ASSOCIATED WITH THE WARM ADVECTION DEPARTS. RATHER
BAGGY 850-700MB THETAE AXIS WILL REMAIN OVERHEAD FROM CENTRAL TO
NORTHEAST WISCONSIN FOR THE REST OF THE DAY. WITH AMPLE DAYTIME
HEATING AND GOOD MIXING...SHOULD BE AMPLE TO TAP INTO THIS MOISTURE
ALOFT FOR AT LEAST PARTLY CLOUDY/PARTLY SUNNY CONDITIONS IN THE
AFTERNOON. SOME MODELS SPIT OUT PRECIP WITHIN THIS THETAE
AXIS...BUT CONVERGENCE IS VERY WEAK AND CAPE IS AROUND 100 J/KG AT
MOST. SEEMS LIKE A BETTER CHANCE FOR PRECIP TO OCCUR IS SOUTHWEST
OF THE REGION IN AN AREA OF BETTER CONVERGENCE. RESULTING SHOWERS
WILL THEN HAVE POTENTIAL TO ADVECT INTO CENTRAL OR EAST-CENTRAL
WISCONSIN LATE IN THE AFTERNOON. WILL KEEP AN ISOLATED SHOWER
MENTION BUT DROP POPS EVERYWHERE ELSE. 925MB TEMPS ARGUE FOR HIGHS
NEAR 70F...SO WILL INCREASE HIGHS A DEGREE OR TWO. HIGHS MAINLY IN
THE LOW TO MID 60S.
.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY
ISSUED AT 231 PM CDT THU APR 25 2013
THE MAIN FCST CONCERNS INCLUDE MILDER TEMPERATURES FOR THE WEEKEND...
THEN PCPN TRENDS FOR NEXT WEEK.
A WEAKENING COLD FRONT WILL BE SAGGING SE ACROSS THE AREA ON FRIDAY
NIGHT. WILL ONLY KEEP A SLIGHT CHC OF SHOWERS DURING THE EARLY
EVENING FOR THE SE HALF OF THE FORECAST AREA...THEN DRY FOR THE
REST OF THE NIGHT. DECREASING CLOUDS...LIGHT WINDS AND LINGERING
SNOW COVER WILL SET THE STAGE FOR SOME FOG OVER NC/FAR NE WI LATE
FRIDAY NIGHT.
WENT WITH A MAINLY DRY FCST FROM SATURDAY THROUGH SUNDAY. ISOLD
SHOWERS MAY DEVELOP IN THE VCNTY OF THE OLD FRONTAL BOUNDARY ON
SATURDAY AFTERNOON...BUT CAPE IS ONLY EXPECTED TO BE AROUND 100
J/KG...SO WILL KEEP THE DRY FCST INTACT. THE NEXT FRONT IS
EXPECTED TO APPROACH OUR FAR NW COUNTIES LATE SUNDAY AFTERNOON...
A LITTLE FASTER THAN EXPECTED YESTERDAY...SO KEPT A SMALL POP
THERE. OTHERWISE...PARTLY CLOUDY SKIES AND MIXING THROUGH 800-850
MB SHOULD SUPPORT HIGHS IN THE MID 60S ON SATURDAY...AND UPPER 60S
TO LOWER 70S ON SUNDAY. THE EXCEPTION WILL BE NEAR LAKE
MICHIGAN...WHERE SOUTH WINDS WILL KEEP HIGH TEMPS 10-15 DEGREES
COOLER.
THE AFOREMENTIONED FRONT IS EXPECTED TO MOVE THROUGH GRB CWA
SUNDAY NIGHT INTO MONDAY...THEN EVENTUALLY LIFT BACK TO THE
NORTH AS A WARM FRONT MONDAY NIGHT INTO TUESDAY. SCT SHRA/ISOLD
TSRA CAN BE EXPECTED DURING THIS PERIOD. TUESDAY LOOKS LIKE THE
WARMEST DAY OF THE WEEK...WITH TEMPS APPROACHING THE MIDDLE 70S
IN CENTRAL WI.
A THIRD STRONGER COLD FRONT IS EXPECTED TO ARRIVE LATE TUES INTO
TUES NIGHT...THEN MOVE SLOWLY ACROSS THE AREA INTO WEDS OR WEDS
NIGHT. THE MOVEMENT WILL BE SLOWED BY THE DEVELOPMENT OF A MORE
AMPLIFIED SW FLOW...AS A DEEPENING UPPER TROF APPROACHES FROM THE
PLAINS. THIS FRONT SHOULD HAVE BETTER MOISTURE TO WORK WITH...AS
IT SHOULD EVENTUALLY TAP INTO THE GULF. MID-RANGE POPS SEEM
REASONABLE FOR NOW...BUT HIGHER POPS MAY EVENTUALLY BE NEEDED.
MAIN FOCUS FOR TSTMS WILL BE TUES NIGHT INTO WEDS...BUT NOT
EXPECTING ANY SEVERE WEATHER AT THIS TIME.
COOLER TEMPERATURES WILL ARRIVE WEDS INTO WEDS NGT...WITH A
MIXTURE OF RAIN/SNOW SHOWERS POSSIBLE OVER NC WI LATE WED NGT.
EXPECT MAX TEMPS TO DROP BACK BLO NORMAL AGAIN BY THURSDAY.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 100 PM CDT THU APR 25 2013
LINGERING MVFR CLOUD DECK OVER CENTRAL AND NORTH-CENTRAL
WISCONSIN WILL TURN TO VFR AS CLOUD BASES RISE THIS AFTERNOON. THIS
WILL SETUP VFR CONDITIONS THROUGH THE REST OF THE TAF PERIOD.
HOWEVER...THERE WILL BE A FEW HOUR PERIOD OF LIGHT RAIN SHOWERS
POSSIBLE LATE TONIGHT WHEN A WARM FRONT MOVES ACROSS THE REGION.
LOW LEVEL WIND SHEAR WILL RAMP UP DURING THIS SAME PERIOD AND
CONTINUE UNTIL MID-MORNING TOMORROW.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......KIECKBUSCH
AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1047 AM CDT THU APR 25 2013
.AVIATION/18Z TAFS/...PRIMARY SHORTWAVE TROUGH LIFTING NORTHEAST
FROM MICHIGAN PER WATER VAPOR LOOP. SECONDARY WAVE SEEN CRUISING
ESE THROUGH IA. NIL IMPACT FROM THE LATTER. MORNING 12Z UPPER AIR
ANALYSIS SHOWED A -36C AT 500 MILLIBARS AT KGRB...-28C AT KMPX. SO
VERY COLD AIR UPSTAIRS AND THE STILL AN ELONGATED CYCLONIC FLOW IN
THE WAKE OF THE PRIMARY TROUGH AXIS. EXPECT BROKEN CUMULUS TO
LINGER THIS AFTERNOON WITH BASES GRADUALLY RISING ABOVE MVFR
LEVELS. INCREASING WAA TONIGHT WITH RH PANELS SUGGESTING MID
CLOUDS FROM 6-14Z. QPF FROM THIS WAA PROGGD TO STAY NORTH OF TAF
SITES..SO WILL RETAIN DRY TAFS.
PC
&&
.PREV DISCUSSION... /ISSUED 347 AM CDT THU APR 25 2013/
VERY SHORT TERM...TODAY AND TONIGHT.
NARROW BAND OF RAIN SHOWERS WEAKENED WITH DIMINISHING LOW-LEVEL
FRONTOGENESIS AS IT CROSSED SOUTHERN WISCONSIN...THOUGH SOME
DOWNWARD MOMENTUM TRANSFER OF 30-40 KT WINDS AROUND 900 MB LED TO
WIND GUSTS UP TO 35 KNOTS AT LNR...30 KTS AT DLL...28 KTS AT MRJ AND
FLD...27 KTS AT EFT. GUSTS DIMINISHED IN INTENSITY WITH THE LOSS OF
MOMENTUM TRANSFER AS THE SHOWERS WEAKENED.
TODAY...FORECAST CONFIDENCE IS MEDIUM TO HIGH.
NARROW BAND OF LIGHT RAIN SHOWERS OVER SE WI ALONG SURFACE TROUGH
WILL EXIT BY 09Z...WITH DCVA-DRIVEN ISOLATED SHOWERS/SPRINKLES OVER
WESTERN CWA TO BE EAST OF CWA BY 12Z. HOWEVER...HI-RES/RAPID REFRESH
MODELS CONTINUE TO SHOW SPOTTY SHOWERS THIS MORNING IN REGION
BETWEEN DEPARTING WAVE TO THE NORTHEAST AND AHEAD OF SHORT WAVE
DROPPING THROUGH SW MN. WILL FOLLOW SHORT-TERM CONSENSUS AND KEEP A
SLIGHT CHANCE UNTIL MID MORNING. MODEL SOUNDINGS INDICATING
SCATTERED CUMULUS THIS AFTERNOON COULD BECOME BROKEN...WITH CAPE
APPROACHING 100 J/KG ON RAP SOUNDINGS...BUT MOISTURE MEAGER SO WILL
LEAVE DRY FOR NOW. 925 MB TEMPS RECOVER ENOUGH FOR HIGHS IN THE LOW
50S.
TONIGHT...FORECAST CONFIDENCE IS MEDIUM.
INCREASING CLOUDS TONIGHT WITH WARM AIR ADVECTION ON STRONG
LOW-LEVEL JET WINDS AHEAD OF NEXT SHORT THAT WAVE BRINGS ISENTROPIC
ADIABATIC OMEGA INTO THE REGION AFTER MIDNIGHT. 00Z ECMWF FOCUSES
THE BETTER LIFT AND LOWER CONDENSATION PRESSURE DEFICITS NORTH OF
CWA...00Z NAM MAINLY ACROSS THE NORTHWESTERN CWA...WHILE 00Z GFS
BRINGS IT ACROSS THE ENTIRE CWA BETWEEN 06Z AND 12Z FRIDAY. CANADIAN
AS WELL AS ARW AND NMM WRF MODELS ALSO FOCUS PCPN CHANCES IN THE
NORTHERN/NORTHWEST CWA. WITH DRY AIR BELOW 800 MB TO BE OVERCOME
WILL LIMIT SLIGHT CHANCE POPS TO NW CWA CLOSER TO THE CONSENSUS
LOWER PRESSURE DEFICITS.
FRIDAY THROUGH SATURDAY NIGHT...FORECAST CONFIDENCE IS MEDIUM TO
HIGH.
SHORT TERM MODELS CONTINUE TO SHOW LIGHT QPF FRIDAY MORNING ACROSS
NORTHERN AND CENTRAL WISCONSIN WITH THE 850MB LOW LEVEL JET NOSE
AND FOCUSED WARM AIR ADVECTION/FRONTOGENESIS RESPONSE. THEY SHOW
LIGHT QPF LINGERING ACROSS THE FAR NORTHERN AND NORTHWESTERN
COUNTIES FRIDAY AFTERNOON AND NIGHT...AS SURFACE TROUGH SHIFTS
INTO THE AREA AND LOW LEVEL FRONTOGENESIS RESPONSE LINGERS.
AREA FORECAST SOUNDINGS IN THESE AREAS SUGGEST DECENT BUT NOT
DEEP MOISTURE IN AIR COLUMN...WITH A DRY LAYER IN THE LOW LEVELS.
WILL CONTINUE TO MENTION SLIGHT CHANCE TO CHANCE POPS FOR SHOWERS
FRIDAY IN THE FAR NORTHERN AND NORTHWESTERN COUNTIES...WITH LOW
POPS FOR SHOWERS LINGERING FRIDAY NIGHT.
OTHERWISE...HIGH PRESSURE SOUTHEAST OF THE AREA WILL BRING STEADY
WARM AIR ADVECTION THROUGH THE REGION FRIDAY INTO SATURDAY NIGHT.
THIS SHOULD LEAD TO STEADILY WARMING TEMPERATURES RISING ABOVE
NORMAL.
PERSISTENT SOUTHWEST WINDS WILL NEGATE A LAKE BREEZE
FRIDAY...WHICH WILL BRING WARM TEMPERATURES IN THE 60S TO THE
ENTIRE AREA. HIGHS SHOULD RISE INTO THE 60S AGAIN SATURDAY PER
925MB TEMPERATURES...WITH A LAKE BREEZE LATE IN THE AFTERNOON NEAR
THE SHORE.
SUNDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE IS MEDIUM TO HIGH.
GFS/ECMWF ARE IN FAIR AGREEMENT WITH FEATURES DURING THIS PERIOD.
THEY CONTINUE TO BRING THE WARMEST AIRMASS SO FAR THIS SPRING INTO
THE REGION SUNDAY INTO WEDNESDAY...WITH SOUTHERLY WINDS. 925MB
TEMPERATURES RISING INTO THE MID TEENS CELSIUS RANGE.
THIS...COMBINED WITH DECENT LOW LEVEL MIXING...SUGGEST HIGHS INTO
THE LOWER TO MID 70S SUNDAY THROUGH TUESDAY. LAKE BREEZE SHOULD
DEVELOP EACH AFTERNOON NEAR THE LAKE...COOLING TEMPERATURES DOWN
QUITE A BIT THERE.
GFS/ECMWF BRING COLD FRONT SOUTHEASTWARD INTO THE AREA MONDAY
AFTERNOON AND EVENING...BEFORE STALLING AND SHIFTING BACK
NORTHEASTWARD AS A WARM FRONT LATER MONDAY NIGHT INTO TUESDAY. QPF
WITH THE FRONT IS SEEN OVER MOST OF THE AREA. BROUGHT LOWER END
POPS INTO THE FORECAST FOR MONDAY INTO TUESDAY. ADDED SLIGHT
CHANCES FOR THUNDER WITH SOME CAPE IN GFS FORECAST SOUNDINGS.
GFS/ECMWF IN BETTER AGREEMENT WITH BRINGING STRONG COLD FRONT EAST
INTO THE AREA WEDNESDAY...WITH AN AMPLIFIED 500MB SHORTWAVE TROUGH
FOLLOWING CLOSE BEHIND. THIS WOULD BRING THE NEXT ORGANIZED CHANCE
FOR SHOWERS AND THUNDERSTORMS. MUCH COOLER TEMPERATURES WOULD THEN
MOVE INTO THE REGION FOR LATER IN THE WEEK.
AVIATION/12Z TAFS/...WILL HAVE TO WATCH BAND OF MVFR CIGS...WITH
SOME LIGHT SPRINKLES/SHOWERS...RIGHT ALONG/BEHIND COLD FRONT TO SEE
IF IT WILL LINGER LONGER THAN MID-MORNING OVER THE REGION. COULD
STILL SEE A FEW GUSTS TO 20 KNOTS THROUGH 15Z. OTHERWISE EXPECT
SCT-BKN CU THIS AFTERNOON...WITH ENOUGH MIXING TO KEEP DECKS AT VFR
LEVELS. WARM ADVECTION CLOUDS RETURN TONIGHT...BUT ANY PCPN WILL
STAY NORTHWEST OF TAF SITES.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...REM
FRIDAY THROUGH WEDNESDAY...WOOD
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
347 AM CDT THU APR 25 2013
.VERY SHORT TERM...TODAY AND TONIGHT.
NARROW BAND OF RAIN SHOWERS WEAKENED WITH DIMINISHING LOW-LEVEL
FRONTOGENESIS AS IT CROSSED SOUTHERN WISCONSIN...THOUGH SOME
DOWNWARD MOMENTUM TRANSFER OF 30-40 KT WINDS AROUND 900 MB LED TO
WIND GUSTS UP TO 35 KNOTS AT LNR...30 KTS AT DLL...28 KTS AT MRJ AND
FLD...27 KTS AT EFT. GUSTS DIMINISHED IN INTENSITY WITH THE LOSS OF
MOMENTUM TRANSFER AS THE SHOWERS WEAKENED.
.TODAY...FORECAST CONFIDENCE IS MEDIUM TO HIGH.
NARROW BAND OF LIGHT RAIN SHOWERS OVER SE WI ALONG SURFACE TROUGH
WILL EXIT BY 09Z...WITH DCVA-DRIVEN ISOLATED SHOWERS/SPRINKLES OVER
WESTERN CWA TO BE EAST OF CWA BY 12Z. HOWEVER...HI-RES/RAPID REFRESH
MODELS CONTINUE TO SHOW SPOTTY SHOWERS THIS MORNING IN REGION
BETWEEN DEPARTING WAVE TO THE NORTHEAST AND AHEAD OF SHORT WAVE
DROPPING THROUGH SW MN. WILL FOLLOW SHORT-TERM CONSENSUS AND KEEP A
SLIGHT CHANCE UNTIL MID MORNING. MODEL SOUNDINGS INDICATING
SCATTERED CUMULUS THIS AFTERNOON COULD BECOME BROKEN...WITH CAPE
APPROACHING 100 J/KG ON RAP SOUNDINGS...BUT MOISTURE MEAGER SO WILL
LEAVE DRY FOR NOW. 925 MB TEMPS RECOVER ENOUGH FOR HIGHS IN THE LOW
50S.
.TONIGHT...FORECAST CONFIDENCE IS MEDIUM.
INCREASING CLOUDS TONIGHT WITH WARM AIR ADVECTION ON STRONG
LOW-LEVEL JET WINDS AHEAD OF NEXT SHORT THAT WAVE BRINGS ISENTROPIC
ADIABATIC OMEGA INTO THE REGION AFTER MIDNIGHT. 00Z ECMWF FOCUSES
THE BETTER LIFT AND LOWER CONDENSATION PRESSURE DEFICITS NORTH OF
CWA...00Z NAM MAINLY ACROSS THE NORTHWESTERN CWA...WHILE 00Z GFS
BRINGS IT ACROSS THE ENTIRE CWA BETWEEN 06Z AND 12Z FRIDAY. CANADIAN
AS WELL AS ARW AND NMM WRF MODELS ALSO FOCUS PCPN CHANCES IN THE
NORTHERN/NORTHWEST CWA. WITH DRY AIR BELOW 800 MB TO BE OVERCOME
WILL LIMIT SLIGHT CHANCE POPS TO NW CWA CLOSER TO THE CONSENSUS
LOWER PRESSURE DEFICITS.
.FRIDAY THROUGH SATURDAY NIGHT...FORECAST CONFIDENCE IS MEDIUM TO
HIGH.
SHORT TERM MODELS CONTINUE TO SHOW LIGHT QPF FRIDAY MORNING ACROSS
NORTHERN AND CENTRAL WISCONSIN WITH THE 850MB LOW LEVEL JET NOSE
AND FOCUSED WARM AIR ADVECTION/FRONTOGENESIS RESPONSE. THEY SHOW
LIGHT QPF LINGERING ACROSS THE FAR NORTHERN AND NORTHWESTERN
COUNTIES FRIDAY AFTERNOON AND NIGHT...AS SURFACE TROUGH SHIFTS
INTO THE AREA AND LOW LEVEL FRONTOGENESIS RESPONSE LINGERS.
AREA FORECAST SOUNDINGS IN THESE AREAS SUGGEST DECENT BUT NOT
DEEP MOISTURE IN AIR COLUMN...WITH A DRY LAYER IN THE LOW LEVELS.
WILL CONTINUE TO MENTION SLIGHT CHANCE TO CHANCE POPS FOR SHOWERS
FRIDAY IN THE FAR NORTHERN AND NORTHWESTERN COUNTIES...WITH LOW
POPS FOR SHOWERS LINGERING FRIDAY NIGHT.
OTHERWISE...HIGH PRESSURE SOUTHEAST OF THE AREA WILL BRING STEADY
WARM AIR ADVECTION THROUGH THE REGION FRIDAY INTO SATURDAY NIGHT.
THIS SHOULD LEAD TO STEADILY WARMING TEMPERATURES RISING ABOVE
NORMAL.
PERSISTENT SOUTHWEST WINDS WILL NEGATE A LAKE BREEZE
FRIDAY...WHICH WILL BRING WARM TEMPERATURES IN THE 60S TO THE
ENTIRE AREA. HIGHS SHOULD RISE INTO THE 60S AGAIN SATURDAY PER
925MB TEMPERATURES...WITH A LAKE BREEZE LATE IN THE AFTERNOON NEAR
THE SHORE.
.SUNDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE IS MEDIUM TO HIGH.
GFS/ECMWF ARE IN FAIR AGREEMENT WITH FEATURES DURING THIS PERIOD.
THEY CONTINUE TO BRING THE WARMEST AIRMASS SO FAR THIS SPRING INTO
THE REGION SUNDAY INTO WEDNESDAY...WITH SOUTHERLY WINDS. 925MB
TEMPERATURES RISING INTO THE MID TEENS CELSIUS RANGE.
THIS...COMBINED WITH DECENT LOW LEVEL MIXING...SUGGEST HIGHS INTO
THE LOWER TO MID 70S SUNDAY THROUGH TUESDAY. LAKE BREEZE SHOULD
DEVELOP EACH AFTERNOON NEAR THE LAKE...COOLING TEMPERATURES DOWN
QUITE A BIT THERE.
GFS/ECMWF BRING COLD FRONT SOUTHEASTWARD INTO THE AREA MONDAY
AFTERNOON AND EVENING...BEFORE STALLING AND SHIFTING BACK
NORTHEASTWARD AS A WARM FRONT LATER MONDAY NIGHT INTO TUESDAY. QPF
WITH THE FRONT IS SEEN OVER MOST OF THE AREA. BROUGHT LOWER END
POPS INTO THE FORECAST FOR MONDAY INTO TUESDAY. ADDED SLIGHT
CHANCES FOR THUNDER WITH SOME CAPE IN GFS FORECAST SOUNDINGS.
GFS/ECMWF IN BETTER AGREEMENT WITH BRINGING STRONG COLD FRONT EAST
INTO THE AREA WEDNESDAY...WITH AN AMPLIFIED 500MB SHORTWAVE TROUGH
FOLLOWING CLOSE BEHIND. THIS WOULD BRING THE NEXT ORGANIZED CHANCE
FOR SHOWERS AND THUNDERSTORMS. MUCH COOLER TEMPERATURES WOULD THEN
MOVE INTO THE REGION FOR LATER IN THE WEEK.
&&
.AVIATION/12Z TAFS/...WILL HAVE TO WATCH BAND OF MVFR CIGS...WITH
SOME LIGHT SPRINKLES/SHOWERS...RIGHT ALONG/BEHIND COLD FRONT TO SEE
IF IT WILL LINGER LONGER THAN MID-MORNING OVER THE REGION. COULD
STILL SEE A FEW GUSTS TO 20 KNOTS THROUGH 15Z. OTHERWISE EXPECT
SCT-BKN CU THIS AFTERNOON...WITH ENOUGH MIXING TO KEEP DECKS AT VFR
LEVELS. WARM ADVECTION CLOUDS RETURN TONIGHT...BUT ANY PCPN WILL
STAY NORTHWEST OF TAF SITES.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...REM
FRIDAY THROUGH WEDNESDAY...WOOD
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1219 AM CDT THU APR 25 2013
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND THURSDAY
ISSUED AT 245 PM CDT WED APR 24 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A HIGH PRESSURE
RIDGE AXIS STRETCHING FROM THE SOUTHERN GREAT PLAINS ACROSS NE
WISCONSIN TO JAMES BAY EARLY THIS AFTERNOON. QUIET WEATHER EXISTS
ACROSS THE FORECAST AREA CURRENTLY...BUT MORE ACTIVE CONDITIONS EXIST
UPSTREAM OVER NE MINNESOTA. A WEAK SHORTWAVE IS PUSHING AN AREA OF
RAIN AND SNOW SOUTH OF DULUTH AND INTO NW WISCONSIN. BUT THE MAIN
SHORTWAVE TROUGH IS STILL OUT OVER NORTH DAKOTA WHERE SCATTERED RAIN
AND SNOW SHOWERS ARE FLYING. IN THE HEAVIER SNOW SHOWERS...VISIBILITIES
ARE FALLING TO AROUND A HALF TO THREE QUARTERS OF A MILE. AS THESE
SHORTWAVE TROUGHS PASS ACROSS THE FORECAST AREA TONIGHT...PRECIP
CHANCES AND AMOUNTS ARE THE MAIN FORECAST CONCERNS.
TONIGHT...THE MAIN SHORTWAVE TROUGH WILL SHARPEN AS IT DIGS ACROSS
THE NORTHERN MISSISSIPPI THIS EVENING AND THE STATE OF WISCONSIN
TONIGHT. A WEAK LITTLE WAVE OVER NORTHERN MINNESOTA WILL PUSH A
LEAD AREA OF PRECIP ENE ACROSS NORTH-CENTRAL WISCONSIN EARLY THIS
EVENING. DESPITE DEWPOINTS IN THE TEENS IN THIS REGION
CURRENTLY...PRECIP RATES LOOK IMPRESSIVE ENOUGH ON RADAR TO THINK
PRECIP WILL REACH THE GROUND EARLY THIS EVENING. THE PRECIP WILL BE
ARRIVING JUST AFTER PEAK HEATING...SO THINK PRECIP WILL START OUT AS
RAIN...THOUGH CANT RULE OUT SNOW FLAKES MIXING IN WITH THE RAIN
DROPS WITHIN THE HEAVIER SHOWERS. THE MAIN SHORTWAVE WILL THEN MOVE ACROSS
THE REGION LATE THIS EVENING THROUGH THE MIDDLE OF THE OVERNIGHT
PERIOD. SATELLITE AND RADAR UPSTREAM LOOK RATHER SHOWERY...PARTLY
CONTRIBUTED TO STEEP MID-LEVEL LAPSE RATES AROUND 8 C/KM. THINK
PRECIP WILL REMAIN SHOWERY TONIGHT DESPITE LOSS OF DIURNAL HEATING.
SURFACE WET BULB TEMPS STRUGGLE TO FALL BELOW FREEZING DURING THE
PERIOD THE PRECIP IS EXPECTED TO FALL...SO PTYPE WILL REMAIN
UNCERTAIN. THINK PRECIP WILL MAINLY BE RAIN OR A RAIN/SNOW MIX THIS
EVENING...CHANGING OVER TO SNOW AFTER MIDNIGHT AS SLIGHTLY COLDER
AIR MOVES IN BEHIND A SURFACE TROUGH. BUT THE ABOVE FREEZING WET
BULB TEMPS SUGGEST ACCUMS WILL BE LIMITED...PERHAPS A HALF INCH TO
AN INCH ON GRASSY SURFACES (HIGHER NORTH). PRECIP TO EXIT LATE
TONIGHT AND SKIES MAY PARTIALLY CLEAR OVER CENTRAL AND EAST-CENTRAL
WISCONSIN. LOWS IN THE UPPER 20S NORTH TO MID 30S SOUTH.
THURSDAY...SOME CLOUDS TO LINGER THURSDAY MORNING AND WILL GO
WITH A PARTLY TO MOSTLY CLOUDY START TO THE DAY AS RESIDUAL
MOISTURE AND CYCLONIC FLOW REACTS WITH DIURNAL HEATING.
HOWEVER...MIXING AND A WEAK 850MB RIDGE AXIS SHOULD LEAD TO
DECREASING CLOUDS IN THE AFTERNOON. HIGHS A DEGREE OR TWO COOLER
THAN TODAY.
.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 245 PM CDT WED APR 24 2013
MAIN FCST CONCERNS ARE PCPN TRENDS THU NGT INTO FRIDAY...AND
DURING THE EARLY TO MID PART OF THE NEXT WORK WEEK...AND FINALLY
SOME WARMER TEMPERATURES.
COOL NORTHWEST FLOW WILL BE REPLACED BY A ZONAL WESTERLY FLOW BY
THE WEEKEND...THEN BECOME MORE AMPLIFIED WITH SOUTHWEST FLOW AS A
TROF DEEPENS OVER THE ROCKIES AND NORTHERN PLAINS DURING THE EARLY
TO MID PART OF THE NEXT WORK WEEK. THE BIGGEST CHANGE WILL BE MUCH
WARMER AND ABOVE NORMAL TEMPS...WITH HIGHS WARMING INTO THE 60S
AND LOWER 70S FOR MOST OF THE PERIOD. THE WARMEST DAYS LOOK LIKE
THEY WILL OCCUR ON MONDAY AND TUESDAY.
FAIRLY STRONG WAA/ISENT LIFT WILL DEVELOP THURSDAY NIGHT...AND
CONTINUE INTO FRIDAY MORNING. IN ADDITION...A S/W TROF WILL TRACK
ACROSS THE REGION LATE THURSDAY NIGHT AND FRIDAY. RH/OMEGA
TIMESECTIONS INDICATE THAT MOISTURE WILL BE SOMEWHAT LACKING...
WITH PCPN NOT DEVELOPING UNTIL AFTER 09Z/FRI IN OUR WESTERN COUNTIES.
LOW-LEVEL THICKNESSES AND TEMPS INDICATE THAT PCPN SHOULD BE MAINLY
RAIN ACROSS CENTRAL WI...BUT A LIGHT MIX OF SNOW/SLEET/RAIN MAY
BRIEFLY OCCUR IN NC WI. DO NOT PLAN TO CARRY A MIX INTO FRIDAY...
AND WILL JUST HAVE A CHANCE OF SHOWERS ACROSS THE CWA.
GENERALLY DRY CONDITIONS ARE EXPECTED FROM FRIDAY NIGHT THROUGH
SUNDAY...MAKING FOR A VERY NICE AND MILD WEEKEND.
A WEAKENING COLD FRONT AND RRQ OF AN UPPER LEVEL JET WILL BRING A
CHANCE OF SHOWERS/ISOLD TSTMS TO OUR NW COUNTIES SUNDAY NIGHT. THE
FRONT IS EXPECTED TO BECOME ORIENTED MORE WEST TO EAST ACROSS THE
AREA ON MONDAY...THEN LIFT NORTH AS A WARM FRONT ON MONDAY NIGHT
AS LOW PRESSURE ORGANIZES IN THE NORTHERN PLAINS. THE THREAT OF
SHOWERS AND TSTMS WILL CONTINUE ALONG THIS BOUNDARY. A STRONGER...
BUT SLOW MOVING COLD FRONT WILL EDGE TOWARD THE AREA TUESDAY INTO
WEDNESDAY...WITH MAINLY POST-FRONTAL PCPN EXPECTED. PCPN ASSOCIATED
WITH THIS FEATURE SHOULD ARRIVE IN OUR NW COUNTIES TUES NGT...AND
ACROSS THE REST OF THE AREA ON WEDNESDAY.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1218 AM CDT THU APR 25 2013
A VIGOROUS UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE AREA
OVERNIGHT AND PRODUCE WIDELY VARIABLE CEILINGS AND VISIBILITIES
DUE TO SNOW AND RAIN SHOWERS. THE LOWER CIGS WILL BE CONFINED TO
OR JUST AFTER THE FROPA WHERE THE RAIN CHANGES TO SNOW. AFTER THIS
SHORT WAVE TROUGH WITH COLD FRONT DEPARTS TO THE EAST THIS
MORNING...VFR CONDITIONS WILL RETURN TODAY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......KIECKBUSCH
AVIATION.......TDH
AREA FORECAST DISCUSSION
NWS LITTLE ROCK AR
349 AM CDT SAT APR 27 2013
..SHORT TERM...TODAY THROUGH TUESDAY NIGHT
USETTLED CONDITIONS ARE EXPECTED FOR THE FIRST BACK OF THE WEEKEND
BUT THE SECOND HALF APPEARS TO BE MUCH BETTER AT THIS POINT. GFS
SOLUTION HAS BEEN THE MOST CONSISTENT MODEL OF LATE IN THE SYNOPTIC
SCALE AND SEE NO REAL REASON TO STRAY FROM IT AT THIS POINT.
SHORTWAVE TROUGH...CLEARLY EVIDENT ON MOISTURE CHANNEL IMAGERY THIS
MORNING...EXTENDS FROM EASTERN KANSAS DOWN TO THE TEXAS PANHANDLE.
FEATURE IS EXPECTED TO MOVE TO THE EAST OVER THE NEXT 24 HOURS OR SO
WITH A WEAK H5 LOW DEVELOPING AS IT DOES. ON THE SURFACE...LATEST
ANALYSIS PLACES A WEAK WARM FRONT ALONG THE ARKANSAS/LOUISIANA
BORDER ANCHORED BY WEAK LOW PRESSURE ALONG THE RED RIVER. THIS
FEATURE APPEARS TO BE STARTING TO MOVE TOWARDS THE NORTH.
RADAR IMAGERY ACROSS THE REGION SHOWS ONGOING...SCATTERED SHOWER
ACTIVITY ACROSS THE STATE THAT IS LIKELY BEING GENERATED IN AN AREA
OF ASCENT ASSOCIATED WITH THE LOW LEVEL JET. CONVECTIVE COMPLEX
OVER EASTERN OKLAHOMA/WESTERN ARKANSAS HAS BEEN STEADILY WEAKENING
WITH TIME. THE AFOREMENTIONED TROUGH WILL PUSH SLOWLY EAST TODAY AS
FRONTAL SYSTEM LIFTS TO THE NORTH WITH WIDESPREAD SHOWER AND
THUNDERSTORM ACTIVITY CONTINUING.
BEST CHANCES OF PRECIPITATION LOOK TO BE EARLY IN THE DAY WITH
CHANCES DECREASING DURING THE DAY AS SYSTEM LIFTS THROUGH. BEST
CHANCES WILL THEN BE CONFINED TO THE TRAILING COLD FRONT AND THERE
REMAINS A CHANCE OF SOME STRONGER CONVECTION OVER THE SOUTHEAST PART
OF THE STATE. WILL HOLD ONTO LINGERING PRECIPITATION CHANCES
EARLY ON SUNDAY BEFORE ENDING THE RAINFALL ENTIRELY.
QPF FORECASTS ALL OVER PLACE THIS MORNING BUT HRRR MODEL ACTUALLY
SEEMS TO HAVE THE BEST HANDLE ON THE SYSTEM. AS SUCH...WILL FOLLOW
ITS TRENDS CONCERNING PRECIPITATION COVERAGE AND WILL TRIM BACK THE
AMOUNTS. WILL BLEND ECWMF/MAV NUMBERS FOR TEMPERATURES.
REMAINDER OF THE SHORT TERM PERIOD LOOKS RATHER EVENTFUL AS SURFACE
HIGH PRESSURE MOVES ACROSS AND EVENTUALLY EAST OF THE FORECAST AREA.
SOUTHERLY SURFACE WINDS AND A RATHER NONDESCRIPT UPPER FLOW WILL
ALLOW TEMPERATURES TO GET ABOVE NORMALS FOR LATE APRIL/EARLY MAY.
NEXT SYSTEM WILL BEGIN TO DROP DOWN INTO THE CENTRAL PLAINS LATE BUT
ITS IMPACTS WILL LIKELY BE FELT IN THE EXTENDED PERIOD.
&&
.LONG TERM...WEDNESDAY THROUGH FRIDAY...
AN UPPER TROUGH WILL BE OVER THE NORTHERN PLAINS TO BEGIN THE PERIOD
WITH A RIDGE OVER THE EASTERN U.S. THE UPPER TROUGH WILL DEEPEN
THROUGH THE SOUTHERN PLAINS WEDNESDAY NIGHT AND THURSDAY. BY FRIDAY
IT BECOMES A CLOSED LOW OVER THE OHIO RIVER VALLEY PROVIDING
NORTHWEST FLOW TO ARKANSAS.
A COLD FRONT WILL MOVE THROUGH ARKANSAS WEDNESDAY. MOISTURE WILL
STREAM NORTH OUT OF THE GULF OF MEXICO. CHANCES OF SHOWERS AND
THUNDERSTORMS WILL INCREASE THROUGH WEDNESDAY...REACH THEIR PEAK
WEDNESDAY NIGHT...AND END THURSDAY MORNING. HIGH PRESSURE WILL BUILD
OVER THE AREA THURSDAY AND FRIDAY. MUCH COOLER AND DRIER AIR WILL BE
USHERED IN WITH THIS COLD HIGH PRESSURE SYSTEM. ABOVE NORMAL
TEMPERATURES ARE EXPECTED WEDNESDAY AND MUCH BELOW NORMAL FOR
THURSDAY AND FRIDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
BATESVILLE AR 70 52 72 52 / 70 40 20 10
CAMDEN AR 78 57 77 51 / 60 30 10 10
HARRISON AR 65 49 72 51 / 80 20 10 10
HOT SPRINGS AR 74 54 76 52 / 60 20 10 10
LITTLE ROCK AR 74 55 75 54 / 60 30 10 10
MONTICELLO AR 79 59 76 54 / 80 40 20 10
MOUNT IDA AR 73 52 76 51 / 60 20 10 10
MOUNTAIN HOME AR 66 50 72 51 / 80 30 10 10
NEWPORT AR 71 54 72 52 / 70 40 20 10
PINE BLUFF AR 77 57 76 54 / 70 40 20 10
RUSSELLVILLE AR 70 51 74 53 / 70 20 10 10
SEARCY AR 72 54 73 53 / 70 40 20 10
STUTTGART AR 75 56 75 54 / 70 40 20 10 &
.LZK WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...51 / LONG TERM...56
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
402 AM CDT SAT APR 27 2013
.SYNOPSIS...
ISSUED AT 400 AM CDT SAT APR 27 2013
THE 00 UTC OBJECTIVE ANALYSIS INDICATED THE 700 MB LOW WAS
POSITIONED ACROSS SOUTH CENTRAL KANSAS AND SLOWLY TRANSLATING
EASTWARD WITH TIME. THE UPPER FLOW WAS SPLIT WITH THE MAIN UPPER JET
ENERGY FOCUSED ACROSS CANADA AND THE SOUTHERN PLAINS. THIS SLOWLY
MOVING SYSTEM WAS RESPONSIBLE FOR A DECAYING MCS ACROSS CENTRAL
OKLAHOMA OVERNIGHT AND WIDESPREAD STRATUS AND DEVELOPING FOG ACROSS
CENTRAL AND WESTERN KANSAS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CDT SAT APR 27 2013
THE CONCERNS IN THE SHORT TERM WILL REVOLVE AROUND FOG THIS MORNING,
FOLLOWED BY TEMPERATURES AND CLEARING THIS AFTERNOON. THE
AFOREMENTIONED 700-500 MB LOW CENTER IS FORECAST TO BE POSITIONED
ACROSS SOUTHEAST KANSAS BY AROUND 12 UTC AND OVER MISSOURI BY THIS
EVENING. WESTERN KANSAS WILL SLOWLY COME UNDER THE INFLUENCE OF
NORTHWEST FLOW ALOFT AND INCREASED SUBSIDENCE ALOFT. WINDS SHOULD
REMAIN LIGHT AND VARIABLE GIVEN THE PRESENCE OF A SURFACE RIDGE
EXTENDING FROM THE UPPER MISSISSIPPI VALLEY INTO CENTRAL KANSAS.
JUST HOW LONG FOG PERSISTS THIS MORNING WILL FIRST DEPEND ON HOW
EXTENSIVE THE FOG DEVELOPS BETWEEN 10 AND 13Z UNDER THE CLEARING MID
LEVEL CLOUDS. LIGHT WESTERLY WINDS MIGHT ALLOW IMPROVEMENT IN THE
SCOTT CITY TO GARDEN CITY AND EVEN DODGE CITY AREAS THIS MORNING,
BUT LIGHT AND VARIABLE WINDS ARE MORE CONCERNING FOR DENSE FOG
ESPECIALLY AROUND HAYS AND SOUTHWARD.
THE BOUNDARY LAYER WILL BE MUCH DRIER ACROSS THE FAR WESTERN KANSAS
COUNTIES THIS AFTERNOON WHICH SHOULD ALLOW TEMPERATURES TO RAPIDLY
WARM INTO THE MID 70`S F BY AROUND NOON. AT THE SAME TIME,
TEMPERATURES ACROSS SOUTH CENTRAL KANSAS, HINDERED BY NORTHEASTERLY
WINDS WILL LIKELY WARM SLOWER, STRUGGLING THROUGH THE 60S FOR MUCH
OF THE DAY. HIGHS NEAR 70 DEGREES SHOULD BE ACHIEVABLE BY MID TO
LATE AFTERNOON. BY SATURDAY NIGHT INTO EARLY SUNDAY MORNING LIGHT
SOUTHWEST WINDS WILL BECOME ESTABLISHED ACROSS THE REGION. WITH NO
SIGNIFICANT CHANGE IN BOUNDARY AIRMASS AND DEW POINTS REMAINING IN
THE MID 40`S, A GENERALLY MILD OVERNIGHT IS EXPECTED. WITH SOUTHWEST
FLOW, FOG DEVELOPMENT IS NOT ANTICIPATED.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 400 AM CDT SAT APR 27 2013
SUNDAY THROUGH TUESDAY:
VERY WARM WEATHER WILL BE THE STORY DURING THIS TIME FRAME...WITH
80S EXPECTED EACH DAY. TUESDAY WILL LIKELY BE THE WARMEST DAY OF THE
THREE AS THE 850-700MB THERMODYNAMIC PROFILE WILL BE VERY WARM IN
THE INCREASING MIDDLE TROPOSPHERIC DOWNSLOPE MOMENTUM. THERE WILL
LIKELY BE A DRYLINE SOMEWHERE ACROSS SOUTHWEST KANSAS INTO THE TEXAS
PANHANDLE...WITH 25 TO 35F DEWPOINTS WEST OF THE DRYLINE AND 50S TO
NEAR 60F DEWPOINTS EAST OF THE DRYLINE. THE SIGNIFICANT AMOUNT OF
WARMTH AT 700MB WILL LIKELY PUT A LID ON ANY THUNDERSTORM FORMATION
ON THE DRYLINE...SO WILL KEEP THE FORECAST TUESDAY DRY.
TUESDAY NIGHT THROUGH THURSDAY:
TO SAY THAT THE FORECAST IN THIS TIME FRAME IS CHALLENGING IS A
MAJOR UNDERSTATEMENT. EVERY SINGLE GLOBAL MODEL IS SHOWING A
PRONOUNCED UPPER LOW DEVELOPMENT ACROSS THE GREAT PLAINS OR MIDWEST
REGION FOLLOWING A POLAR JET AMPLIFICATION EVENT. AS THE TROUGH
UNDERGOES AMPLIFICATION...A VERY INTENSE COLD FRONT WILL PUSH SOUTH
QUICKLY LATE TUESDAY INTO EARLY WEDNESDAY. THE LATEST ECMWF MODEL
SHOWS A SIGNIFICANT AMOUNT OF COLD AIR BEHIND THIS FRONT...WHICH IS
SOMETHING TO TAKE SERIOUSLY BECAUSE THE ECMWF WAS THE FIRST MODEL TO
CATCH ON TO ANOMALOUS COLD EVENTS IN APRIL. YET ANOTHER ANAFRONTAL
PRECIPITATION EVENT MAY UNFOLD IN THE COLD AIR ACROSS THE CENTRAL
PLAINS AS IS SUGGESTED BY THE ECMWF...WHICH COULD INCLUDE FROZEN
PRECIPITATION AS THE 850-700MB COLUMN COOLS DOWN TO AND BELOW ZERO
CELSIUS SOMETIMES LATE WEDNESDAY OR WEDNESDAY NIGHT. AT THIS
TIME...THE OFFICIAL FORECAST WILL REMAIN ON THE CONSERVATIVE SIDE
WITH PRECIPITATION IN THE FORM OF SHOWERS AND ISOLATED
THUNDERSTORMS. IF THE ATMOSPHERE GOES IN THE DIRECTION OF THE
ECMWF...THEN WE WILL HAVE TO THINK ABOUT SOME SLEET OR WET SNOW
AGAIN! EITHER WAY...THE PERIOD WEDNESDAY THROUGH THE END OF THE
UPCOMING WEEK LOOKS WET AND COOL (IF NOT COLD).
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1242 AM CDT SAT APR 27 2013
DENSE FOG IS BECOMING MORE WIDESPREAD ACROSS SOUTHWEST KANSAS EARLY
THIS MORNING. BASED ON THE CURRENT TRENDS AND THE LAST HRRR MODEL AS
WELL AS TRENDS FROM THE LOCAL GFS MOS GUIDANCE, SEVERAL HOURS OF
LIFR/VLIFR VISIBILITIES IN DENSE FOG IS EXPECTED THROUGH SATURDAY
MORNING AT EACH OF THE AREA TERMINALS.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 75 46 84 50 / 0 0 0 10
GCK 77 41 84 48 / 0 0 0 10
EHA 77 45 84 48 / 0 10 0 10
LBL 77 44 85 50 / 0 10 0 10
HYS 73 45 84 50 / 0 0 0 10
P28 72 48 83 55 / 0 0 10 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR KSZ030-031-
043>046-063>065-077>079-087-088.
&&
$$
SYNOPSIS...RUSSELL
SHORT TERM...RUSSELL
LONG TERM...UMSCHEID
AVIATION...RUSSELL
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1217 AM MDT SAT APR 27 2013
.UPDATE...
ISSUED AT 1212 AM MDT SAT APR 27 2013
FOG STARTING TO DEVELOP ACROSS THE AREA NOW...WITH DENSE FOG
ALREADY REPORTED AT OAKLEY AND VISIBILITIES FALLING TO THE NORTH
AND EAST. THINK THIS AIRMASS WILL SHIFT EAST THROUGH THE
NIGHT...BUT HAVE ISSUED ADVISORY AS FAR WEST AS COLBY AND LEOTI
AREAS AND PLAN ON CLEARING AS FOG THREAT WANES.
UPDATE ISSUED AT 827 PM MDT FRI APR 26 2013
JUST COMPLETED AN UPDATE. MAIN CHANGE WAS TO INTRODUCE FOG FOR
TONIGHT INTO MID MORNING ON SATURDAY. DDC SOUNDING AND SURFACE
OBSERVATIONS WOULD INDICATE A RATHER MOIST TO OUR SOUTH. DEWPOINTS
HAVE BEEN INCREASING AND PUSHING FARTHER WEST THAN ANYTHING
INDICATES. THIS IS A RESULT OF MODELS HANDLING THE WIND/PRESSURE
FIELD POORLY AS WELL. RUC AND HRRR APPEAR TO BE CATCHING ALL THIS
FAIRLY WELL AND USED AS THE BASIS FOR THE UPDATE. ALSO ADJUSTED
SKY COVER UP A LITTLE AND RAISED THE MINS AS WELL.
UPDATE ISSUED AT 624 PM MDT FRI APR 26 2013
LET THE RED FLAG WARNING EXPIRE. PER LATEST OBSERVATIONS INCREASED
CLOUD COVER AND ADJUSTED DEWPOINTS DOWN.
&&
.SHORT TERM...(THIS AFTERNOON THROUGH SATURDAY)
ISSUED AT 139 PM MDT FRI APR 26 2013
H5 TROUGH AXIS CURRENTLY EXTENDS ACROSS WESTERN KS...WITH H7
CLOSED CENTER OVER SW KS NEAR 0K PANHANDLE. FRONTOGENETICAL FORCING
ALONG NW EXTENT OF H7 LOW HAS COMBINED WITH ELEVATED INSTABILITY
TO PRODUCE SHOWERS AND THUNDERSTORMS OVER PARTS OF SW KS...WITH
THE EDGE OF THIS ACTIVITY JUST SOUTHEAST OF OUR CWA BORDER. SHORT
RANGE GUIDANCE KEEPS THIS ACTIVITY SOUTH AND EAST OF OUR CWA AS
THE H5/H7 TROUGH SHIFTS EAST THIS AFTERNOON AND EVENING. THERE
HAVE BEEN LIGHT RADAR RETURNS OVER OUR SOUTHEASTERN CWA...HOWEVER
WITH MUCH DRIER AIR UNDERCUTTING THE NORTHERN EDGE OF THIS ACIDITY
AND SUBSIDENCE MOVING IN FROM THE NORTHWEST I AM SKEPTICAL THAT WE
WILL SEE MUCH MORE THAN ISOLATED SHOWERS THIS AFTERNOON.
A SURFACE TROUGH AXIS IS CURRENTLY CENTERED ALONG A LINE FROM JUST
EAST OF MCCOOK TO THE SOUTHWEST KS/CO BORDER. WEST OF THIS...VERY
GOOD MIXING ASSOCIATED WITH A DEEP DRY ADIABATIC LAYER (TO ABOUT
700MB) HAS LED TO VERY WARM/DRY CONDITIONS AND GUSTY WINDS MIXING
TO THE SURFACE. RED FLAG WARNING WAS ISSUED IN RESPONSE TO RH
VALUES FALLING TO 10-20% WITH GUSTS TO 30 MPH. AS THIS SURFACE
TROUGH SHIFTS EAST THIS AFTERNOON AND HIGH PRESSURE BUILDS INTO
NORTHEAST COLORADO THE GRADIENT WILL BEGIN TO WEAKEN...AND WINDS
SHOULD DECREASE SOME. I COULD SEE ENDING THE RFW EARLY FOR WESTERN
LOCATIONS...BUT WE SHOULD STILL SEE ABOUT 3HR OF RFW CONDITIONS
BEFORE ALL IS SAID AND DONE.
ANOTHER VERY WARM DAY IS EXPECTED SATURDAY...AND IF HIGH
TEMPERATURES TODAY ARE ANY INDICATION WE SHOULD SEE WIDESPREAD
HIGHS IN THE UPPER 70S/LOW 80S...POSSIBLY WARMER. WE SHOULD ALSO
SEE RH VALUES DROP TO WITHIN RFW CRITERIA...HOWEVER WINDS ALOFT
ARE MUCH LIGHTER...SO I AM NOT EXPECTING A REPEAT OF THIS
AFTERNOON REGARDING FIRE WEATHER.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 210 PM MDT FRI APR 26 2013
SATURDAY NIGHT-MONDAY...DRY. GENERALLY CLEAR THROUGH SUNDAY WITH AN
INCREASE IN MID AND HIGH LEVEL CLOUDS SUNDAY NIGHT AS A WEAK WEATHER
SYSTEM MOVES THROUGH UPPER W/NW FLOW ALOFT. BIGGER STORY WILL BE THE
VERY WARM TEMPERATURES.
HIGH TEMPERATURES SUNDAY 75 TO 80 IN FAR EASTERN COLORADO...LOW TO
MID 80S ELSEWHERE. FOR MONDAY 850 TEMPERATURES FROM GFS/NAM/ECMWF
AVERAGE A FEW DEGREES WARMER. DISCREPANCIES SHOW UP WITH REGARD TO
850 THERMAL AXIS. GFS/ECMWF INDICATING LESS AGGRESSIVE WARMING ACROSS
THE EASTERN 1/3 OF THE AREA WHILE NAM/SREF ARE SEVERAL DEGREES
WARMER. THIS DISCREPANCY RESULTS IN A SIGNIFICANT DIFFERENCE IN
TEMPERATURE AS THE COOLER SOLUTION WOULD SUGGEST HIGHS GENERALLY IN
THE MID TO UPPER 80S (WEST TO EAST) WHILE THE WARMER SOLUTIONS WOULD
SUGGEST MID 80S TO MID 90S (WEST TO EAST). IF THE WARMER SOLUTION
VERIFIES RECORD HIGH TEMPERATURES WOULD BE REACHED OR TIED JUST
ABOUT EVERYWHERE. WITH A SOUTHEAST TO SOUTH COMPONENT TO THE SFC
WIND EXPECTED DURING THE DAY WILL TREND TOWARD THE COOLER SOLUTION
WHICH STILL PRODUCES HIGHS IN THE 80S...MUCH ABOVE NORMAL FOR MANY.
TUESDAY...COLD FRONT MOVES THROUGH DURING THE DAY LOWERING AFTERNOON
TEMPERATURES INTO THE LOW TO MID 70S NORTH...LOW 80S SOUTH. HIGH
PRESSURE MOVES IN TUESDAY NIGHT WITH LOWS UPPER 30S WEST...UPPER 40S
EAST. PRECIPITATION CHANCES INCREASE TUESDAY NIGHT AS UPPER TROUGH
MOVES ACROSS THE AREA. NOT TERRIBLY EXCITED ABOUT THUNDER CHANCES
GIVEN LACK OF INSTABILITY AND WEAK MID LEVEL LAPSE RATES.
WEDNESDAY...UPPER TROUGH SLOWLY MOVES EAST ALLOWING SOME WARMER AIR
TO RETURN TO THE WESTERN 1/3 OF THE AREA. HIGH TEMPERATURES WELL
BELOW NORMAL WITH LOW TO MID 50S. LOWS WEDNESDAY NIGHT IN THE LOW TO
MID 30S. NORMALLY COLDER LOCATIONS MAY SEE TEMPERATURES AT OR
SLIGHTLY BELOW FREEZING. WILL CONTINUE WITH SMALL CHANCES FOR RAIN
SHOWERS DURING THE DAY AS UPPER WAVES AND PROXIMITY TO UPPER JET
MOVE QUICKLY THROUGH THE STEEP NORTHWEST FLOW ALOFT. DRY CONDITIONS
EXPECTED WEDNESDAY NIGHT.
THURSDAY-FRIDAY...DRY. TEMPERATURES SLOWLY WARM THROUGH THE PERIOD
WITH HIGHS THURSDAY AROUND 60...65 TO 70 FRIDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1140 PM MDT FRI APR 26 2013
VERY DIFFERENT AIRMASS IN PLACE ACROSS THE AREA TONIGHT WITH DRY
AIR ACROSS THE NORTHWEST AND MUCH MORE HUMID AIR MOVING INTO
EASTERN HALF OF THE FORECAST AREA. OBSERVED SOUNDINGS AT 00Z
SUGGEST THAT HUMIDITY PROFILES ARE FAVORABLE FOR FOG
FORMATION...WITH MAIN CONCERN BEING WHERE DIVIDING LINE BETWEEN
THESE TWO AIR MASSES WILL BE OVERNIGHT. CONFIDENCE IN FOG MUCH
HIGHER AT MCK THAN GLD...BUT EVEN THEN MAJORITY OF GUIDANCE
SUGGEST WINDS WILL SHIFT TO THE WEST AND KEEP FOG TO THE SOUTH AND
EAST OF THE AREA. FOR THE TIME BEING...THINK KEEPING OPERATIONALLY
SIGNIFICANT VISBY RESTRICTIONS WARRANTED FOR THE TIME BEING BUT
CONFIDENCE NOT HIGH ENOUGH FOR WIDESPREAD IFR/LIFR VISBYS.
OTHERWISE....VFR CONDITIONS EXPECTED AFTER 15Z.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR KSZ003-004-
014>016-028-029-042.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JRM
SHORT TERM...DR
LONG TERM...99
AVIATION...JRM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1149 PM MDT FRI APR 26 2013
.UPDATE...
ISSUED AT 827 PM MDT FRI APR 26 2013
JUST COMPLETED AN UPDATE. MAIN CHANGE WAS TO INTRODUCE FOG FOR
TONIGHT INTO MID MORNING ON SATURDAY. DDC SOUNDING AND SURFACE
OBSERVATIONS WOULD INDICATE A RATHER MOIST TO OUR SOUTH. DEWPOINTS
HAVE BEEN INCREASING AND PUSHING FARTHER WEST THAN ANYTHING
INDICATES. THIS IS A RESULT OF MODELS HANDLING THE WIND/PRESSURE
FIELD POORLY AS WELL. RUC AND HRRR APPEAR TO BE CATCHING ALL THIS
FAIRLY WELL AND USED AS THE BASIS FOR THE UPDATE. ALSO ADJUSTED
SKY COVER UP A LITTLE AND RAISED THE MINS AS WELL.
UPDATE ISSUED AT 624 PM MDT FRI APR 26 2013
LET THE RED FLAG WARNING EXPIRE. PER LATEST OBSERVATIONS INCREASED
CLOUD COVER AND ADJUSTED DEWPOINTS DOWN.
&&
.SHORT TERM...(THIS AFTERNOON THROUGH SATURDAY)
ISSUED AT 139 PM MDT FRI APR 26 2013
H5 TROUGH AXIS CURRENTLY EXTENDS ACROSS WESTERN KS...WITH H7
CLOSED CENTER OVER SW KS NEAR 0K PANHANDLE. FRONTOGENETICAL FORCING
ALONG NW EXTENT OF H7 LOW HAS COMBINED WITH ELEVATED INSTABILITY
TO PRODUCE SHOWERS AND THUNDERSTORMS OVER PARTS OF SW KS...WITH
THE EDGE OF THIS ACTIVITY JUST SOUTHEAST OF OUR CWA BORDER. SHORT
RANGE GUIDANCE KEEPS THIS ACTIVITY SOUTH AND EAST OF OUR CWA AS
THE H5/H7 TROUGH SHIFTS EAST THIS AFTERNOON AND EVENING. THERE
HAVE BEEN LIGHT RADAR RETURNS OVER OUR SOUTHEASTERN CWA...HOWEVER
WITH MUCH DRIER AIR UNDERCUTTING THE NORTHERN EDGE OF THIS ACIDITY
AND SUBSIDENCE MOVING IN FROM THE NORTHWEST I AM SKEPTICAL THAT WE
WILL SEE MUCH MORE THAN ISOLATED SHOWERS THIS AFTERNOON.
A SURFACE TROUGH AXIS IS CURRENTLY CENTERED ALONG A LINE FROM JUST
EAST OF MCCOOK TO THE SOUTHWEST KS/CO BORDER. WEST OF THIS...VERY
GOOD MIXING ASSOCIATED WITH A DEEP DRY ADIABATIC LAYER (TO ABOUT
700MB) HAS LED TO VERY WARM/DRY CONDITIONS AND GUSTY WINDS MIXING
TO THE SURFACE. RED FLAG WARNING WAS ISSUED IN RESPONSE TO RH
VALUES FALLING TO 10-20% WITH GUSTS TO 30 MPH. AS THIS SURFACE
TROUGH SHIFTS EAST THIS AFTERNOON AND HIGH PRESSURE BUILDS INTO
NORTHEAST COLORADO THE GRADIENT WILL BEGIN TO WEAKEN...AND WINDS
SHOULD DECREASE SOME. I COULD SEE ENDING THE RFW EARLY FOR WESTERN
LOCATIONS...BUT WE SHOULD STILL SEE ABOUT 3HR OF RFW CONDITIONS
BEFORE ALL IS SAID AND DONE.
ANOTHER VERY WARM DAY IS EXPECTED SATURDAY...AND IF HIGH
TEMPERATURES TODAY ARE ANY INDICATION WE SHOULD SEE WIDESPREAD
HIGHS IN THE UPPER 70S/LOW 80S...POSSIBLY WARMER. WE SHOULD ALSO
SEE RH VALUES DROP TO WITHIN RFW CRITERIA...HOWEVER WINDS ALOFT
ARE MUCH LIGHTER...SO I AM NOT EXPECTING A REPEAT OF THIS
AFTERNOON REGARDING FIRE WEATHER.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 210 PM MDT FRI APR 26 2013
SATURDAY NIGHT-MONDAY...DRY. GENERALLY CLEAR THROUGH SUNDAY WITH AN
INCREASE IN MID AND HIGH LEVEL CLOUDS SUNDAY NIGHT AS A WEAK WEATHER
SYSTEM MOVES THROUGH UPPER W/NW FLOW ALOFT. BIGGER STORY WILL BE THE
VERY WARM TEMPERATURES.
HIGH TEMPERATURES SUNDAY 75 TO 80 IN FAR EASTERN COLORADO...LOW TO
MID 80S ELSEWHERE. FOR MONDAY 850 TEMPERATURES FROM GFS/NAM/ECMWF
AVERAGE A FEW DEGREES WARMER. DISCREPANCIES SHOW UP WITH REGARD TO
850 THERMAL AXIS. GFS/ECMWF INDICATING LESS AGGRESSIVE WARMING ACROSS
THE EASTERN 1/3 OF THE AREA WHILE NAM/SREF ARE SEVERAL DEGREES
WARMER. THIS DISCREPANCY RESULTS IN A SIGNIFICANT DIFFERENCE IN
TEMPERATURE AS THE COOLER SOLUTION WOULD SUGGEST HIGHS GENERALLY IN
THE MID TO UPPER 80S (WEST TO EAST) WHILE THE WARMER SOLUTIONS WOULD
SUGGEST MID 80S TO MID 90S (WEST TO EAST). IF THE WARMER SOLUTION
VERIFIES RECORD HIGH TEMPERATURES WOULD BE REACHED OR TIED JUST
ABOUT EVERYWHERE. WITH A SOUTHEAST TO SOUTH COMPONENT TO THE SFC
WIND EXPECTED DURING THE DAY WILL TREND TOWARD THE COOLER SOLUTION
WHICH STILL PRODUCES HIGHS IN THE 80S...MUCH ABOVE NORMAL FOR MANY.
TUESDAY...COLD FRONT MOVES THROUGH DURING THE DAY LOWERING AFTERNOON
TEMPERATURES INTO THE LOW TO MID 70S NORTH...LOW 80S SOUTH. HIGH
PRESSURE MOVES IN TUESDAY NIGHT WITH LOWS UPPER 30S WEST...UPPER 40S
EAST. PRECIPITATION CHANCES INCREASE TUESDAY NIGHT AS UPPER TROUGH
MOVES ACROSS THE AREA. NOT TERRIBLY EXCITED ABOUT THUNDER CHANCES
GIVEN LACK OF INSTABILITY AND WEAK MID LEVEL LAPSE RATES.
WEDNESDAY...UPPER TROUGH SLOWLY MOVES EAST ALLOWING SOME WARMER AIR
TO RETURN TO THE WESTERN 1/3 OF THE AREA. HIGH TEMPERATURES WELL
BELOW NORMAL WITH LOW TO MID 50S. LOWS WEDNESDAY NIGHT IN THE LOW TO
MID 30S. NORMALLY COLDER LOCATIONS MAY SEE TEMPERATURES AT OR
SLIGHTLY BELOW FREEZING. WILL CONTINUE WITH SMALL CHANCES FOR RAIN
SHOWERS DURING THE DAY AS UPPER WAVES AND PROXIMITY TO UPPER JET
MOVE QUICKLY THROUGH THE STEEP NORTHWEST FLOW ALOFT. DRY CONDITIONS
EXPECTED WEDNESDAY NIGHT.
THURSDAY-FRIDAY...DRY. TEMPERATURES SLOWLY WARM THROUGH THE PERIOD
WITH HIGHS THURSDAY AROUND 60...65 TO 70 FRIDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1140 PM MDT FRI APR 26 2013
VERY DIFFERENT AIRMASS IN PLACE ACROSS THE AREA TONIGHT WITH DRY
AIR ACROSS THE NORTHWEST AND MUCH MORE HUMID AIR MOVING INTO
EASTERN HALF OF THE FORECAST AREA. OBSERVED SOUNDINGS AT 00Z
SUGGEST THAT HUMIDITY PROFILES ARE FAVORABLE FOR FOG
FORMATION...WITH MAIN CONCERN BEING WHERE DIVIDING LINE BETWEEN
THESE TWO AIR MASSES WILL BE OVERNIGHT. CONFIDENCE IN FOG MUCH
HIGHER AT MCK THAN GLD...BUT EVEN THEN MAJORITY OF GUIDANCE
SUGGEST WINDS WILL SHIFT TO THE WEST AND KEEP FOG TO THE SOUTH AND
EAST OF THE AREA. FOR THE TIME BEING...THINK KEEPING OPERATIONALLY
SIGNIFICANT VISBY RESTRICTIONS WARRANTED FOR THE TIME BEING BUT
CONFIDENCE NOT HIGH ENOUGH FOR WIDESPREAD IFR/LIFR VISBYS.
OTHERWISE....VFR CONDITIONS EXPECTED AFTER 15Z.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...BULLER
SHORT TERM...DR
LONG TERM...99
AVIATION...JRM
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1245 AM CDT SAT APR 27 2013
...UPDATED FOR AVIATION...
.UPDATE...
ISSUED AT 1212 AM CDT SAT APR 27 2013
A DENSE FOG ADVISORY HAS BEEN POSTED FOR MOST OF THE REGION BETWEEN
HIGHWAYS 83 AND 183. WIDESPREAD 1 TO 3 DEGREE DEW POINT DEPRESSIONS
CHARACTERIZE THE BOUNDARY LAYER IN THIS REGION, WHILE THE FAR WEST
PERIPHERY FROM GARDEN CITY TO SCOTT CITY HAS ALREADY SEEN
VISIBILITIES DOWN TO 1/4 MILE OR LESS OVER THE LAST COUPLE OF HOURS.
WHILE THE WRF/NAM SOLUTIONS SHOW QUITE DIFFERENT SOLUTIONS, THE
HOURLY RAPID REFRESH MODEL EXPANDS DENSE FOG EASTWARD TO NEAR A HAYS
TO MINNEOLA LINE BY 12Z. GIVEN THE CURRENT TRENDS, THIS SEEM LIKE
THE MOST PROBABLE CASE.
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 210 PM CDT FRI APR 26 2013
SHOWERS AND A FEW ISOLATED THUNDERSTORMS WILL LINGER ACROSS CENTRAL
KANSAS THIS EVENING AS AN UPPER LEVEL SHORTWAVE TRANSITIONS EAST
ACROSS THE CENTRAL PLAINS THROUGH SATURDAY MORNING. PRECIP IS
EXPECTED TO DISSIPATE WEST TO EAST THROUGH LATE THIS EVENING.
WIDESPREAD SEVERE WEATHER IS NOT EXPECTED WITH LIMITED INSTABILITY
PRESENT ACROSS THE AREA. OTHERWISE, DRY AND TRANQUIL CONDITIONS
ARE EXPECTED LATE TONIGHT THROUGH SATURDAY AS THE UPPER LEVEL
FEATURE KICKS FURTHER OFF TO THE EAST WHILE DRIER AIR NEAR THE
SURFACE FILTERS SOUTH INTO WESTERN KANSAS. TEMPERATURES WILL BE
SLIGHTLY COOLER TONIGHT AS A LOW LEVEL NORTHERLY FLOW SETS UP
ACROSS WESTERN KANSAS BEHIND A SURFACE LOW DROPPING SOUTHEAST INTO
NORTH TEXAS. WITH SURFACE DEWPOINTS DROPPING INTO THE 30S(F)
ACROSS WEST CENTRAL KANSAS TO THE 40S(F) ELSEWHERE, LOOK FOR LOWS
MAINLY DOWN INTO THE 40S(F) ACROSS CENTRAL AND SOUTHWEST KANSAS
WITH THE UPPER 30S(F) POSSIBLE IN WEST CENTRAL KANSAS. FOR
SATURDAY, THE SURFACE LOW IS PROJECTED TO PUSH EAST FROM NORTH
TEXAS INTO THE ARK-LA-TEX REGION HELPING TO TURN THE NORTHERLY LOW
LEVEL FLOW MORE NORTHEASTERLY BY SATURDAY AFTERNOON. THE SAME
GENERAL AIR MASS IS EXPECTED TO REMAIN IN PLACE WITH H85
TEMPERATURES RANGING FROM AROUND 10C IN CENTRAL KANSAS TO NEAR 18C
IN FAR SOUTHWEST KANSAS. HOWEVER, WITH DECREASING CLOUDS LOOK FOR
WIDESPREAD 70S(F) FOR HIGHS ACROSS CENTRAL AND SOUTHWEST KANSAS.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 333 PM CDT FRI APR 26 2013
THE ECMWF, GFS AND GEM MODELS HAVE ALL CHANGED A LITTLE SINCE
YESTERDAY. THEY ALL KEEP VERY WARM AIR ADVECTING STRONGLY NORTHWARD
SUNDAY, MONDAY AND EVEN MORE SO ON TUESDAY, BEFORE A STRONG COLD
FRONT WILL PLOW SOUTHEASTWARD THROUGH WESTERN KANSAS TUESDAY NIGHT
AND WEDNESDAY. THE UPPER LEVEL WAVE ASSOCIATED WITH THIS FRONT WILL
BE SOMEWHAT DELAYED, CROSSING WESTERN KANSAS WEDNESDAY INTO
WEDNESDAY NIGHT. FOR THIS REASON, AT THIS TIME, I DO NOT EXPECT VERY
MUCH SEVERE WEATHER TO DEVELOP, AND MORE LIKE A ROUND OF ELEVATED
SHOWERS AND THUNDERSTORMS. ALSO, DUE TO THE TIMING OF THE FASTER
MOVING FRONT AND THE DELAYED UPPER LEVEL WAVE, NO PRECIPITATION
CHANCES ARE IN OUR FORECAST AREA FOR TUESDAY AFTERNOON. THE
HIGHEST CHANCES FOR SHOWERS AND THUNDERSTORMS WILL BE ON
WEDNESDAY, RANGING FROM 30 PERCENT NORTH OF I-70, TO 50 PERCENT
DOWN SOUTHEAST IN THE PRATT TO COLDWATER AREAS. THERE WILL BE 20
PERCENT POPS IN FOR WEDNESDAY NIGHT, BUT JUST IN OUR EASTERN ZONES
MAINLY EAST OF HIGHWAY 283. QPF DOES NOT LOOK TOO SIGNIFICANT
WITH THIS SYSTEM, SO THE DROUGHT WILL CONTINUE AND PERSIST. 850
TEMPS FROM BOTH THE ECMWF AND GFS MODELS SHOW +18C AIR IN OUR
EASTERN CWA AND AS MUCH AS +24C ALONG OUR WESTERN BOUNDARY WITH
COLORADO FOR SUNDAY. BY MONDAY, THE 850MB ATMOSPHERE WILL WARM TO
NEAR +20C ALONG THE PRATT AND KINGMAN LINE, AND TO THE 24C TO 25C
DEGREE RANGE IN THE WEST NEAR COLORADO. THE WARMEST DAY MAY BE
TUESDAY, ESPECIALLY IN OUR SOUTHWEST CORNER NEAR ELKHART AND
LIBERAL, WHERE TEMPERATURES MAY SOAR INTO THE MIDDLE 80S.
JUST HOW FAST THE COLD FRONT COMES DOWN TUESDAY NIGHT IS HANDLED
DIFFERENTLY BY THE LONG RANGE MODELS. THE GFS IS THE FASTEST, AND
THE ECMWF IS SLOWER. FOR NOW, THE CONSENSUS WAS TO GO WITH THE
SLOWER EC MODEL. EITHER WAY, WEDNESDAY LOOKS CONSIDERABLY COLDER
THAN TUESDAY, BY ABOUT 19F TO 25F DEGREES. FOR BOTH WEDNESDAY AND
THURSDAY, WE WILL BE IN THE GRIP OF A COLD HIGH PRESSURE SYSTEM.
HIGHS WILL ONLY BE IN THE UPPER 50S TO LOWER 60S. THE LOWER LEVEL
FLOW WILL RETURN TO THE SOUTH BY FRIDAY, AND FRIDAY SHOULD WARM TO
THE MID 60S TO LOWER 70S. MINIMUM TEMPERATURES WILL RANGE FROM 45F
TO 55F DEGREES SUNDAY AND MONDAY, FROM 50F TO 60F DEGREES TUESDAY,
AND BACK TO THE 45F TO 55F DEGREE RANGE WEDNESDAY. BOTH THURSDAY
AND FRIDAY MORNINGS LOOK COLD, WITH LOWS DIPPING DOWN INTO THE MID
30S TO NEAR 40F DEGREES.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 210 PM CDT FRI APR 26 2013
SHOWERS AND A FEW ISOLATED THUNDERSTORMS WILL LINGER ACROSS CENTRAL
KANSAS THIS EVENING AS AN UPPER LEVEL SHORTWAVE TRANSITIONS EAST
ACROSS THE CENTRAL PLAINS THROUGH SATURDAY MORNING. PRECIP IS
EXPECTED TO DISSIPATE WEST TO EAST THROUGH LATE THIS EVENING.
WIDESPREAD SEVERE WEATHER IS NOT EXPECTED WITH LIMITED INSTABILITY
PRESENT ACROSS THE AREA. OTHERWISE, DRY AND TRANQUIL CONDITIONS
ARE EXPECTED LATE TONIGHT THROUGH SATURDAY AS THE UPPER LEVEL
FEATURE KICKS FURTHER OFF TO THE EAST WHILE DRIER AIR NEAR THE
SURFACE FILTERS SOUTH INTO WESTERN KANSAS. TEMPERATURES WILL BE
SLIGHTLY COOLER TONIGHT AS A LOW LEVEL NORTHERLY FLOW SETS UP
ACROSS WESTERN KANSAS BEHIND A SURFACE LOW DROPPING SOUTHEAST INTO
NORTH TEXAS. WITH SURFACE DEWPOINTS DROPPING INTO THE 30S(F)
ACROSS WEST CENTRAL KANSAS TO THE 40S(F) ELSEWHERE, LOOK FOR LOWS
MAINLY DOWN INTO THE 40S(F) ACROSS CENTRAL AND SOUTHWEST KANSAS
WITH THE UPPER 30S(F) POSSIBLE IN WEST CENTRAL KANSAS. FOR
SATURDAY, THE SURFACE LOW IS PROJECTED TO PUSH EAST FROM NORTH
TEXAS INTO THE ARK-LA-TEX REGION HELPING TO TURN THE NORTHERLY LOW
LEVEL FLOW MORE NORTHEASTERLY BY SATURDAY AFTERNOON. THE SAME
GENERAL AIR MASS IS EXPECTED TO REMAIN IN PLACE WITH H85
TEMPERATURES RANGING FROM AROUND 10C IN CENTRAL KANSAS TO NEAR 18C
IN FAR SOUTHWEST KANSAS. HOWEVER, WITH DECREASING CLOUDS LOOK FOR
WIDESPREAD 70S(F) FOR HIGHS ACROSS CENTRAL AND SOUTHWEST KANSAS.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 333 PM CDT FRI APR 26 2013
THE ECMWF, GFS AND GEM MODELS HAVE ALL CHANGED A LITTLE SINCE
YESTERDAY. THEY ALL KEEP VERY WARM AIR ADVECTING STRONGLY NORTHWARD
SUNDAY, MONDAY AND EVEN MORE SO ON TUESDAY, BEFORE A STRONG COLD
FRONT WILL PLOW SOUTHEASTWARD THROUGH WESTERN KANSAS TUESDAY NIGHT
AND WEDNESDAY. THE UPPER LEVEL WAVE ASSOCIATED WITH THIS FRONT WILL
BE SOMEWHAT DELAYED, CROSSING WESTERN KANSAS WEDNESDAY INTO
WEDNESDAY NIGHT. FOR THIS REASON, AT THIS TIME, I DO NOT EXPECT VERY
MUCH SEVERE WEATHER TO DEVELOP, AND MORE LIKE A ROUND OF ELEVATED
SHOWERS AND THUNDERSTORMS. ALSO, DUE TO THE TIMING OF THE FASTER
MOVING FRONT AND THE DELAYED UPPER LEVEL WAVE, NO PRECIPITATION
CHANCES ARE IN OUR FORECAST AREA FOR TUESDAY AFTERNOON. THE
HIGHEST CHANCES FOR SHOWERS AND THUNDERSTORMS WILL BE ON
WEDNESDAY, RANGING FROM 30 PERCENT NORTH OF I-70, TO 50 PERCENT
DOWN SOUTHEAST IN THE PRATT TO COLDWATER AREAS. THERE WILL BE 20
PERCENT POPS IN FOR WEDNESDAY NIGHT, BUT JUST IN OUR EASTERN ZONES
MAINLY EAST OF HIGHWAY 283. QPF DOES NOT LOOK TOO SIGNIFICANT
WITH THIS SYSTEM, SO THE DROUGHT WILL CONTINUE AND PERSIST. 850
TEMPS FROM BOTH THE ECMWF AND GFS MODELS SHOW +18C AIR IN OUR
EASTERN CWA AND AS MUCH AS +24C ALONG OUR WESTERN BOUNDARY WITH
COLORADO FOR SUNDAY. BY MONDAY, THE 850MB ATMOSPHERE WILL WARM TO
NEAR +20C ALONG THE PRATT AND KINGMAN LINE, AND TO THE 24C TO 25C
DEGREE RANGE IN THE WEST NEAR COLORADO. THE WARMEST DAY MAY BE
TUESDAY, ESPECIALLY IN OUR SOUTHWEST CORNER NEAR ELKHART AND
LIBERAL, WHERE TEMPERATURES MAY SOAR INTO THE MIDDLE 80S.
JUST HOW FAST THE COLD FRONT COMES DOWN TUESDAY NIGHT IS HANDLED
DIFFERENTLY BY THE LONG RANGE MODELS. THE GFS IS THE FASTEST, AND
THE ECMWF IS SLOWER. FOR NOW, THE CONSENSUS WAS TO GO WITH THE
SLOWER EC MODEL. EITHER WAY, WEDNESDAY LOOKS CONSIDERABLY COLDER
THAN TUESDAY, BY ABOUT 19F TO 25F DEGREES. FOR BOTH WEDNESDAY AND
THURSDAY, WE WILL BE IN THE GRIP OF A COLD HIGH PRESSURE SYSTEM.
