Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/23/12
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
930 AM MDT FRI SEP 21 2012
.UPDATE...
&&
.SHORT TERM...CURRENT FORECASTS ON TRACK SO NO CHANGES NEEDED. BOTH
HRRR AND RAP INDICATING THE POSSIBILITY OF GUSTY NORTHWEST ACROSS
THE FAR NORTHEAST CORNER DURING THE AFTERNOON...STILL LOOKING LIKE
WINDS SHOULD STAY BELOW RED FLAG CRITERIA. AIRMASS REMAINS DRY.
.AVIATION...CURRENT TAF TRENDS LOOK REASONABLE.
&&
.PREV DISCUSSION... /ISSUED 411 AM MDT FRI SEP 21 2012/
SHORT TERM...ANOTHER DAY WITH DRY NORTHERLY FLOW ALOFT ACROSS
COLORADO. THERE HAS BEEN JUST SLIGHT COOLING IN THE MID
LEVELS WHICH WILL TAKE OFF A COUPLE DEGREES FROM YESTERDAYS HIGH
TEMPS...BUT READINGS WILL STILL BE A FEW DEGREES ABOVE NORMAL.
CIRRUS HAS BEEN THINNING QUITE RAPIDLY SO ANOTHER DAY OF MOSTLY
SUNNY SKIES BUT SLIGHTLY HAZY CONDITIONS DUE TO WESTERN U.S.
FIRES. OUR FIRE DANGER WILL ONCE AGAIN BE ELEVATED ON THE FAR
EASTERN PLAINS WITH DRY AND BREEZY NORTHERLY FLOW...BUT LIKELY
JUST SHY OF RED FLAG CRITERIA.
MAINLY CLEAR SKIES...LIGHT AND VARIABLE WINDS...AND DRY AIRMASS
WILL ALLOW FOR STRONG RADIATIONAL COOLING TONIGHT.
LONG TERM...DRY AND WARM WEATHER ARE EXPECTED TO CONTINUE THROUGH
THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK. THE UPPER LEVEL
RIDGE AXIS IS FORECAST TO STAY IN POSITION OF COLORADO INTO
MONDAY. AFTERNOON TEMPERATURES ACROSS THE PLAINS WILL CONTINUE
REACHING THE LOWER TO MID 80S THROUGH THE WEEKEND WITH SOME HIGH
CLOUDS AT TIMES...BUT OTHERWISE A DRY AIRMASS.
NEXT WEEK IS BEGINNING TO LOOK A LITTLE MORE UNSETTLED AS THE GFS
AND ECMWF BRING AN UPPER LEVEL LOW ACROSS THE STATE FROM TUESDAY
THROUGH THURSDAY. THE UPPER LOW WILL BE ORIGINATING OFF THE
PACIFIC NORTHWEST COAST AND WILL CONTAIN SOME COOLER AIR ALOFT.
THE AIRMASS MAY BECOME UNSTABLE ENOUGH TO SUPPORT A FEW AFTERNOON
THUNDERSTORMS EACH DAY. TEMPERATURES WILL ALSO BE COOLING TO MORE
SEASONAL VALUES DUE TO THE PRESENCE OF MORE CLOUDS AND A BIT MORE
MOISTURE IN THE AIR. AT THIS TIME THE MODELS ARE SHOWING AN ONLY
WEAKLY ORGANIZED SYSTEM WHICH IS ALSO DIFFICULT TO TELL HOW FAST
IT WILL MOVE OUT. THUS A BROAD-BRUSH FORECAST OF COOLER
TEMPERATURES AND A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS
THROUGH MOST OF THE WEEK.
AVIATION...WIND PATTERN LOOKS VERY SIMILAR TO YESTERDAY WITH
NORMAL DRAINAGE WINDS BECOMING NORTHWESTERLY BY 15Z-16Z AND THEN
NORTH/NORTHEASTERLY AROUND 17Z-18Z AS DEEPER MIXING OCCURS. ONLY
DIFFERENCE IS WINDS MAY NOT TRANSITION TO NORMAL DRAINAGE
TONIGHT WITH A WEAK PUSH FROM HIGH PRESSURE BUILDING OVER THE
NORTHERN/CENTRAL PLAINS. THIS SHOULD HAVE A TENDENCY TO KEEP A
MORE EAST/SOUTHEASTERLY BUT VERY LIGHT WIND COMPONENT IN PLACE.
HYDROLOGY...NO ISSUES THROUGH THIS WEEKEND.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....DANKERS
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS ALBANY NY
500 AM EDT FRI SEP 21 2012
.SYNOPSIS...
A COLD FRONT TO OUR WEST WILL DISSIPATE AS IT WORKS INTO OUR REGION
TODAY. IT WILL NEVERTHELESS BRING THE THREAT OF A FEW SHOWERS TO THE
SOUTHEASTERN ADIRONDACKS AND CENTRAL MOHAWK VALLEY. A MUCH STRONGER
COLD FRONT WILL APPROACH OUR REGION ON SATURDAY...THEN MOVE THROUGH
DURING SATURDAY EVENING. THIS FRONT WILL LIKELY BRING SHOWERS AND
POSSIBLY THUNDERSTORMS CONTAINING GUSTY WINDS. COOLER WEATHER WILL
FOLLOW FOR SUNDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 500 AM...SHOWERS...ASSOCIATED WITH A FRONT AND A PIECE OF
POSITIVE VORITICTY ON THE LEADING EDGE OF THE UPPER TROUGH HAVE
PRODUCED LIGHT SHOWERS TO THE NORTHWEST OF HERKIMER COUNTY.
THE 06Z NAM AND THE HRRR ALL INDICATED THIS SHOWER ACTIVITY WILL NOT
MAKE INTO OUR REGION...AT LEAST THROUGH THE EARLY MORNING HOURS.
WILL FOLLOW THAT CUE...BUT LATER ON AS THERE WILL BE A BIT MORE
INSTABILITY AND THE FRONT/VORTEX CENTER INCH CLOSER...WILL CONTINUE
WITH SLIGHT/LOW POPS WELL TO THE NORTHWEST OF THE CAPITAL REGION
THIS AFTERNOON. WILL CONTINUE TO MENTION THE SLIGHT CHANCE OF
THUNDER AS WELL. ANY RAINFALL LOOKS PRETTY LIGHT...UNDER A QUARTER
OF AN INCH.
WE ARE ALSO DEALING WITH SOME AREAS OF LOW CLOUDS AND A LITTLE OF
PATCHY FOG. NEITHER ARE EXPECTED TO EXPAND A WHOLE LATE THROUGH
EARLY MORNING...AND IN FACT...WILL DISSIPATE BY LATE MORNING.
HOWEVER...THERE WILL BE HIGH AND MID LEVEL CLOUDS OCCASIONALLY
FILTERING OUT THE SUNSHINE.
THE MAJORITY OF THE REGION SHOULD REMAIN DRY TODAY WITH TEMPERATURES
RUNNING SLIGHTLY ABOVE NORMAL...LOWER TO MID 70S VALLEY REGIONS...65
TO 70 HIGHER TERRAIN. THERE WILL BE A SOUTH BREEZE 5 TO 10 MPH ALONG
WITH A PARTLY SUNNY SKY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
TONIGHT...THE REMNANTS OF THE AFOREMENTIONED COLD FRONT...STILL TO
OUR WEST...COULD STILL LINGER A FEW SHOWERS AND A THUNDERSTORM TO
THE NORTHWEST OF THE CAPITAL DISTRICT. WHILE NOT REALLY A COLD FRONT
ANYMORE...THIS FEATURE COULD PRODUCE ENOUGH LOW LEVEL CONVERGENCE
ALONG WITH SOME POOLING OF MOISTURE TO KEEP THE THREAT OF SHOWERS
THROUGH THE OVERNIGHT PERIOD INTO EARLY SATURDAY MORNING.
WITH A SOUTHERLY BREEZE AND SOME CLOUDS AGAIN TONIGHT LEANED WITH
THE WARMER MET GUIDANCE REGARDING OVERNIGHT LOW TEMPERATURES. THIS
WOULD MEAN THEY WOULD BE RELATIVELY MILD FOR THE TIME OF
YEAR...GENERALLY IN THE 50S...WITH SOME UPPER 40S IN SOME OF THE
COOLER VALLEY...ESPECIALLY IN THE GREENS.
ON SATURDAY...THE UPPER TROUGH WILL BE SHIFTING EASTWARD TOWARDS THE
EASTERN GREAT LAKES...WITH ANOTHER STRONGER SURFACE COLD FRONT THAT
WILL APPROACH FROM THE WEST AND LIKELY A PRE-FRONTAL TROUGH AHEAD OF
THE COLD FRONT.
