Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 05/23/13
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1032 PM EDT WED MAY 22 2013
.SYNOPSIS...
A STALLED FRONT WILL REMAIN IN THE VICINITY INTO THURSDAY. A COLD
FRONT WILL THEN SLOWLY APPROACH FROM THE WEST THURSDAY...THEN MOVE
INTO WESTERN PORTIONS OF THE TRI-STATE THURSDAY NIGHT. A WAVE OF
LOW PRESSURE DEVELOPS ALONG THIS SLOW MOVING COLD FRONT
FRIDAY...REMAINS JUST EAST OF THE REGION SATURDAY...AND THEN
TRACKS NORTH ALONG THE NEW ENGLAND COAST ON SUNDAY. HIGH PRESSURE
OVER THE GREAT LAKES BUILDS SOUTHEAST ACROSS THE AREA MONDAY INTO
TUESDAY. A WARM FRONT WILL THEN APPROACH FROM THE SOUTHWEST BY MID
WEEK.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
LINE OF SHOWERS AND THUNDERSTORMS OVER EASTERN PA BEGINNING TO
BREAK UP AS THEY TRACK NORTHEAST. ADDITIONAL SHOWERS AND
THUNDERSTORMS ARE FIRING UP OVER NORTHERN VA AND MD...AND THEY ARE
TRACKING NORTHEAST AS WELL. THE BULK OF THE ACTIVITY SHOULD STAY
NORTH OF THE REGION...BUT HRRR GUIDANCE CONTINUES TO INDICATE
CONVECTIVE ACTIVITY MOVING INTO THE LOCAL AREA PRIOR TO DAYBREAK
THURSDAY. MOST OF THE ACTIVITY SHOULD SCATTER OUT BEFORE IT
REACHES THE CWA...AND THE MARINE LAYER OVER THE REGION SHOULD HELP
TO TEMPER ANY STORM AS WELL.
OTHERWISE...LOW CLOUDS/FOG WILL CONTINUE TO ESTABLISH ITSELF OVER
THE AREA. FOG MAY BE LOCALLY DENSE NEAR THE COAST.
LOWS TONIGHT GENERALLY IN THE MID TO UPPER 60S...AND IN THE LOWER
60S NEAR THE COAST. THESE TEMPS ARE ABOUT 10-15 DEGREES ABOVE
NORMAL.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
MIXING ASSOCIATED WITH PASSING 700-500 HPA SHORTWAVE THURSDAY
MORNING SHOULD ERODE THE MARINE INVERSION - BUT STILL WILL BE
LEFT WITH QUITE A BIT OF MID TO HIGH CLOUDS WITH MOIST SW FLOW
ALOFT.
PRE-FRONTAL TROUGH MOVING INTO THE LOWER HUDSON VALLEY/NE NJ
THURSDAY AFTERNOON SHOULD SERVE AS TRIGGER FOR SCT-NUMEROUS SHRA
WITH EMBEDDED TSRA. LIKELY POPS MAINLY FROM NYC-INTERIOR SW CT
ZONES ON W AND CHANCE POPS EAST OF THAT LINE. SOME SUGGESTION FROM
NAM/GFS THAT EASTERN AREAS WILL REMAIN DRY THURSDAY...BUT FOR NOW
TOO MUCH LOW-MID LEVEL MOISTURE AND INCREASING LOW LEVEL JET TO
FORECAST THAT AT THIS TIME.
WITH 30-35 KT BULK SHEAR...1000-1500 J/KG OF CAPE AND BULK
RICHARDSON NUMBERS 15-30 HAVE THE POTENTIAL FOR ISOLATED SEVERE
STORMS THURSDAY AFTERNOON ACROSS NE NJ/LOWER HUDSON VALLEY AND
MAYBE NYC AND SW CT ZONES. MAIN THREAT IS GUSTY WINDS AND LARGE
HAIL. ALSO NEED TO WATCH FOR LOW LEVEL HELICITY WITH S SFC FLOW
AND SW FLOW AT 850 HPA.
FOR HIGHS THURSDAY USED A BLEND OF MIXING DOWN FROM 975 HPA NEAR
THE COAST AND 950 HPA INLAND...WITH NAM 2-METER TEMPERATURES AND A
BLEND OF MAV AND MET GUIDANCE. FORECASTING VALUES AROUND NORMAL
EAST TO A FEW DEGREES ABOVE NORMAL WEST.
DEEP SW FLOW ALOFT...BECOMES DIFFLUENT AT 500 HPA AFTER MIDNIGHT.
HAVE THE POTENTIAL FOR HEAVY RAINFALL AS A RESULT. REFER TO THE
HYDROLOGY SECTION FOR DETAILS. SEVERE THREAT COULD LINGER INTO THE
EVENING ACROSS WESTERN ZONES AS WELL.
FOR LOWS THURSDAY NIGHT USED A BLEND OF MAV/MET GUIDANCE WITH
VALUES FORECAST AROUND 10 DEGREES ABOVE NORMAL.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
MODELS HAVE TRENDED CONSIDERABLY SLOWER AND DEEPER WITH THE
APPROACHING UPPER TROUGH OVER THE MID SECTION OF THE COUNTRY. THERE
IS VERY GOOD AGREEMENT WITH THE 12Z GFS AND ECMWF ON TAKING A CLOSED
UPPER LOW FROM THE MID ATLANTIC STATES ON FRI NE TO OVER NEW ENGLAND
ON SUN. THE NAM AND GGEM ARE TRENDING IN THAT DIRECTION...BUT ARE
MORE PROGRESSIVE BEYOND 00Z SAT. PREFERENCE AT THIS TIME IS TO GO
WITH THE SLOWER GFS/ECMWF SOLUTION BASED ON MODEL TRENDS AND THE RUN
TO RUN CONTINUITY BEING EXHIBITED OVER THE LAST SEVERAL MODEL CYCLES.
AS FOR SENSIBLE WEATHER...THIS RESULTS IN A WET...COOL WEEKEND WITH
THE POTENTIAL FOR ANOTHER 1 TO 2 INCHES OF RAINFALL IN THE FRI-SAT
TIME FRAME. SINCE THIS IS A BIG ADJUSTMENT FROM THE PREVIOUS
FORECAST...HAVE RAMPED UP RAIN CHANCES FRI INTO SAT...BUT THESE MAY
BE UNDERDONE...ESPECIALLY FOR SAT WHERE THERE IS A TREND IN THE
FORECAST TO DRY THINGS OUT SAT INTO SUN. LATEST ECMWF KEEPS
CONDITIONS WET INTO SUN WITH A GUSTY NW FLOW ON THE BACKSIDE. SO
THIS IS THE POINT IN THE FORECAST WHERE CONDITIONS MAY CONTINUE TO
DETERIORATE WITH SUBSEQUENT MODEL RUNS.
ONCE AGAIN...WHILE THE FORECAST HAS AGGRESSIVELY TAKEN A DOWNWARD
NOTE FOR THE HOLIDAY WEEKEND...RAIN CHANCES MAY BE ON THE INCREASE
SAT INTO SUN BASED ON LATEST TRENDS IN THE MODEL GUIDANCE.
IN ADDITION...SOME OF THE RAINFALL ON FRI...OR AT LEAST THE FIRST
HALF OF THE DAY MAY BE CONVECTIVE WITH LOCALIZED HEAVY RAINFALL WITH
ANY EMBEDDED THUNDERSTORMS. THEREAFTER...THE AIRMASS STABILIZES IN
THE LOW-LEVELS WITH POST-FRONTAL RAIN/SHOWERS...PRIMARILY DRIVEN BY
FRONTOGENETIC FORCING ON THE BACKSIDE OF THE LOW. WIND GUSTS SAT
INTO SUN MAY BE UP TO 35 MPH...BUT THIS IS THE POTENTIAL...WITH THE
FORECASTS SIGNIFICANTLY LOWER AT THIS TIME.
AS FOR TEMPS...DAYTIME HIGHS WITH THE CLOUD COVER AND RAIN WILL BE 5
TO 10 DEGREES BELOW NORMAL. STAYED BELOW GUIDANCE. OVERNIGHT LOWS
WILL BE CLOSE TO SEASONABLE. A GRADUAL WARM-UP TO NEAR SEASONABLE
LEVELS IS THEN FORECAST MON-WED.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
A STATIONARY FRONTAL BOUNDARY WILL REMAIN NORTH OF THE TERMINALS
THROUGH THE FORECAST PERIOD. A LOW PRESSURE SYSTEM AND COLD FRONT
APPROACH SLOWLY FROM THE WEST DURING THE DAY THURSDAY.
AN AREA OF SHOWERS MOVING INTO EASTERN PENNSYLVANIA WILL WEAKEN
OVERNIGHT WITH SCATTERED SHOWERS POSSIBLE IN THE NYC VICINITY
AROUND 08Z.
MVFR CEILINGS AND VISIBILITIES IN FOG POSSIBLE AFTER 07Z ALTHOUGH
CONFIDENCE IN THIS OCCURRING ESPECIALLY AT THE NYC TERMINALS IN
DIMINISHING. IFR CEILINGS AND MVFR VISIBILITIES IN FOG POSSIBLE AT
THE TERMINALS EAST OF NEW YORK CITY...CEILINGS MAY BECOME LIFR AFTER
09Z.
MVFR CONDITIONS LIKELY DURING THURSDAY WITH SHOWERS DEVELOPING AFTER
17Z. ISOLATED THUNDERSTORMS WILL BE POSSIBLE ALSO.
WIND WILL BE GENERALLY FROM THE SOUTH 10 KT OR LESS THROUGH LATE
TONIGHT...THEN SOUTH TO SOUTHWEST 10 TO 15 KT LATE TONIGHT INTO
THURSDAY.
.OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY...
.THURSDAY NIGHT-FRIDAY...NUMEROUS SHRA...ISOLATED TSTMS POSSIBLE.
MVFR TO IFR IN SHOWERS...FOG AND STRATUS.
.SATURDAY...SHRA LIKELY WITH MVFR OR LOWER. N WINDS 25-30G35KT.
.SUNDAY...MOST LIKELY VFR WITH NW WINDS 20-25KT. POTENTIAL FOR GUSTS
UP TO 40KT.
.MONDAY...VFR. NW WINDS 15-20G25KT.
&&
.MARINE...
DENSE FOG ADVISORY REMAINS UP FOR ALL WATERS THROUGH 6AM DUE TO
FOG RESTRICTING VSBY TO LESS THAN 1 NM. THIS ADV MAY HAVE TO BE
EXTENDED THROUGH THE MID-MORNING HOURS.
SEAS COMING UP TO SCA LEVELS AND WILL CONTINUE THROUGH THURSDAY
NIGHT. WINDS ALSO INCREASE LATE TONIGHT AND REMAIN UP INTO
THURSDAY NIGHT. INCREASING LOW LEVEL JET THROUGH THURSDAY NIGHT
INCREASES POTENTIAL FOR SCA LEVEL GUSTS OVER THE COASTAL OCEAN
WATERS - SO HAVE KEPT HEADLINE AS SCA VICE CONVERTING TO AN SCA
FOR HAZARDOUS SEAS.
MARINE INVERSION APPEARS WILL LIMIT MIXING - SO WHILE COULD SEE
OCCASIONAL GUSTS TO 25 KT OVER THE REMAINDER OF THE WATERS FROM
LATE TONIGHT INTO THURSDAY NIGHT - DO NOT HAVE CONFIDENCE TO ISSUE
SCA AT THIS TIME FOR THE NON-OCEAN ZONES.
THERE IS A GOOD POTENTIAL FOR SCA CONDITIONS TO CONTINUE THROUGH THE
UPCOMING WEEKEND AS LOW PRESSURE FORMS OVER THE WATERS ON FRI AND
LIFTS SLOWLY TO THE NORTH AND EAST. SCA CONDITIONS ARE BECOMING
INCREASINGLY LIKELY...WITH THE POTENTIAL FOR GALE CONDITIONS SAT
INTO SUN. WINDS AND SEAS BEGIN TO SUBSIDE LATE SUN INTO MON WITH
HIGH PRESSURE BUILDING IN FROM THE GREAT LAKES REGION.
&&
.HYDROLOGY...
THERE IS THE POTENTIAL FOR AROUND 3/4 TO 1 INCH BASIN AVERAGE QPF
THURSDAY AND THURSDAY NIGHT WITH LOCALLY HIGHER AMOUNTS.
DO NOT EXPECT ANY WIDESPREAD FLOOD THREAT THURSDAY FROM ANY
SHRA/TSRA BUT COULD SEE SOME MINOR FLOODING UNDER ANY STRONGER
CONVECTION - ESPECIALLY IF THERE IS ANY TRAINING.
THE HEAVIEST RAINFALL IN THIS TIME FRAME WILL BE LATE THURSDAY
NIGHT - WITH LOCALIZED RAINFALL RATES OF 1-1.5 INCHES/HR POSSIBLE
NOTING PRECIPITABLE WATERS OF 1.5-1/75 INCHES IN THIS TIME
FRAME. IF THESE RATES ARE REALIZED...ESPECIALLY IF THE STORMS
PRODUCING THEM PASS OVER AREAS RECEIVING LOCALLY HEAVY RAINFALL
THURSDAY...THERE IS THE POTENTIAL FOR LOCALIZED FLASH FLOODING.
THE THREAT FOR LOCALIZED HEAVY RAINFALL WILL CONTINUE INTO THE FIRST
HALF OF FRI WITH EMBEDDED CONVECTION. THEREAFTER...A STRATIFORM RAIN
AND/OR SHOWERS DEVELOPS ON THE BACKSIDE OF DEVELOPING LOW PRESSURE.
AN ADDITIONAL 1 TO 2 INCHES OF RAINFALL IS POSSIBLE FRI INTO SAT.
THIS MAY EXACERBATE ANY ONGOING FLOODING. RAIN MAY LINGER EVEN INTO
SUN BASED ON LATEST MODEL TRENDS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...DENSE FOG ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ330-335-338-
340-345-350-353-355.
SMALL CRAFT ADVISORY UNTIL 6 AM EDT FRIDAY FOR ANZ350-353-355.
&&
$$
SYNOPSIS...MALOIT/DW
NEAR TERM...MALOIT/MPS
SHORT TERM...MALOIT
LONG TERM...DW
AVIATION...MET
MARINE...MALOIT/DW
HYDROLOGY...MALOIT/DW
AREA FORECAST DISCUSSION
NWS NEW YORK NY
943 PM EDT WED MAY 22 2013
.SYNOPSIS...
A STALLED FRONT WILL REMAIN IN THE VICINITY INTO THURSDAY. A COLD
FRONT WILL THEN SLOWLY APPROACH FROM THE WEST THURSDAY...THEN MOVE
INTO WESTERN PORTIONS OF THE TRI-STATE THURSDAY NIGHT. A WAVE OF
LOW PRESSURE DEVELOPS ALONG THIS SLOW MOVING COLD FRONT
FRIDAY...REMAINS JUST EAST OF THE REGION SATURDAY...AND THEN
TRACKS NORTH ALONG THE NEW ENGLAND COAST ON SUNDAY. HIGH PRESSURE
OVER THE GREAT LAKES BUILDS SOUTHEAST ACROSS THE AREA MONDAY INTO
TUESDAY. A WARM FRONT WILL THEN APPROACH FROM THE SOUTHWEST BY MID
WEEK.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
LINE OF SHOWERS AND THUNDERSTORMS OVER EASTERN PA BEGINNING TO
BREAK UP AS THEY TRACK NORTHEAST. ADDITIONAL SHOWERS AND
THUNDERSTORMS ARE FIRING UP OVER NORTHERN VA AND MD...AND THEY ARE
TRACKING NORTHEAST AS WELL. THE BULK OF THE ACTIVITY SHOULD STAY
NORTH OF THE REGION...BUT HRRR GUIDANCE CONTINUES TO INDICATE
CONVECTIVE ACTIVITY MOVING INTO THE LOCAL AREA PRIOR TO DAYBREAK
THURSDAY. MOST OF THE ACTIVITY SHOULD SCATTER OUT BEFORE IT
REACHES THE CWA...AND THE MARINE LAYER OVER THE REGION SHOULD HELP
TO TEMPER ANY STORM AS WELL.
OTHERWISE...LOW CLOUDS/FOG WILL CONTINUE TO ESTABLISH ITSELF OVER
THE AREA. FOG MAY BE LOCALLY DENSE NEAR THE COAST.
LOWS TONIGHT GENERALLY IN THE MID TO UPPER 60S...AND IN THE LOWER
60S NEAR THE COAST. THESE TEMPS ARE ABOUT 10-15 DEGREES ABOVE
NORMAL.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
MIXING ASSOCIATED WITH PASSING 700-500 HPA SHORTWAVE THURSDAY
MORNING SHOULD ERODE THE MARINE INVERSION - BUT STILL WILL BE
LEFT WITH QUITE A BIT OF MID TO HIGH CLOUDS WITH MOIST SW FLOW
ALOFT.
PRE-FRONTAL TROUGH MOVING INTO THE LOWER HUDSON VALLEY/NE NJ
THURSDAY AFTERNOON SHOULD SERVE AS TRIGGER FOR SCT-NUMEROUS SHRA
WITH EMBEDDED TSRA. LIKELY POPS MAINLY FROM NYC-INTERIOR SW CT
ZONES ON W AND CHANCE POPS EAST OF THAT LINE. SOME SUGGESTION FROM
NAM/GFS THAT EASTERN AREAS WILL REMAIN DRY THURSDAY...BUT FOR NOW
TOO MUCH LOW-MID LEVEL MOISTURE AND INCREASING LOW LEVEL JET TO
FORECAST THAT AT THIS TIME.
WITH 30-35 KT BULK SHEAR...1000-1500 J/KG OF CAPE AND BULK
RICHARDSON NUMBERS 15-30 HAVE THE POTENTIAL FOR ISOLATED SEVERE
STORMS THURSDAY AFTERNOON ACROSS NE NJ/LOWER HUDSON VALLEY AND
MAYBE NYC AND SW CT ZONES. MAIN THREAT IS GUSTY WINDS AND LARGE
HAIL. ALSO NEED TO WATCH FOR LOW LEVEL HELICITY WITH S SFC FLOW
AND SW FLOW AT 850 HPA.
FOR HIGHS THURSDAY USED A BLEND OF MIXING DOWN FROM 975 HPA NEAR
THE COAST AND 950 HPA INLAND...WITH NAM 2-METER TEMPERATURES AND A
BLEND OF MAV AND MET GUIDANCE. FORECASTING VALUES AROUND NORMAL
EAST TO A FEW DEGREES ABOVE NORMAL WEST.
DEEP SW FLOW ALOFT...BECOMES DIFFLUENT AT 500 HPA AFTER MIDNIGHT.
HAVE THE POTENTIAL FOR HEAVY RAINFALL AS A RESULT. REFER TO THE
HYDROLOGY SECTION FOR DETAILS. SEVERE THREAT COULD LINGER INTO THE
EVENING ACROSS WESTERN ZONES AS WELL.
FOR LOWS THURSDAY NIGHT USED A BLEND OF MAV/MET GUIDANCE WITH
VALUES FORECAST AROUND 10 DEGREES ABOVE NORMAL.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
MODELS HAVE TRENDED CONSIDERABLY SLOWER AND DEEPER WITH THE
APPROACHING UPPER TROUGH OVER THE MID SECTION OF THE COUNTRY. THERE
IS VERY GOOD AGREEMENT WITH THE 12Z GFS AND ECMWF ON TAKING A CLOSED
UPPER LOW FROM THE MID ATLANTIC STATES ON FRI NE TO OVER NEW ENGLAND
ON SUN. THE NAM AND GGEM ARE TRENDING IN THAT DIRECTION...BUT ARE
MORE PROGRESSIVE BEYOND 00Z SAT. PREFERENCE AT THIS TIME IS TO GO
WITH THE SLOWER GFS/ECMWF SOLUTION BASED ON MODEL TRENDS AND THE RUN
TO RUN CONTINUITY BEING EXHIBITED OVER THE LAST SEVERAL MODEL CYCLES.
AS FOR SENSIBLE WEATHER...THIS RESULTS IN A WET...COOL WEEKEND WITH
THE POTENTIAL FOR ANOTHER 1 TO 2 INCHES OF RAINFALL IN THE FRI-SAT
TIME FRAME. SINCE THIS IS A BIG ADJUSTMENT FROM THE PREVIOUS
FORECAST...HAVE RAMPED UP RAIN CHANCES FRI INTO SAT...BUT THESE MAY
BE UNDERDONE...ESPECIALLY FOR SAT WHERE THERE IS A TREND IN THE
FORECAST TO DRY THINGS OUT SAT INTO SUN. LATEST ECMWF KEEPS
CONDITIONS WET INTO SUN WITH A GUSTY NW FLOW ON THE BACKSIDE. SO
THIS IS THE POINT IN THE FORECAST WHERE CONDITIONS MAY CONTINUE TO
DETERIORATE WITH SUBSEQUENT MODEL RUNS.
ONCE AGAIN...WHILE THE FORECAST HAS AGGRESSIVELY TAKEN A DOWNWARD
NOTE FOR THE HOLIDAY WEEKEND...RAIN CHANCES MAY BE ON THE INCREASE
SAT INTO SUN BASED ON LATEST TRENDS IN THE MODEL GUIDANCE.
IN ADDITION...SOME OF THE RAINFALL ON FRI...OR AT LEAST THE FIRST
HALF OF THE DAY MAY BE CONVECTIVE WITH LOCALIZED HEAVY RAINFALL WITH
ANY EMBEDDED THUNDERSTORMS. THEREAFTER...THE AIRMASS STABILIZES IN
THE LOW-LEVELS WITH POST-FRONTAL RAIN/SHOWERS...PRIMARILY DRIVEN BY
FRONTOGENETIC FORCING ON THE BACKSIDE OF THE LOW. WIND GUSTS SAT
INTO SUN MAY BE UP TO 35 MPH...BUT THIS IS THE POTENTIAL...WITH THE
FORECASTS SIGNIFICANTLY LOWER AT THIS TIME.
AS FOR TEMPS...DAYTIME HIGHS WITH THE CLOUD COVER AND RAIN WILL BE 5
TO 10 DEGREES BELOW NORMAL. STAYED BELOW GUIDANCE. OVERNIGHT LOWS
WILL BE CLOSE TO SEASONABLE. A GRADUAL WARM-UP TO NEAR SEASONABLE
LEVELS IS THEN FORECAST MON-WED.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
A STATIONARY FRONTAL BOUNDARY WILL REMAIN NORTH OF THE TERMINALS
THROUGH THE FORECAST PERIOD. A LOW PRESSURE SYSTEM AND COLD FRONT
APPROACH SLOWLY FROM THE WEST DURING THE DAY THURSDAY.
MVFR CEILINGS AND FOG DEVELOP LATE THIS EVENING AND OVERNIGHT FOR
THE NEW YORK CITY TERMINALS AND WEST. TO THE EAST IFR CEILINGS AND
FOG WILL BE DEVELOPING...WITH LIFR AT TIMES AFTER 07Z. MVFR
CONDITIONS DURING THURSDAY WITH SHOWERS DEVELOPING AFTER 17Z.
ISOLATED THUNDERSTORMS WILL BE POSSIBLE ALSO.
WIND WILL BE GENERALLY FROM THE SOUTH 10 KT OR LESS THROUGH LATE
TONIGHT...THEN SOUTH TO SOUTHWEST 10 TO 15 KT LATE TONIGHT INTO
THURSDAY.
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: AMENDMENTS LATE THIS EVENING FOR MVFR
CEILINGS AND FOG DEVELOPING. AMENDMENTS FOR TIMING OF SHOWERS AND
THUNDERSTORMS THURSDAY. SOME THUNDERSTORMS MAY PRODUCE GUSTY
WINDS.
KLGA FCSTER COMMENTS: AMENDMENTS LATE THIS EVENING FOR MVFR
CEILINGS AND FOG DEVELOPING. AMENDMENTS FOR TIMING OF SHOWERS AND
THUNDERSTORMS THURSDAY. SOME THUNDERSTORMS MAY PRODUCE GUSTY WINDS.
KEWR FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS TONIGHT. AMENDMENTS
FOR TIMING OF SHOWERS AND THUNDERSTORMS THURSDAY. SOME THUNDERSTORMS
MAY PRODUCE GUSTY WINDS.
KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS TONIGHT. MVFR
CEILINGS AND FOG POSSIBLE AFTER 09Z. AMENDMENTS FOR TIMING OF
SHOWERS AND THUNDERSTORMS THURSDAY. SOME THUNDERSTORMS MAY PRODUCE
GUSTY WINDS.
KHPN FCSTER COMMENTS: AMENDMENTS LATE THIS EVENING FOR MVFR
CEILINGS AND FOG DEVELOPING...WITH IFR AT TIMES. AMENDMENTS FOR
TIMING OF SHOWERS AND THUNDERSTORMS THURSDAY. SOME THUNDERSTORMS MAY
PRODUCE GUSTY WINDS.
KISP FCSTER COMMENTS: AMENDMENTS THIS EVENING FOR IFR CEILINGS AND
FOG. AMENDMENTS THURSDAY FOR SLOWLY IMPROVING CONDITIONS. SHOWERS
LATE AFTERNOON THURSDAY.
.OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY...
.THURSDAY NIGHT-FRIDAY...NUMEROUS SHRA...ISOLATED TSTMS POSSIBLE.
MVFR TO IFR IN SHOWERS...FOG AND STRATUS.
.SATURDAY...SHRA LIKELY WITH MVFR OR LOWER. N WINDS 25-30G35KT.
.SUNDAY...MOST LIKELY VFR WITH NW WINDS 20-25KT. POTENTIAL FOR GUSTS
UP TO 40KT.
.MONDAY...VFR. NW WINDS 15-20G25KT.
&&
.MARINE...
DENSE FOG ADVISORY REMAINS UP FOR ALL WATERS THROUGH 6AM DUE TO
FOG RESTRICTING VSBY TO LESS THAN 1 NM. THIS ADV MAY HAVE TO BE
EXTENDED THROUGH THE MID-MORNING HOURS.
SEAS COMING UP TO SCA LEVELS AND WILL CONTINUE THROUGH THURSDAY
NIGHT. WINDS ALSO INCREASE LATE TONIGHT AND REMAIN UP INTO
THURSDAY NIGHT. INCREASING LOW LEVEL JET THROUGH THURSDAY NIGHT
INCREASES POTENTIAL FOR SCA LEVEL GUSTS OVER THE COASTAL OCEAN
WATERS - SO HAVE KEPT HEADLINE AS SCA VICE CONVERTING TO AN SCA
FOR HAZARDOUS SEAS.
MARINE INVERSION APPEARS WILL LIMIT MIXING - SO WHILE COULD SEE
OCCASIONAL GUSTS TO 25 KT OVER THE REMAINDER OF THE WATERS FROM
LATE TONIGHT INTO THURSDAY NIGHT - DO NOT HAVE CONFIDENCE TO ISSUE
SCA AT THIS TIME FOR THE NON-OCEAN ZONES.
THERE IS A GOOD POTENTIAL FOR SCA CONDITIONS TO CONTINUE THROUGH THE
UPCOMING WEEKEND AS LOW PRESSURE FORMS OVER THE WATERS ON FRI AND
LIFTS SLOWLY TO THE NORTH AND EAST. SCA CONDITIONS ARE BECOMING
INCREASINGLY LIKELY...WITH THE POTENTIAL FOR GALE CONDITIONS SAT
INTO SUN. WINDS AND SEAS BEGIN TO SUBSIDE LATE SUN INTO MON WITH
HIGH PRESSURE BUILDING IN FROM THE GREAT LAKES REGION.
&&
.HYDROLOGY...
THERE IS THE POTENTIAL FOR AROUND 3/4 TO 1 INCH BASIN AVERAGE QPF
THURSDAY AND THURSDAY NIGHT WITH LOCALLY HIGHER AMOUNTS.
DO NOT EXPECT ANY WIDESPREAD FLOOD THREAT THURSDAY FROM ANY
SHRA/TSRA BUT COULD SEE SOME MINOR FLOODING UNDER ANY STRONGER
CONVECTION - ESPECIALLY IF THERE IS ANY TRAINING.
THE HEAVIEST RAINFALL IN THIS TIME FRAME WILL BE LATE THURSDAY
NIGHT - WITH LOCALIZED RAINFALL RATES OF 1-1.5 INCHES/HR POSSIBLE
NOTING PRECIPITABLE WATERS OF 1.5-1/75 INCHES IN THIS TIME
FRAME. IF THESE RATES ARE REALIZED...ESPECIALLY IF THE STORMS
PRODUCING THEM PASS OVER AREAS RECEIVING LOCALLY HEAVY RAINFALL
THURSDAY...THERE IS THE POTENTIAL FOR LOCALIZED FLASH FLOODING.
THE THREAT FOR LOCALIZED HEAVY RAINFALL WILL CONTINUE INTO THE FIRST
HALF OF FRI WITH EMBEDDED CONVECTION. THEREAFTER...A STRATIFORM RAIN
AND/OR SHOWERS DEVELOPS ON THE BACKSIDE OF DEVELOPING LOW PRESSURE.
AN ADDITIONAL 1 TO 2 INCHES OF RAINFALL IS POSSIBLE FRI INTO SAT.
THIS MAY EXACERBATE ANY ONGOING FLOODING. RAIN MAY LINGER EVEN INTO
SUN BASED ON LATEST MODEL TRENDS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...DENSE FOG ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ330-335-338-
340-345-350-353-355.
SMALL CRAFT ADVISORY UNTIL 6 AM EDT FRIDAY FOR ANZ350-353-355.
&&
$$
SYNOPSIS...MALOIT/DW
NEAR TERM...MALOIT/MPS
SHORT TERM...MALOIT
LONG TERM...DW
AVIATION...PICCA/MET
MARINE...MALOIT/DW
HYDROLOGY...MALOIT/DW
AREA FORECAST DISCUSSION
NWS NEW YORK NY
751 PM EDT WED MAY 22 2013
.SYNOPSIS...
A STALLED FRONT WILL REMAIN IN THE VICINITY INTO THURSDAY. A COLD
FRONT WILL THEN SLOWLY APPROACH FROM THE WEST THURSDAY...THEN MOVE
INTO WESTERN PORTIONS OF THE TRI-STATE THURSDAY NIGHT. A WAVE OF
LOW PRESSURE DEVELOPS ALONG THIS SLOW MOVING COLD FRONT
FRIDAY...REMAINS JUST EAST OF THE REGION SATURDAY...AND THEN
TRACKS NORTH ALONG THE NEW ENGLAND COAST ON SUNDAY. HIGH PRESSURE
OVER THE GREAT LAKES BUILDS SOUTHEAST ACROSS THE AREA MONDAY INTO
TUESDAY. A WARM FRONT WILL THEN APPROACH FROM THE SOUTHWEST BY MID
WEEK.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
MOST OF THE SHOWERS AND THUNDERSTORMS NORTH OF THE CWA ARE
BEGINNING TO DISSIPATE WITH LOSS OF DIURNAL HEATING. WOULD NOT
EXPECT MUSH IN THE WAY OF CONVECTIVE ACTIVITY...MAINLY FOR THE
NORTHERN THIRD OF THE CWA...FOR THE REST OF THE EARLY EVENING
HOURS.
HOWEVER...BROKEN LINE OF SHOWERS AND THUNDERSTORMS SLOWLY TRYING
TO ORGANIZE OVER CENTRAL PA. WITH RELATIVELY LIGHT UPPER LEVEL
FLOW...THESE STORMS WILL TAKE SOME TIME APPROACHING WESTERN
PORTIONS OF THE CWA...AND IF THEY DO MAKE IT HERE...IT WILL NOT BE
UNTIL LATE TONIGHT WITH LATEST HRRR INDICATING SCT ACTIVITY AFTER
08Z. WILL CONTINUE TO CARRY SLIGHT CHANCE...AS MARINE LAYER SHOULD
CONTINUE TO INHIBIT CONVECTIVE ACTIVITY FROM FORMING.
WITH MARINE LAYER INTACT - WOULD EXPECT LOW CLOUD DECK TO RE-
ESTABLISH ITSELF ACROSS THE AREA OVERNIGHT. COULD SEE PATCHY FOG
AS WELL - POSSIBLY LOCALLY DENSE NEAR THE ATLANTIC COAST.
FOR LOWS USED A BLEND OF 50 PERCENT MAV GUIDANCE WITH 25 PERCENT
MET GUIDANCE AND 25 PERCENT NAM 2-METER TEMPERATURES. FORECASTING
LOWS 10-15 DEGREES ABOVE NORMAL.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
MIXING ASSOCIATED WITH PASSING 700-500 HPA SHORTWAVE THURSDAY
MORNING SHOULD ERODE THE MARINE INVERSION - BUT STILL WILL BE
LEFT WITH QUITE A BIT OF MID TO HIGH CLOUDS WITH MOIST SW FLOW
ALOFT.
PRE-FRONTAL TROUGH MOVING INTO THE LOWER HUDSON VALLEY/NE NJ
THURSDAY AFTERNOON SHOULD SERVE AS TRIGGER FOR SCT-NUMEROUS SHRA
WITH EMBEDDED TSRA. LIKELY POPS MAINLY FROM NYC-INTERIOR SW CT
ZONES ON W AND CHANCE POPS EAST OF THAT LINE. SOME SUGGESTION FROM
NAM/GFS THAT EASTERN AREAS WILL REMAIN DRY THURSDAY...BUT FOR NOW
TOO MUCH LOW-MID LEVEL MOISTURE AND INCREASING LOW LEVEL JET TO
FORECAST THAT AT THIS TIME.
WITH 30-35 KT BULK SHEAR...1000-1500 J/KG OF CAPE AND BULK
RICHARDSON NUMBERS 15-30 HAVE THE POTENTIAL FOR ISOLATED SEVERE
STORMS THURSDAY AFTERNOON ACROSS NE NJ/LOWER HUDSON VALLEY AND
MAYBE NYC AND SW CT ZONES. MAIN THREAT IS GUSTY WINDS AND LARGE
HAIL. ALSO NEED TO WATCH FOR LOW LEVEL HELICITY WITH S SFC FLOW
AND SW FLOW AT 850 HPA.
FOR HIGHS THURSDAY USED A BLEND OF MIXING DOWN FROM 975 HPA NEAR
THE COAST AND 950 HPA INLAND...WITH NAM 2-METER TEMPERATURES AND A
BLEND OF MAV AND MET GUIDANCE. FORECASTING VALUES AROUND NORMAL
EAST TO A FEW DEGREES ABOVE NORMAL WEST.
DEEP SW FLOW ALOFT...BECOMES DIFFLUENT AT 500 HPA AFTER MIDNIGHT.
HAVE THE POTENTIAL FOR HEAVY RAINFALL AS A RESULT. REFER TO THE
HYDROLOGY SECTION FOR DETAILS. SEVERE THREAT COULD LINGER INTO THE
EVENING ACROSS WESTERN ZONES AS WELL.
FOR LOWS THURSDAY NIGHT USED A BLEND OF MAV/MET GUIDANCE WITH
VALUES FORECAST AROUND 10 DEGREES ABOVE NORMAL.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
MODELS HAVE TRENDED CONSIDERABLY SLOWER AND DEEPER WITH THE
APPROACHING UPPER TROUGH OVER THE MID SECTION OF THE COUNTRY. THERE
IS VERY GOOD AGREEMENT WITH THE 12Z GFS AND ECMWF ON TAKING A CLOSED
UPPER LOW FROM THE MID ATLANTIC STATES ON FRI NE TO OVER NEW ENGLAND
ON SUN. THE NAM AND GGEM ARE TRENDING IN THAT DIRECTION...BUT ARE
MORE PROGRESSIVE BEYOND 00Z SAT. PREFERENCE AT THIS TIME IS TO GO
WITH THE SLOWER GFS/ECMWF SOLUTION BASED ON MODEL TRENDS AND THE RUN
TO RUN CONTINUITY BEING EXHIBITED OVER THE LAST SEVERAL MODEL CYCLES.
AS FOR SENSIBLE WEATHER...THIS RESULTS IN A WET...COOL WEEKEND WITH
THE POTENTIAL FOR ANOTHER 1 TO 2 INCHES OF RAINFALL IN THE FRI-SAT
TIME FRAME. SINCE THIS IS A BIG ADJUSTMENT FROM THE PREVIOUS
FORECAST...HAVE RAMPED UP RAIN CHANCES FRI INTO SAT...BUT THESE MAY
BE UNDERDONE...ESPECIALLY FOR SAT WHERE THERE IS A TREND IN THE
FORECAST TO DRY THINGS OUT SAT INTO SUN. LATEST ECMWF KEEPS
CONDITIONS WET INTO SUN WITH A GUSTY NW FLOW ON THE BACKSIDE. SO
THIS IS THE POINT IN THE FORECAST WHERE CONDITIONS MAY CONTINUE TO
DETERIORATE WITH SUBSEQUENT MODEL RUNS.
ONCE AGAIN...WHILE THE FORECAST HAS AGGRESSIVELY TAKEN A DOWNWARD
NOTE FOR THE HOLIDAY WEEKEND...RAIN CHANCES MAY BE ON THE INCREASE
SAT INTO SUN BASED ON LATEST TRENDS IN THE MODEL GUIDANCE.
IN ADDITION...SOME OF THE RAINFALL ON FRI...OR AT LEAST THE FIRST
HALF OF THE DAY MAY BE CONVECTIVE WITH LOCALIZED HEAVY RAINFALL WITH
ANY EMBEDDED THUNDERSTORMS. THEREAFTER...THE AIRMASS STABILIZES IN
THE LOW-LEVELS WITH POST-FRONTAL RAIN/SHOWERS...PRIMARILY DRIVEN BY
FRONTOGENETIC FORCING ON THE BACKSIDE OF THE LOW. WIND GUSTS SAT
INTO SUN MAY BE UP TO 35 MPH...BUT THIS IS THE POTENTIAL...WITH THE
FORECASTS SIGNIFICANTLY LOWER AT THIS TIME.
AS FOR TEMPS...DAYTIME HIGHS WITH THE CLOUD COVER AND RAIN WILL BE 5
TO 10 DEGREES BELOW NORMAL. STAYED BELOW GUIDANCE. OVERNIGHT LOWS
WILL BE CLOSE TO SEASONABLE. A GRADUAL WARM-UP TO NEAR SEASONABLE
LEVELS IS THEN FORECAST MON-WED.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
A STATIONARY FRONTAL BOUNDARY WILL REMAIN NORTH OF THE TERMINALS
THROUGH THE FORECAST PERIOD. A LOW PRESSURE SYSTEM AND COLD FRONT
APPROACH SLOWLY FROM THE WEST DURING THE DAY THURSDAY.
MVFR CEILINGS AND FOG DEVELOP LATE THIS EVENING AND OVERNIGHT FOR
THE NEW YORK CITY TERMINALS AND WEST. TO THE EAST IFR CEILINGS AND
FOG WILL BE DEVELOPING...WITH LIFR AT TIMES AFTER 07Z. MVFR
CONDITIONS DURING THURSDAY WITH SHOWERS DEVELOPING AFTER 17Z.
ISOLATED THUNDERSTORMS WILL BE POSSIBLE ALSO.
WIND WILL BE GENERALLY FROM THE SOUTH 10 KT OR LESS THROUGH LATE
TONIGHT...THEN SOUTH TO SOUTHWEST 10 TO 15 KT LATE TONIGHT INTO
THURSDAY.
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: AMENDMENTS LATE THIS EVENING FOR MVFR
CEILINGS AND FOG DEVELOPING. AMENDMENTS FOR TIMING OF SHOWERS AND
THUNDERSTORMS THURSDAY. SOME THUNDERSTORMS MAY PRODUCE GUSTY
WINDS.
KLGA FCSTER COMMENTS: AMENDMENTS LATE THIS EVENING FOR MVFR
CEILINGS AND FOG DEVELOPING. AMENDMENTS FOR TIMING OF SHOWERS AND
THUNDERSTORMS THURSDAY. SOME THUNDERSTORMS MAY PRODUCE GUSTY WINDS.
KEWR FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS TONIGHT. AMENDMENTS
FOR TIMING OF SHOWERS AND THUNDERSTORMS THURSDAY. SOME THUNDERSTORMS
MAY PRODUCE GUSTY WINDS.
KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS TONIGHT. MVFR
CEILINGS AND FOG POSSIBLE AFTER 09Z. AMENDMENTS FOR TIMING OF
SHOWERS AND THUNDERSTORMS THURSDAY. SOME THUNDERSTORMS MAY PRODUCE
GUSTY WINDS.
KHPN FCSTER COMMENTS: AMENDMENTS LATE THIS EVENING FOR MVFR
CEILINGS AND FOG DEVELOPING...WITH IFR AT TIMES. AMENDMENTS FOR
TIMING OF SHOWERS AND THUNDERSTORMS THURSDAY. SOME THUNDERSTORMS MAY
PRODUCE GUSTY WINDS.
KISP FCSTER COMMENTS: AMENDMENTS THIS EVENING FOR IFR CEILINGS AND
FOG. AMENDMENTS THURSDAY FOR SLOWLY IMPROVING CONDITIONS. SHOWERS
LATE AFTERNOON THURSDAY.
.OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY...
.THURSDAY NIGHT-FRIDAY...NUMEROUS SHRA...ISOLATED TSTMS POSSIBLE.
MVFR TO IFR IN SHOWERS...FOG AND STRATUS.
.SATURDAY...SHRA LIKELY WITH MVFR OR LOWER. N WINDS 25-30G35KT.
.SUNDAY...MOST LIKELY VFR WITH NW WINDS 20-25KT. POTENTIAL FOR GUSTS
UP TO 40KT.
.MONDAY...VFR. NW WINDS 15-20G25KT.
&&
.MARINE...
WENT AHEAD AND EXPANDED THE DENSE FOG ADVISORY TO INCLUDE ALL
WATERS AS WEB-CAMS NEAR LI SOUND...MAINLY EASTERN LI SOUND...
INDICATED LOWERING VSBY. SO FAR...DENSE FOG ADVISORY WILL EXPIRE
AT 6 AM THURSDAY...BUT THIS MAY HAVE TO BE EXTENDED THROUGH THE
MID-MORNING HOURS.
SEAS ARE RUNNING 1-2 FT BELOW WAVEWATCH FORECAST - SO FOR NOW HAVE
TAKEN 1 FT OFF OF WAVEWATCH THROUGH THURSDAY NIGHT. STILL EXPECT
SEAS TO COME UP TO SCA LEVELS TONIGHT AND CONTINUE THROUGH
THURSDAY NIGHT. WINDS ALSO INCREASE LATE TONIGHT AND REMAIN UP
INTO THURSDAY NIGHT. INCREASING LOW LEVEL JET THROUGH THURSDAY
NIGHT INCREASES POTENTIAL FOR SCA LEVEL GUSTS OVER THE COASTAL
OCEAN WATERS - SO HAVE KEPT HEADLINE AS SCA VICE CONVERTING TO AN
SCA FOR HAZARDOUS SEAS.
MARINE INVERSION APPEARS WILL LIMIT MIXING - SO WHILE COULD SEE
OCCASIONAL GUSTS TO 25 KT OVER THE REMAINDER OF THE WATERS FROM
LATE TONIGHT INTO THURSDAY NIGHT - DO NOT HAVE CONFIDENCE TO ISSUE
SCA AT THIS TIME FOR THE NON-OCEAN ZONES.
THERE IS A GOOD POTENTIAL FOR SCA CONDITIONS TO CONTINUE THROUGH THE
UPCOMING WEEKEND AS LOW PRESSURE FORMS OVER THE WATERS ON FRI AND
LIFTS SLOWLY TO THE NORTH AND EAST. SCA CONDITIONS ARE BECOMING
INCREASINGLY LIKELY...WITH THE POTENTIAL FOR GALE CONDITIONS SAT
INTO SUN. WINDS AND SEAS BEGIN TO SUBSIDE LATE SUN INTO MON WITH
HIGH PRESSURE BUILDING IN FROM THE GREAT LAKES REGION.
&&
.HYDROLOGY...
THERE IS THE POTENTIAL FOR AROUND 3/4 TO 1 INCH BASIN AVERAGE QPF
THURSDAY AND THURSDAY NIGHT WITH LOCALLY HIGHER AMOUNTS.
DO NOT EXPECT ANY WIDESPREAD FLOOD THREAT THURSDAY FROM ANY
SHRA/TSRA BUT COULD SEE SOME MINOR FLOODING UNDER ANY STRONGER
CONVECTION - ESPECIALLY IF THERE IS ANY TRAINING.
THE HEAVIEST RAINFALL IN THIS TIME FRAME WILL BE LATE THURSDAY
NIGHT - WITH LOCALIZED RAINFALL RATES OF 1-1.5 INCHES/HR POSSIBLE
NOTING PRECIPITABLE WATERS OF 1.5-1/75 INCHES IN THIS TIME
FRAME. IF THESE RATES ARE REALIZED...ESPECIALLY IF THE STORMS
PRODUCING THEM PASS OVER AREAS RECEIVING LOCALLY HEAVY RAINFALL
THURSDAY...THERE IS THE POTENTIAL FOR LOCALIZED FLASH FLOODING.
THE THREAT FOR LOCALIZED HEAVY RAINFALL WILL CONTINUE INTO THE FIRST
HALF OF FRI WITH EMBEDDED CONVECTION. THEREAFTER...A STRATIFORM RAIN
AND/OR SHOWERS DEVELOPS ON THE BACKSIDE OF DEVELOPING LOW PRESSURE.
AN ADDITIONAL 1 TO 2 INCHES OF RAINFALL IS POSSIBLE FRI INTO SAT.
THIS MAY EXACERBATE ANY ONGOING FLOODING. RAIN MAY LINGER EVEN INTO
SUN BASED ON LATEST MODEL TRENDS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...DENSE FOG ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ330-335-338-
340-345-350-353-355.
SMALL CRAFT ADVISORY UNTIL 6 AM EDT FRIDAY FOR ANZ350-353-355.
&&
$$
SYNOPSIS...MALOIT/DW
NEAR TERM...MALOIT/MPS
SHORT TERM...MALOIT
LONG TERM...DW
AVIATION...MET
MARINE...MALOIT/DW
HYDROLOGY...MALOIT/DW
AREA FORECAST DISCUSSION
NWS ALBANY NY
732 PM EDT WED MAY 22 2013
.SYNOPSIS...
A COLD FRONT WILL SLOWLY APPROACH THE REGION INTO FRIDAY. PERIODS
OF SHOWERS AND THUNDERSTORMS WILL PRECEDE THE FRONT. THE RAIN WILL
BE HEAVY AT TIMES. COOLER AND SHOWERY CONDITIONS WILL PERSIST
INTO THE FIRST HALF OF THE MEMORIAL DAY WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
SEVERE THUNDERSTORM WATCH #210 REMAINS IN IN EFFECT UNTIL 10 PM
FOR HERKIMER...HAMILTON...MONTGOMERY...FULTON...WARREN...SARATOGA
AND WASHINGTON COUNTIES. ADDITIONAL CONVECTION WILL MOVE ACROSS
THIS AREA AND HAVE THE BETTER SHEAR ACROSS THIS AREA.
THE WATCH HAS BEEN CANCELLED FOR THE REST OF THE FORECAST.
CONVECTION HAS BEEN HAVING A HARD TIME MAINTAINING ITSELF. MODEL
GUIDANCE IS NOT IS AGREEMENT HANDLING THE THREAT OF CONVECTION
THROUGH TONIGHT. HAVE KEEP FORECAST SIMPLE WITH CHANCE POPS. USED
SCATTERED FOR COVERAGE WHERE WATCH IS STILL IN EFFECT.
AS OF 433 PM EDT...MAIN BAND OF CONVECTION AND ASSOCIATED SEVERE
WEATHER AND FLOODING RAINFALL CONTINUES TO PROGRESS EAST. SOME
REPORTS OF WIND DAMAGE IN SCHENECTADY AND SCHOHARIE COUNTIES.
MEANWHILE...HEAVY RAINFALL...RADAR ESTIMATE SHOWS 2-3 INCHES HAS
LED TO URBAN FLOODING IN SCHENECTADY COUNTY.
WITH MCS-LIKE SYSTEM CONTINUING TO TRACK NORTHEAST THROUGH THE
LATE AFTERNOON SEVERE THREAT/FLASH FLOOD THREAT WILL CONTINUE EAST.
ATTENTION WILL TURN TO ACTIVITY FOR LATER THIS AFTERNOON AND
TONIGHT. CURRENTLY TO OUR WEST LAKE BREEZES ARE FORCING ISOLD
TSRA. HRRR SHOWS LAKE BREEZE TO BLOSSOM WITH CONVECTION INTO LATER
THIS AFTERNOON AND EVENING AS LARGER SCALE ASCENT TRANSLATES
EASTWARD FROM LOWER LAKES. INSTABILITY HAS RECOVERED ACROSS
WESTERN CWA WITH MESOANALYSIS SHOWS CAPES IN 1500-2000 J/KG RANGE.
BULK SHEAR WILL REMAIN FAVORABLE FOR SEVERE STORMS WITH VALUES
INTO THE 30-40 KNOT RANGE. WILL CARRY ENHANCED WORDING TO COINCIDE
WITH WATCH...THEN SCT SHRA/TSRA THROUGH REMAINDER OF OVERNIGHT AS
WAIT TO SEE HOW CONVECTION EVOLVES.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
COLD FRONT SLOWLY APPROACHES THE REGION ON THURSDAY...NOT CLEARING
CWA UNTIL FRIDAY MORNING.
SLOWLY MOVING FRONT WILL PROVIDE ENVIRONMENT FOR BOUTS OF HEAVY
RAIN THROUGH THE PERIOD. PWATS REMAIN IN THE 1.5 INCH RANGE
THROUGH THURSDAY...ONLY SLOWLY DROPPING OFF INTO FRIDAY.
APPROACHING UPPER LEVEL JET TOMORROW BRINGS RIGHT REAR QUAD INTO
FORECAST AREA FOR THE AFTERNOON. SEE HYDRO SECTION FOR DISCUSSION
ON FLOOD RISK.
SEVERE POTENTIAL TOMORROW IS NOT CLEAR CUT NOW. MODEL CAPE LOOKS
TO BE IN THE 1000 J/KG RANGE WITH BULK SHEAR RESPECTABLE IN THE
30-40 KNOT RANGE. MID LEVEL LAPSE RATES ARE RELATIVELY WEAK AT
5.5C/KM. SPC HAS REGION IN SEE TEXT. FROM TODAY/S VANTAGE POINT
THAT LOOKS APPROPRIATE.
WITH COLD FRONT MOVING THROUGH ON FRIDAY...SOME DIMINISHING IN
PRECIP EXPECTED FOR PART OF FRIDAY. HOWEVER GFS AND ECMWF COMING
INTO AGREEMENT ON CUT OFF MIGRATING SLOWLY FROM DELMARVA INTO NEW
ENGLAND INTO THE HOLIDAY WEEKEND. THIS WILL KEEP THE THREAT OF
RAIN/SHOWERS IN THE FORECAST FOR FRIDAY. WITH CWA ON COOL SIDE OF
SURFACE LOW TRACK...INSTABILITY LOOKS NEAR NIL. SO NO MENTION OF
TSRA FOR FRIDAY.
MINS ON SATURDAY MORNING IN ADIRONDACKS ARE FORECAST IN MID 30S.
THIS WOULD MEAN THREAT OF FROST GIVEN BEGINNING OF THE GROWING
SEASON THERE. WILL DEPEND ON CLOUDS AND PRECIP.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
MODEL GUIDANCE HAS TRENDED TO A WET START TO THE HOLIDAY WEEKEND
ALONG WITH CHILLY TEMPERATURES DUE TO MORE CLOUD COVER.
THE MODEL GUIDANCE HAS COME INTO FAIRLY GOOD AGREEMENT THAT AN AREA
OF LOW PRESSURE WILL FORM ON THE COLD FRONT JUST OFF COAST NEAR CAPE
COD AS SHORT WAVES MOVE THROUGH THE LONGWAVE. AN UPPER LEVEL LOW IS
EXPECTED TO DEVELOP OVER THE MID ATLANTIC REGION FRIDAY NIGHT WITH
ADDITIONAL SHORT WAVES MAINTAINING THIS UPPER LOW WITH IT MOVING
GRADUALLY NORTHWARD UP THE COAST. THE LOW ALONG THE BOUNDARY WILL
SLOW THE FRONT`S EASTWARD PROGRESS AND THROW RAIN SHOWERS AND CLOUDS
BACK ACROSS NEW ENGLAND AND EASTERN NEW YORK STATE SATURDAY. THE
REGION WILL REMAIN UNDER CYCLONIC FLOW THROUGH THE WEEKEND WITH
UPPER RIDGING NOT EXPECTED TO BEGIN TO BUILD IN UNTIL TUESDAY. AT
THE SURFACE...HIGH PRESSURE SHOULD BEGIN TO BUILD IN MONDAY AND
ESPECIALLY TUESDAY. IT APPEARS THE HIGH SHOULD HOLD ON FOR WEDNESDAY.
AS FOR TEMPERATURES...CHILLY. TEMPERATURES ARE EXPECTED TO RUN 10 TO
15 DEGREES BELOW NORMAL SATURDAY AND AGAIN SUNDAY. BRISK AND GUSTY
NORTHWESTERLY WINDS WILL ONLY ADD TO THE CHILL. TEMPERATURES ARE
EXPECTED TO MODERATE TOWARD SEASONABLE LEVELS MONDAY WITH THE HELP
OF SUNSHINE BUT STILL BE BELOW NORMAL BY AROUND 5 DEGREES.
THE GROWING SEASON IS UNDERWAY ACROSS THE MID HUDSON VALLEY...
GREATER CAPITAL DISTRICT...LAKE GEORGE SARATOGA REGION...THE MOHAWK
VALLEY...EASTERN CATSKILLS...TACONICS...BERKSHIRES...BENNINGTON AND
EASTERN WINDHAM COUNTIES VT AND LITCHFIELD COUNTY. IT WILL START ON
MAY 25TH FOR THE SOUTHERN ADIRONDACKS AND WESTERN WINDHAM COUNTY.
NIGHTTIME LOWS OVER THE WEEKEND ARE EXPECTED TO BE IN THE 40S WITH
30S ACROSS THE HIGHER TERRAIN. WITH THE EXPANSION OF THE GROWING
SEASON BY THIS TIME FROST ADVISORIES MIGHT BE NEEDED. CONDITIONS
WILL BE MORE FAVORABLE FOR FROST SUNDAY NIGHT/MONDAY MORNING AND
MONDAY NIGHT/TUESDAY MORNING.
&&
.AVIATION /23Z WEDNESDAY THROUGH MONDAY/...
PREVAILING VFR CONDITIONS WITH PERIODS OF MVFR TONIGHT WILL DOMINATE
THE TAF PERIOD WITH A CONTINUED THREAT FOR VCSH/VCTS.
THUNDERSTORM THREAT WILL PREVAIL FOR THE NEXT COUPLE OF HOURS...AS
LINGERING DAYTIME INSTABILITY CONTINUES TO FUEL THESE STORMS. HAVE
INCLUDED TEMPO GROUPS AT KGFL/KALB TO ACCOUNT FOR ANY REMNANT
THUNDERSTORM ACTIVITY. ELSEWHERE...THE THREAT FOR VCSH WILL REMAIN
THROUGHOUT THE NIGHT AS SHOWERS/THUNDERSTORMS APPROACH FROM THE
WESTERN NY/MID-ATLANTIC REGION. A COMBINATION OF SATURATED
LOW-LEVELS AND RECENT RAINFALL SHOULD ALLOW FOR MVFR
CEILINGS/VISIBILITIES TO DEVELOP AT ALL TAF SITES DURING THE
OVERNIGHT HOURS. KGFL/KPOU MAY BRIEFLY DIP TO IFR LEVELS TOWARDS
DAYBREAK BUT CONFIDENCE REMAINS ON THE LOWER SIDE AT THIS TIME.
THE THREAT FOR SHOWERS/THUNDERSTORMS WILL INCREASE DURING THE DAY
THURSDAY AS RENEWED DAYTIME HEATING COMMENCES...WITH EXPECTED
SCATTERED TO WIDESPREAD THUNDERSTORM COVERAGE BY THE EARLY AFTERNOON
HOURS. FLYING CONDITIONS THURSDAY WILL FLUCTUATE BETWEEN VFR/MVFR
WITH PERIODS OF IFR ASSOCIATED WITH SHOWER/THUNDERSTORM ACTIVITY.
HAVE INTRODUCED LLWS INTO THE TAFS THROUGH THE OVERNIGHT PERIOD AS A
LOW-LEVEL JET PASSES OVERHEAD WITH LIGHT SOUTHERLY SURFACE WINDS
GENERALLY LESS THAN 5 KNOTS. THESE SOUTHERLY WINDS WILL INCREASE
SLIGHTLY DURING THE DAY THURSDAY TO 5-10 KNOTS...WITH THE POTENTIAL
FOR HIGHER GUSTS ASSOCIATED WITH ANY THUNDERSTORMS.
OUTLOOK...
THU-THU NIGHT...MVFR WITH IFR POSSIBLE. -SHRA/-TSRA LIKELY.
FRI...MAINLY VFR. CHC -TSRA MAINLY IN THE AM.
SAT-MON...VFR/MVFR. CHC -SHRA.
&&
.FIRE WEATHER...
NO FIRE WEATHER CONCERNS INTO SATURDAY. PERIODS OF RAIN...MODERATE
TO HEAVY AT TIMES WILL CONTINUE INTO THE HOLIDAY WEEKEND.
RH VALUES WILL INCREASE TO 85 TO 100 PERCENT TONIGHT...AND
THURSDAY NIGHT...AND LOWER TO 45 TO 60 PERCENT THURSDAY AFTERNOON.
WINDS WILL GENERALLY BE SOUTH AT 5 TO 10 MPH.
&&
.HYDROLOGY...
ECMWF AND GFS VERY AGGRESSIVE IN BRINGING HEAVY RAINFALL INTO CWA
INTO THE MEMORIAL DAY WEEKEND. OPERATIONAL ECMWF AND GFS PRODUCE
5-7.5 INCHES OF RAIN IN CWA INTO SUNDAY. GEFS SHOW AVERAGE OF 2.25
INCHES THROUGH WEEKEND WITH 4 MEMBERS PUSHING IN EXCESS OF 3
INCHES. WHILE NOT QUITE READY TO ACCEPT TOTALS OF EURO AND
GFS...ENOUGH GUIDANCE AVAILABLE TO AT LEAST WARRANT POTENTIAL OF
HEAVY RAIN THREAT IN HWO. FIRST CHALLENGE FOR HEAVY RAIN WILL COME
TOMORROW WITH SLOWLY MOVING FRONT. EASTERN CWA AND CENTRAL CWA
HAVE SEEN HEAVIEST RAIN OVER THE LAST TWO DAYS AND WOULD APPEAR TO
BE THE REGION WHERE FLASH FLOOD THREAT IS AT HIGHEST.
WILL MONITOR CLOSELY FOR AT LEAST POTENTIAL OF FLASH FLOOD OR
FLOOD WATCH THURSDAY INTO WEEKEND.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...OKEEFE
NEAR TERM...IAA/OKEEFE
SHORT TERM...OKEEFE
LONG TERM...IAA
AVIATION...IRL
FIRE WEATHER...OKEEFE
HYDROLOGY...SNYDER
AREA FORECAST DISCUSSION
NWS ALBANY NY
1045 AM EDT TUE MAY 21 2013
.SYNOPSIS...
WARM AND HUMID CONDITIONS WILL CONTINUE TODAY WITH A
FRONTAL BOUNDARY BECOMING STATIONARY ACROSS UPSTATE NEW YORK AND NEW
ENGLAND. A DISTURBANCE MOVING ALONG THE FRONTAL BOUNDARY WILL FOCUS
SOME SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON AND EVENING
HOURS ESPECIALLY NORTH OF THE IMMEDIATE CAPITAL REGION. THE HUMID
AND UNSETTLED WEATHER CONTINUES TOMORROW AND THURSDAY WITH MORE
CHANCES OF SHOWERS AND THUNDERSTORMS BEFORE A COLD FRONT RETURNS
DRIER AND COOLER WEATHER FOR FRIDAY AND INTO THE HOLIDAY WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1030 AM EDT...A BROAD RIDGE AT 500 HPA IS SITUATED OVER THE
EASTERN CONUS...WITH A SLOW MOVING UPPER LOW OVER THE CENTRAL
PLAINS. AT THE SURFACE...OUR REGION REMAINS IN A WARM SECTOR WITH
SKY COVERAGE BEGINNING TO CLEAR OUT SOUTH OF THE IMMEDIATE CAPITAL
REGION. A STATIONARY BOUNDARY IS SITTING JUST NORTH OF THE
IMMEDIATE CAPITAL REGION WHERE IT IS GENERATING A FEW SHOWERS OVER
THE NY/VT BORDER.
ADDITIONAL SHOWERS AND THUNDERSTORMS WILL DEVELOP DURING THE
HEATING OF THE DAY AS A SFC WAVE ALONG THE FRONT BEGINS TO
APPROACH THE AREA. OUR LOCAL HIRES WRF SUGGESTS THAT SOME SHOWERS
OR STORMS MAY BEGIN TO DEVELOP OVER THE HIGH TERRAIN BY THE LATE
MORNING OR EARLY AFTN HOURS. THE 3 KM HRRR GUIDANCE SEEMS TO SHOW
THAT IT COULD HOLD OFF UNTIL THE EARLY TO MID AFTN HOURS. IN
EITHER CASES...ONCE SHOWERS AND THUNDERSTORMS DEVELOP THEY SHOULD
MOVE IN A GENERA-LY WEST TO EAST MANNER.
WITH MAX TEMPS REACHING THE UPPER 70S TO MID 80S ACROSS THE
AREA...AND TDS WELL INTO THE 60S...THERE SHOULD BE SUFFICIENT
INSTABILITY FOR TSTMS. WITH 0-6 KM BULK SHEAR OF 20-35 KTS AND MID
LEVEL LAPSE RATES OF ABOUT 6-7 DEGREES C PER KM...THERE COULD BE
ENOUGH OF THE INGREDIENTS IN PLACE TO ALLOW A STORM OR TWO TO
BECOME STRONG TO POSSIBLY SEVERE. WE WILL HAVE TO WATCH IF ANY
STORMS GROW TALL ENOUGH TO PRODUCE SOME DAMAGING WIND GUSTS. WE
WILL HIGHLIGHT THIS IN OUR HWO AS WELL.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
ONGOING CONVECTION THIS EVENING LOOKS TO CONTINUE INTO TONIGHT AS
THE SFC WAVE MOVES ALONG THE BOUNDARY. THE BEST CHC FOR SEEING
SHOWERS/TSTMS WILL BE ACROSS THE NORTHERN PORTION OF THE AREA.
WITH THE LOSS OF HEATING...ANY SVR THREAT WILL BE DIMINISHED...BUT
THUNDER SHOULD STILL CONTINUE DUE TO LINGERING ELEVATED
INSTABILITY OVERNIGHT. MIN TEMPS WILL CONTINUE TO BE MILD AND
MUGGY WITH UPPER 50S TO MID 60S ACROSS THE AREA.
THE SFC BOUNDARY WILL LIFT NORTHWARD AS A WARM FRONT ON WEDNESDAY.
THE RIDGE AXIS WILL START TO SHIFT EASTWARD AS THE UPPER LOW OVER
THE PLAINS SLOWLY MOVES EASTWARD. DESPITE THE WEAK LARGE SCALE
FORCING...THERE LOOKS TO BE A CONTINUED THREAT FOR SHOWERS/TSTMS AS
A PRE FRONTAL TROUGH MAY BE IN PLACE ACROSS OUR AREA BY AFTN.
PLENTY OF MOISTURE AND INSTABILITY WILL BE IN PLACE...ESP WITH
WARM TEMPS REACHING THE 80S IN MOST AREAS...AND TDS IN THE MID 60S
F. ANY STORM WILL AGAIN BE CAPABLE OF PRODUCING DAMAGING
WINDS/LARGE HAIL...AND SPC HAS PLACED A GOOD CHUNK OF OUR AREA IN
A SLIGHT RISK FOR SVR STORMS. WILL HIGHLIGHT THIS IN THE HWO AS
WELL.
SHOWERS AND THUNDERSTORMS MAY LINGER AGAIN INTO WEDNESDAY NIGHT
WITH CONTINUED MILD AND MUGGY CONDITIONS. MINS WILL ONLY DROP INTO
THE 60S...WITH MID TO UPPER 60S IN THE HUDSON VALLEY.
THE UPPER TROUGH WILL FINALLY BEGIN TO MAKE SOME STEADY EASTWARD
PROGRESS ON THURSDAY INTO THURSDAY NIGHT. A SFC COLD FRONT WILL
ADVANCE EASTWARD DURING THIS TIME AS WELL. THIS FRONT WILL BE A
FOCUS FOR ADDITIONAL SHOWERS AND THUNDERSTORMS...ESP FOR THURSDAY
AFTN INTO THURSDAY NIGHT. AHEAD OF THIS BOUNDARY...THERE WILL BE
ONE LAST WARM AND MUGGY DAY...WITH MAX TEMPS IN THE 70S. MIN TEMPS
WILL START TO COOL OFF BY THURSDAY NIGHT WILL THE BOUNDARY MOVING
THROUGH...WITH MINS IN THE 40S AND 50S ACROSS THE AREA...WITH THE
MILDEST TEMPS IN SOUTHEASTERN AREAS.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
A COLD FRONT SHOULD EXIT THE REGION THROUGH THE DAY FRIDAY WITH
LINGERING SHOWERS AND THUNDERSTORMS IN THE MORNING IN NY AND INTO
THE AFTERNOON IN WESTERN NEW ENGLAND. THERE SHOULD BE DECENT
BOUNDARY LAYER FORCING WITH A TIGHT THERMAL AND MOISTURE GRADIENT
ALONG THE COLD FRONT...SO WILL KEEP AN EYE FOR ANY STRONG
THUNDERSTORM POTENTIAL. BOUNDARY LAYER TEMPERATURES SHOULD FALL
THROUGH THE DAY...AND HIGH TEMPERATURES SHOULD BE CAPPED AROUND THE
MID 60S TO AROUND 70...BUT IN THE MID TO UPPER 50S IN THE SOUTHERN
ADIRONDACKS.
ONCE THE COLD FRONT IS GONE...HIGH PRESSURE GRADUALLY BUILDS IN
THROUGH THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK. SOME
LINGERING CLOUDINESS COULD AFFECT THE MID HUDSON VALLEY INTO WESTERN
NEW ENGLAND SATURDAY AS THE COLD FRONT COULD BE SLOW TO EXIT THOSE
AREAS. HOWEVER...ANY SHOWER ACTIVITY SHOULD REMAIN EAST OF OUR
AREA. HIGHS SATURDAY IN THE MID TO UPPER 60S...UPPER 50S SOUTHERN
ADIRONDACKS.
FOR SUNDAY AND MONDAY...INCREASING SUNSHINE AND SLOWLY MODERATING
TEMPERATURES. HIGHS SUNDAY IN THE UPPER 60S TO AROUND 70 AND ON
MONDAY...HIGHS AROUND 70 TO THE LOWER 70S. TEMPERATURES COOLER IN
THE SOUTHERN ADIRONDACKS BOTH DAYS.
&&
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
SOME TYPICAL EARLY MORNING LOW CLOUDS AND FOG AFFECTING ALL SITES
AND SHOULD LIFT BY 14Z WHEN CONDITIONS SHOULD BECOME VFR...EXCEPT
BY 16Z AT KPSF. THERE IS ANOTHER SMALL CLUSTER OF SHOWERS AND
THUNDERSTORMS OVER LAKE ONTARIO THAT COULD APPROACH KGFL LATE THIS
MORNING OR EARLY THIS AFTERNOON...BUT TOO EARLY AND TOO ISOLATED
TO MENTION IN TAF AT THIS TIME OTHER THAN PUTTING A VCSH.
MORE SHOWERS AND THUNDERSTORMS IN THE OH VALLEY AND CENTRAL GREAT
LAKES THIS MORNING COULD AFFECT OUR REGION LATE THIS AFTERNOON AND
EVENING...IF THEY HOLD TOGETHER TO TRACK THIS FAR EAST. AGAIN...DUE
TO UNCERTAINTIES...JUST PUTTING VCSH AT ALL SITES THIS AFTERNOON AND
EVENING. LATER IN THE EVENING...SOME FOG AND LOW CEILINGS COULD
POTENTIALLY FORM WITH MVFR CONDITIONS.
LIGHT WINDS SHOULD BECOME SOUTH TO SOUTHWEST AT 10 KT OR LESS
TODAY...THEN DIMINISH BACK TO LIGHT THIS EVENING AND TONIGHT.
OUTLOOK...
WED...VFR/MVFR CHC -SHRA/-TSRA ESPECIALLY DURING THE AFTN.
WED NIGHT...VFR/MVFR. AT KGFL AND KALB -SHRA/-TSRA LIKELY. AT
KPSF AND KPOU CHC -SHRA/-TSRA.
THU...MVFR WITH IFR POSSIBLE. -SHRA/-TSRA LIKELY.
THU NIGHT...VFR/MVFR. CHC -SHRA/-TSRA ESPECIALLY IN THE EVNG.
FRI...MAINLY VFR. CHC -TSRA MAINLY IN THE AM.
SAT...VFR. NO SIG WX.
&&
.FIRE WEATHER...
NO FIRE WEATHER CONCERNS THROUGH AT LEAST THURSDAY DUE TO ON AND OFF
SHOWERS AND THUNDERSTORMS ACROSS THE REGION. RH VALUES WILL RECOVER
TO NEAR 100 PERCENT AT NIGHT...AND RH VALUES WILL GENERALLY STAY
ABOVE 50 PERCENT DURING THE DAYTIME HOURS.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO SERVICE AREAS PROBLEMS ARE EXPECTED THE NEXT 5
DAYS. SOME LOCALLY HEAVY DOWNPOURS OF RAINFALL MAY OCCUR TODAY
THROUGH THURSDAY WITHIN ANY THUNDERSTORMS. 3-HR ZONAL FFG VALUES ARE
GENERALLY IN THE 2.4-3.1 INCH RANGE AT THIS TIME...WHICH ARE HIGH
FOR MID TO LATE MAY.
DUE TO THE SCATTERED NATURE OF THE SHOWERS AND THUNDERSTORMS...
BASIN AVERAGE QPF WILL BE HIGHLY VARIABLE THIS WEEK. THE BEST
THREAT FOR SEEING SIGNIFICANT AMOUNTS OF SHOWERS OR THUNDERSTORMS
WILL FROM THIS AFTERNOON INTO THIS EVENING AND AGAIN ON THURSDAY
AFTERNOON INTO THURSDAY NIGHT. WHILE IT/S DIFFICULT TO PINPOINT
EXACT AMOUNTS...GUIDANCE FROM THE WEATHER PREDICTION CENTER /WPC/
SUGGESTS THAT MOST AREAS WILL SEE BETWEEN ONE HALF INCH AND AN INCH
AND A HALF OF RAIN THROUGH SATURDAY EVENING...WITH THE HIGHEST
AMOUNTS ACROSS THE ADIRONDACKS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...FRUGIS/LFM
NEAR TERM...FRUGIS/LFM
SHORT TERM...FRUGIS
LONG TERM...NAS
AVIATION...NAS
FIRE WEATHER...FRUGIS
HYDROLOGY...FRUGIS/WASULA
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1019 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A BACKDOOR COLD FRONT WILL DROP SOUTH ACROSS THE REGION LATE
TONIGHT AND TUESDAY RESULTING IN BRIEFLY COOLER WEATHER ACROSS
EASTERN NEW ENGLAND AND CHANCE OF THUNDERSTORMS IN WESTERN NEW
ENGLAND. WARM AND HUMID CONDITIONS CONTINUE INTO THURSDAY AND
FRIDAY WITH SCATTERED SHOWERS AND STRONG THUNDERSTORMS POSSIBLE. A
COOLER AND LESS HUMID AIR MASS IS EXPECTED FOR THE COMING WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
10 AM UPDATE...
CLOUDS HAVE CLEARED ACROSS MUCH OF THE REGION...EXCEPT LOW CLOUDS
AND FOG CONTINUED ACROSS PORTIONS OF E COASTAL MA. MODELS SUGGEST
CLOUDS AND FOG WILL BRIEFLY ERODE THROUGH ABOUT 18Z...THEN LOW
CLOUDS FROM THE N AND NE WILL EXPAND SW ACROSS THE REGION 18-00Z
AS THE BACKDOOR FRONT PUSHES SW. THIS FRONT WILL REMAIN ACROSS
FAR NE ZONES INTO THE AFTERNOON WHICH WILL ALLOW TEMPS TO REACH
INTO THE 80S ACROSS A GOOD PORTION OF THE AREA...WITH UPPER 80S
LOWER CT VALLEY. COOLER READINGS WILL BE FOUND ALONG THE S COAST
AND ESPECIALLY NE MA AND SE NH AND THIS COOLER AIR WILL MOVE SW
AFT 18Z WITH TEMPS FALLING SHARPLY THROUGH THE 70S AND INTO THE
60S BY EVENING ACROSS MUCH OF EASTERN HALF OF NEW ENG...WITH 50S
NE MA.
NEXT CONCERN IS POTENTIAL FOR CONVECTION. SPC MESOANALYSIS
ALREADY SHOWING MLCAPES INCREASING TO 1000 J/KG IN THE CT VALLEY
AND EXPECT MLCAPES 1000-2000 J/KG ACROSS CENTRAL AND WESTERN NEW
ENG THIS AFTERNOON WITH HIGHER CAPES BECOMING MORE FOCUSED IN THE
CT VALLEY LATE AFTERNOON AS THE FRONT PUSHES SW. MID LEVEL LAPSE
RATES ARE FAVORABLE AROUND 6.5-7 C/KM. DEEP LAYER SHEAR IS
MARGINAL BUT VALUES 20-30 KT ARE CERTAINLY ENOUGH TO SUPPORT
SOME ORGANIZATION OF ANY STORMS THAT DEVELOP. SO WE ARE EXPECTING
SCT TSTMS TO DEVELOP IN THE INTERIOR WITH POTENTIAL FOR A FEW
STRONG TO SEVERE STORMS. HRRR IS TARGETING MASS PIKE REGION EARLY
THIS AFTERNOON WITH ACTIVITY SHIFTING FURTHER WEST TO THE CT
VALLEY MID/LATE AFTERNOON.
&&
.SHORT TERM /WEDNESDAY/...
BACK-DOOR COLD FRONT SHOULD MOVE FARTHER NORTH LATE TONIGHT INTO
WEDNESDAY AS A WARM FRONT. THIS SHOULD ALLOW FOR A WARMER DAY
ACROSS EASTERN MA. STILL NOT CONVINCED SYNOPTIC FLOW WILL BE
STRONG ENOUGH TO PREVENT LOCAL SEABREEZES FROM DEVELOPING...SO
TEMPERATURES WILL BE TRICKY ALONG THE IMMEDIATE COASTLINES.
AM CURRENTLY EXPECTING A BRIEF DIMINISHMENT OF ANY CONVECTION
LATE TONIGHT INTO WEDNESDAY MORNING...AS SUGGESTED BY CLIMATOLOGY.
INSTABILITY REGENERATES WEDNESDAY AFTERNOON...SO KEPT AT LEAST A
CHANCE OF SHOWERS AND THUNDERSTORMS IN THE FORECAST. THE LOWEST
RISK FOR SHOWERS AND THUNDERSTORMS WILL BE ACROSS THE CAPE AND
ISLANDS...WHERE ANOTHER ROUND OF LOW CLOUDS AND FOG WILL KEEP
TEMPERATURES LOWER.
USED A BLEND OF MOS GUIDANCE ONCE AGAIN FOR TEMPERATURES.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
HIGHLIGHTS...
* SCATTERED SHOWERS AND THUNDERSTORMS THURS INTO FRIDAY
* COOLER AND LESS HUMID FOR THE WEEKEND
CONFIDENCE LEVEL/MODEL GUIDANCE...MODERATE CONFIDENCE IN THE
OVERALL FORECAST...YET LOW CONFIDENCE ON MODEL PERFORMANCE. THE
00Z GFS/NAM SIGNIFICANTLY SLOWED DOWN THE DIGGING TROUGH FOR THE
NORTHEAST. THE REST OF THE MODEL GUIDANCE FOLLOWED SUIT BUT NOT AS
DRASTICALLY. LEANED FORECAST TOWARDS EC/UKMET WHICH WHERE IN
BETWEEN THE 12Z AND 00Z GUIDANCE AS WELL AS PREV FORECAST. OVERALL
HAVE HIGH CONFIDENCE THAT PRECIP WILL OCCUR THURS AND MODERATE
CONFIDENCE FOR FRIDAY. HIGH CONFIDENCE IN A COOL DOWN FOR THE WEEK
WITH MOD CONFIDENCE FOR SEASONAL TEMPS AND DRY FORECAST FOR
BEGINNING OF THE WORK WEEK.
DETAILS...
THURSDAY INTO FRIDAY...
APPROACHING UPPER LEVEL TROUGH WILL BRING A ROUND OF PRECIP AND
THUNDER TO THE REGION. STILL SOME TIMING ISSUES AS MODELS STILL
DIFFER ON EXACT LOCATION AND MESOSCALE PARAMETERS.
REGARDLESS...SOUTHERN NEW ENGLAND WILL BE LOCATED IN THE WARM SECTOR
OF THE SYSTEM ALLOWING HIGHER DEWPOINTS AND THEREFORE MUGGY
CONDITIONS. TEMPS WILL WARM INTO THE 80S. BELIEVE DIURNAL PRECIP
WILL BE THE MAIN TREAT FOR THIS DAY...WITH STRONG STORMS POSSIBLE.
MAIN THREAT OF THESE STORMS WILL BE HAIL...STRONG WINDS AND HEAVY
DOWNPOURS. A COLD FRONT WILL BEGIN TO APPROACH THE REGION THURSDAY
NIGHT AND MOVE THROUGH THE AREA ON FRIDAY. THIS WILL CHANGE THE
CONVECTIVE MODE TO MORE OF A POSSIBLE SQUALL LINE ON FRIDAY.
CONVECTIVE PARAMETERS APPEAR TO BE MORE IN LINE DUE TO THE SLOW DOWN
OF THE OVERALL SYSTEM. ONLY THING TRULY LACKING IS THE AMOUNT OF
INSTABILITY AS CLOUD DEBRIS WILL BE AROUND FROM THE PREV NIGHTS
SHOWERS/THUNDER. IF STORMS DO DEVELOP THEN BELIEVE THE MAIN THREAT
WILL BE STRONG WINDS AND HEAVY DOWNPOURS AS PWATS REACH CLOSE TO 1.5
IN.
THIS WEEKEND...
UPPER LEVEL TROUGH WILL PUSH THROUGH OVER THE WEEK...CAA WILL
BRING A THERMAL TROUGH INTO THE REGION. THIS WILL DROP TEMPS WELL
BELOW SEASONAL AVG. AM NOT ANTICIPATED ANY FROST/FREEZE HEADLINES
AT THIS TIME BUT MAY NEED TO MONITOR IN THE FUTURE AS THE ENTIRE
AREA IS NOW IN THE GROWING SEASON. EXPECT MAINLY DRY WEATHER FOR
THE WEEKEND AND TEMPS IN THE MID TO UPPER 60S.
MONDAY AND BEYOND...SURFACE HIGH PRESSURE WILL BE IN CONTROL FOR
THE FIRST HALF OF NEXT WEEK. THIS WILL HELP TEMPS REACH SEASONAL
CONDITIONS. APPEARS THAT THERE IS LIMITED MOISTURE...HOWEVER
CANNOT RULE OUT A SPOT SHOWER OR TWO...ESP IF SEA BREEZE DEVELOPS.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW...MODERATE CONFIDENCE IN TIMING AND AREAL COVERAGE OF
STRATUS AND FOG BOTH THIS MORNING AND WEDNESDAY MORNING.
PATCHY IFR CONDITIONS PORTIONS OF E COASTAL MA AND CAPE/ISLANDS
MAY BRIEFLY IMPROVE TO VFR FOR A TIME EARLY THIS
AFTERNOON...EXCEPT IFR FOG PERSISTING AT ACK. SHOWERS AND
THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON...ESPECIALLY ACROSS THE
INTERIOR.
TONIGHT...WIDESPREAD IFR/LIFR IN STRATUS AND FOG REDEVELOP.
WEDNESDAY...PRETTY MUCH A REPEAT OF TUESDAY. GRADUAL IMPROVEMENT
TO VFR/MVFR FROM WEST TO EAST.
KBOS TERMINAL...MODERATE CONFIDENCE. CONDITIONS SHOULD
TEMPORARILY IMPROVE TO VFR AROUND MIDDAY BUT FALL BACK TO IFR BY
MID TO LATE AFTERNOON. TIMING UNCERTAIN.
KBDL TERMINAL...MODERATE CONFIDENCE.
OUTLOOK...THURSDAY THROUGH SATURDAY...
THURSDAY INTO FRIDAY...LOW TO MODERATE CONFIDENCE.
MODERATE CONFIDENCE ON SEA BREEZE DEVELOPMENTS. VERY UNSETTLED
PATTERN WITH VARIABILITY BETWEEN VFR CONDITIONS AND MVFR/IFR
CONDITIONS IN SHRA/TSRA/FOG. IMPROVING CONDITIONS LATE FRIDAY
NIGHT INTO SATURDAY MORNING.
SATURDAY...HIGH CONFIDENCE. VFR.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
HIGH CONFIDENCE THROUGH WEDNESDAY.
WINDS AND SEAS EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY
CRITERIA MOST OF TODAY. LEANED MORE HEAVILY UPON THE SWAN WAVE
GUIDANCE AS THE WNA WAVE GUIDANCE APPEARS TO BE TOO HIGH. STILL
EXPECTING AREAS OF FOG TO PERSIST THROUGH TODAY BEFORE EXPANDING
ONCE AGAIN TONIGHT.
INCREASING SOUTHWEST WINDS WEDNESDAY MAY LEAD TO DEVELOPMENT OF
MARGINAL 5 FT SEAS ACROSS THE SOUTHERN OUTER COASTAL WATERS OF MA
AND RI. WILL HOLD OFF ON ISSUING ANOTHER SMALL CRAFT ADVISORY
RIGHT NOW TO AVOID CONFUSION WITH EXISTING ADVISORY.
OUTLOOK...THURSDAY THROUGH SATURDAY...
THURSDAY INTO FRIDAY...HIGH CONFIDENCE. APPROACHING STORM SYSTEM
WILL INCREASE SEAS ABOVE 5FT DURING THIS TIME PERIOD...SCA WILL BE
NEEDED. EXPECT LOW VSBYS IN HEAVY SHOWERS AND SOME THUNDER AS WELL.
BELIEVE FRIDAY IS THE BETTER DAY FOR TSTORMS ACROSS THE WATERS AS
COLD FRONT WILL PUSH THROUGH NEW ENGLAND ON FRIDAY.
THIS WEEKEND...MODERATE CONFIDENCE. SEAS WILL REMAIN ABOVE SCA
FOR MOST OF THE WEEKEND ESP FOR THE OUTER WATERS. GUSTY NW BEHIND
THE FRONT WILL BRING GUSTS CLOSE TO GALE FORCE SAT INTO SAT NIGHT.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR MAZ006-007-
015-016-019>024.
NH...NONE.
RI...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR RIZ006>008.
MARINE...NONE.
&&
$$
SYNOPSIS...BELK/DUNTEN
NEAR TERM...BELK/KJC/DUNTEN
SHORT TERM...BELK
LONG TERM...DUNTEN
AVIATION...BELK/KJC/DUNTEN
MARINE...BELK/DUNTEN
AREA FORECAST DISCUSSION
NWS ALBANY NY
729 AM EDT TUE MAY 21 2013
.SYNOPSIS...
WARM AND HUMID CONDITIONS WILL CONTINUE TODAY WITH A
FRONTAL BOUNDARY BECOMING STATIONARY ACROSS UPSTATE NEW YORK AND NEW
ENGLAND. A DISTURBANCE MOVING ALONG THE FRONTAL BOUNDARY WILL FOCUS
SOME SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON AND EVENING
HOURS. THE HUMID AND UNSETTLED WEATHER CONTINUES TOMORROW AND
THURSDAY WITH MORE CHANCES OF SHOWERS AND THUNDERSTORMS BEFORE A
COLD FRONT RETURNS DRIER AND COOLER WEATHER FOR FRIDAY AND INTO THE
HOLIDAY WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 630 AM EDT...A BROAD RIDGE AT 500 HPA IS SITUATED OVER THE
EASTERN CONUS...WITH A SLOW MOVING UPPER LOW OVER THE CENTRAL
PLAINS. AT THE SURFACE...OUR REGION REMAINS IN A WARM
SECTOR...WITH A VERY SLOW MOVING BOUNDARY SITUATED ACROSS THE
NORTHERN PORTION OF OUR AREA.
A LINE OF CONVECTIVE SHOWERS/THUNDERSTORMS SWEPT THROUGH THE
ADIRONDACKS EARLY THIS MORNING AND IS ALREADY WELL EAST OF THE
REGION ACROSS CENTRAL AND EASTERN NEW ENGLAND. ADDITIONAL SHOWERS
AND THUNDERSTORMS HAVE DEVELOPED ALONG THE STALLED BOUNDARY ACROSS
LAKE ONTARIO. SOME OF THESE SHOWERS/STORMS MAY MAKE IT INTO THE
ADIRONDACKS BY THE MID MORNING HOURS. OTHERWISE...THE REMAINDER OF
THE REGION WILL START THE DRY RAIN FREE...ALTHOUGH IT WILL WARM
AND MUGGY. SOME VALLEY AREAS ARE SEEING PATCHY FOG TO START THE
DAY...BUT THE STRONG MAY SUN SHOULD HELP DISSIPATE THIS FOG BY
ABOUT 8 AM.
ADDITIONAL SHOWERS AND THUNDERSTORMS WILL DEVELOP DURING THE
HEATING OF THE DAY AS A SFC WAVE ALONG THE FRONT BEGINS TO
APPROACH THE AREA. OUR LOCAL HIRES WRF SUGGESTS THAT SOME SHOWERS
OR STORMS MAY BEGIN TO DEVELOP OVER THE HIGH TERRAIN BY THE LATE
MORNING OR EARLY AFTN HOURS. THE 3 KM HRRR GUIDANCE SEEMS TO SHOW
THAT IT COULD HOLD OFF UNTIL THE EARLY TO MID AFTN HOURS. IN
EITHER CASES...ONCE SHOWERS AND THUNDERSTORMS DEVELOP THEY SHOULD
MOVE IN A GENERA-LY WEST TO EAST MANNER.
WITH MAX TEMPS REACHING THE UPPER 70S TO MID 80S ACROSS THE
AREA...AND TDS WELL INTO THE 60S...THERE SHOULD BE SUFFICIENT
INSTABILITY FOR TSTMS. WITH 0-6 KM BULK SHEAR OF 20-35 KTS AND MID
LEVEL LAPSE RATES OF ABOUT 6-7 DEGREES C PER KM...THERE COULD BE
ENOUGH OF THE INGREDIENTS IN PLACE TO ALLOW A STORM OR TWO TO
BECOME STRONG TO POSSIBLY SEVERE. SPC HAS PLACED OUR REGION IN A
/SEE TEXT/ AREA FOR TODAY...AND WE WILL HAVE TO WATCH IF ANY
STORMS GROW TALL ENOUGH TO PRODUCE SOME DAMAGING WIND GUSTS. WE
WILL HIGHLIGHT THIS IN OUR HWO AS WELL.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
ONGOING CONVECTION THIS EVENING LOOKS TO CONTINUE INTO TONIGHT AS
THE SFC WAVE MOVES ALONG THE BOUNDARY. THE BEST CHC FOR SEEING
SHOWERS/TSTMS WILL BE ACROSS THE NORTHERN PORTION OF THE AREA.
WITH THE LOSS OF HEATING...ANY SVR THREAT WILL BE DIMINISHED...BUT
THUNDER SHOULD STILL CONTINUE DUE TO LINGERING ELEVATED
INSTABILITY OVERNIGHT. MIN TEMPS WILL CONTINUE TO BE MILD AND
MUGGY WITH UPPER 50S TO MID 60S ACROSS THE AREA.
THE SFC BOUNDARY WILL LIFT NORTHWARD AS A WARM FRONT ON WEDNESDAY.
THE RIDGE AXIS WILL START TO SHIFT EASTWARD AS THE UPPER LOW OVER
THE PLAINS SLOWLY MOVES EASTWARD. DESPITE THE WEAK LARGE SCALE
FORCING...THERE LOOKS TO BE A CONTINUED THREAT FOR SHOWERS/TSTMS AS
A PRE FRONTAL TROUGH MAY BE IN PLACE ACROSS OUR AREA BY AFTN.
PLENTY OF MOISTURE AND INSTABILITY WILL BE IN PLACE...ESP WITH
WARM TEMPS REACHING THE 80S IN MOST AREAS...AND TDS IN THE MID 60S
F. ANY STORM WILL AGAIN BE CAPABLE OF PRODUCING DAMAGING
WINDS/LARGE HAIL...AND SPC HAS PLACED A GOOD CHUNK OF OUR AREA IN
A SLIGHT RISK FOR SVR STORMS. WILL HIGHLIGHT THIS IN THE HWO AS
WELL.
SHOWERS AND THUNDERSTORMS MAY LINGER AGAIN INTO WEDNESDAY NIGHT
WITH CONTINUED MILD AND MUGGY CONDITIONS. MINS WILL ONLY DROP INTO
THE 60S...WITH MID TO UPPER 60S IN THE HUDSON VALLEY.
THE UPPER TROUGH WILL FINALLY BEGIN TO MAKE SOME STEADY EASTWARD
PROGRESS ON THURSDAY INTO THURSDAY NIGHT. A SFC COLD FRONT WILL
ADVANCE EASTWARD DURING THIS TIME AS WELL. THIS FRONT WILL BE A
FOCUS FOR ADDITIONAL SHOWERS AND THUNDERSTORMS...ESP FOR THURSDAY
AFTN INTO THURSDAY NIGHT. AHEAD OF THIS BOUNDARY...THERE WILL BE
ONE LAST WARM AND MUGGY DAY...WITH MAX TEMPS IN THE 70S. MIN TEMPS
WILL START TO COOL OFF BY THURSDAY NIGHT WILL THE BOUNDARY MOVING
THROUGH...WITH MINS IN THE 40S AND 50S ACROSS THE AREA...WITH THE
MILDEST TEMPS IN SOUTHEASTERN AREAS.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
A COLD FRONT SHOULD EXIT THE REGION THROUGH THE DAY FRIDAY WITH
LINGERING SHOWERS AND THUNDERSTORMS IN THE MORNING IN NY AND INTO
THE AFTERNOON IN WESTERN NEW ENGLAND. THERE SHOULD BE DECENT
BOUNDARY LAYER FORCING WITH A TIGHT THERMAL AND MOISTURE GRADIENT
ALONG THE COLD FRONT...SO WILL KEEP AN EYE FOR ANY STRONG
THUNDERSTORM POTENTIAL. BOUNDARY LAYER TEMPERATURES SHOULD FALL
THROUGH THE DAY...AND HIGH TEMPERATURES SHOULD BE CAPPED AROUND THE
MID 60S TO AROUND 70...BUT IN THE MID TO UPPER 50S IN THE SOUTHERN
ADIRONDACKS.
ONCE THE COLD FRONT IS GONE...HIGH PRESSURE GRADUALLY BUILDS IN
THROUGH THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK. SOME
LINGERING CLOUDINESS COULD AFFECT THE MID HUDSON VALLEY INTO WESTERN
NEW ENGLAND SATURDAY AS THE COLD FRONT COULD BE SLOW TO EXIT THOSE
AREAS. HOWEVER...ANY SHOWER ACTIVITY SHOULD REMAIN EAST OF OUR
AREA. HIGHS SATURDAY IN THE MID TO UPPER 60S...UPPER 50S SOUTHERN
ADIRONDACKS.
FOR SUNDAY AND MONDAY...INCREASING SUNSHINE AND SLOWLY MODERATING
TEMPERATURES. HIGHS SUNDAY IN THE UPPER 60S TO AROUND 70 AND ON
MONDAY...HIGHS AROUND 70 TO THE LOWER 70S. TEMPERATURES COOLER IN
THE SOUTHERN ADIRONDACKS BOTH DAYS.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
SOME TYPICAL EARLY MORNING LOW CLOUDS AND FOG AFFECTING ALL SITES
AND SHOULD LIFT BY 14Z WHEN CONDITIONS SHOULD BECOME VFR...EXCEPT
BY 16Z AT KPSF. THERE IS ANOTHER SMALL CLUSTER OF SHOWERS AND
THUNDERSTORMS OVER LAKE ONTARIO THAT COULD APPROACH KGFL LATE THIS
MORNING OR EARLY THIS AFTERNOON...BUT TOO EARLY AND TOO ISOLATED
TO MENTION IN TAF AT THIS TIME OTHER THAN PUTTING A VCSH.
MORE SHOWERS AND THUNDERSTORMS IN THE OH VALLEY AND CENTRAL GREAT
LAKES THIS MORNING COULD AFFECT OUR REGION LATE THIS AFTERNOON AND
EVENING...IF THEY HOLD TOGETHER TO TRACK THIS FAR EAST. AGAIN...DUE
TO UNCERTAINTIES...JUST PUTTING VCSH AT ALL SITES THIS AFTERNOON AND
EVENING. LATER IN THE EVENING...SOME FOG AND LOW CEILINGS COULD
POTENTIALLY FORM WITH MVFR CONDITIONS.
LIGHT WINDS SHOULD BECOME SOUTH TO SOUTHWEST AT 10 KT OR LESS
TODAY...THEN DIMINISH BACK TO LIGHT THIS EVENING AND TONIGHT.
OUTLOOK...
WED...VFR/MVFR CHC -SHRA/-TSRA ESPECIALLY DURING THE AFTN.
WED NIGHT...VFR/MVFR. AT KGFL AND KALB -SHRA/-TSRA LIKELY. AT
KPSF AND KPOU CHC -SHRA/-TSRA.
THU...MVFR WITH IFR POSSIBLE. -SHRA/-TSRA LIKELY.
THU NIGHT...VFR/MVFR. CHC -SHRA/-TSRA ESPECIALLY IN THE EVNG.
FRI...MAINLY VFR. CHC -TSRA MAINLY IN THE AM.
SAT...VFR. NO SIG WX.
&&
.FIRE WEATHER...
NO FIRE WEATHER CONCERNS THROUGH AT LEAST THURSDAY DUE TO ON AND OFF
SHOWERS AND THUNDERSTORMS ACROSS THE REGION. RH VALUES WILL RECOVER
TO NEAR 100 PERCENT AT NIGHT...AND RH VALUES WILL GENERALLY STAY
ABOVE 50 PERCENT DURING THE DAYTIME HOURS.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO SERVICE AREAS PROBLEMS ARE EXPECTED THE NEXT 5
DAYS. SOME LOCALLY HEAVY DOWNPOURS OF RAINFALL MAY OCCUR TODAY
THROUGH THURSDAY WITHIN ANY THUNDERSTORMS. 3-HR ZONAL FFG VALUES ARE
GENERALLY IN THE 2.4-3.1 INCH RANGE AT THIS TIME...WHICH ARE HIGH
FOR MID TO LATE MAY.
DUE TO THE SCATTERED NATURE OF THE SHOWERS AND THUNDERSTORMS...
BASIN AVERAGE QPF WILL BE HIGHLY VARIABLE THIS WEEK. THE BEST
THREAT FOR SEEING SIGNIFICANT AMOUNTS OF SHOWERS OR THUNDERSTORMS
WILL FROM THIS AFTERNOON INTO THIS EVENING AND AGAIN ON THURSDAY
AFTERNOON INTO THURSDAY NIGHT. WHILE IT/S DIFFICULT TO PINPOINT
EXACT AMOUNTS...GUIDANCE FROM THE WEATHER PREDICTION CENTER /WPC/
SUGGESTS THAT MOST AREAS WILL SEE BETWEEN ONE HALF INCH AND AN INCH
AND A HALF OF RAIN THROUGH SATURDAY EVENING...WITH THE HIGHEST
AMOUNTS ACROSS THE ADIRONDACKS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...FRUGIS
NEAR TERM...FRUGIS
SHORT TERM...FRUGIS
LONG TERM...NAS
AVIATION...NAS
FIRE WEATHER...FRUGIS
HYDROLOGY...FRUGIS/WASULA
AREA FORECAST DISCUSSION
NWS ALBANY NY
630 AM EDT TUE MAY 21 2013
.SYNOPSIS...
WARM AND HUMID CONDITIONS WILL CONTINUE TODAY WITH A
FRONTAL BOUNDARY BECOMING STATIONARY ACROSS UPSTATE NEW YORK AND NEW
ENGLAND. A DISTURBANCE MOVING ALONG THE FRONTAL BOUNDARY WILL FOCUS
SOME SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON AND EVENING
HOURS. THE HUMID AND UNSETTLED WEATHER CONTINUES TOMORROW AND
THURSDAY WITH MORE CHANCES OF SHOWERS AND THUNDERSTORMS BEFORE A
COLD FRONT RETURNS DRIER AND COOLER WEATHER FOR FRIDAY AND INTO THE
HOLIDAY WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 630 AM EDT...A BROAD RIDGE AT 500 HPA IS SITUATED OVER THE
EASTERN CONUS...WITH A SLOW MOVING UPPER LOW OVER THE CENTRAL
PLAINS. AT THE SURFACE...OUR REGION REMAINS IN A WARM
SECTOR...WITH A VERY SLOW MOVING BOUNDARY SITUATED ACROSS THE
NORTHERN PORTION OF OUR AREA.
A LINE OF CONVECTIVE SHOWERS/THUNDERSTORMS SWEPT THROUGH THE
ADIRONDACKS EARLY THIS MORNING AND IS ALREADY WELL EAST OF THE
REGION ACROSS CENTRAL AND EASTERN NEW ENGLAND. ADDITIONAL SHOWERS
AND THUNDERSTORMS HAVE DEVELOPED ALONG THE STALLED BOUNDARY ACROSS
LAKE ONTARIO. SOME OF THESE SHOWERS/STORMS MAY MAKE IT INTO THE
ADIRONDACKS BY THE MID MORNING HOURS. OTHERWISE...THE REMAINDER OF
THE REGION WILL START THE DRY RAIN FREE...ALTHOUGH IT WILL WARM
AND MUGGY. SOME VALLEY AREAS ARE SEEING PATCHY FOG TO START THE
DAY...BUT THE STRONG MAY SUN SHOULD HELP DISSIPATE THIS FOG BY
ABOUT 8 AM.
ADDITIONAL SHOWERS AND THUNDERSTORMS WILL DEVELOP DURING THE
HEATING OF THE DAY AS A SFC WAVE ALONG THE FRONT BEGINS TO
APPROACH THE AREA. OUR LOCAL HIRES WRF SUGGESTS THAT SOME SHOWERS
OR STORMS MAY BEGIN TO DEVELOP OVER THE HIGH TERRAIN BY THE LATE
MORNING OR EARLY AFTN HOURS. THE 3 KM HRRR GUIDANCE SEEMS TO SHOW
THAT IT COULD HOLD OFF UNTIL THE EARLY TO MID AFTN HOURS. IN
EITHER CASES...ONCE SHOWERS AND THUNDERSTORMS DEVELOP THEY SHOULD
MOVE IN A GENERA-LY WEST TO EAST MANNER.
WITH MAX TEMPS REACHING THE UPPER 70S TO MID 80S ACROSS THE
AREA...AND TDS WELL INTO THE 60S...THERE SHOULD BE SUFFICIENT
INSTABILITY FOR TSTMS. WITH 0-6 KM BULK SHEAR OF 20-35 KTS AND MID
LEVEL LAPSE RATES OF ABOUT 6-7 DEGREES C PER KM...THERE COULD BE
ENOUGH OF THE INGREDIENTS IN PLACE TO ALLOW A STORM OR TWO TO
BECOME STRONG TO POSSIBLY SEVERE. SPC HAS PLACED OUR REGION IN A
/SEE TEXT/ AREA FOR TODAY...AND WE WILL HAVE TO WATCH IF ANY
STORMS GROW TALL ENOUGH TO PRODUCE SOME DAMAGING WIND GUSTS. WE
WILL HIGHLIGHT THIS IN OUR HWO AS WELL.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
ONGOING CONVECTION THIS EVENING LOOKS TO CONTINUE INTO TONIGHT AS
THE SFC WAVE MOVES ALONG THE BOUNDARY. THE BEST CHC FOR SEEING
SHOWERS/TSTMS WILL BE ACROSS THE NORTHERN PORTION OF THE AREA.
WITH THE LOSS OF HEATING...ANY SVR THREAT WILL BE DIMINISHED...BUT
THUNDER SHOULD STILL CONTINUE DUE TO LINGERING ELEVATED
INSTABILITY OVERNIGHT. MIN TEMPS WILL CONTINUE TO BE MILD AND
MUGGY WITH UPPER 50S TO MID 60S ACROSS THE AREA.
THE SFC BOUNDARY WILL LIFT NORTHWARD AS A WARM FRONT ON WEDNESDAY.
THE RIDGE AXIS WILL START TO SHIFT EASTWARD AS THE UPPER LOW OVER
THE PLAINS SLOWLY MOVES EASTWARD. DESPITE THE WEAK LARGE SCALE
FORCING...THERE LOOKS TO BE A CONTINUED THREAT FOR SHOWERS/TSTMS AS
A PRE FRONTAL TROUGH MAY BE IN PLACE ACROSS OUR AREA BY AFTN.
PLENTY OF MOISTURE AND INSTABILITY WILL BE IN PLACE...ESP WITH
WARM TEMPS REACHING THE 80S IN MOST AREAS...AND TDS IN THE MID 60S
F. ANY STORM WILL AGAIN BE CAPABLE OF PRODUCING DAMAGING
WINDS/LARGE HAIL...AND SPC HAS PLACED A GOOD CHUNK OF OUR AREA IN
A SLIGHT RISK FOR SVR STORMS. WILL HIGHLIGHT THIS IN THE HWO AS
WELL.
SHOWERS AND THUNDERSTORMS MAY LINGER AGAIN INTO WEDNESDAY NIGHT
WITH CONTINUED MILD AND MUGGY CONDITIONS. MINS WILL ONLY DROP INTO
THE 60S...WITH MID TO UPPER 60S IN THE HUDSON VALLEY.
THE UPPER TROUGH WILL FINALLY BEGIN TO MAKE SOME STEADY EASTWARD
PROGRESS ON THURSDAY INTO THURSDAY NIGHT. A SFC COLD FRONT WILL
ADVANCE EASTWARD DURING THIS TIME AS WELL. THIS FRONT WILL BE A
FOCUS FOR ADDITIONAL SHOWERS AND THUNDERSTORMS...ESP FOR THURSDAY
AFTN INTO THURSDAY NIGHT. AHEAD OF THIS BOUNDARY...THERE WILL BE
ONE LAST WARM AND MUGGY DAY...WITH MAX TEMPS IN THE 70S. MIN TEMPS
WILL START TO COOL OFF BY THURSDAY NIGHT WILL THE BOUNDARY MOVING
THROUGH...WITH MINS IN THE 40S AND 50S ACROSS THE AREA...WITH THE
MILDEST TEMPS IN SOUTHEASTERN AREAS.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
A COLD FRONT SHOULD EXIT THE REGION THROUGH THE DAY FRIDAY WITH
LINGERING SHOWERS AND THUNDERSTORMS IN THE MORNING IN NY AND INTO
THE AFTERNOON IN WESTERN NEW ENGLAND. THERE SHOULD BE DECENT
BOUNDARY LAYER FORCING WITH A TIGHT THERMAL AND MOISTURE GRADIENT
ALONG THE COLD FRONT...SO WILL KEEP AN EYE FOR ANY STRONG
THUNDERSTORM POTENTIAL. BOUNDARY LAYER TEMPERATURES SHOULD FALL
THROUGH THE DAY...AND HIGH TEMPERATURES SHOULD BE CAPPED AROUND THE
MID 60S TO AROUND 70...BUT IN THE MID TO UPPER 50S IN THE SOUTHERN
ADIRONDACKS.
ONCE THE COLD FRONT IS GONE...HIGH PRESSURE GRADUALLY BUILDS IN
THROUGH THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK. SOME
LINGERING CLOUDINESS COULD AFFECT THE MID HUDSON VALLEY INTO WESTERN
NEW ENGLAND SATURDAY AS THE COLD FRONT COULD BE SLOW TO EXIT THOSE
AREAS. HOWEVER...ANY SHOWER ACTIVITY SHOULD REMAIN EAST OF OUR
AREA. HIGHS SATURDAY IN THE MID TO UPPER 60S...UPPER 50S SOUTHERN
ADIRONDACKS.
FOR SUNDAY AND MONDAY...INCREASING SUNSHINE AND SLOWLY MODERATING
TEMPERATURES. HIGHS SUNDAY IN THE UPPER 60S TO AROUND 70 AND ON
MONDAY...HIGHS AROUND 70 TO THE LOWER 70S. TEMPERATURES COOLER IN
THE SOUTHERN ADIRONDACKS BOTH DAYS.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
MOSTLY CLEAR SKY ACROSS THE REGION EARLY THIS MORNING...WITH A WEAK
WARM FRONT ACROSS NORTHERN NY. SOME FOG HAS FORMED AT KPSF AND
ACKNOWLEDGING IFR FOG TEMPORARILY MVFR THROUGH ABOUT 14Z AT KPSF. A
BAND OF SHOWERS AND THUNDERSTORMS OVER LAKE ONTARIO IS MOVING
EAST...AND THE SOUTHERN EDGE OF THE CONVECTION IS NEAR KSYR. THERE
IS A GUST FRONT AHEAD OF THE CONVECTION THAT IS MOVING AT AROUND 35
KT...BUT BASED ON THE STEERING FLOW SEEN ON RADARS ACROSS THE
REGION...THIS CONVECTION SHOULD MAINLY TRACK DUE EAST.
AREA 00Z SOUNDINGS ALSO SHOW ENOUGH INSTABILITY ACROSS THE REGION TO
SUSTAIN THE CONVECTION AS IT TRACKS THROUGH EASTERN NY AND INTO
WESTERN NEW ENGLAND. HOWEVER...IT IS TIMED TO REACH THE HUDSON
VALLEY AROUND 09Z...AND WITH CONTINUED STABILIZING OF THE ATMOSPHERE
THROUGH THE EARLY MORNING HOURS...AND WEAKENING OF THE
CONVECTION...JUST INDICATING VCSH AT KGFL...KALB AND KPSF...ALTHOUGH
THE BEST CHANCE OF A SHOWER OR THUNDERSTORM WOULD BE KGFL BASED ON
RADAR TRENDS. WILL AMEND TAFS AN HOUR OR TWO PRIOR TO A SHOWER OR
THUNDERSTORM IF RADAR SUGGESTS STRENGTH OF CONVECTION AND MOVEMENT
CONTINUES.
OUTSIDE OF THESE SHOWERS AND THUNDERSTORMS...SOME PATCHY MVFR FOG
AND SOME SCATTERED VARIABLE BROKEN CLOUDS AROUND 1500 FEET ARE
POSSIBLE THROUGH ABOUT 14Z. ONCE WHATEVER RAIN TRACKS EAST OF THE
REGION...BROKEN CLOUDS ABOVE 3000 FEET TEMPORARILY SCATTERED THROUGH
THE AFTERNOON. SOME SCATTERED SHOWERS OR THUNDERSTORMS COULD
DEVELOP LATE IN THE AFTERNOON AND INTO THE EVENING...BUT NO REAL
ORGANIZED FOCUS SO LEAVING OUT ANY VCSH FOR NOW...BUT MAY BE ADDED
IN LATER TAF ISSUANCES TODAY ONCE THE CHARACTER OF CONVECTION IS
KNOWN WHEN IT FORMS.
WINDS SHOULD BE NEARLY CAL THROUGH ABOUT 14Z. WINDS SHOULD BECOME
LIGHT SOUTH TO SOUTHWEST AT LESS THAN 10 KT LATER THIS MORNING AND
CONTINUE THIS AFTERNOON AND EVENING.
OUTLOOK...
TUE NIGHT...VFR/MVFR. AT KALB AND KGFL -SHRA LIKELY WITH CHC TSRA.
AT KPSF AND KPOU CHC -SHRA/-TSRA.
WED...VFR/MVFR. CHC -SHRA/-TSRA ESPECIALLY DURING THE AFTN.
WED NIGHT...VFR/MVFR. AT KGFL AND KALB -SHRA/-TSRA LIKELY. AT
KPSF AND KPOU CHC -SHRA/-TSRA.
THU...MVFR WITH IFR POSSIBLE. -SHRA/-TSRA LIKELY.
THU NIGHT...VFR/MVFR. CHC -SHRA/-TSRA ESPECIALLY IN THE EVNG.
FRI...MAINLY VFR. CHC -SHRA MAINLY IN THE AM.
SAT...VFR. NO SIG WX.
&&
.FIRE WEATHER...
NO FIRE WEATHER CONCERNS THROUGH AT LEAST THURSDAY DUE TO ON AND OFF
SHOWERS AND THUNDERSTORMS ACROSS THE REGION. RH VALUES WILL RECOVER
TO NEAR 100 PERCENT AT NIGHT...AND RH VALUES WILL GENERALLY STAY
ABOVE 50 PERCENT DURING THE DAYTIME HOURS.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO SERVICE AREAS PROBLEMS ARE EXPECTED THE NEXT 5
DAYS. SOME LOCALLY HEAVY DOWNPOURS OF RAINFALL MAY OCCUR TODAY
THROUGH THURSDAY WITHIN ANY THUNDERSTORMS. 3-HR ZONAL FFG VALUES ARE
GENERALLY IN THE 2.4-3.1 INCH RANGE AT THIS TIME...WHICH ARE HIGH
FOR MID TO LATE MAY.
DUE TO THE SCATTERED NATURE OF THE SHOWERS AND THUNDERSTORMS...
BASIN AVERAGE QPF WILL BE HIGHLY VARIABLE THIS WEEK. THE BEST
THREAT FOR SEEING SIGNIFICANT AMOUNTS OF SHOWERS OR THUNDERSTORMS
WILL FROM THIS AFTERNOON INTO THIS EVENING AND AGAIN ON THURSDAY
AFTERNOON INTO THURSDAY NIGHT. WHILE IT/S DIFFICULT TO PINPOINT
EXACT AMOUNTS...GUIDANCE FROM THE WEATHER PREDICTION CENTER /WPC/
SUGGESTS THAT MOST AREAS WILL SEE BETWEEN ONE HALF INCH AND AN INCH
AND A HALF OF RAIN THROUGH SATURDAY EVENING...WITH THE HIGHEST
AMOUNTS ACROSS THE ADIRONDACKS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...FRUGIS
NEAR TERM...FRUGIS
SHORT TERM...FRUGIS
LONG TERM...NAS
AVIATION...NAS
FIRE WEATHER...FRUGIS
HYDROLOGY...FRUGIS/WASULA
AREA FORECAST DISCUSSION
NWS ALBANY NY
425 AM EDT TUE MAY 21 2013
.SYNOPSIS...
WARM AND HUMID CONDITIONS WILL CONTINUE TODAY WITH A
FRONTAL BOUNDARY BECOMING STATIONARY ACROSS UPSTATE NEW YORK AND NEW
ENGLAND. A DISTURBANCE MOVING ALONG THE FRONTAL BOUNDARY WILL FOCUS
SOME SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON AND EVENING
HOURS. THE HUMID AND UNSETTLED WEATHER CONTINUES TOMORROW AND
THURSDAY WITH MORE CHANCES OF SHOWERS AND THUNDERSTORMS BEFORE A
COLD FRONT RETURNS DRIER AND COOLER WEATHER FOR FRIDAY AND INTO THE
HOLIDAY WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 424 AM EDT...A BROAD RIDGE AT 500 HPA IS SITUATED OVER THE
EASTERN CONUS...WITH A SLOW MOVING UPPER LOW OVER THE CENTRAL
PLAINS. AT THE SURFACE...OUR REGION REMAINS IN A WARM
SECTOR...WITH A VERY SLOW MOVING BOUNDARY SITUATED ACROSS THE
NORTHERN PORTION OF OUR AREA.
MOVING ALONG THIS SFC BOUNDARY AND AIDED BY A STRONG SW LOW LEVEL
JET...A BROKEN LINE OF CONVECTION CONTINUES TO MOVE ACROSS THE
ADIRONDACKS AND MOHAWK VALLEY. THIS LINE HAS WEAKENED FROM EARLIER
IN THE OVERNIGHT HOURS WHEN IT PRODUCED WIND DAMAGE AND HAIL
ACROSS CNY AND THE LAKE ONTARIO REGION. STILL...A QUICK DOWNPOUR
AND SOME GUSTY WINDS WILL SWEEP FROM WEST TO EAST FROM THE
SOUTHEASTERN ADKS AND CENTRAL MOHAWK VALLEY INTO THE LAKE GEORGE
SARATOGA REGION FOR THE NEXT FEW HOURS THROUGH SUNRISE. MOST AREAS
FROM THE CAPITAL REGION ON SOUTH WILL STAY DRY. BY SHORTLY AFTER
SUNRISE...THIS BATCH OF CONVECTION SHOULD BE DONE AND MOST AREAS
ACROSS THE CWA WILL BE DRY.
HOWEVER...ADDITIONAL SHOWERS AND THUNDERSTORMS WILL DEVELOP DURING
THE HEATING OF THE DAY AS A SFC WAVE ALONG THE FRONT BEGINS TO
APPROACH THE AREA. OUR LOCAL HIRES WRF SUGGESTS THAT SOME SHOWERS OR
STORMS MAY BEGIN TO DEVELOP OVER THE HIGH TERRAIN BY THE LATE
MORNING OR EARLY AFTN HOURS. THE 3 KM HRRR GUIDANCE SEEMS TO SHOW
THAT IT COULD HOLD OFF UNTIL THE EARLY TO MID AFTN HOURS. IN
EITHER CASES...ONCE SHOWERS AND THUNDERSTORMS DEVELOP THEY SHOULD
MOVE TO THE W-SW.
WITH MAX TEMPS REACHING THE UPPER 70S TO MID 80S ACROSS THE
AREA...AND TDS WELL INTO THE 60S...THERE SHOULD BE SUFFICIENT
INSTABILITY FOR TSTMS. WITH 0-6 KM BULK SHEAR OF 20-35 KTS AND MID
LEVEL LAPSE RATES OF ABOUT 6-7 DEGREES C PER KM...THERE COULD BE
ENOUGH OF THE INGREDIENTS IN PLACE TO ALLOW A STORM OR TWO TO
BECOME STRONG TO POSSIBLY SEVERE. SPC HAS PLACED OUR REGION IN A
/SEE TEXT/ AREA FOR TODAY...AND WE WILL HAVE TO WATCH IF ANY
STORMS GROW TALL ENOUGH TO PRODUCE SOME DAMAGING WIND GUSTS. WE
WILL HIGHLIGHT THIS IN OUR HWO AS WELL.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
ONGOING CONVECTION THIS EVENING LOOKS TO CONTINUE INTO TONIGHT AS
THE SFC WAVE MOVES ALONG THE BOUNDARY. THE BEST CHC FOR SEEING
SHOWERS/TSTMS WILL BE ACROSS THE NORTHERN PORTION OF THE AREA.
WITH THE LOSS OF HEATING...ANY SVR THREAT WILL BE DIMINISHED...BUT
THUNDER SHOULD STILL CONTINUE DUE TO LINGERING ELEVATED
INSTABILITY OVERNIGHT. MIN TEMPS WILL CONTINUE TO BE MILD AND
MUGGY WITH UPPER 50S TO MID 60S ACROSS THE AREA.
THE SFC BOUNDARY WILL LIFT NORTHWARD AS A WARM FRONT ON WEDNESDAY.
THE RIDGE AXIS WILL START TO SHIFT EASTWARD AS THE UPPER LOW OVER
THE PLAINS SLOWLY MOVES EASTWARD. DESPITE THE WEAK LARGE SCALE
FORCING...THERE LOOKS TO BE A CONTINUED THREAT FOR SHOWERS/TSTMS AS
A PRE FRONTAL TROUGH MAY BE IN PLACE ACROSS OUR AREA BY AFTN.
PLENTY OF MOISTURE AND INSTABILITY WILL BE IN PLACE...ESP WITH
WARM TEMPS REACHING THE 80S IN MOST AREAS...AND TDS IN THE MID 60S
F. ANY STORM WILL AGAIN BE CAPABLE OF PRODUCING DAMAGING
WINDS/LARGE HAIL...AND SPC HAS PLACED A GOOD CHUNK OF OUR AREA IN
A SLIGHT RISK FOR SVR STORMS. WILL HIGHLIGHT THIS IN THE HWO AS
WELL.
SHOWERS AND THUNDERSTORMS MAY LINGER AGAIN INTO WEDNESDAY NIGHT
WITH CONTINUED MILD AND MUGGY CONDITIONS. MINS WILL ONLY DROP INTO
THE 60S...WITH MID TO UPPER 60S IN THE HUDSON VALLEY.
THE UPPER TROUGH WILL FINALLY BEGIN TO MAKE SOME STEADY EASTWARD
PROGRESS ON THURSDAY INTO THURSDAY NIGHT. A SFC COLD FRONT WILL
ADVANCE EASTWARD DURING THIS TIME AS WELL. THIS FRONT WILL BE A
FOCUS FOR ADDITIONAL SHOWERS AND THUNDERSTORMS...ESP FOR THURSDAY
AFTN INTO THURSDAY NIGHT. AHEAD OF THIS BOUNDARY...THERE WILL BE
ONE LAST WARM AND MUGGY DAY...WITH MAX TEMPS IN THE 70S. MIN TEMPS
WILL START TO COOL OFF BY THURSDAY NIGHT WILL THE BOUNDARY MOVING
THROUGH...WITH MINS IN THE 40S AND 50S ACROSS THE AREA...WITH THE
MILDEST TEMPS IN SOUTHEASTERN AREAS.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
A COLD FRONT SHOULD EXIT THE REGION THROUGH THE DAY FRIDAY WITH
LINGERING SHOWERS AND THUNDERSTORMS IN THE MORNING IN NY AND INTO
THE AFTERNOON IN WESTERN NEW ENGLAND. THERE SHOULD BE DECENT
BOUNDARY LAYER FORCING WITH A TIGHT THERMAL AND MOISTURE GRADIENT
ALONG THE COLD FRONT...SO WILL KEEP AN EYE FOR ANY STRONG
THUNDERSTORM POTENTIAL. BOUNDARY LAYER TEMPERATURES SHOULD FALL
THROUGH THE DAY...AND HIGH TEMPERATURES SHOULD BE CAPPED AROUND THE
MID 60S TO AROUND 70...BUT IN THE MID TO UPPER 50S IN THE SOUTHERN
ADIRONDACKS.
ONCE THE COLD FRONT IS GONE...HIGH PRESSURE GRADUALLY BUILDS IN
THROUGH THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK. SOME
LINGERING CLOUDINESS COULD AFFECT THE MID HUDSON VALLEY INTO WESTERN
NEW ENGLAND SATURDAY AS THE COLD FRONT COULD BE SLOW TO EXIT THOSE
AREAS. HOWEVER...ANY SHOWER ACTIVITY SHOULD REMAIN EAST OF OUR
AREA. HIGHS SATURDAY IN THE MID TO UPPER 60S...UPPER 50S SOUTHERN
ADIRONDACKS.
FOR SUNDAY AND MONDAY...INCREASING SUNSHINE AND SLOWLY MODERATING
TEMPERATURES. HIGHS SUNDAY IN THE UPPER 60S TO AROUND 70 AND ON
MONDAY...HIGHS AROUND 70 TO THE LOWER 70S. TEMPERATURES COOLER IN
THE SOUTHERN ADIRONDACKS BOTH DAYS.
&&
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
MOSTLY CLEAR SKY ACROSS THE REGION EARLY THIS MORNING...WITH A WEAK
WARM FRONT ACROSS NORTHERN NY. SOME FOG HAS FORMED AT KPSF AND
ACKNOWLEDGING IFR FOG TEMPORARILY MVFR THROUGH ABOUT 14Z AT KPSF. A
BAND OF SHOWERS AND THUNDERSTORMS OVER LAKE ONTARIO IS MOVING
EAST...AND THE SOUTHERN EDGE OF THE CONVECTION IS NEAR KSYR. THERE
IS A GUST FRONT AHEAD OF THE CONVECTION THAT IS MOVING AT AROUND 35
KT...BUT BASED ON THE STEERING FLOW SEEN ON RADARS ACROSS THE
REGION...THIS CONVECTION SHOULD MAINLY TRACK DUE EAST.
AREA 00Z SOUNDINGS ALSO SHOW ENOUGH INSTABILITY ACROSS THE REGION TO
SUSTAIN THE CONVECTION AS IT TRACKS THROUGH EASTERN NY AND INTO
WESTERN NEW ENGLAND. HOWEVER...IT IS TIMED TO REACH THE HUDSON
VALLEY AROUND 09Z...AND WITH CONTINUED STABILIZING OF THE ATMOSPHERE
THROUGH THE EARLY MORNING HOURS...AND WEAKENING OF THE
CONVECTION...JUST INDICATING VCSH AT KGFL...KALB AND KPSF...ALTHOUGH
THE BEST CHANCE OF A SHOWER OR THUNDERSTORM WOULD BE KGFL BASED ON
RADAR TRENDS. WILL AMEND TAFS AN HOUR OR TWO PRIOR TO A SHOWER OR
THUNDERSTORM IF RADAR SUGGESTS STRENGTH OF CONVECTION AND MOVEMENT
CONTINUES.
OUTSIDE OF THESE SHOWERS AND THUNDERSTORMS...SOME PATCHY MVFR FOG
AND SOME SCATTERED VARIABLE BROKEN CLOUDS AROUND 1500 FEET ARE
POSSIBLE THROUGH ABOUT 14Z. ONCE WHATEVER RAIN TRACKS EAST OF THE
REGION...BROKEN CLOUDS ABOVE 3000 FEET TEMPORARILY SCATTERED THROUGH
THE AFTERNOON. SOME SCATTERED SHOWERS OR THUNDERSTORMS COULD
DEVELOP LATE IN THE AFTERNOON AND INTO THE EVENING...BUT NO REAL
ORGANIZED FOCUS SO LEAVING OUT ANY VCSH FOR NOW...BUT MAY BE ADDED
IN LATER TAF ISSUANCES TODAY ONCE THE CHARACTER OF CONVECTION IS
KNOWN WHEN IT FORMS.
WINDS SHOULD BE NEARLY CAL THROUGH ABOUT 14Z. WINDS SHOULD BECOME
LIGHT SOUTH TO SOUTHWEST AT LESS THAN 10 KT LATER THIS MORNING AND
CONTINUE THIS AFTERNOON AND EVENING.
OUTLOOK...
TUE NIGHT...VFR/MVFR. AT KALB AND KGFL -SHRA LIKELY WITH CHC TSRA.
AT KPSF AND KPOU CHC -SHRA/-TSRA.
WED...VFR/MVFR. CHC -SHRA/-TSRA ESPECIALLY DURING THE AFTN.
WED NIGHT...VFR/MVFR. AT KGFL AND KALB -SHRA/-TSRA LIKELY. AT
KPSF AND KPOU CHC -SHRA/-TSRA.
THU...MVFR WITH IFR POSSIBLE. -SHRA/-TSRA LIKELY.
THU NIGHT...VFR/MVFR. CHC -SHRA/-TSRA ESPECIALLY IN THE EVNG.
FRI...MAINLY VFR. CHC -SHRA MAINLY IN THE AM.
SAT...VFR. NO SIG WX.
&&
.FIRE WEATHER...
NO FIRE WEATHER CONCERNS THROUGH AT LEAST THURSDAY DUE TO ON AND OFF
SHOWERS AND THUNDERSTORMS ACROSS THE REGION. RH VALUES WILL RECOVER
TO NEAR 100 PERCENT AT NIGHT...AND RH VALUES WILL GENERALLY STAY
ABOVE 50 PERCENT DURING THE DAYTIME HOURS.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO SERVICE AREAS PROBLEMS ARE EXPECTED THE NEXT 5
DAYS. SOME LOCALLY HEAVY DOWNPOURS OF RAINFALL MAY OCCUR TODAY
THROUGH THURSDAY WITHIN ANY THUNDERSTORMS. 3-HR ZONAL FFG VALUES ARE
GENERALLY IN THE 2.4-3.1 INCH RANGE AT THIS TIME...WHICH ARE HIGH
FOR MID TO LATE MAY.
DUE TO THE SCATTERED NATURE OF THE SHOWERS AND THUNDERSTORMS...
BASIN AVERAGE QPF WILL BE HIGHLY VARIABLE THIS WEEK. THE BEST
THREAT FOR SEEING SIGNIFICANT AMOUNTS OF SHOWERS OR THUNDERSTORMS
WILL FROM THIS AFTERNOON INTO THIS EVENING AND AGAIN ON THURSDAY
AFTERNOON INTO THURSDAY NIGHT. WHILE IT/S DIFFICULT TO PINPOINT
EXACT AMOUNTS...GUIDANCE FROM THE WEATHER PREDICTION CENTER /WPC/
SUGGESTS THAT MOST AREAS WILL SEE BETWEEN ONE HALF INCH AND AN INCH
AND A HALF OF RAIN THROUGH SATURDAY EVENING...WITH THE HIGHEST
AMOUNTS ACROSS THE ADIRONDACKS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...FRUGIS
NEAR TERM...FRUGIS
SHORT TERM...FRUGIS
LONG TERM...NAS
AVIATION...NAS
FIRE WEATHER...FRUGIS
HYDROLOGY...FRUGIS/WASULA
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
745 AM EDT TUE MAY 21 2013
.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL PREVAIL THROUGH THURSDAY. A COLD FRONT
WILL DROP THROUGH THE AREA ON FRIDAY WITH DRY HIGH PRESSURE BUILDING
IN NEXT WEEKEND INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
NEAR DAWN...ANOTHER MILD MORNING ACROSS THE REGION AS A MOIST
ATMOSPHERE PERSISTS OVER THE FORECAST AREA. WATER VAPOR SATELLITE
IMAGERY INDICATES A WEAK MID LOW LEVEL LOW PRESSURE NOT FAR FROM
JACKSONVILLE FLORIDA...EMBEDDED IN A 500 MB TROUGH AXIS THAT RUNS
N THROUGH CHARLESTON TO GREENSBORO NC. AREAS OF LAYERED CLOUDS
EARLY THIS MORNING WITH POCKETS OF STRATUS AND FOG OVER INLAND
AREAS. WEAK UPPER DIFLUENCE AND MOIST COASTAL CONVERGENCE NOTED
ON LATEST MESOANALYSIS OVER EASTERN SOUTH CAROLINA AND AN AREA OF
HEAVY RAINFALL WAS EASING INTO NE CHARLESTON COUNTY AND WEAKENING
AFTER DUMPING PLENTY OF RAIN OVER SOUTHERN BERKELEY COUNTY. RADAR
ESTIMATED RAINFALL OVER 4 INCHES OF RAIN SE OF CYPRESS GARDENS.