HIGHS WILL ONLY BE IN THE UPPER 50S TO LOWER 60S. THE LOWER LEVEL
FLOW WILL RETURN TO THE SOUTH BY FRIDAY, AND FRIDAY SHOULD WARM TO
THE MID 60S TO LOWER 70S. MINIMUM TEMPERATURES WILL RANGE FROM 45F
TO 55F DEGREES SUNDAY AND MONDAY, FROM 50F TO 60F DEGREES TUESDAY,
AND BACK TO THE 45F TO 55F DEGREE RANGE WEDNESDAY. BOTH THURSDAY
AND FRIDAY MORNINGS LOOK COLD, WITH LOWS DIPPING DOWN INTO THE MID
30S TO NEAR 40F DEGREES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1242 AM CDT SAT APR 27 2013
DENSE FOG IS BECOMING MORE WIDESPREAD ACROSS SOUTHWEST KANSAS EARLY
THIS MORNING. BASED ON THE CURRENT TRENDS AND THE LAST HRRR MODEL AS
WELL AS TRENDS FROM THE LOCAL GFS MOS GUIDANCE, SEVERAL HOURS OF
LIFR/VLIFR VISIBILITIES IN DENSE FOG IS EXPECTED THROUGH SATURDAY
MORNING AT EACH OF THE AREA TERMINALS.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 51 82 54 83 / 0 0 10 10
GCK 50 82 53 82 / 0 0 10 0
EHA 50 82 54 83 / 10 0 10 0
LBL 51 82 55 84 / 10 0 10 0
HYS 50 81 54 80 / 0 0 10 10
P28 50 79 56 82 / 0 10 10 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR KSZ030-031-
043>046-063>065-077>079-087-088.
&&
$$
UPDATE...RUSSELL
SHORT TERM...JJOHNSON
LONG TERM...BURKE
AVIATION...RUSSELL
AREA FORECAST DISCUSSION
NWS GOODLAND KS
837 PM MDT FRI APR 26 2013
.UPDATE...
ISSUED AT 827 PM MDT FRI APR 26 2013
JUST COMPLETED AN UPDATE. MAIN CHANGE WAS TO INTRODUCE FOG FOR
TONIGHT INTO MID MORNING ON SATURDAY. DDC SOUNDING AND SURFACE
OBSERVATIONS WOULD INDICATE A RATHER MOIST TO OUR SOUTH. DEWPOINTS
HAVE BEEN INCREASING AND PUSHING FARTHER WEST THAN ANYTHING
INDICATES. THIS IS A RESULT OF MODELS HANDLING THE WIND/PRESSURE
FIELD POORLY AS WELL. RUC AND HRRR APPEAR TO BE CATCHING ALL THIS
FAIRLY WELL AND USED AS THE BASIS FOR THE UPDATE. ALSO ADJUSTED
SKY COVER UP A LITTLE AND RAISED THE MINS AS WELL.
UPDATE ISSUED AT 624 PM MDT FRI APR 26 2013
LET THE RED FLAG WARNING EXPIRE. PER LATEST OBSERVATIONS INCREASED
CLOUD COVER AND ADJUSTED DEWPOINTS DOWN.
&&
.SHORT TERM...(THIS AFTERNOON THROUGH SATURDAY)
ISSUED AT 139 PM MDT FRI APR 26 2013
H5 TROUGH AXIS CURRENTLY EXTENDS ACROSS WESTERN KS...WITH H7
CLOSED CENTER OVER SW KS NEAR 0K PANHANDLE. FRONTOGENETICAL FORCING
ALONG NW EXTENT OF H7 LOW HAS COMBINED WITH ELEVATED INSTABILITY
TO PRODUCE SHOWERS AND THUNDERSTORMS OVER PARTS OF SW KS...WITH
THE EDGE OF THIS ACTIVITY JUST SOUTHEAST OF OUR CWA BORDER. SHORT
RANGE GUIDANCE KEEPS THIS ACTIVITY SOUTH AND EAST OF OUR CWA AS
THE H5/H7 TROUGH SHIFTS EAST THIS AFTERNOON AND EVENING. THERE
HAVE BEEN LIGHT RADAR RETURNS OVER OUR SOUTHEASTERN CWA...HOWEVER
WITH MUCH DRIER AIR UNDERCUTTING THE NORTHERN EDGE OF THIS ACIDITY
AND SUBSIDENCE MOVING IN FROM THE NORTHWEST I AM SKEPTICAL THAT WE
WILL SEE MUCH MORE THAN ISOLATED SHOWERS THIS AFTERNOON.
A SURFACE TROUGH AXIS IS CURRENTLY CENTERED ALONG A LINE FROM JUST
EAST OF MCCOOK TO THE SOUTHWEST KS/CO BORDER. WEST OF THIS...VERY
GOOD MIXING ASSOCIATED WITH A DEEP DRY ADIABATIC LAYER (TO ABOUT
700MB) HAS LED TO VERY WARM/DRY CONDITIONS AND GUSTY WINDS MIXING
TO THE SURFACE. RED FLAG WARNING WAS ISSUED IN RESPONSE TO RH
VALUES FALLING TO 10-20% WITH GUSTS TO 30 MPH. AS THIS SURFACE
TROUGH SHIFTS EAST THIS AFTERNOON AND HIGH PRESSURE BUILDS INTO
NORTHEAST COLORADO THE GRADIENT WILL BEGIN TO WEAKEN...AND WINDS
SHOULD DECREASE SOME. I COULD SEE ENDING THE RFW EARLY FOR WESTERN
LOCATIONS...BUT WE SHOULD STILL SEE ABOUT 3HR OF RFW CONDITIONS
BEFORE ALL IS SAID AND DONE.
ANOTHER VERY WARM DAY IS EXPECTED SATURDAY...AND IF HIGH
TEMPERATURES TODAY ARE ANY INDICATION WE SHOULD SEE WIDESPREAD
HIGHS IN THE UPPER 70S/LOW 80S...POSSIBLY WARMER. WE SHOULD ALSO
SEE RH VALUES DROP TO WITHIN RFW CRITERIA...HOWEVER WINDS ALOFT
ARE MUCH LIGHTER...SO I AM NOT EXPECTING A REPEAT OF THIS
AFTERNOON REGARDING FIRE WEATHER.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 210 PM MDT FRI APR 26 2013
SATURDAY NIGHT-MONDAY...DRY. GENERALLY CLEAR THROUGH SUNDAY WITH AN
INCREASE IN MID AND HIGH LEVEL CLOUDS SUNDAY NIGHT AS A WEAK WEATHER
SYSTEM MOVES THROUGH UPPER W/NW FLOW ALOFT. BIGGER STORY WILL BE THE
VERY WARM TEMPERATURES.
HIGH TEMPERATURES SUNDAY 75 TO 80 IN FAR EASTERN COLORADO...LOW TO
MID 80S ELSEWHERE. FOR MONDAY 850 TEMPERATURES FROM GFS/NAM/ECMWF
AVERAGE A FEW DEGREES WARMER. DISCREPANCIES SHOW UP WITH REGARD TO
850 THERMAL AXIS. GFS/ECMWF INDICATING LESS AGGRESSIVE WARMING ACROSS
THE EASTERN 1/3 OF THE AREA WHILE NAM/SREF ARE SEVERAL DEGREES
WARMER. THIS DISCREPANCY RESULTS IN A SIGNIFICANT DIFFERENCE IN
TEMPERATURE AS THE COOLER SOLUTION WOULD SUGGEST HIGHS GENERALLY IN
THE MID TO UPPER 80S (WEST TO EAST) WHILE THE WARMER SOLUTIONS WOULD
SUGGEST MID 80S TO MID 90S (WEST TO EAST). IF THE WARMER SOLUTION
VERIFIES RECORD HIGH TEMPERATURES WOULD BE REACHED OR TIED JUST
ABOUT EVERYWHERE. WITH A SOUTHEAST TO SOUTH COMPONENT TO THE SFC
WIND EXPECTED DURING THE DAY WILL TREND TOWARD THE COOLER SOLUTION
WHICH STILL PRODUCES HIGHS IN THE 80S...MUCH ABOVE NORMAL FOR MANY.
TUESDAY...COLD FRONT MOVES THROUGH DURING THE DAY LOWERING AFTERNOON
TEMPERATURES INTO THE LOW TO MID 70S NORTH...LOW 80S SOUTH. HIGH
PRESSURE MOVES IN TUESDAY NIGHT WITH LOWS UPPER 30S WEST...UPPER 40S
EAST. PRECIPITATION CHANCES INCREASE TUESDAY NIGHT AS UPPER TROUGH
MOVES ACROSS THE AREA. NOT TERRIBLY EXCITED ABOUT THUNDER CHANCES
GIVEN LACK OF INSTABILITY AND WEAK MID LEVEL LAPSE RATES.
WEDNESDAY...UPPER TROUGH SLOWLY MOVES EAST ALLOWING SOME WARMER AIR
TO RETURN TO THE WESTERN 1/3 OF THE AREA. HIGH TEMPERATURES WELL
BELOW NORMAL WITH LOW TO MID 50S. LOWS WEDNESDAY NIGHT IN THE LOW TO
MID 30S. NORMALLY COLDER LOCATIONS MAY SEE TEMPERATURES AT OR
SLIGHTLY BELOW FREEZING. WILL CONTINUE WITH SMALL CHANCES FOR RAIN
SHOWERS DURING THE DAY AS UPPER WAVES AND PROXIMITY TO UPPER JET
MOVE QUICKLY THROUGH THE STEEP NORTHWEST FLOW ALOFT. DRY CONDITIONS
EXPECTED WEDNESDAY NIGHT.
THURSDAY-FRIDAY...DRY. TEMPERATURES SLOWLY WARM THROUGH THE PERIOD
WITH HIGHS THURSDAY AROUND 60...65 TO 70 FRIDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 534 PM MDT FRI APR 26 2013
VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...BULLER
SHORT TERM...DR
LONG TERM...99
AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
230 PM MDT THU APR 25 2013
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 230 PM MDT THU APR 25 2013
EARLY AFTERNOON WV IMAGERY AND RUC ANALYSIS SHOW CLOSED LOW H5/H7
LOW OVER ARIZONA...WITH ENERGY AHEAD OF THIS FEATURE SPREADING NORTH
INTO WESTERN KS/EASTERN COLORADO. AT THE SURFACE A STRONG SURFACE
GRADIENT AS DEVELOPED IN RESPONSE TO SURFACE LOW DEEPENING OVER SOUTH
CENTRAL COLORADO.
WINDS GUSTS HAVE BEEN REPORTED THIS AFTERNOON IN THE 45-50 MPH
RANGE...AND RH VALUES HAVE DROPPED TO 15-17 PERCENT OVER EASTERN
PARTS OF THE CWA. CLOUD COVER COULD EVENTUALLY LIMIT
MIXING...HOWEVER WITH PEAK HEATING UNDERWAY I AM COMFORTABLE
KEEPING WIND ADVISORY AND RED FLAG WARNING IN PLACE WITH AFTERNOON
UPDATE.
CLOSED LOW OVER DESERT SW WILL EJECT OVER WESTERN KS TONIGHT INTO
EASTERN KS FRIDAY. WHILE H5 CENTER BECOMES MORE OF AN OPEN
WAVE...GUIDANCE IS INDICATING H7 CENTER REMAINING CLOSED AS IT
PASSES OVER KS. MODELS SHOW MID LEVEL FRONTOGENETICAL FORCING
OVERSPREADING OUR CWA THIS EVENING WITH POSSIBLE BAND FORMATION LATE
TONIGHT ON NW SIDE OF H7 LOW...POSSIBLY RESULTING IN BETTER RAIN
COVERAGE AND HIGHER RAIN TOTALS. THERE IS MINIMAL MU CAPE GENERALLY
LESS THAN 100 J/KG...HOWEVER GFS/NAM BOTH SHOW NEGATIVE THETA E
LAPSE RATES IN H8-H7 LAYER ASSOCIATED WITH MAIN AREA OF SHOWERS SO I
COULDNT RULE OUT A FEW WEAK THUNDERSTORMS WITH THIS ACTIVITY. HAVE
KEPT 50 POPS IN THE SOUTHEAST WHERE BETTER FORCING IS
ADVERTISED...WITH RAIN COMING TO AN END FOR MOSTLY LOCATIONS FRIDAY
MORNING. I KEPT SLIGHT CHANCE POPS LINGERING IN THE EASTERN PART OF
CWA TO ACCOUNT FOR POSSIBLE RAIN BAND LINGERING OVER NORTHCENTRAL
KS.
THERE WILL BE A WEAK COLD FRONT PASSING THROUGH THE CWA BY FRIDAY
MORNING...HOWEVER WITH CLEARING SKIES AND WAA IN THE AFTERNOON I
STILL EXPECT HIGHS FRIDAY TO REACH UPPER 60S/NEAR 70 IN THE WEST
(BASED ON MIXING THE LAST FEW DAYS). WARMING COULD BE LIMITED IN THE
EAST DUE TO CLOUDS/PRECIP POSSIBLY LINGERING.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 230 PM MDT THU APR 25 2013
FRIDAY NIGHT-SUNDAY...DRY WEATHER EXPECTED. WILL NEED TO WATCH
THE FAR EASTERN PORTIONS OF THE AREA FOR THUNDERSTORMS SATURDAY
AFTERNOON AS A SFC TROUGH MOVES THROUGH. THERE IS SOME WEAK
CONVERGENCE AND INSTABILITY ALONG THE WIND SHIFT WITH THIS
FEATURE...QUESTION RIGHT NOW IS HOW MUCH MOISTURE WILL BE
AVAILABLE. ANY THREAT FOR PRECIP SATURDAY AFTERNOON QUICKLY
DECREASES SATURDAY NIGHT AS THE SFC TROUGH MOVES EAST AND OUT OF
THE AREA. FOR SUNDAY GENERALLY SUNNY...MAY SEE SOME CIRRUS MOVE
DOWN FROM THE NORTH. LOWS FRIDAY NIGHT MID 30S TO LOW 40S WITH
UPPER 30S TO MID 40S SATURDAY NIGHT. HIGHS SATURDAY IN THE 70S
WITH MID 70S (WEST) TO MID 80S (EAST) SUNDAY.
SUNDAY NIGHT-MONDAY...COLD FRONT BRIEFLY PUSHES SOUTHWEST ACROSS
THE AREA SUNDAY NIGHT BEFORE RETREATING OUT OF THE AREA. NEAR OR
SLIGHTLY COOLER READINGS COMPARED TO SUNDAY EXPECTED ACROSS THE
NORTHEAST AND EAST WHERE PROXIMITY TO DEPARTING HIGH WILL BE FELT
MOST. TO THE WEST SIMILAR TO SLIGHTLY WARMER READINGS COMPARED TO
SUNDAY. LOWS MID 40S TO LOW 50S (WEST TO EAST) WITH HIGHS 75 TO 80
MONDAY.
MONDAY NIGHT-TUESDAY NIGHT...SFC TROUGH ACROSS THE AREA MONDAY NIGHT
WITH COLD FRONT MOVING THROUGH FROM THE NORTH TUESDAY. BREEZY NORTH
TO NORTHEAST WINDS TUESDAY NIGHT BEHIND THE FRONT. LOWS MONDAY NIGHT
MID 40S TO MID 50S (WEST TO EAST) WITH MID 30S TO MID 40S (WEST TO
EAST) TUESDAY NIGHT. HIGHS TUESDAY LOW 70S TO AROUND 80 (NORTH TO
SOUTH). SHOWERS AND A FEW THUNDERSTORMS POSSIBLE ACROSS THE EAST
TUESDAY AFTERNOON AHEAD OF THE FRONT. POST FRONTAL STABLE AIR MOVES
IN TUESDAY NIGHT. REMOVED MENTION OF THUNDERSTORMS BUT STILL HAVE A
CHANCE OF LIGHT RAIN.
WEDNESDAY-WEDNESDAY NIGHT...BREEZY NORTH WINDS TO CONTINUE ACROSS
THE EASTERN HALF OF THE AREA THROUGH THE DAY. SFC HIGH REMAINS OVER
THE AREA WEDNESDAY NIGHT ALLOWING FOR NEAR TO SLIGHTLY BELOW NORMAL
LOW TEMPERATURES. HIGHS IN THE MID TO UPPER 50S WITH LOWS MID TO
UPPER 30S. LOW CHANCES FOR SOME LIGHT RAIN OR RAIN SHOWERS DURING
THE DAY DECREASING DURING THE NIGHT.
THURSDAY...WARMER TEMPERATURES EXPECTED TO RETURN TO THE AREA AS
UPPER RIDGING SLOWLY MOVES IN FROM THE WEST. HIGHS MID 50S TO LOW
60S. CONTINUED LOW CHANCE FOR SOME LIGHT RAIN ACROSS THE AREA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1126 AM MDT THU APR 25 2013
VFR CONDITIONS SHOULD PREVAIL AT BOTH KGLD AND KMCK THROUGH THE
TAF PERIOD. GUSTY WINDS THIS AFTERNOON AT BOTH TERMINALS SHOULD
DIMINISH AFTER SUNSET WITH WINDS SHIFTING TO THE W/NW BY FRIDAY
MORNING BEHIND WEAK COLD FRONT. UPPER LEVEL SYSTEM WILL BRING
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS SOUTH OF INTERSTATE
70 TONIGHT THROUGH FRIDAY MORNING. WHILE KGLD HAS A BETTER CHANCE
TO SEE A SHOWER...CONFIDENCE IS TOO LOW TO INCLUDE MORE THAN
VCSH AT THIS TIME.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...RED FLAG WARNING UNTIL 7 PM MDT /8 PM CDT/ THIS EVENING FOR
KSZ002>004-014>016-027>029-041-042.
WIND ADVISORY UNTIL 6 PM MDT /7 PM CDT/ THIS EVENING FOR
KSZ002>004-013>016-027>029-041-042.
CO...NONE.
NE...RED FLAG WARNING UNTIL 8 PM CDT THIS EVENING FOR NEZ080-081.
&&
$$
SHORT TERM...DR
LONG TERM...99
AVIATION...DR
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1155 AM CDT THU APR 25 2013
.UPDATE...
ISSUED AT 1155 AM CDT THU APR 25 2013
LATEST RAP AND NAM FORECAST SOUNDINGS SHOW THE BOUNDARY LAYER
MIXING TO NEAR 800MB. BECAUSE OF THIS HAVE BUMPED UP MAX TEMPS A
COUPLE DEGREES ALREADY...AND WE MAY END UP SEEING SOME PLACES WARM
TO AROUND 70 THIS AFTERNOON WITH GOOD INSOLATION.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 336 AM CDT THU APR 25 2013
ANOTHER COLD START CAN BE EXPECTED ACROSS THE REGION THIS MORNING
AS CLEAR SKIES UNDER THE AREA OF HIGH PRESSURE CAUSED TEMPERATURES
TO BOTTOM OUT IN LOW/MID 30S ACROSS MOST OF THE FORECAST AREA. WITH
THESE UNSEASONABLY COLD TEMPERATURES AND CALM WINDS IN PLACE...AREAS
OF FROST ARE EXPECTED THIS MORNING AND A FREEZE WARNING REMAINS IN
EFFECT THROUGH 9 AM THIS MORNING. TEMPERATURES ARE EXPECTED TO
QUICKLY MODERATE THROUGH THE DAY TODAY AS SOUTHERLY FLOW INCREASES
ACROSS THE REGION...WITH AFTERNOON HIGHS RISING TO WITHIN A FEW
DEGREES OF THE SEASONAL NORMALS WITH READINGS IN THE MIDDLE 60S.
THIS SOUTHERLY FLOW WILL PERSIST TODAY AND TONIGHT AS SURFACE HIGH
PRESSURE SHIFTS SOUTHEAST OF THE AREA.
EARLY THIS MORNING A SHORTWAVE TROUGH WAS LOCATED NEAR THE BAJA
PENINSULA. THIS TROUGH IS PROGGED TO TRACK NORTHEASTWARD THROUGH THE
FOUR CORNERS REGION THIS EVENING AND PROGRESS INTO THE CENTRAL
PLAINS EARLY FRIDAY MORNING. WITH THIS ADVANCING WAVE...HAVE
INCREASING POPS AFTER 06Z FRIDAY MORNING AS THERE IS A CHANCE FOR
RAIN SHOWERS TO DEVELOP ACROSS SOUTHERN KANSAS AND LIFT NORTHWARD
INTO THE FORECAST AREA. THE COMBINATION OF INCREASED CLOUD COVER
FROM THESE APPROACHING SHOWERS AND STEADY SOUTHERLY WINDS WILL HELP
KEEP OVERNIGHT TEMPERATURES RATHER WARM IN COMPARISON TO THE LAST
SEVERAL NIGHTS...WITH LOWS FRIDAY MORNING ONLY DROPPING INTO THE
MID/UPPER 40S.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 336 AM CDT THU APR 25 2013
A MID LEVEL TROUGH WILL MOVE ACROSS THE PLAINS FRIDAY THEN MOVE OFF
TO THE EAST BY EARLY SATURDAY. HIGHEST PROBABILITIES OF
PRECIPITATION CONTINUE TO BE OVER THE SOUTHERN TWO THIRDS OF THE CWA
FRIDAY THEN ACROSS THE EAST CENTRAL FRIDAY NIGHT AS THE SHORTWAVE
TROUGH PASSES THROUGH. HAVE ADJUSTED HIGH TEMPERATURES FRIDAY TO GO
A TAD COOLER OVER EAST CENTRAL AND PARTS OF NORTHEAST KANSAS. HIGHS
WILL STILL BE IN THE UPPER 50S. PRECIPITATION SHOULD COME TO AN END
FROM WEST TO EAST FRIDAY NIGHT.
CLEARING SKIES ON SATURDAY AS WELL AS RETURN FLOW ON THE BACK SIDE
OF THE SURFACE HIGH ACROSS NORTH CENTRAL KANSAS WILL SEND
TEMPERATURES INTO THE LOWER 70S WHILE THE EASTERN COUNTIES WILL SEE
HIGHS IN THE MID TO UPPER 60S.
MODELS ARE IN CONSENSUS DEVELOPING A RIDGE OVER EASTERN KANSAS
SUNDAY AND MONDAY. SENDING TEMPERATURES INTO THE MID TO UPPER
70S...AROUND 80 IN NORTH CENTRAL KANSAS SUNDAY AND MONDAY.
TEMPERATURES REMAIN IN THE 70S ON TUESDAY AHEAD OF AN APPROACHING
COLD FRONT. A DEEPENING UPPER LEVEL TROUGH WILL MOVE ACROSS THE
NORTHERN AND CENTRAL PLAINS TUESDAY AND WEDNESDAY. THIS WILL BRING
AN INCREASE IN PRECIPITATION CHANCES LATE TUESDAY INTO WEDNESDAY.
HIGH TEMPERATURES ON WEDNESDAY WILL COOL BACK INTO THE 60S BEHIND
THE COLD FRONT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1155 AM CDT THU APR 25 2013
VFR CONDITIONS SHOULD PREVAIL THROUGH THIS EVENING. AS UPPER WAVE
APPROACHES OVERNIGHT...CIGS WILL LOWER WITH MODEL GUIDANCE
SUGGESTING MVFR CIGS MOVING IN AROUND 18Z. SINCE THIS IS TOWARDS
THE END OF THE FORECAST PERIOD...HAVE OPTED TO LEAVE OUT OF THE
TAFS FOR NOW. INSTABILITY APPEARS TO BE PRETTY LIMITED SO WILL NOT
INCLUDE A MENTION OF TS IN THE TAFS AT THIS TIME. GIVEN THE
FORCING OF THE APPROACHING UPPER WAVE AND MOISTURE ADVECTION
THROUGH THE NIGHT...THINK SCATTERED TO WIDESPREAD SHOWERS WILL
AFFECT THE TERMINALS BY 12Z FRI.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...WOLTERS
SHORT TERM...HENNECKE
LONG TERM...53
AVIATION...WOLTERS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
348 AM CDT SAT APR 27 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 348 AM CDT SAT APR 27 2013
LOW PRESSURE WILL CONTINUE TO TRACK ACROSS SRN CANADA TODAY
PRODUCING SOUTHWEST WINDS AHEAD OF A NORTHWEST WIND SHIFT ACROSS
NORTHWEST NEBRASKA. LIGHT WINDS...DEEP VERTICAL MIXING...NEARLY FULL
SUN AND A STRONG THERMAL RIDGE SHOULD PRODUCE HIGHS AROUND 80. THE
RAP MODEL IS LEADING THE WAY WITH THIS FEATURE.
TONIGHT...WEST WINDS DEVELOP MAINTAINING A THERMAL RIDGE ACROSS THE
FORECAST AREA AND LOWS IN THE 30S TO NEAR 40.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 348 AM CDT SAT APR 27 2013
ANOTHER DAY OF WELL ABOVE
NORMAL TEMPERATURES WILL BE EXPECTED FOR SUNDAY AS GUIDANCE SUGGEST
H85 TEMPERATURES APPROACHING...IF NOT EXCEEDING 20C. THE WARM LOWER
LEVELS WILL ALLOW SURFACE TEMPERATURES TO CLIMB WELL INTO THE
70S...AND POSSIBLY LOW 80S ACROSS THE ENTIRE FORECAST AREA. WITH THE
WELL ABOVE CLIMO HIGHS EXPECTED...FIRE CONCERNS WILL ONCE AGAIN
FLIRT WITH CRITICAL THRESHOLDS BY EARLY AFTERNOON. THE LOWEST RH
READINGS ARE ANTICIPATED ACROSS OUR WESTERN AND SOUTHERN FIRE ZONES
WHERE A EASTWARD ADVANCING SURFACE TROUGH LOW PRESSURE WILL WORK IN
CONCERT WITH STRONG TROPOSPHERIC MIXING TO ALLOW FOR OCCASIONAL
WIND GUSTS AT OR NEAR 20KTS /SLIGHTLY BELOW RFW WIND THRESHOLD/.
WILL HOLD OFF ON ANY FIRE HEADLINE FOR NOW. INTO THE OVERNIGHT A
WEAK PERTURBATION WILL RAPIDLY ADVANCE THROUGH QUASI-ZONAL FLOW AND
BRING A CHANCE OF A SHOWER...OR POSSIBLY A THUNDERSTORM...TO
NORTHERN PORTIONS OF THE CWA. THE OPERATIONAL MODELS INDICATE
ENOUGH OMEGA FOR PRECIPITATION PRODUCTION FOR MUCH OF THE
CWA...HOWEVER BUFR PROXIMITY SOUNDINGS SUGGEST THE LOWER TROPOSPHERE
WILL REMAIN FAIRLY DRY...THUS WILL MAINTAIN SLIGHT TO LOW END CHANCE
POPS ACROSS OUR NORTH OVERNIGHT SUNDAY INTO MONDAY...GENERALLY TIED
TO THE STRONGEST OMEGA AND BEST LOWER LEVEL MOISTURE PROFILES...BUT
LEAVE THE SOUTHERN HALF OF THE CWA MAINLY DRY...WITH ONLY A MENTION
OF SPRINKLES. SIMILAR CONDITIONS ARE EXPECTED FOR MONDAY...WITH THE
POSSIBILITY OF SLIGHTLY WARMER TEMPERATURES AND GREATER GUSTS. RED
FLAG WARNINGS MAY BE NEEDED FOR THE AFTERNOON HOURS. DRY CONDITIONS
WILL PREVAIL INTO EARLY TUESDAY AS A LACK IN KINEMATIC FORCING
RETURNS ONCE AGAIN...HOWEVER PRECIPITATION CHANCES INCREASE DURING
THE AFTERNOON HOURS ON TUESDAY AS A BAROCLINIC ZONE AND ASSOCIATED
SHORTWAVE CROSSES THE REGION. BESIDES THE PRECIPITATION
CHANCES...TEMPERATURES WILL BE MARKEDLY COOLER FOR MIDWEEK BEHIND
THE PASSING FRONT. IN FACT...FREEZE CONCERNS MAY BE REALIZED EARLY
WEDNESDAY AS THE LONGER RANGE SOLUTIONS SUGGEST H85 TEMPERATURES
FALL SOME 20-25C...WHICH WOULD PROVIDE FOR LOWS IN THE UPPER
20S-LOWER 30S AND HIGHS MAINLY IN THE 50S THROUGH MIDWEEK. THE
LONGER RANGE SOLUTION REMAIN IN POOR AGREEMENT AND THUS CONFIDENCE
IS LOW FOR MIDWEEK AND BEYOND...BUT THE GENERAL IDEA REMAINS OF
BROAD CYCLONIC FLOW ACROSS THE CENTRAL CONUS THROUGH THE END OF THE
WORK WEEK...WITH SLOWLY MODERATING TEMPERATURES AND POSSIBLY A
CHANCE AT ADDITIONAL PRECIPITATION. BUT WITH THE LOW CONFIDENCE IN
THE EXTENDED FORECAST...WILL MAINTAIN A DRY FORECAST BEYOND
WEDNESDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1229 AM CDT SAT APR 27 2013
A WEAK SURFACE FRONT...MOSTLY A DEWPOINT CONTRAST...WILL BE THE
BOUNDARY OF SOME STRATUS AND/OR FOG IN PART OF CENTRAL AND SOUTH
CENTRAL NEBRASKA. AT THIS TIME...WE DO NOT EXPECT THOSE CONDITIONS
TO REACH BBW OR LBF. OTHERWISE...CEILINGS AND VISIBILITY WILL BE
UNRESTRICTED THROUGH TONIGHT AND INTO SATURDAY EVENING. WIND IS
EXPECTED TO SWING AROUND TO THE WEST AND SOUTHWEST MOST AREAS BUT
ARE STILL EXPECTED TO BE 12KT OR LOWER.
&&
.FIRE WEATHER...
ISSUED AT 348 AM CDT SAT APR 27 2013
A 75 PERCENT BLEND OF THE RAP AND 25 PERCENT OF THE REST OF THE
MODELS PRODUCES RELATIVE HUMIDITY BETWEEN 10 AND 20 PERCENT ACROSS
THE FCST AREA. ALL INDICATIONS ARE WINDS WILL BE WEAK AT LESS THAN
20 MPH.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...JACOBS
AVIATION...CDC
FIRE WEATHER...CDC
AREA FORECAST DISCUSSION
NWS HASTINGS NE
310 AM CDT SAT APR 27 2013
.UPDATE...
ISSUED AT 305 AM CDT SAT APR 27 2013
WITH MORE OBSERVATIONS QUICKLY TANKING TO 1/4 VISIBILITY...I
DECIDED TO GO COMPLETELY WITH THE HRRR SOLUTION AND INCLUDE ALL
BUT VALLEY COUNTY IN THE NORTH AND MITCHELL COUNTY IN THE SOUTH IN
THE DENSE FOG ADVISORY. WE SEEM TO BE IN THE MIDST OF A
CONVERGENCE AREA THAT IS PROMOTING FOG AND STRATUS DEVELOPMENT.
UPDATE ISSUED AT 1252 AM CDT SAT APR 27 2013
HIT THE FOG A LITTLE HARDER IN THIS UPDATE AS THE HRRR SEEMS TO BE
PICKING UP THE FOG TO THE SOUTH THE BEST. IF WE CONTINUE TO
TANK...WE COULD END UP WITH A DENSE FOG ADVISORY FOR A GOOD CHUNK
OF THE CWA THIS MORNING.
UPDATE ISSUED AT 902 PM CDT FRI APR 26 2013
WITH TEMPERATURES APPROACHING THE DEW POINTS ACROSS NORTH CENTRAL
KANSAS ALREADY THIS EVENING AND LIGHT SOUTHEASTERLY WINDS
ADVECTING ADDITIONAL MOISTURE NORTHWARD...DECIDED TO INSERT SOME
AREAS OF FOG INTO THE FORECAST DURING THE OVERNIGHT/EARLY MORNING
HOURS TOMORROW. 00Z HRRR IS VERY AGGRESSIVE WITH WIDESPREAD
VISIBILITIES DROPPING TO 1/4 SM...BUT SREF PROBS KEEP LOWER
VISIBILITIES SOUTH OF THE LOCAL AREA...SO WENT AHEAD WITH A
COMPROMISE...BRINGING FOG UP TO AROUND HIGHWAY 6 IN SOUTH CENTRAL
NEBRASKA OVERNIGHT. OTHERWISE...NO ADDITIONAL CHANGES MADE TO
PREVIOUS FORECAST AT THIS TIME.
UPDATE ISSUED AT 650 PM CDT FRI APR 26 2013
WENT AHEAD AND UPDATED THE FORECAST TO REMOVE THE SMALL CHANCES
FOR THUNDERSTORMS THIS EVENING AS WHILE THE SPC MESO ANALYSIS PAGE
INDICATES THERE ARE A COUPLE HUNDRED JOULES OF CAPE ACROSS OUR AREA
RIGHT NOW...THIS WILL DIMINISH OVER THE NEXT COUPLE OF HOURS AND
THUS FAR SHOWERS AND THUNDERSTORMS HAVE LACKED A TRIGGER FOR
DEVELOPMENT. OTHER THAN REMOVING THESE SMALL CHANCES FOR
PRECIPITATION...NO ADDITIONAL CHANGES WERE MADE TO THE PREVIOUS
FORECAST AT THIS TIME.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 320 PM CDT FRI APR 26 2013
MAIN FOCUS IN THE SHORT TERM WILL CENTER AROUND SLIGHT CHANCES FOR
THUNDERSTORMS AND HIGH TEMPERATURES SATURDAY.
A QUICK SYNOPTIC ANALYSIS REVEALS MOSTLY ZONAL FLOW ACROSS THE
CONUS WITH THE EXCEPTION OF AN OPEN WAVE TROUGH ACROSS THE
ROCKIES. AT THE SURFACE...HIGH PRESSURE REMAINED SITUATED ACROSS
BOTH COASTS WITH A WEAK LOW PRESSURE SYSTEM ACROSS THE TEXAS
PANHANDLE. THE OPEN WAVE BEGAN TO SHIFT JUST SOUTH OF THE PLAINS
THIS MORNING...WHICH BROUGHT SHOWERS AND THUNDERSTORMS TO PORTIONS
OF KANSAS. SATELLITE IMAGERY REVEALS A THICK CLOUD COVER OVER MUCH
OF SOUTHEAST KANSAS AND MISSOURI WITH THINNING CIRRUS DECK ACROSS
SOUTHERN NEBRASKA AND IOWA. A SURFACE TROUGH ASSOCIATED WITH THE
LOW IN THE PANHANDLE ALSO BEGAN SHIFTING ACROSS THE PLAINS THIS
AFTERNOON AS WELL. A STRONG 850 MB JET STREAK ON THE BACKSIDE OF
THIS TROUGH ALSO SHIFTED ACROSS NEBRASKA THIS AFTERNOON. COMBINED
WITH STRONG MIXING...THIS JET STREAK LED TO A BRIEF PERIOD OF
STRONGER WIND GUSTS NEAR 30 MPH AND LOW RH VALUES NEAR 20 PERCENT.
THESE CONDITIONS WERE SEEN OVER A FAIRLY SMALL LOCALIZED AREA
STRETCHING FROM MCCOOK TO ORD WESTWARD.
FOR THE REST OF THE AFTERNOON...SHORT TERM MODELS INDICATE THE
WEAKENING OF THE 850 JET STREAK WHICH SHOULD RELAX WINDS AND HELP
STEADY RH VALUES. CURRENT THINKING IS WINDS WILL REMAIN MARGINAL
AROUND 20 TO 25 MPH FOR THE NEXT FEW HOURS OR SO ESPECIALLY WEST
OF A LINE FROM MCCOOK TO KEARNEY TO ORD BEFORE DECREASING BY LATE
THIS AFTERNOON AND EARLY EVENING.
AS THE SURFACE TROUGH CONTINUES TO SHIFT EASTWARD...MODELS ALSO
HINT AT THE POSSIBILITY FOR SOME ADDITIONAL SHOWER DEVELOPMENT
NEAR THE BOUNDARY...MAINLY SOUTH OF LINE FROM CAMBRIDGE TO
FULLERTON. WITH INSTABILITY PARAMETERS NEAR 300 TO 500 J/KG KEPT
MENTION OF THUNDER IN THE FORECAST FROM 0Z TO 3Z WITH DIMINISHING
INSTABILITY THEREAFTER LIKELY DECREASING THUNDER THREAT. AT THIS
POINT...REALLY THINKING ISOLATED LIGHT SHOWERS WITH MAYBE A RUMBLE
OF THUNDER OR TWO. HRRR AND 4 KM WRF MODEL ALSO IN AGREEMENT WITH
THIS THINKING.
HEADING INTO SATURDAY...THE UPPER LEVEL RIDGE SLOWLY BEGINS TO
BUILD EASTWARD INTO THE PLAINS BEHIND THE TROUGH AXIS. WARMER 850
MB TEMPERATURES WILL ALSO SLIDE INTO THE REGION. SHOULD BE A
FAIRLY NICE AND BRIGHT DAY WITH SURFACE HIGH PRESSURE OVER THE
FORECAST AREA...LIGHT NORTH WINDS AND TEMPERATURES RANGING IN THE
70S.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 320 PM CDT FRI APR 26 2013
GUIDANCE SUGGESTS AN OVERALL LACK IN KINEMATIC FORCING SHOULD
PROVIDE DRY CONDITIONS TO OUR AREA SUNDAY INTO SUNDAY EVENING.
DURING THE EARLY MORNING HOURS ON MONDAY HOWEVER...THERE ARE
INDICATIONS OF A WEAK MID LEVEL PERTURBATION MOVING OVER THE
REGION WITH PERHAPS ENOUGH OMEGA FOR PRECIPITATION PRODUCTION.
THAT BEING SAID FORECAST PROXIMITY SOUNDINGS FROM ACROSS OUR
AREA...PER THE NAM AND OPERATIONAL GFS...SUGGEST THE LOWER
TROPOSPHERE WILL REMAIN FAIRLY DRY AND AS A RESULT...IT IS
CURRENTLY BELIEVED NOTHING MORE THAN A FEW SPRINKLES WILL BE
REALIZED ACROSS THE AREA EARLY MONDAY MORNING. GIVEN ALL
THIS...WENT AHEAD WITH A SPRINKLE MENTION IN THE
FORECAST...PRIMARILY FOR LOCATIONS ACROSS OUR NORTH/NORTHWEST
WHERE OMEGA IS EXPECTED TO BE STRONGEST. DRY CONDITIONS ARE THEN
FORECAST INTO THE DAY MONDAY AND MONDAY NIGHT AS A LACK IN
KINEMATIC FORCING OVERTAKES THE AREA ONCE AGAIN.
ANOTHER CHANCE AT PRECIPITATION IS THEN FORECAST TUESDAY THROUGH
WEDNESDAY NIGHT AS A MID LEVEL SHORT WAVE IS EXPECTED TO MOVE OVER
PORTIONS OF THE NORTHERN AND CENTRAL PLAINS. AN ASSOCIATED SURFACE
LOW IS ALSO EXPECTED TO MOVE ACROSS PORTIONS OF THE NORTHERN
PLAINS AND UPPER MISSISSIPPI VALLEY WITH A LOW LEVEL BAROCLINIC
ZONE FORECAST TO MOVE ACROSS OUR CWA AT SOME POINT DURING THE DAY
TUESDAY. TIMING THE PASSAGE OF THE LOW LEVEL BAROCLINIC ZONE IS
DIFFICULT GIVEN THIS SYSTEM IS STILL 4 DAYS OUT...BUT AT THIS TIME
IT APPEARS LOCATIONS AHEAD OF THE BAROCLINIC ZONE WILL OBSERVE A
SURFACE DEWPOINT IN THE MID TO UPPER 50S. THIS LOW LEVEL
MOISTURE...WORKING IN CONCERT WITH INCREASING MID LEVEL LAPSE
RATES WITH THE APPROACH OF THE MID LEVEL SHORT WAVE...COULD
POTENTIALLY PROMOTE 0-1KM MLCAPE VALUES ANYWHERE BETWEEN 500J/KG
AND 1500J/KG. INCREASING MID TO UPPER LEVEL FLOW IS ALSO EXPECTED
TO INCREASE DEEP LAYER BULK SHEAR TO BETWEEN 30KTS AND 40KTS.
GIVEN ALL THIS...IT CERTAINLY APPEARS SEVERE WEATHER COULD BE
REALIZED AT LOCATIONS STILL OUT AHEAD OF THE LOW LEVEL BAROCLINIC
ZONE TUESDAY AFTERNOON AND EVENING. AT THIS TIME IT ALSO APPEARS
THE SOUTHEASTERN ONE-THIRD OF OUR CWA STANDS THE BEST CHANCE AT
OBSERVING SEVERE WEATHER AND AS A RESULT...WILL CONTINUE SUCH
WORDING IN THE HWO.
ANY SEVERE WEATHER THAT IS REALIZED ACROSS THE AREA TUESDAY
AFTERNOON AND EVENING SHOULD QUICKLY DEPART TO THE EAST/SOUTHEAST
TUESDAY NIGHT AS THE LOW LEVEL BAROCLINIC ZONE DOES THE SAME.
DECREASING LOW LEVEL MOISTURE SHOULD ALLOW FOR DECREASING
POTENTIAL INSTABILITY BUT WITH INCREASING OMEGA DUE TO THE
APPROACHING MID LEVEL SHORT WAVE...CHANCES FOR PRECIPITATION
CONTINUE IN THE FORECAST FOR MOST ALL OF OUR CWA TUESDAY NIGHT
INTO WEDNESDAY...AND LINGERING ACROSS OUR EAST/SOUTHEAST WEDNESDAY
NIGHT. DRY CONDITIONS ARE THEN FORECAST THURSDAY ONWARD.
A VERY WARM LOW LEVEL AIRMASS WILL CONTINUE TO PROMOTE AN
AFTERNOON HIGH TEMPERATURE IN THE 70S TO LOW 80S SUNDAY THROUGH
TUESDAY. THE PASSAGE OF THE LOW LEVEL BAROCLINIC ZONE ON TUESDAY
HOWEVER WILL THEN BRING AN END TO THE WARM WEATHER...WITH A COOLER
LOW LEVEL AIRMASS LIKELY PROMOTING AN AFTERNOON HIGH TEMPERATURE
IN THE 50S AND 60S TO FINISH OUT THE FORECAST PERIOD. AN OVERNIGHT
LOW TEMPERATURE IN THE 40S AND 50S IS EXPECTED SUNDAY NIGHT
THROUGH TUESDAY NIGHT...WITH LOWS RANGING FROM THE MID 30S TO THE
LOW 40S WEDNESDAY NIGHT ONWARD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1252 AM CDT SAT APR 27 2013
THE BIGGEST ISSUE WILL BE VISIBILITY. THE HRRR MODEL SEEMS TO BE
DOING THE BEST AT PICKING UP ON FOG AND STRATUS TO THE SOUTH...SO
FOLLOWING THIS MODEL MORE CLOSELY THAN THE OTHERS...WHICH ARE NOT
PREDICTING MUCH FOG IF ANY. SUBSIDENCE SHOULD HELP SCOUR OUT THE
FOG AND STRATUS BY MID-MORNING SATURDAY.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR NEZ040-041-
046>049-060>064-072>077-082>087.
KS...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR KSZ005>007-
017-018.
&&
$$
UPDATE...HEINLEIN
SHORT TERM...SALTZMAN
LONG TERM...BRYANT
AVIATION...HEINLEIN
AREA FORECAST DISCUSSION
NWS HASTINGS NE
100 AM CDT SAT APR 27 2013
.UPDATE...
ISSUED AT 1252 AM CDT SAT APR 27 2013
HIT THE FOG A LITTLE HARDER IN THIS UPDATE AS THE HRRR SEEMS TO BE
PICKING UP THE FOG TO THE SOUTH THE BEST. IF WE CONTINUE TO
TANK...WE COULD END UP WITH A DENSE FOG ADVISORY FOR A GOOD CHUNK
OF THE CWA THIS MORNING.
UPDATE ISSUED AT 902 PM CDT FRI APR 26 2013
WITH TEMPERATURES APPROACHING THE DEW POINTS ACROSS NORTH CENTRAL
KANSAS ALREADY THIS EVENING AND LIGHT SOUTHEASTERLY WINDS
ADVECTING ADDITIONAL MOISTURE NORTHWARD...DECIDED TO INSERT SOME
AREAS OF FOG INTO THE FORECAST DURING THE OVERNIGHT/EARLY MORNING
HOURS TOMORROW. 00Z HRRR IS VERY AGGRESSIVE WITH WIDESPREAD
VISIBILITIES DROPPING TO 1/4 SM...BUT SREF PROBS KEEP LOWER
VISIBILITIES SOUTH OF THE LOCAL AREA...SO WENT AHEAD WITH A
COMPROMISE...BRINGING FOG UP TO AROUND HIGHWAY 6 IN SOUTH CENTRAL
NEBRASKA OVERNIGHT. OTHERWISE...NO ADDITIONAL CHANGES MADE TO
PREVIOUS FORECAST AT THIS TIME.
UPDATE ISSUED AT 650 PM CDT FRI APR 26 2013
WENT AHEAD AND UPDATED THE FORECAST TO REMOVE THE SMALL CHANCES
FOR THUNDERSTORMS THIS EVENING AS WHILE THE SPC MESO ANALYSIS PAGE
INDICATES THERE ARE A COUPLE HUNDRED JOULES OF CAPE ACROSS OUR AREA
RIGHT NOW...THIS WILL DIMINISH OVER THE NEXT COUPLE OF HOURS AND
THUS FAR SHOWERS AND THUNDERSTORMS HAVE LACKED A TRIGGER FOR
DEVELOPMENT. OTHER THAN REMOVING THESE SMALL CHANCES FOR
PRECIPITATION...NO ADDITIONAL CHANGES WERE MADE TO THE PREVIOUS
FORECAST AT THIS TIME.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 320 PM CDT FRI APR 26 2013
MAIN FOCUS IN THE SHORT TERM WILL CENTER AROUND SLIGHT CHANCES FOR
THUNDERSTORMS AND HIGH TEMPERATURES SATURDAY.
A QUICK SYNOPTIC ANALYSIS REVEALS MOSTLY ZONAL FLOW ACROSS THE
CONUS WITH THE EXCEPTION OF AN OPEN WAVE TROUGH ACROSS THE
ROCKIES. AT THE SURFACE...HIGH PRESSURE REMAINED SITUATED ACROSS
BOTH COASTS WITH A WEAK LOW PRESSURE SYSTEM ACROSS THE TEXAS
PANHANDLE. THE OPEN WAVE BEGAN TO SHIFT JUST SOUTH OF THE PLAINS
THIS MORNING...WHICH BROUGHT SHOWERS AND THUNDERSTORMS TO PORTIONS
OF KANSAS. SATELLITE IMAGERY REVEALS A THICK CLOUD COVER OVER MUCH
OF SOUTHEAST KANSAS AND MISSOURI WITH THINNING CIRRUS DECK ACROSS
SOUTHERN NEBRASKA AND IOWA. A SURFACE TROUGH ASSOCIATED WITH THE
LOW IN THE PANHANDLE ALSO BEGAN SHIFTING ACROSS THE PLAINS THIS
AFTERNOON AS WELL. A STRONG 850 MB JET STREAK ON THE BACKSIDE OF
THIS TROUGH ALSO SHIFTED ACROSS NEBRASKA THIS AFTERNOON. COMBINED
WITH STRONG MIXING...THIS JET STREAK LED TO A BRIEF PERIOD OF
STRONGER WIND GUSTS NEAR 30 MPH AND LOW RH VALUES NEAR 20 PERCENT.
THESE CONDITIONS WERE SEEN OVER A FAIRLY SMALL LOCALIZED AREA
STRETCHING FROM MCCOOK TO ORD WESTWARD.
FOR THE REST OF THE AFTERNOON...SHORT TERM MODELS INDICATE THE
WEAKENING OF THE 850 JET STREAK WHICH SHOULD RELAX WINDS AND HELP
STEADY RH VALUES. CURRENT THINKING IS WINDS WILL REMAIN MARGINAL
AROUND 20 TO 25 MPH FOR THE NEXT FEW HOURS OR SO ESPECIALLY WEST
OF A LINE FROM MCCOOK TO KEARNEY TO ORD BEFORE DECREASING BY LATE
THIS AFTERNOON AND EARLY EVENING.
AS THE SURFACE TROUGH CONTINUES TO SHIFT EASTWARD...MODELS ALSO
HINT AT THE POSSIBILITY FOR SOME ADDITIONAL SHOWER DEVELOPMENT
NEAR THE BOUNDARY...MAINLY SOUTH OF LINE FROM CAMBRIDGE TO
FULLERTON. WITH INSTABILITY PARAMETERS NEAR 300 TO 500 J/KG KEPT
MENTION OF THUNDER IN THE FORECAST FROM 0Z TO 3Z WITH DIMINISHING
INSTABILITY THEREAFTER LIKELY DECREASING THUNDER THREAT. AT THIS
POINT...REALLY THINKING ISOLATED LIGHT SHOWERS WITH MAYBE A RUMBLE
OF THUNDER OR TWO. HRRR AND 4 KM WRF MODEL ALSO IN AGREEMENT WITH
THIS THINKING.
HEADING INTO SATURDAY...THE UPPER LEVEL RIDGE SLOWLY BEGINS TO
BUILD EASTWARD INTO THE PLAINS BEHIND THE TROUGH AXIS. WARMER 850
MB TEMPERATURES WILL ALSO SLIDE INTO THE REGION. SHOULD BE A
FAIRLY NICE AND BRIGHT DAY WITH SURFACE HIGH PRESSURE OVER THE
FORECAST AREA...LIGHT NORTH WINDS AND TEMPERATURES RANGING IN THE
70S.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 320 PM CDT FRI APR 26 2013
GUIDANCE SUGGESTS AN OVERALL LACK IN KINEMATIC FORCING SHOULD
PROVIDE DRY CONDITIONS TO OUR AREA SUNDAY INTO SUNDAY EVENING.
DURING THE EARLY MORNING HOURS ON MONDAY HOWEVER...THERE ARE
INDICATIONS OF A WEAK MID LEVEL PERTURBATION MOVING OVER THE
REGION WITH PERHAPS ENOUGH OMEGA FOR PRECIPITATION PRODUCTION.
THAT BEING SAID FORECAST PROXIMITY SOUNDINGS FROM ACROSS OUR
AREA...PER THE NAM AND OPERATIONAL GFS...SUGGEST THE LOWER
TROPOSPHERE WILL REMAIN FAIRLY DRY AND AS A RESULT...IT IS
CURRENTLY BELIEVED NOTHING MORE THAN A FEW SPRINKLES WILL BE
REALIZED ACROSS THE AREA EARLY MONDAY MORNING. GIVEN ALL
THIS...WENT AHEAD WITH A SPRINKLE MENTION IN THE
FORECAST...PRIMARILY FOR LOCATIONS ACROSS OUR NORTH/NORTHWEST
WHERE OMEGA IS EXPECTED TO BE STRONGEST. DRY CONDITIONS ARE THEN
FORECAST INTO THE DAY MONDAY AND MONDAY NIGHT AS A LACK IN
KINEMATIC FORCING OVERTAKES THE AREA ONCE AGAIN.
ANOTHER CHANCE AT PRECIPITATION IS THEN FORECAST TUESDAY THROUGH
WEDNESDAY NIGHT AS A MID LEVEL SHORT WAVE IS EXPECTED TO MOVE OVER
PORTIONS OF THE NORTHERN AND CENTRAL PLAINS. AN ASSOCIATED SURFACE
LOW IS ALSO EXPECTED TO MOVE ACROSS PORTIONS OF THE NORTHERN
PLAINS AND UPPER MISSISSIPPI VALLEY WITH A LOW LEVEL BAROCLINIC
ZONE FORECAST TO MOVE ACROSS OUR CWA AT SOME POINT DURING THE DAY
TUESDAY. TIMING THE PASSAGE OF THE LOW LEVEL BAROCLINIC ZONE IS
DIFFICULT GIVEN THIS SYSTEM IS STILL 4 DAYS OUT...BUT AT THIS TIME
IT APPEARS LOCATIONS AHEAD OF THE BAROCLINIC ZONE WILL OBSERVE A
SURFACE DEWPOINT IN THE MID TO UPPER 50S. THIS LOW LEVEL
MOISTURE...WORKING IN CONCERT WITH INCREASING MID LEVEL LAPSE
RATES WITH THE APPROACH OF THE MID LEVEL SHORT WAVE...COULD
POTENTIALLY PROMOTE 0-1KM MLCAPE VALUES ANYWHERE BETWEEN 500J/KG
AND 1500J/KG. INCREASING MID TO UPPER LEVEL FLOW IS ALSO EXPECTED
TO INCREASE DEEP LAYER BULK SHEAR TO BETWEEN 30KTS AND 40KTS.
GIVEN ALL THIS...IT CERTAINLY APPEARS SEVERE WEATHER COULD BE
REALIZED AT LOCATIONS STILL OUT AHEAD OF THE LOW LEVEL BAROCLINIC
ZONE TUESDAY AFTERNOON AND EVENING. AT THIS TIME IT ALSO APPEARS
THE SOUTHEASTERN ONE-THIRD OF OUR CWA STANDS THE BEST CHANCE AT
OBSERVING SEVERE WEATHER AND AS A RESULT...WILL CONTINUE SUCH
WORDING IN THE HWO.
ANY SEVERE WEATHER THAT IS REALIZED ACROSS THE AREA TUESDAY
AFTERNOON AND EVENING SHOULD QUICKLY DEPART TO THE EAST/SOUTHEAST
TUESDAY NIGHT AS THE LOW LEVEL BAROCLINIC ZONE DOES THE SAME.
DECREASING LOW LEVEL MOISTURE SHOULD ALLOW FOR DECREASING
POTENTIAL INSTABILITY BUT WITH INCREASING OMEGA DUE TO THE
APPROACHING MID LEVEL SHORT WAVE...CHANCES FOR PRECIPITATION
CONTINUE IN THE FORECAST FOR MOST ALL OF OUR CWA TUESDAY NIGHT
INTO WEDNESDAY...AND LINGERING ACROSS OUR EAST/SOUTHEAST WEDNESDAY
NIGHT. DRY CONDITIONS ARE THEN FORECAST THURSDAY ONWARD.
A VERY WARM LOW LEVEL AIRMASS WILL CONTINUE TO PROMOTE AN
AFTERNOON HIGH TEMPERATURE IN THE 70S TO LOW 80S SUNDAY THROUGH
TUESDAY. THE PASSAGE OF THE LOW LEVEL BAROCLINIC ZONE ON TUESDAY
HOWEVER WILL THEN BRING AN END TO THE WARM WEATHER...WITH A COOLER
LOW LEVEL AIRMASS LIKELY PROMOTING AN AFTERNOON HIGH TEMPERATURE
IN THE 50S AND 60S TO FINISH OUT THE FORECAST PERIOD. AN OVERNIGHT
LOW TEMPERATURE IN THE 40S AND 50S IS EXPECTED SUNDAY NIGHT
THROUGH TUESDAY NIGHT...WITH LOWS RANGING FROM THE MID 30S TO THE
LOW 40S WEDNESDAY NIGHT ONWARD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1252 AM CDT SAT APR 27 2013
THE BIGGEST ISSUE WILL BE VISIBILITY. THE HRRR MODEL SEEMS TO BE
DOING THE BEST AT PICKING UP ON FOG AND STRATUS TO THE SOUTH...SO
FOLLOWING THIS MODEL MORE CLOSELY THAN THE OTHERS...WHICH ARE NOT
PREDICTING MUCH FOG IF ANY. SUBSIDENCE SHOULD HELP SCOUR OUT THE
FOG AND STRATUS BY MID-MORNING SATURDAY.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...HEINLEIN
SHORT TERM...SALTZMAN
LONG TERM...BRYANT
AVIATION...HEINLEIN
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1147 PM CDT FRI APR 26 2013
.DISCUSSION...
PULLED ALL MENTION OF RAIN FROM THE SOUTHEASTERN FORECAST AREA
TONIGHT AND ON SATURDAY. ALSO ADDED IN SOME PATCHY FOG LATE
TONIGHT AND SATURDAY MORNING ALONG AND SOUTH OF THE STALLED
SURFACE TROUGH THAT EXISTS FROM COLUMBUS TO TEKAMAH WHERE
DEWPOINTS ARE IN THE MID TO UPPER 40S. RUC WAS INDICATING SOME
PROBABILITY FOR DENSE FOG ACROSS SOUTH CENTRAL INTO SOUTHEAST
NEBRASKA...AS WAS THE MOST RECENT MET GUIDANCE. THIS WOULD LIKELY
DEVELOP ON THE NORTHERN FRINGE OF SOME STRATUS THAT REMAINED ALONG
THE NE/SD BORDER REGION. THE STRATUS WAS ALSO SLOWLY MOVING
NORTHWARD ALONG THE MISSOURI RIVER AND INTO SOUTHWEST IOWA.
DEWALD
&&
.AVIATION...06Z TAFS FOR KOMA...KLNK AND KOFK. VFR CONDITIONS AT
KOFK WITH LIGHT AND VARIABLE WINDS THROUGH THE PERIOD. FORECAST A
PERIOD OF MVFR CONDITIONS AT KLNK/KOMA FROM 09Z-14Z AS PATCHY FOG
MIGHT DEVELOP. FOG COULD BRIEFLY GO DOWN TO IFR LEVELS AT KLNK
BASED ON MODEL TRENDS. MVFR STRATUS DECK MAY ALSO MOVE INTO KOMA
DURING THAT SAME TIME AS WELL. OTHERWISE...SOUTH TO SOUTHEAST
WINDS LESS THAN 10KTS THROUGH THE PERIOD.
DEWALD
&&
.PREV DISCUSSION... /ISSUED 335 PM CDT FRI APR 26 2013/
SHORT TERM...TONIGHT THROUGH MONDAY.
THERE ARE SEVERAL ISSUES IN THIS TIME PERIOD. THE MAIN ONES ARE THE
CHANCE FOR SHOWERS/ISOLATED THUNDERSTORMS THIS EVENING...THE CHANCE
OF PCPN WITH THE FRONT FROM LATE SUNDAY INTO MONDAY AND TEMPERATURES
THE NEXT FEW DAYS.
TONIGHT...A WEAK FRONTAL BOUNDARY EXTENDING FROM NORTHEAST TO
SOUTHWEST ACROSS THE AREA MAY BE ENOUGH TO HELP TRIGGER SOME VERY
LIGHT SHOWERS OR SPRINKLES THIS EVENING. SOME OF THE MODELS HAVE
BEEN SHOWING THAT...INCLUDING RECENT RUNS OF RAPID REFRESH...
ALTHOUGH THE MOST RECENT RUNS ARE NOT AS BULLISH WITH FORECAST
REFLECTIVITY VALUES AS COMPARED TO THE EARLIER RUNS. THIS IS IN
AREA WHICH APPEARS TO HAVE SLIGHTLY HIGHER 850 MB MOISTURE. THERE
IS ALSO SOME SMALL ELEVATED CAPE...BUT DID NOT MENTION THUNDER AT
THIS POINT. LARGER SCALE FORCING WITH SYSTEM TO THE SOUTH WILL
PRODUCE PCPN ACROSS KANSAS AND MISSOURI...AND POSSIBLY INTO THE
FAR SOUTHWEST CORNER OF IOWA AND SOUTHEAST NEBRASKA. KEPT SOME
POPS IN PLACE FOR THAT. LOWS SHOULD HOLD IN THE LOWER TO MID 40S
SOUTH BUT MAY DROP INTO THE 30S NORTH WHERE CLOUD COVER WILL BE
LESS.
ON SATURDAY...WINDS REMAIN FAIRLY LIGHT AND MIXING WILL BE POOR. THE
RESULT SHOULD BE HIGHS CLOSE TO MOS GUIDANCE...IN THE UPPER 60S OR
LOWER 70S. AGAIN...SOME OF THE MODELS HINT AT SOME LIGHT PCPN IN THE
AFTERNOON ACROSS ABOUT THE SOUTHEAST 1/3 OF THE FORECAST AREA. DID
NOT MENTION ANYTHING FOR MOST AREAS RIGHT NOW...EXCEPT NEAR THE
MISSOURI BORDER. THAT MAY NEED TO BE UPDATED LATER.
ON SUNDAY...FAIRLY WARM AIR MOVES INTO THE REGION AND SOUTHERLY
WINDS SHOULD ALLOW FOR DECENT MIXING. NET RESULT SHOULD BE HIGHS IN
THE UPPER 70S AND LOWER 80S. A COLD FRONT WILL BE MOVING TOWARD
NORTHEAST NEBRASKA THOUGH BY LATE IN THE DAY. AS THE FRONT SAGS TO
THE SOUTH SUNDAY NIGHT...IT APPEARS THAT THERE WILL BE ENOUGH
MOISTURE AND INSTABILITY FOR AT LEAST SOME SCATTERED SHOWERS AND
THUNDERSTORMS. THIS CHANCE CONTINUES INTO MONDAY. THE BEST CHANCE
APPEARS TO BE FROM NORTHEAST NEBRASKA INTO WESTERN IOWA. TIMING OF
THE FRONT...CLOUD COVER AND POSSIBLE PCPN COULD HAVE A BIG AFFECT ON
HIGHS MONDAY...BUT WENT WITH MAINLY 70S. LATEST RUNS OF THE NAM SHOW
HIGHS MAINLY IN THE 80S.
MILLER
LONG TERM...MONDAY NIGHT THROUGH THURSDAY.
THE RECENT TIMING DIFFERENCES IN THE GFS AND ECMWF WILL CONTINUE TO
BE PROBLEMATIC. LEANED MORE TOWARD A BLEND OF MODEL TIMING...BUT 12Z
ECMWF SEEMED TOO COLD AND TOO WET LATE IN THE WEEK. TEMPERATURES
WILL TURN MUCH COLDER AGAIN BY MID WEEK...WITH FAIRLY HIGH RAIN
CHANCES BEHIND THE FRONT FROM TUESDAY NIGHT INTO WEDNESDAY NIGHT.
KEPT POPS BELOW 20 PERCENT THURSDAY AND FRIDAY...SINCE WETTER 12Z
ECMWF SOLUTION WAS NOT PREFERRED.
MILLER
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BUFFALO NY
425 AM EDT SAT APR 27 2013
.SYNOPSIS...
A WEAK UPPER LEVEL DISTURBANCE MOVING NORTH OF LAKE ONTARIO WILL
BRING A PERIOD OF CLOUD COVER TODAY TO THE NORTH COUNTRY. OTHERWISE
THE REST OF THE AREA WILL BE MOSTLY SUNNY AS HIGH PRESSURE REMAINS
IN PLACE. THE NEXT CHANCE OF RAIN WILL ARRIVE SUNDAY NIGHT AND
MONDAY AS A WEAK AREA OF LOW PRESSURE LIFTS OUT OF THE OHIO VALLEY.
BUILDING WARMTH THIS WEEKEND WILL CONTINUE ALL OF NEXT WEEK WITH AN
EXTENDED PERIOD OF ABOVE AVERAGE TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
SURFACE ANALYSIS EARLY THIS MORNING SHOWING HIGH PRESSURE IN PLACE
FROM THE LOWER LAKES INTO NEW ENGLAND. WATER VAPOR IMAGERY AND
OBJECTIVE RUC ANALYSIS SHOWING A WEAK SHORTWAVE CROSSING SOUTHERN
QUEBEC AND SOUTHEAST ONTARIO...WITH AN ASSOCIATED BAND OF MID/HIGH
CLOUDS. THIS FEATURE WILL CROSS THE NORTH COUNTRY THROUGH THE FIRST
HALF OF TODAY WITH A PERIOD OF INCREASED CLOUD COVER. UPSTREAM
RADARS DO SHOW A FEW WEAK BANDS OF SHOWERS OVER SOUTHERN ONTARIO...
BUT SHORT TERM MODEL GUIDANCE SUGGESTS THE RAIN WILL FALL APART FOR
THE MOST PART AS IT MOVES EAST INTO AN EVER DRIER AIRMASS AND
INCREASING SUBSIDENCE. WITH THIS IN MIND WILL JUST CARRY SCATTERED
SPRINKLES FOR THE NORTH COUNTRY FROM MID MORNING THROUGH MIDDAY WITH
THE PASSAGE OF THE MID LEVEL TROUGH AND ASSOCIATED PERIOD OF WEAK
ASCENT.
FOR THE REST OF THE AREA...SOME HIGH CLOUDS ON THE SOUTHERN EDGE OF
THIS SYSTEM WILL CLIP THE AREA...ESPECIALLY FROM THE THRUWAY
NORTHWARD. THESE SHOULD REMAIN THIN ENOUGH TO STILL ALLOW FOR A GOOD
AMOUNT OF SUNSHINE TO FILTER THROUGH. 850MB TEMPS RECOVER TO AROUND
+5C TODAY...WHICH WILL SUPPORT HIGHS IN THE UPPER 60S IN MANY
LOCATIONS WITH A FEW OF THE TYPICALLY WARMER SPOTS POSSIBLY REACHING
70. THE LIGHT SYNOPTIC FLOW COMBINED WITH STRONG DIFFERENTIAL
HEATING WILL SUPPORT LOCAL LAKE BREEZES BY EARLY AFTERNOON WHICH
WILL HOLD THE LAKESHORES IN THE 50S.
TONIGHT HIGH PRESSURE WILL DRIFT OFF THE EASTERN SEABOARD...ALLOWING
FOR ONGOING SOUTHERLY RETURN FLOW. THIS WILL KEEP TEMPS MILDER THAN
RECENT NIGHTS...WITH MID TO UPPER 40S ON THE LAKE PLAINS AND LOWER
40S FARTHER INLAND. A FEW OF THE COLDER SOUTHERN TIER VALLEYS AND
TUG HILL REGION WILL STILL DIP INTO THE UPPER 30S WHERE WINDS ARE
MORE LIKELY TO DECOUPLE. ANY LEFTOVER MID/HIGH CLOUDS EAST OF LAKE
ONTARIO ASSOCIATED WITH THE DEPARTING MID LEVEL SHORTWAVE SHOULD
THIN OUT OVERNIGHT AS MID LEVEL HEIGHTS RISE AND SUBSIDENCE
CONTINUES TO INCREASE.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/...
LOW PRESSURE LOCATED OVER THE SOUTHERN PLAINS EARLY THIS SATURDAY
MORNING WILL LIFT TO THE NORTHEAST AND REACH THE OHIO VALLEY ON
SUNDAY. HIGH PRESSURE ANCHORED OFF THE EAST COAST WILL KEEP OUR AREA
DRY...BUT WARM AIR ADVECTION AHEAD OF THE APPROACHING SURFACE LOW
WILL BRING A GRADUAL INCREASE IN CLOUDS TO WESTERN NEW YORK AND THE
GENESEE VALLEY. THE SOUTHERLY FLOW BETWEEN THESE TWO SYSTEMS WILL
ALLOW TEMPERATURES TO WARM WELL INTO THE 60S...AND MAYBE EVEN LOWER
70S ALONG THE LAKE PLAINS WHERE DOWNSLOPING WINDS WILL GIVE AN ADDED
BOOST TO THE TEMPERATURES. AREAS EAST OF LAKE ONTARIO MAY ALSO WARM
INTO THE LOWER 70S DUE TO MORE SUNSHINE.
SUNDAY NIGHT AND MONDAY...THE WEAKENING SURFACE LOW WILL MOVE SLOWLY
TO THE NORTH WHILE THE UPPER LEVEL TROUGH SHIFTS EAST ACROSS NEW
YORK AND PA. A MODEST LOW LEVEL JET THAT WILL BE LIFTING NORTH
ACROSS NEW YORK STATE WILL TAP INTO THE DEEPER MOISTURE THAT WILL BE
IN PLACE OVER THE OHIO AND TENNESSEE VALLEYS. THIS WILL RESULT IN A
GRADUAL SOUTH TO NORTH INCREASE TO LIKELY POPS DURING THIS PERIOD.
IN TERMS OF QPF...THIS SYSTEM DOES NOT APPEAR AS IF IT WILL BE A BIG
RAIN MAKER...BUT IT WILL KEEP OUR WEATHER A LITTLE UNSETTLED. THE
INCREASE IN CLOUDS AND CHANCES FOR RAIN WILL KEEP TEMPERATURES A
LITTLE COOLER ON MONDAY.
THE SHOWERS WILL SHIFT SLOWLY TO THE EAST MONDAY NIGHT AND TUESDAY
AS THE UPPER TROUGH HEADS EAST TO THE NEW ENGLAND COAST. BASED ON
THIS TREND...EXPECT ANY LINGERING SHOWERS TO BE EAST OF OUR CWA BY
NOONTIME TUESDAY. THE PERSISTENT SOUTHERLY FLOW AND ANTICIPATED
TREND TOWARD SOME INCREASE IN SUNSHINE WILL ALLOW TEMPERATURES TO
WARM WELL INTO THE 60S AGAIN ON TUESDAY. DRY WEATHER AND SEASONABLY
MILD TEMPERATURES WILL CONTINUE THROUGH TUESDAY NIGHT.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AN UPPER LEVEL TROUGH WILL DIG INTO THE NATIONS MIDSECTION DURING
THE MIDDLE OF THE WEEK...WHILE A RIDGE REMAINS IN PLACE FROM THE
MIDDLE ATLANTIC STATES TO THE CANADIAN MARITIMES. THE UPPER TROUGH
IS FORECAST TO DEEPEN FURTHER AND TRANSITION TO A CUTOFF LOW OVER
THE MID MISSISSIPPI VALLEY BY FRIDAY. THE DEEPENING TROUGH WILL HELP
TO MAINTAIN A DOWNSTREAM RIDGE OVER THE NORTHEAST AND NEW ENGLAND.
THE UPPER RIDGE SHOULD HELP TO KEEP THE STEADIER PCPN...ASSOCIATED
WITH THE UPSTREAM TROUGH...TO OUR WEST.
THE DEEP LAYERED SOUTHERLY FLOW WILL KEEP TEMPERATURES MILD THROUGH
THURSDAY. THICKENING CLOUDS AND SOME INCREASE IN CHANCE FOR SHOWERS
MAY KEEP TEMPERATURES A LITTLE COOLER ON FRIDAY. HOWEVER...IF THE
THE ECMWF`S UPPER LEVEL CONFIGURATION (WHICH FEATURES A STRONGER AND
MORE PERSISTENT UPPER LEVEL RIDGE OVER THE NORTHEAST)
VERIFIES...THEN MILDER AND DRY CONDITIONS MAY LINGER INTO FRIDAY.
&&
.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
VFR WILL PREVAIL FOR THE 06Z TAF CYCLE. IR SATELLITE IMAGERY SHOWING
MAINLY CLEAR SKIES EARLY THIS MORNING...WITH JUST SOME THIN/HIGH
CIRRUS BEGINNING TO INCREASE. THESE CLOUDS WILL THICKEN AND LOWER
INTO A MID LEVEL DECK BY SATURDAY MORNING ACROSS THE NORTH COUNTRY
INCLUDING KART. THIS AREA MAY EVEN SEE A FEW SPRINKLES OR VERY LIGHT
SHOWERS THROUGH THE FIRST HALF OF SATURDAY...BUT THESE WILL REMAIN
LIGHT ENOUGH TO KEEP VSBY VFR. OTHERWISE THE REST OF THE AREA WILL
JUST SEE SCT CIRRUS LEVEL CLOUDINESS. THE LIGHT BACKGROUND WINDS
WILL ALLOW LOCAL LAKE BREEZES TO DEVELOP DURING THE AFTERNOON WITH
WIND SHIFTS LIKELY OCCURRING WITHIN 10-20 MILES OF THE LAKESHORES.
OUTLOOK...
SUNDAY AND SUNDAY NIGHT...MOSTLY VFR WITH SHOWERS LIKELY DEVELOPING
SUNDAY AFTERNOON AND NIGHT.
MONDAY...MOSTLY VFR WITH A CHANCE OF SHOWERS.
TUESDAY THROUGH WEDNESDAY...VFR.
&&
.MARINE...
HIGH PRESSURE IN PLACE FROM THE OHIO VALLEY TO THE NORTHEAST WILL
PROVIDE LIGHT WINDS TODAY AND TONIGHT. STRONG DIFFERENTIAL HEATING
TODAY WILL SUPPORT LAKE BREEZE DEVELOPMENT BY EARLY AFTERNOON WITH
WINDS BECOMING LOCALLY ONSHORE ON BOTH LAKES ERIE AND ONTARIO. BY
SUNDAY NIGHT AND MONDAY HIGH PRESSURE WILL DRIFT OFF THE EAST COAST.
THIS WILL ALLOW THE PRESSURE GRADIENT TO INCREASE SOMEWHAT...WITH
SOUTH TO SOUTHEAST WINDS INCREASING BUT STILL REMAINING WELL BELOW
SMALL CRAFT ADVISORY CRITERIA. SOUTH TO SOUTHEAST WINDS WILL REMAIN
IN PLACE MUCH OF NEXT WEEK WITH GENERALLY LIGHT WAVE ACTION GIVEN
THE OFFSHORE FLOW.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...HITCHCOCK
NEAR TERM...HITCHCOCK
SHORT TERM...TJP
LONG TERM...TJP
AVIATION...HITCHCOCK
MARINE...HITCHCOCK
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
329 AM EDT SAT APR 27 2013
.SYNOPSIS...
CLOUDS WILL BE ON THE INCREASE TODAY. PASSING SHOWERS WILL
DEVELOP INLAND LATER THIS AFTERNOON AND OVERNIGHT. SEVERAL
DISTURBANCES MOVING EAST ACROSS THE GULF STATES WILL LEAD TO
INCREASING CLOUDS SUNDAY AND ELEVATED RAIN CHANCES LATE SUNDAY
AND MONDAY. A SLIGHT DRYING TREND IS EXPECTED DURING THE MIDDLE OF
NEXT WEEK WITH AN APPROACHING COLD FRONT LATE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM SATURDAY...SURFACE HIGH PRESSURE WILL MOVE OFF THE NEW
ENGLAND COASTLINE AND INTO THE NORTH ATLANTIC THIS AFTERNOON. THIS
WILL MAINTAIN A FAIRLY DRY NORTHEAST TO EAST LOW-LEVEL FLOW INTO
THE EASTERN CAROLINAS THROUGH TONIGHT. SURFACE LOW PRESSURE ALONG
THE TX-OK BORDER THIS MORNING WILL MOVE INTO SOUTHERN ILLINOIS
LATE TONIGHT. THIS LOW IS BEING MAINTAINED BY A SHORTWAVE TROUGH
ALMOST CUT OFF FROM THE MAIN JET STREAM FLOW WELL TO THE NORTH
ACROSS THE NORTHERN UNITED STATES.
THICKENING HIGH AND MID LEVEL CLOUDS EARLY THIS MORNING ARE BEING
PRODUCED BY PACIFIC AND NOW GULF MOISTURE BEING ADVECTED OUT AHEAD
OF THE SHORTWAVE DISTURBANCE. DRY LOW LEVELS OF THE ATMOSPHERE PLUS
AND A PERSISTENT MID TO UPPER LEVEL RIDGE ACROSS THE SOUTHERN
APPALACHIANS ARE HELPING ERODE PRECIPITATION THAT IS TRYING TO
STREAM EAST-SOUTHEAST FROM KENTUCKY AND TENNESSEE. RADAR COMPOSITES
SHOW A NARROW BUT IMPRESSIVE AREA OF MODERATE TO HEAVY RAINFALL
ACROSS NORTHERN GEORGIA THAT LOOKS TO BE MOVING IN THE GENERAL
DIRECTION OF THE SANTEE RIVER BASIN. IF ANY OF THIS PRECIPITATION
SURVIVES OUR DRY AIR...IT WOULD REACH WILLIAMSBURG AND GEORGETOWN
COUNTIES BETWEEN 6-9 AM. THE 04Z HRRR APPEARS TO HAVE A GOOD HANDLE
ON THIS PRECIPITATION AND SHOWS ONLY A COUPLE HUNDREDTHS OF AN INCH
SCATTERED ALONG THE SANTEE RIVER LATER THIS MORNING.
PARTLY TO MOSTLY CLOUDY SKIES WILL CONTINUE THROUGH THE MORNING AND
AFTERNOON HOURS. HIGH SUN ANGLES (SAME AS IN MID AUGUST) WILL CUT
THROUGH THE CLOUDS AND PUSH TEMPERATURES INTO THE LOWER TO MID 70S
AWAY FROM THE BEACHES.
AN INTERESTING SITUATION WILL DEVELOP ACROSS CENTRAL SOUTH CAROLINA
LATE THIS AFTERNOON AS THE GFS AND ECMWF SHOW A NARROW ZONE OF
RATHER IMPRESSIVE ISENTROPIC LIFT DEVELOPING ALONG THE 305-310K
THETA SURFACES...APPROXIMATELY 12000-16000 FT AGL. THIS IS MUCH
HIGHER UP THAN WHERE I TYPICALLY ANALYZE ISENTROPIC LIFT BUT APPEARS
TO BE WHAT THE MODELS ARE LATCHING ONTO FOR THE DEVELOPMENT OF RAIN
THAT MAY AFFECT THE SC PEE DEE REGION JUST BEFORE SUNSET. I HAVE
INCREASED POPS TO 30-40 PERCENT MAINLY BETWEEN 5-9 PM...WITH MODELS
INDICATING THAT AGAIN THE RAIN WILL DRY UP AS IT TRIES TO MOVE EAST
TOWARD THE COAST. PERHAPS EVEN MORE INTERESTING IS THE POTENTIAL FOR
SMALL ELEVATED INSTABILITY ORIGINATING FROM VERY HIGH ALOFT...
500-550 MB. IT IS QUITE RARE FOR CONVECTION TO DEVELOP FROM SUCH A
HIGH BASE IN THIS PART OF THE COUNTRY...BUT THIS COULD ADD A LITTLE
CONVECTIVE CHARACTER TO WHAT MAY BE AN OTHERWISE STRATIFORM RAIN
EVENT. EVEN THE MOST AGGRESSIVE MODEL SHOWS CAPE LESS THAN 100 J/KG
SO WE`RE NOT TALKING ABOUT SEVERE WEATHER BY ANY STRETCH.