AN INCREASING SOUTHERLY FLOW WILL ALLOW FOR TEMPERATURES TO BE ABOVE
NORMAL FOR LATE SEPTEMBER...WITH MIDDLE TO UPPER 70S IN VALLEY
AREAS...MID 60S TO LOWER 70S HIGHER TERRAIN. IT WILL TURN QUITE
BREEZY WITH SOUTHERLY WIND 10 TO 20 MPH GUSTING UP TOWARD 30 MPH.
WITH THE EXCEPTION OF OUR NORTHWESTERN ZONES WHERE CHANCES OF
SHOWERS CONTINUE...THE WEATHER LOOKS TO START OUT MAINLY DRY ACROSS
THE MAJORITY OF THE REGION SATURDAY. POPS WILL INCREASE TO LIKELY
DURING THE AFTERNOON IN OUR NORTHWESTERN ZONES...AND BY
EVENING...WILL BE LIKELY ACROSS MOST OF OUR REGION AS THE
AFOREMENTIONED PRE-FRONTAL TROUGH AND A STRONG VORT MAX WORK INTO
OUR REGION.
A BAND OF SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THE PRE FRONTAL
TROUGH AND THE ACTUAL COLD FRONT FOR SATURDAY AFTERNOON THROUGH THE
EVENING HOURS. THE TIMING OF BOTH SYSTEMS LOOKS SLIGHTLY FASTER THAN
BEFORE...SO THE BULK OF SHOWERS MIGHT BE MOVING OUT AFTER MIDNIGHT
SATURDAY.
THE STORM PREDICATION CENTER (SPC) CONTINUES WITH WITH A SLIGHT RISK
FOR SEVERE THUNDERSTORMS...MAINLY FOR SATURDAY AFTERNOON.
ONCE AGAIN...IT LOOKS AS IF WE WILL BE DEALING WITH ANOTHER
SITUATION WHERE THE INSTABILITY IS MARGINAL (BUT MORE THAN TUESDAY)
WITH PROJECTED SURFACE CAPE VALUES AROUND 1000 J/KG. THE MID LEVEL
LAPSE RATES HOWEVER...DO LOOK TO STEEPEN UP TO ABOUT 6.0
C/KM...STILL BELOW THE 6.5 C/KM CONSIDERED TO BE STEEP TO PRODUCE
LARGE HAIL AND GOOD DOWNWARD MOMENTUM OF MID LEVEL WINDS. THE H850
JET PROGGED TO REACH AROUND 45KTS.
THE LATEST 00Z/06Z NAM RUNS CONTINUE TO SHOW A SPIKE IN THE 0-6KM
BULK SHEAR LAYER RIGHT AHEAD OF THE REAL COLD FRONT...UP TO 70KTS
BUT AS MENTIONED BY THE PREVIOUS FORECASTER...THIS STRIPE OF STRONG
BULK SHEAR DOES NOT FULLY INTERSECT THE AXIS OF MAXIMUM INSTABILITY.
SO ONCE AGAIN...THE POTENTIAL OF SEVERE IS VERY MARGINAL...BUT
NEVERTHELESS THE POTENTIAL FOR STRONG TO LOCALLY SEVERE
THUNDERSTORMS IS THERE AND WE WILL CONTINUE TO MENTION IN OUR
HAZARDOUS WEATHER OUTLOOK BUT NOT IN THE GRIDS.
PWATS LOOK TO REACH ABOUT 1.5 INCH RIGHT AHEAD OF THE COLD FRONT AND
PRE-FRONTAL TROUGH SO WE ARE NOT LOOKING AT THE SAME LEVELS AS
TUESDAY/S "TROPICAL CONNECTION." THE SOUTHERLY H850 WIND COMPONENT
IS ABOUT 2 STANDARD DEVIATIONS ABOVE NORMAL (NOT THE 4-5 AS WE SAW
ON TUESDAY).
THIS ALL POINTS TO A PRETTY GOOD SOAKING RAINFALL BUT THE QPF SHOULD
BE A LOT LESS THAN TUESDAY. MORE ABOUT THAT CAN BE FOUND IN OUR
HYDRO SECTION.
THE ACTUAL COLD FRONT LOOKS TO WORK ACROSS THE ENTIRE REGION
SATURDAY OVERNIGHT. MUCH COOLER AIR WILL FOLLOW WITH H850 TEMPS
FALLING FROM ABOUT A HIGH +14C LATE SATURDAY...DOWN TO ABOUT +1C
(NW) TO ABOUT +4C (SE) BY SUNDAY MORNING! WITH PARTIAL CLEARING WE
ARE STILL LOOKING FOR TEMPS TO DROP TO ABOUT 50 IN THE HUDSON
VALLEY...40S ACROSS THE HIGHER TERRAIN.
LARGE HIGH PRESSURE BUILD IN TO OUR SOUTHWEST ON SUNDAY. WITH THE
COOL AIR ALOFT...EXPECT PLENTY OF STRATO-CU TO MIX WITH
SUNSHINE...ESPECIALLY OVER THE HIGHER TERRAIN. AT THIS POINT... THE
SURFACE TO 10000 FOOT FLOW DOES NOT LOOK FAVORABLE FOR PURE LAKE
EFFECT SHOWERS (ALTHOUGH IT WOULD BE PLENTY COOL AND UNSTABLE FOR
THESE). WITH THE FLOW VEERING FROM WNW AT THE SURFACE TO SW
ALOFT...LAKE EFFECT SHOULD BE MINIMIZED DUE TO TOO MUCH WIND SHEAR.
HOWEVER...UPSLOPE SHOWERS ARE A POSSIBILITY SO WE ASSIGNED LOW POPS
TO ELEVATIONS HIGHER THAN 10000 AGL ON SUNDAY...KEEPING THE VALLEYS
DRY (ALTHOUGH A SPRINKLE CANNOT BE RULED OUT). TEMPERATURES ON
SUNDAY WILL ONLY REACH THE MID TO UPPER 60S IN THE HUDSON
VALLEY...LOWER 60S OTHER VALLEY AREAS (NAMELY THE MOHAWK AND
SCHOHARIE VALLEYS). TEMPERATURES WILL ONLY BE THE 50S ACROSS THE
HIGHER TERRAIN.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THE LINGERING UPPER LEVEL TROF WILL CONTINUE A THREAT FOR ISOLATED
TO SCATTERED SHOWERS ACROSS THE NORTHWEST PART OF THE FORECAST AREA
SUNDAY NIGHT AND MONDAY. LATE SUNDAY NIGHT AND EARLY MONDAY
MORNING...IT COULD EVEN BE COLD ENOUGH FOR SOME SNOW TO MIX IN AS
WELL ACROSS THE HIGHER TERRAIN OF THE ADIRONDACKS. ELSEWHERE...
EXPECT FAIR BUT COOL CONDITIONS. LOWS SUNDAY NIGHT WILL BE IN THE
MID 30S TO MID 40S. HIGHS MONDAY IN THE MID 50S TO MID 60S.
HIGH PRESSURE BRIEFLY BUILDS INTO THE REGION FOR MONDAY NIGHT AND
TUESDAY WITH MAINLY CLEAR TO PARTLY CLOUDY SKIES. LOWS MONDAY NIGHT
WILL BE IN THE MID 30S TO MID 40S. HIGHS TUESDAY 60 TO 70.
ANOTHER COLD FRONT AND ASSOCIATED UPPER LEVEL TROF WILL APPROACH THE
REGION FROM THE WEST TUESDAY NIGHT...BUT WILL ONLY VERY SLOWLY CROSS
THE REGION WEDNESDAY AND WEDNESDAY NIGHT. HAVE KEPT POPS FAIRLY LOW
WITH THIS SYSTEM (20 TO 30 PERCENT) DUE TO ITS RELATIVELY
DISORGANIZED NATURE. LOWS TUESDAY NIGHT WILL BE IN THE 40S...HIGHS
WEDNESDAY IN THE 60S TO LOWER 70S...AND LOWS WEDNESDAY NIGHT 40 TO
50.
HIGH PRESSURE BUILDS SOUTH FROM CANADA ON THURSDAY WITH SKIES
BECOMING MOSTLY SUNNY. HIGHS THURSDAY WILL BE IN THE 60S.