TODAY...THE UPPER TROUGH DOES NOT MOVE MUCH AND EMBEDDED FEATURES
TEND TO WEAKEN WITH TIME. THE DEEPEST MOISTURE CONTINUES TO RESIDE
OVER SE SOUTH CAROLINA ALONG AND E OF INTERSTATE 95 INCLUDING THE
CHARLESTON AND CENTRAL SOUTH CAROLINA COASTAL AREAS. THROUGH MIDDAY
CONVECTIVE RAINS WILL BEGIN TO DEVELOP AS THE LAND MASS QUICKLY
WARMS WITH THE STEEP SUN ANGLE THIS TIME OF YEAR. THERE COULD BE A
FEW HEAVY DOWNPOURS ALONG THE COAST N OF BEAUFORT IF RECENT TRENDS
FROM THE RAP MODEL PAN OUT. CONVECTIVE TEMPS ARE PRETTY LOW TODAY
AND WE THINK SCATTERED CONVECTIVE RAINS WILL DEVELOP SOUTH ALONG
THE GEORGIA SEA BREEZE AND PROPAGATE W AND SW THIS AFTERNOON. 00Z
MODELS PROGS DIFFER ON THE AMOUNT OF INSTABILITY THIS AFTERNOON
BUT THE OPERATIONAL 13K RUC SHOWS DECENT POTENTIAL FOR SHORT-LIVED
BUT STRONG UPDRAFT POTENTIAL. OUR THINKING FOR SIGNIFICANT WEATHER
TODAY IS SIMILAR TO YESTERDAY/S REASONING...LOCALIZED DOWNPOURS
MORE LIKELY AND ONLY AN ISOLATED SEVERE WEATHER POTENTIAL AS BEST
MID LEVEL INSTABILITY AND LOW AND MID LEVEL LAPSE RATES LINGER W
OF THE AREA.
A COUPLE OF CHANGES WE MADE TO OUR FORECAST TODAY. WE RAISED POPS
TO 40-50 PERCENT IN THE CHARLESTON QUAD-COUNTY REGION AND RAISING
HIGH TEMPS OVER INLAND SE GEORGIA ZONES FURTHER INTO THE UPPER
80S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
INLAND CONVECTIVE RAINS WILL BE ENDING EARLY IN THE EVENING AS
THE SEA BREEZE GETS WELL INLAND AND CONVERGENCE DIMINISHES. NO
CHANGES TO THE FORECAST TONIGHT WITH CLOUDS GRADUALLY THINNING
AND LOWS 65-70 DEGREES. WE MAY NEED TO EVENTUALLY ADD SOME PATCHY
FOG IN AGAIN TONIGHT...DEPENDENT ON TRENDS WITH CLOUD DISSIPATION.
A FAIRLY SIMILAR PATTERN WILL PERSIST WEDNESDAY INTO THURSDAY WITH
BROAD UPPER TROUGHING AND ATLANTIC HIGH PRESSURE. SOUTHERLY
LOW-LEVEL FLOW WILL MAINTAIN A FAIRLY MOIST ATMOSPHERE AND HELP PUSH
A SEABREEZE INLAND EACH DAY. THE UPPER TROUGHING WILL CREATE A
SOMEWHAT MORE FAVORABLE ENVIRONMENT FOR CONVECTION TO DEVELOP...
PRIMARILY DRIVEN BY THE SEABREEZE AND BOUNDARY INTERACTIONS. WE KEPT
POPS IN THE 20-30 PERCENT RANGE BOTH DAYS.
THE MODELS ARE NOW QUITE A BIT FASTER AND IN BETTER AGREEMENT
REGARDING A COLD FRONT PUSHING THROUGH FRIDAY MORNING. WE REMOVED
POPS ON FRIDAY AND SHOW DEWPOINTS DROPPING INTO THE UPPER 50S TO
AROUND 60 DURING THE AFTERNOON.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
THERE IS GOOD MODEL AGREEMENT THAT DRY CANADIAN HIGH PRESSURE WILL
EXPAND SOUTHEAST INTO THE FORECAST AREA OVER THE WEEKEND THEN SHIFT
OFFSHORE. DEWPOINTS LOOK TO DROP INTO THE LOWER 50S SATURDAY AND
SUNDAY...WHICH COMBINED WITH HIGHS IN THE LOWER 80S WILL RESULT IN
PLEASANT SPRING WEATHER. OVERNIGHT LOWS WILL PROBABLY DROP INTO THE
UPPER 50S IN SPOTS. LOW-LEVEL MOISTURE INCREASES EARLY NEXT WEEK AS
THE SURFACE HIGH SHIFTS OFFSHORE...BUT WE DID NOT SEE ANY STRONG
SYNOPTIC SCALE FEATURES TO WARRANT ADDING PRECIP.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
KCHS...THE MORNING IS LOOKING WETTER AND WETTER WITH EACH PASSING
HOUR THIS MORNING. PATCHY MVFR/IFR CIGS WILL LINGER THROUGH MID MORNING
OR UNTIL RAINS DIMINISH. ADDITIONAL RAINS ARE LIKELY WITH THE SEA
BREEZE THIS AFTERNOON BUT SHOULD EVENTUALLY DEVELOP W OF THE
TERMINAL BY LATER IN THE DAY. TONIGHT...MAINLY VFR BUT WILL WATCH
FOR LATE NIGHT LOW CLOUDS AND PATCHY FOG WITH WET SOILS AND LIGHT
WINDS.
KSAV...A FEW SHOWERS MAY DEVELOP WITH THE INITIATION OF THE SEA
BREEZE LATE MORNING OR EARLY AFTERNOON ALONG WITH BRIEF MORNING
MVFR CIGS POSSIBLE. BEST CHANCES FOR SHOWERS/TSTMS WILL BE WITH
AFTERNOON CONVECTION WHICH COULD BE MOVING SW ALONG OR JUST W OF
INTERSTATE 95. MAINLY VFR TONIGHT BUT THERE ARE CHANCES OF LATE
NIGHT MVFR/IFR CIGS AND POSSIBLY LIGHT FOG...ESPECIALLY IF SKIES
CLEAR.
EXTENDED AVIATION...SPORADIC REDUCTIONS IN CEILINGS/VSBYS MAINLY IN
AFTERNOON/EVENING SHOWERS OR STORMS THROUGH THURSDAY.
&&
.MARINE...
THROUGH TONIGHT...THE STEADY STATE SYNOPTIC PATTERN CONTINUES UNABATED.
OFFSHORE RIDGE OF HIGH PRESSURE EXTENDS W ACROSS THE COASTAL WATERS...
GENERATING SE AND S WINDS LESS THAN 15 KT AND SEAS IN THE 2-4 FOOT
RANGE...HIGHEST OVER OUTER GEORGIA WATERS BEYOND 20 NM.
HIGH PRESSURE WILL SIT OVER THE WESTERN ATLANTIC UNTIL FRIDAY WHEN A
CANADIAN HIGH DROPS SOUTHEAST. WE MAY SEE A BRIEF PERIOD OF SMALL
CRAFT ADVISORY CONDITIONS FRIDAY NIGHT INTO SATURDAY AS THE GRADIENT
TIGHTENS AND COLD ADVECTION MIXES SOME DECENT WINDS TO THE SURFACE.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...
MARINE...JRL
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
402 AM EDT TUE MAY 21 2013
.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL PREVAIL THROUGH THURSDAY. A COLD FRONT
WILL DROP THROUGH THE AREA ON FRIDAY WITH DRY HIGH PRESSURE BUILDING
IN NEXT WEEKEND INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
PRE-DAWN...ANOTHER MILD MORNING ACROSS THE REGION AS A MOIST
ATMOSPHERE PERSISTS OVER THE FORECAST AREA. WATER VAPOR SATELLITE
IMAGERY INDICATES A WEAK MID LOW LEVEL LOW PRESSURE NOT FAR FROM
JACKSONVILLE FLORIDA...EMBEDDED IN A 500 MB TROUGH AXIS THAT RUNS
N THROUGH CHARLESTON TO GREENSBORO NC. AREAS OF LAYERED CLOUDS
EARLY THIS MORNING WITH POCKETS OF STRATUS EXPECTED TO DEVELOP
OVER INLAND AREAS. WE MAINTAINED PATCHY FOG MENTIONS IN OUR
FORECAST WHERE SKIES CLEARED OVERNIGHT. WEAK UPPER DIFLUENCE AND
MOIST COASTAL CONVERGENCE NOTED ON LATEST MESOANALYSIS OVER EASTERN
SOUTH CAROLINA AND WE MAINTAINED 20/30 POPS ACROSS THE CHARLESTON
TRI-COUNTY AREA AS DAYBREAK NEARS...ELSEWHERE MAINLY DRY EARLY ON.
TODAY...THE UPPER TROUGH DOES NOT MOVE MUCH AND EMBEDDED FEATURES
TEND TO WEAKEN WITH TIME. THE DEEPEST MOISTURE CONTINUES TO RESIDE
OVER SE SOUTH CAROLINA ALONG AND E OF INTERSTATE 95 INCLUDING THE
CHARLESTON AND CENTRAL SOUTH CAROLINA COASTAL AREAS. THROUGH MIDDAY
CONVECTIVE RAINS WILL BEGIN TO DEVELOP AS THE LAND MASS QUICKLY
WARMS WITH THE STEEP SUN ANGLE THIS TIME OF YEAR. THERE COULD BE A
FEW HEAVY DOWNPOURS ALONG THE COAST N OF BEAUFORT IF RECENT TRENDS
FROM THE RAP MODEL PAN OUT. CONVECTIVE TEMPS ARE PRETTY LOW TODAY
AND WE THINK SCATTERED CONVECTIVE RAINS WILL DEVELOP SOUTH ALONG
THE GEORGIA SEA BREEZE AND PROPAGATE W AND SW THIS AFTERNOON. 00Z
MODELS PROGS DIFFER ON THE AMOUNT OF INSTABILITY THIS AFTERNOON
BUT THE OPERATIONAL 13K RUC SHOWS DECENT POTENTIAL FOR SHORT-LIVED
BUT STRONG UPDRAFT POTENTIAL. OUR THINKING FOR SIGNIFICANT WEATHER
TODAY IS SIMILAR TO YESTERDAY/S REASONING...LOCALIZED DOWNPOURS
MORE LIKELY AND ONLY AN ISOLATED SEVERE WEATHER POTENTIAL AS BEST
MID LEVEL INSTABILITY AND LOW AND MID LEVEL LAPSE RATES LINGER W
OF THE AREA.
A COUPLE OF CHANGES WE MADE TO OUR FORECAST TODAY. WE RAISED POPS
TO 40-50 PERCENT IN THE CHARLESTON QUAD-COUNTY REGION AND RAISING
HIGH TEMPS OVER INLAND SE GEORGIA ZONES FURTHER INTO THE UPPER
80S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
INLAND CONVECTIVE RAINS WILL BE ENDING EARLY IN THE EVENING AS
THE SEA BREEZE GETS WELL INLAND AND CONVERGENCE DIMINISHES. NO
CHANGES TO THE FORECAST TONIGHT WITH CLOUDS GRADUALLY THINNING
AND LOWS 65-70 DEGREES. WE MAY NEED TO EVENTUALLY ADD SOME PATCHY
FOG IN AGAIN TONIGHT...DEPENDENT ON TRENDS WITH CLOUD DISSIPATION.
A FAIRLY SIMILAR PATTERN WILL PERSIST WEDNESDAY INTO THURSDAY WITH
BROAD UPPER TROUGHING AND ATLANTIC HIGH PRESSURE. SOUTHERLY
LOW-LEVEL FLOW WILL MAINTAIN A FAIRLY MOIST ATMOSPHERE AND HELP PUSH
A SEABREEZE INLAND EACH DAY. THE UPPER TROUGHING WILL CREATE A
SOMEWHAT MORE FAVORABLE ENVIRONMENT FOR CONVECTION TO DEVELOP...
PRIMARILY DRIVEN BY THE SEABREEZE AND BOUNDARY INTERACTIONS. WE KEPT
POPS IN THE 20-30 PERCENT RANGE BOTH DAYS.
THE MODELS ARE NOW QUITE A BIT FASTER AND IN BETTER AGREEMENT
REGARDING A COLD FRONT PUSHING THROUGH FRIDAY MORNING. WE REMOVED
POPS ON FRIDAY AND SHOW DEWPOINTS DROPPING INTO THE UPPER 50S TO
AROUND 60 DURING THE AFTERNOON.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
THERE IS GOOD MODEL AGREEMENT THAT DRY CANADIAN HIGH PRESSURE WILL
EXPAND SOUTHEAST INTO THE FORECAST AREA OVER THE WEEKEND THEN SHIFT
OFFSHORE. DEWPOINTS LOOK TO DROP INTO THE LOWER 50S SATURDAY AND
SUNDAY...WHICH COMBINED WITH HIGHS IN THE LOWER 80S WILL RESULT IN
PLEASANT SPRING WEATHER. OVERNIGHT LOWS WILL PROBABLY DROP INTO THE
UPPER 50S IN SPOTS. LOW-LEVEL MOISTURE INCREASES EARLY NEXT WEEK AS
THE SURFACE HIGH SHIFTS OFFSHORE...BUT WE DID NOT SEE ANY STRONG
SYNOPTIC SCALE FEATURES TO WARRANT ADDING PRECIP.
&&
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
KCHS...ISOLATED SHOWERS AND BRIEF MVFR CIGS POSSIBLE OVERNIGHT...
OTHERWISE VFR UNTIL DAYBREAK. A RICH TROPICAL-LIKE FEED OF
MOISTURE AND COASTAL CONVERGENCE WILL INTERACT WITH THE SEA BREEZE
DURING THE LATE MORNING AND AFTERNOON HOURS TODAY...PRODUCING
SCATTERED SHRA AND POSSIBLE TSRA. FOR NOW WE MAINTAINED A PROB30
GROUP FOR SHRA AND MVFR CONDITIONS FROM 15-21Z UNTIL TRENDS CAN BE
BETTER DEFINED.
KSAV...WE ANTICIPATE A FEW HOURS OF MVFR CONDITIONS IN LIGHT
LOW STRATUS/STRATOCUMULUS OVERNIGHT AND CONTINUE TO INDICATE THAT
TREND. ISOLATED TO SCATTERED CONVECTION WILL FORM ALONG THE SEA
BREEZE BOUNDARY DURING LATE MORNING THROUGH MID AFTERNOON...THUS
A PROB30 GROUP FROM 16-21Z WAS MAINTAINED.
EXTENDED AVIATION...SPORADIC REDUCTIONS IN CEILINGS/VSBYS MAINLY IN
AFTERNOON/EVENING SHOWERS OR STORMS THROUGH THURSDAY.
&&
.MARINE...
THROUGH TONIGHT...THE STEADY STATE SYNOPTIC PATTERN CONTINUES UNABATED.
OFFSHORE RIDGE OF HIGH PRESSURE EXTENDS W ACROSS THE COASTAL WATERS...
GENERATING SE AND S WINDS LESS THAN 15 KT AND SEAS IN THE 2-4 FOOT
RANGE...HIGHEST OVER OUTER GEORGIA WATERS BEYOND 20 NM.
HIGH PRESSURE WILL SIT OVER THE WESTERN ATLANTIC UNTIL FRIDAY WHEN A
CANADIAN HIGH DROPS SOUTHEAST. WE MAY SEE A BRIEF PERIOD OF SMALL
CRAFT ADVISORY CONDITIONS FRIDAY NIGHT INTO SATURDAY AS THE GRADIENT
TIGHTENS AND COLD ADVECTION MIXES SOME DECENT WINDS TO THE SURFACE.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...
MARINE...JRL
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
229 AM EDT TUE MAY 21 2013
.AVIATION...(FOR THE 06Z TAFS THROUGH 00Z TUESDAY EVENING) ISSUED
AT 225 AM EDT TUE MAY 21 2013
MADE SOME ADJUSTMENTS TO TAFS TO ACCOMMODATE ACCELERATING LINE OF
STORMS MOVING OUT OF NE IL INTO NW INDIANA. SPC MESO ANALYSIS
SHOWS 3 HOUR SFC BASED CAPES CHANGES 200 TO 800 J/KG LOWER...SO
EXPECT STORMS TO GRADUALLY WEAKEN THE REST OF THE NIGHT. ALSO...
SOME SUPPORT FROM THE RIGHT ENTRANCE REGION OF AN UPPER LEVEL JET
WILL WANE AS THE JET AXIS TRANSLATES BACK TO THE WEST GIVEN THE
RESPONSE TO AN UPSTREAM TROF MOVING INTO THE CENTRAL PLAINS. SO
KEPT THUNDER OUT AFTER 12Z. A FAIRLY TIGHT PRESSURE GRADIENT WILL
PERSIST TODAY...WITH DAYTIME MIXING OF HIGHER MOMENTUM AIR CAUSING
SOUTHWEST GUSTS TO AROUND 25 KNOTS.
&&
.SYNOPSIS...
ISSUED AT 532 PM EDT MON MAY 20 2013
SHOWER AND THUNDERSTORM CHANCES WILL CONTINUE TO INCREASE TONIGHT
THROUGH WEDNESDAY...WITH A FEW SHOWERS POSSIBLY LINGERING INTO
THURSDAY. THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS THIS
EVENING THROUGH TUESDAY NIGHT. DRIER AND COOLER WEATHER IS
ANTICIPATED LATE THIS WEEK INTO NEXT WEEKEND.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 305 PM EDT MON MAY 20 2013
REMNANT GRAVITY WAVE FROM OVERNIGHT CONVECTION AND
ASSOCIATED WITH A ~10F DEGREE DEWPOINT DROP IN ITS WAKE HAS WASHED
OUT AS IT MOVED INTO OUR FORECAST AREA. THIS HAS KEPT MODERATELY
UNSTABLE AIRMASS ACROSS THE EASTERN TWO-THIRDS OF OUR FORECAST AREA.
ADDED SLIGHT CHANCE POPS FOR THE EAST THIS EVENING AS CONVECTION
COULD FIRE ALONG OR IN FRONT OF THIS BOUNDARY WHERE THE AIRMASS IS
CHARACTERIZED BY SBCAPE VALUES IN EXCESS OF 3000 J/KG. THE GREATEST
LIMITING FACTOR IS THE LACK OF SIGNIFICANT FORCING...ALTHOUGH
CONVECTION ACROSS MICHIGAN AND ADDITIONAL CONVECTION FIRING ALONG
THE BOUNDARY ACROSS EASTERN ILLINOIS AT 1830Z INDICATES THIS
BOUNDARY MAY PROVIDE JUST ENOUGH FORCED ASCENT FOR ISOLATED STORM
DEVELOPMENT.
STILL SOME UNCERTAINTY REGARDING CONVECTIVE EVOLUTION AND IMPACTS
ACROSS OUR AREA TONIGHT. DECAYING STORM CLUSTER ACROSS WESTERN
ILLINOIS SHOULD CONTINUE ITS WEAKENING TREND AS IT MOVES INTO A
MOISTURE VOID AREA ACROSS ILLINOIS WITH SURFACE DEWPOINTS IN THE
UPPER 50S. WITH THAT BEING SAID...SOME SHORT TERM MODEL GUIDANCE IS
INDICATING A QUICK RECOVERY OF THE MOISTURE PROFILE IN THAT AREA AS
850 MOISTURE TRANSPORT INCREASES THIS AFTERNOON. IF THE AIRMASS
AHEAD OF THESE STORMS CAN DESTABILIZE OVER THE NEXT FEW HOURS...AS
THE HRRR SUGGESTS...UPSCALE GROWTH OF THAT CLUSTER AS WELL AS
ADDITIONAL STORM DEVELOPMENT MAY TRACK ACROSS THE NORTHWEST PORTION
OF OUR FORECAST AREA DURING THE LATE EVENING. IF STORMS CAN
DEVELOP...SEVERE POTENTIAL DOES EXIST AS 0-6 KM SHEAR OF 35-45 KNOTS
OVERSPREADS THE NORTHWEST PORTION OF OUR FORECAST AREA WITH THE MAIN
THREATS BEING SEVERE HAIL AND WIND.
REMAIN MORE CONFIDENT IN PRECIPITATION CHANCES AFTER 06Z WHEN
REMNANT CONVECTION FROM MISSOURI TRACKS TOWARDS THE AREA. SEVERE
THREAT WILL BE MINIMAL WITH THIS CONVECTION DUE TO ITS TIMING DURING
THE EARLY MORNING HOURS.
TUESDAY LOOKS TO BE COOLER THAN TODAY AS LITTLE SUN WILL BE SEEN
ACROSS OUR FORECAST AREA DUE TO CLOUD DEBRIS FROM FROM OVERNIGHT
CONVECTION AS WELL AS ADDITIONAL DYNAMIC LIFT FROM 40-50 KT LLJ.
SEVERE THREAT DOES EXIST IF A FEW BREAKS IN THE CLOUDS CAN PROVIDE
SIGNIFICANT SURFACE HEATING FOR EVEN MARGINAL SURFACE BASED
INSTABILITY. THE MAIN THREAT WILL BE LARGE HAIL AND DAMAGING WINDS
AS UNIDIRECTIONAL 35-40 KNOT SHEAR OVERSPREADS THE AREA.
&&
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 305 PM EDT MON MAY 20 2013
ONE OR TWO MORE ROUNDS OF CONVECTION TO BEGIN THE FORECAST PERIOD.
MODELS IN PRETTY GOOD AGREEMENT IN SHORT WAVE COMING OUT OF BASE OF
CLOSED LOW AND IMPACTING THE AREA TUE NIGHT. GOOD SUPPORT WILL
ACCOMPANY THIS FEATURE AND 50-60KT MID LEVEL SPEED MAX WILL COMBINE
WITH INFLUX OF LOW LEVEL MOISTURE WITH AT LEAST SUFFICIENT
INSTABILITY TO INITIATE OR MAINTAIN CONVECTION. UNIDIRECTIONAL WIND
PROFILE WITH AROUND 30KT OF SPEED SHEAR WILL HAVE DAMAGING WINDS AS
THE MAIN SEVERE THREAT. CLOSED LOW FINALLY OPENS UP AND WILL MOVE
EASTWARD INTO THE GREAT LAKES REGION WEDNESDAY NIGHT...BRINGING SFC
LOW AND MAIN COLD FRONT WITH IT. MODELS OFFERING VARYING
TIMING/PLACEMENT OF THESE FEATURES BUT ONE MORE ROUND OF CONVECTION
POSSIBLE WEDNESDAY...MAINLY FOR THE EASTERN HALF OF THE CWA. UPPER
TROF AXIS ROTATES THROUGH THE AREA WEDNESDAY NIGHT INTO THURSDAY
KEEPING CHANCE FOR A FEW SHOWERS BEFORE COOLER DRIER CANADIAN HIGH
PRESSURE BEGINS TO BUILD INTO THE GREAT LAKES REGION ON FRIDAY. THIS
WILL PROVIDE A NICE START TO THE HOLIDAY WEEKEND...QUESTIONS REMAIN
AS TO WHETHER IT WILL LAST THROUGH MONDAY. SFC RIDGE AXIS WILL
PROGRESS EASTWARD SUNDAY AND MONDAY...PLACING OUR AREA ON THE
WESTERN PERIPHERY OF THE HIGH WHILE MEDIUM RANGE MODELS ATTEMPTING
TO BRING SHORT WAVE ENERGY DOWN IN NW FLOW. GETTING BETTER MODEL
AGREEMENT WITH THIS SOLN BUT LOTS OF VARIATION IN TIMING AND
PLACEMENT. ENSEMBLE GUIDANCE NEAR OR MOSTLY BELOW CLIMO FOR POPS AS
WELL SO WILL STILL HOLD OUT FOR DRY FORECAST FOR AT LEAST ONE MORE
ISSUANCE. TEMPS TRENDING SEASONABLY COOLER WITH AOB NORMAL FOR MOST
&&
.UPDATE...
ISSUED AT 857 PM EDT MON MAY 20 2013
DIFFICULT FORECAST WITH RESPECT TO CONVECTIVE PROBABILITIES THROUGH
THE FORECAST PERIOD AND DISMAL EARLY FAILURE. AMID A STRONGLY
DIVERGENT BOUNDARY LAYER AXIS PER VIS SAT IMAGERY LYING ACROSS
NERN IL/NWRN IN PAST FEW HOURS...HAS PROVEN TO BE STRONGLY
DETRIMENTAL. THIS DESPITE MODERATE SURFACE BASED INSTABILITY POOL
SITUATED ACROSS NORTHERN INDIANA/SOUTHERN LOWER MICHIGAN THIS
EVENING. A WELL SCOURED/DEEPLY MIXED ENVIRONMENT EXISTS ACROSS
NORTHERN/CENTRAL ILLINOIS WITH PUTRID MID/UPR 50S DPS THIS
EVENING...REMOVES ANY IMMEDIATE CONCERN FOR INITIATION NEXT FEW
HOURS. THIS IMMEDIATE UPSTREAM ENVIRON WAS WITHIN WAKE OF EARLY
AFTERNOON SHORTWAVE...THAT INITIATED STRONG/SEVERE CONVECTION
MIDDAY ACROSS YOOP/NORTHERN LOWER MICHIGAN. EASTERN FRINGE OF DRY
SLOTTED ENVIRONMENT WITH 7.5-8.25 C/KM MID LEVEL LAPSE RATES TO
LIKELY KEEP UPDRAFTS IN CHECK/ISOLATED REMAINDER OF THE EVENING.
WILL MAINTAIN THAT ANY SIG CHANCE FOR CONVECTION TO BE ASSOCIATED
WITH WELL UPSTREAM CONVECTION PRESENTLY ACROSS EAST CENTRAL
MO...WITH SEVERAL HOUR WAIT UNTIL A MORE VIGORED UPSTREAM 925-8H
WIND FIELD WITH PRESENT FOCUS INTO THE OZARKS/NORTHERN ARKANSAS
SHIFTS NORTHEASTWARD OVERNIGHT INTO SRN/CENTRAL ILLINOIS WHILE
JETLET VEERS/RAMPS TO 45-55KTS...FINALLY NOSING INTO KLAF VCNTY
AROUND 09-12 UTC PER RAP/ARW...AND A SIGNIFICANTLY POOR/LAGGARD
HRRR3KM THAT RECENTLY CAME IN LINE TO REALITY. SUFFICIENT
PREPARATORY CONDITIONING/RECOVERY OF ENVIRONMENT VIA MOISTURE
FLUX CONVERGENCE SFC-900MB ALONG/NORTH OF STRONG ISODROSOTHERMAL
GRADIENT WITH UPPER 60S/NEAR 70 DPS SOURCE TAPPED WITH
TIME....PUSHING NORTH OF I70 TO MAINTAIN MUCAPE POOL OF 1200-2000
J/KG ACROSS FORECAST AREA. THIS SHOULD ALLOW DECENT MAINTENANCE OF
CONVECTIVE COMPLEX WITH ACROSS MISSOURI TO REACH NORTHERN INDIANA
WELL AFTER MIDNIGHT INTO KSBN AND NEAR DAYBREAK AT KFWA.
DISFAVORED TIMING/PARCEL ASCENT BECOMING LESS SURFACE BASED WITH
TIME AND MODEST DEEP LAYER SHEAR TO LARGELY PRECLUDE SEVERE
POTENTIAL...THOUGH HAVE CONTD TO ACK THAT STRONGEST CELLS MAY
APPROACH LOW END SEVERE LIMITS IN HWO.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...STEINWEDEL/KG
AVIATION...SKIPPER
SHORT TERM...BENTLEY
LONG TERM...JAL
UPDATE...MURPHY
VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSIWX
WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS TOPEKA KS
610 PM CDT WED MAY 22 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 354 PM CDT WED MAY 22 2013
THE UPPER LOW ASSOCIATED WITH THIS WEEKEND`S ACTIVE SEVERE WEATHER
WAS SITUATED OVER IOWA THIS AFTERNOON...WITH THE ASSOCIATED SURFACE
LOW PROGRESSING EASTWARD INTO WISCONSIN AND ILLINOIS. CLOUD COVER IN
ASSOCIATION WITH THIS SYSTEM STRETCHED WESTWARD INTO NORTHEAST AND
FAR EASTERN KANSAS THROUGH THE AFTERNOON HOURS...WHICH RESULTED IN
SOMEWHAT COOLER TEMPERATURES ACROSS THE REGION TODAY. WITH THE CLOUD
COVER...AFTERNOON HIGHS PEAKED IN THE MIDDLE TO UPPER 60S. SURFACE
HIGH PRESSURE OVER THE NORTHERN PLAINS WILL HELP TO PUSH THE LOW
PRESSURE SYSTEM EASTWARD TOWARD THE GREAT LAKES REGION AS THE HIGH
SPREADS SOUTHWARD INTO THE CENTRAL PLAINS TONIGHT INTO THURSDAY.
WITH THE EXITING SURFACE LOW...SHOULD START SEEING SOME BREAKS IN THE
CLOUD COVER TONIGHT INTO THE OVERNIGHT HOURS. THIS DIMINISHING CLOUD
COVER WILL ALLOW FOR MORE RADIATIONAL COOLING EARLY THURSDAY MORNING
WITH LOW TEMPERATURES EXPECTED TO BE A FEW DEGREES COOLER THAN
NORMAL...IN THE UPPER 40S TO LOWER 50S.
THE WEAK UPPER LEVEL RIDGE THAT WAS IN PLACE OVER THE CENTRAL
ROCKIES THIS AFTERNOON WILL CONTINUE TO BUILD AS IT PROGRESSES
EASTWARD INTO THE CENTRAL AND SOUTHERN PLAINS BY THURSDAY. MODELS
CONTINUE TO SHOW AN EMBEDDED SHORTWAVE DEVELOPING ALONG THE NORTHERN
EXTENT OF THE RIDGE OVER WESTERN KANSAS AND WESTERN OKLAHOMA...WHICH
MAY BRING SOME SCATTERED SHOWERS AND THUNDERSTORMS TO THAT REGION
THROUGH THE DAY. WHILE THIS ACTIVITY IS EXPECTED TO REMAIN SOUTHWEST
OF THE FORECAST AREA ON THURSDAY...SHOULD STILL HAVE SCATTERED CLOUD
COVER ACROSS MUCH OF THE AREA THROUGH THE DAY. THIS CLOUD COVER
COMBINED WITH NORTHEASTERLY WINDS AROUND THE SURFACE HIGH WILL KEEP
AFTERNOON HIGHS COOLER THAN NORMAL WITH READINGS LIKING PEAKING IN
THE UPPER 60S TO LOWER 70S.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 354 PM CDT WED MAY 22 2013
OVERALL PATTERN WILL FEATURE A FLAT RIDGE WITH INCREASING WAA AND
MOISTURE ADVECTION WHICH WILL SERVE TO PRODUCE SEVERAL BOUTS OF
THUNDERSTORM CHCS. THE INITIAL FORCING IS WEAK THU NIGHT INTO FRI
AND SHOULD STAY FOCUSED ACROSS THE NORTHWEST PARTS OF THE CWA. WILL
KEEP RAIN CHCS LOW AND CONFINED TO AREAS TOPEKA NORTH AND WEST FOR
FRI BUT AGAIN WITHOUT A FOCUS AND GREATER FORCING NOT SURE HOW
WIDESPREAD ANY PRECIP WILL BE FRI.
BY FRI NIGHT INTO SAT THETA-E (MOISTURE AND TEMP ADVECTION) WILL
INCREASE ACROSS KS INTO NEBRASKA. NOSE OF THE 50KT LLJ WILL TARGET
NORTHEAST NEB SO IT WOULD APPEAR THAT THE MAIN COMPLEX OF ANY MCS
WOULD BE LOCATED NORTH OF THE AREA HOWEVER CANNOT RULE OUT SCT
CONVECTION WITHIN THE LLJ AXIS OVERNIGHT INTO EARLY SAT. ANOTHER
WEAK WAVE WILL MOVE ACROSS THE RIDGE SAT NIGHT INTO SUN AND THIS
SHOULD HELP ANOTHER CONVECTIVE COMPLEX DEVELOP ACROSS NE/NORTHERN KS
SO WILL KEEP 20 TO 40 POPS WITH THE HIGHEST ACROSS THE NORTHERN
COUNTIES.
SAME PATTERN WILL PERSIST INTO SUN NIGHT AND MON SO HAVE TO EXPECT
AT LEAST SOME CHCS FOR MAINLY NIGHTTIME THUNDERSTORMS ACROSS THE
AREA SUN NIGHT AND MON AS WEAK WAVES MOVE INTO THE FLATTENING RIDGE
AND COMBINE WITH THE NIGHTTIME LLJ TO FEED OVERNIGHT STORMS.
MON AND BEYOND...IT APPEARS THAT RIDGING SHOULD STRENGTHEN BY TUES
AHEAD OF A DEEPENING TROUGH ACROSS THE WEST. THIS SHOULD LEAD TO
GRADUALLY WARMER TEMPS AND PERHAPS A LULL IN PRECIP CHCS BY MID
WEEK.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 610 PM CDT WED MAY 22 2013
THINK THAT THE TERMINALS MAY SCATTER OUT THIS EVENING. HOWEVER THE
NAM AND RAP CONTINUE TO SHOW SOME MVFR CIGS AROUND 2500 FT MOVING
BACK IN FROM THE NORTH BY 12Z. THE CIGS ARE EXPECTED TO GRADUALLY
IMPROVE ABOVE 3 KFT BY NOON THURSDAY WITH A STRATOCU DECK HANGING
IN FOR A PORTION OF THE AFTERNOON. NO PRECIP IS ANTICIPATED DUE TO
A LACK OF FORCING AND SFC WINDS WILL GRADUALLY VEER THROUGH THE
DAY THURSDAY AS SFC RIDGING NOSES IN.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...HENNECKE
LONG TERM...OMITT
AVIATION...WOLTERS
AREA FORECAST DISCUSSION
NWS JACKSON KY
135 PM EDT TUE MAY 21 2013
.UPDATE...
ISSUED AT 135 AM EDT TUE MAY 21 2013
THE AIR IS EXTREMELY UNSTABLE AND THE STORM PREDICTION CENTER JUST
UPDATED THEIR OUTLOOK AND PUT EASTERN KENTUCKY IN AN AREA OF SLIGHT
RISK FOR SEVERE THUNDERSTORMS. THE MAIN THREAT IS FOR STRONG
WINDS...HOWEVER HAIL CAN NOT BE TOTALLY RULED OUT AND WILL LIKELY SEE
SMALL HAIL IN THE AREA TODAY. WITH THE POTENTIALLY SEVERE STORMS IN
THE AREA...THE POSSIBILITY OF GUST FRONTS WELL OUT AHEAD OF THE
THUNDERSTORMS IS POSSIBLE AND COULD CREATE SOME UNEXPECTED STRONG
WINDS. CONFIDENCE IN THE TIMING OF CONVECTIVE EVOLUTION IS NOT
HIGH...AND WAS BASED ON A COMBINATION OF THE NAM AND HIGH RESOLUTION
RAPID REFRESH MODEL. DEPENDING ON HOW MUCH RAIN OCCURS...THERE MAY BE
A TIME OF POST FRONTAL MIST WHICH WOULD LAST A FEW HOURS AND THEN
IMPROVE. DUE TO LOW CONFIDENCE ON TIMING AND EXTENT OF THE
STORMS...THIS WAS NOT ADDED TO THE TAFS. ALSO EXPECTING TO SEE SOME
MIST AT THE TAF STATIONS AND VALLEY FOG IN THE VALLEYS AND NEAR AREAS
THAT GET A LOT OF PRECIPITATION TODAY.
.UPDATE...
ISSUED AT 1026 AM EDT TUE MAY 21 2013
THE FORECAST SOUNDINGS ARE FORECASTING EXTREME INSTABILITY TODAY. THE
NAM BUFFER SOUNDING FOR 4 PM AT JACKSON IS CALLING FOR TOTAL TOTALS
OF 51 AND A LIFTED INDEX OF -7.6. THE CAPE IS FORECAST TO BE 3479
JOULES. THE WIND IS NOT FAVORABLE FOR SEVERE THUNDERSTORMS AS THERE
IS VERY LITTLE SHEAR. THERE IS ALSO VERY LITTLE DRY AIR ALOFT. THE
MAIN ISSUE TODAY WILL BE A TRIGGER TO GET THE STORMS GOING. THERE IS
AN OLD OUTFLOW BOUNDARY CURRENTLY BISECTING EASTERN KENTUCKY FROM
NORTH TO SOUTH. BECAUSE IT IS SO EARLY IN THE DAY...THE LOW LEVEL
INSTABILITY IS CURRENTLY NOT FAVORABLE AND MOST LIKELY WILL NOT BE
FAVORABLE UNTIL THIS OUTFLOW BOUNDARY MOVES INTO WEST VIRGINIA. IT
MAY FIRE UP NEAR THE WEST VIRGINIA BORDER AROUND 11 AM. WILL HAVE TO
WAIT AND SEE. CURRENTLY DO NOT HAVE A GOOD FEEL ON EXACTLY WHERE AND
WHEN THE THUNDERSTORMS ARE GOING TO INITIATE. USED THE OUTPUT OF THE
HIGH RESOLUTION MODEL TO TRY AND TIME SOME IMPULSES THROUGH THE
AREA...HOWEVER CONFIDENCE IS FAIRLY LOW UNTIL CONVECTIVE INITIATION
ACTUALLY OCCURS. WITH ALL THE CONVECTION THAT HAS OCCURRED OUT TO THE
WEST...THERE ARE BOUND TO BE SOME OLD BOUNDARIES THAT MOVE THROUGH
THIS AFTERNOON. ALSO...WITH THE VALLEY FOG THAT OCCURRED THIS
MORNING...SOME DIFFERENTIAL HEATING BOUNDARIES MAY BE ABLE TO
GENERATE A STORM. ONCE THE STORMS ARE GENERATED...ANY OUTFLOWS THEY
PRODUCE SHOULD PROPAGATE ACROSS THE ENTIRE AREA. USUALLY WITH THIS
TYPE OF SOUNDING OVER THE AREA...THE THUNDERSTORMS PRODUCED WILL BE
PULSE TYPE STORMS. A FEW OF THESE STORMS MAY BECOME SEVERE AND
PRODUCE WIND GUSTS UP TO 60 MPH AND 1 INCH HAIL. DUE TO THE LACK OF
WIND SHEAR AND LACK OF ANY STRONG BOUNDARIES...TORNADOES ARE VERY
UNLIKELY TODAY AND WOULD PROBABLY NEED SOME INTERSECTING OUTFLOW
BOUNDARIES TO EVEN HAVE A PRAYER OF FORMING.
UPDATE ISSUED AT 759 AM EDT TUE MAY 21 2013
GRIDS WERE FRESHENED BASED ON RECENT OBS AND TO ACCOUNT FOR THE
OUTFLOW BOUNDARY AND CONVECTION WORKING EAST ACROSS CENTRAL KY THAT
LIKELY WILL NOT COMPLETELY DISSIPATE BEFORE REACHING EASTERN KY. THIS
LED TO SOME CHANGES IN POPS...GENERALLY TO RAISE THEM IN THE WEST
DURING THE AM...AND SLIGHTLY IN THE AFTERNOON ACROSS THE REMAINDER
OF THE AREA.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 324 AM EDT TUE MAY 21 2013
A CLOSED UPPER LEVEL LOW WAS CENTERED OVER THE DAKOTAS EARLY THIS
MORNING WITH A SHORTWAVE TROUGH WORKING TOWARD THE MS VALLEY REGION
AND ANOTHER SHORTWAVE WORKING FROM THE SOUTHERN ROCKIES TOWARD THE
SOUTHERN PLAINS. AT THE SFC...AN AREA OF LOW PRESSURE WAS LOCATED
NEAR THE SD/MN BORDER WITH A WARM FRONT EXTENDING EAST ACROSS THE
GREAT LAKES INTO NEW ENGLAND AND A COLD FRONT TRAILING SOUTH AND THEN
SOUTHWEST INTO THE SOUTHERN PLAINS. PREFRONTAL CONVECTION HAS
WEAKENED BUT EXTENDS FROM THE WESTERN GREAT LAKES INTO HE LOWER OH
VALLEY REGION...NORTH OF THE OB AND PAH AREA AND THEN CONTINUES
SOUTH GENERALLY ALONG THE MS RIVER AND THEN WEST INTO EAST CENTRAL
AR. IT DOES APPEAR THAT THIS CONVECTION HAS OUTFLOWED WITH AN OUTFLOW
BOUNDARY FROM CENTRAL IN DOWN TO NEAR THE EVV VICINITY. LOCALLY
ACROSS EASTERN KY 11-3.9 IMAGERY INDICATES A BIT OF LOW CLOUDS NEAR
BLACK MOUNTAIN AND IN SW VA AND VALLEY FOG...ESPECIALLY IN THE BIG
SANDY REGION. SOME DEBRIS CIRRUS SI ALSO PASSING OVERHEAD.
EARLY THIS MORNING...VALLEY FOG WILL LIKELY CONTINUE AND BECOME DENSE
IN SOME AREAS BEFORE DAWN...DESPITE SOME PASSING CIRRUS. COVERAGE OF
THIS SHOULD BE A BIT MORE WIDESPREAD OVER THE SOUTHEAST THAT
EXPERIENCED CONVECTION OVER THE PAST 24 HORUS. A PRE FIRST PERIOD
WILL BE USED TO COVER THIS.
THE 4Z HRRR AND 0Z NAM GENERALLY SEEM TO BRING AN OUTFLOW BOUNDARY
FROM CONVECTION TO OUR NORTH AND WEST ACROSS THE COMMONWEALTH THIS
MORNING AND INTO EASTERN KY IN THE AFTERNOON. ANY CONVECTION ALONG
WITH WILL PROBABLY BE ISOLATED TO SCATTERED IN NATURE. THE 0Z NAM AND
0Z GFS DIFFER CONSIDERABLY ON INSTABILITY FROM MIDDAY INTO THE
AFTERNOON. THE 0Z NAM FORECASTS A CONSIDERABLE AMOUNT OF MIDLEVEL DRY
AIR AND STEEPER LAPSE RATES ALOFT AS COMPARED TO THE 0Z GFS WHILE THE
GFS IS MORE TAME. THE 0Z NAM LIKELY MOISTENS UP THE BOUNDARY LAYER A
TAD TOO MUCH LEADING TO DEWPOINTS NEARING 70 AND RESULTING IN TOTAL
TOTALS OVER 50...CAPE OVER 50 AND LI OF -9C OR LOWER. REALITY WOULD
PROBABLY BE SOMEWHERE IN BETWEEN...MORE ON THE ORDER OF CAPE IN THE
2000 TO 3000 J/KG RANGE AND LI -4C TO -6C OR SO AND 21Z SREF HAS HIGH
PROBABILITIES OF CAPE GREATER THAN 2000 J/KG AND LI LESS THAN -4C.
THIS WOULD STILL BE SUPPORTIVE OF SOME STRONGER STORMS AND POSSIBLY A
LOCALLY SEVERE STORM WITH HEAVY RAIN...ESPECIALLY IF THERE WERE TO BE
ANY CELL MERGERS. A ONE OR TWO HOUR DIFFERENCE IN CU DEVELOPMENT AND
CONVECTIVE DEVELOPMENT WILL DETERMINE MAX T TODAY. HOWEVER...IT STILL
APPEARS THAT MAX T WILL BE CLOSE TO BREAKING THE RECORD FOR TODAY AT
JKL AND POSSIBLY COME CLOSE AT LOZ.
LOSS OF DAYTIME HEATING WILL LEAD TO LESS ACTIVITY AFTER 0Z AS THE
STRENGTHENING LOW LEVEL JET AND APPROACHING COLD FRONT/MID LEVEL
SHORTWAVE SHOULD FOCUS CONVECTION TO OUR WEST AND NORTHWEST FOR MUCH
OF TONIGHT. IF CLEARING TAKES PLACE...VALLEY FOG SHOULD DEVELOP AND
POSSIBLY BECOME DENSE...ESPECIALLY WHERE ANY CONVECTION OCCURS LATER
TODAY. ATTM...WE PLAN NOT MENTION DENSE FOG JUST PATCHY FOG TO AREAS
OF FOG.
ON WEDNESDAY...THE COLD FRONT AND MID LEVEL WAVE WILL APPROACH THE
AREA...THOUGH THE LOW LEVEL JET CORE WITH THE STRONGER WINDS ALOFT
GENERALLY TO OUR NORTH AND NORTHWEST. SOME DEGREE OF DEBRIS CLOUDS
MAY WORK ACROSS THE AREA ON WED...BUT MODERATE 0Z MODELS AND 21Z
FORECAST MODERATE INSTABILITY AND MORE IN THE WAY OF SHEAR AS
COMPARED TO TODAY. THIS SHOULD LEAD TO STRENGTHENING OF CONVECTION AS
IT MOVES INTO EASTERN KY AND PROBABLY AN UPTICK IN COVERAGE AS WELL.
ONE OR MORE LINES OF STORMS...POSSIBLY STRONG TO LOCALLY SEVERE
SHOULD WORK ACROSS THE REGION. GUSTY WINDS WOULD APPEAR TO BE THE
PRIMARY THREAT WITH STORMS ON WED...THOUGH SOME SMALL TO MARGINALLY
SEVERE HAIL COULD OCCUR AS WELL AS LOCALLY HEAVY RAIN. LIKELY POPS
WERE CONTINUED FOR WEDNESDAY. ONCE AGAIN TIMING OF ARRIVAL OF DEBRIS
CLOUDS AND CONVECTIVE DEVELOPMENT WILL DETERMINE MAX T ON WED...BUT
EASTERN LOCATIONS SHOULD SEE THIS OCCUR THE LATEST AND SHOULD AVERAGE
WARMER THAN MORE CENTRAL AND WESTERN LOCATIONS.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 415 AM EDT TUE MAY 21 2013
THE MODELS REMAIN IN GOOD AGREEMENT WITH A BLOCKY UPPER LEVEL PATTERN
TO TAKE SHAPE ACROSS THE CONUS INTO EARLY NEXT WEEK...ALTHOUGH
DETAILS BECOME MORE MURKY BY THIS WEEKEND...WITH SOME DISAGREEMENT
WITH THE SMALLER SCALE FEATURES. AS SUCH...GENERALLY RELIED ON A
BLEND OF THE GUIDANCE.
A DEEP UPPER LEVEL TROUGH WILL SWING THROUGH THE OHIO VALLEY WEDNESDAY
NIGHT INTO THURSDAY...KEEPING GOOD CHANCE TO LIKELY POPS THREATENING
EASTERN KENTUCKY. THERE HAS BEEN A TREND OF A QUICKER EXIT WITH THIS
FEATURE. INSTABILITY WILL WANE QUICKLY BY LATE IN THE DAY ON
THURSDAY...SO REMOVED THUNDER CHANCES FOR THURSDAY NIGHT.
COOL HIGH PRESSURE WILL THEN BRING DRY CONDITIONS TO CONCLUDE THE
WORK WEEK. THIS WEEKEND...THE ECMWF AND GFS DIFFER QUITE A BIT WITH
THE TIMING AND EVOLUTION OF THE NEXT SYSTEM TO AFFECT THE AREA. THE
ECMWF IS PRETTY TRANSIENT WITH THE HIGH PRESSURE...AND ALLOWS A WARM
FRONT TO MOVE IN QUICKLY BY EARLY SATURDAY. THIS BOUNDARY THEN STALLS
ACROSS THE SOUTHERN HALF OF THE AREA...WITH OCCASIONAL SHORT WAVE
TROUGHS TRAVERSING THE NORTHWEST FLOW ALOFT. THE GFS IS MUCH SLOWER
HERE...AND KEEPS THE SURFACE BOUNDARY SHUNTED MORE TO THE NORTH.
GIVEN THE UNCERTAINTY...DID ALLOW FOR A RETURN OF SLIGHT TO CHANCE
POPS...ALTHOUGH NOT AS AGGRESSIVE AS THE ECMWF.
TEMPERATURES WILL GENERALLY AVERAGE A LITTLE BELOW NORMAL THROUGH
THE PERIOD...WITH FRIDAY BEING THE COOLEST DAY...AS HIGHS WILL
RETREAT TO THE 60S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 135 PM EDT TUE MAY 21 2013
THE AIR IS EXTREMELY UNSTABLE AND THE STORM PREDICTION CENTER JUST
UPDATED THEIR OUTLOOK AND PUT EASTERN KENTUCKY IN AN AREA OF SLIGHT
RISK FOR SEVERE THUNDERSTORMS. THE MAIN THREAT IS FOR STRONG
WINDS...HOWEVER HAIL CAN NOT BE TOTALLY RULED OUT AND WILL LIKELY SEE
SMALL HAIL IN THE AREA TODAY. WITH THE POTENTIALLY SEVERE STORMS IN
THE AREA...THE POSSIBILITY OF GUST FRONTS WELL OUT AHEAD OF THE
THUNDERSTORMS IS POSSIBLE AND COULD CREATE SOME STRONG LLWS. CONFIDENCE
IN THE TIMING OF CONVECTIVE EVOLUTION IS NOT HIGH...AND WAS BASED ON
A COMBINATION OF THE NAM AND HIGH RESOLUTION RAPID REFRESH MODEL.
DEPENDING ON HOW MUCH RAIN OCCURS...THERE MAY BE A TIME OF POST
FRONTAL MIST WHICH WOULD LAST A FEW HOURS AND THEN IMPROVE. DUE TO
LOW CONFIDENCE ON TIMING AND EXTENT OF THE STORMS...THIS WAS NOT
ADDED TO THE TAFS. ALSO EXPECTING TO SEE SOME MIST AT THE TAF
STATIONS AND VALLEY FOG IN THE VALLEYS AND NEAR AREAS THAT GET A LOT
OF PRECIPITATION TODAY.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JJ
SHORT TERM...JP
LONG TERM...GEOGERIAN
AVIATION...JJ
AREA FORECAST DISCUSSION
NWS JACKSON KY
1026 AM EDT TUE MAY 21 2013
.UPDATE...
ISSUED AT 1026 AM EDT TUE MAY 21 2013
THE FORECAST SOUNDINGS ARE FORECASTING EXTREME INSTABILITY TODAY. THE
NAM BUFFER SOUNDING FOR 4 PM AT JACKSON IS CALLING FOR TOTAL TOTALS
OF 51 AND A LIFTED INDEX OF -7.6. THE CAPE IS FORECAST TO BE 3479
JOULES. THE WIND IS NOT FAVORABLE FOR SEVERE THUNDERSTORMS AS THERE
IS VERY LITTLE SHEAR. THERE IS ALSO VERY LITTLE DRY AIR ALOFT. THE
MAIN ISSUE TODAY WILL BE A TRIGGER TO GET THE STORMS GOING. THERE IS
AN OLD OUTFLOW BOUNDARY CURRENTLY BISECTING EASTERN KENTUCKY FROM
NORTH TO SOUTH. BECAUSE IT IS SO EARLY IN THE DAY...THE LOW LEVEL
INSTABILITY IS CURRENTLY NOT FAVORABLE AND MOST LIKELY WILL NOT BE
FAVORABLE UNTIL THIS OUTFLOW BOUNDARY MOVES INTO WEST VIRGINIA. IT
MAY FIRE UP NEAR THE WEST VIRGINIA BORDER AROUND 11 AM. WILL HAVE TO
WAIT AND SEE. CURRENTLY DO NOT HAVE A GOOD FEEL ON EXACTLY WHERE AND
WHEN THE THUNDERSTORMS ARE GOING TO INITIATE. USED THE OUTPUT OF THE
HIGH RESOLUTION MODEL TO TRY AND TIME SOME IMPULSES THROUGH THE
AREA...HOWEVER CONFIDENCE IS FAIRLY LOW UNTIL CONVECTIVE INITIATION
ACTUALLY OCCURS. WITH ALL THE CONVECTION THAT HAS OCCURRED OUT TO THE
WEST...THERE ARE BOUND TO BE SOME OLD BOUNDARIES THAT MOVE THROUGH
THIS AFTERNOON. ALSO...WITH THE VALLEY FOG THAT OCCURRED THIS
MORNING...SOME DIFFERENTIAL HEATING BOUNDARIES MAY BE ABLE TO
GENERATE A STORM. ONCE THE STORMS ARE GENERATED...ANY OUTFLOWS THEY
PRODUCE SHOULD PROPAGATE ACROSS THE ENTIRE AREA. USUALLY WITH THIS
TYPE OF SOUNDING OVER THE AREA...THE THUNDERSTORMS PRODUCED WILL BE
PULSE TYPE STORMS. A FEW OF THESE STORMS MAY BECOME SEVERE AND
PRODUCE WIND GUSTS UP TO 60 MPH AND 1 INCH HAIL. DUE TO THE LACK OF
WIND SHEAR AND LACK OF ANY STRONG BOUNDARIES...TORNADOES ARE VERY
UNLIKELY TODAY AND WOULD PROBABLY NEED SOME INTERSECTING OUTFLOW
BOUNDARIES TO EVEN HAVE A PRAYER OF FORMING.
UPDATE ISSUED AT 759 AM EDT TUE MAY 21 2013
GRIDS WERE FRESHENED BASED ON RECENT OBS AND TO ACCOUNT FOR THE
OUTFLOW BOUNDARY AND CONVECTION WORKING EAST ACROSS CENTRAL KY THAT
LIKELY WILL NOT COMPLETELY DISSIPATE BEFORE REACHING EASTERN KY. THIS
LED TO SOME CHANGES IN POPS...GENERALLY TO RAISE THEM IN THE WEST
DURING THE AM...AND SLIGHTLY IN THE AFTERNOON ACROSS THE REMAINDER
OF THE AREA.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 324 AM EDT TUE MAY 21 2013
A CLOSED UPPER LEVEL LOW WAS CENTERED OVER THE DAKOTAS EARLY THIS
MORNING WITH A SHORTWAVE TROUGH WORKING TOWARD THE MS VALLEY REGION
AND ANOTHER SHORTWAVE WORKING FROM THE SOUTHERN ROCKIES TOWARD THE
SOUTHERN PLAINS. AT THE SFC...AN AREA OF LOW PRESSURE WAS LOCATED
NEAR THE SD/MN BORDER WITH A WARM FRONT EXTENDING EAST ACROSS THE
GREAT LAKES INTO NEW ENGLAND AND A COLD FRONT TRAILING SOUTH AND THEN
SOUTHWEST INTO THE SOUTHERN PLAINS. PREFRONTAL CONVECTION HAS
WEAKENED BUT EXTENDS FROM THE WESTERN GREAT LAKES INTO HE LOWER OH
VALLEY REGION...NORTH OF THE OB AND PAH AREA AND THEN CONTINUES
SOUTH GENERALLY ALONG THE MS RIVER AND THEN WEST INTO EAST CENTRAL
AR. IT DOES APPEAR THAT THIS CONVECTION HAS OUTFLOWED WITH AN OUTFLOW
BOUNDARY FROM CENTRAL IN DOWN TO NEAR THE EVV VICINITY. LOCALLY
ACROSS EASTERN KY 11-3.9 IMAGERY INDICATES A BIT OF LOW CLOUDS NEAR
BLACK MOUNTAIN AND IN SW VA AND VALLEY FOG...ESPECIALLY IN THE BIG
SANDY REGION. SOME DEBRIS CIRRUS SI ALSO PASSING OVERHEAD.
EARLY THIS MORNING...VALLEY FOG WILL LIKELY CONTINUE AND BECOME DENSE
IN SOME AREAS BEFORE DAWN...DESPITE SOME PASSING CIRRUS. COVERAGE OF
THIS SHOULD BE A BIT MORE WIDESPREAD OVER THE SOUTHEAST THAT
EXPERIENCED CONVECTION OVER THE PAST 24 HORUS. A PRE FIRST PERIOD
WILL BE USED TO COVER THIS.
THE 4Z HRRR AND 0Z NAM GENERALLY SEEM TO BRING AN OUTFLOW BOUNDARY
FROM CONVECTION TO OUR NORTH AND WEST ACROSS THE COMMONWEALTH THIS
MORNING AND INTO EASTERN KY IN THE AFTERNOON. ANY CONVECTION ALONG
WITH WILL PROBABLY BE ISOLATED TO SCATTERED IN NATURE. THE 0Z NAM AND
0Z GFS DIFFER CONSIDERABLY ON INSTABILITY FROM MIDDAY INTO THE
AFTERNOON. THE 0Z NAM FORECASTS A CONSIDERABLE AMOUNT OF MIDLEVEL DRY
AIR AND STEEPER LAPSE RATES ALOFT AS COMPARED TO THE 0Z GFS WHILE THE
GFS IS MORE TAME. THE 0Z NAM LIKELY MOISTENS UP THE BOUNDARY LAYER A
TAD TOO MUCH LEADING TO DEWPOINTS NEARING 70 AND RESULTING IN TOTAL
TOTALS OVER 50...CAPE OVER 50 AND LI OF -9C OR LOWER. REALITY WOULD
PROBABLY BE SOMEWHERE IN BETWEEN...MORE ON THE ORDER OF CAPE IN THE
2000 TO 3000 J/KG RANGE AND LI -4C TO -6C OR SO AND 21Z SREF HAS HIGH
PROBABILITIES OF CAPE GREATER THAN 2000 J/KG AND LI LESS THAN -4C.
THIS WOULD STILL BE SUPPORTIVE OF SOME STRONGER STORMS AND POSSIBLY A
LOCALLY SEVERE STORM WITH HEAVY RAIN...ESPECIALLY IF THERE WERE TO BE
ANY CELL MERGERS. A ONE OR TWO HOUR DIFFERENCE IN CU DEVELOPMENT AND
CONVECTIVE DEVELOPMENT WILL DETERMINE MAX T TODAY. HOWEVER...IT STILL
APPEARS THAT MAX T WILL BE CLOSE TO BREAKING THE RECORD FOR TODAY AT
JKL AND POSSIBLY COME CLOSE AT LOZ.
LOSS OF DAYTIME HEATING WILL LEAD TO LESS ACTIVITY AFTER 0Z AS THE
STRENGTHENING LOW LEVEL JET AND APPROACHING COLD FRONT/MID LEVEL
SHORTWAVE SHOULD FOCUS CONVECTION TO OUR WEST AND NORTHWEST FOR MUCH
OF TONIGHT. IF CLEARING TAKES PLACE...VALLEY FOG SHOULD DEVELOP AND
POSSIBLY BECOME DENSE...ESPECIALLY WHERE ANY CONVECTION OCCURS LATER
TODAY. ATTM...WE PLAN NOT MENTION DENSE FOG JUST PATCHY FOG TO AREAS
OF FOG.
ON WEDNESDAY...THE COLD FRONT AND MID LEVEL WAVE WILL APPROACH THE
AREA...THOUGH THE LOW LEVEL JET CORE WITH THE STRONGER WINDS ALOFT
GENERALLY TO OUR NORTH AND NORTHWEST. SOME DEGREE OF DEBRIS CLOUDS
MAY WORK ACROSS THE AREA ON WED...BUT MODERATE 0Z MODELS AND 21Z
FORECAST MODERATE INSTABILITY AND MORE IN THE WAY OF SHEAR AS
COMPARED TO TODAY. THIS SHOULD LEAD TO STRENGTHENING OF CONVECTION AS
IT MOVES INTO EASTERN KY AND PROBABLY AN UPTICK IN COVERAGE AS WELL.
ONE OR MORE LINES OF STORMS...POSSIBLY STRONG TO LOCALLY SEVERE
SHOULD WORK ACROSS THE REGION. GUSTY WINDS WOULD APPEAR TO BE THE
PRIMARY THREAT WITH STORMS ON WED...THOUGH SOME SMALL TO MARGINALLY
SEVERE HAIL COULD OCCUR AS WELL AS LOCALLY HEAVY RAIN. LIKELY POPS
WERE CONTINUED FOR WEDNESDAY. ONCE AGAIN TIMING OF ARRIVAL OF DEBRIS
CLOUDS AND CONVECTIVE DEVELOPMENT WILL DETERMINE MAX T ON WED...BUT
EASTERN LOCATIONS SHOULD SEE THIS OCCUR THE LATEST AND SHOULD AVERAGE
WARMER THAN MORE CENTRAL AND WESTERN LOCATIONS.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 415 AM EDT TUE MAY 21 2013
THE MODELS REMAIN IN GOOD AGREEMENT WITH A BLOCKY UPPER LEVEL PATTERN
TO TAKE SHAPE ACROSS THE CONUS INTO EARLY NEXT WEEK...ALTHOUGH
DETAILS BECOME MORE MURKY BY THIS WEEKEND...WITH SOME DISAGREEMENT
WITH THE SMALLER SCALE FEATURES. AS SUCH...GENERALLY RELIED ON A
BLEND OF THE GUIDANCE.
A DEEP UPPER LEVEL TROUGH WILL SWING THROUGH THE OHIO VALLEY WEDNESDAY
NIGHT INTO THURSDAY...KEEPING GOOD CHANCE TO LIKELY POPS THREATENING
EASTERN KENTUCKY. THERE HAS BEEN A TREND OF A QUICKER EXIT WITH THIS
FEATURE. INSTABILITY WILL WANE QUICKLY BY LATE IN THE DAY ON
THURSDAY...SO REMOVED THUNDER CHANCES FOR THURSDAY NIGHT.
COOL HIGH PRESSURE WILL THEN BRING DRY CONDITIONS TO CONCLUDE THE
WORK WEEK. THIS WEEKEND...THE ECMWF AND GFS DIFFER QUITE A BIT WITH
THE TIMING AND EVOLUTION OF THE NEXT SYSTEM TO AFFECT THE AREA. THE
ECMWF IS PRETTY TRANSIENT WITH THE HIGH PRESSURE...AND ALLOWS A WARM
FRONT TO MOVE IN QUICKLY BY EARLY SATURDAY. THIS BOUNDARY THEN STALLS
ACROSS THE SOUTHERN HALF OF THE AREA...WITH OCCASIONAL SHORT WAVE
TROUGHS TRAVERSING THE NORTHWEST FLOW ALOFT. THE GFS IS MUCH SLOWER
HERE...AND KEEPS THE SURFACE BOUNDARY SHUNTED MORE TO THE NORTH.
GIVEN THE UNCERTAINTY...DID ALLOW FOR A RETURN OF SLIGHT TO CHANCE
POPS...ALTHOUGH NOT AS AGGRESSIVE AS THE ECMWF.
TEMPERATURES WILL GENERALLY AVERAGE A LITTLE BELOW NORMAL THROUGH
THE PERIOD...WITH FRIDAY BEING THE COOLEST DAY...AS HIGHS WILL
RETREAT TO THE 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 759 AM EDT TUE MAY 21 2013
ANY LINGERING VALLEY FOG WILL DISSIPATE THROUGH 1330Z. AN OUTFLOW
BOUNDARY WILL WORK INTO EASTERN KY DURING THE FIRST TWO HOURS OF THE
PERIOD...WITH ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS TO
AFFECT LOZ AND SME BY 15Z...AND POSSIBLY FURTHER EAST AT JKL AROUND
16Z. CONFIDENCE IN CONVECTIVE EVOLUTION THROUGH THE PERIOD IS NOT
EXTREMELY HIGH...BUT CONVECTION CANNOT BE RULED OUT DURING MUCH OF
THE PERIOD AND THUS VCTS AND CB WAS USED FOR MOST OF THE PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JJ
SHORT TERM...JP
LONG TERM...GEOGERIAN
AVIATION...JP
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
804 AM EDT TUE MAY 21 2013
.UPDATE...
ISSUED AT 759 AM EDT TUE MAY 21 2013
GRIDS WERE FRESHENED BASED ON RECENT OBS AND TO ACCOUNT FOR THE
OUTFLOW BOUNDARY AND CONVECTION WORKING EAST ACROSS CENTRAL KY THAT
LIKELY WILL NOT COMPLETELY DISSIPATE BEFORE REACHING EASTERN KY. THIS
LED TO SOME CHANGES IN POPS...GENERALLY TO RAISE THEM IN THE WEST
DURING THE AM...AND SLIGHTLY IN THE AFTERNOON ACROSS THE REMAINDER
OF THE AREA.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 324 AM EDT TUE MAY 21 2013
A CLOSED UPPER LEVEL LOW WAS CENTERED OVER THE DAKOTAS EARLY THIS
MORNING WITH A SHORTWAVE TROUGH WORKING TOWARD THE MS VALLEY REGION
AND ANOTHER SHORTWAVE WORKING FROM THE SOUTHERN ROCKIES TOWARD THE
SOUTHERN PLAINS. AT THE SFC...AN AREA OF LOW PRESSURE WAS LOCATED
NEAR THE SD/MN BORDER WITH A WARM FRONT EXTENDING EAST ACROSS THE
GREAT LAKES INTO NEW ENGLAND AND A COLD FRONT TRAILING SOUTH AND THEN
SOUTHWEST INTO THE SOUTHERN PLAINS. PREFRONTAL CONVECTION HAS
WEAKENED BUT EXTENDS FROM THE WESTERN GREAT LAKES INTO HE LOWER OH
VALLEY REGION...NORTH OF THE OWB AND PAH AREA AND THEN CONTINUES
SOUTH GENERALLY ALONG THE MS RIVER AND THEN WEST INTO EAST CENTRAL
AR. IT DOES APPEAR THAT THIS CONVECTION HAS OUTFLOWED WITH AN OUTFLOW
BOUNDARY FROM CENTRAL IN DOWN TO NEAR THE EVV VICINITY. LOCALLY
ACROSS EASTERN KY 11-3.9 IMAGERY INDICATES A BIT OF LOW CLOUDS NEAR
BLACK MOUNTAIN AND IN SW VA AND VALLEY FOG...ESPECIALLY IN THE BIG
SANDY REGION. SOME DEBRIS CIRRUS SI ALSO PASSING OVERHEAD.
EARLY THIS MORNING...VALLEY FOG WILL LIKELY CONTINUE AND BECOME DENSE
IN SOME AREAS BEFORE DAWN...DESPITE SOME PASSING CIRRUS. COVERAGE OF
THIS SHOULD BE A BIT MORE WIDESPREAD OVER THE SOUTHEAST THAT
EXPERIENCED CONVECTION OVER THE PAST 24 HORUS. A PREFIRST PERIOD
WILL BE USED TO COVER THIS.
THE 4Z HRRR AND 0Z NAM GENERALLY SEEM TO BRING AN OUTFLOW BOUNDARY
FROM CONVECTION TO OUR NORTH AND WEST ACROSS THE COMMONWEALTH THIS
MORNING AND INTO EASTERN KY IN THE AFTERNOON. ANY CONVECTION ALONG
WITH WILL PROBABLY BE ISOLATED TO SCATTERED IN NATURE. THE 0Z NAM AND
0Z GFS DIFFER CONSIDERABLY ON INSTABILITY FROM MIDDAY INTO THE
AFTERNOON. THE 0Z NAM FORECASTS A CONSIDERABLE AMOUNT OF MIDLEVEL DRY
AIR AND STEEPER LAPSE RATES ALOFT AS COMPARED TO THE 0Z GFS WHILE THE
GFS IS MORE TAME. THE 0Z NAM LIKELY MOISTENS UP THE BOUNDARY LAYER A
TAD TOO MUCH LEADING TO DEWPOINTS NEARING 70 AND RESULTING IN TOTAL
TOTALS OVER 50...CAPE OVER 50 AND LI OF -9C OR LOWER. REALITY WOULD
PROBABLY BE SOMEWHERE IN BETWEEN...MORE ON THE ORDER OF CAPE IN THE
2000 TO 3000 J/KG RANGE AND LI -4C TO -6C OR SO AND 21Z SREF HAS HIGH
PROBABILITIES OF CAPE GREATER THAN 2000 J/KG AND LI LESS THAN -4C.
THIS WOULD STILL BE SUPPORTIVE OF SOME STRONGER STORMS AND POSSIBLY A
LOCALLY SEVERE STORM WITH HEAVY RAIN...ESPECIALLY IF THERE WERE TO BE
ANY CELL MERGERS. A ONE OR TWO HOUR DIFFERENCE IN CU DEVELOPMENT AND
CONVECTIVE DEVELOPMENT WILL DETERMINE MAX T TODAY. HOWEVER...IT STILL
APPEARS THAT MAX T WILL BE CLOSE TO BREAKING THE RECORD FOR TODAY AT
JKL AND POSSIBLY COME CLOSE AT LOZ.
LOSS OF DAYTIME HEATING WILL LEAD TO LESS ACTIVITY AFTER 0Z AS THE
STRENGTHENING LOW LEVEL JET AND APPROACHING COLD FRONT/MID LEVEL
SHORTWAVE SHOULD FOCUS CONVECTION TO OUR WEST AND NORTHWEST FOR MUCH
OF TONIGHT. IF CLEARING TAKES PLACE...VALLEY FOG SHOULD DEVELOP AND
POSSIBLY BECOME DENSE...ESPECIALLY WHERE ANY CONVECTION OCCURS LATER
TODAY. ATTM...WE PLAN NOT MENTION DENSE FOG JUST PATCHY FOG TO AREAS
OF FOG.
ON WEDNESDAY...THE COLD FRONT AND MID LEVEL WAVE WILL APPROACH THE
AREA...THOUGH THE LOW LEVEL JET CORE WITH THE STRONGER WINDS ALOFT
GENERALLY TO OUR NORTH AND NORTHWEST. SOME DEGREE OF DEBRIS CLOUDS
MAY WORK ACROSS THE AREA ON WED...BUT MODERATE 0Z MODELS AND 21Z
FORECAST MODERATE INSTABILITY AND MORE IN THE WAY OF SHEAR AS
COMPARED TO TODAY. THIS SHOULD LEAD TO STRENGTHENING OF CONVECTION AS
IT MOVES INTO EASTERN KY AND PROBABLY AN UPTICK IN COVERAGE AS WELL.
ONE OR MORE LINES OF STORMS...POSSIBLY STRONG TO LOCALLY SEVERE
SHOULD WORK ACROSS THE REGION. GUSTY WINDS WOULD APPEAR TO BE THE
PRIMARY THREAT WITH STORMS ON WED...THOUGH SOME SMALL TO MARGINALLY
SEVERE HAIL COULD OCCUR AS WELL AS LOCALLY HEAVY RAIN. LIKELY POPS
WERE CONTINUED FOR WEDNESDAY. ONCE AGAIN TIMING OF ARRIVAL OF DEBRIS
CLOUDS AND CONVECTIVE DEVELOPMENT WILL DETERMINE MAX T ON WED...BUT
EASTERN LOCATIONS SHOULD SEE THIS OCCUR THE LATEST AND SHOULD AVERAGE
WARMER THAN MORE CENTRAL AND WESTERN LOCATIONS.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 415 AM EDT TUE MAY 21 2013
THE MODELS REMAIN IN GOOD AGREEMENT WITH A BLOCKY UPPER LEVEL PATTERN
TO TAKE SHAPE ACROSS THE CONUS INTO EARLY NEXT WEEK...ALTHOUGH
DETAILS BECOME MORE MURKY BY THIS WEEKEND...WITH SOME DISAGREEMENT
WITH THE SMALLER SCALE FEATURES. AS SUCH...GENERALLY RELIED ON A
BLEND OF THE GUIDANCE.
A DEEP UPPER LEVEL TROUGH WILL SWING THROUGH THE OHIO VALLEY WEDNESDAY
NIGHT INTO THURSDAY...KEEPING GOOD CHANCE TO LIKELY POPS THREATENING
EASTERN KENTUCKY. THERE HAS BEEN A TREND OF A QUICKER EXIT WITH THIS
FEATURE. INSTABILITY WILL WANE QUICKLY BY LATE IN THE DAY ON
THURSDAY...SO REMOVED THUNDER CHANCES FOR THURSDAY NIGHT.
COOL HIGH PRESSURE WILL THEN BRING DRY CONDITIONS TO CONCLUDE THE
WORK WEEK. THIS WEEKEND...THE ECMWF AND GFS DIFFER QUITE A BIT WITH
THE TIMING AND EVOLUTION OF THE NEXT SYSTEM TO AFFECT THE AREA. THE
ECMWF IS PRETTY TRANSIENT WITH THE HIGH PRESSURE...AND ALLOWS A WARM
FRONT TO MOVE IN QUICKLY BY EARLY SATURDAY. THIS BOUNDARY THEN STALLS
ACROSS THE SOUTHERN HALF OF THE AREA...WITH OCCASIONAL SHORT WAVE
TROUGHS TRAVERSING THE NORTHWEST FLOW ALOFT. THE GFS IS MUCH SLOWER
HERE...AND KEEPS THE SURFACE BOUNDARY SHUNTED MORE TO THE NORTH.
GIVEN THE UNCERTAINTY...DID ALLOW FOR A RETURN OF SLIGHT TO CHANCE
POPS...ALTHOUGH NOT AS AGGRESSIVE AS THE ECMWF.
TEMPERATURES WILL GENERALLY AVERAGE A LITTLE BELOW NORMAL THROUGH
THE PERIOD...WITH FRIDAY BEING THE COOLEST DAY...AS HIGHS WILL
RETREAT TO THE 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 759 AM EDT TUE MAY 21 2013
ANY LINGERING VALLEY FOG WILL DISSIAPTE THROUGH 1330Z. AN OUTFLOW
BOUNDARY WILL WORK INTO EASTERN KY DURING THE FIRST TWO HOURS OF THE
PERIOD...WITH ISOALTED TO SCATTERED SHOWERS AND THUNDERSTORMS TO
AFFECT LOZ AND SME BY 15Z...AND POSSIBLY FURTHER EAST AT JKL AROUND
16Z. CONFIDENCE IN CONVECTIVE EVOLUTION THROUGH THE PERIOD IS NOT
EXTREMELY HIGH...BUT CONVECTION CANNOT BE RULED OUT DURING MUCH OF
THE PERIOD AND THUS VCTS AND CB WAS USED FOR MOST OF THE PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JP
SHORT TERM...JP
LONG TERM...GEOGERIAN
AVIATION...JP
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
415 AM EDT TUE MAY 21 2013
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 324 AM EDT TUE MAY 21 2013
A CLOSED UPPER LEVEL LOW WAS CENTERED OVER THE DAKOTAS EARLY THIS
MORNING WITH A SHORTWAVE TROUGH WORKING TOWARD THE MS VALLEY REGION
AND ANOTHER SHORTWAVE WORKING FROM THE SOUTHERN ROCKIES TOWARD THE
SOUTHERN PLAINS. AT THE SFC...AN AREA OF LOW PRESSURE WAS LOCATED
NEAR THE SD/MN BORDER WITH A WARM FRONT EXTENDING EAST ACROSS THE
GREAT LAKES INTO NEW ENGLAND AND A COLD FRONT TRAILING SOUTH AND THEN
SOUTHWEST INTO THE SOUTHERN PLAINS. PREFRONTAL CONVECTION HAS
WEAKENED BUT EXTENDS FROM THE WESTERN GREAT LAKES INTO HE LOWER OH
VALLEY REGION...NORTH OF THE OWB AND PAH AREA AND THEN CONTINUES
SOUTH GENERALLY ALONG THE MS RIVER AND THEN WEST INTO EAST CENTRAL
AR. IT DOES APPEAR THAT THIS CONVECTION HAS OUTFLOWED WITH AN OUTFLOW
BOUNDARY FROM CENTRAL IN DOWN TO NEAR THE EVV VICINITY. LOCALLY
ACROSS EASTERN KY 11-3.9 IMAGERY INDICATES A BIT OF LOW CLOUDS NEAR
BLACK MOUNTAIN AND IN SW VA AND VALLEY FOG...ESPECIALLY IN THE BIG
SANDY REGION. SOME DEBRIS CIRRUS SI ALSO PASSING OVERHEAD.
EARLY THIS MORNING...VALLEY FOG WILL LIKELY CONTINUE AND BECOME DENSE
IN SOME AREAS BEFORE DAWN...DESPITE SOME PASSING CIRRUS. COVERAGE OF
THIS SHOULD BE A BIT MORE WIDESPREAD OVER THE SOUTHEAST THAT
EXPERIENCED CONVECTION OVER THE PAST 24 HORUS. A PREFIRST PERIOD
WILL BE USED TO COVER THIS.
THE 4Z HRRR AND 0Z NAM GENERALLY SEEM TO BRING AN OUTFLOW BOUNDARY
FROM CONVECTION TO OUR NORTH AND WEST ACROSS THE COMMONWEALTH THIS
MORNING AND INTO EASTERN KY IN THE AFTERNOON. ANY CONVECTION ALONG
WITH WILL PROBABLY BE ISOLATED TO SCATTERED IN NATURE. THE 0Z NAM AND
0Z GFS DIFFER CONSIDERABLY ON INSTABILITY FROM MIDDAY INTO THE
AFTERNOON. THE 0Z NAM FORECASTS A CONSIDERABLE AMOUNT OF MIDLEVEL DRY
AIR AND STEEPER LAPSE RATES ALOFT AS COMPARED TO THE 0Z GFS WHILE THE
GFS IS MORE TAME. THE 0Z NAM LIKELY MOISTENS UP THE BOUNDARY LAYER A
TAD TOO MUCH LEADING TO DEWPOINTS NEARING 70 AND RESULTING IN TOTAL
TOTALS OVER 50...CAPE OVER 50 AND LI OF -9C OR LOWER. REALITY WOULD
PROBABLY BE SOMEWHERE IN BETWEEN...MORE ON THE ORDER OF CAPE IN THE
2000 TO 3000 J/KG RANGE AND LI -4C TO -6C OR SO AND 21Z SREF HAS HIGH
PROBABILITIES OF CAPE GREATER THAN 2000 J/KG AND LI LESS THAN -4C.
THIS WOULD STILL BE SUPPORTIVE OF SOME STRONGER STORMS AND POSSIBLY A
LOCALLY SEVERE STORM WITH HEAVY RAIN...ESPECIALLY IF THERE WERE TO BE
ANY CELL MERGERS. A ONE OR TWO HOUR DIFFERENCE IN CU DEVELOPMENT AND
CONVECTIVE DEVELOPMENT WILL DETERMINE MAX T TODAY. HOWEVER...IT STILL
APPEARS THAT MAX T WILL BE CLOSE TO BREAKING THE RECORD FOR TODAY AT
JKL AND POSSIBLY COME CLOSE AT LOZ.
LOSS OF DAYTIME HEATING WILL LEAD TO LESS ACTIVITY AFTER 0Z AS THE
STRENGTHENING LOW LEVEL JET AND APPROACHING COLD FRONT/MID LEVEL
SHORTWAVE SHOULD FOCUS CONVECTION TO OUR WEST AND NORTHWEST FOR MUCH
OF TONIGHT. IF CLEARING TAKES PLACE...VALLEY FOG SHOULD DEVELOP AND
POSSIBLY BECOME DENSE...ESPECIALLY WHERE ANY CONVECTION OCCURS LATER
TODAY. ATTM...WE PLAN NOT MENTION DENSE FOG JUST PATCHY FOG TO AREAS
OF FOG.
ON WEDNESDAY...THE COLD FRONT AND MID LEVEL WAVE WILL APPROACH THE
AREA...THOUGH THE LOW LEVEL JET CORE WITH THE STRONGER WINDS ALOFT
GENERALLY TO OUR NORTH AND NORTHWEST. SOME DEGREE OF DEBRIS CLOUDS
MAY WORK ACROSS THE AREA ON WED...BUT MODERATE 0Z MODELS AND 21Z
FORECAST MODERATE INSTABILITY AND MORE IN THE WAY OF SHEAR AS
COMPARED TO TODAY. THIS SHOULD LEAD TO STRENGTHENING OF CONVECTION AS
IT MOVES INTO EASTERN KY AND PROBABLY AN UPTICK IN COVERAGE AS WELL.
ONE OR MORE LINES OF STORMS...POSSIBLY STRONG TO LOCALLY SEVERE
SHOULD WORK ACROSS THE REGION. GUSTY WINDS WOULD APPEAR TO BE THE
PRIMARY THREAT WITH STORMS ON WED...THOUGH SOME SMALL TO MARGINALLY
SEVERE HAIL COULD OCCUR AS WELL AS LOCALLY HEAVY RAIN. LIKELY POPS
WERE CONTINUED FOR WEDNESDAY. ONCE AGAIN TIMING OF ARRIVAL OF DEBRIS
CLOUDS AND CONVECTIVE DEVELOPMENT WILL DETERMINE MAX T ON WED...BUT
EASTERN LOCATIONS SHOULD SEE THIS OCCUR THE LATEST AND SHOULD AVERAGE
WARMER THAN MORE CENTRAL AND WESTERN LOCATIONS.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 415 AM EDT TUE MAY 21 2013
THE MODELS REMAIN IN GOOD AGREEMENT WITH A BLOCKY UPPER LEVEL PATTERN
TO TAKE SHAPE ACROSS THE CONUS INTO EARLY NEXT WEEK...ALTHOUGH
DETAILS BECOME MORE MURKY BY THIS WEEKEND...WITH SOME DISAGREEMENT
WITH THE SMALLER SCALE FEATURES. AS SUCH...GENERALLY RELIED ON A
BLEND OF THE GUIDANCE.
A DEEP UPPER LEVEL TROUGH WILL SWING THROUGH THE OHIO VALLEY WEDNESDAY
NIGHT INTO THURSDAY...KEEPING GOOD CHANCE TO LIKELY POPS THREATENING
EASTERN KENTUCKY. THERE HAS BEEN A TREND OF A QUICKER EXIT WITH THIS
FEATURE. INSTABILITY WILL WANE QUICKLY BY LATE IN THE DAY ON
THURSDAY...SO REMOVED THUNDER CHANCES FOR THURSDAY NIGHT.
COOL HIGH PRESSURE WILL THEN BRING DRY CONDITIONS TO CONCLUDE THE
WORK WEEK. THIS WEEKEND...THE ECMWF AND GFS DIFFER QUITE A BIT WITH
THE TIMING AND EVOLUTION OF THE NEXT SYSTEM TO AFFECT THE AREA. THE
ECMWF IS PRETTY TRANSIENT WITH THE HIGH PRESSURE...AND ALLOWS A WARM
FRONT TO MOVE IN QUICKLY BY EARLY SATURDAY. THIS BOUNDARY THEN STALLS
ACROSS THE SOUTHERN HALF OF THE AREA...WITH OCCASIONAL SHORT WAVE
TROUGHS TRAVERSING THE NORTHWEST FLOW ALOFT. THE GFS IS MUCH SLOWER
HERE...AND KEEPS THE SURFACE BOUNDARY SHUNTED MORE TO THE NORTH.
GIVEN THE UNCERTAINTY...DID ALLOW FOR A RETURN OF SLIGHT TO CHANCE
POPS...ALTHOUGH NOT AS AGGRESSIVE AS THE ECMWF.
TEMPERATURES WILL GENERALLY AVERAGE A LITTLE BELOW NORMAL THROUGH
THE PERIOD...WITH FRIDAY BEING THE COOLEST DAY...AS HIGHS WILL
RETREAT TO THE 60S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 205 AM EDT TUE MAY 21 2013
MOSTLY CLEAR SKIES AND DEWPOINTS IN THE 60S HAVE ALREADY LED TO FOG
DEVELOPMENT IN THE VALLEYS AND PER OBS THIS MAY BE DENSE IS SOME
LOCATIONS IN THE BIG SANDY/TUG VALLEY REGION ATTM. KI35...K22 AND
KPBX SHOULD EXPERIENCE SOME OF THE LOWER VIS THROUGH 13Z.
HOWEVER...GUIDANCE ONLY TAKES LOZ AND SME DOWN TO MVFR AROUND 9Z.
EXPECT SHOWERS AND THUNDERSTORMS TO DEVELOP 16Z AND AFTER...POSSIBLY
SOONER AS SOME MODEL GUIDANCE BRINGS AND OUTFLOW BOUNDARY INTO THE
AREA BEFORE 16Z. WE HAVE CONTINUED WITH SOME VCTS AND CB FOR THIS IN
THE TAFS. WINDS THROUGH THE NIGHT WILL BE LIGHT AND VARIABLE...PICKING
UP FROM THE SOUTHWEST WITH SPEEDS UP TO 10 KTS POSSIBLE AFTER 13Z.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JP
LONG TERM...GEOGERIAN
AVIATION...JP
THE EXTENDED FORECAST DISCUSSION WILL BE ISSUED SHORTLY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 205 AM EDT TUE MAY 21 2013
MOSTLY CLEAR SKIES AND DEWPOINTS IN THE 60S HAVE ALREADY LED TO FOG
DEVELOPMENT IN THE VALLEYS AND PER OBS THIS MAY BE DENSE IS SOME
LOCATIONS IN THE BIG SANDY/TUG VALLEY REGION ATTM. KI35...K22 AND
KPBX SHOULD EXPERIENCE SOME OF THE LOWER VIS THROUGH 13Z.
HOWEVER...GUIDANCE ONLY TAKES LOZ AND SME DOWN TO MVFR AROUND 9Z.
EXPECT SHOWERS AND THUNDERSTORMS TO DEVELOP 16Z AND AFTER...POSSIBLY
SOONER AS SOME MODEL GUIDANCE BRINGS AND OUTFLOW BOUNDARY INTO THE
AREA BEFORE 16Z. WE HAVE CONTINUED WITH SOME VCTS AND CB FOR THIS IN
THE TAFS. WINDS THROUGH THE NIGHT WILL BE LIGHT AND VARIABLE...PICKING
UP FROM THE SOUTHWEST WITH SPEEDS UP TO 10 KTS POSSIBLE AFTER 13Z.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JP
LONG TERM...GEOGERIAN
AVIATION...JP
AREA FORECAST DISCUSSION
NWS CARIBOU ME
645 PM EDT TUE MAY 21 2013
.SYNOPSIS...
A FRONTAL BOUNDARY WILL REMAIN ALONG THE SOUTHERN PART OF OUR
REGION THROUGH MID WEEK. SMALL WAVES OF LOW PRESSURE WILL TRACK
ALONG THIS BOUNDARY TODAY AND WEDNESDAY. A LARGER STORM SYSTEM
FROM THE MIDWEST WILL TRACK TO OUR WEST ON THURSDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
645 PM UPDATE: ADJUSTED THE POPS TO ADVERTISE RAIN COMING INTO THE
WRN AREAS EARLIER THAN PREVIOUSLY FCST USING THE LATEST RADAR AND
HRRR. RAFL AFTER MIDNIGHT IN THE WEST-CENTRAL AREAS COULD BE HEAVY
AT TIMES AS RUC SHOWS NICE 5OKT JETLET AT 700 MBS OVERRUNNING THE
WARM FRONT. DECENT LLVL CONVERGENCE IN PLACE AS WELL. THEREFORE,
QPF WAS ADJUSTED USING THE LATEST NERFC GRIDS WHICH SHOWS UP TO
.75" FROM 06-12Z WEDNESDAY IN THE AFOREMENTIONED AREAS. TWEAKED
TEMPERATURES USING THE LATEST LAMP WHICH POINTS TO TEMPERATURES
WARMER THAN PREVIOUSLY FCST.
THE FA WILL ENJOY A BRIEF BREAK IN THE ACTION ERLY THIS EVE
BEFORE CLDNSS FROM ANOTHER S/WV...OLD CNVCTV COMPLEX MOVE W TO E
INTO THE FA DURG THE OVRNGT HRS AS A SFC WARM FRONT REMAINS
STATIONARY OVR THE GULF OF ME. BLENDED 6 HRLY RNFL AMOUNTS LOOK TO
BE MORE SIG AND WIDESPREAD THAN THE AREA OF SHWRS THAT CROSSED THE
REGION EARLIER TDY. IN ADDITION...THERE MAY BE HEAVIER DOWNPOURS
AS MORE CNVCTV ELEMENTS MOVE INTO E CNTRL AND DOWNEAST PTNS OF THE
FA WITH A WEAK ELEVATED CAPE ENVIRONMENT. THIS IDEA IS SUPPORTED
BY CURRENT LGTNG STRIKES ON THE S SIDE OF THE COMPLEX AS IT MOVES
E THRU ERN ONT TOWARD SW QB...SO WE DID INCLUDE ISOLD TSTMS VERY
LATE TNGT OVR CNTRL AND DOWNEAST AREAS. WITH THIS IN MIND...SOME
LOCATIONS OVR THESE PTNS OF THE FA COULD RECEIVE ARND AN INCH OR
EVEN A LITTLE MORE OF TOTAL QPF...WITH ARND A HLF INCH OR SO OVR
THE N...ENOUGH TO JUSTIFY NEAR 100 PERCENT POPS FOR VIRTUALLY ALL
OF THE FA BY WED MORN. LASTLY...WITH LOW TO MID LVL WARM ADVCN
WHICH WILL INCLUDE A MARINE COMPONENT OF AIRFLOW WILL RESULT IN
PATCHY FOG ACROSS THE N VERY LATE TNGT AND AREAS OF FOG S WHICH
WILL LIKELY CARRY OVER WELL INTO THE MORN HRS.
MOST OF THE STEADY RN SHOULD TAPER OFF TO LIGHTER SHWRS WED AFTN
AS THE S/WV MOVES E OF THE FA. LOW TEMPS WILL BE MILD AGAIN AS
CLDNSS...RNFL AND FOG LATE TNGT KEEP TEMPS FROM FALLING MUCH.
HI TEMPS WED WILL BE MUCH SUPPRESSED DUE TO LLVL DAMMING OF RAIN
COOLED AIR HANGING IN ACROSS THE FA THRU THE DAY.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AN UPPER LEVEL TROF ACROSS THE WESTERN GREAT LAKES AT THE START OF
THE PERIOD WILL SLOWLY MIGRATE EAST WEDNESDAY NIGHT THROUGH
THURSDAY. MEANWHILE AT THE SURFACE...LOW PRESSURE WILL TRACK
NORTHEAST ACROSS THE GREAT LAKES AND THROUGH QUEBEC...PASSING TO
NORTH OF THE STATE LATE THURSDAY. A COLD FRONT ASSOCIATED WITH THIS
SYSTEM WILL SLOWLY APPROACH FROM THE WEST LATER THURSDAY. THE FRONT
WILL SLOW DOWN AS IT BECOMES PARALLEL TO THE UPPER FLOW WITH A BROAD
SOUTHWEST FLOW IN PLACE.
A CHANCE OF SHOWERS WILL EXIST WEDNESDAY NIGHT AS A WARM FRONT LIFTS
NORTH ACROSS THE REGION. THE CHANCE OF SHOWERS WILL INCREASE DURING
THE DAY THURSDAY IN ADVANCE OF THE SLOW MOVING COLD FRONT
APPROACHING FROM THE WEST. THERE WILL ALSO BE THE CHANCE FOR
THUNDERSTORMS DURING THURSDAY AFTERNOON ESPECIALLY ACROSS WESTERN
AREAS WHERE SB CAPES INCREASE TO 500-1000 J/KG PER GFS. THERE IS
SOME 0-6KM SHEAR AS WELL SO POTENTIAL IS THERE FOR SOME ORGANIZED
THUNDERSTORMS TO DEVELOP. OF COURSE...THIS WILL BE DEPENDENT ON JUST
HOW MUCH INSTABILITY DEVELOPS IN ADVANCE OF THE FRONT. THINKING WE
WILL SOME BREAKS OF SUNSHINE ACROSS WESTERN AREAS AWAY FROM THE
COAST AS LOW LEVEL FLOW BECOMES SOMEWHAT MORE SOUTHWEST. FOR
NOW...HAVE CONFINED MENTION OF THUNDER TO WESTERN AND NORTHERN
AREAS THURSDAY WITH MARINE INFLUENCE KEEPING THINGS MORE STABLE
DOWNEAST. WITH THE POTENTIAL FOR BREAKS ON THURSDAY AND 925 MB
TEMPERATURES AROUND +17C HAVE HAVE LEANED WITH WARMER MAV NOS FOR
MAXS THURSDAY.
SHOWERY TYPE WEATHER AND PERHAPS SOME LINGERING THUNDER CAN BE
EXPECTED INTO THURSDAY EVENING BEFORE TRANSITIONING TO A MORE STEADY
RAIN THURSDAY NIGHT IN RESPONSE TO AN AREA OF LOW PRESSURE
DEVELOPING TO OUR SOUTH ALONG THE SLOW MOVING FRONTAL BOUNDARY. A
STEAD RAIN IS EXPECTED TO CONTINUE ON FRIDAY AS LOW PRESSURE MOVES
NORTHEAST ALONG THE NEARLY STATIONARY FRONTAL BOUNDARY ACROSS THE
AREA. LOOK LIKE MOST AREAS WILL SEE ANYWHERE FROM A QUARTER TO HALF
AN INCH OF RAINFALL ON FRIDAY. BLENDED SREF/GFS FOR RAINFALL
AMOUNTS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
DAMP AND UNSETTLED WEATHER PTRN LOOKS TO CONT INTO THE LONGER
TERM... LONG RANGE GUIDANCE IN REASONABLE AGREEMENT W/ THE OPNL 12Z
GFS AND 00Z ECMWF SHOWING A NRLY STALLED FRONTAL BNDRY OVR EXTRA
SERN MAINE AT 00Z SAT. BOTH MODELS ADVERTISE BROAD AREA OF LOW
PRES FROM S OF SRN NEW ENGLAND UP INTO NB. BY 12Z SAT THE GFS HAS
DVLP A FAIRLY SIGNIFICANT CLOSED SFC LOW PRES SYSTEM NR CAPE COD
WHILE THE ECMWF IS FURTHER NEWRD W/ THIS LOW OVR WRN NS... BY 00Z
SUN...THE GFS HAS MOVD THIS DEEPENING SYSTEM NEWRD INTO SERN MAINE
WHILE THE ECMWF HAS THE SYSTEM OVR XTRM NERN NB. THEREAFTER THE
GFS WRAPS THIS LOW INTO NRN MAINE WHILE THE ECMWF LIFTS IT NEWRD
TO THE MOUTH OF THE ST LAWRENCE BY 12Z SUN. DESPITE THE 12
TIMING DIFFS...BOTH MODELS SUGGEST A POTENTIALLY SIGNIFICANT QPF
EVENT FOR THE PD LATER FRI NGT INTO SAT NGT W/ CHILLY AND
UNSETTLED CONDS PERSISTING THRU SUN.
STILL BRISK AND CHILLY INTO MON W/ A CONTG CHC OF SOME SHOWERS
SPCLY N AND W THEN APPEARS SOME DRIER AND MILDER AIR MAY FINALLY
WORK INTO THE FA BY TUE. ATTM...NOT THE BEST LOOKING MEMORIAL DAY
WEEKEND WX WISE FOR OUR REGION...
WILL CARRY LIKELY TO CAT POPS FRI NGT INTO SAT NGT W/ THE HIGHEST
POPS E AND SE. PLAYED TEMPS ON THE COOL SIDE USING A CONS ALL
BLEND...
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
NEAR TERM: VFR NRN TAF SITES THIS EVENING WHILE DOWNEAST SITES
HOLD IFR OR IMPROVE TO MVFR. ALL SITES THEN LOWERING TO IFR TO
LIFR LATE TNGT INTO ERLY WED MORN WITH ANOTHER ROUND OF LOW CLDNSS
SHWRS AND PATCHY TO AREAS OF FOG. LIFR CONDITIONS WED MORN ONLY
IMPROVE TO IFR WED AFTN AS STEADY MORN RN AND FOG TAPERS TO AFTN
SHWRS.
SHORT TERM: MVFR/IFR CONDITIONS ARE EXPECTED WEDNESDAY NIGHT AND
INTO THURSDAY MORNING IN LOW CLOUDS AND SHOWERS. CONDITIONS
SHOULD IMPROVE TO MVFR/VFR LATER THURSDAY MORNING INTO THURSDAY
AFTERNOON. SHOWERS ARE EXPECTED TO INCREASE ACROSS THE REGION
LATER THURSDAY AFTERNOON AND COULD EVEN SEE SOME SCT TSRA NORTHERN
TERMINALS THURSDAY AFTERNOON. MVFR/IFR CAN BE EXPECTED ON FRIDAY
IN STEADY RAIN.
&&
.MARINE...
NEAR TERM: NO HDLNS XPCTD OVRNGT THRU WED. WV HTS WILL HAVE SOME
SWELL COMPONENT OVR THE OUTER WATERS...REACHING UP TO 4 FT AT TMS.
WE USED A BLEND OF WW3 AND SWAN GFS...SMOOTHED 10 TMS OVR IN THE
VCNTY OF THE COAST TO LOWER WV HTS FOR THE INNER BAY/HARBOR MZ.
SHORT TERM: WINDS/SEAS WILL REMAIN BELOW SMALL CRAFT ADVISORY LEVELS
WEDNESDAY NIGHT. WINDS/SEAS WILL INCREASE THURSDAY AND CONTINUE
TO INCREASE TO SMALL CRAFT ADVISORY LEVELS THURSDAY NIGHT AND
FRIDAY. AREAS OF FOG WILL LIKELY REDUCE VISIBILITY TO 1 TO 3 NM
ESPECIALLY THURSDAY NIGHT AND ON FRIDAY.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...HEWITT/VJN
SHORT TERM...DUDA
LONG TERM...KHW
AVIATION...HEWITT/VJN/DUDA
MARINE...HEWITT/VJN/DUDA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1202 AM EDT THU MAY 23 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 353 PM EDT WED MAY 22 2013
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SLUGGISH UPR LO
OVER THE UPR MS RIVER VALLEY BTWN RDG OFF THE SE CONUS AND ANOTHER
RDG AXIS OVER THE ROCKIES. BAND OF -SHRA STRETCHING FM NE MN INTO
THE WRN CWA UNDER BAND OF H85-7 FGEN TO THE NE OF THE CLOSED LO IS
HOLDING FIRM EVEN THOUGH LLVL DRY AIR IS SURGING INTO NE MN/WRN LK
SUP IN STEADY NE FLOW BTWN HI PRES OVER NRN MANITOBA AND SFC LO PRES
IN THE LOWER LKS. ANOTHER LARGER AREA OF SHRA/ISOLD TS OVER THE SE
HALF OF WI/S HALF OF LK MI IS EXPANDING TO THE N AS SHRTWV OVER
IL/LEFT EXIT REGION OF SUPPORTING H3 JET MAX IS MOVING N OF THE
CLOSED LO. OTRW...LO CLDS HAVE BEEN QUITE PERSISTENT OVER UPR MI
WITH CHILLY NE WIND OFF LK SUP. SOME FOG HAS PERSISTED AS WELL NEAR
LK SUP E OF THE KEWEENAW...WHERE THE LLVL DRY AIR HAS NOT YET
ARRIVED.
MAIN FCST CONCERNS IN THE SHORT TERM INVOLVE HOW DRIER AIR ARRIVING
FM THE N WL IMPACT POPS ASSOCIATED WITH BAND OF FGEN OVER THE WRN
ZNS AND AREA OF SHRA MOVING N TOWARD THE SE COUNTIES.
TNGT...UPR LO NOW OVER SE MN IS PROGGED TO DRIFT ESE...AND NAM SHOWS
BAND OF H85-7 FGEN/H85-5 QVECTOR CNVGC FOLLOWING THIS FEATURE SEWD
ACRS MAINLY THE W HALF OF THE CWA. AT THE SAME TIME...H7-3 QVECTOR
CNVGC/UPR DVGC IN LEFT EXIT AHEAD OF SHRTWV/SUPPORTING UPR JET
LIFTING NNEWD WL IMPACT MAINLY THE SE COUNTIES. LOOKS LIKE THESE
DYNAMICS MAY INTERACT FOR A TIME LATE THIS AFTN/EARLY EVNG OVER THE
SE ZNS. SO HIER POPS IN THIS AREA AT THAT TIME SEEM APPROPRIATE. AT
THE SAME TIME...DRIER AIR SURGING INTO THE NW CWA UNDER STRONGER NNE
FLOW WL END ANY LINGERING PCPN AS FGEN AXIS SHIFTS TO THE SE. THE
PCPN WL END EVEN OVER THE SE ZNS AFT 06Z FOLLOWING DEPARTURE OF
SHRTWV/ACCOMPANYING DYNAMICS AND ARRIVAL OF DRIER LLVL AIR. THE
ARRIVAL OF THE DRIER LLVL AIR AND EXIT OF THE DYNAMICS WL ALLOW FOR
SOME CLRG...BUT THE UPSLOPE NNE FLOW MAY SLOW THE PROCESS OVER THE
HIER TERRAIN NEAR LK SUP.
THU...HI PRES IS FCST TO BLD INTO THE UPR LKS...RESULTING IN DRY WX.
ALTHOUGH LINGERING H85 THERMAL TROF WITH TEMPS ARND 0C THRU 00Z
WOULD INDICATE QUITE A BIT OF DIURNAL CU/SC AT THIS TIME OF YEAR
OVER LAND...DRYNESS OF INCOMING AIRMASS AS WELL AS LLVL ACYC/
DIFFLUENT FLOW WL RESULT IN MOCLR SKIES. IF THERE IS ANY UPSLOPE SC
OVER THE HIER TERRAIN NEAR LK SUP...THIS CLD WL MIX OUT EARLY. THE
FCST H85 TEMPS AND MIXING TO H8-85 ON NAM FCST SDNGS YIELDS HI TEMPS
TOPPING OUT IN THE 50S OVER THE INTERIOR. BUT STIFF NNE WIND OFF LK
SUP WL CAUSE TEMPS TO HOLD IN THE 40S NEAR THE BIG LAKE. THESE
STRONGER NE WINDS WL DIMINISH OVER THE W IN THE AFTN WITH THE APRCH
OF THE HI CENTER/WEAKENING PRES GRADIENT.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 353 PM EDT WED MAY 22 2013
SLOW MOVING AND RATHER STABLE UPPER AIR PATTERN EXPECTED THROUGH THE
ENTIRE LENGTH OF THE LONG TERM. INITIALLY LATE THIS WEEK...THERE IS
A TROUGH OVER PACIFIC NORTHWEST WITH RIDGING OVER CENTRAL CONUS...
AND TROUGHING OVER MUCH OF EASTERN CANADA ACROSS THE GREAT LAKES.
EXPECT BELOW NORMAL TEMPERATURES TO PREVAIL THROUGH THE HOLIDAY
WEEKEND AS THE TROUGH ONLY SLOWLY MOVES TO THE EAST. EVENTUALLY...
WARMER TEMPERATURES ARE EXPECTED BY MIDDLE OF NEXT WEEK WHEN RIDGING
EXPANDS FROM PLAINS ACROSS THE GREAT LAKES. AFTER AN UNSETTLED AND
WET WEEK THAT HAS OCCURRED OVER THE UPPER GREAT LAKES...HUDSON BAY
HIGH PRESSURE RIDGING ACROSS THE GREAT LAKES SHOULD BRING A
PROLONGED PERIOD OF DRY WEATHER INTO NEXT WEEK. CERTAINLY POSSIBLE
THIS DRY WEATHER STRETCH MAY EVEN PERSIST INTO THE MIDDLE OF NEXT
WEEK. WARM FRONT FORMING TO THE SOUTH AND WEST OF UPPER MICHIGAN
WILL RESULT IN SOME SMALLER CHANCES OF PRECIP BY NEXT WEDNESDAY...
BUT GIVEN THE VERY DRY AIRMASS IN PLACE...GREATEST CHANCE OF SHOWERS
AND STORMS WILL LIKELY STAY TO WEST OF UPPER LAKES CLOSER TO AXIS OF
HIGHER H85-H7 MOISTURE AND INSTABILITY.
GUSTY WINDS AROUND ON THURSDAY DIMINISH BY THE WEEKEND AS HIGH
PRESSURE BUILDING SOUTH OUT OF NORTHERN ONTARIO BECOMES MORE
ESTABLISHED. LIGHTER WINDS ON THURSDAY NIGHT AND VERY DRY AIRMASS
OVERHEAD DUE TO STRONG MIXING EARLIER IN THE DAY WILL SUPPORT MIN
TEMPS DROPPING TO AROUND 20 DEGREES INTERIOR WEST AND IN THE 20S TO
LOWER 30S ELSEWHERE. EXPECT WIDESPREAD FROST FOR MANY AREAS ON
THURSDAY NIGHT. WE DO NOT OFFICIALLY BEGIN THE FROST AND FREEZE
HEADLINES UNTIL MEMORIAL DAY BUT WILL CONTINUE TO INCLUDE MENTION IN
THE GRIDS. WITH STRONG HIGH PRESSURE OVER THE AREA...NEAR 1030MB...
LAKE BREEZES MAY GET GUSTY AT TIMES THIS WEEKEND. AFTER A COOLER DAY
ALL AREAS ON FRIDAY...COOLING WILL BECOME MORE OF A LAKESIDE FEATURE
THROUGH THE WEEKEND AS INLAND AREAS RISE INTO THE 60S.
SEEMS THERE IS A SLIM CHANCE OF LGT RAIN/SPRINKLES OVER FAR WEST
CWA LATE FRIDAY NIGHT INTO SATURDAY MORNING. 12Z NAM SOUNDINGS SHOW
MOISTURE IN MID LEVELS ENHANCED BY RIGHT ENTRANCE REGION OF
DEPARTING JET STREAK OVER ONTARIO BUILDING DOWN ENOUGH ALONG WITH
SUFFICIENT UVM TO RESULT IN BAND OF LGT SHRA MAKING IT INTO IWD
06Z-12Z ON SATURDAY. ECMWF/GFS SHOW SOME MID LEVEL MOISTURE BUT HAVE
QPF STAYING OUT OF CWA. 12Z ECMWF DOES SHOW A BIT NOW THOUGH. NAM
SEEMS TOO AGGRESSIVE WITH EASTWARD PUSH OF LGT PRECIP SO WILL NOT
PUT A MENTION IN YET. INCREASE IN CLOUDS OVERNIGHT WILL IMPACT MIN
TEMPS AND MAY RESTRICT POTENTIAL FOR FROST...AT LEAST IN THE
INTERIOR WEST CWA. ELSEWHERE...TEMPS DROPPING INTO THE UPPER 20S OR
NEAR 30 DEGREES WILL SUPPORT MORE FROST...ESPECIALLY INLAND FROM THE
LAKES. IF THERE ARE BKN CLOUDS WEST...THEY SHOULD DISSIPATE BY
SATURDAY EVENING RESULTING IN ANOTHER COOL NIGHT WITH SOME FROST
INLAND FROM THE GREAT LAKES SHORES.
DUE TO COOL AND DAMP WEATHER AND MODERATE RAIN AMOUNTS IN SOME AREAS
/HAD REPORT TODAY OF OVER 4 INCHES TO WEST OF ONTONAGON/...FIRE
WEATHER ISSUES ARE TAKING A BRIEF HIATUS. EVENTUALLY DUE TO ALMOST A
WEEK OF DRYING...INCREASING SOUTH/SOUTHWEST WINDS...AND WARMER
TEMPERATURES INTO THE 70S EARLY-MID NEXT WEEK MAY SEE INCREASING
FIRE WEATHER CONCERNS FOR AREAS THAT HAVE NOT EXPERIENCED A FULL
GREEN UP AND/OR SEEN A LOT OF RAIN OVER THE LAST FEW DAYS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1201 AM EDT THU MAY 23 2013
A STEADY NNE WIND BETWEEN HIGH PRES IN S CENTRAL CANADA AND LOW PRES
OVER THE LOWER GREAT LAKES WILL ADVECT MUCH DRIER LOW LEVEL AIR OVER
UPPER MI. THE STRONG UPSLOPE WIND COMPONENT MAY MAINTAIN SCT-BKN
CLOUDS NEAR THE MVFR THRESHOLD TIL LATE TONIGHT. UNDER A TIGHTENING
PRES GRADIENT...EXPECT GUSTY NNE WINDS AT CMX/SAW THROUGH THU.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 353 PM EDT WED MAY 22 2013
EXPECT INCREASING NE WINDS UP TO 25-30 KTS UNDER SHARPENING PRES
GRADIENT IN ADVANCE OF HI PRES BUILDING TOWARD LAKE SUP THRU
TONIGHT. THIS STRENGTHENING FLOW WILL ADVECT DRIER AIR OVER THE
LAKE...SO LINGERING FOG SHOULD DISSIPATE THIS EVENING. BASED ON
CURRENT VISIBILITY REPORTS/WEBCAM IMAGERY NEAR THE LAKE...OPTED TO
CANX GOING DENSE FOG ADVISORIES THAT WERE SET TO EXPIRE AT 21Z.
CLOSER APPROACH OF HI PRES/WEAKER PRES GRADIENT WILL RESULT IN
SLOWLY DIMINISHING WINDS W TO E ON THU. AS HIGH PRESSURE CONTINUES TO
SPREAD ACROSS THE UPPER GREAT LAKES THROUGH THE WEEKEND...EXPECT
WINDS LESS THAN 20 KTS ON LAKE SUPERIOR. LIGHTER WINDS WILL CONTINUE
INTO EARLY NEXT WEEK.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...JLA
AVIATION...JLB
MARINE...KC/JLA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
801 PM EDT WED MAY 22 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 353 PM EDT WED MAY 22 2013
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SLUGGISH UPR LO
OVER THE UPR MS RIVER VALLEY BTWN RDG OFF THE SE CONUS AND ANOTHER
RDG AXIS OVER THE ROCKIES. BAND OF -SHRA STRETCHING FM NE MN INTO
THE WRN CWA UNDER BAND OF H85-7 FGEN TO THE NE OF THE CLOSED LO IS
HOLDING FIRM EVEN THOUGH LLVL DRY AIR IS SURGING INTO NE MN/WRN LK
SUP IN STEADY NE FLOW BTWN HI PRES OVER NRN MANITOBA AND SFC LO PRES
IN THE LOWER LKS. ANOTHER LARGER AREA OF SHRA/ISOLD TS OVER THE SE
HALF OF WI/S HALF OF LK MI IS EXPANDING TO THE N AS SHRTWV OVER
IL/LEFT EXIT REGION OF SUPPORTING H3 JET MAX IS MOVING N OF THE
CLOSED LO. OTRW...LO CLDS HAVE BEEN QUITE PERSISTENT OVER UPR MI
WITH CHILLY NE WIND OFF LK SUP. SOME FOG HAS PERSISTED AS WELL NEAR
LK SUP E OF THE KEWEENAW...WHERE THE LLVL DRY AIR HAS NOT YET
ARRIVED.
MAIN FCST CONCERNS IN THE SHORT TERM INVOLVE HOW DRIER AIR ARRIVING
FM THE N WL IMPACT POPS ASSOCIATED WITH BAND OF FGEN OVER THE WRN
ZNS AND AREA OF SHRA MOVING N TOWARD THE SE COUNTIES.
TNGT...UPR LO NOW OVER SE MN IS PROGGED TO DRIFT ESE...AND NAM SHOWS
BAND OF H85-7 FGEN/H85-5 QVECTOR CNVGC FOLLOWING THIS FEATURE SEWD
ACRS MAINLY THE W HALF OF THE CWA. AT THE SAME TIME...H7-3 QVECTOR
CNVGC/UPR DVGC IN LEFT EXIT AHEAD OF SHRTWV/SUPPORTING UPR JET
LIFTING NNEWD WL IMPACT MAINLY THE SE COUNTIES. LOOKS LIKE THESE
DYNAMICS MAY INTERACT FOR A TIME LATE THIS AFTN/EARLY EVNG OVER THE
SE ZNS. SO HIER POPS IN THIS AREA AT THAT TIME SEEM APPROPRIATE. AT
THE SAME TIME...DRIER AIR SURGING INTO THE NW CWA UNDER STRONGER NNE
FLOW WL END ANY LINGERING PCPN AS FGEN AXIS SHIFTS TO THE SE. THE
PCPN WL END EVEN OVER THE SE ZNS AFT 06Z FOLLOWING DEPARTURE OF
SHRTWV/ACCOMPANYING DYNAMICS AND ARRIVAL OF DRIER LLVL AIR. THE
ARRIVAL OF THE DRIER LLVL AIR AND EXIT OF THE DYNAMICS WL ALLOW FOR
SOME CLRG...BUT THE UPSLOPE NNE FLOW MAY SLOW THE PROCESS OVER THE
HIER TERRAIN NEAR LK SUP.
THU...HI PRES IS FCST TO BLD INTO THE UPR LKS...RESULTING IN DRY WX.
ALTHOUGH LINGERING H85 THERMAL TROF WITH TEMPS ARND 0C THRU 00Z
WOULD INDICATE QUITE A BIT OF DIURNAL CU/SC AT THIS TIME OF YEAR
OVER LAND...DRYNESS OF INCOMING AIRMASS AS WELL AS LLVL ACYC/
DIFFLUENT FLOW WL RESULT IN MOCLR SKIES. IF THERE IS ANY UPSLOPE SC
OVER THE HIER TERRAIN NEAR LK SUP...THIS CLD WL MIX OUT EARLY. THE
FCST H85 TEMPS AND MIXING TO H8-85 ON NAM FCST SDNGS YIELDS HI TEMPS
TOPPING OUT IN THE 50S OVER THE INTERIOR. BUT STIFF NNE WIND OFF LK
SUP WL CAUSE TEMPS TO HOLD IN THE 40S NEAR THE BIG LAKE. THESE
STRONGER NE WINDS WL DIMINISH OVER THE W IN THE AFTN WITH THE APRCH
OF THE HI CENTER/WEAKENING PRES GRADIENT.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 353 PM EDT WED MAY 22 2013
SLOW MOVING AND RATHER STABLE UPPER AIR PATTERN EXPECTED THROUGH THE
ENTIRE LENGTH OF THE LONG TERM. INITIALLY LATE THIS WEEK...THERE IS
A TROUGH OVER PACIFIC NORTHWEST WITH RIDGING OVER CENTRAL CONUS...
AND TROUGHING OVER MUCH OF EASTERN CANADA ACROSS THE GREAT LAKES.
EXPECT BELOW NORMAL TEMPERATURES TO PREVAIL THROUGH THE HOLIDAY
WEEKEND AS THE TROUGH ONLY SLOWLY MOVES TO THE EAST. EVENTUALLY...
WARMER TEMPERATURES ARE EXPECTED BY MIDDLE OF NEXT WEEK WHEN RIDGING
EXPANDS FROM PLAINS ACROSS THE GREAT LAKES. AFTER AN UNSETTLED AND
WET WEEK THAT HAS OCCURRED OVER THE UPPER GREAT LAKES...HUDSON BAY
HIGH PRESSURE RIDGING ACROSS THE GREAT LAKES SHOULD BRING A
PROLONGED PERIOD OF DRY WEATHER INTO NEXT WEEK. CERTAINLY POSSIBLE
THIS DRY WEATHER STRETCH MAY EVEN PERSIST INTO THE MIDDLE OF NEXT
WEEK. WARM FRONT FORMING TO THE SOUTH AND WEST OF UPPER MICHIGAN
WILL RESULT IN SOME SMALLER CHANCES OF PRECIP BY NEXT WEDNESDAY...
BUT GIVEN THE VERY DRY AIRMASS IN PLACE...GREATEST CHANCE OF SHOWERS
AND STORMS WILL LIKELY STAY TO WEST OF UPPER LAKES CLOSER TO AXIS OF
HIGHER H85-H7 MOISTURE AND INSTABILITY.
GUSTY WINDS AROUND ON THURSDAY DIMINISH BY THE WEEKEND AS HIGH
PRESSURE BUILDING SOUTH OUT OF NORTHERN ONTARIO BECOMES MORE
ESTABLISHED. LIGHTER WINDS ON THURSDAY NIGHT AND VERY DRY AIRMASS
OVERHEAD DUE TO STRONG MIXING EARLIER IN THE DAY WILL SUPPORT MIN
TEMPS DROPPING TO AROUND 20 DEGREES INTERIOR WEST AND IN THE 20S TO
LOWER 30S ELSEWHERE. EXPECT WIDESPREAD FROST FOR MANY AREAS ON
THURSDAY NIGHT. WE DO NOT OFFICIALLY BEGIN THE FROST AND FREEZE
HEADLINES UNTIL MEMORIAL DAY BUT WILL CONTINUE TO INCLUDE MENTION IN
THE GRIDS. WITH STRONG HIGH PRESSURE OVER THE AREA...NEAR 1030MB...
LAKE BREEZES MAY GET GUSTY AT TIMES THIS WEEKEND. AFTER A COOLER DAY
ALL AREAS ON FRIDAY...COOLING WILL BECOME MORE OF A LAKESIDE FEATURE
THROUGH THE WEEKEND AS INLAND AREAS RISE INTO THE 60S.
SEEMS THERE IS A SLIM CHANCE OF LGT RAIN/SPRINKLES OVER FAR WEST
CWA LATE FRIDAY NIGHT INTO SATURDAY MORNING. 12Z NAM SOUNDINGS SHOW
MOISTURE IN MID LEVELS ENHANCED BY RIGHT ENTRANCE REGION OF
DEPARTING JET STREAK OVER ONTARIO BUILDING DOWN ENOUGH ALONG WITH
SUFFICIENT UVM TO RESULT IN BAND OF LGT SHRA MAKING IT INTO IWD
06Z-12Z ON SATURDAY. ECMWF/GFS SHOW SOME MID LEVEL MOISTURE BUT HAVE
QPF STAYING OUT OF CWA. 12Z ECMWF DOES SHOW A BIT NOW THOUGH. NAM
SEEMS TOO AGGRESSIVE WITH EASTWARD PUSH OF LGT PRECIP SO WILL NOT
PUT A MENTION IN YET. INCREASE IN CLOUDS OVERNIGHT WILL IMPACT MIN
TEMPS AND MAY RESTRICT POTENTIAL FOR FROST...AT LEAST IN THE
INTERIOR WEST CWA. ELSEWHERE...TEMPS DROPPING INTO THE UPPER 20S OR
NEAR 30 DEGREES WILL SUPPORT MORE FROST...ESPECIALLY INLAND FROM THE
LAKES. IF THERE ARE BKN CLOUDS WEST...THEY SHOULD DISSIPATE BY
SATURDAY EVENING RESULTING IN ANOTHER COOL NIGHT WITH SOME FROST
INLAND FROM THE GREAT LAKES SHORES.
DUE TO COOL AND DAMP WEATHER AND MODERATE RAIN AMOUNTS IN SOME AREAS
/HAD REPORT TODAY OF OVER 4 INCHES TO WEST OF ONTONAGON/...FIRE
WEATHER ISSUES ARE TAKING A BRIEF HIATUS. EVENTUALLY DUE TO ALMOST A
WEEK OF DRYING...INCREASING SOUTH/SOUTHWEST WINDS...AND WARMER
TEMPERATURES INTO THE 70S EARLY-MID NEXT WEEK MAY SEE INCREASING
FIRE WEATHER CONCERNS FOR AREAS THAT HAVE NOT EXPERIENCED A FULL
GREEN UP AND/OR SEEN A LOT OF RAIN OVER THE LAST FEW DAYS.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 748 PM EDT WED MAY 22 2013
AS A STEADY NNE WIND BTWN HIGH PRES IN SCENTRAL CANADA AND LOW PRES
OVER THE LOWER GREAT LAKES WILL ADVECT MUCH DRIER LOW LEVEL AIR OVER
UPPER MI. EXPECT IMRPVOING CONDITIONS TO EVENTUALLY SPREAD TOWARD
SAW BY LATE EVENING WHERE THE MORE SIGNIFICANT UPSLOPE WIND
COMPONENT WILL ALSO SLOW THE TREND TOWARD VFR. UNDER A TIGHTENING PRES
GRADIENT...EXPECT GUSTY NNE WINDS AT ALL 3 SITES TONIGHT THROUGH
THU.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 353 PM EDT WED MAY 22 2013
EXPECT INCREASING NE WINDS UP TO 25-30 KTS UNDER SHARPENING PRES
GRADIENT IN ADVANCE OF HI PRES BUILDING TOWARD LAKE SUP THRU
TONIGHT. THIS STRENGTHENING FLOW WILL ADVECT DRIER AIR OVER THE
LAKE...SO LINGERING FOG SHOULD DISSIPATE THIS EVENING. BASED ON
CURRENT VISIBILITY REPORTS/WEBCAM IMAGERY NEAR THE LAKE...OPTED TO
CANX GOING DENSE FOG ADVISORIES THAT WERE SET TO EXPIRE AT 21Z.
CLOSER APPROACH OF HI PRES/WEAKER PRES GRADIENT WILL RESULT IN
SLOWLY DIMINISHING WINDS W TO E ON THU. AS HIGH PRESSURE CONTINUES TO
SPREAD ACROSS THE UPPER GREAT LAKES THROUGH THE WEEKEND...EXPECT
WINDS LESS THAN 20 KTS ON LAKE SUPERIOR. LIGHTER WINDS WILL CONTINUE
INTO EARLY NEXT WEEK.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...JLA
AVIATION...JLB
MARINE...KC/JLA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
358 PM EDT TUE MAY 21 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 357 PM EDT TUE MAY 21 2013
12Z ROABS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SLOW MOVING UPR LO
OVER ERN SDAKOTA BTWN UPR RDG OVER SCENTRAL CANADA AND A RIDGE OFF
THE SE CONUS. BAND OF SHRA/SCT TS THAT IMPACTED THE CWA EARLIER HAS
LIFTED TO THE N ALONG WITH RESPONSIBLE SHRTWV...ALLOWING FOR MAINLY
DRY WX OVER UPR MI EARLY THIS AFTN. BUT SINCE THE CWA IS N OF SFC
WARM FNT IN WI...PLENTY OF LO CLDS LINGER. THERE IS ALSO SOME FOG...
MAINLY NEAR THE COOLER GREAT LKS. ANOTHER DISTURBANCE IS ROTATING N
THRU IOWA ARND THE CLOSED LO. THE APRCH OF THIS DISTURBANCE HAS
RESULTED IN SOME SHRA OVER CENTRAL WI WHERE BREAKS IN THE LO CLDS
ALONG AND S OF WARM FNT HAVE LIFTED SB CAPE 500-1000 J/KG PER SPC
MESOANALYSIS.
MAIN FCST CONCERNS IN THE SHORT TERM ARE SHRA/TS TRENDS ASSOCIATED
WITH SHRTWV IN IOWA AND THEN APRCH OF MAIN UPR LO.
LATE THIS AFTN/TNGT...SHORT RANGE MODELS ARE IN FAIRLY GOOD
AGREEMENT SHOWING SHRA NOW OVER CENTRAL WI DRIFTING ACRS THE WI
BORDER BY 21Z AND THEN CONTINUING TO THE NE. RUC FCST SDNGS MODIFIED
FOR TEMP/DEWPT OF 68/58 YIELDS SBCAPE UP TO 750 J/KG...SO ADDED
MENTION OF TS. RELATIVELY WEAK WINDS SFC-H5 AS WELL AS DEEP
MSTR/SKINNY CAPE WITH PERSISTENT LO CLDS LIMITING DIURNAL HEATING
INDICATE A LO RISK FOR ANY SVR TS...BUT ANY SHRA COULD RESULT IN
SOME HEAVY RA WITH FCST KINX AS HI AS THE UPR 30S. ONCE THE SHRA
MOVE FARTHER TO THE NE AND AWAY FM THE SFC HEATING AREA...ONE MIGHT
EXPECT THESE SHRA TO DIMINISH THRU THE NGT. BUT FCST AREA OF H85-7
FGEN N OF WARM FNT MIGHT ACT TO SUSTAIN THESE SHRA. WL GO WITH HI
CHC-LIKELY POPS THIS EVNG NEAR THE WI BORDER DIMINISHING TO CHCY
POPS TO THE NE. SINCE THE LLVL FLOW IS FCST TO BACK MORE TO THE NE
FOLLOWING THE PASSAGE OF THIS SHRA AREA...EXPECT COOLER LAKE
AIR/SOME FOG TO MOVE BACK INTO THE AREA OVERNGT.
WED...AS CLOSED LO TO THE W BEGINS TO SHIFT FASTER TO THE ESE TO SW
WI BY 00Z THU...AREA OF LARGER SCALE QVECTOR CNVGC WL IMPACT MAINLY
THE AREA NEAR THE WI BORDER BUT WEAKEN WITH TIME AS THE UPR CLO
BEGINS TO OPEN. BAND OF RA ACCOMPANYING AXIS OF SHARPER FGEN OVER
WRN LK SUP/THE WRN ZNS SHOULD THUS SHIFT SLOWLY TO THE SE THRU THE
DAY. ARRIVAL OF DRIER AIR FM THE NW TO THE SE OF EXPANDING HI PRES
OVER SCENTRAL CANADA MIGHT START TO DIMINISH THE PCPN OVER THE FAR W
LATER IN THE DAY. OTRW...LOWERED FCST HI TEMPS TO ACCOUNT FOR STEADY
NE WIND OFF LK SUP AND EXPECTED CLD COVER.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 357 PM EDT TUE MAY 21 2013
AFTER A WET START TO THE WEEK...THE LONG TERM PERIOD LOOKS TO BE
FAIRLY DRY AS CANADIAN HIGH PRESSURE SLIDES THROUGH THE UPPER GREAT
LAKES REGION.