PRECIPITATION SHOULD DIMINISH IN COVERAGE DURING THE LATE EVENING
HOURS...BUT WITH PLENTY OF CLOUDS REMAINING OVERNIGHT. LOWS SHOULD
FALL TO 50-55...WARMEST ALONG THE SC COAST WITH THE ONSHORE WIND AND
ALSO BACK UNDER THE CLOUDS ACROSS THE PEE DEE REGION.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...SURFACE AND MID LEVEL RIDGE AXIS SHIFT
OFFSHORE EARLY IN THE PERIOD ALLOWING DEEP RETURN FLOW. PLENTY OF
DEEP MOISTURE IN PLACE WITH 850-500 LAYER RH VALUES GREATER THAN 75%
FOR THE DURATION OF THE PERIOD. ALTHOUGH SIGNIFICANT DYNAMICAL
FEATURES ARE LACKING THE FLOW ALOFT IS DIVERGENT. ADDITIONALLY THERE
ARE LIKELY TO BE WEAK AREAS OF POSITIVE VORTICITY ADVECTION ROTATING
THROUGH SHORTWAVE TROUGH TO THE WEST. TIMING THESE FEATURES 2 AND 3
DAYS OUT IS DIFFICULT AT BEST BUT THESE WOULD CERTAINLY HELP ENHANCE
ANY ONGOING CONVECTION AS THEY MOVE INTO THE AREA. ALTHOUGH
CONVECTIVE PARAMETERS ARE LIMITED LOW LEVEL CONVERGENCE COMBINED
WITH DIURNAL INSTABILITY SHOULD GENERATE SHOWERS. BEST PRECIP
CHANCES APPEAR TO BE EARLY MON AND MON NIGHT WITH ENHANCED
DIVERGENCE ALOFT AND INCREASED DEEP MOISTURE. HIGHS WILL FALL A
LITTLE SHORT OF CLIMO GIVEN INCREASED CLOUD COVER AND RAIN CHANCES.
ABUNDANT MOISTURE WILL KEEP LOWS NEAR TO SLIGHTLY ABOVE CLIMO.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 3 AM SATURDAY...MEDIUM RANGE GUIDANCE CONTINUES TO HAVE
PROBLEMS WITH EVOLUTION OF MID LEVEL PATTERN OVER THE CONUS NEXT
WEEK. HOWEVER SOME NUGGETS OF INFORMATION CAN BE GLEANED FROM THE
CHAOS. EARLY IN THE PERIOD WEAK PATTERN ALOFT AND COASTAL TROUGH
LEAD TO DIURNAL CONVECTION...THOUGH COVERAGE WILL BE LIMITED BY MID
LEVEL DRY AIR. BY THE MIDDLE OF NEXT WEEK THERE WILL BE A SOUTHERN
STREAM SYSTEM CROSSING THE NORTHERN GULF OF MEXICO. AT THE SAME TIME
A SIGNIFICANT COLD FRONT WILL BE DRIVEN ACROSS THE CENTRAL US BY
LONGWAVE MID LEVEL TROUGH. LATE IN THE PERIOD BOTH ECMWF AND GFS
HINT AT SOUTHERN STREAM SHORTWAVE INDUCING A COASTAL LOW OFF THE
SOUTHEAST COAST WHICH IS THEN LIFTED NORTH AHEAD OF THE COLD FRONT.
DESPITE SIMILARITIES BETWEEN THE GFS/ECMWF THERE REMAIN PLENTY OF
MAJOR DIFFERENCES. BOTH MODELS SHOW THE MID LEVEL TROUGH BECOMING
CUTOFF BUT DO SO AT DIFFERENT TIMES AND LOCATIONS. THE GFS IS SLOWER
TO CUTOFF THE 5H TROUGH AND THUS IS FARTHER EAST. GIVEN THE
UNCERTAINTY WILL KEEP POP CAPPED AT CHANCE WITH HIGHEST VALUES
DURING THE DAY. TEMPERATURES WILL BE NEAR TO SLIGHTLY BELOW CLIMO.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
AS OF 06Z...VFR THROUGH THE PERIOD. INCREASING RAIN CHANCES TONIGHT.
HIGH AND MID CLOUDS WILL CONTINUE TO THICKEN ACROSS THE AREA. LATEST
HIGH-RES MODELS INDICATE MODERATE TO HEAVY RAIN ACROSS S TN AND N GA
MAY MAKE A RUN TOWARD THE FLORENCE AIRPORT 10-13Z. I WILL MONITOR
CLOSELY TO SEE IF RAIN NEEDS TO BE ADDED TO OUR TAF FORECAST.
OTHERWISE RAIN CHANCES INCREASE FOR THE INLAND TERMINALS TOWARDS THE
EVENING HOURS...AND THEN FOR THE COASTAL TERMINALS INTO THE
OVERNIGHT HOURS.
EXTENDED OUTLOOK...UNSETTLED WEATHER SATURDAY NIGHT THROUGH TUESDAY
AS AN OVERRUNNING SCENARIO GIVES US MOSTLY CLOUDY CONDITIONS THROUGH
WEDNESDAY WITH PERIODS OF RAIN AND IFR CONDITIONS.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM SATURDAY...STRONG HIGH PRESSURE OVER NEW ENGLAND WILL
MOVE EAST AND INTO THE NORTH ATLANTIC LATER TODAY. THE HIGH WILL
CONTINUE TO RIDGE SOUTHWARD TOWARD THE CAROLINAS WITH NORTHEAST TO
EAST WIND CONTINUING. WIND SPEEDS SHOULD REMAIN A VERY CONSISTENT
10-15 KNOTS THROUGH TONIGHT...WHICH GIVEN THE LONG FETCH
ORIGINATING FROM NEWFOUNDLAND IS ENOUGH TO MAINTAIN A NEARLY
STEADY SEA STATE OF 3-4 FT NORTH OF CAPE FEAR AND EAST OF
GEORGETOWN...WITH 2-4 FT SEAS ELSEWHERE.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...LIGHT EASTERLY FLOW AT THE START OF THE PERIOD
QUICKLY BECOMES SOUTHEAST AS SURFACE RIDGE AXIS SHIFTS EAST OF THE
WATERS. ONLY SUBTLE CHANGES TO THE GRADIENT EXPECTED DURING THE
PERIOD WITH SEABREEZE DEVELOPMENT ENHANCING SPEEDS SLIGHTLY. SPEEDS
WILL REMAIN IN THE 10 TO 15 KT RANGE WITH SEAS RUNNING 3 TO 5 FT.
LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 3 AM SATURDAY...SOUTHERLY FLOW CONTINUES THROUGH THE PERIOD
WITH SURFACE HIGH CENTERED NORTHEAST OF THE WATERS BEING THE
DOMINANT FEATURE. GRADIENT REMAINS ON THE WEAK SIDE WITH SPEEDS
STRUGGLING TO REACH 15 KT EVEN WITH THE HELP OF SEABREEZE
ENHANCEMENT. SEAS WILL RUN 3 TO 4 FT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA
SHORT TERM...III
LONG TERM...III
AVIATION...SGL/TRA
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
130 AM EDT SAT APR 27 2013
.SYNOPSIS...
CLEAR WEATHER WILL PREVAIL INTO SATURDAY AS HIGH PRESSURE PASSES
NORTH OF THE REGION. SEVERAL DISTURBANCES MOVING EAST ACROSS THE
GULF STATES...WILL BRING INCREASING CLOUDS SUNDAY AND A CHANCE OF
RAIN LATE SUNDAY THROUGH MONDAY. A DRYING TREND IS EXPECTED DURING
THE MIDDLE OF NEXT WEEK WITH AN APPROACHING COLD FRONT LATE WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 130 AM SATURDAY...MID AND HIGH CLOUDS WILL CONTINUE TO PUSH
INTO THE AREA OVERNIGHT. WHILE THE LEADING EDGE OF THE CLOUD COVER
WILL PARTIALLY ERODE THE SKY SHOULD BECOME OVERCAST ACROSS THE SC
PEE DEE REGION BY 4 AM. LATEST HRRR AND GFS SHOW LIGHT PRECIP MAKING
IT AS FAR EAST AS FLORENCE AND KINGSTREE BETWEEN 6-9 AM SATURDAY
MORNING. LOOKING AT UPSTREAM RADARS THERE CERTAINLY IS QUITE A SWATH
OF MODERATE TO HEAVY RAINFALL ACROSS SOUTHERN TENNESSEE AND ENTERING
NORTH GEORGIA...MAKING A BEELINE FOR THIS REGION. MY NEXT UPDATE AT
3 AM WILL BETTER ADDRESS THE POTENTIAL FOR MEASURABLE RAIN ACROSS
THE AREA. OTHERWISE THE ONLY SUBSTANTIAL CHANGE TO THE FORECAST WAS
TO RAISE FORECAST LOW TEMPERATURES BY SEVERAL DEGREES ACROSS THE PEE
DEE REGION WITH THE THICKER CLOUDS EXPECTED TO MOVE IN SHORTLY.
PREVIOUS DISCUSSION FROM 1120 PM FOLLOWS...
EXTRAPOLATION OF THE CURRENT 11-3.9 MICRON SATELLITE IMAGERY LOOPS
INDICATE MAJORITY OF THE OPAQUE MID TO UPPER LEVEL CLOUDS TO REMAIN
NORTH OF THE FA THIS EVENING. DURING THE PRE-DAWN HRS...THIN TO
OPAQUE MID TO UPPER LEVEL CLOUDS WILL FURTHER SPILL OVER THE LOW
AMPLIFIED UPPER RIDGE AND COVERING THE MAJORITY OF THE ILM CWA BY
DAYBREAK. CURRENT MIN TEMP FORECAST BASICALLY ON TARGET...WITH THE
ONLY TWEAKS OF 1 TO 2 DEGREES LOWER TARGETING THE COASTAL ILM NC
COUNTIES. CLOUDINESS OVERSPREADING THE AREA LATER TONIGHT WILL
PREVENT ANY DECENT RADIATIONAL COOLING OVERNIGHT. SFC BASED
INVERSION WILL RESULT IN DECOUPLING WINDS ACROSS INLAND LOCATIONS
WHERE WINDS WILL DROP TO BETWEEN CALM AND NE-E AT 2 MPH. THE
EXCEPTION WILL BE ALONG THE IMMEDIATE COAST...WHERE NE-E WINDS WILL
DROP TO AROUND 5 MPH.
THE TIDE GAGE SITUATED IN THE CAPE FEAR RIVER IN THE VICINITY OF
DOWNTOWN WILMINGTON...IS MODELED TO APPROACH 5.45 FT MLLW AT THE
NEXT HIDE TIDE AROUND MIDNIGHT TONIGHT. THIS REMAINS JUST SHY OF THE
5.5 FT MLLW HEIGHT...WHICH IS THE THRESHOLD FOR MINOR COASTAL
FLOODING ACROSS THOSE USUAL PRONE LOCATIONS. WILL HAVE TO MONITOR
THE HIGH TIDE PROGGED GAGE READINGS FOR TOMORROW NIGHT...WHICH
ARE ALSO MODELED TO BE NEAR MINOR COASTAL FLOODING THRESHOLDS.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
AS OF 315 PM FRIDAY...SHORT WAVE TROUGH CURRENTLY OVER THE CENTRAL
PLAINS WILL DRIFT E OF THE MS VALLEY BY SUNDAY NIGHT. THIS PATTERN
WILL RESULT IN AN INCREASE IN CLOUD COVER SATURDAY THROUGH
SUNDAY...AND RAINFALL INCREASING...ESPECIALLY TOWARD THE LATTER
PORTIONS OF THE PERIOD. FOR SATURDAY...THINK THE BEST...ALBEIT
SLIGHT CHANCES...FOR SHOWERS WILL BE ACROSS THE PEE DEE. HOWEVER BY
SUNDAY EXPECT EQUAL CHANCES FOR SHOWERS FOR MOST LOCATIONS WITHIN
THE FORECAST AREA AS A DIFLUENT PATTERN ALOFT TAKES HOLD WITH THE
PASSAGE OF THE MID/UPPER RIDGE AXIS AND APPROACH OF THE
AFOREMENTIONED SHORT WAVE. COULD SEE ISOLATED TSTMS BY SUNDAY
AFTERNOON/EVENING...BUT CONVECTIVE PARAMETERS ARE NOT ALL THAT
IMPRESSIVE AT THIS TIME. QPF MAY APPROACH 1 INCH ACROSS THE PEE DEE
ZONES THEN GRADUATED LOWER TO A THIRD TO HALF OF AN INCH FOR THE
REMAINDER OF THE AREA. OTHERWISE...MAX TEMPERATURES ARE EXPECTED TO
BE A FEW CATEGORIES BELOW NORMAL LACKING ANY SIGNIFICANT WARM AIR
ADVECTION AND INCREASED CLOUD COVER. MIN TEMPERATURES WILL A NOTCH
BELOW CLIMO SATURDAY NIGHT...THEN BE RIGHT AROUND NORMAL FOR SUNDAY
NIGHT.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 315 PM FRIDAY...RETURN FLOW AROUND HIGH PRESSURE OFF THE COAST
WILL CONTINUE TO VEER TO THE S-SW AS SURFACE LOW LIFTS OFF TO THE
GREAT LAKES. SHORTWAVE FOLLOWS SUIT LIFTING NORTHEAST THROUGH THE
OHIO VALLEY AND WEAKENING LATE MONDAY NIGHT INTO TUESDAY. BEST
SHORTWAVE ENERGY WILL MOVE THROUGH ON MONDAY BUT WARM MOIST
SOUTHERLY RETURN FLOW WILL PERSIST THROUGH MONDAY INTO TUESDAY. ONCE
SHORTWAVE TROUGH AXIS SHIFTS OFF THE COAST ON TUES...SHOULD SEE SOME
DRYING AND SUBSIDENCE ON BACK END THROUGH MID WEEK. THIS MAY BE
SHORT-LIVED AS A LOW DEVELOPS ALONG THE GULF COAST AND MAY SEE
MOISTURE RETURN WED INTO THURS. GFS TRACKS LOW ACROSS THE CAROLINAS
THURS NIGHT INTO FRIDAY BUT LIFTS IT OFF TO THE NORTHEAST BY LATE
FRIDAY. THE ECMWF IS MUCH SLOWER WITH THE MOVEMENT OF LOW PRESSURE
MOVING UP FROM THE GULF AND SHOWS THE LOW STILL OVER THE CAROLINAS
ON SUNDAY. WITH SO MUCH UNCERTAINTY...BASICALLY KEPT FORECAST AS IS
WITH A CONSIDERABLE AMOUNT OF CLOUDS AND CHC OF SHWRS/TSTMS THURS
AND FRI.
TEMPS SHOULD RUN BELOW CLIMO MON AND TUES WITH GREATER AMT OF CLOUDS
AND PCP AROUND AND KEEPING TEMPS CLOSER TO CLIMO THROUGH THE
REMAINDER OF THE WEEK FOR NOW.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 06Z...VFR THROUGH THE PERIOD. INCREASING RAIN CHANCES TONIGHT.
HIGH AND MID CLOUDS WILL CONTINUE TO THICKEN ACROSS THE AREA. LATEST
HIGH-RES MODELS INDICATE MODERATE TO HEAVY RAIN ACROSS S TN AND N GA
MAY MAKE A RUN TOWARD THE FLORENCE AIRPORT 10-13Z. I WILL MONITOR
CLOSELY TO SEE IF RAIN NEEDS TO BE ADDED TO OUR TAF FORECAST.
OTHERWISE RAIN CHANCES INCREASE FOR THE INLAND TERMINALS TOWARDS THE
EVENING HOURS...AND THEN FOR THE COASTAL TERMINALS INTO THE
OVERNIGHT HOURS.
EXTENDED OUTLOOK...UNSETTLED WEATHER SATURDAY NIGHT THROUGH TUESDAY
AS AN OVERRUNNING SCENARIO GIVES US MOSTLY CLOUDY CONDITIONS THROUGH
WEDNESDAY WITH PERIODS OF RAIN AND IFR CONDITIONS.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 130 AM SATURDAY...SUSTAINED WINDS ARE AT OR BELOW 15 KNOTS
ACROSS ALL OF THE COASTAL WATERS AND OUT AT THE FRYING PAN SHOALS
BUOY. LATEST HRRR AND RUC NEAR-TERM MODELS HAVE CAPTURED THIS
IMPROVING TREND QUITE WELL AND WERE USED TO MODIFY OUR WIND FORECAST
FOR THE NEXT 9 HOURS. WITH SEAS NOW ONLY 4.9 FEET AT THE FRYING PAN
SHOALS BUOY IT IS UNLIKELY SUBSTANTIAL AREAS OF 5 FOOT SEAS ARE
BEING EXPERIENCED WITHIN 20 MILES OF SHORE. WITH THE MAJORITY OF THE
WAVE ENERGY IN THE LONGER END OF THE ENERGY SPECTRUM...8 TO 11
SECONDS...THE EXERCISE CAUTION HEADLINE HAS BEEN DROPPED WITH THIS
UPDATE.
WIND OBS REPORTED FROM BUOY 41037...THE "OFFSHORE" WRIGHTSVILLE
BEACH BUOY...ARE ABOUT 160% OF THE ACTUAL SUSTAINED WIND AND GUSTS.
THIS HAS BEEN THE CASE FOR AT LEAST THE PAST MONTH. PLEASE USE WITH
CAUTION EVEN AFTER MAKING CORRECTIONS.
SHORT TERM/SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 315 PM FRIDAY...EASTERLY FLOW WILL PREVAIL THROUGH SATURDAY
THEN VEER TO THE SOUTH BY SUNDAY NIGHT AS HIGH PRESSURE MIGRATES OFF
THE MID-ATLANTIC COAST. SPEEDS WILL REMAIN AROUND 10 KT OR AT MOST
IN THE 10-15 KT RANGE THROUGH THE SHORT TERM. WAVES WILL GENERALLY
AVERAGE 3 TO 4 FT...WITH THE HIGHEST VALUES ACROSS THE OUTER COASTAL
WATERS.
LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 315 PM FRIDAY...SHOULD SEE LIGHT RETURN FLOW BETWEEN HIGH
PRESSURE OFF SHORE AND LOW PRESSURE TRACKING NORTHEAST UP INTO THE
GREAT LAKES MON INTO TUESDAY. EXPECT WINDS OUT OF THE S-SE UP TO 15
KTS. ON SHORE FLOW SHOULD KEEP SEAS AROUND 3 TO 4 FT MON AND
TUESDAY. WINDS SHOULD BECOME MORE EASTERLY THROUGH WEDNESDAY AS LOW
PRESSURE BEGINS TO DEVELOP OVER THE GULF COAST. SOME UNCERTAINTY
EXISTS AS TO HOW THIS LOW WILL AFFECT THE COASTAL WATERS. THEREFORE
LOWER CONFIDENCE FORECAST FROM WEDNESDAY ON.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SRP
NEAR TERM...DCH/TRA
SHORT TERM...SRP
LONG TERM...RGZ
AVIATION...SGL/TRA
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
440 AM EDT SAT APR 27 2013
.SYNOPSIS...
AN INCREASINGLY MOIST WEDGE OF COOLER AIR WILL OVERSPREAD THE REGION
THIS WEEKEND AS WEAK LOW PRESSURE MOVES ACROSS THE TENNESSEE VALLEY
ALONG A STALLED COLD FRONT. THE FRONT WILL SLOWLY DISSIPATE AND THE
COOL AIR WEDGE WILL GRADUALLY WEAKEN INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
430 AM UPDATE...ADJUSTED POPS THROUGH DAYBREAK. 06Z NAM DOES NOT
SEEM TO HAVE A GREAT HANDLE ON THE ONGOING PRECIP AROUND THE
REGION...NOT SHOWING ANY ACCUMS FROM THE ACTIVITY IN THE SAVANNAH
RIVER VALLEY. IT DOES CONTINUE TO SUPPORT THE INCREASING POPS NEAR
THE TENN BORDER AFTER SUNRISE. 06Z HRRR SHOWS SOME OF THE CURRENT
ACTIVITY MOVING EAST THEN BRINGS A COUPLE OF WAVES OF SHOWERS ACROSS
BY LATE MORNING. MADE ADJUSTMENTS TO PREVIOUS TREND MOSTLY BASED ON
RADAR MAINLY INTERPRETING THE NEW GUIDANCE AS A CONFIDENCE BOOST.
AS OF EARLY SAT MORNING...SFC HIGH OVER NE CONUS SEEN ON CURRENT SFC
ANALYSIS SITS IN A FAVORABLE POSITION TO ALLOW DEVELOPMENT OF CAD
ACROSS OUR REGION DURING THE NEAR TERM PERIOD. LLVL WINDS ABOVE THE
BOUNDARY LAYER ARE ALREADY SOUTHERLY. THROUGH THE DAY TODAY MIDLEVEL
RIDGE SHIFTS SLIGHTLY EASTWARD AS CLOSED UPPER LOW GROWS OVER THE MID
MISSISSIPPI VALLEY. THE EFFECT WILL BE TO STRENGTHEN THE FLOW OVER
THE CAD WEDGE LEADING TO A SOMEWHAT STEADY INCREASE IN ISENTROPIC
LIFT AND DEEP MOISTURE ADVECTION. MEANWHILE...EXTRA SUPPORT FOR
PRECIP DEVELOPMENT WILL COME FROM VORT MAXES ROUNDING THE SUBTLE
UPPER RIDGE AHEAD OF THE CLOSED LOW. ONE AREA OF PVA IS EXPECTED TO
SPREAD ITS ASSOCIATED PRECIP INTO THE MTNS AROUND DAYBREAK WHILE A
SECOND...SHOWN ON BOTH GFS AND NAM...WILL MOVE THROUGH THIS
AFTERNOON. THAT FEATURE IS CONCURRENT WITH RIGHT REAR QUAD OF 250MB
JET STREAK AND ASSOCIATED DIVERGENCE. UPPER SUPPORT WANES SOMEWHAT ON
GFS THIS EVENING...BUT NAM FEATURES MCV/S MOVING IN AT THAT TIME.
THESE ARE PROBABLY RESULTING FROM CONVECTION UPSTREAM...SO NOT
NECESSARILY BITING ON ANY MODELED EFFECTS FROM THOSE. MIDLEVEL
Q-VECTOR CONVERGENCE DOES CONTINUE TO INCREASE AS HEIGHTS FALL OVER
THE TENN VALLEY AHEAD OF THE UPPER LOW AND AS THE WARM ADVECTION
RAMPS UP.
HAVE NOT MADE MUCH CHANGE TO POP TRENDS WHICH GENERALLY SPREAD WEST
TO EAST DURING THE PERIOD...WITH CATEGORICAL VALUES APPROPRIATE OVER
THE NW HALF OF CWA /WHERE UPSLOPING WILL PLAY THE BIGGEST ROLE AND
ALSO FEATURING THE BEST UPPER SUPPORT/. QPF COULD BE CRITICAL FOR
THIS EVENT AS A WHOLE SO GAVE IT SOME EXTRA THOUGHT. GFS IS THE MOST
ROBUST WITH THE ACTIVITY THIS AFTERNOON WHICH MAKES SENSE GIVEN ITS
EVOLUTION OF THE UPPER FORCING...AND FEATURES LOWER QPF FOR EVENING
BUT WITH SOME INCREASE AGAIN TOWARD SUN MORNING AS THE MOISTURE
DEEPENS. GENERALLY THE DETERMINISTIC TOTALS ARE BACKED UP BY THE
ACCUM PROBABILITIES PRODUCED BY THE ENSEMBLE RUN. CHOSE TO USE A
BLEND OF AVAILABLE DETERMINISTIC GUIDANCE BUT WITH A BIAS TOWARD THE
GFS.
TEMPS TODAY WILL BE BELOW NORMAL GIVEN THE CLOUD COVER AND DEVELOPING
WEDGE...BUT IF PRECIP IS DELAYED OR DOES NOT DEVELOP OVER A
WIDESPREAD AREA TEMPS COULD BE SOMEWHAT WARMER WITHOUT THE RAINFALL
TO LOCK IN THE WEDGE EARLY. WENT WITH RAW MODEL BLEND FOR TONIGHT
ASSUMING THE WEDGE WILL BE FULLY ENTRENCHED BY THEN.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 240 AM SATURDAY...AS THE UPPER RIDGE AXIS SHIFTS TO THE
COAST...AND DEEP/VERY MOIST SW FLOW BECOMES ESTABLISHED OVER THE
AREA...POPS WILL CONTINUE TO INCREASE THROUGH SUNDAY WITHIN MODESTLY
STRONG WAA/SOUTHERLY UPSLOPE REGIME. WITH THE CENTER OF THE SURFACE
HIGH EXPECTED TO SHIFT OFF THE NEW ENGLAND COAST BY SUNDAY...IN SITU
COLD AIR DAMMING WILL LIKELY BEGIN TO ERODE AROUND THE PERIPHERY OF
THE FORECAST AREA...ESP THE SOUTHERN PIEDMONT AND FAR SOUTHWEST MTN
ZONES. THIS WILL CREATE THE POTENTIAL FOR INCREASED INSTABILITY/
DEEPER CONVECTION/INCREASED RAINFALL RATES BY AFTERNOON. IN FACT...
SUNDAY AFTERNOON THROUGH SUNDAY NIGHT APPEARS TO BE THE MOST LIKELY
PERIOD OF HEAVY RAINFALL IN LIGHT OF THIS TIME OFFERING THE BEST
JUXTAPOSITION OF UPSLOPE FLOW...INSTABILITY/ MOISTURE...AS WELL AS
INCREASING UPPER LEVEL FORCING. THE LATTER COMES ABOUT AS A RESULT
OF A COUPLED JET STRUCTURE THAT MAXIMIZES SUNDAY EVENING. AREAS
ALONG THE SOUTHERN BLUE RIDGE COULD WELL SEE WIDESPREAD RAINFALL
AMOUNTS OF TWO INCHES WITHIN THIS WINDOW OF TIME ALONE. STORM TOTAL
AMOUNTS OF 2.5 TO 4 INCHES APPEAR TO BE A VERY GOOD BET THROUGH
SUNDAY NIGHT...AND CONFIDENCE IS INCREASING THAT WE MAY HAVE LOCALLY
EXCESSIVE RAINFALL CONCERNS ALONG OUR SOUTHERN BLUE RIDGE COUNTIES.
NEVERTHELESS...I STILL THINK WE ARE AROUND 48 HOURS AWAY FROM SEEING
ANY HYDRO CONCERNS...AND I WOULD LIKE TO SEE HOW TODAY/S RAINFALL
SITUATION UNFOLDS BEFORE HOISTING A WATCH...SO HAVE OPTED TO PUNT TO
THE DAY SHIFT.
BY MONDAY...THE BEST UPPER FORCING AND DEEP MOISTURE WILL SHUNT EAST
OF THE AREA. HOWEVER...SOUTHERLY FLOW WILL PERSIST IN THE LOWER
LEVELS...SUPPORTING AMPLE LOW LEVEL MOISTURE. IN FACT...WITH THE AIR
MASS DRYING SOMEWHAT ALOFT...WE MAY SEE MORE SUN/INSTABILITY MONDAY
AFTERNOON. WITH THE UPPER TROUGH/SHEAR AXIS LINGERING OVER THE
AREA...SOLID CHANCE/LOW LIKELY POPS ARE WARRANTED INTO THE
AFTERNOON. CONVECTION SHOULD BECOME MORE DIURNAL IN NATURE BY THE
END OF THE SHORT TERM PERIOD...SO POPS GRADUALLY TAPER DOWN MONDAY
EVENING.
MAX TEMPERATURES WILL REMAIN BELOW NORMAL SUNDAY UNDER WIDESPREAD
CLOUD COVER AND PRECIPITATION...BUT RETURN TO NEAR CLIMO BY MONDAY.
LOWS WILL BE AT LEAST A CATEGORY ABOVE CLIMO THROUGH THE PERIOD.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 305 AM SATURDAY...THE MEDIUM RANGE CONTINUES TO APPEAR
UNSETTLED...AS PERSISTENT SOUTH TO SE FLOW MAINTAINS A FETCH OF LOW
LEVEL MOISTURE INTO THE REGION...SUPPORTING MAINLY DIURNAL CHANCES
FOR SHOWERS AND THUNDERSTORMS. THE GLOBAL MODELS CONTINUE TO
ADVERTISE A REASSERTION OF THE EASTERN LOW LEVEL RIDGE AXIS DURING
MID-LATE WEEK. HOWEVER...THEY ARE NOT AS AGGRESSIVE IN DRYING OUT
THE LOWER LEVEL AIR MASS OVER THE CAROLINAS. THERE IS ALSO
CONSIDERABLE UNCERTAINTY REGARDING THE TIMING OF THE NEXT MAJOR
STORM SYSTEM...AS THE PRIMARY GLOBAL MODELS ARE VERY MUCH AT ODDS IN
THEIR HANDLING OF WESTERN CONUS ENERGY LATE IN THE WEEK.
THEREFORE...SLIGHT/CHANCE POPS AND NEAR-CLIMO TEMPS WILL REMAIN IN
THE FORECAST THROUGH THE EXTENDED RANGE PERIOD.
&&
.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT /09Z UPDATE/...MIDLEVEL CLOUDS NOW OVERHEAD SHOULD REMAIN
VFR THROUGH DAYBREAK AND KEEP DEWPOINT DEPRESSIONS FAR TOO LARGE FOR
ANY FOG RISK. WEAK AREA OF LOW PRESSURE OVER SW VA ASSOCIATED WITH
PASSING UPPER DISTURBANCE PRODUCING A LIGHT SOUTHERLY WIND ATTM WITH
MOST SITES NEARBY BEING CALM. SLY FLOW WILL CONTINUE TO PREVAIL WITH
HIGH PRESSURE OVER THE MID ATLANTIC COAST HELPING TO DEVELOP COLD
AIR DAMMING AND COOL SFC WEDGE. SOUTHERLY FLOW OVER THE WEDGE IS
FAIRLY CONSTANT THROUGH THE PERIOD...BUT BETTER UPPER FORCING AND
DEEPENING MOISTURE WILL LEAD TO INCREASING PRECIP CHANCES AND
LOWERING CIGS BY AFTERNOON...THEN SUFFICIENTLY HIGH FOR A PROB30
SATURDAY EVENING. MODEL CONSENSUS MAINTAINS LOW VFR CIGS THROUGH THE
EVENING BUT THERE IS A CHANCE THEY MAY DROP TO MVFR JUST BEFORE 06Z.
ELSEWHERE...SHOWERS WILL CONTINUE TO DEVELOP THRU THE TAF
PERIOD...WITH RESTRICTIONS BECOMING INCREASINGLY LIKELY...AS WARM
AIR AND MOISTURE ADVECT OVER A WEDGE OF COLD AIR AT THE SURFACE.
SITUATION IS COMPLICATED BY ACTIVE UPPER ATMOSPHERE WHICH WILL
PROVIDE ADDITIONAL LIFT AND ENHANCE PRECIP/CLOUD PRODUCTION AT
TIMES. DO THINK RESTRICTIONS WILL NOT BE SEEN THRU DAYBREAK WITH
MOST OF THE UPSTREAM ACTIVITY MAINTAINING LOW VFR EVEN IN
SHOWERS...THOUGH AS BETTER UPPER SUPPORT MOVES IN TODAY MVFR SHOULD
SETTLE IN ACROSS THE WESTERN PORTIONS OF THE AREA. MVFR CIGS AT KAVL
BY AFTERNOON...AND AT KAND BY EVENING. GUIDANCE SUGGESTS SHOWERS MAY
BRING MVFR VSBY. CONDITIONS WILL GENERALLY CONTINUE TO WORSEN THRU
THE END OF THE PERIOD. MAINLY NE TO ENE WINDS WILL PREVAIL WITH THE
WEDGE IN CONTROL.
OUTLOOK...A WEDGE OF COLD AIR WILL PERSIST ACROSS THE REGION SUNDAY
AND MONDAY. PERIODIC PRECIPITATION INTO THIS WEDGE WILL CREATE THE
POSSIBILITY OF FLIGHT RESTRICTIONS.
CONFIDENCE TABLE...
08-14Z 14-20Z 20-02Z 02-08Z
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 96%
KGSP HIGH 100% HIGH 100% MED 74% MED 60%
KAVL HIGH 93% MED 70% MED 77% HIGH 90%
KHKY HIGH 100% HIGH 98% HIGH 80% MED 75%
KGMU HIGH 100% HIGH 100% MED 75% MED 67%
KAND HIGH 100% HIGH 100% MED 75% LOW 58%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...CSH
NEAR TERM...WIMBERLEY
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
450 AM CDT SAT APR 27 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 450 AM CDT SAT APR 27 2013
CLEAR SKIES AND WARM TEMPERATURES ON TAP AGAIN FOR TODAY... WITH
TEMPERATURES/HUMIDITY LEVELS THE PRIMARY CHALLENGE OF THE DAY. IN
THE IMMEDIATE TERM...DID ADD SOME PATCHY FOG TO OUR FAR SOUTHEAST
AREAS EARLY THIS MORNING. HIGHER DEW POINTS HAVE BEEN PERSISTING
SOUTH OF WEAKENING RIDGE AXIS OVERNIGHT...AND CAN SOMEWHAT SEE THE
MOISTURE DISCONTINUITY ROUGHLY SOUTH OF VERMILLION TO SPENCER IOWA
LINE ON THE IR SATELLITE IMAGERY THIS MORNING. ANY FOG EXPECTED TO
BE RELATIVELY SHALLOW GIVEN DEVELOPMENT THIS LATE IN THE OVERNIGHT
SO EXPECT IT TO DISSIPATE QUICKLY AS TEMPERATURES BEGIN TO RISE.
WITH SUNSHINE...DEEP DRY ATMOSPHERE...AND RELATIVE DRY GROUND
OUTSIDE THE AREAS WITH MOST RECENT SNOW MELT...TEMPERATURES HAVE BEEN
MIXING TO THE FULLEST AND SEE NO REASON WHY THAT WOULD NOT OCCUR
AGAIN TODAY. THUS HAVE WARMED HIGHS TODAY A LITTLE ABOVE MOST
GUIDANCE...RANGING FROM AROUND 70 OVER THE REMAINING SNOW COVER
ALONG THE BUFFALO RIDGE TO AROUND 80S IN THE WESTERN THIRD OF THE
CWA.
BOUNDARY LAYER DRYING ALSO AN ISSUE...PRIMARILY FOR FIRE WEATHER
CONCERNS. SIMILAR TO YESTERDAY...WOULD EXPECT DRIER AIR TO MIX DOWN
TO THE SURFACE THROUGH THE AFTERNOON. MODELS DID NOT SEEM TO HAVE A
GREAT TRACK RECORD ON DROPPING DOWN THE AFTERNOON DEW POINTS WITH
MIXING YESTERDAY...AND LOOKS LIKE SIMILAR DIFFICULTY MAY BE SEEN
TODAY WITH NAM FORECAST SOUNDINGS SEEMING TO MIX THE SOMEWHAT MORE
MOIST BOUNDARY LAYER UPWARD INSTEAD OF MIXING THE DEEPER DRY AIR
ALOFT DOWNWARD. RAP MODEL SOUNDINGS SEEM TO BETTER REFLECT THIS
THINKING...AND MODEL DEW POINTS RESPOND ACCORDINGLY AND FOLLOWED
THESE MORE CLOSELY FOR DEW POINT/HUMIDITY TRENDS LATER THIS MORNING
THROUGH THE AFTERNOON. THIS WILL RESULT IN HIGH FIRE DANGER ACROSS
OUR WESTERN FORECAST AREA THIS AFTERNOON...BUT WINDS SHOULD BE LIGHT
ENOUGH TO KEEP BELOW VERY HIGH CATEGORY.
START TO SEE SOME INCREASE IN CLOUDS ACROSS OUR NORTHWEST LATER
TONIGHT IN ADVANCE OF UPPER WAVE/ASSOCIATED WEAK COLD FRONT MOVING
INTO THE NORTHERN PLAINS. VERY MILD LOW LEVEL AIR ALONG WITH LIGHT
SOUTHERLY FLOW SHOULD KEEP TEMPERATURES WELL ABOVE NORMAL WITH LOWS
IN THE 40S TO NEAR 50.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 450 AM CDT SAT APR 27 2013
A LITTLE MORE ACTIVE PATTERN SETS UP EARLY NEXT WEEK...INITIALLY
WITH A CHANCE OF LATE AFTERNOON/EVENING SHOWERS OR THUNDERSTORMS
ACROSS OUR EAST SUNDAY AS THE COOL FRONT SLIDES THROUGH A SOMEWHAT
MORE MOIST ATMOSPHERE...THEN WITH A BETTER CHANCE OF RAIN LATER
SUNDAY NIGHT ALONG AND SOUTH OF I-90 AS MID LEVEL MOVES THROUGH THE
REGION. SUNDAY SHOULD BE ANOTHER WARM DAY...LIKELY THE WARMEST OF
THIS STRETCH OVER OUR SOUTHERN AREAS...WHILE THE NORTH SHOULD SEE
TEMPERATURES PEAK MORE IN THE MIDDAY/EARLY AFTERNOON WITH COOLING
THROUGH THE LATER AFTERNOON AS COLD ADVECTION SETS IN AND CLOUDS
INCREASE.
MONDAY WILL BE SLIGHTLY COOLER BEHIND THE FRONT...WITH JUST A CHANCE
OF LINGERING LIGHT RAIN IN OUR FAR SOUTHEAST IN THE MORNING AND
SKIES BECOMING MOSTLY SUNNY AGAIN BY AFTERNOON. WARM RETURN FLOW
QUICKLY SETS LATE MONDAY AFTERNOON/EVENING AND WHILE MID LEVEL
SHOWERS/THUNDERSTORMS ARE POSSIBLE ON THE NOSE OF LOW LEVEL JET...
THIS LOOKS TO BE FOCUSED TO OUR NORTH AND WILL KEEP OUR AREA DRY
THROUGH MONDAY NIGHT.
SHARP COLD FRONT THEN MOVES THROUGH LATE MONDAY NIGHT/TUESDAY...
THOUGH STRONG MIXING BEHIND THE FRONT SHOULD STILL KEEP HIGHS ON
TUESDAY NEAR TO SLIGHTLY ABOVE NORMAL IN THE 60S TO LOWER 70S. 850MB
FRONT STALLS JUST SOUTHEAST OF OUR AREA TUESDAY NIGHT WHILE STRONGER
UPPER TROUGH SWINGS OUT OF THE ROCKIES. THIS WILL BRING INCREASING
RAIN CHANCES TO THE AREA TUESDAY NIGHT INTO WEDNESDAY...MAINLY IN
OUR SOUTHEAST.
SECONDARY COLD FRONT ASSOCIATED WITH THIS WAVE WILL BRING A RETURN
TO BELOW NORMAL TEMPERATURES FROM WEDNESDAY THROUGH THE END OF THE
WEEK. LONG RANGE MODELS VASTLY DIFFERENT ON EVOLUTION OF UPPER
TROUGH AFTER IT PASSES THROUGH OUR AREA WEDNESDAY. GFS DEVELOPS A
CUTOFF LOW OVER THE WESTERN OHIO VALLEY WHILE THE ECMWF BUILDS A
MUCH STRONGER RIDGE OVER THE GREAT LAKES WHICH FORCES THE UPPER LOW
TO DEVELOP OVER THE CENTRAL PLAINS. FORMER WOULD KEEP US DRY THROUGH
THE END OF THE WEEK...WHILE THE LATTER RESULTS IN QUITE A WET PERIOD
FOR PARTS OF THE REGION. GIVEN HIGH DEGREE OF UNCERTAINTY...WILL
KEEP THE LATTER HALF OF THE WEEK DRY FOR NOW...ASIDE FROM LINGERING
LOW CHANCE OF PRECIPITATION IN OUR FAR SOUTHEAST WEDNESDAY NIGHT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1032 PM CDT FRI APR 26 2013
VFR THROUGH 06Z SUNDAY.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...JH
LONG TERM...JH
AVIATION...
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
417 AM CDT SAT APR 27 2013
...SLIGHT RISK OF SEVERE STORMS THIS AFTERNOON AND TONIGHT...
...WIDESPREAD RAIN AND THUNDERSTORMS TO CONTINUE THIS WEEKEND...
.SHORT TERM...
LATEST RADAR IMAGERY SHOWS WIDESPREAD LIGHT TO MODERATE RAIN
CONTINUES ACROSS MOST OF THE FORECAST AREA...WITH MORE ISOLATED
SHOWERS ACROSS WAYNE/LAWRENCE/GILES COUNTIES. PRECIPITATION
IS BEING AIDED BY A WEAK SHORTWAVE TROUGH EVIDENT ACROSS EASTERN
TENNESSEE...AND IS FOCUSED ALONG AND NORTH OF A 850 MB WARM FRONT
THAT CURRENTLY EXTENDS FROM DYERSBURG TO WINCHESTER. PRECIPITATION
WILL CONTINUE TO BE GENERATED TODAY DUE TO SUSTAINED WAA ABOVE
THE FRONTAL SURFACE...WITH RENEWED DEVELOPMENT TO OUR WEST AS THE
NEXT WEAK SHORTWAVE CURRENTLY SEEN ALONG THE MISSISSIPPI RIVER
APPROACHES. INDEED...MOSAIC RADAR IMAGERY SHOWS A LARGE AREA OF
SHOWERS AND THUNDERSTORMS HAS ALREADY REDEVELOPED IN WESTERN
TENNESSEE WHICH WILL MOVE ACROSS THE CWA LATER THIS MORNING.
HEAVIEST ACTIVITY IS EXPECTED TO BE IN AN ARC FROM NORTHWEST TO
SOUTHEAST ACROSS THE CENTER OF THE CWA...WITH FAR SOUTHWEST AND
NORTHEAST AREAS SEEING MORE SCATTERED ACTIVITY.
BY AFTERNOON...SOME GLOBAL AND MESOSCALE MODELS DEPICT A BREAK IN
THE WIDESPREAD RAINFALL AS SHORTWAVE CURRENTLY ALONG THE MS RIVER
MOVES OFF TO THE EAST. HAVE THUS LOWERED POPS INTO THE LIKELY
CATEGORY THIS AFTERNOON...BUT REMAINS UNCERTAIN HOW MUCH OF A
BREAK WILL BE SEEN AS OTHER MODELS SUCH AS THE HRRR CONTINUE
PRECIPITATION NONSTOP. REGARDLESS...MAIN UPPER LOW SEEN ON WATER
VAPOR IMAGERY ACROSS OK/KS WILL APPROACH THE MISSISSIPPI RIVER
LATER THIS AFTERNOON AND EVENING. AS THIS OCCURS...A WEAK SURFACE
LOW IS PROGGED BY MODELS TO DEVELOP IN NORTHEAST ARKANSAS THEN
MOVE NORTHEAST INTO SOUTHERN KENTUCKY TONIGHT. STRENGTHENING WIND
FIELDS AND HIGHER SURFACE DEWPOINTS ADVECTING NORTHWARD COMBINED
WITH SOME DIURNAL HEATING SHOULD ALLOW FOR DESTABILIZATION OF THE
LOWER LEVELS OVER WESTERN ZONES. ALL GUIDANCE DEVELOPS ADDITIONAL
SHOWERS AND THUNDERSTORMS LATER THIS AFTERNOON AND EVENING ACROSS
WEST TENNESSEE AND NORTH MISSISSIPPI WHICH THEN MOVE INTO THE MID
STATE THROUGH SATURDAY NIGHT. FORECAST SOUNDINGS SHOW WEAK TO
MODERATE INSTABILITY/SHEAR WITH RELATIVELY COLD MID
LEVELS LATER TODAY...SUGGESTING DAMAGING WINDS AND LARGE HAIL
WOULD BE POSSIBLE WITH THE STRONGEST STORMS. INDEED...MESOSCALE
MODELS SHOW SOME ROBUST STORMS IN OUR WESTERN COUNTIES AROUND 00Z
THIS EVENING. SPC HAS UPGRADED PORTIONS OF WESTERN ZONES INTO A
SLIGHT RISK FOR THIS AFTERNOON AND TONIGHT. EASTWARD EXTENT OF ANY
SEVERE ACTIVITY THAT MAY DEVELOP WILL BE GREATLY LIMITED BY MORE
STABLE CONDITIONS EAST OF THE SLIGHT RISK AREA.
GUIDANCE DEPICTS A DRY SLOT ALOFT ADVANCING ACROSS WESTERN
PORTIONS OF THE MID STATE ON SUNDAY AS UPPER LOW ADVANCES THROUGH
THE OHIO VALLEY. THIS WILL LOWER PRECIP CHANCES OVER THE WEST WITH
HIGH POPS CONTINUING OVER THE EAST. ALL ACTIVITY SHOULD WIND DOWN
BY SUNDAY NIGHT AS UPPER LOW MOVES EAST OF THE REGION. TOTAL
RAINFALL AMOUNTS FOR THIS WEEKEND RAIN EVENT APPEAR TO BE IN THE 1
TO 2 INCH RANGE NORTH OF I-40 WITH 2 TO 3 INCHES SOUTH OF
I-40...BUT SOME 4 INCH AMOUNTS ARE POSSIBLE WITH ANY SUSTAINED
HEAVIER THUNDERSTORMS. ALTHOUGH NO WIDESPREAD FLASH FLOODING IS
EXPECTED...SOME LOCALIZED FLOODING IS CERTAINLY POSSIBLE AND
RUNOFF INTO AREA RIVERS MAY RESULT IN SOME RISING INTO ACTION
STAGE NEXT WEEK.
.LONG TERM...
WARMER AND DRIER WEATHER IS ANTICIPATED FOR MONDAY AND TUESDAY AS
WEAK RIDGING ALOFT BUILDS OVER THE TENNESSEE VALLEY REGION. LOW
PRECIP CHANCES RETURN BY WEDNESDAY AS A WEAK UPPER LOW DEVELOPS
IN THE GULF COAST STATES. FOR THE END OF THE FORECAST
PERIOD...00Z GFS/ECMWF HAVE CONTINUED THE HIGHLY ANOMALOUS TREND
OF THE PAST FEW DAYS IN DEVELOPING A LARGE AND INTENSE CUT OFF H5
LOW WHICH THEN MEANDERS FOR DAYS ACROSS THE EASTERN CONUS.
UNFORTUNATELY...GFS AND ECMWF DIFFER BY 600 MILES ON THEIR
PLACEMENT OF THE UPPER LOW WHICH RESULTS IN TEMPERATURE
DIFFERENCES OF 20 DEGREES OR MORE FOR HIGHS AND LOWS. FOR NOW
WILL GO WITH LOW POPS FOR THE END OF NEXT WEEK AND TREND
TEMPERATURES TOWARDS THE COLDER MEX GUIDANCE...ALTHOUGH FORECAST
IN THE LONG RANGE SHOULD BE CONSIDERED EXTREMELY LOW CONFIDENCE.
&&
.PRELIMINARY POINT TEMPS/POPS...
NASHVILLE 65 57 73 55 / 100 80 50 10
CLARKSVILLE 64 57 72 52 / 100 80 40 05
CROSSVILLE 60 54 67 53 / 100 80 70 30
COLUMBIA 68 58 73 55 / 100 80 50 10
LAWRENCEBURG 70 59 73 54 / 80 80 50 20
WAVERLY 66 57 71 52 / 100 80 40 0
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHAMBURGER
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
155 AM EDT SAT APR 27 2013
.SYNOPSIS...
HIGH PRESSURE ACROSS THE REGION TONIGHT WILL DRIFT OFF THE MID-
ATLANTIC COAST AS AN UPPER DISTURBANCE MOVES EAST FROM THE MID-
MISSISSIPPI VALLEY INTO THE SOUTHERN APPALACHIANS. THIS SYSTEM
WILL SLOW AND LINGER ACROSS THE REGION THROUGH THE MID-PART OF
NEXT WEEK...KEEPING CLOUDS...LIGHT RAIN...AND UNSEASONABLY COOL
TEMPERATURES IN PLACE. A NEW WEATHER SYSTEM WILL APPROACH FROM THE
WEST BY THE END OF NEXT WEEK WITH MORE SHOWERS AND POSSIBLY A FEW
THUNDERSTORMS.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 840 PM EDT FRIDAY...
SOUNDINGS SHOW VERY DRY AIR CONTINUING ESPCLY IN THE LOWER LEVELS
THIS EVENING WITH MOST ADVECTION OF MOISTURE COMING FROM THE WEST
ATTM. THIS DRY AIR HAS BASICALLY DRIED UP THE INITIAL BATCH OF
PRECIP HEADING IN FROM THE WEST WITH THE FIRST FAINT WAVE...WHILE
HAVE ANOTHER WEAK ARC OF ENERGY SET TO ARRIVE FROM TN/KY OVER THE
FAR WEST LATE. LATEST RAP PICKS UP ON THIS AFTER MIDNIGHT AND HAS
SOME SPOTTY -RA OVER THE NW NC RIDGES...AND AREAS WEST OF I-77 IN
VA LATE. MOST OTHER SHORT TERM GUIDANCE QUITE DRY SO ONLY
INCLUDING A SLIGHT POP FOR VERY -RA EXTREME SW BY DAWN. OTRW WILL
SEE VARYING AMOUNTS OF HIGH/MID CLOUDS...WITH A THICKER MID DECK
CANOPY DEVELOPING OVERNIGHT WEST...AND SOME THIN SPOTS OVER THE
NORTH/EAST. BUMPED UP LOW TEMPS A BIT SW DUE TO THICKER CLOUDS
WITH MOST SPOTS IN THE 40S BY MORNING...EXCEPT SOME 30S DEEPER
VALLEYS ACROSS THE NORTH.
HIGH PRESSURE WILL MOVE EAST OFF THE NEW ENGLAND COAST ON SATURDAY.
AN APPROACHING SHORTWAVE COMBINED WITH EASTERLY FLOW WILL INCREASE
MOISTURE ACROSS OUR REGION SATURDAY. PLACED THE HIGHEST POPS ON
SATURDAY ALONG THE SOUTHERN BLUE RIDGE MOUNTAINS...WITH LIGHTER
CHANCES IN THE EAST. HIGH SATURDAY VARY FROM THE LOW 50S ACROSS THE
SOUTHWEST MOUNTAINS TO AROUND 70 IN THE PIEDMONT. A FASTER SPREAD OF
MOISTURE COULD TRIM HIGHS SATURDAY MORE WITH ADDITIONAL CLOUD COVER
AND RAIN.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
AS OF 345 PM EDT FRIDAY...
ECMWF/GFS IN GENERAL AGREEMENT ON THE EVOLUTION OF THE PATTERN
SUN THROUGH MON...BUT CONTINUE TO DIFFER ON TIMING. HOWEVER...MOST
OF THE TIMING ISSUES APPEAR TO BE RESOLVED BY THE BEGINNING OF THE
SHORT TERM PERIOD. THIS PERIOD CAN BEST BE CHARACTERIZED AS A
RATHER CONTINUOUS PERIOD OF LIGHT RAIN AS A SOUTHERN STREAM
DISTURBANCE SPREADS THROUGH THE REGION IN A FAVORABLE WEDGE AREA.
THE WEDGE WILL BE ENHANCED/REINFORCED AS THE PCPN FALLS INTO AN
INITIALLY DRY/COOL SFC AIR MASS. QPF THROUGH THE PERIOD SHOULD
RANGE FROM 0.25 INCH IN THE NE PART OF THE CWA TO PERHAPS NEAR AN
INCH IN THE NW NC MOUNTAINS AND FAR SW VA. BY SUN AFTERNOON...THE
WEDGE MAY ERODE ENOUGH ALONG THE WESTERN EDGE...FROM MERCER COUNTY
WV DOWN TOWARD NE TN TO SUPPORT ISOLD TSRA WITH DIURNAL HEATING.
THUS...HAVE REINTRODUCED THE MENTION OF TSRA ALONG OUR WESTERN
BORDER. EASTERN AREAS SHOULD REMAIN TOO STABLE/COOL TO SUPPORT
TSRA THROUGH THE SHORT TERM. HAVE NOT INCLUDED ANY MENTION OF DZ
THIS PERIOD AS WITH -RA LIKELY...IT JUST ADDS CONFUSION TO THE
PUBLIC FORECAST. TEMPERATURES WILL BE UNSEASONABLY COOL THROUGH
THE PERIOD WITH HIGHS IN THE 50S SUN ACROSS MUCH OF THE
REGION...EXCEPT THE PERIPHERY OF THE CWA WHERE IT WILL BE IN THE
60S. HAVE LEANED HEAVILY TOWARD THE MUCH COOLER ECMWF MOS THROUGH
THE PERIOD.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
CONSIDERABLE QUESTIONS REMAIN WITH RESPECT TO THE EVOLUTION OF
WEATHER FEATURES WITH THE EXTENDED PERIODS...ESPECIALLY THE LATER
PERIODS. THE BIG QUESTION...AS HAS BEEN THE CASE FOR DAYS NOW...IS
THE DEVELOPMENT/MOVEMENT/POSITION OF A POTENTIAL CLOSED UPPER LOW.
ECMWF/GFS CONTINUE TO COVER THE ENTIRE SPECTRUM WITH RESPECT TO
THE DETAILS. THUS...THERE IS LITTLE TO NO RELIABILITY OR
CONFIDENCE IN THE EXTENDED FORECAST...ESPECIALLY THE LATER
PERIODS. AT THE BEGINNING OF THE EXTENDED PERIODS...TUE-
WED...STILL DEALING WITH A LINGERING WEDGE ACROSS THE EASTERN
SECTIONS. GIVEN THE PERSISTENT PATTERN THIS PAST WINTER AND SPRING
SO FAR...HAVE LEANED HEAVILY TOWARD THE ECMWF WHICH IS MUCH SLOWER
TO ERODE THE WEDGE. BETTER PCPN CHANCES WITH BOTH THE GFS/ECMWF
SHIFT SOUTH AND EAST OF THE CWA EARLY...WITH PCPN TRENDING TOWARD
A MORE DIURNAL PATTERN FOCUSING ALONG THE MOUNTAINS IN AREAS OF
BETTER DIFFERENTIAL HEATING. TEMPERATURES SHOULD SLOWLY WARM
TOWARD MORE SEASONAL LEVELS...BUT LIKELY WILL REMAIN JUST BELOW
NORMAL THROUGH THE NEW RIVER VALLEY...SHENANDOAH VALLEY...AND
GREENBRIER VALLEY. DURING THE FINAL DAYS OF THE EXTENDED...NAMELY
THU-FRI...HAVE GONE NEARLY ENTIRELY WITH THE 00Z/12Z ECMWF
SOLUTION AND COMPLETELY IGNORED THE GFS SOLUTION OF A VERY DEEP
CLOSED LOW THROUGH THE SOUTHERN ABLUTIONS WITH ATTENDANT HEAVY
RAIN FOLLOWED BY SNOW AND RIDICULOUSLY COLD TEMPERATURES FOR
EARLY MAY. THE ECMWF OFFERS A MUCH MORE PLAUSIBLE FORECAST FROM
ALL ASPECTS...QPF...POPS...AND TEMPS. A COLD FRONT ON THE FORWARD
FLANK OF ANY LOW PRESSURE AREA ACROSS THE UPPER MID-WEST/OH VALLEY
MAY BEGIN TO APPROACH THE AREA BY SAT WITH INCREASING CHANCES OF
SHRA/TSRA AT THAT TIME.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 140 AM EDT SATURDAY...
CEILINGS WILL GRADUALLY LOWER THROUGHOUT THE DAY. DO NOT EXPECT
MVFR CEILINGS UNTIL WELL AFTER 00Z/8PM THIS EVENING. AS LOW
PRESSURE MOVES ACROSS THE SOUTHERN MISSISSIPPI VALLEY...FORCING
AND INFLOW OF MOISTURE OVER THE SOUTHERN APPALACHIANS WILL GREATLY
INCREASE. RAIN WILL OVERSPREAD THE AREA BEFORE 12Z/8AM SUNDAY.
THIS SHOULD RESULT IN MVFR/IFR CIGS AND VSBYS...ESPECIALLY IN THE
MOUNTAINS DUE TO LIGHT TO MODERATE RAIN.
FLYING WEATHER WILL REMAIN POOR FOR THE NEXT SEVERAL DAYS. SURFACE LOW
PRESSURE WILL MOVE OUT OF THE PLAINS AND INTO THE OHIO VALLEY...
WEAKENING AS IT GOES. NET RESULT WILL BE MOIST SOUTH FLOW AND
PERIODS OF PCPN...LOW CLOUDS AND SUB VFR VISIBILITIES OVER THE
AREA THROUGH MONDAY. HIGH PRESSURE WILL THEN WEDGE DOWN THE ERN
SEABOARD FOR TUESDAY AS A STRONG COLD FRONT APPROACHES ON
WEDNESDAY. MVFR WITH PERIODS OF IF ARE LIKELY FOR MUCH OF NEXT
WEEK.
&&
.EQUIPMENT...
OBSERVATION FROM AUTOMATED EQUIPMENT AT THE VIRGINIA TECH
AIRPORT...KBCB...WAS EXPERIENCING COMMUNICATION PROBLEMS. THIS
OBSERVATION WILL BE UNAVAILABLE UNTIL FURTHER NOTICE.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS/RAB
NEAR TERM...JH/KK
SHORT TERM...RAB
LONG TERM...RAB
AVIATION...AMS
EQUIPMENT...AMS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
144 AM EDT SAT APR 27 2013
.SYNOPSIS...
HIGH PRESSURE ACROSS THE REGION TONIGHT WILL DRIFT OFF THE MID-
ATLANTIC COAST AS AN UPPER DISTURBANCE MOVES EAST FROM THE MID-
MISSISSIPPI VALLEY INTO THE SOUTHERN APPALACHIANS. THIS SYSTEM
WILL SLOW AND LINGER ACROSS THE REGION THROUGH THE MID-PART OF
NEXT WEEK...KEEPING CLOUDS...LIGHT RAIN...AND UNSEASONABLY COOL
TEMPERATURES IN PLACE. A NEW WEATHER SYSTEM WILL APPROACH FROM THE
WEST BY THE END OF NEXT WEEK WITH MORE SHOWERS AND POSSIBLY A FEW
THUNDERSTORMS.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 840 PM EDT FRIDAY...
SOUNDINGS SHOW VERY DRY AIR CONTINUING ESPCLY IN THE LOWER LEVELS
THIS EVENING WITH MOST ADVECTION OF MOISTURE COMING FROM THE WEST
ATTM. THIS DRY AIR HAS BASICALLY DRIED UP THE INITIAL BATCH OF
PRECIP HEADING IN FROM THE WEST WITH THE FIRST FAINT WAVE...WHILE
HAVE ANOTHER WEAK ARC OF ENERGY SET TO ARRIVE FROM TN/KY OVER THE
FAR WEST LATE. LATEST RAP PICKS UP ON THIS AFTER MIDNIGHT AND HAS
SOME SPOTTY -RA OVER THE NW NC RIDGES...AND AREAS WEST OF I-77 IN
VA LATE. MOST OTHER SHORT TERM GUIDANCE QUITE DRY SO ONLY
INCLUDING A SLIGHT POP FOR VERY -RA EXTREME SW BY DAWN. OTRW WILL
SEE VARYING AMOUNTS OF HIGH/MID CLOUDS...WITH A THICKER MID DECK
CANOPY DEVELOPING OVERNIGHT WEST...AND SOME THIN SPOTS OVER THE
NORTH/EAST. BUMPED UP LOW TEMPS A BIT SW DUE TO THICKER CLOUDS
WITH MOST SPOTS IN THE 40S BY MORNING...EXCEPT SOME 30S DEEPER
VALLEYS ACROSS THE NORTH.
HIGH PRESSURE WILL MOVE EAST OFF THE NEW ENGLAND COAST ON SATURDAY.
AN APPROACHING SHORTWAVE COMBINED WITH EASTERLY FLOW WILL INCREASE
MOISTURE ACROSS OUR REGION SATURDAY. PLACED THE HIGHEST POPS ON
SATURDAY ALONG THE SOUTHERN BLUE RIDGE MOUNTAINS...WITH LIGHTER
CHANCES IN THE EAST. HIGH SATURDAY VARY FROM THE LOW 50S ACROSS THE
SOUTHWEST MOUNTAINS TO AROUND 70 IN THE PIEDMONT. A FASTER SPREAD OF
MOISTURE COULD TRIM HIGHS SATURDAY MORE WITH ADDITIONAL CLOUD COVER
AND RAIN.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
AS OF 345 PM EDT FRIDAY...
ECMWF/GFS IN GENERAL AGREEMENT ON THE EVOLUTION OF THE PATTERN
SUN THROUGH MON...BUT CONTINUE TO DIFFER ON TIMING. HOWEVER...MOST
OF THE TIMING ISSUES APPEAR TO BE RESOLVED BY THE BEGINNING OF THE
SHORT TERM PERIOD. THIS PERIOD CAN BEST BE CHARACTERIZED AS A
RATHER CONTINUOUS PERIOD OF LIGHT RAIN AS A SOUTHERN STREAM
DISTURBANCE SPREADS THROUGH THE REGION IN A FAVORABLE WEDGE AREA.
THE WEDGE WILL BE ENHANCED/REINFORCED AS THE PCPN FALLS INTO AN
INITIALLY DRY/COOL SFC AIR MASS. QPF THROUGH THE PERIOD SHOULD
RANGE FROM 0.25 INCH IN THE NE PART OF THE CWA TO PERHAPS NEAR AN
INCH IN THE NW NC MOUNTAINS AND FAR SW VA. BY SUN AFTERNOON...THE
WEDGE MAY ERODE ENOUGH ALONG THE WESTERN EDGE...FROM MERCER COUNTY
WV DOWN TOWARD NE TN TO SUPPORT ISOLD TSRA WITH DIURNAL HEATING.
THUS...HAVE REINTRODUCED THE MENTION OF TSRA ALONG OUR WESTERN
BORDER. EASTERN AREAS SHOULD REMAIN TOO STABLE/COOL TO SUPPORT
TSRA THROUGH THE SHORT TERM. HAVE NOT INCLUDED ANY MENTION OF DZ
THIS PERIOD AS WITH -RA LIKELY...IT JUST ADDS CONFUSION TO THE
PUBLIC FORECAST. TEMPERATURES WILL BE UNSEASONABLY COOL THROUGH
THE PERIOD WITH HIGHS IN THE 50S SUN ACROSS MUCH OF THE
REGION...EXCEPT THE PERIPHERY OF THE CWA WHERE IT WILL BE IN THE
60S. HAVE LEANED HEAVILY TOWARD THE MUCH COOLER ECMWF MOS THROUGH
THE PERIOD.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
CONSIDERABLE QUESTIONS REMAIN WITH RESPECT TO THE EVOLUTION OF
WEATHER FEATURES WITH THE EXTENDED PERIODS...ESPECIALLY THE LATER
PERIODS. THE BIG QUESTION...AS HAS BEEN THE CASE FOR DAYS NOW...IS
THE DEVELOPMENT/MOVEMENT/POSITION OF A POTENTIAL CLOSED UPPER LOW.
ECMWF/GFS CONTINUE TO COVER THE ENTIRE SPECTRUM WITH RESPECT TO
THE DETAILS. THUS...THERE IS LITTLE TO NO RELIABILITY OR
CONFIDENCE IN THE EXTENDED FORECAST...ESPECIALLY THE LATER
PERIODS. AT THE BEGINNING OF THE EXTENDED PERIODS...TUE-
WED...STILL DEALING WITH A LINGERING WEDGE ACROSS THE EASTERN
SECTIONS. GIVEN THE PERSISTENT PATTERN THIS PAST WINTER AND SPRING
SO FAR...HAVE LEANED HEAVILY TOWARD THE ECMWF WHICH IS MUCH SLOWER
TO ERODE THE WEDGE. BETTER PCPN CHANCES WITH BOTH THE GFS/ECMWF
SHIFT SOUTH AND EAST OF THE CWA EARLY...WITH PCPN TRENDING TOWARD
A MORE DIURNAL PATTERN FOCUSING ALONG THE MOUNTAINS IN AREAS OF
BETTER DIFFERENTIAL HEATING. TEMPERATURES SHOULD SLOWLY WARM
TOWARD MORE SEASONAL LEVELS...BUT LIKELY WILL REMAIN JUST BELOW
NORMAL THROUGH THE NEW RIVER VALLEY...SHENANDOAH VALLEY...AND
GREENBRIER VALLEY. DURING THE FINAL DAYS OF THE EXTENDED...NAMELY
THU-FRI...HAVE GONE NEARLY ENTIRELY WITH THE 00Z/12Z ECMWF
SOLUTION AND COMPLETELY IGNORED THE GFS SOLUTION OF A VERY DEEP
CLOSED LOW THROUGH THE SOUTHERN ABLUTIONS WITH ATTENDANT HEAVY
RAIN FOLLOWED BY SNOW AND RIDICULOUSLY COLD TEMPERATURES FOR
EARLY MAY. THE ECMWF OFFERS A MUCH MORE PLAUSIBLE FORECAST FROM
ALL ASPECTS...QPF...POPS...AND TEMPS. A COLD FRONT ON THE FORWARD
FLANK OF ANY LOW PRESSURE AREA ACROSS THE UPPER MID-WEST/OH VALLEY
MAY BEGIN TO APPROACH THE AREA BY SAT WITH INCREASING CHANCES OF
SHRA/TSRA AT THAT TIME.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 140 AM EDT SATURDAY...
CEILINGS WILL GRADUALLY LOWER THROUGHOUT THE DAY. DO NOT EXPECT
MVFR CEILINGS UNTIL WELL AFTER 00Z/8PM THIS EVENING. AS LOW
PRESSURE MOVES ACROSS THE SOUTHERN MISSISSIPPI VALLEY...FORCING
AND INFLOW OF MOISTURE OVER THE SOUTHERN APPALACHIANS WILL GREATLY
INCREASE. RAIN WILL OVERSPREAD THE AREA BEFORE 12Z/8AM SUNDAY.
THIS SHOULD RESULT IN MVFR/IFR CIGS AND VSBYS...ESPECIALLY IN THE
MOUNTAINS DUE TO LIGHT TO MODERATE RAIN.
FLYING WEATHER WILL REMAIN POOR FOR THE NEXT SEVERAL DAYS. SURFACE LOW
PRESSURE WILL MOVE OUT OF THE PLAINS AND INTO THE OHIO VALLEY...
WEAKENING AS IT GOES. NET RESULT WILL BE MOIST SOUTH FLOW AND
PERIODS OF PCPN...LOW CLOUDS AND SUB VFR VISIBILITIES OVER THE
AREA THROUGH MONDAY. HIGH PRESSURE WILL THEN WEDGE DOWN THE ERN
SEABOARD FOR TUESDAY AS A STRONG COLD FRONT APPROACHES ON
WEDNESDAY. MVFR WITH PERIODS OF IF ARE LIKELY FOR MUCH OF NEXT
WEEK.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS/RAB
NEAR TERM...JH/KK
SHORT TERM...RAB
LONG TERM...RAB
AVIATION...AMS
AREA FORECAST DISCUSSION
NWS LITTLE ROCK AR
652 AM CDT SAT APR 27 2013
.AVIATION...
LOW PRESSURE IS LOCATED NEAR THE TEXAS AND OKLAHOMA BORDER. THIS
WILL MOVE ALONG A WARM FRONT THIS MORNING AND WILL BRING A
TRAILING COLD FRONT ACROSS THE AREA THIS AFTERNOON. SHOWERS AND
THUNDERSTORMS WILL CONTINUE THROUGH MUCH OF THE DAY. RAIN CHANCES
WILL DECREASE THIS EVENING AND CEILINGS WILL RISE. PATCHY FOG WILL
DEVELOP OVERNIGHT. LIFR TO MVFR CONDITIONS ARE EXPECTED.
&&
.PREV DISCUSSION... /ISSUED 349 AM CDT SAT APR 27 2013/
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT
USETTLED CONDITIONS ARE EXPECTED FOR THE FIRST BACK OF THE WEEKEND
BUT THE SECOND HALF APPEARS TO BE MUCH BETTER AT THIS POINT. GFS
SOLUTION HAS BEEN THE MOST CONSISTENT MODEL OF LATE IN THE SYNOPTIC
SCALE AND SEE NO REAL REASON TO STRAY FROM IT AT THIS POINT.
SHORTWAVE TROUGH...CLEARLY EVIDENT ON MOISTURE CHANNEL IMAGERY THIS
MORNING...EXTENDS FROM EASTERN KANSAS DOWN TO THE TEXAS PANHANDLE.
FEATURE IS EXPECTED TO MOVE TO THE EAST OVER THE NEXT 24 HOURS OR SO
WITH A WEAK H5 LOW DEVELOPING AS IT DOES. ON THE SURFACE...LATEST
ANALYSIS PLACES A WEAK WARM FRONT ALONG THE ARKANSAS/LOUISIANA
BORDER ANCHORED BY WEAK LOW PRESSURE ALONG THE RED RIVER. THIS
FEATURE APPEARS TO BE STARTING TO MOVE TOWARDS THE NORTH.
RADAR IMAGERY ACROSS THE REGION SHOWS ONGOING...SCATTERED SHOWER
ACTIVITY ACROSS THE STATE THAT IS LIKELY BEING GENERATED IN AN AREA
OF ASCENT ASSOCIATED WITH THE LOW LEVEL JET. CONVECTIVE COMPLEX
OVER EASTERN OKLAHOMA/WESTERN ARKANSAS HAS BEEN STEADILY WEAKENING
WITH TIME. THE AFOREMENTIONED TROUGH WILL PUSH SLOWLY EAST TODAY AS
FRONTAL SYSTEM LIFTS TO THE NORTH WITH WIDESPREAD SHOWER AND
THUNDERSTORM ACTIVITY CONTINUING.
BEST CHANCES OF PRECIPITATION LOOK TO BE EARLY IN THE DAY WITH
CHANCES DECREASING DURING THE DAY AS SYSTEM LIFTS THROUGH. BEST
CHANCES WILL THEN BE CONFINED TO THE TRAILING COLD FRONT AND THERE
REMAINS A CHANCE OF SOME STRONGER CONVECTION OVER THE SOUTHEAST PART
OF THE STATE. WILL HOLD ONTO LINGERING PRECIPITATION CHANCES
EARLY ON SUNDAY BEFORE ENDING THE RAINFALL ENTIRELY.
QPF FORECASTS ALL OVER PLACE THIS MORNING BUT HRRR MODEL ACTUALLY
SEEMS TO HAVE THE BEST HANDLE ON THE SYSTEM. AS SUCH...WILL FOLLOW
ITS TRENDS CONCERNING PRECIPITATION COVERAGE AND WILL TRIM BACK THE
AMOUNTS. WILL BLEND ECWMF/MAV NUMBERS FOR TEMPERATURES.
REMAINDER OF THE SHORT TERM PERIOD LOOKS RATHER EVENTFUL AS SURFACE
HIGH PRESSURE MOVES ACROSS AND EVENTUALLY EAST OF THE FORECAST AREA.
SOUTHERLY SURFACE WINDS AND A RATHER NONDESCRIPT UPPER FLOW WILL
ALLOW TEMPERATURES TO GET ABOVE NORMALS FOR LATE APRIL/EARLY MAY.
NEXT SYSTEM WILL BEGIN TO DROP DOWN INTO THE CENTRAL PLAINS LATE BUT
ITS IMPACTS WILL LIKELY BE FELT IN THE EXTENDED PERIOD.
LONG TERM...WEDNESDAY THROUGH FRIDAY...
AN UPPER TROUGH WILL BE OVER THE NORTHERN PLAINS TO BEGIN THE PERIOD
WITH A RIDGE OVER THE EASTERN U.S. THE UPPER TROUGH WILL DEEPEN
THROUGH THE SOUTHERN PLAINS WEDNESDAY NIGHT AND THURSDAY. BY FRIDAY
IT BECOMES A CLOSED LOW OVER THE OHIO RIVER VALLEY PROVIDING
NORTHWEST FLOW TO ARKANSAS.
A COLD FRONT WILL MOVE THROUGH ARKANSAS WEDNESDAY. MOISTURE WILL
STREAM NORTH OUT OF THE GULF OF MEXICO. CHANCES OF SHOWERS AND
THUNDERSTORMS WILL INCREASE THROUGH WEDNESDAY...REACH THEIR PEAK
WEDNESDAY NIGHT...AND END THURSDAY MORNING. HIGH PRESSURE WILL BUILD
OVER THE AREA THURSDAY AND FRIDAY. MUCH COOLER AND DRIER AIR WILL BE
USHERED IN WITH THIS COLD HIGH PRESSURE SYSTEM. ABOVE NORMAL
TEMPERATURES ARE EXPECTED WEDNESDAY AND MUCH BELOW NORMAL FOR
THURSDAY AND FRIDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
BATESVILLE AR 70 52 72 52 / 70 40 20 10
CAMDEN AR 78 57 77 51 / 60 30 10 10
HARRISON AR 65 49 72 51 / 80 20 10 10
HOT SPRINGS AR 74 54 76 52 / 60 20 10 10
LITTLE ROCK AR 74 55 75 54 / 60 30 10 10
MONTICELLO AR 79 59 76 54 / 80 40 20 10
MOUNT IDA AR 73 52 76 51 / 60 20 10 10
MOUNTAIN HOME AR 66 50 72 51 / 80 30 10 10
NEWPORT AR 71 54 72 52 / 70 40 20 10
PINE BLUFF AR 77 57 76 54 / 70 40 20 10
RUSSELLVILLE AR 70 51 74 53 / 70 20 10 10
SEARCY AR 72 54 73 53 / 70 40 20 10
STUTTGART AR 75 56 75 54 / 70 40 20 10
&&
.LZK WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AVIATION...51
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1024 AM EDT SAT APR 27 2013
.UPDATE...
THE NEAR TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 326 AM EDT SAT APR 27 2013
SURFACE AND UPPER LOWS WILL MOVE THROUGH CENTRAL INDIANA THIS
WEEKEND BRINGING SHOWERS AND PERHAPS A FEW THUNDERSTORMS TO THE
AREA. DRY WEATHER WILL THEN MOVE IN FOR MUCH OF THE EARLY PART OF
THE WORK WEEK...BUT A COLD FRONT WILL BRING RETURNING CHANCES FOR
RAIN FROM MID TO LATE WEEK NEXT WEEK.
TEMPERATURES WILL GRADUALLY WARM TO ABOVE AVERAGE BY MID WEEK...THEN
FALL TO BELOW AVERAGE BY THE END OF THE WEEK.
&&
.NEAR TERM /THIS AFTERNOON/...
ISSUED AT 1024 AM EDT SAT APR 27 2013
CLOUD SHIELD EXPANDING NORTH THIS MORNING WITH LARGE AREA OF RAIN
APPROACHING FROM THE SOUTHWEST. TEMPS HAD WARMED INTO THE 50S
ACROSS THE FORECAST AREA AT 14Z WITH WARMEST TEMPS OVER NORTHEAST
COUNTIES WHERE SKIES WERE MOSTLY SUNNY.
MAIN CHANGE FOR THE UPDATE IS TO DELAY ONSET OF THE RAINFALL BY
3-4 HOURS ACROSS MUCH OF THE FORECAST AREA LATER TODAY AS DRIER AIR
THROUGH THE LOW LEVELS REMAINS PRESENT. HAVE SEEN A FEW SPRINKLES
INTO THE LOWER WABASH VALLEY ALREADY THIS MORNING BUT MUCH OF THIS
ACTIVITY IS DIMINISHING A IT MOVES NORTHEAST AND RUNS INTO AN
INCREASING DRIER AIRMASS. CURRENT RAP INDICATING DEEPER ISENTROPIC
LIFT REALLY HOLDS OFF ACROSS CENTRAL INDIANA UNTIL AFTER 18Z AND
FOR THE NORTHERN HALF OF THE FORECAST AREA UNTIL BETWEEN 21Z AND
00Z. CONSIDERING THE DEPTH OF THE DRY AIR PRESENT...THE SURGE OF
ISENTROPIC LIFT WILL BE NEEDED TO SATURATE THE LOW LEVELS AND
ENABLE PRECIP SHIELD TO EXPAND NORTH. HAVE THEREFORE SLOWED DOWN
ARRIVAL OF RAINFALL BY A FEW HOURS...WITH MANY AREAS NORTH OF I-70
REMAINING DRY UNTIL AFTER 21-22Z. LEFT FORECAST HIGHS ALONE FOR
THE AFTERNOON WITH THE EXCEPTION OF THE FAR NORTHERN COUNTIES
WHERE SUNSHINE WILL CONTINUE FOR THE NEXT FEW HOURS AND MAY ENABLE
LOCATIONS LIKE KOKOMO AND MUNCIE TO MAKE A RUN AT 70 LATER TODAY.
ZONE AND GRID UPDATES OUT.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
ISSUED AT 326 AM EDT SAT APR 27 2013
FOCUS CONTINUES TO BE ON CHANCES FOR RAIN THROUGH THE PERIOD. MODELS
ARE CLOSE ENOUGH THAT A BLEND CAN BE USED FOR MOST ITEMS.