&&
.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
YET ANOTHER TRICKY CALL ON POTENTIAL FOG AND STRATUS CLOUDS
OVERNIGHT. LOW LEVEL MOISTURE WILL INCREASE OVERNIGHT...MAINLY IN
THE FORM OF A HIGHER STRATUS CLOUD DECK...MAINLY AT VFR/MVFR LEVELS.
HOWEVER...AT KPSF HAVE INCLUDED A TEMPO GROUP FOR THE STRATUS TO
BECOME IFR BETWEEN 08Z AND 12Z. THE EXPANSION OF THE STRATUS DECK
MEANS THAT IFR VSBY DUE TO FOG WILL BE LESS LIKELY THIS MORNING THAN
YESTERDAY MORNING. HAVE ONLY INCLUDED MVFR VSBY DUE TO FOR THIS
MORNING AT THE TAF SITES...INCLUDING KGFL. AFTER 12Z TO 13Z EXPECT
VFR CONDITIONS AT THE KGFL/KALB/KPOU/KPSF TAF SITES AS SUNSHINE
BURNS OFF THE STRATUS DECK TO JUST SCT CLOUDS. EXPECT THE VFR
CONDITIONS TO PERSIST THROUGH THE END OF THE TAF PERIOD AT 06Z
SATURDAY.
CALM TO LIGHT SOUTH WINDS EXPECTED THROUGH A FEW HOURS AFTER
SUNRISE...THEN THE SOUTHERLY FLOW WILL INCREASE TO 6-10 KT WITH SOME
GUSTS TO AROUND 15 KTS. THE WINDS WILL BECOME LIGHT AGAIN AFTER
SUNSET ON FRIDAY.
OUTLOOK...
LATE FRI NT...MAINLY VFR. NO SIG WX.
SAT-SUN...VFR. CHC SUB-VFR SHRA/TSRA LATE SAT INTO EARLY SUN.
SUN NT-TUE...VFR. NO SIG WX.
&&
.FIRE WEATHER...
A FEW SHOWERS POSSIBLE NORTH AND WEST OF ALBANY TODAY BUT THEY WILL
BE LIGHT...WELL UNDER A QUARTER OF AN INCH. OTHERWISE DRY TODAY BUT
RH VALUES WILL ONLY DROP TO AROUND 50 PERCENT THIS AFTERNOON ALONG
WITH A SOUTH WIND 5-10 MPH.
RH VALUES WILL ONCE AGAIN RISE TO 90-100 PERCENT TONIGHT. RH VALUES
WILL DROP TO AROUND 50-60 PERCENT ON SATURDAY WITH SHOWERS AND
THUNDERSTORMS LIKELY MAINLY DURING THE LATE DAY AND EARLY EVENING
HOURS. THESE SHOULD PRODUCE ANOTHER WIDESPREAD QUARTER INCH OR MORE
OF RAINFALL. IT WILL BE QUITE BREEZY SATURDAY WITH A SOUTH WIND 10
TO 20 MPH...WITH SOME GUSTS UPWARD OF 30 MPH.
MUCH COOLER SUNDAY WITH A WESTERLY WIND 5 TO 15 MPH. A MIX OF SUN
AND CLOUDS...AND THERE IS THREAT OF ADDITIONAL LIGHT SHOWERS MAINLY
OVER THE HIGHER TERRAIN.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO PROBLEMS ARE LIKELY FOR THE NEXT 5 DAYS.
SOME LIGHT SHOWERS ARE POSSIBLE NORTHWEST OF THE CAPITAL TODAY.
THESE WILL AMOUNT TO WELL UNDER A QUARTER OF AN INCH AND WILL HAVE
NO HYDROLOGICAL IMPACT.
A FEW MORE SHOWERS POSSIBLE NORTHWEST TONIGHT INTO EARLY SATURDAY.
THEN THE THREAT OF MORE NUMEROUS SHOWERS AND THUNDERSTORMS AS WE
HEAD INTO SATURDAY AFTERNOON AND EVENING.
AT THIS POINT...PWATS LOOK TO REACH ABOUT 1.5 INCHES (NOT THE 2+
INCHES WE HAD ON TUESDAY). AN H850 SOUTHERLY WIND COMPONENT UP TO 45
KTS WILL BE ABOUT 2 STANDARD DEVIATIONS ABOVE SEASONAL NORMALS (NOT
THE 4-5 STANDARD DEVIATIONS WE SAW ON TUESDAY).
THEREFORE...AT THIS POINT WE ARE CONFIDENT THE RAINFALL ON SATURDAY
INTO SATURDAY NIGHT WILL BE NOWHERE WHAT WE SAW ON TUESDAY. WE ARE
LOOKING AT A PROJECTED RAINFALL BASIN AVERAGE ANYWHERE FROM ABOUT
HALF TO AN INCH OF RAINFALL. OF COURSE...ANY THUNDERSTORM COULD
PRODUCE LOCALLY HEAVIER RAINFALL...BUT PROBABLY NO MORE THAN TWO
INCHES IN ANY GIVEN SPOT.
THIS TYPE OF RAINFALL MIGHT RESULT IN SOME WITHIN BANK RISES ON SOME
RIVERS AND STREAMS...BUT OTHER THAN THE USUAL PONDING OF WATER ON
ROADWAYS AND AREAS OF POOR DRAINAGE...NO SIGNIFICANT HYDRO PROBLEMS
ARE ANTICIPATED.
THE SHOWERS WILL END ON SUNDAY ALTHOUGH THERE COULD BE A FEW
ADDITIONAL LIGHT ONES ACROSS THE HIGHER TERRAIN BUT WITH NO
ADDITIONAL HYDROLOGICAL IMPACT THROUGH SUNDAY NIGHT.
DRY MONDAY AND TUESDAY WITH THE NEXT CHANCE OF SHOWERS WEDNESDAY.
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...HWJIV
NEAR TERM...HWJIV/FRUGIS
SHORT TERM...HWJIV/FRUGIS
LONG TERM...GJM
AVIATION...GJM
FIRE WEATHER...HWJIV
HYDROLOGY...HWJIV
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
601 PM EDT FRI SEP 21 2012
.SYNOPSIS...
HIGH PRESSURE LOCATED TO THE NORTHEAST WILL WEAKEN THROUGH TONIGHT.
THIS WILL ALLOW A COLD FRONT TO APPROACH FROM THE WEST AND CROSS
THE REGION ON SATURDAY INTO SATURDAY NIGHT. A LARGE HIGH PRESSURE
SYSTEM THEN BUILDS IN FROM THE WEST ON SUNDAY AND PERSISTS THROUGH
MIDWEEK. ANOTHER COLD FRONT WILL MOVE THROUGH THE AREA LATE WEDNESDAY
OR THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
NO BIG CHANGES TO TONIGHT. BASED ON LATEST HRRR AND COSPA AS WELL
AS RADAR RETURNS, WE DROPPED THE LOW CHANCES OF SHRAS GETTING
INTO THE POCONOS. TEMPS AND DEW POINTS ARE PRETTY MUCH SPOT ON,
WITH LESS SKY COVER WE DROPPED THEM SLIGHTLY FASTER DURG THE
EVENING, BUT MAINTAINED CURRENT MINS.
THIS SC SHOULD CLEAR THIS EVENING AS THE SUN SETS. DEWPOINTS HIGHER
TONIGHT THAN THIS PAST MORNING...ESPECIALLY E PA AND SOME DECOUPLING
INDICATED WITH A BL WIND UNDER 15 KT. SREF GUIDANCE AND TSECS OF
12Z/21 MODELS ARE GUIDING US TOWARD AN IFR/LIFR DEVELOPMENT OF ST
AND/OR FOG...AT LEAST IN THE INTERIOR AFTER 04Z. IF THERE IS A
DECK OF CLOUDS ABV 2000 FT...THAT WOULD MINIMIZE THE LIFR RISK.
FOR NOW...PATCHY FOG WILL BE IN THE GRIDS AND THINKING IS THE
THICKEST FOG WILL OCCUR IN E PA/FAR W NJ...NEAR AND WEST OF THE
DELAWARE.
WE MAY NEED TO RUN OUR FOG TOOLS AGAIN THIS EVENING AS I WASNT
SATISFIED WITH THE OUTPUT IN THE MID AFTN GRIDDED ISSUANCE.
TEMPS/WINDS/DEWPOINTS ARE 50 50 BLENDED 12Z/21 GFS/NAM GUIDANCE.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
AFTER MORNING FOG/ST CLEAR AROUND 14Z...A VERY FINE DAY IS UPCOMING...