FIRST...THE UPPER TROUGH THAT HAS BEEN INFLUENCING THE WEATHER FOR
THE START OF THE WORK WEEK WILL BE SITUATED OVER WISCONSIN AND IOWA
AND SHIFTING EAST THROUGH THE GREAT LAKES REGION ON WEDNESDAY
NIGHT. MEANWHILE...THE SURFACE LOW WILL BE LOCATED OVER LOWER
MICHIGAN AT 00Z THURSDAY AND BEGIN TO MOVE UP THE ST LAWRENCE
SEAWAY WEDNESDAY NIGHT INTO THURSDAY AS A SHORTWAVE INTENSIFIES THE
LOW. AS THIS OCCURS...HIGH PRESSURE ORIGINATING FROM NORTH CENTRAL
CANADA WILL BE MOVING A RIDGE INTO THE UPPER MISSISSIPPI VALLEY ON
WEDNESDAY NIGHT AND THE UPPER GREAT LAKES ON THURSDAY. WITH THE
UPPER TROUGH AND CLOSE PROXIMITY OF THE LOW...THERE WILL STILL BE
DEEPER MOISTURE AND 850-700MB Q-VECTOR CONVERGENCE OVER THE
SOUTHEAST HALF OF THE CWA. IN ADDITION...WITH THE INCREASING
NORTHERLY 850-700MB FLOW OVER THE AREA MODELS ARE CONSISTENT ON AN
AREA OF FGEN SETUP FROM IRONWOOD THROUGH EASTERN LAKE SUPERIOR AT
00Z THURSDAY. THEN AS THE LOW SHIFTS EAST...THE FGEN WILL SLIDE
SOUTHEAST THROUGH THE NIGHT AND LIKELY EXIT THE MOST IF NOT ALL OF
THE CWA BY 12Z THURSDAY. AT THIS POINT...THINKING THAT THE MOVEMENT
OF THE PRECIPITATION SHOULD KEEP AMOUNTS UNDER A QUARTER OF AN
INCH.
CANADIAN HIGH PRESSURE THEN BECOMES THE DOMINATING FEATURE FOR THE
REST OF THE PERIOD...AS THE AREA IS UNDER NORTHWEST FLOW ALOFT.
THIS DRY CANADIAN AIR AND COOLER NORTHERLY LOW LEVEL WINDS WILL
LEAD TO NICE BUT SLIGHTLY COOLER THAN NORMAL START TO THE MEMORIAL
DAY WEEKEND. THE STRONGEST NORTHERLY FLOW OFF LAKE SUPERIOR WILL BE
ON THURSDAY WITH THE CLOSER PROXIMITY OF THE EXITING LOW. THIS WILL
KEEP TEMPERATURES COOLER THAN MOST OF THE DAYS...WITH HIGHS IN THE
UPPER 40S NEAR LAKE SUPERIOR AND IN THE 50S INLAND. FRIDAY-SUNDAY
WILL BE DOMINATED BY LAKE BREEZES EACH DAY...WITH THE WARMEST
TEMPERATURES OVER THE INTERIOR LOCATIONS /60S/. THERE ARE HINTS OF A
COUPLE WEAK SHORTWAVES MOVING THROUGH THE NORTHWEST FLOW ALOFT
FRI-SUN...BUT WILL THE DRY AIR IN PLACE...WOULDN/T EXPECT MUCH FOR
PRECIPITATION CHANCES. UNDER THE HIGH PRESSURE RIDGE ON THURSDAY
NIGHT...EXPECT TO SEE SOME SUB FREEZING LOWS OVER THE INTERIOR
PORTIONS OF UPPER MICHIGAN. PWAT VALUES AROUND 40 PERCENT OF NORMAL
AND LIGHT WINDS WOULD BE FAVORABLE WELL BELOW NORMAL LOWS. MAV/MET
GUIDANCE PICKING UP ON THIS IDEA WITH LOWS BETWEEN 25-30 OVER THE
WEST AND THAT SEEMS FAIRLY REASONABLE. HAVE TRENDED THAT DIRECTION
AND LOWERED TEMPS OVER THE WEST AROUND 5 DEGREES. FROST/FREEZE
HEADLINES DON/T START UNTIL MEMORIAL DAY...SO THERE WON/T BE ANY
HEADLINES...BUT ANYONE THAT HAS PLANTED EARLY WILL NEED TO PREPARE
FOR A POTENTIAL FROST/FREEZE.
UPPER RIDGING THAT WILL BE NEARLY STATIONARY JUST EAST OF THE
NORTHERN ROCKIES DURING THIS PERIOD WILL BEGIN TO SHIFT EAST ON
SUNDAY NIGHT AS THE UPPER TROUGH OVER THE NEW ENGLAND STATES SHIFTS
EAST INTO THE ATLANTIC. THIS WILL START A GRADUAL WARMING TREND
TOWARDS MEMORIAL DAY AND INTO THE FIRST PART OF NEXT WEEK. IN
ADDITION...IT WILL ALSO BRING BETTER OPPORTUNITIES FOR SHORTWAVES
TO RIDE OVER THE RIDGE AND INTO THE AREA LATER MONDAY AND MORE
LIKELY TOWARDS TUESDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 126 PM EDT TUE MAY 21 2013
WITH SHALLOW COOL AIR DOME PERSISTING N OF SFC WARM FNT IN WI...
EXPECT LIFR CONDITIONS TO PREVAIL THIS FCST PERIOD. THE WORST
CONDITIONS WILL OCCUR WHERE/WHEN THE BACKING LLVL FLOW UPSLOPES.
VLIFR WX IS LIKELY TO PERSIST AT CMX INTO THIS EVNG BEFORE THE FLOW
BACKS TO A MORE NE DIRECTION AND WEAKENS THE UPSLOPE WIND COMPONENT
AT THAT SITE.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 357 PM EDT TUE MAY 21 2013
GIVEN WIDESPREAD AREA OF RA THAT IMPACTED MUCH OF LAKE SUP INTO THIS
MORNING...SOME RECENT SHIP OBS THAT INDICATED LO VISIBILITY...AND
SHALLOW COOL AIRMASS OVER THE LAKE...OPTED TO EXTENDED DENSE FOG
ADVY THRU TONIGHT. ARRIVAL OF DRIER AIR FROM THE NW ON WED WILL
SLOWLY DIMINISH THE FOG. OTHERWISE...NE WINDS UP TO 25 TO 30 KTS...
WITH SOME GALE FORCE GUSTS AT THE HIER PLATFORMS...WILL CONTINUE
STRONGEST OVER WESTERN LAKE SUP WHERE TERRAIN FUNNELING WILL ENHANCE
THE WIND SPEEDS.
GUSTY NORTHERLY WINDS ARE EXPECTED BEHIND THE LOW PRESSURE SYSTEM
ON WEDNESDAY NIGHT INTO THURSDAY...BUT LINGERING WARM AIR ALOFT
SHOULD KEEP WINDS IN 20-25KT RANGE. THEN...A HIGH PRESSURE RIDGE
BUILDING SOUTHEAST OVER THE UPPER GREAT LAKES FOR THURSDAY NIGHT
THROUGH THE WEEKEND WILL BRING LIGHT WINDS TO LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
DENSE FOG ADVISORY UNTIL 6 AM EDT /5 AM CDT/ WEDNESDAY FOR
LSZ162-243>249-263>267.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...SRF
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
315 PM EDT TUE MAY 21 2013
LATEST UPDATE...
AFTERNOON PACKAGE
.SYNOPSIS...
ISSUED AT 315 PM EDT TUE MAY 21 2013
AN AREA OF LOW PRESSURE WILL DEVELOP OVER SOUTHEAST MISSOURI THIS
EVENING AND MOVE THROUGH CENTRAL MICHIGAN ON WEDNESDAY. THE
DEVELOPING LOW CENTER WILL BRING SOAKING RAINS AND A FEW STRONG
THUNDERSTORMS TO THE AREA LATE TONIGHT AND WEDNESDAY. MUCH COOLER
AIR AND SHOWERS WILL WRAP IN FROM THE NORTHWEST AS THE LOW DEPARTS
ON THURSDAY. CANADIAN HIGH PRESSURE WILL BUILD OVER THE REGION
THURSDAY NIGHT AND PROVIDE COOL AND DRY WEATHER THROUGH THE HOLIDAY
WEEKEND. THERE WILL ALSO BE A GOOD CHANCE OF A SCATTERED FROST ON
BOTH FRIDAY AND SATURDAY MORNING.
&&
.SHORT TERM...(TONIGHT THROUGH THURSDAY NIGHT)
ISSUED AT 315 PM EDT TUE MAY 21 2013
THREATS ARE THREE FOLD NEXT FEW DAYS WITH ISOLATED STRONG/SEVERE
STORMS THIS EVENING...HEAVY RAIN AND POSSIBLE LOCAL FLOOD POTENTIAL
ON WEDNESDAY... AND THEN MUCH COOLER AIR WITH A LATE SEASON FROST
THREAT BOTH FRI AND SAT MORNING...
LIKE RECENT HRRR GUIDANCE INDICATING ISOL TO SCATTERED TSTORM
COVERAGE SOUTH AND EAST OF KBEH...KY70...KMOP LINE THIS EVENING.
OVERALL COVERAGE AND POTENTIAL FOR ORGANIZATION WILL BE SUPPRESSED
BY MODEST SHORTWAVE RIDGING AND UPPER CONVERGENCE. INITIAL FOCUS IS
AN AXIS OF 1000 J/KG MUCAPE STRETCHING FROM KGRR TOWARDS THE THUMB.
THAT COMBINED WITH 35KTS BULK 0-6KM SHEAR WILL LIKELY GIVE RISE TO
SOME STRONG AND POSSIBLY SEVERE PULSE TYPE STORMS.
HEAVY RAIN THREAT ON WEDNESDAY WITH SFC CYCLOGENESIS AND MID LEVEL
FRONTOGENESIS AS NICE SHORTWAVE MOVES NORTHEASTWARD FROM MO/AR THIS
EVENING CROSSING THE REGION WED. BOTH ECMWF AND GFS AS WELL AS SOME
OF THE SHORTER TERM MESO GUIDANCE ALL INDICATE A 75 WIDE 1-2 INCH
BAND OF RAIN ORIENTED SSW TO NNE ON WEDNESDAY. THE MOISTURE AND
DYNAMICS ARE CERTAINLY IN POSITION TO SUPPORT THE RAINFALL...IT IS
JUST WHERE THE AXIS OF THE HEAVIER RAINFALL WILL BE. AT THIS POINT
FEEL THE BEST BET WOULD BE JUST ABOUT ON A KAZO...KGRR...KMOP LINE
WITH KMKG ABOUT AS FAR WEST AS IT MIGHT BE AND KLAN AS FAR EAST.
WRAP AROUND MOISTURE AND MUCH COOLER AIR MOVE IN BY THURSDAY AS
UPPER LOW OVER MN OPENS AND SWINGS EASTWARD THROUGH THE REGION. H85
TEMPS DROP TO NEAR ZERO BY THU EVENING WITH MUCH DRIER SFC DEWPOINT
DRIVING INTO THE REGION AS UPSTREAM CANADIAN SFC HIGH BUILD
OVERHEAD. FEEL PREETY CONFIDENT ABOUT FROST POTENTIAL FRI AND SAT
MORNING...ESPECIALLY UP NORTH AND IN SHELTERED LOW LYING AREAS
EVERYWHERE. NOT SURE WHICH MORNING WILL BE THE COLDER...FRI HAS THE
COLDER OVERALL AIRMASS BUT BOUNDARY LAYER WINDS WILL INHIBIT
RADIATIONAL COOLING.
&&
.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 315 PM EDT TUE MAY 21 2013
THE LONG TERM PORTION OF THE FCST PERIOD LOOKS RATHER QUIET FOR
LOWER MICHIGAN. THE UPPER AIR PATTERN WILL TAKE ON SOME OF THE
CHARACTERISTICS OF AN OMEGA BLOCK. THIS OCCURS AS THE TROUGH/LOW
MOVING THROUGH MID WEEK HELPS TO ESTABLISH AN UPPER LOW ACROSS THE
NE U.S. AND THE CANADIAN MARITIMES. AN UPPER LOW WILL BECOME
ESTABLISHED ACROSS THE WRN U.S. COAST...WITH A RIDGE HOLDING ON IN
THE CENTRAL PORTION OF THE COUNTRY.
LOWER MICHIGAN SHOULD END UP UNDER THE DRY PORTION DOWNSTREAM OF THE
RIDGE AS IT SITS ALMOST STATIONARY. COOL NW FLOW ALOFT WILL KEEP
HIGHS IN THE 60S FROM FRI AND LIKELY THROUGH SUN WITH H850 TEMPS
ROUGHLY FROM 3-5C. WE STILL ARE EXPECTING SOME FROST POTENTIAL UP
NORTH ON FRI NIGHT BEFORE THE AIR MASS MODERATES SOME FOR THE
REMAINDER OF THE WEEKEND.
A WEAK SHORT WAVE WILL PUSH THROUGH THE REGION LATE SUN AND SUN
NIGHT. RIGHT NOW IT SEEMS THAT THIS SHOULD MOVE THROUGH DRY AS THE
LONG WAVE RIDGE SHOULD OVERCOME THIS WEAK SHORT WAVE. ALSO THE AIR
MASS SHOULD BE FAIRLY DRY WITH THE RIDGE SITTING OVER THE AREA FOR A
FEW DAYS AND NO GOOD MOISTURE ADVECTION EXPECTED THROUGH SUN.
SOME SPORADIC MODEL RUNS HAD BEEN SHOWING A WARM FRONT APPROACHING
LATE SUN AND REMAINING THROUGH TUE. THIS WOULD HAVE BROUGHT SOME
RAIN CHCS TO THE AREA. IT APPEARS NOW THAT THE NW FLOW ALOFT SHOULD
KEEP THIS FRONT SW OF THE AREA UNTIL AT LEAST TUE BEFORE SOME LOW
CHCS OF SHOWERS/STORMS WOULD DEVELOP. TEMPS WILL WARM INTO THE 70S
BY TUE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 137 PM EDT TUE MAY 21 2013
THE MAIN FOCUS OF THE 18Z FCSTS IS ONCE AGAIN CONVECTION TRENDS
OVER THE NEXT 24 HOURS.
THE AREA HAS BEEN SLOW TO HEAT UP SIGNIFICANTLY THIS MORNING DUE
TO THE RAIN EARLY THIS MORNING AND THE MID LEVEL CLOUD COVER THAT
HAS BEEN PLAGUING THE AREA. MORE BREAKS ARE OPENING UP...AND
INSTABILITY IS BUILDING. WE EXPECT JUST SPOTTY STORMS TO DEVELOP THIS
AFTERNOON ALONG AND INLAND OF THE LAKE BREEZE/LAKE SHADOW...MAINLY SE
OF A LINE FROM SOUTH HAVEN TO CADILLAC. SPOTTY MVFR CONDITIONS
SHOULD LIFT TO VFR EXCEPT DIRECTLY UNDER ANY STORMS THAT DEVELOP.
WE SHOULD SEE A BREAK IN CONVECTION THIS EVENING AND DURING THE
EARLY OVERNIGHT HOURS. WE WILL SEE THE CHCS OF RAIN INCREASE AFTER
08-10Z WED AS A WAVE OF LOW PRESSURE APPROACHES. THIS SHOULD BE
MAINLY SHOWERS/RAIN WITH ONLY A FEW EMBEDDED STORMS DOWN SOUTH.
THE STORM CHCS ARE LOW ENOUGH AT ANY ONE TERMINAL TO LEAVE OUT OF
THE FCST FOR NOW. WIDESPREAD MVFR CONDITIONS SHOULD ACCOMPANY THIS
PCPN WITH SOME LOCAL IFR NOT OUT OF THE QUESTION. THIS SHOULD HOLD
IN AT MOST LOCATIONS THROUGH 18Z BEFORE IT MOVES OUT AFTER 18Z WED.
&&
.MARINE...
ISSUED AT 315 PM EDT TUE MAY 21 2013
SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED ON THURSDAY AS COLDER AIR
WRAPS IN BEHIND DEPARTING LOW PRESSURE SYSTEM. HIGH PRESSURE WILL
BRING QUIET AND COOL CONDITIONS FOR MOST IF NOT ALL OF THE HOLIDAY
WEEKEND.
&&
.FIRE WEATHER...
ISSUED AT 315 PM EDT TUE MAY 21 2013
THE AREA WILL SEE PERIODS OF RAIN THROUGH THURSDAY. OVER AN INCH OF
RAIN IS LIKELY KEEPING THE FIRE RISK LOW.
&&
.HYDROLOGY...
ISSUED AT 315 PM EDT TUE MAY 21 2013
PERIODS OF HEAVIER RAIN IS EXPECTED BY LATE TONIGHT AND SHOULD
LINGER UNTIL THURSDAY. SOME TYPICAL LOCALIZED FLOODING IS POSSIBLE
BY WEDNESDAY AFTERNOON IN LOW LYING URBAN AND RURAL AREAS AND ON
SMALL STREAMS AND RIVERS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
SYNOPSIS...DKC
SHORT TERM...DKC
LONG TERM...NJJ
AVIATION...NJJ
FIRE WEATHER...DKC
HYDROLOGY...DKC
MARINE...DKC
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
117 PM EDT TUE MAY 21 2013
.AVIATION...
//DISCUSSION...
A DEEP SOUTHWEST FLOW WILL REMAIN IN PLACE ACROSS THE REGION
THROUGH THE TAF PERIOD. WHILE THIS WILL LEAVE THE LOCAL ENVIRONMENT
RELATIVELY MOIST AND UNSTABLE...PROSPECTS OF THUNDERSTORM
DEVELOPMENT REMAIN QUITE ILL-DEFINED. RECENT OBSERVATIONAL/
SATELLITE TRENDS AND MODEL GUIDANCE WOULD SUGGEST ANY POTENTIAL
DEVELOPMENT LATE THIS AFTERNOON WILL TEND TO REMAIN WIDELY
SCATTERED IN COVERAGE. A DEEPENING MIXED LAYER WILL LEAD TO SOME
SOUTHWESTERLY WIND GUSTS IN THE 20 KNOTS RANGE THROUGH PEAK HEATING.
FOR DTW...A LOW PROBABILITY DOES EXIST FOR THUNDERSTORMS TO IMPACT
THE TERMINAL LATE THIS AFTERNOON AND EVENING. HOWEVER THE POTENTIAL
NOW APPEARS TOO LIMITED GIVEN THE QUESTION OF COVERAGE TO INCLUDE
A SPECIFIC MENTION.
//DTW THRESHOLD THREATS...
* LOW CONFIDENCE IN THUNDERSTORM OCCURRANCE FROM MID AFTERNOON INTO
THE EVENING.
&&
.PREV DISCUSSION...ISSUED 1013 AM EDT TUE MAY 21 2013
UPDATE...
SE MICHIGAN REMAINS LODGED WITHIN A DEEP/MOIST AND PROGRESSIVELY
DESTABILIZING SOUTHWEST FLOW LATE THIS MORNING. SEVERAL HOUR WINDOW
OF NEARLY FULL INSOLATION CERTAINLY HELPING THIS PROCESS...ALTHOUGH
THE NORTHERN EXTENSION OF THE REMNANT CLOUD DEBRIS ATTACHED TO THE
LEFTOVER WEAK PV FILAMENT STREAMING INTO WEST-CENTRAL OHIO WILL
BEGIN TO FILTERING THE HEATING COMPONENT SLIGHTLY HEADING INTO
MIDDAY. HOWEVER GIVEN CURRENT TRENDS...HIGH TEMPERATURES OF LOWER
TO MIDDLE 80S CERTAINLY ARE ATTAINABLE. THIS PROJECTS TO ROUGHLY
1500 J/KG OF MLCAPE FOR THIS AFTERNOON.
DESPITE THIS EMERGING LOW LEVEL INSTABILITY GRADIENT...DELINEATING
BOTH THE LOCATION AND SCALE OF CONVECTIVE DEVELOPMENT...BOTH
UPSTREAM AND LOCALLY...REMAINS A CHALLENGE FOR THE AFTERNOON AND
EVENING PERIOD. 12Z DTX SOUNDING AND RECENT MODEL GUIDANCE SUGGEST
SOME DEGREE OF CAPPING REMAINS IN PLACE...ALBEIT NOT NEARLY AS
STRONG AS NOTED YESTERDAY. CONVECTIVE INITIATION MAY BECOME TIED TO
ADDITIONAL WEAK SHORTWAVE ENERGY AND ON THE LEAD EDGE OF AN
EXPANDING DIFFERENTIAL HEATING ZONE WORKING ACROSS MISSOURI AND INTO
SOUTHERN ILLINOIS. RECENT HI RES MODEL GUIDANCE PROVIDE FEW
CLUES...SUGGESTING A WINDOW FOR ISOLATED/SCATTERED DISCRETE CELL
DEVELOPMENT IN THAT FAVORED 19-22Z PERIOD. GIVEN A SOLID BACKGROUND
THERMODYNAMIC ENVIRONMENT TO MAINTAIN UPDRAFT STRENGTH...THE
PRESENCE OF A SUPPORTIVELY DEEP LAYER WIND FIELD WILL MAINTAIN A
RISK OF DAMAGING WINDS AND HAIL WITH ANY CELLS THAT CAN ORGANIZE
THROUGH THE PEAK HEATING CYCLE.
MINOR UPDATE ISSUED ALREADY TO READJUST POPS THROUGH THE EVENING AND
TWEAK TEMPERATURES BASED ON RECENT TRENDS.
PREV DISCUSSION...ISSUED 738 AM EDT TUE MAY 21 2013
UPDATE...
DESPITE A MID LEVEL SHORTWAVE AND SUPPORT FROM THE LOW LEVEL
JET...MORNING CONVECTION HAS NOT HELD TOGETHER WELL AS IT HAS
TRAVELLED THROUGH SOUTHEAST MICHIGAN THIS MORNING. AS THE 06Z RUNS
COME IN THEY ARE KEEPING ADDITIONAL CONVECTION TO THE NORTH AND
SOUTH OF THE AREA WHERE THE BETTER DYNAMICS ARE...IN STARK
CONTRAST TO THE 00Z RUNS WHICH BLANKETED THE AREA WITH RAIN ALL
DAY. WATER VAPOR IMAGERY SHOWS SOME VALIDITY TO THIS THINKING AS
THE JET STREAM TO THE NORTH PULLS STORMS OVER THE NORTHERN GREAT
LAKES AND ACTIVITY TO THE SOUTH SHOWS SIGNS OF STAYING OVER THE
SOUTH. IT APPEARS SOUTHEAST MICHIGAN COULD BE IN BETWEEN ACTIVITY
TO THE NORTH AND SOUTH TODAY THE WAY WATER VAPOR IMAGERY IS
SHAPING UP. GIVEN THESE FACTORS WILL TONE DOWN POPS FROM
CATEGORICAL TO LIKELY...HOWEVER GOING BELOW THIS THRESHOLD WOULD
BE A MISTAKE WITH THE AMOUNT OF INSTABILITY THAT IS FORECAST TO
DEVELOP DURING THE AFTERNOON HOURS. FURTHER ADJUSTMENTS TO THE
FORECAST WILL BE MADE AS NECESSARY.
PREV DISCUSSION...ISSUED 342 AM EDT TUE MAY 21 2013
SHORT TERM...TODAY AND TONIGHT
LINE OF THUNDERSTORMS CURRENTLY OVER NORTHERN ILLINOIS IS SLOWLY BUT
SURELY MARCHING NORTHEAST DURING THE EARLY MORNING HOURS. THE MAIN
QUESTION THIS MORNING IS HOW WELL THIS ACTIVITY WILL HOLD TOGETHER
AS IT TRACKS THROUGH SOUTHEAST MICHIGAN. HI-RES MODEL RUNS ARE IN
GENERAL AGREEMENT IN BRINGING THE SYSTEM THROUGH BETWEEN 09-13Z.
THAT IS WHERE THE AGREEMENT ENDS AS THE HRRR LIFTS THE BEST
THUNDERSTORM ACTIVITY NORTH THROUGH NORTHERN LOWER MICHIGAN WHILE
THE WRF MAINTAINS THE LINE OF STRONG THUNDERSTORMS AS IT TRACKS
THROUGH SOUTHEAST MICHIGAN...MAINLY NORTH OF THE M-59 CORRIDOR. THE
EVOLUTION OF THE JET STREAM WOULD VALIDATE THE HRRR SOLUTION AS IT
LIFTS THE 100+ KNOT JET NORTH OVER THE NORTHERN GREAT LAKES...TAKING
THE UPPER LEVEL DIVERGENCE AFFORDED BY THE RIGHT ENTRANCE REGION OF
THE JET WITH IT. HOWEVER LOWER LEVELS LEND CREDENCE TO THE WRF
SOLUTION AS THE MAIN SHORTWAVE DRIVING THE NORTHERN EDGE OF THE
CONVECTION IS PROGGED TO GO DIRECTLY THROUGH SOUTHEAST MICHIGAN WITH
THE NOSE OF THE 35 KNOT 850 MB LOW LEVEL JET POINTED OVER SOUTHEAST
MICHIGAN. DESPITE THE LOSS OF UPPER LEVEL JET SUPPORT...THE LOWER
LEVEL DYNAMICS POINT TO AN ACTIVE MORNING ACROSS SOUTHEAST MICHIGAN
WITH THE LINE OF CONVECTION EXPECTED TO SURVIVE THE TRIP AND TRACK
THROUGH THE AREA. THIS ACTIVITY WILL STILL HAVE QUITE A BIT OF
INSTABILITY TO WORK WITH AS MUCAPE VALUES REMAIN AT 1000 TO 1500
J/KG DURING THE EARLY MORNING HOURS. SEVERE WEATHER THREAT FROM THIS
MORNINGS CONVECTION WILL MAINLY BE A WIND THREAT...AS UPSTREAM
OBSERVATIONS SHOW LITTLE THREAT FROM LARGE HAIL...ALTHOUGH SMALL TO
NEAR SEVERE HAIL IS A POSSIBILITY.
AFTER THIS INITIAL ACTIVITY THE PICTURE BECOMES VERY MUDDLED AS THE
NWP MODELS KEEP SHOWERS AND THUNDERSTORMS GOING FOR MUCH OF THE DAY.
THIS SCENARIO IS CERTAINLY PLAUSIBLE AS ANOTHER JET STREAK LIFTS
FROM THE SOUTHWEST AND MAKES ITS WAY OVER THE GREAT LAKES REGION. AS
A RESULT THE AREA WILL BE IN THE PATH OF SEVERAL SHORTWAVES ROTATING
AROUND THE MAIN MID LEVEL LOW PRESSURE SYSTEM TAKING UP RESIDENCE
OVER THE MISSOURI VALLEY. WITHOUT A KEY FEATURE INDICATING THERE
WILL BE A SUBSTANTIAL BREAK FROM THE ACTION...DO NOT PLAN ON
DEVIATING MUCH FROM THE PREVIOUS FORECAST HIGH POPS THROUGH THE
DAYTIME HOURS.
SEVERE WEATHER POTENTIAL THIS AFTERNOON WILL HINGE ON THE ABILITY TO
GET A BREAK IN THE CONVECTION. THIS WINDOW WILL NOT HAVE TO BE
LARGE...AS EVIDENCED YESTERDAY...WITH A BRIEF BREAK ALLOWING
TEMPERATURES AND CAPES TO RISE SIGNIFICANTLY IN A SHORT PERIOD OF
TIME. MODELS SHOW MUCAPE VALUES RANGING FROM 500 TO 1000 J/KG WITH A
FAIRLY STEADY STREAM OF CONVECTION DURING THE DAY. AFTERNOON
SUNSHINE COULD EASILY BOOST THESE VALUES TO AROUND 1500 J/KG GIVEN
THE LATE MAY SUN ANGLE AND THE VERY WARM AIR IN THE LOW LEVELS. IN
ADDITION TO THE INSTABILITY...0-6 KM BULK SHEAR VALUES ARE A GOOD 30
TO 40 KNOTS TODAY...MEANING THE POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS PRODUCING DAMAGING WINDS AND LARGE HAIL ARE A
POSSIBILITY. CLOSER INSPECTION OF THE HODOGRAPH AND LOW LEVEL CAPE
SHOW ISOLATED TORNADOES WILL ALSO BE A THREAT...ESPECIALLY IF WE CAN
GET SOME SUNSHINE...AS 0-3KM CAPE VALUES REACH 150 TO 200 J/KG AND
STORM RELATIVE HELICITY VALUES GET TO 150 TO 200 M2/S2. ALL OF THIS
ACTIVITY MAKES FORECASTING HIGH TEMPERATURES TODAY QUITE
CHALLENGING. EVEN WITH ALL OF THE ACTIVITY WE SHOULD BE ABLE TO GET
INTO THE LOW 80S AWAY FROM THE GREAT LAKES...HOWEVER A FEW MID 80S
ARE A DISTINCT POSSIBILITY IF THE AFOREMENTIONED BREAK IN THE
ACTIVITY OCCURS.
OVERNIGHT MODELS ARE HINTING AT A BREAK IN THE CONVECTION AS THE
SECONDARY JET STREAM MOVES OFF TO THE NORTH WITH NVA PROGGED AT THE
500 MB LEVEL AS THE SURFACE LOW LIFTS OVER THE SOO. EVEN WITH THESE
FACTORS THERE IS ABUNDANT LOW LEVEL MOISTURE ACROSS SOUTHEAST
MICHIGAN...SO A COMPLETELY DRY FORECAST IS NOT IN THE CARDS AND
NEITHER IS A CONTINUATION OF THE HIGH POPS FROM TODAY. WITH ALL
THESE FACTORS IN MIND WILL MAINTAIN CHANCY POPS DURING THE OVERNIGHT
HOURS. ABUNDANT CLOUD COVER AND THE REGION STILL IN THE WARM SECTOR
WILL ONCE AGAIN LEAD TO A MILD NIGHT WITH OVERNIGHT LOWS EXPECTED IN
THE 60S.
LONG TERM...WEDNESDAY THROUGH MONDAY
UPPER LEVEL TROUGHING WILL KEEP MENTION OF SHOWERS AND THUNDERSTORMS
AROUND INTO THURSDAY WHICH IS WHEN THE MAIN TROUGH AXIS PASSES EAST
OF THE AREA ALLOWING HEIGHTS TO BUILD. MEANWHILE...COMPLEX SFC LOW
PRESSURE SYSTEM WILL WORK THROUGH LOWER MI ON WEDNESDAY AND THURSDAY
BEFORE A STRONG CANADIAN HIGH PRESSURE SYSTEM DROPS INTO THE GREAT
LAKES AND EXPANDS ACROSS MUCH OF THE EASTERN CONUS FOR THE HOLIDAY
WEEKEND. THIS WILL LEAD TO A DRY BUT COOL WEEKEND.
FIRST OFF WE WILL ADDRESS CONVECTIVE POTENTIAL FOR WEDNESDAY. THE
GFS POORLY INITIALIZES THE SFC LOW OVER THE NORTHERN PLAINS SO WILL
LEAN MORE TOWARD THE ECMWF/NAM/GEM REGIONAL. THE UPPER LEVEL LOW
THAT HAS BEEN SITTING OVER THE NORTHERN PLAINS FOR A FEW DAYS NOW
WILL PHASE WITH A NORTHERN STREAM TROUGH DIGGING SOUTH THROUGH
MANITOBA/ONTARIO ON WEDNESDAY. THIS WILL LEAD TO A MORE PROGRESSIVE
SYSTEM FINALLY. WITH THE CLOSED NATURE OF THE UPPER LOW...A FEW SFC
LOWS HAVE BEEN ROTATING AROUND EACH OTHER THE LAST TWO DAYS. AS THE
WAVE OPENS FURTHER AND THE UPPER JET TURNS WEST/EAST ACROSS NORTHERN
MI...THE MAIN SFC LOW WILL RELEASE AND TRACK ACROSS NORTHERN LOWER
MI THROUGH THE DAY WEDNESDAY. THIS WILL BE A BROAD WEAKENING LOW BUT
WILL PRESENT ISENTROPIC ASCENT AND WILL KEEP THE THETA E RIDGE UP
INTO SE MI. FOCUS WILL BE PLACED ON A SOUTHERN STREAM SHORTWAVE THAT
WILL ROUND THE BASE OF THE TROUGH AND TARGET LOWER MI WEDNESDAY
AFTERNOON. MODEL CONSENSUS SHOWS A SFC LOW CLIPPING EXTREME SE MI.
THIS WILL OPEN THE DOOR FOR ADDITIONAL HEATING AND MOISTURE INTO
THAT AREA DURING PEAK AFTERNOON HEATING WITH THE EASTWARD TRACKING
UPPER LEVEL JET MORE SQUARELY OVERHEAD. CONVECTIVE PARAMETERS ARE ON
THE DECLINE FROM MONDAY AND TUESDAY BUT THERE WILL STILL BE 500 TO
1000 J/KG OF TALL SKINNY MUCAPE WITH A COLD/COOL FRONT PASSING
THROUGH THE AREA IN THE EVENING. OVERALL WEDNESDAY LOOKS LIKE IT
WILL BE COMPOSED OF WIDESPREAD SHOWERS AND THUNDERSTORMS WITH A
CHANCE OF ORGANIZED CONVECTION ACROSS THE EXTREME SE PORTION OF THE
CWA.
UPPER LEVEL TROUGH AXIS WILL BE OVER WESTERN LOWER MI WEDNESDAY
NIGHT PROVIDING BROAD AREA OF LIFT ALOFT WITH THE BACK END OF THE
SFC LOW STILL LINGERING. THIS WILL KEEP SHOWERS AND THUNDERSTORMS
OVER MUCH OF LOWER MI THROUGH THE OVERNIGHT. THE AXIS WILL SWEEP
THROUGH SE MI EARLY ON THURSDAY LEADING TO A CLEARING TREND IN THE
SHOWERS THROUGH THE DAY FROM NW TO SE. MAIN BAROCLINIC ZONE THATS
BEEN LINGERING ACROSS THE NORTHERN GREAT LAKES WILL SURGE SOUTH ON
THURSDAY WITH STRONG CANADIAN HIGH PRESSURE RIGHT BEHIND IT. WITH
BUILDING HEIGHTS ALOFT...CLOUDS WILL CLEAR OUT BUT THAT WILL NOT BE
REALIZED IN TEMPERATURES. 850 MB TEMPS IN THE LOW SINGLE DIGITS WILL
ONLY ALLOW HIGH TEMPS TO REACH AROUND 60F BOTH THURSDAY AND FRIDAY
WITH LOWS AROUND 40. A SLOW WARMING TREND THROUGH THE WEEKEND WILL
ONLY ALLOW TEMPS TO REBOUND TO NEAR 70 FOR MONDAY AND TUESDAY.
THOUGH IT WILL BE COOL...AT LEAST IT LOOKS TO STAY DRY THOUGHT THE
HOLIDAY WEEKEND.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....MR
UPDATE.......MR
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1013 AM EDT TUE MAY 21 2013
.UPDATE...
SE MICHIGAN REMAINS LODGED WITHIN A DEEP/MOIST AND PROGRESSIVELY
DESTABILIZING SOUTHWEST FLOW LATE THIS MORNING. SEVERAL HOUR WINDOW
OF NEARLY FULL INSOLATION CERTAINLY HELPING THIS PROCESS...ALTHOUGH
THE NORTHERN EXTENSION OF THE REMNANT CLOUD DEBRIS ATTACHED TO THE
LEFTOVER WEAK PV FILAMENT STREAMING INTO WEST-CENTRAL OHIO WILL
BEGIN TO FILTERING THE HEATING COMPONENT SLIGHTLY HEADING INTO
MIDDAY. HOWEVER GIVEN CURRENT TRENDS...HIGH TEMPERATURES OF LOWER
TO MIDDLE 80S CERTAINLY ARE ATTAINABLE. THIS PROJECTS TO ROUGHLY
1500 J/KG OF MLCAPE FOR THIS AFTERNOON.
DESPITE THIS EMERGING LOW LEVEL INSTABILITY GRADIENT...DELINEATING
BOTH THE LOCATION AND SCALE OF CONVECTIVE DEVELOPMENT...BOTH
UPSTREAM AND LOCALLY...REMAINS A CHALLENGE FOR THE AFTERNOON AND
EVENING PERIOD. 12Z DTX SOUNDING AND RECENT MODEL GUIDANCE SUGGEST
SOME DEGREE OF CAPPING REMAINS IN PLACE...ALBEIT NOT NEARLY AS
STRONG AS NOTED YESTERDAY. CONVECTIVE INITIATION MAY BECOME TIED TO
ADDITIONAL WEAK SHORTWAVE ENERGY AND ON THE LEAD EDGE OF AN
EXPANDING DIFFERENTIAL HEATING ZONE WORKING ACROSS MISSOURI AND INTO
SOUTHERN ILLINOIS. RECENT HI RES MODEL GUIDANCE PROVIDE FEW
CLUES...SUGGESTING A WINDOW FOR ISOLATED/SCATTERED DISCRETE CELL
DEVELOPMENT IN THAT FAVORED 19-22Z PERIOD. GIVEN A SOLID BACKGROUND
THERMODYNAMIC ENVIRONMENT TO MAINTAIN UPDRAFT STRENGTH...THE
PRESENCE OF A SUPPORTIVELY DEEP LAYER WIND FIELD WILL MAINTAIN A
RISK OF DAMAGING WINDS AND HAIL WITH ANY CELLS THAT CAN ORGANIZE
THROUGH THE PEAK HEATING CYCLE.
MINOR UPDATE ISSUED ALREADY TO READJUST POPS THROUGH THE EVENING AND
TWEAK TEMPERATURES BASED ON RECENT TRENDS.
&&
.AVIATION...ISSUED 727 AM EDT TUE MAY 21 2013
//DISCUSSION...
THE REGION OF THUNDERSTORMS THAT MOVED IN FROM ILLINOIS HAS HAD
LITTLE EFFECT OVER THE TAF SITES...AND WILL ONLY BRING SOME SHOWERS
TO KMBS EARLY THIS MORNING. THE EXTENT OF CLOUD COVER FROM THIS
COMPLEX WHICH MAY LINGER INTO THE AFTERNOON RAISES CONSIDERABLE
UNCERTAINTY WITH RESPECT TO THE CHANCES AND TIMING OF THUNDERSTORMS
LATER IN THE THIS AFTERNOON. BEST CHANCES FOR THUNDERSTORMS WILL BE
THIS AFTERNOON...THEREFORE WILL PUT A TEMPE GROUP IN THE 19-23Z TIME
FRAME WHEN THUNDERSTORMS ARE MOSTLY LIKELY TO OCCUR. A BREAK IN THE
ACTIVITY IS EXPECTED OVERNIGHT AS ONE OF THE SURFACE LOWS TRACKS
THROUGH THE NORTHERN GREAT LAKES.
FOR DTW...TIMING OF THUNDERSTORMS LATER IN THE DAY REMAINS HIGHLY
UNCERTAIN...THE BEST POTENTIAL WILL BE IN THE 19-23Z TIME FRAME WITH
MAX HEATING.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN THUNDERSTORMS THIS AFTERNOON.
&&
.PREV DISCUSSION...ISSUED 738 AM EDT TUE MAY 21 2013
UPDATE...
DESPITE A MID LEVEL SHORTWAVE AND SUPPORT FROM THE LOW LEVEL
JET...MORNING CONVECTION HAS NOT HELD TOGETHER WELL AS IT HAS
TRAVELLED THROUGH SOUTHEAST MICHIGAN THIS MORNING. AS THE 06Z RUNS
COME IN THEY ARE KEEPING ADDITIONAL CONVECTION TO THE NORTH AND
SOUTH OF THE AREA WHERE THE BETTER DYNAMICS ARE...IN STARK
CONTRAST TO THE 00Z RUNS WHICH BLANKETED THE AREA WITH RAIN ALL
DAY. WATER VAPOR IMAGERY SHOWS SOME VALIDITY TO THIS THINKING AS
THE JET STREAM TO THE NORTH PULLS STORMS OVER THE NORTHERN GREAT
LAKES AND ACTIVITY TO THE SOUTH SHOWS SIGNS OF STAYING OVER THE
SOUTH. IT APPEARS SOUTHEAST MICHIGAN COULD BE IN BETWEEN ACTIVITY
TO THE NORTH AND SOUTH TODAY THE WAY WATER VAPOR IMAGERY IS
SHAPING UP. GIVEN THESE FACTORS WILL TONE DOWN POPS FROM
CATEGORICAL TO LIKELY...HOWEVER GOING BELOW THIS THRESHOLD WOULD
BE A MISTAKE WITH THE AMOUNT OF INSTABILITY THAT IS FORECAST TO
DEVELOP DURING THE AFTERNOON HOURS. FURTHER ADJUSTMENTS TO THE
FORECAST WILL BE MADE AS NECESSARY.
PREV DISCUSSION...ISSUED 342 AM EDT TUE MAY 21 2013
SHORT TERM...TODAY AND TONIGHT
LINE OF THUNDERSTORMS CURRENTLY OVER NORTHERN ILLINOIS IS SLOWLY BUT
SURELY MARCHING NORTHEAST DURING THE EARLY MORNING HOURS. THE MAIN
QUESTION THIS MORNING IS HOW WELL THIS ACTIVITY WILL HOLD TOGETHER
AS IT TRACKS THROUGH SOUTHEAST MICHIGAN. HI-RES MODEL RUNS ARE IN
GENERAL AGREEMENT IN BRINGING THE SYSTEM THROUGH BETWEEN 09-13Z.
THAT IS WHERE THE AGREEMENT ENDS AS THE HRRR LIFTS THE BEST
THUNDERSTORM ACTIVITY NORTH THROUGH NORTHERN LOWER MICHIGAN WHILE
THE WRF MAINTAINS THE LINE OF STRONG THUNDERSTORMS AS IT TRACKS
THROUGH SOUTHEAST MICHIGAN...MAINLY NORTH OF THE M-59 CORRIDOR. THE
EVOLUTION OF THE JET STREAM WOULD VALIDATE THE HRRR SOLUTION AS IT
LIFTS THE 100+ KNOT JET NORTH OVER THE NORTHERN GREAT LAKES...TAKING
THE UPPER LEVEL DIVERGENCE AFFORDED BY THE RIGHT ENTRANCE REGION OF
THE JET WITH IT. HOWEVER LOWER LEVELS LEND CREDENCE TO THE WRF
SOLUTION AS THE MAIN SHORTWAVE DRIVING THE NORTHERN EDGE OF THE
CONVECTION IS PROGGED TO GO DIRECTLY THROUGH SOUTHEAST MICHIGAN WITH
THE NOSE OF THE 35 KNOT 850 MB LOW LEVEL JET POINTED OVER SOUTHEAST
MICHIGAN. DESPITE THE LOSS OF UPPER LEVEL JET SUPPORT...THE LOWER
LEVEL DYNAMICS POINT TO AN ACTIVE MORNING ACROSS SOUTHEAST MICHIGAN
WITH THE LINE OF CONVECTION EXPECTED TO SURVIVE THE TRIP AND TRACK
THROUGH THE AREA. THIS ACTIVITY WILL STILL HAVE QUITE A BIT OF
INSTABILITY TO WORK WITH AS MUCAPE VALUES REMAIN AT 1000 TO 1500
J/KG DURING THE EARLY MORNING HOURS. SEVERE WEATHER THREAT FROM THIS
MORNINGS CONVECTION WILL MAINLY BE A WIND THREAT...AS UPSTREAM
OBSERVATIONS SHOW LITTLE THREAT FROM LARGE HAIL...ALTHOUGH SMALL TO
NEAR SEVERE HAIL IS A POSSIBILITY.
AFTER THIS INITIAL ACTIVITY THE PICTURE BECOMES VERY MUDDLED AS THE
NWP MODELS KEEP SHOWERS AND THUNDERSTORMS GOING FOR MUCH OF THE DAY.
THIS SCENARIO IS CERTAINLY PLAUSIBLE AS ANOTHER JET STREAK LIFTS
FROM THE SOUTHWEST AND MAKES ITS WAY OVER THE GREAT LAKES REGION. AS
A RESULT THE AREA WILL BE IN THE PATH OF SEVERAL SHORTWAVES ROTATING
AROUND THE MAIN MID LEVEL LOW PRESSURE SYSTEM TAKING UP RESIDENCE
OVER THE MISSOURI VALLEY. WITHOUT A KEY FEATURE INDICATING THERE
WILL BE A SUBSTANTIAL BREAK FROM THE ACTION...DO NOT PLAN ON
DEVIATING MUCH FROM THE PREVIOUS FORECAST HIGH POPS THROUGH THE
DAYTIME HOURS.
SEVERE WEATHER POTENTIAL THIS AFTERNOON WILL HINGE ON THE ABILITY TO
GET A BREAK IN THE CONVECTION. THIS WINDOW WILL NOT HAVE TO BE
LARGE...AS EVIDENCED YESTERDAY...WITH A BRIEF BREAK ALLOWING
TEMPERATURES AND CAPES TO RISE SIGNIFICANTLY IN A SHORT PERIOD OF
TIME. MODELS SHOW MUCAPE VALUES RANGING FROM 500 TO 1000 J/KG WITH A
FAIRLY STEADY STREAM OF CONVECTION DURING THE DAY. AFTERNOON
SUNSHINE COULD EASILY BOOST THESE VALUES TO AROUND 1500 J/KG GIVEN
THE LATE MAY SUN ANGLE AND THE VERY WARM AIR IN THE LOW LEVELS. IN
ADDITION TO THE INSTABILITY...0-6 KM BULK SHEAR VALUES ARE A GOOD 30
TO 40 KNOTS TODAY...MEANING THE POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS PRODUCING DAMAGING WINDS AND LARGE HAIL ARE A
POSSIBILITY. CLOSER INSPECTION OF THE HODOGRAPH AND LOW LEVEL CAPE
SHOW ISOLATED TORNADOES WILL ALSO BE A THREAT...ESPECIALLY IF WE CAN
GET SOME SUNSHINE...AS 0-3KM CAPE VALUES REACH 150 TO 200 J/KG AND
STORM RELATIVE HELICITY VALUES GET TO 150 TO 200 M2/S2. ALL OF THIS
ACTIVITY MAKES FORECASTING HIGH TEMPERATURES TODAY QUITE
CHALLENGING. EVEN WITH ALL OF THE ACTIVITY WE SHOULD BE ABLE TO GET
INTO THE LOW 80S AWAY FROM THE GREAT LAKES...HOWEVER A FEW MID 80S
ARE A DISTINCT POSSIBILITY IF THE AFOREMENTIONED BREAK IN THE
ACTIVITY OCCURS.
OVERNIGHT MODELS ARE HINTING AT A BREAK IN THE CONVECTION AS THE
SECONDARY JET STREAM MOVES OFF TO THE NORTH WITH NVA PROGGED AT THE
500 MB LEVEL AS THE SURFACE LOW LIFTS OVER THE SOO. EVEN WITH THESE
FACTORS THERE IS ABUNDANT LOW LEVEL MOISTURE ACROSS SOUTHEAST
MICHIGAN...SO A COMPLETELY DRY FORECAST IS NOT IN THE CARDS AND
NEITHER IS A CONTINUATION OF THE HIGH POPS FROM TODAY. WITH ALL
THESE FACTORS IN MIND WILL MAINTAIN CHANCY POPS DURING THE OVERNIGHT
HOURS. ABUNDANT CLOUD COVER AND THE REGION STILL IN THE WARM SECTOR
WILL ONCE AGAIN LEAD TO A MILD NIGHT WITH OVERNIGHT LOWS EXPECTED IN
THE 60S.
LONG TERM...WEDNESDAY THROUGH MONDAY
UPPER LEVEL TROUGHING WILL KEEP MENTION OF SHOWERS AND THUNDERSTORMS
AROUND INTO THURSDAY WHICH IS WHEN THE MAIN TROUGH AXIS PASSES EAST
OF THE AREA ALLOWING HEIGHTS TO BUILD. MEANWHILE...COMPLEX SFC LOW
PRESSURE SYSTEM WILL WORK THROUGH LOWER MI ON WEDNESDAY AND THURSDAY
BEFORE A STRONG CANADIAN HIGH PRESSURE SYSTEM DROPS INTO THE GREAT
LAKES AND EXPANDS ACROSS MUCH OF THE EASTERN CONUS FOR THE HOLIDAY
WEEKEND. THIS WILL LEAD TO A DRY BUT COOL WEEKEND.
FIRST OFF WE WILL ADDRESS CONVECTIVE POTENTIAL FOR WEDNESDAY. THE
GFS POORLY INITIALIZES THE SFC LOW OVER THE NORTHERN PLAINS SO WILL
LEAN MORE TOWARD THE ECMWF/NAM/GEM REGIONAL. THE UPPER LEVEL LOW
THAT HAS BEEN SITTING OVER THE NORTHERN PLAINS FOR A FEW DAYS NOW
WILL PHASE WITH A NORTHERN STREAM TROUGH DIGGING SOUTH THROUGH
MANITOBA/ONTARIO ON WEDNESDAY. THIS WILL LEAD TO A MORE PROGRESSIVE
SYSTEM FINALLY. WITH THE CLOSED NATURE OF THE UPPER LOW...A FEW SFC
LOWS HAVE BEEN ROTATING AROUND EACH OTHER THE LAST TWO DAYS. AS THE
WAVE OPENS FURTHER AND THE UPPER JET TURNS WEST/EAST ACROSS NORTHERN
MI...THE MAIN SFC LOW WILL RELEASE AND TRACK ACROSS NORTHERN LOWER
MI THROUGH THE DAY WEDNESDAY. THIS WILL BE A BROAD WEAKENING LOW BUT
WILL PRESENT ISENTROPIC ASCENT AND WILL KEEP THE THETA E RIDGE UP
INTO SE MI. FOCUS WILL BE PLACED ON A SOUTHERN STREAM SHORTWAVE THAT
WILL ROUND THE BASE OF THE TROUGH AND TARGET LOWER MI WEDNESDAY
AFTERNOON. MODEL CONSENSUS SHOWS A SFC LOW CLIPPING EXTREME SE MI.
THIS WILL OPEN THE DOOR FOR ADDITIONAL HEATING AND MOISTURE INTO
THAT AREA DURING PEAK AFTERNOON HEATING WITH THE EASTWARD TRACKING
UPPER LEVEL JET MORE SQUARELY OVERHEAD. CONVECTIVE PARAMETERS ARE ON
THE DECLINE FROM MONDAY AND TUESDAY BUT THERE WILL STILL BE 500 TO
1000 J/KG OF TALL SKINNY MUCAPE WITH A COLD/COOL FRONT PASSING
THROUGH THE AREA IN THE EVENING. OVERALL WEDNESDAY LOOKS LIKE IT
WILL BE COMPOSED OF WIDESPREAD SHOWERS AND THUNDERSTORMS WITH A
CHANCE OF ORGANIZED CONVECTION ACROSS THE EXTREME SE PORTION OF THE
CWA.
UPPER LEVEL TROUGH AXIS WILL BE OVER WESTERN LOWER MI WEDNESDAY
NIGHT PROVIDING BROAD AREA OF LIFT ALOFT WITH THE BACK END OF THE
SFC LOW STILL LINGERING. THIS WILL KEEP SHOWERS AND THUNDERSTORMS
OVER MUCH OF LOWER MI THROUGH THE OVERNIGHT. THE AXIS WILL SWEEP
THROUGH SE MI EARLY ON THURSDAY LEADING TO A CLEARING TREND IN THE
SHOWERS THROUGH THE DAY FROM NW TO SE. MAIN BAROCLINIC ZONE THATS
BEEN LINGERING ACROSS THE NORTHERN GREAT LAKES WILL SURGE SOUTH ON
THURSDAY WITH STRONG CANADIAN HIGH PRESSURE RIGHT BEHIND IT. WITH
BUILDING HEIGHTS ALOFT...CLOUDS WILL CLEAR OUT BUT THAT WILL NOT BE
REALIZED IN TEMPERATURES. 850 MB TEMPS IN THE LOW SINGLE DIGITS WILL
ONLY ALLOW HIGH TEMPS TO REACH AROUND 60F BOTH THURSDAY AND FRIDAY
WITH LOWS AROUND 40. A SLOW WARMING TREND THROUGH THE WEEKEND WILL
ONLY ALLOW TEMPS TO REBOUND TO NEAR 70 FOR MONDAY AND TUESDAY.
THOUGH IT WILL BE COOL...AT LEAST IT LOOKS TO STAY DRY THOUGHT THE
HOLIDAY WEEKEND.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
UPDATE.......MR
AVIATION.....KURIMSKI
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
738 AM EDT TUE MAY 21 2013
.UPDATE...
DESPITE A MID LEVEL SHORTWAVE AND SUPPORT FROM THE LOW LEVEL
JET...MORNING CONVECTION HAS NOT HELD TOGETHER WELL AS IT HAS
TRAVELLED THROUGH SOUTHEAST MICHIGAN THIS MORNING. AS THE 06Z RUNS
COME IN THEY ARE KEEPING ADDITIONAL CONVECTION TO THE NORTH AND
SOUTH OF THE AREA WHERE THE BETTER DYNAMICS ARE...IN STARK
CONTRAST TO THE 00Z RUNS WHICH BLANKETED THE AREA WITH RAIN ALL
DAY. WATER VAPOR IMAGERY SHOWS SOME VALIDITY TO THIS THINKING AS
THE JET STREAM TO THE NORTH PULLS STORMS OVER THE NORTHERN GREAT
LAKES AND ACTIVITY TO THE SOUTH SHOWS SIGNS OF STAYING OVER THE
SOUTH. IT APPEARS SOUTHEAST MICHIGAN COULD BE IN BETWEEN ACTIVITY
TO THE NORTH AND SOUTH TODAY THE WAY WATER VAPOR IMAGERY IS
SHAPING UP. GIVEN THESE FACTORS WILL TONE DOWN POPS FROM
CATEGORICAL TO LIKELY...HOWEVER GOING BELOW THIS THRESHOLD WOULD
BE A MISTAKE WITH THE AMOUNT OF INSTABILITY THAT IS FORECAST TO
DEVELOP DURING THE AFTERNOON HOURS. FURTHER ADJUSTMENTS TO THE
FORECAST WILL BE MADE AS NECESSARY.
&&
.AVIATION...ISSUED 727 AM EDT TUE MAY 21 2013
//DISCUSSION...
THE REGION OF THUNDERSTORMS THAT MOVED IN FROM ILLINOIS HAS HAD
LITTLE EFFECT OVER THE TAF SITES...AND WILL ONLY BRING SOME SHOWERS
TO KMBS EARLY THIS MORNING. THE EXTENT OF CLOUD COVER FROM THIS
COMPLEX WHICH MAY LINGER INTO THE AFTERNOON RAISES CONSIDERABLE
UNCERTAINTY WITH RESPECT TO THE CHANCES AND TIMING OF THUNDERSTORMS
LATER IN THE THIS AFTERNOON. BEST CHANCES FOR THUNDERSTORMS WILL BE
THIS AFTERNOON...THEREFORE WILL PUT A TEMPE GROUP IN THE 19-23Z TIME
FRAME WHEN THUNDERSTORMS ARE MOSTLY LIKELY TO OCCUR. A BREAK IN THE
ACTIVITY IS EXPECTED OVERNIGHT AS ONE OF THE SURFACE LOWS TRACKS
THROUGH THE NORTHERN GREAT LAKES.
FOR DTW...TIMING OF THUNDERSTORMS LATER IN THE DAY REMAINS HIGHLY
UNCERTAIN...THE BEST POTENTIAL WILL BE IN THE 19-23Z TIME FRAME WITH
MAX HEATING.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN THUNDERSTORMS THIS AFTERNOON.
&&
.PREV DISCUSSION...ISSUED 342 AM EDT TUE MAY 21 2013
SHORT TERM...TODAY AND TONIGHT
LINE OF THUNDERSTORMS CURRENTLY OVER NORTHERN ILLINOIS IS SLOWLY BUT
SURELY MARCHING NORTHEAST DURING THE EARLY MORNING HOURS. THE MAIN
QUESTION THIS MORNING IS HOW WELL THIS ACTIVITY WILL HOLD TOGETHER
AS IT TRACKS THROUGH SOUTHEAST MICHIGAN. HI-RES MODEL RUNS ARE IN
GENERAL AGREEMENT IN BRINGING THE SYSTEM THROUGH BETWEEN 09-13Z.
THAT IS WHERE THE AGREEMENT ENDS AS THE HRRR LIFTS THE BEST
THUNDERSTORM ACTIVITY NORTH THROUGH NORTHERN LOWER MICHIGAN WHILE
THE WRF MAINTAINS THE LINE OF STRONG THUNDERSTORMS AS IT TRACKS
THROUGH SOUTHEAST MICHIGAN...MAINLY NORTH OF THE M-59 CORRIDOR. THE
EVOLUTION OF THE JET STREAM WOULD VALIDATE THE HRRR SOLUTION AS IT
LIFTS THE 100+ KNOT JET NORTH OVER THE NORTHERN GREAT LAKES...TAKING
THE UPPER LEVEL DIVERGENCE AFFORDED BY THE RIGHT ENTRANCE REGION OF
THE JET WITH IT. HOWEVER LOWER LEVELS LEND CREDENCE TO THE WRF
SOLUTION AS THE MAIN SHORTWAVE DRIVING THE NORTHERN EDGE OF THE
CONVECTION IS PROGGED TO GO DIRECTLY THROUGH SOUTHEAST MICHIGAN WITH
THE NOSE OF THE 35 KNOT 850 MB LOW LEVEL JET POINTED OVER SOUTHEAST
MICHIGAN. DESPITE THE LOSS OF UPPER LEVEL JET SUPPORT...THE LOWER
LEVEL DYNAMICS POINT TO AN ACTIVE MORNING ACROSS SOUTHEAST MICHIGAN
WITH THE LINE OF CONVECTION EXPECTED TO SURVIVE THE TRIP AND TRACK
THROUGH THE AREA. THIS ACTIVITY WILL STILL HAVE QUITE A BIT OF
INSTABILITY TO WORK WITH AS MUCAPE VALUES REMAIN AT 1000 TO 1500
J/KG DURING THE EARLY MORNING HOURS. SEVERE WEATHER THREAT FROM THIS
MORNINGS CONVECTION WILL MAINLY BE A WIND THREAT...AS UPSTREAM
OBSERVATIONS SHOW LITTLE THREAT FROM LARGE HAIL...ALTHOUGH SMALL TO
NEAR SEVERE HAIL IS A POSSIBILITY.
AFTER THIS INITIAL ACTIVITY THE PICTURE BECOMES VERY MUDDLED AS THE
NWP MODELS KEEP SHOWERS AND THUNDERSTORMS GOING FOR MUCH OF THE DAY.
THIS SCENARIO IS CERTAINLY PLAUSIBLE AS ANOTHER JET STREAK LIFTS
FROM THE SOUTHWEST AND MAKES ITS WAY OVER THE GREAT LAKES REGION. AS
A RESULT THE AREA WILL BE IN THE PATH OF SEVERAL SHORTWAVES ROTATING
AROUND THE MAIN MID LEVEL LOW PRESSURE SYSTEM TAKING UP RESIDENCE
OVER THE MISSOURI VALLEY. WITHOUT A KEY FEATURE INDICATING THERE
WILL BE A SUBSTANTIAL BREAK FROM THE ACTION...DO NOT PLAN ON
DEVIATING MUCH FROM THE PREVIOUS FORECAST HIGH POPS THROUGH THE
DAYTIME HOURS.
SEVERE WEATHER POTENTIAL THIS AFTERNOON WILL HINGE ON THE ABILITY TO
GET A BREAK IN THE CONVECTION. THIS WINDOW WILL NOT HAVE TO BE
LARGE...AS EVIDENCED YESTERDAY...WITH A BRIEF BREAK ALLOWING
TEMPERATURES AND CAPES TO RISE SIGNIFICANTLY IN A SHORT PERIOD OF
TIME. MODELS SHOW MUCAPE VALUES RANGING FROM 500 TO 1000 J/KG WITH A
FAIRLY STEADY STREAM OF CONVECTION DURING THE DAY. AFTERNOON
SUNSHINE COULD EASILY BOOST THESE VALUES TO AROUND 1500 J/KG GIVEN
THE LATE MAY SUN ANGLE AND THE VERY WARM AIR IN THE LOW LEVELS. IN
ADDITION TO THE INSTABILITY...0-6 KM BULK SHEAR VALUES ARE A GOOD 30
TO 40 KNOTS TODAY...MEANING THE POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS PRODUCING DAMAGING WINDS AND LARGE HAIL ARE A
POSSIBILITY. CLOSER INSPECTION OF THE HODOGRAPH AND LOW LEVEL CAPE
SHOW ISOLATED TORNADOES WILL ALSO BE A THREAT...ESPECIALLY IF WE CAN
GET SOME SUNSHINE...AS 0-3KM CAPE VALUES REACH 150 TO 200 J/KG AND
STORM RELATIVE HELICITY VALUES GET TO 150 TO 200 M2/S2. ALL OF THIS
ACTIVITY MAKES FORECASTING HIGH TEMPERATURES TODAY QUITE
CHALLENGING. EVEN WITH ALL OF THE ACTIVITY WE SHOULD BE ABLE TO GET
INTO THE LOW 80S AWAY FROM THE GREAT LAKES...HOWEVER A FEW MID 80S
ARE A DISTINCT POSSIBILITY IF THE AFOREMENTIONED BREAK IN THE
ACTIVITY OCCURS.
OVERNIGHT MODELS ARE HINTING AT A BREAK IN THE CONVECTION AS THE
SECONDARY JET STREAM MOVES OFF TO THE NORTH WITH NVA PROGGED AT THE
500 MB LEVEL AS THE SURFACE LOW LIFTS OVER THE SOO. EVEN WITH THESE
FACTORS THERE IS ABUNDANT LOW LEVEL MOISTURE ACROSS SOUTHEAST
MICHIGAN...SO A COMPLETELY DRY FORECAST IS NOT IN THE CARDS AND
NEITHER IS A CONTINUATION OF THE HIGH POPS FROM TODAY. WITH ALL
THESE FACTORS IN MIND WILL MAINTAIN CHANCY POPS DURING THE OVERNIGHT
HOURS. ABUNDANT CLOUD COVER AND THE REGION STILL IN THE WARM SECTOR
WILL ONCE AGAIN LEAD TO A MILD NIGHT WITH OVERNIGHT LOWS EXPECTED IN
THE 60S.
LONG TERM...WEDNESDAY THROUGH MONDAY
UPPER LEVEL TROUGHING WILL KEEP MENTION OF SHOWERS AND THUNDERSTORMS
AROUND INTO THURSDAY WHICH IS WHEN THE MAIN TROUGH AXIS PASSES EAST
OF THE AREA ALLOWING HEIGHTS TO BUILD. MEANWHILE...COMPLEX SFC LOW
PRESSURE SYSTEM WILL WORK THROUGH LOWER MI ON WEDNESDAY AND THURSDAY
BEFORE A STRONG CANADIAN HIGH PRESSURE SYSTEM DROPS INTO THE GREAT
LAKES AND EXPANDS ACROSS MUCH OF THE EASTERN CONUS FOR THE HOLIDAY
WEEKEND. THIS WILL LEAD TO A DRY BUT COOL WEEKEND.
FIRST OFF WE WILL ADDRESS CONVECTIVE POTENTIAL FOR WEDNESDAY. THE
GFS POORLY INITIALIZES THE SFC LOW OVER THE NORTHERN PLAINS SO WILL
LEAN MORE TOWARD THE ECMWF/NAM/GEM REGIONAL. THE UPPER LEVEL LOW
THAT HAS BEEN SITTING OVER THE NORTHERN PLAINS FOR A FEW DAYS NOW
WILL PHASE WITH A NORTHERN STREAM TROUGH DIGGING SOUTH THROUGH
MANITOBA/ONTARIO ON WEDNESDAY. THIS WILL LEAD TO A MORE PROGRESSIVE
SYSTEM FINALLY. WITH THE CLOSED NATURE OF THE UPPER LOW...A FEW SFC
LOWS HAVE BEEN ROTATING AROUND EACH OTHER THE LAST TWO DAYS. AS THE
WAVE OPENS FURTHER AND THE UPPER JET TURNS WEST/EAST ACROSS NORTHERN
MI...THE MAIN SFC LOW WILL RELEASE AND TRACK ACROSS NORTHERN LOWER
MI THROUGH THE DAY WEDNESDAY. THIS WILL BE A BROAD WEAKENING LOW BUT
WILL PRESENT ISENTROPIC ASCENT AND WILL KEEP THE THETA E RIDGE UP
INTO SE MI. FOCUS WILL BE PLACED ON A SOUTHERN STREAM SHORTWAVE THAT
WILL ROUND THE BASE OF THE TROUGH AND TARGET LOWER MI WEDNESDAY
AFTERNOON. MODEL CONSENSUS SHOWS A SFC LOW CLIPPING EXTREME SE MI.
THIS WILL OPEN THE DOOR FOR ADDITIONAL HEATING AND MOISTURE INTO
THAT AREA DURING PEAK AFTERNOON HEATING WITH THE EASTWARD TRACKING
UPPER LEVEL JET MORE SQUARELY OVERHEAD. CONVECTIVE PARAMETERS ARE ON
THE DECLINE FROM MONDAY AND TUESDAY BUT THERE WILL STILL BE 500 TO
1000 J/KG OF TALL SKINNY MUCAPE WITH A COLD/COOL FRONT PASSING
THROUGH THE AREA IN THE EVENING. OVERALL WEDNESDAY LOOKS LIKE IT
WILL BE COMPOSED OF WIDESPREAD SHOWERS AND THUNDERSTORMS WITH A
CHANCE OF ORGANIZED CONVECTION ACROSS THE EXTREME SE PORTION OF THE
CWA.
UPPER LEVEL TROUGH AXIS WILL BE OVER WESTERN LOWER MI WEDNESDAY
NIGHT PROVIDING BROAD AREA OF LIFT ALOFT WITH THE BACK END OF THE
SFC LOW STILL LINGERING. THIS WILL KEEP SHOWERS AND THUNDERSTORMS
OVER MUCH OF LOWER MI THROUGH THE OVERNIGHT. THE AXIS WILL SWEEP
THROUGH SE MI EARLY ON THURSDAY LEADING TO A CLEARING TREND IN THE
SHOWERS THROUGH THE DAY FROM NW TO SE. MAIN BAROCLINIC ZONE THATS
BEEN LINGERING ACROSS THE NORTHERN GREAT LAKES WILL SURGE SOUTH ON
THURSDAY WITH STRONG CANADIAN HIGH PRESSURE RIGHT BEHIND IT. WITH
BUILDING HEIGHTS ALOFT...CLOUDS WILL CLEAR OUT BUT THAT WILL NOT BE
REALIZED IN TEMPERATURES. 850 MB TEMPS IN THE LOW SINGLE DIGITS WILL
ONLY ALLOW HIGH TEMPS TO REACH AROUND 60F BOTH THURSDAY AND FRIDAY
WITH LOWS AROUND 40. A SLOW WARMING TREND THROUGH THE WEEKEND WILL
ONLY ALLOW TEMPS TO REBOUND TO NEAR 70 FOR MONDAY AND TUESDAY.
THOUGH IT WILL BE COOL...AT LEAST IT LOOKS TO STAY DRY THOUGHT THE
HOLIDAY WEEKEND.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
UPDATE.......KURIMSKI
AVIATION.....KURIMSKI
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
727 AM EDT TUE MAY 21 2013
.AVIATION...
//DISCUSSION...
THE REGION OF THUNDERSTORMS THAT MOVED IN FROM ILLINOIS HAS HAD
LITTLE EFFECT OVER THE TAF SITES...AND WILL ONLY BRING SOME SHOWERS
TO KMBS EARLY THIS MORNING. THE EXTENT OF CLOUD COVER FROM THIS
COMPLEX WHICH MAY LINGER INTO THE AFTERNOON RAISES CONSIDERABLE
UNCERTAINTY WITH RESPECT TO THE CHANCES AND TIMING OF THUNDERSTORMS
LATER IN THE THIS AFTERNOON. BEST CHANCES FOR THUNDERSTORMS WILL BE
THIS AFTERNOON...THEREFORE WILL PUT A TEMPE GROUP IN THE 19-23Z TIME
FRAME WHEN THUNDERSTORMS ARE MOSTLY LIKELY TO OCCUR. A BREAK IN THE
ACTIVITY IS EXPECTED OVERNIGHT AS ONE OF THE SURFACE LOWS TRACKS
THROUGH THE NORTHERN GREAT LAKES.
FOR DTW...TIMING OF THUNDERSTORMS LATER IN THE DAY REMAINS HIGHLY
UNCERTAIN...THE BEST POTENTIAL WILL BE IN THE 19-23Z TIME FRAME WITH
MAX HEATING.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN THUNDERSTORMS THIS AFTERNOON.
&&
.PREV DISCUSSION...ISSUED 342 AM EDT TUE MAY 21 2013
SHORT TERM...TODAY AND TONIGHT
LINE OF THUNDERSTORMS CURRENTLY OVER NORTHERN ILLINOIS IS SLOWLY BUT
SURELY MARCHING NORTHEAST DURING THE EARLY MORNING HOURS. THE MAIN
QUESTION THIS MORNING IS HOW WELL THIS ACTIVITY WILL HOLD TOGETHER
AS IT TRACKS THROUGH SOUTHEAST MICHIGAN. HI-RES MODEL RUNS ARE IN
GENERAL AGREEMENT IN BRINGING THE SYSTEM THROUGH BETWEEN 09-13Z.
THAT IS WHERE THE AGREEMENT ENDS AS THE HRRR LIFTS THE BEST
THUNDERSTORM ACTIVITY NORTH THROUGH NORTHERN LOWER MICHIGAN WHILE
THE WRF MAINTAINS THE LINE OF STRONG THUNDERSTORMS AS IT TRACKS
THROUGH SOUTHEAST MICHIGAN...MAINLY NORTH OF THE M-59 CORRIDOR. THE
EVOLUTION OF THE JET STREAM WOULD VALIDATE THE HRRR SOLUTION AS IT
LIFTS THE 100+ KNOT JET NORTH OVER THE NORTHERN GREAT LAKES...TAKING
THE UPPER LEVEL DIVERGENCE AFFORDED BY THE RIGHT ENTRANCE REGION OF
THE JET WITH IT. HOWEVER LOWER LEVELS LEND CREDENCE TO THE WRF
SOLUTION AS THE MAIN SHORTWAVE DRIVING THE NORTHERN EDGE OF THE
CONVECTION IS PROGGED TO GO DIRECTLY THROUGH SOUTHEAST MICHIGAN WITH
THE NOSE OF THE 35 KNOT 850 MB LOW LEVEL JET POINTED OVER SOUTHEAST
MICHIGAN. DESPITE THE LOSS OF UPPER LEVEL JET SUPPORT...THE LOWER
LEVEL DYNAMICS POINT TO AN ACTIVE MORNING ACROSS SOUTHEAST MICHIGAN
WITH THE LINE OF CONVECTION EXPECTED TO SURVIVE THE TRIP AND TRACK
THROUGH THE AREA. THIS ACTIVITY WILL STILL HAVE QUITE A BIT OF
INSTABILITY TO WORK WITH AS MUCAPE VALUES REMAIN AT 1000 TO 1500
J/KG DURING THE EARLY MORNING HOURS. SEVERE WEATHER THREAT FROM THIS
MORNINGS CONVECTION WILL MAINLY BE A WIND THREAT...AS UPSTREAM
OBSERVATIONS SHOW LITTLE THREAT FROM LARGE HAIL...ALTHOUGH SMALL TO
NEAR SEVERE HAIL IS A POSSIBILITY.
AFTER THIS INITIAL ACTIVITY THE PICTURE BECOMES VERY MUDDLED AS THE
NWP MODELS KEEP SHOWERS AND THUNDERSTORMS GOING FOR MUCH OF THE DAY.
THIS SCENARIO IS CERTAINLY PLAUSIBLE AS ANOTHER JET STREAK LIFTS
FROM THE SOUTHWEST AND MAKES ITS WAY OVER THE GREAT LAKES REGION. AS
A RESULT THE AREA WILL BE IN THE PATH OF SEVERAL SHORTWAVES ROTATING
AROUND THE MAIN MID LEVEL LOW PRESSURE SYSTEM TAKING UP RESIDENCE
OVER THE MISSOURI VALLEY. WITHOUT A KEY FEATURE INDICATING THERE
WILL BE A SUBSTANTIAL BREAK FROM THE ACTION...DO NOT PLAN ON
DEVIATING MUCH FROM THE PREVIOUS FORECAST HIGH POPS THROUGH THE
DAYTIME HOURS.
SEVERE WEATHER POTENTIAL THIS AFTERNOON WILL HINGE ON THE ABILITY TO
GET A BREAK IN THE CONVECTION. THIS WINDOW WILL NOT HAVE TO BE
LARGE...AS EVIDENCED YESTERDAY...WITH A BRIEF BREAK ALLOWING
TEMPERATURES AND CAPES TO RISE SIGNIFICANTLY IN A SHORT PERIOD OF
TIME. MODELS SHOW MUCAPE VALUES RANGING FROM 500 TO 1000 J/KG WITH A
FAIRLY STEADY STREAM OF CONVECTION DURING THE DAY. AFTERNOON
SUNSHINE COULD EASILY BOOST THESE VALUES TO AROUND 1500 J/KG GIVEN
THE LATE MAY SUN ANGLE AND THE VERY WARM AIR IN THE LOW LEVELS. IN
ADDITION TO THE INSTABILITY...0-6 KM BULK SHEAR VALUES ARE A GOOD 30
TO 40 KNOTS TODAY...MEANING THE POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS PRODUCING DAMAGING WINDS AND LARGE HAIL ARE A
POSSIBILITY. CLOSER INSPECTION OF THE HODOGRAPH AND LOW LEVEL CAPE
SHOW ISOLATED TORNADOES WILL ALSO BE A THREAT...ESPECIALLY IF WE CAN
GET SOME SUNSHINE...AS 0-3KM CAPE VALUES REACH 150 TO 200 J/KG AND
STORM RELATIVE HELICITY VALUES GET TO 150 TO 200 M2/S2. ALL OF THIS
ACTIVITY MAKES FORECASTING HIGH TEMPERATURES TODAY QUITE
CHALLENGING. EVEN WITH ALL OF THE ACTIVITY WE SHOULD BE ABLE TO GET
INTO THE LOW 80S AWAY FROM THE GREAT LAKES...HOWEVER A FEW MID 80S
ARE A DISTINCT POSSIBILITY IF THE AFOREMENTIONED BREAK IN THE
ACTIVITY OCCURS.
OVERNIGHT MODELS ARE HINTING AT A BREAK IN THE CONVECTION AS THE
SECONDARY JET STREAM MOVES OFF TO THE NORTH WITH NVA PROGGED AT THE
500 MB LEVEL AS THE SURFACE LOW LIFTS OVER THE SOO. EVEN WITH THESE
FACTORS THERE IS ABUNDANT LOW LEVEL MOISTURE ACROSS SOUTHEAST
MICHIGAN...SO A COMPLETELY DRY FORECAST IS NOT IN THE CARDS AND
NEITHER IS A CONTINUATION OF THE HIGH POPS FROM TODAY. WITH ALL
THESE FACTORS IN MIND WILL MAINTAIN CHANCY POPS DURING THE OVERNIGHT
HOURS. ABUNDANT CLOUD COVER AND THE REGION STILL IN THE WARM SECTOR
WILL ONCE AGAIN LEAD TO A MILD NIGHT WITH OVERNIGHT LOWS EXPECTED IN
THE 60S.
LONG TERM...WEDNESDAY THROUGH MONDAY
UPPER LEVEL TROUGHING WILL KEEP MENTION OF SHOWERS AND THUNDERSTORMS
AROUND INTO THURSDAY WHICH IS WHEN THE MAIN TROUGH AXIS PASSES EAST
OF THE AREA ALLOWING HEIGHTS TO BUILD. MEANWHILE...COMPLEX SFC LOW
PRESSURE SYSTEM WILL WORK THROUGH LOWER MI ON WEDNESDAY AND THURSDAY
BEFORE A STRONG CANADIAN HIGH PRESSURE SYSTEM DROPS INTO THE GREAT
LAKES AND EXPANDS ACROSS MUCH OF THE EASTERN CONUS FOR THE HOLIDAY
WEEKEND. THIS WILL LEAD TO A DRY BUT COOL WEEKEND.
FIRST OFF WE WILL ADDRESS CONVECTIVE POTENTIAL FOR WEDNESDAY. THE
GFS POORLY INITIALIZES THE SFC LOW OVER THE NORTHERN PLAINS SO WILL
LEAN MORE TOWARD THE ECMWF/NAM/GEM REGIONAL. THE UPPER LEVEL LOW
THAT HAS BEEN SITTING OVER THE NORTHERN PLAINS FOR A FEW DAYS NOW
WILL PHASE WITH A NORTHERN STREAM TROUGH DIGGING SOUTH THROUGH
MANITOBA/ONTARIO ON WEDNESDAY. THIS WILL LEAD TO A MORE PROGRESSIVE
SYSTEM FINALLY. WITH THE CLOSED NATURE OF THE UPPER LOW...A FEW SFC
LOWS HAVE BEEN ROTATING AROUND EACH OTHER THE LAST TWO DAYS. AS THE
WAVE OPENS FURTHER AND THE UPPER JET TURNS WEST/EAST ACROSS NORTHERN
MI...THE MAIN SFC LOW WILL RELEASE AND TRACK ACROSS NORTHERN LOWER
MI THROUGH THE DAY WEDNESDAY. THIS WILL BE A BROAD WEAKENING LOW BUT
WILL PRESENT ISENTROPIC ASCENT AND WILL KEEP THE THETA E RIDGE UP
INTO SE MI. FOCUS WILL BE PLACED ON A SOUTHERN STREAM SHORTWAVE THAT
WILL ROUND THE BASE OF THE TROUGH AND TARGET LOWER MI WEDNESDAY
AFTERNOON. MODEL CONSENSUS SHOWS A SFC LOW CLIPPING EXTREME SE MI.
THIS WILL OPEN THE DOOR FOR ADDITIONAL HEATING AND MOISTURE INTO
THAT AREA DURING PEAK AFTERNOON HEATING WITH THE EASTWARD TRACKING
UPPER LEVEL JET MORE SQUARELY OVERHEAD. CONVECTIVE PARAMETERS ARE ON
THE DECLINE FROM MONDAY AND TUESDAY BUT THERE WILL STILL BE 500 TO
1000 J/KG OF TALL SKINNY MUCAPE WITH A COLD/COOL FRONT PASSING
THROUGH THE AREA IN THE EVENING. OVERALL WEDNESDAY LOOKS LIKE IT
WILL BE COMPOSED OF WIDESPREAD SHOWERS AND THUNDERSTORMS WITH A
CHANCE OF ORGANIZED CONVECTION ACROSS THE EXTREME SE PORTION OF THE
CWA.
UPPER LEVEL TROUGH AXIS WILL BE OVER WESTERN LOWER MI WEDNESDAY
NIGHT PROVIDING BROAD AREA OF LIFT ALOFT WITH THE BACK END OF THE
SFC LOW STILL LINGERING. THIS WILL KEEP SHOWERS AND THUNDERSTORMS
OVER MUCH OF LOWER MI THROUGH THE OVERNIGHT. THE AXIS WILL SWEEP
THROUGH SE MI EARLY ON THURSDAY LEADING TO A CLEARING TREND IN THE
SHOWERS THROUGH THE DAY FROM NW TO SE. MAIN BAROCLINIC ZONE THATS
BEEN LINGERING ACROSS THE NORTHERN GREAT LAKES WILL SURGE SOUTH ON
THURSDAY WITH STRONG CANADIAN HIGH PRESSURE RIGHT BEHIND IT. WITH
BUILDING HEIGHTS ALOFT...CLOUDS WILL CLEAR OUT BUT THAT WILL NOT BE
REALIZED IN TEMPERATURES. 850 MB TEMPS IN THE LOW SINGLE DIGITS WILL
ONLY ALLOW HIGH TEMPS TO REACH AROUND 60F BOTH THURSDAY AND FRIDAY
WITH LOWS AROUND 40. A SLOW WARMING TREND THROUGH THE WEEKEND WILL
ONLY ALLOW TEMPS TO REBOUND TO NEAR 70 FOR MONDAY AND TUESDAY.
THOUGH IT WILL BE COOL...AT LEAST IT LOOKS TO STAY DRY THOUGHT THE
HOLIDAY WEEKEND.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....KURIMSKI
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
342 AM EDT TUE MAY 21 2013
.SHORT TERM...TODAY AND TONIGHT
LINE OF THUNDERSTORMS CURRENTLY OVER NORTHERN ILLINOIS IS SLOWLY BUT
SURELY MARCHING NORTHEAST DURING THE EARLY MORNING HOURS. THE MAIN
QUESTION THIS MORNING IS HOW WELL THIS ACTIVITY WILL HOLD TOGETHER
AS IT TRACKS THROUGH SOUTHEAST MICHIGAN. HI-RES MODEL RUNS ARE IN
GENERAL AGREEMENT IN BRINGING THE SYSTEM THROUGH BETWEEN 09-13Z.
THAT IS WHERE THE AGREEMENT ENDS AS THE HRRR LIFTS THE BEST
THUNDERSTORM ACTIVITY NORTH THROUGH NORTHERN LOWER MICHIGAN WHILE
THE WRF MAINTAINS THE LINE OF STRONG THUNDERSTORMS AS IT TRACKS
THROUGH SOUTHEAST MICHIGAN...MAINLY NORTH OF THE M-59 CORRIDOR. THE
EVOLUTION OF THE JET STREAM WOULD VALIDATE THE HRRR SOLUTION AS IT
LIFTS THE 100+ KNOT JET NORTH OVER THE NORTHERN GREAT LAKES...TAKING
THE UPPER LEVEL DIVERGENCE AFFORDED BY THE RIGHT ENTRANCE REGION OF
THE JET WITH IT. HOWEVER LOWER LEVELS LEND CREDENCE TO THE WRF
SOLUTION AS THE MAIN SHORTWAVE DRIVING THE NORTHERN EDGE OF THE
CONVECTION IS PROGGED TO GO DIRECTLY THROUGH SOUTHEAST MICHIGAN WITH
THE NOSE OF THE 35 KNOT 850 MB LOW LEVEL JET POINTED OVER SOUTHEAST
MICHIGAN. DESPITE THE LOSS OF UPPER LEVEL JET SUPPORT...THE LOWER
LEVEL DYNAMICS POINT TO AN ACTIVE MORNING ACROSS SOUTHEAST MICHIGAN
WITH THE LINE OF CONVECTION EXPECTED TO SURVIVE THE TRIP AND TRACK
THROUGH THE AREA. THIS ACTIVITY WILL STILL HAVE QUITE A BIT OF
INSTABILITY TO WORK WITH AS MUCAPE VALUES REMAIN AT 1000 TO 1500
J/KG DURING THE EARLY MORNING HOURS. SEVERE WEATHER THREAT FROM THIS
MORNINGS CONVECTION WILL MAINLY BE A WIND THREAT...AS UPSTREAM
OBSERVATIONS SHOW LITTLE THREAT FROM LARGE HAIL...ALTHOUGH SMALL TO
NEAR SEVERE HAIL IS A POSSIBILITY.
AFTER THIS INITIAL ACTIVITY THE PICTURE BECOMES VERY MUDDLED AS THE
NWP MODELS KEEP SHOWERS AND THUNDERSTORMS GOING FOR MUCH OF THE DAY.
THIS SCENARIO IS CERTAINLY PLAUSIBLE AS ANOTHER JET STREAK LIFTS
FROM THE SOUTHWEST AND MAKES ITS WAY OVER THE GREAT LAKES REGION. AS
A RESULT THE AREA WILL BE IN THE PATH OF SEVERAL SHORTWAVES ROTATING
AROUND THE MAIN MID LEVEL LOW PRESSURE SYSTEM TAKING UP RESIDENCE
OVER THE MISSOURI VALLEY. WITHOUT A KEY FEATURE INDICATING THERE
WILL BE A SUBSTANTIAL BREAK FROM THE ACTION...DO NOT PLAN ON
DEVIATING MUCH FROM THE PREVIOUS FORECAST HIGH POPS THROUGH THE
DAYTIME HOURS.
SEVERE WEATHER POTENTIAL THIS AFTERNOON WILL HINGE ON THE ABILITY TO
GET A BREAK IN THE CONVECTION. THIS WINDOW WILL NOT HAVE TO BE
LARGE...AS EVIDENCED YESTERDAY...WITH A BRIEF BREAK ALLOWING
TEMPERATURES AND CAPES TO RISE SIGNIFICANTLY IN A SHORT PERIOD OF
TIME. MODELS SHOW MUCAPE VALUES RANGING FROM 500 TO 1000 J/KG WITH A
FAIRLY STEADY STREAM OF CONVECTION DURING THE DAY. AFTERNOON
SUNSHINE COULD EASILY BOOST THESE VALUES TO AROUND 1500 J/KG GIVEN
THE LATE MAY SUN ANGLE AND THE VERY WARM AIR IN THE LOW LEVELS. IN
ADDITION TO THE INSTABILITY...0-6 KM BULK SHEAR VALUES ARE A GOOD 30
TO 40 KNOTS TODAY...MEANING THE POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS PRODUCING DAMAGING WINDS AND LARGE HAIL ARE A
POSSIBILITY. CLOSER INSPECTION OF THE HODOGRAPH AND LOW LEVEL CAPE
SHOW ISOLATED TORNADOES WILL ALSO BE A THREAT...ESPECIALLY IF WE CAN
GET SOME SUNSHINE...AS 0-3KM CAPE VALUES REACH 150 TO 200 J/KG AND
STORM RELATIVE HELICITY VALUES GET TO 150 TO 200 M2/S2. ALL OF THIS
ACTIVITY MAKES FORECASTING HIGH TEMPERATURES TODAY QUITE
CHALLENGING. EVEN WITH ALL OF THE ACTIVITY WE SHOULD BE ABLE TO GET
INTO THE LOW 80S AWAY FROM THE GREAT LAKES...HOWEVER A FEW MID 80S
ARE A DISTINCT POSSIBILITY IF THE AFOREMENTIONED BREAK IN THE
ACTIVITY OCCURS.
OVERNIGHT MODELS ARE HINTING AT A BREAK IN THE CONVECTION AS THE
SECONDARY JET STREAM MOVES OFF TO THE NORTH WITH NVA PROGGED AT THE
500 MB LEVEL AS THE SURFACE LOW LIFTS OVER THE SOO. EVEN WITH THESE
FACTORS THERE IS ABUNDANT LOW LEVEL MOISTURE ACROSS SOUTHEAST
MICHIGAN...SO A COMPLETELY DRY FORECAST IS NOT IN THE CARDS AND
NEITHER IS A CONTINUATION OF THE HIGH POPS FROM TODAY. WITH ALL
THESE FACTORS IN MIND WILL MAINTAIN CHANCY POPS DURING THE OVERNIGHT
HOURS. ABUNDANT CLOUD COVER AND THE REGION STILL IN THE WARM SECTOR
WILL ONCE AGAIN LEAD TO A MILD NIGHT WITH OVERNIGHT LOWS EXPECTED IN
THE 60S.
&&
.LONG TERM...WEDNESDAY THROUGH MONDAY
UPPER LEVEL TROUGHING WILL KEEP MENTION OF SHOWERS AND THUNDERSTORMS
AROUND INTO THURSDAY WHICH IS WHEN THE MAIN TROUGH AXIS PASSES EAST
OF THE AREA ALLOWING HEIGHTS TO BUILD. MEANWHILE...COMPLEX SFC LOW
PRESSURE SYSTEM WILL WORK THROUGH LOWER MI ON WEDNESDAY AND THURSDAY
BEFORE A STRONG CANADIAN HIGH PRESSURE SYSTEM DROPS INTO THE GREAT
LAKES AND EXPANDS ACROSS MUCH OF THE EASTERN CONUS FOR THE HOLIDAY
WEEKEND. THIS WILL LEAD TO A DRY BUT COOL WEEKEND.
FIRST OFF WE WILL ADDRESS CONVECTIVE POTENTIAL FOR WEDNESDAY. THE
GFS POORLY INITIALIZES THE SFC LOW OVER THE NORTHERN PLAINS SO WILL
LEAN MORE TOWARD THE ECMWF/NAM/GEM REGIONAL. THE UPPER LEVEL LOW
THAT HAS BEEN SITTING OVER THE NORTHERN PLAINS FOR A FEW DAYS NOW
WILL PHASE WITH A NORTHERN STREAM TROUGH DIGGING SOUTH THROUGH
MANITOBA/ONTARIO ON WEDNESDAY. THIS WILL LEAD TO A MORE PROGRESSIVE
SYSTEM FINALLY. WITH THE CLOSED NATURE OF THE UPPER LOW...A FEW SFC
LOWS HAVE BEEN ROTATING AROUND EACH OTHER THE LAST TWO DAYS. AS THE
WAVE OPENS FURTHER AND THE UPPER JET TURNS WEST/EAST ACROSS NORTHERN
MI...THE MAIN SFC LOW WILL RELEASE AND TRACK ACROSS NORTHERN LOWER
MI THROUGH THE DAY WEDNESDAY. THIS WILL BE A BROAD WEAKENING LOW BUT
WILL PRESENT ISENTROPIC ASCENT AND WILL KEEP THE THETA E RIDGE UP
INTO SE MI. FOCUS WILL BE PLACED ON A SOUTHERN STREAM SHORTWAVE THAT
WILL ROUND THE BASE OF THE TROUGH AND TARGET LOWER MI WEDNESDAY
AFTERNOON. MODEL CONSENSUS SHOWS A SFC LOW CLIPPING EXTREME SE MI.
THIS WILL OPEN THE DOOR FOR ADDITIONAL HEATING AND MOISTURE INTO
THAT AREA DURING PEAK AFTERNOON HEATING WITH THE EASTWARD TRACKING
UPPER LEVEL JET MORE SQUARELY OVERHEAD. CONVECTIVE PARAMETERS ARE ON
THE DECLINE FROM MONDAY AND TUESDAY BUT THERE WILL STILL BE 500 TO
1000 J/KG OF TALL SKINNY MUCAPE WITH A COLD/COOL FRONT PASSING
THROUGH THE AREA IN THE EVENING. OVERALL WEDNESDAY LOOKS LIKE IT
WILL BE COMPOSED OF WIDESPREAD SHOWERS AND THUNDERSTORMS WITH A
CHANCE OF ORGANIZED CONVECTION ACROSS THE EXTREME SE PORTION OF THE
CWA.
UPPER LEVEL TROUGH AXIS WILL BE OVER WESTERN LOWER MI WEDNESDAY
NIGHT PROVIDING BROAD AREA OF LIFT ALOFT WITH THE BACK END OF THE
SFC LOW STILL LINGERING. THIS WILL KEEP SHOWERS AND THUNDERSTORMS
OVER MUCH OF LOWER MI THROUGH THE OVERNIGHT. THE AXIS WILL SWEEP
THROUGH SE MI EARLY ON THURSDAY LEADING TO A CLEARING TREND IN THE
SHOWERS THROUGH THE DAY FROM NW TO SE. MAIN BAROCLINIC ZONE THATS
BEEN LINGERING ACROSS THE NORTHERN GREAT LAKES WILL SURGE SOUTH ON
THURSDAY WITH STRONG CANADIAN HIGH PRESSURE RIGHT BEHIND IT. WITH
BUILDING HEIGHTS ALOFT...CLOUDS WILL CLEAR OUT BUT THAT WILL NOT BE
REALIZED IN TEMPERATURES. 850 MB TEMPS IN THE LOW SINGLE DIGITS WILL
ONLY ALLOW HIGH TEMPS TO REACH AROUND 60F BOTH THURSDAY AND FRIDAY
WITH LOWS AROUND 40. A SLOW WARMING TREND THROUGH THE WEEKEND WILL
ONLY ALLOW TEMPS TO REBOUND TO NEAR 70 FOR MONDAY AND TUESDAY.
THOUGH IT WILL BE COOL...AT LEAST IT LOOKS TO STAY DRY THOUGHT THE
HOLIDAY WEEKEND.
&&
.MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.AVIATION...ISSUED 1151 PM EDT MON MAY 20 2013
//DISCUSSION...
THE REGION OF THUNDERSTORMS ACROSS ILLINOIS WILL LIFT N-NE DURING
THE EARLY MORNING HOURS. ADDITIONAL CONVECTIVE DEVELOPMENT IS
POSSIBLE OUT AHEAD OF THIS CLUSTER WITHIN A SECONDARY SURGE IN
MOISTURE...TRAVERSING SE MI IN THE 09Z TO 15Z TIME FRAME. THIS WILL
SUPPORT THE INCLUSION OF SOME THUNDERSTORMS IN THE TAFS AROUND
DAYBREAK. THE COVERAGE OF MORNING CONVECTIVE ACTIVITY AND EXTENT OF
CLOUD COVER WHICH MAY LINGER INTO THE AFTERNOON RAISES CONSIDERABLE
UNCERTAINTY WITH RESPECT TO THE CHANCES AND TIMING OF THUNDERSTORMS
LATER IN THE DAY TUESDAY.
FOR DTW...GIVEN THE EASTWARD EXTENT OF CONVECTION ONGOING ACROSS
ILLINOIS...CHANCES OF SOME THUNDERSTORM ACTIVITY IN AND AROUND METRO
APPEAR HIGH ENOUGH TO ADD THEIR INCLUSION IN THE TAFS DURING THE 11
TO 14Z TIME FRAME. ALTHOUGH TIMING OF ADDITIONAL THUNDERSTORMS LATER
IN THE DAY TUESDAY REMAINS HIGHLY UNCERTAIN...THERE IS THE POTENTIAL
FOR SEVERAL ROUNDS OF THUNDERSTORMS TO IMPACT METRO ON TUESDAY.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN THUNDERSTORMS TUESDAY MORNING AND AFTERNOON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
AVIATION.....SC
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
912 AM MDT TUE MAY 21 2013
.UPDATE...
LARGE UPPER LOW OVER THE EASTERN DAKOTAS WILL CONTINUE TO ROTATE
CLOUDS WESTWARD ACROSS EASTERN MONTANA TODAY. RAIN SHOWERS WILL
CONTINUE TO BE POSSIBLE MAINLY EAST OF A MILES CITY TO BROADUS
LINE TODAY BUT THESE WILL BE SHIFTING EAST BY LATE AFTERNOON.
EXPECT A MOSTLY SUNNY AND MILDER DAY TODAY FOR THE REMAINDER OF
THE FORECAST AREA. PATCHY FOG WILL CONTINUE FOR THIS MORNING FOR
THE LIVINGSTON AREA BUT THIS HAS BEEN BREAKING UP DURING THE PAST
HOUR. CURRENT FORECAST IN GOOD SHAPE WITH NO UPDATES PLANNED THIS
MORNING. HOOLEY
&&
.SHORT TERM...VALID FOR TDY AND WED...
THE WEEKEND RAIN-MAKER WILL CONTINUE EXITING STAGE RIGHT...LEAVING
EASTERLY LOW-LEVEL FLOW IN PLAY THE NEXT SEVERAL DAYS OUT AHEAD OF
A 500-HPA LOW WHICH MOVES INTO THE PACIFIC NORTHWEST. THIS PATTERN
WILL YIELD SEASONABLE TEMPERATURES...AND SOME CHANCE OF STORMS FOR
SOUTH CENTRAL MT...ESPECIALLY LATER ON WED AND WED NIGHT.
TODAY...EARLY-MORNING RADAR TRENDS SUGGEST THAT LIKELY POPS REMAIN
NECESSARY AROUND BAKER AND EKALAKA INTO THE MORNING TO ACCOUNT FOR
RESIDUAL BANDS OF SHOWERS ROTATING WESTWARD INTO THAT AREA. THE 00
UTC GUIDANCE IS CLOSELY CLUSTERED IN ITS QPF OUTPUT...AND IT SHOWS
A SHARP WESTERN GRADIENT TO THE SHOWERS DICTATED BY A WEDGE OF DRY
AIR OVER CENTRAL MT. SURFACE OBSERVATIONS AS OF 09 UTC SUGGEST THE
LOW- AND MID-LEVEL DRYING IS BEGINNING TO INFLUENCE THE MILES CITY
AREA...AND MOST 00 UTC GUIDANCE KEEPS SHOWERS EAST OF THERE TODAY.
EVEN RECENT RAP RUNS AND THE 06 UTC NAM KEEP SHOWERS EAST OF MILES
CITY SO WE WENT WITH A DRY FORECAST THERE THIS MORNING. POPS OVER
THE BAKER AND EKALAKA AREAS DROP BACK TO THE CHANCE CATEGORY AFTER
18 UTC AS WELL SINCE MID-LEVEL FORCING AND MOISTURE ADVECTION WILL
BE WEAKENING BY THAT TIME. OTHERWISE...THE EASTERLY LOW-LEVEL FLOW
WILL BECOME ESTABLISHED OVER MUCH OF THE AREA BY AFTERNOON...WHICH
COULD HELP ASSIST WITH SOME CUMULUS DEVELOPMENT GIVEN THE RESIDUAL
NEAR-SURFACE MOISTURE AFTER WEEKEND RAINFALL. THERE IS JUST ENOUGH
INSTABILITY FORECAST BY THE 00 UTC GUIDANCE OVER THE MOUNTAINS FOR
US TO INCLUDE SLIGHT CHANCES OF CONVECTION AFTER 18 UTC THERE TOO.
HIGHS TODAY WERE LARGELY BASED ON A CONSENSUS OF 00 UTC MOS AS THE
EASTERLY FLOW WILL TEND TO LIMIT MIXING...AND USING BIAS-CORRECTED
FLAVORS OF GUIDANCE SEEMS A BIT DANGEROUS GIVEN NEW SOIL MOISTURE.
TONIGHT...QUIET CONDITIONS SHOULD PREVAIL...AND IN FACT BASED ON A
BLEND OF 00 UTC MOS OUTPUT...LOWS WILL PROBABLY BE BELOW NORMAL IN
MANY SPOTS. WE HAVE A DRY FORECAST IN PLAY AFTER 06 UTC EXCEPT FOR
EXTREME SOUTHEASTERN MT. WE WILL NEED TO BE MINDFULL FOR POTENTIAL
FOG DEVELOPMENT...BUT IT SEEMS THAT NEAR-SURFACE FLOW MIGHT END UP
STAYING JUST STRONG ENOUGH TO PREVENT ITS FORMATION...SO IT IS NOT
IN THE FORECAST AT THIS POINT.
WED INTO WED NIGHT...A BETTER CHANCE OF CONVECTION WILL EXIST OVER
SOUTH CENTRAL MT AS MID-LEVEL LAPSE RATES STEEPEN TO AROUND 7 C/KM
ON STRENGTHENING SOUTHERLY FLOW ALOFT. MOST 00 UTC MODEL SOLUTIONS
GENERATE CONVECTION TOWARD 00 UTC...SO OUR GOING CHANCE-STYLE POPS
ARE CERTAINLY WARRANTED. THE ONLY QUESTION MARK MIGHT BE TIMING OR
EASTWARD EXTENT OF THE WEAK SHORT WAVE THAT GUIDANCE KEYS IN ON TO
YIELD CONVECTION...ESPECIALLY SINCE THE MERIDIONAL FLOW MIGHT TAKE
IT FURTHER WEST THAN EXPECTED. THERE IS PROBABLY A NON-ZERO THREAT
OF SEVERE WEATHER IF STORMS DEVELOP...BUT IT WILL BE KEPT IN CHECK
BY A LACK OF BUOYANCY /MUCAPE 500 J/KG OR LESS/. OVER SOUTHEASTERN
MT...STORM CHANCES ARE MINIMAL OWING TO MID-LEVEL RIDGING. SCHULTZ
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
MEDIUM RANGE MODELS WERE PRETTY CONSISTENT THROUGH THE PERIOD
WITH SOME TIMING DIFFERENCES OF SHORTWAVES PROGGED TO GET KICKED
OUT OF A DEEP UPPER TROUGH OVER THE WEST MOVING INLAND.
THURSDAY COULD BE AN ACTIVE DAY FOR THUNDERSTORMS...MAINLY
CENTRAL AND WESTERN ZONES. THE DEEP WESTERN TROUGH ADVANCES EAST
SLOWLY AND LOWERS HEIGHTS THROUGH THE DAY. LOW LEVEL EAST TO
SOUTHEAST WINDS WILL ALLOW FOR DEWPOINTS TO HANG AROUND 50 DEGREES
OVER CENTRAL ZONES...WITH SLIGHTLY LOWER VALUES OVER THE WEST.
EFFECTIVE BULK SHEAR INCREASES TO AROUND 35KTS WITH CAPES REACHING
AS HIGH AS 1000 J/KG. STRONG SURFACE CONVERGENCE WITH SHORTWAVE
ENERGY WILL IGNITE THUNDERSTORMS OVER WESTERN ZONES IN THE
AFTERNOON. STORMS WILL MOVE NORTH TO NORTHEAST AND KICK OUT OF THE
FORECAST FAIRLY QUICKLY IN THE EVENING. SHEAR WOULD BE STRONG
ENOUGH TO PRODUCE SOME STRONG STORMS WITH THE MAIN THREAT BEING
HAIL. WILL HAVE TO WATCH THIS EVENT FOR A POSSIBLE SEVERE WEATHER
DAY. WILL MENTION STRONG STORMS IN THE HWO.
FRIDAY IS A DAY A BIT IN QUESTION AS MODELS DIFFER ON TIMING AND
STRENGTH OF A SHORTWAVE KICKING OFF THE MAIN LOW TO THE WEST. THE
ECMWF WAS STRONGEST AND SLOWEST WITH THIS WAVE AS IT CROSSES THE
FORECAST AREA DURING THE DAY. THE GFS WAS WEAKER AND TAKES IT
ACROSS LATE THURSDAY NIGHT. THE ECMWF WOULD BE WETTER. INHERITED
SCATTERED POPS FOR FRIDAY...BUT IF THE GFS WAS RIGHT...IT WILL BE
DRIER.
DRIER MID LEVEL AIR WILL RUSH IN BEHIND THE SHORTWAVE REGARDLESS
OF THE TIMING. THIS WILL SET UP A MAINLY DRY PERIOD FOR THE
WEEKEND WITH THE MAIN ENERGY STAYING NORTH. HIGH BASED SHOWERS OR
THUNDERSTORMS CAN NOT BE RULED OUT OVER THE WEEKEND THOUGH AS
MODELS KICK DISTURBANCES ACROSS IN SOUTHWEST FLOW. DEWPOINTS
SHOULD BE MUCH LOWER AND THESE SHOWERS WILL NOT CONTAIN A GREAT
DEAL OF PRECIPITATION AND BE MORE WIND PRODUCERS. WILL KEEP POPS
LOW. TEMPERATURES SHOULD SLIGHTLY ABOVE SEASONAL AVERAGES THROUGH
PERIOD. TWH
&&
.AVIATION...
SOME LINGERING SHOWERS OVER KBHK SHOULD DISSIPATE BY THE EARLY
AFTERNOON. FOG IS SLOWLY LIFTING NEAR KLVM...BUT STILL MAY CAUSE
SOME IMPACTS...SO UPDATED THE KLVM TAF TO INCLUDE ONE MORE HOUR OF
LOWERED VISIBILITIES DUE TO FOG. THE REST OF THE AREA SHOULD
REMAIN UNDER VFR CONDITIONS TODAY...HOWEVER THERE IS A CHANCE FOR
AN ISOLATED SHOWER OR THUNDERSTORM...MOSTLY NEAR THE HIGHER
TERRAIN. SINGER
&&
.PRELIMINARY POINT TEMP/POPS...
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 067 043/068 047/074 050/075 048/077 051/077 051/073
1/B 12/T 33/T 43/T 22/T 22/T 23/T
LVM 069 039/067 044/065 041/068 040/075 041/076 042/070
1/F 14/T 45/T 43/T 22/T 22/T 23/T
HDN 069 043/070 048/077 050/078 048/079 051/080 051/076
1/B 12/T 33/T 33/T 22/T 22/T 23/T
MLS 059 044/067 047/073 053/075 051/078 055/078 054/076
1/E 11/B 11/N 23/T 22/T 23/T 33/T
4BQ 056 040/065 046/074 052/076 050/079 053/080 052/077
3/W 11/B 11/N 13/T 22/T 23/T 33/T
BHK 050 040/061 043/067 050/070 050/075 053/073 052/073
7/W 21/N 11/N 13/T 22/T 33/T 33/T
SHR 061 037/068 045/075 049/075 046/078 048/079 048/075
1/B 12/T 32/T 23/T 22/T 22/T 23/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
613 AM MDT TUE MAY 21 2013
.UPDATE...
WE HAVE UPDATED THE FORECAST TO INCLUDE PATCHY DENSE FOG FOR PARTS
OF SOUTH CENTRAL MT THIS MORNING. LIGHT WINDS AND A MOIST BOUNDARY
LAYER ARE CONTRIBUTING TO FOG AS OF 12 UTC...ESPECIALLY AROUND THE
LIVINGSTON AREA WHERE VISIBILITY HAS FALLEN TO LESS THAN A QUARTER
MILE. THE FOG SHOULD BURN OFF BY MID TO LATE MORNING ONCE THE LOW-
LEVELS WARM WITH SUNSHINE. SCHULTZ
&&
.SHORT TERM...VALID FOR TDY AND WED...
THE WEEKEND RAIN-MAKER WILL CONTINUE EXITING STAGE RIGHT...LEAVING
EASTERLY LOW-LEVEL FLOW IN PLAY THE NEXT SEVERAL DAYS OUT AHEAD OF
A 500-HPA LOW WHICH MOVES INTO THE PACIFIC NORTHWEST. THIS PATTERN
WILL YIELD SEASONABLE TEMPERATURES...AND SOME CHANCE OF STORMS FOR
SOUTH CENTRAL MT...ESPECIALLY LATER ON WED AND WED NIGHT.
TODAY...EARLY-MORNING RADAR TRENDS SUGGEST THAT LIKELY POPS REMAIN
NECESSARY AROUND BAKER AND EKALAKA INTO THE MORNING TO ACCOUNT FOR
RESIDUAL BANDS OF SHOWERS ROTATING WESTWARD INTO THAT AREA. THE 00
UTC GUIDANCE IS CLOSELY CLUSTERED IN ITS QPF OUTPUT...AND IT SHOWS
A SHARP WESTERN GRADIENT TO THE SHOWERS DICTATED BY A WEDGE OF DRY
AIR OVER CENTRAL MT. SURFACE OBSERVATIONS AS OF 09 UTC SUGGEST THE
LOW- AND MID-LEVEL DRYING IS BEGINNING TO INFLUENCE THE MILES CITY
AREA...AND MOST 00 UTC GUIDANCE KEEPS SHOWERS EAST OF THERE TODAY.
EVEN RECENT RAP RUNS AND THE 06 UTC NAM KEEP SHOWERS EAST OF MILES
CITY SO WE WENT WITH A DRY FORECAST THERE THIS MORNING. POPS OVER
THE BAKER AND EKALAKA AREAS DROP BACK TO THE CHANCE CATEGORY AFTER
18 UTC AS WELL SINCE MID-LEVEL FORCING AND MOISTURE ADVECTION WILL
BE WEAKENING BY THAT TIME. OTHERWISE...THE EASTERLY LOW-LEVEL FLOW
WILL BECOME ESTABLISHED OVER MUCH OF THE AREA BY AFTERNOON...WHICH
COULD HELP ASSIST WITH SOME CUMULUS DEVELOPMENT GIVEN THE RESIDUAL
NEAR-SURFACE MOISTURE AFTER WEEKEND RAINFALL. THERE IS JUST ENOUGH
INSTABILITY FORECAST BY THE 00 UTC GUIDANCE OVER THE MOUNTAINS FOR
US TO INCLUDE SLIGHT CHANCES OF CONVECTION AFTER 18 UTC THERE TOO.
HIGHS TODAY WERE LARGELY BASED ON A CONSENSUS OF 00 UTC MOS AS THE
EASTERLY FLOW WILL TEND TO LIMIT MIXING...AND USING BIAS-CORRECTED
FLAVORS OF GUIDANCE SEEMS A BIT DANGEROUS GIVEN NEW SOIL MOISTURE.
TONIGHT...QUIET CONDITIONS SHOULD PREVAIL...AND IN FACT BASED ON A
BLEND OF 00 UTC MOS OUTPUT...LOWS WILL PROBABLY BE BELOW NORMAL IN
MANY SPOTS. WE HAVE A DRY FORECAST IN PLAY AFTER 06 UTC EXCEPT FOR
EXTREME SOUTHEASTERN MT. WE WILL NEED TO BE MINDFULL FOR POTENTIAL
FOG DEVELOPMENT...BUT IT SEEMS THAT NEAR-SURFACE FLOW MIGHT END UP
STAYING JUST STRONG ENOUGH TO PREVENT ITS FORMATION...SO IT IS NOT
IN THE FORECAST AT THIS POINT.
WED INTO WED NIGHT...A BETTER CHANCE OF CONVECTION WILL EXIST OVER
SOUTH CENTRAL MT AS MID-LEVEL LAPSE RATES STEEPEN TO AROUND 7 C/KM
ON STRENGTHENING SOUTHERLY FLOW ALOFT. MOST 00 UTC MODEL SOLUTIONS
GENERATE CONVECTION TOWARD 00 UTC...SO OUR GOING CHANCE-STYLE POPS
ARE CERTAINLY WARRANTED. THE ONLY QUESTION MARK MIGHT BE TIMING OR
EASTWARD EXTENT OF THE WEAK SHORT WAVE THAT GUIDANCE KEYS IN ON TO
YIELD CONVECTION...ESPECIALLY SINCE THE MERIDIONAL FLOW MIGHT TAKE
IT FURTHER WEST THAN EXPECTED. THERE IS PROBABLY A NON-ZERO THREAT
OF SEVERE WEATHER IF STORMS DEVELOP...BUT IT WILL BE KEPT IN CHECK
BY A LACK OF BUOYANCY /MUCAPE 500 J/KG OR LESS/. OVER SOUTHEASTERN
MT...STORM CHANCES ARE MINIMAL OWING TO MID-LEVEL RIDGING. SCHULTZ
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
MEDIUM RANGE MODELS WERE PRETTY CONSISTENT THROUGH THE PERIOD
WITH SOME TIMING DIFFERENCES OF SHORTWAVES PROGGED TO GET KICKED
OUT OF A DEEP UPPER TROUGH OVER THE WEST MOVING INLAND.
THURSDAY COULD BE AN ACTIVE DAY FOR THUNDERSTORMS...MAINLY
CENTRAL AND WESTERN ZONES. THE DEEP WESTERN TROUGH ADVANCES EAST
SLOWLY AND LOWERS HEIGHTS THROUGH THE DAY. LOW LEVEL EAST TO
SOUTHEAST WINDS WILL ALLOW FOR DEWPOINTS TO HANG AROUND 50 DEGREES
OVER CENTRAL ZONES...WITH SLIGHTLY LOWER VALUES OVER THE WEST.
EFFECTIVE BULK SHEAR INCREASES TO AROUND 35KTS WITH CAPES REACHING
AS HIGH AS 1000 J/KG. STRONG SURFACE CONVERGENCE WITH SHORTWAVE
ENERGY WILL IGNITE THUNDERSTORMS OVER WESTERN ZONES IN THE
AFTERNOON. STORMS WILL MOVE NORTH TO NORTHEAST AND KICK OUT OF THE
FORECAST FAIRLY QUICKLY IN THE EVENING. SHEAR WOULD BE STRONG
ENOUGH TO PRODUCE SOME STRONG STORMS WITH THE MAIN THREAT BEING
HAIL. WILL HAVE TO WATCH THIS EVENT FOR A POSSIBLE SEVERE WEATHER
DAY. WILL MENTION STRONG STORMS IN THE HWO.
FRIDAY IS A DAY A BIT IN QUESTION AS MODELS DIFFER ON TIMING AND
STRENGTH OF A SHORTWAVE KICKING OFF THE MAIN LOW TO THE WEST. THE
ECMWF WAS STRONGEST AND SLOWEST WITH THIS WAVE AS IT CROSSES THE
FORECAST AREA DURING THE DAY. THE GFS WAS WEAKER AND TAKES IT
ACROSS LATE THURSDAY NIGHT. THE ECMWF WOULD BE WETTER. INHERITED
SCATTERED POPS FOR FRIDAY...BUT IF THE GFS WAS RIGHT...IT WILL BE
DRIER.
DRIER MID LEVEL AIR WILL RUSH IN BEHIND THE SHORTWAVE REGARDLESS
OF THE TIMING. THIS WILL SET UP A MAINLY DRY PERIOD FOR THE
WEEKEND WITH THE MAIN ENERGY STAYING NORTH. HIGH BASED SHOWERS OR
THUNDERSTORMS CAN NOT BE RULED OUT OVER THE WEEKEND THOUGH AS
MODELS KICK DISTURBANCES ACROSS IN SOUTHWEST FLOW. DEWPOINTS
SHOULD BE MUCH LOWER AND THESE SHOWERS WILL NOT CONTAIN A GREAT
DEAL OF PRECIPITATION AND BE MORE WIND PRODUCERS. WILL KEEP POPS
LOW. TEMPERATURES SHOULD SLIGHTLY ABOVE SEASONAL AVERAGES THROUGH
PERIOD. TWH
&&
.AVIATION...
SHOWERS WILL LINGER OVER THE EAST THIS MORNING AND TAPER OFF
THROUGH THE AFTERNOON. THE PRECIPITATION SHOULD STAY MAINLY EAST
OF KMLS AND IMPACT KBHK. FLYING CONDITIONS ARE EXPECTED TO REMAIN
VFR WITH ONLY ISOLATED MVFR CONDITIONS DEVELOPING IN HEAVIER
SHOWERS. THE REST OF THE AREA WILL HAVE A PARTLY CLOUDY SKY WITH
ONLY ISOLATED SHOWERS AND THUNDERSTORMS NEAREST THE MOUNTAINS. TWH
&&
.PRELIMINARY POINT TEMP/POPS...
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 067 043/068 047/074 050/075 048/077 051/077 051/073
1/B 12/T 33/T 43/T 22/T 22/T 23/T
LVM 069 039/067 044/065 041/068 040/075 041/076 042/070
1/F 14/T 45/T 43/T 22/T 22/T 23/T
HDN 069 043/070 048/077 050/078 048/079 051/080 051/076
1/B 12/T 33/T 33/T 22/T 22/T 23/T
MLS 059 044/067 047/073 053/075 051/078 055/078 054/076
1/E 11/B 11/N 23/T 22/T 23/T 33/T
4BQ 056 040/065 046/074 052/076 050/079 053/080 052/077
3/W 11/B 11/N 13/T 22/T 23/T 33/T
BHK 050 040/061 043/067 050/070 050/075 053/073 052/073
7/W 21/N 11/N 13/T 22/T 33/T 33/T
SHR 061 037/068 045/075 049/075 046/078 048/079 048/075
1/B 12/T 32/T 23/T 22/T 22/T 23/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BILLINGS MT
357 AM MDT TUE MAY 21 2013
.SHORT TERM...VALID FOR TDY AND WED...
THE WEEKEND RAIN-MAKER WILL CONTINUE EXITING STAGE RIGHT...LEAVING
EASTERLY LOW-LEVEL FLOW IN PLAY THE NEXT SEVERAL DAYS OUT AHEAD OF
A 500-HPA LOW WHICH MOVES INTO THE PACIFIC NORTHWEST. THIS PATTERN
WILL YIELD SEASONABLE TEMPERATURES...AND SOME CHANCE OF STORMS FOR
SOUTH CENTRAL MT...ESPECIALLY LATER ON WED AND WED NIGHT.
TODAY...EARLY-MORNING RADAR TRENDS SUGGEST THAT LIKELY POPS REMAIN
NECESSARY AROUND BAKER AND EKALAKA INTO THE MORNING TO ACCOUNT FOR
RESIDUAL BANDS OF SHOWERS ROTATING WESTWARD INTO THAT AREA. THE 00
UTC GUIDANCE IS CLOSELY CLUSTERED IN ITS QPF OUTPUT...AND IT SHOWS
A SHARP WESTERN GRADIENT TO THE SHOWERS DICTATED BY A WEDGE OF DRY
AIR OVER CENTRAL MT. SURFACE OBSERVATIONS AS OF 09 UTC SUGGEST THE
LOW- AND MID-LEVEL DRYING IS BEGINNING TO INFLUENCE THE MILES CITY
AREA...AND MOST 00 UTC GUIDANCE KEEPS SHOWERS EAST OF THERE TODAY.
EVEN RECENT RAP RUNS AND THE 06 UTC NAM KEEP SHOWERS EAST OF MILES
CITY SO WE WENT WITH A DRY FORECAST THERE THIS MORNING. POPS OVER
THE BAKER AND EKALAKA AREAS DROP BACK TO THE CHANCE CATEGORY AFTER
18 UTC AS WELL SINCE MID-LEVEL FORCING AND MOISTURE ADVECTION WILL
BE WEAKENING BY THAT TIME. OTHERWISE...THE EASTERLY LOW-LEVEL FLOW
WILL BECOME ESTABLISHED OVER MUCH OF THE AREA BY AFTERNOON...WHICH
COULD HELP ASSIST WITH SOME CUMULUS DEVELOPMENT GIVEN THE RESIDUAL
NEAR-SURFACE MOISTURE AFTER WEEKEND RAINFALL. THERE IS JUST ENOUGH
INSTABILITY FORECAST BY THE 00 UTC GUIDANCE OVER THE MOUNTAINS FOR
US TO INCLUDE SLIGHT CHANCES OF CONVECTION AFTER 18 UTC THERE TOO.
HIGHS TODAY WERE LARGELY BASED ON A CONSENSUS OF 00 UTC MOS AS THE
EASTERLY FLOW WILL TEND TO LIMIT MIXING...AND USING BIAS-CORRECTED
FLAVORS OF GUIDANCE SEEMS A BIT DANGEROUS GIVEN NEW SOIL MOISTURE.
TONIGHT...QUIET CONDITIONS SHOULD PREVAIL...AND IN FACT BASED ON A
BLEND OF 00 UTC MOS OUTPUT...LOWS WILL PROBABLY BE BELOW NORMAL IN
MANY SPOTS. WE HAVE A DRY FORECAST IN PLAY AFTER 06 UTC EXCEPT FOR
EXTREME SOUTHEASTERN MT. WE WILL NEED TO BE MINDFULL FOR POTENTIAL
FOG DEVELOPMENT...BUT IT SEEMS THAT NEAR-SURFACE FLOW MIGHT END UP
STAYING JUST STRONG ENOUGH TO PREVENT ITS FORMATION...SO IT IS NOT
IN THE FORECAST AT THIS POINT.
WED INTO WED NIGHT...A BETTER CHANCE OF CONVECTION WILL EXIST OVER
SOUTH CENTRAL MT AS MID-LEVEL LAPSE RATES STEEPEN TO AROUND 7 C/KM
ON STRENGTHENING SOUTHERLY FLOW ALOFT. MOST 00 UTC MODEL SOLUTIONS
GENERATE CONVECTION TOWARD 00 UTC...SO OUR GOING CHANCE-STYLE POPS
ARE CERTAINLY WARRANTED. THE ONLY QUESTION MARK MIGHT BE TIMING OR
EASTWARD EXTENT OF THE WEAK SHORT WAVE THAT GUIDANCE KEYS IN ON TO
YIELD CONVECTION...ESPECIALLY SINCE THE MERIDIONAL FLOW MIGHT TAKE
IT FURTHER WEST THAN EXPECTED. THERE IS PROBABLY A NON-ZERO THREAT
OF SEVERE WEATHER IF STORMS DEVELOP...BUT IT WILL BE KEPT IN CHECK
BY A LACK OF BUOYANCY /MUCAPE 500 J/KG OR LESS/. OVER SOUTHEASTERN
MT...STORM CHANCES ARE MINIMAL OWING TO MID-LEVEL RIDGING. SCHULTZ
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
MEDIUM RANGE MODELS WERE PRETTY CONSISTENT THROUGH THE PERIOD
WITH SOME TIMING DIFFERENCES OF SHORTWAVES PROGGED TO GET KICKED
OUT OF A DEEP UPPER TROUGH OVER THE WEST MOVING INLAND.
THURSDAY COULD BE AN ACTIVE DAY FOR THUNDERSTORMS...MAINLY
CENTRAL AND WESTERN ZONES. THE DEEP WESTERN TROUGH ADVANCES EAST
SLOWLY AND LOWERS HEIGHTS THROUGH THE DAY. LOW LEVEL EAST TO
SOUTHEAST WINDS WILL ALLOW FOR DEWPOINTS TO HANG AROUND 50 DEGREES
OVER CENTRAL ZONES...WITH SLIGHTLY LOWER VALUES OVER THE WEST.
EFFECTIVE BULK SHEAR INCREASES TO AROUND 35KTS WITH CAPES REACHING
AS HIGH AS 1000 J/KG. STRONG SURFACE CONVERGENCE WITH SHORTWAVE
ENERGY WILL IGNITE THUNDERSTORMS OVER WESTERN ZONES IN THE
AFTERNOON. STORMS WILL MOVE NORTH TO NORTHEAST AND KICK OUT OF THE
FORECAST FAIRLY QUICKLY IN THE EVENING. SHEAR WOULD BE STRONG
ENOUGH TO PRODUCE SOME STRONG STORMS WITH THE MAIN THREAT BEING
HAIL. WILL HAVE TO WATCH THIS EVENT FOR A POSSIBLE SEVERE WEATHER
DAY. WILL MENTION STRONG STORMS IN THE HWO.
FRIDAY IS A DAY A BIT IN QUESTION AS MODELS DIFFER ON TIMING AND
STRENGTH OF A SHORTWAVE KICKING OFF THE MAIN LOW TO THE WEST. THE
ECMWF WAS STRONGEST AND SLOWEST WITH THIS WAVE AS IT CROSSES THE
FORECAST AREA DURING THE DAY. THE GFS WAS WEAKER AND TAKES IT
ACROSS LATE THURSDAY NIGHT. THE ECMWF WOULD BE WETTER. INHERITED
SCATTERED POPS FOR FRIDAY...BUT IF THE GFS WAS RIGHT...IT WILL BE
DRIER.
DRIER MID LEVEL AIR WILL RUSH IN BEHIND THE SHORTWAVE REGARDLESS
OF THE TIMING. THIS WILL SET UP A MAINLY DRY PERIOD FOR THE
WEEKEND WITH THE MAIN ENERGY STAYING NORTH. HIGH BASED SHOWERS OR
THUNDERSTORMS CAN NOT BE RULED OUT OVER THE WEEKEND THOUGH AS
MODELS KICK DISTURBANCES ACROSS IN SOUTHWEST FLOW. DEWPOINTS
SHOULD BE MUCH LOWER AND THESE SHOWERS WILL NOT CONTAIN A GREAT
DEAL OF PRECIPITATION AND BE MORE WIND PRODUCERS. WILL KEEP POPS
LOW. TEMPERATURES SHOULD SLIGHTLY ABOVE SEASONAL AVERAGES THROUGH
PERIOD. TWH
&&
.AVIATION...
SHOWERS WILL LINGER OVER THE EAST THIS MORNING AND TAPER OFF
THROUGH THE AFTERNOON. THE PRECIPITATION SHOULD STAY MAINLY EAST
OF KMLS AND IMPACT KBHK. FLYING CONDITIONS ARE EXPECTED TO REMAIN
VFR WITH ONLY ISOLATED MVFR CONDITIONS DEVELOPING IN HEAVIER
SHOWERS. THE REST OF THE AREA WILL HAVE A PARTLY CLOUDY SKY WITH
ONLY ISOLATED SHOWERS AND THUNDERSTORMS NEAREST THE MOUNTAINS. TWH
&&
.PRELIMINARY POINT TEMP/POPS...
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 067 043/068 047/074 050/075 048/077 051/077 051/073
1/B 12/T 33/T 43/T 22/T 22/T 23/T
LVM 069 039/067 044/065 041/068 040/075 041/076 042/070
1/B 14/T 45/T 43/T 22/T 22/T 23/T
HDN 069 043/070 048/077 050/078 048/079 051/080 051/076
1/B 12/T 33/T 33/T 22/T 22/T 23/T
MLS 059 044/067 047/073 053/075 051/078 055/078 054/076
1/E 11/B 11/N 23/T 22/T 23/T 33/T
4BQ 056 040/065 046/074 052/076 050/079 053/080 052/077
3/W 11/B 11/N 13/T 22/T 23/T 33/T
BHK 050 040/061 043/067 050/070 050/075 053/073 052/073
7/W 21/N 11/N 13/T 22/T 33/T 33/T
SHR 061 037/068 045/075 049/075 046/078 048/079 048/075
1/B 12/T 32/T 23/T 22/T 22/T 23/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1235 PM CDT TUE MAY 21 2013
.UPDATE...
ISSUED AT 1019 AM CDT TUE MAY 21 2013
FORECAST HAS BEEN UPDATED FOR WINDS THROUGH THE DAY. SURFACE LOW
CENTERED OVER EAST CENTRAL SOUTH DAKOTA THIS MORNING HAS ENHANCED
THE PRESSURE GRADIENT OVER NEBRASKA...WITH WINDS NOW BLOWING AT 20
TO 30 MPH WITH GUSTS UP TOWARDS 40 MPH IN PLACES. MODELS ARE
INDICATING WINDS WILL PEAK FROM NOW THROUGH AROUND 20Z...THEN AS
THE LOW SHIFTS EAST...THE STRONGER WINDS WILL SHIFT EASTWARD AS
WELL. AFTERNOON MIXING...WITH STRONG WINDS JUST ABOVE THE SURFACE
WILL KEEP THE WINDS UP THROUGH THE AFTERNOON...WITH A DECREASING
TREND THIS EVENING. THERE ARE A FEW SPOTS THAT HAVE BRIEFLY
REACHED WIND ADVISORY CRITERIA...BUT THINKING THIS WILL NOT BE
WIDESPREAD ENOUGH...OR WITH LONG ENOUGH DURATION AND WILL BE RIGHT
AT THE LOWER THRESHOLD FOR A WIND ADVISORY IF LOCATIONS DO HIT
ADVISORY CRITERIA WITH SUSTAINED AT 30 MPH AND GUSTS OVER 40 MPH.