Q-VECTOR FORECAST PLOTS SHOW THE FORCING MOVING INTO THE AREA
TONIGHT ASSOCIATED WITH AN UPPER LOW MOVING INTO THE AREA...SO
GRADUALLY INCREASED POPS ACROSS THE FORECAST AREA TONIGHT. WENT
CLOSE TO MOS POPS WITH LIKELY NORTH AND CATEGORICAL SOUTH.
ON SUNDAY THE SURFACE AND UPPER LOWS WILL MOVE THROUGH THE AREA. MOS
POPS ARE HIGH...BUT MODELS ARE ONLY SHOWING RELATIVELY WEAK FORCING.
FORECAST REFLECTIVITY ALSO SHOWS MORE OF A SCATTERED COVERAGE THAN
WIDESPREAD AT ANY ONE TIME. HOWEVER WITH THE LOWS MOVING THROUGH
CANNOT REALLY ARGUE AGAINST THE HIGH POPS SINCE MOST AREAS COULD SEE
A HUNDREDTH OF AN INCH IN A PASSING SHOWER. WITH THE HIGH POPS WILL
USE OCCASIONAL WORDING TO HIGHLIGHT DRY PERIODS DURING THE
DAY.
SOME INSTABILITY MOVES IN WITH THE SURFACE LOW SO MENTIONED ISOLATED
THUNDERSTORMS SUNDAY.
WENT LOW POPS SUNDAY EVENING AS MODELS CONTINUE TO HINT AT LINGERING
PRECIPITATION. FOR OVERNIGHT SUNDAY NIGHT INTO MONDAY WENT SLIGHT
CHANCE POPS ACROSS THE EAST FOR THE SAME REASON.
FOR TEMPERATURES THROUGH THE FIRST HALF OF THE PERIOD...GENERALLY
WENT WITH THE COOLER OF THE MOS DURING THE DAY AND THE WARMER OF THE
MOS DURING THE NIGHT DUE TO CLOUDS AND RAINFALL. GENERALLY STUCK
WITH A BLEND FOR THE SECOND HALF.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
ISSUED AT 300 AM EDT SAT APR 27 2013
MODEL TIMING DIFFERENCES REGARDING AN UPPER LOW AND UPSTREAM FRONTAL
SYSTEM WILL CONTINUE TO BE THE MAIN ISSUE IN THE EXTENDED ESPECIALLY
LATE WEEK.
THE 00Z GFS AND GEFS CONTINUE TO BE MUCH FASTER AND WEAKER WITH THE
AFOREMENTIONED UPPER SYSTEM. BY 00Z FRIDAY...THE 12Z ECMWF HAS A
DEEP UPPER LOW ACROSS NORTHEASTERN NEBRASKA...WHILE THE 00Z GFS AND
GEFS HAVE A WEAKER OPEN TROUGH ACROSS EASTERN MISSOURI AND FINALLY
THE 00Z GEM HAS AN UPPER LOW FORMING WITHIN THE TROUGH ACROSS
NORTHERN TEXAS. MEANWHILE...THE GFS AND GEFS WERE MUCH FASTER WITH
THE LEAD FRONT WITH THE ECMWF AND TO A LESSER EXTENT EURO LAGGING
WELL TO THE WEST. THE GEFS AND GFS HAVE THE FRONT ACROSS OHIO...THE
GEM ACROSS EASTERN INDIANA AND EURO ACROSS WESTERN INDIANA AT THAT
TIME. THIS RESULTS IN QUICKER MOISTURE RETURN AND QPF FROM THE GFS
AND GEFS. THE GFS AND GEFS HAS DECENT QPF BY WEDNESDAY NIGHT...WHILE
THE OTHER LONG RANGE MODELS HOLD OFF TIL WEDNESDAY.
WITH A STRONG RIDGING ACROSS THE EASTERN SEABOARD AS WELL AS THE
WEST...PREFER THE SLOWER ECMWF BUT WILL ALLOW FOR SMALL POPS OF THE
REGIONAL INITIALIZATION ON WEDNESDAY IN THE SMALL CHANCE THE GFS
VERIFIES OR THE EURO AND GEM SPEED UP A LITTLE BIT IN LATER RUNS.
ALL MODELS HAVE DECENT QPF ON THURSDAY AND HOLD ON TO IT ALSO FRIDAY
WHICH IS REFLECTED IN CONTINUED REGIONAL INITIALIZATION POPS.
AGAIN WITH LOW CONFIDENCE FROM MODEL DIFFERENCES...WILL ACCEPT THE
REGIONAL TEMPERATURES WHICH HAVE HIGHS IN THE 70S THROUGH WEDNESDAY
AND THEN PROGRESSIVELY COOLER NUMBERS IN THE 60S ON THURSDAY AND 50S
BY FRIDAY AS COLD FRONT SLIDES TO THE EAST.
&&
.AVIATION /DISCUSSION FOR 271500Z TAF UPDATE/...
ISSUED AT 1015 AM EDT FRI APR 27 2013
UPDATE...
NO CHANGES.
PREVIOUS DISCUSSION...
LIGHT RAIN WILL GRADUALLY SPREAD NORTHEAST ACROSS THE TAF SITES
REACHING LAF AND BMG FROM 16Z-18Z...IND FROM 18Z-20Z AND LAF FROM
20-22Z. AS THE RAIN FALLS...VFR CONDITIONS WILL BECOME MVFR AND THEN
IFR SHORTLY THEREAFTER AND REMAIN THAT WAY THROUGH THE NIGHT.
WINDS WILL BE LESS THAN 10 KNOTS FROM THE SOUTHEAST TODAY AND BECOME
LIGHT AND VARIABLE AFTER 00Z.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...50
NEAR TERM...RYAN
SHORT TERM...50
LONG TERM....MK
AVIATION...MK/TDUD
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
1012 AM CDT SAT APR 27 2013
.UPDATE...
ISSUED AT 1001 AM CDT SAT APR 27 2013
MADE SOME UPDATES TO THE FORECAST TODAY...PRIMARILY TO INCREASE
POPS AND LOWER TEMPERATURES A BIT STRETCHING FROM CENTRAL MISSOURI
THROUGH SOUTHWEST ILLINOIS. UPPER LEVEL LOW IS MOVING SLOWLY INTO
WESTERN MISSOURI AND A BROAD AREA OF LIGHT RAIN EXTENDS FROM
SPRINGFIELD MISSOURI UP THROUGH CENTRAL AND EASTERN MISSOURI INTO
SOUTHWEST ILLINOIS. LATEST HRRR GUIDANCE SUGGESTS THIS WILL
PERSIST THROUGH THE DAY AS THE LOW CONTINUES DRIFTING EAST.
CARNEY
&&
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 320 AM CDT SAT APR 27 2013
THE PRIMARY FCST ISSUE FOR TODAY IS PCPN CHCS/COVERAGE ASSOCIATED
WITH A VORT MAX THAT IS SLOWLY PROGRESSING EWD FM OK/KS TOWARDS
MO/IL. THE SFC REFLECTION OF THIS FEATURE IS EXPECTED TO REMAIN
GENERALLY SOUTH OF THE CWA AS IT LIFTS FM OK THROUGH AR INTO SERN
MO. ALTHOUGH THE SFC LOW WILL LIFT A WMFNT NEWD INTO SRN MO...THE
FRONT IS EXPECTED TO REMAIN SOUTH OF THE CWA THEREFORE TEMPERATURES
WILL BE GOVERNED BY CLOUD COVER AND LIMITED DIURNAL HEATING RATHER
THAN BY ADVECTION.
THERE WERE THREE DISTINCT AREAS OF PCPN OCCURRING ACROSS THE REGION
EARLY THIS MORNING. FIRST...A CONVECTIVE COMPLEX WAS MOVING THROUGH
OK INTO WRN AR AT 08Z. THIS COMPLEX WILL REMAIN SOUTH OF THE CWA.
SECOND...A BROKEN AREA OF SHRA WITH ISO TSRA WAS LOCATED OVER SERN
MO AND WAS MOVING INTO SRN IL AND WRN KY. THIS AREA OF PCPN APPEARS
TO BE FORCED BY LLJ MCONV AND WILL CONTINUE TO AFFECT THE SERN PART
OF THE CWA FOR THE NEXT SEVERAL HOURS UNTIL THE LLJ DIMINISHES.
THIRD...A DEFORMATION ZONE HAS DVLPD ACROSS CENTRAL AND ERN KS AS
WELL AS NWRN MO. AS THE UPPER LOW SHIFTS SLOWLY EWD TODAY SO WILL
THE DEFORMATION ZONE AND ITS PCPN. THERE MAY ALSO BE SOME DIURNAL
ENHANCEMENT OF PCPN COVERAGE. NO MODEL IS HANDLING THE DEFORMATION
ZONE VERY WELL THIS MORNING THEREFORE POPS FOR TODAY ARE BASED ON
THE POSITION OF THE CURRENT DEFORMATION ZONE AND THE FCST POSITION
OF THE CLOSED H5 LOW BY 00Z. IN A DEPARTURE FROM THE PREVIOUS
FCST...PCPN IS NOW EXPECTED TO AFFECT THE MIDDLE AND NRN HALF OF THE
CWA MORE THAN THE SRN HALF.
KANOFSKY
.LONG TERM...(TONIGHT THROUGH FRIDAY)
ISSUED AT 320 AM CDT SAT APR 27 2013
(TONIGHT - SUNDAY)
A LARGELY NEUTRAL LONGWAVE PATTERN OVER NOAM WILL BEGIN TO
TRANSITION TOWARDS A LONGWAVE RIDGE IN THE E AND A TROF IN THE W
LATER ON SUNDAY. THE MOST PROMINENT FEATURE OF THIS PERIOD WILL BE
THE SYSTEM CENTERED OVER SERN KS CONTINUING TO SLOWLY WORK ITS WAY
THRU OUR REGION...AND SLOWLY IT WILL GO. MODELS HAVE TRENDED ABOUT
6-12 HRS SLOWER WITH THE EWD PROGRESSION OF THIS SYSTEM FROM 24HRS
AGO AND SO HAVING IT ONLY MAKE IT THRU ABOUT TWO-THIRDS THRU THE FA
BY SUNDAY/12Z WITH IT FINALLY EXITING WITH MOST OF ITS DYNAMICS BY
18Z. MAIN DYNAMICS WITH THIS SYSTEM...SINCE IT CLOSED OFF EARLIER
TONIGHT...WILL BE ITS ABILITY NOW TO PRODUCE DEFORMATION ZONE PCPN
FOR AREAS FARTHER N. THIS PCPN SHOULD BE FURTHER ENHANCED DIURNALLY
BY COLD CORE NATURE OF LO ALOFT AND WILL LIKELY SEE THESE EFFECTS
EARLY THIS EVENING BEFORE SUN GOES DOWN. STILL...A GOOD PREVIEW OF
WHAT WE WILL SEE TONIGHT CAN BE SEEN IN ERN KS WITH THE CENTER OF
THE UPPER SYSTEM EXPECTED TO TRACK JUST N OF THE I-70 CORRIDOR.
DEFORMATION ZONE PCPN INITIALLY SHUNTED TO THE NRN HALF OF THE FA
THIS EVENING WILL ERODE ON ITS WRN SIDE AND THEN GRADUALLY TILT MORE
N-S ORIENTED BY SUNDAY MORNING AND DO A FINAL SWEEP ACROSS THE ERN
FA/SWRN IL.
CLOUDS WILL ALSO STICK AROUND SUNDAY LONGER THAN ANTICIPATED 24HRS
AGO...AND THIS WILL TAKE A HIT TO MAX TEMPS...ESPECIALLY FOR STL
METRO AND AREAS SE...WHERE THEY HAVE BEEN TRIMMED A CATEGORY OR
TWO...OR IN LINE WITH THE COOLER MET MOS NUMBERS. FURTHER NW...MAX
TEMPS ARE CLOSE TO A MOS BLEND.
(MONDAY - WEDNESDAY)
UPPER LEVEL RIDGE OVER ERN NOAM WILL DOMINATE THIS PERIOD...WITH A
TROF BUILDING OVER THE NWRN CONUS INITIALLY...BUT DEEPENING WITH
TIME AS IT SLOWLY TRANSLATES EWD INTO THE PLAINS BY WEDNESDAY. THIS
SHOULD GIVE US A PERIOD OF WARM AND MAINLY DRY WX.
THE WARMER MAV MOS IS A GOOD PLACE TO START FOR MONDAY MAX TEMPS AND
IN SOME PLACES...EDGED EVEN HIGHER. LOOK FOR LO-MID 80S ON TUESDAY
WITH A MORE SW WIND EXPECTED. LARGE ADJUSTMENT MADE TO
INITIALIZATION FOR MAX TEMPS ON WEDNESDAY WITH ECMWF CONSISTENTLY
THE SLOWEST MODEL WITH PROGRESSION WHAT SHOULD BE A STRONG CDFNT AND
EVEN GFS ALSO BACKING OFF. WEDNESDAY MAX TEMPS WITH A CDFNT EITHER
ARRIVING VERY LATE OR NOT AT ALL WILL YIELD VALUES AT LEAST
COMPARABLE TO MONDAY...PROBABLY TUESDAY.
(THURSDAY - FRIDAY)
LARGE DISCREPANCY BETWEEN MODELS ON WHAT TO DO NEXT WITH THAT PLAINS
UPPER LEVEL TROF. WHILE ALL BREAK OFF THE DIGGING SHORTWAVE
RESPONSIBLE AND CUT IT OFF FROM THE MAIN FLOW...WHEN AND WHERE THIS
HAPPENS IS A MATTER OF DISPUTE. THE GEM AND ECMWF PREFER TO MAKE
THIS OCCUR SOONER AND SETUP A CUTOFF LO OVER THE CNTRL-SRN PLAINS
WHILE THE GFS IS A BIT LATER...AND INSTEAD OVER THE MID MS AND LOWER
OH VALLEYS. A HUGE DIFFERENCE IN WHAT I FCST DEPENDING ON WHICH
MODEL WITH SFC CDFNT TIMING DIFFS AND AMOUNT OF TIME FRONT SPENDS
OVER THE FA AS WELL...WITH THE GFS BLOWING IT THRU QUICKLY WHILE THE
ECMWF AND GEM LINGER IT FOR A WHILE. WENT GENEROUS WITH POPS ON THE
TAIL-END TIMING-WISE...NOW EXTENDING CHC CATEGORY INTO THURSDAY
NIGHT FOR SOME AREAS ESPECIALLY WITH WEDNESDAY LOOKING LESS
PROBABLE. BUT OVERALL...A LO CONFIDENCE FCST AT THIS TIME. SHOULD
COLD AIR BLOW THRU PER GFS...COULD BE AN UNUSUALLY COLD COUPLE OF
MORNINGS FOR EARLY MAY.
TES
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1001 AM CDT SAT APR 27 2013
HAVE UPDATED ALL TERMINALS TO LOWER CIGS INTO THE AFTERNOON BASED
ON CONDITIONAL CLIMATOLOGY AND UPSTREAM OBSERVATIONS. FROM CENTRAL
MISSOURI THROUGH THE STL METRO AREA THIS MEANS IFR INTO THE
AFTERNOON. FURTHER NORTH ACROSS NORTHEAST MISSOURI AND WEST
CENTRAL ILLINOIS CIGS WILL LIKELY STAY BETWEEN 1000-1900FT.
CARNEY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1000 AM CDT SAT APR 27 2013
.UPDATE...
ISSUED AT 957 AM CDT SAT APR 27 2013
WILL CONTINUE TO SEE SOME AREAS OF FOG LINGERING THIS
MORNING...PRIMARILY ALONG A PHG/HSI/AUH/JYR LINE...WHERE
VISIBILITIES NEAR 1/2 MILE WILL REMAIN POSSIBLE. HOWEVER...WITH
MOST OTHER AUTOMATED SITES/WEB CAMS SHOWING IMPROVING CONDITIONS
AND THE HRRR SUGGESTING WHAT LINGERING FOG THERE IS NOT LASTING
MUCH LONGER...DECIDED TO LET THE HEADLINE EXPIRE AT 10. OTHERWISE
ONLY MINOR TWEAKS MADE.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 535 AM CDT SAT APR 27 2013
BIGGEST CHALLENGE WILL BE DETERMINING EXTEND AND TIMING OF FOG THIS
MORNING...AND ALSO HIGH TEMPERATURES FOR TODAY.
WE HAPPEN TO BE IN AN AREA OF LOW-LEVEL CONVERGENCE THAT IS HANDLED
FAIRLY WELL BY THE HRRR...BUT NOT AS WELL BY OTHER MODELS...ALTHOUGH
THE LATEST RUN OF THE SREF ENSEMBLE SEEMS TO BE CATCHING UP WITH THE
HRRR. THE HRRR INDICATES THAT IT COULD BE AS LATE AS 10 AM UNTIL WE
CAN GET THE FOG BURNED OFF.
OVERALL...SPLIT FLOW CONTINUES IN THE UPPER LEVELS...WITH OUR CWA IN
BETWEEN...WHICH WHICH WILL LEND TO LIGHT FLOW IN GENERAL. THERE
SHOULD BE ENOUGH SUBSIDENCE TO HELP SCOUR OUT THE STRATUS AND FOG BY
LATE MORNING...WHICH SHOULD GIVE US PLENTY OF SUN BY AFTERNOON.
AREAS TO THE NORTH/WEST WILL WARM THE MOST AND I HAVE INCREASED HIGH
TEMPERATURES IN THESE AREAS FROM THE PREVIOUS FORECAST...WITH
SOUTHEASTERN AREAS A BIT COOLER WHERE STRATUS MIGHT STICK AROUND A
BIT LONGER AND 850 MB TEMPERATURES WILL BE COOLER. I PLACED QUITE A
BIT OF WEIGHT ON HOW MODELS HAVE PERFORMED VERY RECENTLY TO DERIVE
HIGH TEMPERATURES FOR TODAY. WENT CLOSE TO PREVIOUS FORECAST LOW
TEMPERATURES.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 535 AM CDT SAT APR 27 2013
THIS 6-DAY PERIOD LOOKS TO FEATURE QUITE A ROLLER COASTER RIDE IN
TEMPERATURES...STARTING OUT WITH A CONTINUATION OF THE ONGOING
VERY MILD STREAK...BUT THEN SETTLING DOWN BELOW NORMAL AGAIN FOR
WEDNESDAY-FRIDAY. UNFORTUNATELY...THERE ARE SUGGESTIONS BY SOME
MODELS...ESPECIALLY THE ECMWF...THAT THIS NEXT BATCH OF COLD COULD
BE QUITE A BIT MORE INTENSE THAN THE CURRENT FORECAST
DEPICTS...AND DARE WE SAY BRING THE POTENTIAL FOR AT LEAST A
RAIN/SNOW MIX TO SOME AREAS. HOWEVER...GIVEN THAT THIS POTENTIALLY
BIG COOL DOWN IS STILL 4+ DAYS AWAY AND UNCERTAINTY REMAINS
PLENTIFUL...HAVE ONLY MADE MINOR DOWNWARD TWEAKS TO PREVIOUS
FORECAST TEMPS FOR NOW...BUT STAY TUNED FOR POTENTIALLY MORE
DRASTIC CHANGES. GIVEN THAT THIS POTENTIAL COLD SNAP WILL OCCUR IN
EARLY MAY...ITS NOW NOT OUT OF THE QUESTION THAT A FROST
ADVISORY/FREEZE WARNING SITUATION MAY UNFOLD SOMETIME DURING THE
WED-FRI TIME FRAME AS WELL...ALTHOUGH A WIDESPREAD HARD KILLING
FREEZE OF 28 DEGREES OR LOWER DOES NOT SEEM EVIDENT AT THIS TIME.
TURNING TO OTHER ELEMENTS OF THE FORECAST...IT STILL LOOKS LIKE
THE TUES AFTERNOON/EVENING TIME FRAME HOLDS COULD HAVE SEVERE
THUNDERSTORM POTENTIAL...ESPECIALLY WITHIN THE SOUTHEAST 1/3 OF
THE CWA. LAST BUT NOT LEAST...WILL HAVE TO KEEP AN EYE SUNDAY
AFTERNOON FOR AT LEAST LIMITED FIRE DANGER...AS DISCUSSED IN A BIT
MORE DETAIL IN THE SEPARATE FIRE WEATHER SECTION BELOW.
STARTING IN MORE DETAIL WITH SUNDAY/SUNDAY NIGHT...THE VAST
MAJORITY...IF NOT THE ENTIRE CWA SHOULD STAY DRY...WITH THE
DAYTIME HIGHS LIKELY THE WARMEST OF THE ONGOING WARM
STRETCH...WITH MUCH OF THE CWA FORECAST TO BREACH 80 DEGREES FOR
THE FIRST TIME THIS SPRING. ALOFT...VARIOUS MODELS SUCH AS THE 00Z
NAM/GFS/ECMWF ARE IN DECENT AGREEMENT WITH BROAD WEST-NORTHWEST
FLOW...AS ONE MID LEVEL SHORTWAVE DEPARTS EASTWARD THROUGH THE
MIDWEST/OH VALLEY...WHILE THE NEXT BATCH OF LOW AMPLITUDE MID
LEVEL TROUGHS BRUSHES ACROSS THE DAKOTAS/MAINLY NORTHERN NEB ON
SUN NIGHT. THROUGH MOST OF THE DAY...FAIRLY LIGHT WEST-SOUTHWEST
BREEZES AND PLENTY OF SUNSHINE WILL PREVAIL. HOWEVER...BY LATE
AFTERNOON INTO EARLY EVENING...A WEAK COLD FRONT WILL SAG INTO THE
NORTHERN CWA...PUSHED SOUTHWARD BY THE AFOREMENTIONED NORTHERN
PLAINS ENERGY. ALTHOUGH HAVE LEFT OUT ANY PRECIP MENTION...WENT
AHEAD WITH SILENT 10 POPS ACROSS SEVERAL NORTHERN/WESTERN COUNTIES
LATE AFTERNOON INTO THE EVENING NEAR THIS BOUNDARY TO AT LEAST
HINT AT THE VERY LOW POTENTIAL FOR A SHOWER OR WEAK
THUNDERSTORM...ALTHOUGH THE LATEST 4KM WRF-NMM KEEPS ANY PRECIP
POTENTIAL NORTH OF THE CWA...ALTHOUGH THIS BEARS WATCHING. LATE
SUNDAY NIGHT...KEPT A MEASURABLE POP OUT OF THE FORECAST...BUT
EXPANDED THE PREVIOUSLY INTRODUCED CHANCE OF SPRINKLES ACROSS MOST
OF THE NORTHERN 1/3 OF THE CWA...AS A BAND OF MID LEVEL SATURATION
WORKS EASTWARD ACROSS THE REGION IN ASSOCIATION WITH THE PASSING
WEAK WAVE. ALTHOUGH LATER SHIFTS MAY NEED TO CONSIDER ADDING A LOW
MEASURABLE POP FOR THIS ACTIVITY ESPECIALLY FAR NORTH AROUND
ORD/GREELEY...DRY LOW LEVELS STILL SEEM TO SUGGEST THAT SPRINKLES
SHOULD LARGELY SUFFICE. TEMP-WISE...MADE LITTLE CHANGE TO HIGHS
AND LOWS...WITH ALL AREAS TOPPING OUT SOMEWHERE BETWEEN
79-85...AND BOTTOMING OUT IN THE UPPER 40S TO LOW 50S SUNDAY
NIGHT. BASED ON DRY WESTERLY FLOW ESPECIALLY EVIDENT IN THE LAST
FEW NAM RUNS...AFTERNOON DEWPOINTS WERE LOWERED SEVERAL DEGREES
FROM PREVIOUS...THUS PUSHING A GOOD CHUNK OF THE AREA TO 20
PERCENT OR LOWER RELATIVE HUMIDITY FOR A FEW HOURS.
MONDAY/MONDAY NIGHT...HAVE LEFT THIS ENTIRE 24 HOURS PRECIP
MENTION-FREE FOR NOW...ALTHOUGH AS NOTED BY PREVIOUS FORECASTERS
THIS IS NOT NECESSARILY A GUARANTEE FOR ALL AREAS AND WILL BEAR
WATCHING. IN THE MID LEVELS...THE GENERAL STORY INVOLVES THE
AFOREMENTIONED LOW AMPLITUDE SHORTWAVE TROUGH DEPARTING TO THE
EAST...WHILE A STRONGER UPSTREAM DISTURBANCE AND ASSOCIATED UPPER
JET STREAK STARTS TO CARVE A BIT MORE AMPLIFIED TROUGH ACROSS THE
NORTHERN ROCKIES/NORTHERN PLAINS. BREEZES DURING THE DAY WILL
GRADUALLY TURN FROM EASTERLY TO SOUTHERLY IN RESPONSE TO DEEPENING
LOW PRESSURE TO THE NORTHWEST...WITH THE LEADING EDGES OF THE NEXT
COLD FRONT THEN POSSIBLY REACHING THE NORTHWEST CWA BY SUNRISE
TUESDAY MORNING. AS FOR POSSIBLE PRECIP CHANCES TO CONSIDER IN
LATER FORECASTS...FOR ONE THERE COULD BE A BRIEF PERIOD OF
LINGERING SPRINKLES RIGHT AWAY IN THE MORNING. SECONDLY...THE
LATEST NAM SUGGESTS ANOTHER BATCH OF SHOWER ACTIVITY COULD BRUSH
NORTHERN COUNTIES VERY LATE MON NIGHT...ALTHOUGH THIS IS NOT WELL-
SUPPORTED BY OTHER SOLUTIONS. LASTLY...ALTHOUGH UNLIKELY...SUPPOSE
ITS NOT COMPLETELY OUT OF THE QUESTION THAT A LATE AFTERNOON
THUNDERSTORM COULD DEVELOP PRIMARILY IN THE SOUTHEAST CWA IN
RESPONSE TO 500-1000 J/KG OF 0-1KM MLCAPE...BUT FORECAST SOUNDINGS
SUGGEST THAT CAPPING AND LACK OF LIFT IN THE WAKE OF THE INITIAL
DEPARTING WAVE SHOULD PRECLUDE THIS SCENARIO. BOTTOM LINE...NO
PRECIP RISK MENTIONED AT THIS TIME. TEMP-WISE...ALTHOUGH STILL
QUITE WARM...SLIGHTLY LESS FAVORABLE MIXING THAN SUNDAY IS
EXPECTED TO KEEP TEMPS VERY SLIGHTLY COOLER...AND HAVE MOST AREAS
TOPPING OUT 77-82.
TUESDAY/TUESDAY NIGHT...AS MENTIONED ABOVE...THE LATE
AFTERNOON/EVENING TIME FRAME HOLDS THE BEST POTENTIAL FOR A ROUND
OF POTENTIALLY SEVERE STORMS MAINLY ACROSS THE SOUTHEAST 1/3 TO
1/2 OF THE CWA...BUT THIS IS ALSO FAR FROM A SURE THING AS SO MUCH
WILL DEPEND ON STILL-UNCERTAIN FRONTAL TIMING. ALOFT...BOTH THE
ECMWF/GFS SOLUTIONS ARE STILL IN PRETTY DECENT AGREEMENT AT THIS
POINT THAT A LARGE SCALE TROUGH AXIS WILL CONTINUE TO AMPLIFY
ALONG AN AXIS FROM THE NORTHERN PLAINS TO CENTRAL ROCKIES...WHILE
IN THE LOW LEVELS A RATHER HEALTHY COLD FRONT PUSHES SOUTHWARD
ACROSS THE CWA. ALTHOUGH A DECENT CAP SHOULD HOLD CONVECTION AT
BAY UNTIL AT LEAST MID-AFTERNOON...SOMETIME IN THE 21Z-01Z TIME
FRAME IS CURRENTLY EXPECTED TO FEATURE THE DEVELOPMENT OF STORMS
NEAR THE INVADING COLD FRONT...WHICH COULD BECOME SEVERE IN A
LIKELY QUASI-LINEAR FASHION PER THE ECMWF FORECAST OF 1000-1500
J/KG MLCAPE AND MODEST DEEP LAYER SHEAR. AS THE NIGHT WEARS
ON...THE OVERALL THUNDERSTORM INTENSITY SHOULD DIMINISH...BUT
COVERAGE OF WIDESPREAD RAIN AND EMBEDDED THUNDERSTORMS WOULD
INCREASE ACROSS NEARLY THE ENTIRE CWA AS A STRONGLY FORCED BAND OF
MID LEVEL CONVERGENCE/FRONTOGENESIS INVADES THE CWA FROM NORTHWEST
TO SOUTHEAST. ENOUGH CONSISTENCY IN THIS SCENARIO FOR TUESDAY
NIGHT EXISTS THAT POPS WERE RAISED INTO LIKELY TERRITORY IN MANY
AREAS. TEMP-WISE...HIGHS TUESDAY WILL BE TRICKY DUE TO UNCERTAINTY
IN THE SPEED OF THE INVADING COLD FRONT...BUT FOR NOW KEPT A
GENERAL RANGE FROM NEAR 70 NORTH TO NEAR 80 SOUTH.
FOR THE WEDNESDAY-FRIDAY TIME FRAME...THERE JUST ISN/T MUCH TO BE
GAINED YET BY GOING INTO MUCH DETAIL DUE TO VARYING MODEL
SOLUTIONS REGARDING THE EVOLUTION OF THE PASSING LARGE SCALE
TROUGH. IN GENERAL...BOTH THE 00Z ECMWF/GFS SOLUTIONS DEPICT A
SLOWING AND STALLING MID/UPPER TROUGH AS IT PASSES INTO THE
CENTRAL PORTION OF THE NATION...AS AN EXPANSIVE BLOCKING RIDGE
SETS UP SHOP OVER THE EASTERN CONUS. AS THIS BLOCK TAKES SHAPE...A
CLOSED...COLD AND FAIRLY COMPACT MID LEVEL LOW IS PROGGED TO FORM
SOMEWHERE...WITH THE ECMWF CLOSING THIS OFF OVER THE KS/OK AREA BY
THURS NIGHT INTO FRIDAY...WHILE THE GFS CLOSES THIS DEEP LOW OFF
MORE SO OVER MO/AR. ABOUT THE ONLY THING THE CURRENT FORECAST HAS
MUCH CONFIDENCE IN IS THAT DECENT PRECIP CHANCES WILL CONTINUE
ACROSS NEARLY THE ENTIRE CWA DURING THE DAY WEDNESDAY. HAVE KEPT
THIS RAIN FOR NOW...BUT THE VERY COLD ECMWF SOLUTION WOULD SUGGEST
A SNOW MIX POSSIBLE. THE CURRENT FORECAST THEN LINGERS A LESSER
CHANCE OF A RAIN/SNOW MIX ACROSS ROUGHLY THE SOUTHEAST 1/3 OF THE
CWA WED NIGHT...WHILE KEEPING THURSDAY-FRIDAY PRECIP-FREE.
HOWEVER...THIS PRECIP-FREE DEPICTION WILL NOT LAST IF THE ECMWF IS
IN FACT ONTO SOMETHING...AS IT DEPICTS A POSSIBLE RAIN/SNOW MIX
LASTING INTO FRIDAY IN SOME AREAS. RE-EMPHASIZING THE MAIN POINTS
HERE...A MUCH COOLER WEATHER REGIME WILL SETTLE IN BY MID-LATE
WEEK...BUT WE ARE STILL A FEW DAYS AWAY FROM PINNING DOWN JUST
HOW COLD IT MIGHT REALLY GET...AND WHETHER A RISK REALLY EXISTS
FOR POSSIBLY ANOTHER ROUND OF LATE-SEASON SNOW AND/OR SUB-
FREEZING OVERNIGHT LOW TEMPS. STAY TUNED...
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 546 AM CDT SAT APR 27 2013
REDUCED VISIBILITY IS THE BIGGEST CONCERN FOR THE FIRST 4 HOURS OR
SO. DENSE FOG IS CLOSE BY NEAR THE INTERSTATE AND AT THE AURORA
OBSERVATION. I WENT WITH A MIDDLE ROAD AND ANTICIPATED A 1SM
VISIBILITY ALTHOUGH THE TERMINAL HAS NOT DROPPED BELOW MVFR AS OF
THIS AFD. CONFIDENCE IS NOT HIGH FOR VISIBILITY. STRATUS IS
EXPECTED IN ASSOCIATION WITH THE REDUCED VISIBILITY AND SHOULD
BURN OFF BY LATE MORNING. WIND SHOULD REMAIN LIGHT FOR THIS
FORECAST.
&&
.FIRE WEATHER...
ISSUED AT 535 AM CDT SAT APR 27 2013
BOTH TODAY AND SUNDAY...THE LATEST FORECASTS NOW PUSH AFTERNOON
RELATIVE HUMIDITY VALUES BELOW 20 PERCENT IN PARTS OF THE CWA.
HOWEVER...THE PRESENCE OF LIGHTER WINDS THAN THOSE OBSERVED FRIDAY
IS CURRENTLY EXPECTED TO KEEP OVERALL FIRE DANGER RATHER
LIMITED...AS OPPOSED TO ELEVATED TO CRITICAL AS MIGHT BE THE CASE
WITH STRONGER WINDS. FOCUSING FIRST ON TODAY...SUB-20 PERCENT
RELATIVE HUMIDITY IS FORECAST TO FOCUS ONLY IN FAR
WESTERN/NORTHERN AREAS...GENERALLY WEST OF A GREELEY-BEAVER CITY
LINE. THEN ON SUNDAY...SUB-20 PERCENT RH IS PROGGED TO DEVELOP
ACROSS MOST COUNTIES WEST OF THE HIGHWAY 281 CORRIDOR. OF THE TWO
AFTERNOONS...SUNDAY BEARS THE MOST WATCHING TO MAKE SURE WINDS
SPEEDS DON/T CREEP HIGHER THAN CURRENTLY FORECAST.
FOR NOW...SUSTAINED WESTERLY SPEEDS AT MOST 10-15 MPH/GUSTS AT
MOST 15-20 MPH ARE FORECAST...KEEPING THINGS 5-10 MPH SHORT OF
POTENTIALLY CRITICAL FIRE THRESHOLDS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...ADO
SHORT TERM...HEINLEIN
LONG TERM...PFANNKUCH
AVIATION...HEINLEIN
FIRE WEATHER...PFANNKUCH
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
625 AM CDT SAT APR 27 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 348 AM CDT SAT APR 27 2013
LOW PRESSURE WILL CONTINUE TO TRACK ACROSS SRN CANADA TODAY
PRODUCING SOUTHWEST WINDS AHEAD OF A NORTHWEST WIND SHIFT ACROSS
NORTHWEST NEBRASKA. LIGHT WINDS...DEEP VERTICAL MIXING...NEARLY FULL
SUN AND A STRONG THERMAL RIDGE SHOULD PRODUCE HIGHS AROUND 80. THE
RAP MODEL IS LEADING THE WAY WITH THIS FEATURE.
TONIGHT...WEST WINDS DEVELOP MAINTAINING A THERMAL RIDGE ACROSS THE
FORECAST AREA AND LOWS IN THE 30S TO NEAR 40.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 348 AM CDT SAT APR 27 2013
ANOTHER DAY OF WELL ABOVE
NORMAL TEMPERATURES WILL BE EXPECTED FOR SUNDAY AS GUIDANCE SUGGEST
H85 TEMPERATURES APPROACHING...IF NOT EXCEEDING 20C. THE WARM LOWER
LEVELS WILL ALLOW SURFACE TEMPERATURES TO CLIMB WELL INTO THE
70S...AND POSSIBLY LOW 80S ACROSS THE ENTIRE FORECAST AREA. WITH THE
WELL ABOVE CLIMO HIGHS EXPECTED...FIRE CONCERNS WILL ONCE AGAIN
FLIRT WITH CRITICAL THRESHOLDS BY EARLY AFTERNOON. THE LOWEST RH
READINGS ARE ANTICIPATED ACROSS OUR WESTERN AND SOUTHERN FIRE ZONES
WHERE A EASTWARD ADVANCING SURFACE TROUGH LOW PRESSURE WILL WORK IN
CONCERT WITH STRONG TROPOSPHERIC MIXING TO ALLOW FOR OCCASIONAL
WIND GUSTS AT OR NEAR 20KTS /SLIGHTLY BELOW RFW WIND THRESHOLD/.
WILL HOLD OFF ON ANY FIRE HEADLINE FOR NOW. INTO THE OVERNIGHT A
WEAK PERTURBATION WILL RAPIDLY ADVANCE THROUGH QUASI-ZONAL FLOW AND
BRING A CHANCE OF A SHOWER...OR POSSIBLY A THUNDERSTORM...TO
NORTHERN PORTIONS OF THE CWA. THE OPERATIONAL MODELS INDICATE
ENOUGH OMEGA FOR PRECIPITATION PRODUCTION FOR MUCH OF THE
CWA...HOWEVER BUFR PROXIMITY SOUNDINGS SUGGEST THE LOWER TROPOSPHERE
WILL REMAIN FAIRLY DRY...THUS WILL MAINTAIN SLIGHT TO LOW END CHANCE
POPS ACROSS OUR NORTH OVERNIGHT SUNDAY INTO MONDAY...GENERALLY TIED
TO THE STRONGEST OMEGA AND BEST LOWER LEVEL MOISTURE PROFILES...BUT
LEAVE THE SOUTHERN HALF OF THE CWA MAINLY DRY...WITH ONLY A MENTION
OF SPRINKLES. SIMILAR CONDITIONS ARE EXPECTED FOR MONDAY...WITH THE
POSSIBILITY OF SLIGHTLY WARMER TEMPERATURES AND GREATER GUSTS. RED
FLAG WARNINGS MAY BE NEEDED FOR THE AFTERNOON HOURS. DRY CONDITIONS
WILL PREVAIL INTO EARLY TUESDAY AS A LACK IN KINEMATIC FORCING
RETURNS ONCE AGAIN...HOWEVER PRECIPITATION CHANCES INCREASE DURING
THE AFTERNOON HOURS ON TUESDAY AS A BAROCLINIC ZONE AND ASSOCIATED
SHORTWAVE CROSSES THE REGION. BESIDES THE PRECIPITATION
CHANCES...TEMPERATURES WILL BE MARKEDLY COOLER FOR MIDWEEK BEHIND
THE PASSING FRONT. IN FACT...FREEZE CONCERNS MAY BE REALIZED EARLY
WEDNESDAY AS THE LONGER RANGE SOLUTIONS SUGGEST H85 TEMPERATURES
FALL SOME 20-25C...WHICH WOULD PROVIDE FOR LOWS IN THE UPPER
20S-LOWER 30S AND HIGHS MAINLY IN THE 50S THROUGH MIDWEEK. THE
LONGER RANGE SOLUTION REMAIN IN POOR AGREEMENT AND THUS CONFIDENCE
IS LOW FOR MIDWEEK AND BEYOND...BUT THE GENERAL IDEA REMAINS OF
BROAD CYCLONIC FLOW ACROSS THE CENTRAL CONUS THROUGH THE END OF THE
WORK WEEK...WITH SLOWLY MODERATING TEMPERATURES AND POSSIBLY A
CHANCE AT ADDITIONAL PRECIPITATION. BUT WITH THE LOW CONFIDENCE IN
THE EXTENDED FORECAST...WILL MAINTAIN A DRY FORECAST BEYOND
WEDNESDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 623 AM CDT SAT APR 27 2013
VFR IS EXPECTED ALL AREAS TODAY AND TONIGHT. NEARLY FEATURELESS
WEATHER IS EXPECTED AS STORM SYSTEMS TRACK NORTH AND SOUTH OF THE
FCST AREA.
&&
.FIRE WEATHER...
ISSUED AT 348 AM CDT SAT APR 27 2013
A 75 PERCENT BLEND OF THE RAP AND 25 PERCENT OF THE REST OF THE
MODELS PRODUCES RELATIVE HUMIDITY BETWEEN 10 AND 20 PERCENT ACROSS
THE FCST AREA. ALL INDICATIONS ARE WINDS WILL BE WEAK AT LESS THAN
20 MPH.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...JACOBS
AVIATION...CDC
FIRE WEATHER...CDC
AREA FORECAST DISCUSSION
NWS HASTINGS NE
557 AM CDT SAT APR 27 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 535 AM CDT SAT APR 27 2013
BIGGEST CHALLENGE WILL BE DETERMINING EXTEND AND TIMING OF FOG THIS
MORNING...AND ALSO HIGH TEMPERATURES FOR TODAY.
WE HAPPEN TO BE IN AN AREA OF LOW-LEVEL CONVERGENCE THAT IS HANDLED
FAIRLY WELL BY THE HRRR...BUT NOT AS WELL BY OTHER MODELS...ALTHOUGH
THE LATEST RUN OF THE SREF ENSEMBLE SEEMS TO BE CATCHING UP WITH THE
HRRR. THE HRRR INDICATES THAT IT COULD BE AS LATE AS 10 AM UNTIL WE
CAN GET THE FOG BURNED OFF.
OVERALL...SPLIT FLOW CONTINUES IN THE UPPER LEVELS...WITH OUR CWA IN
BETWEEN...WHICH WHICH WILL LEND TO LIGHT FLOW IN GENERAL. THERE
SHOULD BE ENOUGH SUBSIDENCE TO HELP SCOUR OUT THE STRATUS AND FOG BY
LATE MORNING...WHICH SHOULD GIVE US PLENTY OF SUN BY AFTERNOON.
AREAS TO THE NORTH/WEST WILL WARM THE MOST AND I HAVE INCREASED HIGH
TEMPERATURES IN THESE AREAS FROM THE PREVIOUS FORECAST...WITH
SOUTHEASTERN AREAS A BIT COOLER WHERE STRATUS MIGHT STICK AROUND A
BIT LONGER AND 850 MB TEMPERATURES WILL BE COOLER. I PLACED QUITE A
BIT OF WEIGHT ON HOW MODELS HAVE PERFORMED VERY RECENTLY TO DERIVE
HIGH TEMPERATURES FOR TODAY. WENT CLOSE TO PREVIOUS FORECAST LOW
TEMPERATURES.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 535 AM CDT SAT APR 27 2013
THIS 6-DAY PERIOD LOOKS TO FEATURE QUITE A ROLLER COASTER RIDE IN
TEMPERATURES...STARTING OUT WITH A CONTINUATION OF THE ONGOING
VERY MILD STREAK...BUT THEN SETTLING DOWN BELOW NORMAL AGAIN FOR
WEDNESDAY-FRIDAY. UNFORTUNATELY...THERE ARE SUGGESTIONS BY SOME
MODELS...ESPECIALLY THE ECMWF...THAT THIS NEXT BATCH OF COLD COULD
BE QUITE A BIT MORE INTENSE THAN THE CURRENT FORECAST
DEPICTS...AND DARE WE SAY BRING THE POTENTIAL FOR AT LEAST A
RAIN/SNOW MIX TO SOME AREAS. HOWEVER...GIVEN THAT THIS POTENTIALLY
BIG COOL DOWN IS STILL 4+ DAYS AWAY AND UNCERTAINTY REMAINS
PLENTIFUL...HAVE ONLY MADE MINOR DOWNWARD TWEAKS TO PREVIOUS
FORECAST TEMPS FOR NOW...BUT STAY TUNED FOR POTENTIALLY MORE
DRASTIC CHANGES. GIVEN THAT THIS POTENTIAL COLD SNAP WILL OCCUR IN
EARLY MAY...ITS NOW NOT OUT OF THE QUESTION THAT A FROST
ADVISORY/FREEZE WARNING SITUATION MAY UNFOLD SOMETIME DURING THE
WED-FRI TIME FRAME AS WELL...ALTHOUGH A WIDESPREAD HARD KILLING
FREEZE OF 28 DEGREES OR LOWER DOES NOT SEEM EVIDENT AT THIS TIME.
TURNING TO OTHER ELEMENTS OF THE FORECAST...IT STILL LOOKS LIKE
THE TUES AFTERNOON/EVENING TIME FRAME HOLDS COULD HAVE SEVERE
THUNDERSTORM POTENTIAL...ESPECIALLY WITHIN THE SOUTHEAST 1/3 OF
THE CWA. LAST BUT NOT LEAST...WILL HAVE TO KEEP AN EYE SUNDAY
AFTERNOON FOR AT LEAST LIMITED FIRE DANGER...AS DISCUSSED IN A BIT
MORE DETAIL IN THE SEPARATE FIRE WEATHER SECTION BELOW.
STARTING IN MORE DETAIL WITH SUNDAY/SUNDAY NIGHT...THE VAST
MAJORITY...IF NOT THE ENTIRE CWA SHOULD STAY DRY...WITH THE
DAYTIME HIGHS LIKELY THE WARMEST OF THE ONGOING WARM
STRETCH...WITH MUCH OF THE CWA FORECAST TO BREACH 80 DEGREES FOR
THE FIRST TIME THIS SPRING. ALOFT...VARIOUS MODELS SUCH AS THE 00Z
NAM/GFS/ECMWF ARE IN DECENT AGREEMENT WITH BROAD WEST-NORTHWEST
FLOW...AS ONE MID LEVEL SHORTWAVE DEPARTS EASTWARD THROUGH THE
MIDWEST/OH VALLEY...WHILE THE NEXT BATCH OF LOW AMPLITUDE MID
LEVEL TROUGHS BRUSHES ACROSS THE DAKOTAS/MAINLY NORTHERN NEB ON
SUN NIGHT. THROUGH MOST OF THE DAY...FAIRLY LIGHT WEST-SOUTHWEST
BREEZES AND PLENTY OF SUNSHINE WILL PREVAIL. HOWEVER...BY LATE
AFTERNOON INTO EARLY EVENING...A WEAK COLD FRONT WILL SAG INTO THE
NORTHERN CWA...PUSHED SOUTHWARD BY THE AFOREMENTIONED NORTHERN
PLAINS ENERGY. ALTHOUGH HAVE LEFT OUT ANY PRECIP MENTION...WENT
AHEAD WITH SILENT 10 POPS ACROSS SEVERAL NORTHERN/WESTERN COUNTIES
LATE AFTERNOON INTO THE EVENING NEAR THIS BOUNDARY TO AT LEAST
HINT AT THE VERY LOW POTENTIAL FOR A SHOWER OR WEAK
THUNDERSTORM...ALTHOUGH THE LATEST 4KM WRF-NMM KEEPS ANY PRECIP
POTENTIAL NORTH OF THE CWA...ALTHOUGH THIS BEARS WATCHING. LATE
SUNDAY NIGHT...KEPT A MEASURABLE POP OUT OF THE FORECAST...BUT
EXPANDED THE PREVIOUSLY INTRODUCED CHANCE OF SPRINKLES ACROSS MOST
OF THE NORTHERN 1/3 OF THE CWA...AS A BAND OF MID LEVEL SATURATION
WORKS EASTWARD ACROSS THE REGION IN ASSOCIATION WITH THE PASSING
WEAK WAVE. ALTHOUGH LATER SHIFTS MAY NEED TO CONSIDER ADDING A LOW
MEASURABLE POP FOR THIS ACTIVITY ESPECIALLY FAR NORTH AROUND
ORD/GREELEY...DRY LOW LEVELS STILL SEEM TO SUGGEST THAT SPRINKLES
SHOULD LARGELY SUFFICE. TEMP-WISE...MADE LITTLE CHANGE TO HIGHS
AND LOWS...WITH ALL AREAS TOPPING OUT SOMEWHERE BETWEEN
79-85...AND BOTTOMING OUT IN THE UPPER 40S TO LOW 50S SUNDAY
NIGHT. BASED ON DRY WESTERLY FLOW ESPECIALLY EVIDENT IN THE LAST
FEW NAM RUNS...AFTERNOON DEWPOINTS WERE LOWERED SEVERAL DEGREES
FROM PREVIOUS...THUS PUSHING A GOOD CHUNK OF THE AREA TO 20
PERCENT OR LOWER RELATIVE HUMIDITY FOR A FEW HOURS.
MONDAY/MONDAY NIGHT...HAVE LEFT THIS ENTIRE 24 HOURS PRECIP
MENTION-FREE FOR NOW...ALTHOUGH AS NOTED BY PREVIOUS FORECASTERS
THIS IS NOT NECESSARILY A GUARANTEE FOR ALL AREAS AND WILL BEAR
WATCHING. IN THE MID LEVELS...THE GENERAL STORY INVOLVES THE
AFOREMENTIONED LOW AMPLITUDE SHORTWAVE TROUGH DEPARTING TO THE
EAST...WHILE A STRONGER UPSTREAM DISTURBANCE AND ASSOCIATED UPPER
JET STREAK STARTS TO CARVE A BIT MORE AMPLIFIED TROUGH ACROSS THE
NORTHERN ROCKIES/NORTHERN PLAINS. BREEZES DURING THE DAY WILL
GRADUALLY TURN FROM EASTERLY TO SOUTHERLY IN RESPONSE TO DEEPENING
LOW PRESSURE TO THE NORTHWEST...WITH THE LEADING EDGES OF THE NEXT
COLD FRONT THEN POSSIBLY REACHING THE NORTHWEST CWA BY SUNRISE
TUESDAY MORNING. AS FOR POSSIBLE PRECIP CHANCES TO CONSIDER IN
LATER FORECASTS...FOR ONE THERE COULD BE A BRIEF PERIOD OF
LINGERING SPRINKLES RIGHT AWAY IN THE MORNING. SECONDLY...THE
LATEST NAM SUGGESTS ANOTHER BATCH OF SHOWER ACTIVITY COULD BRUSH
NORTHERN COUNTIES VERY LATE MON NIGHT...ALTHOUGH THIS IS NOT WELL-
SUPPORTED BY OTHER SOLUTIONS. LASTLY...ALTHOUGH UNLIKELY...SUPPOSE
ITS NOT COMPLETELY OUT OF THE QUESTION THAT A LATE AFTERNOON
THUNDERSTORM COULD DEVELOP PRIMARILY IN THE SOUTHEAST CWA IN
RESPONSE TO 500-1000 J/KG OF 0-1KM MLCAPE...BUT FORECAST SOUNDINGS
SUGGEST THAT CAPPING AND LACK OF LIFT IN THE WAKE OF THE INITIAL
DEPARTING WAVE SHOULD PRECLUDE THIS SCENARIO. BOTTOM LINE...NO
PRECIP RISK MENTIONED AT THIS TIME. TEMP-WISE...ALTHOUGH STILL
QUITE WARM...SLIGHTLY LESS FAVORABLE MIXING THAN SUNDAY IS
EXPECTED TO KEEP TEMPS VERY SLIGHTLY COOLER...AND HAVE MOST AREAS
TOPPING OUT 77-82.
TUESDAY/TUESDAY NIGHT...AS MENTIONED ABOVE...THE LATE
AFTERNOON/EVENING TIME FRAME HOLDS THE BEST POTENTIAL FOR A ROUND
OF POTENTIALLY SEVERE STORMS MAINLY ACROSS THE SOUTHEAST 1/3 TO
1/2 OF THE CWA...BUT THIS IS ALSO FAR FROM A SURE THING AS SO MUCH
WILL DEPEND ON STILL-UNCERTAIN FRONTAL TIMING. ALOFT...BOTH THE
ECMWF/GFS SOLUTIONS ARE STILL IN PRETTY DECENT AGREEMENT AT THIS
POINT THAT A LARGE SCALE TROUGH AXIS WILL CONTINUE TO AMPLIFY
ALONG AN AXIS FROM THE NORTHERN PLAINS TO CENTRAL ROCKIES...WHILE
IN THE LOW LEVELS A RATHER HEALTHY COLD FRONT PUSHES SOUTHWARD
ACROSS THE CWA. ALTHOUGH A DECENT CAP SHOULD HOLD CONVECTION AT
BAY UNTIL AT LEAST MID-AFTERNOON...SOMETIME IN THE 21Z-01Z TIME
FRAME IS CURRENTLY EXPECTED TO FEATURE THE DEVELOPMENT OF STORMS
NEAR THE INVADING COLD FRONT...WHICH COULD BECOME SEVERE IN A
LIKELY QUASI-LINEAR FASHION PER THE ECMWF FORECAST OF 1000-1500
J/KG MLCAPE AND MODEST DEEP LAYER SHEAR. AS THE NIGHT WEARS
ON...THE OVERALL THUNDERSTORM INTENSITY SHOULD DIMINISH...BUT
COVERAGE OF WIDESPREAD RAIN AND EMBEDDED THUNDERSTORMS WOULD
INCREASE ACROSS NEARLY THE ENTIRE CWA AS A STRONGLY FORCED BAND OF
MID LEVEL CONVERGENCE/FRONTOGENESIS INVADES THE CWA FROM NORTHWEST
TO SOUTHEAST. ENOUGH CONSISTENCY IN THIS SCENARIO FOR TUESDAY
NIGHT EXISTS THAT POPS WERE RAISED INTO LIKELY TERRITORY IN MANY
AREAS. TEMP-WISE...HIGHS TUESDAY WILL BE TRICKY DUE TO UNCERTAINTY
IN THE SPEED OF THE INVADING COLD FRONT...BUT FOR NOW KEPT A
GENERAL RANGE FROM NEAR 70 NORTH TO NEAR 80 SOUTH.
FOR THE WEDNESDAY-FRIDAY TIME FRAME...THERE JUST ISN/T MUCH TO BE
GAINED YET BY GOING INTO MUCH DETAIL DUE TO VARYING MODEL
SOLUTIONS REGARDING THE EVOLUTION OF THE PASSING LARGE SCALE
TROUGH. IN GENERAL...BOTH THE 00Z ECMWF/GFS SOLUTIONS DEPICT A
SLOWING AND STALLING MID/UPPER TROUGH AS IT PASSES INTO THE
CENTRAL PORTION OF THE NATION...AS AN EXPANSIVE BLOCKING RIDGE
SETS UP SHOP OVER THE EASTERN CONUS. AS THIS BLOCK TAKES SHAPE...A
CLOSED...COLD AND FAIRLY COMPACT MID LEVEL LOW IS PROGGED TO FORM
SOMEWHERE...WITH THE ECMWF CLOSING THIS OFF OVER THE KS/OK AREA BY
THURS NIGHT INTO FRIDAY...WHILE THE GFS CLOSES THIS DEEP LOW OFF
MORE SO OVER MO/AR. ABOUT THE ONLY THING THE CURRENT FORECAST HAS
MUCH CONFIDENCE IN IS THAT DECENT PRECIP CHANCES WILL CONTINUE
ACROSS NEARLY THE ENTIRE CWA DURING THE DAY WEDNESDAY. HAVE KEPT
THIS RAIN FOR NOW...BUT THE VERY COLD ECMWF SOLUTION WOULD SUGGEST
A SNOW MIX POSSIBLE. THE CURRENT FORECAST THEN LINGERS A LESSER
CHANCE OF A RAIN/SNOW MIX ACROSS ROUGHLY THE SOUTHEAST 1/3 OF THE
CWA WED NIGHT...WHILE KEEPING THURSDAY-FRIDAY PRECIP-FREE.
HOWEVER...THIS PRECIP-FREE DEPICTION WILL NOT LAST IF THE ECMWF IS
IN FACT ONTO SOMETHING...AS IT DEPICTS A POSSIBLE RAIN/SNOW MIX
LASTING INTO FRIDAY IN SOME AREAS. RE-EMPHASIZING THE MAIN POINTS
HERE...A MUCH COOLER WEATHER REGIME WILL SETTLE IN BY MID-LATE
WEEK...BUT WE ARE STILL A FEW DAYS AWAY FROM PINNING DOWN JUST
HOW COLD IT MIGHT REALLY GET...AND WHETHER A RISK REALLY EXISTS
FOR POSSIBLY ANOTHER ROUND OF LATE-SEASON SNOW AND/OR SUB-
FREEZING OVERNIGHT LOW TEMPS. STAY TUNED...
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 546 AM CDT SAT APR 27 2013
REDUCED VISIBILITY IS THE BIGGEST CONCERN FOR THE FIRST 4 HOURS OR
SO. DENSE FOG IS CLOSE BY NEAR THE INTERSTATE AND AT THE AURORA
OBSERVATION. I WENT WITH A MIDDLE ROAD AND ANTICIPATED A 1SM
VISIBILITY ALTHOUGH THE TERMINAL HAS NOT DROPPED BELOW MVFR AS OF
THIS AFD. CONFIDENCE IS NOT HIGH FOR VISIBILITY. STRATUS IS
EXPECTED IN ASSOCIATION WITH THE REDUCED VISIBILITY AND SHOULD
BURN OFF BY LATE MORNING. WIND SHOULD REMAIN LIGHT FOR THIS
FORECAST.
&&
.FIRE WEATHER...
ISSUED AT 535 AM CDT SAT APR 27 2013
BOTH TODAY AND SUNDAY...THE LATEST FORECASTS NOW PUSH AFTERNOON
RELATIVE HUMIDITY VALUES BELOW 20 PERCENT IN PARTS OF THE CWA.
HOWEVER...THE PRESENCE OF LIGHTER WINDS THAN THOSE OBSERVED FRIDAY
IS CURRENTLY EXPECTED TO KEEP OVERALL FIRE DANGER RATHER
LIMITED...AS OPPOSED TO ELEVATED TO CRITICAL AS MIGHT BE THE CASE
WITH STRONGER WINDS. FOCUSING FIRST ON TODAY...SUB-20 PERCENT
RELATIVE HUMIDITY IS FORECAST TO FOCUS ONLY IN FAR
WESTERN/NORTHERN AREAS...GENERALLY WEST OF A GREELEY-BEAVER CITY
LINE. THEN ON SUNDAY...SUB-20 PERCENT RH IS PROGGED TO DEVELOP
ACROSS MOST COUNTIES WEST OF THE HIGHWAY 281 CORRIDOR. OF THE TWO
AFTERNOONS...SUNDAY BEARS THE MOST WATCHING TO MAKE SURE WINDS
SPEEDS DON/T CREEP HIGHER THAN CURRENTLY FORECAST.
FOR NOW...SUSTAINED WESTERLY SPEEDS AT MOST 10-15 MPH/GUSTS AT
MOST 15-20 MPH ARE FORECAST...KEEPING THINGS 5-10 MPH SHORT OF
POTENTIALLY CRITICAL FIRE THRESHOLDS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR NEZ040-041-
046>049-060>064-072>077-082>087.
KS...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR KSZ005>007-
017-018.
&&
$$
SHORT TERM...HEINLEIN
LONG TERM...PFANNKUCH
AVIATION...HEINLEIN
FIRE WEATHER...PFANNKUCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
535 AM CDT SAT APR 27 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 535 AM CDT SAT APR 27 2013
BIGGEST CHALLENGE WILL BE DETERMINING EXTEND AND TIMING OF FOG THIS
MORNING...AND ALSO HIGH TEMPERATURES FOR TODAY.
WE HAPPEN TO BE IN AN AREA OF LOW-LEVEL CONVERGENCE THAT IS HANDLED
FAIRLY WELL BY THE HRRR...BUT NOT AS WELL BY OTHER MODELS...ALTHOUGH
THE LATEST RUN OF THE SREF ENSEMBLE SEEMS TO BE CATCHING UP WITH THE
HRRR. THE HRRR INDICATES THAT IT COULD BE AS LATE AS 10 AM UNTIL WE
CAN GET THE FOG BURNED OFF.
OVERALL...SPLIT FLOW CONTINUES IN THE UPPER LEVELS...WITH OUR CWA IN
BETWEEN...WHICH WHICH WILL LEND TO LIGHT FLOW IN GENERAL. THERE
SHOULD BE ENOUGH SUBSIDENCE TO HELP SCOUR OUT THE STRATUS AND FOG BY
LATE MORNING...WHICH SHOULD GIVE US PLENTY OF SUN BY AFTERNOON.
AREAS TO THE NORTH/WEST WILL WARM THE MOST AND I HAVE INCREASED HIGH
TEMPERATURES IN THESE AREAS FROM THE PREVIOUS FORECAST...WITH
SOUTHEASTERN AREAS A BIT COOLER WHERE STRATUS MIGHT STICK AROUND A
BIT LONGER AND 850 MB TEMPERATURES WILL BE COOLER. I PLACED QUITE A
BIT OF WEIGHT ON HOW MODELS HAVE PERFORMED VERY RECENTLY TO DERIVE
HIGH TEMPERATURES FOR TODAY. WENT CLOSE TO PREVIOUS FORECAST LOW
TEMPERATURES.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 535 AM CDT SAT APR 27 2013
THIS 6-DAY PERIOD LOOKS TO FEATURE QUITE A ROLLER COASTER RIDE IN
TEMPERATURES...STARTING OUT WITH A CONTINUATION OF THE ONGOING
VERY MILD STREAK...BUT THEN SETTLING DOWN BELOW NORMAL AGAIN FOR
WEDNESDAY-FRIDAY. UNFORTUNATELY...THERE ARE SUGGESTIONS BY SOME
MODELS...ESPECIALLY THE ECMWF...THAT THIS NEXT BATCH OF COLD COULD
BE QUITE A BIT MORE INTENSE THAN THE CURRENT FORECAST
DEPICTS...AND DARE WE SAY BRING THE POTENTIAL FOR AT LEAST A
RAIN/SNOW MIX TO SOME AREAS. HOWEVER...GIVEN THAT THIS POTENTIALLY
BIG COOL DOWN IS STILL 4+ DAYS AWAY AND UNCERTAINTY REMAINS
PLENTIFUL...HAVE ONLY MADE MINOR DOWNWARD TWEAKS TO PREVIOUS
FORECAST TEMPS FOR NOW...BUT STAY TUNED FOR POTENTIALLY MORE
DRASTIC CHANGES. GIVEN THAT THIS POTENTIAL COLD SNAP WILL OCCUR IN
EARLY MAY...ITS NOW NOT OUT OF THE QUESTION THAT A FROST
ADVISORY/FREEZE WARNING SITUATION MAY UNFOLD SOMETIME DURING THE
WED-FRI TIME FRAME AS WELL...ALTHOUGH A WIDESPREAD HARD KILLING
FREEZE OF 28 DEGREES OR LOWER DOES NOT SEEM EVIDENT AT THIS TIME.
TURNING TO OTHER ELEMENTS OF THE FORECAST...IT STILL LOOKS LIKE
THE TUES AFTERNOON/EVENING TIME FRAME HOLDS COULD HAVE SEVERE
THUNDERSTORM POTENTIAL...ESPECIALLY WITHIN THE SOUTHEAST 1/3 OF
THE CWA. LAST BUT NOT LEAST...WILL HAVE TO KEEP AN EYE SUNDAY
AFTERNOON FOR AT LEAST LIMITED FIRE DANGER...AS DISCUSSED IN A BIT
MORE DETAIL IN THE SEPARATE FIRE WEATHER SECTION BELOW.
STARTING IN MORE DETAIL WITH SUNDAY/SUNDAY NIGHT...THE VAST
MAJORITY...IF NOT THE ENTIRE CWA SHOULD STAY DRY...WITH THE
DAYTIME HIGHS LIKELY THE WARMEST OF THE ONGOING WARM
STRETCH...WITH MUCH OF THE CWA FORECAST TO BREACH 80 DEGREES FOR
THE FIRST TIME THIS SPRING. ALOFT...VARIOUS MODELS SUCH AS THE 00Z
NAM/GFS/ECMWF ARE IN DECENT AGREEMENT WITH BROAD WEST-NORTHWEST
FLOW...AS ONE MID LEVEL SHORTWAVE DEPARTS EASTWARD THROUGH THE
MIDWEST/OH VALLEY...WHILE THE NEXT BATCH OF LOW AMPLITUDE MID
LEVEL TROUGHS BRUSHES ACROSS THE DAKOTAS/MAINLY NORTHERN NEB ON
SUN NIGHT. THROUGH MOST OF THE DAY...FAIRLY LIGHT WEST-SOUTHWEST
BREEZES AND PLENTY OF SUNSHINE WILL PREVAIL. HOWEVER...BY LATE
AFTERNOON INTO EARLY EVENING...A WEAK COLD FRONT WILL SAG INTO THE
NORTHERN CWA...PUSHED SOUTHWARD BY THE AFOREMENTIONED NORTHERN
PLAINS ENERGY. ALTHOUGH HAVE LEFT OUT ANY PRECIP MENTION...WENT
AHEAD WITH SILENT 10 POPS ACROSS SEVERAL NORTHERN/WESTERN COUNTIES
LATE AFTERNOON INTO THE EVENING NEAR THIS BOUNDARY TO AT LEAST
HINT AT THE VERY LOW POTENTIAL FOR A SHOWER OR WEAK
THUNDERSTORM...ALTHOUGH THE LATEST 4KM WRF-NMM KEEPS ANY PRECIP
POTENTIAL NORTH OF THE CWA...ALTHOUGH THIS BEARS WATCHING. LATE
SUNDAY NIGHT...KEPT A MEASURABLE POP OUT OF THE FORECAST...BUT
EXPANDED THE PREVIOUSLY INTRODUCED CHANCE OF SPRINKLES ACROSS MOST
OF THE NORTHERN 1/3 OF THE CWA...AS A BAND OF MID LEVEL SATURATION
WORKS EASTWARD ACROSS THE REGION IN ASSOCIATION WITH THE PASSING
WEAK WAVE. ALTHOUGH LATER SHIFTS MAY NEED TO CONSIDER ADDING A LOW
MEASURABLE POP FOR THIS ACTIVITY ESPECIALLY FAR NORTH AROUND
ORD/GREELEY...DRY LOW LEVELS STILL SEEM TO SUGGEST THAT SPRINKLES
SHOULD LARGELY SUFFICE. TEMP-WISE...MADE LITTLE CHANGE TO HIGHS
AND LOWS...WITH ALL AREAS TOPPING OUT SOMEWHERE BETWEEN
79-85...AND BOTTOMING OUT IN THE UPPER 40S TO LOW 50S SUNDAY
NIGHT. BASED ON DRY WESTERLY FLOW ESPECIALLY EVIDENT IN THE LAST
FEW NAM RUNS...AFTERNOON DEWPOINTS WERE LOWERED SEVERAL DEGREES
FROM PREVIOUS...THUS PUSHING A GOOD CHUNK OF THE AREA TO 20
PERCENT OR LOWER RELATIVE HUMIDITY FOR A FEW HOURS.
MONDAY/MONDAY NIGHT...HAVE LEFT THIS ENTIRE 24 HOURS PRECIP
MENTION-FREE FOR NOW...ALTHOUGH AS NOTED BY PREVIOUS FORECASTERS
THIS IS NOT NECESSARILY A GUARANTEE FOR ALL AREAS AND WILL BEAR
WATCHING. IN THE MID LEVELS...THE GENERAL STORY INVOLVES THE
AFOREMENTIONED LOW AMPLITUDE SHORTWAVE TROUGH DEPARTING TO THE
EAST...WHILE A STRONGER UPSTREAM DISTURBANCE AND ASSOCIATED UPPER
JET STREAK STARTS TO CARVE A BIT MORE AMPLIFIED TROUGH ACROSS THE
NORTHERN ROCKIES/NORTHERN PLAINS. BREEZES DURING THE DAY WILL
GRADUALLY TURN FROM EASTERLY TO SOUTHERLY IN RESPONSE TO DEEPENING
LOW PRESSURE TO THE NORTHWEST...WITH THE LEADING EDGES OF THE NEXT
COLD FRONT THEN POSSIBLY REACHING THE NORTHWEST CWA BY SUNRISE
TUESDAY MORNING. AS FOR POSSIBLE PRECIP CHANCES TO CONSIDER IN
LATER FORECASTS...FOR ONE THERE COULD BE A BRIEF PERIOD OF
LINGERING SPRINKLES RIGHT AWAY IN THE MORNING. SECONDLY...THE
LATEST NAM SUGGESTS ANOTHER BATCH OF SHOWER ACTIVITY COULD BRUSH
NORTHERN COUNTIES VERY LATE MON NIGHT...ALTHOUGH THIS IS NOT WELL-
SUPPORTED BY OTHER SOLUTIONS. LASTLY...ALTHOUGH UNLIKELY...SUPPOSE
ITS NOT COMPLETELY OUT OF THE QUESTION THAT A LATE AFTERNOON
THUNDERSTORM COULD DEVELOP PRIMARILY IN THE SOUTHEAST CWA IN
RESPONSE TO 500-1000 J/KG OF 0-1KM MLCAPE...BUT FORECAST SOUNDINGS
SUGGEST THAT CAPPING AND LACK OF LIFT IN THE WAKE OF THE INITIAL
DEPARTING WAVE SHOULD PRECLUDE THIS SCENARIO. BOTTOM LINE...NO
PRECIP RISK MENTIONED AT THIS TIME. TEMP-WISE...ALTHOUGH STILL
QUITE WARM...SLIGHTLY LESS FAVORABLE MIXING THAN SUNDAY IS
EXPECTED TO KEEP TEMPS VERY SLIGHTLY COOLER...AND HAVE MOST AREAS
TOPPING OUT 77-82.
TUESDAY/TUESDAY NIGHT...AS MENTIONED ABOVE...THE LATE
AFTERNOON/EVENING TIME FRAME HOLDS THE BEST POTENTIAL FOR A ROUND
OF POTENTIALLY SEVERE STORMS MAINLY ACROSS THE SOUTHEAST 1/3 TO
1/2 OF THE CWA...BUT THIS IS ALSO FAR FROM A SURE THING AS SO MUCH
WILL DEPEND ON STILL-UNCERTAIN FRONTAL TIMING. ALOFT...BOTH THE
ECMWF/GFS SOLUTIONS ARE STILL IN PRETTY DECENT AGREEMENT AT THIS
POINT THAT A LARGE SCALE TROUGH AXIS WILL CONTINUE TO AMPLIFY
ALONG AN AXIS FROM THE NORTHERN PLAINS TO CENTRAL ROCKIES...WHILE
IN THE LOW LEVELS A RATHER HEALTHY COLD FRONT PUSHES SOUTHWARD
ACROSS THE CWA. ALTHOUGH A DECENT CAP SHOULD HOLD CONVECTION AT
BAY UNTIL AT LEAST MID-AFTERNOON...SOMETIME IN THE 21Z-01Z TIME
FRAME IS CURRENTLY EXPECTED TO FEATURE THE DEVELOPMENT OF STORMS
NEAR THE INVADING COLD FRONT...WHICH COULD BECOME SEVERE IN A
LIKELY QUASI-LINEAR FASHION PER THE ECMWF FORECAST OF 1000-1500
J/KG MLCAPE AND MODEST DEEP LAYER SHEAR. AS THE NIGHT WEARS
ON...THE OVERALL THUNDERSTORM INTENSITY SHOULD DIMINISH...BUT
COVERAGE OF WIDESPREAD RAIN AND EMBEDDED THUNDERSTORMS WOULD
INCREASE ACROSS NEARLY THE ENTIRE CWA AS A STRONGLY FORCED BAND OF
MID LEVEL CONVERGENCE/FRONTOGENESIS INVADES THE CWA FROM NORTHWEST
TO SOUTHEAST. ENOUGH CONSISTENCY IN THIS SCENARIO FOR TUESDAY
NIGHT EXISTS THAT POPS WERE RAISED INTO LIKELY TERRITORY IN MANY
AREAS. TEMP-WISE...HIGHS TUESDAY WILL BE TRICKY DUE TO UNCERTAINTY
IN THE SPEED OF THE INVADING COLD FRONT...BUT FOR NOW KEPT A
GENERAL RANGE FROM NEAR 70 NORTH TO NEAR 80 SOUTH.
FOR THE WEDNESDAY-FRIDAY TIME FRAME...THERE JUST ISN/T MUCH TO BE
GAINED YET BY GOING INTO MUCH DETAIL DUE TO VARYING MODEL
SOLUTIONS REGARDING THE EVOLUTION OF THE PASSING LARGE SCALE
TROUGH. IN GENERAL...BOTH THE 00Z ECMWF/GFS SOLUTIONS DEPICT A
SLOWING AND STALLING MID/UPPER TROUGH AS IT PASSES INTO THE
CENTRAL PORTION OF THE NATION...AS AN EXPANSIVE BLOCKING RIDGE
SETS UP SHOP OVER THE EASTERN CONUS. AS THIS BLOCK TAKES SHAPE...A
CLOSED...COLD AND FAIRLY COMPACT MID LEVEL LOW IS PROGGED TO FORM
SOMEWHERE...WITH THE ECMWF CLOSING THIS OFF OVER THE KS/OK AREA BY
THURS NIGHT INTO FRIDAY...WHILE THE GFS CLOSES THIS DEEP LOW OFF
MORE SO OVER MO/AR. ABOUT THE ONLY THING THE CURRENT FORECAST HAS
MUCH CONFIDENCE IN IS THAT DECENT PRECIP CHANCES WILL CONTINUE
ACROSS NEARLY THE ENTIRE CWA DURING THE DAY WEDNESDAY. HAVE KEPT
THIS RAIN FOR NOW...BUT THE VERY COLD ECMWF SOLUTION WOULD SUGGEST
A SNOW MIX POSSIBLE. THE CURRENT FORECAST THEN LINGERS A LESSER
CHANCE OF A RAIN/SNOW MIX ACROSS ROUGHLY THE SOUTHEAST 1/3 OF THE
CWA WED NIGHT...WHILE KEEPING THURSDAY-FRIDAY PRECIP-FREE.
HOWEVER...THIS PRECIP-FREE DEPICTION WILL NOT LAST IF THE ECMWF IS
IN FACT ONTO SOMETHING...AS IT DEPICTS A POSSIBLE RAIN/SNOW MIX
LASTING INTO FRIDAY IN SOME AREAS. RE-EMPHASIZING THE MAIN POINTS
HERE...A MUCH COOLER WEATHER REGIME WILL SETTLE IN BY MID-LATE
WEEK...BUT WE ARE STILL A FEW DAYS AWAY FROM PINNING DOWN JUST
HOW COLD IT MIGHT REALLY GET...AND WHETHER A RISK REALLY EXISTS
FOR POSSIBLY ANOTHER ROUND OF LATE-SEASON SNOW AND/OR SUB-
FREEZING OVERNIGHT LOW TEMPS. STAY TUNED...
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1252 AM CDT SAT APR 27 2013
THE BIGGEST ISSUE WILL BE VISIBILITY. THE HRRR MODEL SEEMS TO BE
DOING THE BEST AT PICKING UP ON FOG AND STRATUS TO THE SOUTH...SO
FOLLOWING THIS MODEL MORE CLOSELY THAN THE OTHERS...WHICH ARE NOT
PREDICTING MUCH FOG IF ANY. SUBSIDENCE SHOULD HELP SCOUR OUT THE
FOG AND STRATUS BY MID-MORNING SATURDAY.
&&
.FIRE WEATHER...
ISSUED AT 535 AM CDT SAT APR 27 2013
BOTH TODAY AND SUNDAY...THE LATEST FORECASTS NOW PUSH AFTERNOON
RELATIVE HUMIDITY VALUES BELOW 20 PERCENT IN PARTS OF THE CWA.
HOWEVER...THE PRESENCE OF LIGHTER WINDS THAN THOSE OBSERVED FRIDAY
IS CURRENTLY EXPECTED TO KEEP OVERALL FIRE DANGER RATHER
LIMITED...AS OPPOSED TO ELEVATED TO CRITICAL AS MIGHT BE THE CASE
WITH STRONGER WINDS. FOCUSING FIRST ON TODAY...SUB-20 PERCENT
RELATIVE HUMIDITY IS FORECAST TO FOCUS ONLY IN FAR
WESTERN/NORTHERN AREAS...GENERALLY WEST OF A GREELEY-BEAVER CITY
LINE. THEN ON SUNDAY...SUB-20 PERCENT RH IS PROGGED TO DEVELOP
ACROSS MOST COUNTIES WEST OF THE HIGHWAY 281 CORRIDOR. OF THE TWO
AFTERNOONS...SUNDAY BEARS THE MOST WATCHING TO MAKE SURE WINDS
SPEEDS DON/T CREEP HIGHER THAN CURRENTLY FORECAST.
FOR NOW...SUSTAINED WESTERLY SPEEDS AT MOST 10-15 MPH/GUSTS AT
MOST 15-20 MPH ARE FORECAST...KEEPING THINGS 5-10 MPH SHORT OF
POTENTIALLY CRITICAL FIRE THRESHOLDS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR NEZ040-041-
046>049-060>064-072>077-082>087.
KS...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR KSZ005>007-
017-018.
&&
$$
SHORT TERM...HEINLEIN
LONG TERM...PFANNKUCH
AVIATION...HEINLEIN
FIRE WEATHER...PFANNKUCH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1020 AM EDT SAT APR 27 2013
.SYNOPSIS...
CLOUDS WILL BE ON THE INCREASE TODAY. PASSING SHOWERS WILL
DEVELOP INLAND LATER THIS AFTERNOON AND OVERNIGHT. SEVERAL
DISTURBANCES MOVING EAST ACROSS THE GULF STATES WILL LEAD TO
INCREASING CLOUDS SUNDAY AND ELEVATED RAIN CHANCES LATE SUNDAY
AND MONDAY. A SLIGHT DRYING TREND IS EXPECTED DURING THE MIDDLE OF
NEXT WEEK WITH AN APPROACHING COLD FRONT LATE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1015 AM SATURDAY...THE SHOWERS OVER SOUTH CAROLINA CONTINUE TO
WEAKEN AS THEY MOVE INTO THE DRIER AIR TO THE EAST. THE NAM AND
LATEST RUC ALL ARE SHOWING THE COLUMN FROM 700 MB TO 600 MB
MOISTENING UP WITH THE ONLY MINOR LIFT ABOVE 700 MB. CLOUD COVER
WILL STAY OVER THE SOUTHERN 2/3 OF THE AREA WITH PORTIONS OF
SOUTHEAST NORTH CAROLINA SEEING A FEW MORE BREAKS IN THE CLOUDS
THIS AFTERNOON.