PLENTY OF SS...GUSTY SSW WIND TO 20 MAYBE EVEN 25 MPH IN THE MID
AFTN AND 600J OF ML CAPE. THE APPROACHING CF THROUGH PA WILL HAVE
SHOWERS ALONG IT BUT THE CONVECTIVE INDICES DO NOT LOOK IMPRESSIVE
TO ME AND THINKING IS ONLY EMBEDDED ISO TSTMS LATE IN THE DAY IN E
PA. DUE TO SPEED SHEAR...THERE COULD BE A GUSTY TSTM TO 35 OR 40
KTS BUT ITS NOT SOMETHING THAT AM FAVORING ATTM.
TEMPS/WINDS/DEWPOINTS ARE BLENDED 21/12Z GFS/NAM MOS FAVORING THE
WARMER NAM VALUES IN SSW WARM SECTOR BL FLOW.
CONFIDENCE: AVERAGE
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
A CDFNT WILL BE CROSSING THE REGION AT THE START OF THE PD AND
WILL TRIGGER SHWRS AND SOME TSTMS. WE REMAIN IN A SLIGHT RISK FOR
SEVERE ON SATURDAY, BUT THE SET UP IS NOT LOOKING ALL THAT
PROMISING FOR A WIDESPREAD KIND OF EVENT. THE UPPER LEVEL JET IS
CENTERED PRETTY FAR OFF TO OUR NORTHWEST AND BETTER SITUATED WITH
THE STRONG MID LEVEL SHORTWAVE. SHEAR IS DECENT BUT STILL REMAINS
BEST OFF TO OUR NORTH. TIME OF DAY IS ALSO A FACTOR AS THE BRUNT
OF THE WX LOOKS TO OCCUR DURG THE EVE WELL AFTER PK HEATING. THERE
COULD BE SOME LCLY HVY RAIN, BUT OVERALL QPF VALUES ARE NOT ALL
THAT HIGH.
THE FRONT WILL CLEAR THE COAST BY DAYBREAK AND A LARGE AREA OF
HIGH PRESSURE OVER THE MIDSECTION OF THE COUNTRY WILL BEGIN TO
BUILD INTO THE ERN STATES. THIS HIGH WILL KEEP CONDS DRY THROUGH
ABOUT WEDNESDAY, AS THE HIGH MOVES EWD. BY LATER WED OR THU
ANOTHER CDFNT MAY APPROACH THE REGION.
TEMPS WILL START OFF BLO NRML BEHIND THE AFOREMENTIONED FROPA THEN
REBOUND TO NR SEASONAL BY MIDWEEK.
&&
.AVIATION /22Z FRIDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
TONIGHT...VFR TO START...BUT AFTER 04Z OR 05Z FOG AND STRATUS SHOULD
START DEVELOPING...MAINLY IN THE AXIS ALONG AND W OF KILG-KPHL-KFWN...
ENOUGH EXPECTED TO FORCE IFR OR LIFR CONDS AFTER 08Z IN PARTS OF
THAT AREA. LIGHT S-SE WIND. CONFIDENCE AVG.
SATURDAY...IFR CONDS TO START AT LEAST IN THE KILG-KPHL-KFWN REGION
WESTWARD ACROSS E PA BUT THIS SHOULD ALL BECOME VFR SCT AOA 3500 FT
BY 15Z. SSW WIND G 20 KTS IN THE AFTERNOON. SCT SHOWERS ARRIVE
FROM W TO E AFTER 18Z IN E PA WITH POSSIBLE EMBEDDED TSTM NEAR
22Z. CONFIDENCE AVG.
OUTLOOK...
SATURDAY NIGHT...MVFR AND PSBL IFR IN SHOWERS AND THUNDERSTORMS
MAINLY EARLY AS A COLD FRONT CROSSES THE REGION. IMPROVING CONDS
BY DAYBREAK.
SUNDAY THROUGH WEDNESDAY...THE COLD FRONT MOVES OFFSHORE EARLY ON
SUNDAY AND CONDITIONS SHOULD GRADUALLY IMPROVE TO VFR FROM WEST TO
EAST. HIGH PRESSURE THEN BUILDS IN KEEPING GOOD FLYING CONDITIONS
ACROSS THE TERMINALS THROUGH THE MIDDLE OF THE WEEK.
&&
.MARINE...
NO HEADLINES THROUGH AT LEAST MIDDAY SATURDAY.
CONSIDERABLE UNCERTAINTY REGARDING EXCEEDING SCA THRESHOLD FROM
MID AFTERNOON SATURDAY INTO SAT NIGHT. WE HAVE GRIDDED SCA
CONDITIONS IN THE ATLC WATERS BUT THIS COULD BE SLIGHTLY OVERDONE.
12Z/21 NAM WAS MORE ROBUST THAN THE GFS/ECMWF.
ESE WIND G UNDER 15 KTS NOW BECOMING MORE SSE DURING THE NIGHT AND
THE SSW SATURDAY. G SAT AFTERNOON MAY NUDGE 25 KTS AND ATLC SEAS
MAY REACH 5 FT IN THE AFTN.
OUTLOOK...
A COLD FRONT WILL MOVE THROUGH SATURDAY NIGHT INTO EARLY SUNDAY,
BRINGING SHOWERS AND THUNDERSTORMS THROUGH THE AREA WATERS. SEAS
WILL LIKELY BE IN THE 5-6 FT RANGE SAT NIGHT ON THE OCEAN FRONT.
AS THE FRONT MOVES THROUGH, THE WINDS WILL TURN TO THE WEST AND
BECOME QUITE GUSTY, AROUND 25 KNOTS, WHICH WILL AID IN KEEPING THE
SEAS AT OR ABOVE 5 FEET THROUGH MUCH OF SUNDAY. SEAS SHOULD START
TO SUBSIDE BY LATE SUNDAY AFTERNOON OR EVENING. A SCA WILL LIKELY
BE NEEDED DURG THIS TIME PD.
HIGH PRESSURE BUILDS IN ON SUNDAY AND PERSISTS THROUGH THE MIDWEEK
PERIOD, KEEPING WINDS AND WAVES BELOW SMALL CRAFT ADVISORY CRITERIA.
&&
.RIP CURRENTS...
APPARENTLY A COUPLE OF RESCUES ALONG THE NJ COAST THIS AFTN WITH AN
E SWELL OF 3 FT VARYING BETWEEN 6 AND 12 SECONDS. WE UPGRADED THE
SRF RISK TO MODERATE FOR NJ.
SATURDAY AND SUNDAY...A MODERATE RISK FOR DANGEROUS RIP CURRENTS
SHOULD PREVAIL WITH A 10 TO 12 SECOND PERIOD 3 TO 4 FT E SWELL.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...NIERENBERG
NEAR TERM...DRAG/GIGI
SHORT TERM...DRAG
LONG TERM...NIERENBERG
AVIATION...DRAG/NIERENBERG
MARINE...DRAG/NIERENBERG
RIP CURRENTS...
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
441 AM EDT FRI SEP 21 2012
.SYNOPSIS...
HIGH PRESSURE LOCATED OFF TO OUR NORTHEAST WILL WEAKEN TODAY.
MEANWHILE, A COLD FRONT WILL APPROACH FROM THE WEST AND CROSS THE
REGION ON SATURDAY. HIGH PRESSURE BUILDS IN FROM THE WEST ON SUNDAY
AND PERSISTS THROUGH MIDWEEK. ANOTHER COLD FRONT WILL MOVE THROUGH
THE AREA LATE WEDNESDAY OR THURSDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THERE ARE A COUPLE OF ISSUES THAT NEED ATTENTION IN THE EARLY
MORNING PORTION OF THE FORECAST.
THE FIRST PROBLEM IS FOG. THE STRATUS HAS BEEN FAIRLY SLOW TO
DEVELOP OUTSIDE OF THE SOUTHERN POCONOS AND PORTIONS OF THE LEHIGH
VALLEY. INSTEAD...RADIATIONAL COOLING IS ALLOW MOISTURE TO POOL
UNDER THE VERY LOW INVERSION IN PLACE TO FORM FOG. THE GEOCAT
PRODUCT SHOWS THAT THE FOG HAS SPREAD INTO THE DELAWARE VALLEY AND
INTO PORTIONS OF WESTERN NEW JERSEY. THUS FAR...THE VISIBILITIES
HAVE REMAINED ABOVE ONE-QUARTER OF A MILE (WITH KABE AND KUKT THE
EXCEPTIONS). SHOULD THE LOWER VISIBILITIES BECOME MORE
WIDESPREAD... A SHORT FUSED DENSE FOG ADVISORY COULD BECOME
NEEDED.