OTHERWISE...TEMPERATURES ARE ON TREND...WITH HIGHS ONLY EXPECTED
IN THE UPPER 50S AND LOW 60S AS QUITE A BIT OF CLOUD COVER WILL BE
IN PLACE THROUGH THE DAY. ISOLATED TO SCATTERED LIGHT SHOWERS IN
THE FORECAST ARE ALSO ON TRACK AS THEY ROTATE AROUND THE LOW
PRESSURE SYSTEM. SO NO CHANGES IN THE PRECIPITATION FORECAST FOR
THE DAY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 357 AM CDT TUE MAY 21 2013
TODAY AND TONIGHT...
MORE WRAP AROUND CLOUDINESS AND SHOWERS ARE EXPECTED TODAY HOWEVER
THE RADAR RETURNS ARE NOT NEARLY AS PROLIFIC AS THEY WERE SUNDAY
NIGHT AND MONDAY. THUS RAINFALL SHOULD BE LIGHT WITH TOTALS OF 1/10
OF AN INCH. THE LOW PRESSURE SYSTEM ACROSS THE NRN PLAINS IS FCST TO
FILL AND WOBBLE SOUTH THROUGH SWRN MN AND NRN IA TODAY AND THEN OPEN
UP TONIGHT. THE SHOWERS/LIGHT RAIN WOULD THEN PUSH AS FAR SOUTH AS
HIGHWAY 2 DURING THE DAY TODAY AND THEN LIFT NORTHEAST TONIGHT.
WINDS CONTINUE STRONG TODAY BUT SHOULD REMAIN BELOW 30 MPH. THE RAP
IS SUGGESTING THE STRONGEST WINDS NEAR KVTN AND A BLEND OF THE MAV
AND MET GUIDANCE KEEPS THE WINDS BELOW ADVISORY CRITERIA. THIS AREA
WILL BE UNDER THE STRONGEST SFC PRESSURE GRADIENT BUT THE RAP 500M
AGL WINDS ARE AROUND 26 KTS WHICH EQUATES TO 26 MPH AT THE SFC.
WINDS ARE ALSO FCST TO WEAKEN MID TO LATE AFTN.
VERY COOL HIGHS ARE EXPECTED TODAY IN THE CLOUDINESS AND COOL AIR
ALOFT. LOWER 50S TO MID 60S IS ALL WE WILL MANAGE AND LOWS TONIGHT
FALL INTO THE 40S WITH UPPER 30S ACROSS THE ERN PANHANDLE.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 357 AM CDT TUE MAY 21 2013
WEDNESDAY THROUGH THURSDAY NIGHT...
AS UPPER LOW MOVES SLOWLY ACROSS IOWA ON WEDNESDAY...STILL SUPPORTIVE
OF A FEW SHOWERS IN THE NORTHEAST WEDNESDAY MORNING. MOISTURE WILL
BECOME SHALLOWER THROUGH THE DAY AND VERY LITTLE LIFT INDICATED.
AS SURFACE HIGH BUILDS IN...WINDS WILL VEER TO THE NORTH AND BE
LIGHTER THAN THE PAST FEW DAYS AT 5 TO 15 MPH. AN UPPER RIDGE WILL
ALSO BUILD INTO THE CNTRL ROCKIES WEDNESDAY IN RESPONSE TO A
SUBSTANTIAL CLOSED LOW DIGGING INTO THE PAC NW. TIME SECTIONS
INDICATE PARTLY CLOUDY SOUTHWESTERN HALF OF FA...WHILE NORTHEAST
TO STAY OVERCAST. ONLY A MINOR CHANGE TO HIGHS WEDNESDAY FROM
60-64 NCTRL TO 65-72 SOUTHWEST. EASTERLY UPSLOPE WINDS WEDNESDAY
NIGHT MAY RESULT IN STRATUS AND/OR FOG DEVELOPMENT. FOR THURSDAY...
THE UPPER RIDGE AXIS WILL BECOME CENTERED ACROSS THE CENTRAL U.S.
SURFACE HIGH PRESSURE BUILDING INTO THE NRN AND CNTRL MISSISSIPPI
VALLEY TO BRING INCREASING SOUTHEAST WINDS 15 TO 25 MPH. LOOKS
PARTLY CLOUDY WEST TO MOSTLY SUNNY EAST. WITH ABSENCE OF STRATUS
TEMPERATURES WILL WARM UP MOST ACROSS THE NORTH CENTRAL INTO THE
UPPER 60S...WHILE THE SOUTHWEST SIMILAR IN THE UPPER 60S/NEAR 70.
NEXT CHANCE FOR SHOWERS/THUNDERSTORM THURSDAY NIGHT AS GULF
MOISTURE RETURNS NORTH UP THE HIGH PLAINS. PRONOUNCED
SOUTHWESTERLY FLOW ALOFT INTO WESTERN NEBRASKA SUPPORTIVE OF 20-30
POPS SOUTHWESTERN HALF OF FA.
FRIDAY THROUGH MONDAY...
AN UNSETTLED WEATHER PATTERN WILL SET UP AS AN UPPER TROUGH
REMAINS ACROSS THE WESTERN U.S AND A RIDGE ACROSS THE CENTRAL
CONUS. ABUNDANT LOW LEVEL MOISTURE WILL INCREASE WITH H85
DEWPOINTS FROM 12-15C AT TIMES FRIDAY THROUGH SUNDAY. LOCATION OF
THE SURFACE FRONT NOT IN VERY GOOD AGREEMENT. STILL...THE PRESENCE OF
A NOCTURNAL LOW LEVEL JET WILL ALLOW FOR THUNDERSTORMS TO POSSIBLY
DEVELOP INTO AN MCS ACROSS THE REGION EACH NIGHT. HIGHS IN THE 70S
FRIDAY WILL WARM TO THE UPPER 70S TO MID 80S SATURDAY THROUGH
MONDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1234 PM CDT TUE MAY 21 2013
WINDS WILL STAY BREEZY TO STRONG AT TIMES ACROSS MUCH OF WESTERN
AND NORTH CENTRAL NEBRASKA THROUGH EARLY THIS EVENING. WINDS WILL
STAY A BIT HIGHER OVER NORTH CENTRAL NEBRASKA OVERNIGHT AS THE
AREA OF LOW PRESSURE...OVER EASTERN SOUTH DAKOTA THIS AFTERNOON
MOVES EASTWARD THROUGH WEDNESDAY MORNING. THE LIGHT RAIN SHOWERS
ACROSS THE AREA WILL CONTINUE TO ROTATE AROUND THIS LOW PRESSURE
SYSTEM...WHICH WILL KEEP ISOLATED TO SCATTERED SHOWERS TO
LOCATIONS...MAINLY NORTH OF INTERSTATE 80 THROUGH EARLY
EVENING...AND POSSIBLY IN AREAS EAST OF A KVTN TO KBBW LINE
TONIGHT. CLOUDS WILL REMAIN ACROSS MUCH OF THE AREA
OVERNIGHT...WITH HIGH PRESSURE BUILDING INTO THE REGION ON
WEDNESDAY. MVFR CEILINGS LOOK LIKELY OVER WESTERN INTO SOUTHWEST
NEBRASKA THROUGH MID MORNING WEDNESDAY...WHILE IFR CEILINGS AND
MAYBE SOME 4SM VISIBILITIES ARE LOOKING LIKELY OVER NORTH CENTRAL
NEBRASKA THROUGH THE SAME TIME FRAME. AS THE SURFACE HIGH BUILDS
IN ON WEDNESDAY...CONDITIONS WILL IMPROVE FROM WEST TO EAST.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BROOKS
SHORT TERM...CDC
LONG TERM...ROBERG
AVIATION...BROOKS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1020 AM CDT TUE MAY 21 2013
.UPDATE...
ISSUED AT 1019 AM CDT TUE MAY 21 2013
FORECAST HAS BEEN UPDATED FOR WINDS THROUGH THE DAY. SURFACE LOW
CENTERED OVER EAST CENTRAL SOUTH DAKOTA THIS MORNING HAS ENHANCED
THE PRESSURE GRADIENT OVER NEBRASKA...WITH WINDS NOW BLOWING AT 20
TO 30 MPH WITH GUSTS UP TOWARDS 40 MPH IN PLACES. MODELS ARE
INDICATING WINDS WILL PEAK FROM NOW THROUGH AROUND 20Z...THEN AS
THE LOW SHIFTS EAST...THE STRONGER WINDS WILL SHIFT EASTWARD AS
WELL. AFTERNOON MIXING...WITH STRONG WINDS JUST ABOVE THE SURFACE
WILL KEEP THE WINDS UP THROUGH THE AFTERNOON...WITH A DECREASING
TREND THIS EVENING. THERE ARE A FEW SPOTS THAT HAVE BRIEFLY
REACHED WIND ADVISORY CRITERIA...BUT THINKING THIS WILL NOT BE
WIDESPREAD ENOUGH...OR WITH LONG ENOUGH DURATION AND WILL BE RIGHT
AT THE LOWER THRESHOLD FOR A WIND ADVISORY IF LOCATIONS DO HIT
ADVISORY CRITERIA WITH SUSTAINED AT 30 MPH AND GUSTS OVER 40 MPH.
OTHERWISE...TEMPERATURES ARE ON TREND...WITH HIGHS ONLY EXPECTED
IN THE UPPER 50S AND LOW 60S AS QUITE A BIT OF CLOUD COVER WILL BE
IN PLACE THROUGH THE DAY. ISOLATED TO SCATTERED LIGHT SHOWERS IN
THE FORECAST ARE ALSO ON TRACK AS THEY ROTATE AROUND THE LOW
PRESSURE SYSTEM. SO NO CHANGES IN THE PRECIPITATION FORECAST FOR
THE DAY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 357 AM CDT TUE MAY 21 2013
TODAY AND TONIGHT...
MORE WRAP AROUND CLOUDINESS AND SHOWERS ARE EXPECTED TODAY HOWEVER
THE RADAR RETURNS ARE NOT NEARLY AS PROLIFIC AS THEY WERE SUNDAY
NIGHT AND MONDAY. THUS RAINFALL SHOULD BE LIGHT WITH TOTALS OF 1/10
OF AN INCH. THE LOW PRESSURE SYSTEM ACROSS THE NRN PLAINS IS FCST TO
FILL AND WOBBLE SOUTH THROUGH SWRN MN AND NRN IA TODAY AND THEN OPEN
UP TONIGHT. THE SHOWERS/LIGHT RAIN WOULD THEN PUSH AS FAR SOUTH AS
HIGHWAY 2 DURING THE DAY TODAY AND THEN LIFT NORTHEAST TONIGHT.
WINDS CONTINUE STRONG TODAY BUT SHOULD REMAIN BELOW 30 MPH. THE RAP
IS SUGGESTING THE STRONGEST WINDS NEAR KVTN AND A BLEND OF THE MAV
AND MET GUIDANCE KEEPS THE WINDS BELOW ADVISORY CRITERIA. THIS AREA
WILL BE UNDER THE STRONGEST SFC PRESSURE GRADIENT BUT THE RAP 500M
AGL WINDS ARE AROUND 26 KTS WHICH EQUATES TO 26 MPH AT THE SFC.
WINDS ARE ALSO FCST TO WEAKEN MID TO LATE AFTN.
VERY COOL HIGHS ARE EXPECTED TODAY IN THE CLOUDINESS AND COOL AIR
ALOFT. LOWER 50S TO MID 60S IS ALL WE WILL MANAGE AND LOWS TONIGHT
FALL INTO THE 40S WITH UPPER 30S ACROSS THE ERN PANHANDLE.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 357 AM CDT TUE MAY 21 2013
WEDNESDAY THROUGH THURSDAY NIGHT...
AS UPPER LOW MOVES SLOWLY ACROSS IOWA ON WEDNESDAY...STILL SUPPORTIVE
OF A FEW SHOWERS IN THE NORTHEAST WEDNESDAY MORNING. MOISTURE WILL
BECOME SHALLOWER THROUGH THE DAY AND VERY LITTLE LIFT INDICATED.
AS SURFACE HIGH BUILDS IN...WINDS WILL VEER TO THE NORTH AND BE
LIGHTER THAN THE PAST FEW DAYS AT 5 TO 15 MPH. AN UPPER RIDGE WILL
ALSO BUILD INTO THE CNTRL ROCKIES WEDNESDAY IN RESPONSE TO A
SUBSTANTIAL CLOSED LOW DIGGING INTO THE PAC NW. TIME SECTIONS
INDICATE PARTLY CLOUDY SOUTHWESTERN HALF OF FA...WHILE NORTHEAST
TO STAY OVERCAST. ONLY A MINOR CHANGE TO HIGHS WEDNESDAY FROM
60-64 NCTRL TO 65-72 SOUTHWEST. EASTERLY UPSLOPE WINDS WEDNESDAY
NIGHT MAY RESULT IN STRATUS AND/OR FOG DEVELOPMENT. FOR THURSDAY...
THE UPPER RIDGE AXIS WILL BECOME CENTERED ACROSS THE CENTRAL U.S.
SURFACE HIGH PRESSURE BUILDING INTO THE NRN AND CNTRL MISSISSIPPI
VALLEY TO BRING INCREASING SOUTHEAST WINDS 15 TO 25 MPH. LOOKS
PARTLY CLOUDY WEST TO MOSTLY SUNNY EAST. WITH ABSENCE OF STRATUS
TEMPERATURES WILL WARM UP MOST ACROSS THE NORTH CENTRAL INTO THE
UPPER 60S...WHILE THE SOUTHWEST SIMILAR IN THE UPPER 60S/NEAR 70.
NEXT CHANCE FOR SHOWERS/THUNDERSTORM THURSDAY NIGHT AS GULF
MOISTURE RETURNS NORTH UP THE HIGH PLAINS. PRONOUNCED
SOUTHWESTERLY FLOW ALOFT INTO WESTERN NEBRASKA SUPPORTIVE OF 20-30
POPS SOUTHWESTERN HALF OF FA.
FRIDAY THROUGH MONDAY...
AN UNSETTLED WEATHER PATTERN WILL SET UP AS AN UPPER TROUGH
REMAINS ACROSS THE WESTERN U.S AND A RIDGE ACROSS THE CENTRAL
CONUS. ABUNDANT LOW LEVEL MOISTURE WILL INCREASE WITH H85
DEWPOINTS FROM 12-15C AT TIMES FRIDAY THROUGH SUNDAY. LOCATION OF
THE SURFACE FRONT NOT IN VERY GOOD AGREEMENT. STILL...THE PRESENCE OF
A NOCTURNAL LOW LEVEL JET WILL ALLOW FOR THUNDERSTORMS TO POSSIBLY
DEVELOP INTO AN MCS ACROSS THE REGION EACH NIGHT. HIGHS IN THE 70S
FRIDAY WILL WARM TO THE UPPER 70S TO MID 80S SATURDAY THROUGH
MONDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 626 AM CDT TUE MAY 21 2013
MVFR CIGS SHOULD CONTINUE ALONG AND NORTH OF NEBRASKA HIGHWAY 2 TODAY
AND TONIGHT IN PERIODS OF LIGHT RAIN OR DRIZZLE. SOUTH OF HIGHWAY
2...GENERALLY VFR IS EXPECTED TODAY THROUGH TONIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BROOKS
SHORT TERM...CDC
LONG TERM...ROBERG
AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
628 AM CDT TUE MAY 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 357 AM CDT TUE MAY 21 2013
TODAY AND TONIGHT...
MORE WRAP AROUND CLOUDINESS AND SHOWERS ARE EXPECTED TODAY HOWEVER
THE RADAR RETURNS ARE NOT NEARLY AS PROLIFIC AS THEY WERE SUNDAY
NIGHT AND MONDAY. THUS RAINFALL SHOULD BE LIGHT WITH TOTALS OF 1/10
OF AN INCH. THE LOW PRESSURE SYSTEM ACROSS THE NRN PLAINS IS FCST TO
FILL AND WOBBLE SOUTH THROUGH SWRN MN AND NRN IA TODAY AND THEN OPEN
UP TONIGHT. THE SHOWERS/LIGHT RAIN WOULD THEN PUSH AS FAR SOUTH AS
HIGHWAY 2 DURING THE DAY TODAY AND THEN LIFT NORTHEAST TONIGHT.
WINDS CONTINUE STRONG TODAY BUT SHOULD REMAIN BELOW 30 MPH. THE RAP
IS SUGGESTING THE STRONGEST WINDS NEAR KVTN AND A BLEND OF THE MAV
AND MET GUIDANCE KEEPS THE WINDS BELOW ADVISORY CRITERIA. THIS AREA
WILL BE UNDER THE STRONGEST SFC PRESSURE GRADIENT BUT THE RAP 500M
AGL WINDS ARE AROUND 26 KTS WHICH EQUATES TO 26 MPH AT THE SFC.
WINDS ARE ALSO FCST TO WEAKEN MID TO LATE AFTN.
VERY COOL HIGHS ARE EXPECTED TODAY IN THE CLOUDINESS AND COOL AIR
ALOFT. LOWER 50S TO MID 60S IS ALL WE WILL MANAGE AND LOWS TONIGHT
FALL INTO THE 40S WITH UPPER 30S ACROSS THE ERN PANHANDLE.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 357 AM CDT TUE MAY 21 2013
WEDNESDAY THROUGH THURSDAY NIGHT...
AS UPPER LOW MOVES SLOWLY ACROSS IOWA ON WEDNESDAY...STILL SUPPORTIVE
OF A FEW SHOWERS IN THE NORTHEAST WEDNESDAY MORNING. MOISTURE WILL
BECOME SHALLOWER THROUGH THE DAY AND VERY LITTLE LIFT INDICATED.
AS SURFACE HIGH BUILDS IN...WINDS WILL VEER TO THE NORTH AND BE
LIGHTER THAN THE PAST FEW DAYS AT 5 TO 15 MPH. AN UPPER RIDGE WILL
ALSO BUILD INTO THE CNTRL ROCKIES WEDNESDAY IN RESPONSE TO A
SUBSTANTIAL CLOSED LOW DIGGING INTO THE PAC NW. TIME SECTIONS
INDICATE PARTLY CLOUDY SOUTHWESTERN HALF OF FA...WHILE NORTHEAST
TO STAY OVERCAST. ONLY A MINOR CHANGE TO HIGHS WEDNESDAY FROM
60-64 NCTRL TO 65-72 SOUTHWEST. EASTERLY UPSLOPE WINDS WEDNESDAY
NIGHT MAY RESULT IN STRATUS AND/OR FOG DEVELOPMENT. FOR THURSDAY...
THE UPPER RIDGE AXIS WILL BECOME CENTERED ACROSS THE CENTRAL U.S.
SURFACE HIGH PRESSURE BUILDING INTO THE NRN AND CNTRL MISSISSIPPI
VALLEY TO BRING INCREASING SOUTHEAST WINDS 15 TO 25 MPH. LOOKS
PARTLY CLOUDY WEST TO MOSTLY SUNNY EAST. WITH ABSENCE OF STRATUS
TEMPERATURES WILL WARM UP MOST ACROSS THE NORTH CENTRAL INTO THE
UPPER 60S...WHILE THE SOUTHWEST SIMILAR IN THE UPPER 60S/NEAR 70.
NEXT CHANCE FOR SHOWERS/THUNDERSTORM THURSDAY NIGHT AS GULF
MOISTURE RETURNS NORTH UP THE HIGH PLAINS. PRONOUNCED
SOUTHWESTERLY FLOW ALOFT INTO WESTERN NEBRASKA SUPPORTIVE OF 20-30
POPS SOUTHWESTERN HALF OF FA.
FRIDAY THROUGH MONDAY...
AN UNSETTLED WEATHER PATTERN WILL SET UP AS AN UPPER TROUGH
REMAINS ACROSS THE WESTERN U.S AND A RIDGE ACROSS THE CENTRAL
CONUS. ABUNDANT LOW LEVEL MOISTURE WILL INCREASE WITH H85
DEWPOINTS FROM 12-15C AT TIMES FRIDAY THROUGH SUNDAY. LOCATION OF
THE SURFACE FRONT NOT IN VERY GOOD AGREEMENT. STILL...THE PRESENCE OF
A NOCTURNAL LOW LEVEL JET WILL ALLOW FOR THUNDERSTORMS TO POSSIBLY
DEVELOP INTO AN MCS ACROSS THE REGION EACH NIGHT. HIGHS IN THE 70S
FRIDAY WILL WARM TO THE UPPER 70S TO MID 80S SATURDAY THROUGH
MONDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 626 AM CDT TUE MAY 21 2013
MVFR CIGS SHOULD CONTINUE ALONG AND NORTH OF NEBRASKA HIGHWAY 2 TODAY
AND TONIGHT IN PERIODS OF LIGHT RAIN OR DRIZZLE. SOUTH OF HIGHWAY
2...GENERALLY VFR IS EXPECTED TODAY THROUGH TONIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...ROBERG
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
358 AM CDT TUE MAY 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 357 AM CDT TUE MAY 21 2013
TODAY AND TONIGHT...
MORE WRAP AROUND CLOUDINESS AND SHOWERS ARE EXPECTED TODAY HOWEVER
THE RADAR RETURNS ARE NOT NEARLY AS PROLIFIC AS THEY WERE SUNDAY
NIGHT AND MONDAY. THUS RAINFALL SHOULD BE LIGHT WITH TOTALS OF 1/10
OF AN INCH. THE LOW PRESSURE SYSTEM ACROSS THE NRN PLAINS IS FCST TO
FILL AND WOBBLE SOUTH THROUGH SWRN MN AND NRN IA TODAY AND THEN OPEN
UP TONIGHT. THE SHOWERS/LIGHT RAIN WOULD THEN PUSH AS FAR SOUTH AS
HIGHWAY 2 DURING THE DAY TODAY AND THEN LIFT NORTHEAST TONIGHT.
WINDS CONTINUE STRONG TODAY BUT SHOULD REMAIN BELOW 30 MPH. THE RAP
IS SUGGESTING THE STRONGEST WINDS NEAR KVTN AND A BLEND OF THE MAV
AND MET GUIDANCE KEEPS THE WINDS BELOW ADVISORY CRITERIA. THIS AREA
WILL BE UNDER THE STRONGEST SFC PRESSURE GRADIENT BUT THE RAP 500M
AGL WINDS ARE AROUND 26 KTS WHICH EQUATES TO 26 MPH AT THE SFC.
WINDS ARE ALSO FCST TO WEAKEN MID TO LATE AFTN.
VERY COOL HIGHS ARE EXPECTED TODAY IN THE CLOUDINESS AND COOL AIR
ALOFT. LOWER 50S TO MID 60S IS ALL WE WILL MANAGE AND LOWS TONIGHT
FALL INTO THE 40S WITH UPPER 30S ACROSS THE ERN PANHANDLE.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 357 AM CDT TUE MAY 21 2013
WEDNESDAY THROUGH THURSDAY NIGHT...
AS UPPER LOW MOVES SLOWLY ACROSS IOWA ON WEDNESDAY...STILL SUPPORTIVE
OF A FEW SHOWERS IN THE NORTHEAST WEDNESDAY MORNING. MOISTURE WILL
BECOME SHALLOWER THROUGH THE DAY AND VERY LITTLE LIFT INDICATED.
AS SURFACE HIGH BUILDS IN...WINDS WILL VEER TO THE NORTH AND BE
LIGHTER THAN THE PAST FEW DAYS AT 5 TO 15 MPH. AN UPPER RIDGE WILL
ALSO BUILD INTO THE CNTRL ROCKIES WEDNESDAY IN RESPONSE TO A
SUBSTANTIAL CLOSED LOW DIGGING INTO THE PAC NW. TIME SECTIONS
INDICATE PARTLY CLOUDY SOUTHWESTERN HALF OF FA...WHILE NORTHEAST
TO STAY OVERCAST. ONLY A MINOR CHANGE TO HIGHS WEDNESDAY FROM
60-64 NCTRL TO 65-72 SOUTHWEST. EASTERLY UPSLOPE WINDS WEDNESDAY
NIGHT MAY RESULT IN STRATUS AND/OR FOG DEVELOPMENT. FOR THURSDAY...
THE UPPER RIDGE AXIS WILL BECOME CENTERED ACROSS THE CENTRAL U.S.
SURFACE HIGH PRESSURE BUILDING INTO THE NRN AND CNTRL MISSISSIPPI
VALLEY TO BRING INCREASING SOUTHEAST WINDS 15 TO 25 MPH. LOOKS
PARTLY CLOUDY WEST TO MOSTLY SUNNY EAST. WITH ABSENCE OF STRATUS
TEMPERATURES WILL WARM UP MOST ACROSS THE NORTH CENTRAL INTO THE
UPPER 60S...WHILE THE SOUTHWEST SIMILAR IN THE UPPER 60S/NEAR 70.
NEXT CHANCE FOR SHOWERS/THUNDERSTORM THURSDAY NIGHT AS GULF
MOISTURE RETURNS NORTH UP THE HIGH PLAINS. PRONOUNCED
SOUTHWESTERLY FLOW ALOFT INTO WESTERN NEBRASKA SUPPORTIVE OF 20-30
POPS SOUTHWESTERN HALF OF FA.
FRIDAY THROUGH MONDAY...
AN UNSETTLED WEATHER PATTERN WILL SET UP AS AN UPPER TROUGH
REMAINS ACROSS THE WESTERN U.S AND A RIDGE ACROSS THE CENTRAL
CONUS. ABUNDANT LOW LEVEL MOISTURE WILL INCREASE WITH H85
DEWPOINTS FROM 12-15C AT TIMES FRIDAY THROUGH SUNDAY. LOCATION OF
THE SURFACE FRONT NOT IN VERY GOOD AGREEMENT. STILL...THE PRESENCE OF
A NOCTURNAL LOW LEVEL JET WILL ALLOW FOR THUNDERSTORMS TO POSSIBLY
DEVELOP INTO AN MCS ACROSS THE REGION EACH NIGHT. HIGHS IN THE 70S
FRIDAY WILL WARM TO THE UPPER 70S TO MID 80S SATURDAY THROUGH
MONDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1223 AM CDT TUE MAY 21 2013
FOR THE KLBF TERMINAL...EXPECT VFR CIGS OVER THE NEXT 24 HOURS.
SCATTERED CLOUDINESS AON 4000 FT AGL WILL BECOME BROKEN AT 3500 FT
AGL TUESDAY MORNING AND WILL PERSIST THROUGH TUESDAY EVENING.
NORTHWESTERLY WINDS AROUND 12 KTS TONIGHT WILL INCREASE TO 15 TO 30
KTS ON TUESDAY...BEFORE DIMINISHING TO AROUND 10 KTS TUESDAY
EVENING.
FOR THE KVTN TERMINAL...MVFR CIGS OF 1500 TO 2000 FT AGL ARE
EXPECTED TO DEVELOP OVERNIGHT AND PERSIST THROUGH TUESDAY EVENING.
CIGS ARE EXPECTED TO LIFT TO 3000 FT AGL LATE TUESDAY EVENING.
NORTHWESTERLY WINDS OF 15 TO 30 KTS WILL PERSIST INTO THE OVERNIGHT
AND WILL CONTINUE THROUGH MID EVENING TUESDAY. WINDS WILL DIMINISH
TO AROUND 12 KTS BY LATE TUESDAY EVENING. SCATTERED RAIN SHOWERS ARE
POSSIBLE TUESDAY AFTERNOON IN NORTHERN NEBRASKA. GIVEN SCATTERED
COVERAGE...WILL HANDLE MENTION WITH A PROB30 GROUP.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...ROBERG
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS BUFFALO NY
104 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A SOUTHWESTERLY FLOW OF WARM AND MORE HUMID AIR WILL CONTINUE ACROSS
THE REGION FOR MUCH OF THIS WEEK...WHILE A FRONTAL BOUNDARY ALSO
STALLS OUT ACROSS NEW YORK STATE AND SETS THE STAGE FOR INCREASING
CHANCES OF SHOWERS AND THUNDERSTORMS. THE MORE UNSETTLED CONDITIONS
WILL LAST THROUGH THURSDAY...BEFORE A COLD FRONT CROSSES THE AREA
AND USHERS IN COOLER AND DRIER WEATHER FOR THE END OF THE WEEK AND
THE MEMORIAL DAY WEEKEND.
&&
.NEAR TERM /THROUGH TODAY/...
BAND OF SHOWERS AND THUNDERSTORMS IS HOLDING TOGETHER ACROSS
SOUTHERN ONTARIO AND NOW WORKING TOWARD THE NIAGARA FRONTIER SO
HAVE INCREASED POPS FROM BUFFALO NORTH AND EASTWARD THIS EVENING
FOLLOWING ALONG THE LINES OF A MIX OF LATEST HRRR RUNS AND RADAR
EXTRAPOLATION. TIMING CONTINUES TO PLACE THUNDERSTORMS INTO THE
NIAGARA FRONTIER AROUND MIDNIGHT THEN SHIFTING THEM EASTWARD THROUGH
THE EARLY MORNING. 00Z BUF RAOB SHOWS AREA OF ELEVATED INSTABILITY
OVER 1000 J/KG ABOVE 700MB WHICH THE CURRENT STORMS CAN FEED OFF OF.
KBUF RADAR VELOCITY SHOWING NO WINDS HIGHER THAN 30 KNOTS AND WITH
LOW LEVEL INVERSION NOT EXPECTING ANY SEVERE IMPACTS FROM
CONVECTION. OTHERWISE BEFOREHAND THERE IS A SLIGHT CHANCE OF A POP
UP SHOWER AHEAD OF THE MAIN LINE AS THE HRRR SUGGESTS BUT KEEP
FORECAST GRIDS IN LINE WITH MAIN BAND OF PRECIP WHERE HIGHEST
CONFIDENCE LIES. TEMPS WILL REMAIN WARM AND HUMID. 850MB TEMPS IN
THE MID TEENS AND A RETURN OF BLANKETING CLOUD COVER WILL KEEP
OVERNIGHT LOW TEMPS UP IN THE LOWER TO MID 60S ACROSS THE ENTIRE
FORECAST AREA.
THE UPPER RIDGE AXIS WILL BE OVER OR TO THE EAST OF THE FORECAST
AREA ON TUESDAY AND WILL ALLOW AN INFLUX OF WARMTH AND MOISTURE WITH
DEWPOINTS SURGING TO THE UPPER 60S ACROSS WESTERN NY DURING TUESDAY
AFTERNOON. THE SUPPRESSIVE SUBSIDENCE WILL BE NEARLY ABSENT ON
TUESDAY SO CAN EXPECT CONVECTION TO DEVELOP DURING THE AFTERNOON
ALONG THE LAKE BREEZE BOUNDARIES AND THE INLAND TERRAIN. LAKE COOLED
AIR WILL PROVIDE LAKE SHADOWS WITHIN ABOUT HALF A COUNTY`S WIDTH OF
THE LAKE ERIE AND ONTARIO SHORES. WILL HAVE POPS INCREASING TO THE
LIKELY CATEGORY BY THE END OF THE DAY ON TUESDAY WITH THE CONTINUED
INFLUX OF HIGH THETA-E AIR. HIGH TEMPS ON TUESDAY SHOULD BE IN THE
LOWER TO MID 80S FOR MOST AREAS...LOWER TO MID 70S EXPECTED ACROSS
THE CLOUDIER AND POSSIBLY RAINIER TUG HILL PLATEAU AND EASTERN LAKE
ONTARIO COUNTIES.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
SUMMERY CONDITIONS WILL CONTINUE ACROSS OUR REGION ON WEDNESDAY...
AS A DEEP SOUTHERLY FLOW WILL REMAIN IN PLACE IN ADVANCE OF A
BROAD SFC LOW FOUND OVER LOWER MICHIGAN. WHILE IT WILL BE WARM AND
HUMID WITH TEMPERATURES RESEMBLING THOSE OF JULY...THERE WILL BE
SOME UNSETTLED WEATHER TO DEAL WITH AS WELL. OUR UNSTABLE AIRMASS
WILL CERTAINLY SUPPORT SOME SHOWERS AND THUNDERSTORMS...ALTHOUGH
THE BULK OF THE DAY MAY END UP BEING RAINFREE. LETS LOOK AT THE
PROS AND CONS TO THIS CONVECTION.
WORKING AGAINST WIDESPREAD CONVECTION WILL BE A SHORTWAVE RIDGE THAT
WILL LIFT UP ACROSS OUR REGION. THIS COULD BE A DOUBLE EDGED SWORD
THOUGH...AS THE RIDGE COULD HELP TO THIN SOME OF THE EXPECTED CLOUD
COVER. THAT WOULD LEAD TO GREATER DIURNALLY INDUCED INSTABILITY THAN
IS BEING FORECAST...WHICH IN TURN WOULD LIKELY LEAD TO MORE
AFTERNOON CONVECTION. ON THE OTHER HAND...THE SUBSIDENCE FROM THE
PASSING RIDGE IN TANDEM WITH MOSTLY CLOUDY SKIES COULD MINIMIZE THE
THREAT OF STORMS (AS WAS ALSO EXPRESSED IN A PREVIOUS STORM
PREDICTION CENTER DISCUSSION)...OR AT LEAST HOLD THEM OFF UNTIL MID
TO LATE AFTERNOON.
EITHER WAY YOU SLICE IT...THERE SHOULD BE AT LEAST 500-1000 J/KG OF
SBCAPE BY WEDNESDAY AFTERNOON SO THERE SHOULD BE SHOWERS OR
THUNDERSTORMS TO DEAL WITH AS WE MOVE THROUGH THE DAY. THIS ACTIVITY
WILL LIKELY FOCUS ON TWO AREAS. THE FIRST BEING A NEARLY STALLED
FRONTAL BOUNDARY THAT WILL BE FOUND FROM THE NORTH SHORE OF LAKE
ONTARIO TO THE NORTH COUNTRY...AND THE SECOND BEING A LAKE BREEZE
BOUNDARY THAT SHOULD PUSH EAST OF LK ERIE. THE LATTER WOULD BE OF
MORE CONCERN BECAUSE THIS WOULD BE THE TRIGGER TO RELEASE THE
GREATER INSTABILITY OVER THE WRN COUNTIES. THIS LEADS US TO THE
POTENTIAL FOR SEVERE WEATHER.
LETS STATE RIGHT UP FRONT THAT SPC HAS OUR FORECAST AREA OUTLINED IN
A SLIGHT RISK FOR SEVERE STORMS ON WEDNESDAY. THAT BEING SAID AND
AS WAS THE CASE IN YESTERDAYS MORNING DISCUSSION...AM NOT OVERLY
IMPRESSED WITH THE OVERALL SET UP FOR SEVERE WEATHER. WE COULD HAVE
SUPPRESSED INSTABILITY FROM CLOUD COVER AND ONGOING SHOWER
ACTIVITY...BUT I AM JUST AS UNIMPRESSED WITH 0-3KM BULK SHEAR
(GENERALLY <25 M/S) AND LACKLUSTER MID LEVE LAPSE RATES OF 6 DEG
C/KM. ONE HAS TO LOOK AT A DEEPER LAYER (0-6 KM) TO FIND IMPRESSIVE
BULK SHEAR VALUES OF 35-40 M/S. A TELLING SIGN WILL LIKELY BE HOW
MUCH SUN WE GET DURING THE MORNING AND MIDDAY. THE MAIN THREAT FROM
ANY STRONG TO SEVERE STORMS WOULD BE STRAIGHT LINE WINDS...AND IF WE
CAN GET OUR CAPES UP OVER 1500 J/KG...SOME LARGE HAIL. PWAT VALUES
>1.5 INCHES WILL ALSO LIKELY LEAD TO SOME TORRENTIAL DOWNPOURS...
BUT THERE SHOULD BE ENOUGH WINDS TO MOVE THE STORMS ALONG AND
MINIMIZE THE POTENTIAL FOR HYDRO ISSUES. BOILING THIS ALL DOWN...
WILL MAINTAIN HIGH LIKELY TO CAT POPS BUT WILL REFRAIN FROM ADDING
ANY ENHANCED TSRA WORDING. WILL DEFER THIS TO LATER SHIFTS FOR
FURTHER REVIEW.
ON WEDNESDAY NIGHT...THE AFOREMENTIONED SFC LOW WILL TRACK BY TO OUR
NORTH WHILE THE CONVECTION FROM THE EVENING HOURS WILL GRADUALLY
SUBSIDE WITH THE LOSS OF DAYTIME HEATING AND SUBSEQUENT
STABILIZATION OF THE LOWEST LEVELS. THIS WILL LEAVE A WARM AND DAMP
NIGHT WITH NOCTURNAL TEMPERATURES ONCE AGAIN NOT FALLING OUT OF THE
60S.
THE VARIOUS GUIDANCE PACKAGES THEN START TO DIVERGE ON THE HANDLING
OF THE WAVY FRONTAL BOUNDARY THAT WILL OOZE ACROSS OUR FORECAST AREA
ON THURSDAY. IN PREVIOUS MODEL RUNS...THE ECMWF HAS BEEN THE FASTER
PACKAGE IN BRINGING THE FRONT THROUGH. IT NOW TRAILS THE GFS...AND
FOR WHAT ITS WORTH...THE NAM. THE SECONDARY WAVE ALONG THE TRAILING
FRONT IS WHAT IS OBVIOUSLY THROWING A MONKEY WRENCH INTO THE
MODELS...BUT IN ANY CASE...THE MODELS ARE IN GENERAL AGREEMENT THAT
THERE WILL BE A WEALTH OF LOW LEVEL MOISTURE THAT WILL BE LIFTED IN
FAIRLY WIDESPREAD SHOWERS. JUST DO NOT SEE ENOUGH INSTABILITY TO
HOLD ONTO THE SLGT CHC THAT WE HAVE FOR THUNDER...AS LAPSE RATES ARE
GENERALLY BELOW 6 DEG C/KM BY MID MORNING. WILL COMPROMISE AND LEAVE
THE MENTION FOR THE MORNING ONLY. OTHERWISE...IT WILL BE A WET AND
NOTICEABLY COOLER DAY WITH TEMPERATURES AVERAGING SOME 10 DEG F
LOWER THAN PREVIOUS DAYS. HIGHS SHOULD GENERALLY BE IN THE UPPER 60S
TO LOWER 70S.
WHILE THE WAVY FRONT WILL BE WELL TO OUR EAST THURSDAY NIGHT...THE
SUPPORTING H5 TROUGH WILL BE JUST CROSSING THE LOWER LAKES. THIS
SHOULD KEEP SOME LEFTOVER SHOWERS OVER THE REGION...ESPECIALLY
DURING THE FIRST HALF OF THE NIGHT. MEANWHILE...TEMPERATURES ARE
EXPECTED TO TUMBLE INTO THE 40S...WHICH WILL BE QUITE REFRESHING
AFTER SEVERAL DAYS OF MID JULY-LIKE WEATHER.
FRIDAY WILL FEATURE SEASONABLY COOL CONDITIONS AS H85 TEMPS IN THE
VCNTY OF 4C WILL ONLY SUPPORT AFTERNOON HIGHS AROUND 60 F. WHAT IS
MUCH LESS CERTAIN IS WHETHER ALL OF THE SHOWER ACTIVITY WILL BE
DONE. THE 00Z GFS IS NOW BEING STUBBORN WITH CLEARING OUT THE
SHOWERS AND LEFTOVER CLOUDS...SO WILL HAVE TO KEEP AT LEAST SLGT CHC
POPS OVER THE REGION DURING THE MORNING AND INCREASE OUR CLOUD COVER
A BIT. WILL STILL LEAN MORE ON THE ECMWF SOLUTION THOUGYH...WHICH AT
THIS POINT FAVORS A MORE OPTIMISTIC SCENARIO.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
PLENTY OF SUNSHINE AND SEASONABLY COOL TEMPERATURES WILL BE THE NAME
OF THE GAME THIS WEEKEND AS HIGH PRESSURE WILL SETTLE ACROSS THE
GREAT LAKES. 850MB TEMPS DROPPING TO AROUND 0C SHOULD ONLY YIELD
HIGHS TOPPING OUT IN THE LOWER 60S FOR MOST AREAS ON SATURDAY...
NEARLY 10 DEGREES BELOW NORMAL. LIKEWISE OVERNIGHT LOWS WILL RUN ON
THE CHILLY SIDE WITH READINGS IN THE LOWER 40S ALONG THE LAKE PLAINS
WHILE AREAS FARTHER INLAND ACROSS THE SOUTHERN TIER AND NORTH
COUNTRY COULD DROP INTO MID 30S...POTENTIALLY SETTING THE STAGE FOR
A FROST...PARTICULARLY SATURDAY NIGHT WHEN THE SURFACE HIGH IS
FORECAST TO BE OVERHEAD.
A GRADUAL REBOUND IN TEMPERATURES IS EXPECTED FOR THE LATTER HALF OF
THE WEEKEND AS THE COLDEST AIR ASSOCIATED WITH THE UPPER LEVEL
TROUGH DEPARTS THE REGION AND WARMER AIR BEGINS TO CREEP NORTH FROM
THE OHIO VALLEY ONCE AGAIN. OTHERWISE...EXPECT DRY WEATHER TO
CONTINUE THROUGH THE END OF THE WEEKEND.
&&
.AVIATION /05Z TUESDAY THROUGH SATURDAY/...
EXPECT VFR CONDITIONS TO BRIEFLY DETERIORATE WITHIN TS AROUND
MIDNIGHT FOR KBUF/KIAG AND CLOSER TO 05Z/06Z FOR KROC AND 07Z/08Z
FOR KART. LEFT KJHW OUT OF TS BECAUSE SOUTHERN FLANK OF STORMS WILL
REMAIN TO THE NORTH OF THE AIRFIELD. SOME MVFR STRATUS IS POSSIBLE
HERE THOUGH SIMILAR TO WHAT HAPPENED LAST NIGHT.
THE UPPER AND MID LEVEL RIDGE AXES TO PASS ACROSS THE REGION AND TO
THE EAST ON TUESDAY. WILL HAVE A SLIGHTLY BETTER CHANCE OF AFTERNOON
AND EVENING CONVECTION...ALONG THE LAKE BREEZE BOUNDARIES AND OVER
THE INTERIOR OF THE FORECAST AREA.
OUTLOOK...
TUESDAY THROUGH THURSDAY...NUMEROUS SHOWERS AND THUNDERSTORMS WITH
ASSOCIATED BRIEF MVFR/IFR...OTHERWISE VFR.
FRIDAY...MAINLY VFR WITH A CHANCE OF SHOWERS.
SATURDAY...VFR.
&&
.MARINE...
A LINE OF SHOWERS AND THUNDERSTORMS MOVING ACROSS EASTERN MICHIGAN
AND LAKE HURON WILL SHIFT EAST THIS EVENING AND MAY PUSH ACROSS THE
LAKES ARRIVING NEAR MIDNIGHT AND SHIFTING EAST THROUGH THE EARLY
MORNING HOURS.
OTHERWISE...FOR MUCH OF THIS WEEK WINDS WILL REMAIN RELATIVELY LIGHT
AND VARIABLE IN DIRECTION DUE TO A NEARLY STATIONARY FRONTAL
BOUNDARY THAT WILL REMAIN DRAPED ACROSS THE REGION...AS WELL AS THE
DAILY DEVELOPMENT OF LAKE BREEZES. AS A RESULT...WAVE HEIGHTS SHOULD
ALSO REMAIN MINIMAL. OTHERWISE...SHOWER AND THUNDERSTORM
CHANCES WILL INCREASE MARKEDLY FOR THE TUESDAY THROUGH THURSDAY TIME
FRAME. A COLD FRONTAL PASSAGE WILL TURN WINDS TO A NORTHERLY
DIRECTION WITH AN INCREASE IN WAVE HEIGHTS... ESPECIALLY ALONG THE
SOUTH SHORE OF LAKE ONTARIO ON FRIDAY MORNING.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JJR
NEAR TERM...SMITH/WCH
SHORT TERM...RSH
LONG TERM...RSH
AVIATION...SMITH
MARINE...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1013 PM EDT WED MAY 22 2013
.SYNOPSIS...
A MOIST SOUTHERLY WIND FLOW WILL PERSIST ACROSS CENTRAL NC THROUGH
THURSDAY. A COLD FRONT WILL CROSS THE REGION LATE THURSDAY AND
THURSDAY NIGHT. A CANADIAN HIGH PRESSURE SYSTEM WILL BUILD INTO THE
CAROLINAS FRIDAY AND LINGER OVERHEAD THROUGH THE HOLIDAY WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1010 PM WEDNESDAY...
ANY SHOWERS AND THUNDERSTORMS FROM THIS AFTERNOON AND EVENING
ASSOCIATED WITH THE SEA BREEZE AND OUTFLOW ACROSS THE EASTERN
TWO-THIRDS OF THE AREA HAVE DISSIPATED WITH THE LOSS OF DAYTIME
HEATING AND RESULTANT STABILIZING BOUNDARY LAYER. CONVECTION THAT
FIRED ACROSS THE HIGHER TERRAIN TODAY... HAS GENERALLY STAYED TO THE
WEST OF THE REGION WITH A 15 TO 20 KT SOUTH-SOUTHWESTERLY MEAN
STEERING FLOW. HOWEVER... A WEST-NORTHWESTERLY OUTFLOW... GENERATED
FROM THESE CLUSTERS OF SHOWERS AND STORMS THAT ORIGINATED ALONG THE
HIGHER TERRAIN... HAS FINALLY ALLOWED FOR THE DEVELOPMENT OF SHOWERS
AND STORMS ACROSS OUR FAR NORTHWESTERN REACHES OF OUR CWA... ALONG
THE OUTFLOW. THINK THIS OUTFLOW SHOULD SUPPORT AT LEAST SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS ACROSS OUR WESTERN PIEDMONT
THROUGH 06/07Z... GIVEN 500 TO 1000 J/KG OF SURFACE BASED CAPE.
THEREAFTER... EXPECT BOUNDARY LAYER COOLING SHOULD YIELD A TREND TO
ISOLATED SHOWERS AT BEST. ANY SIGNIFICANT S/W ENERGY ROTATING
THROUGH THE CYCLONIC FLOW ALOFT FROM THE APPROACHING MID LEVEL
TROUGH WELL TO THE WEST OF THE AREA... INVOF THE MS RIVER THIS
EVENING... IS EXPECTED TO PASS TO THE WEST AND NORTH OF THE REGION
THUS... PLAN TO TRIM POPS TO SLIGHT CHANCE BY EARLY THURSDAY MORNING
ACROSS THE ENTIRE CWA. THIS IS SUPPORTED BY THE LATEST HRRR.
HOWEVER... ITS WORTH NOTING THE LATEST HRRR DOES SHOW SOME SHOWERS
CURRENTLY OFF THE CAROLINA COAST MOVING ONSHORE OVERNIGHT ACROSS THE
COASTAL PLAIN. CURRENT HI-RES MODELS GENERALLY SHOW THIS PRECIP
REMAINING JUST TO THE EAST OF OUR AREA. THUS... WILL KEEP ONLY
SLIGHT CHANCE POPS ACROSS OUR EAST AS WELL. OVERNIGHT LOWS IN THE
MID TO UPPER 60S ARE STILL EXPECTED... WITH GENERALLY PATCHY FOG
(FOG... AT LOCATIONS THAT ARE PICKING UP DECENT SHOWERS/STORMS
ACROSS THE TRIAD NOW) AND WIDESPREAD LOW STATUS.
&&
.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
AS OF 300 PM WEDNESDAY...
A COLD FRONT WILL APPROACH CENTRAL NC FROM THE WEST ON FRIDAY. AS A
DEEP 500 MB TROUGH DIGS SOUTHWARD THROUGH THE OHIO VALLEY. AS FAR AS
TIMING IS CONCERNED...SHOWERS AND THUNDERSTORMS AHEAD OF FRONT WILL
BEGIN TO AFFECT THE TRIAD BY LATE THURSDAY MORNING AND CONTINUE TO
PROGRESS SLOWLY EASTWARD ACROSS THE CWA BY AFTERNOON/EVENING. SEVERE
POTENTIAL WITH THIS SYSTEM WILL BE GREATER THAN THE PAST COUPLE OF
DAYS BUT STILL LOOKS VERY LOW. EFFECTIVE SHEAR WILL BE ABOUT 20
KNOTS SUGGESTING MORE LINEAR THUNDERSTORMS. THIS IS SUPPORTED BY THE
STRAIGHT HODOGRAPHS SHOWN BY NAM FORECAST SOUNDINGS. MID LEVEL LAPSE
RATES WILL BE WEEK ALTHOUGH 1000 ML CAPE OF THE TALL AND SKINNY
VARIETY COULD BE REALIZED BY AFTERNOON. LATER IN THE EVENT DYNAMICS
IMPROVE AS A 30 KNOT 850MB APPROACHES THE NORTHWEST. IT IS UNCLEAR
AT THIS TIME WHETHER OR NOT CONVECTION WILL BE TOO FAR TO THE EAST
TO TAKE ADVANTAGE OF THE INCREASED SHEAR. STORMS LINGERING BACK
TOWARDS THE WEST MAY BE ABLE TO TAKE ADVANTAGE OF AN INCREASED AXIS
OF DCAPE EXPECTED TO MOVE THROUGH THE CWA JUST AFTER 00Z FRIDAY.
THEREFORE IF WE DO ENCOUNTER SEVERE WEATHER TOMORROW...IT WILL MOST
LIKELY BE DAMAGING WINDS AND NOT HAIL. FOR NOW SPC HAS KEPT THE
RALEIGH AREA OUT OF THE SLIGHT RISK AREA FOR TOMORROW. PRECIPITABLE
WATERS WILL BE SIMILAR TO TODAY NEAR 1.5 INCHES BUT QPF WITH FRONTAL
PASSAGE IS ONLY EXPECTED TO BE BETWEEN A QUARTER AND A HALF OF AN
INCH WITH LOCALLY HEAVIER AMOUNTS POSSIBLE IN THUNDERSTORMS.
LOCALIZED FLOODING COULD BE AN ISSUE...ESPECIALLY IN URBAN AREAS
UNDER SLOW MOVING OR TRAINING THUNDERSTORMS. CLOUD COVER SHOULD
OVERSPREAD THE AREA FAIRLY EARLY TOMORROW AND THUS WILL TREND
TOWARDS THE COOLER MET GUIDANCE WITH HIGH TEMPERATURES. UPPER 70S IN
THE NORTHWEST TO LOW 80S SOUTHEAST. AS THE LOWER ATMOSPHERE BEGINS
TO DRY OUT LOW TEMPERATURES IN THE TRIAD SHOULD DIP INTO THE UPPER
50S IN THE NORTHWEST FOR THE FIRST TIME IN SEVERAL DAYS BUT FURTHER
TO THE SOUTHEAST LOWS WILL REMAIN IN THE MIDDLE 60S AS THE FRONT IS
EXPECTED TO FULLY MOVE THROUGH THE EAST UNTIL CLOSER TO 6Z ON FRIDAY.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AS OF 310 PM WEDNESDAY...
FRIDAY THROUGH SATURDAY NIGHT...
A DEEP UPPER LEVEL TROUGH WILL SWING ACROSS CENTRAL NC FRIDAY AND
EXIT THE REGION FRIDAY NIGHT. MAY SEE A FEW INSTABILITY SHOWERS
WITH THE PASSAGE OF THIS SYSTEM HOWEVER MODEL RH CROSS SECTIONS
DEPICT THE AIR MASS DRYING OUT APPRECIABLY ABOVE 5000-8000FT BY
EARLY AFTERNOON. FOR NOW WILL LIMIT POPS TO SLIGHT CHANCE. OTHERWISE
BRISK NW FLOW WILL ADVECT COOLER MORE STABLE AIR INTO THE REGION.
SUSTAINED NW WINDS 10-15 MPH WITH GUSTS AROUND 25 MPH PROBABLE. THE
ARRIVAL OF THIS AIR MASS WILL RESULT IN COOLER CONDITIONS WITH
AFTERNOON MAX TEMPS IN THE LOWER 70S NORTH TO UPPER 70S FAR SE.
FRIDAY NIGHT...SKIES WILL CLEAR EARLY THOUGH A STEADY NW SFC WIND
WILL BE SLOW TO SUBSIDE. LOW LEVEL THICKNESSES CLUSTERING AROUND
1340M. HISTORICALLY...THIS SUGGEST MIN TEMPS NEAR 40-LOWER 40S.
FAVOR THE HIGH END OF THIS REGION DUE TO EXPECTED MIXING WELL INTO
THE NIGHT. MIN TEMPS 45-50.
SATURDAY INTO SATURDAY NIGHT...CANADIAN HIGH PRESSURE OVER THE LOWER
GREAT LAKES WILL BUILD/EXTEND INTO OUR REGION SATURDAY INTO SATURDAY
NIGHT. THIS WEATHER SYSTEM WILL RESULT IN A DRY WEATHER PATTERN WITH
BELOW NORMAL TEMPS. AFTERNOON THICKNESSES PROJECTED TO BE ABOUT 35M
BELOW NORMAL...SUPPORTIVE OF TEMPS CLOSE TO 10 DEGREES BELOW NORMAL.
ALLOWING FOR WARMTH FROM LATE MAY SUN...EXPECT AFTERNOON HIGH TEMPS
IN THE MID-UPPER 70S. MOS GUIDANCE LIKELY TRENDING TOWARD
CLIMATOLOGY BY SATURDAY NIGHT. WITH SFC RIDGE OVERHEAD AND CORE OF
LOW LEVEL DRY ACROSS THE REGION...TEMPS SHOULD COOL QUICKLY INT EH
EVENING THEN STABILIZE. MODEL RH CROSS SECTIONS HINT AT INCREASING
MID-HIGH LEVEL CLOUDS OVERNIGHT INTO EARLY SUNDAY. FIRST GLANCE
SUGGEST THAT CLOUD COVERAGE MAY INITIALLY BE THIN AND SPOTTY SO
COULD SEE DECENT NOCTURNAL COOLING. FAVOR MIN TEMPS A FEW DEGREES
COOLER THAN PREVIOUS FORECAST WITH MIN TEMPS IN THE MID-UPPER 40S.
SUNDAY INTO MONDAY...DEEP UPPER LEVEL LOW OVER NORTHERN NEW
ENGLAND-CANADIAN MARITIME PROVINCES WILL MAINTAIN A NW FLOW OVER THE
FORECAST AREA SUNDAY. WEAK PERTURBATIONS IN THIS FLOW ALOFT WORKING
WITH AVAILABLE MOISTURE WILL LIKELY CAUSE AN INCREASE IN MID-HIGH
LEVEL CLOUDINESS SUNDAY INTO SUNDAY NIGHT...MORE SO ACROSS OUR WEST
AND SOUTH SECTIONS AND LEAST IN THE NE. A MODIFYING AIR MASS WILL
LEAD TO SLIGHTLY WARMER CONDITIONS WITH AFTERNOON TEMPS IN THE
MID-UPPER 70S...AND AND MIN TEMPS IN THE MID 50S. 00Z ECMWF SUGGEST
THAT THERE MAY BE ENOUGH AMPLITUDE TO AN APPROACHING MID LEVEL
TROUGH TO WARRANT A SLIGHT-SMALL CHANCE POP ACROSS CENTRAL NC MONDAY
AFTERNOON-MONDAY EVENING.
TUESDAY INTO WEDNESDAY...AN AMPLIFYING MID-UPPER LEVEL RIDGE OVER
THE EASTERN HALF OF THE U.S. WILL PLACE CENTRAL NC BACK INTO A
SUMMER-LIKE PATTERN WITH A SFC HIGH ANCHORED OFFSHORE BUT EXTENDING
WESTWARD INTO THE SE U.S. THIS SUGGEST A RETURN TO WARM AND SLIGHTLY
HUMID CONDITIONS WITH AFTERNOON TEMPS IN THE LOW-MID 80S AND MIN
TEMPS 60-65. CONVECTION APPEARS TO BE DIURNALLY DRIVEN...ADDED BY A
SEABREEZE TO SE AND NW FLOW ALOFT SENDING CONVECTION OFF THE HIGHER
TERRAIN INTO THE WESTERN PIEDMONT. POPS NO HIGHER THAN SLIGHT
CHANCE-SMALL CHANCE AT THIS TIME...CONFINED TO THE AFTERNOON-EVENING
HOURS.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AS OF 750 PM WEDNESDAY...
SEABREEZE AND OUTFLOW GENERATED SHOWERS HAVE MOSTLY DISSIPATED IN
THE LAST HOUR...WITH MORE ROBUST CONVECTION JUST TO THE WEST OF KINT
CONTINUING TO MOVE SOUTHWEST TO NORTHEAST. THERE IS NOT MUCH
EVIDENCE ON RADAR OF THESE CELLS MOVING EAST MAKING MUCH PROGRESS
EAST TOWARD KINT...SO WILL KEEP VCSH IN THE KINT TAF THROUGH 03Z.
THE MORE PROGRESSIVE AREA OF CONVECTION AND OUTFLOW IS STILL WEST OF
KHKY. THE OVERALL WEAKENING TREND OF CONVECTION IS EXPECTED TO
CONTINUE THIS EVENING...WITH IFR/MVFR STRATUS EXPECTED TO DEVELOP
AFTER MIDNIGHT.
THE THREAT OF SCATTERED CONVECTION WILL CONTINUE ON THURSDAY AHEAD
OF AN UPPER LEVEL TROUGH AND ASSOCIATED COLD FRONT OVER THE MIDWEST
STATES. MODEL GUIDANCE SUGGESTS SHOWERS MAY BE POSSIBLE AS EARLY AS
12Z NEAR KGSO/KINT...WITH MORE WIDESPREAD SHOWERS AND STORMS MORE
LIKELY THURSDAY AFTERNOON AS THE TROUGH AND COLD FRONT APPROACH FROM
THE WEST. CEILINGS WILL BREAK BY MIDDAY THURSDAY...WITH CLOUD BASED
EXPECTED TO LIFT TO AROUND 3500-4000 FT THURSDAY AFTERNOON.
OUTLOOK...
A COLD FRONT MOVING THROUGH THE AREA LATE THURSDAY AND EARLY FRIDAY
WILL CONTINUE THE THREAT OF ADVERSE AVIATION CONDITIONS. VFR
CONDITIONS ARE EXPECTED TO RETURN DURING THE DAY FRIDAY AND PREVAIL
THROUGH THE WEEKEND.
&&
.CLIMATE...
MORNING LOW TEMPERATURES ON THE 25TH AND 26TH ARE EXPECTED TO BE A
FEW DEGREES SHY OF RECORD MIN TEMPS FOR THE DATE.
RECORD MIN TEMP/YEAR SET MAY 25TH MAY 26TH
RDU 43 / 1967 43 / 1979
GSO 43 / 1956 42 / 1930
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS
NEAR TERM...BSD
SHORT TERM...ELLIS
LONG TERM...WSS
AVIATION...SMITH
CLIMATE...RAH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
323 PM EDT TUE MAY 21 2013
.SYNOPSIS...
SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON WILL DISSIPATE
THIS EVENING. SHOWER AND THUNDERSTORM ACTIVITY WILL DECREASE ON
WEDNESDAY WITH TEMPERATURES WARMING A LITTLE. SHOWERS AND
THUNDERSTORMS WILL INCREASE ON THURSDAY AHEAD OF A COLD FRONT THAT
WILL CROSS THE REGION EARLY FRIDAY. COOLER AND DRIER WEATHER WILL
DEVELOP FOR THE WEEKEND. TEMPERATURES WILL RETURN TO NORMAL EARLY
NEXT WEEK AS HIGH PRESSURE MOVES OFF THE EAST COAST.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
AS OF 3 PM TUESDAY...CONVECTION NOW FOCUSED ALONG WHAT APPEARS TO
BE DIFFERENTIAL HEATING BOUNDARY. HEATING REALLY THE ONLY FORCING
IN THE ABSENCE OF ANY ASCENT ABOVE THE BOUNDARY LAYER BUT LCLS ARE
VERY LOW. LAPSE RATES SO WEAK THROUGH THE COLUMN THAT LIGHTNING
HAS BEEN MINIMAL DESPITE SOME OF THE TALLER CELLS REACHING THE EL
OF ABOUT 40KFT. DESPITE THIS IMPLIED VERY WEAK UPDRAFT SPEED THE
COLUMN IS NEARLY SATURATED AND RAINFALL WILL STILL BE HEAVY UNDER
MOST OF THE SHOWERS BUT THEIR SHORT DURATION IN ANY GIVEN LOCATION
WILL MINIMIZE FLOODING CONCERNS...WHICH ARE LOW BUT STILL NON-
ZERO. BEING BORNE OF NOTHING MORE THAN HEATING THE CONVECTION
SHOULD DWINDLE THROUGH THE EVENING AND A RAIN-FREE NIGHT IS
EXPECTED. HOW MUCH CLOUD COVER LINGERS IS A LITTLE UNCERTAIN AND
IS PROBABLY THE MAIN FORECAST CHALLENGE AT THIS TIME WITH POSSIBLE
MINOR RAMIFICATIONS FOR THE LOW TEMPERATURE FORECAST.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
AS OF 3 PM TUESDAY...DEEP SOUTH TO SOUTHWEST FLOW FOR MUCH OF THE
PERIOD WILL CONTINUE TO PUMP PLENTY OF GULF MOISTURE INTO THE
REGION. BERMUDA HIGH AND MID LEVEL RIDING OVER THE WESTERN ATLANTIC
BRIEFLY EXPAND WEST WED. INCREASE IN MID LEVEL SUBSIDENCE WILL
LIMIT COVERAGE OF AFTERNOON SHOWERS AND THUNDERSTORMS. DIURNAL
INSTABILITY ALONG WITH PRECIPITABLE WATER VALUES AROUND 1.7 INCHES
AND CONVERGENCE ALONG THE SEA BREEZE HOWEVER SUGGEST POP WILL NOT
BE ZERO. GIVEN THE LIMITING FACTORS SLIGHT CHANCE TO LOW CHANCE
SEEMS REASONABLE WITH INLAND SC FAVORED. WORTH NOTING THAT THE 12Z
NAM IS NOT AS AGGRESSIVE WITH THE BUILDING RIDGE AND IS SLOWER TO
EXIT THE SHORTWAVE REMNANTS. DISCOUNTING THIS SCENARIO FOR NOW AS
IT IS A SIGNIFICANT CHANGE FROM PREVIOUS SOLUTIONS BUT SHOULD IT
VERIFY POP WOULD NEED TO BE MUCH HIGHER.
MID LEVEL RIDGE QUICKLY WEAKENS THU WITH 5H TROUGH APPROACHING FROM
THE WEST. WHILE THE LOCAL ENVIRONMENT REMAINS RELATIVELY
UNCHANGED...DEEP SOUTHERLY FLOW PUSHES PWATS NEAR 1.8 INCHES...THE
LOSS OF SUBSIDENCE WILL RESULT IN A SIGNIFICANT INCREASE IN STORM
COVERAGE. IN ADDITION ANOTHER STRETCHED SHORTWAVE WILL MOVE INTO THE
AREA FROM THE BAHAMAS EARLY THU. PVA AHEAD OF IT REACHES THE AREA
LATE WED NIGHT OR THU MORNING AND SHOULD ENHANCE CONVECTION. AS HAS
BEEN THE CASE OVER THE PAST FEW DAYS THE ENVIRONMENT IS NOT
SUPPORTIVE OF SEVERE WEATHER. HOWEVER DEEP WARM LAYER AND RELATIVELY
SLOW STORM MOTION WITH POTENTIAL FOR TRAINING STORMS WILL KEEP THE
FLOOD THREAT ELEVATED...ESPECIALLY IN AREAS THAT HAVE ALREADY
RECEIVED SIGNIFICANT RAINFALL THE LAST FEW DAYS.
CONVECTION WILL BE WINDING DOWN THU EVENING AS DRY AIR JUST AHEAD OF
THE 5H TROUGH AXIS AND SURFACE COLD FRONT STARTS TO MOVE IN. COLD
FRONT IS SLOW TO CROSS THE AREA...NOT REACHING THE COAST UNTIL CLOSE
TO THE END OF THE PERIOD...BUT ALOFT WESTERLY FLOW STARTS DEVELOPING
BEFORE 00Z FRI. HIGHS WILL BE NEAR TO SLIGHTLY ABOVE CLIMO...WITH
NUMBERS TEMPERED BY CLOUDS IN SOME AREAS WHILE LOWS CONTINUE TO RUN
ABOVE CLIMO.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 3 PM TUESDAY...CHANGE IN AIR MASS EXPECTED ON FRIDAY AS
COLD FRONT MAKES ITS WAY OFF SHORE AND COOL CANADIAN HIGH PRESSURE
BUILDS IN. EXPECT COOLER AND DRIER AIR TO MAKE ITS WAY INTO THE
COASTAL CAROLINAS IN DEEP WEST TO NORTHWEST FLOW. PCP WATER VALUES
UP ABOVE 1.5 INCHES OVER THE DAYS LEADING UP TO FRIDAY WILL DROP
OUT TO LESS THAN AN INCH BY FRI AFTN AND BE DOWN TO LESS THAN A
HALF INCH BY SAT MORNING AS ATMOSPHERIC COLUMN DRIES OUT.
THEREFORE DO NOT EXPECT ANY PCP THROUGH THE WEEKEND IN A
RELATIVELY COOLER AND DRIER NORTHERLY FLOW.
AS FOR TEMPS...FRIDAY SHOULD MAKE IT INTO THE 80S IN MOST PLACES BUT
WILL FEEL COOLER AND DRIER BY THE END OF THE DAY. THE 850 TEMPS DROP
FROM CLOSE TO 15C PREVIOUS DAYS DOWN TO 8 TO 10C THROUGH THE
WEEKEND. SATURDAY AND SUNDAY TEMPS WILL REMAIN BETWEEN 75 TO 80 MOST
PLACES WITH MUCH LOWER DEWPOINTS REACHING DOWN INTO THE 40S INLAND
TO AROUND 50 ALONG THE COAST AS COMPARED TO 65 THE PREVIOUS DAYS.
WILL ALSO SEE MUCH GREATER DIURNAL SWINGS DUE TO THE DRY AIR MASS IN
PLACE. OVERNIGHT LOWS WILL REACH DOWN TO THE LOWER END OF THE 50S
BOTH FRI NIGHT AND SAT NIGHT IN COOL ADVECTION AND BETTER
RADIATIONAL COOLING SAT NIGHT AS HIGH PRESSURE SHIFTS OVERHEAD.
BY LATE SUNDAY INTO MONDAY THE HIGH PRESSURE WILL SHIFT OFF SHORE
GIVING WAY TO A WARMER MOISTER RETURN FLOW THROUGH EARLY NEXT WEEK.
THEREFORE WILL SEE A WARMING TREND. THE GFS SHOWS A WEAK COLD FRONT
DROPPING SOUTH INTO NORTH CAROLINA LATE MONDAY INTO TUES. THEREFORE
WILL SHOW CLOUDS AND CHC OF PCP BACK IN THE FORECAST HOLDING TO THE
NORTH ON MONDAY AND OVER LOCAL AREA BY TUES.
&&
.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
AS OF 18Z...MAINLY VFR/MVFR CONDITIONS ARE BEING REPORTED ACROSS THE
CWA THIS AFTN WITH SOUTH WINDS 8-12 KTS. CONVECTION HAS ALREADY
FIRED ALONG THE SEA BREEZE BOUNDARY THIS MORNING...MAINLY NEAR
KMYR/KCRE. MORE SHOWERS/T-STORMS ARE POSSIBLE TODAY WITH CONTINUED
DIURNAL HEATING. HAVE INCLUDED VCSH/VCTS AT ALL TERMS THROUGH
00Z...ALTHOUGH THE LATEST HRRR RUNS SUGGEST PCPN THIS AFTN MAY BE
MORE CONCENTRATED INLAND. VERY BRIEF PERIODS OF IFR ARE POSSIBLE IN
HEAVIER DOWNPOURS. THE ABUNDANT LOW-LEVEL MOISTURE IN PLACE COULD
ALLOW MVFR CIGS/VSBYS TO DEVELOP OVERNIGHT. EXPECT MOSTLY CLOUDY
CONDITIONS AGAIN ON WEDNESDAY WITH SOUTH WINDS AROUND 8-12 KTS.
EXTENDED OUTLOOK...SLIGHT CHC OF SHOWERS WEDNESDAY. SHOWERS/T-STORMS
POSSIBLE THURSDAY THROUGH EARLY FRIDAY. OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 PM TUESDAY...NOT MUCH CHANGING THROUGH THE PERIOD FROM
THE CONDITIONS THAT HAVE BEEN IN PLACE FOR QUITE SOME TIME NOW.
SOUTH TO SOUTHWESTERLY WINDS WILL RUN IN THE 10 TO 15 KT RANGE ON
AVERAGE. SEAS WILL BE IN THE 3 TO 4 FT RANGE AND BE A LITTLE ON
THE CHOPPY SIDE WITH A PERIOD OF 4-6 SECONDS. THERE IS STILL SOME
SWELL ENERGY OUT OF THE ESE AT ABOUT 9 SEC BUT IT IS SHOWING UP AS
A MUCH LESSER WAVE COMPONENT IN SPECTRAL PLOTS.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 PM TUESDAY...BERMUDA HIGH REMAINS IN CONTROL WED BEFORE
RETREATING EAST THU AHEAD OF A COLD FRONT EXPECTED TO CROSS THE
WATERS LATE THU NIGHT. WED BERMUDA HIGH MAINTAINS SOUTHERLY FLOW
WITH SPEEDS OF 10 TO 15 KT RANGE AND SEAS 2 TO 4 FT. WIND SPEEDS
INCREASE SLIGHTLY THEN VEER THU INTO THU NIGHT AS THE COLD FRONT
APPROACHES FROM THE WEST. WINDS WILL GENERALLY BE 10 TO 15 KT WITH
PERIODS OF SUSTAINED 15 KT LIKELY...ESPECIALLY IN THE AFTERNOON.
WINDS EVENTUALLY VEER TO WEST LATE THU NIGHT AS FRONT PASSES. SEAS
BRIEFLY RISE TO 3 TO 5 FT THU THEN DROP BACK TO 2 TO 4 FT AS PERIOD
ENDS.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 3 PM TUESDAY...COLD FRONT MOVING FARTHER ON FRIDAY AS
COOLER AND DRIER CANADIAN HIGH PRESSURE BUILDS IN BEHIND IT
THROUGH THE WEEKEND. WINDS WILL VEER AROUND FROM WEST AROUND 10
KTS FRIDAY MORNING...TO NORTH TO NORTHEAST AT 15 TO 20 KTS FRIDAY
NIGHT INTO SATURDAY IN COOL SURGE AND TIGHTENED GRADIENT. WINDS
WILL LIGHTEN AND CONTINUE TO VEER AS HIGH PRESSURE SHIFTS OVERHEAD
ON SUNDAY.
SEAS WILL BE ENTIRELY WIND-WAVE DOMINATED BETWEEN 3 AND 5 FT THROUGH
FRI INTO SATURDAY. BY LATE SATURDAY INTO SUNDAY...THE SEAS WILL
SUBSIDE AND WINDS LIGHTEN AS HIGH SHIFTS CLOSER OVERHEAD. EXPECT
SEAS DOWN TO 3 FT OR LESS BY SAT NIGHT INTO SUNDAY.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...MBB
SHORT TERM...III
LONG TERM...RGZ
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
130 PM EDT TUE MAY 21 2013
.SYNOPSIS...
A WEAK UPPER LEVEL DISTURBANCE AND HIGH PRESSURE OFFSHORE WILL
CONTINUE TO PRODUCE SCATTERED SHOWERS AND THUNDERSTORMS TODAY. DRIER
AND WARMER WEATHER IS EXPECTED FOR MID-WEEK. A COLD FRONT WILL
APPROACH AND CROSS THE REGION EARLY FRIDAY. COOLER AND DRIER WEATHER
WILL DEVELOP FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM TUESDAY...ITS PRETTY HARD TO ADD MUCH SPECIFICITY TO
THE FORECAST ON A DAY LIKE TODAY. CURRENTLY CONVECTION IS WINDING
DOWN OVER THE WRN ZONES WHILE THE SEABREEZE IS LIGHTING UP NICELY
WITH SHOWERS THAT WHILE HEAVY WILL BE SO SHORT-LIVED THE ACTUAL
RAINFALL AMOUNTS WILL BE QUITE LIGHT OVER A GIVEN LOCATION. HOW MUCH
ACTIVITY REFIRES OVER WESTERN ZONES WILL LARGELY BE A FUNCTION OF
HEATING DUE THE ABSENCE OF ANY MEANINGFUL LARGE SCALE LIFT. THERE
WILL ALSO BE A TENDENCY FOR THE IMMEDIATE COAST TO SEE LESS ACTIVITY
EAST OF THE SEA BREEZE...WHICH WILL NOT MOVE MUCH INLAND AT ALL
TODAY. IN FACT IT MAY NOT MOVE MUCH FROM ITS CURRENT LOCATION WHICH
COULD NECESSITATE RAISING POPS ALONG THE GRAND STRAND. STORM MOTION
ALSO SHOWING CONSIDERABLE VARIABILITY TODAY DUE TO THE LEFTOVER
UPPER SHEAR AXIS OVER THE REGION.
AS OF 700 AM TUESDAY...A LARGE CLUSTER OF THUNDERSTORMS PRODUCING
HEAVY RAIN HAS DEVELOPED ACROSS THE SANDHILLS AND SOUTHERN PIEDMONT
OF NC. THIS CONVECTION IS DRIFTING SOUTHEASTWARD...PIVOTING AROUND
THE INLAND SIDE OF THE UPPER SHEAR AXIS THAT IS LINED UP ALONG THE
INTERSTATE 95 CORRIDOR. THE LATEST SEVERAL HRRR MODEL RUNS TAKE THIS
CONVECTION SOUTHEASTWARD INTO THE BENNETTSVILLE AND DARLINGTON AREA
OVER THE NEXT COUPLE OF HOURS...BUT DIVERGE FROM RUN TO RUN AS TO
WHAT HAPPENS LATER THIS MORNING. PRIOR RUNS SHOWED THE CONVECTION
CONTINUING TO RUN SOUTH/SOUTHEASTWARD THROUGH NOON...WHILE THE
LATEST RUN (08Z) DISSIPATES THE CURRENT CLUSTER WHILE DEVELOPING NEW
CONVECTION JUST INLAND FROM THE COAST BY LATE MORNING AHEAD OF THE
DEVELOPING SEABREEZE BOUNDARY.
THE TAKE-HOME MESSAGE FROM ALL THIS IS THAT WE HAVE AN AIRMASS THAT
REALLY WANTS TO PRODUCE CONVECTION GIVEN ANY POSSIBLE REASON.
CONVECTIVE OUTFLOW BOUNDARIES FROM THE CURRENT ACTIVITY PLUS THE
DEVELOPMENT OF A SEABREEZE THIS AFTERNOON SHOULD ENSURE THERE ARE
PLENTY OF REASONS FOR NEW CONVECTIVE DEVELOPMENT...THEREFORE I HAVE
RAISED POPS INTO THE LIKELY CATEGORY FOR MOST AREAS MORE THAN 20
MILES INLAND FROM THE COAST TODAY. WEST OF INTERSTATE 95 I HAVE
RAISED POPS INTO THE 70-90 PERCENT RANGE...ANTICIPATING THE CURRENT
SANDHILLS CONVECTION WILL SOAK THIS AREA IN THE NEXT FEW HOURS.
RAINFALL OVER THE PAST THREE DAYS HAS AVERAGED 2 TO 5 INCHES WEST OF
INTERSTATE 95 EXCEPT FOR THE WESTERN THIRD OF DARLINGTON COUNTY
WHERE BARELY ONE INCH HAS FALLEN. GIVEN SOME OF THE RADAR-ESTIMATED
TOTALS FROM ROCKINGHAM TO WEST OF CHERAW THIS MORNING IT IS POSSIBLE
FLOOD ADVISORIES OR WARNINGS MAY BE NEEDED IN MY PEE DEE COUNTIES IN
THE NEXT SEVERAL HOURS.
PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
THE WEAK UPPER LEVEL DISTURBANCE THAT BEGAN THIS RECENT WET PERIOD
SEVERAL DAYS AGO HAS DEGENERATED INTO A 500-TO-700 MB SHEAR AXIS.
WIND SPEEDS SURROUNDING THE UPPER FEATURE ARE TOO WEAK AT THIS POINT
TO SUPPORT DYNAMIC LIFT...BUT RICH LOW AND MID LEVEL MOISTURE
REMAINS IN PLACE ACROSS THE EASTERN CAROLINAS WITH PRECIPITABLE
WATER VALUES AROUND 1.7 INCHES. THE LACK OF ANY CONVECTIVE
CAP...DEEP-LAYER ENVIRONMENTAL LAPSE RATES SLIGHTLY STEEPER THAN THE
MOIST ADIABATIC LAPSE RATE...AND THIS AFTERNOON`S SEABREEZE BOUNDARY
SHOULD HELP PRODUCE ANOTHER ROUND OF SCATTERED SHOWERS AND
THUNDERSTORMS. SLOW STORM MOTION AND A DEEP REGION (NEARLY 10000
FEET DEEP) WHERE EFFICIENT WARM-CLOUD COALESCENCE PROCESSES WILL
DOMINATE SHOULD ALLOW HEAVY RAINFALL TO OCCUR. HIGHS THIS AFTERNOON
SHOULD REACH THE LOWER 80S FOR MOST AREAS AWAY FROM THE BEACHES.
SHOWER ACTIVITY SHOULD END QUICKLY THIS EVENING...ALTHOUGH PLENTY OF
RESIDUAL MOISTURE SHOULD ENSURE SKIES REMAIN PARTLY CLOUDY
OVERNIGHT. MODELS HINT AT SOME NOCTURNAL CONVECTIVE DEVELOPMENT OVER
THE OCEAN WHICH MAY MAKE A RUN AT CAPE FEAR LATE TONIGHT. WITH A
LITTLE LESS CLOUD COVER THAN WE HAVE SEEN OVER THE PAST FEW
NIGHTS...LOWS SHOULD DROP INTO THE MID 60S INLAND WITH UPPER 60S AT
THE COAST.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM TUESDAY...MID LEVEL RIDGING AND BERMUDA HIGH PRESSURE
PERSIST ON WEDNESDAY BEFORE PATTERN CHANGE FINALLY OCCURS LATE IN
THE PERIOD. WHILE TEMPS BOTH DAYS WILL CONTINUE TO BE SEVERAL
DEGREES ABOVE CLIMO...MID AND UPPER 80S...WEDNESDAY IS LIKELY TO BE
A DRIER DAY WITH ONLY ISOLATED CONVECTION DUE TO SUBSIDENCE/CAPPING
BENEATH THE 5H RIDGE. 5H RIDGE...AS QUOTED BY THE PREVIOUS
FORECASTER...BREAKS DOWN SURPRISINGLY QUICKLY...THURSDAY AS LONGWAVE
TROUGH EXITS THE MIDWEST AND PUSHES EAST. THIS IN ITSELF WILL LEAD
TO INCREASED CONVECTION CHANCES THURSDAY DUE TO COOLER TEMPS ALOFT
STEEPENING LAPSE RATES. AN ADDITIONAL FACTOR TO CONVECTION THURSDAY
WILL BE THE APPROACH OF A COLD FRONT WHICH IS NOW PROGGED TO CROSS
THE AREA OVERNIGHT THURSDAY NIGHT. WITH GOOD THETA-E ADVECTION AHEAD
OF THIS BOUNDARY...WILL BUMP POP TO HIGH CHC EVEN THURSDAY NIGHT FOR
SHOWERS/TSTMS...WITH DRYING OCCURRING IN THE COLUMN AT THE VERY END
OF THE PERIOD.
MINS WED NIGHT WILL BE WELL ABOVE NORMAL...UPPER 60S TO NEAR 70.
SEVERAL DEGREES COOLER THURSDAY NIGHT AS THE FROPA OCCURS...FALLING
INTO THE LOW/MID 60S.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 300 AM TUESDAY...BEAUTIFUL LATE MAY WEATHER EXPECTED FOR THE
EXTENDED AS DRIER BUT STILL SEASONABLE AIR DEVELOPS ACROSS THE
CAROLINAS. COLD FRONT WILL BE JUST EXITING OFFSHORE AT THE START OF
THE PERIOD...WITH MUCH DRIER AIR FLOODING IN BEHIND IT AS A HIGH
PRESSURE BUILDS DOWN FROM THE NW. WHILE A FEW SHOWERS MAY LINGER
VERY EARLY FRIDAY...WILL QUICKLY RAMP POP DOWN TO SILENT FRIDAY
THROUGH MONDAY AS HIGH PRESSURE BUILDS ACROSS THE AREA HELPING PWATS
DROP TO WELL BELOW ONE INCH. EVEN WITH HIGH PRESSURE BUILDING DOWN
FROM THE NW...THE OVERALL AIR MASS CHANGE WILL BE ONE TO MUCH DRIER
CONDITIONS AS OPPOSED TO MUCH COOLER...WITH TEMPS FALLING TO JUST A
FEW DEGREES BELOW CLIMO...AND A NEAR PERFECT LATE-SPRING WKND
APPEARS TO BE IN STORE FOR THIS AREA.
&&
.AVIATION /18Z TUESDAY THROUGH SATURDAY/...
AS OF 18Z...MAINLY VFR/MVFR CONDITIONS ARE BEING REPORTED ACROSS THE
CWA THIS AFTN WITH SOUTH WINDS 8-12 KTS. CONVECTION HAS ALREADY
FIRED ALONG THE SEA BREEZE BOUNDARY THIS MORNING...MAINLY NEAR
KMYR/KCRE. MORE SHOWERS/T-STORMS ARE POSSIBLE TODAY WITH CONTINUED
DIURNAL HEATING. HAVE INCLUDED VCSH/VCTS AT ALL TERMS THROUGH
00Z...ALTHOUGH THE LATEST HRRR RUNS SUGGEST PCPN THIS AFTN MAY BE
MORE CONCENTRATED INLAND. VERY BRIEF PERIODS OF IFR ARE POSSIBLE IN
HEAVIER DOWNPOURS. THE ABUNDANT LOW-LEVEL MOISTURE IN PLACE COULD
ALLOW MVFR CIGS/VSBYS TO DEVELOP OVERNIGHT. EXPECT MOSTLY CLOUDY
CONDITIONS AGAIN ON WEDNESDAY WITH SOUTH WINDS AROUND 8-12 KTS.
EXTENDED OUTLOOK...SLIGHT CHC OF SHOWERS WEDNESDAY. SHOWERS/T-STORMS
POSSIBLE THURSDAY THROUGH EARLY FRIDAY. OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM TUESDAY...NO SIGNIFICANT CHANGES ARE NEEDED TO THE
FORECAST. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
THERE HAS BEEN AMAZINGLY LITTLE CHANGE IN THE OVERALL SYNOPTIC
WEATHER PATTERN OVER THE PAST 24 HOURS. HIGH PRESSURE HAS DROPPED
SOUTH TO NEAR BERMUDA WHILE LOW PRESSURE IN THE NORTHERN PLAINS IS
STILL SITTING OVER EASTERN SOUTH DAKOTA. THIS WILL ENSURE A SOUTH
WIND AT 10-15 KNOTS CONTINUES TODAY THROUGH TONIGHT. SCATTERED
SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL BE MOST NUMEROUS THIS
MORNING...WITH SUBSIDENCE BEHIND THE SEABREEZE CLEARING OUT MOST OF
THIS ACTIVITY FROM THE COASTAL WATERS THIS AFTERNOON. SEAS CURRENTLY
RANGE FROM 3-4 FT ON BUOYS IN THE CAPE FEAR VICINITY...IN A
COMBINATION OF 10 SECOND EASTERLY SWELL AND A 6 SECOND SOUTHERLY
WIND WAVE.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM TUESDAY...BERMUDA HIGH PRESSURE REMAINS IN PLACE
WEDNESDAY BEFORE GRADUALLY PUSHING AWAY THURSDAY THANKS TO A COLD
FRONT WHICH WILL CROSS THE WATERS AT THE VERY END OF THE PERIOD.
WITH BERMUDA HIGH IN PLACE WED...RETURN FLOW CREATES S/SW WINDS OF
10-15 KTS...CREATING SEAS OF 2-4 FT WITH A 6 SEC SOUTHERLY WIND WAVE
DOMINANT IN THE WAVE SPECTRUM. BY THURSDAY...WINDS BEGIN TO VEER
SLOWLY AS COLD FRONT APPROACHES FROM THE WEST. WINDS WILL REMAIN
10-15 KTS...BUT VEER TO THE SW THU AFTN AND THEN FINALLY TO THE WEST
LATE THURSDAY NIGHT WITH THE ACTUAL FROPA. SEAS WILL BRIEFLY RISE TO
3-5 FT DURING THURSDAY...BEFORE FALLING BACK TO 2-4 FT AT THE END OF
THE PERIOD.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 300 AM TUESDAY...COLD FRONT EXITING OFFSHORE AT THE START OF
THE PERIOD...WITH HIGH PRESSURE BUILDING DOWN FROM THE NW INTO
SATURDAY. WINDS WILL VEER SIGNIFICANTLY DURING THE PERIOD...FROM
WEST AROUND 10 KTS FRIDAY MORNING...TO NORTH AT 15 KTS FRIDAY
NIGHT...THEN NE AT 15-20 KTS ON SATURDAY THANKS TO A PINCHED
PRESSURE GRADIENT JUST OFFSHORE. SEAS WILL BE ENTIRELY WIND-WAVE
DOMINATED DURING THE EXTENDED...BUILDING FROM 2-4 FT FRIDAY...TO 3-5
FT ON SATURDAY WITH A NORTHERLY CHOP BECOMING PREDOMINANT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JDW
NEAR TERM...MBB/TRA
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
739 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A WEAK UPPER LEVEL DISTURBANCE AND HIGH PRESSURE OFFSHORE WILL
CONTINUE TO PRODUCE SCATTERED SHOWERS AND THUNDERSTORMS TODAY. DRIER
AND WARMER WEATHER IS EXPECTED FOR MID-WEEK. A COLD FRONT WILL
APPROACH AND CROSS THE REGION EARLY FRIDAY. COOLER AND DRIER WEATHER
WILL DEVELOP FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 700 AM TUESDAY...A LARGE CLUSTER OF THUNDERSTORMS PRODUCING
HEAVY RAIN HAS DEVELOPED ACROSS THE SANDHILLS AND SOUTHERN PIEDMONT
OF NC. THIS CONVECTION IS DRIFTING SOUTHEASTWARD...PIVOTING AROUND
THE INLAND SIDE OF THE UPPER SHEAR AXIS THAT IS LINED UP ALONG THE
INTERSTATE 95 CORRIDOR. THE LATEST SEVERAL HRRR MODEL RUNS TAKE THIS
CONVECTION SOUTHEASTWARD INTO THE BENNETTSVILLE AND DARLINGTON AREA
OVER THE NEXT COUPLE OF HOURS...BUT DIVERGE FROM RUN TO RUN AS TO
WHAT HAPPENS LATER THIS MORNING. PRIOR RUNS SHOWED THE CONVECTION
CONTINUING TO RUN SOUTH/SOUTHEASTWARD THROUGH NOON...WHILE THE
LATEST RUN (08Z) DISSIPATES THE CURRENT CLUSTER WHILE DEVELOPING NEW
CONVECTION JUST INLAND FROM THE COAST BY LATE MORNING AHEAD OF THE
DEVELOPING SEABREEZE BOUNDARY.
THE TAKE-HOME MESSAGE FROM ALL THIS IS THAT WE HAVE AN AIRMASS THAT
REALLY WANTS TO PRODUCE CONVECTION GIVEN ANY POSSIBLE REASON.
CONVECTIVE OUTFLOW BOUNDARIES FROM THE CURRENT ACTIVITY PLUS THE
DEVELOPMENT OF A SEABREEZE THIS AFTERNOON SHOULD ENSURE THERE ARE
PLENTY OF REASONS FOR NEW CONVECTIVE DEVELOPMENT...THEREFORE I HAVE
RAISED POPS INTO THE LIKELY CATEGORY FOR MOST AREAS MORE THAN 20
MILES INLAND FROM THE COAST TODAY. WEST OF INTERSTATE 95 I HAVE
RAISED POPS INTO THE 70-90 PERCENT RANGE...ANTICIPATING THE CURRENT
SANDHILLS CONVECTION WILL SOAK THIS AREA IN THE NEXT FEW HOURS.
RAINFALL OVER THE PAST THREE DAYS HAS AVERAGED 2 TO 5 INCHES WEST OF
INTERSTATE 95 EXCEPT FOR THE WESTERN THIRD OF DARLINGTON COUNTY
WHERE BARELY ONE INCH HAS FALLEN. GIVEN SOME OF THE RADAR-ESTIMATED
TOTALS FROM ROCKINGHAM TO WEST OF CHERAW THIS MORNING IT IS POSSIBLE
FLOOD ADVISORIES OR WARNINGS MAY BE NEEDED IN MY PEE DEE COUNTIES IN
THE NEXT SEVERAL HOURS.
PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
THE WEAK UPPER LEVEL DISTURBANCE THAT BEGAN THIS RECENT WET PERIOD
SEVERAL DAYS AGO HAS DEGENERATED INTO A 500-TO-700 MB SHEAR AXIS.
WIND SPEEDS SURROUNDING THE UPPER FEATURE ARE TOO WEAK AT THIS POINT
TO SUPPORT DYNAMIC LIFT...BUT RICH LOW AND MID LEVEL MOISTURE
REMAINS IN PLACE ACROSS THE EASTERN CAROLINAS WITH PRECIPITABLE
WATER VALUES AROUND 1.7 INCHES. THE LACK OF ANY CONVECTIVE
CAP...DEEP-LAYER ENVIRONMENTAL LAPSE RATES SLIGHTLY STEEPER THAN THE
MOIST ADIABATIC LAPSE RATE...AND THIS AFTERNOON`S SEABREEZE BOUNDARY
SHOULD HELP PRODUCE ANOTHER ROUND OF SCATTERED SHOWERS AND
THUNDERSTORMS. SLOW STORM MOTION AND A DEEP REGION (NEARLY 10000
FEET DEEP) WHERE EFFICIENT WARM-CLOUD COALESCENCE PROCESSES WILL
DOMINATE SHOULD ALLOW HEAVY RAINFALL TO OCCUR. HIGHS THIS AFTERNOON
SHOULD REACH THE LOWER 80S FOR MOST AREAS AWAY FROM THE BEACHES.
SHOWER ACTIVITY SHOULD END QUICKLY THIS EVENING...ALTHOUGH PLENTY OF
RESIDUAL MOISTURE SHOULD ENSURE SKIES REMAIN PARTLY CLOUDY
OVERNIGHT. MODELS HINT AT SOME NOCTURNAL CONVECTIVE DEVELOPMENT OVER
THE OCEAN WHICH MAY MAKE A RUN AT CAPE FEAR LATE TONIGHT. WITH A
LITTLE LESS CLOUD COVER THAN WE HAVE SEEN OVER THE PAST FEW
NIGHTS...LOWS SHOULD DROP INTO THE MID 60S INLAND WITH UPPER 60S AT
THE COAST.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM TUESDAY...MID LEVEL RIDGING AND BERMUDA HIGH PRESSURE
PERSIST ON WEDNESDAY BEFORE PATTERN CHANGE FINALLY OCCURS LATE IN
THE PERIOD. WHILE TEMPS BOTH DAYS WILL CONTINUE TO BE SEVERAL
DEGREES ABOVE CLIMO...MID AND UPPER 80S...WEDNESDAY IS LIKELY TO BE
A DRIER DAY WITH ONLY ISOLATED CONVECTION DUE TO SUBSIDENCE/CAPPING
BENEATH THE 5H RIDGE. 5H RIDGE...AS QUOTED BY THE PREVIOUS
FORECASTER...BREAKS DOWN SURPRISINGLY QUICKLY...THURSDAY AS LONGWAVE
TROUGH EXITS THE MIDWEST AND PUSHES EAST. THIS IN ITSELF WILL LEAD
TO INCREASED CONVECTION CHANCES THURSDAY DUE TO COOLER TEMPS ALOFT
STEEPENING LAPSE RATES. AN ADDITIONAL FACTOR TO CONVECTION THURSDAY
WILL BE THE APPROACH OF A COLD FRONT WHICH IS NOW PROGGED TO CROSS
THE AREA OVERNIGHT THURSDAY NIGHT. WITH GOOD THETA-E ADVECTION AHEAD
OF THIS BOUNDARY...WILL BUMP POP TO HIGH CHC EVEN THURSDAY NIGHT FOR
SHOWERS/TSTMS...WITH DRYING OCCURRING IN THE COLUMN AT THE VERY END
OF THE PERIOD.
MINS WED NIGHT WILL BE WELL ABOVE NORMAL...UPPER 60S TO NEAR 70.
SEVERAL DEGREES COOLER THURSDAY NIGHT AS THE FROPA OCCURS...FALLING
INTO THE LOW/MID 60S.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 300 AM TUESDAY...BEAUTIFUL LATE MAY WEATHER EXPECTED FOR THE
EXTENDED AS DRIER BUT STILL SEASONABLE AIR DEVELOPS ACROSS THE
CAROLINAS. COLD FRONT WILL BE JUST EXITING OFFSHORE AT THE START OF
THE PERIOD...WITH MUCH DRIER AIR FLOODING IN BEHIND IT AS A HIGH
PRESSURE BUILDS DOWN FROM THE NW. WHILE A FEW SHOWERS MAY LINGER
VERY EARLY FRIDAY...WILL QUICKLY RAMP POP DOWN TO SILENT FRIDAY
THROUGH MONDAY AS HIGH PRESSURE BUILDS ACROSS THE AREA HELPING PWATS
DROP TO WELL BELOW ONE INCH. EVEN WITH HIGH PRESSURE BUILDING DOWN
FROM THE NW...THE OVERALL AIR MASS CHANGE WILL BE ONE TO MUCH DRIER
CONDITIONS AS OPPOSED TO MUCH COOLER...WITH TEMPS FALLING TO JUST A
FEW DEGREES BELOW CLIMO...AND A NEAR PERFECT LATE-SPRING WKND
APPEARS TO BE IN STORE FOR THIS AREA.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 12Z...CURRENT RADAR IMAGERY SHOWS SCT SHOWERS/T-STORMS NEAR
AND WEST OF KFLO WITH MORE SHOWERS OFFSHORE. THERE ARE POCKETS OF
IFR CIGS WITHIN THE CWA...AND KFLO COULD DEVELOP IFR SHORTLY WITH
STORMS MOVING OVERHEAD. HAVE INCLUDED TEMPO -SHRA IN THE NEAR TERM
TO ACCOUNT FOR CURRENT ACTIVITY BASED ON RADAR TRENDS AND LATEST
HRRR RUNS. MORE SHOWERS/T-STORMS WILL DEVELOP TODAY WITH DAYTIME
HEATING. EXPECT VFR/MVFR TO PREVAIL WITH BRIEF PERIODS OF IFR IN
HEAVIER PCPN. BETTER PCPN CHCS WILL BE INLAND THIS AFTN...BUT SOME
SEA BREEZE STORMS COULD DRIFT BACK TOWARDS THE COAST AS WELL. S-SW
WINDS AOB 10 KTS THIS MORNING WILL BECOME SOUTH AROUND 10 KTS THIS
AFTN. MVFR/IFR CIGS/VSBYS ARE CERTAINLY POSSIBLE OVERNIGHT WITH THE
ABUNDANT LOW-LEVEL MOISTURE IN PLACE.
EXTENDED OUTLOOK...SLIGHT CHC OF SHOWERS WEDNESDAY. SHOWERS/T-STORMS
POSSIBLE THURSDAY THROUGH EARLY FRIDAY. OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 700 AM TUESDAY...NO SIGNIFICANT CHANGES ARE NEEDED TO THE
FORECAST. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
THERE HAS BEEN AMAZINGLY LITTLE CHANGE IN THE OVERALL SYNOPTIC
WEATHER PATTERN OVER THE PAST 24 HOURS. HIGH PRESSURE HAS DROPPED
SOUTH TO NEAR BERMUDA WHILE LOW PRESSURE IN THE NORTHERN PLAINS IS
STILL SITTING OVER EASTERN SOUTH DAKOTA. THIS WILL ENSURE A SOUTH
WIND AT 10-15 KNOTS CONTINUES TODAY THROUGH TONIGHT. SCATTERED
SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL BE MOST NUMEROUS THIS
MORNING...WITH SUBSIDENCE BEHIND THE SEABREEZE CLEARING OUT MOST OF
THIS ACTIVITY FROM THE COASTAL WATERS THIS AFTERNOON. SEAS CURRENTLY
RANGE FROM 3-4 FT ON BUOYS IN THE CAPE FEAR VICINITY...IN A
COMBINATION OF 10 SECOND EASTERLY SWELL AND A 6 SECOND SOUTHERLY
WIND WAVE.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM TUESDAY...BERMUDA HIGH PRESSURE REMAINS IN PLACE
WEDNESDAY BEFORE GRADUALLY PUSHING AWAY THURSDAY THANKS TO A COLD
FRONT WHICH WILL CROSS THE WATERS AT THE VERY END OF THE PERIOD.
WITH BERMUDA HIGH IN PLACE WED...RETURN FLOW CREATES S/SW WINDS OF
10-15 KTS...CREATING SEAS OF 2-4 FT WITH A 6 SEC SOUTHERLY WIND WAVE
DOMINANT IN THE WAVE SPECTRUM. BY THURSDAY...WINDS BEGIN TO VEER
SLOWLY AS COLD FRONT APPROACHES FROM THE WEST. WINDS WILL REMAIN
10-15 KTS...BUT VEER TO THE SW THU AFTN AND THEN FINALLY TO THE WEST
LATE THURSDAY NIGHT WITH THE ACTUAL FROPA. SEAS WILL BRIEFLY RISE TO
3-5 FT DURING THURSDAY...BEFORE FALLING BACK TO 2-4 FT AT THE END OF
THE PERIOD.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 300 AM TUESDAY...COLD FRONT EXITING OFFSHORE AT THE START OF
THE PERIOD...WITH HIGH PRESSURE BUILDING DOWN FROM THE NW INTO
SATURDAY. WINDS WILL VEER SIGNIFICANTLY DURING THE PERIOD...FROM
WEST AROUND 10 KTS FRIDAY MORNING...TO NORTH AT 15 KTS FRIDAY
NIGHT...THEN NE AT 15-20 KTS ON SATURDAY THANKS TO A PINCHED
PRESSURE GRADIENT JUST OFFSHORE. SEAS WILL BE ENTIRELY WIND-WAVE
DOMINATED DURING THE EXTENDED...BUILDING FROM 2-4 FT FRIDAY...TO 3-5
FT ON SATURDAY WITH A NORTHERLY CHOP BECOMING PREDOMINANT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JDW
NEAR TERM...TRA
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
720 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A TROUGH OVER THE REGION WILL GRADUALLY WEAKEN THROUGH WEDNESDAY. A
STRONG COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST LATE
THURSDAY... THEN PUSH THROUGH TO THE COAST BY FRIDAY MORNING. COOL
HIGH PRESSURE WILL FOLLOW THE FRONT LATE FRIDAY INTO THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 315 AM TUESDAY...
DELAYED A BIT WITH DISCUSSION TO SEE THE LATEST EC MODEL SINCE
MODELS WERE AT ODDS ON TIMING/LOCATION OF CONVECTION CHANCES TODAY.
WATER VAPOR SATELLITE DATA INDICATED THE WEAKENING MID/UPPER TROUGH
STILL LINGERING OVER THE REGION. PRECIPITABLE WATER VALUES REMAIN
VERY HIGH (GENERALLY 1.5 TO 1.75 INCHES). AT THE SURFACE... A WEAK
TROUGH WAS LOCATED OVER THE EASTERN PIEDMONT WITH DEW POINT VALUES
IN THE UPPER 60S TO NEAR 70. ONLY SCATTERED SHOWERS WERE NOTED OVER
THE COASTAL PLAIN AT 06Z/21 MAY.
THE LATEST HI-RES MODELS... IN PARTICULAR THE HRRR (WHICH PREFORMED
WELL WITH THE CONVECTION ON MONDAY)... BUT INCLUDING THE NMM EAST
AND ARW EAST INDICATE SOME DEVELOPMENT OF CONVECTION WESTWARD
BETWEEN 09Z AND 12Z OVER THE SOUTHERN PIEDMONT AND SANDHILLS
REGION.... SPREADING NE ACROSS THE FAYETTEVILLE AND RALEIGH AREAS
AROUND RUSH HOUR THIS MORNING. INTERESTINGLY ENOUGH... THESE HI-RES
MODELS ALSO INDICATE THE TROUGH AND ASSOCIATED CONVECTION SETTLING
SOUTH INTO THE LOWER COASTAL PLAIN BY THIS AFTERNOON. THIS IS IN
STARK CONTRAST TO THE OPERATIONAL NAM/GFS WHICH BOTH DEPICT AN
UPTICK IN CONVECTION WITH AFTERNOON HEATING... AND LITTLE THIS
MORNING.
IN ADDITION... THE HI-RES MODELS ALSO SHOW THE CURRENT LINE OF
STORMS OVER WESTERN KY/TN SURGING TOWARD THE APPALACHIANS LATER
TODAY... THEN POSSIBLY CROSSING THE MOUNTAINS INTO THE PIEDMONT
BETWEEN 00Z-06Z/WED (TONIGHT).
NEEDLESS TO SAY... CONVECTION LOCATION AND TIMING IS DIFFICULT AT
BEST TO FORECAST BEYOND 6 HOURS... THEREFORE WE WILL USE THE LATEST
SATELLITE/RADAR TRENDS... ALONG WITH CURRENT DATA TO TRY TO PIN DOWN
THE FAVORED TIMING/LOCATION OF CONVECTION TODAY AND TONIGHT.
FOR NOW... SINCE THE HRRR PREFORMED WELL MONDAY WITH THIS TROUGH
OVERHEAD... WE WILL LEAN TOWARD SCATTERED CONVECTION THIS MORNING...
WITH ADDITIONAL SCATTERED CONVECTION MAINLY SOUTH AND EAST THIS
AFTERNOON. MORE ISOLATED STORMS EXPECTED TO THE NORTH AND WEST.
HIGHS WILL RETURN TO NORMAL WITH ADDITIONAL HEATING TODAY... LOWER
TO MID 80S.
TONIGHT... AT LEAST SOME CHANCE OF A LINE OF STORMS COMING OUT OF
THE BLUE RIDGE APPROACHING OR AROUND SUNSET. THE AIR MASS SHOULD
BECOME MORE UNSTABLE ESPECIALLY OVER THE WESTERN PIEDMONT DURING
THIS TIME. HOWEVER... MLCAPES OF LESS THAN 1500 J/KG SHOULD YIELD
SUB SEVERE CONVECTION ALONG AND EAST OF THE BLUE RIDGE TODAY OR
TONIGHT. LOW END CHANCE OF SHOWERS/STORMS INTO THE MIDNIGHT HOUR IN
THE WEST... OTHERWISE PARTLY CLOUDY. LOWS IN THE MID TO UPPER 60S.
&&
.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
AS OF 310 AM TUESDAY...
WEAK SHORTWAVE RIDGING OVER THE REGION WILL YIELD MOSTLY DRY AND
WARM WEATHER FOR ONE DAY (WED). HOWEVER...SUFFICIENT MOISTURE WILL
STILL BE IN PLACE OVER THE REGION...WITH PWAT VALUES HOVERING NEAR
1.5 INCHES OR SO. WIDELY SCATTERED AFTERNOON AND EVENING
THUNDERSTORMS CAN BE EXPECTED. HIGHS SHOULD BE IN THE MID/UPPER
80S... WITH OVERNIGHT LOWS IN THE MID/UPPER 60S.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 300 AM TUESDAY...
UPPER LEVEL TROUGH WILL MOVE EASTWARD FROM THE MIDWEST ON
THURSDAY...WHICH WILL PUT THE AREA IN DEEP SOUTH TO SOUTHWESTERLY
FLOW DURING THE DAY. WITH MOISTURE IN PLACE AND SUFFICIENT
INSTABILITY... WITH MLCAPE VALUES OF 500 TO 1000 J/KG...
THUNDERSTORMS WILL DEVELOP DURING THE DAY. BULK SHEAR VALUES NEAR 25
KTS WILL SUPPORT THE DEVELOPMENT OF SOME MULTICELL CLUSTERS... AND
FEW STRONGER STORMS WITH GUSTY WINDS ARE POSSIBLE. NO WIDESPREAD
SEVERE WEATHER IS EXPECTED... AS THE BEST UPPER LEVEL FORCING
REMAINS NORTH OF THE AREA. HIGHS IN THE LOW TO MID 80S... LOWS IN
THE MID 60S.
THE ASSOCIATED COLD FRONT WILL PROGRESS INTO WESTERN NORTH CAROLINA
THURSDAY EVENING... REACHING THE COAST BY ABOUT 12Z FRIDAY. MIDLEVEL
DRYING WILL SPREAD ACROSS THE AREA FRIDAY... ENDING PRECIPITATION
AND DECREASING CLOUD COVER THROUGH THE DAY FROM WEST TO EAST. COLD
ADVECTION WILL TEMPER HIGHS... WHICH WILL BE IN THE MID 70S TO LOW
80S. COOLER LOWS IN THE MID 50S.
THE TROUGH MOVES OFF THE COAST EARLY SATURDAY... WITH AN UPPER LEVEL
RIDGE ACROSS THE MIDDLE OF THE COUNTRY AND THE SURFACE HIGH
POSITIONED WEST OF THE AREA... PUTTING THE REGION IN A NORTHWEST
FLOW REGIME THROUGH THE WEEKEND... AND KEEPING TEMPERATURES
SEVERAL DEGREES BELOW NORMAL THROUGH MONDAY... WITH HIGHS IN THE
UPPER 70S TO NEAR 80.. AND LOWS IN THE MID TO UPPER 50S.
&&
.AVIATION /12Z TUESDAY THROUGH FRIDAY/...
AS OF 715 AM TUESDAY...
24 HOUR TAF PERIOD:
LIFR AND IFR CEILINGS CONTINUE TO PREVAIL WITH MVFR TO VFR
VISIBILITIES AT ALL TERMINALS. CEILINGS SHOULD CONTINUE TO PREVAIL
FOR A FEW HOURS THIS MORNING BEFORE CONDITIONS GRADUALLY IMPROVE
LATE MORNING INTO EARLY AFTERNOON. VFR CONDITIONS EXPECTED THIS
AFTERNOON OUTSIDE OF SOME SCATTERED SHOWERS AND THUNDERSTORMS THAT
WILL BE POSSIBLE ONCE AGAIN. WINDS WILL CONTINUE TO BE LIGHT AND OUT
OF THE SOUTHWEST TODAY. LOWER CEILINGS AND VISIBILITIES ARE PROBABLE
AGAIN TONIGHT BETWEEN GENERALLY BETWEEN 9-13Z OR SO.
LONG TERM: SUB VFR CONDITIONS ARE POSSIBLE AGAIN WEDNESDAY AND
THURSDAY AS SHOWERS AND THUNDERSTORMS WILL CONTINUE OUT AHEAD OF AN
APPROACHING FRONTAL SYSTEM THAT WILL MOVE THROUGH THE AREA LATE
THURSDAY INTO EARLY FRIDAY. VFR CONDITIONS SHOULD RETURN FOR FRIDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...PWB
NEAR TERM...BADGETT
SHORT TERM...BADGETT
LONG TERM...SEC
AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
653 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A WEAK UPPER LEVEL DISTURBANCE AND HIGH PRESSURE OFFSHORE WILL
CONTINUE TO PRODUCE SCATTERED SHOWERS AND THUNDERSTORMS TODAY. DRIER
AND WARMER WEATHER IS EXPECTED FOR MID-WEEK. A COLD FRONT WILL
APPROACH AND CROSS THE REGION EARLY FRIDAY. COOLER AND DRIER WEATHER
WILL DEVELOP FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 700 AM TUESDAY...A LARGE CLUSTER OF THUNDERSTORMS PRODUCING
HEAVY RAIN HAS DEVELOPED ACROSS THE SANDHILLS AND SOUTHERN PIEDMONT
OF NC. THIS CONVECTION IS DRIFTING SOUTHEASTWARD...PIVOTING AROUND
THE INLAND SIDE OF THE UPPER SHEAR AXIS THAT IS LINED UP ALONG THE
INTERSTATE 95 CORRIDOR. THE LATEST SEVERAL HRRR MODEL RUNS TAKE THIS
CONVECTION SOUTHEASTWARD INTO THE BENNETTSVILLE AND DARLINGTON AREA
OVER THE NEXT COUPLE OF HOURS...BUT DIVERGE FROM RUN TO RUN AS TO
WHAT HAPPENS LATER THIS MORNING. PRIOR RUNS SHOWED THE CONVECTION
CONTINUING TO RUN SOUTH/SOUTHEASTWARD THROUGH NOON...WHILE THE
LATEST RUN (08Z) DISSIPATES THE CURRENT CLUSTER WHILE DEVELOPING NEW
CONVECTION JUST INLAND FROM THE COAST BY LATE MORNING AHEAD OF THE
DEVELOPING SEABREEZE BOUNDARY.
THE TAKE-HOME MESSAGE FROM ALL THIS IS THAT WE HAVE AN AIRMASS THAT
REALLY WANTS TO PRODUCE CONVECTION GIVEN ANY POSSIBLE REASON.
CONVECTIVE OUTFLOW BOUNDARIES FROM THE CURRENT ACTIVITY PLUS THE
DEVELOPMENT OF A SEABREEZE THIS AFTERNOON SHOULD ENSURE THERE ARE
PLENTY OF REASONS FOR NEW CONVECTIVE DEVELOPMENT...THEREFORE I HAVE
RAISED POPS INTO THE LIKELY CATEGORY FOR MOST AREAS MORE THAN 20
MILES INLAND FROM THE COAST TODAY. WEST OF INTERSTATE 95 I HAVE
RAISED POPS INTO THE 70-90 PERCENT RANGE...ANTICIPATING THE CURRENT
SANDHILLS CONVECTION WILL SOAK THIS AREA IN THE NEXT FEW HOURS.
RAINFALL OVER THE PAST THREE DAYS HAS AVERAGED 2 TO 5 INCHES WEST OF
INTERSTATE 95 EXCEPT FOR THE WESTERN THIRD OF DARLINGTON COUNTY
WHERE BARELY ONE INCH HAS FALLEN. GIVEN SOME OF THE RADAR-ESTIMATED
TOTALS FROM ROCKINGHAM TO WEST OF CHERAW THIS MORNING IT IS POSSIBLE
FLOOD ADVISORIES OR WARNINGS MAY BE NEEDED IN MY PEE DEE COUNTIES IN
THE NEXT SEVERAL HOURS.
PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
THE WEAK UPPER LEVEL DISTURBANCE THAT BEGAN THIS RECENT WET PERIOD
SEVERAL DAYS AGO HAS DEGENERATED INTO A 500-TO-700 MB SHEAR AXIS.
WIND SPEEDS SURROUNDING THE UPPER FEATURE ARE TOO WEAK AT THIS POINT
TO SUPPORT DYNAMIC LIFT...BUT RICH LOW AND MID LEVEL MOISTURE
REMAINS IN PLACE ACROSS THE EASTERN CAROLINAS WITH PRECIPITABLE
WATER VALUES AROUND 1.7 INCHES. THE LACK OF ANY CONVECTIVE
CAP...DEEP-LAYER ENVIRONMENTAL LAPSE RATES SLIGHTLY STEEPER THAN THE
MOIST ADIABATIC LAPSE RATE...AND THIS AFTERNOON`S SEABREEZE BOUNDARY
SHOULD HELP PRODUCE ANOTHER ROUND OF SCATTERED SHOWERS AND
THUNDERSTORMS. SLOW STORM MOTION AND A DEEP REGION (NEARLY 10000
FEET DEEP) WHERE EFFICIENT WARM-CLOUD COALESCENCE PROCESSES WILL
DOMINATE SHOULD ALLOW HEAVY RAINFALL TO OCCUR. HIGHS THIS AFTERNOON
SHOULD REACH THE LOWER 80S FOR MOST AREAS AWAY FROM THE BEACHES.
SHOWER ACTIVITY SHOULD END QUICKLY THIS EVENING...ALTHOUGH PLENTY OF
RESIDUAL MOISTURE SHOULD ENSURE SKIES REMAIN PARTLY CLOUDY
OVERNIGHT. MODELS HINT AT SOME NOCTURNAL CONVECTIVE DEVELOPMENT OVER
THE OCEAN WHICH MAY MAKE A RUN AT CAPE FEAR LATE TONIGHT. WITH A
LITTLE LESS CLOUD COVER THAN WE HAVE SEEN OVER THE PAST FEW
NIGHTS...LOWS SHOULD DROP INTO THE MID 60S INLAND WITH UPPER 60S AT
THE COAST.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM TUESDAY...MID LEVEL RIDGING AND BERMUDA HIGH PRESSURE
PERSIST ON WEDNESDAY BEFORE PATTERN CHANGE FINALLY OCCURS LATE IN
THE PERIOD. WHILE TEMPS BOTH DAYS WILL CONTINUE TO BE SEVERAL
DEGREES ABOVE CLIMO...MID AND UPPER 80S...WEDNESDAY IS LIKELY TO BE
A DRIER DAY WITH ONLY ISOLATED CONVECTION DUE TO SUBSIDENCE/CAPPING
BENEATH THE 5H RIDGE. 5H RIDGE...AS QUOTED BY THE PREVIOUS
FORECASTER...BREAKS DOWN SURPRISINGLY QUICKLY...THURSDAY AS LONGWAVE
TROUGH EXITS THE MIDWEST AND PUSHES EAST. THIS IN ITSELF WILL LEAD
TO INCREASED CONVECTION CHANCES THURSDAY DUE TO COOLER TEMPS ALOFT
STEEPENING LAPSE RATES. AN ADDITIONAL FACTOR TO CONVECTION THURSDAY
WILL BE THE APPROACH OF A COLD FRONT WHICH IS NOW PROGGED TO CROSS
THE AREA OVERNIGHT THURSDAY NIGHT. WITH GOOD THETA-E ADVECTION AHEAD
OF THIS BOUNDARY...WILL BUMP POP TO HIGH CHC EVEN THURSDAY NIGHT FOR
SHOWERS/TSTMS...WITH DRYING OCCURRING IN THE COLUMN AT THE VERY END
OF THE PERIOD.
MINS WED NIGHT WILL BE WELL ABOVE NORMAL...UPPER 60S TO NEAR 70.
SEVERAL DEGREES COOLER THURSDAY NIGHT AS THE FROPA OCCURS...FALLING
INTO THE LOW/MID 60S.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 300 AM TUESDAY...BEAUTIFUL LATE MAY WEATHER EXPECTED FOR THE
EXTENDED AS DRIER BUT STILL SEASONABLE AIR DEVELOPS ACROSS THE
CAROLINAS. COLD FRONT WILL BE JUST EXITING OFFSHORE AT THE START OF
THE PERIOD...WITH MUCH DRIER AIR FLOODING IN BEHIND IT AS A HIGH
PRESSURE BUILDS DOWN FROM THE NW. WHILE A FEW SHOWERS MAY LINGER
VERY EARLY FRIDAY...WILL QUICKLY RAMP POP DOWN TO SILENT FRIDAY
THROUGH MONDAY AS HIGH PRESSURE BUILDS ACROSS THE AREA HELPING PWATS
DROP TO WELL BELOW ONE INCH. EVEN WITH HIGH PRESSURE BUILDING DOWN
FROM THE NW...THE OVERALL AIR MASS CHANGE WILL BE ONE TO MUCH DRIER
CONDITIONS AS OPPOSED TO MUCH COOLER...WITH TEMPS FALLING TO JUST A
FEW DEGREES BELOW CLIMO...AND A NEAR PERFECT LATE-SPRING WKND
APPEARS TO BE IN STORE FOR THIS AREA.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 06Z...PLENTIFUL LOW-LEVEL MOISTURE HAS LED TO DEVELOPMENT OF
IFR STRATUS CEILINGS INLAND WHICH MAY CONTINUE THROUGH DAYBREAK. THE
ONLY POTENTIAL TO SCOUR OUT THESE LOW CIGS EARLIER WILL BE IF
CONVECTIVE SHOWERS OR T-STORMS CAN DEVELOP ACROSS THE SC PEE DEE
REGION AS SHOWN ON THE LATEST SEVERAL RUNS OF THE HRRR MODEL. THIS
COULD LEAD TO ENOUGH DISTURBANCE OF THE STABLE LOW-LEVEL INVERSION
TO LIFT CEILINGS AT KFLO TEMPORARILY INTO THE VFR RANGE SHORTLY
BEFORE DAYBREAK. ALONG THE COAST VFR CONDITIONS SHOULD PREVAIL
THROUGH DAYBREAK WITH THE POSSIBLE EXCEPTION OF SCATTERED SHOWERS
ADVECTING ONSHORE OFF THE ATLANTIC OCEAN...MAINLY AFTER 09Z...WITH
ACCOMPANYING MVFR CIGS.
AFTER DAYBREAK A TYPICAL SUMMER AIRMASS WILL YIELD SCATTERED SHOWERS
AND THUNDERSTORMS DURING THE HEAT OF THE DAY. PREVAILING SOUTH WINDS
SHOULD SWEEP MOST OF THE ACTIVITY AWAY FROM THE COAST BY
MID-AFTERNOON WITH FLO/LBT SEEING THE BEST POTENTIAL OF VSBY
RESTRICTIONS IN SHOWERS OR STORMS.
EXTENDED OUTLOOK...SCATTERED SHOWERS/TSTMS WITH TEMPO MVFR ON
TUESDAY. CHANCE OF SHOWERS THURSDAY THROUGH EARLY FRIDAY. OTHERWISE
VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 700 AM TUESDAY...NO SIGNIFICANT CHANGES ARE NEEDED TO THE
FORECAST. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS...
THERE HAS BEEN AMAZINGLY LITTLE CHANGE IN THE OVERALL SYNOPTIC
WEATHER PATTERN OVER THE PAST 24 HOURS. HIGH PRESSURE HAS DROPPED
SOUTH TO NEAR BERMUDA WHILE LOW PRESSURE IN THE NORTHERN PLAINS IS
STILL SITTING OVER EASTERN SOUTH DAKOTA. THIS WILL ENSURE A SOUTH
WIND AT 10-15 KNOTS CONTINUES TODAY THROUGH TONIGHT. SCATTERED
SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL BE MOST NUMEROUS THIS
MORNING...WITH SUBSIDENCE BEHIND THE SEABREEZE CLEARING OUT MOST OF
THIS ACTIVITY FROM THE COASTAL WATERS THIS AFTERNOON. SEAS CURRENTLY
RANGE FROM 3-4 FT ON BUOYS IN THE CAPE FEAR VICINITY...IN A
COMBINATION OF 10 SECOND EASTERLY SWELL AND A 6 SECOND SOUTHERLY
WIND WAVE.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM TUESDAY...BERMUDA HIGH PRESSURE REMAINS IN PLACE
WEDNESDAY BEFORE GRADUALLY PUSHING AWAY THURSDAY THANKS TO A COLD
FRONT WHICH WILL CROSS THE WATERS AT THE VERY END OF THE PERIOD.
WITH BERMUDA HIGH IN PLACE WED...RETURN FLOW CREATES S/SW WINDS OF
10-15 KTS...CREATING SEAS OF 2-4 FT WITH A 6 SEC SOUTHERLY WIND WAVE
DOMINANT IN THE WAVE SPECTRUM. BY THURSDAY...WINDS BEGIN TO VEER
SLOWLY AS COLD FRONT APPROACHES FROM THE WEST. WINDS WILL REMAIN
10-15 KTS...BUT VEER TO THE SW THU AFTN AND THEN FINALLY TO THE WEST
LATE THURSDAY NIGHT WITH THE ACTUAL FROPA. SEAS WILL BRIEFLY RISE TO
3-5 FT DURING THURSDAY...BEFORE FALLING BACK TO 2-4 FT AT THE END OF
THE PERIOD.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 300 AM TUESDAY...COLD FRONT EXITING OFFSHORE AT THE START OF
THE PERIOD...WITH HIGH PRESSURE BUILDING DOWN FROM THE NW INTO
SATURDAY. WINDS WILL VEER SIGNIFICANTLY DURING THE PERIOD...FROM
WEST AROUND 10 KTS FRIDAY MORNING...TO NORTH AT 15 KTS FRIDAY
NIGHT...THEN NE AT 15-20 KTS ON SATURDAY THANKS TO A PINCHED
PRESSURE GRADIENT JUST OFFSHORE. SEAS WILL BE ENTIRELY WIND-WAVE
DOMINATED DURING THE EXTENDED...BUILDING FROM 2-4 FT FRIDAY...TO 3-5
FT ON SATURDAY WITH A NORTHERLY CHOP BECOMING PREDOMINANT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JDW
NEAR TERM...TRA
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...TRA
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
322 AM EDT TUE MAY 21 2013
.SYNOPSIS...
WEAK UPPER LEVEL DISTURBANCE AND HIGH PRESSURE OFFSHORE WILL
CONTINUE THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS TODAY. DRIER
AND WARMER WEATHER IS EXPECTED FOR MID-WEEK. A COLD FRONT WILL
APPROACH...AND CROSS THE REGION EARLY FRIDAY. COOLER AND DRIER
WEATHER WILL DEVELOP FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM TUESDAY...THE WEAK UPPER LEVEL DISTURBANCE THAT BEGAN
THIS RECENT WET PERIOD SEVERAL DAYS AGO HAS DEGENERATED INTO A
500-TO-700 MB SHEAR AXIS. WIND SPEEDS SURROUNDING THE UPPER FEATURE
ARE TOO WEAK AT THIS POINT TO SUPPORT DYNAMIC LIFT...BUT RICH LOW
AND MID LEVEL MOISTURE REMAINS IN PLACE ACROSS THE EASTERN CAROLINAS
WITH PRECIPITABLE WATER VALUES AROUND 1.7 INCHES. THE LACK OF ANY
CONVECTIVE CAP...DEEP-LAYER ENVIRONMENTAL LAPSE RATES SLIGHTLY
STEEPER THAN THE MOIST ADIABATIC LAPSE RATE...AND THIS AFTERNOON`S
SEABREEZE BOUNDARY SHOULD HELP PRODUCE ANOTHER ROUND OF SCATTERED
SHOWERS AND THUNDERSTORMS. SLOW STORM MOTION AND A DEEP REGION
(NEARLY 10000 FEET DEEP) WHERE EFFICIENT WARM-CLOUD COALESCENCE
PROCESSES WILL DOMINATE SHOULD ALLOW HEAVY RAINFALL TO OCCUR. HIGHS
THIS AFTERNOON SHOULD REACH THE LOWER 80S FOR MOST AREAS AWAY FROM
THE BEACHES.
SHOWER ACTIVITY SHOULD END QUICKLY THIS EVENING...ALTHOUGH PLENTY OF
RESIDUAL MOISTURE SHOULD ENSURE SKIES REMAIN PARTLY CLOUDY
OVERNIGHT. MODELS HINT AT SOME NOCTURNAL CONVECTIVE DEVELOPMENT OVER
THE OCEAN WHICH MAY MAKE A RUN AT CAPE FEAR LATE TONIGHT. WITH A
LITTLE LESS CLOUD COVER THAN WE HAVE SEEN OVER THE PAST FEW
NIGHTS...LOWS SHOULD DROP INTO THE MID 60S INLAND WITH UPPER 60S AT
THE COAST.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM TUESDAY...MID LEVEL RIDGING AND BERMUDA HIGH PRESSURE
PERSIST ON WEDNESDAY BEFORE PATTERN CHANGE FINALLY OCCURS LATE IN
THE PERIOD. WHILE TEMPS BOTH DAYS WILL CONTINUE TO BE SEVERAL
DEGREES ABOVE CLIMO...MID AND UPPER 80S...WEDNESDAY IS LIKELY TO BE
A DRIER DAY WITH ONLY ISOLATED CONVECTION DUE TO SUBSIDENCE/CAPPING
BENEATH THE 5H RIDGE. 5H RIDGE...AS QUOTED BY THE PREVIOUS
FORECASTER...BREAKS DOWN SURPRISINGLY QUICKLY...THURSDAY AS LONGWAVE
TROUGH EXITS THE MIDWEST AND PUSHES EAST. THIS IN ITSELF WILL LEAD
TO INCREASED CONVECTION CHANCES THURSDAY DUE TO COOLER TEMPS ALOFT
STEEPENING LAPSE RATES. AN ADDITIONAL FACTOR TO CONVECTION THURSDAY
WILL BE THE APPROACH OF A COLD FRONT WHICH IS NOW PROGGED TO CROSS
THE AREA OVERNIGHT THURSDAY NIGHT. WITH GOOD THETA-E ADVECTION AHEAD
OF THIS BOUNDARY...WILL BUMP POP TO HIGH CHC EVEN THURSDAY NIGHT FOR
SHOWERS/TSTMS...WITH DRYING OCCURRING IN THE COLUMN AT THE VERY END
OF THE PERIOD.
MINS WED NIGHT WILL BE WELL ABOVE NORMAL...UPPER 60S TO NEAR 70.
SEVERAL DEGREES COOLER THURSDAY NIGHT AS THE FROPA OCCURS...FALLING
INTO THE LOW/MID 60S.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 300 AM TUESDAY...BEAUTIFUL LATE MAY WEATHER EXPECTED FOR THE
EXTENDED AS DRIER BUT STILL SEASONABLE AIR DEVELOPS ACROSS THE
CAROLINAS. COLD FRONT WILL BE JUST EXITING OFFSHORE AT THE START OF
THE PERIOD...WITH MUCH DRIER AIR FLOODING IN BEHIND IT AS A HIGH
PRESSURE BUILDS DOWN FROM THE NW. WHILE A FEW SHOWERS MAY LINGER
VERY EARLY FRIDAY...WILL QUICKLY RAMP POP DOWN TO SILENT FRIDAY
THROUGH MONDAY AS HIGH PRESSURE BUILDS ACROSS THE AREA HELPING PWATS
DROP TO WELL BELOW ONE INCH. EVEN WITH HIGH PRESSURE BUILDING DOWN
FROM THE NW...THE OVERALL AIR MASS CHANGE WILL BE ONE TO MUCH DRIER
CONDITIONS AS OPPOSED TO MUCH COOLER...WITH TEMPS FALLING TO JUST A
FEW DEGREES BELOW CLIMO...AND A NEAR PERFECT LATE-SPRING WKND
APPEARS TO BE IN STORE FOR THIS AREA.