THE 09 UTC SREF IS SHOWING THE PROBABILITY OF 12H PCPN GREATER
THAN 0.01 INCHES TO BE HIGH THIS EVENING AND MAINLY NORTH AND WEST
OF INTERSTATE 20 AND INTERSTATE 95. THE 0.10 INCH PROBABILITY 70%
CHANCE IS JUST WEST OF OUR FORECASTER. AS MENTIONED IN PREVIOUS
DISCUSSION THE LIFT IS ELEVATED AND THE CHANCE OF HEAVY RAIN OR
VERY REMOTE, BUT THE CHANCE OF MEASURABLE PRECIPITATION OUT WEST
INCREASES INTO THE EVENING HOURS.
THERE WERE NO CHANGES ON THE HIGH WITH MAXIMUM TEMPERATURES
REACHING THE LOWER 70S AND TONIGHT THE LOWS ARE EXPECTED TO FALL
TO THE 50-55 DEGREE RANGE.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...SURFACE AND MID LEVEL RIDGE AXIS SHIFT
OFFSHORE EARLY IN THE PERIOD ALLOWING DEEP RETURN FLOW. PLENTY OF
DEEP MOISTURE IN PLACE WITH 850-500 LAYER RH VALUES GREATER THAN 75%
FOR THE DURATION OF THE PERIOD. ALTHOUGH SIGNIFICANT DYNAMICAL
FEATURES ARE LACKING THE FLOW ALOFT IS DIVERGENT. ADDITIONALLY THERE
ARE LIKELY TO BE WEAK AREAS OF POSITIVE VORTICITY ADVECTION ROTATING
THROUGH SHORTWAVE TROUGH TO THE WEST. TIMING THESE FEATURES 2 AND 3
DAYS OUT IS DIFFICULT AT BEST BUT THESE WOULD CERTAINLY HELP ENHANCE
ANY ONGOING CONVECTION AS THEY MOVE INTO THE AREA. ALTHOUGH
CONVECTIVE PARAMETERS ARE LIMITED LOW LEVEL CONVERGENCE COMBINED
WITH DIURNAL INSTABILITY SHOULD GENERATE SHOWERS. BEST PRECIP
CHANCES APPEAR TO BE EARLY MON AND MON NIGHT WITH ENHANCED
DIVERGENCE ALOFT AND INCREASED DEEP MOISTURE. HIGHS WILL FALL A
LITTLE SHORT OF CLIMO GIVEN INCREASED CLOUD COVER AND RAIN CHANCES.
ABUNDANT MOISTURE WILL KEEP LOWS NEAR TO SLIGHTLY ABOVE CLIMO.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 3 AM SATURDAY...MEDIUM RANGE GUIDANCE CONTINUES TO HAVE
PROBLEMS WITH EVOLUTION OF MID LEVEL PATTERN OVER THE CONUS NEXT
WEEK. HOWEVER SOME NUGGETS OF INFORMATION CAN BE GLEANED FROM THE
CHAOS. EARLY IN THE PERIOD WEAK PATTERN ALOFT AND COASTAL TROUGH
LEAD TO DIURNAL CONVECTION...THOUGH COVERAGE WILL BE LIMITED BY MID
LEVEL DRY AIR. BY THE MIDDLE OF NEXT WEEK THERE WILL BE A SOUTHERN
STREAM SYSTEM CROSSING THE NORTHERN GULF OF MEXICO. AT THE SAME TIME
A SIGNIFICANT COLD FRONT WILL BE DRIVEN ACROSS THE CENTRAL US BY
LONGWAVE MID LEVEL TROUGH. LATE IN THE PERIOD BOTH ECMWF AND GFS
HINT AT SOUTHERN STREAM SHORTWAVE INDUCING A COASTAL LOW OFF THE
SOUTHEAST COAST WHICH IS THEN LIFTED NORTH AHEAD OF THE COLD FRONT.
DESPITE SIMILARITIES BETWEEN THE GFS/ECMWF THERE REMAIN PLENTY OF
MAJOR DIFFERENCES. BOTH MODELS SHOW THE MID LEVEL TROUGH BECOMING
CUTOFF BUT DO SO AT DIFFERENT TIMES AND LOCATIONS. THE GFS IS SLOWER
TO CUTOFF THE 5H TROUGH AND THUS IS FARTHER EAST. GIVEN THE
UNCERTAINTY WILL KEEP POP CAPPED AT CHANCE WITH HIGHEST VALUES
DURING THE DAY. TEMPERATURES WILL BE NEAR TO SLIGHTLY BELOW CLIMO.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 12Z...VFR AT ALL TERMS THIS MORNING WITH INCREASING MID-
LEVEL CLOUDS AHEAD OF A LOW PRESSURE SYSTEM NEAR TX/AR. RAINFALL
FROM THE WESTERN CAROLINAS IS GENERALLY DISSIPATING AS IT NEARS
OUR CWA...SO DO NOT EXPECT ANY NEAR-TERM IMPACTS TO OUR TAF SITES.
CLOUD COVER WILL PERSIST FOR MUCH OF THE PERIOD WITH 10-15KFT CIGS
AND SCT LOWER CLOUDS AS WELL. LIGHT NE WINDS THIS MORNING WILL
BECOME E/SE 10-12 KTS IN THE AFTN. RAIN CHANCES INCREASE LATER THIS
AFTN AS MOIST ISENTROPIC LIFT COULD RESULT IN SOME SHOWER ACTIVITY
INLAND...MOST LIKELY AT KFLO. THE BEST LIFT WILL LIKELY REMAIN TO
THE WEST OF OUR CWA...BUT HAVE INCLUDED VCSH FOR KFLO/KLBT THRU THE
AFTN/EVENING HOURS. CANNOT RULE OUT A STRAY SHOWER AFTER 00Z ALONG
THE COAST...BUT CHOSE NOT TO MENTION PCPN FOR THE COASTAL SITES ATTM.
EXTENDED OUTLOOK...UNSETTLED WEATHER WILL RESULT IN PERIODS OF RAIN
WITH SUB-VFR CONDITIONS POSSIBLE SUNDAY THROUGH WEDNESDAY. BEST RAIN
CHANCES LOOK TO BE ON MONDAY ASSOCIATED WITH A SHORTWAVE TROUGH.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 10115 AM SATURDAY...HIGH PRESSURE WELL TO THE NORTH WILL
CONTINUE TO INFLUENCE THE COASTAL MARINE WATERS. NORTHEAST WINDS
ARE EXPECTED TO VEER TO THE EAST BY THIS AFTERNOON. WINDS SPEEDS
ARE EXPECTED TO INCREASE TO 10 TO 15 KNOTS AND SEAS WILL INCREASE TO
4 FEET.. WITH TO 2 TO 3 FEET NEAR THE BRUNSWICK COUNTY COAST.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...LIGHT EASTERLY FLOW AT THE START OF THE PERIOD
QUICKLY BECOMES SOUTHEAST AS SURFACE RIDGE AXIS SHIFTS EAST OF THE
WATERS. ONLY SUBTLE CHANGES TO THE GRADIENT EXPECTED DURING THE
PERIOD WITH SEA-BREEZE DEVELOPMENT ENHANCING SPEEDS SLIGHTLY. SPEEDS
WILL REMAIN IN THE 10 TO 15 KT RANGE WITH SEAS RUNNING 3 TO 5 FT.
LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 3 AM SATURDAY...SOUTHERLY FLOW CONTINUES THROUGH THE PERIOD
WITH SURFACE HIGH CENTERED NORTHEAST OF THE WATERS BEING THE
DOMINANT FEATURE. GRADIENT REMAINS ON THE WEAK SIDE WITH SPEEDS
STRUGGLING TO REACH 15 KT EVEN WITH THE HELP OF SEABREEZE
ENHANCEMENT. SEAS WILL RUN 3 TO 4 FT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...HAWKINS
SHORT TERM...III
LONG TERM...III
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
743 AM EDT SAT APR 27 2013
.SYNOPSIS...
CLOUDS WILL BE ON THE INCREASE TODAY. PASSING SHOWERS WILL
DEVELOP INLAND LATER THIS AFTERNOON AND OVERNIGHT. SEVERAL
DISTURBANCES MOVING EAST ACROSS THE GULF STATES WILL LEAD TO
INCREASING CLOUDS SUNDAY AND ELEVATED RAIN CHANCES LATE SUNDAY
AND MONDAY. A SLIGHT DRYING TREND IS EXPECTED DURING THE MIDDLE OF
NEXT WEEK WITH AN APPROACHING COLD FRONT LATE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM SATURDAY...THE FIRST WAVE OF RAINFALL ACROSS SOUTH
CAROLINA IS DIMINISHING AS EXPECTED AS IT ENCOUNTERS DEEP DRY AIR
OVER THE EASTERN PIEDMONT AND COASTAL PLAINS. IT APPEARS MEASURABLE
RAINFALL WILL REMAIN SOUTH AND WEST OF KINGSTREE SO I HAVE REMOVED
THE SMALL 20 POP ALONG THE SANTEE RIVER FOR THIS MORNING. 06Z MODELS
HAVE CHANGED LITTLE WITH THEIR DEPICTION OF THIS EVENING`S NEXT WAVE
OF RAIN ACROSS THE PEE DEE REGION SO LITTLE CHANGE HAS BEEN MADE TO
THE FORECAST BEYOND THIS MORNING. PREVIOUS DISCUSSION FROM 300 AM
FOLLOWS...
SURFACE HIGH PRESSURE WILL MOVE OFF THE NEW ENGLAND COASTLINE AND
INTO THE NORTH ATLANTIC THIS AFTERNOON. THIS WILL MAINTAIN A FAIRLY
DRY NORTHEAST TO EAST LOW-LEVEL FLOW INTO THE EASTERN CAROLINAS
THROUGH TONIGHT. SURFACE LOW PRESSURE ALONG THE TX-OK BORDER THIS
MORNING WILL MOVE INTO SOUTHERN ILLINOIS LATE TONIGHT. THIS LOW IS
BEING MAINTAINED BY A SHORTWAVE TROUGH ALMOST CUT OFF FROM THE MAIN
JET STREAM FLOW WELL TO THE NORTH ACROSS THE NORTHERN UNITED STATES.
THICKENING HIGH AND MID LEVEL CLOUDS EARLY THIS MORNING ARE BEING
PRODUCED BY PACIFIC AND NOW GULF MOISTURE BEING ADVECTED OUT AHEAD
OF THE SHORTWAVE DISTURBANCE. DRY LOW LEVELS OF THE ATMOSPHERE PLUS
AND A PERSISTENT MID TO UPPER LEVEL RIDGE ACROSS THE SOUTHERN
APPALACHIANS ARE HELPING ERODE PRECIPITATION THAT IS TRYING TO
STREAM EAST-SOUTHEAST FROM KENTUCKY AND TENNESSEE. RADAR COMPOSITES
SHOW A NARROW BUT IMPRESSIVE AREA OF MODERATE TO HEAVY RAINFALL
ACROSS NORTHERN GEORGIA THAT LOOKS TO BE MOVING IN THE GENERAL
DIRECTION OF THE SANTEE RIVER BASIN. IF ANY OF THIS PRECIPITATION
SURVIVES OUR DRY AIR...IT WOULD REACH WILLIAMSBURG AND GEORGETOWN
COUNTIES BETWEEN 6-9 AM. THE 04Z HRRR APPEARS TO HAVE A GOOD HANDLE
ON THIS PRECIPITATION AND SHOWS ONLY A COUPLE HUNDREDTHS OF AN INCH
SCATTERED ALONG THE SANTEE RIVER LATER THIS MORNING.
PARTLY TO MOSTLY CLOUDY SKIES WILL CONTINUE THROUGH THE MORNING AND
AFTERNOON HOURS. HIGH SUN ANGLES (SAME AS IN MID AUGUST) WILL CUT
THROUGH THE CLOUDS AND PUSH TEMPERATURES INTO THE LOWER TO MID 70S
AWAY FROM THE BEACHES.
AN INTERESTING SITUATION WILL DEVELOP ACROSS CENTRAL SOUTH CAROLINA
LATE THIS AFTERNOON AS THE GFS AND ECMWF SHOW A NARROW ZONE OF
RATHER IMPRESSIVE ISENTROPIC LIFT DEVELOPING ALONG THE 305-310K
THETA SURFACES...APPROXIMATELY 12000-16000 FT AGL. THIS IS MUCH
HIGHER UP THAN WHERE I TYPICALLY ANALYZE ISENTROPIC LIFT BUT APPEARS
TO BE WHAT THE MODELS ARE LATCHING ONTO FOR THE DEVELOPMENT OF RAIN
THAT MAY AFFECT THE SC PEE DEE REGION JUST BEFORE SUNSET. I HAVE
INCREASED POPS TO 30-40 PERCENT MAINLY BETWEEN 5-9 PM...WITH MODELS
INDICATING THAT AGAIN THE RAIN WILL DRY UP AS IT TRIES TO MOVE EAST
TOWARD THE COAST. PERHAPS EVEN MORE INTERESTING IS THE POTENTIAL FOR
SMALL ELEVATED INSTABILITY ORIGINATING FROM VERY HIGH ALOFT...
500-550 MB. IT IS QUITE RARE FOR CONVECTION TO DEVELOP FROM SUCH A
HIGH BASE IN THIS PART OF THE COUNTRY...BUT THIS COULD ADD A LITTLE
CONVECTIVE CHARACTER TO WHAT MAY BE AN OTHERWISE STRATIFORM RAIN
EVENT. EVEN THE MOST AGGRESSIVE MODEL SHOWS CAPE LESS THAN 100 J/KG
SO WE`RE NOT TALKING ABOUT SEVERE WEATHER BY ANY STRETCH.
PRECIPITATION SHOULD DIMINISH IN COVERAGE DURING THE LATE EVENING
HOURS...BUT WITH PLENTY OF CLOUDS REMAINING OVERNIGHT. LOWS SHOULD
FALL TO 50-55...WARMEST ALONG THE SC COAST WITH THE ONSHORE WIND AND
ALSO BACK UNDER THE CLOUDS ACROSS THE PEE DEE REGION.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...SURFACE AND MID LEVEL RIDGE AXIS SHIFT
OFFSHORE EARLY IN THE PERIOD ALLOWING DEEP RETURN FLOW. PLENTY OF
DEEP MOISTURE IN PLACE WITH 850-500 LAYER RH VALUES GREATER THAN 75%
FOR THE DURATION OF THE PERIOD. ALTHOUGH SIGNIFICANT DYNAMICAL
FEATURES ARE LACKING THE FLOW ALOFT IS DIVERGENT. ADDITIONALLY THERE
ARE LIKELY TO BE WEAK AREAS OF POSITIVE VORTICITY ADVECTION ROTATING
THROUGH SHORTWAVE TROUGH TO THE WEST. TIMING THESE FEATURES 2 AND 3
DAYS OUT IS DIFFICULT AT BEST BUT THESE WOULD CERTAINLY HELP ENHANCE
ANY ONGOING CONVECTION AS THEY MOVE INTO THE AREA. ALTHOUGH
CONVECTIVE PARAMETERS ARE LIMITED LOW LEVEL CONVERGENCE COMBINED
WITH DIURNAL INSTABILITY SHOULD GENERATE SHOWERS. BEST PRECIP
CHANCES APPEAR TO BE EARLY MON AND MON NIGHT WITH ENHANCED
DIVERGENCE ALOFT AND INCREASED DEEP MOISTURE. HIGHS WILL FALL A
LITTLE SHORT OF CLIMO GIVEN INCREASED CLOUD COVER AND RAIN CHANCES.
ABUNDANT MOISTURE WILL KEEP LOWS NEAR TO SLIGHTLY ABOVE CLIMO.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 3 AM SATURDAY...MEDIUM RANGE GUIDANCE CONTINUES TO HAVE
PROBLEMS WITH EVOLUTION OF MID LEVEL PATTERN OVER THE CONUS NEXT
WEEK. HOWEVER SOME NUGGETS OF INFORMATION CAN BE GLEANED FROM THE
CHAOS. EARLY IN THE PERIOD WEAK PATTERN ALOFT AND COASTAL TROUGH
LEAD TO DIURNAL CONVECTION...THOUGH COVERAGE WILL BE LIMITED BY MID
LEVEL DRY AIR. BY THE MIDDLE OF NEXT WEEK THERE WILL BE A SOUTHERN
STREAM SYSTEM CROSSING THE NORTHERN GULF OF MEXICO. AT THE SAME TIME
A SIGNIFICANT COLD FRONT WILL BE DRIVEN ACROSS THE CENTRAL US BY
LONGWAVE MID LEVEL TROUGH. LATE IN THE PERIOD BOTH ECMWF AND GFS
HINT AT SOUTHERN STREAM SHORTWAVE INDUCING A COASTAL LOW OFF THE
SOUTHEAST COAST WHICH IS THEN LIFTED NORTH AHEAD OF THE COLD FRONT.
DESPITE SIMILARITIES BETWEEN THE GFS/ECMWF THERE REMAIN PLENTY OF
MAJOR DIFFERENCES. BOTH MODELS SHOW THE MID LEVEL TROUGH BECOMING
CUTOFF BUT DO SO AT DIFFERENT TIMES AND LOCATIONS. THE GFS IS SLOWER
TO CUTOFF THE 5H TROUGH AND THUS IS FARTHER EAST. GIVEN THE
UNCERTAINTY WILL KEEP POP CAPPED AT CHANCE WITH HIGHEST VALUES
DURING THE DAY. TEMPERATURES WILL BE NEAR TO SLIGHTLY BELOW CLIMO.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 12Z...VFR AT ALL TERMS THIS MORNING WITH INCREASING MID-LEVEL
CLOUDS AHEAD OF A LOW PRESSURE SYSTEM NEAR TX/AR. RAINFALL FROM
THE WESTERN CAROLINAS IS GENERALLY DISSIPATING AS IT NEARS OUR
CWA...SO DO NOT EXPECT ANY NEAR-TERM IMPACTS TO OUR TAF SITES.
CLOUD COVER WILL PERSIST FOR MUCH OF THE PERIOD WITH 10-15KFT CIGS
AND SCT LOWER CLOUDS AS WELL. LIGHT NE WINDS THIS MORNING WILL
BECOME E/SE 10-12 KTS IN THE AFTN. RAIN CHANCES INCREASE LATER THIS
AFTN AS MOIST ISENTROPIC LIFT COULD RESULT IN SOME SHOWER ACTIVITY
INLAND...MOST LIKELY AT KFLO. THE BEST LIFT WILL LIKELY REMAIN TO
THE WEST OF OUR CWA...BUT HAVE INCLUDED VCSH FOR KFLO/KLBT THRU THE
AFTN/EVENING HOURS. CANNOT RULE OUT A STRAY SHOWER AFTER 00Z ALONG
THE COAST...BUT CHOSE NOT TO MENTION PCPN FOR THE COASTAL SITES ATTM.
EXTENDED OUTLOOK...UNSETTLED WEATHER WILL RESULT IN PERIODS OF RAIN
WITH SUB-VFR CONDITIONS POSSIBLE SUNDAY THROUGH WEDNESDAY. BEST RAIN
CHANCES LOOK TO BE ON MONDAY ASSOCIATED WITH A SHORTWAVE TROUGH.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM SATURDAY...6 AM OBSERVATIONS OF WIND AND SEAS WERE
RIGHT ON THE MONEY...SO NO CHANGES HAVE BEEN MADE FROM THE PREVIOUS
FORECAST. DISCUSSION FROM 300 AM FOLLOWS...
STRONG HIGH PRESSURE OVER NEW ENGLAND WILL MOVE EAST AND INTO THE
NORTH ATLANTIC LATER TODAY. THE HIGH WILL CONTINUE TO RIDGE
SOUTHWARD TOWARD THE CAROLINAS WITH NORTHEAST TO EAST WIND
CONTINUING. WIND SPEEDS SHOULD REMAIN A VERY CONSISTENT 10-15 KNOTS
THROUGH TONIGHT...WHICH GIVEN THE LONG FETCH ORIGINATING FROM
NEWFOUNDLAND IS ENOUGH TO MAINTAIN A NEARLY STEADY SEA STATE OF 3-4
FT NORTH OF CAPE FEAR AND EAST OF GEORGETOWN...WITH 2-4 FT SEAS
ELSEWHERE.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...LIGHT EASTERLY FLOW AT THE START OF THE PERIOD
QUICKLY BECOMES SOUTHEAST AS SURFACE RIDGE AXIS SHIFTS EAST OF THE
WATERS. ONLY SUBTLE CHANGES TO THE GRADIENT EXPECTED DURING THE
PERIOD WITH SEABREEZE DEVELOPMENT ENHANCING SPEEDS SLIGHTLY. SPEEDS
WILL REMAIN IN THE 10 TO 15 KT RANGE WITH SEAS RUNNING 3 TO 5 FT.
LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 3 AM SATURDAY...SOUTHERLY FLOW CONTINUES THROUGH THE PERIOD
WITH SURFACE HIGH CENTERED NORTHEAST OF THE WATERS BEING THE
DOMINANT FEATURE. GRADIENT REMAINS ON THE WEAK SIDE WITH SPEEDS
STRUGGLING TO REACH 15 KT EVEN WITH THE HELP OF SEABREEZE
ENHANCEMENT. SEAS WILL RUN 3 TO 4 FT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA
SHORT TERM...III
LONG TERM...III
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
642 AM EDT SAT APR 27 2013
.SYNOPSIS...
CLOUDS WILL BE ON THE INCREASE TODAY. PASSING SHOWERS WILL
DEVELOP INLAND LATER THIS AFTERNOON AND OVERNIGHT. SEVERAL
DISTURBANCES MOVING EAST ACROSS THE GULF STATES WILL LEAD TO
INCREASING CLOUDS SUNDAY AND ELEVATED RAIN CHANCES LATE SUNDAY
AND MONDAY. A SLIGHT DRYING TREND IS EXPECTED DURING THE MIDDLE OF
NEXT WEEK WITH AN APPROACHING COLD FRONT LATE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM SATURDAY...THE FIRST WAVE OF RAINFALL ACROSS SOUTH
CAROLINA IS DIMINISHING AS EXPECTED AS IT ENCOUNTERS DEEP DRY AIR
OVER THE EASTERN PIEDMONT AND COASTAL PLAINS. IT APPEARS MEASURABLE
RAINFALL WILL REMAIN SOUTH AND WEST OF KINGSTREE SO I HAVE REMOVED
THE SMALL 20 POP ALONG THE SANTEE RIVER FOR THIS MORNING. 06Z MODELS
HAVE CHANGED LITTLE WITH THEIR DEPICTION OF THIS EVENING`S NEXT WAVE
OF RAIN ACROSS THE PEE DEE REGION SO LITTLE CHANGE HAS BEEN MADE TO
THE FORECAST BEYOND THIS MORNING. PREVIOUS DISCUSSION FROM 300 AM
FOLLOWS...
SURFACE HIGH PRESSURE WILL MOVE OFF THE NEW ENGLAND COASTLINE AND
INTO THE NORTH ATLANTIC THIS AFTERNOON. THIS WILL MAINTAIN A FAIRLY
DRY NORTHEAST TO EAST LOW-LEVEL FLOW INTO THE EASTERN CAROLINAS
THROUGH TONIGHT. SURFACE LOW PRESSURE ALONG THE TX-OK BORDER THIS
MORNING WILL MOVE INTO SOUTHERN ILLINOIS LATE TONIGHT. THIS LOW IS
BEING MAINTAINED BY A SHORTWAVE TROUGH ALMOST CUT OFF FROM THE MAIN
JET STREAM FLOW WELL TO THE NORTH ACROSS THE NORTHERN UNITED STATES.
THICKENING HIGH AND MID LEVEL CLOUDS EARLY THIS MORNING ARE BEING
PRODUCED BY PACIFIC AND NOW GULF MOISTURE BEING ADVECTED OUT AHEAD
OF THE SHORTWAVE DISTURBANCE. DRY LOW LEVELS OF THE ATMOSPHERE PLUS
AND A PERSISTENT MID TO UPPER LEVEL RIDGE ACROSS THE SOUTHERN
APPALACHIANS ARE HELPING ERODE PRECIPITATION THAT IS TRYING TO
STREAM EAST-SOUTHEAST FROM KENTUCKY AND TENNESSEE. RADAR COMPOSITES
SHOW A NARROW BUT IMPRESSIVE AREA OF MODERATE TO HEAVY RAINFALL
ACROSS NORTHERN GEORGIA THAT LOOKS TO BE MOVING IN THE GENERAL
DIRECTION OF THE SANTEE RIVER BASIN. IF ANY OF THIS PRECIPITATION
SURVIVES OUR DRY AIR...IT WOULD REACH WILLIAMSBURG AND GEORGETOWN
COUNTIES BETWEEN 6-9 AM. THE 04Z HRRR APPEARS TO HAVE A GOOD HANDLE
ON THIS PRECIPITATION AND SHOWS ONLY A COUPLE HUNDREDTHS OF AN INCH
SCATTERED ALONG THE SANTEE RIVER LATER THIS MORNING.
PARTLY TO MOSTLY CLOUDY SKIES WILL CONTINUE THROUGH THE MORNING AND
AFTERNOON HOURS. HIGH SUN ANGLES (SAME AS IN MID AUGUST) WILL CUT
THROUGH THE CLOUDS AND PUSH TEMPERATURES INTO THE LOWER TO MID 70S
AWAY FROM THE BEACHES.
AN INTERESTING SITUATION WILL DEVELOP ACROSS CENTRAL SOUTH CAROLINA
LATE THIS AFTERNOON AS THE GFS AND ECMWF SHOW A NARROW ZONE OF
RATHER IMPRESSIVE ISENTROPIC LIFT DEVELOPING ALONG THE 305-310K
THETA SURFACES...APPROXIMATELY 12000-16000 FT AGL. THIS IS MUCH
HIGHER UP THAN WHERE I TYPICALLY ANALYZE ISENTROPIC LIFT BUT APPEARS
TO BE WHAT THE MODELS ARE LATCHING ONTO FOR THE DEVELOPMENT OF RAIN
THAT MAY AFFECT THE SC PEE DEE REGION JUST BEFORE SUNSET. I HAVE
INCREASED POPS TO 30-40 PERCENT MAINLY BETWEEN 5-9 PM...WITH MODELS
INDICATING THAT AGAIN THE RAIN WILL DRY UP AS IT TRIES TO MOVE EAST
TOWARD THE COAST. PERHAPS EVEN MORE INTERESTING IS THE POTENTIAL FOR
SMALL ELEVATED INSTABILITY ORIGINATING FROM VERY HIGH ALOFT...
500-550 MB. IT IS QUITE RARE FOR CONVECTION TO DEVELOP FROM SUCH A
HIGH BASE IN THIS PART OF THE COUNTRY...BUT THIS COULD ADD A LITTLE
CONVECTIVE CHARACTER TO WHAT MAY BE AN OTHERWISE STRATIFORM RAIN
EVENT. EVEN THE MOST AGGRESSIVE MODEL SHOWS CAPE LESS THAN 100 J/KG
SO WE`RE NOT TALKING ABOUT SEVERE WEATHER BY ANY STRETCH.
PRECIPITATION SHOULD DIMINISH IN COVERAGE DURING THE LATE EVENING
HOURS...BUT WITH PLENTY OF CLOUDS REMAINING OVERNIGHT. LOWS SHOULD
FALL TO 50-55...WARMEST ALONG THE SC COAST WITH THE ONSHORE WIND AND
ALSO BACK UNDER THE CLOUDS ACROSS THE PEE DEE REGION.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...SURFACE AND MID LEVEL RIDGE AXIS SHIFT
OFFSHORE EARLY IN THE PERIOD ALLOWING DEEP RETURN FLOW. PLENTY OF
DEEP MOISTURE IN PLACE WITH 850-500 LAYER RH VALUES GREATER THAN 75%
FOR THE DURATION OF THE PERIOD. ALTHOUGH SIGNIFICANT DYNAMICAL
FEATURES ARE LACKING THE FLOW ALOFT IS DIVERGENT. ADDITIONALLY THERE
ARE LIKELY TO BE WEAK AREAS OF POSITIVE VORTICITY ADVECTION ROTATING
THROUGH SHORTWAVE TROUGH TO THE WEST. TIMING THESE FEATURES 2 AND 3
DAYS OUT IS DIFFICULT AT BEST BUT THESE WOULD CERTAINLY HELP ENHANCE
ANY ONGOING CONVECTION AS THEY MOVE INTO THE AREA. ALTHOUGH
CONVECTIVE PARAMETERS ARE LIMITED LOW LEVEL CONVERGENCE COMBINED
WITH DIURNAL INSTABILITY SHOULD GENERATE SHOWERS. BEST PRECIP
CHANCES APPEAR TO BE EARLY MON AND MON NIGHT WITH ENHANCED
DIVERGENCE ALOFT AND INCREASED DEEP MOISTURE. HIGHS WILL FALL A
LITTLE SHORT OF CLIMO GIVEN INCREASED CLOUD COVER AND RAIN CHANCES.
ABUNDANT MOISTURE WILL KEEP LOWS NEAR TO SLIGHTLY ABOVE CLIMO.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 3 AM SATURDAY...MEDIUM RANGE GUIDANCE CONTINUES TO HAVE
PROBLEMS WITH EVOLUTION OF MID LEVEL PATTERN OVER THE CONUS NEXT
WEEK. HOWEVER SOME NUGGETS OF INFORMATION CAN BE GLEANED FROM THE
CHAOS. EARLY IN THE PERIOD WEAK PATTERN ALOFT AND COASTAL TROUGH
LEAD TO DIURNAL CONVECTION...THOUGH COVERAGE WILL BE LIMITED BY MID
LEVEL DRY AIR. BY THE MIDDLE OF NEXT WEEK THERE WILL BE A SOUTHERN
STREAM SYSTEM CROSSING THE NORTHERN GULF OF MEXICO. AT THE SAME TIME
A SIGNIFICANT COLD FRONT WILL BE DRIVEN ACROSS THE CENTRAL US BY
LONGWAVE MID LEVEL TROUGH. LATE IN THE PERIOD BOTH ECMWF AND GFS
HINT AT SOUTHERN STREAM SHORTWAVE INDUCING A COASTAL LOW OFF THE
SOUTHEAST COAST WHICH IS THEN LIFTED NORTH AHEAD OF THE COLD FRONT.
DESPITE SIMILARITIES BETWEEN THE GFS/ECMWF THERE REMAIN PLENTY OF
MAJOR DIFFERENCES. BOTH MODELS SHOW THE MID LEVEL TROUGH BECOMING
CUTOFF BUT DO SO AT DIFFERENT TIMES AND LOCATIONS. THE GFS IS SLOWER
TO CUTOFF THE 5H TROUGH AND THUS IS FARTHER EAST. GIVEN THE
UNCERTAINTY WILL KEEP POP CAPPED AT CHANCE WITH HIGHEST VALUES
DURING THE DAY. TEMPERATURES WILL BE NEAR TO SLIGHTLY BELOW CLIMO.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 06Z...VFR THROUGH THE PERIOD. INCREASING RAIN CHANCES TONIGHT.
HIGH AND MID CLOUDS WILL CONTINUE TO THICKEN ACROSS THE AREA. LATEST
HIGH-RES MODELS INDICATE MODERATE TO HEAVY RAIN ACROSS S TN AND N GA
MAY MAKE A RUN TOWARD THE FLORENCE AIRPORT 10-13Z. I WILL MONITOR
CLOSELY TO SEE IF RAIN NEEDS TO BE ADDED TO OUR TAF FORECAST.
OTHERWISE RAIN CHANCES INCREASE FOR THE INLAND TERMINALS TOWARDS THE
EVENING HOURS...AND THEN FOR THE COASTAL TERMINALS INTO THE
OVERNIGHT HOURS.
EXTENDED OUTLOOK...UNSETTLED WEATHER SATURDAY NIGHT THROUGH TUESDAY
AS AN OVERRUNNING SCENARIO GIVES US MOSTLY CLOUDY CONDITIONS THROUGH
WEDNESDAY WITH PERIODS OF RAIN AND IFR CONDITIONS.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM SATURDAY...6 AM OBSERVATIONS OF WIND AND SEAS WERE
RIGHT ON THE MONEY...SO NO CHANGES HAVE BEEN MADE FROM THE PREVIOUS
FORECAST. DISCUSSION FROM 300 AM FOLLOWS...
STRONG HIGH PRESSURE OVER NEW ENGLAND WILL MOVE EAST AND INTO THE
NORTH ATLANTIC LATER TODAY. THE HIGH WILL CONTINUE TO RIDGE
SOUTHWARD TOWARD THE CAROLINAS WITH NORTHEAST TO EAST WIND
CONTINUING. WIND SPEEDS SHOULD REMAIN A VERY CONSISTENT 10-15 KNOTS
THROUGH TONIGHT...WHICH GIVEN THE LONG FETCH ORIGINATING FROM
NEWFOUNDLAND IS ENOUGH TO MAINTAIN A NEARLY STEADY SEA STATE OF 3-4
FT NORTH OF CAPE FEAR AND EAST OF GEORGETOWN...WITH 2-4 FT SEAS
ELSEWHERE.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...LIGHT EASTERLY FLOW AT THE START OF THE PERIOD
QUICKLY BECOMES SOUTHEAST AS SURFACE RIDGE AXIS SHIFTS EAST OF THE
WATERS. ONLY SUBTLE CHANGES TO THE GRADIENT EXPECTED DURING THE
PERIOD WITH SEABREEZE DEVELOPMENT ENHANCING SPEEDS SLIGHTLY. SPEEDS
WILL REMAIN IN THE 10 TO 15 KT RANGE WITH SEAS RUNNING 3 TO 5 FT.
LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 3 AM SATURDAY...SOUTHERLY FLOW CONTINUES THROUGH THE PERIOD
WITH SURFACE HIGH CENTERED NORTHEAST OF THE WATERS BEING THE
DOMINANT FEATURE. GRADIENT REMAINS ON THE WEAK SIDE WITH SPEEDS
STRUGGLING TO REACH 15 KT EVEN WITH THE HELP OF SEABREEZE
ENHANCEMENT. SEAS WILL RUN 3 TO 4 FT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA
SHORT TERM...III
LONG TERM...III
AVIATION...SGL/TRA
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1122 AM EDT SAT APR 27 2013
.SYNOPSIS...
AN INCREASINGLY MOIST WEDGE OF COOLER AIR WILL OVERSPREAD THE REGION
THIS WEEKEND AS WEAK LOW PRESSURE MOVES ACROSS THE TENNESSEE VALLEY
ALONG A STALLED COLD FRONT. THE FRONT WILL SLOWLY DISSIPATE AND THE
COOL AIR WEDGE WILL GRADUALLY WEAKEN INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1115 AM...LATEST RADAR TRENDS HAVE INDICATED AN INCREASING
TREND IN RAINFALL RATES ACROSS THE SOUTHERN NC MTNS SE ACROSS THE
SAVANNAH RIVER VALLEY. I WILL INCREASE POPS OVER THE AREA THROUGH
MID DAY. THE REST OF THE CWA HAS MAINLY EXPERIENCED SPRINKLES TO
LIGHT RAIN SHOWERS. THIS TREND MAY CONTINUE OVER THE NEXT COUPLE OF
HOURS. HOWEVER...NEAR TERM MODELS REMAIN IN AGREEMENT WITH SPREADING
COVERAGE EAST ACROSS THE MTNS THIS AFTERNOON WITH THE APPROACH AND
PASSAGE OF A MID LEVEL S/W. I WILL TIME CATE POPS ACROSS THE MTNS
AND ADJACENT FOOTHILLS THIS AFTERNOON. I WILL ALSO COOL TEMPS ACROSS
THE MTNS A COUPLE OF CLICKS...PIEDMONT AREAS APPEARS ON TRACK.
I HAVE ALSO UPDATED THE FORECAST THROUGH SUNDAY. THE MAIN CHANGES
INCLUDE INCREASING POPS AND INDICATING HIGHER QPF OVER UPSLOPE AREAS.
630 AM UPDATE...500MB VORT MAX NOW PASSING THROUGH THE AREA AND
SPARKING A FEW ADDITIONAL SHOWERS OVER THE NW NC PIEDMONT...WHILE
MOST OF THE ACTIVITY REMAINS OVER SW HALF OF CWFA. MADE SOME MORE
ADJUSTMENTS TO POPS INCLUDING SLIGHT EASTWARD EXPANSION TO ACCOUNT
FOR THE PIEDMONT SHOWERS...WHICH LOOK VERY LIGHT ON RADAR AND ARE
NOT LIKELY TO PRODUCE SIGNIFICANT ACCUMS OVER THE NEXT HOUR OR SO.
430 AM UPDATE...ADJUSTED POPS THROUGH DAYBREAK. 06Z NAM DOES NOT
SEEM TO HAVE A GREAT HANDLE ON THE ONGOING PRECIP AROUND THE
REGION...NOT SHOWING ANY ACCUMS FROM THE ACTIVITY IN THE SAVANNAH
RIVER VALLEY. IT DOES CONTINUE TO SUPPORT THE INCREASING POPS NEAR
THE TENN BORDER AFTER SUNRISE. 06Z HRRR SHOWS SOME OF THE CURRENT
ACTIVITY MOVING EAST THEN BRINGS A COUPLE OF WAVES OF SHOWERS ACROSS
BY LATE MORNING. MADE ADJUSTMENTS TO PREVIOUS TREND MOSTLY BASED ON
RADAR MAINLY INTERPRETING THE NEW GUIDANCE AS A CONFIDENCE BOOST.
AS OF EARLY SAT MORNING...SFC HIGH OVER NE CONUS SEEN ON CURRENT SFC
ANALYSIS SITS IN A FAVORABLE POSITION TO ALLOW DEVELOPMENT OF CAD
ACROSS OUR REGION DURING THE NEAR TERM PERIOD. LLVL WINDS ABOVE THE
BOUNDARY LAYER ARE ALREADY SOUTHERLY. THROUGH THE DAY TODAY MIDLEVEL
RIDGE SHIFTS SLIGHTLY EASTWARD AS CLOSED UPPER LOW GROWS OVER THE MID
MISSISSIPPI VALLEY. THE EFFECT WILL BE TO STRENGTHEN THE FLOW OVER
THE CAD WEDGE LEADING TO A SOMEWHAT STEADY INCREASE IN ISENTROPIC
LIFT AND DEEP MOISTURE ADVECTION. MEANWHILE...EXTRA SUPPORT FOR
PRECIP DEVELOPMENT WILL COME FROM VORT MAXES ROUNDING THE SUBTLE
UPPER RIDGE AHEAD OF THE CLOSED LOW. ONE AREA OF PVA IS EXPECTED TO
SPREAD ITS ASSOCIATED PRECIP INTO THE MTNS AROUND DAYBREAK WHILE A
SECOND...SHOWN ON BOTH GFS AND NAM...WILL MOVE THROUGH THIS
AFTERNOON. THAT FEATURE IS CONCURRENT WITH RIGHT REAR QUAD OF 250MB
JET STREAK AND ASSOCIATED DIVERGENCE. UPPER SUPPORT WANES SOMEWHAT ON
GFS THIS EVENING...BUT NAM FEATURES MCV/S MOVING IN AT THAT TIME.
THESE ARE PROBABLY RESULTING FROM CONVECTION UPSTREAM...SO NOT
NECESSARILY BITING ON ANY MODELED EFFECTS FROM THOSE. MIDLEVEL
Q-VECTOR CONVERGENCE DOES CONTINUE TO INCREASE AS HEIGHTS FALL OVER
THE TENN VALLEY AHEAD OF THE UPPER LOW AND AS THE WARM ADVECTION
RAMPS UP.
HAVE NOT MADE MUCH CHANGE TO POP TRENDS WHICH GENERALLY SPREAD WEST
TO EAST DURING THE PERIOD...WITH CATEGORICAL VALUES APPROPRIATE OVER
THE NW HALF OF CWA /WHERE UPSLOPING WILL PLAY THE BIGGEST ROLE AND
ALSO FEATURING THE BEST UPPER SUPPORT/. QPF COULD BE CRITICAL FOR
THIS EVENT AS A WHOLE SO GAVE IT SOME EXTRA THOUGHT. GFS IS THE MOST
ROBUST WITH THE ACTIVITY THIS AFTERNOON WHICH MAKES SENSE GIVEN ITS
EVOLUTION OF THE UPPER FORCING...AND FEATURES LOWER QPF FOR EVENING
BUT WITH SOME INCREASE AGAIN TOWARD SUN MORNING AS THE MOISTURE
DEEPENS. GENERALLY THE DETERMINISTIC TOTALS ARE BACKED UP BY THE
ACCUM PROBABILITIES PRODUCED BY THE ENSEMBLE RUN. CHOSE TO USE A
BLEND OF AVAILABLE DETERMINISTIC GUIDANCE BUT WITH A BIAS TOWARD THE
GFS.
TEMPS TODAY WILL BE BELOW NORMAL GIVEN THE CLOUD COVER AND DEVELOPING
WEDGE...BUT IF PRECIP IS DELAYED OR DOES NOT DEVELOP OVER A
WIDESPREAD AREA TEMPS COULD BE SOMEWHAT WARMER WITHOUT THE RAINFALL
TO LOCK IN THE WEDGE EARLY. WENT WITH RAW MODEL BLEND FOR TONIGHT
ASSUMING THE WEDGE WILL BE FULLY ENTRENCHED BY THEN.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 240 AM SATURDAY...AS THE UPPER RIDGE AXIS SHIFTS TO THE
COAST...AND DEEP/VERY MOIST SW FLOW BECOMES ESTABLISHED OVER THE
AREA...POPS WILL CONTINUE TO INCREASE THROUGH SUNDAY WITHIN MODESTLY
STRONG WAA/SOUTHERLY UPSLOPE REGIME. WITH THE CENTER OF THE SURFACE
HIGH EXPECTED TO SHIFT OFF THE NEW ENGLAND COAST BY SUNDAY...IN SITU
COLD AIR DAMMING WILL LIKELY BEGIN TO ERODE AROUND THE PERIPHERY OF
THE FORECAST AREA...ESP THE SOUTHERN PIEDMONT AND FAR SOUTHWEST MTN
ZONES. THIS WILL CREATE THE POTENTIAL FOR INCREASED INSTABILITY/
DEEPER CONVECTION/INCREASED RAINFALL RATES BY AFTERNOON. IN FACT...
SUNDAY AFTERNOON THROUGH SUNDAY NIGHT APPEARS TO BE THE MOST LIKELY
PERIOD OF HEAVY RAINFALL IN LIGHT OF THIS TIME OFFERING THE BEST
JUXTAPOSITION OF UPSLOPE FLOW...INSTABILITY/ MOISTURE...AS WELL AS
INCREASING UPPER LEVEL FORCING. THE LATTER COMES ABOUT AS A RESULT
OF A COUPLED JET STRUCTURE THAT MAXIMIZES SUNDAY EVENING. AREAS
ALONG THE SOUTHERN BLUE RIDGE COULD WELL SEE WIDESPREAD RAINFALL
AMOUNTS OF TWO INCHES WITHIN THIS WINDOW OF TIME ALONE. STORM TOTAL
AMOUNTS OF 2.5 TO 4 INCHES APPEAR TO BE A VERY GOOD BET THROUGH
SUNDAY NIGHT...AND CONFIDENCE IS INCREASING THAT WE MAY HAVE LOCALLY
EXCESSIVE RAINFALL CONCERNS ALONG OUR SOUTHERN BLUE RIDGE COUNTIES.
NEVERTHELESS...I STILL THINK WE ARE AROUND 48 HOURS AWAY FROM SEEING
ANY HYDRO CONCERNS...AND I WOULD LIKE TO SEE HOW TODAY/S RAINFALL
SITUATION UNFOLDS BEFORE HOISTING A WATCH...SO HAVE OPTED TO PUNT TO
THE DAY SHIFT.
BY MONDAY...THE BEST UPPER FORCING AND DEEP MOISTURE WILL SHUNT EAST
OF THE AREA. HOWEVER...SOUTHERLY FLOW WILL PERSIST IN THE LOWER
LEVELS...SUPPORTING AMPLE LOW LEVEL MOISTURE. IN FACT...WITH THE AIR
MASS DRYING SOMEWHAT ALOFT...WE MAY SEE MORE SUN/INSTABILITY MONDAY
AFTERNOON. WITH THE UPPER TROUGH/SHEAR AXIS LINGERING OVER THE
AREA...SOLID CHANCE/LOW LIKELY POPS ARE WARRANTED INTO THE
AFTERNOON. CONVECTION SHOULD BECOME MORE DIURNAL IN NATURE BY THE
END OF THE SHORT TERM PERIOD...SO POPS GRADUALLY TAPER DOWN MONDAY
EVENING.
MAX TEMPERATURES WILL REMAIN BELOW NORMAL SUNDAY UNDER WIDESPREAD
CLOUD COVER AND PRECIPITATION...BUT RETURN TO NEAR CLIMO BY MONDAY.
LOWS WILL BE AT LEAST A CATEGORY ABOVE CLIMO THROUGH THE PERIOD.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 305 AM SATURDAY...THE MEDIUM RANGE CONTINUES TO APPEAR
UNSETTLED...AS PERSISTENT SOUTH TO SE FLOW MAINTAINS A FETCH OF LOW
LEVEL MOISTURE INTO THE REGION...SUPPORTING MAINLY DIURNAL CHANCES
FOR SHOWERS AND THUNDERSTORMS. THE GLOBAL MODELS CONTINUE TO
ADVERTISE A REASSERTION OF THE EASTERN LOW LEVEL RIDGE AXIS DURING
MID-LATE WEEK. HOWEVER...THEY ARE NOT AS AGGRESSIVE IN DRYING OUT
THE LOWER LEVEL AIR MASS OVER THE CAROLINAS. THERE IS ALSO
CONSIDERABLE UNCERTAINTY REGARDING THE TIMING OF THE NEXT MAJOR
STORM SYSTEM...AS THE PRIMARY GLOBAL MODELS ARE VERY MUCH AT ODDS IN
THEIR HANDLING OF WESTERN CONUS ENERGY LATE IN THE WEEK.
THEREFORE...SLIGHT/CHANCE POPS AND NEAR-CLIMO TEMPS WILL REMAIN IN
THE FORECAST THROUGH THE EXTENDED RANGE PERIOD.
&&
.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...THE FIELD SHOULD MAINTAIN A SOUTHERLY WIND THROUGH MIDDAY.
WITH HIGH PRESSURE OVER THE MID ATLANTIC COAST HELPING TO DEVELOP
COLD AIR DAMMING AND COOL SFC WEDGE. WARM MOIST FLOW ALOFT OVER THE
WEDGE IS FAIRLY CONSTANT THROUGH THE PERIOD. BETTER UPPER FORCING
AND DEEPENING MOISTURE WILL LEAD TO INCREASING PRECIP CHANCES AND
LOWERING CIGS BY AFTERNOON. BASED ON LATEST GUIDANCE CONSENSUS AND
UPSTREAM ACTIVITY THE SHOWERS ARE NOT EXPECTED TO RESTRICT VSBY.
CIGS SHOULD BE ABLE TO FURTHER DROP TO MVFR BY 06Z...WITH SOME
INDICATION THAT IFR IS POSSIBLE CLOSER TO SUNRISE SUNDAY. WINDS MAY
BE SOMEWHAT VARIABLE THIS AFTERNOON WITH UPPER DISTURBANCE OVERHEAD.
THEY SHOULD TURN BACK TO THE SOUTHEAST AS THE PRECIP AND WEDGE
DEVELOP TONIGHT.
ELSEWHERE...SHOWERS WILL CONTINUE TO DEVELOP THRU THE TAF
PERIOD...WITH RESTRICTIONS BECOMING INCREASINGLY LIKELY...AS WARM
AIR AND MOISTURE ADVECT OVER A WEDGE OF COLD AIR AT THE SURFACE.
SITUATION IS COMPLICATED BY ACTIVE UPPER ATMOSPHERE WHICH WILL
PROVIDE ADDITIONAL LIFT AND ENHANCE PRECIP/CLOUD PRODUCTION AT
TIMES. DO THINK RESTRICTIONS WILL NOT BE SEEN UNTIL AFTERNOON WITH
MOST OF THE UPSTREAM ACTIVITY MAINTAINING LOW VFR EVEN IN SHOWERS.
AS BETTER UPPER SUPPORT MOVES IN TODAY MVFR SHOULD SETTLE IN ACROSS
THE WESTERN PORTIONS OF THE AREA. MVFR CIGS AT KAVL BY
AFTERNOON...AND ELSEWHERE OVERNIGHT. CONDITIONS WILL GENERALLY
CONTINUE TO WORSEN THRU THE END OF THE PERIOD WITH IFR NOT TOTALLY
OUT OF THE QUESTION...LEANING TOWARD MORE OPTIMISTIC GUIDANCE ATTM
AND KEEPING IT MVFR. MAINLY NE TO ENE WINDS WILL PREVAIL WITH THE
WEDGE IN CONTROL.
OUTLOOK...A WEDGE OF COLD AIR WILL PERSIST ACROSS THE REGION SUNDAY
AND MONDAY. PERIODIC PRECIPITATION INTO THIS WEDGE WILL CREATE THE
POSSIBILITY OF FLIGHT RESTRICTIONS.
CONFIDENCE TABLE...
15-21Z 21-03Z 03-09Z 09-15Z
KCLT HIGH 100% HIGH 100% HIGH 83% HIGH 81%
KGSP HIGH 100% HIGH 92% HIGH 88% HIGH 100%
KAVL MED 78% MED 78% HIGH 94% HIGH 100%
KHKY HIGH 100% HIGH 97% HIGH 90% HIGH 87%
KGMU HIGH 100% HIGH 92% HIGH 87% HIGH 100%
KAND HIGH 100% HIGH 88% HIGH 83% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...CSH
NEAR TERM...NED/WIMBERLEY
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
546 AM CDT SAT APR 27 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 450 AM CDT SAT APR 27 2013
CLEAR SKIES AND WARM TEMPERATURES ON TAP AGAIN FOR TODAY... WITH
TEMPERATURES/HUMIDITY LEVELS THE PRIMARY CHALLENGE OF THE DAY. IN
THE IMMEDIATE TERM...DID ADD SOME PATCHY FOG TO OUR FAR SOUTHEAST
AREAS EARLY THIS MORNING. HIGHER DEW POINTS HAVE BEEN PERSISTING
SOUTH OF WEAKENING RIDGE AXIS OVERNIGHT...AND CAN SOMEWHAT SEE THE
MOISTURE DISCONTINUITY ROUGHLY SOUTH OF VERMILLION TO SPENCER IOWA
LINE ON THE IR SATELLITE IMAGERY THIS MORNING. ANY FOG EXPECTED TO
BE RELATIVELY SHALLOW GIVEN DEVELOPMENT THIS LATE IN THE OVERNIGHT
SO EXPECT IT TO DISSIPATE QUICKLY AS TEMPERATURES BEGIN TO RISE.
WITH SUNSHINE...DEEP DRY ATMOSPHERE...AND RELATIVE DRY GROUND
OUTSIDE THE AREAS WITH MOST RECENT SNOW MELT...TEMPERATURES HAVE BEEN
MIXING TO THE FULLEST AND SEE NO REASON WHY THAT WOULD NOT OCCUR
AGAIN TODAY. THUS HAVE WARMED HIGHS TODAY A LITTLE ABOVE MOST
GUIDANCE...RANGING FROM AROUND 70 OVER THE REMAINING SNOW COVER
ALONG THE BUFFALO RIDGE TO AROUND 80S IN THE WESTERN THIRD OF THE
CWA.
BOUNDARY LAYER DRYING ALSO AN ISSUE...PRIMARILY FOR FIRE WEATHER
CONCERNS. SIMILAR TO YESTERDAY...WOULD EXPECT DRIER AIR TO MIX DOWN
TO THE SURFACE THROUGH THE AFTERNOON. MODELS DID NOT SEEM TO HAVE A
GREAT TRACK RECORD ON DROPPING DOWN THE AFTERNOON DEW POINTS WITH
MIXING YESTERDAY...AND LOOKS LIKE SIMILAR DIFFICULTY MAY BE SEEN
TODAY WITH NAM FORECAST SOUNDINGS SEEMING TO MIX THE SOMEWHAT MORE
MOIST BOUNDARY LAYER UPWARD INSTEAD OF MIXING THE DEEPER DRY AIR
ALOFT DOWNWARD. RAP MODEL SOUNDINGS SEEM TO BETTER REFLECT THIS
THINKING...AND MODEL DEW POINTS RESPOND ACCORDINGLY AND FOLLOWED
THESE MORE CLOSELY FOR DEW POINT/HUMIDITY TRENDS LATER THIS MORNING
THROUGH THE AFTERNOON. THIS WILL RESULT IN HIGH FIRE DANGER ACROSS
OUR WESTERN FORECAST AREA THIS AFTERNOON...BUT WINDS SHOULD BE LIGHT
ENOUGH TO KEEP BELOW VERY HIGH CATEGORY.
START TO SEE SOME INCREASE IN CLOUDS ACROSS OUR NORTHWEST LATER
TONIGHT IN ADVANCE OF UPPER WAVE/ASSOCIATED WEAK COLD FRONT MOVING
INTO THE NORTHERN PLAINS. VERY MILD LOW LEVEL AIR ALONG WITH LIGHT
SOUTHERLY FLOW SHOULD KEEP TEMPERATURES WELL ABOVE NORMAL WITH LOWS
IN THE 40S TO NEAR 50.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 450 AM CDT SAT APR 27 2013
A LITTLE MORE ACTIVE PATTERN SETS UP EARLY NEXT WEEK...INITIALLY
WITH A CHANCE OF LATE AFTERNOON/EVENING SHOWERS OR THUNDERSTORMS
ACROSS OUR EAST SUNDAY AS THE COOL FRONT SLIDES THROUGH A SOMEWHAT
MORE MOIST ATMOSPHERE...THEN WITH A BETTER CHANCE OF RAIN LATER
SUNDAY NIGHT ALONG AND SOUTH OF I-90 AS MID LEVEL MOVES THROUGH THE
REGION. SUNDAY SHOULD BE ANOTHER WARM DAY...LIKELY THE WARMEST OF
THIS STRETCH OVER OUR SOUTHERN AREAS...WHILE THE NORTH SHOULD SEE
TEMPERATURES PEAK MORE IN THE MIDDAY/EARLY AFTERNOON WITH COOLING
THROUGH THE LATER AFTERNOON AS COLD ADVECTION SETS IN AND CLOUDS
INCREASE.
MONDAY WILL BE SLIGHTLY COOLER BEHIND THE FRONT...WITH JUST A CHANCE
OF LINGERING LIGHT RAIN IN OUR FAR SOUTHEAST IN THE MORNING AND
SKIES BECOMING MOSTLY SUNNY AGAIN BY AFTERNOON. WARM RETURN FLOW
QUICKLY SETS LATE MONDAY AFTERNOON/EVENING AND WHILE MID LEVEL
SHOWERS/THUNDERSTORMS ARE POSSIBLE ON THE NOSE OF LOW LEVEL JET...
THIS LOOKS TO BE FOCUSED TO OUR NORTH AND WILL KEEP OUR AREA DRY
THROUGH MONDAY NIGHT.
SHARP COLD FRONT THEN MOVES THROUGH LATE MONDAY NIGHT/TUESDAY...
THOUGH STRONG MIXING BEHIND THE FRONT SHOULD STILL KEEP HIGHS ON
TUESDAY NEAR TO SLIGHTLY ABOVE NORMAL IN THE 60S TO LOWER 70S. 850MB
FRONT STALLS JUST SOUTHEAST OF OUR AREA TUESDAY NIGHT WHILE STRONGER
UPPER TROUGH SWINGS OUT OF THE ROCKIES. THIS WILL BRING INCREASING
RAIN CHANCES TO THE AREA TUESDAY NIGHT INTO WEDNESDAY...MAINLY IN
OUR SOUTHEAST.
SECONDARY COLD FRONT ASSOCIATED WITH THIS WAVE WILL BRING A RETURN
TO BELOW NORMAL TEMPERATURES FROM WEDNESDAY THROUGH THE END OF THE
WEEK. LONG RANGE MODELS VASTLY DIFFERENT ON EVOLUTION OF UPPER
TROUGH AFTER IT PASSES THROUGH OUR AREA WEDNESDAY. GFS DEVELOPS A
CUTOFF LOW OVER THE WESTERN OHIO VALLEY WHILE THE ECMWF BUILDS A
MUCH STRONGER RIDGE OVER THE GREAT LAKES WHICH FORCES THE UPPER LOW
TO DEVELOP OVER THE CENTRAL PLAINS. FORMER WOULD KEEP US DRY THROUGH
THE END OF THE WEEK...WHILE THE LATTER RESULTS IN QUITE A WET PERIOD
FOR PARTS OF THE REGION. GIVEN HIGH DEGREE OF UNCERTAINTY...WILL
KEEP THE LATTER HALF OF THE WEEK DRY FOR NOW...ASIDE FROM LINGERING
LOW CHANCE OF PRECIPITATION IN OUR FAR SOUTHEAST WEDNESDAY NIGHT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 547 AM CDT SAT APR 27 2013
AREAS OF VISIBILITIES 3-5SM IN LIGHT FOG THROUGH 15Z OVER THE
SOUTHEAST CORNER OF THE AREA...FROM SUX TO SLB...WITH VERY LOCAL
CEILINGS BELOW 1K FEET AND VISIBILITIES BELOW 3SM IN FOG THROUGH
15Z IN THE SAME PART OF THE AREA. THE FOG SHOULD DISSIPATE BY
15Z...OTHERWISE VFR IS EXPECTED OVER THE AREA THROUGH 28/12Z.
STRONGER SURFACE AND LOW LEVEL FLOW SHOULD PREVENT ANY LOWERING OF
CONDITIONS NEAR THE END OF THE PERIOD.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...JH
LONG TERM...JH
AVIATION...
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
913 AM CDT SAT APR 27 2013
.MESOSCALE UPDATE...
AT 14Z WARM FRONT DRAPED ACROSS SOUTHERN ARKANSAS AND NORTHERN
MISSISSIPPI SOUTH OF CLARKDALE. MID STATE WELL NORTH OF WARM FRONT
AND ON COOL SIDE WITH WIDESPREAD SHOWERS STRUNG OUT FROM WEST TO
EAST ACROSS WEST AND MIDDLE TENNESSEE WORKING EASTWARD. THERE IS A
SMALL CLUSTER OF THUNDERSTORMS CURRENTLY IN PERRY COUNTY WITH A
FEW MORE STORMS STILL IN WESTERN TENNESSEE YET TO COME EAST.
INFRARED CLOUD TOPS HAVE REMAINED COLD LAST FEW IMAGES WITH NO
SIGN OF WARMING. BELIEVE BEST CHANCE FOR LIGHTNING THROUGH 21Z WILL
BE SOUTH OF INTERSTATE 40...THIS BASED ON LATEST SREF RUN.
LOOKS LIKE FRONT IS GOING TO BE SLOW LIFTING NORTH DURING THE DAY
AS UPPER LEVEL ENERGY STILL REMAINS WELL WEST OF SURFACE BOUNDARY.
SURFACE LOW THIS MORNING CENTERED SOUTH OF FORT SMITH AND IS
FORECAST TO MOVE EASTWARD DURING THE DAY AND BE NEAR MEMPHIS BY
00Z THIS EVENING. AM EXPECTING WARM FRONT TO BEGIN LIFTING NORTH
AND INTO SOUTHWEST MIDDLE TENNESSEE AFTER 20Z TODAY WITH
INCREASING CAPES AND INSTABILITY ALONG WITH RISING SURFACE TEMPS
AND DEWPOINTS OVER THE SOUTHWESTERN AREAS DURING THE LATE
AFTERNOON AND WORK NORTHEASTWARD INTO MIDDLE TENNESSEE DURING THE
EARLY EVENING. THINK A FEW STRONG TO SEVERE STORMS ARE POSSIBLE
DURING THE LATE AFTERNOON/EVENING ESPECIALLY SOUTHWEST MIDDLE TENNESSEE
WHERE INSTABILITY LOOKS TO BE THE STRONGEST...BUT ISOLATED SEVERE
CANT BE RULED OUT ELSEWHERE IN THE MID STATE FROM MID TO LATE
EVENING AS INSTABILITY TRIES TO COME NORTH ALONG SURFACE BOUNDARY.
AS FOR TODAYS HIGHS...WARMER TEMPS WILL BE IN THE SOUTHWEST WHERE I
HAVE LOWER 70S WITH 60S ELSEWHERE. ONCE THIS INITIAL ROUND OF
SHOWERS AND ISOLATED THUNDERSTORMS GETS TO OUR EAST AM EXPECTING
NEW DEVELOPMENT TO TAKE PLACE. ALL IN ALL IT LOOKS VERY MUCH LIKE
A WET SATURDAY.
BOYD
&&
.PREV DISCUSSION... /ISSUED 716 AM CDT SAT APR 27 2013/
UPDATE...FOR 12Z AVIATION FORECAST
AVIATION...TODAY WILL BE CHARACTERIZED BY STRONG WARM ADVECTION
IN A VERY MOIST AIRMASS AS UPPER LEVEL LOW OVER KS MOVES SLOWLY
INTO MO. NUMEROUS SHOWERS AND SOME THUNDERSTORMS...ALONG WITH LOW
CIGS AND 3 TO 5 MILE VSBYS...WILL SPREAD ACROSS CKV...BNA...AND
CSV THIS MORNING. MUCH OF THE RAIN WILL DIMINISH BY 18Z AT CKV
..BY 20Z AT BNA...AND BY 22Z AT CSV. HOWEVER...SHOWERS AND STORMS
WILL RETURN OVERNIGHT ACROSS THE ENTIRE REGION AS UPPER TROF
MOVES FROM MO EASTWARD THROUGH THE OHIO VALLEY. A TRAILING WEAK COLD
FRONT WILL MOVE THROUGH MIDDLE TN ON SUNDAY AS THE UPPER TROF
HEADS TOWARD THE GREAT LAKES.
PREV DISCUSSION... /ISSUED 417 AM CDT SAT APR 27 2013/
.SLIGHT RISK OF SEVERE STORMS THIS AFTERNOON AND TONIGHT...
.WIDESPREAD RAIN AND THUNDERSTORMS TO CONTINUE THIS WEEKEND...
SHORT TERM...
LATEST RADAR IMAGERY SHOWS WIDESPREAD LIGHT TO MODERATE RAIN
CONTINUES ACROSS MOST OF THE FORECAST AREA...WITH MORE ISOLATED
SHOWERS ACROSS WAYNE/LAWRENCE/GILES COUNTIES. PRECIPITATION
IS BEING AIDED BY A WEAK SHORTWAVE TROUGH EVIDENT ACROSS EASTERN
TENNESSEE...AND IS FOCUSED ALONG AND NORTH OF A 850 MB WARM FRONT
THAT CURRENTLY EXTENDS FROM DYERSBURG TO WINCHESTER. PRECIPITATION
WILL CONTINUE TO BE GENERATED TODAY DUE TO SUSTAINED WAA ABOVE
THE FRONTAL SURFACE...WITH RENEWED DEVELOPMENT TO OUR WEST AS THE
NEXT WEAK SHORTWAVE CURRENTLY SEEN ALONG THE MISSISSIPPI RIVER
APPROACHES. INDEED...MOSAIC RADAR IMAGERY SHOWS A LARGE AREA OF
SHOWERS AND THUNDERSTORMS HAS ALREADY REDEVELOPED IN WESTERN
TENNESSEE WHICH WILL MOVE ACROSS THE CWA LATER THIS MORNING.
HEAVIEST ACTIVITY IS EXPECTED TO BE IN AN ARC FROM NORTHWEST TO
SOUTHEAST ACROSS THE CENTER OF THE CWA...WITH FAR SOUTHWEST AND
NORTHEAST AREAS SEEING MORE SCATTERED ACTIVITY.
BY AFTERNOON...SOME GLOBAL AND MESOSCALE MODELS DEPICT A BREAK IN
THE WIDESPREAD RAINFALL AS SHORTWAVE CURRENTLY ALONG THE MS RIVER
MOVES OFF TO THE EAST. HAVE THUS LOWERED POPS INTO THE LIKELY
CATEGORY THIS AFTERNOON...BUT REMAINS UNCERTAIN HOW MUCH OF A
BREAK WILL BE SEEN AS OTHER MODELS SUCH AS THE HRRR CONTINUE
PRECIPITATION NONSTOP. REGARDLESS...MAIN UPPER LOW SEEN ON WATER
VAPOR IMAGERY ACROSS OK/KS WILL APPROACH THE MISSISSIPPI RIVER
LATER THIS AFTERNOON AND EVENING. AS THIS OCCURS...A WEAK SURFACE
LOW IS PROGGED BY MODELS TO DEVELOP IN NORTHEAST ARKANSAS THEN
MOVE NORTHEAST INTO SOUTHERN KENTUCKY TONIGHT. STRENGTHENING WIND
FIELDS AND HIGHER SURFACE DEWPOINTS ADVECTING NORTHWARD COMBINED
WITH SOME DIURNAL HEATING SHOULD ALLOW FOR DESTABILIZATION OF THE
LOWER LEVELS OVER WESTERN ZONES. ALL GUIDANCE DEVELOPS ADDITIONAL
SHOWERS AND THUNDERSTORMS LATER THIS AFTERNOON AND EVENING ACROSS
WEST TENNESSEE AND NORTH MISSISSIPPI WHICH THEN MOVE INTO THE MID
STATE THROUGH SATURDAY NIGHT. FORECAST SOUNDINGS SHOW WEAK TO
MODERATE INSTABILITY/SHEAR WITH RELATIVELY COLD MID
LEVELS LATER TODAY...SUGGESTING DAMAGING WINDS AND LARGE HAIL
WOULD BE POSSIBLE WITH THE STRONGEST STORMS. INDEED...MESOSCALE
MODELS SHOW SOME ROBUST STORMS IN OUR WESTERN COUNTIES AROUND 00Z
THIS EVENING. SPC HAS UPGRADED PORTIONS OF WESTERN ZONES INTO A
SLIGHT RISK FOR THIS AFTERNOON AND TONIGHT. EASTWARD EXTENT OF ANY
SEVERE ACTIVITY THAT MAY DEVELOP WILL BE GREATLY LIMITED BY MORE
STABLE CONDITIONS EAST OF THE SLIGHT RISK AREA.
GUIDANCE DEPICTS A DRY SLOT ALOFT ADVANCING ACROSS WESTERN
PORTIONS OF THE MID STATE ON SUNDAY AS UPPER LOW ADVANCES THROUGH
THE OHIO VALLEY. THIS WILL LOWER PRECIP CHANCES OVER THE WEST WITH
HIGH POPS CONTINUING OVER THE EAST. ALL ACTIVITY SHOULD WIND DOWN
BY SUNDAY NIGHT AS UPPER LOW MOVES EAST OF THE REGION. TOTAL
RAINFALL AMOUNTS FOR THIS WEEKEND RAIN EVENT APPEAR TO BE IN THE 1
TO 2 INCH RANGE NORTH OF I-40 WITH 2 TO 3 INCHES SOUTH OF
I-40...BUT SOME 4 INCH AMOUNTS ARE POSSIBLE WITH ANY SUSTAINED
HEAVIER THUNDERSTORMS. ALTHOUGH NO WIDESPREAD FLASH FLOODING IS
EXPECTED...SOME LOCALIZED FLOODING IS CERTAINLY POSSIBLE AND
RUNOFF INTO AREA RIVERS MAY RESULT IN SOME RISING INTO ACTION
STAGE NEXT WEEK.
LONG TERM...
WARMER AND DRIER WEATHER IS ANTICIPATED FOR MONDAY AND TUESDAY AS
WEAK RIDGING ALOFT BUILDS OVER THE TENNESSEE VALLEY REGION. LOW
PRECIP CHANCES RETURN BY WEDNESDAY AS A WEAK UPPER LOW DEVELOPS
IN THE GULF COAST STATES. FOR THE END OF THE FORECAST
PERIOD...00Z GFS/ECMWF HAVE CONTINUED THE HIGHLY ANOMALOUS TREND
OF THE PAST FEW DAYS IN DEVELOPING A LARGE AND INTENSE CUT OFF H5
LOW WHICH THEN MEANDERS FOR DAYS ACROSS THE EASTERN CONUS.
UNFORTUNATELY...GFS AND ECMWF DIFFER BY 600 MILES ON THEIR
PLACEMENT OF THE UPPER LOW WHICH RESULTS IN TEMPERATURE
DIFFERENCES OF 20 DEGREES OR MORE FOR HIGHS AND LOWS. FOR NOW
WILL GO WITH LOW POPS FOR THE END OF NEXT WEEK AND TREND
TEMPERATURES TOWARDS THE COLDER MEX GUIDANCE...ALTHOUGH FORECAST
IN THE LONG RANGE SHOULD BE CONSIDERED EXTREMELY LOW CONFIDENCE.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
01
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
716 AM CDT SAT APR 27 2013
.UPDATE...FOR 12Z AVIATION FORECAST
&&
.AVIATION...TODAY WILL BE CHARACTERIZED BY STRONG WARM ADVECTION
IN A VERY MOIST AIRMASS AS UPPER LEVEL LOW OVER KS MOVES SLOWLY
INTO MO. NUMEROUS SHOWERS AND SOME THUNDERSTORMS...ALONG WITH LOW
CIGS AND 3 TO 5 MILE VSBYS...WILL SPREAD ACROSS CKV...BNA...AND
CSV THIS MORNING. MUCH OF THE RAIN WILL DIMINISH BY 18Z AT CKV
...BY 20Z AT BNA...AND BY 22Z AT CSV. HOWEVER...SHOWERS AND STORMS
WILL RETURN OVERNIGHT ACROSS THE ENTIRE REGION AS UPPER TROF
MOVES FROM MO EASTWARD THROUGH THE OHIO VALLEY. A TRAILING WEAK COLD
FRONT WILL MOVE THROUGH MIDDLE TN ON SUNDAY AS THE UPPER TROF
HEADS TOWARD THE GREAT LAKES.
&&
.PREV DISCUSSION... /ISSUED 417 AM CDT SAT APR 27 2013/
..SLIGHT RISK OF SEVERE STORMS THIS AFTERNOON AND TONIGHT...
..WIDESPREAD RAIN AND THUNDERSTORMS TO CONTINUE THIS WEEKEND...
SHORT TERM...
LATEST RADAR IMAGERY SHOWS WIDESPREAD LIGHT TO MODERATE RAIN
CONTINUES ACROSS MOST OF THE FORECAST AREA...WITH MORE ISOLATED
SHOWERS ACROSS WAYNE/LAWRENCE/GILES COUNTIES. PRECIPITATION
IS BEING AIDED BY A WEAK SHORTWAVE TROUGH EVIDENT ACROSS EASTERN
TENNESSEE...AND IS FOCUSED ALONG AND NORTH OF A 850 MB WARM FRONT
THAT CURRENTLY EXTENDS FROM DYERSBURG TO WINCHESTER. PRECIPITATION
WILL CONTINUE TO BE GENERATED TODAY DUE TO SUSTAINED WAA ABOVE
THE FRONTAL SURFACE...WITH RENEWED DEVELOPMENT TO OUR WEST AS THE
NEXT WEAK SHORTWAVE CURRENTLY SEEN ALONG THE MISSISSIPPI RIVER
APPROACHES. INDEED...MOSAIC RADAR IMAGERY SHOWS A LARGE AREA OF
SHOWERS AND THUNDERSTORMS HAS ALREADY REDEVELOPED IN WESTERN
TENNESSEE WHICH WILL MOVE ACROSS THE CWA LATER THIS MORNING.
HEAVIEST ACTIVITY IS EXPECTED TO BE IN AN ARC FROM NORTHWEST TO
SOUTHEAST ACROSS THE CENTER OF THE CWA...WITH FAR SOUTHWEST AND
NORTHEAST AREAS SEEING MORE SCATTERED ACTIVITY.
BY AFTERNOON...SOME GLOBAL AND MESOSCALE MODELS DEPICT A BREAK IN
THE WIDESPREAD RAINFALL AS SHORTWAVE CURRENTLY ALONG THE MS RIVER
MOVES OFF TO THE EAST. HAVE THUS LOWERED POPS INTO THE LIKELY
CATEGORY THIS AFTERNOON...BUT REMAINS UNCERTAIN HOW MUCH OF A
BREAK WILL BE SEEN AS OTHER MODELS SUCH AS THE HRRR CONTINUE
PRECIPITATION NONSTOP. REGARDLESS...MAIN UPPER LOW SEEN ON WATER
VAPOR IMAGERY ACROSS OK/KS WILL APPROACH THE MISSISSIPPI RIVER
LATER THIS AFTERNOON AND EVENING. AS THIS OCCURS...A WEAK SURFACE
LOW IS PROGGED BY MODELS TO DEVELOP IN NORTHEAST ARKANSAS THEN
MOVE NORTHEAST INTO SOUTHERN KENTUCKY TONIGHT. STRENGTHENING WIND
FIELDS AND HIGHER SURFACE DEWPOINTS ADVECTING NORTHWARD COMBINED
WITH SOME DIURNAL HEATING SHOULD ALLOW FOR DESTABILIZATION OF THE
LOWER LEVELS OVER WESTERN ZONES. ALL GUIDANCE DEVELOPS ADDITIONAL
SHOWERS AND THUNDERSTORMS LATER THIS AFTERNOON AND EVENING ACROSS
WEST TENNESSEE AND NORTH MISSISSIPPI WHICH THEN MOVE INTO THE MID
STATE THROUGH SATURDAY NIGHT. FORECAST SOUNDINGS SHOW WEAK TO
MODERATE INSTABILITY/SHEAR WITH RELATIVELY COLD MID
LEVELS LATER TODAY...SUGGESTING DAMAGING WINDS AND LARGE HAIL
WOULD BE POSSIBLE WITH THE STRONGEST STORMS. INDEED...MESOSCALE
MODELS SHOW SOME ROBUST STORMS IN OUR WESTERN COUNTIES AROUND 00Z
THIS EVENING. SPC HAS UPGRADED PORTIONS OF WESTERN ZONES INTO A
SLIGHT RISK FOR THIS AFTERNOON AND TONIGHT. EASTWARD EXTENT OF ANY
SEVERE ACTIVITY THAT MAY DEVELOP WILL BE GREATLY LIMITED BY MORE
STABLE CONDITIONS EAST OF THE SLIGHT RISK AREA.
GUIDANCE DEPICTS A DRY SLOT ALOFT ADVANCING ACROSS WESTERN
PORTIONS OF THE MID STATE ON SUNDAY AS UPPER LOW ADVANCES THROUGH
THE OHIO VALLEY. THIS WILL LOWER PRECIP CHANCES OVER THE WEST WITH
HIGH POPS CONTINUING OVER THE EAST. ALL ACTIVITY SHOULD WIND DOWN
BY SUNDAY NIGHT AS UPPER LOW MOVES EAST OF THE REGION. TOTAL
RAINFALL AMOUNTS FOR THIS WEEKEND RAIN EVENT APPEAR TO BE IN THE 1
TO 2 INCH RANGE NORTH OF I-40 WITH 2 TO 3 INCHES SOUTH OF
I-40...BUT SOME 4 INCH AMOUNTS ARE POSSIBLE WITH ANY SUSTAINED
HEAVIER THUNDERSTORMS. ALTHOUGH NO WIDESPREAD FLASH FLOODING IS
EXPECTED...SOME LOCALIZED FLOODING IS CERTAINLY POSSIBLE AND
RUNOFF INTO AREA RIVERS MAY RESULT IN SOME RISING INTO ACTION
STAGE NEXT WEEK.
LONG TERM...
WARMER AND DRIER WEATHER IS ANTICIPATED FOR MONDAY AND TUESDAY AS
WEAK RIDGING ALOFT BUILDS OVER THE TENNESSEE VALLEY REGION. LOW
PRECIP CHANCES RETURN BY WEDNESDAY AS A WEAK UPPER LOW DEVELOPS
IN THE GULF COAST STATES. FOR THE END OF THE FORECAST
PERIOD...00Z GFS/ECMWF HAVE CONTINUED THE HIGHLY ANOMALOUS TREND
OF THE PAST FEW DAYS IN DEVELOPING A LARGE AND INTENSE CUT OFF H5
LOW WHICH THEN MEANDERS FOR DAYS ACROSS THE EASTERN CONUS.
UNFORTUNATELY...GFS AND ECMWF DIFFER BY 600 MILES ON THEIR
PLACEMENT OF THE UPPER LOW WHICH RESULTS IN TEMPERATURE
DIFFERENCES OF 20 DEGREES OR MORE FOR HIGHS AND LOWS. FOR NOW
WILL GO WITH LOW POPS FOR THE END OF NEXT WEEK AND TREND
TEMPERATURES TOWARDS THE COLDER MEX GUIDANCE...ALTHOUGH FORECAST
IN THE LONG RANGE SHOULD BE CONSIDERED EXTREMELY LOW CONFIDENCE.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
49
AREA FORECAST DISCUSSION
NWS AUSTIN/SAN ANTONIO TX
1046 AM CDT SAT APR 27 2013
.UPDATE...