THE NEXT PROBLEM IS THE POTENTIAL FOR LIGHT SHOWER ACTIVITY ACROSS
PORTIONS OF EASTERN NEW JERSEY. KDIX IS SHOWING SOME LIGHT RETURNS
(GENERALLY LESS THAN 10 DBZ) MOVING WEST TOWARD THE CAPE MAY
COAST. AN AREA OF MORE SUBSTANTIAL SHOWERS IS MOVING NORTH ABOUT
85 TO 90 MILES SOUTHEAST OF KACY. THE LATEST HRRR AND 0000 UTC NAM
SUGGEST THAT SOME OF THIS ACTIVITY WILL AFFECT EASTERN NEW JERSEY
(MAINLY FROM OCEAN COUNTY SOUTH TO CAPE MAY COUNTY) BEFORE
DAYBREAK.
NAM MODEL SOUNDINGS (WHICH ARE BETTER CAPTURING THE MOISTURE
SPREADING OUT UNDER THE LOW INVERSION) SUGGEST THE LOW CLOUDS BREAK
BETWEEN 1300 AND 1500 UTC. TIMING MAY BE AN ISSUE SINCE THE SUN
ANGLE IS GETTING LOWER...BUT THE CLOUDS MAY END UP HANGING ON THE
LONGEST CLOSER TO THE NEW JERSEY COAST. AFTER THE CLOUDS BREAK...
SCATTERED CUMULUS COULD REMAIN...ESPECIALLY ACROSS NORTHWEST ZONES.
THE SCATTERED SHOWERS (AND EMBEDDED THUNDER) ASSOCIATED WITH THE
WARM FRONT AND MID LEVEL SHORT WAVE OVER THE GREAT LAKES SHOULD PASS
TO THE NORTHWEST OF THE AREA THIS AFTERNOON. FOR NOW...THE NORTHWEST
ZONES WILL REMAIN DRY FOR THIS AFTERNOON...BUT TRENDS ON HOW THE
PRECIPITATION EVOLVES TO THE WEST MAY NEED TO BE MONITORED.
850 MB TEMPERATURES SUGGEST HIGHS IN THE IN THE MID TO UPPER 70S
OUTSIDE OF THE INFLUENCE OF TERRAIN AND THE WATERS. THIS IS CLOSE TO
THE MOS MEAN...AND IS ACCEPTED.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
THE FORECAST PROBLEM FOR TONIGHT WILL AGAIN BE SKY COVER. THE LOW
LEVEL FLOW LOOKS TO REMAIN MORE SOUTHERLY TONIGHT (AS OPPOSED TO
SOME VARIATION OF EAST). THE LOW LEVEL WIND DIRECTION CHANGE WOULD
IMPLY THAT THE LOWER LEVELS WOULD NOT BE AS MOIST...NOR WOULD THE
LOW LEVEL INVERSION BE AS PRONOUNCED. HOWEVER...WARM AIR ADVECTION
ON THE NOSE OF THE LOW LEVEL JET MAY ALLOW THE INVERSION TO
LOWER...AND THIS PRESENTS THE POTENTIAL FOR LOWER CLOUDS TO MOVE
BACK IN AFTER MIDNIGHT.
MODEL SOUNDINGS ARE LESS BULLISH ON THE THREAT FOR LOWER CLOUDS...
WITH THE GFS EVEN LESS SO. BASED ON THIS...WILL NOT HIT THE LOWER
CLOUDS TOO HARD TONIGHT...BUT THIS MAY NEED TO BE REVISITED.
SHOWERS SHOULD DEVELOP ON THE NOSE OF THE LOW LEVEL JET. THE MODEL
CONSENSUS IS TO TAKE THE WARM AIR ADVECTION DEVELOPING OVER THE
LOWER OHIO VALLEY THIS MORNING INTO NORTHEAST PENNSYLVANIA AFTER
0600 UTC. FURTHER SOUTH AND EAST...THE LIFT GENERATED BY THE WARM
AIR ADVECTION SHOULD BE INSUFFICIENT FOR SHOWER GENERATION...AND THE
REMAINDER OF THE FORECAST AREA SHOULD REMAIN DRY TONIGHT.
THE AIRMASS CONTINUES TO SLOWLY WARM FROM WITHIN. THIS WOULD SUGGEST
THAT LOW WOULD BE CLOSER TO A MOS BLEND THAN THE COOLER GFS MOS
NUMBERS.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
THE MID LEVEL TROUGH ACROSS THE UPPER MIDWEST, CONTINUES TO DEEPEN
ON SATURDAY AS IT BECOMES MORE OF A CLOSED LOW. A STRONG SHORTWAVE
WILL ROTATE THROUGH THE BASE OF THE TROUGH SATURDAY EVENING. ONE THE
SHORTWAVE ROTATES THROUGH THE MID LEVEL FLOW, THE TROUGH STARTS TO
WEAKEN A BIT AND LIFT NORTH. WHILE THE MAIN MID LEVEL LOW SHOULD BE
WELL NORTH OF THE REGION BY MONDAY, ANOTHER STRONG SHORTWAVE WILL
ROTATE THROUGH THE FLOW AND ACROSS OUR REGION ON MONDAY.
AT THE SURFACE, THE COLD FRONT WILL PUSH ACROSS PENNSYLVANIA DURING
THE DAY SATURDAY AND THEN START TO MOVE THROUGH OUR AREA MAINLY LATE
SATURDAY AFTERNOON THROUGH SATURDAY NIGHT, EXITING OFF THE COAST BY
EARLY SUNDAY MORNING. OUT AHEAD OF THE FRONT, WE SHOULD SEE SOME
DECENT WARM AIR ADVECTION TAKE PLACE AND INCREASE IN MOISTURE AS THE
SURFACE FLOW WILL BE PREDOMINATELY OUT OF THE SOUTH.
WHILE THE STORM PREDICTION CENTER HAS US IN A SLIGHT RISK FOR SEVERE
WEATHER, THE SET UP IS NOT LOOKING ALL THAT PROMISING FOR A
WIDESPREAD KIND OF EVENT. THE UPPER LEVEL JET IS CENTERED PRETTY FAR
OFF TO OUR NORTHWEST AND BETTER SITUATED WITH THE STRONG MID LEVEL
SHORTWAVE. SHEAR IS DECENT BUT STILL REMAINS BEST OFF TO OUR NORTH.
PLENTY OF MOISTURE WILL BE AVAILABLE AS PWATS GENERALLY FALL INTO
THE 1.5-2.0 INCH RANGE, WHICH IS WELL ABOVE NORMAL FOR MID TO LATE
SEPTEMBER, AND DEWPOINTS SHOULD HAVE NO PROBLEM RISING BACK UP INTO
60S. SO WE WILL NEED TO KEEP AN EYE ON HEAVY RAIN AND ANY POTENTIAL
FLOODING ISSUES THAT MAY ARISE FROM THAT. TIME OF DAY MAY PLAY A BIG
ROLE IN JUST HOW MUCH ACTION WE SEE AHEAD OF AND ALONG THE FRONT.
WITH TEMPERATURES EXPECTED TO RISE INTO THE 80S ACROSS NEARLY THE
ENTIRE REGION, WE COULD GET ENOUGH SURFACE HEATING TO CONTRIBUTE TO
THE SEVERE THREAT. THE LIMITING FACTOR ON THE SURFACE HEATING MAY
ACTUALLY BE THE CLOUD COVER. WARM MOIST AIR WILL CONTRIBUTE TO THE
RISING TEMPERATURES AND DEWPOINTS BUT CLOUD COVER MAY END UP
LIMITING THE CONVECTIVE DEVELOPMENT.
AS THE FRONT MOVES OFFSHORE EARLY SUNDAY MORNING, WE WILL SEE A
DRYING TREND DEVELOP AS A LARGE AREA OF HIGH PRESSURE BUILDS ACROSS
THE MID-ATLANTIC REGION. SOME MUCH COLDER AIR WILL MAKES IT WAY INTO
OUR REGION THROUGH THE DAY ON SUNDAY. MAXIMUM TEMPERATURES WILL BE
IN THE UPPER 60S TO LOWER 70S. THE GUIDANCE EVEN INDICATES THAT
TEMPERATURES MAY STRUGGLE TO REACH 70 THROUGH THE DAY. WITH THE
COOLER AIR IN PLACE AND CLEARING SKIES WE SHOULD RADIATE EXTREMELY
WELL SUNDAY NIGHT. TEMPERATURES WILL FALL INTO THE 40S, MAY STAY
CLOSER TO 50 IN THE MORE URBAN AREAS, AND TEMPERATURES ACROSS THE
NORTHERN ZONES MAY ACTUALLY FALL INTO THE MIDDLE TO UPPER 30S! WE
COULD SEE SOME FRONT DEVELOP ACROSS THE NORTHERN AREAS AND WE HAVE
ADDED PATCHY FROST INTO THE FORECAST FOR NOW. AS THE GROWING SEASON
IS STILL ONGOING, WE WILL NEED TO MONITOR THE NEED FOR ANY KIND OF
FROST HEADLINES.