&&
.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
AS OF 06Z...PLENTIFUL LOW-LEVEL MOISTURE HAS LED TO DEVELOPMENT OF
IFR STRATUS CEILINGS INLAND WHICH MAY CONTINUE THROUGH DAYBREAK. THE
ONLY POTENTIAL TO SCOUR OUT THESE LOW CIGS EARLIER WILL BE IF
CONVECTIVE SHOWERS OR T-STORMS CAN DEVELOP ACROSS THE SC PEE DEE
REGION AS SHOWN ON THE LATEST SEVERAL RUNS OF THE HRRR MODEL. THIS
COULD LEAD TO ENOUGH DISTURBANCE OF THE STABLE LOW-LEVEL INVERSION
TO LIFT CEILINGS AT KFLO TEMPORARILY INTO THE VFR RANGE SHORTLY
BEFORE DAYBREAK. ALONG THE COAST VFR CONDITIONS SHOULD PREVAIL
THROUGH DAYBREAK WITH THE POSSIBLE EXCEPTION OF SCATTERED SHOWERS
ADVECTING ONSHORE OFF THE ATLANTIC OCEAN...MAINLY AFTER 09Z...WITH
ACCOMPANYING MVFR CIGS.
AFTER DAYBREAK A TYPICAL SUMMER AIRMASS WILL YIELD SCATTERED SHOWERS
AND THUNDERSTORMS DURING THE HEAT OF THE DAY. PREVAILING SOUTH WINDS
SHOULD SWEEP MOST OF THE ACTIVITY AWAY FROM THE COAST BY
MID-AFTERNOON WITH FLO/LBT SEEING THE BEST POTENTIAL OF VSBY
RESTRICTIONS IN SHOWERS OR STORMS.
EXTENDED OUTLOOK...SCATTERED SHOWERS/TSTMS WITH TEMPO MVFR ON
TUESDAY. CHANCE OF SHOWERS THURSDAY THROUGH EARLY FRIDAY. OTHERWISE
VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM TUESDAY...THERE HAS BEEN AMAZINGLY LITTLE CHANGE IN THE
OVERALL SYNOPTIC WEATHER PATTERN OVER THE PAST 24 HOURS. HIGH
PRESSURE HAS DROPPED SOUTH TO NEAR BERMUDA WHILE LOW PRESSURE IN THE
NORTHERN PLAINS IS STILL SITTING OVER EASTERN SOUTH DAKOTA. THIS
WILL ENSURE A SOUTH WIND AT 10-15 KNOTS CONTINUES TODAY THROUGH
TONIGHT. SCATTERED SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL BE
MOST NUMEROUS THIS MORNING...WITH SUBSIDENCE BEHIND THE SEABREEZE
CLEARING OUT MOST OF THIS ACTIVITY FROM THE COASTAL WATERS THIS
AFTERNOON. SEAS CURRENTLY RANGE FROM 3-4 FT ON BUOYS IN THE CAPE
FEAR VICINITY...IN A COMBINATION OF 10 SECOND EASTERLY SWELL AND A 6
SECOND SOUTHERLY WIND WAVE.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM TUESDAY...BERMUDA HIGH PRESSURE REMAINS IN PLACE
WEDNESDAY BEFORE GRADUALLY PUSHING AWAY THURSDAY THANKS TO A COLD
FRONT WHICH WILL CROSS THE WATERS AT THE VERY END OF THE PERIOD.
WITH BERMUDA HIGH IN PLACE WED...RETURN FLOW CREATES S/SW WINDS OF
10-15 KTS...CREATING SEAS OF 2-4 FT WITH A 6 SEC SOUTHERLY WIND WAVE
DOMINANT IN THE WAVE SPECTRUM. BY THURSDAY...WINDS BEGIN TO VEER
SLOWLY AS COLD FRONT APPROACHES FROM THE WEST. WINDS WILL REMAIN
10-15 KTS...BUT VEER TO THE SW THU AFTN AND THEN FINALLY TO THE WEST
LATE THURSDAY NIGHT WITH THE ACTUAL FROPA. SEAS WILL BRIEFLY RISE TO
3-5 FT DURING THURSDAY...BEFORE FALLING BACK TO 2-4 FT AT THE END OF
THE PERIOD.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 300 AM TUESDAY...COLD FRONT EXITING OFFSHORE AT THE START OF
THE PERIOD...WITH HIGH PRESSURE BUILDING DOWN FROM THE NW INTO
SATURDAY. WINDS WILL VEER SIGNIFICANTLY DURING THE PERIOD...FROM
WEST AROUND 10 KTS FRIDAY MORNING...TO NORTH AT 15 KTS FRIDAY
NIGHT...THEN NE AT 15-20 KTS ON SATURDAY THANKS TO A PINCHED
PRESSURE GRADIENT JUST OFFSHORE. SEAS WILL BE ENTIRELY WIND-WAVE
DOMINATED DURING THE EXTENDED...BUILDING FROM 2-4 FT FRIDAY...TO 3-5
FT ON SATURDAY WITH A NORTHERLY CHOP BECOMING PREDOMINANT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JDW
NEAR TERM...TRA
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...TRA
MARINE...TRA/JDW
AREA FORECAST DISCUSSION
NWS RALEIGH NC
300 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A TROUGH OVER THE REGION WILL GRADUALLY WEAKEN THROUGH WEDNESDAY. A
STRONG COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST LATE
THURSDAY... THEN PUSH THROUGH TO THE COAST BY FRIDAY MORNING. COOL
HIGH PRESSURE WILL FOLLOW THE FRONT LATE FRIDAY INTO THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 315 AM TUESDAY...
DELAYED A BIT WITH DISCUSSION TO SEE THE LATEST EC MODEL SINCE
MODELS WERE AT ODDS ON TIMING/LOCATION OF CONVECTION CHANCES TODAY.
WATER VAPOR SATELLITE DATA INDICATED THE WEAKENING MID/UPPER TROUGH
STILL LINGERING OVER THE REGION. PRECIPITABLE WATER VALUES REMAIN
VERY HIGH (GENERALLY 1.5 TO 1.75 INCHES). AT THE SURFACE... A WEAK
TROUGH WAS LOCATED OVER THE EASTERN PIEDMONT WITH DEW POINT VALUES
IN THE UPPER 60S TO NEAR 70. ONLY SCATTERED SHOWERS WERE NOTED OVER
THE COASTAL PLAIN AT 06Z/21 MAY.
THE LATEST HI-RES MODELS... IN PARTICULAR THE HRRR (WHICH PREFORMED
WELL WITH THE CONVECTION ON MONDAY)... BUT INCLUDING THE NMM EAST
AND ARW EAST INDICATE SOME DEVELOPMENT OF CONVECTION WESTWARD
BETWEEN 09Z AND 12Z OVER THE SOUTHERN PIEDMONT AND SANDHILLS
REGION.... SPREADING NE ACROSS THE FAYETTEVILLE AND RALEIGH AREAS
AROUND RUSH HOUR THIS MORNING. INTERESTINGLY ENOUGH... THESE HI-RES
MODELS ALSO INDICATE THE TROUGH AND ASSOCIATED CONVECTION SETTLING
SOUTH INTO THE LOWER COASTAL PLAIN BY THIS AFTERNOON. THIS IS IN
STARK CONTRAST TO THE OPERATIONAL NAM/GFS WHICH BOTH DEPICT AN
UPTICK IN CONVECTION WITH AFTERNOON HEATING... AND LITTLE THIS
MORNING.
IN ADDITION... THE HI-RES MODELS ALSO SHOW THE CURRENT LINE OF
STORMS OVER WESTERN KY/TN SURGING TOWARD THE APPALACHIANS LATER
TODAY... THEN POSSIBLY CROSSING THE MOUNTAINS INTO THE PIEDMONT
BETWEEN 00Z-06Z/WED (TONIGHT).
NEEDLESS TO SAY... CONVECTION LOCATION AND TIMING IS DIFFICULT AT
BEST TO FORECAST BEYOND 6 HOURS... THEREFORE WE WILL USE THE LATEST
SATELLITE/RADAR TRENDS... ALONG WITH CURRENT DATA TO TRY TO PIN DOWN
THE FAVORED TIMING/LOCATION OF CONVECTION TODAY AND TONIGHT.
FOR NOW... SINCE THE HRRR PREFORMED WELL MONDAY WITH THIS TROUGH
OVERHEAD... WE WILL LEAN TOWARD SCATTERED CONVECTION THIS MORNING...
WITH ADDITIONAL SCATTERED CONVECTION MAINLY SOUTH AND EAST THIS
AFTERNOON. MORE ISOLATED STORMS EXPECTED TO THE NORTH AND WEST.
HIGHS WILL RETURN TO NORMAL WITH ADDITIONAL HEATING TODAY... LOWER
TO MID 80S.
TONIGHT... AT LEAST SOME CHANCE OF A LINE OF STORMS COMING OUT OF
THE BLUE RIDGE APPROACHING OR AROUND SUNSET. THE AIR MASS SHOULD
BECOME MORE UNSTABLE ESPECIALLY OVER THE WESTERN PIEDMONT DURING
THIS TIME. HOWEVER... MLCAPES OF LESS THAN 1500 J/KG SHOULD YIELD
SUB SEVERE CONVECTION ALONG AND EAST OF THE BLUE RIDGE TODAY OR
TONIGHT. LOW END CHANCE OF SHOWERS/STORMS INTO THE MIDNIGHT HOUR IN
THE WEST... OTHERWISE PARTLY CLOUDY. LOWS IN THE MID TO UPPER 60S.
&&
.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
AS OF 310 AM TUESDAY...
WEAK SHORTWAVE RIDGING OVER THE REGION WILL YIELD MOSTLY DRY AND
WARM WEATHER FOR ONE DAY (WED). HOWEVER...SUFFICIENT MOISTURE WILL
STILL BE IN PLACE OVER THE REGION...WITH PWAT VALUES HOVERING NEAR
1.5 INCHES OR SO. WIDELY SCATTERED AFTERNOON AND EVENING
THUNDERSTORMS CAN BE EXPECTED. HIGHS SHOULD BE IN THE MID/UPPER
80S... WITH OVERNIGHT LOWS IN THE MID/UPPER 60S.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 300 AM TUESDAY...
UPPER LEVEL TROUGH WILL MOVE EASTWARD FROM THE MIDWEST ON
THURSDAY...WHICH WILL PUT THE AREA IN DEEP SOUTH TO SOUTHWESTERLY
FLOW DURING THE DAY. WITH MOISTURE IN PLACE AND SUFFICIENT
INSTABILITY... WITH MLCAPE VALUES OF 500 TO 1000 J/KG...
THUNDERSTORMS WILL DEVELOP DURING THE DAY. BULK SHEAR VALUES NEAR 25
KTS WILL SUPPORT THE DEVELOPMENT OF SOME MULTICELL CLUSTERS... AND
FEW STRONGER STORMS WITH GUSTY WINDS ARE POSSIBLE. NO WIDESPREAD
SEVERE WEATHER IS EXPECTED... AS THE BEST UPPER LEVEL FORCING
REMAINS NORTH OF THE AREA. HIGHS IN THE LOW TO MID 80S... LOWS IN
THE MID 60S.
THE ASSOCIATED COLD FRONT WILL PROGRESS INTO WESTERN NORTH CAROLINA
THURSDAY EVENING... REACHING THE COAST BY ABOUT 12Z FRIDAY. MIDLEVEL
DRYING WILL SPREAD ACROSS THE AREA FRIDAY... ENDING PRECIPITATION
AND DECREASING CLOUD COVER THROUGH THE DAY FROM WEST TO EAST. COLD
ADVECTION WILL TEMPER HIGHS... WHICH WILL BE IN THE MID 70S TO LOW
80S. COOLER LOWS IN THE MID 50S.
THE TROUGH MOVES OFF THE COAST EARLY SATURDAY... WITH AN UPPER LEVEL
RIDGE ACROSS THE MIDDLE OF THE COUNTRY AND THE SURFACE HIGH
POSITIONED WEST OF THE AREA... PUTTING THE REGION IN A NORTHWEST
FLOW REGIME THROUGH THE WEEKEND... AND KEEPING TEMPERATURES
SEVERAL DEGREES BELOW NORMAL THROUGH MONDAY... WITH HIGHS IN THE
UPPER 70S TO NEAR 80.. AND LOWS IN THE MID TO UPPER 50S.
&&
.AVIATION /00Z TUESDAY THROUGH FRIDAY/...
AS OF 140 AM TUESDAY...
24 HOUR TAF PERIOD:
LIFR TO IFR CIGS AND MVFR VSBYS EXPECTED THROUGH 13Z-15Z TODAY...
THEN VFR CONDITIONS THIS AFTERNOON. ISOLATED TO SCATTERED
THUNDERSTORMS POSSIBLE THIS AFTERNOON. MVFR TO IFR CIGS AND VSBYS
MAY REDEVELOP LATER TONIGHT 09Z-12Z... FOLLOWED BY VFR CONDITIONS
WEDNESDAY.
LONG TERM:
AREAS OF STRATUS (LIFR TO IFR CIGS) AND VSBYS ARE EXPECTED AGAIN
THURSDAY MORNING. OTHERWISE... MOSTLY VFR CONDITIONS THU-FRI WITH A
CHANCE OF SHOWERS AND THUNDERSTORMS WITH MVFR CIGS/VSBYS BOTH DAYS.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...PWB
NEAR TERM...BADGETT
SHORT TERM...BADGETT
LONG TERM...SEC
AVIATION...PWB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
140 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A TROUGH OVER THE REGION WILL GRADUALLY WEAKEN THROUGH WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 950 PM MONDAY...
THROUGH TONIGHT: THE MAJORITY OF THE SHOWERS HAVE DISSIPATED OR
MOVED OUT OF THE AREA THIS EVENING. A FEW ISOLATED SHOWERS HAVE
DEVELOPED DURING THE PAST COUPLE HOURS...BUT HAVE NOT BEEN HEAVY OR
LONG LASTING. THE 00Z UPPER AIR ANALYSES SHOW THE WAVE OVER CENTRAL
NC FROM 850-500 MB...WITH A SHORTWAVE TROUGH TO THE SOUTHWEST AT 250
MB. AS A PAIR OF VORTICITY MAXIMA EMBEDDED IN THE MID LEVEL TROUGH
PIVOTS OVER EASTERN NC OVERNIGHT...ADDITIONAL SHOWERS COULD DEVELOP
ACROSS THE SOUTHEAST. THE 00Z SOUNDING AT KGSO STILL YIELDS MLCAPE
AROUND 1000-1500 J/KG WITH A MOIST BOUNDARY LAYER AND RELATIVELY
DRIER AIR IN THE MID LEVELS. THE LATEST HRRR SHOWS ADDITIONAL SHOWER
ACTIVITY DEVELOPING ACROSS THE SOUTHEAST AROUND MIDNIGHT AS A MID
LEVEL DISTURBANCE MOVES OVER THE AREA. HAVE INCREASED RAIN CHANCES
IN THE EAST OVERNIGHT TO REFLECT THE POTENTIAL DEVELOPMENT.
TEMPERATURES ACROSS THE AREA ARE IN THE UPPER 60S TO LOW 70S...WITH
OVERNIGHT LOWS IN THE MID 60S EXPECTED.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 215 PM MONDAY...
TUESDAY STILL SHOWS THE UPPER LEVEL TROUGH LINGERING AT LEAST OVER
THE NORTHEASTERN PART OF THE STATE WITH A SURFACE HIGH OVER THE
SOUTHWESTERN ATLANTIC. THE BEST MOISTURE TRANSPORT AND PRECIPITABLE
WATER VALUES WILL SHIFT TO THE EASTERN HALF OF THE STATE TOMORROW
BUT WILL STILL HAVE THE CHANCE FOR SHOWERS AND THUNDERSTORMS TO
DEVELOP WITH DIURNAL HEATING. ONCE AGAIN THE SEVERE THREAT WILL BE
SEVERELY HINDERED BY LACK OF GOOD LAPSE RATES...SHEAR...AND
INSTABILITY IN THE MOISTURE CONVERGENCE ZONE. THE BEST INSTABILITY
WILL BE ACROSS THE TRIAD...WHERE CLOUD COVER SHOULD BE
DECREASED...BUT ALSO WHERE THE LOW LEVELS WILL BE A BIT DRIER. IF WE
CAN GET A STORM TO FORM...THE BEST CHANCE FOR SEVERE STORMS WOULD BE
BACK ACROSS THE NORTHWEST LATE TOMORROW AFTERNOON WITH DAMAGING
WINDS THE PRIMARY THREAT...BUT ONCE AGAIN THIS IS A VERY SMALL
THREAT AND NOT EXPECTING THIS TO HAPPEN AT THIS TIME.
MODELS HAVE COME INTO A BIT BETTER AGREEMENT ON TEMPERATURES FOR
TOMORROW WITH HIGHS IN THE MID 80S EXPECTED ACROSS THE CWA AND
PERHAPS A FEW DEGREES WARMER IN THE TRIAD WHERE THERE WILL BE
GREATER INSOLATION.
TUESDAY NIGHT THINGS WILL BEGIN TO DRY OUT AS THE MESO LOW PUSHES
OFF TO THE NORTHEAST AND WEAK UPPER LEVEL RIDGING TAKES OVER.
SURFACE DEWPOINTS WILL REMAIN IN THE LOWER TO MID 60S AND LOW FOG
AND/OR STRATUS COULD ONCE AGAIN BE A PROBLEM TUESDAY NIGHT INTO
WEDNESDAY MORNING. EXPECT LOWS IN THE MIDDLE 60S TUESDAY NIGHT.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AS OF 240 PM MONDAY...
FOR WEDNESDAY...WEAK SHORTWAVE RIDGING WILL BUILD OVER THE AREA...
WHILE AT THE SURFACE...THE BERMUDA HIGH WILL RIDGE WESTWARD INTO THE
CAROLINAS. ALL OF THIS WILL TRANSLATE TO AN EVEN FURTHER DECREASE IN
PRECIP COVERAGE. HOWEVER...SUFFICIENT MOISTURE WILL STILL BE IN
PLACE OVER THE REGION...WITH PWAT VALUES HOVERING NEAR 1.5 INCHES OR
SO. THEREFORE...AM STILL EXPECTING TO SEE WIDELY SCATTERED TO
SCATTERED DIURNALLY DRIVEN CONVECTION...WITH THE HIGHEST CHANCES
BEING ACROSS THE WESTERN PORTIONS OF THE FORECAST AREA. HIGHS ONCE
AGAIN SHOULD BE IN THE MID/UPPER 80S...WITH OVERNIGHT LOWS IN THE
MID/UPPER 60S.
SHOWER AND THUNDERSTORM COVERAGE SHOULD BEGIN TO INCREASE ONCE AGAIN
BY THE END OF THE WORK WEEK AS THE MID/UPPER LEVEL RIDGE SHIFTS
OFFSHORE AHEAD OF OUR NEXT MID/UPPER LEVEL TROUGH AND ASSOCIATED
COLD FRONT. MODELS REMAIN IN GENERAL AGREEMENT WITH BRINGING THE
FRONT THROUGH THE FORECAST AREA LATE THURSDAY NIGHT/EARLY FRIDAY.
THEREFORE...WILL SHOW POPS HIGHEST POPS CONCENTRATED DURING THE
THURSDAY/EARLY FRIDAY TIME FRAME...THEN DECREASING FROM WEST TO EAST
THROUGHOUT THE DAY ON FRIDAY. BULK SHEAR VALUES WILL INCREASE TO
AROUND 25 KNOTS OR SO...THEREFORE BETTER STORM ORGANIZATION IS
EXPECTED...HOWEVER THE BEST UPPER LEVEL FORCING WILL PASS WELL TO
OUR NORTH. THEREFORE...EVEN THOUGH AN ISOLATED SEVERE STORM CANNOT
BE COMPLETELY RULED OUT...THE OVERALL THREAT REMAINS LOW AT THIS
TIME. WITH THE INCREASED PRECIP CHANCES/CLOUDS ON THURSDAY AND
FRIDAY...TEMPS WILL MOSTLY BE IN THE LOW/MID 80S.
IT STILL APPEARS THE WEEKEND AND INTO EARLY NEXT WEEK WILL BE DRY AS
HIGH PRESSURE BUILDS IN BEHIND THE DEPARTING FRONT. SLIGHTLY COOLER
TEMPS ARE EXPECTED DURING THIS TIME FRAME...GENERALLY THE UPPER 70S
TO LOWER 80S...WITH OVERNIGHT LOWS IN THE 50S.
&&
.AVIATION /00Z TUESDAY THROUGH FRIDAY/...
AS OF 140 AM TUESDAY...
24 HOUR TAF PERIOD:
LIFR TO IFR CIGS AND MVFR VSBYS EXPECTED THROUGH 13Z-15Z TODAY...
THEN VFR CONDITIONS THIS AFTERNOON. ISOLATED TO SCATTERED
THUNDERSTORMS POSSIBLE THIS AFTERNOON. MVFR TO IFR CIGS AND VSBYS
MAY REDEVELOP LATER TONIGHT 09Z-12Z... FOLLOWED BY VFR CONDITIONS
WEDNESDAY.
LONG TERM:
AREAS OF STRATUS (LIFR TO IFR CIGS) AND VSBYS ARE EXPECTED AGAIN
THURSDAY MORNING. OTHERWISE... MOSTLY VFR CONDITIONS THU-FRI WITH A
CHANCE OF SHOWERS AND THUNDERSTORMS WITH MVFR CIGS/VSBYS BOTH DAYS.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...PWB
NEAR TERM...KC
SHORT TERM...ELLIS
LONG TERM...KRR
AVIATION...PWB
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
132 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A DISTURBANCE ALOFT MOVING ACROSS THE AREA WILL MAINTAIN SHOWERS AND
THUNDERSTORMS THROUGH TUESDAY. DRIER AND WARMER WEATHER IS EXPECTED
MID WEEK. A COLD FRONT IS EXPECTED TO APPROACH AND CROSS THE REGION
ON FRIDAY...BRINGING DRIER AND SLIGHTLY COOLER WEATHER INTO THE NEXT
WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
AS OF 130 AM TUESDAY...LATEST SEVERAL HRRR RUNS SHOW INCREASING
POTENTIAL FOR NOCTURNAL CONVECTION LATE TONIGHT...PARTICULARLY IN
THE SC PEE DEE REGION FROM FLORENCE WESTWARD...AND ALSO ACROSS
COASTAL SE NORTH CAROLINA. THAT IS ESSENTIALLY THE ONLY CHANGE TO
THE FORECAST. PREVIOUS DISCUSSION FROM 1100 PM FOLLOWS...
CONVECTIVE ACTIVITY HAS WANED ACROSS THE FA THIS EVENING...NEARLY
IDENTICAL TO WHAT TRANSPIRED SUNDAY EVENING. THE ATM ACROSS THE FA
HAS BEEN ONCE AGAIN TAXED AND BECOME SOMEWHAT STABLE...AND WILL NEED
SOME TIME TO DE-STABILIZE. LIKE LAST EVENING AND OVERNIGHT...THE
DAYS INSOLATION WILL NOT BE AVAILABLE TO AID THIS DESTABILIZATION
PROCESS. WILL HAVE TO RELY...AGAIN LIKE LAST NIGHT...DYNAMICS FROM
WEAK PVA ALOFT AND IN ADDITION...THE SLIGHTLY COLDER TEMPS ALOFT TO
REACH THE FA FROM THE SW-W DIRECTION. LATEST CHS 00Z RAOB INDICATES
SUB -10 C AT 500MB. PWS ACROSS THE FA REMAIN IN THE 1.5 TO 1.7
INCHES...VIA LATEST 00Z RAOB DATA FROM MHX AND CHS. FORECAST STORM
MOTIONS REMAIN SLOW...10 KT OR LESS...WHICH HAS RESULTED IN
SUFFIXING THE CONVECTION WITH HEAVY RAIN POSSIBLE. THE COASTAL
PORTIONS OF THE ILM CWA WILL HAVE THE HIGHEST POPS
ILLUSTRATED...MAINLY OCCURRING DURING THE PRE-DAWN HRS INTO DAYLIGHT
TUESDAY. MIN TEMP FORECAST TWEAKED ACROSS THE FA BUT WILL REMAIN IN
THE MID TO UPPER 60S RANGE PREVIOUSLY FORECAST.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
AS OF 300 PM MONDAY...FORECAST MODELS ARE CONSISTENT IN SHOWING
THE MID LEVEL PATTERN TRANSITIONING FROM WHAT SEEMS LIKE A NEVER
ENDING TROUGH/WEAKNESS TO MORE OF A SOUTHWESTERLY FLOW. THIS IN
RESPONSE TO THE MASSIVE MID LEVEL LOW FINALLY OPENING UP ACROSS
THE NORTHERN PLAINS AND GETTING KICKED OUT.
AT THE SURFACE...BERMUDA HIGH PRESSURE WILL REMAIN THE MAIN PLAYER
ALTHOUGH THIS HAS LITTLE IMPACT OR CHANGE ON PREVAILING CONDITIONS
AS THIS HAS BEEN SECONDARY THE PAST FEW DAYS. POPS REMAIN ON A
DIURNAL CYCLE ALTHOUGH LOWER THROUGH THE PERIOD AS THE MID LEVEL
CATALYST IS ALL BUT REMOVED. HAVE OPTED FOR THE WARMER MAV NUMBERS
FOR TEMPERATURES THROUGH THE PERIOD.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 300 PM MONDAY...ONE LAST DAY OF WARM AND HUMID CONDITIONS ON
THURSDAY AS UPPER TROUGH AND SURFACE COLD FRONT BEAR DOWN ON THE
REGION FROM THE NW. SOMEWHAT SURPRISINGLY MODELS ARE GRAVITATING
TOWARDS A QUICKER SOLUTION AND THE FRONT MAY PUSH THROUGH TUESDAY
NIGHT. AHEAD OF IT SW FLOW AND HEIGHT FALLS SHOULD YIELD BETTER THAN
AVERAGE COVERAGE OF CONVECTION AND WITH A LARGELY PINNED SEABREEZE
THERE MAY BE NO PREFERRED LOCATION FOR MEASURABLE RAINFALL ESP THIS
FAR OUT IN TIME. SYSTEM WILL MOVE A LITTLE BIT SLOWLY OWING TO THE
STRENGTH OF THE DOWNSTREAM RIDGING AND RAIN CHANCES MAY LINGER INTO
FRIDAY ESPECIALLY ALONG THE COAST. MODEST COOLING AND STRONG DRYING
WILL THEN FOLLOW FOR THE WEEKEND AND SOME VERY COMFORTABLE AND
PLEASANT WEATHER APPEARS TO BE ON TAP. DAYTIME DEVIATIONS FROM CLIMO
TEMPS SHOULD BE RATHER SMALL BUT THE NIGHTS MAY TURN COOLISH DUE TO
THE DRYING. THE POST-FRONTAL HIGH MAY MOVE OFF THE COAST ON MONDAY
ALLOWING FOR AN UPTICK IN THE DEWPOINTS.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 06Z...PLENTIFUL LOW-LEVEL MOISTURE HAS LED TO DEVELOPMENT OF
IFR STRATUS CEILINGS INLAND WHICH MAY CONTINUE THROUGH DAYBREAK. THE
ONLY POTENTIAL TO SCOUR OUT THESE LOW CIGS EARLIER WILL BE IF
CONVECTIVE SHOWERS OR T-STORMS CAN DEVELOP ACROSS THE SC PEE DEE
REGION AS SHOWN ON THE LATEST SEVERAL RUNS OF THE HRRR MODEL. THIS
COULD LEAD TO ENOUGH DISTURBANCE OF THE STABLE LOW-LEVEL INVERSION
TO LIFT CEILINGS AT KFLO TEMPORARILY INTO THE VFR RANGE SHORTLY
BEFORE DAYBREAK. ALONG THE COAST VFR CONDITIONS SHOULD PREVAIL
THROUGH DAYBREAK WITH THE POSSIBLE EXCEPTION OF SCATTERED SHOWERS
ADVECTING ONSHORE OFF THE ATLANTIC OCEAN...MAINLY AFTER 09Z...WITH
ACCOMPANYING MVFR CIGS.
AFTER DAYBREAK A TYPICAL SUMMER AIRMASS WILL YIELD SCATTERED SHOWERS
AND THUNDERSTORMS DURING THE HEAT OF THE DAY. PREVAILING SOUTH WINDS
SHOULD SWEEP MOST OF THE ACTIVITY AWAY FROM THE COAST BY
MID-AFTERNOON WITH FLO/LBT SEEING THE BEST POTENTIAL OF VSBY
RESTRICTIONS IN SHOWERS OR STORMS.
EXTENDED OUTLOOK...SCATTERED SHOWERS/TSTMS WITH TEMPO MVFR ON
TUESDAY. CHANCE OF SHOWERS THURSDAY THROUGH EARLY FRIDAY. OTHERWISE
VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 130 AM TUESDAY...NO SIGNIFICANT CHANGES TO THE FORECAST NEEDED
EARLY THIS MORNING. PREVIOUS DISCUSSION FROM 1100 PM FOLLOWS...
SSE-SSW WINDS TO REMAIN 10 TO OCCASIONALLY 15 KT OVERNIGHT. THIS IN
RESPONSE TO RIDGING FROM THE WESTERN ATLANTIC HIGH. SOUTH OF THE SFC
RIDGING...AN ESE-SSE FLOW EXTENDS FROM WELL OFFSHORE AND ACROSS A
DECENT FETCH LEADING UP TO THE SE U.S. COAST. THIS HAS RESULTED IN
AN EVOLVING AND BUILDING SE GROUND SWELL AT 2 TO 4 FT EXHIBITING 7
TO 8 SECOND PERIODS...JUST PRIOR TO ENTERING THE ILM COASTAL WATERS.
SEE LATEST 41013 BUOY DATA. COMBINED WITH 3 TO 5 SECOND PERIOD
LOCALLY PRODUCED WIND DRIVEN WAVES...SIGNIFICANT SEAS ACROSS THE
COASTAL WATERS WILL RUN A SOLID 3 TO 4 FT...WITH 5 FOOTERS POSSIBLE
ACROSS THE OUTER WATERS OFF CAPE FEAR. OVERALL...THE WIND AND
SIGNIFICANT SEAS FORECAST REMAINS ON TRACK. ONLY UPDATE WAS TO
RESTRUCTURE POPS ACROSS THE COASTAL WATERS TO ACCOUNT FOR THE
DIMINISHED CONVECTION THIS EVENING...FOLLOWED BY AN INCREASING
COVERAGE TOWARD DAYBREAK TUE.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 PM MONDAY...BERMUDA HIGH PRESSURE REMAINS THE MAIN FEATURE
FOR THE COASTAL WATERS WITH A SOUTHERLY FLOW EXPECTED TO CONTINUE
THROUGH THE PERIOD. SPEEDS WILL CONTINUE IN A 10-15 KNOT RANGE
WITH A SLIGHT INCREASE CLOSER TO THE COAST EACH LATE MORNING AND
AFTERNOON WITH THE SEA BREEZE. THE LATEST RUN OF SWAN REMAINS
CONSISTENT WITH 2-4 FOOT SEAS.
LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 300 PM MONDAY...COAST WILL LIE BETWEEN STRONG HIGH PRESSURE
ACROSS THE WEST-CENTRAL ATLANTIC AND APPROACHING COLD FRONT TO THE
NW. THE LATTER WILL BE DISPLACED EASTWARD OF THE MORE TYPICAL
BERMUDA HIGH POSITION WHICH WILL ACT TO EASE THE GRADIENT OTHERWISE
EXPECTED GIVEN SUCH A LARGE ANTICYCLONE. THE RESULTING SWELL ENERGY
COULD BRING SOME SCEC-WORTHY 5 FT SEAS TO PART OF THE AREA MAINLY
NORTHERN ZONES. COLD FRONT NOW APPEARS FASTER THAN PREVIOUSLY
THOUGHT AND SHOULD YIELD VEERING WINDS BY FRIDAY MORNING WITH A TURN
TO OFFSHORE. THE OFFSHORE FETCH AND SWELL DISRUPTION WILL LEAD TO
LOWER SEAS ON FRIDAY BUT THEN THE ENSUING PUSH OF DRY HIGH PRESSURE
COULD TIGHTEN THE GRADIENT AGAIN TO WHERE HEADLINES TOUGH TO RULE
OUT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SHK
NEAR TERM...DCH/TRA
SHORT TERM...SHK
LONG TERM...MBB
AVIATION...SGL/TRA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
326 PM CDT TUE MAY 21 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 327 PM CDT TUE MAY 21 2013
THE HIGHLIGHT OF THE SHORT TERM IS THE END OF THE LONG DURATION
RAINFALL EVENT ACROSS THE AREA.
FOR TONIGHT...THE RAP THROUGHOUT THE DAY HAS HAD A GOOD HANDLE ON
THE STRATUS DECK ACROSS THE AREA..AND FOLLOWED ITS LATEST 19 UTC
RUN FOR CLOUD COVER THROUGH THE NIGHT WHICH ADVECTS DRIER AIR
SOUTHWEST AND SCOURS OUT THE STRATUS. DID ADD A MENTION OF FOG TO
THE NORTHWEST AND NORTH CENTRAL WHERE SKIES FIRST CLEAR TONIGHT
AND WINDS BECOME LIGHT...ALLOWING FOR GOOD RADIATIONAL COOLING
INTO THE UPPER 30S AND SATURATION IN LIGHT OF THE RECENT RAINFALL.
A QUIET WEDNESDAY IS FORECAST WITH A SURFACE RIDGE AXIS ACROSS THE
AREA. GIVEN GOOD MODEL AGREEMENT...USED A BLEND OF THE 12 UTC
GEM/GFS/NAM/ECMWF AND 15 UTC SREF FOR ALL FIELDS...WITH GENERALLY
SUNNY SKIES AND HIGHS IN THE 60S.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 327 PM CDT TUE MAY 21 2013
BY WEDNESDAY NIGHT AN UPPER LEVEL SHORTWAVE RIDGE BETWEEN THE
EXITING LOW PRESSURE SYSTEM TO THE EAST...AND THE ESTABLISHED UPPER
LEVEL LOW OVER THE WEST COAST/ROCKIES...WILL BE SITUATED OVER THE
PLAINS OF NORTH AMERICA. AT THE SURFACE...COOL HIGH PRESSURE RIDGE
MOVING SOUTH FROM CANADA NOSES INTO THE DAKOTAS.
BY THURSDAY THE SURFACE PRESSURE GRADIENT INCREASES AS THE
INTENSIFYING SURFACE LOW OVER THE ROCKIES/LEE OF THE ROCKIES SETS UP
A STRONGER SOUTHERLY/SOUTHEASTERLY WIND FLOW ACROSS THE WESTERN
PLAINS. SOUTHEAST WINDS 20 TO 30 MPH CAN BE EXPECTED OVER THE
WESTERN THIRD OF NORTH DAKOTA.
FRIDAY THROUGH THE MEMORIAL DAY WEEKEND...THE LARGE UPPER LEVEL LOW
OVER THE ROCKIES SETS UP A SOUTHWEST FLOW ALOFT OVER NORTH
DAKOTA...AND A SERIES OF UPPER LEVEL IMPULSES WILL TRAVERSE
NORTHEASTWARD ACROSS THE DAKOTAS. THUS A CHANCE OF THUNDERSTORMS
THROUGHOUT THIS PERIOD.
FAIRLY SEASONABLE TEMPERATURES IN THE LONG TERM...WITH HIGHS IN THE
60S AND 70S AND LOWS IN THE 40S AND 50S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 327 PM CDT TUE MAY 21 2013
MVFR STRATUS WITH OCCASIONAL LIGHT RAIN WILL CONTINUE TO IMPACT
KMOT...KBIS...KJMS AND KDIK THIS AFTERNOON AND EVENING...WITH A
CLEARING TREND FROM NORTH TO SOUTH TONIGHT. HOWEVER...WITH
SUNSET...THE STRATUS DECK MAY LOWER TO IFR BEFORE CLEARING. KISN
SHOULD REMAIN OUTSIDE OF THIS DECK FOR THE 18 UTC TAF CYCLE WITH
VFR CONDITIONS EXPECTED. THERE IS A CHANCE OF FOG TONIGHT AT KMOT
AS SKIES CLEAR WITH RECENT RAINFALL...HOWEVER...IMPACTS ARE STILL
UNCERTAIN AT THIS TIME AND WILL CODE AS VCFG FOR NOW.
&&
.HYDROLOGY...
ISSUED AT 327 PM CDT TUE MAY 21 2013
FLOOD WARNINGS CONTINUE FOR THE PIPESTEM CREEK NEAR PINGREE AND
THE FORECAST POINTS OF TOWNER...BANTRY AND WESTHOPE ON THE SOURIS.
CONTINUING TO MONITOR THE WINTERING RIVER NEAR KARLSRUHE AND THE
WILLOW CREEK NEAR WILLOW CITY WHICH MAY APPROACH FLOOD STAGE IN
THE NEXT 24-48 HOURS. HAVE HELD OFF ON A FLOOD WARNING FOR
NOW...AND WILL WATCH HOW THESE WATERWAYS RESPOND TO RUNOFF.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...AYD
LONG TERM...JV
AVIATION...AYD
HYDROLOGY...AYD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
115 PM CDT TUE MAY 21 2013
.UPDATE...
ISSUED AT 115 PM CDT TUE MAY 21 2013
THE MAIN CHANGE WITH THIS FORECAST UPDATE WAS TO DECREASE SKY
COVER ACROSS THE FAR NORTHWEST AND NORTH CENTRAL...FOLLOWING THE
17 UTC RAP FOR CLOUD COVER THROUGH TONIGHT...WHICH HAS HANDLED THE
CLOUD SHIELD WELL SO FAR TODAY. ALSO...REMOVED THE MENTION OF
PRECIPITATION GENERALLY FOR US HIGHWAY 2 AND NORTH...AND REDUCED
POPS TO CHANCE FOR MOST OTHER LOCATIONS OUTSIDE OF THE JAMES RIVER
VALLEY BASED ON RADAR TRENDS.
UPDATE ISSUED AT 953 AM CDT TUE MAY 21 2013
NO SIGNIFICANT CHANGES REQUIRED WITH THIS FORECAST UPDATE AS THE
TREND THROUGH THE REMAINDER OF THE DAY WILL BE A DECREASE IN
PRECIPITATION CHANCES FROM NORTH TO SOUTH AS THE SURFACE LOW
ACROSS EASTERN SOUTH DAKOTA PROPAGATES INTO SOUTHERN MINNESOTA.
ALL MODELS ARE IN GOOD AGREEMENT WITH A BLEND OF THE 00 UTC
GEM/ECMWF...09 UTC SREF...06 UTC GFS AND 12 UTC NAM UTILIZED FOR
TEMPERATURES AND POPS.
UPDATE ISSUED AT 640 AM CDT TUE MAY 21 2013
GRADIENT FLOW HAS DECREASED ACROSS CENTRAL NORTH DAKOTA AS A SURFACE
LOW OVER EASTERN SOUTH DAKOTA WEAKENS AND SHIFTS FARTHER TO THE
SOUTHEAST. AS A RESULT...CANCELLED THE WIND ADVISORY FOR THIS
UPDATE.
OTHERWISE...ONLY MODIFIED HOURLY SENSIBLE WEATHER GRIDS BASED ON
CURRENT OBS/TRENDS. NO MAJOR UPDATES WERE REQUIRED TO THE ONGOING
FORECAST. THE UPDATED GRIDDED AND TEXT PRODUCTS HAVE BEEN SENT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 414 AM CDT TUE MAY 21 2013
FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE ONGOING
RAIN AND WIND ASSOCIATED WITH THE STORM SYSTEM OVER THE REGION.
CURRENTLY...LARGE STACKED LOW PRESSURE SYSTEM OVER THE NORTHERN
PLAINS...CENTERED OVER WESTERN SOUTH DAKOTA. SEVERAL EMBEDDED
VORTICITY MAXIMUMS/CYCLONIC CIRCULATIONS ROTATING AROUND/WITHIN
THE LARGE LOW. RAIN IS MORE SCATTERED IN NATURE THIS MORNING
COMPARED TO THE PAST FEW DAYS WITH MOST OBS REPORTING LIGHT
RAIN RATHER THAN MODERATE OR HEAVY. PRESSURE GRADIENT SLOWLY
DIMINISHING OVER MY EAST BUT AM STILL SEEING GUSTY WINDS AT ROLLA
AND RUGBY TO OVER 40 MPH. THUS WILL MAINTAIN THE WIND ADVISORY AS
IS EAST OF HIGHWAY 83 AND NORTH IF I94 WITH THIS FORECAST PACKAGE.
100KT JET STREAK SOUTHEAST OF THE LOW FROM EASTERN KANSAS
NORTHEAST INTO THE WESTERN GREAT LAKES REGION...ALONG WITH A
SOUTHERN STREAM S/WV TROUGH MOVING EAST ACROSS NORTHERN
TEXAS TODAY...WILL ALL HELP TO NUDGE THE UPPER LOW SLOWLY
SOUTHEAST BEGINNING THIS AFTERNOON...ALLOWING A RIDGE OF HIGH
PRESSURE OVER SOUTH CENTRAL CANADA TO BUILD SOUTHWARD INTO THE
NORTHERN PLAINS TONIGHT. SEVERAL MORE EMBEDDED WAVES ROTATING
AROUND THE LOW WILL STILL BRING LIGHT RAINFALL TO MOST LOCATIONS
THIS MORNING...BUT WILL SEE CHANCES DECREASE NORTH LATER
TODAY...WITH THIS TREND (DECREASING PRECIPITATION CHANCES FROM
NORTH TO SOUTH) CONTINUING TONIGHT. WITH LESS THAN A QUARTER OF AN
INCH OF ADDITIONAL RAINFALL NOW EXPECTED FROM THIS STORM
SYSTEM...WE OPTED TO CANCEL THE FLOOD WATCH WITH FURTHER
HYDROLOGIC IMPACTS EXPECTED TO BE MINIMAL.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 414 AM CDT TUE MAY 21 2013
LIGHT RAIN WILL CONTINUE TO TAPER OFF FROM NORTHWEST TO SOUTHEAST
WEDNESDAY AS HIGH PRESSURE BUILDS INTO WESTERN NORTH DAKOTA. DRY
CONDITIONS ARE EXPECTED AREA WIDE WEDNESDAY NIGHT AND WILL CONTINUE
THROUGH THURSDAY NIGHT AS A MID-LEVEL RIDGE AXIS CRESTS ACROSS THE
REGION. NEAR NORMAL TEMPERATURES ARE EXPECTED.
THE MEDIUM RANGE MODELS CONTINUE TO PROG AN UNSETTLED WEATHER
PATTERN TO DEVELOP OVER WESTERN AND CENTRAL NORTH DAKOTA FRIDAY
THROUGH THE WEEKEND...AND INTO MONDAY. SOUTHWESTERLY FLOW ALOFT WILL
DEVELOP AS AN UPPER LEVEL LOW SPINS OVER THE PACIFIC NORTHWEST.
PERIODIC ENERGY TRAVERSING THE MEAN FLOW ALOFT WILL GENERATE CHANCES
FOR THUNDERSTORMS. GIVEN THE TIMING UNCERTAINTY...CONTINUED TO BROAD
BRUSH A CHANCE FOR THUNDERSTORMS EACH DAY IN THE LATTER PART OF THE
EXTENDED. IT IS STILL TOO EARLY TO TRY AND TARGET WHICH DAY WILL
HAVE THE HIGHEST POTENTIAL FOR SEVERE WEATHER...IF ANY SEVERE
WEATHER DEVELOPS AT ALL. AS A RESULT...SIDED WITH THE SPC AND THINK
THE POTENTIAL FOR SEVERE WEATHER IS TOO LOW AT THIS TIME.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY)
ISSUED AT 115 PM CDT TUE MAY 21 2013
MVFR STRATUS WITH SCATTERED LIGHT RAIN WILL CONTINUE TO IMPACT
KMOT...KBIS...KJMS AND KDIK THIS AFTERNOON AND EVENING...WITH A
CLEARING TREND FROM NORTH TO SOUTH TONIGHT. KISN SHOULD REMAIN
OUTSIDE OF THIS DECK FOR THE 18 UTC TAF CYCLE WITH VFR CONDITIONS
EXPECTED. THERE IS A CHANCE OF FOG TONIGHT AT KMOT AS SKIES CLEAR
WITH RECENT RAINFALL...HOWEVER...IMPACTS ARE STILL UNCERTAIN AT
THIS TIME AND WILL CODE AS VCFG FOR NOW.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AYD
SHORT TERM...NH
LONG TERM...TM
AVIATION...AYD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
109 AM CDT TUE MAY 21 2013
.UPDATE...
ISSUED AT 109 AM CDT TUE MAY 21 2013
MAIN UPDATE EARLY THIS MORNING WAS TO TRIM THE WESTERN EDGE OF THE
WIND ADVISORY WITH WINDS DECREASING ALONG TO WEST OF HIGHWAY 83.
OTHERWISE THE INHERITED FORECAST LOOKS GOOD WITH RAIN CONTINUING
MOST AREAS.
UPDATE ISSUED AT 1008 PM CDT MON MAY 20 2013
MAIN UPDATE THIS EVENING WAS TO ADJUST THE WIND ADVISORY. WINDS
ARE DIMINISHING QUICKLY IN THE NORTHWEST AND EXPECT WINDS
SOUTHWEST TO DROP SOON. THEREFORE WILL CANCEL THE ADVISORY IN THE
WEST. WILL KEEP IT GOING IN THE CENTRAL THROUGH 1 AM CDT. DID
EXTEND THE ADVISORY OVER EASTERN PORTIONS OF CENTRAL NORTH DAKOTA
THROUGH 7 AM BASED MAINLY ON RAP ANALYSIS KEEPING 40-45 KNOT WINDS
AT 925MB INTO THE EARLY MORNING HOURS.
UPDATE ISSUED AT 734 PM CDT MON MAY 20 2013
QUICK UPDATE JUST TO FRESHEN UP GRIDS NOT UPDATED WITH THE
EXPANSION OF THE WIND ADVISORY. NO CHANGES TO THE ADVISORY AT THIS
TIME. WITH NEXT UPDATE MAY NEED TO LOOK INTO EXTENDING EASTERN
COUNTIES THROUGH THE NIGHT. MADE SOME MINOR ADJUSTMENTS TO POPS
THROUGH THE EVENING.
UPDATE ISSUED AT 540 PM CDT MON MAY 20 2013
UPDATE LATE THIS AFTERNOON DUE TO STRONG WINDS. WILL EXTEND THE
WIND ADVISORY FARTHER SOUTH TO INCLUDE AREAS ALONG AND NORTH OF
INTERSTATE 94.
VERY STRONG WINDS ACROSS FAR NORTH CENTRAL NORTH DAKOTA LATE THIS
AFTERNOON WITH WIND GUST TO 48KTS RECORDED AT ROLLA. CURRENT GUSTS
HAVE SUBSIDED BACK TO AROUND 40-42 KNOTS. WILL CONTINUE TO MONITOR
FOR POSSIBLE HIGH WIND WARNING THIS EVENING.
LATEST RAP ANALYSIS SHOWS AROUND 40-45 KNOTS OF WIND AT 925 MB
THROUGH MID EVENING...MAINLY ALONG AND EAST OF THE HIGHWAY 83
CORRIDOR AND ALONG AND NORTH OF INTERSTATE 94. ALSO 850 KNOT WINDS
INCREASE EARLY THIS EVENING ACROSS MUCH OF CENTRAL NORTH DAKOTA.
AFTER COORDINATION WITH FGF...WILL EXTEND THE CURRENT WIND
ADVISORY FARTHER SOUTH TO ALONG AND NORTH OF INTERSTATE 94...AND
KEEP AN EYE ON WINDS ACROSS THE FAR NORTH CENTRAL...HOLDING OFF ON
A HIGH WIND WARNING AT THIS TIME.
OTHERWISE NO SIGNIFICANT CHANGES TO THE FORECAST.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 330 PM CDT MON MAY 20 2013
THE HIGHLIGHT OF THE SHORT TERM CONTINUES TO BE THE IMPACTS OF THE
ONGOING RAINFALL EVENT.
OVERALL THE GUIDANCE IS IN GOOD AGREEMENT...AND FOLLOWED A BLEND
OF THE 12 UTC GFS/GEM/ECMWF AND 15 UTC SREF FOR ALL FIELDS.
CURRENTLY THE STACKED LOW ACROSS FAR NORTHEAST SOUTH DAKOTA IS
EXPECTED TO SLOWLY PROPAGATE INTO CENTRAL MINNESOTA THROUGH
TUESDAY. WRAP AROUND RAINFALL IS EXPECTED TO SLOWLY DOWNTREND
THROUGH THE NIGHT AND INTO TUESDAY WITH AN ADDITIONAL ONE HALF TO
THREE QUARTERS OF AN INCH OF RAINFALL EXPECTED. SEE THE HYDROLOGY
DISCUSSION BELOW FOR DETAILS.
FOR THIS EVENING AND TONIGHT...DID MAINTAIN THE WIND ADVISORY FOR
THE WEST AND NORTH. THE WIND FIELD ACROSS THESE AREAS CONTINUES TO
STRENGTHEN WITH 40-45 KTS AT THE TOP OF A SHALLOW MIXED LAYER AS
DEPICTED BY THE 12 UTC NAM/GFS BUFR SOUNDINGS. THE STRONGEST WINDS
ARE EXPECTED ACROSS THE TURTLE MOUNTAINS WHERE GUSTS TO NEAR 50
MPH ARE POSSIBLE THROUGH EARLY EVENING.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 330 PM CDT MON MAY 20 2013
THE MAIN FORECAST ISSUE THROUGH THE LONG TERM PERIOD WILL BE ONGOING
RIVER AND OVERLAND FLOODING CONCERNS. SEE HYDROLOGY DISCUSSION BELOW
FOR DETAILS. THEN ATTENTION TURNS TO THE UPCOMING WEEKEND AND THE
POSSIBILITY FOR SCATTERED THUNDERSTORMS AND POSSIBLE SEVERE WEATHER.
THERE IS FAIRLY GOOD MODEL AGREEMENT REGARDING THE POSITION AND
MOVEMENT OF THE CLOSED UPPER LEVEL LOW...ASSOCIATED WITH THE
PERSISTENT RAINS FOR THE PAST SEVERAL DAYS. THE UPPER LOW IS
FORECAST TO BE OVER THE SD/MN BORDER TUESDAY EVENING...THEN BECOME
MORE OF AN OPEN WAVE BY WEDNESDAY EVENING OVER IA/WI/IL AND THE
WESTERN GREAT LAKES. THIS SCENARIO WILL MEAN THE VERY HIGH/LIKELY
CHANCES OF RAIN TUESDAY NIGHT IN THE JAMES RIVER BASIN WILL LESSEN
TO SCATTERED IN NATURE BY WEDNESDAY. THE REST OF WESTERN AND CENTRAL
NORTH DAKOTA SHOULD SEE A DECREASE IN COVERAGE OF THE SHOWERS
TUESDAY NIGHT. SLIGHT CHANCES TO SCATTERED SHOWERS WEDNESDAY AS THE
SYSTEM MOVES EAST OF THE REGION.
BY WEDNESDAY EVENING AS THE UPPER LEVEL LOW/TROUGH MOVES EAST...A
WEAK UPPER LEVEL RIDGE WILL BUILD ACROSS THE NORTHERN PLAINS. THIS
WILL BE SHORT-LIVED AS ANOTHER LARGE UPPER LEVEL LOW/TROUGH SYSTEM
MOVES INTO THE PACIFIC NORTHWEST AND ROCKIES. THUS NO PRECIPITATION
MENTION FOR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT.
FRIDAY THROUGH THE WEEKEND AND INTO MONDAY...THE UPPER LEVEL LOW
OVER THE ROCKIES IS FORECAST TO REMAIN IN PLACE...SETTING UP A
PROLONGED PERIOD OF SOUTHWESTERLY FLOW ALOFT FOR NORTH DAKOTA. THIS
WILL MEAN PERIODIC UPPER LEVEL SHORTWAVE ENERGY MOVING NORTHEASTWARD
THROUGH THE MEAN FLOW. AT THE SURFACE...THIS WILL RESULT IN BROAD
LOW PRESSURE ACROSS THE PLAINS...ALLOWING PLENTY OF GULF OF MEXICO
MOISTURE TO STREAM NORTHWARD. A PROLONGED LOW LEVEL JET AT H925-H850
WILL HELP TRANSPORT MOISTURE AND ENERGY NORTHWARD UP THE PLAINS.
THUS PERIODIC EPISODES OF SCATTERED THUNDERSTORMS WILL BE IN THE
FORECAST FRIDAY THROUGH THE MEMORIAL DAY WEEKEND.
WHILE TOO FAR OUT FOR MUCH CERTAINTY IN NARROWING DOWN SPECIFIC
AREAS OF CONCERN...SURFACE DEWPOINTS RISING INTO THE 50S BY FRIDAY
AND FORECAST CAPE DEVELOPING FROM THE SOUTHERN...CENTRAL...TO THE
NORTHERN PLAINS WOULD SUGGEST SOME SEVERE THUNDERSTORM ACTIVITY OVER
A BROAD AREA OF THE PLAINS FRIDAY AND SATURDAY. STAY TUNED FOR LATER
FORECASTS AND STORM PREDICTION CENTER OUTLOOKS FOR THE POTENTIAL FOR
SEVERE THUNDERSTORMS THIS COMING WEEKEND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 109 AM CDT TUE MAY 21 2013
LIGHT TO SOMETIMES MODERATE RAINFALL WILL CONTINUE OVER ALL
TERMINALS THROUGH THE TAF PERIOD WITH MVFR/IFR CIGS/VSBYS. WIND
GUSTS OF 30-40 KTS ARE POSSIBLE AT EASTERN TAF
SITES...KJMS...THROUGH THIS TUESDAY MORNING.
&&
.HYDROLOGY...
ISSUED AT 330 PM CDT MON MAY 20 2013
DID MAINTAIN THE FLOOD WATCH FOR ALL OF WESTERN AND CENTRAL NORTH
DAKOTA THROUGH TONIGHT. CALLS TO AREA EMERGENCY MANAGERS REVEAL THAT
FOR THE MOST PART...COUNTY AND TOWNSHIP ROAD IMPACTS ARE LIMITED.
HOWEVER...AS SOILS CONTINUE TO SATURATE...OVERLAND FLOOD CONCERNS
COULD INCREASE THROUGH THE NIGHT. FURTHERMORE...REPORTS HAVE BEEN
COMING IN OF WATER ENTERING BASEMENTS ACROSS THE AREA WITH THE
SATURATED GROUND. ADDITIONAL RIVER AND STREAM RISES ARE EXPECTED
OVER THE COMING DAYS. FOR THE MOST PART WITHIN BANK RISES ARE
ANTICIPATED. HOWEVER...THE SOURIS RIVER AT TOWNER IS EXPECTED TO
RISE ABOVE FLOOD STAGE AGAIN...THE PIPESTEM CREEK NEAR PINGREE IS
FORECAST TO RISE ABOVE MINOR FLOOD STAGE TOMORROW AFTERNOON WITH
THE WILLOW CREEK NEAR WILLOW CITY POSSIBLY APPROACHING FLOOD STAGE
BY WEDNESDAY EVENING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH UNTIL 7 AM CDT /6 AM MDT/ THIS MORNING FOR
NDZ001>005-009>013-017>023-025-031>037-040>048-050-051.
WIND ADVISORY UNTIL 7 AM CDT THIS MORNING FOR NDZ004-005-012-013-
022-023-025-036-037.
&&
$$
UPDATE...NH
SHORT TERM...AYD
LONG TERM...JV
AVIATION...NH
HYDROLOGY...AYD
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
137 PM EDT TUE MAY 21 2013
.SYNOPSIS...
THE AIR MASS WILL BECOME INCREASINGLY MOIST AND UNSTABLE THROUGH MID
WEEK AS AN AREA OF LOW PRESSURE OVER THE UPPER MIDWEST SLOWLY
APPROACHES THE REGION. THIS LOW PRESSURE SYSTEM WILL TRACK THROUGH
THE EASTERN GREAT LAKES LATE WEDNESDAY AND PUSH A COLD FRONT SOUTH
ACROSS THE AREA ON THURSDAY. HIGH PRESSURE WILL RETURN FOR THE END
OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AXIS OF WEAK LIFT MOVING EAST ACROSS THE CENTRAL PART OF THE CWA
ATTM. NEAR TERM MODELS GENERATE CONVECTION FROM THIS FEATURE OVER
THE SNOWBELT AREA BY 17Z WITH THE HRRR BY FAR THE MOST GENEROUS.
SINCE THE HRRR USUALLY TENDS TO BE OVERDONE WITH THIS TYPE OF
CONVECTION WILL ONLY RAMP UP A SLIGHT OR SMALL CHANCE POP FOR THIS.
OTHERWISE WILL GRADUALLY RAMP UP CHANCE POPS FOR SCT CONVECTION TO
DEVELOP DURING THE AFTERNOON BUT NOT SEEING THE COVERAGE AS
WIDESPREAD AS PREVIOUS THINKING. WILL INCREASE TEMPS OVER THE WEST
AND CENTRAL A LITTLE AS MID CLOUDS WILL BE ABSENT OVER THESE AREAS
FOR THE PEAK HEATING HOURS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
SOME LEFT OVER SHOWERS AND THUNDERSTORMS IN THE EVENING AND THEN
THE AREA SHOULD BE IN A LULL FOR MUCH OF TONIGHT AND THEN WAITING
FOR THE NEXT SYSTEM TO AFFECT THE REGION FOR WEDNESDAY INTO
WEDNESDAY NIGHT. THIS WILL BE THE DAY WITH THE BEST CHANCE OF
SEVERE WEATHER. THE COLD FRONT MOVES THROUGH ON THURSDAY. FRIDAY
SHOULD BE DRY AND COOL WITH HIGH PRESSURE BUILDING IN.
THE TEMPERATURE FORECAST IS TOUGH...ESPECIALLY THE HIGHS. IF THE
SHOWERS AND THUNDERSTORMS DEVELOP EARLY OR IF WE HAVE A LOT OF
DEBRIS CLOUDS THAT WILL AFFECT THE HIGHS. USED A BLEND OF GUIDANCE.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
MODELS IN DISAGREEMENT IN THE EXTENDED. GFS CONTINUES WITH CANADIAN
HIGH PRESSURE OVER THE ENTIRE AREA THROUGH THE WEEKEND. THE ECMWF
ON THE OTHER HAND HAS ANOTHER FRONT PUSH THROUGH THE AREA ON
SATURDAY...AND IS THUS WETTER AND COOLER. SINCE THE GFS HAS BEEN
CONSISTENT WITH THIS SOLUTION IGNORED THE ECMWF AND WENT WITH THE
GFS FORECAST. THIS WILL RESULT IN DRY NORTHERLY FLOW FOR THE AREA
FOR THE ENTIRE WEEKEND AND SLIGHTLY BELOW NORMAL TEMPERATURES.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
MORE UNCERTAINTY TODAY AS FAR AS PRECIP CHANCES GO. MUCH DRIER AIR
HAS WORKED INTO THE WESTERN HALF OF THE AREA WITH DEWPOINTS DOWN
INTO THE 50S. HAVING A TOUGH TIME EVEN GETTING CU THAT AREA AND
PRECIP CHANCES THROUGH THE EVENING HOURS APPEAR MINIMAL. MODELS
SHOWING AN UPPER TROUGH MOVING INTO LOWER MI LATER TODAY WHICH
COULD KICK OFF SOME TSRA ACTIVITY. THIS ACTIVITY COULD COME CLOSE
TO KTOL. FURTHER EAST THE AIRMASS REMAINS MORE UNSTABLE. GUIDANCE
SUGGESTS SOME POP UP STORMS ARE POSSIBLE LATER THIS AFTERNOON.
WILL USE A COMBINATION OF TEMPOS AND VCTS FOR A FEW HOURS THIS
EVENING. THE OVERNIGHT HOURS SHOULD BE DRY WITH JUST PATCHY MVFR
FOG TOWARD DAYBREAK. WEDNESDAY SHOULD BE A MORE ACTIVE DAY AND
WILL BRING MORE PRECIP INTO THE WEST TOWARD MIDDAY. GUSTY S TO SW
FLOW WILL DIMINISH THIS EVENING.
.OUTLOOK...NON VFR PROBABLE IN SHOWERS/THUNDERSTORMS WEDNESDAY AND
THURSDAY.
&&
.MARINE...
SOUTH TO SOUTHWEST FLOW WILL CONTINUE ON THE LAKE THROUGH MID WEEK.
MODELS HAVE BEEN CONSISTENT WITH THE NEXT SYSTEM MOVING ACROSS THE
LAKE ON THURSDAY. SMALL CRAFT ADVISORY WILL BE NEEDED AS NORTH TO
NORTHWEST WINDS INCREASE TO 15 TO 25 KNOTS IN COLDER AIR. THE 850MB
TEMPS DIP TO 2C BY THE WEEKEND. STRONG TO SEVERE STORMS APPEAR
POSSIBLE BOTH TODAY AND WEDNESDAY. BOATERS WILL NEED TO REMAIN
ALERT.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KIELTYKA
SHORT TERM...KIELTYKA
LONG TERM...DJB
AVIATION...KUBINA
MARINE...DJB
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
922 AM EDT TUE MAY 21 2013
.SYNOPSIS...
THE AIR MASS WILL BECOME INCREASINGLY MOIST AND UNSTABLE THROUGH MID
WEEK AS AN AREA OF LOW PRESSURE OVER THE UPPER MIDWEST SLOWLY
APPROACHES THE REGION. THIS LOW PRESSURE SYSTEM WILL TRACK THROUGH
THE EASTERN GREAT LAKES LATE WEDNESDAY AND PUSH A COLD FRONT SOUTH
ACROSS THE AREA ON THURSDAY. HIGH PRESSURE WILL RETURN FOR THE END
OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AXIS OF WEAK LIFT MOVING EAST ACROSS THE CENTRAL PART OF THE CWA
ATTM. NEAR TERM MODELS GENERATE CONVECTION FROM THIS FEATURE OVER
THE SNOWBELT AREA BY 17Z WITH THE HRRR BY FAR THE MOST GENEROUS.
SINCE THE HRRR USUALLY TENDS TO BE OVERDONE WITH THIS TYPE OF
CONVECTION WILL ONLY RAMP UP A SLIGHT OR SMALL CHANCE POP FOR THIS.
OTHERWISE WILL GRADUALLY RAMP UP CHANCE POPS FOR SCT CONVECTION TO
DEVELOP DURING THE AFTERNOON BUT NOT SEEING THE COVERAGE AS
WIDESPREAD AS PREVIOUS THINKING. WILL INCREASE TEMPS OVER THE WEST
AND CENTRAL A LITTLE AS MID CLOUDS WILL BE ABSENT OVER THESE AREAS
FOR THE PEAK HEATING HOURS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
SOME LEFT OVER SHOWERS AND THUNDERSTORMS IN THE EVENING AND THEN
THE AREA SHOULD BE IN A LULL FOR MUCH OF TONIGHT AND THEN WAITING
FOR THE NEXT SYSTEM TO AFFECT THE REGION FOR WEDNESDAY INTO
WEDNESDAY NIGHT. THIS WILL BE THE DAY WITH THE BEST CHANCE OF
SEVERE WEATHER. THE COLD FRONT MOVES THROUGH ON THURSDAY. FRIDAY
SHOULD BE DRY AND COOL WITH HIGH PRESSURE BUILDING IN.
THE TEMPERATURE FORECAST IS TOUGH...ESPECIALLY THE HIGHS. IF THE
SHOWERS AND THUNDERSTORMS DEVELOP EARLY OR IF WE HAVE A LOT OF
DEBRIS CLOUDS THAT WILL AFFECT THE HIGHS. USED A BLEND OF GUIDANCE.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
MODELS IN DISAGREEMENT IN THE EXTENDED. GFS CONTINUES WITH CANADIAN
HIGH PRESSURE OVER THE ENTIRE AREA THROUGH THE WEEKEND. THE ECMWF
ON THE OTHER HAND HAS ANOTHER FRONT PUSH THROUGH THE AREA ON
SATURDAY...AND IS THUS WETTER AND COOLER. SINCE THE GFS HAS BEEN
CONSISTENT WITH THIS SOLUTION IGNORED THE ECMWF AND WENT WITH THE
GFS FORECAST. THIS WILL RESULT IN DRY NORTHERLY FLOW FOR THE AREA
FOR THE ENTIRE WEEKEND AND SLIGHTLY BELOW NORMAL TEMPERATURES.
&&
.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
PATCHY MVFR BR WILL END BY MID MORNING. MODELS CONTINUE TO
INDICATE SCATTERED TSRA FOR THIS AFTERNOON AS CAPES REACH 1000-1500
J/KG OVER AREA THIS AFTERNOON. CONFIDENCE IS LOW AS TO PRECISELY
WHERE AND WHEN THE TSRA WILL DEVELOP. MUCH BETTER CHANCE OF
ORGANIZED CONVECTION WEDNESDAY AFTERNOON.
.OUTLOOK...NON VFR PROBABLE IN SHOWERS/THUNDERSTORMS WEDNESDAY AND
THURSDAY.
&&
.MARINE...
SOUTH TO SOUTHWEST FLOW WILL CONTINUE ON THE LAKE THROUGH MID WEEK.
MODELS HAVE BEEN CONSISTENT WITH THE NEXT SYSTEM MOVING ACROSS THE
LAKE ON THURSDAY. SMALL CRAFT ADVISORY WILL BE NEEDED AS NORTH TO
NORTHWEST WINDS INCREASE TO 15 TO 25 KNOTS IN COLDER AIR. THE 850MB
TEMPS DIP TO 2C BY THE WEEKEND. STRONG TO SEVERE STORMS APPEAR
POSSIBLE BOTH TODAY AND WEDNESDAY. BOATERS WILL NEED TO REMAIN
ALERT.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KIELTYKA/ADAMS
SHORT TERM...KIELTYKA
LONG TERM...DJB
AVIATION...DJB
MARINE...DJB
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
912 AM EDT TUE MAY 21 2013
.SYNOPSIS...
THE AIR MASS WILL BECOME INCREASINGLY MOIST AND UNSTABLE THROUGH MID
WEEK AS AN AREA OF LOW PRESSURE OVER THE UPPER MIDWEST SLOWLY
APPROACHES THE REGION. THIS LOW PRESSURE SYSTEM WILL TRACK THROUGH
THE EASTERN GREAT LAKES LATE WEDNESDAY AND PUSH A COLD FRONT SOUTH
ACROSS THE AREA ON THURSDAY. HIGH PRESSURE WILL RETURN FOR THE END
OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
PREVIOUS DISCUSSION...
AXIS OF WEAK LIFT MOVING EAST ACROSS THE CENTRAL PART OF THE CWA
ATTM. NEAR TERM MODELS GENERATE CONVECTION FROM THIS FEATURE OVER
THE SNOWBELT AREA BY 17Z WITH THE HRRR BY FAR THE MOST GENEROUS.
SINCE THE HRRR USUALLY TENDS TO BE OVERDONE WITH THIS TYPE OF
CONVECTION WILL ONLY RAMP UP A SLIGHT OR SMALL CHANCE POP FOR THIS.
OTHERWISE WILL GRADUALLY RAMP UP CHANCE POPS FOR SCT CONVECTION TO
DEVELOP DURING THE AFTERNOON BUT NOT SEEING THE COVERAGE AS
WIDESPREAD AS PREVIOUS THINKING. WILL INCREASE TEMPS OVER THE WEST
AND CENTRAL A LITTLE AS MID CLOUDS WILL BE ABSENT OVER THESE AREAS
FOR THE PEAK HEATING HOURS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
SOME LEFT OVER SHOWERS AND THUNDERSTORMS IN THE EVENING AND THEN
THE AREA SHOULD BE IN A LULL FOR MUCH OF TONIGHT AND THEN WAITING
FOR THE NEXT SYSTEM TO AFFECT THE REGION FOR WEDNESDAY INTO
WEDNESDAY NIGHT. THIS WILL BE THE DAY WITH THE BEST CHANCE OF
SEVERE WEATHER. THE COLD FRONT MOVES THROUGH ON THURSDAY. FRIDAY
SHOULD BE DRY AND COOL WITH HIGH PRESSURE BUILDING IN.
THE TEMPERATURE FORECAST IS TOUGH...ESPECIALLY THE HIGHS. IF THE
SHOWERS AND THUNDERSTORMS DEVELOP EARLY OR IF WE HAVE A LOT OF
DEBRIS CLOUDS THAT WILL AFFECT THE HIGHS. USED A BLEND OF GUIDANCE.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
MODELS IN DISAGREEMENT IN THE EXTENDED. GFS CONTINUES WITH CANADIAN
HIGH PRESSURE OVER THE ENTIRE AREA THROUGH THE WEEKEND. THE ECMWF
ON THE OTHER HAND HAS ANOTHER FRONT PUSH THROUGH THE AREA ON
SATURDAY...AND IS THUS WETTER AND COOLER. SINCE THE GFS HAS BEEN
CONSISTENT WITH THIS SOLUTION IGNORED THE ECMWF AND WENT WITH THE
GFS FORECAST. THIS WILL RESULT IN DRY NORTHERLY FLOW FOR THE AREA
FOR THE ENTIRE WEEKEND AND SLIGHTLY BELOW NORMAL TEMPERATURES.
&&
.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
PATCHY MVFR BR WILL END BY MID MORNING. MODELS CONTINUE TO
INDICATE SCATTERED TSRA FOR THIS AFTERNOON AS CAPES REACH 1000-1500
J/KG OVER AREA THIS AFTERNOON. CONFIDENCE IS LOW AS TO PRECISELY
WHERE AND WHEN THE TSRA WILL DEVELOP. MUCH BETTER CHANCE OF
ORGANIZED CONVECTION WEDNESDAY AFTERNOON.
.OUTLOOK...NON VFR PROBABLE IN SHOWERS/THUNDERSTORMS WEDNESDAY AND
THURSDAY.
&&
.MARINE...
SOUTH TO SOUTHWEST FLOW WILL CONTINUE ON THE LAKE THROUGH MID WEEK.
MODELS HAVE BEEN CONSISTENT WITH THE NEXT SYSTEM MOVING ACROSS THE
LAKE ON THURSDAY. SMALL CRAFT ADVISORY WILL BE NEEDED AS NORTH TO
NORTHWEST WINDS INCREASE TO 15 TO 25 KNOTS IN COLDER AIR. THE 850MB
TEMPS DIP TO 2C BY THE WEEKEND. STRONG TO SEVERE STORMS APPEAR
POSSIBLE BOTH TODAY AND WEDNESDAY. BOATERS WILL NEED TO REMAIN
ALERT.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KIELTYKA/ADAMS
SHORT TERM...KIELTYKA
LONG TERM...DJB
AVIATION...DJB
MARINE...DJB
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
605 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A WARM AND HUMID AIR MASS WILL REMAIN IN PLACE THROUGH WEDNESDAY.
OCCASIONAL PERIODS OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE.
A COLD FRONT WILL MOVE THROUGH THE REGION ON THURSDAY...BEFORE
COOLER AIR SETTLES IN ON FRIDAY AND INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SIGNIFICANT CHANGES WERE MADE TO THE FORECAST IN THE NEAR
TERM...AS A RAGGED MCS CURRENTLY MOVING ACROSS CENTRAL INDIANA
WILL CONTINUE ITS WAY INTO THE ILN FORECAST AREA THIS MORNING. ALL
MODELS...INCLUDING CONVECTIVE ALLOWING MODELS...FORECAST A GRADUAL
WEAKENING OF THIS FEATURE AS IT CONTINUES MOVING TO THE EAST.
MESOSCALE ANALYSIS SHOWS THE NEAR-SURFACE ENVIRONMENT IS VERY
UNFAVORABLE FOR THIS LINE TO MAINTAIN ITS STRENGTH...WITH MUCH MORE
INHIBITION (UP TO 100-150 J/KG) THAN WHEN IT WAS IN CENTRAL
INDIANA...AND A NEAR-SURFACE INVERSION OVER THE ILN CWA.
HOWEVER...AS SOME ELEVATED INSTABILITY WILL REMAIN IN PLACE...THE
CONVECTION IS NOT EXPECTED TO DISSIPATE ENTIRELY. THERE IS SOME
SHEAR IN PLACE IN THE LOW LEVELS (30-40 KNOTS FROM 0-1KM...WHICH
IS SOMEWHAT IMPRESSIVE). WINDS AHEAD OF THE LINE ARE GENERALLY OUT
OF THE SOUTH...AND WINDS AT 925MB ARE OUT OF THE SOUTHWEST AND UP
TO 40 KNOTS. THIS HAS LED TO SOME ISOLATED POCKETS OF STRONGER
WINDS ON THE LINE. HOWEVER...IT IS UNLIKELY THAT THIS SHEAR WILL
BE REALIZED OVER THE ILN CWA...GIVEN THE MORE HOSTILE
THERMODYNAMIC ENVIRONMENT. THUS...THE SEVERE THREAT THIS MORNING
APPEARS LOW...THOUGH SOME GUSTY WINDS WILL CERTAINLY BE POSSIBLE.
THE FOCUS FOR THE REST OF THE DAY IS ON THE POTENTIAL FOR
ADDITIONAL STORMS THIS AFTERNOON AND EVENING. THE FIRST CHALLENGE
IS A NEAR COMPLETE LACK OF PROPER MODELING OF THE CURRENT
CONVECTIVE COMPLEX. THE HRRR APPEARS TO BE THE CLOSEST...THOUGH IT
IS A COUPLE HOURS BEHIND. THE NAM SOLUTION...WHICH
FEATURES PRECIPITATION MOVING THROUGH INDIANA AND OHIO DURING THE
LATE MORNING AND EARLY AFTERNOON (3-6 HOURS BEHIND THE CURRENT
ACTIVITY) DOES NOT APPEAR RELIABLE. WITH A LACK OF SYNOPTIC SCALE
FORCING...MESOSCALE FEATURES WILL PLAY A BIG ROLE IN THE POTENTIAL
FOR STORMS...AND THESE FEATURES WILL BE HIGHLY DEPENDENT ON THE
EVOLUTION OF THE MORNING CONVECTION (PLACEMENT OF OUTFLOW / CLOUD
DEBRIS LIMITING DESTABILIZATION).
IN GENERAL...THE PATTERN WILL FAVOR THE GREATEST INSTABILITY IN
THE SOUTHERN PORTIONS OF THE FORECAST AREA...PERHAPS AS HIGH AS
1500-2500 J/KG OF MIXED LAYER CAPE. STILL A WAYS REMOVED FROM THE
BRUNT OF THE JET...THE ILN CWA WILL NOT GET INTO A GREAT DEAL OF
WIND SHEAR TODAY...PERHAPS UP TO 30 KNOTS IN THE DEEP LAYER AND
NOT MUCH AT ALL IN THE LOWEST LEVELS. THE INSTABILITY SHOULD BE
SURFACE BASED AND UNCAPPED (RAP13 FORECASTS SHOW A 3 DEG C DROP IN
700MB TEMPS BY AFTERNOON)...AND THIS APPEARS TO BE ENOUGH TO
SUPPORT SOME SEVERE THREAT. THE LACK OF STRONGER SHEAR AND
ORGANIZED FORCING SHOULD BE A LIMITING FACTOR. IT IS POSSIBLE THAT
THE MORNING CONVECTION MAY END UP LEAVING A BOUNDARY THAT COULD
ACT AS THE FOCUS FOR CONVECTIVE DEVELOPMENT IN THE AFTERNOON
HOURS.
THE TEMPERATURE FORECAST IS ALSO SIGNIFICANTLY DEPENDENT ON THE
ABOVE FACTORS...THOUGH THE AIR MASS IS CERTAINLY CAPABLE OF
SUPPORTING TEMPS AS HIGH AS THE MID TO UPPER 80S. RAW MODEL TEMPS
ARE IN WIDE VARIANCE FROM MODEL TO MODEL...WITH INTENSE HEATING
BEFORE PRECIPITATION FORCES DROPS IN THE SURFACE TEMP FIELDS (AND
AT DIFFERENT TIMES AND PLACES). WHILE A GENERAL CONSENSUS WAS
USED...IN THE INTEREST OF BEING A BIT CONSERVATIVE GIVEN THE
UNCERTAIN CONVECTIVE FORECAST...THE MAX TEMPS WERE KNOCKED DOWN A
COUPLE DEGREES FROM THERE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
CONVECTION WILL LIKELY BE ONGOING FOR AT LEAST PART OF THE
FORECAST AREA DURING THE TUESDAY EVENING HOURS...WITH A DIURNAL
MIN LEADING TO MORE TRANQUIL CONDITIONS OVERNIGHT. HOWEVER...BY
WEDNESDAY MORNING...THIS MAY BEGIN TO CHANGE AGAIN. A SHORTWAVE
MOVING OUT OF THE SOUTHERN PLAINS WILL EVENTUALLY MAKE ITS WAY
JUST EAST OF THE ILN CWA BY MORNING...WITH MODEL AGREEMENT ON AN
ASSOCIATED CONVECTIVE COMPLEX SPREADING INTO INDIANA BY THEN.
MEANWHILE...SURFACE LOW PRESSURE WILL STRENGTHEN AS IT MOVES
THROUGH ILLINOIS AND INTO MICHIGAN...WITH GENERAL SURFACE
TROUGHING AND HEIGHT FALLS ALOFT SPREADING INTO THE ILN CWA. THIS
IS A FAVORABLE ENVIRONMENT FOR LIFT...AND SHOULD SUPPORT A LIKELY POP
FORECAST THROUGH MOST OF THE DAY WEDNESDAY. ALTHOUGH GENERALLY
UNIDIRECTIONAL...THE INCREASING PRESSURE GRADIENT AND
JUXTAPOSITION WITH THE RIGHT ENTRANCE REGION OF THE UPPER JET WILL
ALSO SUPPORT AN INCREASED BIT OF SHEAR AND FORCING (RESPECTIVELY).
THE LIMITING FACTOR FOR SEVERE POTENTIAL WILL BE
INSTABILITY...WHICH DOES NOT APPEAR TO BE PARTICULARLY STRONG (AND
THIS IS NOT SURPRISING GIVEN THE LACK OF EXPECTED SURFACE
HEATING). TEMPS ALOFT WILL CONTINUE TO DROP...WHICH SHOULD HELP
GENERATE 500-1000 J/KG IF SOME SUN CAN BE REALIZED. AN ALTERNATE
POSSIBILITY WOULD KEEP PRECIPITATION OVER THE CWA THROUGH THE
MORNING AND EARLY AFTERNOON...ESSENTIALLY LIMITING DESTABILIZATION
TO NEAR-ZERO. THE SOUNDINGS LOOK RATHER MOIST...LEADING TO THIN
CAPE AND LOW LCLS.
IT IS AN INTERESTING CONTRAST IN SEVERE POTENTIAL FROM TODAY
(TUESDAY)...WITH DIFFERENT ELEMENTS OF THE MESOSCALE ANALYSIS
APPEARING FAVORABLE ON EITHER DAY.
THE LARGE NORTHERN PLAINS UPPER LOW WILL FINALLY BE ON THE MOVE BY
LATE WEDNESDAY...CROSSING THE ILN CWA ON THURSDAY. THIS WILL BRING
ANOTHER HIGH CHANCE OF POPS ON THURSDAY...MAINLY IN THE NORTH AND
GENERALLY WITH DIURNAL TIMING. BEHIND THE AXIS OF THIS
TROUGH...RAPID DRYING IS EXPECTED.
TEMPERATURES WILL BEGIN A DOWNWARD TREND AFTER THE POORLY-DEFINED
COLD FRONT (ASSOCIATED WITH THE WEDNESDAY SURFACE LOW) MOVES
THROUGH THE REGION. A STRONGER CHANGE IN NEAR-SURFACE AIR MASS IS
EXPECTED BEHIND THE TROUGH ON THURSDAY NIGHT...WITH NORTHERLY
WINDS ADVECTING COLDER AND DRIER AIR INTO THE REGION.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
SURFACE HIGH PRESSURE WILL BUILD DOWN FROM THE NORTH AND INTO OUR
AREA FRIDAY INTO SATURDAY...KEEPING A SEASONABLY COOL AIRMASS IN
PLACE THROUGH THE START OF THE WEEKEND. HIGHS ON FRIDAY WILL BE IN
THE MID TO UPPER 60S AND WITH THE SURFACE HIGH OVERHEAD...LOWS
SATURDAY MORNING WILL DIP INTO THE LOW TO MID 40S. THE SURFACE
HIGH WILL BEGIN TO SHIFT OFF TO THE EAST THROUGH THE REMAINDER OF
THE WEEKEND AS MID LEVEL RIDGING BEGINS TO ESTABLISH ITSELF ALOFT.
THIS WILL RESULT IN A GRADUAL RETURN TO WARMER TEMPERATURES
THROUGH THE REST OF THE HOLIDAY WEEKEND. MODELS ARE STILL TRYING
TO SUGGEST THE POSSIBILITY OF SOME ENERGY DROPPING DOWN FROM THE
NORTHWEST LATE IN THE WEEKEND. HOWEVER...TIMING AND PLACEMENT ARE
HIGHLY VARIABLE SO WILL MAINTAIN A DRY FORECAST AT THIS POINT.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
LARGE SCALE UPPER LEVEL LOW CENTERED OVER THE NORTHERN PLAINS WILL
MAKE LITTLE EASTWARD PROGRESSION OVER THE NEXT 24 HOURS. REGION
WILL BE LOCATED IN A WARM...MOIST SOUTH/SOUTHWEST FLOW AT THE SFC
AND ALOFT.
FIRST ITEM OF CONCERN WILL BE A CLUSTER OF CONVECTION ONGOING
ACROSS SOUTHWEST INDIANA AND WESTERN KENTUCKY. IT IS UNCLEAR HOW
MUCH OF THIS WILL HOLD IN TACT AS IT PUSHES TOWARD THE KCVG AND KLUK
TERMINALS BETWEEN 12Z AND 15Z SO HAVE INCLUDED A VCTS/CB AT
THESES TAF SITES BUT WILL MAKE A LAST MINUTE DECISION BASED ON
RADAR TRENDS IF A TEMPO GROUP IS NEEDED. AS OUR AREA IS IN A MOIST
SOUTHWEST FLOW ALOFT...ADDITIONAL SHOWER AND THUNDERSTORM ACTIVITY
WILL BE DEPENDENT ON ANY LINGER OUTFLOW BOUNDARIES FROM EARLY
MORNING CONVECTION...EMBEDDED DISTURBANCES ALOFT AND HOW MUCH
SUNSHINE THE AREA RECEIVES FOR INSTABILITY. MODELS ARE NOT
OFFERING MUCH IN TERMS OF SPECIFIC TIMING EXCEPT TO FAVOR THE
DIURNAL CYCLE AND HAVE INCLUDE ONLY VCTS/CB AT THE TAF SITES AS
SUCH. THIS MAY SIGNIFICANTLY CHANGE DEPENDING ON PREVIOUS
MENTIONED FACTORS IF THUNDERSTORMS GET GOING ON ANY MESOSCALE
FEATURE.
FOR TONIGHT...MODELS SUGGEST A LULL IN THE CONVECTIVE ACTIVITY IN
TERMS OF COVERAGE. COVERAGE SHOULD INCREASE ON WEDNESDAY AS A MORE
SIGNIFICANT DISTURBANCE ROTATES FROM SOUTHWEST TO NORTHEAST ACROSS
THE REGION OUT AHEAD OF A COLD FRONT. SHOWERS AND THUNDERSTORMS
LOOK LIKE A GOOD BET FOR WEDNESDAY INTO WEDNESDAY EVENING.
OUTLOOK...THUNDERSTORMS LIKELY WEDNESDAY INTO WEDNESDAY EVENING.
MVFR CONDITIONS POSSIBLE THURSDAY INTO THURSDAY NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HATZOS
NEAR TERM...HATZOS
SHORT TERM...HATZOS
LONG TERM...JGL
AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
428 AM EDT TUE MAY 21 2013
.SYNOPSIS...
A WARM AND HUMID AIR MASS WILL REMAIN IN PLACE THROUGH WEDNESDAY.
OCCASIONAL PERIODS OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE.
A COLD FRONT WILL MOVE THROUGH THE REGION ON THURSDAY...BEFORE
COOLER AIR SETTLES IN ON FRIDAY AND INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SIGNIFICANT CHANGES WERE MADE TO THE FORECAST IN THE NEAR
TERM...AS A RAGGED MCS CURRENTLY MOVING ACROSS CENTRAL INDIANA
WILL CONTINUE ITS WAY INTO THE ILN FORECAST AREA THIS MORNING. ALL
MODELS...INCLUDING CONVECTIVE ALLOWING MODELS...FORECAST A GRADUAL
WEAKENING OF THIS FEATURE AS IT CONTINUES MOVING TO THE EAST.
MESOSCALE ANALYSIS SHOWS THE NEAR-SURFACE ENVIRONMENT IS VERY
UNFAVORABLE FOR THIS LINE TO MAINTAIN ITS STRENGTH...WITH MUCH MORE
INHIBITION (UP TO 100-150 J/KG) THAN WHEN IT WAS IN CENTRAL
INDIANA...AND A NEAR-SURFACE INVERSION OVER THE ILN CWA.
HOWEVER...AS SOME ELEVATED INSTABILITY WILL REMAIN IN PLACE...THE
CONVECTION IS NOT EXPECTED TO DISSIPATE ENTIRELY. THERE IS SOME
SHEAR IN PLACE IN THE LOW LEVELS (30-40 KNOTS FROM 0-1KM...WHICH
IS SOMEWHAT IMPRESSIVE). WINDS AHEAD OF THE LINE ARE GENERALLY OUT
OF THE SOUTH...AND WINDS AT 925MB ARE OUT OF THE SOUTHWEST AND UP
TO 40 KNOTS. THIS HAS LED TO SOME ISOLATED POCKETS OF STRONGER
WINDS ON THE LINE. HOWEVER...IT IS UNLIKELY THAT THIS SHEAR WILL
BE REALIZED OVER THE ILN CWA...GIVEN THE MORE HOSTILE
THERMODYNAMIC ENVIRONMENT. THUS...THE SEVERE THREAT THIS MORNING
APPEARS LOW...THOUGH SOME GUSTY WINDS WILL CERTAINLY BE POSSIBLE.
THE FOCUS FOR THE REST OF THE DAY IS ON THE POTENTIAL FOR
ADDITIONAL STORMS THIS AFTERNOON AND EVENING. THE FIRST CHALLENGE
IS A NEAR COMPLETE LACK OF PROPER MODELING OF THE CURRENT
CONVECTIVE COMPLEX. THE HRRR APPEARS TO BE THE CLOSEST...THOUGH IT
IS A COUPLE HOURS BEHIND. THE NAM SOLUTION...WHICH
FEATURES PRECIPITATION MOVING THROUGH INDIANA AND OHIO DURING THE
LATE MORNING AND EARLY AFTERNOON (3-6 HOURS BEHIND THE CURRENT
ACTIVITY) DOES NOT APPEAR RELIABLE. WITH A LACK OF SYNOPTIC SCALE
FORCING...MESOSCALE FEATURES WILL PLAY A BIG ROLE IN THE POTENTIAL
FOR STORMS...AND THESE FEATURES WILL BE HIGHLY DEPENDENT ON THE
EVOLUTION OF THE MORNING CONVECTION (PLACEMENT OF OUTFLOW / CLOUD
DEBRIS LIMITING DESTABILIZATION).
IN GENERAL...THE PATTERN WILL FAVOR THE GREATEST INSTABILITY IN
THE SOUTHERN PORTIONS OF THE FORECAST AREA...PERHAPS AS HIGH AS
1500-2500 J/KG OF MIXED LAYER CAPE. STILL A WAYS REMOVED FROM THE
BRUNT OF THE JET...THE ILN CWA WILL NOT GET INTO A GREAT DEAL OF
WIND SHEAR TODAY...PERHAPS UP TO 30 KNOTS IN THE DEEP LAYER AND
NOT MUCH AT ALL IN THE LOWEST LEVELS. THE INSTABILITY SHOULD BE
SURFACE BASED AND UNCAPPED (RAP13 FORECASTS SHOW A 3 DEG C DROP IN
700MB TEMPS BY AFTERNOON)...AND THIS APPEARS TO BE ENOUGH TO
SUPPORT SOME SEVERE THREAT. THE LACK OF STRONGER SHEAR AND
ORGANIZED FORCING SHOULD BE A LIMITING FACTOR. IT IS POSSIBLE THAT
THE MORNING CONVECTION MAY END UP LEAVING A BOUNDARY THAT COULD
ACT AS THE FOCUS FOR CONVECTIVE DEVELOPMENT IN THE AFTERNOON
HOURS.
THE TEMPERATURE FORECAST IS ALSO SIGNIFICANTLY DEPENDENT ON THE
ABOVE FACTORS...THOUGH THE AIR MASS IS CERTAINLY CAPABLE OF
SUPPORTING TEMPS AS HIGH AS THE MID TO UPPER 80S. RAW MODEL TEMPS
ARE IN WIDE VARIANCE FROM MODEL TO MODEL...WITH INTENSE HEATING
BEFORE PRECIPITATION FORCES DROPS IN THE SURFACE TEMP FIELDS (AND
AT DIFFERENT TIMES AND PLACES). WHILE A GENERAL CONSENSUS WAS
USED...IN THE INTEREST OF BEING A BIT CONSERVATIVE GIVEN THE
UNCERTAIN CONVECTIVE FORECAST...THE MAX TEMPS WERE KNOCKED DOWN A
COUPLE DEGREES FROM THERE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
CONVECTION WILL LIKELY BE ONGOING FOR AT LEAST PART OF THE
FORECAST AREA DURING THE TUESDAY EVENING HOURS...WITH A DIURNAL
MIN LEADING TO MORE TRANQUIL CONDITIONS OVERNIGHT. HOWEVER...BY
WEDNESDAY MORNING...THIS MAY BEGIN TO CHANGE AGAIN. A SHORTWAVE
MOVING OUT OF THE SOUTHERN PLAINS WILL EVENTUALLY MAKE ITS WAY
JUST EAST OF THE ILN CWA BY MORNING...WITH MODEL AGREEMENT ON AN
ASSOCIATED CONVECTIVE COMPLEX SPREADING INTO INDIANA BY THEN.
MEANWHILE...SURFACE LOW PRESSURE WILL STRENGTHEN AS IT MOVES
THROUGH ILLINOIS AND INTO MICHIGAN...WITH GENERAL SURFACE
TROUGHING AND HEIGHT FALLS ALOFT SPREADING INTO THE ILN CWA. THIS
IS A FAVORABLE ENVIRONMENT FOR LIFT...AND SHOULD SUPPORT A LIKELY POP
FORECAST THROUGH MOST OF THE DAY WEDNESDAY. ALTHOUGH GENERALLY
UNIDIRECTIONAL...THE INCREASING PRESSURE GRADIENT AND
JUXTAPOSITION WITH THE RIGHT ENTRANCE REGION OF THE UPPER JET WILL
ALSO SUPPORT AN INCREASED BIT OF SHEAR AND FORCING (RESPECTIVELY).
THE LIMITING FACTOR FOR SEVERE POTENTIAL WILL BE
INSTABILITY...WHICH DOES NOT APPEAR TO BE PARTICULARLY STRONG (AND
THIS IS NOT SURPRISING GIVEN THE LACK OF EXPECTED SURFACE
HEATING). TEMPS ALOFT WILL CONTINUE TO DROP...WHICH SHOULD HELP
GENERATE 500-1000 J/KG IF SOME SUN CAN BE REALIZED. AN ALTERNATE
POSSIBILITY WOULD KEEP PRECIPITATION OVER THE CWA THROUGH THE
MORNING AND EARLY AFTERNOON...ESSENTIALLY LIMITING DESTABILIZATION
TO NEAR-ZERO. THE SOUNDINGS LOOK RATHER MOIST...LEADING TO THIN
CAPE AND LOW LCLS.
IT IS AN INTERESTING CONTRAST IN SEVERE POTENTIAL FROM TODAY
(TUESDAY)...WITH DIFFERENT ELEMENTS OF THE MESOSCALE ANALYSIS
APPEARING FAVORABLE ON EITHER DAY.
THE LARGE NORTHERN PLAINS UPPER LOW WILL FINALLY BE ON THE MOVE BY
LATE WEDNESDAY...CROSSING THE ILN CWA ON THURSDAY. THIS WILL BRING
ANOTHER HIGH CHANCE OF POPS ON THURSDAY...MAINLY IN THE NORTH AND
GENERALLY WITH DIURNAL TIMING. BEHIND THE AXIS OF THIS
TROUGH...RAPID DRYING IS EXPECTED.
TEMPERATURES WILL BEGIN A DOWNWARD TREND AFTER THE POORLY-DEFINED
COLD FRONT (ASSOCIATED WITH THE WEDNESDAY SURFACE LOW) MOVES
THROUGH THE REGION. A STRONGER CHANGE IN NEAR-SURFACE AIR MASS IS
EXPECTED BEHIND THE TROUGH ON THURSDAY NIGHT...WITH NORTHERLY
WINDS ADVECTING COLDER AND DRIER AIR INTO THE REGION.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
SURFACE HIGH PRESSURE WILL BUILD DOWN FROM THE NORTH AND INTO OUR
AREA FRIDAY INTO SATURDAY...KEEPING A SEASONABLY COOL AIRMASS IN
PLACE THROUGH THE START OF THE WEEKEND. HIGHS ON FRIDAY WILL BE IN
THE MID TO UPPER 60S AND WITH THE SURFACE HIGH OVERHEAD...LOWS
SATURDAY MORNING WILL DIP INTO THE LOW TO MID 40S. THE SURFACE
HIGH WILL BEGIN TO SHIFT OFF TO THE EAST THROUGH THE REMAINDER OF
THE WEEKEND AS MID LEVEL RIDGING BEGINS TO ESTABLISH ITSELF ALOFT.
THIS WILL RESULT IN A GRADUAL RETURN TO WARMER TEMPERATURES
THROUGH THE REST OF THE HOLIDAY WEEKEND. MODELS ARE STILL TRYING
TO SUGGEST THE POSSIBILITY OF SOME ENERGY DROPPING DOWN FROM THE
NORTHWEST LATE IN THE WEEKEND. HOWEVER...TIMING AND PLACEMENT ARE
HIGHLY VARIABLE SO WILL MAINTAIN A DRY FORECAST AT THIS POINT.
&&
.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
LARGE SCALE UPPER LEVEL LOW CENTERED OVER THE NORTHERN PLAINS WILL
MAKE LITTLE EASTWARD PROGRESSION OVER THE NEXT 24 HOURS. REGION
WILL BE LOCATED IN A WARM...MOIST SOUTH/SOUTHWEST FLOW AT THE SFC
AND ALOFT.
FIRST ITEM OF CONCERN WILL BE THE QLCS TO OUR WEST ACROSS WESTERN
INDIANA AND EASTERN ILLINOIS. SOME MODELS WEAKEN THIS FEATURE TO
THE POINT THAT IT IS GONE BY THE TIME IT GETS NEAR OUR WESTERN TAF
SITES BETWEEN 09Z AND 12Z. OTHER MODELS TRY TO HOLD IT TOGETHER
INTO OUR WESTERN TAF SITES BEFORE COMPLETELY WEAKENING IT. AT THIS
TIME...HAVE NOT PLACED ANY CONVECTION IN THE TAFS AND WILL MONITOR
LINE/TRENDS AND UPDATE/AMEND ACCORDINGLY IF NECESSARY.
OTHERWISE...THE TIMING OF CONVECTION FOR TODAY IS FAIRLY MURKY AS
MODELS ARE NOT HANDLING MESOSCALE FEATURES AT THE SURFACE AND
ALOFT WELL. KEPT PREVIOUS FORECAST TREND TO ALLOW FOR SHOWERS AND
THUNDERSTORMS DURING THE PEAK HEATING OF THE DAY FOLLOWED BY A
LULL IN ACTIVITY THIS EVENING. FOR LATE TONIGHT INTO WEDNESDAY...A
MORE BONAFIDE DISTURBANCE AND DEVELOPING LOW LEVEL JET WILL LIKELY
BRING WIDESPREAD PRECIPITATION TO OUR AREA...BUT EXACT TIMING IS
STILL IN QUESTION AT THIS POINT. WINDS TODAY WILL BE LOCALLY GUSTY
FROM THE SOUTHWEST TO 25 KNOTS WITH GUSTINESS SUBSIDING TOWARD
SUNSET.
OUTLOOK...THUNDERSTORMS WILL BE POSSIBLE FROM TUESDAY NIGHT THROUGH
THURSDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HATZOS
NEAR TERM...HATZOS
SHORT TERM...HATZOS
LONG TERM...JGL
AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
125 AM EDT TUE MAY 21 2013
.SYNOPSIS...
HIGH PRESSURE OVERNIGHT. AFTERNOON CONVECTION TUESDAY AND
WEDNESDAY. COLD FRONT APPROACHES WEDNESDAY AND MOVES ACROSS
THURSDAY. COOLER HIGH PRESSURE FRIDAY AND THE WEEKEND.
&&
.NEAR TERM /THROUGH TODAY/...
INTRODUCE AREAS OF FOG MAINLY OVER AREAS THAT RECEIVED RAIN DURING
THE AFTERNOON HOURS...AND OVER TYGART RIVER AND KANAWHA RIVER
VALLEYS...AND THE SOUTHERN COAL FIELDS OF WEST VIRGINIA DURING THE
PREDAWN HOURS. ADJUSTED HOURLY TEMPS CURVE. REMOVED ALL PCPN
THROUGH 12Z TUESDAY. MODELS SHOWING NO DISTURBANCES AT H5 WITHIN UPPER
RIDGE ACROSS NORTHEAST KY...OH...WV...AND PA. FOR
TUESDAY...AFTERNOON SHOWERS AND STORMS ARE POSSIBLE.
PREVIOUS DISCUSSION BELOW...
RADAR IMAGERY AT 18Z SHOWING SHOWERS WITH A FEW EMBEDDED
THUNDERSTORMS MAINLY CONFINED TO THE EASTERN HIGHER TERRAIN AT
THIS POINT. EXPECT THIS PRECIP TO CONTINUE EASTWARD AS THE S/W
TROUGH AND ASSOC VORT MAX RESPONSIBLE FOR TODAY/S PRECIP CONTINUES
EAST AS WELL. LATEST SFC OBS AND RUC13 CONTINUE TO DEPICT SOME SFC
CONVERGENCE WITH WEAK TROUGH ACROSS THE FAR WESTERN ZONES THIS
AFTERNOON. BEST LLVL MOISTURE HAS PUSHED EASTWARD AND NEAR-TERM
CONVECTIVE MODELS DO NOT SHOW ANY REDEVELOPMENT ACROSS THE WEST.
WILL HOWEVER GO AHEAD AND CONTINUE A SLIGHT CHANCE FOR CONVECTION
OUT HERE WITH JUST A PINCH OF LLVL MOISTURE STILL NOTED ON POINT
SOUNDINGS AND PWATS UP AROUND 1.2-1.4 INCHES.
DURING THE OVERNIGHT HOURS TODAY/S S/W TROUGH AND VORT MAX CONTINUE
EASTWARD. PRECIP WILL HAVE ENDED FOR MOST IF NOT ALL LOCATIONS BTWN
00Z-03Z TUE. MOST LOCATIONS WILL REMAIN PRECIP-FREE OVERNIGHT BUT
LATEST NWP GUIDANCE DEPICTING A 2-3KFT LAYER OF CONVECTIVE MOISTURE
PUSHING INTO THE NORTHERN ZONES CENTERED AROUND 850MB AND AROUND 12Z
TUE. SIMULTANEOUSLY 850MB CONVERGENCE NOTED ACROSS THE I-79 CORRIDOR
AS WELL AND THUS WILL BRING IN SLIGHT CHANCE POPS WITH THUNDER WITH
THIS FEATURE. INHERITED MINS IN THE LOW/MID 60S MOST LOWLAND
LOCATIONS LOOK GOOD. WILL CONTINUE TO CARRY AT LEAST A SLIGHT CHANCE
OF SHOWERS/THUNDER MOST LOCATION DURING THE DAY...BUT THE BETTER
CHANCE OF THUNDERSTORMS ARRIVES SE OHIO ZONES BY AND AFTER 21Z AS
BETTER LLVL MOISTURE ARRIVES WITH DECENT SFC CONVERGENCE NOTED SAME
AREA. SHEAR IS WEAK AND THUS ORGANIZATION WILL BE AS WELL WITH
REGARD TO SEVERE POTENTIAL. BUT HEAVY DOWNPOURS WILL BE POSSIBLE AND
WITH SOME STRONG WINDS.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
MAIN WEATHER MAKER THROUGH THE SHORT TERM WILL BE THE SURFACE COLD
FRONT PASSING WEDNESDAY...AND THEN THE LINGER UPPER LEVEL TROUGH.
FOR TUESDAY NIGHT...MAIN FOCUS IS TO THE WEST...SO DECREASED POPS
SOME...HOWEVER WITH LOTS OF MOISTURE STILL HANGING AROUND COULD NOT
GO DRY SO HAVE SLIGHT CHANCE TO CHANCE POPS FOR MUCH OF THE AREA
OVERNIGHT. COLD FRONT APPROACHES FROM THE WEST WEDNESDAY...WILL
LIKELY BE ONGOING CONVECTION/OUTFLOW BOUNDARIES TO OUR WEST
WEDNESDAY MORNING. WE SHOULD HAVE PLENTY OF INSTABILITY IN THE
WARM SECTOR AHEAD OF THE FRONT...NAM IS SHOWING 2000+ J/KG CAPE
ALONG THE OHIO RIVER AROUND NOON...WITH 30-40KTS BULK SHEER AND
PWATS AROUND 1.5 INCHES. SHOULD SEE A ROUND OF ORGANIZED
CONVECTION OUT AHEAD OF THE COLD FRONT MOVING FROM WEST TO EAST
ACROSS THE CWA. THE MOST LIKELY AREA OF CONCERN FOR STRONG TO
SEVERE STORMS CONTINUES TO BE ALONG AND EITHER SIDE OF THE OHIO
RIVER FROM SE OHIO INTO NORTH CENTRAL WEST VIRGINIA. WILL CONTINUE
HWO MENTION FOR DAMAGING WINDS AND HAIL POTENTIAL. THE ACTUAL COLD
FRONT WILL NOT PASS UNTIL THURSDAY...SO POPS CONTINUE THROUGH THE
SHORT TERM PERIOD.
WEDNESDAY WILL BE A WARM DAY...BUT WITH PLENTY OF CLOUDS SHOULD NOT
BE AS WARM AS TUESDAY. THURSDAY WILL BE ABOUT 10 DEGREES COOLER.
OVERNIGHT LOWS WILL BE MILD WITH LOTS OF CLOUDS AND MOISTURE.
BASED ON RECENT VERIFICATION STATS...BLENDED IN BIAS- CORRECTED
CONSENSUS GUIDANCE FOR BOTH HIGHS AND LOWS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
HAVE GENERALLY FOLLOWED WPC THINKING FOR THIS PORTION OF THE FORECAST.
COLD FRONT SHOULD BE LOCATED SOUTHEAST OF THE REGION AT THE
BEGINNING OF THE PERIOD...WITH HIGH PRESSURE BUILDING IN. CHANCE
OF SHOWERS AND STORMS WILL END FROM THE NORTHWEST THURSDAY NIGHT
INTO FRIDAY. HOWEVER...A MID-LEVEL DISTURBANCE MOVING SOUTHEAST
WILL INCREASE THE CHANCES FOR PRECIPITATION ON FRIDAY....MAINLY IN
THE MOUNTAINS AND ADJACENT COUNTIES.
HIGH PRESSURE WILL THEN BE IN CONTROL OF THE AREA INTO MONDAY.
HOWEVER...A WEAK MID-LEVEL DISTURBANCE WILL SLIDE SOUTHEAST SATURDAY
NIGHT INTO SUNDAY.
A WARM FRONT WILL DEVELOP AND APPROACH THE REGION ON MONDAY. ECMWF
SUGGESTS THERE WILL BE A CHANCE OF SHOWERS AND STORMS MONDAY
AFTERNOON...ESPECIALLY ACROSS THE SOUTH. BECAUSE OF UNCERTAINTY...HAVE
LEFT THESE CHANCES OUT OF THE FORECAST FOR NOW.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
PATCHY DENSE FOG CAN BE EXPECTED IN VALLEYS IN AND JUST WEST OF THE
MOUNTAINS THAT RECEIVED RAIN TODAY. FURTHER WEST AND ON
HILLTOPS...WINDS SHOULD PREVENT THE DENSE FOG. CUMULUS CAN BE
EXPECTED TODAY...WITH AFTERNOON AND EVENING THUNDERSTORMS POSSIBLE.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z WEDNESDAY...
FORECAST CONFIDENCE...MODERATE WITH FOG EARLY THIS MORNING...THEN
HIGH.
ALTERNATE SCENARIOS: SOME UNCERTAINTY ON FOG DENSITY AND COVERAGE
OVERNIGHT. TIMING OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON COULD
VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE TUE 05/21/13
UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13
CRW CONSISTENCY M H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H M H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY L L L L L L L L H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 06Z WEDNESDAY...
IFR CONDITIONS POSSIBLE WEDNESDAY WITH SHOWERS AND THUNDERSTORMS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...JSH/ARJ/50
NEAR TERM...ARJ/50
SHORT TERM...MZ
LONG TERM...JSH
AVIATION...RPY
AREA FORECAST DISCUSSION
NWS TULSA OK
312 PM CDT TUE MAY 21 2013
.DISCUSSION...
LINEAR MCS THAT HAS FORMED AHEAD OF COMPACT UPPER SYSTEM SURGING
ACROSS OK/TX IS CURRENTLY MOVING ACROSS PORTIONS OF SERN OK. THE
LINE HAS BEEN STRONG/MARGINALLY SEVERE SO FAR...AND STILL COULD SEE
SOME 60+ MPH WIND GUSTS OVER THE NEXT FEW HOURS. HRRR HAS SHOWN A
VERY GOOD HANDLE ON THE COMPLEX...WITH THE LEADING EDGE EXITING OUR
FORECAST AREA AROUND 22Z-23Z. CURRENT FLASH FLOOD WATCH IS SET TO
EXPIRE AT 00Z...ALTHOUGH MAY EXTEND IT A FEW MORE HOURS. WILL TAKE A
LAST LOOK AT RADAR BEFORE FINAL DECISION. OTHERWISE...PARTIALLY
CLEARING SKIES ALONG WITH DRIER LOW-LEVEL AIR WILL ALLOW TEMPS TO
FALL INTO THE 50S FOR MUCH OF THE AREA.
WEAK SURFACE BOUNDARY MAY BE PRESENT ACROSS THE AREA ON
WEDNESDAY...ALTHOUGH ATMOSPHERE SHOULD BE TOO DRY AND WORKED OVER TO
SUPPORT PRECIPITATION.
UPPER PATTERN WILL BECOME INCREASINGLY AMPLIFIED BY MID-TO-LATE
WEEK...WITH RIDGING THROUGH THE PLAINS SANDWICHED BY DEEP UPPER
SYSTEMS ACROSS THE PAC NW AND THE EAST COAST. MODELS SUGGEST THAT
SEVERAL WEAK WAVES WILL MOVE INTO THE MEAN RIDGE POSITION...WITH AT
LEAST SOME LOW POPS WARRANTED ACROSS WRN SECTIONS IN THE VERY
WARM/MOIST AIRMASS.
UPPER RIDGE SHOULD FLATTEN SOME ACROSS THE SRN/CENTRL PLAINS GOING
INTO THE WEEKEND. WITH THE FORECAST AREA ALONG THE SRN EDGE OF THE
STRONGER UPPER FLOW...SHOULD SEE PERIODIC SHOWER/THUNDERSTORM
EPISODES...ESPECIALLY ACROSS NE OK/NW AR. TOUGH TO PINPOINT WHICH
DAY WILL HAVE THE BEST CHANCES...SO HAVE MAINTAINED GENERAL CHANCE
POPS FOR ABOUT THE NRN HALF OF THE AREA FOR THE WEEKEND AND INTO
EARLY NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 55 81 58 78 / 40 0 10 20
FSM 58 83 62 81 / 80 10 10 10
MLC 55 83 61 84 / 40 0 10 20
BVO 52 81 54 77 / 20 0 10 20
FYV 54 79 55 76 / 80 10 10 10
BYV 56 79 55 77 / 80 10 10 10
MKO 55 82 60 79 / 60 10 10 20
MIO 54 78 56 78 / 50 10 10 10
F10 55 82 61 79 / 30 0 10 20
HHW 60 85 64 85 / 50 0 10 20
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...FLASH FLOOD WATCH UNTIL 7 PM TUESDAY FOR OKZ049-OKZ053-OKZ068-
OKZ069-OKZ070-OKZ071-OKZ072-OKZ073-OKZ074-OKZ075-OKZ076.
AR...FLASH FLOOD WATCH UNTIL 7 PM TUESDAY FOR ARZ001-ARZ002-ARZ010-
ARZ011-ARZ019-ARZ020-ARZ029.
&&
$$
SHORT TERM...06
LONG TERM....18
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1048 PM EDT WED MAY 22 2013
.SYNOPSIS...
AN APPROACHING UPPER LEVEL TROUGH WILL CONTINUE TO INFLUENCE THE
REGION THROUGH THURSDAY. A COLD FRONT MOVES THROUGH THE AREA
THURSDAY NIGHT...BEFORE A COOLER AND DRIER AIRMASS SETTLES IN FOR
THE WEEKEND AND MODIFIES THROUGH THE EARLY PART OF NEXT WEEK.
&&
.NEAR TERM /THROUGH THURSDAY/...
AS OF 1045 PM...BROKEN MULTICELL LINE OF THUNDERSTORMS CONTINUES TO
MOVE TO THE EAST NORTHEAST ACROSS THE UPSTATE IN ASSOCIATION WITH
CONVERGENCE NEAR FRONTAL BOUNDARY. ELSEWHERE...DISCRETE PULSE
SHOWERS AND THUNDERSTORMS WERE PRESENT ACROSS PORTIONS OF THE NORTH
CAROLINA FOOTHILLS/PIEDMONT. THE MAIN THREATS WITH ANY OF THESE
THUNDERSTORMS ARE BRIEF HEAVY RAINFALL...LARGE HAIL...DAMAGING
WINDS...AND FREQUENT CLOUD TO GROUND LIGHTNING. AS FOR THE
FCST...THE ACTIVITY CURRENTLY EXTENDING ACROSS THE WESTERN CWFA
SHOULD MOVE EASTWARD ACROSS THE CWFA GRADUALLY DIMINISHING IN
INTENSITY AS INSTABILITY WANES. GENERALLY CHANGED POPS TO REFLECT
THIS WAVE OF ACTIVITY BEING FOLLOWED BY MUCH LOWER POPS IN SCHC TO
LOW CHC RANGE DUE TO CONTINUED PRESENCE OF UPSTREAM ACTIVITY.
ADJUSTED TEMPERATURE TRENDS FURTHER BY LOWERING TEMPS ACROSS THE
NORTH CAROLINA PIEDMONT DUE TO OUTFLOW BOUNDARIES FROM EARLIER
CONVECTION SPREADING ACROSS THIS REGION.
REMAINDER OF PREVIOUS DISCUSSION...
AS OF 800 PM...TOUCHED UP EVENING TEMP TRENDS...WHICH HAVE BEEN
IMPACTED GREATLY BY THUNDERSTORMS AND THEIR COOL OUTFLOW. RADAR
INDICATES SEVERAL BOUNDARIES SPREADING ACROSS THE PIEDMONT...WHERE
TEMPS REMAIN IN THE MID TO UPPER 70S. THINK THESE WILL BE IMPACTED
BY BOTH DIURNAL COOLING AS WELL AS THE OUTFLOW. LAMP TEMPS SEEM TO
REFLECT THE CURRENT SITUATION FAIRLY WELL AND THESE ARE IN DECENT
AGREEMENT WITH LATE EVENING TEMPS...SO NO CHANGES MADE OTHER THAN TO
UPDATE FIRST FEW HRS.
AS OF MID AFTERNOON...A BROKEN BAND OF SHOWERS AND THUNDERSTORMS WAS
LOCATED JUST EAST OF THE BLUE RIDGE IN NC FROM I-40 NEWD...WITH
OTHER STORMS POPPING UP ACROSS THE HIGHER TERRAIN AIDED BY
DIFFERENTIAL HEATING. EXPECT THE STORMS TO BECOME MORE NUMEROUS
ACROSS THE MTNS THROUGH LATE AFTERNOON...WITH THAT CONVECTION MOVING
EAST OVER THE FOOTHILLS AND PIEDMONT INTO THE EVENING. POP HAS BEEN
ADJUSTED ACCORDINGLY. SOME OF THESE STORMS WILL PRODUCE LARGE HAIL
AND DAMAGING WIND GUSTS. HIGH TEMPS STILL LOOK OKAY.
FOR TONIGHT...THE CONVECTION ALLOWING MODELS SUGGEST THAT ANOTHER
ROUND OF STORMS WILL FIRE TO THE WEST AND THEN MOVE EAST INTO THE
FCST AREA IN THE EARLY EVENING. THE HRRR AND 4KM WRF PAINT A SIMILAR
PICTURE WITH NUMEROUS STORMS OVER THE WESTERN HALF OF THE FCST AREA
THROUGH MID TO LATE EVENING. A SHORT WAVE MOVING AROUND THE UPPER
TROF...COMBINED WITH SOME UPPER DIVERGENCE...SHOULD PROVIDE THE
NECESSARY SUPPORT FOR THIS CONVECTION TO THRIVE. WITH THAT IN
MIND...THE POP WAS RAISED TO LIKELY OVER THE WESTERN HALF. AFTER
SOME LOSS OF HEATING...THE STORMS SHOULD BECOME A BIT LESS NUMEROUS
OVER THE NC PIEDMONT. AT THAT POINT...THE POP WAS KEPT BELOW 50 PCT
ONLY BECAUSE OF SOME UNCERTAINTY GIVEN BY THE CONVECTION HAVING NOT
YET DEVELOPED AS OF 18Z. MIN TEMPS SHOULD REMAIN MILD.
THE COLD FRONT WILL MOVE IN FROM THE WEST ON THURSDAY...MOST LIKELY
OVER THE MTNS IN THE MORNING AND THEN MOVING OUT OVER THE FOOTHILLS
IN THE AFTERNOON. NEW CONVECTION SHOULD DEVELOP ALONG THE FRONT
MAINLY OVER THE PIEDMONT IN THE AFTERNOON. THIS IS TRICKY BECAUSE OF
THE LIKELIHOOD OF WIDESPREAD DEBRIS CLOUDINESS INTO THE EARLY
AFTERNOON THAT WOULD LIMIT CONVECTION. THINK THE MTNS STAND A CHANCE
BECAUSE OF THE FRONT EARLY IN THE DAY. THE UPSTATE AND NE GEORGIA
HAS THE LEAST FAVORABLE ENVIRONMENT...SO A 20 PCT POP WAS KEPT. THE
PIEDMONT HAS A BETTER CHANCE AHEAD OF THE FRONT SO A LIKELY POP WAS
CARRIED OVER THE EASTERN ZONES FOR A TIME. SEVERE STORMS ARE
POSSIBLE...BUT MORE LIKELY TO THE EAST OF I-77. HIGH TEMPS WILL BE
A FEW DEGREES COOLER.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 230 PM WEDNESDAY...A SURFACE COLD FRONT SHOULD BE LOCATED NEAR
THE EDGE OF OUR WESTERN NORTH CAROLINA PIEDMONT EARLY THURSDAY
EVENING. THIS LINES UP WELL WITH THE SHORT TERM SUITE OF MODELS...
AND LINES UP WITH WITH AN AXIS OF DPVA WHICH SHOULD BE CROSSING THAT
REGION LATE IN THE DAY/EARLY EVENING. CONVECTIVE ALLOWING MODELS
ALSO DEPICT THIS TREND AND IS SUPPORTED BY INSTABILITY LINGERING
ACROSS THAT AREA. AS A RESULT WE WILL HAVE A CORRIDOR OF LOWER
CHANCE POPS IN OUR EASTERN FORECAST AREA (FA) UNTIL AROUND DARK OR
SO.
A SECOND AREA OF PRECIPITATION FOR THURSDAY NIGHT WILL BE IN THE NC
MOUNTAINS WHERE ANOTHER LOBE OF ENERGY...EMBEDDED IN A SHARPENING H5
TROF...CROSSES THE AREA. WE WILL CARRY CHANCE POPS IN THE NC
MOUNTAINS THURSDAY NIGHT AND FRIDAY MORNING...IN A CONTINUALLY
DEEPENING FORCED UPPER AIR PATTERN. ALTHOUGH THE SHARPENING TROF
CROSSES ALL OF OUR REGION FRIDAY...THE ATMOSPHERE LOOKS TO DRY FOR
ANY PRECIPITATION.
MEANWHILE THE H85 ISALLOBARIC PATTERN WAS INDICATING SIGNIFICANT
CROSS CONTOURS OF THERMAL STRUCTURE AND HEIGHTS FRIDAY. THIS
SUGGESTS AT LEAST SIGNIFICANT COLD AIR ADVECTION (ESPECIALLY JUST
ABOVE THE SURFACE) AND MIXING DOWN. WE HAVE FOLLOWED BUFKIT
INFORMATION FOR WIND GUSTS FRIDAY...AND IN ALL LIKELIHOOD WE WILL
NEED SOME TYPE OF WIND HEADLINE FRIDAY FOR PART OF OUR FAA...
PARTICULARLY IN THE AFTERNOON.
HIGH PRESSURE WILL EDGE TOWARD THE REGION FRIDAY NIGHT...WHICH WILL
BRING A COOL/COLD NIGHT AROUND THE AREA. SOME MOUNTAIN LOCATIONS TO
DIP INTO THE 30S...BUT BELIEVE ENOUGH MIXING SHOULD PREVENT FROST
DUE TO THE LINGERING GRADIENT OF HIGH PRESSURE OFF TO THE NORTHWEST
AND LOW PRESSURE MOVING UP THE EASTERN SEABOARD. HOWEVER WE WILL
HAVE TO MONITOR TRENDS.
HIGH PRESSURE TO HOLD SWAY SATURDAY WITH A PLEASANT DAY ON
TAP.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 225 PM WEDNESDAY...RATHER GOOD AGREEMENT IS HAD IN THE UPPER
LEVEL OMEGA PATTERN OVER THE EXT RANGE. THE 12Z GFS IS A BIT OF AN
OUTLIER AND SHARPENS THE EAST COAST TROF AND SUBSEQUENT DEEP NW/LY
FLOW GRADIENT MORESO THAN THE OTHER OP MODELS...BUT NOT ENOUGH FOR A
SIGFNT LLVL RESPONSE. AT THE SFC...THERE ARE MAJOR DIFFERENCES
EVOLVING WITH THE SYNOPTIC PATTERN...THUS A LESS THAN AVG
CONFIDENCE IS HAD AS THE EXT RANGE PROGRESSES.
HIGH PRESSURE CONTINUES TO BUILD IN FROM THE NORTH SUN AND KEEPS
THINGS DRY. HIGH TEMPS WILL BE A LITTLE BELOW NORMAL WITH A
REINFORCING CP AIRMASS MIXING IN. THE LLVL FLOW BECOMES DEFINED
SW/LY MON AS THE ATL HIGH NUDGES IN. THIS WILL ALSO ENABLE A WARM
FRONT OR STATIONARY TO PERHAPS IMPINGE UPON THE REGION MON NIGHT
INTO TUE. THERE IS LOW CONFIDENCE IN THIS FEATURE...HOWEVER...AS THE
GFS KEEPS ANY FRONTOGENESIS WELL TO THE NORTH OF THE REGION WITH A
WEAK TROF BUILDING INTO THE SFC SE RIDGE...WHILE THE ECMWF HAS THE
WARM FRONT STALLING OUT ACROSS THE CWFA DURING THE DAY TUE INTO WED.
RIGHT NOW...POPS HAVE BEEN CONTINUED IN THE LOW END CHANCE RANGE MON
THROUGH TUE...AND A DRIER HPC BLEND WAS MAINTAINED FOR WED.
SOUNDINGS SHOW VERY LITTLE SBCAPE DEVELOPING MON AS THE UPPER FLOW
KEEPS A SUBSIDENCE INVERSION IN PLACE...HOWEVER A RELATIVE WEAKENING
ALOFT TUE SHOULD ENABLE THE DEVELOPMENT OF SOME ENHANCE CONVECTION
AND TSTMS. MAX TEMPS WILL WARM EACH DAY MON THROUGH THE PERIOD TO A
LITTLE ABOVE NORMAL IN GOOD SW/LY FLOW AND INSOLATION.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
AT KCLT...PREVAILING VFR THIS EVENING BUT THERE REMAINS THE
POSSIBILITY OF RESTRICTIONS FROM THUNDERSTORMS. STABILIZING OUTFLOW
FROM UPSTREAM TS MAY PUT A STOP TO CONVECTION BUT ITS LEADING EDGE
COULD BE THE FOCUS FOR NEW DEVELOPMENT FOR A TIME TONIGHT. INCLUDED
A TEMPO THRU 04Z FOR MVFR TSRA...BUT WILL CLOSELY WATCH TRENDS OVER
NEXT COUPLE OF HOURS AND MAY BE ABLE TO REMOVE IT. PROFILES BECOME
INCREASINGLY MOIST OVERNIGHT AHEAD OF FRONTAL BOUNDARY. PER MODEL RH
FIELDS EXPECT A LOWERING TO SOLID MVFR LATE...WITH SUFFICIENT
ELEVATED INSTABILITY TO WARRANT ANOTHER TEMPO FOR TSRA. LULL IN
ACTIVITY EXPECTED NEAR DAYBREAK WITH LOW MVFR PERSISTING UNTIL
MIXING GETS UNDERWAY MID MORNING. DECENT THUNDER CHANCES AGAIN WITH
DIURNAL HEATING WARRANTING -TSRA BUT VFR.
ELSEWHERE...CONVECTION CONTINUES THIS EVENING ACROSS MAINLY THE
MTNS/FOOTHILLS. MUCH OF THE PIEDMONT WILL BE STABILIZED BY TS
OUTFLOW WITH UPSTREAM ACTIVITY LIKELY TO DIMINISH TOO QUICKLY WITH
LOSS OF HEATING TO HAVE EFFECTS. OVERNIGHT FROPA WILL BRING BACK TS
OR SHRA CHANCES. HANDLED THIS WITH VCTS OR TEMPOS AS APPROPRIATE.
PLENTY OF MOISTURE TO THINK RESTRICTIVE CIGS WILL DEVELOP BEHIND THE
FRONT AND PERSIST THRU DAYBREAK. DIURNAL CU WILL QUICKLY GROW IN
UNSTABLE ATMOSPHERE BY LATE MORNING. CU BASES EXPECTED TO BE WELL
WITHIN VFR TERRITORY...WITH SOME LOW TS CHANCES ALSO THROUGH PEAK
HEATING.
OUTLOOK...RESTRICTIONS POSSIBLE WITH LINGERING MOISTURE OVERNIGHT
THU NIGHT AND FRI MORNING. GENERALLY VFR WEATHER FRIDAY AND SATURDAY.
CONFIDENCE TABLE...
02-08Z 08-14Z 14-20Z 20-02Z
KCLT MED 60% HIGH 86% HIGH 80% HIGH 100%
KGSP LOW 58% MED 72% HIGH 82% HIGH 100%
KAVL MED 71% HIGH 97% HIGH 98% HIGH 100%
KHKY LOW 45% MED 77% HIGH 91% HIGH 100%
KGMU LOW 58% MED 73% HIGH 100% HIGH 100%
KAND MED 65% MED 76% HIGH 100% 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...SBK
NEAR TERM...CDG/PM/WIMBERLEY
SHORT TERM...TS
LONG TERM...SBK
AVIATION...CDG/WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
822 PM EDT WED MAY 22 2013
.SYNOPSIS...
AN APPROACHING UPPER LEVEL TROUGH WILL CONTINUE TO INFLUENCE THE
REGION THROUGH THURSDAY. A COLD FRONT MOVES THROUGH THE AREA
THURSDAY NIGHT...BEFORE A COOLER AND DRIER AIRMASS SETTLES IN FOR
THE WEEKEND AND MODIFIES THROUGH THE EARLY PART OF NEXT WEEK.
&&
.NEAR TERM /THROUGH THURSDAY/...
AS OF 800 PM...TOUCHED UP EVENING TEMP TRENDS...WHICH HAVE BEEN
IMPACTED GREATLY BY THUNDERSTORMS AND THEIR COOL OUTFLOW. RADAR
INDICATES SEVERAL BOUNDARIES SPREADING ACROSS THE PIEDMONT...WHERE
TEMPS REMAIN IN THE MID TO UPPER 70S. THINK THESE WILL BE IMPACTED
BY BOTH DIURNAL COOLING AS WELL AS THE OUTFLOW. LAMP TEMPS SEEM TO
REFLECT THE CURRENT SITUATION FAIRLY WELL AND THESE ARE IN DECENT
AGREEMENT WITH LATE EVENING TEMPS...SO NO CHANGES MADE OTHER THAN TO
UPDATE FIRST FEW HRS.
AS OF 430 PM...INCREASED POPS ACROSS THE UPSTATE OF SOUTH CAROLINA
AND THE PIEDMONT OF NORTH CAROLINA DURING THE OVERNIGHT HOURS AS
SHORT TERM CONVECTIVE MODEL GUIDANCE CONTINUES WIDESPREAD CONVECTION
ACROSS THE ABOVE MENTIONED REGIONS THROUGH 10Z THURSDAY. ALSO
TOUCHED UP SKY AND TEMP GRIDS. OTHERWISE...NO OTHER CHANGES WERE
MADE.