TO EXTEND SLIGHT RISK OF SEVERE THUNDERSTORMS AND REMOVE MORNING DRIZZLE.
&&
.DISCUSSION...
THE MORNING UPDATE FROM SPC EXTENDED THE SLIGHT RISK AREA TO COVER
ALL OF SOUTH CENTRAL TEXAS. EXPECTING CONVECTION TO DEVELOP OVER
THE MEXICAN MOUNTAINS AND ALONG A COLD FRONT LATER THIS EVENING.
THE COLD FRONT IS CURRENTLY LYING JUST NORTH OF OUR NORTHERN CWA
BORDER FROM AROUND LAMPASAS TO SONORA TO SANDERSON. THIS FRONT
WILL DRIFT SOUTHWARD THROUGH THE AFTERNOON AND WILL LIKELY BE THE
FOCUS FOR THUNDERSTORMS. DEW POINTS SOUTH OF THE FRONT ARE IN THE
MID TO UPPER 60S. CLOUD COVER WILL KEEP TEMPERATURES DOWN UNTIL
AFTERNOON AND LIMITING INSTABILITY IN THE BOUNDARY LAYER. FORECAST
SOUNDINGS SHOW CAPE RISING TO 1500-2000 J/KG LATER TODAY. STILL
DISAGREEMENT ON TIMING. GFS IS LATER TO DEVELOP STRONG INSTABILITY
AND THIS SEEMS MORE LIKELY WITH LATER EROSION OF CLOUD DECK.
OUR FORECAST LOOKS TO BE IN GOOD SHAPE WITH MOST CONVECTION AFTER
00Z. HAVE REMOVED MENTION OF MORNING DRIZZLE. DRIZZLE OR SPRINKLES
MAY STILL OCCUR...BUT WILL BE ISOLATED AND NOT WORTH KEEPING IN
FORECAST. HAVE ALSO MADE MINOR ADJUSTMENTS TO HOURLY GRIDS TO
ACCOUNT FOR OBSERVATIONAL TRENDS.
&&
.PREV DISCUSSION... /ISSUED 631 AM CDT SAT APR 27 2013/
DISCUSSION...
SEE AVIATION FOR THE 12Z TAF DISCUSSION.
AVIATION...
THE PRIMARY CHALLENGE FOR THIS TAF PACKAGE IS THE TIMING OF THUNDERSTORMS
FOR THIS EVENING INTO EARLY TONIGHT. A WEAK FRONTAL BOUNDARY WILL FILTER
SOUTHWARD ACROSS THE HILL COUNTRY THIS EVENING BECOMING STATIONARY IN
THE VICINITY OF HIGHWAY 90 WHILE AN UPPER LEVEL IMPULSE MOVES EASTWARD
OUT OF MEXICO. THE FRONTAL BOUNDARY AND THE EASTERN SLOPES OF THE SIERRA
MADRE WILL BE THE FOCUS AREAS OF CONVECTIVE DEVELOPMENT. THE UPPER LEVEL
DISTURBANCE WILL HELP IN THE PROPAGATION OF CONVECTION TO THE EAST AND
SOUTHEAST OVERNIGHT. A BLEND OF THE 00Z ARW...07Z RUC13 AND 00Z TTU
3KM WRF WILL BE USED FOR TIMING OF THUNDERSTORMS IMPACTING THE TAF
SITES. OTHERWISE MVFR CIGS WILL PREVAIL THIS MORNING IMPROVING TO VFR
THIS AFTERNOON. CIGS WILL ONCE AGAIN LOWER TO MVFR AFTER 06Z...IFR BY
11Z. SFC WINDS TODAY S TO SE AT 5 TO 10 KTS...BACKING TO THE EAST AT
5 TO 8 KTS OVERNIGHT BECOMING L/V BY SUNDAY MORNING.
PREV DISCUSSION... /ISSUED 325 AM CDT SAT APR 27 2013/
SHORT TERM (TODAY THROUGH SUNDAY)...
INCREASING CHANCES FOR RAIN THIS WEEKEND AS A COLD FRONT SLIDES INTO
THE REGION. FOR TODAY...A CONTINUED SOUTHEAST INFLUX OF LOW LEVEL
MOISTURE WILL KEEP THE AREA POTENTIALLY UNSTABLE AS BOUNDARIES
APPROACH THE AREA. A MIXED LAYER CAP ALOFT WILL KEEP MUCH
CONVECTION FROM FIRING UNTIL AFTER DARK WHEN LOW LEVEL CONVERGENT
FORCES TAKE OVER (ALONG WITH SUPPORT ALOFT FROM A MID LEVEL JET).
HIGHS TODAY WILL BE IN THE 80S. WILL PLACE AT LEAST A SLIGHT
CHANCE OF THUNDERSTORMS OVER OUR NORTHERN CWA ALONG THE FRONT FOR
THIS AFTERNOON. THE COLD FRONT...LOCATED EARLY THIS MORNING OVER
THE TEXAS SOUTH PLAINS WILL SLIP SOUTH INTO OUR NORTHERN CWA BY
AFTERNOON. THE GFS MODEL SOLUTION STALLS THE FRONT OVER OVER
NORTHERN CWA DURING THE EVENING...THEN EDGES IT SOUTHWARD INTO THE
CENTRAL CWA OVERNIGHT. THIS IS SIGNIFICANT IN AS FAR AS RAINFALL
AND POTENTIALLY SEVERE WEATHER ARE CONCERNED AS BURRO MOUNTAIN
(MEXICAN PLATEAU) STORMS WHICH DEVELOP DURING THE LATE AFTERNOON/
EVENING HOURS PUSH EASTWARD AND INTERSECT THE FRONT DURING THE
OVERNIGHT HOURS OVER WESTERN SECTIONS. MOIST LOW LEVEL SOUTHEAST
FLOW (DEWPOINTS IN UPPER 60S) WILL MAINTAIN THESE STORMS AS THEY
TRAVERSE EAST...INTERSECTING THE FRONT AND ENHANCING RAIN AMOUNTS
AND SEVERITY OF STORMS. WILL INCLUDE A CHANCE OF SOME OF THE
STORMS BECOMING SEVERE TONIGHT OVER THE WESTERN HALF OF THE CWA
.WITH THE GREATEST THREAT BEING FROM LARGE HAIL. SOME DAMAGING
WIND GUSTS ARE ALSO POSSIBLE. ISOLATED RAIN AMOUNTS OF 1 TO 3
INCHES ARE EXPECTED ALONG THE TRACK OF THE BURRO STORMS AS THEY
INTERSECT THE FRONT OVER WESTERN SECTIONS TONIGHT. SOME
STABILIZATION IS EXPECTED SUNDAY AS THE FRONT AND RAIN-COOLED AIR
SETTLE OVER THE AREA. HOWEVER THERE REMAINS ENOUGH DYNAMICS AND
INSTABILITY ALOFT FOR SOME RE-DEVELOPMENT OF STORMS IN DAYTIME
HEATING. HIGHS SUNDAY IN THE UPPER 70S HILLS...NEAR 80 TO LOW 80S
ELSEWHERE.
LONG TERM (SUNDAY NIGHT THROUGH FRIDAY)...
AS FRONTOLYSIS (DISSIPATION OR WEAKENING OF A FRONT) OCCURS SUNDAY
NIGHT...SOUTHEAST FLOW AND LIFT OVER THE WEAKENING BOUNDARY MAY BE
ENOUGH FOR ADDITIONAL CONVECTION. IN FACT...ANOTHER THREAT FOR
BURRO DEVELOPMENT MAY OCCUR OVERNIGHT SUNDAY/EARLY MONDAY MORNING
AS MOIST SOUTHEAST FLOW UPLIFTS ACROSS THE MEXICAN PLATEAU AMID A
WEAK UPPER LEVEL SUBTROPICAL JET. THIS INSTABILITY AND UNSETTLED
WEATHER PATTERN WILL LINGER THROUGH TUESDAY AS A MOIST SOUTHEAST
FLOW AT THE SURFACE AND COOLING ALOFT COUPLED WITH DISTURBANCES
TRIGGER FURTHER ACTIVITY ESPECIALLY OVER SOUTHWEST PORTIONS OF THE
CWA. THE UPPER TROUGH WILL EXIT THE REGION WEDNESDAY WITH A STABLE
NORTHERLY FLOW ALOFT IN PLACE. A STRONG COLD FRONT WILL THEN PUSH
RAPIDLY THROUGH THE REGION WEDNESDAY NIGHT WITH LOW CHANCES OF
SHOWERS AND THUNDERSTORMS LINING THE FRONT. DECREASING CLOUDINESS
AND MUCH COOLER THURSDAY WITH HIGHS GENERALLY IN THE 70S. SURFACE
RIDGING WILL SETTLE OVER THE AREA THURSDAY NIGHT AND EARLY FRIDAY
WITH LOWS FRIDAY MORNING MOSTLY IN THE 40S. MOSTLY SUNNY FRIDAY
WITH HIGHS IN THE 70S.
&&
.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY 84 62 83 60 84 / 10 50 30 10 10
AUSTIN BERGSTROM INTL AIRPORT 84 61 82 57 83 / 10 50 30 20 10
NEW BRAUNFELS MUNI AIRPORT 85 61 83 58 83 / 10 60 40 20 20
BURNET MUNI AIRPORT 83 60 81 57 83 / 20 50 20 10 10
DEL RIO INTL AIRPORT 85 66 81 64 84 / 10 60 40 30 20
GEORGETOWN MUNI AIRPORT 82 61 81 58 82 / 20 50 20 10 10
HONDO MUNI AIRPORT 84 63 81 60 83 / 10 70 40 30 20
SAN MARCOS MUNI AIRPORT 83 62 82 58 82 / 10 50 30 20 20
LA GRANGE - FAYETTE REGIONAL 85 66 83 62 84 / 20 40 30 10 20
SAN ANTONIO INTL AIRPORT 83 63 81 60 82 / 10 60 40 30 20
STINSON MUNI AIRPORT 84 63 81 61 82 / 10 60 40 30 20
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE/AVIATION...10
SYNOPTIC/GRIDS...05
PUBLIC SERVICE/DATA COLLECTION...32
AREA FORECAST DISCUSSION...CORRECTED
NWS FORT WORTH TX
1020 AM CDT SAT APR 27 2013
.UPDATE...
A COLD FRONT EXTENDED FROM JUST WEST OF PARIS TO SOUTHEAST OF
GREENVILLE...TERRELL...WEST...GATESVILLE AND LAMPASAS AT 16Z.
THIS FRONT WILL MOVE THROUGH WACO IN THE NEXT HALF HOUR...BUT
STALL OUT OVER THE SOUTHEASTERN PART OF THE FORECAST AREA THIS
AFTERNOON. HAVE ADJUSTED THE HOURLY WIND/TEMPERATURE/DEW POINT
GRIDS BASED ON THE LATEST RUC GUIDANCE WHICH SEEMS TO BE IN LINE
WITH ONGOING TRENDS.
THE 06Z TEXAS TECH WRF AND THE LATEST /12Z/ HIGH RESOLUTION RAPID
REFRESH...INDICATE THAT MOST OF THE SHOWERS AND THUNDERSTORMS
WILL BE TO THE SOUTH OF THE FORECAST AREA THIS AFTERNOON WITH A
LITTLE MORE MOVING INTO THE SOUTHEASTERN ZONES AFTER 23Z. FOR
NOW...HAVE LEFT POPS AS IS...BUT WE MAY BE ABLE TO TRIM A LITTLE
OFF LATER THIS AFTERNOON DEPENDING ON EXACTLY WHERE THE FRONT
STALLS.
58
&&
.AVIATION...
COLD FRONT IS KNOCKING ON THE METROPLEX/S DOOR THIS MORNING. FRONT
IS THROUGH ALLIANCE...AND WILL BE THROUGH THE OTHER 4 SITES IN THE
METRO WITHIN THE NEXT HOUR. LOW CLOUDS HAVE BEEN SCATTERED AHEAD
OF THE FRONT...BUT REMAIN IN PLACE NEAR WACO WHERE THE BEST LOW-
LEVEL MOISTURE IS LOCATED. LOW CLOUDS ARE EXPECTED TO FILL IN
BEHIND THE COLD FRONT. WILL START THE METRO TAF SITES OFF WITH A
NORTHWEST WIND AND LOW MVFR CIGS...EXCEPT KDAL AND KGKY WHERE THE
FROPA IS EXPECTED CLOSER TO 1230Z. CURRENT EXTRAPOLATION HAS THE
FRONT REACHING WACO AROUND 17Z...BEFORE STALLING SOUTH OF THE
AIRPORT. WILL KEEP MVFR IN THE TAFS UNTIL 17Z FOR THE METRO AND
21Z FOR WACO. THIS TIMING IS CLOSE TO WHAT THE LATEST RAP IS
SHOWING. LOW CLOUDS DO NOT EXTEND TOO FAR WEST...AND CLEARING
SHOULD OCCUR EARLIER THAN PREVIOUSLY EXPECTED. CANT RULE OUT A
SHOWER OR THUNDERSTORM CLOSER TO THE FRONT NEAR WACO THIS
AFTERNOON...BUT PROBABILITIES ARE TOO LOW TO MENTION IN THE TAF AT
THIS TIME.
HAMPSHIRE
&&
.PREV DISCUSSION... /ISSUED 415 AM CDT SAT APR 27 2013/
EARLY MORNING WATER VAPOR IMAGERY DEPICTED A CYCLONIC CIRCULATION
CENTERED OVER SOUTH CENTRAL KS OR NORTH CENTRAL OK MOVING EAST.
THIS CIRCULATION WAS LOCATED ON THE EAST END OF A POSITIVELY
TILTED CYCLONIC SHEAR AXIS EXTENDING WSW OVER THE TX PANHANDLE AND
OVER WEST CENTRAL AZ. TO THE EAST OF THE KS/OK UPPER LOW WAS A
LINE OF LOOSELY ORGANIZED THUNDERSTORMS LOCATED FROM NORTHWESTERN
AR SOUTHWEST TO SOUTHEAST OK. 08Z /3AM/ SURFACE OBSERVATIONS
DEPICTED A COLD FRONT LOCATED NEAR A BOWIE TO PK LAKE TO COMANCHE
LINE MOVING SOUTHEAST. THE FWD 00Z RAOB INDICATED A SUBSTANTIAL
CAP IN PLACE OVER NORTH TX...AND THIS CAP WAS LIKELY RESPONSIBLE
FOR THE DEARTH OF PRECIPITATION ALONG THE PORTION OF THE FRONT IN
TEXAS EARLY THIS MORNING.
TODAY AND TONIGHT...GUIDANCE CONSISTENTLY INDICATES THAT THE
CYCLONIC CIRCULATION/UPPER LOW OVER THE KS/OK BORDER EARLY THIS
MORNING WILL DEEPEN INTO A CLOSED LOW WHILE MOVING EAST OVER THE
NEXT 24 HRS. THIS WILL CAUSE THE CYCLONIC SHEAR AXIS TO SWING
SOUTHEAST IN ITS WAKE OVER THE CWA LATE THIS AFTERNOON THROUGH THE
OVERNIGHT HRS. THE EVOLUTION OF THIS UPPER LEVEL SYSTEM WILL HAVE
SOME INTERESTING IMPACTS ON SURFACE FEATURES ACROSS NORTH AND
CENTRAL TX TODAY.
THE SURFACE LOW THAT WAS LOCATED JUST EAST OF WICHITA FALLS AT THE
TIME OF THIS DISCUSSION IS EXPECTED TO MOVE EAST NORTHEAST WITH
THE MAIN UPPER LOW OVER THE NEXT 24 HRS. THIS WILL CAUSE THE COLD
FRONT TO CONTINUE SOUTH ACROSS THE CWA THROUGH THIS AFTERNOON. AS
THE SURFACE LOW IS MOVING EAST ACROSS AR TODAY ANOTHER SURFACE LOW
IS EXPECTED TO DEVELOP OVER NORTHERN MEXICO TO THE WEST OF DEL RIO
IN RESPONSE TO THE CYCLONIC SHEAR AXIS MOVING SOUTHEAST. WITH A
NEW SURFACE LOW DEVELOPING TO THE SOUTHWEST...AND THE OTHER
SURFACE LOW MOVING OFF TO THE EAST...THE COLD FRONT WILL LIKELY
STALL OUT NEAR OR JUST SOUTHEAST OF A LINE FROM ATHENS TO WACO BY
THE MID-AFTERNOON HOURS.
OVERNIGHT MODELS ARE STILL NOT IN COMPLETE AGREEMENT AS TO WHERE
THE FRONT WILL COME TO A REST...BUT SOMEWHERE BETWEEN WACO AND
COLLEGE STATION IS THE CONSENSUS LOCATION. WHEREVER THE FRONT
STALLS...WITH LOW PRESSURE OFF TO THE NORTHEAST AND
SOUTHWEST...THE GENERAL LOW LEVEL WIND FIELD LOOKS TO BE
DOMINATED BY VERY WEAK DEFORMATION ON EITHER SIDE OF THE STALLED
FRONT THIS AFTERNOON. WEAK NORTHEAST WINDS NORTH OF THE FRONT AND
WEAK SOUTHWEST WINDS TO THE SOUTH WILL ACTUALLY MINIMIZE PURE
CONVERGENCE ALONG THE FRONT...MAKING IT VERY DIFFICULT TO
DETERMINE IF THE FRONT WILL BE AN IMPORTANT SOURCE OF LIFT THIS
AFTERNOON.
TEMPERATURES WILL GENERALLY BE WARMER SOUTHEAST OF THE
FRONT...BUT THE GULF MOISTURE IN PLACE WILL ACTUALLY SUPPORT
CLOUDIER CONDITIONS TO THE SOUTHEAST OF THE FRONT THIS AFTERNOON.
DRIER AIR TO THE NORTH COMBINED WITH SUBSIDENCE IN THE WAKE OF THE
DEPARTING UPPER LOW WILL CAUSE SKIES TO CLEAR OUT NORTH OF THE
FRONT. AFTERNOON SUNSHINE WILL WEAKEN THE TEMPERATURE GRADIENT
ALONG THE FRONT...REDUCING FRONTOGENETIC FORCING DURING THE PEAK
HEATING HRS OF THE DAY. AS A RESULT THINK MESOSCALE FORCING FOR
ASCENT ALONG THE FRONT WILL BE FAIRLY WEAK THIS AFTERNOON...
REDUCING CONFIDENCE IN CONVECTION INITIATION ALONG THE STALLED OUT
FRONT DURING THE PEAK HEATING HRS OF THE DAY.
AS A RESULT...BUMPED POPS DOWN A LITTLE BIT THRU SUNSET FOR
LOCATIONS ALONG AND SOUTH OF A LINE FROM COMANCHE TO CANTON.
GUIDANCE CONTINUES TO INDICATE THAT THERE WILL BE OVER 2000 J/KG
OF CAPE AVAILABLE FOR FREE CONVECTION IF STORMS CAN DEVELOP ALONG
THE FRONT. THEREFORE DESPITE THE LOW POPS...WILL CONTINUE TO
MENTION A CHANCE OF STRONG TO SEVERE STORMS AS ANYTHING THAT DOES
MANAGE TO DEVELOP WILL LIKELY BE QUITE STRONG THIS AFTERNOON.
DAMAGING WINDS AND LARGE HAIL WOULD BE THE MOST LIKELY HAZARDS IF
ANYTHING WERE ABLE TO DEVELOP ALONG THE FRONT THRU SUNSET.
TONIGHT...THE DRIER AIR TO THE NORTH WILL ACTUALLY HELP INCREASE
THE THERMAL GRADIENT ALONG THE STALLED OUT FRONT AS THIS AIR WILL
COOL MORE QUICKLY THAN THE CLOUDY AND MORE MOIST AIRMASS TO THE
SOUTH OF THE FRONT. AS A RESULT...EVEN THOUGH THIS SEEMS
COUNTER-INTUITIVE...OUR BEST CHANCES FOR STORMS ALONG THE FRONT MAY
BE WELL AFTER SUNSET TONIGHT. MODELS DO NOT REALLY INDICATE A BIG
INCREASE IN CONVERGENCE ALONG THE FRONT...BUT THE INCREASE IN THE
THERMAL GRADIENT WILL LEAD TO STRONGER MESOSCALE FORCING FOR
ASCENT. THIS COMBINED WITH THE MEAGER LARGE SCALE SUPPORT OFFERED
BY THE CYCLONIC SHEAR AXIS MOVING OVER THE REGION HAS CONFIDENCE A
BIT HIGHER IN STORMS ALONG THE FRONT AFTER SUNSET. AS A RESULT
WENT AHEAD AND BUMPED UP POPS FROM 00-12Z ALONG THE FRONT FOR
TONIGHT. SEVERE WEATHER CHANCES WILL NOT BE AS GREAT AFTER
SUNSET...HOWEVER LARGE HAIL IS STILL A POSSIBILITY WITH THE
STRONGEST STORMS. ANY STORMS THAT DEVELOP WILL LIKELY MOVE
PARALLEL TO THE FRONT...SO THERE IS A RISK FOR LOCALLY HEAVY
RAINFALL DUE TO THE POTENTIAL FOR STORMS TO TRAIN ALONG THE FRONT
TONIGHT. THAT SAID...POPS ARE ONLY IN THE 30 TO 40 PERCENT CHANCE
RANGE...SO IT IS STILL POSSIBLE THAT FORCING REMAINS TOO WEAK FOR
ANYTHING ALONG THE FRONT OVERNIGHT.
SUNDAY THROUGH TUESDAY...GUIDANCE INDICATES THAT WEAK UPPER LEVEL
RIDGING WILL BUILD OVER THE NORTHERN PORTIONS OF THE SOUTH PLAINS
DURING THE PERIOD WHICH SHOULD HELP KEEP US DRY. THE ECMWF
STUBBORNLY INDICATES THAT THE TAILING END OF THE CYCLONIC SHEAR
AXIS MOVING SOUTH OVER TX TONIGHT WILL BECOME ISOLATED FROM THE
DEPARTING UPPER LOW/SHEAR AXIS AND FORM A WEAK CUT-OFF UPPER LOW
OVER THE TX GULF COAST DURING THIS PERIOD. BASED ON THE ECMWFS
EVOLUTION AND TRACK OF THIS FEATURE...IT IS SOMEWHAT
INCONSEQUENTIAL TO NORTH AND CENTRAL TX AS WE WOULD REMAIN NORTH
OR NORTHWEST OF THIS UPPER LOW THRU THE PERIOD. THE ECMWF HAS BEEN
CONSISTENT WITH THIS FEATURE...SO CONFIDENCE IS HIGHER THAT IT
WILL DEVELOP...HOWEVER THIS SHOULD JUST REINFORCE RIDGING OVER THE
CWA INCREASING CONFIDENCE IN A DRY FORECAST FROM SUNDAY AFTERNOON
THRU TUESDAY. EVEN IF THE UPPER LOW DEVELOPS...IT IS EXPECTED TO
REMAIN TOO WEAK TO HAVE A LARGE IMPACT ON THE SURFACE PRESSURE
PATTERN...THEREFORE WE SHOULD REMAIN IN SOUTHERLY FLOW DUE TO LEE
SIDE TROUGHING IN RESPONSE TO A POWERFUL UPPER LOW EXPECTED TO
SWING INTO THE PLAINS MID-WEEK. SOUTH WINDS AND SUBSIDENCE ALOFT
SHOULD HELP US BRING TEMPERATURES UP INTO THE 80S DURING THIS
PERIOD.
MID-WEEK...MEDIUM RANGE GUIDANCE CONTINUES TO STRUGGLE ON THE
EXACT EVOLUTION OF THE POWERFUL SYSTEM PROGGED TO MOVE OVER THE
PLAINS WEDNESDAY OR WEDNESDAY NIGHT. ASIDE FROM THE FAIRLY LARGE
PLACEMENT DISCREPANCIES BETWEEN THE GFS AND CANADIAN/ECMWF ALL
GUIDANCE AGREES THAT THIS UPPER LEVEL SYSTEM WILL BE UNSEASONABLY
STRONG AND MAY LEAD TO AN EXTENDED PERIOD OF BELOW NORMAL
TEMPERATURES FOR NORTH TX FOR THE FIRST SEVERAL DAYS OF MAY. THIS
FORECAST IS MOST IN LINE WITH THE CONSENSUS OF THE ECMWF/CANADIAN
OPERATIONAL MODELS THAT WERE VALID AT 27/00Z. THESE MODELS BRING
THE INITIAL UPPER LEVEL LOW OVER THE SOUTH PLAINS DRIVING A STRONG
COLD FRONT SOUTH ACROSS NORTH TX LATE WEDNESDAY AFTERNOON THRU THE
OVERNIGHT HRS.
ASSUMING THE UPPER LOW DIGS AS FAR SOUTH AS THESE MODELS
INDICATE...ALMOST ALL OF THE CWA WILL SEE SOME RAIN/THUNDERSTORMS
ALONG THE COLD FRONT AS IT MOVES THROUGH. DID NOT GO CRAZY WITH
THE POPS YET BECAUSE THE GFS CONTINUES TO INDICATE THAT THE UPPER
LOW WILL REMAIN SIGNIFICANTLY FURTHER NORTH...REDUCING
PRECIPITATION CHANCES ALONG THE FRONT. WENT AHEAD WITH 40 POPS
ALONG AND BEHIND THE FRONT WITH THIS FORECAST...BUT POPS MAY NEED
TO BE MUCH HIGHER IF THE CMC/ECMWF TRACK VERIFIES. ITS TOO EARLY
TO DETERMINE SEVERE WEATHER CHANCES...HOWEVER A LARGE OUTBREAK
DOES NOT LOOK LIKELY BECAUSE THE FRONT IS EXPECTED TO MOVE SOUTH
VERY QUICKLY WEDNESDAY AFTERNOON UNDERCUTTING MOST ORGANIZED
CONVECTION THAT INITIATES JUST OUT AHEAD OF THE FRONT.
EXTENDED...THE ECMWF INDICATES THAT A BIG BLOCKING PATTERN SETS
UP AFTER THE UPPER LOW MOVES INTO THE PLAINS FOR THE END OF THE
WEEK. THIS KEEPS THE UPPER LOW IN PLACE OVER THE CENTRAL PLAINS
THRU AT LEAST MAY 5TH...WHICH WOULD TEND TO KEEP TEMPERATURES
BELOW NORMAL OVER MOST OF THE CENTRAL AND SOUTHERN PLAINS THRU THE
FIRST WEEK OF MAY. THE COLDEST TEMPERATURES WOULD BE RIGHT AFTER
THE COLD FRONT...WITH TEMPERATURES MODERATING THEREAFTER AS THE
UPPER LOW DRIFTS NORTH OF THE CWA. CONFIDENCE IN THIS SOLUTION IS
NOT GREAT...HOWEVER MOST GUIDANCE INDICATES SOME SORT OF BLOCKING
PATTERN FOR LATE IN THE WEEK INTO NEXT WEEKEND...SO THE MAIN
FORECAST CONCERN IS WHERE WILL THE UPPER LOW BE WHEN THE BLOCKING
PATTERN SETS UP. AT THIS TIME KEPT TEMPERATURES BELOW NORMAL
DURING THIS PERIOD AS THERE IS NO GUIDANCE THAT SHOWS WE GET STUCK
IN A BLOCKING PATTERN WITH UPPER LEVEL RIDGING OVER THE PLAINS.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 79 56 81 59 86 / 10 5 5 0 0
WACO, TX 83 60 81 57 85 / 20 30 10 0 0
PARIS, TX 78 52 79 52 82 / 10 5 5 0 0
DENTON, TX 77 53 81 55 86 / 10 5 5 0 0
MCKINNEY, TX 77 53 80 56 85 / 10 5 5 0 0
DALLAS, TX 80 56 83 61 86 / 10 10 5 0 0
TERRELL, TX 80 54 81 55 84 / 20 10 5 0 0
CORSICANA, TX 83 59 81 58 83 / 20 20 5 0 0
TEMPLE, TX 84 62 80 58 84 / 30 40 20 0 0
MINERAL WELLS, TX 80 54 83 56 85 / 10 5 5 0 0
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
84/58
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1018 AM CDT SAT APR 27 2013
.UPDATE...
A COLD FRONT EXTENDED FROM JUST WEST OF PARIS TO SOUTHEAST OF
GREENVILLE...TERRELL...WEST...GATESVILLE AND LAMPASAS AT 16Z.
THIS FRONT WILL MOVE THROUGH WACO IN THE HALF HOUR...BUT STALL
OUT OVER THE SOUTHEASTERN PART OF THE FORECAST AREA THIS
AFTERNOON. HAVE ADJUSTED THE HOURLY WIND/TEMPERATURE/DEW POINT
GRIDS BASED ON THE LATEST RUC GUIDANCE WHICH SEEMS TO BE IN LINE
WITH ONGOING TRENDS.
THE 06Z TEXAS TECH WRF AND THE LATEST /12Z/ HIGH RESOLUTION RAPID
REFRESH...INDICATE THAT BUT MOST OF THE SHOWERS AND THUNDERSTORMS
WILL BE TO THE SOUTH OF THE FORECAST AREA THIS AFTERNOON WITH A
LITTLE MORE MOVING INTO THE SOUTHEASTERN ZONES AFTER 23Z. FOR
NOW...HAVE LEFT POPS AS IS...BUT WE MAY BE ABLE TO TRIM A LITTLE
OFF LATER THIS AFTERNOON DEPENDING ON EXACTLY WHERE THE FRONT
STALLS.
58
&&
.AVIATION...
COLD FRONT IS KNOCKING ON THE METROPLEX/S DOOR THIS MORNING. FRONT
IS THROUGH ALLIANCE...AND WILL BE THROUGH THE OTHER 4 SITES IN THE
METRO WITHIN THE NEXT HOUR. LOW CLOUDS HAVE BEEN SCATTERED AHEAD
OF THE FRONT...BUT REMAIN IN PLACE NEAR WACO WHERE THE BEST LOW-
LEVEL MOISTURE IS LOCATED. LOW CLOUDS ARE EXPECTED TO FILL IN
BEHIND THE COLD FRONT. WILL START THE METRO TAF SITES OFF WITH A
NORTHWEST WIND AND LOW MVFR CIGS...EXCEPT KDAL AND KGKY WHERE THE
FROPA IS EXPECTED CLOSER TO 1230Z. CURRENT EXTRAPOLATION HAS THE
FRONT REACHING WACO AROUND 17Z...BEFORE STALLING SOUTH OF THE
AIRPORT. WILL KEEP MVFR IN THE TAFS UNTIL 17Z FOR THE METRO AND
21Z FOR WACO. THIS TIMING IS CLOSE TO WHAT THE LATEST RAP IS
SHOWING. LOW CLOUDS DO NOT EXTEND TOO FAR WEST...AND CLEARING
SHOULD OCCUR EARLIER THAN PREVIOUSLY EXPECTED. CANT RULE OUT A
SHOWER OR THUNDERSTORM CLOSER TO THE FRONT NEAR WACO THIS
AFTERNOON...BUT PROBABILITIES ARE TOO LOW TO MENTION IN THE TAF AT
THIS TIME.
HAMPSHIRE
&&
.PREV DISCUSSION... /ISSUED 415 AM CDT SAT APR 27 2013/
EARLY MORNING WATER VAPOR IMAGERY DEPICTED A CYCLONIC CIRCULATION
CENTERED OVER SOUTH CENTRAL KS OR NORTH CENTRAL OK MOVING EAST.
THIS CIRCULATION WAS LOCATED ON THE EAST END OF A POSITIVELY
TILTED CYCLONIC SHEAR AXIS EXTENDING WSW OVER THE TX PANHANDLE AND
OVER WEST CENTRAL AZ. TO THE EAST OF THE KS/OK UPPER LOW WAS A
LINE OF LOOSELY ORGANIZED THUNDERSTORMS LOCATED FROM NORTHWESTERN
AR SOUTHWEST TO SOUTHEAST OK. 08Z /3AM/ SURFACE OBSERVATIONS
DEPICTED A COLD FRONT LOCATED NEAR A BOWIE TO PK LAKE TO COMANCHE
LINE MOVING SOUTHEAST. THE FWD 00Z RAOB INDICATED A SUBSTANTIAL
CAP IN PLACE OVER NORTH TX...AND THIS CAP WAS LIKELY RESPONSIBLE
FOR THE DEARTH OF PRECIPITATION ALONG THE PORTION OF THE FRONT IN
TEXAS EARLY THIS MORNING.
TODAY AND TONIGHT...GUIDANCE CONSISTENTLY INDICATES THAT THE
CYCLONIC CIRCULATION/UPPER LOW OVER THE KS/OK BORDER EARLY THIS
MORNING WILL DEEPEN INTO A CLOSED LOW WHILE MOVING EAST OVER THE
NEXT 24 HRS. THIS WILL CAUSE THE CYCLONIC SHEAR AXIS TO SWING
SOUTHEAST IN ITS WAKE OVER THE CWA LATE THIS AFTERNOON THROUGH THE
OVERNIGHT HRS. THE EVOLUTION OF THIS UPPER LEVEL SYSTEM WILL HAVE
SOME INTERESTING IMPACTS ON SURFACE FEATURES ACROSS NORTH AND
CENTRAL TX TODAY.
THE SURFACE LOW THAT WAS LOCATED JUST EAST OF WICHITA FALLS AT THE
TIME OF THIS DISCUSSION IS EXPECTED TO MOVE EAST NORTHEAST WITH
THE MAIN UPPER LOW OVER THE NEXT 24 HRS. THIS WILL CAUSE THE COLD
FRONT TO CONTINUE SOUTH ACROSS THE CWA THROUGH THIS AFTERNOON. AS
THE SURFACE LOW IS MOVING EAST ACROSS AR TODAY ANOTHER SURFACE LOW
IS EXPECTED TO DEVELOP OVER NORTHERN MEXICO TO THE WEST OF DEL RIO
IN RESPONSE TO THE CYCLONIC SHEAR AXIS MOVING SOUTHEAST. WITH A
NEW SURFACE LOW DEVELOPING TO THE SOUTHWEST...AND THE OTHER
SURFACE LOW MOVING OFF TO THE EAST...THE COLD FRONT WILL LIKELY
STALL OUT NEAR OR JUST SOUTHEAST OF A LINE FROM ATHENS TO WACO BY
THE MID-AFTERNOON HOURS.
OVERNIGHT MODELS ARE STILL NOT IN COMPLETE AGREEMENT AS TO WHERE
THE FRONT WILL COME TO A REST...BUT SOMEWHERE BETWEEN WACO AND
COLLEGE STATION IS THE CONSENSUS LOCATION. WHEREVER THE FRONT
STALLS...WITH LOW PRESSURE OFF TO THE NORTHEAST AND
SOUTHWEST...THE GENERAL LOW LEVEL WIND FIELD LOOKS TO BE
DOMINATED BY VERY WEAK DEFORMATION ON EITHER SIDE OF THE STALLED
FRONT THIS AFTERNOON. WEAK NORTHEAST WINDS NORTH OF THE FRONT AND
WEAK SOUTHWEST WINDS TO THE SOUTH WILL ACTUALLY MINIMIZE PURE
CONVERGENCE ALONG THE FRONT...MAKING IT VERY DIFFICULT TO
DETERMINE IF THE FRONT WILL BE AN IMPORTANT SOURCE OF LIFT THIS
AFTERNOON.
TEMPERATURES WILL GENERALLY BE WARMER SOUTHEAST OF THE
FRONT...BUT THE GULF MOISTURE IN PLACE WILL ACTUALLY SUPPORT
CLOUDIER CONDITIONS TO THE SOUTHEAST OF THE FRONT THIS AFTERNOON.
DRIER AIR TO THE NORTH COMBINED WITH SUBSIDENCE IN THE WAKE OF THE
DEPARTING UPPER LOW WILL CAUSE SKIES TO CLEAR OUT NORTH OF THE
FRONT. AFTERNOON SUNSHINE WILL WEAKEN THE TEMPERATURE GRADIENT
ALONG THE FRONT...REDUCING FRONTOGENETIC FORCING DURING THE PEAK
HEATING HRS OF THE DAY. AS A RESULT THINK MESOSCALE FORCING FOR
ASCENT ALONG THE FRONT WILL BE FAIRLY WEAK THIS AFTERNOON...
REDUCING CONFIDENCE IN CONVECTION INITIATION ALONG THE STALLED OUT
FRONT DURING THE PEAK HEATING HRS OF THE DAY.
AS A RESULT...BUMPED POPS DOWN A LITTLE BIT THRU SUNSET FOR
LOCATIONS ALONG AND SOUTH OF A LINE FROM COMANCHE TO CANTON.
GUIDANCE CONTINUES TO INDICATE THAT THERE WILL BE OVER 2000 J/KG
OF CAPE AVAILABLE FOR FREE CONVECTION IF STORMS CAN DEVELOP ALONG
THE FRONT. THEREFORE DESPITE THE LOW POPS...WILL CONTINUE TO
MENTION A CHANCE OF STRONG TO SEVERE STORMS AS ANYTHING THAT DOES
MANAGE TO DEVELOP WILL LIKELY BE QUITE STRONG THIS AFTERNOON.
DAMAGING WINDS AND LARGE HAIL WOULD BE THE MOST LIKELY HAZARDS IF
ANYTHING WERE ABLE TO DEVELOP ALONG THE FRONT THRU SUNSET.
TONIGHT...THE DRIER AIR TO THE NORTH WILL ACTUALLY HELP INCREASE
THE THERMAL GRADIENT ALONG THE STALLED OUT FRONT AS THIS AIR WILL
COOL MORE QUICKLY THAN THE CLOUDY AND MORE MOIST AIRMASS TO THE
SOUTH OF THE FRONT. AS A RESULT...EVEN THOUGH THIS SEEMS
COUNTER-INTUITIVE...OUR BEST CHANCES FOR STORMS ALONG THE FRONT MAY
BE WELL AFTER SUNSET TONIGHT. MODELS DO NOT REALLY INDICATE A BIG
INCREASE IN CONVERGENCE ALONG THE FRONT...BUT THE INCREASE IN THE
THERMAL GRADIENT WILL LEAD TO STRONGER MESOSCALE FORCING FOR
ASCENT. THIS COMBINED WITH THE MEAGER LARGE SCALE SUPPORT OFFERED
BY THE CYCLONIC SHEAR AXIS MOVING OVER THE REGION HAS CONFIDENCE A
BIT HIGHER IN STORMS ALONG THE FRONT AFTER SUNSET. AS A RESULT
WENT AHEAD AND BUMPED UP POPS FROM 00-12Z ALONG THE FRONT FOR
TONIGHT. SEVERE WEATHER CHANCES WILL NOT BE AS GREAT AFTER
SUNSET...HOWEVER LARGE HAIL IS STILL A POSSIBILITY WITH THE
STRONGEST STORMS. ANY STORMS THAT DEVELOP WILL LIKELY MOVE
PARALLEL TO THE FRONT...SO THERE IS A RISK FOR LOCALLY HEAVY
RAINFALL DUE TO THE POTENTIAL FOR STORMS TO TRAIN ALONG THE FRONT
TONIGHT. THAT SAID...POPS ARE ONLY IN THE 30 TO 40 PERCENT CHANCE
RANGE...SO IT IS STILL POSSIBLE THAT FORCING REMAINS TOO WEAK FOR
ANYTHING ALONG THE FRONT OVERNIGHT.
SUNDAY THROUGH TUESDAY...GUIDANCE INDICATES THAT WEAK UPPER LEVEL
RIDGING WILL BUILD OVER THE NORTHERN PORTIONS OF THE SOUTH PLAINS
DURING THE PERIOD WHICH SHOULD HELP KEEP US DRY. THE ECMWF
STUBBORNLY INDICATES THAT THE TAILING END OF THE CYCLONIC SHEAR
AXIS MOVING SOUTH OVER TX TONIGHT WILL BECOME ISOLATED FROM THE
DEPARTING UPPER LOW/SHEAR AXIS AND FORM A WEAK CUT-OFF UPPER LOW
OVER THE TX GULF COAST DURING THIS PERIOD. BASED ON THE ECMWFS
EVOLUTION AND TRACK OF THIS FEATURE...IT IS SOMEWHAT
INCONSEQUENTIAL TO NORTH AND CENTRAL TX AS WE WOULD REMAIN NORTH
OR NORTHWEST OF THIS UPPER LOW THRU THE PERIOD. THE ECMWF HAS BEEN
CONSISTENT WITH THIS FEATURE...SO CONFIDENCE IS HIGHER THAT IT
WILL DEVELOP...HOWEVER THIS SHOULD JUST REINFORCE RIDGING OVER THE
CWA INCREASING CONFIDENCE IN A DRY FORECAST FROM SUNDAY AFTERNOON
THRU TUESDAY. EVEN IF THE UPPER LOW DEVELOPS...IT IS EXPECTED TO
REMAIN TOO WEAK TO HAVE A LARGE IMPACT ON THE SURFACE PRESSURE
PATTERN...THEREFORE WE SHOULD REMAIN IN SOUTHERLY FLOW DUE TO LEE
SIDE TROUGHING IN RESPONSE TO A POWERFUL UPPER LOW EXPECTED TO
SWING INTO THE PLAINS MID-WEEK. SOUTH WINDS AND SUBSIDENCE ALOFT
SHOULD HELP US BRING TEMPERATURES UP INTO THE 80S DURING THIS
PERIOD.
MID-WEEK...MEDIUM RANGE GUIDANCE CONTINUES TO STRUGGLE ON THE
EXACT EVOLUTION OF THE POWERFUL SYSTEM PROGGED TO MOVE OVER THE
PLAINS WEDNESDAY OR WEDNESDAY NIGHT. ASIDE FROM THE FAIRLY LARGE
PLACEMENT DISCREPANCIES BETWEEN THE GFS AND CANADIAN/ECMWF ALL
GUIDANCE AGREES THAT THIS UPPER LEVEL SYSTEM WILL BE UNSEASONABLY
STRONG AND MAY LEAD TO AN EXTENDED PERIOD OF BELOW NORMAL
TEMPERATURES FOR NORTH TX FOR THE FIRST SEVERAL DAYS OF MAY. THIS
FORECAST IS MOST IN LINE WITH THE CONSENSUS OF THE ECMWF/CANADIAN
OPERATIONAL MODELS THAT WERE VALID AT 27/00Z. THESE MODELS BRING
THE INITIAL UPPER LEVEL LOW OVER THE SOUTH PLAINS DRIVING A STRONG
COLD FRONT SOUTH ACROSS NORTH TX LATE WEDNESDAY AFTERNOON THRU THE
OVERNIGHT HRS.
ASSUMING THE UPPER LOW DIGS AS FAR SOUTH AS THESE MODELS
INDICATE...ALMOST ALL OF THE CWA WILL SEE SOME RAIN/THUNDERSTORMS
ALONG THE COLD FRONT AS IT MOVES THROUGH. DID NOT GO CRAZY WITH
THE POPS YET BECAUSE THE GFS CONTINUES TO INDICATE THAT THE UPPER
LOW WILL REMAIN SIGNIFICANTLY FURTHER NORTH...REDUCING
PRECIPITATION CHANCES ALONG THE FRONT. WENT AHEAD WITH 40 POPS
ALONG AND BEHIND THE FRONT WITH THIS FORECAST...BUT POPS MAY NEED
TO BE MUCH HIGHER IF THE CMC/ECMWF TRACK VERIFIES. ITS TOO EARLY
TO DETERMINE SEVERE WEATHER CHANCES...HOWEVER A LARGE OUTBREAK
DOES NOT LOOK LIKELY BECAUSE THE FRONT IS EXPECTED TO MOVE SOUTH
VERY QUICKLY WEDNESDAY AFTERNOON UNDERCUTTING MOST ORGANIZED
CONVECTION THAT INITIATES JUST OUT AHEAD OF THE FRONT.
EXTENDED...THE ECMWF INDICATES THAT A BIG BLOCKING PATTERN SETS
UP AFTER THE UPPER LOW MOVES INTO THE PLAINS FOR THE END OF THE
WEEK. THIS KEEPS THE UPPER LOW IN PLACE OVER THE CENTRAL PLAINS
THRU AT LEAST MAY 5TH...WHICH WOULD TEND TO KEEP TEMPERATURES
BELOW NORMAL OVER MOST OF THE CENTRAL AND SOUTHERN PLAINS THRU THE
FIRST WEEK OF MAY. THE COLDEST TEMPERATURES WOULD BE RIGHT AFTER
THE COLD FRONT...WITH TEMPERATURES MODERATING THEREAFTER AS THE
UPPER LOW DRIFTS NORTH OF THE CWA. CONFIDENCE IN THIS SOLUTION IS
NOT GREAT...HOWEVER MOST GUIDANCE INDICATES SOME SORT OF BLOCKING
PATTERN FOR LATE IN THE WEEK INTO NEXT WEEKEND...SO THE MAIN
FORECAST CONCERN IS WHERE WILL THE UPPER LOW BE WHEN THE BLOCKING
PATTERN SETS UP. AT THIS TIME KEPT TEMPERATURES BELOW NORMAL
DURING THIS PERIOD AS THERE IS NO GUIDANCE THAT SHOWS WE GET STUCK
IN A BLOCKING PATTERN WITH UPPER LEVEL RIDGING OVER THE PLAINS.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 79 56 81 59 86 / 10 5 5 0 0
WACO, TX 83 60 81 57 85 / 20 30 10 0 0
PARIS, TX 78 52 79 52 82 / 10 5 5 0 0
DENTON, TX 77 53 81 55 86 / 10 5 5 0 0
MCKINNEY, TX 77 53 80 56 85 / 10 5 5 0 0
DALLAS, TX 80 56 83 61 86 / 10 10 5 0 0
TERRELL, TX 80 54 81 55 84 / 20 10 5 0 0
CORSICANA, TX 83 59 81 58 83 / 20 20 5 0 0
TEMPLE, TX 84 62 80 58 84 / 30 40 20 0 0
MINERAL WELLS, TX 80 54 83 56 85 / 10 5 5 0 0
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
84/58
AREA FORECAST DISCUSSION...UPDATED
NWS AUSTIN/SAN ANTONIO TX
631 AM CDT SAT APR 27 2013
.DISCUSSION...
SEE AVIATION FOR THE 12Z TAF DISCUSSION.
&&
.AVIATION...
THE PRIMARY CHALLENGE FOR THIS TAF PACKAGE IS THE TIMING OF THUNDERSTORMS
FOR THIS EVENING INTO EARLY TONIGHT. A WEAK FRONTAL BOUNDARY WILL FILTER
SOUTHWARD ACROSS THE HILL COUNTRY THIS EVENING BECOMING STATIONARY IN
THE VICINITY OF HIGHWAY 90 WHILE AN UPPER LEVEL IMPULSE MOVES EASTWARD
OUT OF MEXICO. THE FRONTAL BOUNDARY AND THE EASTERN SLOPES OF THE SIERRA
MADRE WILL BE THE FOCUS AREAS OF CONVECTIVE DEVELOPMENT. THE UPPER LEVEL
DISTURBANCE WILL HELP IN THE PROPAGATION OF CONVECTION TO THE EAST AND
SOUTHEAST OVERNIGHT. A BLEND OF THE 00Z ARW...07Z RUC13 AND 00Z TTU
3KM WRF WILL BE USED FOR TIMING OF THUNDERSTORMS IMPACTING THE TAF
SITES. OTHERWISE MVFR CIGS WILL PREVAIL THIS MORNING IMPROVING TO VFR
THIS AFTERNOON. CIGS WILL ONCE AGAIN LOWER TO MVFR AFTER 06Z...IFR BY
11Z. SFC WINDS TODAY S TO SE AT 5 TO 10 KTS...BACKING TO THE EAST AT
5 TO 8 KTS OVERNIGHT BECOMING L/V BY SUNDAY MORNING.
&&
.PREV DISCUSSION... /ISSUED 325 AM CDT SAT APR 27 2013/
SHORT TERM (TODAY THROUGH SUNDAY)...
INCREASING CHANCES FOR RAIN THIS WEEKEND AS A COLD FRONT SLIDES INTO
THE REGION. FOR TODAY...A CONTINUED SOUTHEAST INFLUX OF LOW LEVEL
MOISTURE WILL KEEP THE AREA POTENTIALLY UNSTABLE AS BOUNDARIES
APPROACH THE AREA. A MIXED LAYER CAP ALOFT WILL KEEP MUCH
CONVECTION FROM FIRING UNTIL AFTER DARK WHEN LOW LEVEL CONVERGENT
FORCES TAKE OVER (ALONG WITH SUPPORT ALOFT FROM A MID LEVEL JET).
HIGHS TODAY WILL BE IN THE 80S. WILL PLACE AT LEAST A SLIGHT
CHANCE OF THUNDERSTORMS OVER OUR NORTHERN CWA ALONG THE FRONT FOR
THIS AFTERNOON. THE COLD FRONT...LOCATED EARLY THIS MORNING OVER
THE TEXAS SOUTH PLAINS WILL SLIP SOUTH INTO OUR NORTHERN CWA BY
AFTERNOON. THE GFS MODEL SOLUTION STALLS THE FRONT OVER OVER
NORTHERN CWA DURING THE EVENING...THEN EDGES IT SOUTHWARD INTO THE
CENTRAL CWA OVERNIGHT. THIS IS SIGNIFICANT IN AS FAR AS RAINFALL
AND POTENTIALLY SEVERE WEATHER ARE CONCERNED AS BURRO MOUNTAIN
(MEXICAN PLATEAU) STORMS WHICH DEVELOP DURING THE LATE AFTERNOON/
EVENING HOURS PUSH EASTWARD AND INTERSECT THE FRONT DURING THE
OVERNIGHT HOURS OVER WESTERN SECTIONS. MOIST LOW LEVEL SOUTHEAST
FLOW (DEWPOINTS IN UPPER 60S) WILL MAINTAIN THESE STORMS AS THEY
TRAVERSE EAST...INTERSECTING THE FRONT AND ENHANCING RAIN AMOUNTS
AND SEVERITY OF STORMS. WILL INCLUDE A CHANCE OF SOME OF THE
STORMS BECOMING SEVERE TONIGHT OVER THE WESTERN HALF OF THE CWA
..WITH THE GREATEST THREAT BEING FROM LARGE HAIL. SOME DAMAGING
WIND GUSTS ARE ALSO POSSIBLE. ISOLATED RAIN AMOUNTS OF 1 TO 3
INCHES ARE EXPECTED ALONG THE TRACK OF THE BURRO STORMS AS THEY
INTERSECT THE FRONT OVER WESTERN SECTIONS TONIGHT. SOME
STABILIZATION IS EXPECTED SUNDAY AS THE FRONT AND RAIN-COOLED AIR
SETTLE OVER THE AREA. HOWEVER THERE REMAINS ENOUGH DYNAMICS AND
INSTABILITY ALOFT FOR SOME RE-DEVELOPMENT OF STORMS IN DAYTIME
HEATING. HIGHS SUNDAY IN THE UPPER 70S HILLS...NEAR 80 TO LOW 80S
ELSEWHERE.
LONG TERM (SUNDAY NIGHT THROUGH FRIDAY)...
AS FRONTOLYSIS (DISSIPATION OR WEAKENING OF A FRONT) OCCURS SUNDAY
NIGHT...SOUTHEAST FLOW AND LIFT OVER THE WEAKENING BOUNDARY MAY BE
ENOUGH FOR ADDITIONAL CONVECTION. IN FACT...ANOTHER THREAT FOR
BURRO DEVELOPMENT MAY OCCUR OVERNIGHT SUNDAY/EARLY MONDAY MORNING
AS MOIST SOUTHEAST FLOW UPLIFTS ACROSS THE MEXICAN PLATEAU AMID A
WEAK UPPER LEVEL SUBTROPICAL JET. THIS INSTABILITY AND UNSETTLED
WEATHER PATTERN WILL LINGER THROUGH TUESDAY AS A MOIST SOUTHEAST
FLOW AT THE SURFACE AND COOLING ALOFT COUPLED WITH DISTURBANCES
TRIGGER FURTHER ACTIVITY ESPECIALLY OVER SOUTHWEST PORTIONS OF THE
CWA. THE UPPER TROUGH WILL EXIT THE REGION WEDNESDAY WITH A STABLE
NORTHERLY FLOW ALOFT IN PLACE. A STRONG COLD FRONT WILL THEN PUSH
RAPIDLY THROUGH THE REGION WEDNESDAY NIGHT WITH LOW CHANCES OF
SHOWERS AND THUNDERSTORMS LINING THE FRONT. DECREASING CLOUDINESS
AND MUCH COOLER THURSDAY WITH HIGHS GENERALLY IN THE 70S. SURFACE
RIDGING WILL SETTLE OVER THE AREA THURSDAY NIGHT AND EARLY FRIDAY
WITH LOWS FRIDAY MORNING MOSTLY IN THE 40S. MOSTLY SUNNY FRIDAY
WITH HIGHS IN THE 70S.
&&
.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY 84 62 83 60 84 / 10 50 30 10 10
AUSTIN BERGSTROM INTL AIRPORT 84 61 82 57 83 / 10 50 30 20 10
NEW BRAUNFELS MUNI AIRPORT 85 61 83 58 83 / 10 60 40 20 20
BURNET MUNI AIRPORT 83 60 81 57 83 / 20 50 20 10 10
DEL RIO INTL AIRPORT 85 66 81 64 84 / 10 60 40 30 20
GEORGETOWN MUNI AIRPORT 82 61 81 58 82 / 20 50 20 10 10
HONDO MUNI AIRPORT 84 63 81 60 83 / 10 70 40 30 20
SAN MARCOS MUNI AIRPORT 83 62 82 58 82 / 10 50 30 20 20
LA GRANGE - FAYETTE REGIONAL 85 66 83 62 84 / 20 40 30 10 20
SAN ANTONIO INTL AIRPORT 83 63 81 60 82 / 10 60 40 30 20
STINSON MUNI AIRPORT 84 63 81 61 82 / 10 60 40 30 20
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE/AVIATION...13
SYNOPTIC/GRIDS...02
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
630 AM CDT SAT APR 27 2013
.AVIATION...
COLD FRONT IS KNOCKING ON THE METROPLEXS DOOR THIS MORNING. FRONT
IS THROUGH ALLIANCE...AND WILL BE THROUGH THE OTHER 4 SITES IN THE
METRO WITHIN THE NEXT HOUR. LOW CLOUDS HAVE BEEN SCATTERED AHEAD
OF THE FRONT...BUT REMAIN IN PLACE NEAR WACO WHERE THE BEST LOW-
LEVEL MOISTURE IS LOCATED. LOW CLOUDS ARE EXPECTED TO FILL IN
BEHIND THE COLD FRONT. WILL START THE METRO TAF SITES OFF WITH A
NORTHWEST WIND AND LOW MVFR CIGS...EXCEPT KDAL AND KGKY WHERE THE
FROPA IS EXPECTED CLOSER TO 1230Z. CURRENT EXTRAPOLATION HAS THE
FRONT REACHING WACO AROUND 17Z...BEFORE STALLING SOUTH OF THE
AIRPORT. WILL KEEP MVFR IN THE TAFS UNTIL 17Z FOR THE METRO AND
21Z FOR WACO. THIS TIMING IS CLOSE TO WHAT THE LATEST RAP IS
SHOWING. LOW CLOUDS DO NOT EXTEND TOO FAR WEST...AND CLEARING
SHOULD OCCUR EARLIER THAN PREVIOUSLY EXPECTED. CANT RULE OUT A
SHOWER OR THUNDERSTORM CLOSER TO THE FRONT NEAR WACO THIS
AFTERNOON...BUT PROBABILITIES ARE TOO LOW TO MENTION IN THE TAF AT
THIS TIME.
HAMPSHIRE
&&
.PREV DISCUSSION... /ISSUED 415 AM CDT SAT APR 27 2013/
EARLY MORNING WATER VAPOR IMAGERY DEPICTED A CYCLONIC CIRCULATION
CENTERED OVER SOUTH CENTRAL KS OR NORTH CENTRAL OK MOVING EAST.
THIS CIRCULATION WAS LOCATED ON THE EAST END OF A POSITIVELY
TILTED CYCLONIC SHEAR AXIS EXTENDING WSW OVER THE TX PANHANDLE AND
OVER WEST CENTRAL AZ. TO THE EAST OF THE KS/OK UPPER LOW WAS A
LINE OF LOOSELY ORGANIZED THUNDERSTORMS LOCATED FROM NORTHWESTERN
AR SOUTHWEST TO SOUTHEAST OK. 08Z /3AM/ SURFACE OBSERVATIONS
DEPICTED A COLD FRONT LOCATED NEAR A BOWIE TO PK LAKE TO COMANCHE
LINE MOVING SOUTHEAST. THE FWD 00Z RAOB INDICATED A SUBSTANTIAL
CAP IN PLACE OVER NORTH TX...AND THIS CAP WAS LIKELY RESPONSIBLE
FOR THE DEARTH OF PRECIPITATION ALONG THE PORTION OF THE FRONT IN
TEXAS EARLY THIS MORNING.
TODAY AND TONIGHT...GUIDANCE CONSISTENTLY INDICATES THAT THE
CYCLONIC CIRCULATION/UPPER LOW OVER THE KS/OK BORDER EARLY THIS
MORNING WILL DEEPEN INTO A CLOSED LOW WHILE MOVING EAST OVER THE
NEXT 24 HRS. THIS WILL CAUSE THE CYCLONIC SHEAR AXIS TO SWING
SOUTHEAST IN ITS WAKE OVER THE CWA LATE THIS AFTERNOON THROUGH THE
OVERNIGHT HRS. THE EVOLUTION OF THIS UPPER LEVEL SYSTEM WILL HAVE
SOME INTERESTING IMPACTS ON SURFACE FEATURES ACROSS NORTH AND
CENTRAL TX TODAY.
THE SURFACE LOW THAT WAS LOCATED JUST EAST OF WICHITA FALLS AT THE
TIME OF THIS DISCUSSION IS EXPECTED TO MOVE EAST NORTHEAST WITH
THE MAIN UPPER LOW OVER THE NEXT 24 HRS. THIS WILL CAUSE THE COLD
FRONT TO CONTINUE SOUTH ACROSS THE CWA THROUGH THIS AFTERNOON. AS
THE SURFACE LOW IS MOVING EAST ACROSS AR TODAY ANOTHER SURFACE LOW
IS EXPECTED TO DEVELOP OVER NORTHERN MEXICO TO THE WEST OF DEL RIO
IN RESPONSE TO THE CYCLONIC SHEAR AXIS MOVING SOUTHEAST. WITH A
NEW SURFACE LOW DEVELOPING TO THE SOUTHWEST...AND THE OTHER
SURFACE LOW MOVING OFF TO THE EAST...THE COLD FRONT WILL LIKELY
STALL OUT NEAR OR JUST SOUTHEAST OF A LINE FROM ATHENS TO WACO BY
THE MID-AFTERNOON HOURS.
OVERNIGHT MODELS ARE STILL NOT IN COMPLETE AGREEMENT AS TO WHERE
THE FRONT WILL COME TO A REST...BUT SOMEWHERE BETWEEN WACO AND
COLLEGE STATION IS THE CONSENSUS LOCATION. WHEREVER THE FRONT
STALLS...WITH LOW PRESSURE OFF TO THE NORTHEAST AND
SOUTHWEST...THE GENERAL LOW LEVEL WIND FIELD LOOKS TO BE
DOMINATED BY VERY WEAK DEFORMATION ON EITHER SIDE OF THE STALLED
FRONT THIS AFTERNOON. WEAK NORTHEAST WINDS NORTH OF THE FRONT AND
WEAK SOUTHWEST WINDS TO THE SOUTH WILL ACTUALLY MINIMIZE PURE
CONVERGENCE ALONG THE FRONT...MAKING IT VERY DIFFICULT TO
DETERMINE IF THE FRONT WILL BE AN IMPORTANT SOURCE OF LIFT THIS
AFTERNOON.
TEMPERATURES WILL GENERALLY BE WARMER SOUTHEAST OF THE
FRONT...BUT THE GULF MOISTURE IN PLACE WILL ACTUALLY SUPPORT
CLOUDIER CONDITIONS TO THE SOUTHEAST OF THE FRONT THIS AFTERNOON.
DRIER AIR TO THE NORTH COMBINED WITH SUBSIDENCE IN THE WAKE OF THE
DEPARTING UPPER LOW WILL CAUSE SKIES TO CLEAR OUT NORTH OF THE
FRONT. AFTERNOON SUNSHINE WILL WEAKEN THE TEMPERATURE GRADIENT
ALONG THE FRONT...REDUCING FRONTOGENETIC FORCING DURING THE PEAK
HEATING HRS OF THE DAY. AS A RESULT THINK MESOSCALE FORCING FOR
ASCENT ALONG THE FRONT WILL BE FAIRLY WEAK THIS AFTERNOON...
REDUCING CONFIDENCE IN CONVECTION INITIATION ALONG THE STALLED OUT
FRONT DURING THE PEAK HEATING HRS OF THE DAY.
AS A RESULT...BUMPED POPS DOWN A LITTLE BIT THRU SUNSET FOR
LOCATIONS ALONG AND SOUTH OF A LINE FROM COMANCHE TO CANTON.
GUIDANCE CONTINUES TO INDICATE THAT THERE WILL BE OVER 2000 J/KG
OF CAPE AVAILABLE FOR FREE CONVECTION IF STORMS CAN DEVELOP ALONG
THE FRONT. THEREFORE DESPITE THE LOW POPS...WILL CONTINUE TO
MENTION A CHANCE OF STRONG TO SEVERE STORMS AS ANYTHING THAT DOES
MANAGE TO DEVELOP WILL LIKELY BE QUITE STRONG THIS AFTERNOON.
DAMAGING WINDS AND LARGE HAIL WOULD BE THE MOST LIKELY HAZARDS IF
ANYTHING WERE ABLE TO DEVELOP ALONG THE FRONT THRU SUNSET.
TONIGHT...THE DRIER AIR TO THE NORTH WILL ACTUALLY HELP INCREASE
THE THERMAL GRADIENT ALONG THE STALLED OUT FRONT AS THIS AIR WILL
COOL MORE QUICKLY THAN THE CLOUDY AND MORE MOIST AIRMASS TO THE
SOUTH OF THE FRONT. AS A RESULT...EVEN THOUGH THIS SEEMS
COUNTER-INTUITIVE...OUR BEST CHANCES FOR STORMS ALONG THE FRONT MAY
BE WELL AFTER SUNSET TONIGHT. MODELS DO NOT REALLY INDICATE A BIG
INCREASE IN CONVERGENCE ALONG THE FRONT...BUT THE INCREASE IN THE
THERMAL GRADIENT WILL LEAD TO STRONGER MESOSCALE FORCING FOR
ASCENT. THIS COMBINED WITH THE MEAGER LARGE SCALE SUPPORT OFFERED
BY THE CYCLONIC SHEAR AXIS MOVING OVER THE REGION HAS CONFIDENCE A
BIT HIGHER IN STORMS ALONG THE FRONT AFTER SUNSET. AS A RESULT
WENT AHEAD AND BUMPED UP POPS FROM 00-12Z ALONG THE FRONT FOR
TONIGHT. SEVERE WEATHER CHANCES WILL NOT BE AS GREAT AFTER
SUNSET...HOWEVER LARGE HAIL IS STILL A POSSIBILITY WITH THE
STRONGEST STORMS. ANY STORMS THAT DEVELOP WILL LIKELY MOVE
PARALLEL TO THE FRONT...SO THERE IS A RISK FOR LOCALLY HEAVY
RAINFALL DUE TO THE POTENTIAL FOR STORMS TO TRAIN ALONG THE FRONT
TONIGHT. THAT SAID...POPS ARE ONLY IN THE 30 TO 40 PERCENT CHANCE
RANGE...SO IT IS STILL POSSIBLE THAT FORCING REMAINS TOO WEAK FOR
ANYTHING ALONG THE FRONT OVERNIGHT.
SUNDAY THROUGH TUESDAY...GUIDANCE INDICATES THAT WEAK UPPER LEVEL
RIDGING WILL BUILD OVER THE NORTHERN PORTIONS OF THE SOUTH PLAINS
DURING THE PERIOD WHICH SHOULD HELP KEEP US DRY. THE ECMWF
STUBBORNLY INDICATES THAT THE TAILING END OF THE CYCLONIC SHEAR
AXIS MOVING SOUTH OVER TX TONIGHT WILL BECOME ISOLATED FROM THE
DEPARTING UPPER LOW/SHEAR AXIS AND FORM A WEAK CUT-OFF UPPER LOW
OVER THE TX GULF COAST DURING THIS PERIOD. BASED ON THE ECMWFS
EVOLUTION AND TRACK OF THIS FEATURE...IT IS SOMEWHAT
INCONSEQUENTIAL TO NORTH AND CENTRAL TX AS WE WOULD REMAIN NORTH
OR NORTHWEST OF THIS UPPER LOW THRU THE PERIOD. THE ECMWF HAS BEEN
CONSISTENT WITH THIS FEATURE...SO CONFIDENCE IS HIGHER THAT IT
WILL DEVELOP...HOWEVER THIS SHOULD JUST REINFORCE RIDGING OVER THE
CWA INCREASING CONFIDENCE IN A DRY FORECAST FROM SUNDAY AFTERNOON
THRU TUESDAY. EVEN IF THE UPPER LOW DEVELOPS...IT IS EXPECTED TO
REMAIN TOO WEAK TO HAVE A LARGE IMPACT ON THE SURFACE PRESSURE
PATTERN...THEREFORE WE SHOULD REMAIN IN SOUTHERLY FLOW DUE TO LEE
SIDE TROUGHING IN RESPONSE TO A POWERFUL UPPER LOW EXPECTED TO
SWING INTO THE PLAINS MID-WEEK. SOUTH WINDS AND SUBSIDENCE ALOFT
SHOULD HELP US BRING TEMPERATURES UP INTO THE 80S DURING THIS
PERIOD.
MID-WEEK...MEDIUM RANGE GUIDANCE CONTINUES TO STRUGGLE ON THE
EXACT EVOLUTION OF THE POWERFUL SYSTEM PROGGED TO MOVE OVER THE
PLAINS WEDNESDAY OR WEDNESDAY NIGHT. ASIDE FROM THE FAIRLY LARGE
PLACEMENT DISCREPANCIES BETWEEN THE GFS AND CANADIAN/ECMWF ALL
GUIDANCE AGREES THAT THIS UPPER LEVEL SYSTEM WILL BE UNSEASONABLY
STRONG AND MAY LEAD TO AN EXTENDED PERIOD OF BELOW NORMAL
TEMPERATURES FOR NORTH TX FOR THE FIRST SEVERAL DAYS OF MAY. THIS
FORECAST IS MOST IN LINE WITH THE CONSENSUS OF THE ECMWF/CANADIAN
OPERATIONAL MODELS THAT WERE VALID AT 27/00Z. THESE MODELS BRING
THE INITIAL UPPER LEVEL LOW OVER THE SOUTH PLAINS DRIVING A STRONG
COLD FRONT SOUTH ACROSS NORTH TX LATE WEDNESDAY AFTERNOON THRU THE
OVERNIGHT HRS.
ASSUMING THE UPPER LOW DIGS AS FAR SOUTH AS THESE MODELS
INDICATE...ALMOST ALL OF THE CWA WILL SEE SOME RAIN/THUNDERSTORMS
ALONG THE COLD FRONT AS IT MOVES THROUGH. DID NOT GO CRAZY WITH
THE POPS YET BECAUSE THE GFS CONTINUES TO INDICATE THAT THE UPPER
LOW WILL REMAIN SIGNIFICANTLY FURTHER NORTH...REDUCING
PRECIPITATION CHANCES ALONG THE FRONT. WENT AHEAD WITH 40 POPS
ALONG AND BEHIND THE FRONT WITH THIS FORECAST...BUT POPS MAY NEED
TO BE MUCH HIGHER IF THE CMC/ECMWF TRACK VERIFIES. ITS TOO EARLY
TO DETERMINE SEVERE WEATHER CHANCES...HOWEVER A LARGE OUTBREAK
DOES NOT LOOK LIKELY BECAUSE THE FRONT IS EXPECTED TO MOVE SOUTH
VERY QUICKLY WEDNESDAY AFTERNOON UNDERCUTTING MOST ORGANIZED
CONVECTION THAT INITIATES JUST OUT AHEAD OF THE FRONT.
EXTENDED...THE ECMWF INDICATES THAT A BIG BLOCKING PATTERN SETS
UP AFTER THE UPPER LOW MOVES INTO THE PLAINS FOR THE END OF THE
WEEK. THIS KEEPS THE UPPER LOW IN PLACE OVER THE CENTRAL PLAINS
THRU AT LEAST MAY 5TH...WHICH WOULD TEND TO KEEP TEMPERATURES
BELOW NORMAL OVER MOST OF THE CENTRAL AND SOUTHERN PLAINS THRU THE
FIRST WEEK OF MAY. THE COLDEST TEMPERATURES WOULD BE RIGHT AFTER
THE COLD FRONT...WITH TEMPERATURES MODERATING THEREAFTER AS THE
UPPER LOW DRIFTS NORTH OF THE CWA. CONFIDENCE IN THIS SOLUTION IS
NOT GREAT...HOWEVER MOST GUIDANCE INDICATES SOME SORT OF BLOCKING
PATTERN FOR LATE IN THE WEEK INTO NEXT WEEKEND...SO THE MAIN
FORECAST CONCERN IS WHERE WILL THE UPPER LOW BE WHEN THE BLOCKING
PATTERN SETS UP. AT THIS TIME KEPT TEMPERATURES BELOW NORMAL
DURING THIS PERIOD AS THERE IS NO GUIDANCE THAT SHOWS WE GET STUCK
IN A BLOCKING PATTERN WITH UPPER LEVEL RIDGING OVER THE PLAINS.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 79 56 81 59 86 / 10 5 5 0 0
WACO, TX 83 60 81 57 85 / 20 30 10 0 0
PARIS, TX 78 52 79 52 82 / 30 5 5 0 0
DENTON, TX 77 53 81 55 86 / 10 5 5 0 0
MCKINNEY, TX 77 53 80 56 85 / 10 5 5 0 0
DALLAS, TX 80 56 83 61 86 / 10 10 5 0 0
TERRELL, TX 80 54 81 55 84 / 10 10 5 0 0
CORSICANA, TX 83 59 81 58 83 / 20 20 5 0 0
TEMPLE, TX 84 62 80 58 84 / 30 40 20 0 0
MINERAL WELLS, TX 80 54 83 56 85 / 10 5 5 0 0
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
85/85
AREA FORECAST DISCUSSION...UPDATED
NWS LITTLE ROCK AR
1207 PM CDT SAT APR 27 2013
.DISCUSSION...
UPDATED TO INCLUDE THE 18Z AVIATION DISCUSSION BELOW...
&&
.AVIATION...
WEAK SFC LOW PRESSURE WILL CONTINUE MOVING ACROSS THE STATE
THROUGH THIS AFTERNOON...WITH CHANCES FOR SHRA/TSRA PERSISTING FOR
MOST SITES THROUGH THE AFTERNOON HRS. MANY SITES HAVE CONTINUED
WITH MVFR TO LIFR CIGS/VIS THIS MORNING WHERE WINDS WERE LIGHT AND
WHERE PRECIP HAD BEEN OBSERVED. THE EXCEPTION BEING THE SRN SITES
WHERE RECENTLY VFR CONDITIONS HAD DEVELOPED AS RESULT OF STRONGER
SRLY WINDS AND LACK OF PRECIP. AFTER THIS SFC LOW EXITS THE STATE
TO THE EAST TONIGHT...WEST AND NW WINDS WILL BE SEEN...BUT REMAIN
FAIRLY LIGHT. AS A RESULT...WILL LIKELY SEE SOME FOG DEVELOP
DURING THE OVERNIGHT HRS...WITH IFR TO EVEN LIFR CONDITIONS
POSSIBLE. IMPROVING CONDITIONS WILL THEN BE SEEN LATER ON SUN.
&&
PREV DISCUSSION... /ISSUED 349 AM CDT SAT APR 27 2013/
SHORT TERM...TODAY THROUGH TUESDAY NIGHT
UNSETTLED CONDITIONS ARE EXPECTED FOR THE FIRST BACK OF THE
WEEKEND BUT THE SECOND HALF APPEARS TO BE MUCH BETTER AT THIS
POINT. GFS SOLUTION HAS BEEN THE MOST CONSISTENT MODEL OF LATE IN
THE SYNOPTIC SCALE AND SEE NO REAL REASON TO STRAY FROM IT AT THIS
POINT.
SHORTWAVE TROUGH...CLEARLY EVIDENT ON MOISTURE CHANNEL IMAGERY THIS
MORNING...EXTENDS FROM EASTERN KANSAS DOWN TO THE TEXAS PANHANDLE.
FEATURE IS EXPECTED TO MOVE TO THE EAST OVER THE NEXT 24 HOURS OR SO
WITH A WEAK H5 LOW DEVELOPING AS IT DOES. ON THE SURFACE...LATEST
ANALYSIS PLACES A WEAK WARM FRONT ALONG THE ARKANSAS/LOUISIANA
BORDER ANCHORED BY WEAK LOW PRESSURE ALONG THE RED RIVER. THIS
FEATURE APPEARS TO BE STARTING TO MOVE TOWARDS THE NORTH.
RADAR IMAGERY ACROSS THE REGION SHOWS ONGOING...SCATTERED SHOWER
ACTIVITY ACROSS THE STATE THAT IS LIKELY BEING GENERATED IN AN AREA
OF ASCENT ASSOCIATED WITH THE LOW LEVEL JET. CONVECTIVE COMPLEX
OVER EASTERN OKLAHOMA/WESTERN ARKANSAS HAS BEEN STEADILY WEAKENING
WITH TIME. THE AFOREMENTIONED TROUGH WILL PUSH SLOWLY EAST TODAY AS
FRONTAL SYSTEM LIFTS TO THE NORTH WITH WIDESPREAD SHOWER AND
THUNDERSTORM ACTIVITY CONTINUING.
BEST CHANCES OF PRECIPITATION LOOK TO BE EARLY IN THE DAY WITH
CHANCES DECREASING DURING THE DAY AS SYSTEM LIFTS THROUGH. BEST
CHANCES WILL THEN BE CONFINED TO THE TRAILING COLD FRONT AND THERE
REMAINS A CHANCE OF SOME STRONGER CONVECTION OVER THE SOUTHEAST PART
OF THE STATE. WILL HOLD ONTO LINGERING PRECIPITATION CHANCES
EARLY ON SUNDAY BEFORE ENDING THE RAINFALL ENTIRELY.
QPF FORECASTS ALL OVER PLACE THIS MORNING BUT HRRR MODEL ACTUALLY
SEEMS TO HAVE THE BEST HANDLE ON THE SYSTEM. AS SUCH...WILL FOLLOW
ITS TRENDS CONCERNING PRECIPITATION COVERAGE AND WILL TRIM BACK THE
AMOUNTS. WILL BLEND ECMWF/MAV NUMBERS FOR TEMPERATURES.
REMAINDER OF THE SHORT TERM PERIOD LOOKS RATHER EVENTFUL AS SURFACE
HIGH PRESSURE MOVES ACROSS AND EVENTUALLY EAST OF THE FORECAST AREA.
SOUTHERLY SURFACE WINDS AND A RATHER NONDESCRIPT UPPER FLOW WILL
ALLOW TEMPERATURES TO GET ABOVE NORMALS FOR LATE APRIL/EARLY MAY.
NEXT SYSTEM WILL BEGIN TO DROP DOWN INTO THE CENTRAL PLAINS LATE BUT
ITS IMPACTS WILL LIKELY BE FELT IN THE EXTENDED PERIOD.
LONG TERM...WEDNESDAY THROUGH FRIDAY...
AN UPPER TROUGH WILL BE OVER THE NORTHERN PLAINS TO BEGIN THE
PERIOD WITH A RIDGE OVER THE EASTERN U.S. THE UPPER TROUGH WILL
DEEPEN THROUGH THE SOUTHERN PLAINS WEDNESDAY NIGHT AND THURSDAY.
BY FRIDAY IT BECOMES A CLOSED LOW OVER THE OHIO RIVER VALLEY
PROVIDING NORTHWEST FLOW TO ARKANSAS.