THE HIGH WILL INFLUENCE OUR WEATHER THROUGH AROUND WEDNESDAY, WHEN
IT STARTS TO SHIFT OFF TO THE SOUTH OF OUR AREA. A SURFACE LOW WILL
CROSS THE AREA LATE WEDNESDAY AND DRAG A COLD FRONT THROUGH
WEDNESDAY NIGHT OR THURSDAY. MEANWHILE, ANOTHER MID LEVEL TROUGH
WILL DIG DOWN ACROSS THE NORTHEASTERN UNITED STATES AND THE MODELS
SHOW A FAIRLY STRONG SHORTWAVE MOVING THROUGH THE FLOW AND CROSSING
OUR AREA LATE THURSDAY.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
WITH THE EXCEPTION OF KACY (WITH HAS MVFR CEILINGS ON ITS
DOORSTEP)...CONDITIONS ARE VFR AT THE TERMINAL LOCATIONS EARLY THIS
MORNING. HOWEVER...THAT IS EXPECTED TO CHANGE AS MVFR/IFR CONDITIONS
DEVELOP...MAINLY FROM TWO AREAS OF LOW CLOUDS.
THE FIRST AREA OF LOW CLOUDS EXTENDS FROM THE SOUTHERN POCONOS INTO
CENTRAL NEW JERSEY (ROUGHLY FROM KMPO TO NEAR KWRI). MOISTURE IS
SPREADING OUT UNDER A LOW INVERSION (NEAR 1000 FEET) IN THIS AREA.
BASED ON EXPANSION OF THE AREA...KABE...KTTN AND KPNE SHOULD BE
AFFECTED BEFORE 0800 UTC. KPHL...KILG AND KMIV SHOULD BE AFFECT
BETWEEN 0800 UTC AND 1000 UTC. THERE IS LESS CONFIDENCE CONCERNING
THE MVFR CEILINGS AT KPHL...AND TRENDS WILL NEED TO BE MONITORED.
THE LOW CLOUDS PROBABLY REMAIN IN PLACE THROUGH ABOUT 1300 TO 1440
UTC...WHEN THE DECK LIFTS INTO A VFR CEILINGS.
THE SECOND AREA OF LOW CLOUDS EXTENDS FROM THE SOUTHEAST NEW JERSEY
COAST OUT 85 NM SOUTHEAST OF KACY. THE GECOCAT LOW CLOUD PRODUCT
SUGGESTS THAT THIS AREA IS NOT GETTING MUCH BETTER ORGANIZED...BUT
MVFR/IFR CEILINGS ARE EXPECTED AT KACY THROUGH ABOUT 1400 UTC IN
ASSOCIATION WITH THIS AREA.
THE CLOUD DECKS SHOULD BREAK BY 1600 UTC...WITH VFR CONDITIONS
RETURNING. A LIGHT NORTHEAST WINDS SHOULD BECOME SOUTH THIS
AFTERNOON...WITH LOCAL SEA AND BAY BREEZES DEVELOPING.
THIS STARTS WITH VFR CONDITIONS...BUT AFTER 0600 UTC THE QUESTION
AGAIN BECOMES HOW MUCH MVFR/IFR STRATUS DEVELOPS? MODEL SOUNDINGS
SUGGEST THAT IFR CEILINGS DEVELOP BETWEEN 0600 AND 0900 UTC SATURDAY
AT MOST LOCATIONS...BUT IT IS UNCLEAR RIGHT NOW JUST HOW WIDESPREAD
THE LOW CLOUDS MIGHT GET. THE STRATUS LATE TONIGHT AND EARLY
SATURDAY MORNING WILL BE ADDRESSED WITH THE 1200 UTC TERMINAL
FORECAST ISSUANCE.
OUTLOOK...
SATURDAY AND SATURDAY NIGHT...VFR CONDITIONS TO START...THEN
BECOMING SUB-VFR IN SHOWERS AND THUNDERSTORMS DURING THE
AFTERNOON/EVENING AS A COLD FRONT CROSSES THE REGION.
SUNDAY THROUGH WEDNESDAY...THE COLD FRONT MOVES OFFSHORE EARLY ON
SUNDAY AND CONDITIONS SHOULD GRADUALLY IMPROVE TO VFR FROM WEST TO
EAST. HIGH PRESSURE THEN BUILDS IN KEEPING FAIRLY GOOD FLYING
CONDITIONS ACROSS THE TERMINALS.
&&
.MARINE...
WINDS ARE IN THE PROCESS OF SNAPPING BACK TO THE GENERAL NORTH TO
NORTHEAST SYNOPTIC FLOW. THE GRADIENT MAY TIGHTEN BRIEFLY THIS
MORNING AS THE HIGH OVER NORTHERN NEW ENGLAND REORGANIZES ITSELF.
THIS COULD ALLOW WINDS...ESPECIALLY OVER SOUTHERN OCEAN WATERS...TO
GET BACK CLOSER TO 12 OR 13 KNOTS FOR A TIME THROUGH MID MORNING.
SEAS ARE STILL CLOSE TO 4 FEET ACROSS THE NORTHERN OCEAN WATERS...
BUT THE WAVE WATCH MODEL SHOWS SEAS BACKING OFF LATER THIS MORNING.
THE GRADIENT BACKS OFF AGAIN BY LATE MORNING...ALLOW WINDS TO SHIFT
BACK TO FAVORED SEA AND BAY BREEZE CONFIGURATIONS. IN ANY EVENT...
WINDS THIS AFTERNOON SHOULD REMAIN LESS THAN 15 KNOTS.
THE GRADIENT SHOULD REMAIN LIGHT INTO THE EVENING HOURS...AS WINDS
REMAIN MORE SOUTHERLY THAN EASTERLY. THE LOW LEVEL INVERSION SETTING
UP LATER THIS EVENING AND OVERNIGHT SHOULD KEEP WINDS ASSOCIATED
WITH AN APPROACHING LOW LEVEL JET ABOVE THE SURFACE. BECAUSE OF
THIS...WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT
LEVELS INTO EARLY SATURDAY MORNING.
OUTLOOK...
A COLD FRONT WILL MOVE THROUGH SATURDAY NIGHT THROUGH EARLY SUNDAY,
BRINGING SHOWERS AND THUNDERSTORMS THROUGH THE AREA WATERS. THE
SOUTHERLY FLOW AHEAD OF THE FRONT WILL START TO BUILD SEAS AND WE
WILL SEE 5-6 FT SEAS BY SATURDAY EVENING ON THE OCEAN FRONT. AS THE
FRONT MOVES THROUGH, THE WINDS WILL TURN TO THE WEST AND BECOME
QUITE GUSTY, AROUND 25 KNOTS, WHICH WILL AID IN KEEPING THE SEAS AT
OR ABOVE 5 FEET THROUGH MUCH OF SUNDAY. SEAS SHOULD START TO SUBSIDE
BY LATE SUNDAY AFTERNOON OR EVENING.
HIGH PRESSURE BUILDS IN ON SUNDAY AND PERSISTS THROUGH THE MIDWEEK
PERIOD, KEEPING WINDS AND WAVES BELOW SMALL CRAFT ADVISORY CRITERIA.
&&
.TIDES/COASTAL FLOODING...
TIDES ARE RUNNING ABOUT ONE-HALF TO THREE-QUARTERS OF A FOOT ABOVE
PREDICTED EARLY THIS MORNING ON THE OCEAN FRONT. MOST PLACES ON THE
OCEAN FRONT WOULD NEED DEPARTURES CLOSE TO A FOOT TO GET CLOSE TO
THE MINOR TIDAL FLOODING BENCHMARK THIS AFTERNOON. BOTH THE MDL
EXTRATROPICAL SURGE GUIDANCE AND DBOFS BRING CAPE MAY CLOSE TO THE
MINOR TIDAL FLOODING BENCHMARK EARLY THIS AFTERNOON. IN ADDITION...