REMAINDER OF PREVIOUS DISCUSSION...
AS OF MID AFTERNOON...A BROKEN BAND OF SHOWERS AND THUNDERSTORMS WAS
LOCATED JUST EAST OF THE BLUE RIDGE IN NC FROM I-40 NEWD...WITH
OTHER STORMS POPPING UP ACROSS THE HIGHER TERRAIN AIDED BY
DIFFERENTIAL HEATING. EXPECT THE STORMS TO BECOME MORE NUMEROUS
ACROSS THE MTNS THROUGH LATE AFTERNOON...WITH THAT CONVECTION MOVING
EAST OVER THE FOOTHILLS AND PIEDMONT INTO THE EVENING. POP HAS BEEN
ADJUSTED ACCORDINGLY. SOME OF THESE STORMS WILL PRODUCE LARGE HAIL
AND DAMAGING WIND GUSTS. HIGH TEMPS STILL LOOK OKAY.
FOR TONIGHT...THE CONVECTION ALLOWING MODELS SUGGEST THAT ANOTHER
ROUND OF STORMS WILL FIRE TO THE WEST AND THEN MOVE EAST INTO THE
FCST AREA IN THE EARLY EVENING. THE HRRR AND 4KM WRF PAINT A SIMILAR
PICTURE WITH NUMEROUS STORMS OVER THE WESTERN HALF OF THE FCST AREA
THROUGH MID TO LATE EVENING. A SHORT WAVE MOVING AROUND THE UPPER
TROF...COMBINED WITH SOME UPPER DIVERGENCE...SHOULD PROVIDE THE
NECESSARY SUPPORT FOR THIS CONVECTION TO THRIVE. WITH THAT IN
MIND...THE POP WAS RAISED TO LIKELY OVER THE WESTERN HALF. AFTER
SOME LOSS OF HEATING...THE STORMS SHOULD BECOME A BIT LESS NUMEROUS
OVER THE NC PIEDMONT. AT THAT POINT...THE POP WAS KEPT BELOW 50 PCT
ONLY BECAUSE OF SOME UNCERTAINTY GIVEN BY THE CONVECTION HAVING NOT
YET DEVELOPED AS OF 18Z. MIN TEMPS SHOULD REMAIN MILD.
THE COLD FRONT WILL MOVE IN FROM THE WEST ON THURSDAY...MOST LIKELY
OVER THE MTNS IN THE MORNING AND THEN MOVING OUT OVER THE FOOTHILLS
IN THE AFTERNOON. NEW CONVECTION SHOULD DEVELOP ALONG THE FRONT
MAINLY OVER THE PIEDMONT IN THE AFTERNOON. THIS IS TRICKY BECAUSE OF
THE LIKELIHOOD OF WIDESPREAD DEBRIS CLOUDINESS INTO THE EARLY
AFTERNOON THAT WOULD LIMIT CONVECTION. THINK THE MTNS STAND A CHANCE
BECAUSE OF THE FRONT EARLY IN THE DAY. THE UPSTATE AND NE GEORGIA
HAS THE LEAST FAVORABLE ENVIRONMENT...SO A 20 PCT POP WAS KEPT. THE
PIEDMONT HAS A BETTER CHANCE AHEAD OF THE FRONT SO A LIKELY POP WAS
CARRIED OVER THE EASTERN ZONES FOR A TIME. SEVERE STORMS ARE
POSSIBLE...BUT MORE LIKELY TO THE EAST OF I-77. HIGH TEMPS WILL BE
A FEW DEGREES COOLER.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 230 PM WEDNESDAY...A SURFACE COLD FRONT SHOULD BE LOCATED NEAR
THE EDGE OF OUR WESTERN NORTH CAROLINA PIEDMONT EARLY THURSDAY
EVENING. THIS LINES UP WELL WITH THE SHORT TERM SUITE OF MODELS...
AND LINES UP WITH WITH AN AXIS OF DPVA WHICH SHOULD BE CROSSING THAT
REGION LATE IN THE DAY/EARLY EVENING. CONVECTIVE ALLOWING MODELS
ALSO DEPICT THIS TREND AND IS SUPPORTED BY INSTABILITY LINGERING
ACROSS THAT AREA. AS A RESULT WE WILL HAVE A CORRIDOR OF LOWER
CHANCE POPS IN OUR EASTERN FORECAST AREA (FA) UNTIL AROUND DARK OR
SO.
A SECOND AREA OF PRECIPITATION FOR THURSDAY NIGHT WILL BE IN THE NC
MOUNTAINS WHERE ANOTHER LOBE OF ENERGY...EMBEDDED IN A SHARPENING H5
TROF...CROSSES THE AREA. WE WILL CARRY CHANCE POPS IN THE NC
MOUNTAINS THURSDAY NIGHT AND FRIDAY MORNING...IN A CONTINUALLY
DEEPENING FORCED UPPER AIR PATTERN. ALTHOUGH THE SHARPENING TROF
CROSSES ALL OF OUR REGION FRIDAY...THE ATMOSPHERE LOOKS TO DRY FOR
ANY PRECIPITATION.
MEANWHILE THE H85 ISALLOBARIC PATTERN WAS INDICATING SIGNIFICANT
CROSS CONTOURS OF THERMAL STRUCTURE AND HEIGHTS FRIDAY. THIS
SUGGESTS AT LEAST SIGNIFICANT COLD AIR ADVECTION (ESPECIALLY JUST
ABOVE THE SURFACE) AND MIXING DOWN. WE HAVE FOLLOWED BUFKIT
INFORMATION FOR WIND GUSTS FRIDAY...AND IN ALL LIKELIHOOD WE WILL
NEED SOME TYPE OF WIND HEADLINE FRIDAY FOR PART OF OUR FAA...
PARTICULARLY IN THE AFTERNOON.
HIGH PRESSURE WILL EDGE TOWARD THE REGION FRIDAY NIGHT...WHICH WILL
BRING A COOL/COLD NIGHT AROUND THE AREA. SOME MOUNTAIN LOCATIONS TO
DIP INTO THE 30S...BUT BELIEVE ENOUGH MIXING SHOULD PREVENT FROST
DUE TO THE LINGERING GRADIENT OF HIGH PRESSURE OFF TO THE NORTHWEST
AND LOW PRESSURE MOVING UP THE EASTERN SEABOARD. HOWEVER WE WILL
HAVE TO MONITOR TRENDS.
HIGH PRESSURE TO HOLD SWAY SATURDAY WITH A PLEASANT DAY ON
TAP.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 225 PM WEDNESDAY...RATHER GOOD AGREEMENT IS HAD IN THE UPPER
LEVEL OMEGA PATTERN OVER THE EXT RANGE. THE 12Z GFS IS A BIT OF AN
OUTLIER AND SHARPENS THE EAST COAST TROF AND SUBSEQUENT DEEP NW/LY
FLOW GRADIENT MORESO THAN THE OTHER OP MODELS...BUT NOT ENOUGH FOR A
SIGFNT LLVL RESPONSE. AT THE SFC...THERE ARE MAJOR DIFFERENCES
EVOLVING WITH THE SYNOPTIC PATTERN...THUS A LESS THAN AVG
CONFIDENCE IS HAD AS THE EXT RANGE PROGRESSES.
HIGH PRESSURE CONTINUES TO BUILD IN FROM THE NORTH SUN AND KEEPS
THINGS DRY. HIGH TEMPS WILL BE A LITTLE BELOW NORMAL WITH A
REINFORCING CP AIRMASS MIXING IN. THE LLVL FLOW BECOMES DEFINED
SW/LY MON AS THE ATL HIGH NUDGES IN. THIS WILL ALSO ENABLE A WARM
FRONT OR STATIONARY TO PERHAPS IMPINGE UPON THE REGION MON NIGHT
INTO TUE. THERE IS LOW CONFIDENCE IN THIS FEATURE...HOWEVER...AS THE
GFS KEEPS ANY FRONTOGENESIS WELL TO THE NORTH OF THE REGION WITH A
WEAK TROF BUILDING INTO THE SFC SE RIDGE...WHILE THE ECMWF HAS THE
WARM FRONT STALLING OUT ACROSS THE CWFA DURING THE DAY TUE INTO WED.
RIGHT NOW...POPS HAVE BEEN CONTINUED IN THE LOW END CHANCE RANGE MON
THROUGH TUE...AND A DRIER HPC BLEND WAS MAINTAINED FOR WED.
SOUNDINGS SHOW VERY LITTLE SBCAPE DEVELOPING MON AS THE UPPER FLOW
KEEPS A SUBSIDENCE INVERSION IN PLACE...HOWEVER A RELATIVE WEAKENING
ALOFT TUE SHOULD ENABLE THE DEVELOPMENT OF SOME ENHANCE CONVECTION
AND TSTMS. MAX TEMPS WILL WARM EACH DAY MON THROUGH THE PERIOD TO A
LITTLE ABOVE NORMAL IN GOOD SW/LY FLOW AND INSOLATION.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
AT KCLT...PREVAILING VFR THIS EVENING BUT THERE REMAINS THE
POSSIBILITY OF RESTRICTIONS FROM THUNDERSTORMS. STABILIZING OUTFLOW
FROM UPSTREAM TS MAY PUT A STOP TO CONVECTION BUT ITS LEADING EDGE
COULD BE THE FOCUS FOR NEW DEVELOPMENT FOR A TIME TONIGHT. INCLUDED
A TEMPO THRU 04Z FOR MVFR TSRA...BUT WILL CLOSELY WATCH TRENDS OVER
NEXT COUPLE OF HOURS AND MAY BE ABLE TO REMOVE IT. PROFILES BECOME
INCREASINGLY MOIST OVERNIGHT AHEAD OF FRONTAL BOUNDARY. PER MODEL RH
FIELDS EXPECT A LOWERING TO SOLID MVFR LATE...WITH SUFFICIENT
ELEVATED INSTABILITY TO WARRANT ANOTHER TEMPO FOR TSRA. LULL IN
ACTIVITY EXPECTED NEAR DAYBREAK WITH LOW MVFR PERSISTING UNTIL
MIXING GETS UNDERWAY MID MORNING. DECENT THUNDER CHANCES AGAIN WITH
DIURNAL HEATING WARRANTING -TSRA BUT VFR.
ELSEWHERE...CONVECTION CONTINUES THIS EVENING ACROSS MAINLY THE
MTNS/FOOTHILLS. MUCH OF THE PIEDMONT WILL BE STABILIZED BY TS
OUTFLOW WITH UPSTREAM ACTIVITY LIKELY TO DIMINISH TOO QUICKLY WITH
LOSS OF HEATING TO HAVE EFFECTS. OVERNIGHT FROPA WILL BRING BACK TS
OR SHRA CHANCES. HANDLED THIS WITH VCTS OR TEMPOS AS APPROPRIATE.
PLENTY OF MOISTURE TO THINK RESTRICTIVE CIGS WILL DEVELOP BEHIND THE
FRONT AND PERSIST THRU DAYBREAK. DIURNAL CU WILL QUICKLY GROW IN
UNSTABLE ATMOSPHERE BY LATE MORNING. CU BASES EXPECTED TO BE WELL
WITHIN VFR TERRITORY...WITH SOME LOW TS CHANCES ALSO THROUGH PEAK
HEATING.
OUTLOOK...RESTRICTIONS POSSIBLE WITH LINGERING MOISTURE OVERNIGHT
THU NIGHT AND FRI MORNING. GENERALLY VFR WEATHER FRIDAY AND SATURDAY.
CONFIDENCE TABLE...
00-06Z 06-12Z 12-18Z 18-24Z
KCLT MED 60% MED 78% MED 79% HIGH 96%
KGSP LOW 57% MED 65% MED 73% HIGH 100%
KAVL HIGH 80% HIGH 94% HIGH 94% HIGH 100%
KHKY LOW 58% MED 60% HIGH 82% HIGH 100%
KGMU LOW 57% MED 68% HIGH 91% HIGH 100%
KAND MED 65% HIGH 86% HIGH 91% 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...SBK
NEAR TERM...CDG/PM/WIMBERLEY
SHORT TERM...TS
LONG TERM...SBK
AVIATION...CDG/WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
755 PM EDT WED MAY 22 2013
.SYNOPSIS...
AN APPROACHING UPPER LEVEL TROUGH WILL CONTINUE TO INFLUENCE THE
REGION THROUGH THURSDAY. A COLD FRONT MOVES THROUGH THE AREA
THURSDAY NIGHT...BEFORE A COOLER AND DRIER AIRMASS SETTLES IN FOR
THE WEEKEND AND MODIFIES THROUGH THE EARLY PART OF NEXT WEEK.
&&
.NEAR TERM /THROUGH THURSDAY/...
AS OF 430 PM...INCREASED POPS ACROSS THE UPSTATE OF SOUTH CAROLINA
AND THE PIEDMONT OF NORTH CAROLINA DURING THE OVERNIGHT HOURS AS
SHORT TERM CONVECTIVE MODEL GUIDANCE CONTINUES WIDESPREAD CONVECTION
ACROSS THE ABOVE MENTIONED REGIONS THROUGH 10Z THURSDAY. ALSO
TOUCHED UP SKY AND TEMP GRIDS. OTHERWISE...NO OTHER CHANGES WERE
MADE.
REMAINDER OF PREVIOUS DISCUSSION...
AS OF MID AFTERNOON...A BROKEN BAND OF SHOWERS AND THUNDERSTORMS WAS
LOCATED JUST EAST OF THE BLUE RIDGE IN NC FROM I-40 NEWD...WITH
OTHER STORMS POPPING UP ACROSS THE HIGHER TERRAIN AIDED BY
DIFFERENTIAL HEATING. EXPECT THE STORMS TO BECOME MORE NUMEROUS
ACROSS THE MTNS THROUGH LATE AFTERNOON...WITH THAT CONVECTION MOVING
EAST OVER THE FOOTHILLS AND PIEDMONT INTO THE EVENING. POP HAS BEEN
ADJUSTED ACCORDINGLY. SOME OF THESE STORMS WILL PRODUCE LARGE HAIL
AND DAMAGING WIND GUSTS. HIGH TEMPS STILL LOOK OKAY.
FOR TONIGHT...THE CONVECTION ALLOWING MODELS SUGGEST THAT ANOTHER
ROUND OF STORMS WILL FIRE TO THE WEST AND THEN MOVE EAST INTO THE
FCST AREA IN THE EARLY EVENING. THE HRRR AND 4KM WRF PAINT A SIMILAR
PICTURE WITH NUMEROUS STORMS OVER THE WESTERN HALF OF THE FCST AREA
THROUGH MID TO LATE EVENING. A SHORT WAVE MOVING AROUND THE UPPER
TROF...COMBINED WITH SOME UPPER DIVERGENCE...SHOULD PROVIDE THE
NECESSARY SUPPORT FOR THIS CONVECTION TO THRIVE. WITH THAT IN
MIND...THE POP WAS RAISED TO LIKELY OVER THE WESTERN HALF. AFTER
SOME LOSS OF HEATING...THE STORMS SHOULD BECOME A BIT LESS NUMEROUS
OVER THE NC PIEDMONT. AT THAT POINT...THE POP WAS KEPT BELOW 50 PCT
ONLY BECAUSE OF SOME UNCERTAINTY GIVEN BY THE CONVECTION HAVING NOT
YET DEVELOPED AS OF 18Z. MIN TEMPS SHOULD REMAIN MILD.
THE COLD FRONT WILL MOVE IN FROM THE WEST ON THURSDAY...MOST LIKELY
OVER THE MTNS IN THE MORNING AND THEN MOVING OUT OVER THE FOOTHILLS
IN THE AFTERNOON. NEW CONVECTION SHOULD DEVELOP ALONG THE FRONT
MAINLY OVER THE PIEDMONT IN THE AFTERNOON. THIS IS TRICKY BECAUSE OF
THE LIKELIHOOD OF WIDESPREAD DEBRIS CLOUDINESS INTO THE EARLY
AFTERNOON THAT WOULD LIMIT CONVECTION. THINK THE MTNS STAND A CHANCE
BECAUSE OF THE FRONT EARLY IN THE DAY. THE UPSTATE AND NE GEORGIA
HAS THE LEAST FAVORABLE ENVIRONMENT...SO A 20 PCT POP WAS KEPT. THE
PIEDMONT HAS A BETTER CHANCE AHEAD OF THE FRONT SO A LIKELY POP WAS
CARRIED OVER THE EASTERN ZONES FOR A TIME. SEVERE STORMS ARE
POSSIBLE...BUT MORE LIKELY TO THE EAST OF I-77. HIGH TEMPS WILL BE
AFEW DEGREES COOLER.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 230 PM WEDNESDAY...A SURFACE COLD FRONT SHOULD BE LOCATED NEAR
THE EDGE OF OUR WESTERN NORTH CAROLINA PIEDMONT EARLY THURSDAY
EVENING. THIS LINES UP WELL WITH THE SHORT TERM SUITE OF MODELS...
AND LINES UP WITH WITH AN AXIS OF DPVA WHICH SHOULD BE CROSSING THAT
REGION LATE IN THE DAY/EARLY EVENING. CONVECTIVE ALLOWING MODELS
ALSO DEPICT THIS TREND AND IS SUPPORTED BY INSTABILITY LINGERING
ACROSS THAT AREA. AS A RESULT WE WILL HAVE A CORRIDOR OF LOWER
CHANCE POPS IN OUR EASTERN FORECAST AREA (FA) UNTIL AROUND DARK OR
SO.
A SECOND AREA OF PRECIPITATION FOR THURSDAY NIGHT WILL BE IN THE NC
MOUNTAINS WHERE ANOTHER LOBE OF ENERGY...EMBEDDED IN A SHARPENING H5
TROF...CROSSES THE AREA. WE WILL CARRY CHANCE POPS IN THE NC
MOUNTAINS THURSDAY NIGHT AND FRIDAY MORNING...IN A CONTINUALLY
DEEPENING FORCED UPPER AIR PATTERN. ALTHOUGH THE SHARPENING TROF
CROSSES ALL OF OUR REGION FRIDAY...THE ATMOSPHERE LOOKS TO DRY FOR
ANY PRECIPITATION.
MEANWHILE THE H85 ISALLOBARIC PATTERN WAS INDICATING SIGNIFICANT
CROSS CONTOURS OF THERMAL STRUCTURE AND HEIGHTS FRIDAY. THIS
SUGGESTS AT LEAST SIGNIFICANT COLD AIR ADVECTION (ESPECIALLY JUST
ABOVE THE SURFACE) AND MIXING DOWN. WE HAVE FOLLOWED BUFKIT
INFORMATION FOR WIND GUSTS FRIDAY...AND IN ALL LIKELIHOOD WE WILL
NEED SOME TYPE OF WIND HEADLINE FRIDAY FOR PART OF OUR FAA...
PARTICULARLY IN THE AFTERNOON.
HIGH PRESSURE WILL EDGE TOWARD THE REGION FRIDAY NIGHT...WHICH WILL
BRING A COOL/COLD NIGHT AROUND THE AREA. SOME MOUNTAIN LOCATIONS TO
DIP INTO THE 30S...BUT BELIEVE ENOUGH MIXING SHOULD PREVENT FROST
DUE TO THE LINGERING GRADIENT OF HIGH PRESSURE OFF TO THE NORTHWEST
AND LOW PRESSURE MOVING UP THE EASTERN SEABOARD. HOWEVER WE WILL
HAVE TO MONITOR TRENDS.
HIGH PRESSURE TO HOLD SWAY SATURDAY WITH A PLEASANT DAY ON
TAP.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 225 PM WEDNESDAY...RATHER GOOD AGREEMENT IS HAD IN THE UPPER
LEVEL OMEGA PATTERN OVER THE EXT RANGE. THE 12Z GFS IS A BIT OF AN
OUTLIER AND SHARPENS THE EAST COAST TROF AND SUBSEQUENT DEEP NW/LY
FLOW GRADIENT MORESO THAN THE OTHER OP MODELS...BUT NOT ENOUGH FOR A
SIGFNT LLVL RESPONSE. AT THE SFC...THERE ARE MAJOR DIFFERENCES
EVOLVING WITH THE SYNOPTIC PATTERN...THUS A LESS THAN AVG
CONFIDENCE IS HAD AS THE EXT RANGE PROGRESSES.
HIGH PRESSURE CONTINUES TO BUILD IN FROM THE NORTH SUN AND KEEPS
THINGS DRY. HIGH TEMPS WILL BE A LITTLE BELOW NORMAL WITH A
REINFORCING CP AIRMASS MIXING IN. THE LLVL FLOW BECOMES DEFINED
SW/LY MON AS THE ATL HIGH NUDGES IN. THIS WILL ALSO ENABLE A WARM
FRONT OR STATIONARY TO PERHAPS IMPINGE UPON THE REGION MON NIGHT
INTO TUE. THERE IS LOW CONFIDENCE IN THIS FEATURE...HOWEVER...AS THE
GFS KEEPS ANY FRONTOGENESIS WELL TO THE NORTH OF THE REGION WITH A
WEAK TROF BUILDING INTO THE SFC SE RIDGE...WHILE THE ECMWF HAS THE
WARM FRONT STALLING OUT ACROSS THE CWFA DURING THE DAY TUE INTO WED.
RIGHT NOW...POPS HAVE BEEN CONTINUED IN THE LOW END CHANCE RANGE MON
THROUGH TUE...AND A DRIER HPC BLEND WAS MAINTAINED FOR WED.
SOUNDINGS SHOW VERY LITTLE SBCAPE DEVELOPING MON AS THE UPPER FLOW
KEEPS A SUBSIDENCE INVERSION IN PLACE...HOWEVER A RELATIVE WEAKENING
ALOFT TUE SHOULD ENABLE THE DEVELOPMENT OF SOME ENHANCE CONVECTION
AND TSTMS. MAX TEMPS WILL WARM EACH DAY MON THROUGH THE PERIOD TO A
LITTLE ABOVE NORMAL IN GOOD SW/LY FLOW AND INSOLATION.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AT KCLT...PREVAILING VFR THIS EVENING BUT THERE REMAINS THE
POSSIBILITY OF RESTRICTIONS FROM THUNDERSTORMS. STABILIZING OUTFLOW
FROM UPSTREAM TS MAY PUT A STOP TO CONVECTION BUT ITS LEADING EDGE
COULD BE THE FOCUS FOR NEW DEVELOPMENT FOR A TIME TONIGHT. INCLUDED
A TEMPO THRU 04Z FOR MVFR TSRA...BUT WILL CLOSELY WATCH TRENDS OVER
NEXT COUPLE OF HOURS AND MAY BE ABLE TO REMOVE IT. PROFILES BECOME
INCREASINGLY MOIST OVERNIGHT AHEAD OF FRONTAL BOUNDARY. PER MODEL RH
FIELDS EXPECT A LOWERING TO SOLID MVFR LATE...WITH SUFFICIENT
ELEVATED INSTABILITY TO WARRANT ANOTHER TEMPO FOR TSRA. LULL IN
ACTIVITY EXPECTED NEAR DAYBREAK WITH LOW MVFR PERSISTING UNTIL
MIXING GETS UNDERWAY MID MORNING. DECENT THUNDER CHANCES AGAIN WITH
DIURNAL HEATING WARRANTING -TSRA BUT VFR.
ELSEWHERE...CONVECTION CONTINUES THIS EVENING ACROSS MAINLY THE
MTNS/FOOTHILLS. MUCH OF THE PIEDMONT WILL BE STABILIZED BY TS
OUTFLOW WITH UPSTREAM ACTIVITY LIKELY TO DIMINISH TOO QUICKLY WITH
LOSS OF HEATING TO HAVE EFFECTS. OVERNIGHT FROPA WILL BRING BACK TS
OR SHRA CHANCES. HANDLED THIS WITH VCTS OR TEMPOS AS APPROPRIATE.
PLENTY OF MOISTURE TO THINK RESTRICTIVE CIGS WILL DEVELOP BEHIND THE
FRONT AND PERSIST THRU DAYBREAK. DIURNAL CU WILL QUICKLY GROW IN
UNSTABLE ATMOSPHERE BY LATE MORNING. CU BASES EXPECTED TO BE WELL
WITHIN VFR TERRITORY...WITH SOME LOW TS CHANCES ALSO THROUGH PEAK
HEATING.
OUTLOOK...RESTRICTIONS POSSIBLE WITH LINGERING MOISTURE OVERNIGHT
THU NIGHT AND FRI MORNING. GENERALLY VFR WEATHER FRIDAY AND SATURDAY.
CONFIDENCE TABLE...
00-06Z 06-12Z 12-18Z 18-24Z
KCLT MED 60% MED 78% MED 79% HIGH 96%
KGSP LOW 57% MED 65% MED 73% HIGH 100%
KAVL HIGH 80% HIGH 94% HIGH 94% HIGH 100%
KHKY LOW 58% MED 60% HIGH 82% HIGH 100%
KGMU LOW 57% MED 68% HIGH 91% HIGH 100%
KAND MED 65% HIGH 86% HIGH 91% 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...SBK
NEAR TERM...CDG/PM/WIMBERLEY
SHORT TERM...TS
LONG TERM...SBK
AVIATION...CDG/WIMBERLEY
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1228 AM CDT TUE MAY 21 2013
.UPDATE...
SEE UPDATED AVIATION DISCUSSION BELOW.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH TUESDAY
AXIS OF SHOWERS HAS SHIFTED INTO THE EASTERN CWA THIS
AFTERNOON...WITH A BREAK FOR COUNTIES WEST OF ABERDEEN. THIS BREAK
WILL BE SHORT LIVED AS RADARS UPSTREAM IN NORTH DAKOTA ARE QUITE
ACTIVE...WITH WIDESPREAD LIGHT/MODERATE RAINFALL. HRRR AND RUC
GUIDANCE PIVOTS THIS MOISTURE BACK OVER THE CWA THIS EVENING AND
PERSISTS WELL INTO TUESDAY. MOST OF THE AREA HAS BEEN ABLE TO
HANDLE THE MOISTURE THUS FAR...WITH A FEW SPOTS REPORTING RISING
WATER IN DITCHES/CREEKS BUT NOT MUCH IMPACT OTHERWISE. SREF
PROBABILITIES FOR GREATER THEN A QUARTER INCH ARE HIGHEST ACROSS
OUR NORTHERN MISSOURI RIVER COUNTIES...AN AREA THAT HAS NOT
RECEIVED MUCH DROUGHT RELIEF THIS SPRING...AND THUS THINK THAT AREA
CAN HANDLE THE ADDITIONAL 1/2 INCH OF RAIN. SOILS FARTHER SOUTH
AND EAST MAY BE LESS FORGIVING AND WILL NEED TO BE MONITORED THIS
EVENING/OVERNIGHT FOR WATER ISSUES.
AS THE STACKED LOW CONTINUES TO DRIFT EAST TUESDAY...LIFT WEAKENS
WITH SOME DRIER AIR ENTRAINMENT RESULTING IN LOWER PROBABILITY FOR
PRECIPITATION AND QPF. TEMPERATURES THIS PERIOD WILL REMAIN BELOW
NORMAL AND CHANGE LITTLE THANKS TO CLOUD COVER.
.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
AS THE PERIOD OPENS...A DECAYING UPPER LOW CIRCULATION OVER THE
REGION WILL BE SLOWLY DRIFTING SOUTHEAST OUT OF THE AREA.
CONTINUED WRAP-AROUND MOISTURE COMBINED WITH SOME WEAK TROWALESQUE
FORCING/LIFT WILL KEEP POPS/RAIN SHOWERS MENTION GOING TUESDAY
NIGHT INTO WEDNESDAY AS THIS LOW PULLS AWAY FROM THE REGION.
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT SHOULD BE DRY FORECAST
PERIODS WHILE A TRANSIENT HIGH-AMPLITUDE LONGWAVE HIGH PRESSURE
RIDGE WORKS THROUGH THE REGION.
BY FRIDAY...LOW LEVEL RETURN FLOW IS IN FULL SWING AND POPS FOR
SHOWERS AND THUNDERSTORMS MAKE THEIR RETURN TO THE FORECAST AS MID
AND UPPER LEVEL FLOW TAKES ON A RATHER PROLONGED PERIOD OF SWRLY
FLOW...THAT IS CURRENTLY PROGGED BY THE GFS AND ECMWF TO LAST
RIGHT INTO MONDAY.
THE COOLEST TEMPS DURING THE PERIOD LOOK TO BE TUESDAY NIGHT AND
WEDNESDAY BEFORE THE WARMING TREND ENSUES. BY THE
WEEKEND...TEMPERATURES SHOULD BE MUCH CLOSER TO CLIMO NORMAL.
&&
.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
AN AREA OF RAIN WILL CONTINUE TO SPIN OVER MUCH OF CENTRAL AND
NORTHEASTERN SOUTH DAKOTA OVERNIGHT AND THROUGH THE DAY TUESDAY.
CIGS AND VSBYS WILL VARY BETWEEN VFR AND MVFR LEVELS WITH THE
RAINFALL. BREEZY NORTHERLY WINDS OF 20 TO 30 MPH WILL AFFECT KPIR
AND KMBG.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...WISE
SHORT TERM...CONNELLY
LONG TERM...DORN
AVIATION...WISE
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
715 AM CDT TUE MAY 21 2013
.MESOSCALE UPDATE...
CURRENT RADAR IMAGERY SHOWS THAT THE HRRR APPEARS TO BE WINNING
WITH ITS DEPICTION OF MULTIPLE ROUNDS OF STORMS MOVING ACROSS THE
MID STATE. INITIAL LINE OF STORMS CONTINUES TO COLLAPSE AS IT
MOVES EAST OF THE I-65 CORRIDOR...BUT A SECOND LINE IS APPROACHING
THE WESTERN CWA BORDER. A THIRD AND MUCH MORE INTENSE LINE OF
STORMS IS MOVING ACROSS EASTERN ARKANSAS TOWARDS THE MID STATE.
THUS APPEARS SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGHOUT
THE DAY AND EVENTUALLY SPREAD ACROSS THE ENTIRE CWA...AND HAVE
BUMPED UP POPS AND LOWERED HIGH TEMPS ACCORDINGLY. 12Z OHX
SOUNDING PRIOR TO THE INITIAL LINE OF STORMS HAD CONSIDERABLE
POTENTIAL INSTABILITY WITH AN LI OF -10 AND VERY STEEP LAPSE
RATES. THUS CANNOT RULE OUT SOME STRONG TO SEVERE STORMS WITH
THESE NEXT TWO LINES OF STORMS LATER THIS MORNING AND
AFTERNOON...WITH THE MAIN THREAT BEING DAMAGING WINDS.
SHAMBURGER
&&
.PREV DISCUSSION... /ISSUED 601 AM CDT TUE MAY 21 2013/
UPDATE...ADDED AVIATION SECTION FOR 12Z TAF`S.
AVIATION...LINE OF OVERNIGHT CONVECTION HAS STAYED TOGETHER AND
MOVED INTO MIDDLE TENNESSEE EARLY THIS MORNING, SO RAIN IS PART OF
THE INITIAL PERIOD OF THE TAF`S, ALONG WITH SOME FOG AT CSV. LOOK
FOR A REPRIEVE FROM THE WEATHER LATER THIS MORNING AND LASTING
THROUGH THE AFTERNOON, WITH A LONG STRETCH OF VFR WX. A COLD FRONT
APPROACHING FROM THE WEST WILL THEN BEGIN SPREADING ANOTHER ROUND
OF ACTIVE WEATHER ACROSS MIDDLE TENNESSEE THIS EVENING AND
OVERNIGHT, WITH THUNDERSTORMS POSSIBLE.
PREV DISCUSSION... /ISSUED 321 AM CDT TUE MAY 21 2013/
SHORT TERM...
RADAR IMAGERY THIS MORNING SHOWS AN EXTENSIVE LINE OF SHOWERS AND
THUNDERSTORMS FROM THE GREAT LAKES SOUTHWARD INTO WESTERN
TENNESSEE...WITH ACTIVITY NOW APPROACHING OUR WESTERN CWA BORDER.
ALTHOUGH MCS HAS SHOWN AN OVERALL WEAKENING TREND...SATELLITE
IMAGERY SHOWS NEW UPDRAFTS DEVELOPING ALONG LEADING EDGE OF COLD
POOL WITH CLOUD TOPS COOLING. LATEST SHORT TERM MODEL GUIDANCE
SUCH AS THE 4 KM WRF...HRRR...AND NSSL WRF ALL BRING ACTIVITY INTO
OUR WESTERN ZONES IN A FEW HOURS BEFORE DIMINISHING LATER THIS
MORNING...AND THUS WILL RAISE POPS SUBSTANTIALLY OVER GUIDANCE FOR
THE PRE-FIRST AND FIRST PERIOD OF THE FORECAST. ALSO BUMPED UP
CLOUD COVER AND WENT SIGNIFICANTLY BELOW MOS GUIDANCE HIGHS FOR
TODAY DUE TO ANTICIPATED CLOUDS/PRECIP. NO SEVERE WEATHER IS
EXPECTED WITH THESE STORMS THIS MORNING ALTHOUGH SOME GUSTY WINDS
MAY OCCUR. CHANGES TO THE FORECAST ARE LIKELY DEPENDING ON HOW
CURRENT ACTIVITY EVOLVES.
MODELS INDICATE A SHARP SHORTWAVE TROUGH CURRENTLY SEEN ON WATER
VAPOR IMAGERY OVER NEW MEXICO WILL SWING THROUGH THE SOUTHERN
PLAINS TODAY...THEN ACROSS THE OHIO VALLEY AND NORTHWEST PART OF
OUR FORECAST AREA TUESDAY NIGHT. EXPECTING NUMEROUS SHOWERS AND
THUNDERSTORMS TO DEVELOP TO OUR WEST ACROSS ARKANSAS TUESDAY
AFTERNOON...THEN SPREAD INTO WESTERN TENNESSEE AND THE NORTHWEST
MID STATE TUESDAY EVENING AND ESPECIALLY AFTER MIDNIGHT TUESDAY
NIGHT. SPC HAS THE NORTHWEST PART OF THE FORECAST AREA IN A SLIGHT
RISK FOR SEVERE STORMS TUESDAY NIGHT...GENERALLY ALONG AND WEST OF
A LINE FROM WAYNESBORO TO SPRINGFIELD. APPEARS BEST CHANCE FOR ANY
SEVERE WEATHER IN OUR CWA WILL BE IN THE 03Z-12Z TIMEFRAME AS
SHORTWAVE TROUGH AXIS MOVES ACROSS...BUT NOCTURNAL TIMING MAY
REDUCE THE SEVERE POTENTIAL. FORECAST SOUNDINGS DO SHOW
SUBSTANTIAL MLCAPE AND MODERATE DEEP LAYER SHEAR TUESDAY
NIGHT...WHICH SUGGESTS POTENTIAL FOR A LOWER END THREAT OF SOME
DAMAGING WINDS OR LARGE HAIL. HOWEVER...ANY TORNADO THREAT
APPEARS VERY LOW IN OUR FORECAST AREA. MUCH BETTER CHANCES FOR
SEVERE STORMS WILL EXIST TO OUR WEST ACROSS ARKANSAS TUESDAY
AFTERNOON/EVENING. NOTE THAT MUCH OF THE CWA EAST OF I-65 WILL
REMAIN DRY DURING THIS TIME PERIOD.
AS SHORTWAVE EXITS THE REGION ON WEDNESDAY...A COLD FRONT WILL
PUSH EASTWARD ACROSS THE MID STATE WITH ADDITIONAL SHOWERS AND
STORMS ANTICIPATED THROUGH THE DAY. ACTIVITY WILL END FROM WEST TO
EAST WEDNESDAY NIGHT AS MUCH COOLER AND DRIER AIR FILTERS IN.
BELOW NORMAL TEMPERATURES ARE THEN ANTICIPATED OVER THE WEEKEND
AS NORTHWEST FLOW BUILDS IN ALOFT...WITH LOWS IN THE 40S/50S AND
HIGHS IN THE 70S. MID STATE LOOKS TO STAY IN A NORTHWEST FLOW
PATTERN THROUGH THE REMAINDER OF THE FORECAST PERIOD WITH A
GRADUAL WARMING TREND...BUT MAJOR DIFFERENCES EXIST BETWEEN THE
GFS/ECMWF NEXT WEEK REGARDING PRECIP CHANCES WITH GFS COMPLETELY
DRY BUT ECMWF SHOWING DAILY POPS. HAVE TRENDED TOWARDS THE GFS
FOR NOW BUT NOTE THAT EXTENDED FORECAST IS LOW CONFIDENCE.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
541 AM CDT TUE MAY 21 2013
.MESOSCALE UPDATE...
RADAR INDICATES LINE OF THUNDERSTORMS CURRENTLY STRETCHES FROM
SPRINGFIELD TO LINDEN AND CONTINUES TO WEAKEN AS IT OUTRUNS WHAT
LITTLE INSTABILITY REMAINS. HOWEVER...LINE SHOULD REACH THE I-65
CORRIDOR AND NASHVILLE METRO AREA SOON WITH LIGHT TO MODERATE RAIN
AND A FEW LIGHTNING STRIKES EXPECTED. THE LINE SHOULD COLLAPSE AS
IT CONTINUES FURTHER EAST AND RUNS INTO THE UPPER LEVEL RIDGE IN
PLACE. MEANWHILE...TWO ADDITIONAL LINES OF STORMS ARE CURRENTLY
ONGOING ACROSS ARKANSAS...AND LATEST HRRR RUNS INDICATE THESE
STORMS MAY ALSO REACH THE MID STATE LATER THIS MORNING. VERY
UNCERTAIN ON IF THIS WILL OCCUR...BUT IF IT DOES POPS WOULD NEED
TO BE RAISED AND HIGH TEMPS LOWERED SUBSTANTIALLY DUE TO THE
CLOUD COVER/PRECIP. FOR NOW HAVE BUMPED UP POPS FOR THE WESTERN
TWO- THIRDS OF THE CWA FOR THE MORNING PERIOD...AND WILL TAKE A
WAIT AND SEE APPROACH ON THE ACTIVITY TO OUR WEST BEFORE CHANGING
GRIDS/ZONES FURTHER. SHOULD CONVECTION CONTINUE TO AFFECT THE MID
STATE THROUGHOUT THE DAY AS THE HRRR SUGGESTS...THIS WOULD LIKELY
REDUCE THE SEVERE WEATHER THREAT TUESDAY NIGHT.
SHAMBURGER
&&
.PREV DISCUSSION... /ISSUED 425 AM CDT TUE MAY 21 2013/
MESOSCALE UPDATE...
LINE OF THUNDERSTORMS HAS ENTERED STEWART COUNTY WITH WIND GUSTS
ALONG LEADING EDGE UP TO 50 MPH POSSIBLE PER HPX BASE VELOCITY
RADAR DATA. ALSO CANNOT RULE OUT SOME SMALL HAIL AS UPDRAFTS
REGENERATE ALONG THE FRONT SIDE OF COLD POOL AS LINE RACES
EASTWARD AT UP TO 60 MPH. SPC MESOANALYSIS SHOWS INSTABILITY AXIS
OF UP TO 1000 J/KG ACROSS NORTHWEST ZONES...DECREASING TO 500 J/KG
NEAR I-65 AND TO NEAR ZERO ON THE PLATEAU. THUS EXPECT LINE OF
STORMS TO CONTINUE GRADUALLY WEAKENING AS IT MOVES FURTHER
EASTWARD...BUT WILL CONTINUE TO CLOSELY MONITOR.
SHAMBURGER
PREV DISCUSSION... /ISSUED 321 AM CDT TUE MAY 21 2013/
SHORT TERM...
RADAR IMAGERY THIS MORNING SHOWS AN EXTENSIVE LINE OF SHOWERS AND
THUNDERSTORMS FROM THE GREAT LAKES SOUTHWARD INTO WESTERN
TENNESSEE...WITH ACTIVITY NOW APPROACHING OUR WESTERN CWA BORDER.
ALTHOUGH MCS HAS SHOWN AN OVERALL WEAKENING TREND...SATELLITE
IMAGERY SHOWS NEW UPDRAFTS DEVELOPING ALONG LEADING EDGE OF COLD
POOL WITH CLOUD TOPS COOLING. LATEST SHORT TERM MODEL GUIDANCE
SUCH AS THE 4 KM WRF...HRRR...AND NSSL WRF ALL BRING ACTIVITY INTO
OUR WESTERN ZONES IN A FEW HOURS BEFORE DIMINISHING LATER THIS
MORNING...AND THUS WILL RAISE POPS SUBSTANTIALLY OVER GUIDANCE FOR
THE PRE-FIRST AND FIRST PERIOD OF THE FORECAST. ALSO BUMPED UP
CLOUD COVER AND WENT SIGNIFICANTLY BELOW MOS GUIDANCE HIGHS FOR
TODAY DUE TO ANTICIPATED CLOUDS/PRECIP. NO SEVERE WEATHER IS
EXPECTED WITH THESE STORMS THIS MORNING ALTHOUGH SOME GUSTY WINDS
MAY OCCUR. CHANGES TO THE FORECAST ARE LIKELY DEPENDING ON HOW
CURRENT ACTIVITY EVOLVES.
MODELS INDICATE A SHARP SHORTWAVE TROUGH CURRENTLY SEEN ON WATER
VAPOR IMAGERY OVER NEW MEXICO WILL SWING THROUGH THE SOUTHERN
PLAINS TODAY...THEN ACROSS THE OHIO VALLEY AND NORTHWEST PART OF
OUR FORECAST AREA TUESDAY NIGHT. EXPECTING NUMEROUS SHOWERS AND
THUNDERSTORMS TO DEVELOP TO OUR WEST ACROSS ARKANSAS TUESDAY
AFTERNOON...THEN SPREAD INTO WESTERN TENNESSEE AND THE NORTHWEST
MID STATE TUESDAY EVENING AND ESPECIALLY AFTER MIDNIGHT TUESDAY
NIGHT. SPC HAS THE NORTHWEST PART OF THE FORECAST AREA IN A SLIGHT
RISK FOR SEVERE STORMS TUESDAY NIGHT...GENERALLY ALONG AND WEST OF
A LINE FROM WAYNESBORO TO SPRINGFIELD. APPEARS BEST CHANCE FOR ANY
SEVERE WEATHER IN OUR CWA WILL BE IN THE 03Z-12Z TIMEFRAME AS
SHORTWAVE TROUGH AXIS MOVES ACROSS...BUT NOCTURNAL TIMING MAY
REDUCE THE SEVERE POTENTIAL. FORECAST SOUNDINGS DO SHOW
SUBSTANTIAL MLCAPE AND MODERATE DEEP LAYER SHEAR TUESDAY
NIGHT...WHICH SUGGESTS POTENTIAL FOR A LOWER END THREAT OF SOME
DAMAGING WINDS OR LARGE HAIL. HOWEVER...ANY TORNADO THREAT
APPEARS VERY LOW IN OUR FORECAST AREA. MUCH BETTER CHANCES FOR
SEVERE STORMS WILL EXIST TO OUR WEST ACROSS ARKANSAS TUESDAY
AFTERNOON/EVENING. NOTE THAT MUCH OF THE CWA EAST OF I-65 WILL
REMAIN DRY DURING THIS TIME PERIOD.
AS SHORTWAVE EXITS THE REGION ON WEDNESDAY...A COLD FRONT WILL
PUSH EASTWARD ACROSS THE MID STATE WITH ADDITIONAL SHOWERS AND
STORMS ANTICIPATED THROUGH THE DAY. ACTIVITY WILL END FROM WEST TO
EAST WEDNESDAY NIGHT AS MUCH COOLER AND DRIER AIR FILTERS IN.
BELOW NORMAL TEMPERATURES ARE THEN ANTICIPATED OVER THE WEEKEND
AS NORTHWEST FLOW BUILDS IN ALOFT...WITH LOWS IN THE 40S/50S AND
HIGHS IN THE 70S. MID STATE LOOKS TO STAY IN A NORTHWEST FLOW
PATTERN THROUGH THE REMAINDER OF THE FORECAST PERIOD WITH A
GRADUAL WARMING TREND...BUT MAJOR DIFFERENCES EXIST BETWEEN THE
GFS/ECMWF NEXT WEEK REGARDING PRECIP CHANCES WITH GFS COMPLETELY
DRY BUT ECMWF SHOWING DAILY POPS. HAVE TRENDED TOWARDS THE GFS
FOR NOW BUT NOTE THAT EXTENDED FORECAST IS LOW CONFIDENCE.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1202 AM CDT TUE MAY 21 2013
.UPDATE...
&&
.AVIATION...
06Z TAFS...SOME MVFR BR OR PERHAPS PATCHY STRATUS IS POSSIBLE
OVERNIGHT. STORMS OVER AR/MO WILL APPROACH FROM THE WEST...BUT
THINK THEY WILL MOSTLY DIMINISH BEFORE REACHING MID TN. S WINDS
WILL BECOME SOMEWHAT GUSTY ON TUESDAY...TO 20KT AT
TIMES...ESPECIALLY FOR CKV. THE CHANCE FOR TSRA WILL INCREASE LATE
IN THE TAF PERIOD WITH AN APPROACHING DISTURBANCE. SCT
COVERAGE...SO JUST INCLUDING A VCTS FOR CKV/BNA.
13
&&
.PREV DISCUSSION... /ISSUED 854 PM CDT MON MAY 20 2013/
UPDATE...
HAVE UPDATED THE SUITE OF FORECAST PRODUCTS TO REFLECT CLEAR SKIES
ACROSS THE MID STATE THRU THE EVENING HRS...WITH A GENERAL INCREASE
OF CLOUDINESS WEST TO EAST ACROSS THE MID STATE AFTER MIDNIGHT. HAVE
ALSO MENTIONED PATCHY FOG AFTER MIDNIGHT PLATEAU PER CONTINUED LOW
LEVEL MOISTURE POOLING POTENTIAL. WITH SOME UNCERTAINTIES CONCERNING
ACTUAL CLOUD COVERAGE LATE...WILL CONTINUE TO GO CLOSE TO CURRENT
FORECAST REASONING ON OVERNIGHT LOWS.
PREV DISCUSSION... /ISSUED 324 PM CDT MON MAY 20 2013/
AFTERNOON CU DEVELOPMENT IS WIDESPREAD ACROSS THE MID STATE THIS
AFTERNOON AS DEWPOINTS HAVE CONTINUED TO RISE. MID LEVEL CAP IS
RATHER STRONG ACCORDING TO THE 12Z SOUNDING FROM THIS MORNING. THE
HIGHER DEWPOINTS HAVE ACTED TO LOWER CONVECTIVE TEMPS BUT CURRENT
TEMPS ARE STRUGGLING TO RISE GIVEN THE EXTRA CLOUD COVER.
FOR TONIGHT`S FORECAST...WILL INCLUDE A 20 POP BUT ONLY FOR THE
NW. THIS IS IN LINE WITH THE HRRR REFLECTIVITY FCST WHICH SHOWS
LITTLE IF ANY DEVELOPMENT. OVERALL...IT JUST APPEARS THAT THERE IS
TOO MUCH VERTICAL DRYNESS IN PLACE.
A SLIGHT CHANCE OF SHOWERS AND TSTMS WILL BE IN THE FCST AGAIN FOR
TUESDAY. MOISTURE LEVELS SHOULD BE HIGHER AND WE DO SEE MORE 18Z CAP
EROSION WITH THE GFS MODEL. THE INCREASE IN MOISTURE WILL BE AIDED
BY AN APPROACHING FRONTAL BOUNDARY WHICH WILL IMPACT THE AREA LATE
TUESDAY NIGHT AND INTO WEDNESDAY. AT THAT TIME...A SLIGHT RISK OF
SEVERE WEATHER IS IN THE FCST FOR OUR NW COUNTIES. BEST OMEGA
FORCING APPEARS TO BE AROUND 06Z WEDNESDAY ACROSS WESTERN TN.
BUT...THERE COULD BE A FEW STRONGER CELLS OVER THAT SAME AREA
EARLIER ON TUES AFTERNOON. STORM MOTION SHOULD RUN FROM SW TO NE.
SHOWERS AND TSTMS TO PERSIST INTO WEDNESDAY. ITS IMPORTANT TO NOTE
HOWEVER THAT OVERALL POPS WITH THIS SYSTEM ARE NOT DRASTICALLY HIGH.
IN FACT...MODELS NOT LEANING TOWARD DEEP MOISTURE WITH A WIDESPREAD
AREA OF RAIN OCCURRING. NEVERTHELESS...POPS IN THE 40-60 PERCENT
RANGE WILL BE INCLUDED FOR TUESDAY NT INTO WEDNESDAY. AFTER A FEW
LINGERING SHOWERS ON THURSDAY ACROSS THE PLATEAU...CLEARING WILL
OCCUR WITH DRIER AIR MOVING IN.
FOR THE NEAR TERM TEMPS...WILL AGAIN UNDERCUT THE HIGH TEMPS FOR
TUESDAY AND WEDNESDAY. OVERNIGHT LOWS FROM THE GUIDANCE APPEARS
REASONABLE.
IN THE EXT FCST...NICE LATE MAY CONDITIONS ARE ON TAP FOLLOWING THE
FROPA WHICH WAS MENTIONED IN THE SHORT TERM TIME FRAME.
THUS...SUNSHINE TO RETURN IN EARNEST FOR FRIDAY AND INTO THE
WEEKEND. THERMAL TROUGHING WILL BE SLOW TO GIVE WAY AND
THUS...MOSTLY SUNNY SKIES WITH BELOW NORMAL TEMPS AND LOWER
HUMIDITY LEVELS WILL PREVAIL THU THROUGH SAT. SUNDAY AND MONDAY...UPPER
RIDGING AND HEIGHT RISES WILL BE ON TAP. THIS WILL EQUATE TO HIGH
TEMPS BACK UP INTO THE 80S. BUT...STILL NOT SEEING ANY APPRECIABLE
PRECIP CHANCES THROUGH MONDAY.
21
&&
.OHX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
701 PM EDT TUE MAY 21 2013
.SYNOPSIS...
AN UPPER LEVEL AREA OF LOW PRESSURE WILL DRIFT EAST AND OFFSHORE
OVERNIGHT. A LARGE LOW PRESSURE SYSTEM WILL TRACK FROM THE
CENTRAL PLAINS INTO THE GREAT LAKES BY THURSDAY. THIS SYSTEM WILL
PUSH A COLD FRONT THROUGH THE AREA THURSDAY...FOLLOWED BY HIGH
PRESSURE ON FRIDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 310 PM EDT TUESDAY...
SATELLITE LOOP SHOWED SCATTERED CU DEVELOPING THIS AFTERNOON
ESPECIALLY ACROSS THE HIGHER TERRAIN. REGIONAL WSR-88D LOOP
DISPLAYED ISOLATED CONVECTION FORMING JUST SOUTHEAST OF CWA ACROSS
EASTERN PORTIONS OF VIRGINIA AND NORTH CAROLINA IN THE MOIST AND
UNSTABLE AIR. RNK WRF ARW AND RUC INDICATED THAT THE BEST CHANCE
FOR THUNDERSTORMS THIS AFTERNOON INTO TONIGHT WILL OCCUR ALONG THE
SOUTHERN BLUE RIDGE MOUNTAINS. THE NAM AND GFS FOCUS ON CONVECTION
THIS EVENING INTO TONIGHT IN THE WEST AND NORTHWEST. INCREASED POPS
THIS EVENING IN THE NORTHWEST ALLOWING FOR MENTION OF LIKELY FOR
SOUTHEAST WEST VIRGINIA WITH BEST SFC MOISTURE CONVERGENCE AND MID
LVL OMEGA FIELDS. SOME OF THE STORMS TONIGHT COULD CONTAIN HEAVY
DOWNPOURS...HAIL AND GUSTY WINDS. WITH THE LOSS OF SOLAR
HEATING...CONVECTION WILL WEAKEN AND TAPER OFF AFTER MIDNIGHT. WENT
WITH LOW TEMPERATURES CLOSE TO MILD ADJMAV WITH VALUES FROM THE MID
50S IN THE MOUNTAINS TO THE MID 60S IN THE SOUTHEAST. WARM AND HUMID
CONDITIONS CONTINUE ON WEDNESDAY IN THE SOUTHERLY FLOW OUT AHEAD OF
THE APPROACHING COLD FRONT AND UPPER TROUGH. INCREASED POPS FROM
WEST TO EAST ON WEDNESDAY...WITH HIGHEST POPS ALONG WESTERN
MOUNTAINS. THE SWODY2 (DAY TWO CONVECTIVE OUTLOOK) HAS THE SLIGHT
RISK JUST TO OUR WEST ON WEDNESDAY. PLAYED HIGHS TEMPERATURES COOLER
ON WEDNESDAY WITH READINGS FROM THE MID 70S IN THE MOUNTAINS TO
THE MID 80S IN THE SOUTHEAST.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 255 PM EDT TUESDAY...
HAVE A COUPLE DAYS MORE OF HUMID WEATHER BEFORE FRONT SWINGS ACROSS
THURSDAY AND BRINGS A RETURN TO LOWER DEWPOINTS.
UNTIL THEN...NO MAJOR CHANGES TO THE FORECAST. WEDNESDAY NIGHT A
PIECE OF SHORTWAVE ENERGY ARRIVES ACROSS THE CENTRAL APPALACHIANS
WHICH CREATES AN AREA OF SHOWERS AND STORMS...MAINLY AFFECTING THE
WRN EDGE OF THE FORECAST AREA. THE BETTER PUSH OF THE FRONT ON
THURSDAY COMBINED WITH BETTER UPPER SUPPORT SHOULD BRING SOME
ENHANCED THREAT OF SHOWERS AND STORMS. TIMING OF THIS FRONT DOES
VARY SOMEWHAT FROM THE MODELS BUT ENOUGH AGREEMENT TO HAVE HIGH
CHANCE TO LIKLEY IN THE AREA THURSDAY. TIMING ALSO GIVES ISSUES TO
SVR THREAT. ATTM...EXPECT A LINE OF SHRA/TSRA TO BE IN THE MTNS IN
THE MORNING AND MOVING INTO THE PIEDMONT BY EARLY AFTERNOON. NOT
SEEING A LOT OF HEATING AS CLOUDS WILL BE GENEROUSLY SPREAD. ONE
AREA WITH THE BETTER INSOLATION COULD BE SOUTHSIDE VA/NW NC
PIEDMONT. AT THIS TIME...THE STORM PREDICTION CENTER HAS A 5 PERCENT
THREAT OF SVR WX MAINLY OVER THE PIEDMONT AND TIDEWATER AREAS OF
VA/NC.
THE FRONT WILL BE EAST OF THE AREA GOING INTO THURSDAY EVENING WITH
LINGERING SHORTWAVE INDUCED SHOWERS ACROSS THE MTNS OVERNIGHT. THE
MAIN SHORTWAVE SHIFTS EAST BY 12Z FRIDAY WITH DRIER AND COOLER AIR
ARRIVING. HIGHS FRIDAY WILL RANGE FROM THE LOWER TO MID 60S WEST TO
THE LOWER TO MID 70S EAST.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 130 PM EDT TUESDAY
FOR THE LONG RANGE FORECAST...THE MODELS KEEP A TROUGH IN PLACE
EARLY ON AND THEN GO MORE TOWARD A ZONAL TO RIDGE CONFIGURATION BY
THE END OF THE PERIOD.
WE SHOULD BE MAINLY DRY AS SFC HIGH BUILDS ACROSS THIS WEEKEND...SO
WEEKEND HOLIDAY PLANS ARE LOOKING GOOD FOR OUTDOOR ACTIVITIES AT
LEAST SATURDAY...AS THE LATEST ECMWF SHOWS ANOTHER WEAK SHORTWAVE
PUSHING ACROSS BY SUNDAY AND MAY BRING SOME SHOWERS ACROSS THE MTN
EMPIRE OF SW VA/INTO THE NC MTNS SUNDAY MORNING.
THE FLOW SWINGS MORE TOWARD THE SOUTHEAST SUNDAY EVENING INTO EARLY
NEXT WEEK WITH INCREASING HUMIDITY AND TEMPS. MODELS KEEPING MORE
ACTIVE WEATHER ACROSS THE OHIO VALLEY AND WEST...ALTHOUGH A WESTERLY
FLOW ALOFT CAN BRING STORMS WORKING EAST INTO THE MTNS. GIVEN WPC
SOLUTION OF THE ECMWF ENSEMBLE WILL KEEP THE FORECAST MORE ON THE
LOW CHANCE SIDE...BUT IF THE 12Z ECMWF VERIFIES WE COULD BE GETTING
SOAKED AGAIN MONDAY-WEDNESDAY.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
AS OF 645 PM EDT TUESDAY...
CONVECTION REMAINS QUITE ISOLATED ACROSS THE REGION THIS EVENING
WITH MOST COVERAGE OVER NW NORTH CAROLINA WELL SW OF THE TAF
SITES. MAIN CONCERN WILL BE WITH THE COMPLEX OF SHRA/TSRA
ASSOCIATED WITH AN OLD OUTFLOW HEADING NE OUT OF TN/KY DURING THE
NEXT FEW HOURS. LATEST SHORT RANGE GUIDANCE BRINGS SOME OF THIS AS
FAR EAST AS THE BLUE RIDGE AROUND MIDNIGHT BEFORE IT FADES. THUS
MAY HAVE A STORM OR SHRA AFFECT KBLF/KLWB DURING THE LATE EVENING
...WITH A BAND/CLUSTER OF SHRA/TSRA NEAR KBCB/KROA TOWARD
MIDNIGHT PENDING HOW FAR EAST THE PRECIP MAKES IT AFTER LOSS OF
HEATING AND LITTLE UPPER SUPPORT. GIVEN UNCERTAINTY WILL COVER
MAINLY WITH VCTS/VCSH FOR NOW AND AMEND IF STORMS DO INDEED GET
CLOSER.
OTHER CONCERN AGAIN WITH FOG LATE ESPCLY NEAR WHERE ANY RAINFALL
OCCURS GIVEN SUCH A MUGGY ENVIRONMENT. LATEST FORECAST RAOB
SOUNDINGS SUGGEST QUITE A BIT OF PATCHY FOG BUT LIKELY NOT AS
WIDESPREAD AS THIS MORNING EXCEPT IN SPOTS WHERE A SHRA PASSES.
REGARDLESS OF SHRA COVERAGE...APPEARS KLWB STILL HAS THE BEST
CHANCE TO DROP TO LIFR IN FOG WEDNESDAY MORNING WITH A PERIOD OF
IFR ELSW EXCLUDING KBLF/KROA WHERE ONLY BRIEF MVFR POSSIBLE AT
THIS TIME.
EXPECT A QUICK IMPROVEMENT TO CONDITIONS ON WEDNESDAY WITH THE
ONSET OF HEATING AND DECENT MIXING BY MID OR LATE MORNING. THINK
ALL SITES WILL BE VFR BY 15Z/11AM BUT WITH A BETTER SHOT AT
AFTERNOON CONVECTION DEVELOPING ESPCLY WEST OF THE BLUE RIDGE BY
20Z/4PM. WITH POTENTIAL TO SEE A BAND OF SHRA/TSRA DEVELOP WESTERN
SLOPES...INCLUDED A PREVAILING -TSRA THREAT AT BOTH KBLF/KLWB
WEDNESDAY AFTERNOON WHILE LEAVING ELSW VFR W/OUT CONVECTION UNDER
SCTD/BKN 5-6K FT CU FIELDS.
THE REGION STAYS IN A WARM...MOIST AIRMASS THROUGH THURSDAY AHEAD
OF A COLD FRONT THAT SHOULD PUSH THROUGH LATE IN THE DAY THURSDAY.
THIS WILL BRING THE BEST COVERAGE OF SHOWERS WEDNESDAY NIGHT INTO
THURSDAY ALONG WITH AREAS OF LATE NIGHT/EARLY MORNING FOG.
HIGH PRESSURE AND BETTER FLYING CONDITIONS ARE EXPECTED ON FRIDAY
AND THROUGH MUCH OF THE WEEKEND BEHIND THE FRONT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS/KK
SHORT TERM...WP
LONG TERM...WP
AVIATION...AMS/JH/KK
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
317 PM EDT TUE MAY 21 2013
.SYNOPSIS...
LOW PRESSURE ALOFT WILL DRIFT EAST INTO THE ATLANTIC THIS
EVENING INTO TONIGHT. A LARGE LOW PRESSURE SYSTEM WILL TRACK FROM
THE CENTRAL PLAINS INTO THE GREAT LAKES BY THURSDAY. THIS SYSTEM
WILL PUSH A COLD FRONT THROUGH THE AREA THURSDAY...FOLLOWED BY
HIGH PRESSURE ON FRIDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 310 PM EDT TUESDAY...
SATELLITE LOOP SHOWED SCATTERED CU DEVELOPING THIS AFTERNOON
ESPECIALLY ACROSS THE HIGHER TERRAIN. REGIONAL WSR-88D LOOP
DISPLAYED ISOLATED CONVECTION FORMING JUST SOUTHEAST OF CWA ACROSS
EASTERN PORTIONS OF VIRGINIA AND NORTH CAROLINA IN THE MOIST AND
UNSTABLE AIR. RNK WRF ARW AND RUC INDICATED THAT THE BEST CHANCE
FOR THUNDERSTORMS THIS AFTERNOON INTO TONIGHT WILL OCCUR ALONG THE
SOUTHERN BLUE RIDGE MOUNTAINS. THE NAM AND GFS FOCUS ON CONVECTION
THIS EVENING INTO TONIGHT IN THE WEST AND NORTHWEST. INCREASED POPS
THIS EVENING IN THE NORTHWEST ALLOWING FOR MENTION OF LIKELY FOR
SOUTHEAST WEST VIRGINIA WITH BEST SFC MOISTURE CONVERGENCE AND MID
LVL OMEGA FIELDS. SOME OF THE STORMS TONIGHT COULD CONTAIN HEAVY
DOWNPOURS...HAIL AND GUSTY WINDS. WITH THE LOSS OF SOLAR
HEATING...CONVECTION WILL WEAKEN AND TAPER OFF AFTER MIDNIGHT. WENT
WITH LOW TEMPERATURES CLOSE TO MILD ADJMAV WITH VALUES FROM THE MID
50S IN THE MOUNTAINS TO THE MID 60S IN THE SOUTHEAST. WARM AND HUMID
CONDITIONS CONTINUE ON WEDNESDAY IN THE SOUTHERLY FLOW OUT AHEAD OF
THE APPROACHING COLD FRONT AND UPPER TROUGH. INCREASED POPS FROM
WEST TO EAST ON WEDNESDAY...WITH HIGHEST POPS ALONG WESTERN
MOUNTAINS. THE SWODY2 (DAY TWO CONVECTIVE OUTLOOK) HAS THE SLIGHT
RISK JUST TO OUR WEST ON WEDNESDAY. PLAYED HIGHS TEMPERATURES COOLER
ON WEDNESDAY WITH READINGS FROM THE MID 70S IN THE MOUNTAINS TO
THE MID 80S IN THE SOUTHEAST.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 255 PM EDT TUESDAY...
HAVE A COUPLE DAYS MORE OF HUMID WEATHER BEFORE FRONT SWINGS ACROSS
THURSDAY AND BRINGS A RETURN TO LOWER DEWPOINTS.
UNTIL THEN...NO MAJOR CHANGES TO THE FORECAST. WEDNESDAY NIGHT A
PIECE OF SHORTWAVE ENERGY ARRIVES ACROSS THE CENTRAL APPALACHIANS
WHICH CREATES AN AREA OF SHOWERS AND STORMS...MAINLY AFFECTING THE
WRN EDGE OF THE FORECAST AREA. THE BETTER PUSH OF THE FRONT ON
THURSDAY COMBINED WITH BETTER UPPER SUPPORT SHOULD BRING SOME
ENHANCED THREAT OF SHOWERS AND STORMS. TIMING OF THIS FRONT DOES
VARY SOMEWHAT FROM THE MODELS BUT ENOUGH AGREEMENT TO HAVE HIGH
CHANCE TO LIKLEY IN THE AREA THURSDAY. TIMING ALSO GIVES ISSUES TO
SVR THREAT. ATTM...EXPECT A LINE OF SHRA/TSRA TO BE IN THE MTNS IN
THE MORNING AND MOVING INTO THE PIEDMONT BY EARLY AFTERNOON. NOT
SEEING A LOT OF HEATING AS CLOUDS WILL BE GENEROUSLY SPREAD. ONE
AREA WITH THE BETTER INSOLATION COULD BE SOUTHSIDE VA/NW NC
PIEDMONT. AT THIS TIME...THE STORM PREDICTION CENTER HAS A 5 PERCENT
THREAT OF SVR WX MAINLY OVER THE PIEDMONT AND TIDEWATER AREAS OF
VA/NC.
THE FRONT WILL BE EAST OF THE AREA GOING INTO THURSDAY EVENING WITH
LINGERING SHORTWAVE INDUCED SHOWERS ACROSS THE MTNS OVERNIGHT. THE
MAIN SHORTWAVE SHIFTS EAST BY 12Z FRIDAY WITH DRIER AND COOLER AIR
ARRIVING. HIGHS FRIDAY WILL RANGE FROM THE LOWER TO MID 60S WEST TO
THE LOWER TO MID 70S EAST.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 130 PM EDT TUESDAY
FOR THE LONG RANGE FORECAST...THE MODELS KEEP A TROUGH IN PLACE
EARLY ON AND THEN GO MORE TOWARD A ZONAL TO RIDGE CONFIGURATION BY
THE END OF THE PERIOD.
WE SHOULD BE MAINLY DRY AS SFC HIGH BUILDS ACROSS THIS WEEKEND...SO
WEEKEND HOLIDAY PLANS ARE LOOKING GOOD FOR OUTDOOR ACTIVITIES AT
LEAST SATURDAY...AS THE LATEST ECMWF SHOWS ANOTHER WEAK SHORTWAVE
PUSHING ACROSS BY SUNDAY AND MAY BRING SOME SHOWERS ACROSS THE MTN
EMPIRE OF SW VA/INTO THE NC MTNS SUNDAY MORNING.
THE FLOW SWINGS MORE TOWARD THE SOUTHEAST SUNDAY EVENING INTO EARLY
NEXT WEEK WITH INCREASING HUMIDITY AND TEMPS. MODELS KEEPING MORE
ACTIVE WEATHER ACROSS THE OHIO VALLEY AND WEST...ALTHOUGH A WESTERLY
FLOW ALOFT CAN BRING STORMS WORKING EAST INTO THE MTNS. GIVEN WPC
SOLUTION OF THE ECMWF ENSEMBLE WILL KEEP THE FORECAST MORE ON THE
LOW CHANCE SIDE...BUT IF THE 12Z ECMWF VERIFIES WE COULD BE GETTING
SOAKED AGAIN MONDAY-WEDNESDAY.
&&
.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
AS OF 130 PM EDT TUESDAY...
MORNING LOW CLOUDS AND FOG HAVE LIFTED ACROSS THE REGION.
SCT CU ARE FORMING THIS AFTERNOON ESPECIALLY ACROSS THE HIGHER
TERRAIN.
ONCE AGAIN...SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP
THIS AFTERNOON. THE BEST CHANCE OF A THUNDERSTORM IS ACROSS
THE WEST. LOCAL WRFARW DISPLAYED HIGHEST POPS ALONG THE SOUTHERN
BLUE RIDGE THIS AFTERNOON INTO TONIGHT. THEN...STORMS AND COVERAGE
TAPPER OFF OVERNIGHT INTO WEDNESDAY MORNING.
PATCHY FOG EXPECTED OVERNIGHT...IN LOCATIONS WHICH RAIN THIS
AFTERNOON AND THEN CLEAR OUT DURING THE EVENING INTO TONIGHT.
LWB HAS THE BEST CHANCE TO DROP TO LIFR IN FOG WEDNESDAY
MORNING.
THE REGION STAYS IN A WARM...MOIST AIRMASS THROUGH THURSDAY.
AREAS OF FOG WITH MVFR VISIBILITIES IS LIKELY EACH NIGHT AND EACH
AFTERNOON AND EVENING THERE WILL BE SCATTERED THUNDERSTORMS.
NEXT FRONT APPROACHES ON THURSDAY WITH MORE SHOWERS/STORMS
DEVELOPING. HIGH PRESSURE AND BETTER FLYING CONDITIONS ARE
EXPECTED ON FRIDAY BEHIND THE FRONT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS/KK
NEAR TERM...AMS/KK
SHORT TERM...WP
LONG TERM...WP
AVIATION...AMS/KK
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
140 PM EDT TUE MAY 21 2013
.SYNOPSIS...
LOW PRESSURE ALOFT WILL DRIFT EAST INTO THE ATLANTIC THIS
AFTERNOON INTO TONIGHT. A LARGE LOW PRESSURE SYSTEM WILL TRACK
FROM THE CENTRAL PLAINS INTO THE GREAT LAKES BY THURSDAY. THIS
SYSTEM WILL PUSH A COLD FRONT THROUGH THE AREA THURSDAY...FOLLOWED
BY HIGH PRESSURE ON FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1015 AM EDT TUESDAY...
NORTHWEST WINDS COMBINED WITH SUNSHINE WILL ALLOW VISIBILITIES TO
IMPROVE THIS MORNING...THUS THE DENSE FOG FOR WIDESPREAD HAS
ENDED. POCKET OF FOG MAY LINGER A HOUR OR SO IN THE DEEPER
SHELTERED LOCATION. SHORTWAVE OVER SOUTHSIDE THIS MORNING WILL
TRAVEL EAST INTO EASTERN VIRGINIA THIS AFTERNOON. RUC AND WRF
INDICATED THAT THE BEST CHANCE FOR THUNDERSTORMS THIS AFTERNOON
WILL BE ALONG THE SOUTHERN BLUE RIDGE. MADE SOME MINOR
ADJUSTMENTS IN TEMPERATURES AND DEW POINTS.
AS OF 500 AM EDT TUESDAY...
MANY LOCATIONS REPORTING VISIBILITIES ONE QUARTER MILE OR LESS.
HAVE ISSUED A DENSE FOG ADVISORY. CONDITIONS WILL IMPROVE AFTER
8AM.
RADAR SHOWED ISOLATED SHOWERS IN NORTH CENTRAL NORTH CAROLINA THIS
MORNING...MOVING SOUTHEAST. HAVE KEPT CHANCE OF PRECIPITATION OUT
OF THE FORECAST FOR THIS MORNING. DID LEAVE IN AREAS OF FOG.
SHORT WAVE WAS OVER THE FORECAST AREA EARLY THIS MORNING. MOST
MODELS HAVE FEATURE MOVING INTO EASTERN VIRGINIA BY THIS
AFTERNOON. RUC AND WRF MODELS SUGGEST MOST LIKELY LOCATION FOR
THUNDERSTORM DEVELOPMENT WILL BE ALONG THE SOUTHERN BLUE RIDGE
THIS AFTERNOON. THEN IN EASTERN KENTUCKY AND WEST
VIRGINIA...MOVING INTO OUR SOUTHEAST WEST VIRGINIA COUNTIES AND
THROUGH THE NORTHERN COUNTY WARNING AREA THIS EVENING. DO NOT
ENVISION MORE THAN SCATTERED COVERAGE THIS AFTERNOON OR TONIGHT.
850 MB WINDS TURN TO THE NORTHWEST BRIEFLY AFTERNOON FOLLOWING THE
SHORT WAVE THEN BACK TO SOUTHWEST FOR TONIGHT. NORTHWEST FLOW AND
850 MB TEMPERATURES AROUND +16 WILL RESULT IN DECENT WARM UP FOR
THE FOOTHILLS AND PIEDMONT...ESPECIALLY IN AREAS THAT HAVE SUN
THIS MORNING. GUIDANCE LOOKED REASONABLE FOR AFTERNOON HIGHS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 300 AM EDT TUESDAY...
CLOSED UPPER LOW AND SHARP TROUGH OVER THE MIDWEST WILL MAKE SLOW
EASTWARD PROGRESS AGAINST STRONG RIDGE OFF THE ATLANTIC COAST BUT
EVENTUALLY WILL SHOVE A SURFACE FRONT THROUGH THE CWA THURSDAY
AFTERNOON. UNTIL THEN AREA WILL REMAIN UNDER SOUTHERLY FLOW WITH
GENERALLY ABUNDANT MOISTURE BUT WEAK TO DISORGANIZED FORCING. MAY
SEE A PRE-FRONTAL SQUALL LINE ACRS THE OH VALLEY WED AFTERNOON
WHICH WILL LIKELY BE WEAKENING AS IT APPROACHES FAR WESTERN CWA
WED EVENING/NIGHT. STILL MAINTAINED AT LEAST HIGH CHC POPS IN THE
MOUNTAINS AHEAD OF ANY PSBL LINE WEDNESDAY AFTERNOON WHERE
DIFFERENTIAL DIURNAL HEATING AND UPSLOPE ENHANCMENT WILL BE FOCUS
FOR MOST LIKELY ACTIVITY WITH LOWER CHC POPS ACRS THE PIEDMONT.
SOME STORMS POTENTIALLY STRONG WITH CAPE APPROACHING 1000 J/KG BUT
LIMITED SHEAR SHOULD PRECLUDE MUCH IN THE WAY OF SEVERE STORMS.
AGAIN COULD BE WITH LOCALLY HEAVY RAINFALL AS PWATS REMAIN IN THE
1.2 TO 1.5 INCH RANGE AHEAD OF FRONT AND STORMS COULD BE SLOW-
MOVING.
POPS DIMINISH OVERNIGHT WED WITH LOSS OF HEATING BUT RENEWED
CONVECTIVE ACTIVITY LIKELY ON THURSDAY WITH PASSAGE OF SURFACE
FRONT. NOT LOOKING FOR MUCH IN THE WAY OF SEVERE AS BEST SUPPORT
WELL TO NORTH OF CWA BUT A FEW STRONG STORMS AND MORE POCKETS OF
HEAVY RAINFALL POSSIBLE. POPS DECREASING THURS NIGHT AND FRI AS
DRIER NW FLOW TAKES OVER. LEFT CHC POPS FRI AS COOLER AIR ALOFT
ENHANCES INSTABILITY LESSENING TREND. MILD TEMPS WILL PREDOMINATE
AHEAD OF THE FRONT WITH 80S WED AND EVEN THUR BUT SUBSTANTIALLY
COOLER WEATHER EXPECTED BEHIND THE FRONT FOR FRIDAY AND BEYOND.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
AS OF 345 PM EDT MONDAY...
BOTH THE GFS AND ECMWF ARE DELIVERING A GOOD INTRUSION COOLER AIR BY
12Z FRIDAY WITH H85 TEMPS SLIPPING TO +5C. THE UPPER TROUGH IS FCST
TO SLIDE ACROSS NEW ENGLAND ON FRIDAY WITH COOL NORTHWEST FLOW
PROGGED FROM THE GREAT LAKES TO THE MID ATLANTIC.
COOLER NORTHWESTERLY FLOW ALSO SUGGESTS THE AIR WILL BE DRY...THUS
HAVE REMOVED ALL MENTION OF PRECIP FOR THE WEEKEND. THAT SAID...AS
HIGH PRESSURE PASSES OVHD SATURDAY AND ROLLS OFF THE EAST COAST
SUNDAY...MOISTURE COULD SNEAK BACK IN THE PICTURE AS EARLY AS SUNDAY
AFTERNOON. ATTM...WILL GO WITH AN OPTIMISTIC FCST AND JUST
ADVERTISE INCREASING CLOUDS FOR SUNDAY...AND HOLD OFF ON NEXT
OPPORTUNITY FOR SHOWERS UNTIL MONDAY.
BOTH SATURDAY AND SUNDAY MORNINGS LOOK COOL WITH EARLY MORNING LOWS
IN THE 40S IN THE MOUNTAINS TO THE LOWER 50S IN THE PIEDMONT. IF
WINDS DECOUPLE AND SKIES REMAIN CLEAR...SOME OF THE SHELTERED
MOUNTAIN VALLEYS MAY SLIP INTO THE UPPER 30S.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
AS OF 130 PM EDT TUESDAY...
MORNING LOW CLOUDS AND FOG HAVE LIFTED ACROSS THE REGION.
SCT CU ARE FORMING THIS AFTERNOON ESPECIALLY ACROSS THE HIGHER
TERRAIN.
ONCE AGAIN...SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP
THIS AFTERNOON. THE BEST CHANCE OF A THUNDERSTORM IS ACROSS
THE WEST. LOCAL WRFARW DISPLAYED HIGHEST POPS ALONG THE SOUTHERN
BLUE RIDGE THIS AFTERNOON INTO TONIGHT. THEN...STORMS AND COVERAGE
TAPPER OFF OVERNIGHT INTO WEDNESDAY MORNING.
PATCHY FOG EXPECTED OVERNIGHT...IN LOCATIONS WHICH RAIN THIS
AFTERNOON AND THEN CLEAR OUT DURING THE EVENING INTO TONIGHT.
LWB HAS THE BEST CHANCE TO DROP TO LIFR IN FOG WEDNESDAY
MORNING.
THE REGION STAYS IN A WARM...MOIST AIRMASS THROUGH THURSDAY.
AREAS OF FOG WITH MVFR VISIBILITIES IS LIKELY EACH NIGHT AND EACH
AFTERNOON AND EVENING THERE WILL BE SCATTERED THUNDERSTORMS.
NEXT FRONT APPROACHES ON THURSDAY WITH MORE SHOWERS/STORMS
DEVELOPING. HIGH PRESSURE AND BETTER FLYING CONDITIONS ARE
EXPECTED ON FRIDAY BEHIND THE FRONT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS/KK
SHORT TERM...PC
LONG TERM...PM
AVIATION...AMS/KK
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1025 AM EDT TUE MAY 21 2013
.SYNOPSIS...
LOW PRESSURE ALOFT WILL DRIFT EAST OF THE REGION THIS MORNING. A
LARGE LOW PRESSURE SYSTEM WILL TRACK FROM THE CENTRAL PLAINS INTO
THE GREAT LAKES BY THURSDAY. THIS SYSTEM WILL PUSH A COLD FRONT
THROUGH THE AREA THURSDAY...FOLLOWED BY HIGH PRESSURE ON FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1015 AM EDT TUESDAY...
NORTHWEST WINDS COMBINED WITH SUNSHINE WILL ALLOW VISIBILITIES TO
IMPROVE THIS MORNING...THUS THE DENSE FOG FOR WIDESPREAD HAS
ENDED. POCKET OF FOG MAY LINGER A HOUR OR SO IN THE DEEPER
SHELTERED LOCATION. SHORTWAVE OVER SOUTHSIDE THIS MORNING WILL
TRAVEL EAST INTO EASTERN VIRGINIA THIS AFTERNOON. RUC AND WRF
INDICATED THAT THE BEST CHANCE FOR THUNDERSTORMS THIS AFTERNOON
WILL BE ALONG THE SOUTHERN BLUE RIDGE. MADE SOME MINOR
ADJUSTMENTS IN TEMPERATURES AND DEW POINTS.
AS OF 500 AM EDT TUESDAY...
MANY LOCATIONS REPORTING VISIBILITIES ONE QUARTER MILE OR LESS.
HAVE ISSUED A DENSE FOG ADVISORY. CONDITIONS WILL IMPROVE AFTER
8AM.
RADAR SHOWED ISOLATED SHOWERS IN NORTH CENTRAL NORTH CAROLINA THIS
MORNING...MOVING SOUTHEAST. HAVE KEPT CHANCE OF PRECIPITATION OUT
OF THE FORECAST FOR THIS MORNING. DID LEAVE IN AREAS OF FOG.
SHORT WAVE WAS OVER THE FORECAST AREA EARLY THIS MORNING. MOST
MODELS HAVE FEATURE MOVING INTO EASTERN VIRGINIA BY THIS
AFTERNOON. RUC AND WRF MODELS SUGGEST MOST LIKELY LOCATION FOR
THUNDERSTORM DEVELOPMENT WILL BE ALONG THE SOUTHERN BLUE RIDGE
THIS AFTERNOON. THEN IN EASTERN KENTUCKY AND WEST
VIRGINIA...MOVING INTO OUR SOUTHEAST WEST VIRGINIA COUNTIES AND
THROUGH THE NORTHERN COUNTY WARNING AREA THIS EVENING. DO NOT
ENVISION MORE THAN SCATTERED COVERAGE THIS AFTERNOON OR TONIGHT.
850 MB WINDS TURN TO THE NORTHWEST BRIEFLY AFTERNOON FOLLOWING THE
SHORT WAVE THEN BACK TO SOUTHWEST FOR TONIGHT. NORTHWEST FLOW AND
850 MB TEMPERATURES AROUND +16 WILL RESULT IN DECENT WARM UP FOR
THE FOOTHILLS AND PIEDMONT...ESPECIALLY IN AREAS THAT HAVE SUN
THIS MORNING. GUIDANCE LOOKED REASONABLE FOR AFTERNOON HIGHS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 300 AM EDT TUESDAY...
CLOSED UPPER LOW AND SHARP TROUGH OVER THE MIDWEST WILL MAKE SLOW
EASTWARD PROGRESS AGAINST STRONG RIDGE OFF THE ATLANTIC COAST BUT
EVENTUALLY WILL SHOVE A SURFACE FRONT THROUGH THE CWA THURSDAY
AFTERNOON. UNTIL THEN AREA WILL REMAIN UNDER SOUTHERLY FLOW WITH
GENERALLY ABUNDANT MOISTURE BUT WEAK TO DISORGANIZED FORCING. MAY
SEE A PRE-FRONTAL SQUALL LINE ACRS THE OH VALLEY WED AFTERNOON
WHICH WILL LIKELY BE WEAKENING AS IT APPROACHES FAR WESTERN CWA
WED EVENING/NIGHT. STILL MAINTAINED AT LEAST HIGH CHC POPS IN THE
MOUNTAINS AHEAD OF ANY PSBL LINE WEDNESDAY AFTERNOON WHERE
DIFFERENTIAL DIURNAL HEATING AND UPSLOPE ENHANCMENT WILL BE FOCUS
FOR MOST LIKELY ACTIVITY WITH LOWER CHC POPS ACRS THE PIEDMONT.
SOME STORMS POTENTIALLY STRONG WITH CAPE APPROACHING 1000 J/KG BUT
LIMITED SHEAR SHOULD PRECLUDE MUCH IN THE WAY OF SEVERE STORMS.
AGAIN COULD BE WITH LOCALLY HEAVY RAINFALL AS PWATS REMAIN IN THE
1.2 TO 1.5 INCH RANGE AHEAD OF FRONT AND STORMS COULD BE SLOW-
MOVING.
POPS DIMINISH OVERNIGHT WED WITH LOSS OF HEATING BUT RENEWED
CONVECTIVE ACTIVITY LIKELY ON THURSDAY WITH PASSAGE OF SURFACE
FRONT. NOT LOOKING FOR MUCH IN THE WAY OF SEVERE AS BEST SUPPORT
WELL TO NORTH OF CWA BUT A FEW STRONG STORMS AND MORE POCKETS OF
HEAVY RAINFALL POSSIBLE. POPS DECREASING THURS NIGHT AND FRI AS
DRIER NW FLOW TAKES OVER. LEFT CHC POPS FRI AS COOLER AIR ALOFT
ENHANCES INSTABILITY LESSENING TREND. MILD TEMPS WILL PREDOMINATE
AHEAD OF THE FRONT WITH 80S WED AND EVEN THUR BUT SUBSTANTIALLY
COOLER WEATHER EXPECTED BEHIND THE FRONT FOR FRIDAY AND BEYOND.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
AS OF 345 PM EDT MONDAY...
BOTH THE GFS AND ECMWF ARE DELIVERING A GOOD INTRUSION COOLER AIR BY
12Z FRIDAY WITH H85 TEMPS SLIPPING TO +5C. THE UPPER TROUGH IS FCST
TO SLIDE ACROSS NEW ENGLAND ON FRIDAY WITH COOL NORTHWEST FLOW
PROGGED FROM THE GREAT LAKES TO THE MID ATLANTIC.
COOLER NORTHWESTERLY FLOW ALSO SUGGESTS THE AIR WILL BE DRY...THUS
HAVE REMOVED ALL MENTION OF PRECIP FOR THE WEEKEND. THAT SAID...AS
HIGH PRESSURE PASSES OVHD SATURDAY AND ROLLS OFF THE EAST COAST
SUNDAY...MOISTURE COULD SNEAK BACK IN THE PICTURE AS EARLY AS SUNDAY
AFTERNOON. ATTM...WILL GO WITH AN OPTIMISTIC FCST AND JUST
ADVERTISE INCREASING CLOUDS FOR SUNDAY...AND HOLD OFF ON NEXT
OPPORTUNITY FOR SHOWERS UNTIL MONDAY.
BOTH SATURDAY AND SUNDAY MORNINGS LOOK COOL WITH EARLY MORNING LOWS
IN THE 40S IN THE MOUNTAINS TO THE LOWER 50S IN THE PIEDMONT. IF
WINDS DECOUPLE AND SKIES REMAIN CLEAR...SOME OF THE SHELTERED
MOUNTAIN VALLEYS MAY SLIP INTO THE UPPER 30S.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
AS OF 730 AM EDT TUESDAY...
POCKETS OF FOG WILL CONTINUE TO LIFT THIS MORNING AS WINDS
INCREASE. LOW CLOUDS SHOULD LIFT BY LATE MORNING.
ISOLATED TO SCATTERED THUNDERSTORMS WILL DEVELOP AGAIN THIS
AFTERNOON. PROBABILITY AT ANY ONE AIRPORT IS TOO LOW TO INCLUDE IN
THE TAFS AT THIS TIME. FOG FORMATION OVERNIGHT WILL BE DEPENDENT
ON WHICH LOCATIONS GET RAIN THIS AFTERNOON AND WHICH CLEAR OUT
DURING THE EVENING.
THE REGION STAYS IN A WARM...MOIST AIRMASS THROUGH THURSDAY.
AREAS OF FOG WITH MVFR VISIBILITIES IS LIKELY EACH NIGHT AND EACH
AFTERNOON AND EVENING THERE WILL BE SCATTERED THUNDERSTORMS.
NEXT FRONT APPROACHES ON THURSDAY WITH MORE SHOWERS/STORMS
DEVELOPING. HIGH PRESSURE AND BETTER FLYING CONDITIONS ARE
EXPECTED ON FRIDAY BEHIND THE FRONT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS/KK
SHORT TERM...PC
LONG TERM...PM
AVIATION...AMS/KK
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
736 AM EDT TUE MAY 21 2013
.SYNOPSIS...
LOW PRESSURE ALOFT WILL DRIFT EAST OF THE REGION THIS MORNING. A
LARGE LOW PRESSURE SYSTEM WILL TRACK FROM THE CENTRAL PLAINS INTO
THE GREAT LAKES BY THURSDAY. THIS SYSTEM WILL PUSH A COLD FRONT
THROUGH THE AREA THURSDAY...FOLLOWED BY HIGH PRESSURE ON FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 500 AM EDT TUESDAY...
MANY LOCATIONS REPORTING VISIBILITIES ONE QUARTER MILE OR LESS.
HAVE ISSUED A DENSE FOG ADVISORY. CONDITIONS WILL IMPROVE AFTER
8AM.
RADAR SHOWED ISOLATED SHOWERS IN NORTH CENTRAL NORTH CAROLINA THIS
MORNING...MOVING SOUTHEAST. HAVE KEPT CHANCE OF PRECIPITATION OUT
OF THE FORECAST FOR THIS MORNING. DID LEAVE IN AREAS OF FOG.
SHORT WAVE WAS OVER THE FORECAST AREA EARLY THIS MORNING. MOST
MODELS HAVE FEATURE MOVING INTO EASTERN VIRGINIA BY THIS
AFTERNOON. RUC AND WRF MODELS SUGGEST MOST LIKELY LOCATION FOR
THUNDERSTORM DEVELOPMENT WILL BE ALONG THE SOUTHERN BLUE RIDGE
THIS AFTERNOON. THEN IN EASTERN KENTUCKY AND WEST
VIRGINIA...MOVING INTO OUR SOUTHEAST WEST VIRGINIA COUNTIES AND
THROUGH THE NORTHERN COUNTY WARNING AREA THIS EVENING. DO NOT
ENVISION MORE THAN SCATTERED COVERAGE THIS AFTERNOON OR TONIGHT.
850 MB WINDS TURN TO THE NORTHWEST BRIEFLY AFTERNOON FOLLOWING THE
SHORT WAVE THEN BACK TO SOUTHWEST FOR TONIGHT. NORTHWEST FLOW AND
850 MB TEMPERATURES AROUND +16 WILL RESULT IN DECENT WARM UP FOR
THE FOOTHILLS AND PIEDMONT...ESPECIALLY IN AREAS THAT HAVE SUN
THIS MORNING. GUIDANCE LOOKED REASONABLE FOR AFTERNOON HIGHS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 300 AM EDT TUESDAY...
CLOSED UPPER LOW AND SHARP TROUGH OVER THE MIDWEST WILL MAKE SLOW
EASTWARD PROGRESS AGAINST STRONG RIDGE OFF THE ATLANTIC COAST BUT
EVENTUALLY WILL SHOVE A SURFACE FRONT THROUGH THE CWA THURSDAY
AFTERNOON. UNTIL THEN AREA WILL REMAIN UNDER SOUTHERLY FLOW WITH
GENERALLY ABUNDANT MOISTURE BUT WEAK TO DISORGANIZED FORCING. MAY
SEE A PRE-FRONTAL SQUALL LINE ACRS THE OH VALLEY WED AFTERNOON
WHICH WILL LIKELY BE WEAKENING AS IT APPROACHES FAR WESTERN CWA
WED EVENING/NIGHT. STILL MAINTAINED AT LEAST HIGH CHC POPS IN THE
MOUNTAINS AHEAD OF ANY PSBL LINE WEDNESDAY AFTERNOON WHERE
DIFFERENTIAL DIURNAL HEATING AND UPSLOPE ENHANCMENT WILL BE FOCUS
FOR MOST LIKELY ACTIVITY WITH LOWER CHC POPS ACRS THE PIEDMONT.
SOME STORMS POTENTIALLY STRONG WITH CAPE APPROACHING 1000 J/KG BUT
LIMITED SHEAR SHOULD PRECLUDE MUCH IN THE WAY OF SEVERE STORMS.
AGAIN COULD BE WITH LOCALLY HEAVY RAINFALL AS PWATS REMAIN IN THE
1.2 TO 1.5 INCH RANGE AHEAD OF FRONT AND STORMS COULD BE SLOW-
MOVING.
POPS DIMINISH OVERNIGHT WED WITH LOSS OF HEATING BUT RENEWED
CONVECTIVE ACTIVITY LIKELY ON THURSDAY WITH PASSAGE OF SURFACE
FRONT. NOT LOOKING FOR MUCH IN THE WAY OF SEVERE AS BEST SUPPORT
WELL TO NORTH OF CWA BUT A FEW STRONG STORMS AND MORE POCKETS OF
HEAVY RAINFALL POSSIBLE. POPS DECREASING THURS NIGHT AND FRI AS
DRIER NW FLOW TAKES OVER. LEFT CHC POPS FRI AS COOLER AIR ALOFT
ENHANCES INSTABILITY LESSENING TREND. MILD TEMPS WILL PREDOMINATE
AHEAD OF THE FRONT WITH 80S WED AND EVEN THUR BUT SUBSTANTIALLY
COOLER WEATHER EXPECTED BEHIND THE FRONT FOR FRIDAY AND BEYOND.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
AS OF 345 PM EDT MONDAY...
BOTH THE GFS AND ECMWF ARE DELIVERING A GOOD INTRUSION COOLER AIR BY
12Z FRIDAY WITH H85 TEMPS SLIPPING TO +5C. THE UPPER TROUGH IS FCST
TO SLIDE ACROSS NEW ENGLAND ON FRIDAY WITH COOL NORTHWEST FLOW
PROGGED FROM THE GREAT LAKES TO THE MID ATLANTIC.
COOLER NORTHWESTERLY FLOW ALSO SUGGESTS THE AIR WILL BE DRY...THUS
HAVE REMOVED ALL MENTION OF PRECIP FOR THE WEEKEND. THAT SAID...AS
HIGH PRESSURE PASSES OVHD SATURDAY AND ROLLS OFF THE EAST COAST
SUNDAY...MOISTURE COULD SNEAK BACK IN THE PICTURE AS EARLY AS SUNDAY
AFTERNOON. ATTM...WILL GO WITH AN OPTIMISTIC FCST AND JUST
ADVERTISE INCREASING CLOUDS FOR SUNDAY...AND HOLD OFF ON NEXT
OPPORTUNITY FOR SHOWERS UNTIL MONDAY.
BOTH SATURDAY AND SUNDAY MORNINGS LOOK COOL WITH EARLY MORNING LOWS
IN THE 40S IN THE MOUNTAINS TO THE LOWER 50S IN THE PIEDMONT. IF
WINDS DECOUPLE AND SKIES REMAIN CLEAR...SOME OF THE SHELTERED
MOUNTAIN VALLEYS MAY SLIP INTO THE UPPER 30S.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 730 AM EDT TUESDAY...
WIDESPREAD FOG COVERED THE REGION THIS MORNING WITH IFR TO LIFR
VISIBILITIES. LOW CONFIDENCE AS TO HOW FAST VISIBILITIES WILL
IMPROVE TO MVFR THEN VFR. ONCE 12Z RNK AND GSO UPPER AIR SOUNDINGS
ARE AVAILABLE...DEPTH OF LOW CLOUDS AND FOG WILL BE DETERMINED AND
EROSION TIME MAY BE EASIER TO JUDGE.
A SHORT WAVE OVER THE AREA TONIGHT MOVES INTO EASTERN
VIRGINIA THIS MORNING. ISOLATED TO SCATTERED THUNDERSTORMS WILL
DEVELOP AGAIN THIS AFTERNOON. PROBABILITY AT ANY ONE AIRPORT IS
TOO LOW TO INCLUDE IN THE TAFS AT THIS TIME. FOG FORMATION
OVERNIGHT WILL BE DEPENDENT ON WHICH LOCATIONS GET RAIN THIS
AFTERNOON AND WHICH CLEAR OUT DURING THE EVENING.
THE REGION STAYS IN A WARM...MOIST AIRMASS THROUGH THURSDAY.
AREAS OF FOG WITH MVFR VISIBILITIES IS LIKELY EACH NIGHT AND EACH
AFTERNOON AND EVENING THERE WILL BE SCATTERED THUNDERSTORMS.
NEXT FRONT APPROACHES ON THURSDAY WITH MORE SHOWERS/STORMS
DEVELOPING. HIGH PRESSURE AND BETTER FLYING CONDITIONS ARE
EXPECTED ON FRIDAY BEHIND THE FRONT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR VAZ009-
012>020-022>024.
NC...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR NCZ001-002-
018.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...PC
LONG TERM...PM
AVIATION...AMS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
459 AM EDT TUE MAY 21 2013
.SYNOPSIS...
LOW PRESSURE ALOFT WILL DRIFT EAST OF THE REGION THIS MORNING. A
LARGE LOW PRESSURE SYSTEM WILL TRACK FROM THE CENTRAL PLAINS INTO
THE GREAT LAKES BY THURSDAY. THIS SYSTEM WILL PUSH A COLD FRONT
THROUGH THE AREA THURSDAY...FOLLOWED BY HIGH PRESSURE ON FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 500 AM EDT TUESDAY...
MANY LOCATIONS REPORTING VISIBILITIES ONE QUARTER MILE OR LESS.
HAVE ISSUED A DENSE FOG ADVISORY. CONDITIONS WILL IMPROVE AFTER
8AM.
RADAR SHOWED ISOLATED SHOWERS IN NORTH CENTRAL NORTH CAROLINA THIS
MORNING...MOVING SOUTHEAST. HAVE KEPT CHANCE OF PRECIPITATION OUT
OF THE FORECAST FOR THIS MORNING. DID LEAVE IN AREAS OF FOG.
SHORT WAVE WAS OVER THE FORECAST AREA EARLY THIS MORNING. MOST
MODELS HAVE FEATURE MOVING INTO EASTERN VIRGINIA BY THIS
AFTERNOON. RUC AND WRF MODELS SUGGEST MOST LIKELY LOCATION FOR
THUNDERSTORM DEVELOPMENT WILL BE ALONG THE SOUTHERN BLUE RIDGE
THIS AFTERNOON. THEN IN EASTERN KENTUCKY AND WEST
VIRGINIA...MOVING INTO OUR SOUTHEAST WEST VIRGINIA COUNTIES AND
THROUGH THE NORTHERN COUNTY WARNING AREA THIS EVENING. DO NOT
ENVISION MORE THAN SCATTERED COVERAGE THIS AFTERNOON OR TONIGHT.
850 MB WINDS TURN TO THE NORTHWEST BRIEFLY AFTERNOON FOLLOWING THE
SHORT WAVE THEN BACK TO SOUTHWEST FOR TONIGHT. NORTHWEST FLOW AND
850 MB TEMPERATURES AROUND +16 WILL RESULT IN DECENT WARM UP FOR
THE FOOTHILLS AND PIEDMONT...ESPECIALLY IN AREAS THAT HAVE SUN
THIS MORNING. GUIDANCE LOOKED REASONABLE FOR AFTERNOON HIGHS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 300 AM EDT TUESDAY...
CLOSED UPPER LOW AND SHARP TROUGH OVER THE MIDWEST WILL MAKE SLOW
EASTWARD PROGRESS AGAINST STRONG RIDGE OFF THE ATLANTIC COAST BUT
EVENTUALLY WILL SHOVE A SURFACE FRONT THROUGH THE CWA THURSDAY
AFTERNOON. UNTIL THEN AREA WILL REMAIN UNDER SOUTHERLY FLOW WITH
GENERALLY ABUNDANT MOISTURE BUT WEAK TO DISORGANIZED FORCING. MAY
SEE A PRE-FRONTAL SQUALL LINE ACRS THE OH VALLEY WED AFTERNOON
WHICH WILL LIKELY BE WEAKENING AS IT APPROACHES FAR WESTERN CWA
WED EVENING/NIGHT. STILL MAINTAINED AT LEAST HIGH CHC POPS IN THE
MOUNTAINS AHEAD OF ANY PSBL LINE WEDNESDAY AFTERNOON WHERE
DIFFERENTIAL DIURNAL HEATING AND UPSLOPE ENHANCMENT WILL BE FOCUS
FOR MOST LIKELY ACTIVITY WITH LOWER CHC POPS ACRS THE PIEDMONT.
SOME STORMS POTENTIALLY STRONG WITH CAPE APPROACHING 1000 J/KG BUT
LIMITED SHEAR SHOULD PRECLUDE MUCH IN THE WAY OF SEVERE STORMS.
AGAIN COULD BE WITH LOCALLY HEAVY RAINFALL AS PWATS REMAIN IN THE
1.2 TO 1.5 INCH RANGE AHEAD OF FRONT AND STORMS COULD BE SLOW-
MOVING.
POPS DIMINISH OVERNIGHT WED WITH LOSS OF HEATING BUT RENEWED
CONVECTIVE ACTIVITY LIKELY ON THURSDAY WITH PASSAGE OF SURFACE
FRONT. NOT LOOKING FOR MUCH IN THE WAY OF SEVERE AS BEST SUPPORT
WELL TO NORTH OF CWA BUT A FEW STRONG STORMS AND MORE POCKETS OF
HEAVY RAINFALL POSSIBLE. POPS DECREASING THURS NIGHT AND FRI AS
DRIER NW FLOW TAKES OVER. LEFT CHC POPS FRI AS COOLER AIR ALOFT
ENHANCES INSTABILITY LESSENING TREND. MILD TEMPS WILL PREDOMINATE
AHEAD OF THE FRONT WITH 80S WED AND EVEN THUR BUT SUBSTANTIALLY
COOLER WEATHER EXPECTED BEHIND THE FRONT FOR FRIDAY AND BEYOND.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
AS OF 345 PM EDT MONDAY...
BOTH THE GFS AND ECMWF ARE DELIVERING A GOOD INTRUSION COOLER AIR BY
12Z FRIDAY WITH H85 TEMPS SLIPPING TO +5C. THE UPPER TROUGH IS FCST
TO SLIDE ACROSS NEW ENGLAND ON FRIDAY WITH COOL NORTHWEST FLOW
PROGGED FROM THE GREAT LAKES TO THE MID ATLANTIC.
COOLER NORTHWESTERLY FLOW ALSO SUGGESTS THE AIR WILL BE DRY...THUS
HAVE REMOVED ALL MENTION OF PRECIP FOR THE WEEKEND. THAT SAID...AS
HIGH PRESSURE PASSES OVHD SATURDAY AND ROLLS OFF THE EAST COAST
SUNDAY...MOISTURE COULD SNEAK BACK IN THE PICTURE AS EARLY AS SUNDAY
AFTERNOON. ATTM...WILL GO WITH AN OPTIMISTIC FCST AND JUST
ADVERTISE INCREASING CLOUDS FOR SUNDAY...AND HOLD OFF ON NEXT
OPPORTUNITY FOR SHOWERS UNTIL MONDAY.
BOTH SATURDAY AND SUNDAY MORNINGS LOOK COOL WITH EARLY MORNING LOWS
IN THE 40S IN THE MOUNTAINS TO THE LOWER 50S IN THE PIEDMONT. IF
WINDS DECOUPLE AND SKIES REMAIN CLEAR...SOME OF THE SHELTERED
MOUNTAIN VALLEYS MAY SLIP INTO THE UPPER 30S.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
AS OF 145 AM EDT MONDAY...
MANY OBSERVATIONS HAVE NOT BEEN TRANSMITTED SINCE 04Z/MIDNIGHT DUE
TO AN OUTAGE IN NATIONAL COMMUNICATIONS CENTER. UNTIL DATA FLOW IS
RESUMED...HAVE ADDED...AMD NOT SKED...TO THE END OF THE TAFS.
EXPECT AREAS OF FOG AND STRATUS OVERNIGHT. IFR TO LIFR CEILINGS
ARE LIKELY BY 09Z/4AM. LOCATIONS THAT HAD RAIN ON MONDAY WILL HAVE
FOG...INCLUDING ROA AND DAN.
A SHORT WAVE OVER THE AREA TONIGHT MOVES INTO EASTERN VIRGINIA
TODAY. ISOLATED TO SCATTERED THUNDERSTORMS WILL DEVELOP AGAIN THIS
AFTERNOON. PROBABILITY AT ANY ONE AIRPORT IS TOO LOW TON INCLUDE
IN THE TAF AT THIS TIME.
THE REGION STAYS IN A WARM...MOIST AIRMASS THROUGH THURSDAY.
PATCHY FOG WITH MVFR VISIBILITIES IS LIKELY EACH NIGHT AND EACH
AFTERNOON AND EVENING THERE WILL BE SCATTERED THUNDERSTORMS.
NEXT FRONT APPROACHES ON THURSDAY WITH MORE SHOWERS/STORMS
DEVELOPING. HIGH PRESSURE AND BETTER FLYING CONDITIONS ARE
EXPECTED ON FRIDAY BEHIND THE FRONT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR VAZ009-
012>020-022>024.
NC...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR NCZ001-002-
018.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...PC
LONG TERM...PM
AVIATION...AMS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
422 AM EDT TUE MAY 21 2013
.SYNOPSIS...
LOW PRESSURE ALOFT WILL DRIFT EAST OF THE REGION THIS MORNING. A
LARGE LOW PRESSURE SYSTEM WILL TRACK FROM THE CENTRAL PLAINS INTO
THE GREAT LAKES BY THURSDAY. THIS SYSTEM WILL PUSH A COLD FRONT
THROUGH THE AREA THURSDAY...FOLLOWED BY HIGH PRESSURE ON FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 410 AM EDT TUESDAY...
RADAR SHOWED ISOLATED SHOWERS IN NORTH CENTRAL NORTH CAROLINA THIS
MORNING...MOVING SOUTHEAST. HAVE KEPT CHANCE OF PRECIPITATION OUT
OF THE FORECAST FOR THIS MORNING. DID LEAVE IN AREAS OF FOG.
SHORT WAVE WAS OVER THE FORECAST AREA EARLY THIS MORNING. MOST
MODELS HAVE FEATURE MOVING INTO EASTERN VIRGINIA BY THIS
AFTERNOON. RUC AND WRF MODELS SUGGEST MOST LIKELY LOCATION FOR
THUNDERSTORM DEVELOPMENT WILL BE ALONG THE SOUTHERN BLUE RIDGE
THIS AFTERNOON. THEN IN EASTERN KENTUCKY AND WEST
VIRGINIA...MOVING INTO OUR SOUTHEAST WEST VIRGINIA COUNTIES AND
THROUGH THE NORTHERN COUNTY WARNING AREA THIS EVENING. DO NOT
ENVISION MORE THAN SCATTERED COVERAGE THIS AFTERNOON OR TONIGHT.
850 MB WINDS TURN TO THE NORTHWEST BRIEFLY AFTERNOON FOLLOWING THE
SHORT WAVE THEN BACK TO SOUTHWEST FOR TONIGHT. NORTHWEST FLOW AND
850 MB TEMPERATURES AROUND +16 WILL RESULT IN DECENT WARM UP FOR
THE FOOTHILLS AND PIEDMONT...ESPECIALLY IN AREAS THAT HAVE SUN
THIS MORNING. GUIDANCE LOOKED REASONABLE FOR AFTERNOON HIGHS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 300 AM EDT TUESDAY...
CLOSED UPPER LOW AND SHARP TROUGH OVER THE MIDWEST WILL MAKE SLOW
EASTWARD PROGRESS AGAINST STRONG RIDGE OFF THE ATLANTIC COAST BUT
EVENTUALLY WILL SHOVE A SURFACE FRONT THROUGH THE CWA THURSDAY
AFTERNOON. UNTIL THEN AREA WILL REMAIN UNDER SOUTHERLY FLOW WITH
GENERALLY ABUNDANT MOISTURE BUT WEAK TO DISORGANIZED FORCING. MAY
SEE A PRE-FRONTAL SQUALL LINE ACRS THE OH VALLEY WED AFTERNOON
WHICH WILL LIKELY BE WEAKENING AS IT APPROACHES FAR WESTERN CWA
WED EVENING/NIGHT. STILL MAINTAINED AT LEAST HIGH CHC POPS IN THE
MOUNTAINS AHEAD OF ANY PSBL LINE WEDNESDAY AFTERNOON WHERE
DIFFERENTIAL DIURNAL HEATING AND UPSLOPE ENHANCMENT WILL BE FOCUS
FOR MOST LIKELY ACTIVITY WITH LOWER CHC POPS ACRS THE PIEDMONT.
SOME STORMS POTENTIALLY STRONG WITH CAPE APPROACHING 1000 J/KG BUT
LIMITED SHEAR SHOULD PRECLUDE MUCH IN THE WAY OF SEVERE STORMS.
AGAIN COULD BE WITH LOCALLY HEAVY RAINFALL AS PWATS REMAIN IN THE
1.2 TO 1.5 INCH RANGE AHEAD OF FRONT AND STORMS COULD BE SLOW-
MOVING.
POPS DIMINISH OVERNIGHT WED WITH LOSS OF HEATING BUT RENEWED
CONVECTIVE ACTIVITY LIKELY ON THURSDAY WITH PASSAGE OF SURFACE
FRONT. NOT LOOKING FOR MUCH IN THE WAY OF SEVERE AS BEST SUPPORT
WELL TO NORTH OF CWA BUT A FEW STRONG STORMS AND MORE POCKETS OF
HEAVY RAINFALL POSSIBLE. POPS DECREASING THURS NIGHT AND FRI AS
DRIER NW FLOW TAKES OVER. LEFT CHC POPS FRI AS COOLER AIR ALOFT
ENHANCES INSTABILITY LESSENING TREND. MILD TEMPS WILL PREDOMINATE
AHEAD OF THE FRONT WITH 80S WED AND EVEN THUR BUT SUBSTANTIALLY
COOLER WEATHER EXPECTED BEHIND THE FRONT FOR FRIDAY AND BEYOND.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
AS OF 345 PM EDT MONDAY...
BOTH THE GFS AND ECMWF ARE DELIVERING A GOOD INTRUSION COOLER AIR BY
12Z FRIDAY WITH H85 TEMPS SLIPPING TO +5C. THE UPPER TROUGH IS FCST
TO SLIDE ACROSS NEW ENGLAND ON FRIDAY WITH COOL NORTHWEST FLOW
PROGGED FROM THE GREAT LAKES TO THE MID ATLANTIC.
COOLER NORTHWESTERLY FLOW ALSO SUGGESTS THE AIR WILL BE DRY...THUS
HAVE REMOVED ALL MENTION OF PRECIP FOR THE WEEKEND. THAT SAID...AS
HIGH PRESSURE PASSES OVHD SATURDAY AND ROLLS OFF THE EAST COAST
SUNDAY...MOISTURE COULD SNEAK BACK IN THE PICTURE AS EARLY AS SUNDAY
AFTERNOON. ATTM...WILL GO WITH AN OPTIMISTIC FCST AND JUST
ADVERTISE INCREASING CLOUDS FOR SUNDAY...AND HOLD OFF ON NEXT
OPPORTUNITY FOR SHOWERS UNTIL MONDAY.
BOTH SATURDAY AND SUNDAY MORNINGS LOOK COOL WITH EARLY MORNING LOWS
IN THE 40S IN THE MOUNTAINS TO THE LOWER 50S IN THE PIEDMONT. IF
WINDS DECOUPLE AND SKIES REMAIN CLEAR...SOME OF THE SHELTERED
MOUNTAIN VALLEYS MAY SLIP INTO THE UPPER 30S.
&&
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
AS OF 145 AM EDT MONDAY...
MANY OBSERVATIONS HAVE NOT BEEN TRANSMITTED SINCE 04Z/MIDNIGHT DUE
TO AN OUTAGE IN NATIONAL COMMUNICATIONS CENTER. UNTIL DATA FLOW IS
RESUMED...HAVE ADDED...AMD NOT SKED...TO THE END OF THE TAFS.
EXPECT AREAS OF FOG AND STRATUS OVERNIGHT. IFR TO LIFR CEILINGS
ARE LIKELY BY 09Z/4AM. LOCATIONS THAT HAD RAIN ON MONDAY WILL HAVE
FOG...INCLUDING ROA AND DAN.
A SHORT WAVE OVER THE AREA TONIGHT MOVES INTO EASTERN VIRGINIA
TODAY. ISOLATED TO SCATTERED THUNDERSTORMS WILL DEVELOP AGAIN THIS
AFTERNOON. PROBABILITY AT ANY ONE AIRPORT IS TOO LOW TON INCLUDE
IN THE TAF AT THIS TIME.
THE REGION STAYS IN A WARM...MOIST AIRMASS THROUGH THURSDAY.
PATCHY FOG WITH MVFR VISIBILITIES IS LIKELY EACH NIGHT AND EACH
AFTERNOON AND EVENING THERE WILL BE SCATTERED THUNDERSTORMS.
NEXT FRONT APPROACHES ON THURSDAY WITH MORE SHOWERS/STORMS
DEVELOPING. HIGH PRESSURE AND BETTER FLYING CONDITIONS ARE
EXPECTED ON FRIDAY BEHIND THE FRONT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...PC
LONG TERM...PM
AVIATION...AMS
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
904 PM CDT WED MAY 22 2013
NEW INFORMATION ADDED TO UPDATE SECTION
.UPDATE...
ISSUED AT 902 PM CDT WED MAY 22 2013
SLOW MOVING AREA OF LIGHT RAIN ASSOCIATED WITH PESKY
MID-LEVEL CIRCULATION AND ASSOCIATED DEFORMATION SLOWLY WANING
AND BECOMING INCREASINGLY DISORGANIZED AS NORTHERLY FLOW AND
SUBSIDENCE INCREASES UPSTREAM. GOING SHORT-TERM FORECAST STILL
LOOKING ON TRACK. LAST FEW RUNS OF THE HRRR SEEM TO HAVE A DECENT
HANDLE ON THE DEMISE OF THIS SYSTEM WITH PRECIPITATION ENDING FROM
NORTHWEST TO SOUTHEAST OVERNIGHT. EXPECT BACK EDGE OF WEAKENING
PRECIPITATION SHIELD TO MOVE SOUTHEAST OF THE FORECAST AREA BY
AROUND 10Z OR 11Z FOLLOWED BY CLEARING SKIES AFTER 15Z THURSDAY.
EXPECT NORTHEAST WINDS TO INCREASE OVERNIGHT WITH A FEW GUSTS OF
25 TO 30 MPH MAINLY OVER THE FOX VALLEY FROM GREEN BAY SOUTH TO
OSHKOSH.
&&
.SYNOPSIS...
ISSUED AT 233 PM CDT WED MAY 22 2013
UPPER LEVEL SYSTEM THAT HAS BEEN SITTING OVER THE NORTHERN PLAINS
THE PAST FEW DAYS WAS FINALLY MOVING EAST...WITH THE SFC LOW
PRESSURE SLIDING THROUGH SOUTHERN WISCONSIN THIS AFTERNOON PER
MSAS ANALYSIS. THIS SFC LOW...COMBINED WITH ENERGY FROM A POTENT
SHORTWAVE THAT WAS SWINGING AROUND THE SOUTHEAST SIDE OF THE
UPPER LEVEL TROUGH INTO THE GREAT LAKES AREA...RESULTED IN
WIDESPREAD SHOWERS THIS AFTERNOON. SOME LIGHTNING WAS ALSO
DETECTED IN THIS AREA OF PRECIP...MAINLY IN THE VICINITY OF A NOSE
OF MINOR MU-CAPES AND THE BEST FORCING. SHOWERS HAVE BECOME MORE
NUMEROUS THROUGH THE MORNING AND AFTERNOON AS A DECENT 300MB JET
STREAK MOVED OVER THE STATE...WITH NORTHEAST WISCONSIN SITTING IN
THE RIGHT REAR QUAD. EVEN THOUGH SFC WINDS WERE OUT OF THE EAST TO
NORTHEAST...THIS MORNINGS 12Z SOUNDING OUT OF GRB AND DVN SHOWED
SOUTHWEST FLOW ALOFT...WHICH HELPED CONTINUE TO PUMP MOISTURE
INTO SOUTHERN PORTIONS OF THE CWA. PRECIPITABLE WATER VALUES IN
THIS AREA INCREASED THROUGH THE MORNING AND OCCASIONAL MODERATE TO
HEAVY RAIN WAS REPORTED IN SOME LOCATIONS JUST SOUTH OF OSHKOSH
AND FDL. FURTHER NORTH...SKIES REMAINED CLOUDY BUT NO PRECIP WAS
REPORTED. EXPECT SHOWERS AND ISOLATED THUNDERSTORMS TO CONTINUE TO
PUSH NORTH AND OVERSPREAD THE AREA THROUGH THE REST OF THE
AFTERNOON...WITH PORTIONS OF EASTERN AND CENTRAL WISCONSIN SEEING
OCCASIONAL MODERATE TO HEAVY RAINFALL AS THE BEST FORCING MOVES
THROUGH THE STATE WITH THE MAIN UPPER LEVEL TROUGH.
&&
.SHORT TERM...TONIGHT AND THURSDAY
ISSUED AT 233 PM CDT WED MAY 22 2013
MAIN FORECAST CONCERN WILL BE PRECIPITATION TRENDS TONIGHT AND
EARLY THURSDAY MORNING. OTHERWISE...SKIES WILL CLEAR FROM
NORTHWEST TO SOUTHEAST AS HIGH PRESSURE MOVES IN FROM CANADA ON
THURSDAY.
PRECIPITATION SHOULD OVERSPREAD THE ENTIRE AREA LATE THIS
AFTERNOON...REACHING THE UPPER PENINSULA BORDER BY 21Z-00Z.
GENERALLY SHOWERY CONDITIONS WILL PERSIST THROUGH THE EARLY
OVERNIGHT HOURS FOR THE CWA...WITH SOME MODERATE RAIN POSSIBLE IN
EASTERN WISCONSIN. THERE HAS BEEN A CONSISTENT SIGNAL FROM THE
MODELS FOR STRONG FORCING 21Z TODAY THROUGH 03Z TONIGHT IN CENTRAL
AND EAST CENTRAL WISCONSIN...AND EXPECT THIS TIME FRAME TO BE WHEN
WE WILL SEE THE HEAVIEST AND MOST WIDESPREAD RAINFALL. BUMPED UP
QPF A LITTLE IN EASTERN WISCONSIN FROM 00Z TO 06Z THURSDAY TO
ACCOUNT FOR POSSIBLE HEAVIER SHOWERS WITH THIS FORCING. CONTINUED
TO KEEP ISOLATED THUNDER IN THE FCST UNTIL 03Z THURSDAY AS
WELL...AT WHICH POINT ANY LINGERING MU-CAPE OVER 500 J/KG WILL
DISSIPATE AND THE BEST FORCING WILL MOVE AWAY FROM WISCONSIN...SO
PRECIPITATION WILL BE MAINLY SHOWERS.
DRY AIR WILL RUSH IN BEHIND THE UPPER LEVEL SYSTEM LATE TONIGHT
AND SHOULD QUICKLY USHER OUT PRECIPITATION. THIS COMBINED WITH
STRONG SUBSIDENCE WILL RESULT IN SHOWERS ENDING IN FAR NW PORTIONS
OF THE CWA AROUND MIDNIGHT. THIS TREND WILL CONTINUE FROM
NORTHWEST TO SOUTHEAST THROUGH THE EARLY MORNING HOURS BEFORE THE
LAST OF THE PRECIP EXITS THE LAKESHORE AROUND 15Z THURSDAY. SPED
UP THE EXIT OF PRECIP/CLOUDS A BIT FROM THE PREVIOUS FORECAST DUE
TO MODEL TRENDS...OTHERWISE MADE FEW CHANGES TO WHAT WE HAD GOING
BEFORE. TEMPERATURES WILL BE CHILLY ON THURSDAY AS STRONG COLD AIR
ADVECTION ALOFT SETS UP AND GUSTY NORTH WINDS DEVELOP.
.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 233 PM CDT WED MAY 22 2013
MAIN FCST CONCERNS INCLUDE FROST/FREEZE POTENTIAL ON THURSDAY NIGHT...
WHETHER OR NOT TO INCLUDE PCPN CHANCES FOR THE HOLIDAY WEEKEND...AND
TEMPERATURES THROUGHOUT THE PERIOD.
HUDSON BAY HIGH PRESSURE WILL RESIDE OVER THE REGION FOR THE END
OF THE WORK WEEK...AND THROUGH THE HOLIDAY WEEKEND. A VERY DRY AIR MASS
WILL BE IN PLACE THURSDAY NIGHT...WITH PRECIPITABLE WATER VALUES
DROPPING TO 0.25 TO 0.33 INCH. CLEAR SKIES AND LIGHT WINDS WILL ALLOW
TEMPERATURES TO PLUMMET TO BLO FREEZING ACROSS MOST OF NC/FAR NE WI...
WITH READINGS POSSIBLY APPROACHING 20 DEGREES IN THE TYPICAL COLD SPOTS.
WILL ISSUE A FREEZE WATCH FOR NC/FAR NE WI...WHERE FREEZING TEMPS ARE
LIKELY. AN SPS WILL BE ISSUED FOR THE REST OF THE CWA...WHERE PATCHY/
AREAS OF FROST ARE A GOOD BET. WILL NEED TO WATCH CENTRAL WI
CLOSELY...AS FCST MIN TEMPS ARE CLOSE TO FREEZING.
THE LARGE HIGH PRESSURE WILL ONLY DRIFT SLIGHTLY TO THE EAST OVER THE
HOLIDAY WEEKEND...WITH THE RIDGE AXIS SETTING UP JUST TO OUR EAST.
THE ECMWF HAS BEEN CONSISTENT IN KEEPING ANY PCPN TO OUR WEST AND SOUTH
THROUGH THE WEEKEND...WHILE THE GFS/GEFS ATTEMPT TO BRING SOME LGT
QPF INTO OUR SW COUNTIES BY ABOUT SUNDAY. HAVE KEPT THE FCST DRY
THROUGH SUNDAY...AND ONLY MENTIONED A SLIGHT CHANCE OF SHOWERS FROM
SUNDAY NIGHT INTO TUESDAY. TEMPERATURES WILL REMAIN A LITTLE BLO
NORMAL THROUGH THE WEEKEND...WITH HIGHS IN THE 60S.
A WARM FRONT IS EXPECTED TO LIFT NORTH INTO THE REGION TUESDAY NIGHT
AND WEDNESDAY...AND MAY BRING A CHANCE OF THUNDERSTORMS AND MILDER
TEMPS TO THE FORECAST AREA.
&&
.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 713 PM CDT WED MAY 22 2013
SLOW MOVING AREA OF IFR CIGS AND BROKEN AREA OF LIGHT
RAIN ASSOCIATED WITH DEFORMATION ZONE WILL PERSIST OVER THE
FORECAST AREA THIS EVENING. HOWEVER...WATER VAPOR IMAGERY OVER THE
PAST SEVERAL HOURS INDICATES THAT SURGE OF DRIER AIR OVER CENTRAL
MINNESOTA TO THE DAKOTAS...ASSOCIATED WITH STRENGTHENING NORTHERLY
UPPER-LEVEL FLOW AND SUBSIDENCE...WILL WORK TO GRAUDUALLY ERODE
DEFORMATION ZONE PRECIPITATION TOWARD MIDNIGHT.
RADAR TRENDS LAST COUPLE HOURS SUPPORT THIS AS PRECIPTATION AREA
HAS BEEN SLOWLY WEAKENING AND BECOMING INCREASINGLY DISORGANIZED
FROM GREEN BAY...WEST TO CENTRAL WISCONSIN. LATEST HRRR FORECAST
SEEMS TO HAVE A GOOD HANDLE ON SHORT-TERM TRENDS AND PUSHES
PRECIPTATION AREA SOUTHEAST OF THE FORECAST AREA BY AROUND 10Z OR
SO. EXPECT IFR CIGS TO GRADUALLY IMPROVE TO MVFR AFTER MIDNIGHT
FROM NORTHWEST TO SOUTHEAST...WITH VFR CONDTIONS TO FOLLOW AFTER
15Z THURSDAY. NORTHEAST WINDS EXPECTED TO INCREASE AFTER MIDNIGHT
ESPECIALLY OVER THE FOX VALLEY...WITH GUSTS OF 20 TO 25 KTS
EXPCETED FROM GRB SOUTHWEST TO ATW AND OSH BY 12Z.
&&
.MARINE...
ISSUED AT 233 PM CDT WED MAY 22 2013
HIGH-END SMALL CRAFT ADVISORY ISSUED FOR THIS AFTERNOON THROUGH AT
LEAST FRIDAY FOR GUSTY NORTH TO NORTHEAST WINDS. GUSTS WILL GET
CLOSE TO GALE FORCE TOMORROW LATE MORNING AND EARLY AFTERNOON...
HOWEVER THE BEST MIXING WILL OCCUR AFTER THE STRONGER WINDS OFF
THE SFC BEGIN TO DISSIPATE. SO WILL KEEP THE STRONG WORDED SMALL
CRAFT ADVISORY WITH JUST A MENTION OF A FEW GALE FORCE GUSTS
POSSIBLE. PERSISTENT MARINE FOG HAS BEGUN TO LIFT AND VISIBILITIES
ARE COMING UP THIS AFTERNOON AS WINDS INCREASE. KEPT PATCHY FOG IN
THE FORECAST UNTIL 03Z THURSDAY...BUT AT THIS POINT DEW POINT
DEPRESSIONS AND WINDS INCREASE AND FOG SHOULD NO LONGER BE AN
ISSUE. WILL REMOVE FOG MENTION FROM THE MWW.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
FREEZE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY MORNING FOR
WIZ005-010>013-018-019-021.
&&
$$
UPDATE.........ESB
SYNOPSIS.......WOLF
SHORT TERM.....WOLF
LONG TERM......KIECKBUSCH
AVIATION.......ESB
MARINE.........WOLF
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
716 PM CDT WED MAY 22 2013
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SYNOPSIS...
ISSUED AT 233 PM CDT WED MAY 22 2013
UPPER LEVEL SYSTEM THAT HAS BEEN SITTING OVER THE NORTHERN PLAINS
THE PAST FEW DAYS WAS FINALLY MOVING EAST...WITH THE SFC LOW
PRESSURE SLIDING THROUGH SOUTHERN WISCONSIN THIS AFTERNOON PER
MSAS ANALYSIS. THIS SFC LOW...COMBINED WITH ENERGY FROM A POTENT
SHORTWAVE THAT WAS SWINGING AROUND THE SOUTHEAST SIDE OF THE
UPPER LEVEL TROUGH INTO THE GREAT LAKES AREA...RESULTED IN
WIDESPREAD SHOWERS THIS AFTERNOON. SOME LIGHTNING WAS ALSO
DETECTED IN THIS AREA OF PRECIP...MAINLY IN THE VICINITY OF A NOSE
OF MINOR MU-CAPES AND THE BEST FORCING. SHOWERS HAVE BECOME MORE
NUMEROUS THROUGH THE MORNING AND AFTERNOON AS A DECENT 300MB JET
STREAK MOVED OVER THE STATE...WITH NORTHEAST WISCONSIN SITTING IN
THE RIGHT REAR QUAD. EVEN THOUGH SFC WINDS WERE OUT OF THE EAST TO
NORTHEAST...THIS MORNINGS 12Z SOUNDING OUT OF GRB AND DVN SHOWED
SOUTHWEST FLOW ALOFT...WHICH HELPED CONTINUE TO PUMP MOISTURE
INTO SOUTHERN PORTIONS OF THE CWA. PRECIPITABLE WATER VALUES IN
THIS AREA INCREASED THROUGH THE MORNING AND OCCASIONAL MODERATE TO
HEAVY RAIN WAS REPORTED IN SOME LOCATIONS JUST SOUTH OF OSHKOSH
AND FDL. FURTHER NORTH...SKIES REMAINED CLOUDY BUT NO PRECIP WAS
REPORTED. EXPECT SHOWERS AND ISOLATED THUNDERSTORMS TO CONTINUE TO
PUSH NORTH AND OVERSPREAD THE AREA THROUGH THE REST OF THE
AFTERNOON...WITH PORTIONS OF EASTERN AND CENTRAL WISCONSIN SEEING
OCCASIONAL MODERATE TO HEAVY RAINFALL AS THE BEST FORCING MOVES
THROUGH THE STATE WITH THE MAIN UPPER LEVEL TROUGH.