A COLD FRONT WILL MOVE THROUGH ARKANSAS WEDNESDAY. MOISTURE WILL
STREAM NORTH OUT OF THE GULF OF MEXICO. CHANCES OF SHOWERS AND
THUNDERSTORMS WILL INCREASE THROUGH WEDNESDAY...REACH THEIR PEAK
WEDNESDAY NIGHT...AND END THURSDAY MORNING. HIGH PRESSURE WILL BUILD
OVER THE AREA THURSDAY AND FRIDAY. MUCH COOLER AND DRIER AIR WILL BE
USHERED IN WITH THIS COLD HIGH PRESSURE SYSTEM. ABOVE NORMAL
TEMPERATURES ARE EXPECTED WEDNESDAY AND MUCH BELOW NORMAL FOR
THURSDAY AND FRIDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
BATESVILLE AR 70 52 72 52 / 80 40 20 10
CAMDEN AR 78 57 77 51 / 60 30 10 10
HARRISON AR 65 49 72 51 / 80 20 10 10
HOT SPRINGS AR 74 54 76 52 / 60 20 10 10
LITTLE ROCK AR 74 55 75 54 / 70 30 10 10
MONTICELLO AR 79 59 76 54 / 80 40 20 10
MOUNT IDA AR 73 52 76 51 / 60 20 10 10
MOUNTAIN HOME AR 66 50 72 51 / 80 30 10 10
NEWPORT AR 71 54 72 52 / 80 40 20 10
PINE BLUFF AR 77 57 76 54 / 70 40 20 10
RUSSELLVILLE AR 70 51 74 53 / 70 20 10 10
SEARCY AR 72 54 73 53 / 80 40 20 10
STUTTGART AR 75 56 75 54 / 80 40 20 10
&&
.LZK WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AVIATION...62
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
121 PM EDT SAT APR 27 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 326 AM EDT SAT APR 27 2013
SURFACE AND UPPER LOWS WILL MOVE THROUGH CENTRAL INDIANA THIS
WEEKEND BRINGING SHOWERS AND PERHAPS A FEW THUNDERSTORMS TO THE
AREA. DRY WEATHER WILL THEN MOVE IN FOR MUCH OF THE EARLY PART OF
THE WORK WEEK...BUT A COLD FRONT WILL BRING RETURNING CHANCES FOR
RAIN FROM MID TO LATE WEEK NEXT WEEK.
TEMPERATURES WILL GRADUALLY WARM TO ABOVE AVERAGE BY MID WEEK...THEN
FALL TO BELOW AVERAGE BY THE END OF THE WEEK.
&&
.NEAR TERM /THIS AFTERNOON/...
ISSUED AT 1024 AM EDT SAT APR 27 2013
CLOUD SHIELD EXPANDING NORTH THIS MORNING WITH LARGE AREA OF RAIN
APPROACHING FROM THE SOUTHWEST. TEMPS HAD WARMED INTO THE 50S
ACROSS THE FORECAST AREA AT 14Z WITH WARMEST TEMPS OVER NORTHEAST
COUNTIES WHERE SKIES WERE MOSTLY SUNNY.
MAIN CHANGE FOR THE UPDATE IS TO DELAY ONSET OF THE RAINFALL BY
3-4 HOURS ACROSS MUCH OF THE FORECAST AREA LATER TODAY AS DRIER AIR
THROUGH THE LOW LEVELS REMAINS PRESENT. HAVE SEEN A FEW SPRINKLES
INTO THE LOWER WABASH VALLEY ALREADY THIS MORNING BUT MUCH OF THIS
ACTIVITY IS DIMINISHING A IT MOVES NORTHEAST AND RUNS INTO AN
INCREASING DRIER AIRMASS. CURRENT RAP INDICATING DEEPER ISENTROPIC
LIFT REALLY HOLDS OFF ACROSS CENTRAL INDIANA UNTIL AFTER 18Z AND
FOR THE NORTHERN HALF OF THE FORECAST AREA UNTIL BETWEEN 21Z AND
00Z. CONSIDERING THE DEPTH OF THE DRY AIR PRESENT...THE SURGE OF
ISENTROPIC LIFT WILL BE NEEDED TO SATURATE THE LOW LEVELS AND
ENABLE PRECIP SHIELD TO EXPAND NORTH. HAVE THEREFORE SLOWED DOWN
ARRIVAL OF RAINFALL BY A FEW HOURS...WITH MANY AREAS NORTH OF I-70
REMAINING DRY UNTIL AFTER 21-22Z. LEFT FORECAST HIGHS ALONE FOR
THE AFTERNOON WITH THE EXCEPTION OF THE FAR NORTHERN COUNTIES
WHERE SUNSHINE WILL CONTINUE FOR THE NEXT FEW HOURS AND MAY ENABLE
LOCATIONS LIKE KOKOMO AND MUNCIE TO MAKE A RUN AT 70 LATER TODAY.
ZONE AND GRID UPDATES OUT.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
ISSUED AT 326 AM EDT SAT APR 27 2013
FOCUS CONTINUES TO BE ON CHANCES FOR RAIN THROUGH THE PERIOD. MODELS
ARE CLOSE ENOUGH THAT A BLEND CAN BE USED FOR MOST ITEMS.
Q-VECTOR FORECAST PLOTS SHOW THE FORCING MOVING INTO THE AREA
TONIGHT ASSOCIATED WITH AN UPPER LOW MOVING INTO THE AREA...SO
GRADUALLY INCREASED POPS ACROSS THE FORECAST AREA TONIGHT. WENT
CLOSE TO MOS POPS WITH LIKELY NORTH AND CATEGORICAL SOUTH.
ON SUNDAY THE SURFACE AND UPPER LOWS WILL MOVE THROUGH THE AREA. MOS
POPS ARE HIGH...BUT MODELS ARE ONLY SHOWING RELATIVELY WEAK FORCING.
FORECAST REFLECTIVITY ALSO SHOWS MORE OF A SCATTERED COVERAGE THAN
WIDESPREAD AT ANY ONE TIME. HOWEVER WITH THE LOWS MOVING THROUGH
CANNOT REALLY ARGUE AGAINST THE HIGH POPS SINCE MOST AREAS COULD SEE
A HUNDREDTH OF AN INCH IN A PASSING SHOWER. WITH THE HIGH POPS WILL
USE OCCASIONAL WORDING TO HIGHLIGHT DRY PERIODS DURING THE
DAY.
SOME INSTABILITY MOVES IN WITH THE SURFACE LOW SO MENTIONED ISOLATED
THUNDERSTORMS SUNDAY.
WENT LOW POPS SUNDAY EVENING AS MODELS CONTINUE TO HINT AT LINGERING
PRECIPITATION. FOR OVERNIGHT SUNDAY NIGHT INTO MONDAY WENT SLIGHT
CHANCE POPS ACROSS THE EAST FOR THE SAME REASON.
FOR TEMPERATURES THROUGH THE FIRST HALF OF THE PERIOD...GENERALLY
WENT WITH THE COOLER OF THE MOS DURING THE DAY AND THE WARMER OF THE
MOS DURING THE NIGHT DUE TO CLOUDS AND RAINFALL. GENERALLY STUCK
WITH A BLEND FOR THE SECOND HALF.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
ISSUED AT 300 AM EDT SAT APR 27 2013
MODEL TIMING DIFFERENCES REGARDING AN UPPER LOW AND UPSTREAM FRONTAL
SYSTEM WILL CONTINUE TO BE THE MAIN ISSUE IN THE EXTENDED ESPECIALLY
LATE WEEK.
THE 00Z GFS AND GEFS CONTINUE TO BE MUCH FASTER AND WEAKER WITH THE
AFOREMENTIONED UPPER SYSTEM. BY 00Z FRIDAY...THE 12Z ECMWF HAS A
DEEP UPPER LOW ACROSS NORTHEASTERN NEBRASKA...WHILE THE 00Z GFS AND
GEFS HAVE A WEAKER OPEN TROUGH ACROSS EASTERN MISSOURI AND FINALLY
THE 00Z GEM HAS AN UPPER LOW FORMING WITHIN THE TROUGH ACROSS
NORTHERN TEXAS. MEANWHILE...THE GFS AND GEFS WERE MUCH FASTER WITH
THE LEAD FRONT WITH THE ECMWF AND TO A LESSER EXTENT EURO LAGGING
WELL TO THE WEST. THE GEFS AND GFS HAVE THE FRONT ACROSS OHIO...THE
GEM ACROSS EASTERN INDIANA AND EURO ACROSS WESTERN INDIANA AT THAT
TIME. THIS RESULTS IN QUICKER MOISTURE RETURN AND QPF FROM THE GFS
AND GEFS. THE GFS AND GEFS HAS DECENT QPF BY WEDNESDAY NIGHT...WHILE
THE OTHER LONG RANGE MODELS HOLD OFF TIL WEDNESDAY.
WITH A STRONG RIDGING ACROSS THE EASTERN SEABOARD AS WELL AS THE
WEST...PREFER THE SLOWER ECMWF BUT WILL ALLOW FOR SMALL POPS OF THE
REGIONAL INITIALIZATION ON WEDNESDAY IN THE SMALL CHANCE THE GFS
VERIFIES OR THE EURO AND GEM SPEED UP A LITTLE BIT IN LATER RUNS.
ALL MODELS HAVE DECENT QPF ON THURSDAY AND HOLD ON TO IT ALSO FRIDAY
WHICH IS REFLECTED IN CONTINUED REGIONAL INITIALIZATION POPS.
AGAIN WITH LOW CONFIDENCE FROM MODEL DIFFERENCES...WILL ACCEPT THE
REGIONAL TEMPERATURES WHICH HAVE HIGHS IN THE 70S THROUGH WEDNESDAY
AND THEN PROGRESSIVELY COOLER NUMBERS IN THE 60S ON THURSDAY AND 50S
BY FRIDAY AS COLD FRONT SLIDES TO THE EAST.
&&
.AVIATION /DISCUSSION FOR THE 27/1800Z TAF ISSUANCE/...
ISSUED AT 112 PM EDT SAT APR 27 2013
DELAYED ONSET OF RAIN ACROSS TAF SITES THIS AFTERNOON WITH THE BULK OF
PRECIP NOT ENTERING UNTIL LATE AFTERNOON/EARLY EVENING AT KIND/KLAF/KBMG.
THE EXCEPTION WILL BE KHUF WHICH COULD SEE LIGHT RAIN WITHIN THE
NEXT 1 TO 2 HOURS. VFR CONDITIONS WILL PREVAIL UP UNTIL THAT POINT...
BUT CONDITIONS WILL QUICKLY FALL TO MVFR CATEGORY WITH ONSET OF
RAIN...AND CONTINUE TO DETERIORATE FURTHER TONIGHT AS CEILINGS
FALL AND FOG FORMS. IFR/LIFR CATEGORY WILL BE POSSIBLE AS EARLY AS
SUN 00Z. EXPECT MVFR CONDITIONS TO RETURN AROUND MID-MORNING
TOMORROW AT MOST TAF SITES AS RAIN TAPERS OFF. WINDS WILL BE
SOUTHEASTERLY FOR THE MAJORITY OF TAF PERIOD WITH SUSTAINED SPEEDS
OF 6 TO 12 KTS...AND THEN VEER TO THE SOUTHWEST LATE TOMORROW
MORNING.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...50
NEAR TERM...RYAN
SHORT TERM...50
LONG TERM....MK
AVIATION...TDUD
AREA FORECAST DISCUSSION
NWS WICHITA KS
1222 PM CDT SAT APR 27 2013
.SYNOPSIS...
ISSUED AT 337 AM CDT SAT APR 27 2013
SCATTERED SHOWERS AND DRIZZLE ARE SLOWLY MAKING THEIR WAY EASTWARD
AS THE UPPER LEVEL SYSTEM MOVES ACROSS THE PLAINS. WHERE CLOUDS
HAVE THINNED OR CLEARED OUT...DENSE FOG HAS DEVELOPED ACROSS
WESTERN AND NORTHERN KANSAS. WINDS HAVE BECOME NORTH TO
NORTHEASTERLY AND ARE LIGHT.
BILLINGS
&&
.UPDATE...
ISSUED AT 1220 PM CDT SAT APR 27 2013
THE CLOUDS HAVE FINALLY STARTED TO ABATE OVER THE WESTERN PART OF
THE FORECAST AREA. CENTRAL KANSAS OVER THE LAST COUPLE OF HOURS
HAS SEEN A SIGNIFICANT REDUCTION OF CLOUDS. MOREOVER...THE
PRECIPITATION OVER EASTERN KANSAS HAS BEEN RELEGATED TO A FEW
SPRINKLES.
THE LAST FEW RUNS OF THE HRRR AND RUC ARE ON TRACK WITH THESE
TRENDS. HAVE ADJUSTED TEMPERATURES TO INDICATED A QUICK WARM UP
THIS AFTERNOON ONCE THE CLOUDS CLEAR. THE MAIN PROBLEM IS
REALLY OVER SOUTHEAST KANSAS AND HOW LONG THE CLOUDS WILL BE
THERE...WHICH WILL AFFECT HIGHS. WILL KEEP HIGHS NEAR 60 THERE FOR
NOW.
FINALLY...THE HRRR HAS CONSISTENTLY INDICATED WEAK CONVECTIVE
DEVELOPMENT FROM THE UPPER LEVEL COLD POOL. THAT COULD BE ENTIRELY
POSSIBLE...BUT AT THIS TIME HAVE REDUCED PRECIPITATION CHANCES AND
JUST STUCK WITH SOME SPRINKLES...WHICH I THINK BETTER INDICATES
WHAT IS EXPECTED.
COOK
UPDATE ISSUED AT 616 AM CDT SAT APR 27 2013
UPDATED THE AVIATION SECTION BELOW FOR THE 12Z TAFS.
&&
.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 337 AM CDT SAT APR 27 2013
THE UPPER LEVEL SYSTEM WILL SLOWLY CONTINUE TO MOVE OUT OF THE
AREA TODAY. EXPECTING SHOWERS AND DRIZZLE TO LINGER ACROSS
SOUTHEASTERN KANSAS THROUGH PART OF THE MORNING. SKIES WILL CLEAR
OUT FROM WEST TO EAST...AND TEMPERATURES WILL RETURN TO NEAR NORMAL.
HOWEVER...TEMPS WILL BE SLIGHTLY COOLER WHERE CLOUDS LINGER
THROUGH PART OF THE DAY. ANOTHER BRIEF WAVE WILL QUICKLY MOVE
ACROSS THE CENTRAL PLAINS...BUT DO LITTLE TO THE SURFACE PATTERN
OVER THE AREA. TEMPERATURES ON SUNDAY AND MONDAY WILL BE IN THE
LOW 80S WITH SOUTHERLY WINDS.
BILLINGS
.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 337 AM CDT SAT APR 27 2013
THIS PERIOD IS THE ONE TO WATCH. THE GUIDANCE HAS CONTINUED TO
SHOW AN UPPER WAVE BEING CUT OFF FROM THE MAIN FLOW AND ROTATING
AROUND THE MIDDLE OF THE COUNTRY FOR THURSDAY AND FRIDAY. WHILE THE
GUIDANCE HAS BEEN CONSISTENT IN SHOWING THIS SOLUTION...THEY DO
DIFFER ON TIMING AND PLACEMENT OF THE WAVE/CUT-OFF LOW. THE GFS
AND ECMWF ARE FAIRLY CONSISTENT WITH THE STRONG COLD FRONT MOVING
THROUGH THE REGION ON WEDNESDAY NIGHT/THURSDAY MORNING...BUT THE
GFS BECOMES MORE PROGRESSIVE WITH THE WAVE AS IT PUSHES THE FRONT
THROUGH TO THE OHIO VALLEY...WHILE THE ECMWF KEEPS THE CUT-OFF
LOW OVER THE CENTRAL/SOUTHERN PLAINS.
THESE DISCREPANCIES DO HAVE LARGE IMPACT ON THE FORECAST...WITH
THE GFS KEEPING MOST OF THE PRECIPITATION OVER THE OHIO VALLEY
WHILE THE ECMWF KEEPS THE COOL AIR AND PRECIPITATION OVER KANSAS.
MUCH LIKE THE PREVIOUS FORECAST...THE CONSENSUS WEIGHS MORE
HEAVILY ON THE GFS SOLUTION THAN THE ECMWF...SO IT HAS
PRECIPITATION EXITING THE AREA ON THURSDAY...HOWEVER...IF THE
ECMWF REMAINS CONSISTENT OVER THE NEXT FEW DAYS THE END OF THE
WEEK AND INTO THE WEEKEND NEXT WEEK (BEYOND THE PERIOD) WILL BE
COOL AND RAINY.
BILLINGS
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1220 PM CDT SAT APR 27 2013
THE FOG IS MORE OR LESS GONE ACROSS THE AREA...WITH VERY LITTLE
PRECIPITATION. BKN010 CLOUDS MAINLY ALONG AND EAST OF THE KANSAS
TURNPIKE WILL GRADUALLY MOVE EAST. IT SHOULD BE OUT OF
KICT/KHUT/KSLN BY 27.19Z AND OUT OF KCNU BEFORE 28.00Z.
FOG IS EXPECTED TO REDEVELOP AROUND 28.08Z AND LAST THROUGH 28.13Z
AT ALL STATIONS WITH THE EXCEPTION OF KRSL...WHERE THE RIDGE OF
HIGH PRESSURE MOVING IN MAY LIMIT THE FOG DEVELOPMENT.
COOK
&&
.FIRE WEATHER...
ISSUED AT 337 AM CDT SAT APR 27 2013
DESPITE THE WARM TEMPERATURES...THE LIGHT WINDS EXPECTED OVER THE
NEXT COUPLE OF DAYS WILL KEEP GRASSLAND FIRE DANGER LOW.
HOWEVER...VERY HIGH FIRE DANGER IS POSSIBLE TUESDAY WITH GUSTY
SOUTHWEST WINDS AND WARM TEMPERATURES AHEAD OF THE COLD FRONT.
AFTER THE FRONT PASSES...TEMPERATURES WILL COOL AND PRECIPITATION
WILL KEEP FIRE WEATHER CONCERNS AT BAY.
BILLINGS
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 67 49 81 55 / 20 10 0 0
HUTCHINSON 68 47 82 55 / 10 10 0 0
NEWTON 67 49 80 56 / 30 10 0 0
ELDORADO 66 47 79 55 / 50 10 0 0
WINFIELD-KWLD 68 48 80 56 / 30 10 0 0
RUSSELL 71 47 83 53 / 10 0 0 0
GREAT BEND 72 47 84 54 / 10 0 0 0
SALINA 67 47 82 55 / 10 10 0 0
MCPHERSON 67 47 82 55 / 10 10 0 0
COFFEYVILLE 60 46 77 55 / 60 10 0 0
CHANUTE 60 45 76 54 / 60 10 0 0
IOLA 60 45 76 54 / 60 10 0 0
PARSONS-KPPF 60 46 77 55 / 60 10 0 0
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
121 PM CDT SAT APR 27 2013
.UPDATE...
ISSUED AT 1001 AM CDT SAT APR 27 2013
MADE SOME UPDATES TO THE FORECAST TODAY...PRIMARILY TO INCREASE
POPS AND LOWER TEMPERATURES A BIT STRETCHING FROM CENTRAL MISSOURI
THROUGH SOUTHWEST ILLINOIS. UPPER LEVEL LOW IS MOVING SLOWLY INTO
WESTERN MISSOURI AND A BROAD AREA OF LIGHT RAIN EXTENDS FROM
SPRINGFIELD MISSOURI UP THROUGH CENTRAL AND EASTERN MISSOURI INTO
SOUTHWEST ILLINOIS. LATEST HRRR GUIDANCE SUGGESTS THIS WILL
PERSIST THROUGH THE DAY AS THE LOW CONTINUES DRIFTING EAST.
CARNEY
&&
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 320 AM CDT SAT APR 27 2013
THE PRIMARY FCST ISSUE FOR TODAY IS PCPN CHCS/COVERAGE ASSOCIATED
WITH A VORT MAX THAT IS SLOWLY PROGRESSING EWD FM OK/KS TOWARDS
MO/IL. THE SFC REFLECTION OF THIS FEATURE IS EXPECTED TO REMAIN
GENERALLY SOUTH OF THE CWA AS IT LIFTS FM OK THROUGH AR INTO SERN
MO. ALTHOUGH THE SFC LOW WILL LIFT A WMFNT NEWD INTO SRN MO...THE
FRONT IS EXPECTED TO REMAIN SOUTH OF THE CWA THEREFORE TEMPERATURES
WILL BE GOVERNED BY CLOUD COVER AND LIMITED DIURNAL HEATING RATHER
THAN BY ADVECTION.
THERE WERE THREE DISTINCT AREAS OF PCPN OCCURRING ACROSS THE REGION
EARLY THIS MORNING. FIRST...A CONVECTIVE COMPLEX WAS MOVING THROUGH
OK INTO WRN AR AT 08Z. THIS COMPLEX WILL REMAIN SOUTH OF THE CWA.
SECOND...A BROKEN AREA OF SHRA WITH ISO TSRA WAS LOCATED OVER SERN
MO AND WAS MOVING INTO SRN IL AND WRN KY. THIS AREA OF PCPN APPEARS
TO BE FORCED BY LLJ MCONV AND WILL CONTINUE TO AFFECT THE SERN PART
OF THE CWA FOR THE NEXT SEVERAL HOURS UNTIL THE LLJ DIMINISHES.
THIRD...A DEFORMATION ZONE HAS DVLPD ACROSS CENTRAL AND ERN KS AS
WELL AS NWRN MO. AS THE UPPER LOW SHIFTS SLOWLY EWD TODAY SO WILL
THE DEFORMATION ZONE AND ITS PCPN. THERE MAY ALSO BE SOME DIURNAL
ENHANCEMENT OF PCPN COVERAGE. NO MODEL IS HANDLING THE DEFORMATION
ZONE VERY WELL THIS MORNING THEREFORE POPS FOR TODAY ARE BASED ON
THE POSITION OF THE CURRENT DEFORMATION ZONE AND THE FCST POSITION
OF THE CLOSED H5 LOW BY 00Z. IN A DEPARTURE FROM THE PREVIOUS
FCST...PCPN IS NOW EXPECTED TO AFFECT THE MIDDLE AND NRN HALF OF THE
CWA MORE THAN THE SRN HALF.
KANOFSKY
.LONG TERM...(TONIGHT THROUGH FRIDAY)
ISSUED AT 320 AM CDT SAT APR 27 2013
(TONIGHT - SUNDAY)
A LARGELY NEUTRAL LONGWAVE PATTERN OVER NOAM WILL BEGIN TO
TRANSITION TOWARDS A LONGWAVE RIDGE IN THE E AND A TROF IN THE W
LATER ON SUNDAY. THE MOST PROMINENT FEATURE OF THIS PERIOD WILL BE
THE SYSTEM CENTERED OVER SERN KS CONTINUING TO SLOWLY WORK ITS WAY
THRU OUR REGION...AND SLOWLY IT WILL GO. MODELS HAVE TRENDED ABOUT
6-12 HRS SLOWER WITH THE EWD PROGRESSION OF THIS SYSTEM FROM 24HRS
AGO AND SO HAVING IT ONLY MAKE IT THRU ABOUT TWO-THIRDS THRU THE FA
BY SUNDAY/12Z WITH IT FINALLY EXITING WITH MOST OF ITS DYNAMICS BY
18Z. MAIN DYNAMICS WITH THIS SYSTEM...SINCE IT CLOSED OFF EARLIER
TONIGHT...WILL BE ITS ABILITY NOW TO PRODUCE DEFORMATION ZONE PCPN
FOR AREAS FARTHER N. THIS PCPN SHOULD BE FURTHER ENHANCED DIURNALLY
BY COLD CORE NATURE OF LO ALOFT AND WILL LIKELY SEE THESE EFFECTS
EARLY THIS EVENING BEFORE SUN GOES DOWN. STILL...A GOOD PREVIEW OF
WHAT WE WILL SEE TONIGHT CAN BE SEEN IN ERN KS WITH THE CENTER OF
THE UPPER SYSTEM EXPECTED TO TRACK JUST N OF THE I-70 CORRIDOR.
DEFORMATION ZONE PCPN INITIALLY SHUNTED TO THE NRN HALF OF THE FA
THIS EVENING WILL ERODE ON ITS WRN SIDE AND THEN GRADUALLY TILT MORE
N-S ORIENTED BY SUNDAY MORNING AND DO A FINAL SWEEP ACROSS THE ERN
FA/SWRN IL.
CLOUDS WILL ALSO STICK AROUND SUNDAY LONGER THAN ANTICIPATED 24HRS
AGO...AND THIS WILL TAKE A HIT TO MAX TEMPS...ESPECIALLY FOR STL
METRO AND AREAS SE...WHERE THEY HAVE BEEN TRIMMED A CATEGORY OR
TWO...OR IN LINE WITH THE COOLER MET MOS NUMBERS. FURTHER NW...MAX
TEMPS ARE CLOSE TO A MOS BLEND.
(MONDAY - WEDNESDAY)
UPPER LEVEL RIDGE OVER ERN NOAM WILL DOMINATE THIS PERIOD...WITH A
TROF BUILDING OVER THE NWRN CONUS INITIALLY...BUT DEEPENING WITH
TIME AS IT SLOWLY TRANSLATES EWD INTO THE PLAINS BY WEDNESDAY. THIS
SHOULD GIVE US A PERIOD OF WARM AND MAINLY DRY WX.
THE WARMER MAV MOS IS A GOOD PLACE TO START FOR MONDAY MAX TEMPS AND
IN SOME PLACES...EDGED EVEN HIGHER. LOOK FOR LO-MID 80S ON TUESDAY
WITH A MORE SW WIND EXPECTED. LARGE ADJUSTMENT MADE TO
INITIALIZATION FOR MAX TEMPS ON WEDNESDAY WITH ECMWF CONSISTENTLY
THE SLOWEST MODEL WITH PROGRESSION WHAT SHOULD BE A STRONG CDFNT AND
EVEN GFS ALSO BACKING OFF. WEDNESDAY MAX TEMPS WITH A CDFNT EITHER
ARRIVING VERY LATE OR NOT AT ALL WILL YIELD VALUES AT LEAST
COMPARABLE TO MONDAY...PROBABLY TUESDAY.
(THURSDAY - FRIDAY)
LARGE DISCREPANCY BETWEEN MODELS ON WHAT TO DO NEXT WITH THAT PLAINS
UPPER LEVEL TROF. WHILE ALL BREAK OFF THE DIGGING SHORTWAVE
RESPONSIBLE AND CUT IT OFF FROM THE MAIN FLOW...WHEN AND WHERE THIS
HAPPENS IS A MATTER OF DISPUTE. THE GEM AND ECMWF PREFER TO MAKE
THIS OCCUR SOONER AND SETUP A CUTOFF LO OVER THE CNTRL-SRN PLAINS
WHILE THE GFS IS A BIT LATER...AND INSTEAD OVER THE MID MS AND LOWER
OH VALLEYS. A HUGE DIFFERENCE IN WHAT I FCST DEPENDING ON WHICH
MODEL WITH SFC CDFNT TIMING DIFFS AND AMOUNT OF TIME FRONT SPENDS
OVER THE FA AS WELL...WITH THE GFS BLOWING IT THRU QUICKLY WHILE THE
ECMWF AND GEM LINGER IT FOR A WHILE. WENT GENEROUS WITH POPS ON THE
TAIL-END TIMING-WISE...NOW EXTENDING CHC CATEGORY INTO THURSDAY
NIGHT FOR SOME AREAS ESPECIALLY WITH WEDNESDAY LOOKING LESS
PROBABLE. BUT OVERALL...A LO CONFIDENCE FCST AT THIS TIME. SHOULD
COLD AIR BLOW THRU PER GFS...COULD BE AN UNUSUALLY COLD COUPLE OF
MORNINGS FOR EARLY MAY.
TES
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1249 PM CDT SAT APR 27 2013
UPPER LEVEL DISTURBANCE OVER NORTHWEST MISSOURI WILL CONTINUE
DRIFTING EAST. OCCASIONAL RAIN/SHOWERS WILL CONTINUE ACROSS MOST
OF THE AREA...WITH IFR FLIGHT CONDITIONS PREVAILING FOR MOST OF
THE AFTERNOON ALONG AND SOUTH OF THE I-70 CORRIDOR. CONDITIONS MAY
IMPROVE TEMPORARILY AT TIMES...BUT GENERALLY SPEAKING CIGS WILL
REMAIN AOB 900FT IN THESE AREAS. FURTHER NORTH...CIGS BETWEEN
1000-1900FT WILL PREVAIL WITH OCCASIONAL DIPS INTO IFR TERRITORY.
THE RAIN WILL EVENTUALLY TAPER OFF AND END LATE THIS
EVENING/OVERNIGHT. HOWEVER...WIDESPREAD IFR FLIGHT CONDITIONS WILL
CONTINUE TO PREVAIL...MOST LIKELY ACROSS THE ENTIRE AREA IN IN THE
WAKE OF THE DISTURBANCE.
SPECIFICS FOR KSTL...
DIFFICULT CEILING FORECAST AT LAMBERT. BEEN WATCHING CIGS CREEP UP
OVER THE PAST FEW HOURS...AND WITH RAIN COMING TO A TEMPORARY END
IT APPEARS THAT CIGS MAY STILL POP UP TO 1000FT OR A BIT HIGHER.
REGARDLESS...THE RISE TO MVFR WILL ONLY BE TEMPORARY AS ANOTHER
ROUND OF RAIN WILL AFFECT THE TERMINAL LATER THIS AFTERNOON/EARLY
THIS EVENING. AGAIN...TIMING WILL BE DIFFICULT AS THE AREA OF RAIN
CONTINUES TO CHANGE SIZE AND SHAPE. IFR CONDITIONS SHOULD PREVAIL
THROUGH THE NIGHT INTO SUNDAY MORNING.
CARNEY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
101 PM CDT SAT APR 27 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 348 AM CDT SAT APR 27 2013
LOW PRESSURE WILL CONTINUE TO TRACK ACROSS SRN CANADA TODAY
PRODUCING SOUTHWEST WINDS AHEAD OF A NORTHWEST WIND SHIFT ACROSS
NORTHWEST NEBRASKA. LIGHT WINDS...DEEP VERTICAL MIXING...NEARLY FULL
SUN AND A STRONG THERMAL RIDGE SHOULD PRODUCE HIGHS AROUND 80. THE
RAP MODEL IS LEADING THE WAY WITH THIS FEATURE.
TONIGHT...WEST WINDS DEVELOP MAINTAINING A THERMAL RIDGE ACROSS THE
FORECAST AREA AND LOWS IN THE 30S TO NEAR 40.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 348 AM CDT SAT APR 27 2013
ANOTHER DAY OF WELL ABOVE
NORMAL TEMPERATURES WILL BE EXPECTED FOR SUNDAY AS GUIDANCE SUGGEST
H85 TEMPERATURES APPROACHING...IF NOT EXCEEDING 20C. THE WARM LOWER
LEVELS WILL ALLOW SURFACE TEMPERATURES TO CLIMB WELL INTO THE
70S...AND POSSIBLY LOW 80S ACROSS THE ENTIRE FORECAST AREA. WITH THE
WELL ABOVE CLIMO HIGHS EXPECTED...FIRE CONCERNS WILL ONCE AGAIN
FLIRT WITH CRITICAL THRESHOLDS BY EARLY AFTERNOON. THE LOWEST RH
READINGS ARE ANTICIPATED ACROSS OUR WESTERN AND SOUTHERN FIRE ZONES
WHERE A EASTWARD ADVANCING SURFACE TROUGH LOW PRESSURE WILL WORK IN
CONCERT WITH STRONG TROPOSPHERIC MIXING TO ALLOW FOR OCCASIONAL
WIND GUSTS AT OR NEAR 20KTS /SLIGHTLY BELOW RFW WIND THRESHOLD/.
WILL HOLD OFF ON ANY FIRE HEADLINE FOR NOW. INTO THE OVERNIGHT A
WEAK PERTURBATION WILL RAPIDLY ADVANCE THROUGH QUASI-ZONAL FLOW AND
BRING A CHANCE OF A SHOWER...OR POSSIBLY A THUNDERSTORM...TO
NORTHERN PORTIONS OF THE CWA. THE OPERATIONAL MODELS INDICATE
ENOUGH OMEGA FOR PRECIPITATION PRODUCTION FOR MUCH OF THE
CWA...HOWEVER BUFR PROXIMITY SOUNDINGS SUGGEST THE LOWER TROPOSPHERE
WILL REMAIN FAIRLY DRY...THUS WILL MAINTAIN SLIGHT TO LOW END CHANCE
POPS ACROSS OUR NORTH OVERNIGHT SUNDAY INTO MONDAY...GENERALLY TIED
TO THE STRONGEST OMEGA AND BEST LOWER LEVEL MOISTURE PROFILES...BUT
LEAVE THE SOUTHERN HALF OF THE CWA MAINLY DRY...WITH ONLY A MENTION
OF SPRINKLES. SIMILAR CONDITIONS ARE EXPECTED FOR MONDAY...WITH THE
POSSIBILITY OF SLIGHTLY WARMER TEMPERATURES AND GREATER GUSTS. RED
FLAG WARNINGS MAY BE NEEDED FOR THE AFTERNOON HOURS. DRY CONDITIONS
WILL PREVAIL INTO EARLY TUESDAY AS A LACK IN KINEMATIC FORCING
RETURNS ONCE AGAIN...HOWEVER PRECIPITATION CHANCES INCREASE DURING
THE AFTERNOON HOURS ON TUESDAY AS A BAROCLINIC ZONE AND ASSOCIATED
SHORTWAVE CROSSES THE REGION. BESIDES THE PRECIPITATION
CHANCES...TEMPERATURES WILL BE MARKEDLY COOLER FOR MIDWEEK BEHIND
THE PASSING FRONT. IN FACT...FREEZE CONCERNS MAY BE REALIZED EARLY
WEDNESDAY AS THE LONGER RANGE SOLUTIONS SUGGEST H85 TEMPERATURES
FALL SOME 20-25C...WHICH WOULD PROVIDE FOR LOWS IN THE UPPER
20S-LOWER 30S AND HIGHS MAINLY IN THE 50S THROUGH MIDWEEK. THE
LONGER RANGE SOLUTION REMAIN IN POOR AGREEMENT AND THUS CONFIDENCE
IS LOW FOR MIDWEEK AND BEYOND...BUT THE GENERAL IDEA REMAINS OF
BROAD CYCLONIC FLOW ACROSS THE CENTRAL CONUS THROUGH THE END OF THE
WORK WEEK...WITH SLOWLY MODERATING TEMPERATURES AND POSSIBLY A
CHANCE AT ADDITIONAL PRECIPITATION. BUT WITH THE LOW CONFIDENCE IN
THE EXTENDED FORECAST...WILL MAINTAIN A DRY FORECAST BEYOND
WEDNESDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1259 PM CDT SAT APR 27 2013
RIDGE OF HIGH PRESSURE WILL CONTINUE TO DOMINATE THE REGION INTO
SUNDAY WITH CLEAR VFR SKIES. SOUTHWEST WINDS WILL SLOWLY TURN TO
THE WEST THEN NORTHWEST TODAY. THIS AFTERNOON WINDS WILL GUST TO
AROUND 15 KTS...THEN THIS EVENING DECOUPLING WILL RESULT IN LIGHT
WINDS. TOMORROW WINDS WILL ONCE AGAIN COME UP...ALTHOUGH ONLY TO
10 TO 15 KTS IN THE MORNING.
&&
.FIRE WEATHER...
ISSUED AT 348 AM CDT SAT APR 27 2013
A 75 PERCENT BLEND OF THE RAP AND 25 PERCENT OF THE REST OF THE
MODELS PRODUCES RELATIVE HUMIDITY BETWEEN 10 AND 20 PERCENT ACROSS
THE FCST AREA. ALL INDICATIONS ARE WINDS WILL BE WEAK AT LESS THAN
20 MPH.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...JACOBS
AVIATION...MASEK
FIRE WEATHER...CDC
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1229 PM CDT SAT APR 27 2013
.UPDATE...
ISSUED AT 957 AM CDT SAT APR 27 2013
WILL CONTINUE TO SEE SOME AREAS OF FOG LINGERING THIS
MORNING...PRIMARILY ALONG A PHG/HSI/AUH/JYR LINE...WHERE
VISIBILITIES NEAR 1/2 MILE WILL REMAIN POSSIBLE. HOWEVER...WITH
MOST OTHER AUTOMATED SITES/WEB CAMS SHOWING IMPROVING CONDITIONS
AND THE HRRR SUGGESTING WHAT LINGERING FOG THERE IS NOT LASTING
MUCH LONGER...DECIDED TO LET THE HEADLINE EXPIRE AT 10. OTHERWISE
ONLY MINOR TWEAKS MADE.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 535 AM CDT SAT APR 27 2013
BIGGEST CHALLENGE WILL BE DETERMINING EXTEND AND TIMING OF FOG THIS
MORNING...AND ALSO HIGH TEMPERATURES FOR TODAY.
WE HAPPEN TO BE IN AN AREA OF LOW-LEVEL CONVERGENCE THAT IS HANDLED
FAIRLY WELL BY THE HRRR...BUT NOT AS WELL BY OTHER MODELS...ALTHOUGH
THE LATEST RUN OF THE SREF ENSEMBLE SEEMS TO BE CATCHING UP WITH THE
HRRR. THE HRRR INDICATES THAT IT COULD BE AS LATE AS 10 AM UNTIL WE
CAN GET THE FOG BURNED OFF.
OVERALL...SPLIT FLOW CONTINUES IN THE UPPER LEVELS...WITH OUR CWA IN
BETWEEN...WHICH WHICH WILL LEND TO LIGHT FLOW IN GENERAL. THERE
SHOULD BE ENOUGH SUBSIDENCE TO HELP SCOUR OUT THE STRATUS AND FOG BY
LATE MORNING...WHICH SHOULD GIVE US PLENTY OF SUN BY AFTERNOON.
AREAS TO THE NORTH/WEST WILL WARM THE MOST AND I HAVE INCREASED HIGH
TEMPERATURES IN THESE AREAS FROM THE PREVIOUS FORECAST...WITH
SOUTHEASTERN AREAS A BIT COOLER WHERE STRATUS MIGHT STICK AROUND A
BIT LONGER AND 850 MB TEMPERATURES WILL BE COOLER. I PLACED QUITE A
BIT OF WEIGHT ON HOW MODELS HAVE PERFORMED VERY RECENTLY TO DERIVE
HIGH TEMPERATURES FOR TODAY. WENT CLOSE TO PREVIOUS FORECAST LOW
TEMPERATURES.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 535 AM CDT SAT APR 27 2013
THIS 6-DAY PERIOD LOOKS TO FEATURE QUITE A ROLLER COASTER RIDE IN
TEMPERATURES...STARTING OUT WITH A CONTINUATION OF THE ONGOING
VERY MILD STREAK...BUT THEN SETTLING DOWN BELOW NORMAL AGAIN FOR
WEDNESDAY-FRIDAY. UNFORTUNATELY...THERE ARE SUGGESTIONS BY SOME
MODELS...ESPECIALLY THE ECMWF...THAT THIS NEXT BATCH OF COLD COULD
BE QUITE A BIT MORE INTENSE THAN THE CURRENT FORECAST
DEPICTS...AND DARE WE SAY BRING THE POTENTIAL FOR AT LEAST A
RAIN/SNOW MIX TO SOME AREAS. HOWEVER...GIVEN THAT THIS POTENTIALLY
BIG COOL DOWN IS STILL 4+ DAYS AWAY AND UNCERTAINTY REMAINS
PLENTIFUL...HAVE ONLY MADE MINOR DOWNWARD TWEAKS TO PREVIOUS
FORECAST TEMPS FOR NOW...BUT STAY TUNED FOR POTENTIALLY MORE
DRASTIC CHANGES. GIVEN THAT THIS POTENTIAL COLD SNAP WILL OCCUR IN
EARLY MAY...ITS NOW NOT OUT OF THE QUESTION THAT A FROST
ADVISORY/FREEZE WARNING SITUATION MAY UNFOLD SOMETIME DURING THE
WED-FRI TIME FRAME AS WELL...ALTHOUGH A WIDESPREAD HARD KILLING
FREEZE OF 28 DEGREES OR LOWER DOES NOT SEEM EVIDENT AT THIS TIME.
TURNING TO OTHER ELEMENTS OF THE FORECAST...IT STILL LOOKS LIKE
THE TUES AFTERNOON/EVENING TIME FRAME HOLDS COULD HAVE SEVERE
THUNDERSTORM POTENTIAL...ESPECIALLY WITHIN THE SOUTHEAST 1/3 OF
THE CWA. LAST BUT NOT LEAST...WILL HAVE TO KEEP AN EYE SUNDAY
AFTERNOON FOR AT LEAST LIMITED FIRE DANGER...AS DISCUSSED IN A BIT
MORE DETAIL IN THE SEPARATE FIRE WEATHER SECTION BELOW.
STARTING IN MORE DETAIL WITH SUNDAY/SUNDAY NIGHT...THE VAST
MAJORITY...IF NOT THE ENTIRE CWA SHOULD STAY DRY...WITH THE
DAYTIME HIGHS LIKELY THE WARMEST OF THE ONGOING WARM
STRETCH...WITH MUCH OF THE CWA FORECAST TO BREACH 80 DEGREES FOR
THE FIRST TIME THIS SPRING. ALOFT...VARIOUS MODELS SUCH AS THE 00Z
NAM/GFS/ECMWF ARE IN DECENT AGREEMENT WITH BROAD WEST-NORTHWEST
FLOW...AS ONE MID LEVEL SHORTWAVE DEPARTS EASTWARD THROUGH THE
MIDWEST/OH VALLEY...WHILE THE NEXT BATCH OF LOW AMPLITUDE MID
LEVEL TROUGHS BRUSHES ACROSS THE DAKOTAS/MAINLY NORTHERN NEB ON
SUN NIGHT. THROUGH MOST OF THE DAY...FAIRLY LIGHT WEST-SOUTHWEST
BREEZES AND PLENTY OF SUNSHINE WILL PREVAIL. HOWEVER...BY LATE
AFTERNOON INTO EARLY EVENING...A WEAK COLD FRONT WILL SAG INTO THE
NORTHERN CWA...PUSHED SOUTHWARD BY THE AFOREMENTIONED NORTHERN
PLAINS ENERGY. ALTHOUGH HAVE LEFT OUT ANY PRECIP MENTION...WENT
AHEAD WITH SILENT 10 POPS ACROSS SEVERAL NORTHERN/WESTERN COUNTIES
LATE AFTERNOON INTO THE EVENING NEAR THIS BOUNDARY TO AT LEAST
HINT AT THE VERY LOW POTENTIAL FOR A SHOWER OR WEAK
THUNDERSTORM...ALTHOUGH THE LATEST 4KM WRF-NMM KEEPS ANY PRECIP
POTENTIAL NORTH OF THE CWA...ALTHOUGH THIS BEARS WATCHING. LATE
SUNDAY NIGHT...KEPT A MEASURABLE POP OUT OF THE FORECAST...BUT
EXPANDED THE PREVIOUSLY INTRODUCED CHANCE OF SPRINKLES ACROSS MOST
OF THE NORTHERN 1/3 OF THE CWA...AS A BAND OF MID LEVEL SATURATION
WORKS EASTWARD ACROSS THE REGION IN ASSOCIATION WITH THE PASSING
WEAK WAVE. ALTHOUGH LATER SHIFTS MAY NEED TO CONSIDER ADDING A LOW
MEASURABLE POP FOR THIS ACTIVITY ESPECIALLY FAR NORTH AROUND
ORD/GREELEY...DRY LOW LEVELS STILL SEEM TO SUGGEST THAT SPRINKLES
SHOULD LARGELY SUFFICE. TEMP-WISE...MADE LITTLE CHANGE TO HIGHS
AND LOWS...WITH ALL AREAS TOPPING OUT SOMEWHERE BETWEEN
79-85...AND BOTTOMING OUT IN THE UPPER 40S TO LOW 50S SUNDAY
NIGHT. BASED ON DRY WESTERLY FLOW ESPECIALLY EVIDENT IN THE LAST
FEW NAM RUNS...AFTERNOON DEWPOINTS WERE LOWERED SEVERAL DEGREES
FROM PREVIOUS...THUS PUSHING A GOOD CHUNK OF THE AREA TO 20
PERCENT OR LOWER RELATIVE HUMIDITY FOR A FEW HOURS.
MONDAY/MONDAY NIGHT...HAVE LEFT THIS ENTIRE 24 HOURS PRECIP
MENTION-FREE FOR NOW...ALTHOUGH AS NOTED BY PREVIOUS FORECASTERS
THIS IS NOT NECESSARILY A GUARANTEE FOR ALL AREAS AND WILL BEAR
WATCHING. IN THE MID LEVELS...THE GENERAL STORY INVOLVES THE
AFOREMENTIONED LOW AMPLITUDE SHORTWAVE TROUGH DEPARTING TO THE
EAST...WHILE A STRONGER UPSTREAM DISTURBANCE AND ASSOCIATED UPPER
JET STREAK STARTS TO CARVE A BIT MORE AMPLIFIED TROUGH ACROSS THE
NORTHERN ROCKIES/NORTHERN PLAINS. BREEZES DURING THE DAY WILL
GRADUALLY TURN FROM EASTERLY TO SOUTHERLY IN RESPONSE TO DEEPENING
LOW PRESSURE TO THE NORTHWEST...WITH THE LEADING EDGES OF THE NEXT
COLD FRONT THEN POSSIBLY REACHING THE NORTHWEST CWA BY SUNRISE
TUESDAY MORNING. AS FOR POSSIBLE PRECIP CHANCES TO CONSIDER IN
LATER FORECASTS...FOR ONE THERE COULD BE A BRIEF PERIOD OF
LINGERING SPRINKLES RIGHT AWAY IN THE MORNING. SECONDLY...THE
LATEST NAM SUGGESTS ANOTHER BATCH OF SHOWER ACTIVITY COULD BRUSH
NORTHERN COUNTIES VERY LATE MON NIGHT...ALTHOUGH THIS IS NOT WELL-
SUPPORTED BY OTHER SOLUTIONS. LASTLY...ALTHOUGH UNLIKELY...SUPPOSE
ITS NOT COMPLETELY OUT OF THE QUESTION THAT A LATE AFTERNOON
THUNDERSTORM COULD DEVELOP PRIMARILY IN THE SOUTHEAST CWA IN
RESPONSE TO 500-1000 J/KG OF 0-1KM MLCAPE...BUT FORECAST SOUNDINGS
SUGGEST THAT CAPPING AND LACK OF LIFT IN THE WAKE OF THE INITIAL
DEPARTING WAVE SHOULD PRECLUDE THIS SCENARIO. BOTTOM LINE...NO
PRECIP RISK MENTIONED AT THIS TIME. TEMP-WISE...ALTHOUGH STILL
QUITE WARM...SLIGHTLY LESS FAVORABLE MIXING THAN SUNDAY IS
EXPECTED TO KEEP TEMPS VERY SLIGHTLY COOLER...AND HAVE MOST AREAS
TOPPING OUT 77-82.
TUESDAY/TUESDAY NIGHT...AS MENTIONED ABOVE...THE LATE
AFTERNOON/EVENING TIME FRAME HOLDS THE BEST POTENTIAL FOR A ROUND
OF POTENTIALLY SEVERE STORMS MAINLY ACROSS THE SOUTHEAST 1/3 TO
1/2 OF THE CWA...BUT THIS IS ALSO FAR FROM A SURE THING AS SO MUCH
WILL DEPEND ON STILL-UNCERTAIN FRONTAL TIMING. ALOFT...BOTH THE
ECMWF/GFS SOLUTIONS ARE STILL IN PRETTY DECENT AGREEMENT AT THIS
POINT THAT A LARGE SCALE TROUGH AXIS WILL CONTINUE TO AMPLIFY
ALONG AN AXIS FROM THE NORTHERN PLAINS TO CENTRAL ROCKIES...WHILE
IN THE LOW LEVELS A RATHER HEALTHY COLD FRONT PUSHES SOUTHWARD
ACROSS THE CWA. ALTHOUGH A DECENT CAP SHOULD HOLD CONVECTION AT
BAY UNTIL AT LEAST MID-AFTERNOON...SOMETIME IN THE 21Z-01Z TIME
FRAME IS CURRENTLY EXPECTED TO FEATURE THE DEVELOPMENT OF STORMS
NEAR THE INVADING COLD FRONT...WHICH COULD BECOME SEVERE IN A
LIKELY QUASI-LINEAR FASHION PER THE ECMWF FORECAST OF 1000-1500
J/KG MLCAPE AND MODEST DEEP LAYER SHEAR. AS THE NIGHT WEARS
ON...THE OVERALL THUNDERSTORM INTENSITY SHOULD DIMINISH...BUT
COVERAGE OF WIDESPREAD RAIN AND EMBEDDED THUNDERSTORMS WOULD
INCREASE ACROSS NEARLY THE ENTIRE CWA AS A STRONGLY FORCED BAND OF
MID LEVEL CONVERGENCE/FRONTOGENESIS INVADES THE CWA FROM NORTHWEST
TO SOUTHEAST. ENOUGH CONSISTENCY IN THIS SCENARIO FOR TUESDAY
NIGHT EXISTS THAT POPS WERE RAISED INTO LIKELY TERRITORY IN MANY
AREAS. TEMP-WISE...HIGHS TUESDAY WILL BE TRICKY DUE TO UNCERTAINTY
IN THE SPEED OF THE INVADING COLD FRONT...BUT FOR NOW KEPT A
GENERAL RANGE FROM NEAR 70 NORTH TO NEAR 80 SOUTH.
FOR THE WEDNESDAY-FRIDAY TIME FRAME...THERE JUST ISN/T MUCH TO BE
GAINED YET BY GOING INTO MUCH DETAIL DUE TO VARYING MODEL
SOLUTIONS REGARDING THE EVOLUTION OF THE PASSING LARGE SCALE
TROUGH. IN GENERAL...BOTH THE 00Z ECMWF/GFS SOLUTIONS DEPICT A
SLOWING AND STALLING MID/UPPER TROUGH AS IT PASSES INTO THE
CENTRAL PORTION OF THE NATION...AS AN EXPANSIVE BLOCKING RIDGE
SETS UP SHOP OVER THE EASTERN CONUS. AS THIS BLOCK TAKES SHAPE...A
CLOSED...COLD AND FAIRLY COMPACT MID LEVEL LOW IS PROGGED TO FORM
SOMEWHERE...WITH THE ECMWF CLOSING THIS OFF OVER THE KS/OK AREA BY
THURS NIGHT INTO FRIDAY...WHILE THE GFS CLOSES THIS DEEP LOW OFF
MORE SO OVER MO/AR. ABOUT THE ONLY THING THE CURRENT FORECAST HAS
MUCH CONFIDENCE IN IS THAT DECENT PRECIP CHANCES WILL CONTINUE
ACROSS NEARLY THE ENTIRE CWA DURING THE DAY WEDNESDAY. HAVE KEPT
THIS RAIN FOR NOW...BUT THE VERY COLD ECMWF SOLUTION WOULD SUGGEST
A SNOW MIX POSSIBLE. THE CURRENT FORECAST THEN LINGERS A LESSER
CHANCE OF A RAIN/SNOW MIX ACROSS ROUGHLY THE SOUTHEAST 1/3 OF THE
CWA WED NIGHT...WHILE KEEPING THURSDAY-FRIDAY PRECIP-FREE.
HOWEVER...THIS PRECIP-FREE DEPICTION WILL NOT LAST IF THE ECMWF IS
IN FACT ONTO SOMETHING...AS IT DEPICTS A POSSIBLE RAIN/SNOW MIX
LASTING INTO FRIDAY IN SOME AREAS. RE-EMPHASIZING THE MAIN POINTS
HERE...A MUCH COOLER WEATHER REGIME WILL SETTLE IN BY MID-LATE
WEEK...BUT WE ARE STILL A FEW DAYS AWAY FROM PINNING DOWN JUST
HOW COLD IT MIGHT REALLY GET...AND WHETHER A RISK REALLY EXISTS
FOR POSSIBLY ANOTHER ROUND OF LATE-SEASON SNOW AND/OR SUB-
FREEZING OVERNIGHT LOW TEMPS. STAY TUNED...
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1222 PM CDT SAT APR 27 2013
QUIET WEATHER WITH VFR CONDITIONS EXPECTED FOR THIS TAF
PERIOD...WITH UPPER LEVEL SHORTWAVE RIDGING BUILDING INTO THE
REGION. EXPECTING LITTLE IN THE WAY OF CLOUD COVER THROUGH THE
PERIOD...AND SOUTH/SOUTHWESTERLY WINDS WILL REMAIN IN
PLACE WITH SPEEDS GENERALLY NEAR 10 MPH.
&&
.FIRE WEATHER...
ISSUED AT 535 AM CDT SAT APR 27 2013
BOTH TODAY AND SUNDAY...THE LATEST FORECASTS NOW PUSH AFTERNOON
RELATIVE HUMIDITY VALUES BELOW 20 PERCENT IN PARTS OF THE CWA.
HOWEVER...THE PRESENCE OF LIGHTER WINDS THAN THOSE OBSERVED FRIDAY
IS CURRENTLY EXPECTED TO KEEP OVERALL FIRE DANGER RATHER
LIMITED...AS OPPOSED TO ELEVATED TO CRITICAL AS MIGHT BE THE CASE
WITH STRONGER WINDS. FOCUSING FIRST ON TODAY...SUB-20 PERCENT
RELATIVE HUMIDITY IS FORECAST TO FOCUS ONLY IN FAR
WESTERN/NORTHERN AREAS...GENERALLY WEST OF A GREELEY-BEAVER CITY
LINE. THEN ON SUNDAY...SUB-20 PERCENT RH IS PROGGED TO DEVELOP
ACROSS MOST COUNTIES WEST OF THE HIGHWAY 281 CORRIDOR. OF THE TWO
AFTERNOONS...SUNDAY BEARS THE MOST WATCHING TO MAKE SURE WINDS
SPEEDS DON/T CREEP HIGHER THAN CURRENTLY FORECAST.
FOR NOW...SUSTAINED WESTERLY SPEEDS AT MOST 10-15 MPH/GUSTS AT
MOST 15-20 MPH ARE FORECAST...KEEPING THINGS 5-10 MPH SHORT OF
POTENTIALLY CRITICAL FIRE THRESHOLDS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...ADO
SHORT TERM...HEINLEIN
LONG TERM...PFANNKUCH
AVIATION...ADO
FIRE WEATHER...PFANNKUCH
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
201 PM EDT SAT APR 27 2013
.SYNOPSIS...
AN INCREASINGLY MOIST WEDGE OF COOLER AIR WILL OVERSPREAD THE REGION
THIS WEEKEND AS WEAK LOW PRESSURE MOVES ACROSS THE TENNESSEE VALLEY
ALONG A STALLED COLD FRONT. THE FRONT WILL SLOWLY DISSIPATE AND THE
COOL AIR WEDGE WILL GRADUALLY WEAKEN INTO EARLY NEXT WEEK. OUR
WEATHER PATTERN WILL LIKELY REMAIN UNSETTLED THROUGH NEXT WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 2 PM...I WILL UPDATE THE FORECAST TO REFINE POPS TO RADAR
TRENDS. BASED ON THE LATEST TRENDS...LIGHT TO MODERATE RAIN SHOWERS
SHOULD SPREAD ACROSS THE CLT METRO AREA OVER THE NEXT HOUR OR TWO.
TEMPERATURES ACROSS THE REGION THIS AFTERNOON WILL REMAIN NEARLY
STEADY.
AS OF 1115 AM...LATEST RADAR TRENDS HAVE INDICATED AN INCREASING
TREND IN RAINFALL RATES ACROSS THE SOUTHERN NC MTNS SE ACROSS THE
SAVANNAH RIVER VALLEY. I WILL INCREASE POPS OVER THE AREA THROUGH
MID DAY. THE REST OF THE CWA HAS MAINLY EXPERIENCED SPRINKLES TO
LIGHT RAIN SHOWERS. THIS TREND MAY CONTINUE OVER THE NEXT COUPLE OF
HOURS. HOWEVER...NEAR TERM MODELS REMAIN IN AGREEMENT WITH SPREADING
COVERAGE EAST ACROSS THE MTNS THIS AFTERNOON WITH THE APPROACH AND
PASSAGE OF A MID LEVEL S/W. I WILL TIME CATE POPS ACROSS THE MTNS
AND ADJACENT FOOTHILLS THIS AFTERNOON. I WILL ALSO COOL TEMPS ACROSS
THE MTNS A COUPLE OF CLICKS...PIEDMONT AREAS APPEARS ON TRACK.
I HAVE ALSO UPDATED THE FORECAST THROUGH SUNDAY. THE MAIN CHANGES
INCLUDE INCREASING POPS AND INDICATING HIGHER QPF OVER UPSLOPE AREAS.
630 AM UPDATE...500MB VORT MAX NOW PASSING THROUGH THE AREA AND
SPARKING A FEW ADDITIONAL SHOWERS OVER THE NW NC PIEDMONT...WHILE
MOST OF THE ACTIVITY REMAINS OVER SW HALF OF CWFA. MADE SOME MORE
ADJUSTMENTS TO POPS INCLUDING SLIGHT EASTWARD EXPANSION TO ACCOUNT
FOR THE PIEDMONT SHOWERS...WHICH LOOK VERY LIGHT ON RADAR AND ARE
NOT LIKELY TO PRODUCE SIGNIFICANT ACCUMS OVER THE NEXT HOUR OR SO.
430 AM UPDATE...ADJUSTED POPS THROUGH DAYBREAK. 06Z NAM DOES NOT
SEEM TO HAVE A GREAT HANDLE ON THE ONGOING PRECIP AROUND THE
REGION...NOT SHOWING ANY ACCUMS FROM THE ACTIVITY IN THE SAVANNAH
RIVER VALLEY. IT DOES CONTINUE TO SUPPORT THE INCREASING POPS NEAR
THE TENN BORDER AFTER SUNRISE. 06Z HRRR SHOWS SOME OF THE CURRENT
ACTIVITY MOVING EAST THEN BRINGS A COUPLE OF WAVES OF SHOWERS ACROSS
BY LATE MORNING. MADE ADJUSTMENTS TO PREVIOUS TREND MOSTLY BASED ON
RADAR MAINLY INTERPRETING THE NEW GUIDANCE AS A CONFIDENCE BOOST.
AS OF EARLY SAT MORNING...SFC HIGH OVER NE CONUS SEEN ON CURRENT SFC
ANALYSIS SITS IN A FAVORABLE POSITION TO ALLOW DEVELOPMENT OF CAD
ACROSS OUR REGION DURING THE NEAR TERM PERIOD. LLVL WINDS ABOVE THE
BOUNDARY LAYER ARE ALREADY SOUTHERLY. THROUGH THE DAY TODAY MIDLEVEL
RIDGE SHIFTS SLIGHTLY EASTWARD AS CLOSED UPPER LOW GROWS OVER THE MID
MISSISSIPPI VALLEY. THE EFFECT WILL BE TO STRENGTHEN THE FLOW OVER
THE CAD WEDGE LEADING TO A SOMEWHAT STEADY INCREASE IN ISENTROPIC
LIFT AND DEEP MOISTURE ADVECTION. MEANWHILE...EXTRA SUPPORT FOR
PRECIP DEVELOPMENT WILL COME FROM VORT MAXES ROUNDING THE SUBTLE
UPPER RIDGE AHEAD OF THE CLOSED LOW. ONE AREA OF PVA IS EXPECTED TO
SPREAD ITS ASSOCIATED PRECIP INTO THE MTNS AROUND DAYBREAK WHILE A
SECOND...SHOWN ON BOTH GFS AND NAM...WILL MOVE THROUGH THIS
AFTERNOON. THAT FEATURE IS CONCURRENT WITH RIGHT REAR QUAD OF 250MB
JET STREAK AND ASSOCIATED DIVERGENCE. UPPER SUPPORT WANES SOMEWHAT ON
GFS THIS EVENING...BUT NAM FEATURES MCV/S MOVING IN AT THAT TIME.
THESE ARE PROBABLY RESULTING FROM CONVECTION UPSTREAM...SO NOT
NECESSARILY BITING ON ANY MODELED EFFECTS FROM THOSE. MIDLEVEL
Q-VECTOR CONVERGENCE DOES CONTINUE TO INCREASE AS HEIGHTS FALL OVER
THE TENN VALLEY AHEAD OF THE UPPER LOW AND AS THE WARM ADVECTION
RAMPS UP.
HAVE NOT MADE MUCH CHANGE TO POP TRENDS WHICH GENERALLY SPREAD WEST
TO EAST DURING THE PERIOD...WITH CATEGORICAL VALUES APPROPRIATE OVER
THE NW HALF OF CWA /WHERE UPSLOPING WILL PLAY THE BIGGEST ROLE AND
ALSO FEATURING THE BEST UPPER SUPPORT/. QPF COULD BE CRITICAL FOR
THIS EVENT AS A WHOLE SO GAVE IT SOME EXTRA THOUGHT. GFS IS THE MOST
ROBUST WITH THE ACTIVITY THIS AFTERNOON WHICH MAKES SENSE GIVEN ITS
EVOLUTION OF THE UPPER FORCING...AND FEATURES LOWER QPF FOR EVENING
BUT WITH SOME INCREASE AGAIN TOWARD SUN MORNING AS THE MOISTURE
DEEPENS. GENERALLY THE DETERMINISTIC TOTALS ARE BACKED UP BY THE
ACCUM PROBABILITIES PRODUCED BY THE ENSEMBLE RUN. CHOSE TO USE A
BLEND OF AVAILABLE DETERMINISTIC GUIDANCE BUT WITH A BIAS TOWARD THE
GFS.
TEMPS TODAY WILL BE BELOW NORMAL GIVEN THE CLOUD COVER AND DEVELOPING
WEDGE...BUT IF PRECIP IS DELAYED OR DOES NOT DEVELOP OVER A
WIDESPREAD AREA TEMPS COULD BE SOMEWHAT WARMER WITHOUT THE RAINFALL
TO LOCK IN THE WEDGE EARLY. WENT WITH RAW MODEL BLEND FOR TONIGHT
ASSUMING THE WEDGE WILL BE FULLY ENTRENCHED BY THEN.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 240 AM SATURDAY...AS THE UPPER RIDGE AXIS SHIFTS TO THE
COAST...AND DEEP/VERY MOIST SW FLOW BECOMES ESTABLISHED OVER THE
AREA...POPS WILL CONTINUE TO INCREASE THROUGH SUNDAY WITHIN MODESTLY
STRONG WAA/SOUTHERLY UPSLOPE REGIME. WITH THE CENTER OF THE SURFACE
HIGH EXPECTED TO SHIFT OFF THE NEW ENGLAND COAST BY SUNDAY...IN SITU
COLD AIR DAMMING WILL LIKELY BEGIN TO ERODE AROUND THE PERIPHERY OF
THE FORECAST AREA...ESP THE SOUTHERN PIEDMONT AND FAR SOUTHWEST MTN
ZONES. THIS WILL CREATE THE POTENTIAL FOR INCREASED INSTABILITY/
DEEPER CONVECTION/INCREASED RAINFALL RATES BY AFTERNOON. IN FACT...
SUNDAY AFTERNOON THROUGH SUNDAY NIGHT APPEARS TO BE THE MOST LIKELY
PERIOD OF HEAVY RAINFALL IN LIGHT OF THIS TIME OFFERING THE BEST
JUXTAPOSITION OF UPSLOPE FLOW...INSTABILITY/ MOISTURE...AS WELL AS
INCREASING UPPER LEVEL FORCING. THE LATTER COMES ABOUT AS A RESULT
OF A COUPLED JET STRUCTURE THAT MAXIMIZES SUNDAY EVENING. AREAS
ALONG THE SOUTHERN BLUE RIDGE COULD WELL SEE WIDESPREAD RAINFALL
AMOUNTS OF TWO INCHES WITHIN THIS WINDOW OF TIME ALONE. STORM TOTAL
AMOUNTS OF 2.5 TO 4 INCHES APPEAR TO BE A VERY GOOD BET THROUGH
SUNDAY NIGHT...AND CONFIDENCE IS INCREASING THAT WE MAY HAVE LOCALLY
EXCESSIVE RAINFALL CONCERNS ALONG OUR SOUTHERN BLUE RIDGE COUNTIES.
NEVERTHELESS...I STILL THINK WE ARE AROUND 48 HOURS AWAY FROM SEEING
ANY HYDRO CONCERNS...AND I WOULD LIKE TO SEE HOW TODAY/S RAINFALL
SITUATION UNFOLDS BEFORE HOISTING A WATCH...SO HAVE OPTED TO PUNT TO
THE DAY SHIFT.
BY MONDAY...THE BEST UPPER FORCING AND DEEP MOISTURE WILL SHUNT EAST
OF THE AREA. HOWEVER...SOUTHERLY FLOW WILL PERSIST IN THE LOWER
LEVELS...SUPPORTING AMPLE LOW LEVEL MOISTURE. IN FACT...WITH THE AIR
MASS DRYING SOMEWHAT ALOFT...WE MAY SEE MORE SUN/INSTABILITY MONDAY
AFTERNOON. WITH THE UPPER TROUGH/SHEAR AXIS LINGERING OVER THE
AREA...SOLID CHANCE/LOW LIKELY POPS ARE WARRANTED INTO THE
AFTERNOON. CONVECTION SHOULD BECOME MORE DIURNAL IN NATURE BY THE
END OF THE SHORT TERM PERIOD...SO POPS GRADUALLY TAPER DOWN MONDAY
EVENING.
MAX TEMPERATURES WILL REMAIN BELOW NORMAL SUNDAY UNDER WIDESPREAD
CLOUD COVER AND PRECIPITATION...BUT RETURN TO NEAR CLIMO BY MONDAY.
LOWS WILL BE AT LEAST A CATEGORY ABOVE CLIMO THROUGH THE PERIOD.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 305 AM SATURDAY...THE MEDIUM RANGE CONTINUES TO APPEAR
UNSETTLED...AS PERSISTENT SOUTH TO SE FLOW MAINTAINS A FETCH OF LOW
LEVEL MOISTURE INTO THE REGION...SUPPORTING MAINLY DIURNAL CHANCES
FOR SHOWERS AND THUNDERSTORMS. THE GLOBAL MODELS CONTINUE TO
ADVERTISE A REASSERTION OF THE EASTERN LOW LEVEL RIDGE AXIS DURING
MID-LATE WEEK. HOWEVER...THEY ARE NOT AS AGGRESSIVE IN DRYING OUT
THE LOWER LEVEL AIR MASS OVER THE CAROLINAS. THERE IS ALSO
CONSIDERABLE UNCERTAINTY REGARDING THE TIMING OF THE NEXT MAJOR
STORM SYSTEM...AS THE PRIMARY GLOBAL MODELS ARE VERY MUCH AT ODDS IN
THEIR HANDLING OF WESTERN CONUS ENERGY LATE IN THE WEEK.
THEREFORE...SLIGHT/CHANCE POPS AND NEAR-CLIMO TEMPS WILL REMAIN IN
THE FORECAST THROUGH THE EXTENDED RANGE PERIOD.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AT KCLT...THE TERMINAL HAS REMAINED EAST OF THE MAIN BAND OF SHRA
TODAY. HOWEVER...RADAR TRENDS INDICATE THAT LIGHT RAIN WILL REACH
THE TERMINAL AROUND 19Z...POSSIBLY RESULTING IN MVFR VIS BETWEEN
20Z-22Z. -SHRA SHOULD CONTINUE FOR THE REMAINDER OF THE TAF PERIOD.
AFTER SUNSET...MODEL SOUNDINGS AND MOS GUIDANCE INDICATES THAT
MOISTURE WILL INCREASE FROM THE TOP DOWN. BASED ON CONSENSUS OF THE
GUIDANCE...CLOUD BASES MAY REACH MVFR BY 7Z...LOWERING TO JUST ABOVE
010 BY 17Z. MOS INDICATES THE POSSIBILITY OF IFR AFTER SUNRISE...BUT
LEANING ON NAM SOUNDINGS I WILL KEEP IFR OUT OF THE TAF WITH THIS
PACKAGE.
ELSEWHERE...A WIDE BAND OF LIGHT TO MODERATE SHOWERS WILL REMAIN
ACROSS KAVL...KGMU..KGSP THROUGH THIS AFTERNOON. KAND MAY GENERALLY
REMAIN SOUTH OF THE BAND AS KHKY WILL GRADUALLY SEE INCREASING
COVERAGE. CEILINGS WITHIN THE BAND SHOULD REMAIN VFR...WITH ISOLATED
MVFR BASES AT TIMES. RAINFALL SHOULD INITIALLY LIMIT VIS TO MVFR AT
KAVL/KGSP/KGMU THROUGH MID AFTERNOON...THEN EXPECTED TO IMPROVE TO
VFR LATE THIS AFTERNOON. AFTER SUNSET...MODEL SOUNDINGS AND MOS
GUIDANCE INDICATES THAT MOISTURE WILL INCREASE FROM THE TOP DOWN.
BASED ON CONSENSUS OF THE GUIDANCE...CLOUD BASES MAY REACH MVFR
AFTER MIDNIGHT...LOWERING TO IFR AFTER SUNRISE.
OUTLOOK...WIDESPREAD MODERATE TO HEAVY RAIN AND LOW RESTRICTIONS
WILL CONTINUE THROUGH SUNDAY NIGHT. AN UPPER LEVEL WAVE WILL CROSS
THE REGION ON MONDAY...ACCOMPANIED BY SCATTERED THUNDERSTORMS AND
ASSOCIATED RESTRICTIONS. LOW CLOUDS AND FOG WILL THEN BE POSSIBLE
EACH MORNING THROUGH MID WEEK.
CONFIDENCE TABLE...
18-24Z 00-06Z 06-12Z 12-18Z
KCLT HIGH 100% HIGH 97% MED 79% HIGH 95%
KGSP HIGH 95% HIGH 88% MED 76% HIGH 95%
KAVL HIGH 92% HIGH 86% HIGH 80% HIGH 89%
KHKY HIGH 100% HIGH 92% HIGH 88% HIGH 85%
KGMU HIGH 91% HIGH 87% HIGH 89% MED 78%
KAND HIGH 100% HIGH 83% MED 76% HIGH 93%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...CSH
NEAR TERM...NED/WIMBERLEY
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...NED
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1217 PM CDT SAT APR 27 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 450 AM CDT SAT APR 27 2013
CLEAR SKIES AND WARM TEMPERATURES ON TAP AGAIN FOR TODAY... WITH
TEMPERATURES/HUMIDITY LEVELS THE PRIMARY CHALLENGE OF THE DAY. IN
THE IMMEDIATE TERM...DID ADD SOME PATCHY FOG TO OUR FAR SOUTHEAST
AREAS EARLY THIS MORNING. HIGHER DEW POINTS HAVE BEEN PERSISTING
SOUTH OF WEAKENING RIDGE AXIS OVERNIGHT...AND CAN SOMEWHAT SEE THE
MOISTURE DISCONTINUITY ROUGHLY SOUTH OF VERMILLION TO SPENCER IOWA
LINE ON THE IR SATELLITE IMAGERY THIS MORNING. ANY FOG EXPECTED TO
BE RELATIVELY SHALLOW GIVEN DEVELOPMENT THIS LATE IN THE OVERNIGHT
SO EXPECT IT TO DISSIPATE QUICKLY AS TEMPERATURES BEGIN TO RISE.
WITH SUNSHINE...DEEP DRY ATMOSPHERE...AND RELATIVE DRY GROUND
OUTSIDE THE AREAS WITH MOST RECENT SNOW MELT...TEMPERATURES HAVE BEEN
MIXING TO THE FULLEST AND SEE NO REASON WHY THAT WOULD NOT OCCUR
AGAIN TODAY. THUS HAVE WARMED HIGHS TODAY A LITTLE ABOVE MOST
GUIDANCE...RANGING FROM AROUND 70 OVER THE REMAINING SNOW COVER
ALONG THE BUFFALO RIDGE TO AROUND 80S IN THE WESTERN THIRD OF THE
CWA.
BOUNDARY LAYER DRYING ALSO AN ISSUE...PRIMARILY FOR FIRE WEATHER
CONCERNS. SIMILAR TO YESTERDAY...WOULD EXPECT DRIER AIR TO MIX DOWN
TO THE SURFACE THROUGH THE AFTERNOON. MODELS DID NOT SEEM TO HAVE A
GREAT TRACK RECORD ON DROPPING DOWN THE AFTERNOON DEW POINTS WITH
MIXING YESTERDAY...AND LOOKS LIKE SIMILAR DIFFICULTY MAY BE SEEN
TODAY WITH NAM FORECAST SOUNDINGS SEEMING TO MIX THE SOMEWHAT MORE
MOIST BOUNDARY LAYER UPWARD INSTEAD OF MIXING THE DEEPER DRY AIR
ALOFT DOWNWARD. RAP MODEL SOUNDINGS SEEM TO BETTER REFLECT THIS
THINKING...AND MODEL DEW POINTS RESPOND ACCORDINGLY AND FOLLOWED
THESE MORE CLOSELY FOR DEW POINT/HUMIDITY TRENDS LATER THIS MORNING
THROUGH THE AFTERNOON. THIS WILL RESULT IN HIGH FIRE DANGER ACROSS
OUR WESTERN FORECAST AREA THIS AFTERNOON...BUT WINDS SHOULD BE LIGHT
ENOUGH TO KEEP BELOW VERY HIGH CATEGORY.
START TO SEE SOME INCREASE IN CLOUDS ACROSS OUR NORTHWEST LATER
TONIGHT IN ADVANCE OF UPPER WAVE/ASSOCIATED WEAK COLD FRONT MOVING
INTO THE NORTHERN PLAINS. VERY MILD LOW LEVEL AIR ALONG WITH LIGHT
SOUTHERLY FLOW SHOULD KEEP TEMPERATURES WELL ABOVE NORMAL WITH LOWS
IN THE 40S TO NEAR 50.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 450 AM CDT SAT APR 27 2013
A LITTLE MORE ACTIVE PATTERN SETS UP EARLY NEXT WEEK...INITIALLY
WITH A CHANCE OF LATE AFTERNOON/EVENING SHOWERS OR THUNDERSTORMS
ACROSS OUR EAST SUNDAY AS THE COOL FRONT SLIDES THROUGH A SOMEWHAT
MORE MOIST ATMOSPHERE...THEN WITH A BETTER CHANCE OF RAIN LATER
SUNDAY NIGHT ALONG AND SOUTH OF I-90 AS MID LEVEL MOVES THROUGH THE
REGION. SUNDAY SHOULD BE ANOTHER WARM DAY...LIKELY THE WARMEST OF
THIS STRETCH OVER OUR SOUTHERN AREAS...WHILE THE NORTH SHOULD SEE
TEMPERATURES PEAK MORE IN THE MIDDAY/EARLY AFTERNOON WITH COOLING
THROUGH THE LATER AFTERNOON AS COLD ADVECTION SETS IN AND CLOUDS
INCREASE.
MONDAY WILL BE SLIGHTLY COOLER BEHIND THE FRONT...WITH JUST A CHANCE
OF LINGERING LIGHT RAIN IN OUR FAR SOUTHEAST IN THE MORNING AND
SKIES BECOMING MOSTLY SUNNY AGAIN BY AFTERNOON. WARM RETURN FLOW
QUICKLY SETS LATE MONDAY AFTERNOON/EVENING AND WHILE MID LEVEL
SHOWERS/THUNDERSTORMS ARE POSSIBLE ON THE NOSE OF LOW LEVEL JET...
THIS LOOKS TO BE FOCUSED TO OUR NORTH AND WILL KEEP OUR AREA DRY
THROUGH MONDAY NIGHT.
SHARP COLD FRONT THEN MOVES THROUGH LATE MONDAY NIGHT/TUESDAY...
THOUGH STRONG MIXING BEHIND THE FRONT SHOULD STILL KEEP HIGHS ON
TUESDAY NEAR TO SLIGHTLY ABOVE NORMAL IN THE 60S TO LOWER 70S. 850MB
FRONT STALLS JUST SOUTHEAST OF OUR AREA TUESDAY NIGHT WHILE STRONGER
UPPER TROUGH SWINGS OUT OF THE ROCKIES. THIS WILL BRING INCREASING
RAIN CHANCES TO THE AREA TUESDAY NIGHT INTO WEDNESDAY...MAINLY IN
OUR SOUTHEAST.
SECONDARY COLD FRONT ASSOCIATED WITH THIS WAVE WILL BRING A RETURN
TO BELOW NORMAL TEMPERATURES FROM WEDNESDAY THROUGH THE END OF THE
WEEK. LONG RANGE MODELS VASTLY DIFFERENT ON EVOLUTION OF UPPER
TROUGH AFTER IT PASSES THROUGH OUR AREA WEDNESDAY. GFS DEVELOPS A
CUTOFF LOW OVER THE WESTERN OHIO VALLEY WHILE THE ECMWF BUILDS A
MUCH STRONGER RIDGE OVER THE GREAT LAKES WHICH FORCES THE UPPER LOW
TO DEVELOP OVER THE CENTRAL PLAINS. FORMER WOULD KEEP US DRY THROUGH
THE END OF THE WEEK...WHILE THE LATTER RESULTS IN QUITE A WET PERIOD
FOR PARTS OF THE REGION. GIVEN HIGH DEGREE OF UNCERTAINTY...WILL
KEEP THE LATTER HALF OF THE WEEK DRY FOR NOW...ASIDE FROM LINGERING
LOW CHANCE OF PRECIPITATION IN OUR FAR SOUTHEAST WEDNESDAY NIGHT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1213 PM CDT SAT APR 27 2013
EXPECTING VFR CONDITIONS THROUGH THE PERIOD WITH SOUTH SOUTHWESTERLY
WINDS TODAY AROUND 5 TO 10 KTS. COLD FRONT WILL WORK ACROSS THE AREA
FROM NORTHWEST TO SOUTHEAST TOMORROW...ONLY EXPECTING IT BE THROUGH
KHON BY 18Z...WITH WINDS TURNING NORTH NORTHWESTERLY BEHIND IT AT
AROUND 10 KTS.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...JH
LONG TERM...JH
AVIATION...CHENARD
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1245 PM CDT SAT APR 27 2013
.AVIATION UPDATE...FOR 18Z TAF PACKAGE...