THE STEVENS INSTITUTE OF TECHNOLOGY CMS MODEL BRING LEWES DELAWARE
CLOSE FOR THE EARLY AFTERNOON HIGH TIDE.
FOR NOW...NO ACTION WILL BE TAKEN...AS IT WOULD APPEAR THAT ALL
OCEAN LOCATIONS WILL REMAIN BELOW THE THRESHOLD FOR THE EARLY
AFTERNOON HIGH TIDE CYCLE.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MEOLA
NEAR TERM...HAYES
SHORT TERM...HAYES
LONG TERM...MEOLA
AVIATION...HAYES/MEOLA
MARINE...HAYES/MEOLA
TIDES/COASTAL FLOODING...HAYES
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
326 AM EDT FRI SEP 21 2012
.SYNOPSIS...
HIGH PRESSURE LOCATED OFF TO OUR NORTHEAST WILL WEAKEN TODAY.
MEANWHILE, A COLD FRONT WILL APPROACH FROM THE WEST AND CROSS THE
REGION ON SATURDAY. HIGH PRESSURE BUILDS IN FROM THE WEST ON SUNDAY
AND PERSISTS THROUGH MIDWEEK. ANOTHER COLD FRONT WILL MOVE THROUGH
THE AREA LATE WEDNESDAY OR THURSDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THERE ARE A COUPLE OF ISSUES THAT NEED ATTENTION IN THE EARLY
MORNING PORTION OF THE FORECAST.
FIRST IS THE LOW CLOUDS. A BANK OF LOW CLOUDINESS HAS DEVELOPED
ACROSS THE SOUTHERN POCONOS AND PARTS OF SUSSEX COUNTY NEW JERSEY.
THE AREA HAS EXPANDED CONSIDERABLY DURING THE OVERNIGHT HOURS...AND
THE LOWER CLOUDS PROBABLY SPREAD INTO THE LEHIGH VALLEY AND
NORTHWEST NEW JERSEY BEFORE DAYBREAK.
THERE IS ALSO THE POTENTIAL FOR LOW CLOUDS TO AFFECT PORTIONS OF NEW
JERSEY AND DELAWARE. THE LOW CLOUD PRODUCT IS SHOWING CLOUDINESS
ABOUT 85 MILES SOUTHEAST OF KACY. WHILE THE AREA HAS NOT GOTTEN ANY
BETTER ORGANIZED...THE LOW LEVEL EAST SOUTHEAST FLOW WOULD BRING
THESE CLOUDS TO THE NEW JERSEY COAST BEFORE DAYBREAK.
THE NEXT PROBLEM IS THE POTENTIAL FOR LIGHT SHOWER ACTIVITY ACROSS
PORTIONS OF EASTERN NEW JERSEY. KDIX IS SHOWING SOME LIGHT RETURNS
(GENERALLY LESS THAN 10 DBZ) MOVING WEST TOWARD THE CAPE MAY
COAST. AN AREA OF MORE SUBSTANTIAL SHOWERS IS MOVING NORTH ABOUT
85 TO 90 MILES SOUTHEAST OF KACY. THE LATEST HRRR AND 0000 UTC NAM
SUGGEST THAT SOME OF THIS ACTIVITY WILL AFFECT EASTERN NEW JERSEY
(MAINLY FROM OCEAN COUNTY SOUTH TO CAPE MAY COUNTY) BEFORE
DAYBREAK.
NAM MODEL SOUNDINGS (WHICH ARE BETTER CAPTURING THE MOISTURE
SPREADING OUT UNDER THE LOW INVERSION) SUGGEST THE LOW CLOUDS BREAK
BETWEEN 1300 AND 1500 UTC. TIMING MAY BE AN ISSUE SINCE THE SUN
ANGLE IS GETTING LOWER...BUT THE CLOUDS MAY END UP HANGING ON THE
LONGEST CLOSER TO THE NEW JERSEY COAST. AFTER THE CLOUDS BREAK...
SCATTERED CUMULUS COULD REMAIN...ESPECIALLY ACROSS NORTHWEST ZONES.
THE SCATTERED SHOWERS (AND EMBEDDED THUNDER) ASSOCIATED WITH THE
WARM FRONT AND MID LEVEL SHORT WAVE OVER THE GREAT LAKES SHOULD PASS
TO THE NORTHWEST OF THE AREA THIS AFTERNOON. FOR NOW...THE NORTHWEST
ZONES WILL REMAIN DRY FOR THIS AFTERNOON...BUT TRENDS ON HOW THE
PRECIPITATION EVOLVES TO THE WEST MAY NEED TO BE MONITORED.
850 MB TEMPERATURES SUGGEST HIGHS IN THE IN THE MID TO UPPER 70S
OUTSIDE OF THE INFLUENCE OF TERRAIN AND THE WATERS. THIS IS CLOSE TO
THE MOS MEAN...AND IS ACCEPTED.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
THE FORECAST PROBLEM FOR TONIGHT WILL AGAIN BE SKY COVER. THE LOW
LEVEL FLOW LOOKS TO REMAIN MORE SOUTHERLY TONIGHT (AS OPPOSED TO
SOME VARIATION OF EAST). THE LOW LEVEL WIND DIRECTION CHANGE WOULD
IMPLY THAT THE LOWER LEVELS WOULD NOT BE AS MOIST...NOR WOULD THE
LOW LEVEL INVERSION BE AS PRONOUNCED. HOWEVER...WARM AIR ADVECTION
ON THE NOSE OF THE LOW LEVEL JET MAY ALLOW THE INVERSION TO
LOWER...AND THIS PRESENTS THE POTENTIAL FOR LOWER CLOUDS TO MOVE
BACK IN AFTER MIDNIGHT.
MODEL SOUNDINGS ARE LESS BULLISH ON THE THREAT FOR LOWER CLOUDS...
WITH THE GFS EVEN LESS SO. BASED ON THIS...WILL NOT HIT THE LOWER
CLOUDS TOO HARD TONIGHT...BUT THIS MAY NEED TO BE REVISITED.
SHOWERS SHOULD DEVELOP ON THE NOSE OF THE LOW LEVEL JET. THE MODEL
CONSENSUS IS TO TAKE THE WARM AIR ADVECTION DEVELOPING OVER THE
LOWER OHIO VALLEY THIS MORNING INTO NORTHEAST PENNSYLVANIA AFTER
0600 UTC. FURTHER SOUTH AND EAST...THE LIFT GENERATED BY THE WARM
AIR ADVECTION SHOULD BE INSUFFICIENT FOR SHOWER GENERATION...AND THE
REMAINDER OF THE FORECAST AREA SHOULD REMAIN DRY TONIGHT.
THE AIRMASS CONTINUES TO SLOWLY WARM FROM WITHIN. THIS WOULD SUGGEST
THAT LOW WOULD BE CLOSER TO A MOS BLEND THAN THE COOLER GFS MOS
NUMBERS.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
THE MID LEVEL TROUGH ACROSS THE UPPER MIDWEST, CONTINUES TO DEEPEN
ON SATURDAY AS IT BECOMES MORE OF A CLOSED LOW. A STRONG SHORTWAVE
WILL ROTATE THROUGH THE BASE OF THE TROUGH SATURDAY EVENING. ONE THE
SHORTWAVE ROTATES THROUGH THE MID LEVEL FLOW, THE TROUGH STARTS TO
WEAKEN A BIT AND LIFT NORTH. WHILE THE MAIN MID LEVEL LOW SHOULD BE
WELL NORTH OF THE REGION BY MONDAY, ANOTHER STRONG SHORTWAVE WILL
ROTATE THROUGH THE FLOW AND ACROSS OUR REGION ON MONDAY.
AT THE SURFACE, THE COLD FRONT WILL PUSH ACROSS PENNSYLVANIA DURING
THE DAY SATURDAY AND THEN START TO MOVE THROUGH OUR AREA MAINLY LATE
SATURDAY AFTERNOON THROUGH SATURDAY NIGHT, EXITING OFF THE COAST BY
EARLY SUNDAY MORNING. OUT AHEAD OF THE FRONT, WE SHOULD SEE SOME
DECENT WARM AIR ADVECTION TAKE PLACE AND INCREASE IN MOISTURE AS THE
SURFACE FLOW WILL BE PREDOMINATELY OUT OF THE SOUTH.
WHILE THE STORM PREDICTION CENTER HAS US IN A SLIGHT RISK FOR SEVERE
WEATHER, THE SET UP IS NOT LOOKING ALL THAT PROMISING FOR A
WIDESPREAD KIND OF EVENT. THE UPPER LEVEL JET IS CENTERED PRETTY FAR
OFF TO OUR NORTHWEST AND BETTER SITUATED WITH THE STRONG MID LEVEL
SHORTWAVE. SHEAR IS DECENT BUT STILL REMAINS BEST OFF TO OUR NORTH.