&&
.SHORT TERM...TONIGHT AND THURSDAY
ISSUED AT 233 PM CDT WED MAY 22 2013
MAIN FORECAST CONCERN WILL BE PRECIPITATION TRENDS TONIGHT AND
EARLY THURSDAY MORNING. OTHERWISE...SKIES WILL CLEAR FROM
NORTHWEST TO SOUTHEAST AS HIGH PRESSURE MOVES IN FROM CANADA ON
THURSDAY.
PRECIPITATION SHOULD OVERSPREAD THE ENTIRE AREA LATE THIS
AFTERNOON...REACHING THE UPPER PENINSULA BORDER BY 21Z-00Z.
GENERALLY SHOWERY CONDITIONS WILL PERSIST THROUGH THE EARLY
OVERNIGHT HOURS FOR THE CWA...WITH SOME MODERATE RAIN POSSIBLE IN
EASTERN WISCONSIN. THERE HAS BEEN A CONSISTENT SIGNAL FROM THE
MODELS FOR STRONG FORCING 21Z TODAY THROUGH 03Z TONIGHT IN CENTRAL
AND EAST CENTRAL WISCONSIN...AND EXPECT THIS TIME FRAME TO BE WHEN
WE WILL SEE THE HEAVIEST AND MOST WIDESPREAD RAINFALL. BUMPED UP
QPF A LITTLE IN EASTERN WISCONSIN FROM 00Z TO 06Z THURSDAY TO
ACCOUNT FOR POSSIBLE HEAVIER SHOWERS WITH THIS FORCING. CONTINUED
TO KEEP ISOLATED THUNDER IN THE FCST UNTIL 03Z THURSDAY AS
WELL...AT WHICH POINT ANY LINGERING MU-CAPE OVER 500 J/KG WILL
DISSIPATE AND THE BEST FORCING WILL MOVE AWAY FROM WISCONSIN...SO
PRECIPITATION WILL BE MAINLY SHOWERS.
DRY AIR WILL RUSH IN BEHIND THE UPPER LEVEL SYSTEM LATE TONIGHT
AND SHOULD QUICKLY USHER OUT PRECIPITATION. THIS COMBINED WITH
STRONG SUBSIDENCE WILL RESULT IN SHOWERS ENDING IN FAR NW PORTIONS
OF THE CWA AROUND MIDNIGHT. THIS TREND WILL CONTINUE FROM
NORTHWEST TO SOUTHEAST THROUGH THE EARLY MORNING HOURS BEFORE THE
LAST OF THE PRECIP EXITS THE LAKESHORE AROUND 15Z THURSDAY. SPED
UP THE EXIT OF PRECIP/CLOUDS A BIT FROM THE PREVIOUS FORECAST DUE
TO MODEL TRENDS...OTHERWISE MADE FEW CHANGES TO WHAT WE HAD GOING
BEFORE. TEMPERATURES WILL BE CHILLY ON THURSDAY AS STRONG COLD AIR
ADVECTION ALOFT SETS UP AND GUSTY NORTH WINDS DEVELOP.
.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 233 PM CDT WED MAY 22 2013
MAIN FCST CONCERNS INCLUDE FROST/FREEZE POTENTIAL ON THURSDAY NIGHT...
WHETHER OR NOT TO INCLUDE PCPN CHANCES FOR THE HOLIDAY WEEKEND...AND
TEMPERATURES THROUGHOUT THE PERIOD.
HUDSON BAY HIGH PRESSURE WILL RESIDE OVER THE REGION FOR THE END
OF THE WORK WEEK...AND THROUGH THE HOLIDAY WEEKEND. A VERY DRY AIR MASS
WILL BE IN PLACE THURSDAY NIGHT...WITH PRECIPITABLE WATER VALUES
DROPPING TO 0.25 TO 0.33 INCH. CLEAR SKIES AND LIGHT WINDS WILL ALLOW
TEMPERATURES TO PLUMMET TO BLO FREEZING ACROSS MOST OF NC/FAR NE WI...
WITH READINGS POSSIBLY APPROACHING 20 DEGREES IN THE TYPICAL COLD SPOTS.
WILL ISSUE A FREEZE WATCH FOR NC/FAR NE WI...WHERE FREEZING TEMPS ARE
LIKELY. AN SPS WILL BE ISSUED FOR THE REST OF THE CWA...WHERE PATCHY/
AREAS OF FROST ARE A GOOD BET. WILL NEED TO WATCH CENTRAL WI
CLOSELY...AS FCST MIN TEMPS ARE CLOSE TO FREEZING.
THE LARGE HIGH PRESSURE WILL ONLY DRIFT SLIGHTLY TO THE EAST OVER THE
HOLIDAY WEEKEND...WITH THE RIDGE AXIS SETTING UP JUST TO OUR EAST.
THE ECMWF HAS BEEN CONSISTENT IN KEEPING ANY PCPN TO OUR WEST AND SOUTH
THROUGH THE WEEKEND...WHILE THE GFS/GEFS ATTEMPT TO BRING SOME LGT
QPF INTO OUR SW COUNTIES BY ABOUT SUNDAY. HAVE KEPT THE FCST DRY
THROUGH SUNDAY...AND ONLY MENTIONED A SLIGHT CHANCE OF SHOWERS FROM
SUNDAY NIGHT INTO TUESDAY. TEMPERATURES WILL REMAIN A LITTLE BLO
NORMAL THROUGH THE WEEKEND...WITH HIGHS IN THE 60S.
A WARM FRONT IS EXPECTED TO LIFT NORTH INTO THE REGION TUESDAY NIGHT
AND WEDNESDAY...AND MAY BRING A CHANCE OF THUNDERSTORMS AND MILDER
TEMPS TO THE FORECAST AREA.
&&
.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 713 PM CDT WED MAY 22 2013
SLOW MOVING AREA OF IFR CIGS AND BROKEN AREA OF LIGHT
RAIN ASSOCIATED WITH DEFORMATION ZONE WILL PERSIST OVER THE
FORECAST AREA THIS EVENING. HOWEVER...WATER VAPOR IMAGERY OVER THE
PAST SEVERAL HOURS INDICATES THAT SURGE OF DRIER AIR OVER CENTRAL
MINNESOTA TO THE DAKOTAS...ASSOCIATED WITH STRENGTHENING NORTHERLY
UPPER-LEVEL FLOW AND SUBSIDENCE...WILL WORK TO GRAUDUALLY ERODE
DEFORMATION ZONE PRECIPITATION TOWARD MIDNIGHT.
RADAR TRENDS LAST COUPLE HOURS SUPPORT THIS AS PRECIPTATION AREA
HAS BEEN SLOWLY WEAKENING AND BECOMING INCREASINGLY DISORGANIZED
FROM GREEN BAY...WEST TO CENTRAL WISCONSIN. LATEST HRRR FORECAST
SEEMS TO HAVE A GOOD HANDLE ON SHORT-TERM TRENDS AND PUSHES
PRECIPTATION AREA SOUTHEAST OF THE FORECAST AREA BY AROUND 10Z OR
SO. EXPECT IFR CIGS TO GRADUALLY IMPROVE TO MVFR AFTER MIDNIGHT
FROM NORTHWEST TO SOUTHEAST...WITH VFR CONDTIONS TO FOLLOW AFTER
15Z THURSDAY. NORTHEAST WINDS EXPECTED TO INCREASE AFTER MIDNIGHT
ESPECIALLY OVER THE FOX VALLEY...WITH GUSTS OF 20 TO 25 KTS
EXPCETED FROM GRB SOUTHWEST TO ATW AND OSH BY 12Z.
&&
.MARINE...
ISSUED AT 233 PM CDT WED MAY 22 2013
HIGH-END SMALL CRAFT ADVISORY ISSUED FOR THIS AFTERNOON THROUGH AT
LEAST FRIDAY FOR GUSTY NORTH TO NORTHEAST WINDS. GUSTS WILL GET
CLOSE TO GALE FORCE TOMORROW LATE MORNING AND EARLY AFTERNOON...
HOWEVER THE BEST MIXING WILL OCCUR AFTER THE STRONGER WINDS OFF
THE SFC BEGIN TO DISSIPATE. SO WILL KEEP THE STRONG WORDED SMALL
CRAFT ADVISORY WITH JUST A MENTION OF A FEW GALE FORCE GUSTS
POSSIBLE. PERSISTENT MARINE FOG HAS BEGUN TO LIFT AND VISIBILITIES
ARE COMING UP THIS AFTERNOON AS WINDS INCREASE. KEPT PATCHY FOG IN
THE FORECAST UNTIL 03Z THURSDAY...BUT AT THIS POINT DEW POINT
DEPRESSIONS AND WINDS INCREASE AND FOG SHOULD NO LONGER BE AN
ISSUE. WILL REMOVE FOG MENTION FROM THE MWW.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
FREEZE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY MORNING FOR
WIZ005-010>013-018-019-021.
&&
$$
SYNOPSIS.......WOLF
SHORT TERM.....WOLF
LONG TERM......KIECKBUSCH
AVIATION.......ESB
MARINE.........WOLF
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1151 AM CDT TUE MAY 21 2013
.AVIATION/18Z TAFS/...LIMITED CONVECTIVE POTENTIAL WITH LACK OF
FORCING AND DRY AIR ADVECTION IN LOW LEVELS AS WINDS START TO
SHIFT SW. ISOLATED DEVELOPMENT NORTH OF THE CWA WILL CONTINUE TO
PULL AWAY TO THE NE. THIS WAS IN AGREEMENT WITH LATEST HRRR RUN.
EVERYTHING PRETTY MUCH SHUTS DOWN WITH CU FIELD FILLING IN FROM
IA AND NW IL. SOME CEILINGS ARE MVFR WITHIN THIS CLOUD FIELD. MORE
SHRA AND LOWER CEILINGS ON WEDNESDAY AS LOW DEVELOPS AND MOVES TO
OUR SOUTH AND EAST.
PC
&&
.PREV DISCUSSION... /ISSUED 537 AM CDT TUE MAY 21 2013/
TODAY AND TONIGHT...FORECAST CONFIDENCE MEDIUM
AREAS OF STRATUS WILL PREVAIL EARLY THIS MORNING WITH SOME CLEARING
BY MID TO LATE MORNING. THIS WILL AID DAYTIME HEATING AND
INSTABILITY FOR LATE THIS MORNING AND AFTERNOON. VARIOUS MODEL
SOUNDINGS VARY WITH EXPECTED CAPE VALUES FROM VERY LITTLE UP TO 1000
J/KG. THIS HAS TO DO WITH DIFFERENCES IN MID LEVEL LAPSE RATES AND
DEWPOINTS. WILL COUNT ON MARGINAL CAPE PERHAPS UP TO 500 J/KG.
TRIGGERS FOR CONVECTION TODAY ARE WEAK WITH A COUPLE WEAK VORTICITY
MAXIMUMS TO SWING NWD IN THE SLY FLOW ALOFT OF THE UPPER LOW. A WEAK
SFC TROUGH MAY ALSO BECOME PRESENT AS SLY WINDS TURN MORE WLY. WILL
GO WITH CHANCES OF TSTORMS FROM LATE AM THROUGH THE AFTERNOON. LOW
PROBABILITIES OF SEVERE WX WILL BE POSSIBLE GIVEN MDT DEEP LAYER
SHEAR AND MID LEVEL DRY AIR.
THE UPPER LOW WILL FINALLY BEGIN TO MOVE SEWD INTO WRN IA BY 12Z
WED. THE FORWARD TILT UPPER TROUGH WILL BECOME MORE NEGATIVE TILT
WITH SATURATION AND RAIN POSSIBLE IN FAR SE WI BY 12Z.
WEDNESDAY AND WEDNESDAY NIGHT...FORECAST CONFIDENCE MEDIUM.
THE STACKED LOW PRESSURE SYSTEM FINALLY SLIDES INTO THE AREA ON
WEDNESDAY AND PASSES OVERHEAD WEDNESDAY NIGHT. THERE IS IMPRESSIVE
AND RATHER SUSTAINED Q-VECTOR CONVERGENCE THROUGH THE PERIOD WITH
DEEP MOISTURE AVAILABLE. THIS LOOKS LIKE OUR BEST CHANCE FOR A
WIDESPREAD RAINFALL. INSTABILITY IS MARGINAL SO WILL JUST CARRY A
CHANCE FOR STORMS. NO SEVERE WEATHER IS EXPECTED.
WINDS ALSO TURN ONSHORE ACROSS THE SOUTHEAST...SO AREAS CLOSE TO
THE LAKE WILL COOL OFF QUITE A BIT.
THURSDAY AND THURSDAY NIGHT...FORECAST CONFIDENCE IS HIGH.
WILL LINGER A CHANCE FOR RAIN ACROSS THE SOUTHEAST THURSDAY
MORNING AS THE REMNANTS OF THE UPPER LOW PULL AWAY. THEN MUCH
COOLER AND DRIER WEATHER OVERSPREADS THE AREA ON INCREASING
NORTHEAST WINDS AS HIGH PRESSURE BUILDS IN. WE COULD SEE LOWS
THURSDAY NIGHT DIP INTO THE UPPER 30S IN MANY AREAS AS WINDS FALL
OFF WITH THE RIDGE AXIS MOVING OVERHEAD.
FRIDAY AND FRIDAY NIGHT...
COOL AND DRY FOR FRIDAY WITH HIGH PRESSURE HOLDING STRONG.
AS THE RIDGE SLIDES OFF TO THE EAST FRIDAY NIGHT...THE RETURN FLOW
WARM AIR ADVECTION COULD BRING IN SOME LATE NIGHT THUNDERSTORMS.
THIS IS A PRETTY SMALL CHANCE AT THIS POINT.
SATURDAY AND BEYOND...FORCAST CONFIDENCE IS LOW TO MEDIUM.
THE GFS AND THE ECMWF ARE IN DISAGREEMENT WITH THE PATTERN THIS
WEEKEND INTO EARLY NEXT WEEK. THE ECMWF MAINTAINS THE RIDGE OVER
OUR AREA AND THE GREAT LAKES THROUGH NEXT TUESDAY...RESULTING IN
DRY WEATHER. MEANWHILE THE GFS PUSHES A SFC BOUNDARY FARTHER
EAST...ACTING AS A FOCUS FOR SHOWERS AND STORMS THROUGH THE SAME
PERIOD. A BLEND WOULD KEEP ANY RISK FOR STORMS MAINLY OVER OUR FAR
WESTERN CWA...AND THOSE CHANCES LOOK SMALL.
AVIATION/12Z TAFS/...IFR TO MVFR STRATUS HAS FORMED OVER SRN WI AND
SWWD INTO ERN IA. THIS STRATUS WILL LIKELY NOT DISSIPATE UNTIL MID
TO LATE MORNING FOR KMSN. A MUCH LESSER TIME PERIOD OF STRATUS IS
EXPECTED OVER THE SE WI TAF SITES. THE STRATUS SHOULD LIFT INTO
SCT-BKN CUMULUS CONGESTUS OF 4-5 KFT FOR THE AFTERNOON. A WEAK WIND
SHIFT LINE WILL GRADUALLY SHIFT WINDS FROM SLY TO WLY TODAY. THERE
IS A CHANCE OF TSTORMS MAINLY THIS AFTERNOON AS THE WINDS SHIFT.
DRIER AIR WILL ARRIVE ON THE WLY WINDS FOR TNT BUT LOW PRESSURE OVER
IA WILL BRING GOOD CHANCES OF RAIN TO FAR SRN WI INCLUDING KENW
TOWARD SUNRISE WED AM. AREAS OF LIGHT FOG COULD DEVELOP LATE TNT
BEFORE THE CLOUDS AND RAIN CHANCES MOVE BACK INTO THE AREA.
WIDESPREAD RAIN WITH LOW CIGS AND VSBYS IS THEN EXPECTED ON WED.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...GEHRING
WEDNESDAY THROUGH MONDAY...DAVIS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
400 AM CDT TUE MAY 21 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 358 AM CDT TUE MAY 21 2013
AT 345 AM...SHOWERS AND ISOLATED THUNDERSTORMS WERE FOUND ALONG AND
NORTH OF THE INTERSTATE 94 CORRIDOR. THIS PRECIPITATION WAS
CONTINUING TO DEVELOP IN THE RIGHT ENTRANCE REGION OF A 110 KNOT
250 MB JET. THE 21.00Z MESO MODELS ARE IN VERY GOOD AGREEMENT THAT
THE PRECIPITATION WILL CONTINUE TO MOVE NORTHEAST AWAY FROM NORTH
CENTRAL WISCONSIN EARLY THIS MORNING. FURTHER TO THE WEST...A
CLOSED UPPER LEVEL LOW REMAINED OVER THE EASTERN DAKOTAS.
FOR TODAY...THE MESO MODELS ARE IN GOOD AGREEMENT THAT WEAK TO
MODERATE 900-700 MB FRONTOGENESIS WILL REMAIN ACROSS NORTHERN
WISCONSIN AND CENTRAL MINNESOTA. IN ADDITION...THE ML CAPE WILL BE
CLIMBING UP TO 500 J/KG FOR LATE THIS MORNING AND AFTERNOON. THIS
WILL RESULT IN THE DEVELOPMENT OF SHOWERS AND ISOLATED
THUNDERSTORMS ALONG AND NORTH OF THE INTERSTATE 94 CORRIDOR. WITH
0-3 KM AND 0-6 KM SHEAR GENERALLY LESS 25 KNOTS...NO SEVERE
WEATHER IS EXPECTED.
FOR TONIGHT...THE 900-700 MB FRONTOGENESIS WILL PROVIDE A CHANCE
OF SHOWERS AND ISOLATED THUNDERSTORMS CONTINUING NORTH OF THE
INTERSTATE 94 CORRIDOR. MEANWHILE WITH THE CLOSED LOW WILL
APPROACHING THE AREA FROM THE DAKOTAS...AND A SHORT WAVE
TROUGH...CURRENTLY OVER NEW MEXICO...MOVING NORTHEAST ACROSS
NORTHERN ILLINOIS AND SOUTHWEST WISCONSIN WILL RESULT IN ISOLATED
TO SCATTERED SHOWERS MOVING INTO THE REMAINDER OF THE FORECAST
AREA AFTER MIDNIGHT.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 358 AM CDT TUE MAY 21 2013
FROM WEDNESDAY INTO WEDNESDAY NIGHT...THE CLOSED LOW WILL OPEN UP
INTO AN OPEN WAVE AND MOVE EAST THROUGH THE FORECAST AREA. THIS
EVENTUALLY EVOLVED INTO A DEFORMATION BAND OF PRECIPITATION MOVING
EAST THROUGH THE FORECAST AREA. THE HIGHEST PRECIPITATION CHANCES
WILL LIKELY RUN FROM THE LATE MORNING INTO THE EARLY EVENING. WITH
BOTH THE 0-3 KM AND 0-6 KM SHEAR LESS THAN 25 KNOTS...NONE OF THE
THUNDERSTORMS ARE EXPECTED TO BECOME SEVERE.
ON THURSDAY NIGHT...A CANADIAN HIGH PRESSURE SYSTEM WILL USHER IN
DEW POINTS OF AROUND 30 DEGREES INTO CENTRAL AND NORTH CENTRAL
WISCONSIN. IN ADDITION...THE CLEAR SKIES AND LIGHT WINDS WILL
ALLOW FOR VERY GOOD RADIATIVE COOLING. LOW TEMPERATURES ON FRIDAY
MORNING WILL LIKELY FALL INTO THE MID 30S ACROSS THIS REGION.
THERE EVEN COULD BE SOME LOWER 30S IN THE CRANBERRY BOGS OF
CENTRAL WISCONSIN. DUE TO THIS ADDED SOME PATCHY FROST INTO THE
FORECAST FOR THESE AREAS.
ON FRIDAY NIGHT AND SATURDAY MORNING...MODERATE WARM AIR ADVECTION
AND ISENTROPIC LIFT WILL DEVELOP ACROSS SOUTHEAST MINNESOTA...
NORTHEAST IOWA...AND WESTERN WISCONSIN. THIS IS IN RESPONSE TO THE
UPPER LEVEL RIDGE BUILDING TOWARD THE AREA. IN ADDITION...WEAK TO
MODERATE 850 MB MOISTURE TRANSPORT WILL LIKELY RESULT IN THE
DEVELOPMENT OF A MESOSCALE CONVECTIVE COMPLEX ACROSS NORTHWEST
MINNESOTA DURING THE EVENING AND THEN THE SYSTEM WILL MOVE
SOUTHEAST THROUGH OUR AREA FROM THE LATE EVENING INTO SATURDAY
MORNING. WITH PRECIPITABLE WATER VALUES RUNNING AROUND 1.2
INCHES...THERE COULD POTENTIALLY BE SOME BRIEF PERIODS OF HEAVY
RAIN WITH THIS COMPLEX. WHILE THE 0-6KM SHEAR REMAIN LESS THAN
30 KNOTS...THE 0-3KM SHEAR WILL BECOME FAVORABLE ACROSS SOUTHEAST
MINNESOTA AND NORTHEAST IOWA THAT THERE COULD POTENTIALLY BE A
WIND THREAT WITH THESE STORMS.
FROM SATURDAY THROUGH MEMORIAL DAY...THE MODELS CONTINUE TO DIFFER
ON THE LOCATION OF THE CANADIAN HIGH. THE ECMWF CONTINUES TO
SUGGEST THAT THE HIGH WILL KEEP THE AREA DRY THROUGHOUT THIS TIME
PERIOD. MEANWHILE THE GFS...CONTINUES TO KEEP THE HIGH MORE OVER
THE GREAT LAKES AND THIS KEEPS US IN THE ACTIVE AREA ON THE EAST
SIDE OF THE UPPER LEVEL RIDGE. SINCE BOTH MODELS HAVE CHANGED
LITTLE...DECIDED TO JUST STAY WITH THE ALL BLEND FOR NOW.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1202 AM CDT TUE MAY 21 2013
THUNDERSTORM ACTIVITY CONTINUES TO MOVE OFF THE NORTHEAST AHEAD OF
THE SHORT WAVE TROUGH MOVING ACROSS WESTERN IOWA. THE 21.00Z NAM
SHOWS THIS WAVE LIFTING NORTHEAST PAST THE AREA OVERNIGHT AND THE
GENERAL CONSENSUS FROM THE NAM...21.03Z RAP AND HRRR IS THAT THIS
ACTIVITY WILL LIFT NORTHEAST OF THE TAF SITES BY 09Z. PLAN TO
HAVE A TEMPO GROUP FOR THUNDER IN AT KLSE THROUGH 08Z FOLLOWED BY
VCTS FOR A SHORT PERIOD AND JUST CARRY A VCTS AT KRST THROUGH 08Z
AS RADAR SHOWS JUST SCATTERED ACTIVITY BACK ACROSS NORTHERN IOWA.
THE SURFACE LOW ACROSS NORTHEAST SOUTH DAKOTA IS EXPECTED TO MOVE
INTO EASTERN WISCONSIN BY TUESDAY AFTERNOON. THIS WILL ALLOW THE
COLD FRONT TO SWING THROUGH WITH A WIND SWITCH TO THE SOUTHWEST
DURING THE MID TO LATE MORNING. SATELLITE AND SURFACE OBS SHOW
LOTS OF VFR CEILINGS IN PLACE AROUND THE SURFACE LOW SO WILL SHOW
A CEILING AROUND 4K FEET FOR BOTH SITES FOR FROM MID MORNING
THROUGH THE REMAINDER OF THE PERIOD.
&&
.HYDROLOGY...
ISSUED AT 358 AM CDT TUE MAY 21 2013
RAINFALL ON WEDNESDAY AND WEDNESDAY EVENING WILL LIKELY BE LESS
THAN A QUARTER OF AN INCH ACROSS NORTHEAST IOWA AND SOUTHEAST
MINNESOTA. THIS RAINFALL WILL LIKELY JUST SLOW THE FALLS ON AREA
RIVERS AND STREAMS.
ON FRIDAY NIGHT AND SATURDAY...ANOTHER QUARTER TO HALF INCH OF
RAIN WILL LIKELY FALL ACROSS SOUTHEAST MINNESOTA AND NORTHEAST
IOWA. LIKE WEDNESDAY...THIS RAIN WILL LIKELY ONLY SLOW THE FALL ON
AREA RIVERS AND STREAMS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...04
HYDROLOGY...BOYNE
AREA FORECAST DISCUSSION
NWS TOPEKA KS
312 AM CDT THU MAY 23 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 230 AM CDT THU MAY 23 2013
THE OLD UPPER SYSTEM CONTINUES TO SLIDE EAST AND WEAKEN OVER THE
WESTERN GREAT LAKES...WITH 0Z 500MB HEIGHT CHANGE OBSERVATIONS
DEPICTING WEAK TO MODERATE RISES ACROSS THE PLAINS. LOW LEVEL
RIDGING WAS TAKING SHAPE ACROSS THE CENTRAL PLAINS...WITH SOUTH
WINDS TAKING HOLD OVER THE SOUTHERN HIGH PLAINS. A SHRINKING STRATUS
DECK WAS OOZING SOUTH THROUGH NEBRASKA EARLY THIS MORNING.
SHALLOW NATURE TO THE LOW CLOUDS AND INCREASING LOW LEVEL ISENTROPIC
DOWNGLIDE SHOULD ALLOW THE INVADING STRATUS TO DISSIPATE THIS
MORNING THOUGH MORE COULD REDEVELOP WITH DAYTIME HEATING. TEMPS
AGAIN STAY ON THE COOL SIDE WITH NORTH WINDS VEERING TO THE EAST
THROUGH THE DAY. FURTHER VEERING ON TRACK FOR TONIGHT AS LEE LOW
PRESSURE BEGINS TO TAKE SHAPE AND UPPER HEIGHTS CONTINUE TO RISE.
MID LEVEL MOISTURE INCREASES A BIT IN THE WEST WITH MODEST
ISENTROPIC UPGLIDE VIA WEAK WINDS AND ELEVATED CAPE DEVELOPING. THIS
COULD BE ENOUGH TO USHER ANY HIGH PLAINS CONVECTION INTO NORTH
CENTRAL KANSAS LATE TONIGHT...THOUGH CONFIDENCE IN THE FORMER MAKING
IT THIS FAR NORTH IS NOT VERY HIGH.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 230 AM CDT THU MAY 23 2013
DESPITE THE FACT THAT THERE ARE CHANCES FOR PRECIPITATION THROUGH
THE FORECAST FOR FRIDAY THROUGH NEXT WEDNESDAY...REST ASSURED IT
WONT BE RAINING ALL DAY EVERY DAY. CONVECTION IS BEING DRIVEN BY
SMALL WAVES IN THE FLOW THAT ARE DIFFICULT TO TIME...BY THE
NOCTURNAL LLJ...AS WELL AS THE BOUNDARIES THAT THE CONVECTION
LEAVES BEHIND TO REGENERATE CHANCES FOR THE FOLLOWING DAY...AND
OTHER MESOSCALE INTERACTIONS RELATED TO ALL THESE FEATURES. WILL
LIKELY BE ABLE TO TIME PRECIPITATION CHANCES BETTER IN A WINDOW
CLOSER TO THEIR TIME SCALES...BY A MATTER OF A DAY OR TWO RATHER
THAN SEVERAL DAYS OUT.
FIRST FEATURE IS A FRONTAL BOUNDARY DRAPED N/S FROM THE DAKOTAS
INTO NEBRASKA...THE SOUTHERN EDGE OF WHICH CLIPS ACROSS THE
FORECAST AREA THROUGH THE DAY ON FRIDAY. THE FOLLOWING NIGHT LLJ
SLIDES CONVECTION ALONG THE NORTH AND TO THE NE OF THE CWA AND MAY
RUN THROUGH OUR NORTHERN COUNTIES. BOUNDARY FROM THIS MCS COULD THEN
LAY UP ACROSS THE AREA ON SATURDAY AFTERNOON AND REGENERATE
STORMS...WITH YET ANOTHER WEAK WAVE RIDING ACROSS WRN/CTRL KS AND
BRINGING ANOTHER CHANCE FOR TS SATURDAY NIGHT INTO SUNDAY MORNING.
MAY CATCH A BREAK BETWEEN WAVES ON SUNDAY AFTERNOON BEFORE
POTENTIAL FOR ANOTHER WAVE TO LIFT ACROSS THE WRN THRU NORTHERN
COUNTIES INTO MONDAY. SOME SUGGESTION THAT RIDGE AMPLIFIES TUESDAY
INTO WEDNESDAY IN THE ECMWF...ALTHOUGH GFS AMPLIFIES IT FARTHER TO
THE EAST OF OUR FA AND KEEPS THE DAMP PATTERN GOING FOR ANOTHER
DAY. AFTER A COOLER DAY IN THE 70S ON FRIDAY...AS SFC RIDGE SHIFTS
EAST AND WAA RETURNS...SHOULD SE A SHIFT BACK TOWARD THE LOWER 80S
FOR HIGHS ACROSS THE AREA. IF THE RIDGE CAN AMPLIFY...MAY SEE
WARMER TEMPS TOWARD LATER NEXT WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1122 PM CDT WED MAY 22 2013
THE RAP AND NAM CONTINUE TO SHOW THE POTENTIAL FOR MVFR CIGS
MOVING IN FROM THE NORTH BY 12Z. THEREFORE FORECAST THINKING IS
UNCHANGED. CIGS SHOULD GRADUALLY IMPROVE BY NOON WITH THE
POTENTIAL FOR A STRATOCU DECK PERSISTING THROUGH A GOOD PORTION OF
THE DAY. SFC WINDS WILL GRADUALLY VEER WITH RIDGING NOSING IN.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...65
LONG TERM...67
AVIATION...WOLTERS
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
104 AM CDT THU MAY 23 2013
...AVIATION SECTION UPDATED FOR 06Z TAFS...
.SYNOPSIS...
ISSUED AT 340 PM CDT WED MAY 22 2013
THE 12Z UPPER AIR ANALYSIS SHOWED THE REMAINS OF THE NORTHERN PLAINS
CLOSED LOW WEAKENING OVER SOUTHERN MINNESOTA AS IT IS GETTING PHASED
WITH A STRONG SHORTWAVE TROUGH OVER HUDSON`S BAY. A DEEP CLOSED LOW
WAS OVER THE PACIFIC NORTHWEST. IN BETWEEN THESE FEATURES, WEAK
UPPER LEVEL RIDGING EXTENDED FROM CENTRAL CANADA SOUTHWARD ALONG THE
EASTERN SLOPES OF THE ROCKIES AND ADJACENT HIGH PLAINS.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 340 PM CDT WED MAY 22 2013
THE UPPER LOW WILL CONTINUE TO FILL AS IT MOVES INTO THE GREAT
LAKES ON THURSDAY. AS IT MOVES OUT, A SHORTWAVE TROUGH WILL ROTATE
AROUND THE WEST PART OF THE UPPER LOW, WHICH WILL HELP PUSH A COLD
FRONT SOUTH INTO THE CENTRAL HIGH PLAINS TONIGHT. A WEAK DISTURBANCE
WAS EVIDENT IN THE WATER VAPOR IMAGERY MOVING OUT OF THE FOUR
CORNERS REGION THIS AFTERNOON. THE MODELS ARE NOT PICKING UP ON
THIS FEATURE VERY WELL. THEY DO SHOW SOME WARM AIR ADVECTION
DEVELOPING AHEAD OF IT OVER WESTERN KANSAS TONIGHT ALONG WITH SOME
VERY WEAK ELEVATED INSTABILITY ATOP THE COLD FRONT AND LOW LEVEL
COLD ADVECTION THAT WILL BE MOVING INTO WESTERN KANSAS THIS EVENING.
THE HRRR IS STARTING TO SHOW CONVECTION DEVELOPING OVER EASTERN
COLORADO THIS EVENING WORKING INTO WESTERN KANSAS OVERNIGHT. LOW
STRATUS IS ALSO EXPECTED TO DEVELOP BEHIND THE FRONT TONIGHT.
ON THURSDAY, SMALL CHANCES FOR SHOWERS AND THUNDERSTORMS WILL MOVE
INTO CENTRAL KANSAS WHERE THE BEST, ALBEIT WEAK, ELEVATED INSTABILITY
WILL BE. AREAS FARTHER WEST WILL BE CLOUDY TO MOSTLY CLOUDY BUT
STABLE ALOFT. HIGH TEMPERATURES WILL STRUGGLE INTO THE LOW 70S IN
MOST AREAS GIVEN THE CLOUD COVER. AREAS ALONG THE OKLAHOMA BORDER
COULD REACH THE LOW/MID 70S.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 348 PM CDT WED MAY 22 2013
LOW LEVEL MOISTURE WILL SURGE BACK TO THE NORTHWEST INTO THE
SOUTHERN PLAINS BY LATE THURSDAY AS UPPER LEVEL TROUGHING DEVELOPS
ACROSS THE WESTERN UNITED STATES. SURGE HIGH PRESSURE WILL SLIDE
SOUTHEASTWARD INTO THE MIDWEST. A WARM ADVECTION PATTERN WILL
STRENGTHEN THURSDAY NIGHT AND SOME ELEVATED THUNDERSTORM ACTIVITY
IS POSSIBLE. THE UPPER LEVEL RIDGE AXIS BETWEEN THE WESTERN AND
EASTERN UNITED STATES TROUGHS WILL BE OVER THE CENTRAL PLAINS BY
FRIDAY. BUT SOME MID LEVEL FLOW COMING THROUGH THE RIDGE WILL
ALLOW FOR LEE TROUGHING AND A SURGE OF MOISTURE FROM THE SOUTHERN
PLAINS INTO KANSAS. WESTERN KANSAS WILL BE ON THE SOUTHERN EDGE OF
THE WESTERLIES AND THE UPPER LEVEL WINDS WILL NOT BE THAT
IMPRESSIVE. HOWEVER, WITH 2000-3000 J/KG CAPE AND STRONG
DIRECTIONAL TURNING, A FEW SEVERE THUNDERSTORMS ARE POSSIBLE,
PARTICULARLY IN FAR SOUTHWEST KANSAS. HIGH TEMPERATURES FRIDAY WILL
RANGE FROM THE UPPER 70S NEAR HAYS TO THE UPPER 80S IN FAR
SOUTHWEST KANSAS CLOSER TO THE LEE TROUGH.
UPPER LEVEL TROUGHING WILL REMAIN ACROSS THE WESTERN UNITED STATES
THROUGH MID NEXT WEEK, ALTHOUGH THERE IS SOME UNCERTAINTY IN HOW
FAR EAST IT WILL PROGRESS. THE ECMWF IS LESS PROGRESSIVE THAN THE
OTHER MODELS AND GENERALLY A LESS PROGRESSIVE SOLUTION IS THE BEST
ONE. FOR SATURDAY INTO MONDAY, MODERATE TO HIGH SURFACE BASED CAPE
WILL BE IN PLACE AHEAD OF A DRYLINE. A FEW THUNDERSTORMS WILL
DEVELOP EACH DAY ALONG THE DRYLINE AND SLOWLY MOVE EASTWARD. THESE
STORMS COULD BE SEVERE WITH LARGE HAIL AND DAMAGING WINDS. THE
UPPER LEVEL WINDS ARE STILL NOT PROGGED TO BE THAT STRONG, SO
TORNADIC STORMS ARE NOT EXPECTED, BUT CANNOT BE RULED OUT GIVEN THE
STRONG INSTABILITY. TEMPERATURES WILL BE FAIRLY WARM THROUGH THE
EXTENDED WITH LOWS IN THE 60S AND HIGHS IN THE 80S AND 90S SINCE
KANSAS WILL BE IN THE WARM SECTOR. THE WARMEST HIGH TEMPERATURES
OUGHT TO BE IN FAR WESTERN KANSAS BEHIND THE DRYLINE AND THE
WARMEST LOWS SHOULD BE IN SOUTH CENTRAL AND CENTRAL KANSAS WHERE
DEWPOINTS AND WINDS WILL BE HIGHEST.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1257 AM CDT THU MAY 23 2013
A COLD FRONT WILL SLIDE INTO THE HAYS AREA BY 10Z AND INTO GCK AND
DDC BY 12Z. AT THE SAME TIME A WARM FRONT ACROSS WEST AND CENTRAL
TEXAS WILL LIFT NORTH INTO THE TX PANHANDLE DURING THE OVERNIGHT
PERIOD. MOISTENING EASTERLY WINDS HAVE COMMENCED AND WILL BE
REINFORCED BEHIND THE AFOREMENTIONED COLD FRONT. THERE WAS ALREADY
STRATUS BEHIND THE FRONT AND AS THE SURFACE FLOW MOVES WEST INTO
HIGHER TERRAIN STRATUS WILL BEGIN TO FORM SOUTH OF THE FRONT BY
SUNRISE. INITIAL THINKING IS MVFR CEILINGS MAY BE REACHED AT HYS
BY 12Z BUT SHOULD REMAIN HIGHER AT DDC/GCK. I`VE LEFT PCPN OUT OF
THE TERMINALS FOR NOW BUT WILL WATCH FOR ELEVATED DEVELOPMENT
EARLY THIS MORNING AS HIGH RESOLUTION FORECAST MODELS SHOW SOME
ACTIVITY BY SUNRISE AROUND HAYS.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 58 81 63 89 / 40 30 30 30
GCK 58 83 63 91 / 30 40 40 20
EHA 59 88 63 92 / 30 40 30 20
LBL 60 87 64 91 / 30 40 30 20
HYS 56 77 67 89 / 40 40 30 40
P28 59 78 67 86 / 30 40 30 40
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...GERARD
SHORT TERM...GERARD
LONG TERM...FINCH
AVIATION...HUTTON
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1122 PM CDT WED MAY 22 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 354 PM CDT WED MAY 22 2013
THE UPPER LOW ASSOCIATED WITH THIS WEEKEND`S ACTIVE SEVERE WEATHER
WAS SITUATED OVER IOWA THIS AFTERNOON...WITH THE ASSOCIATED SURFACE
LOW PROGRESSING EASTWARD INTO WISCONSIN AND ILLINOIS. CLOUD COVER IN
ASSOCIATION WITH THIS SYSTEM STRETCHED WESTWARD INTO NORTHEAST AND
FAR EASTERN KANSAS THROUGH THE AFTERNOON HOURS...WHICH RESULTED IN
SOMEWHAT COOLER TEMPERATURES ACROSS THE REGION TODAY. WITH THE CLOUD
COVER...AFTERNOON HIGHS PEAKED IN THE MIDDLE TO UPPER 60S. SURFACE
HIGH PRESSURE OVER THE NORTHERN PLAINS WILL HELP TO PUSH THE LOW
PRESSURE SYSTEM EASTWARD TOWARD THE GREAT LAKES REGION AS THE HIGH
SPREADS SOUTHWARD INTO THE CENTRAL PLAINS TONIGHT INTO THURSDAY.
WITH THE EXITING SURFACE LOW...SHOULD START SEEING SOME BREAKS IN THE
CLOUD COVER TONIGHT INTO THE OVERNIGHT HOURS. THIS DIMINISHING CLOUD
COVER WILL ALLOW FOR MORE RADIATIONAL COOLING EARLY THURSDAY MORNING
WITH LOW TEMPERATURES EXPECTED TO BE A FEW DEGREES COOLER THAN
NORMAL...IN THE UPPER 40S TO LOWER 50S.
THE WEAK UPPER LEVEL RIDGE THAT WAS IN PLACE OVER THE CENTRAL
ROCKIES THIS AFTERNOON WILL CONTINUE TO BUILD AS IT PROGRESSES
EASTWARD INTO THE CENTRAL AND SOUTHERN PLAINS BY THURSDAY. MODELS
CONTINUE TO SHOW AN EMBEDDED SHORTWAVE DEVELOPING ALONG THE NORTHERN
EXTENT OF THE RIDGE OVER WESTERN KANSAS AND WESTERN OKLAHOMA...WHICH
MAY BRING SOME SCATTERED SHOWERS AND THUNDERSTORMS TO THAT REGION
THROUGH THE DAY. WHILE THIS ACTIVITY IS EXPECTED TO REMAIN SOUTHWEST
OF THE FORECAST AREA ON THURSDAY...SHOULD STILL HAVE SCATTERED CLOUD
COVER ACROSS MUCH OF THE AREA THROUGH THE DAY. THIS CLOUD COVER
COMBINED WITH NORTHEASTERLY WINDS AROUND THE SURFACE HIGH WILL KEEP
AFTERNOON HIGHS COOLER THAN NORMAL WITH READINGS LIKING PEAKING IN
THE UPPER 60S TO LOWER 70S.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 354 PM CDT WED MAY 22 2013
OVERALL PATTERN WILL FEATURE A FLAT RIDGE WITH INCREASING WAA AND
MOISTURE ADVECTION WHICH WILL SERVE TO PRODUCE SEVERAL BOUTS OF
THUNDERSTORM CHCS. THE INITIAL FORCING IS WEAK THU NIGHT INTO FRI
AND SHOULD STAY FOCUSED ACROSS THE NORTHWEST PARTS OF THE CWA. WILL
KEEP RAIN CHCS LOW AND CONFINED TO AREAS TOPEKA NORTH AND WEST FOR
FRI BUT AGAIN WITHOUT A FOCUS AND GREATER FORCING NOT SURE HOW
WIDESPREAD ANY PRECIP WILL BE FRI.
BY FRI NIGHT INTO SAT THETA-E (MOISTURE AND TEMP ADVECTION) WILL
INCREASE ACROSS KS INTO NEBRASKA. NOSE OF THE 50KT LLJ WILL TARGET
NORTHEAST NEB SO IT WOULD APPEAR THAT THE MAIN COMPLEX OF ANY MCS
WOULD BE LOCATED NORTH OF THE AREA HOWEVER CANNOT RULE OUT SCT
CONVECTION WITHIN THE LLJ AXIS OVERNIGHT INTO EARLY SAT. ANOTHER
WEAK WAVE WILL MOVE ACROSS THE RIDGE SAT NIGHT INTO SUN AND THIS
SHOULD HELP ANOTHER CONVECTIVE COMPLEX DEVELOP ACROSS NE/NORTHERN KS
SO WILL KEEP 20 TO 40 POPS WITH THE HIGHEST ACROSS THE NORTHERN
COUNTIES.
SAME PATTERN WILL PERSIST INTO SUN NIGHT AND MON SO HAVE TO EXPECT
AT LEAST SOME CHCS FOR MAINLY NIGHTTIME THUNDERSTORMS ACROSS THE
AREA SUN NIGHT AND MON AS WEAK WAVES MOVE INTO THE FLATTENING RIDGE
AND COMBINE WITH THE NIGHTTIME LLJ TO FEED OVERNIGHT STORMS.
MON AND BEYOND...IT APPEARS THAT RIDGING SHOULD STRENGTHEN BY TUES
AHEAD OF A DEEPENING TROUGH ACROSS THE WEST. THIS SHOULD LEAD TO
GRADUALLY WARMER TEMPS AND PERHAPS A LULL IN PRECIP CHCS BY MID
WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1122 PM CDT WED MAY 22 2013
THE RAP AND NAM CONTINUE TO SHOW THE POTENTIAL FOR MVFR CIGS
MOVING IN FROM THE NORTH BY 12Z. THEREFORE FORECAST THINKING IS
UNCHANGED. CIGS SHOULD GRADUALLY IMPROVE BY NOON WITH THE
POTENTIAL FOR A STRATOCU DECK PERSISTING THROUGH A GOOD PORTION OF
THE DAY. SFC WINDS WILL GRADUALLY VEER WITH RIDGING NOSING IN.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...HENNECKE
LONG TERM...OMITT
AVIATION...WOLTERS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
255 AM EDT THU MAY 23 2013
.SYNOPSIS...
A TROUGH ALOFT AND ACCOMPANYING PRE-FRONTAL SURFACE PRESSURE TROUGH
WILL SETTLE INTO CENTRAL NC TODAY...FOLLOWED BY THE PASSAGE OF A
COLD FRONT TONIGHT. CANADIAN HIGH PRESSURE WILL THEN EXPAND ACROSS
OUR REGION THROUGH THE HOLIDAY WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1010 PM WEDNESDAY...
ANY SHOWERS AND THUNDERSTORMS FROM THIS AFTERNOON AND EVENING
ASSOCIATED WITH THE SEA BREEZE AND OUTFLOW ACROSS THE EASTERN
TWO-THIRDS OF THE AREA HAVE DISSIPATED WITH THE LOSS OF DAYTIME
HEATING AND RESULTANT STABILIZING BOUNDARY LAYER. CONVECTION THAT
FIRED ACROSS THE HIGHER TERRAIN TODAY... HAS GENERALLY STAYED TO THE
WEST OF THE REGION WITH A 15 TO 20 KT SOUTH-SOUTHWESTERLY MEAN
STEERING FLOW. HOWEVER... A WEST-NORTHWESTERLY OUTFLOW... GENERATED
FROM THESE CLUSTERS OF SHOWERS AND STORMS THAT ORIGINATED ALONG THE
HIGHER TERRAIN... HAS FINALLY ALLOWED FOR THE DEVELOPMENT OF SHOWERS
AND STORMS ACROSS OUR FAR NORTHWESTERN REACHES OF OUR CWA... ALONG
THE OUTFLOW. THINK THIS OUTFLOW SHOULD SUPPORT AT LEAST SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS ACROSS OUR WESTERN PIEDMONT
THROUGH 06/07Z... GIVEN 500 TO 1000 J/KG OF SURFACE BASED CAPE.
THEREAFTER... EXPECT BOUNDARY LAYER COOLING SHOULD YIELD A TREND TO
ISOLATED SHOWERS AT BEST. ANY SIGNIFICANT S/W ENERGY ROTATING
THROUGH THE CYCLONIC FLOW ALOFT FROM THE APPROACHING MID LEVEL
TROUGH WELL TO THE WEST OF THE AREA... INVOF THE MS RIVER THIS
EVENING... IS EXPECTED TO PASS TO THE WEST AND NORTH OF THE REGION
THUS... PLAN TO TRIM POPS TO SLIGHT CHANCE BY EARLY THURSDAY MORNING
ACROSS THE ENTIRE CWA. THIS IS SUPPORTED BY THE LATEST HRRR.
HOWEVER... ITS WORTH NOTING THE LATEST HRRR DOES SHOW SOME SHOWERS
CURRENTLY OFF THE CAROLINA COAST MOVING ONSHORE OVERNIGHT ACROSS THE
COASTAL PLAIN. CURRENT HI-RES MODELS GENERALLY SHOW THIS PRECIP
REMAINING JUST TO THE EAST OF OUR AREA. THUS... WILL KEEP ONLY
SLIGHT CHANCE POPS ACROSS OUR EAST AS WELL. OVERNIGHT LOWS IN THE
MID TO UPPER 60S ARE STILL EXPECTED... WITH GENERALLY PATCHY FOG
(FOG... AT LOCATIONS THAT ARE PICKING UP DECENT SHOWERS/STORMS
ACROSS THE TRIAD NOW) AND WIDESPREAD LOW STATUS.
&&
.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
AS OF 300 PM WEDNESDAY...
A COLD FRONT WILL APPROACH CENTRAL NC FROM THE WEST ON FRIDAY. AS A
DEEP 500 MB TROUGH DIGS SOUTHWARD THROUGH THE OHIO VALLEY. AS FAR AS
TIMING IS CONCERNED...SHOWERS AND THUNDERSTORMS AHEAD OF FRONT WILL
BEGIN TO AFFECT THE TRIAD BY LATE THURSDAY MORNING AND CONTINUE TO
PROGRESS SLOWLY EASTWARD ACROSS THE CWA BY AFTERNOON/EVENING. SEVERE
POTENTIAL WITH THIS SYSTEM WILL BE GREATER THAN THE PAST COUPLE OF
DAYS BUT STILL LOOKS VERY LOW. EFFECTIVE SHEAR WILL BE ABOUT 20
KNOTS SUGGESTING MORE LINEAR THUNDERSTORMS. THIS IS SUPPORTED BY THE
STRAIGHT HODOGRAPHS SHOWN BY NAM FORECAST SOUNDINGS. MID LEVEL LAPSE
RATES WILL BE WEEK ALTHOUGH 1000 ML CAPE OF THE TALL AND SKINNY
VARIETY COULD BE REALIZED BY AFTERNOON. LATER IN THE EVENT DYNAMICS
IMPROVE AS A 30 KNOT 850MB APPROACHES THE NORTHWEST. IT IS UNCLEAR
AT THIS TIME WHETHER OR NOT CONVECTION WILL BE TOO FAR TO THE EAST
TO TAKE ADVANTAGE OF THE INCREASED SHEAR. STORMS LINGERING BACK
TOWARDS THE WEST MAY BE ABLE TO TAKE ADVANTAGE OF AN INCREASED AXIS
OF DCAPE EXPECTED TO MOVE THROUGH THE CWA JUST AFTER 00Z FRIDAY.
THEREFORE IF WE DO ENCOUNTER SEVERE WEATHER TOMORROW...IT WILL MOST
LIKELY BE DAMAGING WINDS AND NOT HAIL. FOR NOW SPC HAS KEPT THE
RALEIGH AREA OUT OF THE SLIGHT RISK AREA FOR TOMORROW. PRECIPITABLE
WATERS WILL BE SIMILAR TO TODAY NEAR 1.5 INCHES BUT QPF WITH FRONTAL
PASSAGE IS ONLY EXPECTED TO BE BETWEEN A QUARTER AND A HALF OF AN
INCH WITH LOCALLY HEAVIER AMOUNTS POSSIBLE IN THUNDERSTORMS.
LOCALIZED FLOODING COULD BE AN ISSUE...ESPECIALLY IN URBAN AREAS
UNDER SLOW MOVING OR TRAINING THUNDERSTORMS. CLOUD COVER SHOULD
OVERSPREAD THE AREA FAIRLY EARLY TOMORROW AND THUS WILL TREND
TOWARDS THE COOLER MET GUIDANCE WITH HIGH TEMPERATURES. UPPER 70S IN
THE NORTHWEST TO LOW 80S SOUTHEAST. AS THE LOWER ATMOSPHERE BEGINS
TO DRY OUT LOW TEMPERATURES IN THE TRIAD SHOULD DIP INTO THE UPPER
50S IN THE NORTHWEST FOR THE FIRST TIME IN SEVERAL DAYS BUT FURTHER
TO THE SOUTHEAST LOWS WILL REMAIN IN THE MIDDLE 60S AS THE FRONT IS
EXPECTED TO FULLY MOVE THROUGH THE EAST UNTIL CLOSER TO 6Z ON FRIDAY.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 255 AM THURSDAY...
SATURDAY AND SUNDAY...
A TERRIFIC WEEKEND IS SHAPING UP AS CANADIAN HIGH PRESSURE WILL
BUILD SOUTH OUT OF THE GREAT LAKES INTO THE EASTERN CONUS. THIS WILL
RESULT IN CLEAR SKIES SATURDAY WITH DRY AND COOLER AIR IN PLACE.
UPPER FLOW WILL BE NORTHWEST AND MODEL CROSS SECTIONS SHOW THAT SOME
HIGH CLOUDINESS COULD MILDLY IMPEDE THE SUNSHINE ON SUNDAY. HIGHS
BOTH DAYS WILL BE MOSTLY IN THE MID 70S. MEANWHILE... SUNDAY
MORNINGS LOW TEMPERATURE WILL BE CONSIDERABLY BELOW NORMAL DUE TO
EXCELLENT RADIATIONAL CONDITIONS...IN THE 45 TO 50 DEGREE RANGE.
MONDAY THROUGH WEDNESDAY....
THE SURFACE HIGH PRESSURE MIGRATES OFFSHORE EARLY NEXT WEEK WHICH
WILL RESULT IN A GRADUAL WARMER AND MOISTER TREND INTO MIDWEEK. WE
WILL BE UNDER A BUILDING LOW AMPLITUDE UPPER RIDGE THROUGH THE
PERIOD WHICH WILL TEND TO SUPPRESS CONVECTION...ESPECIALLY WITH NO
EASILY IDENTIFIABLE FORCING OTHER THAN GENERALLY INCREASING
INSTABILITY WITH LEE TROFFING IN NORTHWEST FLOW AND POTENTIAL FOR
SOME INLAND PENETRATION OF SEA BREEZE CONVECTION IN THE EAST. AS
SUCH...WILL NOT MEDDLE WITH ONGOING SLIGHT CHANCE FOR LATE DAY
CONVECTION MONDAY THROUGH WEDNESDAY. TEMPS WILL BE ON THE UPTICK...
FROM 75 TO 80 ON MONDAY RISING TO 80 TO 85 ON WEDNESDAY...WITH MINS
FOLLOWING A SIMILAR TREND...FROM THE MID 50S MONDAY MORNING TO THE
LOWER 60S WEDNESDAY MORNING.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 205 AM THURSDAY...
A LINE OF SHOWERS AND ISOLATED STORMS THAT EARLIER AFFECTED THE
TRIAD TERMINALS WILL CONTINUE TO MOVE SLOWLY EASTWARD AT AROUND 10
MPH...AFFECTING THE KRDU AREA BETWEEN 8-10Z. A GRADUAL
WEAKENING/DISSIPATING TREND SHOULD OCCUR AS THE AIR MASS CONTINUES
TO STABILIZE WITH NOCTURNAL COOLING...HOWEVER...SO CONFIDENCE OF THE
CONVECTION REACHING THE KFAY AND KRWI AREAS IS LOW. OTHERWISE...A
CONTINUED MOIST AIR MASS WILL PROMOTE A HIGH CHANCE OF LIFR-IFR
CEILINGS THIS MORNING...THOUGH WITH RELATIVE LOWEST CHANCES - AROUND
60 PERCENT - AT TRIAD TERMINALS. THESE CEILINGS WILL LIFT AND
SCATTER TO VFR WITH HEATING THROUGH MIDDAY. HEATING OF THE MOIST AIR
MASS WILL ALSO CAUSE SCATTERED TO NUMEROUS SHOWERS AND STORMS TO
DEVELOP THIS AFTERNOON...AND THESE WILL LIKELY CONTINUE UNTIL A COLD
FRONT SWEEPS ACROSS CENTRAL NC FROM WEST TO EAST BETWEEN 04-06Z AT
TRIAD TERMINALS...TO 09-12Z AT EASTERN ONES. AREAS O FOG OR LOW
STRATUS WILL ALSO BE POSSIBLE AHEAD OF THE COLD FRONT...MOST LIKELY
AT KFAY AND KRWI BETWEEN 06-12Z.
VFR CONDITIONS WILL OTHERWISE PREVAIL IN CANADIAN HIGH PRESSURE
THROUGH THE HOLIDAY WEEKEND.
&&
.CLIMATE...
MORNING LOW TEMPERATURES ON THE 25TH AND 26TH ARE EXPECTED TO BE A
FEW DEGREES SHY OF RECORD MIN TEMPS FOR THE DATE.
RECORD MIN TEMP/YEAR SET MAY 25TH MAY 26TH
RDU 43 / 1967 43 / 1979
GSO 43 / 1956 42 / 1930
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MWS
NEAR TERM...BSD
SHORT TERM...ELLIS
LONG TERM...MLM
AVIATION...MWS
CLIMATE...RAH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
208 AM EDT THU MAY 23 2013
.SYNOPSIS...
A TROUGH ALOFT AND ACCOMPANYING PRE-FRONTAL SURFACE PRESSURE TROUGH
WILL MOVE INTO CENTRAL NC TODAY...FOLLOWED BY THE PASSAGE OF A COLD
FRONT TONIGHT. CANADIAN HIGH PRESSURE WILL THEN EXPAND ACROSS OUR
REGION THROUGH THE HOLIDAY WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1010 PM WEDNESDAY...
ANY SHOWERS AND THUNDERSTORMS FROM THIS AFTERNOON AND EVENING
ASSOCIATED WITH THE SEA BREEZE AND OUTFLOW ACROSS THE EASTERN
TWO-THIRDS OF THE AREA HAVE DISSIPATED WITH THE LOSS OF DAYTIME
HEATING AND RESULTANT STABILIZING BOUNDARY LAYER. CONVECTION THAT
FIRED ACROSS THE HIGHER TERRAIN TODAY... HAS GENERALLY STAYED TO THE
WEST OF THE REGION WITH A 15 TO 20 KT SOUTH-SOUTHWESTERLY MEAN
STEERING FLOW. HOWEVER... A WEST-NORTHWESTERLY OUTFLOW... GENERATED
FROM THESE CLUSTERS OF SHOWERS AND STORMS THAT ORIGINATED ALONG THE
HIGHER TERRAIN... HAS FINALLY ALLOWED FOR THE DEVELOPMENT OF SHOWERS
AND STORMS ACROSS OUR FAR NORTHWESTERN REACHES OF OUR CWA... ALONG
THE OUTFLOW. THINK THIS OUTFLOW SHOULD SUPPORT AT LEAST SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS ACROSS OUR WESTERN PIEDMONT
THROUGH 06/07Z... GIVEN 500 TO 1000 J/KG OF SURFACE BASED CAPE.
THEREAFTER... EXPECT BOUNDARY LAYER COOLING SHOULD YIELD A TREND TO
ISOLATED SHOWERS AT BEST. ANY SIGNIFICANT S/W ENERGY ROTATING
THROUGH THE CYCLONIC FLOW ALOFT FROM THE APPROACHING MID LEVEL
TROUGH WELL TO THE WEST OF THE AREA... INVOF THE MS RIVER THIS
EVENING... IS EXPECTED TO PASS TO THE WEST AND NORTH OF THE REGION
THUS... PLAN TO TRIM POPS TO SLIGHT CHANCE BY EARLY THURSDAY MORNING
ACROSS THE ENTIRE CWA. THIS IS SUPPORTED BY THE LATEST HRRR.
HOWEVER... ITS WORTH NOTING THE LATEST HRRR DOES SHOW SOME SHOWERS
CURRENTLY OFF THE CAROLINA COAST MOVING ONSHORE OVERNIGHT ACROSS THE
COASTAL PLAIN. CURRENT HI-RES MODELS GENERALLY SHOW THIS PRECIP
REMAINING JUST TO THE EAST OF OUR AREA. THUS... WILL KEEP ONLY
SLIGHT CHANCE POPS ACROSS OUR EAST AS WELL. OVERNIGHT LOWS IN THE
MID TO UPPER 60S ARE STILL EXPECTED... WITH GENERALLY PATCHY FOG
(FOG... AT LOCATIONS THAT ARE PICKING UP DECENT SHOWERS/STORMS
ACROSS THE TRIAD NOW) AND WIDESPREAD LOW STATUS.
&&
.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
AS OF 300 PM WEDNESDAY...
A COLD FRONT WILL APPROACH CENTRAL NC FROM THE WEST ON FRIDAY. AS A
DEEP 500 MB TROUGH DIGS SOUTHWARD THROUGH THE OHIO VALLEY. AS FAR AS
TIMING IS CONCERNED...SHOWERS AND THUNDERSTORMS AHEAD OF FRONT WILL
BEGIN TO AFFECT THE TRIAD BY LATE THURSDAY MORNING AND CONTINUE TO
PROGRESS SLOWLY EASTWARD ACROSS THE CWA BY AFTERNOON/EVENING. SEVERE
POTENTIAL WITH THIS SYSTEM WILL BE GREATER THAN THE PAST COUPLE OF
DAYS BUT STILL LOOKS VERY LOW. EFFECTIVE SHEAR WILL BE ABOUT 20
KNOTS SUGGESTING MORE LINEAR THUNDERSTORMS. THIS IS SUPPORTED BY THE
STRAIGHT HODOGRAPHS SHOWN BY NAM FORECAST SOUNDINGS. MID LEVEL LAPSE
RATES WILL BE WEEK ALTHOUGH 1000 ML CAPE OF THE TALL AND SKINNY
VARIETY COULD BE REALIZED BY AFTERNOON. LATER IN THE EVENT DYNAMICS
IMPROVE AS A 30 KNOT 850MB APPROACHES THE NORTHWEST. IT IS UNCLEAR
AT THIS TIME WHETHER OR NOT CONVECTION WILL BE TOO FAR TO THE EAST
TO TAKE ADVANTAGE OF THE INCREASED SHEAR. STORMS LINGERING BACK
TOWARDS THE WEST MAY BE ABLE TO TAKE ADVANTAGE OF AN INCREASED AXIS
OF DCAPE EXPECTED TO MOVE THROUGH THE CWA JUST AFTER 00Z FRIDAY.
THEREFORE IF WE DO ENCOUNTER SEVERE WEATHER TOMORROW...IT WILL MOST
LIKELY BE DAMAGING WINDS AND NOT HAIL. FOR NOW SPC HAS KEPT THE
RALEIGH AREA OUT OF THE SLIGHT RISK AREA FOR TOMORROW. PRECIPITABLE
WATERS WILL BE SIMILAR TO TODAY NEAR 1.5 INCHES BUT QPF WITH FRONTAL
PASSAGE IS ONLY EXPECTED TO BE BETWEEN A QUARTER AND A HALF OF AN
INCH WITH LOCALLY HEAVIER AMOUNTS POSSIBLE IN THUNDERSTORMS.
LOCALIZED FLOODING COULD BE AN ISSUE...ESPECIALLY IN URBAN AREAS
UNDER SLOW MOVING OR TRAINING THUNDERSTORMS. CLOUD COVER SHOULD
OVERSPREAD THE AREA FAIRLY EARLY TOMORROW AND THUS WILL TREND
TOWARDS THE COOLER MET GUIDANCE WITH HIGH TEMPERATURES. UPPER 70S IN
THE NORTHWEST TO LOW 80S SOUTHEAST. AS THE LOWER ATMOSPHERE BEGINS
TO DRY OUT LOW TEMPERATURES IN THE TRIAD SHOULD DIP INTO THE UPPER
50S IN THE NORTHWEST FOR THE FIRST TIME IN SEVERAL DAYS BUT FURTHER
TO THE SOUTHEAST LOWS WILL REMAIN IN THE MIDDLE 60S AS THE FRONT IS
EXPECTED TO FULLY MOVE THROUGH THE EAST UNTIL CLOSER TO 6Z ON FRIDAY.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
AS OF 310 PM WEDNESDAY...
FRIDAY THROUGH SATURDAY NIGHT...
A DEEP UPPER LEVEL TROUGH WILL SWING ACROSS CENTRAL NC FRIDAY AND
EXIT THE REGION FRIDAY NIGHT. MAY SEE A FEW INSTABILITY SHOWERS
WITH THE PASSAGE OF THIS SYSTEM HOWEVER MODEL RH CROSS SECTIONS
DEPICT THE AIR MASS DRYING OUT APPRECIABLY ABOVE 5000-8000FT BY
EARLY AFTERNOON. FOR NOW WILL LIMIT POPS TO SLIGHT CHANCE. OTHERWISE
BRISK NW FLOW WILL ADVECT COOLER MORE STABLE AIR INTO THE REGION.
SUSTAINED NW WINDS 10-15 MPH WITH GUSTS AROUND 25 MPH PROBABLE. THE
ARRIVAL OF THIS AIR MASS WILL RESULT IN COOLER CONDITIONS WITH
AFTERNOON MAX TEMPS IN THE LOWER 70S NORTH TO UPPER 70S FAR SE.
FRIDAY NIGHT...SKIES WILL CLEAR EARLY THOUGH A STEADY NW SFC WIND
WILL BE SLOW TO SUBSIDE. LOW LEVEL THICKNESSES CLUSTERING AROUND
1340M. HISTORICALLY...THIS SUGGEST MIN TEMPS NEAR 40-LOWER 40S.
FAVOR THE HIGH END OF THIS REGION DUE TO EXPECTED MIXING WELL INTO
THE NIGHT. MIN TEMPS 45-50.
SATURDAY INTO SATURDAY NIGHT...CANADIAN HIGH PRESSURE OVER THE LOWER
GREAT LAKES WILL BUILD/EXTEND INTO OUR REGION SATURDAY INTO SATURDAY
NIGHT. THIS WEATHER SYSTEM WILL RESULT IN A DRY WEATHER PATTERN WITH
BELOW NORMAL TEMPS. AFTERNOON THICKNESSES PROJECTED TO BE ABOUT 35M
BELOW NORMAL...SUPPORTIVE OF TEMPS CLOSE TO 10 DEGREES BELOW NORMAL.
ALLOWING FOR WARMTH FROM LATE MAY SUN...EXPECT AFTERNOON HIGH TEMPS
IN THE MID-UPPER 70S. MOS GUIDANCE LIKELY TRENDING TOWARD
CLIMATOLOGY BY SATURDAY NIGHT. WITH SFC RIDGE OVERHEAD AND CORE OF
LOW LEVEL DRY ACROSS THE REGION...TEMPS SHOULD COOL QUICKLY INT EH
EVENING THEN STABILIZE. MODEL RH CROSS SECTIONS HINT AT INCREASING
MID-HIGH LEVEL CLOUDS OVERNIGHT INTO EARLY SUNDAY. FIRST GLANCE
SUGGEST THAT CLOUD COVERAGE MAY INITIALLY BE THIN AND SPOTTY SO
COULD SEE DECENT NOCTURNAL COOLING. FAVOR MIN TEMPS A FEW DEGREES
COOLER THAN PREVIOUS FORECAST WITH MIN TEMPS IN THE MID-UPPER 40S.
SUNDAY INTO MONDAY...DEEP UPPER LEVEL LOW OVER NORTHERN NEW
ENGLAND-CANADIAN MARITIME PROVINCES WILL MAINTAIN A NW FLOW OVER THE
FORECAST AREA SUNDAY. WEAK PERTURBATIONS IN THIS FLOW ALOFT WORKING
WITH AVAILABLE MOISTURE WILL LIKELY CAUSE AN INCREASE IN MID-HIGH
LEVEL CLOUDINESS SUNDAY INTO SUNDAY NIGHT...MORE SO ACROSS OUR WEST
AND SOUTH SECTIONS AND LEAST IN THE NE. A MODIFYING AIR MASS WILL
LEAD TO SLIGHTLY WARMER CONDITIONS WITH AFTERNOON TEMPS IN THE
MID-UPPER 70S...AND AND MIN TEMPS IN THE MID 50S. 00Z ECMWF SUGGEST
THAT THERE MAY BE ENOUGH AMPLITUDE TO AN APPROACHING MID LEVEL
TROUGH TO WARRANT A SLIGHT-SMALL CHANCE POP ACROSS CENTRAL NC MONDAY
AFTERNOON-MONDAY EVENING.
TUESDAY INTO WEDNESDAY...AN AMPLIFYING MID-UPPER LEVEL RIDGE OVER
THE EASTERN HALF OF THE U.S. WILL PLACE CENTRAL NC BACK INTO A
SUMMER-LIKE PATTERN WITH A SFC HIGH ANCHORED OFFSHORE BUT EXTENDING
WESTWARD INTO THE SE U.S. THIS SUGGEST A RETURN TO WARM AND SLIGHTLY
HUMID CONDITIONS WITH AFTERNOON TEMPS IN THE LOW-MID 80S AND MIN
TEMPS 60-65. CONVECTION APPEARS TO BE DIURNALLY DRIVEN...ADDED BY A
SEABREEZE TO SE AND NW FLOW ALOFT SENDING CONVECTION OFF THE HIGHER
TERRAIN INTO THE WESTERN PIEDMONT. POPS NO HIGHER THAN SLIGHT
CHANCE-SMALL CHANCE AT THIS TIME...CONFINED TO THE AFTERNOON-EVENING
HOURS.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 205 AM THURSDAY...
A LINE OF SHOWERS AND ISOLATED STORMS THAT EARLIER AFFECTED THE
TRIAD TERMINALS WILL CONTINUE TO MOVE SLOWLY EASTWARD AT AROUND 10
MPH...AFFECTING THE KRDU AREA BETWEEN 8-10Z. A GRADUAL
WEAKENING/DISSIPATING TREND SHOULD OCCUR AS THE AIR MASS CONTINUES
TO STABILIZE WITH NOCTURNAL COOLING...HOWEVER...SO CONFIDENCE OF THE
CONVECTION REACHING THE KFAY AND KRWI AREAS IS LOW. OTHERWISE...A
CONTINUED MOIST AIR MASS WILL PROMOTE A HIGH CHANCE OF LIFR-IFR
CEILINGS THIS MORNING...THOUGH WITH RELATIVE LOWEST CHANCES - AROUND
60 PERCENT - AT TRIAD TERMINALS. THESE CEILINGS WILL LIFT AND
SCATTER TO VFR WITH HEATING THROUGH MIDDAY. HEATING OF THE MOIST AIR
MASS WILL ALSO CAUSE SCATTERED TO NUMEROUS SHOWERS AND STORMS TO
DEVELOP THIS AFTERNOON...AND THESE WILL LIKELY CONTINUE UNTIL A COLD
FRONT SWEEPS ACROSS CENTRAL NC FROM WEST TO EAST BETWEEN 04-06Z AT
TRIAD TERMINALS...TO 09-12Z AT EASTERN ONES. AREAS O FOG OR LOW
STRATUS WILL ALSO BE POSSIBLE AHEAD OF THE COLD FRONT...MOST LIKELY
AT KFAY AND KRWI BETWEEN 06-12Z.
VFR CONDITIONS WILL OTHERWISE PREVAIL IN CANADIAN HIGH PRESSURE
THROUGH THE HOLIDAY WEEKEND.
&&
.CLIMATE...
MORNING LOW TEMPERATURES ON THE 25TH AND 26TH ARE EXPECTED TO BE A
FEW DEGREES SHY OF RECORD MIN TEMPS FOR THE DATE.
RECORD MIN TEMP/YEAR SET MAY 25TH MAY 26TH
RDU 43 / 1967 43 / 1979
GSO 43 / 1956 42 / 1930
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...MWS
NEAR TERM...BSD
SHORT TERM...ELLIS
LONG TERM...WSS
AVIATION...MWS
CLIMATE...RAH
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
121 AM EDT THU MAY 23 2013
.SYNOPSIS...
AN APPROACHING UPPER LEVEL TROUGH WILL CONTINUE TO INFLUENCE THE
REGION THROUGH THURSDAY. A COLD FRONT MOVES THROUGH THE AREA
THURSDAY NIGHT...BEFORE A COOLER AND DRIER AIRMASS SETTLES IN FOR
THE WEEKEND AND MODIFIES THROUGH THE EARLY PART OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
0500 UTC UPDATE...POPS WERE REALIGNED TO CONCUR WITH RADAR
TRENDS...MOVING A LINE OF CONVECTION ACROSS INTERSTATE 77 OVER THE
NET FEW HOURS...ANOTHER CLUSTER OF STORMS ACROSS THE UPPER SAVANNAH
RIVER VALLEY...AND A THIRD GROUP OF STORMS FROM THE GA MOUNTAINS
INTO SC. WINDS WERE UPDATED WITH A BLEND OF THE LATEST ADJMAV AND
NAM...FAVORING THE LATER FOR HIGHER WINDS IN THE MOUNTAINS.
VISIBILITY WAS UPDATED FORM OBSERVATIONS AND A BLEND OF THE ADJMAV
AND ADJMET...LOWERED SLIGHTLY TOWARD THE LAMP GUIDANCE.
AS OF 1045 PM...BROKEN MULTICELL LINE OF THUNDERSTORMS CONTINUES TO
MOVE TO THE EAST NORTHEAST ACROSS THE UPSTATE IN ASSOCIATION WITH
CONVERGENCE NEAR FRONTAL BOUNDARY. ELSEWHERE...DISCRETE PULSE
SHOWERS AND THUNDERSTORMS WERE PRESENT ACROSS PORTIONS OF THE NORTH
CAROLINA FOOTHILLS/PIEDMONT. THE MAIN THREATS WITH ANY OF THESE
THUNDERSTORMS ARE BRIEF HEAVY RAINFALL...LARGE HAIL...DAMAGING
WINDS...AND FREQUENT CLOUD TO GROUND LIGHTNING. AS FOR THE
FCST...THE ACTIVITY CURRENTLY EXTENDING ACROSS THE WESTERN CWFA
SHOULD MOVE EASTWARD ACROSS THE CWFA GRADUALLY DIMINISHING IN
INTENSITY AS INSTABILITY WANES. GENERALLY CHANGED POPS TO REFLECT
THIS WAVE OF ACTIVITY BEING FOLLOWED BY MUCH LOWER POPS IN SCHC TO
LOW CHC RANGE DUE TO CONTINUED PRESENCE OF UPSTREAM ACTIVITY.
ADJUSTED TEMPERATURE TRENDS FURTHER BY LOWERING TEMPS ACROSS THE
NORTH CAROLINA PIEDMONT DUE TO OUTFLOW BOUNDARIES FROM EARLIER
CONVECTION SPREADING ACROSS THIS REGION.
REMAINDER OF PREVIOUS DISCUSSION...
AS OF 800 PM...TOUCHED UP EVENING TEMP TRENDS...WHICH HAVE BEEN
IMPACTED GREATLY BY THUNDERSTORMS AND THEIR COOL OUTFLOW. RADAR
INDICATES SEVERAL BOUNDARIES SPREADING ACROSS THE PIEDMONT...WHERE
TEMPS REMAIN IN THE MID TO UPPER 70S. THINK THESE WILL BE IMPACTED
BY BOTH DIURNAL COOLING AS WELL AS THE OUTFLOW. LAMP TEMPS SEEM TO
REFLECT THE CURRENT SITUATION FAIRLY WELL AND THESE ARE IN DECENT
AGREEMENT WITH LATE EVENING TEMPS...SO NO CHANGES MADE OTHER THAN TO
UPDATE FIRST FEW HRS.
AS OF MID AFTERNOON...A BROKEN BAND OF SHOWERS AND THUNDERSTORMS WAS
LOCATED JUST EAST OF THE BLUE RIDGE IN NC FROM I-40 NEWD...WITH
OTHER STORMS POPPING UP ACROSS THE HIGHER TERRAIN AIDED BY
DIFFERENTIAL HEATING. EXPECT THE STORMS TO BECOME MORE NUMEROUS
ACROSS THE MTNS THROUGH LATE AFTERNOON...WITH THAT CONVECTION MOVING
EAST OVER THE FOOTHILLS AND PIEDMONT INTO THE EVENING. POP HAS BEEN
ADJUSTED ACCORDINGLY. SOME OF THESE STORMS WILL PRODUCE LARGE HAIL
AND DAMAGING WIND GUSTS. HIGH TEMPS STILL LOOK OKAY.
FOR TONIGHT...THE CONVECTION ALLOWING MODELS SUGGEST THAT ANOTHER
ROUND OF STORMS WILL FIRE TO THE WEST AND THEN MOVE EAST INTO THE
FCST AREA IN THE EARLY EVENING. THE HRRR AND 4KM WRF PAINT A SIMILAR
PICTURE WITH NUMEROUS STORMS OVER THE WESTERN HALF OF THE FCST AREA
THROUGH MID TO LATE EVENING. A SHORT WAVE MOVING AROUND THE UPPER
TROF...COMBINED WITH SOME UPPER DIVERGENCE...SHOULD PROVIDE THE
NECESSARY SUPPORT FOR THIS CONVECTION TO THRIVE. WITH THAT IN
MIND...THE POP WAS RAISED TO LIKELY OVER THE WESTERN HALF. AFTER
SOME LOSS OF HEATING...THE STORMS SHOULD BECOME A BIT LESS NUMEROUS
OVER THE NC PIEDMONT. AT THAT POINT...THE POP WAS KEPT BELOW 50 PCT
ONLY BECAUSE OF SOME UNCERTAINTY GIVEN BY THE CONVECTION HAVING NOT
YET DEVELOPED AS OF 18Z. MIN TEMPS SHOULD REMAIN MILD.
THE COLD FRONT WILL MOVE IN FROM THE WEST ON THURSDAY...MOST LIKELY
OVER THE MTNS IN THE MORNING AND THEN MOVING OUT OVER THE FOOTHILLS
IN THE AFTERNOON. NEW CONVECTION SHOULD DEVELOP ALONG THE FRONT
MAINLY OVER THE PIEDMONT IN THE AFTERNOON. THIS IS TRICKY BECAUSE OF
THE LIKELIHOOD OF WIDESPREAD DEBRIS CLOUDINESS INTO THE EARLY
AFTERNOON THAT WOULD LIMIT CONVECTION. THINK THE MTNS STAND A CHANCE
BECAUSE OF THE FRONT EARLY IN THE DAY. THE UPSTATE AND NE GEORGIA
HAS THE LEAST FAVORABLE ENVIRONMENT...SO A 20 PCT POP WAS KEPT. THE
PIEDMONT HAS A BETTER CHANCE AHEAD OF THE FRONT SO A LIKELY POP WAS
CARRIED OVER THE EASTERN ZONES FOR A TIME. SEVERE STORMS ARE
POSSIBLE...BUT MORE LIKELY TO THE EAST OF I-77. HIGH TEMPS WILL BE
A FEW DEGREES COOLER.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY/...
AS OF 230 PM WEDNESDAY...A SURFACE COLD FRONT SHOULD BE LOCATED NEAR
THE EDGE OF OUR WESTERN NORTH CAROLINA PIEDMONT EARLY THURSDAY
EVENING. THIS LINES UP WELL WITH THE SHORT TERM SUITE OF MODELS...
AND LINES UP WITH WITH AN AXIS OF DPVA WHICH SHOULD BE CROSSING THAT
REGION LATE IN THE DAY/EARLY EVENING. CONVECTIVE ALLOWING MODELS
ALSO DEPICT THIS TREND AND IS SUPPORTED BY INSTABILITY LINGERING
ACROSS THAT AREA. AS A RESULT WE WILL HAVE A CORRIDOR OF LOWER
CHANCE POPS IN OUR EASTERN FORECAST AREA (FA) UNTIL AROUND DARK OR
SO.
A SECOND AREA OF PRECIPITATION FOR THURSDAY NIGHT WILL BE IN THE NC
MOUNTAINS WHERE ANOTHER LOBE OF ENERGY...EMBEDDED IN A SHARPENING H5
TROF...CROSSES THE AREA. WE WILL CARRY CHANCE POPS IN THE NC
MOUNTAINS THURSDAY NIGHT AND FRIDAY MORNING...IN A CONTINUALLY
DEEPENING FORCED UPPER AIR PATTERN. ALTHOUGH THE SHARPENING TROF
CROSSES ALL OF OUR REGION FRIDAY...THE ATMOSPHERE LOOKS TO DRY FOR
ANY PRECIPITATION.
MEANWHILE THE H85 ISALLOBARIC PATTERN WAS INDICATING SIGNIFICANT
CROSS CONTOURS OF THERMAL STRUCTURE AND HEIGHTS FRIDAY. THIS
SUGGESTS AT LEAST SIGNIFICANT COLD AIR ADVECTION (ESPECIALLY JUST
ABOVE THE SURFACE) AND MIXING DOWN. WE HAVE FOLLOWED BUFKIT
INFORMATION FOR WIND GUSTS FRIDAY...AND IN ALL LIKELIHOOD WE WILL
NEED SOME TYPE OF WIND HEADLINE FRIDAY FOR PART OF OUR FAA...
PARTICULARLY IN THE AFTERNOON.
HIGH PRESSURE WILL EDGE TOWARD THE REGION FRIDAY NIGHT...WHICH WILL
BRING A COOL/COLD NIGHT AROUND THE AREA. SOME MOUNTAIN LOCATIONS TO
DIP INTO THE 30S...BUT BELIEVE ENOUGH MIXING SHOULD PREVENT FROST
DUE TO THE LINGERING GRADIENT OF HIGH PRESSURE OFF TO THE NORTHWEST
AND LOW PRESSURE MOVING UP THE EASTERN SEABOARD. HOWEVER WE WILL
HAVE TO MONITOR TRENDS.
HIGH PRESSURE TO HOLD SWAY SATURDAY WITH A PLEASANT DAY ON
TAP.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 225 PM WEDNESDAY...RATHER GOOD AGREEMENT IS HAD IN THE UPPER
LEVEL OMEGA PATTERN OVER THE EXT RANGE. THE 12Z GFS IS A BIT OF AN
OUTLIER AND SHARPENS THE EAST COAST TROF AND SUBSEQUENT DEEP NW/LY
FLOW GRADIENT MORESO THAN THE OTHER OP MODELS...BUT NOT ENOUGH FOR A
SIGFNT LLVL RESPONSE. AT THE SFC...THERE ARE MAJOR DIFFERENCES
EVOLVING WITH THE SYNOPTIC PATTERN...THUS A LESS THAN AVG
CONFIDENCE IS HAD AS THE EXT RANGE PROGRESSES.
HIGH PRESSURE CONTINUES TO BUILD IN FROM THE NORTH SUN AND KEEPS
THINGS DRY. HIGH TEMPS WILL BE A LITTLE BELOW NORMAL WITH A
REINFORCING CP AIRMASS MIXING IN. THE LLVL FLOW BECOMES DEFINED
SW/LY MON AS THE ATL HIGH NUDGES IN. THIS WILL ALSO ENABLE A WARM
FRONT OR STATIONARY TO PERHAPS IMPINGE UPON THE REGION MON NIGHT
INTO TUE. THERE IS LOW CONFIDENCE IN THIS FEATURE...HOWEVER...AS THE
GFS KEEPS ANY FRONTOGENESIS WELL TO THE NORTH OF THE REGION WITH A
WEAK TROF BUILDING INTO THE SFC SE RIDGE...WHILE THE ECMWF HAS THE
WARM FRONT STALLING OUT ACROSS THE CWFA DURING THE DAY TUE INTO WED.
RIGHT NOW...POPS HAVE BEEN CONTINUED IN THE LOW END CHANCE RANGE MON
THROUGH TUE...AND A DRIER HPC BLEND WAS MAINTAINED FOR WED.
SOUNDINGS SHOW VERY LITTLE SBCAPE DEVELOPING MON AS THE UPPER FLOW
KEEPS A SUBSIDENCE INVERSION IN PLACE...HOWEVER A RELATIVE WEAKENING
ALOFT TUE SHOULD ENABLE THE DEVELOPMENT OF SOME ENHANCE CONVECTION
AND TSTMS. MAX TEMPS WILL WARM EACH DAY MON THROUGH THE PERIOD TO A
LITTLE ABOVE NORMAL IN GOOD SW/LY FLOW AND INSOLATION.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AT KCLT...ANOTHER LINE OF THUNDERSTORMS WILL CROSS THE FIELD
SHORTLY...THEN ACTIVITY WILL DIMINISH. A DAMP AIR MASS AND PRIOR
RAINFALL AMOUNTS SUPPORT VSBY AND CIG RESTRICTIONS TOWARD DAWN...AND
MVFR WILL BE CARRIED. SW WINDS WILL MIX OUT RESTRICTIONS AFTER IN
THE MORNING. ANOTHER ROUND OF CONVECTION WITH POSSIBLE RESTRICTIONS
IS EXPECTED ON THURSDAY AS A COLD FRONT MOVES THROUGH FROM THE
W...AND ANOTHER APPROACHES FROM THE NW. CONVECTION WILL MOVE OFF TO
THE EAST BY THURSDAY EVENING....WHILE SW WINDS VEER TO NW AND BECOME
GUSTY.
ELSEWHERE...CONVECTION WILL MOVE EAST OUR OF THE FOOTHILLS SHORTLY.
EARLIER RAINFALL HAS MOISTENED THE ATMOSPHERE AND GROUND TO THE
POINT THAT AT LEAST MVFR RESTRICTIONS ARE EXPECTED BY DAYBREAK...AND
TEMPORARY IFR AT KAVL. BY MID MORNING RESTRICTIONS WILL END AS THE
WINDS COMES UP FROM THE SW IN THE FOOTHILLS ND NW IN THE MOUNTAINS.
ADDITIONAL CONVECTION AND RESTRICTIONS ARE EXPECTED BY MIDDAY
BETWEEN A DEPARTING COLD FRONT...AND ANOTHER STRONGER FRONT ARRIVING
FROM THE NW. WINDS WILL VEER TO THE WEST DURING THE DAY IN THE
FOOTHILLS AND BECOME GUSTY...VEERING FURTHER TO BECOME NW IN THE
EVENING. PRECIPITATION WILL BE MAINLY CONFINED TO THE MOUNTAINS
THURSDAY EVENING IN NW UPSLOPE FLOW.
OUTLOOK...RESTRICTIONS POSSIBLE WITH LINGERING MOISTURE OVERNIGHT
THU NIGHT AND FRI MORNING. GENERALLY VFR WEATHER FRIDAY AND SATURDAY.
CONFIDENCE TABLE...
05-11Z 11-17Z 17-23Z 23-05Z
KCLT HIGH 84% HIGH 90% HIGH 100% HIGH 100%
KGSP MED 79% HIGH 88% HIGH 100% HIGH 100%
KAVL MED 70% HIGH 88% HIGH 100% HIGH 97%
KHKY LOW 56% HIGH 83% HIGH 100% HIGH 100%
KGMU MED 73% HIGH 83% HIGH 100% HIGH 100%
KAND MED 69% HIGH 94% HIGH 100% 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...SBK
NEAR TERM...CDG/JAT/PM/WIMBERLEY
SHORT TERM...TS
LONG TERM...SBK
AVIATION...JAT
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1133 PM CDT WED MAY 22 2013
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.UPDATE...
ISSUED AT 902 PM CDT WED MAY 22 2013
SLOW MOVING AREA OF LIGHT RAIN ASSOCIATED WITH PESKY
MID-LEVEL CIRCULATION AND ASSOCIATED DEFORMATION SLOWLY WANING
AND BECOMING INCREASINGLY DISORGANIZED AS NORTHERLY FLOW AND
SUBSIDENCE INCREASES UPSTREAM. GOING SHORT-TERM FORECAST STILL
LOOKING ON TRACK. LAST FEW RUNS OF THE HRRR SEEM TO HAVE A DECENT
HANDLE ON THE DEMISE OF THIS SYSTEM WITH PRECIPITATION ENDING FROM
NORTHWEST TO SOUTHEAST OVERNIGHT. EXPECT BACK EDGE OF WEAKENING
PRECIPITATION SHIELD TO MOVE SOUTHEAST OF THE FORECAST AREA BY
AROUND 10Z OR 11Z FOLLOWED BY CLEARING SKIES AFTER 15Z THURSDAY.
EXPECT NORTHEAST WINDS TO INCREASE OVERNIGHT WITH A FEW GUSTS OF
25 TO 30 MPH MAINLY OVER THE FOX VALLEY FROM GREEN BAY SOUTH TO
OSHKOSH.
&&
.SYNOPSIS...
ISSUED AT 233 PM CDT WED MAY 22 2013
UPPER LEVEL SYSTEM THAT HAS BEEN SITTING OVER THE NORTHERN PLAINS
THE PAST FEW DAYS WAS FINALLY MOVING EAST...WITH THE SFC LOW
PRESSURE SLIDING THROUGH SOUTHERN WISCONSIN THIS AFTERNOON PER
MSAS ANALYSIS. THIS SFC LOW...COMBINED WITH ENERGY FROM A POTENT
SHORTWAVE THAT WAS SWINGING AROUND THE SOUTHEAST SIDE OF THE
UPPER LEVEL TROUGH INTO THE GREAT LAKES AREA...RESULTED IN
WIDESPREAD SHOWERS THIS AFTERNOON. SOME LIGHTNING WAS ALSO
DETECTED IN THIS AREA OF PRECIP...MAINLY IN THE VICINITY OF A NOSE
OF MINOR MU-CAPES AND THE BEST FORCING. SHOWERS HAVE BECOME MORE
NUMEROUS THROUGH THE MORNING AND AFTERNOON AS A DECENT 300MB JET
STREAK MOVED OVER THE STATE...WITH NORTHEAST WISCONSIN SITTING IN
THE RIGHT REAR QUAD. EVEN THOUGH SFC WINDS WERE OUT OF THE EAST TO
NORTHEAST...THIS MORNINGS 12Z SOUNDING OUT OF GRB AND DVN SHOWED
SOUTHWEST FLOW ALOFT...WHICH HELPED CONTINUE TO PUMP MOISTURE
INTO SOUTHERN PORTIONS OF THE CWA. PRECIPITABLE WATER VALUES IN
THIS AREA INCREASED THROUGH THE MORNING AND OCCASIONAL MODERATE TO
HEAVY RAIN WAS REPORTED IN SOME LOCATIONS JUST SOUTH OF OSHKOSH
AND FDL. FURTHER NORTH...SKIES REMAINED CLOUDY BUT NO PRECIP WAS
REPORTED. EXPECT SHOWERS AND ISOLATED THUNDERSTORMS TO CONTINUE TO
PUSH NORTH AND OVERSPREAD THE AREA THROUGH THE REST OF THE
AFTERNOON...WITH PORTIONS OF EASTERN AND CENTRAL WISCONSIN SEEING
OCCASIONAL MODERATE TO HEAVY RAINFALL AS THE BEST FORCING MOVES
THROUGH THE STATE WITH THE MAIN UPPER LEVEL TROUGH.
&&
.SHORT TERM...TONIGHT AND THURSDAY
ISSUED AT 233 PM CDT WED MAY 22 2013
MAIN FORECAST CONCERN WILL BE PRECIPITATION TRENDS TONIGHT AND
EARLY THURSDAY MORNING. OTHERWISE...SKIES WILL CLEAR FROM
NORTHWEST TO SOUTHEAST AS HIGH PRESSURE MOVES IN FROM CANADA ON
THURSDAY.
PRECIPITATION SHOULD OVERSPREAD THE ENTIRE AREA LATE THIS
AFTERNOON...REACHING THE UPPER PENINSULA BORDER BY 21Z-00Z.
GENERALLY SHOWERY CONDITIONS WILL PERSIST THROUGH THE EARLY
OVERNIGHT HOURS FOR THE CWA...WITH SOME MODERATE RAIN POSSIBLE IN
EASTERN WISCONSIN. THERE HAS BEEN A CONSISTENT SIGNAL FROM THE
MODELS FOR STRONG FORCING 21Z TODAY THROUGH 03Z TONIGHT IN CENTRAL
AND EAST CENTRAL WISCONSIN...AND EXPECT THIS TIME FRAME TO BE WHEN
WE WILL SEE THE HEAVIEST AND MOST WIDESPREAD RAINFALL. BUMPED UP
QPF A LITTLE IN EASTERN WISCONSIN FROM 00Z TO 06Z THURSDAY TO
ACCOUNT FOR POSSIBLE HEAVIER SHOWERS WITH THIS FORCING. CONTINUED
TO KEEP ISOLATED THUNDER IN THE FCST UNTIL 03Z THURSDAY AS
WELL...AT WHICH POINT ANY LINGERING MU-CAPE OVER 500 J/KG WILL
DISSIPATE AND THE BEST FORCING WILL MOVE AWAY FROM WISCONSIN...SO
PRECIPITATION WILL BE MAINLY SHOWERS.
DRY AIR WILL RUSH IN BEHIND THE UPPER LEVEL SYSTEM LATE TONIGHT
AND SHOULD QUICKLY USHER OUT PRECIPITATION. THIS COMBINED WITH
STRONG SUBSIDENCE WILL RESULT IN SHOWERS ENDING IN FAR NW PORTIONS
OF THE CWA AROUND MIDNIGHT. THIS TREND WILL CONTINUE FROM
NORTHWEST TO SOUTHEAST THROUGH THE EARLY MORNING HOURS BEFORE THE
LAST OF THE PRECIP EXITS THE LAKESHORE AROUND 15Z THURSDAY. SPED
UP THE EXIT OF PRECIP/CLOUDS A BIT FROM THE PREVIOUS FORECAST DUE
TO MODEL TRENDS...OTHERWISE MADE FEW CHANGES TO WHAT WE HAD GOING
BEFORE. TEMPERATURES WILL BE CHILLY ON THURSDAY AS STRONG COLD AIR
ADVECTION ALOFT SETS UP AND GUSTY NORTH WINDS DEVELOP.
.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 233 PM CDT WED MAY 22 2013
MAIN FCST CONCERNS INCLUDE FROST/FREEZE POTENTIAL ON THURSDAY NIGHT...
WHETHER OR NOT TO INCLUDE PCPN CHANCES FOR THE HOLIDAY WEEKEND...AND
TEMPERATURES THROUGHOUT THE PERIOD.
HUDSON BAY HIGH PRESSURE WILL RESIDE OVER THE REGION FOR THE END
OF THE WORK WEEK...AND THROUGH THE HOLIDAY WEEKEND. A VERY DRY AIR MASS
WILL BE IN PLACE THURSDAY NIGHT...WITH PRECIPITABLE WATER VALUES
DROPPING TO 0.25 TO 0.33 INCH. CLEAR SKIES AND LIGHT WINDS WILL ALLOW
TEMPERATURES TO PLUMMET TO BLO FREEZING ACROSS MOST OF NC/FAR NE WI...
WITH READINGS POSSIBLY APPROACHING 20 DEGREES IN THE TYPICAL COLD SPOTS.
WILL ISSUE A FREEZE WATCH FOR NC/FAR NE WI...WHERE FREEZING TEMPS ARE
LIKELY. AN SPS WILL BE ISSUED FOR THE REST OF THE CWA...WHERE PATCHY/
AREAS OF FROST ARE A GOOD BET. WILL NEED TO WATCH CENTRAL WI
CLOSELY...AS FCST MIN TEMPS ARE CLOSE TO FREEZING.
THE LARGE HIGH PRESSURE WILL ONLY DRIFT SLIGHTLY TO THE EAST OVER THE
HOLIDAY WEEKEND...WITH THE RIDGE AXIS SETTING UP JUST TO OUR EAST.
THE ECMWF HAS BEEN CONSISTENT IN KEEPING ANY PCPN TO OUR WEST AND SOUTH
THROUGH THE WEEKEND...WHILE THE GFS/GEFS ATTEMPT TO BRING SOME LGT
QPF INTO OUR SW COUNTIES BY ABOUT SUNDAY. HAVE KEPT THE FCST DRY
THROUGH SUNDAY...AND ONLY MENTIONED A SLIGHT CHANCE OF SHOWERS FROM
SUNDAY NIGHT INTO TUESDAY. TEMPERATURES WILL REMAIN A LITTLE BLO
NORMAL THROUGH THE WEEKEND...WITH HIGHS IN THE 60S.
A WARM FRONT IS EXPECTED TO LIFT NORTH INTO THE REGION TUESDAY NIGHT
AND WEDNESDAY...AND MAY BRING A CHANCE OF THUNDERSTORMS AND MILDER
TEMPS TO THE FORECAST AREA.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1130 PM CDT WED MAY 22 2013
A RAPIDLY IMPROVEMENT IN FLIGHT CONDITIONS WILL SWEEP NW-SE ACRS
THE AREA LATE TNGT AND THU MORNING AS THE RAIN-PRODUCING CYCLONE
DEPARTS THE AREA TO THE E AND IS REPLACED BY CANADIAN HIGH
PRESSURE.
.MARINE...
ISSUED AT 233 PM CDT WED MAY 22 2013
HIGH-END SMALL CRAFT ADVISORY ISSUED FOR THIS AFTERNOON THROUGH AT
LEAST FRIDAY FOR GUSTY NORTH TO NORTHEAST WINDS. GUSTS WILL GET
CLOSE TO GALE FORCE TOMORROW LATE MORNING AND EARLY AFTERNOON...
HOWEVER THE BEST MIXING WILL OCCUR AFTER THE STRONGER WINDS OFF
THE SFC BEGIN TO DISSIPATE. SO WILL KEEP THE STRONG WORDED SMALL
CRAFT ADVISORY WITH JUST A MENTION OF A FEW GALE FORCE GUSTS
POSSIBLE. PERSISTENT MARINE FOG HAS BEGUN TO LIFT AND VISIBILITIES
ARE COMING UP THIS AFTERNOON AS WINDS INCREASE. KEPT PATCHY FOG IN
THE FORECAST UNTIL 03Z THURSDAY...BUT AT THIS POINT DEW POINT
DEPRESSIONS AND WINDS INCREASE AND FOG SHOULD NO LONGER BE AN
ISSUE. WILL REMOVE FOG MENTION FROM THE MWW.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
FREEZE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY MORNING FOR
WIZ005-010>013-018-019-021.
&&
$$
UPDATE.........ESB
SYNOPSIS.......WOLF
SHORT TERM.....WOLF
LONG TERM......KIECKBUSCH
AVIATION.......JS
MARINE.........WOLF
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
1043 AM EDT THU MAY 23 2013
.SYNOPSIS...
A BERMUDA HIGH PRESSURE SYSTEM WELL OFF THE EAST COAST WILL SLOWLY
RECEDE TODAY AND TONIGHT. A LOW PRESSURE SYSTEM MOVING THROUGH THE
SAINT LAWRENCE VALLEY WILL SLOWLY DRAG A COLD FRONT INTO AND THROUGH
THE REGION LATE TONIGHT INTO FRIDAY. A SECOND LOW PRESSURE SYSTEM
WILL DEVELOP ON THE FRONT OFF THE NEW JERSEY COAST FRIDAY AND
SLOWLY TRUNDLE NORTHEAST REACHING THE CANADIAN MARITIMES ON
MONDAY. A HIGH PRESSURE SYSTEM WILL BUILD EAST IN ITS WAKE EARLY
NEXT WEEK. A WARM FRONT IS FORECAST TO APPROACH AND MOVE THROUGH
THE FORECAST AREA ON TUESDAY INTO WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WITH THE MID-MORNING UPDATE, WE DECREASED POPS SOME FOR THE NEXT
FEW HOURS ACROSS EASTERN AND SOUTHERN SECTIONS OF THE FORECAST
AREA, BASED ON CURRENT RADAR IMAGERY AND THE LATEST HRRR GUIDANCE
WHICH LOOKS TO BE CAPTURING TRENDS TODAY FAIRLY WELL. WE ALSO
DECREASED T-STORM COVERAGE FROM SCATTERED TO ISOLATED UNTIL THIS
AFTERNOON. HOURLY TEMPERATURES WERE ADJUSTED USING LAV/LAMP
GUIDANCE, AS TEMPS WERE RISING A LITTLE FASTER THAN FORECAST IN SOME
LOCATIONS. MAXIMUM TEMPERATURES LOOK ON TRACK FOR NOW, CONSIDERING
THE CONSIDERABLE CLOUD COVER ACROSS THE REGION. HOWEVER, A FEW
BREAKS ARE DEVELOPING ACROSS OUR DELMARVA REGION, AND THIS MAY
ALLOW TEMPS TO RISE TO AROUND 80 DEGREES IN SOME LOCATIONS. WE
WILL CONTINUE TO MONITOR AND UPDATE MAX TEMPS AS NEEDED.
OTHERWISE, A RAINY PERIOD IS IN STORE TODAY AS SHOWERS AND
SCATTERED THUNDERSTORMS ARE EXPECTED TO INCREASE IN COVERAGE
THROUGH THE DAY. SURFACE LOW PRESSURE WILL MOVE OUT OF THE GREAT
LAKES AND INTO NEW ENGLAND TODAY, WHICH WILL PUSH A COLD FRONT
THROUGH CENTRAL PENNSYLVANIA AND TOWARD OUR AREA LATER TODAY.
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO CONTINUE TO DEVELOP
AHEAD OF THE FRONTAL BOUNDARY. A PRE-FRONTAL, LEE-SIDE TROUGH IS
EXPECTED TO DEVELOP DURING THE DAY WHILE A SHORT WAVE/VORT MAX
MOVES ACROSS THE AREA AS WELL. THIS WILL LIKELY BE THE FOCUS FOR A
LINE OF SHOWERS AND THUNDERSTORMS LATE IN THE DAY. THE SPC HAS
PLACED A PORTION OF THE AREA UNDER A SLIGHT RISK FOR SEVERE
WEATHER THIS AFTERNOON. ONE LIMITING FACTOR WILL BE THE EXPECTED
CLOUD COVER ACROSS THE AREA WHICH MAY LIMIT THE AMOUNT OF
INSTABILITY ACROSS THE AREA. BUT WE COULD STILL HAVE CAPE VALUES
AROUND 500-1000 J/KG, AND WITH SHEAR VALUES AROUND 30-40 KNOTS, WE
COULD HAVE A FEW STORMS BECOME ORGANIZED ENOUGH TO PRODUCE SOME
STRONG WINDS.
ANOTHER CONCERN TODAY WILL BE HEAVY RAINFALL. PW VALUES ARE FORECAST
TO BE AROUND 1.50-1.75 INCHES. THEREFORE, SOME SHOWERS/THUNDERSTORMS
COULD BE RATHER EFFICIENT RAIN PRODUCERS. POOR DRAINAGE AND
URBAN/SMALL STREAM FLOODING IS POSSIBLE THIS AFTERNOON, ESPECIALLY
IF ANY TRAINING OCCURS.
MAV/MET MOS GUIDANCE WERE FAIRLY CLOSE, ALTHOUGH THE MAV WAS
SLIGHTLY HIGHER. WE USED A BLEND, WITH MAJORITY OF THE MAV MOS. THIS
WILL GIVE HIGHS GENERALLY IN THE MID-UPPER 70S, AND IF THE SUN COMES
OUT AT ALL FOR AN EXTENDED PERIOD OF TIME, A FEW AREAS COULD REACH
80 DEGREES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO BE ONGOING ACROSS THE AREA
BY WEDNESDAY EVENING AS THE PRE-FRONTAL TROUGH MAKES ITS WAY ACROSS
OUR AREA AND THE INITIAL SHORT WAVE MOVES ACROSS THE AREA.
INSTABILITY WILL LIKELY DECREASE SOME AFTER SUNSET, BUT WITH MORE
PVA EXPECTED TO TAKE PLACE OVERNIGHT IN THE CYCLONIC FLOW ALOFT,
ALONG WITH THE PASSAGE OF THE FRONTAL BOUNDARY, SHOWERS AND
THUNDERSTORMS COULD CONTINUE TO DEVELOP THROUGH THE NIGHT. THE FRONT
WILL NOT CLEAR THE ENTIRE AREA OVERNIGHT, MAY BE NEAR THE COAST BY
SUNRISE. WITH PW VALUES STILL AROUND 1.50-1.75 INCHES AHEAD OF THE
FRONT, SOME HEAVY RAIN REMAINS POSSIBLE.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
NEITHER THE GFS NOR WRF-NMMB LOOKED STELLAR OFF THEIR
INITIALIZATION. IN FACT A MODEL COMPROMISE SEEMED TO LOOK THE BEST.
OVERALL THOUGH THE DP/DT WITH THE UPCOMING SYSTEM WAS SLOWER AND
THIS FCST PACKAGE DID GO THAT WAY WITH A WETTER START TO THE HOLIDAY
WEEKEND. THIS PACKAGE IS CLOSE TO THE GEFS MEAN WHICH IS SLIGHTLY
MORE PROGRESSIVE THAN THE OP GFS AND CLOSEST TO A MODELING
CONSENSUS. THE MODEL 500MB PATTERN FORECAST IS ANOMALOUS FOR LATE
MAY, SO WE DID EDGE SLIGHTLY MORE PROGRESSIVE THAN THE SLOWER
SOLUTIONS.
THE SLOWING FRONT WILL BE MOVING THROUGH OUR CWA AS WE START THE
LONG TERM. WITH THE TROF SHARPENING, IT BECOMES AN UNDERRUNNER WITH
INSTABILITY STILL PRESENT ALOFT EVEN WITH THE BOUNDARY MOVING
OFFSHORE. WE INCLUDED THE CHANCE OF THUNDER IN THE MORNING, BUT
THEORETICALLY THUNDER COULD LINGER INTO THE AFTERNOON (FRI NIGHT OFF
THE PREVIOUS ECMWF). NOT CONFIDENT ABOUT TEMP FCST AS DAYTIME MAX
TEMP MAY BE DRIVEN BY HOW FAR TEMPS FALL BY 12Z FRIDAY. KIND OF
RARE TO HAVE TEMPS GO NOWHERE ON A MAY DAY (AND ALSO HAVE THE
CALENDAR DAY HIGH POSSIBLY OCCUR AT 101 AM) AND WE SHOWED A SLIGHT
BUMP UP FOR NOW.
AS THE TROF ALOFT CLOSES, MODEL DIAGS ARE SHOWING SOME RATHER ROBUST
MID LEVEL QVEC CONVERGENCE AND FGEN FORCING FORECAST AND A
DEVELOPING MID LEVEL TROWAL OVER OUR CWA WITH THE ENTRANCE REGION
OF THE 250MB JET TO BOOT. ITS NO WONDER THAT QPF HAVE BECOME
WETTER FRIDAY NIGHT AND SATURDAY. IT STILL DEPENDS UPON HOW
QUICKLY AND FAR SOUTH THE 500MB LOW TRACKS. FOR NOW WE REMAIN MOST
CONFIDENT FOR THE NORTHEASTERN PART OF OUR CWA. WHILE POPS WERE
INCREASED FRIDAY NIGHT AND SATURDAY ACROSS THE BOARD, THE HIGHEST
REMAIN IN THE NORTHEASTERN PART OF OUR CWA. WITH ONLY THE ECMWF
SUPPORTING THUNDER FOR FRIDAY NIGHT (NONE OF THE MODELS DO ON
SATURDAY), WE PRECLUDED THEM. CONDITIONS ARE EXPECTED TO IMPROVE
AS SATURDAY MOVES ALONG, BUT WITH OUR CWA REMAINING UNDER THE
CLOSED LOW, ITS GOING TO BE TOUGH TO GET MUCH SUNSHINE BEFORE WE SELF
DESTRUCT. MIN AND MAX TEMPS WERE EDGED LOWER AND CLOSE TO A STAT
GUIDANCE COMPROMISE.
WE KEPT IN PCPN CHANCES FOR SATURDAY NIGHT NORTHEAST AND KEPT SUNDAY
DRY. WE WILL STILL BE IN THE CYCLONIC FLOW OF THE CLOSED LOW, SO
MORE SELF DESTRUCT SUNSHINE IS POSSIBLE, ESPECIALLY FARTHER
NORTHEAST ONE IS WITHIN OUR CWA. WE SHOWED A TEMPERATURE IMPROVEMENT
VS SATURDAY, CONFIDENCE THOUGH IS NOT HIGH UNTIL THE MODEL TREND
SETTLES.
WE DID NOT CHANGE MUCH IN THE REMAINDER OF THE LONG TERM. MONDAY
LOOKS TO BE THE BEST DAY ON THE HOLIDAY WEEKEND WITH TEMPERATURES
RETURNING TO NEAR NORMAL BY TUESDAY AND ABOVE NORMAL ON WEDNESDAY.
WE KEPT LOW CHANCE POPS IN ASSOCIATED WITH THE NEXT APPROACHING
WARM FRONT.
&&
.AVIATION /14Z THURSDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
A CLOUDY, RAINY PERIOD EXPECTED TODAY AS SHOWERS, AND POSSIBLE
THUNDERSTORMS, ARE EXPECTED TO INCREASE THROUGH THE DAY AHEAD OF AN
APPROACHING COLD FRONT. CEILINGS ACROSS MUCH OF THE REGION ARE IN
THE MVFR RANGE, AND WE EXPECT THIS TREND TO HOLD THROUGH MUCH OF
THE DAY. AS MENTIONED, SHOWERS ARE EXPECTED TO INCREASE IN COVERAGE
THROUGH THE DAY AND COULD REDUCE VSBYS IF HEAVY ENOUGH. THERE IS
ALSO THE POTENTIAL FOR THUNDERSTORMS, MAINLY THIS AFTERNOON INTO
THIS EVENING, SO WE WILL KEEP THEM IN THE FORECAST FOR NOW.
THE COLD FRONT IS NOT EXPECTED TO CROSS THE AREA UNTIL OVERNIGHT
THURSDAY INTO FRIDAY MORNING. CONDITIONS COULD LOWER MORE AHEAD OF
THE FRONTAL BOUNDARY THURSDAY NIGHT, AND SHOWERS WILL LIKELY
CONTINUE AT LEAST UNTIL THE FRONT MOVES INTO THE REGION.
OUTLOOK...
FRIDAY THROUGH SATURDAY...MVFR TO POSSIBLY IFR CONDITIONS DUE TO
CLOUDS AND SHOWERS. WORST CONDITIONS EXPECTED AT NORTHEASTERN
TERMINALS AND AIRPORTS. CONDITIONS COULD IMPROVE AS SATURDAY
CONTINUES. NORTH TO NORTHWEST WIND GUSTS COULD EXCEED 20 KTS.
SATURDAY NIGHT THRU MONDAY...MOSTLY VFR. SOME GUSTY NORTHWEST WINDS
POSSIBLE ON SUNDAY.
&&
.MARINE...
SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR TODAY AND TONIGHT AS
WINDS ARE EXPECTED TO CONTINUE TO GUST NEAR 25 KNOTS IN THE
SOUTH-SOUTHWESTERLY FLOW AHEAD OF AN APPROACHING COLD FRONT. SEAS
ARE EXPECTED TO CONTINUE TO INCREASE TO NEAR 5-6 FEET TODAY INTO
TONIGHT AS WELL.
OUTLOOK...
THE SCA FLAG HAS BEEN EXTENDED INTO FRIDAY DAY FOR NOW. WINDS MAY
NOT BE A FACTOR, BUT SWELLS SHOULD REMAIN. THE INCREASING
NORTHWEST FLOW AROUND THE DEVELOPING LOW SHOULD RESULT IN MORE
SMALL CRAFT ADVISORY CONDITIONS ON ALL OUR AREA WATERS LATER
FRIDAY INTO SATURDAY EVENING. THERE IS A SMALL CHANCE THAT EVEN
GALE FORCE WIND GUSTS MIGHT OCCUR FOR A TIME ON SATURDAY. SMALL
CRAFT ADVISORY WIND GUSTS MIGHT LINGER ON THE OCEAN INTO SUNDAY
MORNING. AFTER THAT SUB SMALL CRAFT ADVISORY CONDITIONS ARE
EXPECTED FOR THE REST OF THE HOLIDAY WEEKEND.
&&
.RIP CURRENTS...
THERE IS A MODERATE RISK FOR THE FORMATION OF DANGEROUS RIP
CURRENTS ALONG THE COAST OF NEW JERSEY TODAY.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT FRIDAY FOR ANZ450>455.
&&
$$
SYNOPSIS...GIGI/O`HARA
NEAR TERM...KLINE/ROBERTSON
SHORT TERM...ROBERTSON
LONG TERM...GIGI
AVIATION...GIGI/ROBERTSON/O`HARA/KLINE
MARINE...GIGI/ROBERTSON/O`HARA
RIP CURRENTS...ROBERTSON/KLINE
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
1057 AM EDT Thu May 23 2013
.NEAR TERM [Rest of Today]...
The 12 UTC sounding from our office had a relatively moist profile
with a PWAT of 1.53". However, drier air is situated just to the
northwest, with the Birmingham (BMX) sounding indicating much
drier air in the 950-800mb layer. This is portrayed in the latest
objective RAP analysis which shows the leading edge of the drier
air just arriving in our southeast Alabama zones. This is expected
to push into the northwest half of our area by early afternoon,
and as boundary layer mixing increases, surface dewpoints should
decrease markedly. The advection of drier air from the northwest
will also set up a low-level thetae gradient somewhere near an
AAF-VLD line by afternoon. Various convection-allowing models show
scattered showers and thunderstorms developing in the unstable
environment ahead of this boundary in the afternoon - mainly in
Taylor, Lafayette, and Dixie counties. Therefore, a 20% PoP was
added in areas southeast of Tallahassee. It wouldn`t be out of the
question for some of the storms to produce some hail or gusty
winds, but widespread or organized severe weather is not expected.
Otherwise, it looks like a mostly sunny and seasonably warm day
with highs within a couple degrees of 90 in most spots.
&&
.SHORT TERM [Tonight through Sunday]...
TONIGHT...the large scale longwave pattern remains highly amplified
with full latitude trough over Wrn, ridge over Cntrl and trough over
Ern states followed by ridge over extreme Wrn Atlc. Low assocd with
Ern trough continuing to weaken as it shears NEWD. At surface, low
vcnty PA with weakening cold front Swd to N GA then SWWD across SE
AL. During the rest of overnight hours, axis of Ern trough to move
to Ern seaboard with rapidly weakening mainly dry front reaching
extreme Nrn Gulf waters by sunrise FRI.
FRIDAY THRU SUNDAY...By Fri eve, trough axis and assocd low just
off Ern seaboard. In their wake, upper ridge will build NWD from
Wrn Gulf of Mex while surface high pressure builds SWD from the
OH/ TN Valleys to the Nrn Gulf. Assocd ridge will continue to
build SEWD Fri night into SAT with high centered NNE of region.
Locally this places local area between departing trough and
advancing upstream ridge yielding a much cooler and drier airmass
with NW steering flow. Flow aloft becoming WNW by Sun, and with
NLY flow at lower levels veering to NE on Sat and ESE on Sun. The
result is a reinforcing dry airmass heralding an ideal weekend
with mostly clear skies, low dew points and cool nights.
10% pops tonight then no POPs thru period. Inland Lows tonight low
to mid 60s dropping Fri and Sat nights in wake of front to mid 50s.
Highs generally mid to upper 80s. Invading drier air should limit
fog chances thru period.
&&
.LONG TERM [Sunday Night through Wednesday]...
Upper ridging will build over the area through Memorial Day and
into the middle of next week. This will leave somewhat tranquil
conditions in place with a seasonably cool start to the period and
a gradual warm up into the early part of the week, with little or
no rain outside of possible isolated showers along the sea breeze.
&&
.AVIATION...[through 06 UTC Friday]
Areas of fog will develop in the pre-dawn hours. Some of the fog may
become dense especially in places that received rain. VFR conditions
will return across the entire region after 14Z. Winds will be from
the west to northwest in the 10 to 15 knot range with higher
gusts.
&&
.MARINE...
Fairly low winds and seas will persist into Friday, when offshore
winds will increase in the wake of a surface cold front late
Friday night into Saturday. Seas will eventually build as well in
the offshore legs with cautionary wind speeds expected Friday night.
winds will veer and along with seas decrease thru the rest of the
weekend.
&&
.FIRE WEATHER...
A much drier airmass will be filtering into the region over the next
few days. Today the minimum relative humidity should stay above
critical levels but is forecast to drop at or just below 28 percent
over interior portions of the Florida Panhandle and western Big Bend
Friday afternoon. This combined with elevated ERC values and
sustained winds at or above 15 mph will possibly meet Red flag
conditions. A fire weather watch has been posted and may be upgraded
to a warning later today. A fire weather watch will also be issued
for our SE Alabama counties Friday due to a combination of long
durations of low RH, KBDI over 500 and sustained winds at or above
10 mph. Low relative humidities are also expected across our Georgia
zones Friday but the 10-hour fuel moisture should remain above 6
percent. Red Flag conditions are also possible across portions of
north Florida and our southeast Alabama counties again on Saturday.
On top of all this, dispersions will be very high across north
Florida this afternoon and again on Friday with forecast values
approaching 120.
&&
.HYDROLOGY...
No issues are forecast along area rivers for the foreseeable future.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 92 66 89 56 87 / 10 10 10 10 0
Panama City 87 75 87 66 81 / 10 10 10 10 0
Dothan 91 66 87 55 86 / 0 10 10 10 0
Albany 90 64 85 55 85 / 10 10 10 10 0
Valdosta 92 63 87 56 85 / 10 10 10 10 0
Cross City 88 67 89 58 86 / 20 10 10 10 0
Apalachicola 84 72 87 66 82 / 10 10 10 10 0
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...FIRE WEATHER WATCH from Friday afternoon through Friday
evening for Calhoun-Gadsden-Holmes-Inland Walton-Jackson-
Liberty-Washington.
GA...None.
AL...FIRE WEATHER WATCH from Friday afternoon through Friday
evening for Coffee-Dale-Geneva-Henry-Houston.
GM...None.
&&
$$
NEAR TERM...Lamers
SHORT TERM...Block
LONG TERM...Evans
AVIATION...Barry
MARINE...Block
FIRE WEATHER...Barry
HYDROLOGY...Evans/Block
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
950 AM EDT THU MAY 23 2013
.UPDATE (REST OF TODAY AND TONIGHT)...
13Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS A RATHER CHAOTIC UPPER
LEVEL PATTERN IN PLACE ACROSS THE CONUS. PATTERN IS DOMINATED BY
THREE LONGWAVE FEATURES. LOOKING FAR UPSTREAM WE FIND A LARGE AND
VIGOROUS UPPER LEVEL LOW SPINNING OVER THE PACIFIC NORTHWEST. MAIN
FLOW AROUND THE SOUTHERN PERIPHERY OF THIS CIRCULATION EMERGES
THROUGH THE FOUR-CORNERS REGION AND THEN RIDGES UP OVER THE CENTRAL
PLAINS. THIS FLOW THEN QUICKLY DIVES BACK TO THE SOUTHEAST AND
MERGES WITH AN IMPRESSIVE LONGWAVE TROUGH PIVOTING THROUGH MUCH OF
EASTERN CANADA AND THE EASTERN CONUS. OUR FORECAST AREA RESIDES NEAR
THE SOUTHERN PERIPHERY/BASE OF THIS EASTERN TROUGH. WV IMAGERY
CLEARLY DEFINES A WEAK SHORTWAVE EMBEDDED WITHIN THE FLOW WITHIN THE
BASE OF THE LONGWAVE TROUGH WHICH WILL PIVOT THROUGH THE REGION THIS
MORNING AND EARLY AFTERNOON.
BEHIND THIS SHORTWAVE FOR THE SECOND HALF OF THE DAY/EVENING THE
DEPTH OF DRY AIR WITHIN THE COLUMN WILL INCREASE (ESPECIALLY OVER
THE NORTHERN HALF OF THE AREA AS WEAK NVA AND DEEP LAYER SUBSIDENCE
ARRIVES FROM THE WEST AND NORTHWEST.
THE PASSAGE OF THIS SHORTWAVE TO OUR EAST BEFORE THE TIME OF PEAK
DIURNAL HEATING WILL WORK IN THE FAVOR FOR THOSE LOOKING FOR LESS
CONVECTIVE ACTIVITY THAN HAS BEEN SEEN THE PAST COUPLE OF DAYS.
STILL UNLIKELY THAT THIS SETUP WILL BE ENOUGH TO COMPLETELY SUPPRESS
THE THUNDERSTORM THREAT FOR ALL AREAS. SEEING A FEW FAVORABLE
ASPECTS IN THE SHORT TERM FOR UPDRAFT INITIATION AND SUPPORT. WILL
BE WATCHING A WEAK LOW LEVEL TROUGH DROP SOUTH TOWARD THE I-10
CORRIDOR EARLY THIS AFTERNOON. LOW LEVEL FOCUS ALONG AND JUST SOUTH
OF THIS BOUNDARY MAY BE ENOUGH TO SUPPORT A FEW SHOWERS/STORMS UP
TOWARD LEVY COUNTY BY MID AFTERNOON BEFORE THE MORE SIGNIFICANTLY
HOSTILE AIR ALOFT TOWARD CONVECTION ARRIVES. LOCAL HIGH-RES WRFARW
SIMULATIONS ARE IN FAVOR OF THIS CONVECTIVE DEVELOPMENT...BUT ALSO
KEEP THE CONVECTION FAIRLY SHALLOW WITH UPDRAFT RATES THAT ARE
GENERALLY UNSUPPORTIVE OF SIGNIFICANT WEATHER. BY THIS
EVENING...THETA-E VALUES AROUND 700MB ARE WELL BELOW 320K UP TOWARD
CHIEFLAND WHICH WILL MAKE IT VERY DIFFICULT FOR ANY CUMULUS TOWERS
ATTEMPTING TO GROW.
THE OTHER AREA WE AREA LOOKING FOR WIDELY SCATTERED CONVECTIVE
ACTIVITY IS ACROSS OUR INTERIOR SOUTHERN ZONES...MAINLY WELL INLAND
FROM I-75. MORE FAVORABLE MOISTURE PROFILES WILL HOLD ON A LITTLE
LONGER DOWN TOWARD THESE AREA...AND A RAPID INLAND PROPAGATION OF
THE SEA-BREEZE WILL ADD SOME LOWER LEVEL FOCUS.
LESS CONVECTIVE ACTIVITY AND 850MB TEMPS OF 16-17C GIVE THE
BOUNDARY LAYER A WARM POTENTIAL TODAY. THOSE AREAS NOT SEEING ANY
QUICK SHOWER AND AWAY FROM THE BEACHES SHOULD EASILY MIX OUT INTO
THE LOWER 90S...WITH WARMER SPOTS PEAKING IN THE MID 90S. ONSHORE
FLOW DEVELOPING QUICKLY TODAY WILL HOLD THE BEACHES IN THE 80S.
PATTERN SUGGESTS ANY LINGERING STORMS BY MID-EVENING WILL BE OVER
TOWARD THE I-95 CORRIDOR WHICH SHOULD SET UP A MAINLY DRY...QUIET
AND SEASONABLE OVERNIGHT PERIOD. ENJOY!
&&
.AVIATION...
PREVAILING VFR WITH FEW-SCT CLOUDS. LIGHT AND VARIABLE WINDS BECOME
WESTERLY LATE MORNING AND AFTERNOON...KEEPING LIMITED TSRA EAST OF
THE TERMINALS.
&&
.MARINE...
WINDS AND SEAS WILL REMAIN RATHER LIGHT THROUGH TODAY AND
TONIGHT. A WEAKENING COLD FRONT WILL SLIDE SOUTHWARD THROUGH THE
WATERS FRIDAY AND FRIDAY NIGHT...WITH STRONG HIGH PRESSURE THEN
BUILDING NORTH OF THE STATE OVER THE WEEKEND INTO EARLY NEXT WEEK.
ELEVATED EASTERLY FLOW WILL LIKELY RESULT IN A NEED FOR EXERCISE
CAUTION OR ADVISORY HEADLINES FOR MUCH OF THE MARINE AREA DURING THE
EVENING AND OVERNIGHT HOURS EACH DAY THROUGH THE PERIOD.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 90 73 91 71 / 0 0 0 0
FMY 91 72 91 72 / 10 10 10 10
GIF 92 71 93 68 / 20 10 10 0
SRQ 86 71 89 71 / 0 0 0 0
BKV 90 65 91 63 / 10 0 10 0
SPG 90 75 89 74 / 0 0 0 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE...MROCZKA
AVIATION...RUDE
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1103 AM CDT THU MAY 23 2013
.DISCUSSION...
240 AM CDT
TODAY...
FORECAST CHALLENGES FOR TODAY RESIDE WITH HIGH TEMPS...AND PRECIP
CHANCES THIS MORNING.
IR IMAGERY EARLY THIS MORNING SHOWS CONSIDERABLE CLOUD COVER
REMAINING ACROSS THE WESTERN GREAT LAKES...EXTENDING SOUTH THROUGH
THE MID-MISSISSIPPI VALLEY. ALONG THE WESTERN PERIPHERY OF THE CLOUD
COVER LIES THE LEADING EDGE OF THE STRONG SFC RIDGE...BEGINNING TO
PUSH INTO THE UPPER MIDWEST/NORTHERN PLAINS. MOISTURE HAS BEEN
CONSISTENTLY PEELING OFF TO THE NORTHEAST...NOTED IN THE STEADILY
LOWERING DEW POINTS. DEW POINTS ACROSS CENTRAL WISC HAVE ALREADY
FALLEN INTO THE UPR 40S...AND EXPECT THIS TREND TO EVENTUALLY ARRIVE
ACROSS NORTHERN IL/NORTHWEST IN. A BROAD SFC TROUGH WAS ANALYZED
ACROSS NORTHEAST IL STRETCHING INTO SOUTHCENTRAL LOWER MI. AS A
RESULT SFC WINDS ACROSS THE CWFA HAVE MAINLY BEEN FROM THE
WEST/SOUTHWEST...HOWEVER JUST NORTH OF THE CWFA INTO WISC WINDS HAVE
ALREADY SHIFTED TO THE NORTHWEST/NORTH. LOCATIONS ADJACENT TO LAKE
MICHIGAN WILL SEE WINDS FLOP OVER TO THE NORTHEAST THIS
MORNING...ALLOWING THE MUCH COOLER MARINE ENVIRONMENT TO READILY
FLOW ACROSS THE LAND.
REGIONAL RADAR EARLY THIS MORNING SHOWS AN AREA OF SHOWERS ACROSS
CENTRAL WISC...SLOWLY SLIDING SOUTHEAST. HI-RES GUIDANCE SUGGESTS
THIS CHANNEL OF PRECIP WILL EVENTUALLY ARRIVE ACROSS NORTHERN IL
JUST BEFORE DAYBREAK. AS A RESULT OF THE INCREASED CONFIDENCE IN
PRECIP...HAVE NUDGED THE 12-15Z TIMEFRAME TO LIKELY POPS FOR FAR
NORTHEAST IL.
DRY AIR CONTINUES TO POUR INTO THE REGION MID-MORNING...AND SHOULD
BRING AN END TO THE PRECIP FROM NORTHWEST TO SOUTHEAST ACROSS THE
CWFA BY EARLY THIS AFTERNOON. THE STEADY PUSH OF DRY AIR WILL ALSO
AID IN ERODING THE CLOUD COVER...AND BY LATE THIS AFTERNOON EXPECT
MOSTLY SUNNY SKIES TO DEVELOP. COLD AIR ADVECTION WILL DOMINATE THE
DAY...COUPLED PRECIP AND CLOUDS...EXPECT MUCH COOLER TEMPS FOR THIS
AFTERNOON. GUIDANCE HAS CONTINUED TO SUGGEST TEMPS WILL STRUGGLE TO
WARM BEYOND THE LOW 60S FOR THE FAR WESTERN CWFA...MEANWHILE FURTHER
EAST TEMPS WILL ONLY WARM A FEW DEGREES FROM THEIR STARTING POINT.
THIS WILL MOST LIKELY LEAD TO AREAS EAST OF I-39 ONLY WARMING INTO
THE MID/UPR 50S. LOCATIONS IMMEDIATELY ADJACENT TO LAKE MICHIGAN
COULD SEE TEMPS STRUGGLE TO WARM BEYOND 50 DEGREES.