LATEST RADAR TRENDS INDICATE RAIN SHIELD MOSTLY EAST OF I65
CORRIDOR. STILL SCATTERED SHOWERS BEING OBSERVED ACROSS WESTERN
AND SOUTHERN MIDDLE TN AT TAF ISSUANCE. VISIBILITIES ARE CLEARING
UP AT KBNA AND KCKV AS WELL. WARM FRONT IS STILL WELL SOUTH OF THE
CWA SO ONLY WENT WITH VCSH FOR KBNA TO PREVAIL FOR THE FIRST FEW
HOURS. THIS AFTERNOON...SCATTERED SHOWERS AND THUNDERSTORMS WILL
REDEVELOP IN THE VICINITY OF KBNA AND KCKV. THESE STORMS WILL
LIKELY BE ORIENTED ALONG THE WARM FRONT AND MOVE NORTHEASTWARD.
AMENDMENTS MAY BE REQUIRED AS IMPACTS TO TERMINALS BECOMES MORE
CLEAR THIS EVENING.
&&
.PREV DISCUSSION... /ISSUED 913 AM CDT SAT APR 27 2013/
MESOSCALE UPDATE...
AT 14Z WARM FRONT DRAPED ACROSS SOUTHERN ARKANSAS AND NORTHERN
MISSISSIPPI SOUTH OF CLARKDALE. MID STATE WELL NORTH OF WARM FRONT
AND ON COOL SIDE WITH WIDESPREAD SHOWERS STRUNG OUT FROM WEST TO
EAST ACROSS WEST AND MIDDLE TENNESSEE WORKING EASTWARD. THERE IS A
SMALL CLUSTER OF THUNDERSTORMS CURRENTLY IN PERRY COUNTY WITH A
FEW MORE STORMS STILL IN WESTERN TENNESSEE YET TO COME EAST.
INFRARED CLOUD TOPS HAVE REMAINED COLD LAST FEW IMAGES WITH NO
SIGN OF WARMING. BELIEVE BEST CHANCE FOR LIGHTNING THROUGH 21Z WILL
BE SOUTH OF INTERSTATE 40...THIS BASED ON LATEST SREF RUN.
LOOKS LIKE FRONT IS GOING TO BE SLOW LIFTING NORTH DURING THE DAY
AS UPPER LEVEL ENERGY STILL REMAINS WELL WEST OF SURFACE BOUNDARY.
SURFACE LOW THIS MORNING CENTERED SOUTH OF FORT SMITH AND IS
FORECAST TO MOVE EASTWARD DURING THE DAY AND BE NEAR MEMPHIS BY
00Z THIS EVENING. AM EXPECTING WARM FRONT TO BEGIN LIFTING NORTH
AND INTO SOUTHWEST MIDDLE TENNESSEE AFTER 20Z TODAY WITH
INCREASING CAPES AND INSTABILITY ALONG WITH RISING SURFACE TEMPS
AND DEWPOINTS OVER THE SOUTHWESTERN AREAS DURING THE LATE
AFTERNOON AND WORK NORTHEASTWARD INTO MIDDLE TENNESSEE DURING THE
EARLY EVENING. THINK A FEW STRONG TO SEVERE STORMS ARE POSSIBLE
DURING THE LATE AFTERNOON/EVENING ESPECIALLY SOUTHWEST MIDDLE TENNESSEE
WHERE INSTABILITY LOOKS TO BE THE STRONGEST...BUT ISOLATED SEVERE
CANT BE RULED OUT ELSEWHERE IN THE MID STATE FROM MID TO LATE
EVENING AS INSTABILITY TRIES TO COME NORTH ALONG SURFACE BOUNDARY.
AS FOR TODAYS HIGHS...WARMER TEMPS WILL BE IN THE SOUTHWEST WHERE I
HAVE LOWER 70S WITH 60S ELSEWHERE. ONCE THIS INITIAL ROUND OF
SHOWERS AND ISOLATED THUNDERSTORMS GETS TO OUR EAST AM EXPECTING
NEW DEVELOPMENT TO TAKE PLACE. ALL IN ALL IT LOOKS VERY MUCH LIKE
A WET SATURDAY.
BOYD
PREV DISCUSSION... /ISSUED 716 AM CDT SAT APR 27 2013/
UPDATE...FOR 12Z AVIATION FORECAST
AVIATION...TODAY WILL BE CHARACTERIZED BY STRONG WARM ADVECTION
IN A VERY MOIST AIRMASS AS UPPER LEVEL LOW OVER KS MOVES SLOWLY
INTO MO. NUMEROUS SHOWERS AND SOME THUNDERSTORMS...ALONG WITH LOW
CIGS AND 3 TO 5 MILE VSBYS...WILL SPREAD ACROSS CKV...BNA...AND
CSV THIS MORNING. MUCH OF THE RAIN WILL DIMINISH BY 18Z AT CKV
.BY 20Z AT BNA...AND BY 22Z AT CSV. HOWEVER...SHOWERS AND STORMS
WILL RETURN OVERNIGHT ACROSS THE ENTIRE REGION AS UPPER TROF
MOVES FROM MO EASTWARD THROUGH THE OHIO VALLEY. A TRAILING WEAK COLD
FRONT WILL MOVE THROUGH MIDDLE TN ON SUNDAY AS THE UPPER TROF
HEADS TOWARD THE GREAT LAKES.
PREV DISCUSSION... /ISSUED 417 AM CDT SAT APR 27 2013/
SLIGHT RISK OF SEVERE STORMS THIS AFTERNOON AND TONIGHT...
WIDESPREAD RAIN AND THUNDERSTORMS TO CONTINUE THIS WEEKEND...
SHORT TERM...
LATEST RADAR IMAGERY SHOWS WIDESPREAD LIGHT TO MODERATE RAIN
CONTINUES ACROSS MOST OF THE FORECAST AREA...WITH MORE ISOLATED
SHOWERS ACROSS WAYNE/LAWRENCE/GILES COUNTIES. PRECIPITATION
IS BEING AIDED BY A WEAK SHORTWAVE TROUGH EVIDENT ACROSS EASTERN
TENNESSEE...AND IS FOCUSED ALONG AND NORTH OF A 850 MB WARM FRONT
THAT CURRENTLY EXTENDS FROM DYERSBURG TO WINCHESTER. PRECIPITATION
WILL CONTINUE TO BE GENERATED TODAY DUE TO SUSTAINED WAA ABOVE
THE FRONTAL SURFACE...WITH RENEWED DEVELOPMENT TO OUR WEST AS THE
NEXT WEAK SHORTWAVE CURRENTLY SEEN ALONG THE MISSISSIPPI RIVER
APPROACHES. INDEED...MOSAIC RADAR IMAGERY SHOWS A LARGE AREA OF
SHOWERS AND THUNDERSTORMS HAS ALREADY REDEVELOPED IN WESTERN
TENNESSEE WHICH WILL MOVE ACROSS THE CWA LATER THIS MORNING.
HEAVIEST ACTIVITY IS EXPECTED TO BE IN AN ARC FROM NORTHWEST TO
SOUTHEAST ACROSS THE CENTER OF THE CWA...WITH FAR SOUTHWEST AND
NORTHEAST AREAS SEEING MORE SCATTERED ACTIVITY.
BY AFTERNOON...SOME GLOBAL AND MESOSCALE MODELS DEPICT A BREAK IN
THE WIDESPREAD RAINFALL AS SHORTWAVE CURRENTLY ALONG THE MS RIVER
MOVES OFF TO THE EAST. HAVE THUS LOWERED POPS INTO THE LIKELY
CATEGORY THIS AFTERNOON...BUT REMAINS UNCERTAIN HOW MUCH OF A
BREAK WILL BE SEEN AS OTHER MODELS SUCH AS THE HRRR CONTINUE
PRECIPITATION NONSTOP. REGARDLESS...MAIN UPPER LOW SEEN ON WATER
VAPOR IMAGERY ACROSS OK/KS WILL APPROACH THE MISSISSIPPI RIVER
LATER THIS AFTERNOON AND EVENING. AS THIS OCCURS...A WEAK SURFACE
LOW IS PROGGED BY MODELS TO DEVELOP IN NORTHEAST ARKANSAS THEN
MOVE NORTHEAST INTO SOUTHERN KENTUCKY TONIGHT. STRENGTHENING WIND
FIELDS AND HIGHER SURFACE DEWPOINTS ADVECTING NORTHWARD COMBINED
WITH SOME DIURNAL HEATING SHOULD ALLOW FOR DESTABILIZATION OF THE
LOWER LEVELS OVER WESTERN ZONES. ALL GUIDANCE DEVELOPS ADDITIONAL
SHOWERS AND THUNDERSTORMS LATER THIS AFTERNOON AND EVENING ACROSS
WEST TENNESSEE AND NORTH MISSISSIPPI WHICH THEN MOVE INTO THE MID
STATE THROUGH SATURDAY NIGHT. FORECAST SOUNDINGS SHOW WEAK TO
MODERATE INSTABILITY/SHEAR WITH RELATIVELY COLD MID
LEVELS LATER TODAY...SUGGESTING DAMAGING WINDS AND LARGE HAIL
WOULD BE POSSIBLE WITH THE STRONGEST STORMS. INDEED...MESOSCALE
MODELS SHOW SOME ROBUST STORMS IN OUR WESTERN COUNTIES AROUND 00Z
THIS EVENING. SPC HAS UPGRADED PORTIONS OF WESTERN ZONES INTO A
SLIGHT RISK FOR THIS AFTERNOON AND TONIGHT. EASTWARD EXTENT OF ANY
SEVERE ACTIVITY THAT MAY DEVELOP WILL BE GREATLY LIMITED BY MORE
STABLE CONDITIONS EAST OF THE SLIGHT RISK AREA.
GUIDANCE DEPICTS A DRY SLOT ALOFT ADVANCING ACROSS WESTERN
PORTIONS OF THE MID STATE ON SUNDAY AS UPPER LOW ADVANCES THROUGH
THE OHIO VALLEY. THIS WILL LOWER PRECIP CHANCES OVER THE WEST WITH
HIGH POPS CONTINUING OVER THE EAST. ALL ACTIVITY SHOULD WIND DOWN
BY SUNDAY NIGHT AS UPPER LOW MOVES EAST OF THE REGION. TOTAL
RAINFALL AMOUNTS FOR THIS WEEKEND RAIN EVENT APPEAR TO BE IN THE 1
TO 2 INCH RANGE NORTH OF I-40 WITH 2 TO 3 INCHES SOUTH OF
I-40...BUT SOME 4 INCH AMOUNTS ARE POSSIBLE WITH ANY SUSTAINED
HEAVIER THUNDERSTORMS. ALTHOUGH NO WIDESPREAD FLASH FLOODING IS
EXPECTED...SOME LOCALIZED FLOODING IS CERTAINLY POSSIBLE AND
RUNOFF INTO AREA RIVERS MAY RESULT IN SOME RISING INTO ACTION
STAGE NEXT WEEK.
LONG TERM...
WARMER AND DRIER WEATHER IS ANTICIPATED FOR MONDAY AND TUESDAY AS
WEAK RIDGING ALOFT BUILDS OVER THE TENNESSEE VALLEY REGION. LOW
PRECIP CHANCES RETURN BY WEDNESDAY AS A WEAK UPPER LOW DEVELOPS
IN THE GULF COAST STATES. FOR THE END OF THE FORECAST
PERIOD...00Z GFS/ECMWF HAVE CONTINUED THE HIGHLY ANOMALOUS TREND
OF THE PAST FEW DAYS IN DEVELOPING A LARGE AND INTENSE CUT OFF H5
LOW WHICH THEN MEANDERS FOR DAYS ACROSS THE EASTERN CONUS.
UNFORTUNATELY...GFS AND ECMWF DIFFER BY 600 MILES ON THEIR
PLACEMENT OF THE UPPER LOW WHICH RESULTS IN TEMPERATURE
DIFFERENCES OF 20 DEGREES OR MORE FOR HIGHS AND LOWS. FOR NOW
WILL GO WITH LOW POPS FOR THE END OF NEXT WEEK AND TREND
TEMPERATURES TOWARDS THE COLDER MEX GUIDANCE...ALTHOUGH FORECAST
IN THE LONG RANGE SHOULD BE CONSIDERED EXTREMELY LOW CONFIDENCE.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
12
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
125 PM CDT SAT APR 27 2013
.UPDATE...
A QUICK UPDATE HAS BEEN SENT TO LOWER THIS AFTERNOON/S HIGHS BY A
FEW DEGREES ACROSS THE NORTHERN HALF OF THE FORECAST AREA. HAVE
ALSO TRIMMED THE POPS FROM AREAS NORTH OF A GOLDTHWAITE TO ATHENS
LINE.
58
&&
.AVIATION...
STRATUS BURNING OFF FROM WEST...AND TIMING THE WESTERN EDGE INTO
METROPLEX GIVES VFR CONDITIONS BY 19Z. WACO CURRENTLY CLEAR...BUT
SATELLITE SHOWS SCT VFR CU FAIRLY CLOSE.
METROPLEX EXPECTED TO REMAIN CLEAR THROUGH END OF TAF CYCLE AND
BEYOND...BUT CONVECTION EXPECTED TO DEVELOP SOUTH OF WACO AND
ANVIL SHIELD WILL LIKELY GROW NORTH LATER TODAY THROUGH MOST OF
THE NIGHT. THERE REMAINS A LOW THREAT OF THUNDER/SHOWERS
OVERNIGHT...BUT BASED ON HI RES GUIDANCE FEEL THAT RAIN WILL STAY
SOUTH OF THE WACO AIRPORT.
SOUTH FLOW RETURNS TOMORROW. 84
&&
.PREV UPDATE...
.UPDATE...
A COLD FRONT EXTENDED FROM JUST WEST OF PARIS TO SOUTHEAST OF
GREENVILLE...TERRELL...WEST...GATESVILLE AND LAMPASAS AT 16Z.
THIS FRONT WILL MOVE THROUGH WACO IN THE NEXT HALF HOUR...BUT
STALL OUT OVER THE SOUTHEASTERN PART OF THE FORECAST AREA THIS
AFTERNOON. HAVE ADJUSTED THE HOURLY WIND/TEMPERATURE/DEW POINT
GRIDS BASED ON THE LATEST RUC GUIDANCE WHICH SEEMS TO BE IN LINE
WITH ONGOING TRENDS.
THE 06Z TEXAS TECH WRF AND THE LATEST /12Z/ HIGH RESOLUTION RAPID
REFRESH...INDICATE THAT MOST OF THE SHOWERS AND THUNDERSTORMS
WILL BE TO THE SOUTH OF THE FORECAST AREA THIS AFTERNOON WITH A
LITTLE MORE MOVING INTO THE SOUTHEASTERN ZONES AFTER 23Z. FOR
NOW...HAVE LEFT POPS AS IS...BUT WE MAY BE ABLE TO TRIM A LITTLE
OFF LATER THIS AFTERNOON DEPENDING ON EXACTLY WHERE THE FRONT
STALLS.
58
&&
.PREV DISCUSSION... /ISSUED 415 AM CDT SAT APR 27 2013/
EARLY MORNING WATER VAPOR IMAGERY DEPICTED A CYCLONIC CIRCULATION
CENTERED OVER SOUTH CENTRAL KS OR NORTH CENTRAL OK MOVING EAST.
THIS CIRCULATION WAS LOCATED ON THE EAST END OF A POSITIVELY
TILTED CYCLONIC SHEAR AXIS EXTENDING WSW OVER THE TX PANHANDLE AND
OVER WEST CENTRAL AZ. TO THE EAST OF THE KS/OK UPPER LOW WAS A
LINE OF LOOSELY ORGANIZED THUNDERSTORMS LOCATED FROM NORTHWESTERN
AR SOUTHWEST TO SOUTHEAST OK. 08Z /3AM/ SURFACE OBSERVATIONS
DEPICTED A COLD FRONT LOCATED NEAR A BOWIE TO PK LAKE TO COMANCHE
LINE MOVING SOUTHEAST. THE FWD 00Z RAOB INDICATED A SUBSTANTIAL
CAP IN PLACE OVER NORTH TX...AND THIS CAP WAS LIKELY RESPONSIBLE
FOR THE DEARTH OF PRECIPITATION ALONG THE PORTION OF THE FRONT IN
TEXAS EARLY THIS MORNING.
TODAY AND TONIGHT...GUIDANCE CONSISTENTLY INDICATES THAT THE
CYCLONIC CIRCULATION/UPPER LOW OVER THE KS/OK BORDER EARLY THIS
MORNING WILL DEEPEN INTO A CLOSED LOW WHILE MOVING EAST OVER THE
NEXT 24 HRS. THIS WILL CAUSE THE CYCLONIC SHEAR AXIS TO SWING
SOUTHEAST IN ITS WAKE OVER THE CWA LATE THIS AFTERNOON THROUGH THE
OVERNIGHT HRS. THE EVOLUTION OF THIS UPPER LEVEL SYSTEM WILL HAVE
SOME INTERESTING IMPACTS ON SURFACE FEATURES ACROSS NORTH AND
CENTRAL TX TODAY.
THE SURFACE LOW THAT WAS LOCATED JUST EAST OF WICHITA FALLS AT THE
TIME OF THIS DISCUSSION IS EXPECTED TO MOVE EAST NORTHEAST WITH
THE MAIN UPPER LOW OVER THE NEXT 24 HRS. THIS WILL CAUSE THE COLD
FRONT TO CONTINUE SOUTH ACROSS THE CWA THROUGH THIS AFTERNOON. AS
THE SURFACE LOW IS MOVING EAST ACROSS AR TODAY ANOTHER SURFACE LOW
IS EXPECTED TO DEVELOP OVER NORTHERN MEXICO TO THE WEST OF DEL RIO
IN RESPONSE TO THE CYCLONIC SHEAR AXIS MOVING SOUTHEAST. WITH A
NEW SURFACE LOW DEVELOPING TO THE SOUTHWEST...AND THE OTHER
SURFACE LOW MOVING OFF TO THE EAST...THE COLD FRONT WILL LIKELY
STALL OUT NEAR OR JUST SOUTHEAST OF A LINE FROM ATHENS TO WACO BY
THE MID-AFTERNOON HOURS.
OVERNIGHT MODELS ARE STILL NOT IN COMPLETE AGREEMENT AS TO WHERE
THE FRONT WILL COME TO A REST...BUT SOMEWHERE BETWEEN WACO AND
COLLEGE STATION IS THE CONSENSUS LOCATION. WHEREVER THE FRONT
STALLS...WITH LOW PRESSURE OFF TO THE NORTHEAST AND
SOUTHWEST...THE GENERAL LOW LEVEL WIND FIELD LOOKS TO BE
DOMINATED BY VERY WEAK DEFORMATION ON EITHER SIDE OF THE STALLED
FRONT THIS AFTERNOON. WEAK NORTHEAST WINDS NORTH OF THE FRONT AND
WEAK SOUTHWEST WINDS TO THE SOUTH WILL ACTUALLY MINIMIZE PURE
CONVERGENCE ALONG THE FRONT...MAKING IT VERY DIFFICULT TO
DETERMINE IF THE FRONT WILL BE AN IMPORTANT SOURCE OF LIFT THIS
AFTERNOON.
TEMPERATURES WILL GENERALLY BE WARMER SOUTHEAST OF THE
FRONT...BUT THE GULF MOISTURE IN PLACE WILL ACTUALLY SUPPORT
CLOUDIER CONDITIONS TO THE SOUTHEAST OF THE FRONT THIS AFTERNOON.
DRIER AIR TO THE NORTH COMBINED WITH SUBSIDENCE IN THE WAKE OF THE
DEPARTING UPPER LOW WILL CAUSE SKIES TO CLEAR OUT NORTH OF THE
FRONT. AFTERNOON SUNSHINE WILL WEAKEN THE TEMPERATURE GRADIENT
ALONG THE FRONT...REDUCING FRONTOGENETIC FORCING DURING THE PEAK
HEATING HRS OF THE DAY. AS A RESULT THINK MESOSCALE FORCING FOR
ASCENT ALONG THE FRONT WILL BE FAIRLY WEAK THIS AFTERNOON...
REDUCING CONFIDENCE IN CONVECTION INITIATION ALONG THE STALLED OUT
FRONT DURING THE PEAK HEATING HRS OF THE DAY.
AS A RESULT...BUMPED POPS DOWN A LITTLE BIT THRU SUNSET FOR
LOCATIONS ALONG AND SOUTH OF A LINE FROM COMANCHE TO CANTON.
GUIDANCE CONTINUES TO INDICATE THAT THERE WILL BE OVER 2000 J/KG
OF CAPE AVAILABLE FOR FREE CONVECTION IF STORMS CAN DEVELOP ALONG
THE FRONT. THEREFORE DESPITE THE LOW POPS...WILL CONTINUE TO
MENTION A CHANCE OF STRONG TO SEVERE STORMS AS ANYTHING THAT DOES
MANAGE TO DEVELOP WILL LIKELY BE QUITE STRONG THIS AFTERNOON.
DAMAGING WINDS AND LARGE HAIL WOULD BE THE MOST LIKELY HAZARDS IF
ANYTHING WERE ABLE TO DEVELOP ALONG THE FRONT THRU SUNSET.
TONIGHT...THE DRIER AIR TO THE NORTH WILL ACTUALLY HELP INCREASE
THE THERMAL GRADIENT ALONG THE STALLED OUT FRONT AS THIS AIR WILL
COOL MORE QUICKLY THAN THE CLOUDY AND MORE MOIST AIRMASS TO THE
SOUTH OF THE FRONT. AS A RESULT...EVEN THOUGH THIS SEEMS
COUNTER-INTUITIVE...OUR BEST CHANCES FOR STORMS ALONG THE FRONT MAY
BE WELL AFTER SUNSET TONIGHT. MODELS DO NOT REALLY INDICATE A BIG
INCREASE IN CONVERGENCE ALONG THE FRONT...BUT THE INCREASE IN THE
THERMAL GRADIENT WILL LEAD TO STRONGER MESOSCALE FORCING FOR
ASCENT. THIS COMBINED WITH THE MEAGER LARGE SCALE SUPPORT OFFERED
BY THE CYCLONIC SHEAR AXIS MOVING OVER THE REGION HAS CONFIDENCE A
BIT HIGHER IN STORMS ALONG THE FRONT AFTER SUNSET. AS A RESULT
WENT AHEAD AND BUMPED UP POPS FROM 00-12Z ALONG THE FRONT FOR
TONIGHT. SEVERE WEATHER CHANCES WILL NOT BE AS GREAT AFTER
SUNSET...HOWEVER LARGE HAIL IS STILL A POSSIBILITY WITH THE
STRONGEST STORMS. ANY STORMS THAT DEVELOP WILL LIKELY MOVE
PARALLEL TO THE FRONT...SO THERE IS A RISK FOR LOCALLY HEAVY
RAINFALL DUE TO THE POTENTIAL FOR STORMS TO TRAIN ALONG THE FRONT
TONIGHT. THAT SAID...POPS ARE ONLY IN THE 30 TO 40 PERCENT CHANCE
RANGE...SO IT IS STILL POSSIBLE THAT FORCING REMAINS TOO WEAK FOR
ANYTHING ALONG THE FRONT OVERNIGHT.
SUNDAY THROUGH TUESDAY...GUIDANCE INDICATES THAT WEAK UPPER LEVEL
RIDGING WILL BUILD OVER THE NORTHERN PORTIONS OF THE SOUTH PLAINS
DURING THE PERIOD WHICH SHOULD HELP KEEP US DRY. THE ECMWF
STUBBORNLY INDICATES THAT THE TAILING END OF THE CYCLONIC SHEAR
AXIS MOVING SOUTH OVER TX TONIGHT WILL BECOME ISOLATED FROM THE
DEPARTING UPPER LOW/SHEAR AXIS AND FORM A WEAK CUT-OFF UPPER LOW
OVER THE TX GULF COAST DURING THIS PERIOD. BASED ON THE ECMWFS
EVOLUTION AND TRACK OF THIS FEATURE...IT IS SOMEWHAT
INCONSEQUENTIAL TO NORTH AND CENTRAL TX AS WE WOULD REMAIN NORTH
OR NORTHWEST OF THIS UPPER LOW THRU THE PERIOD. THE ECMWF HAS BEEN
CONSISTENT WITH THIS FEATURE...SO CONFIDENCE IS HIGHER THAT IT
WILL DEVELOP...HOWEVER THIS SHOULD JUST REINFORCE RIDGING OVER THE
CWA INCREASING CONFIDENCE IN A DRY FORECAST FROM SUNDAY AFTERNOON
THRU TUESDAY. EVEN IF THE UPPER LOW DEVELOPS...IT IS EXPECTED TO
REMAIN TOO WEAK TO HAVE A LARGE IMPACT ON THE SURFACE PRESSURE
PATTERN...THEREFORE WE SHOULD REMAIN IN SOUTHERLY FLOW DUE TO LEE
SIDE TROUGHING IN RESPONSE TO A POWERFUL UPPER LOW EXPECTED TO
SWING INTO THE PLAINS MID-WEEK. SOUTH WINDS AND SUBSIDENCE ALOFT
SHOULD HELP US BRING TEMPERATURES UP INTO THE 80S DURING THIS
PERIOD.
MID-WEEK...MEDIUM RANGE GUIDANCE CONTINUES TO STRUGGLE ON THE
EXACT EVOLUTION OF THE POWERFUL SYSTEM PROGGED TO MOVE OVER THE
PLAINS WEDNESDAY OR WEDNESDAY NIGHT. ASIDE FROM THE FAIRLY LARGE
PLACEMENT DISCREPANCIES BETWEEN THE GFS AND CANADIAN/ECMWF ALL
GUIDANCE AGREES THAT THIS UPPER LEVEL SYSTEM WILL BE UNSEASONABLY
STRONG AND MAY LEAD TO AN EXTENDED PERIOD OF BELOW NORMAL
TEMPERATURES FOR NORTH TX FOR THE FIRST SEVERAL DAYS OF MAY. THIS
FORECAST IS MOST IN LINE WITH THE CONSENSUS OF THE ECMWF/CANADIAN
OPERATIONAL MODELS THAT WERE VALID AT 27/00Z. THESE MODELS BRING
THE INITIAL UPPER LEVEL LOW OVER THE SOUTH PLAINS DRIVING A STRONG
COLD FRONT SOUTH ACROSS NORTH TX LATE WEDNESDAY AFTERNOON THRU THE
OVERNIGHT HRS.
ASSUMING THE UPPER LOW DIGS AS FAR SOUTH AS THESE MODELS
INDICATE...ALMOST ALL OF THE CWA WILL SEE SOME RAIN/THUNDERSTORMS
ALONG THE COLD FRONT AS IT MOVES THROUGH. DID NOT GO CRAZY WITH
THE POPS YET BECAUSE THE GFS CONTINUES TO INDICATE THAT THE UPPER
LOW WILL REMAIN SIGNIFICANTLY FURTHER NORTH...REDUCING
PRECIPITATION CHANCES ALONG THE FRONT. WENT AHEAD WITH 40 POPS
ALONG AND BEHIND THE FRONT WITH THIS FORECAST...BUT POPS MAY NEED
TO BE MUCH HIGHER IF THE CMC/ECMWF TRACK VERIFIES. ITS TOO EARLY
TO DETERMINE SEVERE WEATHER CHANCES...HOWEVER A LARGE OUTBREAK
DOES NOT LOOK LIKELY BECAUSE THE FRONT IS EXPECTED TO MOVE SOUTH
VERY QUICKLY WEDNESDAY AFTERNOON UNDERCUTTING MOST ORGANIZED
CONVECTION THAT INITIATES JUST OUT AHEAD OF THE FRONT.
EXTENDED...THE ECMWF INDICATES THAT A BIG BLOCKING PATTERN SETS
UP AFTER THE UPPER LOW MOVES INTO THE PLAINS FOR THE END OF THE
WEEK. THIS KEEPS THE UPPER LOW IN PLACE OVER THE CENTRAL PLAINS
THRU AT LEAST MAY 5TH...WHICH WOULD TEND TO KEEP TEMPERATURES
BELOW NORMAL OVER MOST OF THE CENTRAL AND SOUTHERN PLAINS THRU THE
FIRST WEEK OF MAY. THE COLDEST TEMPERATURES WOULD BE RIGHT AFTER
THE COLD FRONT...WITH TEMPERATURES MODERATING THEREAFTER AS THE
UPPER LOW DRIFTS NORTH OF THE CWA. CONFIDENCE IN THIS SOLUTION IS
NOT GREAT...HOWEVER MOST GUIDANCE INDICATES SOME SORT OF BLOCKING
PATTERN FOR LATE IN THE WEEK INTO NEXT WEEKEND...SO THE MAIN
FORECAST CONCERN IS WHERE WILL THE UPPER LOW BE WHEN THE BLOCKING
PATTERN SETS UP. AT THIS TIME KEPT TEMPERATURES BELOW NORMAL
DURING THIS PERIOD AS THERE IS NO GUIDANCE THAT SHOWS WE GET STUCK
IN A BLOCKING PATTERN WITH UPPER LEVEL RIDGING OVER THE PLAINS.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 56 81 59 86 62 / 5 5 0 0 0
WACO, TX 60 81 57 85 60 / 30 10 0 0 0
PARIS, TX 52 79 52 82 57 / 5 5 0 0 0
DENTON, TX 53 81 55 86 59 / 5 5 0 0 0
MCKINNEY, TX 53 80 56 85 60 / 5 5 0 0 0
DALLAS, TX 56 83 61 86 65 / 10 5 0 0 0
TERRELL, TX 54 81 55 84 59 / 10 5 0 0 0
CORSICANA, TX 59 81 58 83 60 / 20 5 0 0 0
TEMPLE, TX 62 80 58 84 59 / 40 20 0 0 0
MINERAL WELLS, TX 54 83 56 85 59 / 5 5 0 0 0
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/58
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1233 PM CDT SAT APR 27 2013
.AVIATION...
STRATUS BURNING OFF FROM WEST...AND TIMING THE WESTERN EDGE INTO
METROPLEX GIVES VFR CONDITIONS BY 19Z. WACO CURRENTLY CLEAR...BUT
SATELLITE SHOWS SCT VFR CU FAIRLY CLOSE.
METROPLEX EXPECTED TO REMAIN CLEAR THROUGH END OF TAF CYCLE AND
BEYOND...BUT CONVECTION EXPECTED TO DEVELOP SOUTH OF WACO AND
ANVIL SHIELD WILL LIKELY GROW NORTH LATER TODAY THROUGH MOST OF
THE NIGHT. THERE REMAINS A LOW THREAT OF THUNDER/SHOWERS
OVERNIGHT...BUT BASED ON HI RES GUIDANCE FEEL THAT RAIN WILL STAY
SOUTH OF THE WACO AIRPORT.
SOUTH FLOW RETURNS TOMORROW. 84
&&
.UPDATE...
A COLD FRONT EXTENDED FROM JUST WEST OF PARIS TO SOUTHEAST OF
GREENVILLE...TERRELL...WEST...GATESVILLE AND LAMPASAS AT 16Z.
THIS FRONT WILL MOVE THROUGH WACO IN THE NEXT HALF HOUR...BUT
STALL OUT OVER THE SOUTHEASTERN PART OF THE FORECAST AREA THIS
AFTERNOON. HAVE ADJUSTED THE HOURLY WIND/TEMPERATURE/DEW POINT
GRIDS BASED ON THE LATEST RUC GUIDANCE WHICH SEEMS TO BE IN LINE
WITH ONGOING TRENDS.
THE 06Z TEXAS TECH WRF AND THE LATEST /12Z/ HIGH RESOLUTION RAPID
REFRESH...INDICATE THAT MOST OF THE SHOWERS AND THUNDERSTORMS
WILL BE TO THE SOUTH OF THE FORECAST AREA THIS AFTERNOON WITH A
LITTLE MORE MOVING INTO THE SOUTHEASTERN ZONES AFTER 23Z. FOR
NOW...HAVE LEFT POPS AS IS...BUT WE MAY BE ABLE TO TRIM A LITTLE
OFF LATER THIS AFTERNOON DEPENDING ON EXACTLY WHERE THE FRONT
STALLS.
58
&&
.PREV DISCUSSION... /ISSUED 415 AM CDT SAT APR 27 2013/
EARLY MORNING WATER VAPOR IMAGERY DEPICTED A CYCLONIC CIRCULATION
CENTERED OVER SOUTH CENTRAL KS OR NORTH CENTRAL OK MOVING EAST.
THIS CIRCULATION WAS LOCATED ON THE EAST END OF A POSITIVELY
TILTED CYCLONIC SHEAR AXIS EXTENDING WSW OVER THE TX PANHANDLE AND
OVER WEST CENTRAL AZ. TO THE EAST OF THE KS/OK UPPER LOW WAS A
LINE OF LOOSELY ORGANIZED THUNDERSTORMS LOCATED FROM NORTHWESTERN
AR SOUTHWEST TO SOUTHEAST OK. 08Z /3AM/ SURFACE OBSERVATIONS
DEPICTED A COLD FRONT LOCATED NEAR A BOWIE TO PK LAKE TO COMANCHE
LINE MOVING SOUTHEAST. THE FWD 00Z RAOB INDICATED A SUBSTANTIAL
CAP IN PLACE OVER NORTH TX...AND THIS CAP WAS LIKELY RESPONSIBLE
FOR THE DEARTH OF PRECIPITATION ALONG THE PORTION OF THE FRONT IN
TEXAS EARLY THIS MORNING.
TODAY AND TONIGHT...GUIDANCE CONSISTENTLY INDICATES THAT THE
CYCLONIC CIRCULATION/UPPER LOW OVER THE KS/OK BORDER EARLY THIS
MORNING WILL DEEPEN INTO A CLOSED LOW WHILE MOVING EAST OVER THE
NEXT 24 HRS. THIS WILL CAUSE THE CYCLONIC SHEAR AXIS TO SWING
SOUTHEAST IN ITS WAKE OVER THE CWA LATE THIS AFTERNOON THROUGH THE
OVERNIGHT HRS. THE EVOLUTION OF THIS UPPER LEVEL SYSTEM WILL HAVE
SOME INTERESTING IMPACTS ON SURFACE FEATURES ACROSS NORTH AND
CENTRAL TX TODAY.
THE SURFACE LOW THAT WAS LOCATED JUST EAST OF WICHITA FALLS AT THE
TIME OF THIS DISCUSSION IS EXPECTED TO MOVE EAST NORTHEAST WITH
THE MAIN UPPER LOW OVER THE NEXT 24 HRS. THIS WILL CAUSE THE COLD
FRONT TO CONTINUE SOUTH ACROSS THE CWA THROUGH THIS AFTERNOON. AS
THE SURFACE LOW IS MOVING EAST ACROSS AR TODAY ANOTHER SURFACE LOW
IS EXPECTED TO DEVELOP OVER NORTHERN MEXICO TO THE WEST OF DEL RIO
IN RESPONSE TO THE CYCLONIC SHEAR AXIS MOVING SOUTHEAST. WITH A
NEW SURFACE LOW DEVELOPING TO THE SOUTHWEST...AND THE OTHER
SURFACE LOW MOVING OFF TO THE EAST...THE COLD FRONT WILL LIKELY
STALL OUT NEAR OR JUST SOUTHEAST OF A LINE FROM ATHENS TO WACO BY
THE MID-AFTERNOON HOURS.
OVERNIGHT MODELS ARE STILL NOT IN COMPLETE AGREEMENT AS TO WHERE
THE FRONT WILL COME TO A REST...BUT SOMEWHERE BETWEEN WACO AND
COLLEGE STATION IS THE CONSENSUS LOCATION. WHEREVER THE FRONT
STALLS...WITH LOW PRESSURE OFF TO THE NORTHEAST AND
SOUTHWEST...THE GENERAL LOW LEVEL WIND FIELD LOOKS TO BE
DOMINATED BY VERY WEAK DEFORMATION ON EITHER SIDE OF THE STALLED
FRONT THIS AFTERNOON. WEAK NORTHEAST WINDS NORTH OF THE FRONT AND
WEAK SOUTHWEST WINDS TO THE SOUTH WILL ACTUALLY MINIMIZE PURE
CONVERGENCE ALONG THE FRONT...MAKING IT VERY DIFFICULT TO
DETERMINE IF THE FRONT WILL BE AN IMPORTANT SOURCE OF LIFT THIS
AFTERNOON.
TEMPERATURES WILL GENERALLY BE WARMER SOUTHEAST OF THE
FRONT...BUT THE GULF MOISTURE IN PLACE WILL ACTUALLY SUPPORT
CLOUDIER CONDITIONS TO THE SOUTHEAST OF THE FRONT THIS AFTERNOON.
DRIER AIR TO THE NORTH COMBINED WITH SUBSIDENCE IN THE WAKE OF THE
DEPARTING UPPER LOW WILL CAUSE SKIES TO CLEAR OUT NORTH OF THE
FRONT. AFTERNOON SUNSHINE WILL WEAKEN THE TEMPERATURE GRADIENT
ALONG THE FRONT...REDUCING FRONTOGENETIC FORCING DURING THE PEAK
HEATING HRS OF THE DAY. AS A RESULT THINK MESOSCALE FORCING FOR
ASCENT ALONG THE FRONT WILL BE FAIRLY WEAK THIS AFTERNOON...
REDUCING CONFIDENCE IN CONVECTION INITIATION ALONG THE STALLED OUT
FRONT DURING THE PEAK HEATING HRS OF THE DAY.
AS A RESULT...BUMPED POPS DOWN A LITTLE BIT THRU SUNSET FOR
LOCATIONS ALONG AND SOUTH OF A LINE FROM COMANCHE TO CANTON.
GUIDANCE CONTINUES TO INDICATE THAT THERE WILL BE OVER 2000 J/KG
OF CAPE AVAILABLE FOR FREE CONVECTION IF STORMS CAN DEVELOP ALONG
THE FRONT. THEREFORE DESPITE THE LOW POPS...WILL CONTINUE TO
MENTION A CHANCE OF STRONG TO SEVERE STORMS AS ANYTHING THAT DOES
MANAGE TO DEVELOP WILL LIKELY BE QUITE STRONG THIS AFTERNOON.
DAMAGING WINDS AND LARGE HAIL WOULD BE THE MOST LIKELY HAZARDS IF
ANYTHING WERE ABLE TO DEVELOP ALONG THE FRONT THRU SUNSET.
TONIGHT...THE DRIER AIR TO THE NORTH WILL ACTUALLY HELP INCREASE
THE THERMAL GRADIENT ALONG THE STALLED OUT FRONT AS THIS AIR WILL
COOL MORE QUICKLY THAN THE CLOUDY AND MORE MOIST AIRMASS TO THE
SOUTH OF THE FRONT. AS A RESULT...EVEN THOUGH THIS SEEMS
COUNTER-INTUITIVE...OUR BEST CHANCES FOR STORMS ALONG THE FRONT MAY
BE WELL AFTER SUNSET TONIGHT. MODELS DO NOT REALLY INDICATE A BIG
INCREASE IN CONVERGENCE ALONG THE FRONT...BUT THE INCREASE IN THE
THERMAL GRADIENT WILL LEAD TO STRONGER MESOSCALE FORCING FOR
ASCENT. THIS COMBINED WITH THE MEAGER LARGE SCALE SUPPORT OFFERED
BY THE CYCLONIC SHEAR AXIS MOVING OVER THE REGION HAS CONFIDENCE A
BIT HIGHER IN STORMS ALONG THE FRONT AFTER SUNSET. AS A RESULT
WENT AHEAD AND BUMPED UP POPS FROM 00-12Z ALONG THE FRONT FOR
TONIGHT. SEVERE WEATHER CHANCES WILL NOT BE AS GREAT AFTER
SUNSET...HOWEVER LARGE HAIL IS STILL A POSSIBILITY WITH THE
STRONGEST STORMS. ANY STORMS THAT DEVELOP WILL LIKELY MOVE
PARALLEL TO THE FRONT...SO THERE IS A RISK FOR LOCALLY HEAVY
RAINFALL DUE TO THE POTENTIAL FOR STORMS TO TRAIN ALONG THE FRONT
TONIGHT. THAT SAID...POPS ARE ONLY IN THE 30 TO 40 PERCENT CHANCE
RANGE...SO IT IS STILL POSSIBLE THAT FORCING REMAINS TOO WEAK FOR
ANYTHING ALONG THE FRONT OVERNIGHT.
SUNDAY THROUGH TUESDAY...GUIDANCE INDICATES THAT WEAK UPPER LEVEL
RIDGING WILL BUILD OVER THE NORTHERN PORTIONS OF THE SOUTH PLAINS
DURING THE PERIOD WHICH SHOULD HELP KEEP US DRY. THE ECMWF
STUBBORNLY INDICATES THAT THE TAILING END OF THE CYCLONIC SHEAR
AXIS MOVING SOUTH OVER TX TONIGHT WILL BECOME ISOLATED FROM THE
DEPARTING UPPER LOW/SHEAR AXIS AND FORM A WEAK CUT-OFF UPPER LOW
OVER THE TX GULF COAST DURING THIS PERIOD. BASED ON THE ECMWFS
EVOLUTION AND TRACK OF THIS FEATURE...IT IS SOMEWHAT
INCONSEQUENTIAL TO NORTH AND CENTRAL TX AS WE WOULD REMAIN NORTH
OR NORTHWEST OF THIS UPPER LOW THRU THE PERIOD. THE ECMWF HAS BEEN
CONSISTENT WITH THIS FEATURE...SO CONFIDENCE IS HIGHER THAT IT
WILL DEVELOP...HOWEVER THIS SHOULD JUST REINFORCE RIDGING OVER THE
CWA INCREASING CONFIDENCE IN A DRY FORECAST FROM SUNDAY AFTERNOON
THRU TUESDAY. EVEN IF THE UPPER LOW DEVELOPS...IT IS EXPECTED TO
REMAIN TOO WEAK TO HAVE A LARGE IMPACT ON THE SURFACE PRESSURE
PATTERN...THEREFORE WE SHOULD REMAIN IN SOUTHERLY FLOW DUE TO LEE
SIDE TROUGHING IN RESPONSE TO A POWERFUL UPPER LOW EXPECTED TO
SWING INTO THE PLAINS MID-WEEK. SOUTH WINDS AND SUBSIDENCE ALOFT
SHOULD HELP US BRING TEMPERATURES UP INTO THE 80S DURING THIS
PERIOD.
MID-WEEK...MEDIUM RANGE GUIDANCE CONTINUES TO STRUGGLE ON THE
EXACT EVOLUTION OF THE POWERFUL SYSTEM PROGGED TO MOVE OVER THE
PLAINS WEDNESDAY OR WEDNESDAY NIGHT. ASIDE FROM THE FAIRLY LARGE
PLACEMENT DISCREPANCIES BETWEEN THE GFS AND CANADIAN/ECMWF ALL
GUIDANCE AGREES THAT THIS UPPER LEVEL SYSTEM WILL BE UNSEASONABLY
STRONG AND MAY LEAD TO AN EXTENDED PERIOD OF BELOW NORMAL
TEMPERATURES FOR NORTH TX FOR THE FIRST SEVERAL DAYS OF MAY. THIS
FORECAST IS MOST IN LINE WITH THE CONSENSUS OF THE ECMWF/CANADIAN
OPERATIONAL MODELS THAT WERE VALID AT 27/00Z. THESE MODELS BRING
THE INITIAL UPPER LEVEL LOW OVER THE SOUTH PLAINS DRIVING A STRONG
COLD FRONT SOUTH ACROSS NORTH TX LATE WEDNESDAY AFTERNOON THRU THE
OVERNIGHT HRS.
ASSUMING THE UPPER LOW DIGS AS FAR SOUTH AS THESE MODELS
INDICATE...ALMOST ALL OF THE CWA WILL SEE SOME RAIN/THUNDERSTORMS
ALONG THE COLD FRONT AS IT MOVES THROUGH. DID NOT GO CRAZY WITH
THE POPS YET BECAUSE THE GFS CONTINUES TO INDICATE THAT THE UPPER
LOW WILL REMAIN SIGNIFICANTLY FURTHER NORTH...REDUCING
PRECIPITATION CHANCES ALONG THE FRONT. WENT AHEAD WITH 40 POPS
ALONG AND BEHIND THE FRONT WITH THIS FORECAST...BUT POPS MAY NEED
TO BE MUCH HIGHER IF THE CMC/ECMWF TRACK VERIFIES. ITS TOO EARLY
TO DETERMINE SEVERE WEATHER CHANCES...HOWEVER A LARGE OUTBREAK
DOES NOT LOOK LIKELY BECAUSE THE FRONT IS EXPECTED TO MOVE SOUTH
VERY QUICKLY WEDNESDAY AFTERNOON UNDERCUTTING MOST ORGANIZED
CONVECTION THAT INITIATES JUST OUT AHEAD OF THE FRONT.
EXTENDED...THE ECMWF INDICATES THAT A BIG BLOCKING PATTERN SETS
UP AFTER THE UPPER LOW MOVES INTO THE PLAINS FOR THE END OF THE
WEEK. THIS KEEPS THE UPPER LOW IN PLACE OVER THE CENTRAL PLAINS
THRU AT LEAST MAY 5TH...WHICH WOULD TEND TO KEEP TEMPERATURES
BELOW NORMAL OVER MOST OF THE CENTRAL AND SOUTHERN PLAINS THRU THE
FIRST WEEK OF MAY. THE COLDEST TEMPERATURES WOULD BE RIGHT AFTER
THE COLD FRONT...WITH TEMPERATURES MODERATING THEREAFTER AS THE
UPPER LOW DRIFTS NORTH OF THE CWA. CONFIDENCE IN THIS SOLUTION IS
NOT GREAT...HOWEVER MOST GUIDANCE INDICATES SOME SORT OF BLOCKING
PATTERN FOR LATE IN THE WEEK INTO NEXT WEEKEND...SO THE MAIN
FORECAST CONCERN IS WHERE WILL THE UPPER LOW BE WHEN THE BLOCKING
PATTERN SETS UP. AT THIS TIME KEPT TEMPERATURES BELOW NORMAL
DURING THIS PERIOD AS THERE IS NO GUIDANCE THAT SHOWS WE GET STUCK
IN A BLOCKING PATTERN WITH UPPER LEVEL RIDGING OVER THE PLAINS.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 79 56 81 59 86 / 10 5 5 0 0
WACO, TX 83 60 81 57 85 / 20 30 10 0 0
PARIS, TX 78 52 79 52 82 / 10 5 5 0 0
DENTON, TX 77 53 81 55 86 / 10 5 5 0 0
MCKINNEY, TX 77 53 80 56 85 / 10 5 5 0 0
DALLAS, TX 80 56 83 61 86 / 10 10 5 0 0
TERRELL, TX 80 54 81 55 84 / 20 10 5 0 0
CORSICANA, TX 83 59 81 58 83 / 20 20 5 0 0
TEMPLE, TX 84 62 80 58 84 / 30 40 20 0 0
MINERAL WELLS, TX 80 54 83 56 85 / 10 5 5 0 0
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/
AREA FORECAST DISCUSSION...UPDATED
NWS AUSTIN/SAN ANTONIO TX
1228 PM CDT SAT APR 27 2013
.AVIATION...
THE PRIMARY CHALLENGE FOR THIS FORECAST PERIOD WILL BE THE TIMING
OF THUNDERSTORMS FOR THIS EVENING INTO EARLY TONIGHT. A WEAK
FRONTAL BOUNDARY IS CURRENTLY MOVING SLOWLY SOUTH ACROSS NORTHERN
PORTIONS OF THE HILL COUNTRY AND WILL CONTINUE TO MOVE SLOWLY
SOUTH THIS AFTERNOON AND THEN BECOME STATIONARY NEAR HIGHWAY 90
THIS EVENING WHILE AN UPPER LEVEL IMPULSE MOVES EASTWARD OUT OF
NORTHERN MEXICO. THIS FRONTAL BOUNDARY AND THE SIERRA MADRE IN
MEXICO WILL BE THE FOCUS AREAS OF CONVECTIVE DEVELOPMENT. THE
UPPER LEVEL DISTURBANCE WILL HELP IN THE PROPAGATION OF CONVECTION
TO THE EAST AND SOUTHEAST OVERNIGHT. CONTINUE TO LIKE THE 00Z ARW
AND 12Z TTU 3KM WRF FOR THUNDERSTORMS TIMING AND WILL USE A BLEND
OF THE TWO. MVFR CIGS CONTINUE TO LIFT LATE THIS MORNING AND
SHOULD SEE VFR CONDITIONS BETWEEN 19Z-20Z. OVERNIGHT WILL SEE MVFR
CIGS DEVELOP 06Z-08Z THEN FALL TO IFR BY 11Z-12Z. SFC WINDS WILL
BE E TO SE AT 5 TO 10 KTS THIS AFTERNOON AND EAST AT 5 TO 8 KTS
OVERNIGHT.
&&
.PREV DISCUSSION... /ISSUED 1046 AM CDT SAT APR 27 2013/
UPDATE...
TO EXTEND SLIGHT RISK OF SEVERE THUNDERSTORMS AND REMOVE MORNING DRIZZLE.
DISCUSSION...
THE MORNING UPDATE FROM SPC EXTENDED THE SLIGHT RISK AREA TO COVER
ALL OF SOUTH CENTRAL TEXAS. EXPECTING CONVECTION TO DEVELOP OVER
THE MEXICAN MOUNTAINS AND ALONG A COLD FRONT LATER THIS EVENING.
THE COLD FRONT IS CURRENTLY LYING JUST NORTH OF OUR NORTHERN CWA
BORDER FROM AROUND LAMPASAS TO SONORA TO SANDERSON. THIS FRONT
WILL DRIFT SOUTHWARD THROUGH THE AFTERNOON AND WILL LIKELY BE THE
FOCUS FOR THUNDERSTORMS. DEW POINTS SOUTH OF THE FRONT ARE IN THE
MID TO UPPER 60S. CLOUD COVER WILL KEEP TEMPERATURES DOWN UNTIL
AFTERNOON AND LIMITING INSTABILITY IN THE BOUNDARY LAYER. FORECAST
SOUNDINGS SHOW CAPE RISING TO 1500-2000 J/KG LATER TODAY. STILL
DISAGREEMENT ON TIMING. GFS IS LATER TO DEVELOP STRONG INSTABILITY
AND THIS SEEMS MORE LIKELY WITH LATER EROSION OF CLOUD DECK.
OUR FORECAST LOOKS TO BE IN GOOD SHAPE WITH MOST CONVECTION AFTER
00Z. HAVE REMOVED MENTION OF MORNING DRIZZLE. DRIZZLE OR SPRINKLES
MAY STILL OCCUR...BUT WILL BE ISOLATED AND NOT WORTH KEEPING IN
FORECAST. HAVE ALSO MADE MINOR ADJUSTMENTS TO HOURLY GRIDS TO
ACCOUNT FOR OBSERVATIONAL TRENDS.
PREV DISCUSSION... /ISSUED 631 AM CDT SAT APR 27 2013/
DISCUSSION...
SEE AVIATION FOR THE 12Z TAF DISCUSSION.
AVIATION...
THE PRIMARY CHALLENGE FOR THIS TAF PACKAGE IS THE TIMING OF THUNDERSTORMS
FOR THIS EVENING INTO EARLY TONIGHT. A WEAK FRONTAL BOUNDARY WILL FILTER
SOUTHWARD ACROSS THE HILL COUNTRY THIS EVENING BECOMING STATIONARY IN
THE VICINITY OF HIGHWAY 90 WHILE AN UPPER LEVEL IMPULSE MOVES EASTWARD
OUT OF MEXICO. THE FRONTAL BOUNDARY AND THE EASTERN SLOPES OF THE SIERRA
MADRE WILL BE THE FOCUS AREAS OF CONVECTIVE DEVELOPMENT. THE UPPER LEVEL
DISTURBANCE WILL HELP IN THE PROPAGATION OF CONVECTION TO THE EAST AND
SOUTHEAST OVERNIGHT. A BLEND OF THE 00Z ARW...07Z RUC13 AND 00Z TTU
3KM WRF WILL BE USED FOR TIMING OF THUNDERSTORMS IMPACTING THE TAF
SITES. OTHERWISE MVFR CIGS WILL PREVAIL THIS MORNING IMPROVING TO VFR
THIS AFTERNOON. CIGS WILL ONCE AGAIN LOWER TO MVFR AFTER 06Z...IFR BY
11Z. SFC WINDS TODAY S TO SE AT 5 TO 10 KTS...BACKING TO THE EAST AT
5 TO 8 KTS OVERNIGHT BECOMING L/V BY SUNDAY MORNING.
PREV DISCUSSION... /ISSUED 325 AM CDT SAT APR 27 2013/
SHORT TERM (TODAY THROUGH SUNDAY)...
INCREASING CHANCES FOR RAIN THIS WEEKEND AS A COLD FRONT SLIDES INTO
THE REGION. FOR TODAY...A CONTINUED SOUTHEAST INFLUX OF LOW LEVEL
MOISTURE WILL KEEP THE AREA POTENTIALLY UNSTABLE AS BOUNDARIES
APPROACH THE AREA. A MIXED LAYER CAP ALOFT WILL KEEP MUCH
CONVECTION FROM FIRING UNTIL AFTER DARK WHEN LOW LEVEL CONVERGENT
FORCES TAKE OVER (ALONG WITH SUPPORT ALOFT FROM A MID LEVEL JET).
HIGHS TODAY WILL BE IN THE 80S. WILL PLACE AT LEAST A SLIGHT
CHANCE OF THUNDERSTORMS OVER OUR NORTHERN CWA ALONG THE FRONT FOR
THIS AFTERNOON. THE COLD FRONT...LOCATED EARLY THIS MORNING OVER
THE TEXAS SOUTH PLAINS WILL SLIP SOUTH INTO OUR NORTHERN CWA BY
AFTERNOON. THE GFS MODEL SOLUTION STALLS THE FRONT OVER OVER
NORTHERN CWA DURING THE EVENING...THEN EDGES IT SOUTHWARD INTO THE
CENTRAL CWA OVERNIGHT. THIS IS SIGNIFICANT IN AS FAR AS RAINFALL
AND POTENTIALLY SEVERE WEATHER ARE CONCERNED AS BURRO MOUNTAIN
(MEXICAN PLATEAU) STORMS WHICH DEVELOP DURING THE LATE AFTERNOON/
EVENING HOURS PUSH EASTWARD AND INTERSECT THE FRONT DURING THE
OVERNIGHT HOURS OVER WESTERN SECTIONS. MOIST LOW LEVEL SOUTHEAST
FLOW (DEWPOINTS IN UPPER 60S) WILL MAINTAIN THESE STORMS AS THEY
TRAVERSE EAST...INTERSECTING THE FRONT AND ENHANCING RAIN AMOUNTS
AND SEVERITY OF STORMS. WILL INCLUDE A CHANCE OF SOME OF THE
STORMS BECOMING SEVERE TONIGHT OVER THE WESTERN HALF OF THE CWA
WITH THE GREATEST THREAT BEING FROM LARGE HAIL. SOME DAMAGING
WIND GUSTS ARE ALSO POSSIBLE. ISOLATED RAIN AMOUNTS OF 1 TO 3
INCHES ARE EXPECTED ALONG THE TRACK OF THE BURRO STORMS AS THEY
INTERSECT THE FRONT OVER WESTERN SECTIONS TONIGHT. SOME
STABILIZATION IS EXPECTED SUNDAY AS THE FRONT AND RAIN-COOLED AIR
SETTLE OVER THE AREA. HOWEVER THERE REMAINS ENOUGH DYNAMICS AND
INSTABILITY ALOFT FOR SOME RE-DEVELOPMENT OF STORMS IN DAYTIME
HEATING. HIGHS SUNDAY IN THE UPPER 70S HILLS...NEAR 80 TO LOW 80S
ELSEWHERE.
LONG TERM (SUNDAY NIGHT THROUGH FRIDAY)...
AS FRONTOLYSIS (DISSIPATION OR WEAKENING OF A FRONT) OCCURS SUNDAY
NIGHT...SOUTHEAST FLOW AND LIFT OVER THE WEAKENING BOUNDARY MAY BE
ENOUGH FOR ADDITIONAL CONVECTION. IN FACT...ANOTHER THREAT FOR
BURRO DEVELOPMENT MAY OCCUR OVERNIGHT SUNDAY/EARLY MONDAY MORNING
AS MOIST SOUTHEAST FLOW UPLIFTS ACROSS THE MEXICAN PLATEAU AMID A
WEAK UPPER LEVEL SUBTROPICAL JET. THIS INSTABILITY AND UNSETTLED
WEATHER PATTERN WILL LINGER THROUGH TUESDAY AS A MOIST SOUTHEAST
FLOW AT THE SURFACE AND COOLING ALOFT COUPLED WITH DISTURBANCES
TRIGGER FURTHER ACTIVITY ESPECIALLY OVER SOUTHWEST PORTIONS OF THE
CWA. THE UPPER TROUGH WILL EXIT THE REGION WEDNESDAY WITH A STABLE
NORTHERLY FLOW ALOFT IN PLACE. A STRONG COLD FRONT WILL THEN PUSH
RAPIDLY THROUGH THE REGION WEDNESDAY NIGHT WITH LOW CHANCES OF
SHOWERS AND THUNDERSTORMS LINING THE FRONT. DECREASING CLOUDINESS
AND MUCH COOLER THURSDAY WITH HIGHS GENERALLY IN THE 70S. SURFACE
RIDGING WILL SETTLE OVER THE AREA THURSDAY NIGHT AND EARLY FRIDAY
WITH LOWS FRIDAY MORNING MOSTLY IN THE 40S. MOSTLY SUNNY FRIDAY
WITH HIGHS IN THE 70S.
&&
.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY 84 62 83 60 84 / 10 50 30 10 10
AUSTIN BERGSTROM INTL AIRPORT 84 61 82 57 83 / 10 50 30 20 10
NEW BRAUNFELS MUNI AIRPORT 85 61 83 58 83 / 10 60 40 20 20
BURNET MUNI AIRPORT 83 60 81 57 83 / 20 50 20 10 10
DEL RIO INTL AIRPORT 85 66 81 64 84 / 10 60 40 30 20
GEORGETOWN MUNI AIRPORT 82 61 81 58 82 / 20 50 20 10 10
HONDO MUNI AIRPORT 84 63 81 60 83 / 10 70 40 30 20
SAN MARCOS MUNI AIRPORT 83 62 82 58 82 / 10 50 30 20 20
LA GRANGE - FAYETTE REGIONAL 85 66 83 62 84 / 20 40 30 10 20
SAN ANTONIO INTL AIRPORT 83 63 81 60 82 / 10 60 40 30 20
STINSON MUNI AIRPORT 84 63 81 61 82 / 10 60 40 30 20
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE/AVIATION...10
SYNOPTIC/GRIDS...05
PUBLIC SERVICE/DATA COLLECTION...32
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1227 PM CDT SAT APR 27 2013
.DISCUSSION...
SEE 18Z AVIATION DISCUSSION.
&&
.AVIATION...
4KM WRF IS VERY AGGRESSIVE WITH CONVECTIVE POTENTIAL THIS AFTN
WHICH IS OF SOME CONCERN. OTHER SHORT TERM MODELS ARE LESS BULLISH
WITH THUNDER. A S/WV WILL MOVE TOWARD SE TX THIS AFTN AND THIS
FEATURE COUPLED WITH HIGH PW VALUES...SOME UPPER LEVEL DIVERGENCE
SHOULD YIELD HIGH RAIN CHANCES FOR THIS AFTN AND EVENING. WILL
CARRY VCSH FOR THE AFTN AND EVENING. THE NAM AND RAP HAVE
INITIALIZED BEST SO HAVE LEANED TOWARD THOSE SOLUTIONS AND THIS
KEEPS MOST OF THE ORGANIZED PRECIP AND THUNDER NORTH OF THE
HOUSTON TERMINALS. AM EXPECTING SOME FOG AND IFR/LIFR CIGS TO
DEVELOP AFTER 08Z AREA WIDE. 43
&&
.PREV DISCUSSION... /ISSUED 1058 AM CDT SAT APR 27 2013/
UPDATE...
ELEMENTS ARE BEGINNING TO LINE UP THAT LEAN TOWARDS A HIGHER
CHANCE FOR MORE WIDESPREAD AFTERNOON RAIN AND THUNDER. RECENT
MODELS ARE COMING IN MORE WET...WITH BETTER MID TO UPPER LEVEL
DYNAMICS OVER EASTERN TEXAS WITHIN THE NEXT 24 HOURS. AT THE
SURFACE...AN APPROACHING BOUNDARY NOW NESTLING OVER CENTRAL TEXAS
MAY SAG INTO OUR EXTREME NORTHERN CWA TO PROVIDE BETTER LOW LEVEL
FOCUS AS EARLY PM TEMPERATURES WARM INTO THE UPPER 70S. MOISTURE
IS NOT A PROBLEM WITH PWAT VALUES IN THE 75 PERCENTILE RANGE FOR
LATE APRIL. SHORT TERM MODELS (RAP AND NAM) MAY BE ONTO SOMETHING
AS LOCAL TERMINAL DOPPLERS ARE DISPLAYING INCREASING -SHRA COVERAGE
OVER THE PAST HOUR OR TWO. PROG SOUNDINGS DO ERODE THIS MORNING`S
9-7H CAP...WITH SOME 12Z JET LEVEL DIVERGENCE NOTED AT 3OO MB
(TEXAS LAYING BETWEEN SOUTHERN POLAR BRANCH AND STJ). COMBINE ALL
OF THESE CHARACTERISTICS WITH WHAT APPEARS TO BE A SHORTWAVE
DISTURBANCE WITHIN THE NORTHERN MEXICO JET STREAK AND YOU HAVE A
STRONGER CASE FOR INCREASING OVERALL (SHORT TERM) POPS. 31
PREV DISCUSSION... /ISSUED 642 AM CDT SAT APR 27 2013/
AVIATION...
WIDESPREAD MVFR CEILINGS AGAIN THIS MORNING WITH SOME PATCHES OF
IFR. WILL SEE CEILINGS GRADUALLY RISE LATER THIS MORNING. S/SE
WINDS WILL BE LIGHTER TODAY AS THE PRESSURE GRADIENT HAS WEAKENED.
THERE IS A BOUNDARY THAT WILL LIKELY SERVE TO FOCUS SCT SHWRS AND
TSTMS LATE THIS AFT/EVE ACROSS NORTHERN AREAS. ADDITIONAL SHWR/TSTM
ACTIVITY THAT DEVELOPS WEST OF THE AREA THIS EVENING MAY MOVE EAST
ACROSS CENTRAL PORTIONS OF THE AREA AFTER MIDNIGHT ON SUN. 33
PREV DISCUSSION... /ISSUED 446 AM CDT SAT APR 27 2013/
DISCUSSION...
ADDED MARINE DISCUSSION.
MARINE...
LIGHT TO MODERATE EAST TO SOUTHEAST WINDS WILL CONTINUE INTO THE
MIDDLE OF NEXT WEEK. SIGNIFICANT CHANGE CONCERNING WIND/SEAS WILL
NOT OCCUR UNTIL EARLY THURSDAY OF NEXT WEEK...WHEN AN UNSEASONABLY
STRONG COLD FRONT WILL MOVE ACROSS THE MARINE AREA. EARLY
THURSDAY`S FORECAST CURRENTLY ADVERTISES STRONG POST FRONTAL
NORTHERLY WINDS THAT COULD REACH GALE FORCE IN GUSTS...ESPECIALLY
ACROSS THE OFFSHORE WATERS. THERE IS A CHANCE OF SOME SHOWERS OR
THUNDERSTORMS MOVING OFFSHORE LATE SATURDAY NIGHT OR EARLY SUNDAY.
33
PREV DISCUSSION... /ISSUED 441 AM CDT SAT APR 27 2013/
DISCUSSION...
SFC ANALYSIS AT 09Z HAS SFC LOW IN C OK WITH A WEAK BOUNDARY
TRAILING BACK TO THE SW THROUGH W C TX INTO W TX. MAINLY SSE WINDS
ACROSS THE AREA WITH SFC DEWPOINTS IN THE UPPER 60S ALONG THE
COAST. GULF MOISTURE IS CONTRIBUTING TO LOW STRATOCU DECKS THIS
MORNING WHICH WILL KEEP MIN TEMPS FROM DROPPING TOO MUCH MORE FROM
CURRENT TEMPS. UPPER AIR ANALYSIS HAS UPPER LOW OVER S PLAINS WITH
A JET STREAK STRETCHING FROM W TX TO C TENN. SFC LOW SHOULD MOVE
EAST AS UPPER LOW SLOWLY MOVES TOWARDS MISS RIVER VALLEY. SFC
BOUNDARY SHOULD WORK INTO NORTHERN AREAS OF SE TX FROM BRAZOS
VALLEY TO THE PINEY WOODS. BOUNDARY SHOULD BE FOCUS FOR
THUNDERSTORM ACTIVITY LATER THIS EVENING AND INTO THE OVERNIGHT.
MAIN FORECAST CONCERN THE NEXT COUPLE OF DAYS WILL BE CONVECTION.
UPPER LEVEL SUPPORT BECOMES MORE FAVORABLE TONIGHT INTO SUN
MORNING AS RIGHT ENTRANCE OF THE JET MOVES OVER THE AREA WITH AN
ENHANCED SUB-TROPICAL JET PUSHING ACROSS THE RIO GRANDE AND S TX.
COMBINATION OF DIVERGENCE FROM JET CIRC AND DIFFLUENCE OF JETS MAY
PROVIDE ENOUGH LARGE SCALE ASCENT TO ERODE MID LEVEL CAP
INVERSION. GFS/NAM BUFR SOUNDINGS SEEM TO SUPPORT THIS IDEA AND
ALSO YEILD CAPE AROUND 1500-2500 J/KG FROM COLLEGE STATION TO
CROCKETT JUST SOUTH OF THE FRONTAL BOUNDARY. YET MODELS WAIT UNTIL
THE LATE EVENING AFTER 00Z FOR CONVECTION TO INITIATE. WILL KEEP
POPS AROUND 30 PERCENT IN THE EVENING AND THEN UP TO 40 PERCENT
FOR THE OVERNIGHT TIME FRAME. WRF-ARW SHOWS CONVECTION DEVELOPING
IN THE EVENING OVER THE HILL COUNTRY THAT MAY THEN MOVE INTO SE TX
BY 09-12Z SUN AND CONTINUE UNTIL 18Z. RIGHT NOW SPC DOES NOT HAVE
SE TX IN A SEVERE THUNDERSTORM OUTLOOK BUT THINK IF SFC BASED
CONVECTION DOES FORM WITH AFOREMENTIONED INSTABILITY...COULD SEE
SEVERE STORMS WITH HAIL/WIND THREAT. DEEP LAYER SHEAR AND UPPER
LEVEL JET MAY EVEN SUPPORT ORGANIZED STORM STRUCTURES WHICH WOULD
ALSO ENHANCE THE SEVERE THREAT. AT THIS TIME...JUST A WAITING GAME
TO SEE IF CAP WILL HOLD OR NOT.
FRONTAL BOUNDARY DOES WEAKEN/DISSIPATE MON/TUE SO WILL ONLY CARRY
A SLIGHT CHANCE OF STORMS FOR THIS TIME PERIOD. MOISTURE MAY
INCREASE ENOUGH TUE TO HAVE A FEW MORE SCT STORMS. ALSO LOOKS LIKE
LEFT OVER VORTICITY WILL REMAIN OVER SE TX THROUGH TUE WITH MAIN
UPPER LEVEL SHORT WAVE MOVING OUT OF THE AREA. A FAIRLY STRONG JET
AND UPPER LEVEL TROUGH ALSO DEVELOPS MON/TUE OVER THE INTER
MOUNTAIN WEST. BY WED A STRONG SHORTWAVE DROPS INTO THE ROCKIES
AND C PLAINS. THIS AMPLIFIED PATTERN HELPS SUPPORT A STRONG COLD
FRONT PUSHING INTO TX LATE WED AND WED NIGHT. GFS HAS BEEN QUITE
CONSISTENT WITH FRONTAL PASSAGE IN THE 06Z TO 12Z THUR TIME
FRAME. THE ECMWF HAS BEEN CONSISTENT WITH THIS TIMING BUT THE 00Z
RUNS HAVE BEEN SLOWER WITH THE FRONT. WILL KEEP 30 POPS FOR
CONVECTION ALONG THE FRONT AND POST FRONTAL PRECIP. DO EXPECT
CLEARING TO OCCUR THUR AFTERNOON AND NIGHT. BOTH GFS/ECMWF BRING A
1040MB HIGH INTO THE C AND N PLAINS BY 12Z THUR. SFC HIGH DOES
STRETCH OVER ALL OF THE PLAINS AND DOWN INTO THE GULF. SHOULD
WINDS DECREASE ENOUGH FRI MORNING LOW TEMPS WILL BE IN RECORD LOW
TERRITORY. WILL DROP MIN TEMP TO 48F FOR HOUSTON IAH WHICH IS ONE
DEGREE ABOVE THE RECORD OR COUPLE OF DEGREES BELOW GUIDANCE.
LATEST GFS ENSEMBLE MOS HAS A LOW MEMBER TEMP OF 45F FOR FRI
MORNING. GIVEN SOME MORE CONSISTENCY MAY NEED TO GO WITH A RECORD
LOW FORECAST TEMP. THUR/FRI NEXT WEEK WILL BE ON THE CHILLY SIDE.
NOT SURE HOW MUCH OF A WARM UP WILL OCCUR BEHIND THE FRONT. GFS
BRINGS 850MB TEMPS DOWN TO 2C BY FRI MORNING. GIVE STRONG COLD
ADVECTION...MAY BE TOUGH FOR TEMPS TO REACH THE 70S EACH DAY. THIS
WILL LARGELY DEPEND ON CLOUD COVER AND THE MAGNITUDE OF COLD
ADVECTION. REGARDLESS LOOKS LIKE TEMPS WILL BE A GOOD 10-15
DEGREES BELOW NORMAL FOR THE END OF NEXT WEEK.
39
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 84 67 83 61 84 / 50 40 30 10 10
HOUSTON (IAH) 83 68 82 62 83 / 60 40 40 10 20
GALVESTON (GLS) 77 68 77 66 78 / 40 20 30 20 20
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
234 PM PDT Sat Apr 27 2013
.SYNOPSIS...
An upper level low pressure system passing through the region
tonight will bring scattered showers along the Cascade crest and
over the Central Panhandle Mountains. Another storm system is
expected Sunday night into Monday and will bring a better chance
for some rain and mountain snow along with stronger winds for
Monday afternoon. This system will usher in much cooler
temperatures for early next week. High pressure will then rebound,
bringing a warming trend for the middle to end of next week.
&&
.DISCUSSION...
Tonight: A cold front is beginning to sag into the region from the
northwest. Water vapor imagery shows a nicely defined dry slot
indicating the back edge of the front from Castlegar in BC to 50
N 160 W in the Gulf of Alaska. A fetch of Pacific moisture is
streaming eastward into the Northwest along the leading edge of
the front and is expected to sag southward with time tonight. This
moisture has generally only yielded some rain across western
Washington up to the crest of the Cascade Mountain Range. Over
eastern WA into the ID Panhandle, we have been too dry for any of
this moisture to reach the surface yet. However, LAPS data has
shown a gradual moistening of the upper atmosphere through time
today, and radar has begin to show some blips to the east and
south of Spokane. We should hold on to a fairly substantial pocket
of dry air through tonight across the basin. Strong westerly flow
across the Cascades will undoubtedly result in conditions
remaining dry east for the western two-thirds of the forecast area
(expect right along the Cascade crest). Eventually we will begin
to see some rain reaching the surface late this afternoon or early
evening. Latest HRRR model guidance suggest that measurable
rainfall will begin in the Central Panhandle Mountains around 6:00
PM or so. Gusty winds across the Wenatchee Area over into the
western portions of the basin are expected to relax this evening
as we begin to decouple a bit from the free atmosphere. I fully
anticipate our Wind Advisory to be able to come down right around
sunset today. /SVH
...BREEZY SUNDAY THEN VERY WINDY ON MONDAY...
Sunday through Monday night: Wind will be the main concern for
the next couple of days as a swift westerly flow remains parked
over the Inland Northwest, along with mostly dry and cool weather.
With a surface low over the Canadian Rockies and a surface high
on the OR coast, a stiff pressure gradient will continue into
Sunday with good mixing kicking up winds in the afternoon and
early evening. Speeds should be similar if not slightly lighter
than experienced today with lack of a frontal boundary. The NAM
and SREF want to hold on to low level moisture across southeast
Washington into the Idaho Sunday morning and given the light
upslope lift, could see light showers across the Palouse, Blue
mountains and into the Idaho panhandle. Anticipate light
orographic showers to persist into the afternoon and evening in
north Idaho. Then late Sunday night, the upper level jet stream
sinks over the region while the next in a series of weather
disturbances drops into eastern Washington. There is a chance of
precipitation, although it will be small and confined to the
orographic favored areas of the Cascade crest, the Blue mountains
and parts of north Idaho. As this features pushes through the
region, winds will steadily increase due the cold and dry air
advection. The jet 120 kt jet core will be over the region by
midday Monday. This will support stronger winds mixing to the
surface and also kicking up some blowing dust. There is also the
potential for mountain wave winds off the lee side of the
Cascades. The GFS MAV seems to have the strongest winds with this
feature, supporting the idea for the potential of high wind
highlights for a good chunk of the forecast area. The NAM MET is
slightly weaker but it still shows windy conditions across the
region. Have bumped up the winds in the forecast for Monday and
will continue to highlight the concern in the Hazardous Weather
Outlook. By Monday night, drier air filters in the region with
clearing skies and winds decrease. Dewpoints take a plunge and
drop into the 20s. In sheltered areas, there is the potential for
some rather chilly freezing temperatures by late Monday night.
/rfox.
Tues to Thu night: After a few showers and breezy conditions,
high pressure brings drier weather by mid-week. Tuesday a surface
trof lingers across N ID and the E 1/3 of WA. A secondary mid-
level shortwave slides by on 130kt+ jet. The jet curves by the
Cascades through north Oregon early, placing some unstable lapse
rates, marginal CAPE (50-200 J/kg) and LI values across NE WA and
N ID. These ingredients will be working against CIN and larger-
scale subsidence with the approaching high. The forecast focuses
the primary shower threat across Idaho in mountains in the
afternoon. Ingredients are marginal for thunder so I kept it out
for now, but I would not be surprised to see some "one-clap-
wonders". I expect locally breezy conditions to continue. However
winds should be much less as compared to the days just prior.
Tuesday night to Thursday night high pressure builds in and, for
the most part, the atmosphere stabilizes with drier, clearer
conditions. A weak impulse approaches late Thursday with a few
more clouds. The threat of precipitation will be minimal.
Temperatures remain cooler than normal on Tuesday, with more
freezing temperatures possible Wednesday morning, but value
moderate toward average by Thursday. /J. Cote`
Friday through Saturday night...The Inland Northwest will be
on the eastern edge of an upper level ridge centered off the
Pacific coast. Weather-wise, this might be the first Saturday that
the weather looks fairly uneventful. The winds do not look like
they will be much of an issue, and precipitation chances will be
limited to the higher elevations of the Idaho panhandle and the
Cascades. Well above normal temperatures are forecast for both.
Friday and Saturday. ty
&&
.AVIATION...
18Z TAFS: A cold front approaching the region from the northwest
has resulted in increasing mid and high level clouds. these clouds
will lower a bit to between 5-8k ft through the afternoon into the
evening as the atmosphere moistens from the top down. Pre-frontal
southwesterly winds will increase this afternoon with gusts up
around 30-35 mph over much of the region. These winds will likely
kick up some dust across the northern Columbia Basin, which may
result in some reduced visibilities at KMWH. We may see some
showers developing in the vicinity of KCOE and KPUW this evening,
but all other TAF sites are expected to remain dry. Models are
indicating the possibility for some low stratus developing near
these TAF sites early Sunday morning, but I don`t have a lot of
confidence with this as boundary layer moisture will be lacking
without much rainfall anticipated with the cold front. /SVH
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 43 63 43 56 32 53 / 10 10 30 10 0 10
Coeur d`Alene 41 62 40 55 30 52 / 20 20 40 20 10 20
Pullman 41 61 43 54 29 51 / 20 20 30 20 10 20
Lewiston 50 68 48 62 38 57 / 10 10 20 10 10 20
Colville 40 67 42 58 31 58 / 10 10 30 10 0 20
Sandpoint 39 61 39 54 31 50 / 30 20 70 30 10 20
Kellogg 42 59 41 49 31 45 / 60 30 70 70 20 30
Moses Lake 47 70 46 63 33 63 / 0 0 10 0 0 0
Wenatchee 48 66 46 59 37 58 / 0 10 10 0 0 0
Omak 40 68 42 58 32 59 / 0 10 10 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Wind Advisory until 8 PM PDT this evening for Moses Lake Area-
Upper Columbia Basin-Waterville Plateau-Wenatchee Area.
&&
$$