CONFIDENCE IN PRECIP ENDING TIME...MEDIUM/HIGH.
CONFIDENCE IN TEMPERATURES...HIGH.
TONIGHT...
ANTI-CYCLONIC FLOW WILL CONTINUE TO BUILD OVERHEAD EARLY THIS
EVENING...AND ERODE ANY LINGERING CLOUDS BY MIDNIGHT. DEW POINTS AS
A RESULT WILL CONTINUE TO DRY...BOTTOMING OUT IN THE MID 30S IN MANY
LOCATIONS. THE COMBINATION OF NEAR CLOUDLESS SKIES...LIGHT NORTH TO
AT TIMES CALM WINDS...AND RECENT RAINFALL...WILL SET THE STAGE FOR
NOT ONLY STRONG RADIATIONAL COOLING BUT PATCHY FROST AWAY FROM LAKE
MICHIGAN. GUIDANCE CONTINUES TO PROG TEMPS FALLING OVERNIGHT INTO
THE MID/UPR 30S FOR AREAS WEST OF WAUKEGAN TO KANKAKEE. FAR SOUTHERN
PORTIONS OF THE CWFA SHOULD HAVE TEMPS HOLD ARND 40 DEGREES
OVERNIGHT...HOWEVER A FEW LOW-LYING AREAS COULD SEE SPOTTY FROST. AT
THIS POINT IT DOES NOT APPEAR TO BE A WIDESPREAD FROST SETUP...SO
WILL HOLD OFF ON ANY HEADLINES AT THIS POINT.
CONFIDENCE...HIGH.
FRIDAY...
SFC HIGH PRESSURE WILL DOMINATE THE REGION FOR THE END OF THE
WEEK...AND MORE THAN LIKELY ONLY ALLOW A FEW DIURNAL CLOUDS TO
DEVELOP. A LIGHT NORTHEAST FLOW OFF OF LAKE MICHIGAN WILL CONTINUE
TO KEEP ADJACENT AREAS MUCH COOLER IN THE MID/UPR 50S...MEANWHILE
INLAND LOCATIONS WILL BEGIN TO WARM INTO THE LOW/MID 60S.
WITH HIGH PRESSURE STILL IN CONTROL FRIDAY NIGHT...EXPECT ANOTHER
NIGHT OF STRONG RADIATIONAL COOLING. THE ONLY DIFFERENCE FOR FRI
NIGHT WILL BE THE RIDGE AXIS WILL HAVE SHIFTED EAST. THIS WILL ALLOW
THE LIGHT WINDS TO BEGIN TURNING SOUTHEASTERLY AFTER MIDNIGHT...AND
COULD SLOW THE RATE OF COOLING. HAVE MAINTAINED TEMPS IN THE LOW 40S
FOR MANY AREAS. COULD SEE A FEW OF THE TRADITIONAL COOL SPOTS DIP TO
THE UPR 30S EARLY SAT MORNING...HOWEVER AT THIS POINT NOT
ANTICIPATING FROST FORMATION.
CONFIDENCE IN TEMPERATURES...HIGH.
SATURDAY...
DISCREPANCIES BEGIN TO EMERGE AMONGST SOLUTIONS FOR SAT...WITH
RESPECT TO PLACEMENT/TIMING OF A MOIST BOUNDARY. GFS HAS CONTINUED
TO BE THE MORE PROGRESSIVE SOLUTION...BRINGING THIS CHANNEL OF
MOISTURE/PRECIP INTO THE REGION AND STRETCHES FROM THE NORTHERN
PLAINS SOUTHEAST THROUGH THE OHIO VALLEY. MEANWHILE THE EC HAS
MAINTAINED THE SFC RIDGE...AND SUPPRESSING THE MOIST CHANNEL TO THE
SOUTHWEST OF THE CWFA.
THE LARGEST WEATHER PLAYER IS THE DOWNSTREAM 500MB RIDGE LOCATED
ACROSS THE WESTERN ATLANTIC. THIS WILL ACT AS A BLOCK...SLOWING THE
DEPARTURE OF THE MID-LVL TROUGH ACROSS THE MID-ATLANTIC REGION. THEN
FURTHER UPSTREAM YET ANOTHER 500MB RIDGE WAS PROGGED TO ARRIVE
ACROSS THE CENTRAL CONUS...AND DOES SHOW SOME SIGNS OF
AMPLIFICATION. BASED ON THIS SETUP IT IS BECOMING MORE EVIDENT THAT
SAT COULD END UP BEING DRY...AND POSSIBLY EXTEND INTO SUN. AT THIS
POINT HAVE ONLY ADJUSTED POPS SAT MARGINALLY...TO SLIGHT CHANCE
WORDING.
SFC TEMPS WILL REMAIN UNSEASONABLY COOL IN THE LOW/MID 60S...WITH
AREAS ADJACENT TO LAKE MICHIGAN BEING EVEN COOLER THAN THIS. DESPITE
THE EXPECTED SOUTHEAST COMPONENT TO THE SFC WINDS...ENOUGH HEATING
COULD ALLOW A LAKE BREEZE TO FORM AND ALLOW WINDS TO BECOME MORE
EASTERLY FOR LOCATIONS ADJACENT TO LAKE MICHIGAN. THIS WILL MOST
LIKELY RESULT IN THOSE AREAS IMMEDIATELY NEXT TO THE LAKE REMAINING
IN THE 50S SAT AFTN.
CONFIDENCE...MEDIUM.
SUNDAY THROUGH WEDNESDAY...
FOR THE EXTENDED PERIODS GUIDANCE HAS CONTINUED TO DEMONSTRATE
MINIMAL CHANGES FROM PREVIOUS SOLUTIONS...HOWEVER OPERATIONAL
ECMWF/GFS CONTINUE TO DIFFER ON THE PLACEMENT/TIMING OF PRECIP. THE
ECMWF CONTINUES TO SUGGEST THE SFC RIDGE FROM LATE IN THE WEEK WILL
HOLD TOUGH AND KEEP NORTHERN IL/NORTHWEST IN DRY THRU THE WEEKEND
AND INTO EARLY NEXT WEEK. MEANWHILE THE GFS IS STILL MORE
PROGRESSIVE AND BRINGS THE BOUNDARY OVERHEAD AND BECOMES
QUASI-STATIONARY THRU THE FIRST HALF OF NEXT WEEK.
ENSEMBLES CONTINUE TO INDICATE THE WESTERN ATLANTIC MID-LVL RIDGE
WILL WEAKEN...ALLOWING THE 500MB TROUGH TO FINALLY EJECT EAST. IN
ADDITION THE UPSTREAM RIDGE WILL BEGIN TO FLATTEN...LEADING TO A
SOMEWHAT PROGRESSIVE FLOW OF SYSTEMS FROM WEST TO EAST TOWARDS THE
MIDDLE OF NEXT WEEK. THUS PRECIP CHC WILL BE ON THE INCREASE TOWARDS
THE FINAL FEW PERIODS OF THE CURRENT EXTENDED FORECAST.
BY TUE/WED OF NEXT WEEK...TEMPS COULD EASILY BE BACK INTO THE UPR
70S TO LOW 80S.
CONFIDENCE IN PRECIPITATION...LOW.
CONFIDENCE IN TEMPERATURES...HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* VARIABLE MVFR/IFR CIG SLOWLY IMPROVING AOA 1500 FT AROUND 17Z.
VFR/CLEARING BY MID AFTN.
* NORTH WIND WITH GUSTS TO AROUND 30 KT CONTINUING THROUGH AFTN.
ALLSOPP/BMD
//DISCUSSION...UPDATED 12Z...
MAIN CONCERN THIS MORNING IS CIG TRENDS...THEN THIS AFTERNOON
FOCUS WILL BE ON STRONG GUSTY NNE WINDS. LOW PRESSURE WAS OVER
THE EASTERN GREAT LAKES WITH A COLD FRONT TRAILING WESTWARD INTO
NORTHERN IL. AT 11Z THE FRONT WAS FROM ABOUT IKK-VYS. BASED ON
NAM AND HRRR MODEL SOUNDINGS...CIGS SHOULD SLOWLY IMPROVE TO
AROUND 1000-1200 FT IN THE NEXT COUPLE HOURS. THIS SEEMS
REASONABLE WITH STRONGER WINDS MIXING COLDER AND SLIGHTLY DRIER
AIR DOWN FROM THE NORTH. ALSO SPOTTY LIGHT RAIN/DRIZZLE WILL BE
DIMINISHING/MOVING OUT AND THAT MAY ALSO HELP IMPROVE CIG AND VSBY
A BIT THIS MORNING. AS OF 11Z THE BACK EDGE OF THE MAIN BAND OF
RAIN ASSOCIATED WITH THE COLD FRONT WAS LINED UP FROM DKB-DPA-
MDW-GYY AND SINKING VERY SLOWLY S. THERE WERE SOME VSBY
RESTRICTIONS DOWN TO 2-3 MILES IN THIS BAND OF RAIN...BUT IT HAS
PUSHED SOUTH OF THE TERMINALS. FURTHER NORTH INTO SOUTHERN WI
THERE WERE SOME PATCHES OF LIGHT RAIN/DRIZZLE..BUT THIS WAS VERY
LIGHT. SHORT RANGE/HI RES MODELS SUGGEST THIS SPOTTY LIGHT RAIN
WILL BE DRYING UP AND MOVING SE OUT OF THE AREA BY MID TO LATE
MORNING. THEREFORE DONT EXPECT ANY SIGNIFICANT VSBY RESTRICTIONS
BELOW 5 OR 6 MILES THE REST OF THE MORNING. AS STRONG NORTH WINDS
CONTINUE TO PUSH COLDER DRIER AIR DOWN...EXPECT CLOUDS TO LIFT TO
1500 FT OR BETTER BY NOON AND BREAK UP THIS AFTERNOON WITH
CLEARING MID TO LATE AFTN.
NORTH WINDS HAVE PICKED UP AND WINDS WILL CONTINUE TO INCREASE TO
20 TO 30 KT BY MID MORNING. DIRECTION MAY VARY SOME FROM 350-030
BUT WILL BE PREDOMINANTLY JUST E OF N TODAY. PRESSURE GRADIENT
SLOWLY BEGINS TO RELAX LATE THIS AFTERNOON AND WINDS MAY DIMINISH
SLIGHTLY DURING THE LATE AFTN. ATMOSPHERE SHOULD BEGIN TO DECOUPLE
THIS EVENING AS PRESSURE GRADIENT CONTINUES TO RELAX.
OUTLOOK FOR FRIDAY IS VFR WITH LIGHT NORTHEAST WINDS.
ALLSOPP
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM-HIGH CONFIDENCE IN CIG TRENDS THIS MORNING.
* MEDIUM CONFIDENCE IN TIMING OF CLEARING THIS AFTN.
* HIGH CONFIDENCE IN WIND FORECAST. DIRECTION MAY VARY FROM
350-030.
ALLSOPP/BMD
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT AND SATURDAY...VFR. WX NIL.
SUNDAY AND MONDAY...VFR. CHC SHRA SLIGHT CHC TSRA.
TUESDAY AND WEDNESDAY...CHC TSRA.
ALLSOPP
&&
.MARINE...
147 AM CDT
EARLY THURSDAY MORNING AN ELONGATED AREA OF LOW PRESSURE WAS FROM
THE EASTERN GREAT LAKES BACK TO NORTHERN ILLINOIS...WHILE A STRONG
AREA OF HIGH PRESSURE WAS CENTERED OVER NORTHERN MANITOBA WITH A
RIDGE EXTENDING SOUTHWARD INTO THE NORTHERN PLAINS. AS THE TROF
SWINGS EAST AND THE RIDGE BUILDS INTO THE WESTERN GREAT LAKES
TODAY...GALE FORCE NORTH WINDS WILL DEVELOP OVER LAKE MICHIGAN.
THE GALES WILL DEVELOP OVER CENTRAL LAKE MICHIGAN EARLY THIS
MORNING AND SPREAD TO THE SOUTH END BY MID OR LATE MORNING. WINDS
WILL DIMINISH OVERNIGHT AS THE HIGH SETTLES OVER THE WESTERN GREAT
LAKES AND THE LOW MOVES UP THE EAST COAST. THE HIGH WILL THEN BE
NEARLY STATIONARY OVER THE GREAT LAKES THROUGH THE WEEKEND WITH
LIGHT EAST TO SOUTHEAST FLOW OVER THE LAKE. LOW PRESSURE WILL MOVE
FROM THE CENTRAL PLAINS TO THE UPPER MISSISSIPPI VALLEY MONDAY AND
TUESDAY WHICH WILL CAUSE WINDS TO BECOME SOUTHERLY OVER LAKE
MICHIGAN.
ALLSOPP
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-
LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ872-LMZ874-LMZ876-
LMZ878 UNTIL 9 PM THURSDAY.
GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870 UNTIL 3
PM THURSDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
907 AM CDT THU MAY 23 2013
.DISCUSSION...
240 AM CDT
TODAY...
FORECAST CHALLENGES FOR TODAY RESIDE WITH HIGH TEMPS...AND PRECIP
CHANCES THIS MORNING.
IR IMAGERY EARLY THIS MORNING SHOWS CONSIDERABLE CLOUD COVER
REMAINING ACROSS THE WESTERN GREAT LAKES...EXTENDING SOUTH THROUGH
THE MID-MISSISSIPPI VALLEY. ALONG THE WESTERN PERIPHERY OF THE CLOUD
COVER LIES THE LEADING EDGE OF THE STRONG SFC RIDGE...BEGINNING TO
PUSH INTO THE UPPER MIDWEST/NORTHERN PLAINS. MOISTURE HAS BEEN
CONSISTENTLY PEELING OFF TO THE NORTHEAST...NOTED IN THE STEADILY
LOWERING DEW POINTS. DEW POINTS ACROSS CENTRAL WISC HAVE ALREADY
FALLEN INTO THE UPR 40S...AND EXPECT THIS TREND TO EVENTUALLY ARRIVE
ACROSS NORTHERN IL/NORTHWEST IN. A BROAD SFC TROUGH WAS ANALYZED
ACROSS NORTHEAST IL STRETCHING INTO SOUTHCENTRAL LOWER MI. AS A
RESULT SFC WINDS ACROSS THE CWFA HAVE MAINLY BEEN FROM THE
WEST/SOUTHWEST...HOWEVER JUST NORTH OF THE CWFA INTO WISC WINDS HAVE
ALREADY SHIFTED TO THE NORTHWEST/NORTH. LOCATIONS ADJACENT TO LAKE
MICHIGAN WILL SEE WINDS FLOP OVER TO THE NORTHEAST THIS
MORNING...ALLOWING THE MUCH COOLER MARINE ENVIRONMENT TO READILY
FLOW ACROSS THE LAND.
REGIONAL RADAR EARLY THIS MORNING SHOWS AN AREA OF SHOWERS ACROSS
CENTRAL WISC...SLOWLY SLIDING SOUTHEAST. HI-RES GUIDANCE SUGGESTS
THIS CHANNEL OF PRECIP WILL EVENTUALLY ARRIVE ACROSS NORTHERN IL
JUST BEFORE DAYBREAK. AS A RESULT OF THE INCREASED CONFIDENCE IN
PRECIP...HAVE NUDGED THE 12-15Z TIMEFRAME TO LIKELY POPS FOR FAR
NORTHEAST IL.
DRY AIR CONTINUES TO POUR INTO THE REGION MID-MORNING...AND SHOULD
BRING AN END TO THE PRECIP FROM NORTHWEST TO SOUTHEAST ACROSS THE
CWFA BY EARLY THIS AFTERNOON. THE STEADY PUSH OF DRY AIR WILL ALSO
AID IN ERODING THE CLOUD COVER...AND BY LATE THIS AFTERNOON EXPECT
MOSTLY SUNNY SKIES TO DEVELOP. COLD AIR ADVECTION WILL DOMINATE THE
DAY...COUPLED PRECIP AND CLOUDS...EXPECT MUCH COOLER TEMPS FOR THIS
AFTERNOON. GUIDANCE HAS CONTINUED TO SUGGEST TEMPS WILL STRUGGLE TO
WARM BEYOND THE LOW 60S FOR THE FAR WESTERN CWFA...MEANWHILE FURTHER
EAST TEMPS WILL ONLY WARM A FEW DEGREES FROM THEIR STARTING POINT.
THIS WILL MOST LIKELY LEAD TO AREAS EAST OF I-39 ONLY WARMING INTO
THE MID/UPR 50S. LOCATIONS IMMEDIATELY ADJACENT TO LAKE MICHIGAN
COULD SEE TEMPS STRUGGLE TO WARM BEYOND 50 DEGREES.
CONFIDENCE IN PRECIP ENDING TIME...MEDIUM/HIGH.
CONFIDENCE IN TEMPERATURES...HIGH.
TONIGHT...
ANTI-CYCLONIC FLOW WILL CONTINUE TO BUILD OVERHEAD EARLY THIS
EVENING...AND ERODE ANY LINGERING CLOUDS BY MIDNIGHT. DEW POINTS AS
A RESULT WILL CONTINUE TO DRY...BOTTOMING OUT IN THE MID 30S IN MANY
LOCATIONS. THE COMBINATION OF NEAR CLOUDLESS SKIES...LIGHT NORTH TO
AT TIMES CALM WINDS...AND RECENT RAINFALL...WILL SET THE STAGE FOR
NOT ONLY STRONG RADIATIONAL COOLING BUT PATCHY FROST AWAY FROM LAKE
MICHIGAN. GUIDANCE CONTINUES TO PROG TEMPS FALLING OVERNIGHT INTO
THE MID/UPR 30S FOR AREAS WEST OF WAUKEGAN TO KANKAKEE. FAR SOUTHERN
PORTIONS OF THE CWFA SHOULD HAVE TEMPS HOLD ARND 40 DEGREES
OVERNIGHT...HOWEVER A FEW LOW-LYING AREAS COULD SEE SPOTTY FROST. AT
THIS POINT IT DOES NOT APPEAR TO BE A WIDESPREAD FROST SETUP...SO
WILL HOLD OFF ON ANY HEADLINES AT THIS POINT.
CONFIDENCE...HIGH.
FRIDAY...
SFC HIGH PRESSURE WILL DOMINATE THE REGION FOR THE END OF THE
WEEK...AND MORE THAN LIKELY ONLY ALLOW A FEW DIURNAL CLOUDS TO
DEVELOP. A LIGHT NORTHEAST FLOW OFF OF LAKE MICHIGAN WILL CONTINUE
TO KEEP ADJACENT AREAS MUCH COOLER IN THE MID/UPR 50S...MEANWHILE
INLAND LOCATIONS WILL BEGIN TO WARM INTO THE LOW/MID 60S.
WITH HIGH PRESSURE STILL IN CONTROL FRIDAY NIGHT...EXPECT ANOTHER
NIGHT OF STRONG RADIATIONAL COOLING. THE ONLY DIFFERENCE FOR FRI
NIGHT WILL BE THE RIDGE AXIS WILL HAVE SHIFTED EAST. THIS WILL ALLOW
THE LIGHT WINDS TO BEGIN TURNING SOUTHEASTERLY AFTER MIDNIGHT...AND
COULD SLOW THE RATE OF COOLING. HAVE MAINTAINED TEMPS IN THE LOW 40S
FOR MANY AREAS. COULD SEE A FEW OF THE TRADITIONAL COOL SPOTS DIP TO
THE UPR 30S EARLY SAT MORNING...HOWEVER AT THIS POINT NOT
ANTICIPATING FROST FORMATION.
CONFIDENCE IN TEMPERATURES...HIGH.
SATURDAY...
DISCREPANCIES BEGIN TO EMERGE AMONGST SOLUTIONS FOR SAT...WITH
RESPECT TO PLACEMENT/TIMING OF A MOIST BOUNDARY. GFS HAS CONTINUED
TO BE THE MORE PROGRESSIVE SOLUTION...BRINGING THIS CHANNEL OF
MOISTURE/PRECIP INTO THE REGION AND STRETCHES FROM THE NORTHERN
PLAINS SOUTHEAST THROUGH THE OHIO VALLEY. MEANWHILE THE EC HAS
MAINTAINED THE SFC RIDGE...AND SUPPRESSING THE MOIST CHANNEL TO THE
SOUTHWEST OF THE CWFA.
THE LARGEST WEATHER PLAYER IS THE DOWNSTREAM 500MB RIDGE LOCATED
ACROSS THE WESTERN ATLANTIC. THIS WILL ACT AS A BLOCK...SLOWING THE
DEPARTURE OF THE MID-LVL TROUGH ACROSS THE MID-ATLANTIC REGION. THEN
FURTHER UPSTREAM YET ANOTHER 500MB RIDGE WAS PROGGED TO ARRIVE
ACROSS THE CENTRAL CONUS...AND DOES SHOW SOME SIGNS OF
AMPLIFICATION. BASED ON THIS SETUP IT IS BECOMING MORE EVIDENT THAT
SAT COULD END UP BEING DRY...AND POSSIBLY EXTEND INTO SUN. AT THIS
POINT HAVE ONLY ADJUSTED POPS SAT MARGINALLY...TO SLIGHT CHANCE
WORDING.
SFC TEMPS WILL REMAIN UNSEASONABLY COOL IN THE LOW/MID 60S...WITH
AREAS ADJACENT TO LAKE MICHIGAN BEING EVEN COOLER THAN THIS. DESPITE
THE EXPECTED SOUTHEAST COMPONENT TO THE SFC WINDS...ENOUGH HEATING
COULD ALLOW A LAKE BREEZE TO FORM AND ALLOW WINDS TO BECOME MORE
EASTERLY FOR LOCATIONS ADJACENT TO LAKE MICHIGAN. THIS WILL MOST
LIKELY RESULT IN THOSE AREAS IMMEDIATELY NEXT TO THE LAKE REMAINING
IN THE 50S SAT AFTN.
CONFIDENCE...MEDIUM.
SUNDAY THROUGH WEDNESDAY...
FOR THE EXTENDED PERIODS GUIDANCE HAS CONTINUED TO DEMONSTRATE
MINIMAL CHANGES FROM PREVIOUS SOLUTIONS...HOWEVER OPERATIONAL
ECMWF/GFS CONTINUE TO DIFFER ON THE PLACEMENT/TIMING OF PRECIP. THE
ECMWF CONTINUES TO SUGGEST THE SFC RIDGE FROM LATE IN THE WEEK WILL
HOLD TOUGH AND KEEP NORTHERN IL/NORTHWEST IN DRY THRU THE WEEKEND
AND INTO EARLY NEXT WEEK. MEANWHILE THE GFS IS STILL MORE
PROGRESSIVE AND BRINGS THE BOUNDARY OVERHEAD AND BECOMES
QUASI-STATIONARY THRU THE FIRST HALF OF NEXT WEEK.
ENSEMBLES CONTINUE TO INDICATE THE WESTERN ATLANTIC MID-LVL RIDGE
WILL WEAKEN...ALLOWING THE 500MB TROUGH TO FINALLY EJECT EAST. IN
ADDITION THE UPSTREAM RIDGE WILL BEGIN TO FLATTEN...LEADING TO A
SOMEWHAT PROGRESSIVE FLOW OF SYSTEMS FROM WEST TO EAST TOWARDS THE
MIDDLE OF NEXT WEEK. THUS PRECIP CHC WILL BE ON THE INCREASE TOWARDS
THE FINAL FEW PERIODS OF THE CURRENT EXTENDED FORECAST.
BY TUE/WED OF NEXT WEEK...TEMPS COULD EASILY BE BACK INTO THE UPR
70S TO LOW 80S.
CONFIDENCE IN PRECIPITATION...LOW.
CONFIDENCE IN TEMPERATURES...HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* VARIABLE MVFR/IFR CIG SLOWLY IMPROVING AOA 1500 FT AROUND 17Z.
VFR/CLEARING BY MID AFTN.
* NORTH WIND INCREASING TO 20 TO 30 KT BY MID MORNING AND
CONTINUING THROUGH AFTN.
ALLSOPP/BMD
//DISCUSSION...UPDATED 12Z...
MAIN CONCERN THIS MORNING IS CIG TRENDS...THEN THIS AFTERNOON
FOCUS WILL BE ON STRONG GUSTY NNE WINDS. LOW PRESSURE WAS OVER
THE EASTERN GREAT LAKES WITH A COLD FRONT TRAILING WESTWARD INTO
NORTHERN IL. AT 11Z THE FRONT WAS FROM ABOUT IKK-VYS. BASED ON
NAM AND HRRR MODEL SOUNDINGS...CIGS SHOULD SLOWLY IMPROVE TO
AROUND 1000-1200 FT IN THE NEXT COUPLE HOURS. THIS SEEMS
REASONABLE WITH STRONGER WINDS MIXING COLDER AND SLIGHTLY DRIER
AIR DOWN FROM THE NORTH. ALSO SPOTTY LIGHT RAIN/DRIZZLE WILL BE
DIMINISHING/MOVING OUT AND THAT MAY ALSO HELP IMPROVE CIG AND VSBY
A BIT THIS MORNING. AS OF 11Z THE BACK EDGE OF THE MAIN BAND OF
RAIN ASSOCIATED WITH THE COLD FRONT WAS LINED UP FROM DKB-DPA-
MDW-GYY AND SINKING VERY SLOWLY S. THERE WERE SOME VSBY
RESTRICTIONS DOWN TO 2-3 MILES IN THIS BAND OF RAIN...BUT IT HAS
PUSHED SOUTH OF THE TERMINALS. FURTHER NORTH INTO SOUTHERN WI
THERE WERE SOME PATCHES OF LIGHT RAIN/DRIZZLE..BUT THIS WAS VERY
LIGHT. SHORT RANGE/HI RES MODELS SUGGEST THIS SPOTTY LIGHT RAIN
WILL BE DRYING UP AND MOVING SE OUT OF THE AREA BY MID TO LATE
MORNING. THEREFORE DONT EXPECT ANY SIGNIFICANT VSBY RESTRICTIONS
BELOW 5 OR 6 MILES THE REST OF THE MORNING. AS STRONG NORTH WINDS
CONTINUE TO PUSH COLDER DRIER AIR DOWN...EXPECT CLOUDS TO LIFT TO
1500 FT OR BETTER BY NOON AND BREAK UP THIS AFTERNOON WITH
CLEARING MID TO LATE AFTN.
NORTH WINDS HAVE PICKED UP AND WINDS WILL CONTINUE TO INCREASE TO
20 TO 30 KT BY MID MORNING. DIRECTION MAY VARY SOME FROM 350-030
BUT WILL BE PREDOMINANTLY JUST E OF N TODAY. PRESSURE GRADIENT
SLOWLY BEGINS TO RELAX LATE THIS AFTERNOON AND WINDS MAY DIMINISH
SLIGHTLY DURING THE LATE AFTN. ATMOSPHERE SHOULD BEGIN TO DECOUPLE
THIS EVENING AS PRESSURE GRADIENT CONTINUES TO RELAX.
OUTLOOK FOR FRIDAY IS VFR WITH LIGHT NORTHEAST WINDS.
ALLSOPP
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* LOW/MEDIUM CONFIDENCE IN CIG TRENDS THIS MORNING.
* MEDIUM CONFIDENCE IN TIMING OF CLEARING THIS AFTN.
* HIGH CONFIDENCE IN WIND FORECAST. DIRECTION MAY VARY FROM
350-030 BUT SHOULD STAY JUST E OF N.
ALLSOPP
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT AND SATURDAY...VFR. WX NIL.
SUNDAY AND MONDAY...VFR. CHC SHRA SLIGHT CHC TSRA.
TUESDAY AND WEDNESDAY...CHC TSRA.
ALLSOPP
&&
.MARINE...
147 AM CDT
EARLY THURSDAY MORNING AN ELONGATED AREA OF LOW PRESSURE WAS FROM
THE EASTERN GREAT LAKES BACK TO NORTHERN ILLINOIS...WHILE A STRONG
AREA OF HIGH PRESSURE WAS CENTERED OVER NORTHERN MANITOBA WITH A
RIDGE EXTENDING SOUTHWARD INTO THE NORTHERN PLAINS. AS THE TROF
SWINGS EAST AND THE RIDGE BUILDS INTO THE WESTERN GREAT LAKES
TODAY...GALE FORCE NORTH WINDS WILL DEVELOP OVER LAKE MICHIGAN.
THE GALES WILL DEVELOP OVER CENTRAL LAKE MICHIGAN EARLY THIS
MORNING AND SPREAD TO THE SOUTH END BY MID OR LATE MORNING. WINDS
WILL DIMINISH OVERNIGHT AS THE HIGH SETTLES OVER THE WESTERN GREAT
LAKES AND THE LOW MOVES UP THE EAST COAST. THE HIGH WILL THEN BE
NEARLY STATIONARY OVER THE GREAT LAKES THROUGH THE WEEKEND WITH
LIGHT EAST TO SOUTHEAST FLOW OVER THE LAKE. LOW PRESSURE WILL MOVE
FROM THE CENTRAL PLAINS TO THE UPPER MISSISSIPPI VALLEY MONDAY AND
TUESDAY WHICH WILL CAUSE WINDS TO BECOME SOUTHERLY OVER LAKE
MICHIGAN.
ALLSOPP
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-
LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ872-LMZ874-LMZ876-
LMZ878 UNTIL 9 PM THURSDAY.
GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870 UNTIL 3
PM THURSDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
648 AM CDT THU MAY 23 2013
.DISCUSSION...
240 AM CDT
TODAY...
FORECAST CHALLENGES FOR TODAY RESIDE WITH HIGH TEMPS...AND PRECIP
CHANCES THIS MORNING.
IR IMAGERY EARLY THIS MORNING SHOWS CONSIDERABLE CLOUD COVER
REMAINING ACROSS THE WESTERN GREAT LAKES...EXTENDING SOUTH THROUGH
THE MID-MISSISSIPPI VALLEY. ALONG THE WESTERN PERIPHERY OF THE CLOUD
COVER LIES THE LEADING EDGE OF THE STRONG SFC RIDGE...BEGINNING TO
PUSH INTO THE UPPER MIDWEST/NORTHERN PLAINS. MOISTURE HAS BEEN
CONSISTENTLY PEELING OFF TO THE NORTHEAST...NOTED IN THE STEADILY
LOWERING DEW POINTS. DEW POINTS ACROSS CENTRAL WISC HAVE ALREADY
FALLEN INTO THE UPR 40S...AND EXPECT THIS TREND TO EVENTUALLY ARRIVE
ACROSS NORTHERN IL/NORTHWEST IN. A BROAD SFC TROUGH WAS ANALYZED
ACROSS NORTHEAST IL STRETCHING INTO SOUTHCENTRAL LOWER MI. AS A
RESULT SFC WINDS ACROSS THE CWFA HAVE MAINLY BEEN FROM THE
WEST/SOUTHWEST...HOWEVER JUST NORTH OF THE CWFA INTO WISC WINDS HAVE
ALREADY SHIFTED TO THE NORTHWEST/NORTH. LOCATIONS ADJACENT TO LAKE
MICHIGAN WILL SEE WINDS FLOP OVER TO THE NORTHEAST THIS
MORNING...ALLOWING THE MUCH COOLER MARINE ENVIRONMENT TO READILY
FLOW ACROSS THE LAND.
REGIONAL RADAR EARLY THIS MORNING SHOWS AN AREA OF SHOWERS ACROSS
CENTRAL WISC...SLOWLY SLIDING SOUTHEAST. HI-RES GUIDANCE SUGGESTS
THIS CHANNEL OF PRECIP WILL EVENTUALLY ARRIVE ACROSS NORTHERN IL
JUST BEFORE DAYBREAK. AS A RESULT OF THE INCREASED CONFIDENCE IN
PRECIP...HAVE NUDGED THE 12-15Z TIMEFRAME TO LIKELY POPS FOR FAR
NORTHEAST IL.
DRY AIR CONTINUES TO POUR INTO THE REGION MID-MORNING...AND SHOULD
BRING AN END TO THE PRECIP FROM NORTHWEST TO SOUTHEAST ACROSS THE
CWFA BY EARLY THIS AFTERNOON. THE STEADY PUSH OF DRY AIR WILL ALSO
AID IN ERODING THE CLOUD COVER...AND BY LATE THIS AFTERNOON EXPECT
MOSTLY SUNNY SKIES TO DEVELOP. COLD AIR ADVECTION WILL DOMINATE THE
DAY...COUPLED PRECIP AND CLOUDS...EXPECT MUCH COOLER TEMPS FOR THIS
AFTERNOON. GUIDANCE HAS CONTINUED TO SUGGEST TEMPS WILL STRUGGLE TO
WARM BEYOND THE LOW 60S FOR THE FAR WESTERN CWFA...MEANWHILE FURTHER
EAST TEMPS WILL ONLY WARM A FEW DEGREES FROM THEIR STARTING POINT.
THIS WILL MOST LIKELY LEAD TO AREAS EAST OF I-39 ONLY WARMING INTO
THE MID/UPR 50S. LOCATIONS IMMEDIATELY ADJACENT TO LAKE MICHIGAN
COULD SEE TEMPS STRUGGLE TO WARM BEYOND 50 DEGREES.
CONFIDENCE IN PRECIP ENDING TIME...MEDIUM/HIGH.
CONFIDENCE IN TEMPERATURES...HIGH.
TONIGHT...
ANTI-CYCLONIC FLOW WILL CONTINUE TO BUILD OVERHEAD EARLY THIS
EVENING...AND ERODE ANY LINGERING CLOUDS BY MIDNIGHT. DEW POINTS AS
A RESULT WILL CONTINUE TO DRY...BOTTOMING OUT IN THE MID 30S IN MANY
LOCATIONS. THE COMBINATION OF NEAR CLOUDLESS SKIES...LIGHT NORTH TO
AT TIMES CALM WINDS...AND RECENT RAINFALL...WILL SET THE STAGE FOR
NOT ONLY STRONG RADIATIONAL COOLING BUT PATCHY FROST AWAY FROM LAKE
MICHIGAN. GUIDANCE CONTINUES TO PROG TEMPS FALLING OVERNIGHT INTO
THE MID/UPR 30S FOR AREAS WEST OF WAUKEGAN TO KANKAKEE. FAR SOUTHERN
PORTIONS OF THE CWFA SHOULD HAVE TEMPS HOLD ARND 40 DEGREES
OVERNIGHT...HOWEVER A FEW LOW-LYING AREAS COULD SEE SPOTTY FROST. AT
THIS POINT IT DOES NOT APPEAR TO BE A WIDESPREAD FROST SETUP...SO
WILL HOLD OFF ON ANY HEADLINES AT THIS POINT.
CONFIDENCE...HIGH.
FRIDAY...
SFC HIGH PRESSURE WILL DOMINATE THE REGION FOR THE END OF THE
WEEK...AND MORE THAN LIKELY ONLY ALLOW A FEW DIURNAL CLOUDS TO
DEVELOP. A LIGHT NORTHEAST FLOW OFF OF LAKE MICHIGAN WILL CONTINUE
TO KEEP ADJACENT AREAS MUCH COOLER IN THE MID/UPR 50S...MEANWHILE
INLAND LOCATIONS WILL BEGIN TO WARM INTO THE LOW/MID 60S.
WITH HIGH PRESSURE STILL IN CONTROL FRIDAY NIGHT...EXPECT ANOTHER
NIGHT OF STRONG RADIATIONAL COOLING. THE ONLY DIFFERENCE FOR FRI
NIGHT WILL BE THE RIDGE AXIS WILL HAVE SHIFTED EAST. THIS WILL ALLOW
THE LIGHT WINDS TO BEGIN TURNING SOUTHEASTERLY AFTER MIDNIGHT...AND
COULD SLOW THE RATE OF COOLING. HAVE MAINTAINED TEMPS IN THE LOW 40S
FOR MANY AREAS. COULD SEE A FEW OF THE TRADITIONAL COOL SPOTS DIP TO
THE UPR 30S EARLY SAT MORNING...HOWEVER AT THIS POINT NOT
ANTICIPATING FROST FORMATION.
CONFIDENCE IN TEMPERATURES...HIGH.
SATURDAY...
DISCREPANCIES BEGIN TO EMERGE AMONGST SOLUTIONS FOR SAT...WITH
RESPECT TO PLACEMENT/TIMING OF A MOIST BOUNDARY. GFS HAS CONTINUED
TO BE THE MORE PROGRESSIVE SOLUTION...BRINGING THIS CHANNEL OF
MOISTURE/PRECIP INTO THE REGION AND STRETCHES FROM THE NORTHERN
PLAINS SOUTHEAST THROUGH THE OHIO VALLEY. MEANWHILE THE EC HAS
MAINTAINED THE SFC RIDGE...AND SUPPRESSING THE MOIST CHANNEL TO THE
SOUTHWEST OF THE CWFA.
THE LARGEST WEATHER PLAYER IS THE DOWNSTREAM 500MB RIDGE LOCATED
ACROSS THE WESTERN ATLANTIC. THIS WILL ACT AS A BLOCK...SLOWING THE
DEPARTURE OF THE MID-LVL TROUGH ACROSS THE MID-ATLANTIC REGION. THEN
FURTHER UPSTREAM YET ANOTHER 500MB RIDGE WAS PROGGED TO ARRIVE
ACROSS THE CENTRAL CONUS...AND DOES SHOW SOME SIGNS OF
AMPLIFICATION. BASED ON THIS SETUP IT IS BECOMING MORE EVIDENT THAT
SAT COULD END UP BEING DRY...AND POSSIBLY EXTEND INTO SUN. AT THIS
POINT HAVE ONLY ADJUSTED POPS SAT MARGINALLY...TO SLIGHT CHANCE
WORDING.
SFC TEMPS WILL REMAIN UNSEASONABLY COOL IN THE LOW/MID 60S...WITH
AREAS ADJACENT TO LAKE MICHIGAN BEING EVEN COOLER THAN THIS. DESPITE
THE EXPECTED SOUTHEAST COMPONENT TO THE SFC WINDS...ENOUGH HEATING
COULD ALLOW A LAKE BREEZE TO FORM AND ALLOW WINDS TO BECOME MORE
EASTERLY FOR LOCATIONS ADJACENT TO LAKE MICHIGAN. THIS WILL MOST
LIKELY RESULT IN THOSE AREAS IMMEDIATELY NEXT TO THE LAKE REMAINING
IN THE 50S SAT AFTN.
CONFIDENCE...MEDIUM.
SUNDAY THROUGH WEDNESDAY...
FOR THE EXTENDED PERIODS GUIDANCE HAS CONTINUED TO DEMONSTRATE
MINIMAL CHANGES FROM PREVIOUS SOLUTIONS...HOWEVER OPERATIONAL
ECMWF/GFS CONTINUE TO DIFFER ON THE PLACEMENT/TIMING OF PRECIP. THE
ECMWF CONTINUES TO SUGGEST THE SFC RIDGE FROM LATE IN THE WEEK WILL
HOLD TOUGH AND KEEP NORTHERN IL/NORTHWEST IN DRY THRU THE WEEKEND
AND INTO EARLY NEXT WEEK. MEANWHILE THE GFS IS STILL MORE
PROGRESSIVE AND BRINGS THE BOUNDARY OVERHEAD AND BECOMES
QUASI-STATIONARY THRU THE FIRST HALF OF NEXT WEEK.
ENSEMBLES CONTINUE TO INDICATE THE WESTERN ATLANTIC MID-LVL RIDGE
WILL WEAKEN...ALLOWING THE 500MB TROUGH TO FINALLY EJECT EAST. IN
ADDITION THE UPSTREAM RIDGE WILL BEGIN TO FLATTEN...LEADING TO A
SOMEWHAT PROGRESSIVE FLOW OF SYSTEMS FROM WEST TO EAST TOWARDS THE
MIDDLE OF NEXT WEEK. THUS PRECIP CHC WILL BE ON THE INCREASE TOWARDS
THE FINAL FEW PERIODS OF THE CURRENT EXTENDED FORECAST.
BY TUE/WED OF NEXT WEEK...TEMPS COULD EASILY BE BACK INTO THE UPR
70S TO LOW 80S.
CONFIDENCE IN PRECIPITATION...LOW.
CONFIDENCE IN TEMPERATURES...HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* IFR CIG SLOWLY IMPROVING TO MVFR AROUND 12-14Z...AND AOA 1500 FT
BY NOON. VFR/CLEARING BY MID AFTN.
* NORTH WIND INCREASING TO 20 TO 30 KT BY MID MORNING AND
CONTINUING THROUGH AFTN.
ALLSOPP
//DISCUSSION...UPDATED 12Z...
MAIN CONCERN THIS MORNING IS CIG TRENDS...THEN THIS AFTERNOON
FOCUS WILL BE ON STRONG GUSTY NNE WINDS. LOW PRESSURE WAS OVER
THE EASTERN GREAT LAKES WITH A COLD FRONT TRAILING WESTWARD INTO
NORTHERN IL. AT 11Z THE FRONT WAS FROM ABOUT IKK-VYS. BASED ON
NAM AND HRRR MODEL SOUNDINGS...CIGS SHOULD SLOWLY IMPROVE TO
AROUND 1000-1200 FT IN THE NEXT COUPLE HOURS. THIS SEEMS
REASONABLE WITH STRONGER WINDS MIXING COLDER AND SLIGHTLY DRIER
AIR DOWN FROM THE NORTH. ALSO SPOTTY LIGHT RAIN/DRIZZLE WILL BE
DIMINISHING/MOVING OUT AND THAT MAY ALSO HELP IMPROVE CIG AND VSBY
A BIT THIS MORNING. AS OF 11Z THE BACK EDGE OF THE MAIN BAND OF
RAIN ASSOCIATED WITH THE COLD FRONT WAS LINED UP FROM DKB-DPA-
MDW-GYY AND SINKING VERY SLOWLY S. THERE WERE SOME VSBY
RESTRICTIONS DOWN TO 2-3 MILES IN THIS BAND OF RAIN...BUT IT HAS
PUSHED SOUTH OF THE TERMINALS. FURTHER NORTH INTO SOUTHERN WI
THERE WERE SOME PATCHES OF LIGHT RAIN/DRIZZLE..BUT THIS WAS VERY
LIGHT. SHORT RANGE/HI RES MODELS SUGGEST THIS SPOTTY LIGHT RAIN
WILL BE DRYING UP AND MOVING SE OUT OF THE AREA BY MID TO LATE
MORNING. THEREFORE DONT EXPECT ANY SIGNIFICANT VSBY RESTRICTIONS
BELOW 5 OR 6 MILES THE REST OF THE MORNING. AS STRONG NORTH WINDS
CONTINUE TO PUSH COLDER DRIER AIR DOWN...EXPECT CLOUDS TO LIFT TO
1500 FT OR BETTER BY NOON AND BREAK UP THIS AFTERNOON WITH
CLEARING MID TO LATE AFTN.
NORTH WINDS HAVE PICKED UP AND WINDS WILL CONTINUE TO INCREASE TO
20 TO 30 KT BY MID MORNING. DIRECTION MAY VARY SOME FROM 350-030
BUT WILL BE PREDOMINANTLY JUST E OF N TODAY. PRESSURE GRADIENT
SLOWLY BEGINS TO RELAX LATE THIS AFTERNOON AND WINDS MAY DIMINISH
SLIGHTLY DURING THE LATE AFTN. ATMOSPHERE SHOULD BEGIN TO DECOUPLE
THIS EVENING AS PRESSURE GRADIENT CONTINUES TO RELAX.
OUTLOOK FOR FRIDAY IS VFR WITH LIGHT NORTHEAST WINDS.
ALLSOPP
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* MEDIUM CONFIDENCE IN CIG TRENDS THIS MORNING.
* MEDIUM CONFIDENCE IN TIMING OF CLEARING THIS AFTN.
* HIGH CONFIDENCE IN WIND FORECAST. DIRECTION MAY VARY FROM
350-030 BUT SHOULD STAY JUST E OF N.
ALLSOPP
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT AND SATURDAY...VFR. WX NIL.
SUNDAY AND MONDAY...VFR. CHC SHRA SLIGHT CHC TSRA.
TUESDAY AND WEDNESDAY...CHC TSRA.
ALLSOPP
&&
.MARINE...
147 AM CDT
EARLY THURSDAY MORNING AN ELONGATED AREA OF LOW PRESSURE WAS FROM
THE EASTERN GREAT LAKES BACK TO NORTHERN ILLINOIS...WHILE A STRONG
AREA OF HIGH PRESSURE WAS CENTERED OVER NORTHERN MANITOBA WITH A
RIDGE EXTENDING SOUTHWARD INTO THE NORTHERN PLAINS. AS THE TROF
SWINGS EAST AND THE RIDGE BUILDS INTO THE WESTERN GREAT LAKES
TODAY...GALE FORCE NORTH WINDS WILL DEVELOP OVER LAKE MICHIGAN.
THE GALES WILL DEVELOP OVER CENTRAL LAKE MICHIGAN EARLY THIS
MORNING AND SPREAD TO THE SOUTH END BY MID OR LATE MORNING. WINDS
WILL DIMINISH OVERNIGHT AS THE HIGH SETTLES OVER THE WESTERN GREAT
LAKES AND THE LOW MOVES UP THE EAST COAST. THE HIGH WILL THEN BE
NEARLY STATIONARY OVER THE GREAT LAKES THROUGH THE WEEKEND WITH
LIGHT EAST TO SOUTHEAST FLOW OVER THE LAKE. LOW PRESSURE WILL MOVE
FROM THE CENTRAL PLAINS TO THE UPPER MISSISSIPPI VALLEY MONDAY AND
TUESDAY WHICH WILL CAUSE WINDS TO BECOME SOUTHERLY OVER LAKE
MICHIGAN.
ALLSOPP
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-
LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ872-LMZ874-LMZ876-
LMZ878 UNTIL 9 PM THURSDAY.
GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ868-LMZ870 UNTIL 3
PM THURSDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
355 PM EDT THU MAY 23 2013
.DISCUSSION...
TONIGHT...
H100-H70 ANTICYCLONE OVER THE N CNTRL GOMEX WILL GENERATE A DEEP NW
FLOW ACRS CENTRAL FL OVERNIGHT. LATEST RAP ANALYSIS SHOWS LIMITED
INSTABILITY ACRS CENTRAL FL...COMMON IN SUCH A FLOW REGIME. WEAK LOW
LVL PGRAD ALLOWED THE EAST COAST SEABREEZE TO DVLP BY MID
AFTN...WHICH WILL PUSH STEADILY INLAND THROUGH SUNSET. ISOLD
SHRAS/TSRAS ALONG AND N OF THE I-4 CORRIDOR SHOULD DISSIPATE BY
SUNSET WITH THE LOSS OF DAYTIME HEATING.
WEAK FRONTAL BNDRY WILL PUSH INTO THE FL STRAITS...ALLOWING A LIGHT
W/NW BREEZE TO PREVAIL OVER LAND OVERNIGHT. DEEP LYR DRY AIR
ADVECTION WILL ALLOW SKIES TO BCM MCLR OVERNIGHT...UPSTREAM SFC
DEWPOINTS OVER N FL SUGGEST MIN TEMPS IN THE M/U60S...GENERALLY
WITHIN A DEG OR TWO OF CLIMO AVG.
FRI-FRI NIGHT...
CONTINENTAL RIDGE OVER THE CENTRAL/NRN PLAINS WILL BUILD INTO THE
DEEP SOUTH...RESULTING IN A STEADY NW TO NE BREEZE THRU THE H100-H70
LYR THAT WILL BRING OVERALL DRY WX TO E CNTRL FL. LATE SEASON COOL
FRONT WILL BRING LIMITED MOISTURE TO THE CENTRAL PENINSULA...WHILE
LATEST RAP ANALYSIS INDICATES LIMITED POTENTIAL FOR MID LVL
VORTICITY ADVECTION OR UPR LVL EVACUATION.
PRECIP CHANCES WILL BE LIMITED TO AREAS S OF THE I-4 CORRIDOR...BUT
WITH LIMITED MOISTURE AND INSTABILITY TO WORK WITH...ANTICIPATE AFTN
COVERAGE AOB 20PCT...SHIFTING OFFSHORE AFT SUNSET. W/NW FLOW WILL
PREVENT SEA BREEZE FORMATION N OF THE CAPE...MAYBE LATE DAY
DEVELOPMENT ALONG THE TREASURE COAST. NEAR FULL SUN WILL ALLOW TEMPS
TO WARM TO THE U80S ALONG THE COAST...L90S INLAND. WEAK ONSHORE FLOW
WILL DVLP OVERNIGHT AS THE RIDGE AXIS DRIFTS EWD...KEEPING MIN TEMPS
SLIGHTLY ABV AVG...M/U60S INTERIOR AND U60S/L70S ALONG THE COAST.
SAT-TUE...(PREV DISC)
IT WILL BE A WARM AND DRY MEMORIAL DAY WEEKEND ACROSS THE AREA AS
NORTH-NORTHWEST FLOW ALOFT BEHIND THE TROUGH USHERS IN DRY AIR THAT
WILL STAY IN PLACE INTO EARLY NEXT WEEK.
AT THE SURFACE...STOUT ONSHORE FLOW WILL DEVELOP ON SATURDAY AS THE
SURFACE HIGH OVER THE GREAT LAKES BUILDS TO THE SOUTHEAST AND OFF
THE CAROLINA COAST WITH ITS AXIS ACROSS NORTH FLORIDA INTO NEXT WEEK.
FLOW WILL BE STRONG ENOUGH AND DEEP ENOUGH THAT A FEW ATLANTIC
SHOWERS REACHING THE COAST CAN`T BE RULED OUT...ESPECIALLY ACROSS
THE TREASURE COAST WHERE MOISTURE WILL BE HIGHER. HOWEVER THE
PROBABILITY THIS FAR OUT REMAINS TO LOW TO MENTION.
ONSHORE FLOW WILL KEEP HIGH TEMPERATURES A FEW DEGREES COOLER IN THE
LOW-MID 80S ALONG THE COAST AND MID-UPPER 80S INLAND. POST FRONTAL
DRY AIR AND MOSTLY CLEAR SKIES SHOULD ALLOW TEMPERATURES TO DROP
INTO THE LOW TO MID 60S ACROSS THE INTERIOR SAT-SUN NIGHTS BEFORE
THE GRADUALLY MOISTENING IN ONSHORE FLOW BRINGS LOWS UP IN THE
MID-UPPER 60S. COASTAL TEMPS REMAIN WARM AND MUGGY IN THE LOW-MID
70S. LOCATIONS WHERE WINDS DROP OVERNIGHT OR WEAK DRAINAGE FLOW
DEVELOPS MAY DROP SEVERAL MORE DEGREES INTO THE MID 60S.
&&
.AVIATION...
VFR ALL SITES UNLESS OTHERWISE NOTED. BTWN 23/20Z-23/24Z...ISOLD
MVFR SHRAS/IFR TSRAS E OF KDAB-KOBE. BTWN 24/08Z-24/12Z...LCL IFR
CIGS/VSBYS IN BR.
&&
.MARINE...
TONIGHT...LIGHT TO GENTLE E/SE BREEZE NEARSHORE THRU SUNSET DUE TO
THE INLAND MOVING EAST COAST SEA BREEZE...WRLY BREEZE OFFSHORE IN
THE WAKE OF A WEAK FRONTAL BNDRY PUSHING INTO THE FL STRAITS.
SFC/BNDRY LYR WINDS LIGHT AND VARIABLE BCMG W/SW OVERNIGHT AS HI
PRES OVER THE CENTRAL GOMEX IS ABSORBED BY A LARGER CONTINENTAL
RIDGE BUILDING OUT OF THE CENTRAL/NRN PLAINS. SEAS MAINLY 2-3FT...
UP TO 4FT IN THE GULF STREAM N OF CAPE CANAVERAL.
FRI-FRI NIGHT...LIGHT TO GENTLE NW WINDS BCMG N/NE THRU THE DAY AS
THE CONTINENTAL RIDGE BUILDS INTO THE DEEP SOUTH. LCL PGRAD WILL
TIGHTEN LATE FRI NIGHT AS THE RIDGE BUILDS INTO THE REGION...WINDS
WILL RESPOND BY FRESHENING TO 10-15KTS NEARSHORE AND ARND 15KTS
OFFSHORE. SEAS 2-3FT NEARSHORE AND 3-4FT OFFSHORE THRU LATE FRI
NIGHT...BUILDING TO 3-5FT N OF SEBASTIAN INLET AND 2-4FT S OF THE
INLET BY DAYBREAK SAT.
MEMORIAL DAY WEEKEND...(PREV DISC)
MODELS HAVE BACKED OFF SLIGHTLY ON THE MAGNITUDE OF THE NORTHEAST
WINDS SURGE SAT MORNING...THOUGH STILL EXPECT SPEEDS AROUND 15-20KTS
THROUGH LATE SAT NIGHT AS HIGH PRESSURE BUILDS IN BEHIND THE FRONTAL
BOUNDARY. WINDS WILL DIMINISH SLIGHTLY INTO THE OVERNIGHT HOURS INTO
SUNDAY AS THEY VEER TO THE EAST AROUND 15KTS. LIGHTEST WINDS WILL BE
NORTH OF CAPE CANAVERAL INTO MONDAY AT 10-15KTS WHICH WILL BE
CLOSEST TO THE RIDGE AXIS.
WIND SURGE WILL BRING SEAS TO AROUND 6FT OFFSHORE SAT
AFTERNOON/NIGHT WITH THE OFFSHORE FLOW KEEPING HEIGHTS 4-5FT THROUGH
THE REMAINDER OF THE HOLIDAY WEEKEND.
&&
.FIRE WEATHER...
NWRLY TRANSPORT FLOW WILL GENERATE MODERATE DRY AIR ADVECTION THRU
THE END OF THE WEEK...RESULTING IN LITTLE IF ANY MEASURABLE PRECIP.
RH VALUES ALONG AND N OF THE I-4 CORRIDOR WILL FALL BLO 35PCT FOR A
FEW HRS EACH AFTN...BUT SFC PGRAD SHOULD BE LOOSE ENOUGH TO ALLOW
THE EAST COAST SEA BREEZE TO DEVELOP...KEEPING COASTAL AFTN RH
VALUES NEAR 50PCT.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 70 88 68 80 / 10 10 0 0
MCO 69 92 69 86 / 10 10 0 0
MLB 71 88 72 81 / 10 20 10 0
VRB 71 88 72 82 / 10 20 10 0
LEE 69 91 66 86 / 10 10 0 0
SFB 69 91 69 85 / 10 10 0 0
ORL 70 92 69 86 / 10 10 0 0
FPR 71 89 72 82 / 10 20 10 10
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM/AVIATION...BRAGAW
LONG TERM/IMPACT WX...PENDERGRAST
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
345 PM EDT THU MAY 23 2013
.SYNOPSIS...
19Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS A RATHER CHAOTIC UPPER
LEVEL PATTERN IN PLACE ACROSS THE CONUS. PATTERN IS DOMINATED BY
THREE LONGWAVE FEATURES. LOOKING FAR UPSTREAM WE FIND A LARGE AND
VIGOROUS UPPER LEVEL LOW SPINNING OVER THE PACIFIC NORTHWEST. MAIN
FLOW AROUND THE SOUTHERN PERIPHERY OF THIS CIRCULATION EMERGES
THROUGH THE FOUR-CORNERS REGION AND THEN RIDGES UP OVER THE CENTRAL
PLAINS. THIS FLOW THEN QUICKLY DIVES BACK TO THE SOUTHEAST AND
MERGES WITH AN IMPRESSIVE LONGWAVE TROUGH PIVOTING THROUGH MUCH OF
EASTERN CANADA AND THE EASTERN CONUS. OUR FORECAST AREA RESIDES NEAR
THE SOUTHERN PERIPHERY/BASE OF THIS EASTERN TROUGH. WV IMAGERY
CLEARLY DEFINES A WEAK SHORTWAVE EMBEDDED WITHIN THE FLOW WITHIN THE
BASE OF THE LONGWAVE TROUGH WHICH IS PIVOTING THROUGH THE REGION
THIS AFTERNOON...AND WILL BE OFF TO OUR EAST BY TONIGHT.
MID/UPPER LEVEL DRY AIR IS EXPANDING ACROSS THE REGION WITH WEAK NVA
AND LARGE SCALE SUBSIDENCE IN THE WAKE OF THIS DEPARTING SHORTWAVE.
AT THE SURFACE...A WEAK PRESSURE GRADIENT IS RESULTING IN MAINLY
SEA-BREEZE DOMINATED FLOW LATE TODAY. THE WEST COAST SEA-BREEZE IS
QUICKLY BEGINNING TO TRANSLATE INLAND CLEARING THE DIURNAL CUMULUS
FIELD AWAY FROM THE BEACHES. MAY STILL SEE A FEW INTERIOR ISOLATED
CONVECTIVE CELLS INTO THE EARLY EVENING...HOWEVER COVERAGE LOOKS TO
BE SIGNIFICANTLY LESS THAN WHAT WAS EXPERIENCED THE PAST COUPLE OF
DAY.
&&
.SHORT TERM (TONIGHT THROUGH SATURDAY NIGHT)...
TONIGHT...
LARGE SCALE SUBSIDENCE PATTERN SUGGESTS ANY LINGERING STORMS BY
MID-EVENING WILL BE OVER TOWARD THE I-95 CORRIDOR WHICH SHOULD SET
UP A MAINLY DRY...QUIET AND SEASONABLE OVERNIGHT PERIOD FOR OUR
ZONES. TEMPERATURES WILL GENERALLY DROP TO THE MID 60S TO LOWER 70S
BY SUNRISE ON FRIDAY...WITH THE NORMALLY COLDER INLAND SPOTS DOWN
INTO THE LOWER 60S.
FRIDAY/FRIDAY NIGHT...
EASTERN CONUS UPPER LEVEL TROUGH IS FORECAST TO SHARPEN AS ITS AXIS
REACHES THE ATLANTIC COAST DURING FRIDAY. SURGE OF ENERGY ROUNDING
THE BASE OF THIS TROUGH DURING THIS TIME WILL PASS TO OUR
NORTH...HOWEVER IT WILL ACT TO PROPEL A LATE SEASON TROUGH/FRONT
DOWN AND ACROSS THE FL PENINSULA. SIGNIFICANTLY DRIER AIR WILL BE
ARRIVING BEHIND THIS FRONT...ESPECIALLY ABOVE THE SURFACE WHICH
SHOULD SUPPRESS MUCH IF NOT ALL OF THE DIURNAL CONVECTION FROM THE
TAMPA BAY AREA NORTHWARD ALONG THE NATURE COAST. SOME LINGERING
MOISTURE AND SEA-BREEZE COLLISION WITHIN A WEAK GRADIENT OVER THE
SOUTHERN ZONES SHOULD BE ENOUGH FOR A FEW LATE DAY STORMS...MAINLY
INLAND FROM THE I-75 CORRIDOR. STRONG CONTINENTAL HIGH PRESSURE
BEGINS TO BUILD OVER THE PENINSULA DURING FRIDAY NIGHT WITH A
TIGHTENING PRESSURE GRADIENT AND DEVELOPING NE FLOW. DRIER AIR WILL
CONTINUE TO ADVECT INTO THE AREA...EVEN AT THE SURFACE AND LEAD TO A
NOTICEABLY COOLER OVERNIGHT PERIOD. IN FACT...A FEW SPOTS UP TOWARD
CITRUS/LEVY COUNTY MAY FIND THEMSELVES BACK INTO THE 50S FOR A FEW
HOURS TOWARD DAWN ON SATURDAY.
SATURDAY/SATURDAY NIGHT...
ON THE BACKSIDE OF THE DEPARTING UPPER TROUGH...AN UNSEASONABLY DRY
MID-LEVEL AIRMASS WILL DESCEND OVER THE REGION FOR SATURDAY AND
SATURDAY NIGHT. CROSS-SECTION AND TIME-HEIGHT ANALYSIS FROM THE GFS
AND NAM BOTH SHOW AVERAGE RELATIVE HUMIDITY THROUGH THE 850-400MB
LAYER AT UNDER 10%...THAT IS DRY! IN ADDITION...THETA-E VALUES
AROUND 700MB ARE FORECAST TO DROP BELOW 315K ALMOST REGION-WIDE BY
SATURDAY AFTERNOON. THIS COMBINATION ALONG WITH THE SYNOPTIC FLOW
DISRUPTING THE SEA-BREEZE FORMATION WILL LEAD TO LITTLE IF ANY
CHANCES FOR DIURNAL CONVECTION. WILL KEEP THE FORECAST DRY FOR THE
FIRST HALF OF THE WEEKEND UNDER PLENTY OF SUNSHINE AND SEASONABLE
TEMPERATURES. THE DRY CONDITIONS WILL LEAD TO ANOTHER BELOW AVERAGE
NIGHT IN TERMS OF TEMPERATURES...WITH WIDESPREAD LOWER 60S AWAY FROM
THE COAST BY DAWN ON SUNDAY. ONCE AGAIN COLDER SPOTS ACROSS THE
NATURE COAST ARE FORECAST TO DROP INTO THE MID/UPPER 50S.
&&
.LONG TERM (SUNDAY THROUGH NEXT WEDNESDAY)...
MODEL SOLUTIONS REMAIN IN GOOD AGREEMENT SHOWING HIGH PRESSURE RIDGE
AXIS REMAINING NORTH OF THE FORECAST AREA...KEEPING AN EASTERLY
BOUNDARY LAYER FLOW IN PLACE. MOISTURE WILL REMAIN LIMITED THROUGH
MONDAY NIGHT...WITH RAIN FREE CONDITIONS EXPECTED. BOUNDARY LAYER
MOISTURE WILL INCREASE SLIGHTLY DURING THE MID WEEK TIME FRAME...SO
WILL CARRY SLIGHT CHANCE POPS FOR PORTIONS OF THE AREA TUESDAY
THROUGH THURSDAY FOR AFTERNOON/EARLY EVENING SHOWERS AND
THUNDERSTORMS.
&&
.AVIATION...
PREVAILING VFR WITH FEW-SCT CLOUDS...ISOLD TSRA EAST OF THE
TERMINALS THROUGH EARLY EVENING. LIMITED BR MAY BE POSSIBLE AT LAL
AND PGD. WESTERLY WINDS BECOME LIGHT AND VARIABLE OVERNIGHT THEN
NORTHWESTERLY DURING THE DAY.
&&
.MARINE...
WEAK HIGH PRESSURE ACROSS THE EASTERN GULF SLIDES OFF TONIGHT AS A
DRY FRONT MOVES SOUTHWARD FRIDAY AND INTO SOUTH FLORIDA. HIGH
PRESSURE BUILDS INTO THE GULF REGION SATURDAY THEN MOVES EAST...AS
IT CONTINUES TO DOMINATE THE EAST GULF WATERS. THE BUILDING HIGH
PRESSURE RESULTS IN A TIGHTENING PRESSURE GRADIENT WITH GUSTY EAST
AND NORTHEAST WINDS POSSIBLY REACHING CAUTIONARY OR LOW END ADVISORY
CRITERIA AT TIMES.
&&
.FIRE WEATHER..
A LATE SEASON FRONT WILL DROP SOUTH ACROSS THE REGION FRIDAY AND
FRIDAY NIGHT ALLOWING A MUCH DRIER AIRMASS TO FILTER IN FROM THE
NORTH FOR THE UPCOMING WEEKEND. RELATIVE HUMIDITY VALUES ARE
FORECAST TO DROP BELOW CRITICAL VALUES FOR A PERIOD FRIDAY AFTERNOON
AWAY FROM THE COAST WITH THE LOWEST VALUES AND LONGEST DURATIONS
FROM THE I-4 CORRIDOR AND NORTHWARD. ANOTHER DAY WITH A PERIOD OF
CRITICALLY LOW RELATIVE HUMIDITY IS ANTICIPATED FOR SATURDAY. A
NORTHEAST WIND WILL HELP BRING THESE LOW RELATIVE HUMIDITY VALUES
BACK CLOSER TO THE COAST.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 73 91 69 87 / 0 0 0 0
FMY 72 92 70 91 / 10 10 10 10
GIF 71 93 67 90 / 10 10 10 0
SRQ 71 90 70 90 / 0 0 0 0
BKV 65 91 62 87 / 0 10 10 0
SPG 75 90 73 87 / 0 0 0 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/FIRE WX...MROCZKA
AVIATION/MARINE/DECISION SUPPORT...RUDE
LONG TERM...JELSEMA
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
523 PM CDT THU MAY 23 2013
.SHORT TERM...THROUGH MONDAY
ISSUED AT 204 PM CDT THU MAY 23 2013
23.12Z RAOBS SHOW GOOD 925-850MB COLD ADVECTION ACROSS THE WRN GREAT
LAKES THIS MORNING IN MODERATE NORTHEAST FLOW. FRONTAL SLOPE OVER
THE STATE IS SOMETHING THAT WILL COME INTO PLAY FOR UPCOMING
FORECAST AND HOW FAR IT SLIDES SOUTHWEST. AT 12Z KINL-KABR HAD A 7C
TEMPERATURE DIFFERENCE AT 850MB /12C AT 925MB/. A MASSIVE DRYING
ACROSS MN OCCURRED OVERNIGHT WITH PRECIPITATELY WATER VALUES
PLUMMETING FROM 0.90 TO 0.32 INCHES...OR 136 TO 48 PERCENT NORMAL.
THE SURFACE RIDGE NOSING IN IS QUITE DRY WITH PRECIPITABLE WATER
VALUES IN THE 30 PERCENT RANGE ACROSS SRN CANADA. THIS GAVE WAY TO A
SUNNY BUT COOL DAY TODAY. A HIGHER AMPLITUDE RIDGE AXIS IS
ANCHORED IN THE DAKOTAS AND SOUTH...WHILE A DEEPER CYCLONE HAS NOW
SHIFTED ONSHORE INTO THE NWRN U.S. NUMEROUS SPOKES OF ENERGY ARE
CIRCULATING AROUND THAT LOW...ONE OF WHICH IS QUITE STRONG OVER
NEVADA WITH RAP ANALYSIS SHOWING A TROPOPAUSE FOLD TO NEAR
500MB...ON THE POLEWARD SIDE OF A MEASURED 100KT 250MB JET CORE
NOSE. THIS IS DRIVING HEIGHT FALLS ACROSS MT/ID/UT. SURFACE DEW
POINTS OF MEANING FOR CONVECTION ARE LOCATED IN OKLAHOMA...SOON TO
RETURN NORTHWARD.
FORECAST IS ON TRACK FOR CALMING WINDS TONIGHT AND CLEAR SKIES.
WIDESPREAD FROST SHOULD OCCUR WITH LOWER 30S FORECAST ACROSS NWRN
WI. WITH LOWER DEW POINTS OVER NWRN WI COUNTIES CURRENTLY...HAVE
DECIDED TO JUST ADD ALL OF THOSE COUNTIES INTO THE FROST ADVISORY.
BIG PICTURE DURING THIS PERIOD IS FALLING HEIGHTS AND PRESSURE IN
THE FRONT RANGE WITH SOUTHERLY FLOW INCREASING AND A RETURN OF
MOISTURE TO NEB/SD FRIDAY NIGHT. THIS WILL PLACE THE LOW-LEVEL
THERMAL BOUNDARY ACROSS THE FORECAST AREA FROM 850-925MB...SLIGHTLY
DISPLACED SWWRD...FROM KABR-KMLI. THE CONSENSUS NCEP MODELS AT
23.12Z REMAIN CONSISTENT WITH THEIR PREVIOUS RUNS ON THE FRONTAL
BOUNDARY BECOMING ACTIVE IN THE DAKOTAS/NEB FRIDAY EVENING AND
SHIFTING EAST INTO MN/IA OVERNIGHT. THE 23.00Z ECMWF/UKMET
SOLUTIONS DO AS WELL...HOWEVER THEY REMAIN FURTHER WEST.
THE 300/305K SURFACE IN THE NCEP SOLUTIONS REMAINS CONSISTENT WITH
AN 8G/KG MOISTURE SURGE ISENTROPICALLY LIFTING AND CONVERGING INTO
CENTRAL AND ERN MN FRIDAY OVERNIGHT WITH A FETCH OF ABOUT 500 J/KG
OF MUCAPE FEEDING IT. THE NAM SEEMS TO BE THE MOST AGRESSIVE. NOT
OVERLY IMPRESSIVE FOR SEVERE WEATHER...BUT RATHER THERE IS ENOUGH
FORCING TO GENERATE RA/TSRA SWWRD OF MSP. THE ECMWF SOLUTIONS
SUGGEST MORE OF A FOCUS IN SRN/SWRN MN. THE MAIN QUESTION IS HOW
FAR EAST DOES THIS CONVECTIVE COMPLEX TRACK FRIDAY NIGHT AND HOW FAR
EAST DOES THE FRONTAL BOUNDARY LIFT. HAVE INCREASED RAIN CHANCES
FURTHER EAST FOR FRIDAY NIGHT AND SATURDAY...HOWEVER WITH THE
VERIFICATION RECORD OF THE ECMWF...THERE IS STILL A CHANCE THE
EASTERN AREAS WILL BE DRY. CONFIDENCE IS LOW ON THE EXACT
LOCATION OF THE WEATHER...BUT HIGHER THAT IT WILL BE AN ACTIVE
FRONTAL ZONE WITH SHRA/ISO TSRA.
THIS QUESTION REMAINS THROUGH MONDAY...HOW FAR EAST WILL THE
FRONTAL BAND BE LOCATED. THE FRONT WILL LIKELY REMAIN ACTIVE WITH
SHOWERS/STORMS AND CLOUDS...AND HIGHS QUITE A BIT COOLER THANOUTSIDE
THE BAND. OVERALL...HAVE INCREASED RAIN CHANCES IN THE WRN/SRN
FORECAST AREA AND TRIED TO REMAIN NEARLY DRY IN THE EAST. SEEMS
LIKE IT WILL BE A CLOUDY WEEKEND...AND THUS HAVE LOWERED HIGHS
SUNDAY AND MONDAY AS WELL. SEVERE WEATHER THREATS ARE MOST
POSSIBLE IN SWRN MN CLOSER TO THE CAPE POOL...AND MONDAY LOOKS
MOST FAVORABLE SHOULD THE INSTABILITY INCREASE AS THE WARM FRONT
MOVES TOWARD MN. HOWEVER...ACTIVITY ALONG THAT FRONT THIS WEEKEND
MAY HAVE MUCH TO DO WITH HOW THE ENVIRONMENT/FRONT EVOLVES MONDAY.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 241 PM CDT THU MAY 23 2013
IT CONTINUES TO LOOK LIKE WE/LL UNFORTUNATELY NEED TO KEEP A
PROLONGED PERIOD OF CHANCE POPS IN THE FORECAST THROUGH THE WEEK
AS THE BAROCLINIC ZONE LINGERS IN THE AREA... WITH ELEVATED
INSTABILITY AND PERSISTENT WARM ADVECTION WORK TO GENERATE
SCATTERED SHRA/TSRA. THERE WILL UNDOUBTEDLY BE SOME DRY PERIODS...
WITH PCPN FOCUSED WHEN INDIVIDUAL SHORTWAVES RIPPLE SOUTHEAST
THROUGH THE UPPER FLOW... BUT AT THIS POINT IT IS IMPOSSIBLE TO
TRY AND PIN POINT WHEN SUCH DRY PERIODS MIGHT OCCUR. THE 12Z ECMWF
HAS COME AROUND MORE IN LINE WITH THE GFS IN KEEPING THINGS MORE
ACTIVE IN OUR AREA THROUGHOUT THE TIME PERIOD... ALTHOUGH BOTH
SUGGEST WE SHOULD FINALLY BRING THE UPPER TROUGH EAST TOWARD THE
REGION BY THE END OF THE WEEK. DEPENDING ON HOW THAT UNFOLDS... WE
COULD HAVE A POSSIBILITY FOR FOCUSED CONVECTION AND POSSIBLE
SEVERE WEATHER DURING THE THURSDAY-FRIDAY TIME FRAME. BUT... UNTIL
THAT POINT THE MAIN ISSUES WOULD LIKELY BE LOCALLY HEAVY RAIN AND
PERHAPS SOME HAIL. IN GENERAL... TEMPERATURES WILL WARM THROUGH
THE WEEK AS THE BONAFIDE WARM SECTOR SLOWLY LIFTS NORTH INTO THE
AREA.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 459 PM CDT THU MAY 23 2013
VFR DURING THE PERIOD. INCREASING HIGH CLOUDS FROM THE WEST DURING
THE DAY FRIDAY. CHANCE OF SHRA LIMITED TO FAR WESTERN SITES.
INTRODUCED VCSH FOR NOW. LIGHT NORTHEAST TO EAST WINDS BECOMING
SOUTHEAST OVERNIGHT AND INCREASING ON FRIDAY. GUSTY AT MN SITES BY
MIDDAY.
KMSP...
VFR THROUGH PERIOD. NEXT CHANCE OF SHOWERS MOVES IN LATER FRIDAY
NIGHT. LIGHT NORTHEAST TO EAST WIND BECOMING SOUTHEAST FRIDAY AND
A BIT GUSTY BY MIDDAY.
/OUTLOOK FOR KMSP/
FRIDAY NIGHT...VFR. CHANCE OF SHOWERS. SOUTHEAST WIND 5 TO 15 KT.
SATURDAY...BRIEF MVFR CEILINGS POSSIBLE WITH A CHANCE OF
SHRA/TSRA. SOUTHEAST WIND 10 TO 20 KT.
SATURDAY NIGHT...MVFR CEILINGS AND VISIBILITIES POSSIBLE WITH A
CHANCE OF SHRA/TSRA. SOUTHEAST WIND 10 TO 20 KT.
SUNDAY...MVFR CEILINGS AND VISIBILITIES POSSIBLE WITH A CHANCE OF
SHRA/TSRA...BRIEF IFR CONDITIONS POSSIBLE. SOUTHEAST WIND 10 TO 20
KT.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 7 AM CDT FRIDAY FOR
MNZ045-052-053-063.
WI...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 7 AM CDT FRIDAY FOR
WIZ014>016-023>028.
&&
$$
SHORT TERM...BAUMGARDT/ARX
LONG TERM...
AVIATION...DE
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
246 PM CDT THU MAY 23 2013
.SHORT TERM...THROUGH MONDAY
ISSUED AT 204 PM CDT THU MAY 23 2013
23.12Z RAOBS SHOW GOOD 925-850MB COLD ADVECTION ACROSS THE WRN GREAT
LAKES THIS MORNING IN MODERATE NORTHEAST FLOW. FRONTAL SLOPE OVER
THE STATE IS SOMETHING THAT WILL COME INTO PLAY FOR UPCOMING
FORECAST AND HOW FAR IT SLIDES SOUTHWEST. AT 12Z KINL-KABR HAD A 7C
TEMPERATURE DIFFERENCE AT 850MB /12C AT 925MB/. A MASSIVE DRYING
ACROSS MN OCCURRED OVERNIGHT WITH PRECIPITATELY WATER VALUES
PLUMMETING FROM 0.90 TO 0.32 INCHES...OR 136 TO 48 PERCENT NORMAL.
THE SURFACE RIDGE NOSING IN IS QUITE DRY WITH PRECIPITABLE WATER
VALUES IN THE 30 PERCENT RANGE ACROSS SRN CANADA. THIS GAVE WAY TO A
SUNNY BUT COOL DAY TODAY. A HIGHER AMPLITUDE RIDGE AXIS IS
ANCHORED IN THE DAKOTAS AND SOUTH...WHILE A DEEPER CYCLONE HAS NOW
SHIFTED ONSHORE INTO THE NWRN U.S. NUMEROUS SPOKES OF ENERGY ARE
CIRCULATING AROUND THAT LOW...ONE OF WHICH IS QUITE STRONG OVER
NEVADA WITH RAP ANALYSIS SHOWING A TROPOPAUSE FOLD TO NEAR
500MB...ON THE POLEWARD SIDE OF A MEASURED 100KT 250MB JET CORE
NOSE. THIS IS DRIVING HEIGHT FALLS ACROSS MT/ID/UT. SURFACE DEW
POINTS OF MEANING FOR CONVECTION ARE LOCATED IN OKLAHOMA...SOON TO
RETURN NORTHWARD.
FORECAST IS ON TRACK FOR CALMING WINDS TONIGHT AND CLEAR SKIES.
WIDESPREAD FROST SHOULD OCCUR WITH LOWER 30S FORECAST ACROSS NWRN
WI. WITH LOWER DEW POINTS OVER NWRN WI COUNTIES CURRENTLY...HAVE
DECIDED TO JUST ADD ALL OF THOSE COUNTIES INTO THE FROST ADVISORY.
BIG PICTURE DURING THIS PERIOD IS FALLING HEIGHTS AND PRESSURE IN
THE FRONT RANGE WITH SOUTHERLY FLOW INCREASING AND A RETURN OF
MOISTURE TO NEB/SD FRIDAY NIGHT. THIS WILL PLACE THE LOW-LEVEL
THERMAL BOUNDARY ACROSS THE FORECAST AREA FROM 850-925MB...SLIGHTLY
DISPLACED SWWRD...FROM KABR-KMLI. THE CONSENSUS NCEP MODELS AT
23.12Z REMAIN CONSISTENT WITH THEIR PREVIOUS RUNS ON THE FRONTAL
BOUNDARY BECOMING ACTIVE IN THE DAKOTAS/NEB FRIDAY EVENING AND
SHIFTING EAST INTO MN/IA OVERNIGHT. THE 23.00Z ECMWF/UKMET
SOLUTIONS DO AS WELL...HOWEVER THEY REMAIN FURTHER WEST.
THE 300/305K SURFACE IN THE NCEP SOLUTIONS REMAINS CONSISTENT WITH
AN 8G/KG MOISTURE SURGE ISENTROPICALLY LIFTING AND CONVERGING INTO
CENTRAL AND ERN MN FRIDAY OVERNIGHT WITH A FETCH OF ABOUT 500 J/KG
OF MUCAPE FEEDING IT. THE NAM SEEMS TO BE THE MOST AGRESSIVE. NOT
OVERLY IMPRESSIVE FOR SEVERE WEATHER...BUT RATHER THERE IS ENOUGH
FORCING TO GENERATE RA/TSRA SWWRD OF MSP. THE ECMWF SOLUTIONS
SUGGEST MORE OF A FOCUS IN SRN/SWRN MN. THE MAIN QUESTION IS HOW
FAR EAST DOES THIS CONVECTIVE COMPLEX TRACK FRIDAY NIGHT AND HOW FAR
EAST DOES THE FRONTAL BOUNDARY LIFT. HAVE INCREASED RAIN CHANCES
FURTHER EAST FOR FRIDAY NIGHT AND SATURDAY...HOWEVER WITH THE
VERIFICATION RECORD OF THE ECMWF...THERE IS STILL A CHANCE THE
EASTERN AREAS WILL BE DRY. CONFIDENCE IS LOW ON THE EXACT
LOCATION OF THE WEATHER...BUT HIGHER THAT IT WILL BE AN ACTIVE
FRONTAL ZONE WITH SHRA/ISO TSRA.
THIS QUESTION REMAINS THROUGH MONDAY...HOW FAR EAST WILL THE
FRONTAL BAND BE LOCATED. THE FRONT WILL LIKELY REMAIN ACTIVE WITH
SHOWERS/STORMS AND CLOUDS...AND HIGHS QUITE A BIT COOLER THANOUTSIDE
THE BAND. OVERALL...HAVE INCREASED RAIN CHANCES IN THE WRN/SRN
FORECAST AREA AND TRIED TO REMAIN NEARLY DRY IN THE EAST. SEEMS
LIKE IT WILL BE A CLOUDY WEEKEND...AND THUS HAVE LOWERED HIGHS
SUNDAY AND MONDAY AS WELL. SEVERE WEATHER THREATS ARE MOST
POSSIBLE IN SWRN MN CLOSER TO THE CAPE POOL...AND MONDAY LOOKS
MOST FAVORABLE SHOULD THE INSTABILITY INCREASE AS THE WARM FRONT
MOVES TOWARD MN. HOWEVER...ACTIVITY ALONG THAT FRONT THIS WEEKEND
MAY HAVE MUCH TO DO WITH HOW THE ENVIRONMENT/FRONT EVOLVES MONDAY.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 241 PM CDT THU MAY 23 2013
IT CONTINUES TO LOOK LIKE WE/LL UNFORTUNATELY NEED TO KEEP A
PROLONGED PERIOD OF CHANCE POPS IN THE FORECAST THROUGH THE WEEK
AS THE BAROCLINIC ZONE LINGERS IN THE AREA... WITH ELEVATED
INSTABILITY AND PERSISTENT WARM ADVECTION WORK TO GENERATE
SCATTERED SHRA/TSRA. THERE WILL UNDOUBTEDLY BE SOME DRY PERIODS...
WITH PCPN FOCUSED WHEN INDIVIDUAL SHORTWAVES RIPPLE SOUTHEAST
THROUGH THE UPPER FLOW... BUT AT THIS POINT IT IS IMPOSSIBLE TO
TRY AND PIN POINT WHEN SUCH DRY PERIODS MIGHT OCCUR. THE 12Z ECMWF
HAS COME AROUND MORE IN LINE WITH THE GFS IN KEEPING THINGS MORE
ACTIVE IN OUR AREA THROUGHOUT THE TIME PERIOD... ALTHOUGH BOTH
SUGGEST WE SHOULD FINALLY BRING THE UPPER TROUGH EAST TOWARD THE
REGION BY THE END OF THE WEEK. DEPENDING ON HOW THAT UNFOLDS... WE
COULD HAVE A POSSIBILITY FOR FOCUSED CONVECTION AND POSSIBLE
SEVERE WEATHER DURING THE THURSDAY-FRIDAY TIME FRAME. BUT... UNTIL
THAT POINT THE MAIN ISSUES WOULD LIKELY BE LOCALLY HEAVY RAIN AND
PERHAPS SOME HAIL. IN GENERAL... TEMPERATURES WILL WARM THROUGH
THE WEEK AS THE BONAFIDE WARM SECTOR SLOWLY LIFTS NORTH INTO THE
AREA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1243 PM CDT THU MAY 23 2013
HIGH PRESSURE AREA BUILDING IN WITH NEARLY CLEAR SKIES/VFR.
LARGEST 3 HOURLY PRESSURE CLIMBS ARE SHIFTING OFF TO THE SOUTHEAST
SO GRADIENT WILL SLACKEN CONSIDERABLY GOING INTO THIS EVENING.
EXPECT ANY LINGERING GUSTS TO CALM DOWN AND WITH RIDGE AXIS
SPREADING THROUGH TONIGHT...GRADUAL SHIFT TO SOUTHEAST LOW LEVEL
FLOW WILL MATERIALIZE GOING INTO FRIDAY MORNING. DRY AIRMASS SHOULD
KEEP SKIES CLEAR THROUGH MOST OF FRIDAY AS WELL.
KMSP...
VFR CONDITIONS TO CONTINUE. NORTHEAST WIND THIS AFTERNOON WILL
DECREASE AND SLOWLY BECOME SOUTHEAST BY FRIDAY MORNING.
/OUTLOOK FOR KMSP/
FRIDAY NIGHT...VFR. CHANCE OF SHOWERS. SOUTHEAST WIND 5 TO 15 KT.
SATURDAY...BRIEF MVFR CEILINGS POSSIBLE WITH A CHANCE OF
SHRA/TSRA. SOUTHEAST WIND 10 TO 20 KT.
SATURDAY NIGHT...MVFR CEILINGS AND VISIBILITIES POSSIBLE WITH A
CHANCE OF SHRA/TSRA. SOUTHEAST WIND 10 TO 20 KT.
SUNDAY...MVFR CEILINGS AND VISIBILITIES POSSIBLE WITH A CHANCE OF
SHRA/TSRA...BRIEF IFR CONDITIONS POSSIBLE. SOUTHEAST WIND 10 TO 20
KT.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 7 AM CDT FRIDAY FOR
MNZ045-052-053-063.
WI...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 7 AM CDT FRIDAY FOR
WIZ014>016-023>028.
&&
$$
SHORT TERM...BAUMGARDT/ARX
LONG TERM...
AVIATION....SHEA/ARX
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
ISSUED BY NATIONAL WEATHER SERVICE LA CROSSE WI
206 PM CDT THU MAY 23 2013
.SHORT TERM...THROUGH MONDAY
ISSUED AT 204 PM CDT THU MAY 23 2013
23.12Z RAOBS SHOW GOOD 925-850MB COLD ADVECTION ACROSS THE WRN GREAT
LAKES THIS MORNING IN MODERATE NORTHEAST FLOW. FRONTAL SLOPE OVER
THE STATE IS SOMETHING THAT WILL COME INTO PLAY FOR UPCOMING
FORECAST AND HOW FAR IT SLIDES SOUTHWEST. AT 12Z KINL-KABR HAD A 7C
TEMPERATURE DIFFERENCE AT 850MB /12C AT 925MB/. A MASSIVE DRYING
ACROSS MN OCCURRED OVERNIGHT WITH PRECIPITATELY WATER VALUES
PLUMMETING FROM 0.90 TO 0.32 INCHES...OR 136 TO 48 PERCENT NORMAL.
THE SURFACE RIDGE NOSING IN IS QUITE DRY WITH PRECIPITABLE WATER
VALUES IN THE 30 PERCENT RANGE ACROSS SRN CANADA. THIS GAVE WAY TO A
SUNNY BUT COOL DAY TODAY. A HIGHER AMPLITUDE RIDGE AXIS IS
ANCHORED IN THE DAKOTAS AND SOUTH...WHILE A DEEPER CYCLONE HAS NOW
SHIFTED ONSHORE INTO THE NWRN U.S. NUMEROUS SPOKES OF ENERGY ARE
CIRCULATING AROUND THAT LOW...ONE OF WHICH IS QUITE STRONG OVER
NEVADA WITH RAP ANALYSIS SHOWING A TROPOPAUSE FOLD TO NEAR
500MB...ON THE POLEWARD SIDE OF A MEASURED 100KT 250MB JET CORE
NOSE. THIS IS DRIVING HEIGHT FALLS ACROSS MT/ID/UT. SURFACE DEW
POINTS OF MEANING FOR CONVECTION ARE LOCATED IN OKLAHOMA...SOON TO
RETURN NORTHWARD.
FORECAST IS ON TRACK FOR CALMING WINDS TONIGHT AND CLEAR SKIES.
WIDESPREAD FROST SHOULD OCCUR WITH LOWER 30S FORECAST ACROSS NWRN
WI. WITH LOWER DEW POINTS OVER NWRN WI COUNTIES CURRENTLY...HAVE
DECIDED TO JUST ADD ALL OF THOSE COUNTIES INTO THE FROST ADVISORY.
BIG PICTURE DURING THIS PERIOD IS FALLING HEIGHTS AND PRESSURE IN
THE FRONT RANGE WITH SOUTHERLY FLOW INCREASING AND A RETURN OF
MOISTURE TO NEB/SD FRIDAY NIGHT. THIS WILL PLACE THE LOW-LEVEL
THERMAL BOUNDARY ACROSS THE FORECAST AREA FROM 850-925MB...SLIGHTLY
DISPLACED SWWRD...FROM KABR-KMLI. THE CONSENSUS NCEP MODELS AT
23.12Z REMAIN CONSISTENT WITH THEIR PREVIOUS RUNS ON THE FRONTAL
BOUNDARY BECOMING ACTIVE IN THE DAKOTAS/NEB FRIDAY EVENING AND
SHIFTING EAST INTO MN/IA OVERNIGHT. THE 23.00Z ECMWF/UKMET
SOLUTIONS DO AS WELL...HOWEVER THEY REMAIN FURTHER WEST.
THE 300/305K SURFACE IN THE NCEP SOLUTIONS REMAINS CONSISTENT WITH
AN 8G/KG MOISTURE SURGE ISENTROPICALLY LIFTING AND CONVERGING INTO
CENTRAL AND ERN MN FRIDAY OVERNIGHT WITH A FETCH OF ABOUT 500 J/KG
OF MUCAPE FEEDING IT. THE NAM SEEMS TO BE THE MOST AGRESSIVE. NOT
OVERLY IMPRESSIVE FOR SEVERE WEATHER...BUT RATHER THERE IS ENOUGH
FORCING TO GENERATE RA/TSRA SWWRD OF MSP. THE ECMWF SOLUTIONS
SUGGEST MORE OF A FOCUS IN SRN/SWRN MN. THE MAIN QUESTION IS HOW
FAR EAST DOES THIS CONVECTIVE COMPLEX TRACK FRIDAY NIGHT AND HOW FAR
EAST DOES THE FRONTAL BOUNDARY LIFT. HAVE INCREASED RAIN CHANCES
FURTHER EAST FOR FRIDAY NIGHT AND SATURDAY...HOWEVER WITH THE
VERIFICATION RECORD OF THE ECMWF...THERE IS STILL A CHANCE THE
EASTERN AREAS WILL BE DRY. CONFIDENCE IS LOW ON THE EXACT
LOCATION OF THE WEATHER...BUT HIGHER THAT IT WILL BE AN ACTIVE
FRONTAL ZONE WITH SHRA/ISO TSRA.
THIS QUESTION REMAINS THROUGH MONDAY...HOW FAR EAST WILL THE
FRONTAL BAND BE LOCATED. THE FRONT WILL LIKELY REMAIN ACTIVE WITH
SHOWERS/STORMS AND CLOUDS...AND HIGHS QUITE A BIT COOLER THANOUTSIDE
THE BAND. OVERALL...HAVE INCREASED RAIN CHANCES IN THE WRN/SRN
FORECAST AREA AND TRIED TO REMAIN NEARLY DRY IN THE EAST. SEEMS
LIKE IT WILL BE A CLOUDY WEEKEND...AND THUS HAVE LOWERED HIGHS
SUNDAY AND MONDAY AS WELL. SEVERE WEATHER THREATS ARE MOST
POSSIBLE IN SWRN MN CLOSER TO THE CAPE POOL...AND MONDAY LOOKS
MOST FAVORABLE SHOULD THE INSTABILITY INCREASE AS THE WARM FRONT
MOVES TOWARD MN. HOWEVER...ACTIVITY ALONG THAT FRONT THIS WEEKEND
MAY HAVE MUCH TO DO WITH HOW THE ENVIRONMENT/FRONT EVOLVES MONDAY.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 415 AM CDT THU MAY 23 2013
THE LONG TERM BEGINS WITH A LARGE HIGH PRESSURE SYSTEM OVER THE
WESTERN GREAT LAKES REGION. MUCH OF FRIDAY WILL BE DRY...WITH THE
EXCEPTION OF THE FAR WEST WHERE STRONG LOW LEVEL THETA-E ADVECTION
WILL COMMENCE IN THE AFTERNOON ON THE BACK SIDE OF THE HIGH. THIS
COUPLED WITH A SHORT WAVE AND MID LEVEL FRONTOGENESIS MOVING EAST
FROM THE NORTHERN PLAINS WILL DRIVE SHOWERS AND ISOLATED
THUNDERSTORMS INTO THE FAR WEST BY LATE AFTERNOON...WITH THE
ACTIVITY PASSING ACROSS THE FA FRIDAY NIGHT AND EARLY SATURDAY.
ELEVATED INSTABILITY IS MINIMAL FRIDAY NIGHT AND SEVERE WEATHER IS
NOT EXPECTED. THE BEST LOW LEVEL MOISTURE TRANSPORT IS AIMED FROM
THE CENTRAL PLAINS INTO IA FRIDAY NIGHT WITH JUST ABOUT ALL MODEL
SOLUTIONS POINTING TO THE HIGHEST QPF STAYING SOUTH OF MN.
IN THE WAKE OF THE SHORT WAVE ON SATURDAY...WE ARE BEGINNING TO SEE
THE NAM AND SREF TAKING ON MORE OF WHAT THE ECMWF HAS BEEN SHOWING
FOR 3 DAYS NOW...AND THAT IS A MORE AMPLIFIED FLOW ALOFT. THIS IS
VERY EVIDENT LOOKING AT THREE RUNS OF THE ECMWF SPACED 24 HOURS
APART. DEEPER UPPER LOWS ALONG BOTH COAST WITH MORE RIDGING IN THE
CENTER OF THE COUNTRY. WITH TIME...THIS BUILDS THE SURFACE HIGH
PRESSURE SYSTEM OVER THE GREAT LAKES BACK WEST ACROSS THE FA ALONG
WITH DRIER AIR. USING THE ECMWF OUTRIGHT WOULD PLACE DRY WEATHER
OVER ALL BUT OUR FAR WESTERN AND SOUTHERN COUNTIES IN MN FOR
SUNDAY AND MONDAY. GOING AGAINST THE GRAIN HOWEVER ARE THE GFS AND
GEM. BOTH ARE ADAMANT ON DRIVING WAVE AFTER WAVE ALOFT THROUGH THE
REGION BOTH DAYS WITH CONVECTIVE CLUSTERS. MODEL RUN QPF IS IN THE
SEVERAL INCH RANGE ACROSS PARTS OF THE MN CWA. ON THE OTHER HAND...
THE ECMWF ONLY HAS A TENTH TO A HALF INCH FROM NORTHEAST TO
SOUTHWEST ACROSS OUR AREA RESPECTIVELY FROM FRIDAY THROUGH
MONDAY. HENCE...THE WEEKEND/HOLIDAY MAY TURN OUT BETTER THAN THE
FORECAST INDICATES IF THE ECMWF IS MORE CORRECT. POPS ARE MORE
ALIGNED NOW WITH VERY LOW CHANCES IN WI WITH HIGHER CHANCES NEAR THE
WESTERN AND SOUTHERN BORDER.
ALTHOUGH THE RAIN CHANCES ARE DIMINISHING AFTER SATURDAY
MORNING...THERE IS GOOD CONSENSUS THAT ABUNDANT LOW LEVEL MOISTURE
WILL COVER THE AREA WITH A WARM FRONT REMAINING SOUTH OF US. THIS
WILL LIKELY YIELD PLENTY OF CLOUD COVER WITH HIGH TEMPERATURES
REMAINING IN THE 60S SATURDAY AND SUNDAY WITH UPPER 60S TO LOWER
70S ON SUNDAY. SHOWERS AND THUNDERSTORMS SHOULD BECOME MORE COMMON
OVER THE REGION FROM TUESDAY ONWARD AS THE TROUGH IN THE WEST
MOVES EAST. THIS WILL LIFT THE LOW PRESSURE SYSTEM AND WARM FRONT
INTO OUT AREA. THIS WILL ALSO INCREASE OUR THREAT FOR SEVERE
WEATHER.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1243 PM CDT THU MAY 23 2013
HIGH PRESSURE AREA BUILDING IN WITH NEARLY CLEAR SKIES/VFR.
LARGEST 3 HOURLY PRESSURE CLIMBS ARE SHIFTING OFF TO THE SOUTHEAST
SO GRADIENT WILL SLACKEN CONSIDERABLY GOING INTO THIS EVENING.
EXPECT ANY LINGERING GUSTS TO CALM DOWN AND WITH RIDGE AXIS
SPREADING THROUGH TONIGHT...GRADUAL SHIFT TO SOUTHEAST LOW LEVEL
FLOW WILL MATERIALIZE GOING INTO FRIDAY MORNING. DRY AIRMASS SHOULD
KEEP SKIES CLEAR THROUGH MOST OF FRIDAY AS WELL.
KMSP...
VFR CONDITIONS TO CONTINUE. NORTHEAST WIND THIS AFTERNOON WILL
DECREASE AND SLOWLY BECOME SOUTHEAST BY FRIDAY MORNING.
/OUTLOOK FOR KMSP/
FRIDAY NIGHT...VFR. CHANCE OF SHOWERS. SOUTHEAST WIND 5 TO 15 KT.
SATURDAY...BRIEF MVFR CEILINGS POSSIBLE WITH A CHANCE OF
SHRA/TSRA. SOUTHEAST WIND 10 TO 20 KT.
SATURDAY NIGHT...MVFR CEILINGS AND VISIBILITIES POSSIBLE WITH A
CHANCE OF SHRA/TSRA. SOUTHEAST WIND 10 TO 20 KT.
SUNDAY...MVFR CEILINGS AND VISIBILITIES POSSIBLE WITH A CHANCE OF
SHRA/TSRA...BRIEF IFR CONDITIONS POSSIBLE. SOUTHEAST WIND 10 TO 20
KT.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 7 AM CDT FRIDAY FOR
WIZ014>016-023>028.
&&
$$
SHORT TERM...BAUMGARDT/ARX
LONG TERM...RAH
AVIATION....SHEA/ARX
AREA FORECAST DISCUSSION
NWS RALEIGH NC
300 PM EDT THU MAY 23 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH THE AREA FROM THE WEST TODAY...LEADING TO
UNSETTLED WEATHER MOST OF THE DAY. AFTER FRONTAL PASSAGE
TONIGHT...THE INTRODUCTION OF CANADIAN HIGH PRESSURE WILL BRING
COOLER AND MORE SETTLED CONDITIONS TO THE REGION THROUGH THE HOLIDAY
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 240 PM THURSDAY...
UPPER LEVEL TROUGH CONTINUES TO DIG SOUTHWARD THIS AFTERNOON AIDED
BY A 50-75 KNOT UPPER JET OVER THE UPPER MISSISSIPPI VALLEY. THE
SURFACE COLD FRONT IS CURRENTLY MOVING ACROSS CENTRAL TENNESSEE AND
WILL TAKE ITS TIME MOVING ACROSS THE MOUNTAINS THIS EVENING. THE
MAIN 500 MB VORT MAX ASSOCIATED WITH THE FRONT WILL NOT ARRIVE UNTIL
CLOSER TO 00Z. FRONTAL PASSAGE WILL FINALLY OCCUR AFTER 00Z IN THE
NORTHWEST PIEDMONT...CLOSER TO 3Z IN THE TRIANGLE AREA...AND NEAR 6Z
FOR THE I-95 CORRIDOR.
CURRENT RADAR TRENDS SHOW A MYRIAD OF SURFACE BOUNDARIES LEFT OVER
FROM LAST NIGHTS CONVECTION AND DIFFERENTIAL HEATING THIS MORNING.
IN ADDITION A SMALL SHORTWAVE TROUGH IS MOVING NORTHWARD FROM
UPSTATE SOUTH CAROLINA. AT THIS TIME THE BOUNDARY INITIATING THE
MOST CONVECTION SPANS SW TO NE FROM THE ROCKINGHAM AREA TO ROANOKE
RAPIDS. AT THIS TIME INGREDIENTS FOR THUNDERSTORMS ARE A BIT
HEALTHIER THAN IN PREVIOUS DAYS. CURRENTLY THERE IS ABOUT 1000 ML
CAPE IN THE EAST WITH LOW LEVEL LAPSE RATES BETWEEN 7-8. EFFECTIVE
SHEAR IS AROUND 20 KNOTS. RAP SOUNDINGS SHOW VERY TALL SKINNY CAPE
IN THE HAIL GROWTH ZONE MAKING SEVERE HAIL UNLIKELY IN THIS SCENARIO
BUT PEA HAIL IS CERTAINLY POSSIBLE. STRAIGHT HODOGRAPHS WITH 20
KNOTS OF SHEAR SUPPORT A MORE LINEAR MULTICELLULAR CONVECTIVE MODE.
THERE IS A RELATIVELY DRIER LAYER NEAR 800 MB WITH A VERY MODEST
INVERTED V MAKING SEVERE WINDS A LITTLE BIT MORE POSSIBLE THAN IN
PREVIOUS DAYS BUT GUSTS WILL MORE LIKELY TOP OUT IN THE 30-40 KNOT
RANGE. CURRENT SPC ANALYSIS ALSO SHOWS AN AREA OF 500-700 J/KG OF
DCAPE ACROSS THE SOUTH CENTRAL PORTION OF THE CWA. DESPITE
PARAMETERS BEING RELATIVELY BETTER TODAY...MID LEVEL LAPSE RATES ARE
STILL VERY WEAK. OVERALL BULK SHEAR IS LOW. THERE IS ENOUGH LIFT IN
THE MID LEVELS TO SUPPORT MORE LIGHTNING THAN IN PREVIOUS DAYS BUT
ANY SEVERE THREAT WILL BE FAIRLY SUBDUED. AS THE VORT MAX APPROACHES
FROM THE NORTHWEST...DYNAMICS WILL IMPROVE SLIGHTLY AND IF THERE IS
STILL CONVECTION AROUND THE NORTHWEST PIEDMONT WOULD BE THE MOST
LIKELY LOCATION TO SEE SEVERE WEATHER.
WITH SEVERE POTENTIAL LOW...HEAVY RAIN AND FLOODING WILL AGAIN BE
THE LARGEST THREAT. WHILE ONLY A QUARTER TO A HALF OF AN INCH OF
WIDESPREAD PRECIPITATION IS EXPECTED...AREAS RECEIVING HEAVY RAINS
OVER THE PAST FEW DAYS WOULD BE A BIT MORE PRIMED FOR URBAN AND
SMALL STREAM FLOODING. CORFIDI VECTORS SHOW THAT STORMS SHOULD BE
PROGRESSIVE ENOUGH TO AVOID TRAINING BUT ORIENTATION OF INDIVIDUAL
BOUNDARIES COULD ALLOW FOR SOME TRAINING CELLS THIS AFTERNOON.
MOISTURE TRANSPORT...PW VALUES AND SURFACE CONVERGENCE ARE ALL BEST
IN THE COASTAL PLAIN THIS AFTERNOON...MAKING THIS THE MOST LIKELY
LOCATION FOR FLOODING TODAY.
SOUTH SOUTHWESTERLY WINDS TODAY WILL SHIFT TO NORTHWESTERLY AFTER
FRONTAL PASSAGE AND SUSTAINED WINDS WILL ELEVATE TO 10-15 KNOTS.
HIGHS TODAY WILL BE LARGELY DEPENDENT UPON CONVECTION AND CLOUD
COVER BUT IN GENERAL...UPPER 70S TO NEAR 80 IN THE NW AND LOWER TO
MID 80S IN THE SOUTH. LOWS WILL BE DEPENDENT UPON THE TIMING OF THE
FRONTAL PASSAGE UPPER 50S TO NEAR 60 IN THE NW AND MID 60S SE. SOME
MVFR CEILINGS OR VISIBILITIES COULD BE POSSIBLE IN THE EAST BEFORE
MAIN FRONT MOVES THROUGH EARLY FRIDAY MORNING.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
AS OF 240 PM THURSDAY...
FRIDAY AND FRIDAY NIGHT...
THE COLD FRONT WILL SLOWLY MOVE OUT OF THE EASTERN AREAS OF THE CWA
DURING THE EARLY MORNING. AFTER FRONTAL PASSAGE WINDS WILL SHIFT TO
NORTHWESTERLY AND INCREASE IN SPEED TO 15 KNOTS SUSTAINED. A VERY
TALL MIXED LAYER DURING THE AFTERNOON AND THE PASSAGE OF A 30 KNOT
850 JET WILL HELP TRANSPORT SOME OF THOSE WINDS DOWN TO THE SURFACE
AND GUSTS OF 25-30 KNOTS ARE POSSIBLE FRIDAY AFTERNOON. SKIES WILL
GRADUALLY CLEAR OUT AND THICKNESSES SUPPORT HIGH TEMPERATURES IN THE
MID 70S IN MOST LOCATIONS. ON FRIDAY NIGHT WINDS WILL REMAIN
BLUSTERY WHICH WILL HELP TO OFFSET RADIATIONAL COOLING A BIT AS
THICKNESSES SUPPORT LOWS NEAR 40 DEGREES BUT WILL GO A BIT
CONSERVATIVE IN THE LOWER 40S. STILL VERY POSSIBLE TO BREAK THE LOW
TEMPERATURE RECORDS AT BOTH RDU AND GSO WHICH ARE BOTH 43 DEGREES.
-ELLIS
SATURDAY THROUGH SUNDAY NIGHT...
A DEEP UPPER LEVEL LOW WILL DRIFT NWD ALONG THE NORTHERN MID
ATLANTIC AND NEW ENGLAND COAST THROUGH SUNDAY. DUE TO THE EXTENSIVE
CIRCULATION ASSOCIATED WITH THIS SYSTEM IN TANDEM WITH AN AMPLIFYING
RIDGE OVER THE CENTRAL U.S....THE FLOW ALOFT ACROSS CENTRAL NC WILL
BE NWLY. AT THE SURFACE...COOL CANADIAN HIGH PRESSURE WILL BUILD
SEWD FROM THE GREAT LAKES INTO THE CAROLINAS. THE DEEP N-NW FLOW
WILL RESULT IN A DRY AND COOL HOLIDAY WEEKEND. THICKNESSES SATURDAY
AFTERNOON IN THE 1360S...SOME 30-35M BELOW NORMAL AND SUPPORTIVE OF
TEMPS UPPER 60S TO NEAR 70. ALLOWING FOR THE WARMTH OF A LATE MAY
SUN...FAVOR TEMPS IN THE LOW-MID 70S.
TEMPS WILL COOL OFF QUICKLY SATURDAY EVENING THEN STABILIZE AS MODEL
RH CROSS SECTIONS SUGGEST INCREASING MID-HIGH LEVEL CLOUDINESS AFTER
MIDNIGHT. THESE CLOUDS ASSOCIATED WITH DISTURBANCES IN THE NW FLOW
ALOFT. THIS TYPE OF PATTERN SUPPORTIVE OF OROGRAPHIC ENHANCED
CLOUDINESS...SO THE USUALLY TOO WET GFS MAY BE ONTO SOMETHING. THE
ARRIVAL OF THESE CLOUDS WILL PLAY A ROLE IN DETERMINING MIN TEMPS.
FAVOR COOLEST TEMPS NE WHERE CLOUDS WILL BE LESS/THINNER COMPARED TO
THE WEST-SW. IF CLOUDS ARE SLOW TO ARRIVE OR THIN...MIN TEMPS MAY
END UP BEING 2-3 DEGREES COOLER THAN FORECAST.
MODEST WARM UP EXPECTED SUNDAY AS THICKNESSES RECOVER INTO THE
1370S/LOW 1380S. EXPECT AFTERNOON TEMPS IN THE MID-UPPER 70S UNDER
PARTLY-MOSTLY SUNNY SKIES. SUNDAY NIGHT SHOULD BE A LITTLE MILDER AS
AIR MASS CONTINUES TO MODIFY. MOS GUIDANCE APPEARS TOO WARM BY A
CATEGORY. FAVOR MIN TEMPS NEAR 50 COOLER SPOTS TO LOW-MID 50S
ELSEWHERE. -WSS
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 300 PM THURSDAY...
12Z GFS TRENDING TOWARD THE 00Z ECMWF. THE ECMWF HELD ONTO THE L/W
TROUGH ALONG THE EASTERN SEABOARD RESULTING IN A SLOWER WARMING
TREND WHERE AS THE GFS WITH ITS BUILDING MID-UPPER HEIGHTS
ADVERTISES A QUICKER/MORE NOTABLE WARM-UP. THE ECMWF SOLUTION OF A
LINGERING TROUGH NEAR OR OFFSHORE OF THE NEW ENGLAND COAST AND AN
AMPLIFYING RIDGE OVER THE MS RIVER VALLEY WILL MAINTAIN A NW FLOW
ALOFT OVER CENTRAL NC. THE ECMWF HINTS AT POSSIBLE DISTURBANCES
ASSOCIATED WITH MCS ACTIVITY THAT MAY OCCUR IN THE UPPER MID
WEST/GREAT LAKES TUESDAY-THURSDAY CROSSING OUR REGION. IF THIS WERE
TO OCCUR...COULD SEE A PERIOD OF UNSETTLED WEATHER ANYTIME BETWEEN
WEDNESDAY-THURSDAY. IF GFS WERE TO VERIFY WITH THE RIDGE BUILDING
CLOSER TO HOME...MCS ACTIVITY WILL BE SHUNTED MORE TO OUR NORTH. FOR
NOW...WILL KEEP POPS NO HIGHER THAN 20 PERCENT TUESDAY INTO
THURSDAY. LOW LEVEL THICKNESSES RETURN TO NEAR OR SLIGHTLY ABOVE
NORMAL VALUES TUESDAY ONWARD. WILL HAVE AFTERNOON TEMPS NEAR 80-LOWER
80S TUESDAY...AND LOW-MID 80S WEDNESDAY/THURSDAY. AGAIN...IF GFS
VERIFIES...WED/THU COULD SEE TEMPS IN THE UPPER 80S TO NEAR 90.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 140 PM THURSDAY...
24 HOUR TAF PERIOD: COMPLICATED LOW CONFIDENCE FORECAST FOR THIS
AFTERNOON. SEVERAL OUTFLOW AND DIFFERENTIAL HEATING BOUNDARIES HAVE
SET UP ACROSS CENTRAL NORTH CAROLINA THIS AFTERNOON. APPROACHING
FROM THE SOUTHWEST IS A SHORTWAVE TROUGH THAT WAS LOCATED OVER
NORTHERN GA THIS MORNING. ALL OF THESE SURFACE BOUNDARIES WILL BE
FOCI FOR THE GENESIS OF SHOWERS AND STORMS THIS AFTERNOON. THE MOST
PROMINENT BOUNDARY AT THIS TIME IS BISECTING THE CWA FROM SW TO NE
AND WILL BE AFFECTING KFAY AND KRWI IN THE NEXT COUPLE OF HOURS.
HEAVY RAIN AND GUSTY WINDS ARE LIKELY WITH THESE STORMS ALONG WITH
IFR/MVFR CEILINGS AND VISIBILITIES. OTHERWISE VFR CONDITIONS WILL
PREVAIL OUTSIDE OF STORMS WITH WINDS OUT OF THE SOUTH SOUTHWEST AT
5-10 KNOTS. LATER THIS AFTERNOON A MORE CONCENTRATED LINE OF SHOWERS
AND STORMS ASSOCIATED WITH THE PRE-FRONTAL TROUGH WILL MAKE THEIR
WAY ACROSS THE AREA WITH THE TRIAD TERMINALS AFFECTED JUST BEFORE
0Z. THIS LINE WILL SLOWLY PROGRESS EASTWARD GETTING TO KRDU AND KFAY
IN THE VICINITY OF 3Z AND KRWI CLOSER TO 6Z.
FOR FRIDAY CONDITIONS WILL RETURN TO VFR BUT STRONG GUSTY WINDS WILL
BE THE PROBLEM OF THE DAY WITH 15-20 KNOTS SUSTAINED OUT OF THE
NORTHWEST GUSTING TO 25-30 KNOTS. SKIES WILL GRADUALLY CLEAR
THROUGHOUT THE DAY.
LONG TERM: SATURDAY WILL SEE A PROLONGED RETURN TO VFR CONDITIONS
THROUGH MONDAY MAKING CONDITIONS VERY FAVORABLE FOR GENERAL AVIATION
THROUGH THE EXTENDED MEMORIAL DAY WEEKEND.
&&
.CLIMATE...
MORNING LOW TEMPERATURES ON THE 25TH AND 26TH ARE EXPECTED TO BE
NEAR RECORD MIN TEMPS FOR THE DATE.
RECORD MIN TEMP/YEAR SET MAY 25TH MAY 26TH
RDU 43 / 1967 43 / 1979
GSO 43 / 1956 42 / 1930
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...ELLIS
NEAR TERM...ELLIS
SHORT TERM...ELLIS/WSS
LONG TERM...WSS
AVIATION...ELLIS
CLIMATE...RAH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
242 PM EDT THU MAY 23 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH THE AREA FROM THE WEST TODAY...LEADING TO
UNSETTLED WEATHER MOST OF THE DAY. AFTER FRONTAL PASSAGE
TONIGHT...THE INTRODUCTION OF CANADIAN HIGH PRESSURE WILL BRING
COOLER AND MORE SETTLED CONDITIONS TO THE REGION THROUGH THE HOLIDAY
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 240 PM THURSDAY...
UPPER LEVEL TROUGH CONTINUES TO DIG SOUTHWARD THIS AFTERNOON AIDED
BY A 50-75 KNOT UPPER JET OVER THE UPPER MISSISSIPPI VALLEY. THE
SURFACE COLD FRONT IS CURRENTLY MOVING ACROSS CENTRAL TENNESSEE AND
WILL TAKE ITS TIME MOVING ACROSS THE MOUNTAINS THIS EVENING. THE
MAIN 500 MB VORT MAX ASSOCIATED WITH THE FRONT WILL NOT ARRIVE UNTIL
CLOSER TO 00Z. FRONTAL PASSAGE WILL FINALLY OCCUR AFTER 00Z IN THE
NORTHWEST PIEDMONT...CLOSER TO 3Z IN THE TRIANGLE AREA...AND NEAR 6Z
FOR THE I-95 CORRIDOR.
CURRENT RADAR TRENDS SHOW A MYRIAD OF SURFACE BOUNDARIES LEFT OVER
FROM LAST NIGHTS CONVECTION AND DIFFERENTIAL HEATING THIS MORNING.
IN ADDITION A SMALL SHORTWAVE TROUGH IS MOVING NORTHWARD FROM
UPSTATE SOUTH CAROLINA. AT THIS TIME THE BOUNDARY INITIATING THE
MOST CONVECTION SPANS SW TO NE FROM THE ROCKINGHAM AREA TO ROANOKE
RAPIDS. AT THIS TIME INGREDIENTS FOR THUNDERSTORMS ARE A BIT
HEALTHIER THAN IN PREVIOUS DAYS. CURRENTLY THERE IS ABOUT 1000 ML
CAPE IN THE EAST WITH LOW LEVEL LAPSE RATES BETWEEN 7-8. EFFECTIVE
SHEAR IS AROUND 20 KNOTS. RAP SOUNDINGS SHOW VERY TALL SKINNY CAPE
IN THE HAIL GROWTH ZONE MAKING SEVERE HAIL UNLIKELY IN THIS SCENARIO
BUT PEA HAIL IS CERTAINLY POSSIBLE. STRAIGHT HODOGRAPHS WITH 20
KNOTS OF SHEAR SUPPORT A MORE LINEAR MULTICELLULAR CONVECTIVE MODE.
THERE IS A RELATIVELY DRIER LAYER NEAR 800 MB WITH A VERY MODEST
INVERTED V MAKING SEVERE WINDS A LITTLE BIT MORE POSSIBLE THAN IN
PREVIOUS DAYS BUT GUSTS WILL MORE LIKELY TOP OUT IN THE 30-40 KNOT
RANGE. CURRENT SPC ANALYSIS ALSO SHOWS AN AREA OF 500-700 J/KG OF
DCAPE ACROSS THE SOUTH CENTRAL PORTION OF THE CWA. DESPITE
PARAMETERS BEING RELATIVELY BETTER TODAY...MID LEVEL LAPSE RATES ARE
STILL VERY WEAK. OVERALL BULK SHEAR IS LOW. THERE IS ENOUGH LIFT IN
THE MID LEVELS TO SUPPORT MORE LIGHTNING THAN IN PREVIOUS DAYS BUT
ANY SEVERE THREAT WILL BE FAIRLY SUBDUED. AS THE VORT MAX APPROACHES
FROM THE NORTHWEST...DYNAMICS WILL IMPROVE SLIGHTLY AND IF THERE IS
STILL CONVECTION AROUND THE NORTHWEST PIEDMONT WOULD BE THE MOST
LIKELY LOCATION TO SEE SEVERE WEATHER.
WITH SEVERE POTENTIAL LOW...HEAVY RAIN AND FLOODING WILL AGAIN BE
THE LARGEST THREAT. WHILE ONLY A QUARTER TO A HALF OF AN INCH OF
WIDESPREAD PRECIPITATION IS EXPECTED...AREAS RECEIVING HEAVY RAINS
OVER THE PAST FEW DAYS WOULD BE A BIT MORE PRIMED FOR URBAN AND
SMALL STREAM FLOODING. CORFIDI VECTORS SHOW THAT STORMS SHOULD BE
PROGRESSIVE ENOUGH TO AVOID TRAINING BUT ORIENTATION OF INDIVIDUAL
BOUNDARIES COULD ALLOW FOR SOME TRAINING CELLS THIS AFTERNOON.
MOISTURE TRANSPORT...PW VALUES AND SURFACE CONVERGENCE ARE ALL BEST
IN THE COASTAL PLAIN THIS AFTERNOON...MAKING THIS THE MOST LIKELY
LOCATION FOR FLOODING TODAY.
SOUTH SOUTHWESTERLY WINDS TODAY WILL SHIFT TO NORTHWESTERLY AFTER
FRONTAL PASSAGE AND SUSTAINED WINDS WILL ELEVATE TO 10-15 KNOTS.
HIGHS TODAY WILL BE LARGELY DEPENDENT UPON CONVECTION AND CLOUD
COVER BUT IN GENERAL...UPPER 70S TO NEAR 80 IN THE NW AND LOWER TO
MID 80S IN THE SOUTH. LOWS WILL BE DEPENDENT UPON THE TIMING OF THE
FRONTAL PASSAGE UPPER 50S TO NEAR 60 IN THE NW AND MID 60S SE. SOME
MVFR CEILINGS OR VISIBILITIES COULD BE POSSIBLE IN THE EAST BEFORE
MAIN FRONT MOVES THROUGH EARLY FRIDAY MORNING.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
AS OF 240 PM THURSDAY...
FRIDAY AND FRIDAY NIGHT...
THE COLD FRONT WILL SLOWLY MOVE OUT OF THE EASTERN AREAS OF THE CWA
DURING THE EARLY MORNING. AFTER FRONTAL PASSAGE WINDS WILL SHIFT TO
NORTHWESTERLY AND INCREASE IN SPEED TO 15 KNOTS SUSTAINED. A VERY
TALL MIXED LAYER DURING THE AFTERNOON AND THE PASSAGE OF A 30 KNOT
850 JET WILL HELP TRANSPORT SOME OF THOSE WINDS DOWN TO THE SURFACE
AND GUSTS OF 25-30 KNOTS ARE POSSIBLE FRIDAY AFTERNOON. SKIES WILL
GRADUALLY CLEAR OUT AND THICKNESSES SUPPORT HIGH TEMPERATURES IN THE
MID 70S IN MOST LOCATIONS. ON FRIDAY NIGHT WINDS WILL REMAIN
BLUSTERY WHICH WILL HELP TO OFFSET RADIATIONAL COOLING A BIT AS
THICKNESSES SUPPORT LOWS NEAR 40 DEGREES BUT WILL GO A BIT
CONSERVATIVE IN THE LOWER 40S. STILL VERY POSSIBLE TO BREAK THE LOW
TEMPERATURE RECORDS AT BOTH RDU AND GSO WHICH ARE BOTH 43 DEGREES.
-ELLIS
SATURDAY THROUGH SUNDAY NIGHT...
A DEEP UPPER LEVEL LOW WILL DRIFT NWD ALONG THE NORTHERN MID
ATLANTIC AND NEW ENGLAND COAST THROUGH SUNDAY. DUE TO THE EXTENSIVE
CIRCULATION ASSOCIATED WITH THIS SYSTEM IN TANDEM WITH AN AMPLIFYING
RIDGE OVER THE CENTRAL U.S....THE FLOW ALOFT ACROSS CENTRAL NC WILL
BE NWLY. AT THE SURFACE...COOL CANADIAN HIGH PRESSURE WILL BUILD
SEWD FROM THE GREAT LAKES INTO THE CAROLINAS. THE DEEP N-NW FLOW
WILL RESULT IN A DRY AND COOL HOLIDAY WEEKEND. THICKNESSES SATURDAY
AFTERNOON IN THE 1360S...SOME 30-35M BELOW NORMAL AND SUPPORTIVE OF
TEMPS UPPER 60S TO NEAR 70. ALLOWING FOR THE WARMTH OF A LATE MAY
SUN...FAVOR TEMPS IN THE LOW-MID 70S.
TEMPS WILL COOL OFF QUICKLY SATURDAY EVENING THEN STABILIZE AS MODEL
RH CROSS SECTIONS SUGGEST INCREASING MID-HIGH LEVEL CLOUDINESS AFTER
MIDNIGHT. THESE CLOUDS ASSOCIATED WITH DISTURBANCES IN THE NW FLOW
ALOFT. THIS TYPE OF PATTERN SUPPORTIVE OF OROGRAPHIC ENHANCED
CLOUDINESS...SO THE USUALLY TOO WET GFS MAY BE ONTO SOMETHING. THE
ARRIVAL OF THESE CLOUDS WILL PLAY A ROLE IN DETERMINING MIN TEMPS.
FAVOR COOLEST TEMPS NE WHERE CLOUDS WILL BE LESS/THINNER COMPARED TO
THE WEST-SW. IF CLOUDS ARE SLOW TO ARRIVE OR THIN...MIN TEMPS MAY
END UP BEING 2-3 DEGREES COOLER THAN FORECAST.
MODEST WARM UP EXPECTED SUNDAY AS THICKNESSES RECOVER INTO THE
1370S/LOW 1380S. EXPECT AFTERNOON TEMPS IN THE MID-UPPER 70S UNDER
PARTLY-MOSTLY SUNNY SKIES. SUNDAY NIGHT SHOULD BE A LITTLE MILDER AS
AIR MASS CONTINUES TO MODIFY. MOS GUIDANCE APPEARS TOO WARM BY A
CATEGORY. FAVOR MIN TEMPS NEAR 50 COOLER SPOTS TO LOW-MID 50S
ELSEWHERE. -WSS
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 255 AM THURSDAY...
SATURDAY AND SUNDAY...
A TERRIFIC WEEKEND IS SHAPING UP AS CANADIAN HIGH PRESSURE WILL
BUILD SOUTH OUT OF THE GREAT LAKES INTO THE EASTERN CONUS. THIS WILL
RESULT IN CLEAR SKIES SATURDAY WITH DRY AND COOLER AIR IN PLACE.
UPPER FLOW WILL BE NORTHWEST AND MODEL CROSS SECTIONS SHOW THAT SOME
HIGH CLOUDINESS COULD MILDLY IMPEDE THE SUNSHINE ON SUNDAY. HIGHS
BOTH DAYS WILL BE MOSTLY IN THE MID 70S. MEANWHILE... SUNDAY
MORNINGS LOW TEMPERATURE WILL BE CONSIDERABLY BELOW NORMAL DUE TO
EXCELLENT RADIATIONAL CONDITIONS...IN THE 45 TO 50 DEGREE RANGE.
MONDAY THROUGH WEDNESDAY....
THE SURFACE HIGH PRESSURE MIGRATES OFFSHORE EARLY NEXT WEEK WHICH
WILL RESULT IN A GRADUAL WARMER AND MOISTER TREND INTO MIDWEEK. WE
WILL BE UNDER A BUILDING LOW AMPLITUDE UPPER RIDGE THROUGH THE
PERIOD WHICH WILL TEND TO SUPPRESS CONVECTION...ESPECIALLY WITH NO
EASILY IDENTIFIABLE FORCING OTHER THAN GENERALLY INCREASING
INSTABILITY WITH LEE TROFFING IN NORTHWEST FLOW AND POTENTIAL FOR
SOME INLAND PENETRATION OF SEA BREEZE CONVECTION IN THE EAST. AS
SUCH...WILL NOT MEDDLE WITH ONGOING SLIGHT CHANCE FOR LATE DAY
CONVECTION MONDAY THROUGH WEDNESDAY. TEMPS WILL BE ON THE UPTICK...
FROM 75 TO 80 ON MONDAY RISING TO 80 TO 85 ON WEDNESDAY...WITH MINS
FOLLOWING A SIMILAR TREND...FROM THE MID 50S MONDAY MORNING TO THE
LOWER 60S WEDNESDAY MORNING.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 140 PM THURSDAY...
24 HOUR TAF PERIOD: COMPLICATED LOW CONFIDENCE FORECAST FOR THIS
AFTERNOON. SEVERAL OUTFLOW AND DIFFERENTIAL HEATING BOUNDARIES HAVE
SET UP ACROSS CENTRAL NORTH CAROLINA THIS AFTERNOON. APPROACHING
FROM THE SOUTHWEST IS A SHORTWAVE TROUGH THAT WAS LOCATED OVER
NORTHERN GA THIS MORNING. ALL OF THESE SURFACE BOUNDARIES WILL BE
FOCI FOR THE GENESIS OF SHOWERS AND STORMS THIS AFTERNOON. THE MOST
PROMINENT BOUNDARY AT THIS TIME IS BISECTING THE CWA FROM SW TO NE
AND WILL BE AFFECTING KFAY AND KRWI IN THE NEXT COUPLE OF HOURS.
HEAVY RAIN AND GUSTY WINDS ARE LIKELY WITH THESE STORMS ALONG WITH
IFR/MVFR CEILINGS AND VISIBILITIES. OTHERWISE VFR CONDITIONS WILL
PREVAIL OUTSIDE OF STORMS WITH WINDS OUT OF THE SOUTH SOUTHWEST AT
5-10 KNOTS. LATER THIS AFTERNOON A MORE CONCENTRATED LINE OF SHOWERS
AND STORMS ASSOCIATED WITH THE PRE-FRONTAL TROUGH WILL MAKE THEIR
WAY ACROSS THE AREA WITH THE TRIAD TERMINALS AFFECTED JUST BEFORE
0Z. THIS LINE WILL SLOWLY PROGRESS EASTWARD GETTING TO KRDU AND KFAY
IN THE VICINITY OF 3Z AND KRWI CLOSER TO 6Z.
FOR FRIDAY CONDITIONS WILL RETURN TO VFR BUT STRONG GUSTY WINDS WILL
BE THE PROBLEM OF THE DAY WITH 15-20 KNOTS SUSTAINED OUT OF THE
NORTHWEST GUSTING TO 25-30 KNOTS. SKIES WILL GRADUALLY CLEAR
THROUGHOUT THE DAY.
LONG TERM: SATURDAY WILL SEE A PROLONGED RETURN TO VFR CONDITIONS
THROUGH MONDAY MAKING CONDITIONS VERY FAVORABLE FOR GENERAL AVIATION
THROUGH THE EXTENDED MEMORIAL DAY WEEKEND.
&&
.CLIMATE...
MORNING LOW TEMPERATURES ON THE 25TH AND 26TH ARE EXPECTED TO BE
NEAR RECORD MIN TEMPS FOR THE DATE.
RECORD MIN TEMP/YEAR SET MAY 25TH MAY 26TH
RDU 43 / 1967 43 / 1979
GSO 43 / 1956 42 / 1930
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...ELLIS
NEAR TERM...ELLIS
SHORT TERM...ELLIS/WSS
LONG TERM...MLM
AVIATION...ELLIS
CLIMATE...RAH