PLENTY OF MOISTURE WILL BE AVAILABLE AS PWATS GENERALLY FALL INTO
THE 1.5-2.0 INCH RANGE, WHICH IS WELL ABOVE NORMAL FOR MID TO LATE
SEPTEMBER, AND DEWPOINTS SHOULD HAVE NO PROBLEM RISING BACK UP INTO
60S. SO WE WILL NEED TO KEEP AN EYE ON HEAVY RAIN AND ANY POTENTIAL
FLOODING ISSUES THAT MAY ARISE FROM THAT. TIME OF DAY MAY PLAY A BIG
ROLE IN JUST HOW MUCH ACTION WE SEE AHEAD OF AND ALONG THE FRONT.
WITH TEMPERATURES EXPECTED TO RISE INTO THE 80S ACROSS NEARLY THE
ENTIRE REGION, WE COULD GET ENOUGH SURFACE HEATING TO CONTRIBUTE TO
THE SEVERE THREAT. THE LIMITING FACTOR ON THE SURFACE HEATING MAY
ACTUALLY BE THE CLOUD COVER. WARM MOIST AIR WILL CONTRIBUTE TO THE
RISING TEMPERATURES AND DEWPOINTS BUT CLOUD COVER MAY END UP
LIMITING THE CONVECTIVE DEVELOPMENT.
AS THE FRONT MOVES OFFSHORE EARLY SUNDAY MORNING, WE WILL SEE A
DRYING TREND DEVELOP AS A LARGE AREA OF HIGH PRESSURE BUILDS ACROSS
THE MID-ATLANTIC REGION. SOME MUCH COLDER AIR WILL MAKES IT WAY INTO
OUR REGION THROUGH THE DAY ON SUNDAY. MAXIMUM TEMPERATURES WILL BE
IN THE UPPER 60S TO LOWER 70S. THE GUIDANCE EVEN INDICATES THAT
TEMPERATURES MAY STRUGGLE TO REACH 70 THROUGH THE DAY. WITH THE
COOLER AIR IN PLACE AND CLEARING SKIES WE SHOULD RADIATE EXTREMELY
WELL SUNDAY NIGHT. TEMPERATURES WILL FALL INTO THE 40S, MAY STAY
CLOSER TO 50 IN THE MORE URBAN AREAS, AND TEMPERATURES ACROSS THE
NORTHERN ZONES MAY ACTUALLY FALL INTO THE MIDDLE TO UPPER 30S! WE
COULD SEE SOME FRONT DEVELOP ACROSS THE NORTHERN AREAS AND WE HAVE
ADDED PATCHY FROST INTO THE FORECAST FOR NOW. AS THE GROWING SEASON
IS STILL ONGOING, WE WILL NEED TO MONITOR THE NEED FOR ANY KIND OF
FROST HEADLINES.
THE HIGH WILL INFLUENCE OUR WEATHER THROUGH AROUND WEDNESDAY, WHEN
IT STARTS TO SHIFT OFF TO THE SOUTH OF OUR AREA. A SURFACE LOW WILL
CROSS THE AREA LATE WEDNESDAY AND DRAG A COLD FRONT THROUGH
WEDNESDAY NIGHT OR THURSDAY. MEANWHILE, ANOTHER MID LEVEL TROUGH
WILL DIG DOWN ACROSS THE NORTHEASTERN UNITED STATES AND THE MODELS
SHOW A FAIRLY STRONG SHORTWAVE MOVING THROUGH THE FLOW AND CROSSING
OUR AREA LATE THURSDAY.
&&
.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
WITH THE EXCEPTION OF KACY (WITH HAS MVFR CEILINGS ON ITS
DOORSTEP)...CONDITIONS ARE VFR AT THE TERMINAL LOCATIONS EARLY THIS
MORNING. HOWEVER...THAT IS EXPECTED TO CHANGE AS MVFR/IFR CONDITIONS
DEVELOP...MAINLY FROM TWO AREAS OF LOW CLOUDS.
THE FIRST AREA OF LOW CLOUDS EXTENDS FROM THE SOUTHERN POCONOS INTO
CENTRAL NEW JERSEY (ROUGHLY FROM KMPO TO NEAR KWRI). MOISTURE IS
SPREADING OUT UNDER A LOW INVERSION (NEAR 1000 FEET) IN THIS AREA.
BASED ON EXPANSION OF THE AREA...KABE...KTTN AND KPNE SHOULD BE
AFFECTED BEFORE 0800 UTC. KPHL...KILG AND KMIV SHOULD BE AFFECT
BETWEEN 0800 UTC AND 1000 UTC. THERE IS LESS CONFIDENCE CONCERNING
THE MVFR CEILINGS AT KPHL...AND TRENDS WILL NEED TO BE MONITORED.
THE LOW CLOUDS PROBABLY REMAIN IN PLACE THROUGH ABOUT 1300 TO 1440
UTC...WHEN THE DECK LIFTS INTO A VFR CEILINGS.
THE SECOND AREA OF LOW CLOUDS EXTENDS FROM THE SOUTHEAST NEW JERSEY
COAST OUT 85 NM SOUTHEAST OF KACY. THE GECOCAT LOW CLOUD PRODUCT
SUGGESTS THAT THIS AREA IS NOT GETTING MUCH BETTER ORGANIZED...BUT
MVFR/IFR CEILINGS ARE EXPECTED AT KACY THROUGH ABOUT 1400 UTC IN
ASSOCIATION WITH THIS AREA.
THE CLOUD DECKS SHOULD BREAK BY 1600 UTC...WITH VFR CONDITIONS
RETURNING. A LIGHT NORTHEAST WINDS SHOULD BECOME SOUTH THIS
AFTERNOON...WITH LOCAL SEA AND BAY BREEZES DEVELOPING.
THIS STARTS WITH VFR CONDITIONS...BUT AFTER 0600 UTC THE QUESTION
AGAIN BECOMES HOW MUCH MVFR/IFR STRATUS DEVELOPS? MODEL SOUNDINGS
SUGGEST THAT IFR CEILINGS DEVELOP BETWEEN 0600 AND 0900 UTC SATURDAY
AT MOST LOCATIONS...BUT IT IS UNCLEAR RIGHT NOW JUST HOW WIDESPREAD
THE LOW CLOUDS MIGHT GET. THE STRATUS LATE TONIGHT AND EARLY
SATURDAY MORNING WILL BE ADDRESSED WITH THE 1200 UTC TERMINAL
FORECAST ISSUANCE.
OUTLOOK...
SATURDAY AND SATURDAY NIGHT...VFR CONDITIONS TO START...THEN
BECOMING SUB-VFR IN SHOWERS AND THUNDERSTORMS DURING THE
AFTERNOON/EVENING AS A COLD FRONT CROSSES THE REGION.
SUNDAY THROUGH WEDNESDAY...THE COLD FRONT MOVES OFFSHORE EARLY ON
SUNDAY AND CONDITIONS SHOULD GRADUALLY IMPROVE TO VFR FROM WEST TO
EAST. HIGH PRESSURE THEN BUILDS IN KEEPING FAIRLY GOOD FLYING
CONDITIONS ACROSS THE TERMINALS.
&&
.MARINE...
WINDS ARE IN THE PROCESS OF SNAPPING BACK TO THE GENERAL NORTH TO
NORTHEAST SYNOPTIC FLOW. THE GRADIENT MAY TIGHTEN BRIEFLY THIS
MORNING AS THE HIGH OVER NORTHERN NEW ENGLAND REORGANIZES ITSELF.
THIS COULD ALLOW WINDS...ESPECIALLY OVER SOUTHERN OCEAN WATERS...TO
GET BACK CLOSER TO 12 OR 13 KNOTS FOR A TIME THROUGH MID MORNING.
SEAS ARE STILL CLOSE TO 4 FEET ACROSS THE NORTHERN OCEAN WATERS...
BUT THE WAVE WATCH MODEL SHOWS SEAS BACKING OFF LATER THIS MORNING.
THE GRADIENT BACKS OFF AGAIN BY LATE MORNING...ALLOW WINDS TO SHIFT
BACK TO FAVORED SEA AND BAY BREEZE CONFIGURATIONS. IN ANY EVENT...
WINDS THIS AFTERNOON SHOULD REMAIN LESS THAN 15 KNOTS.
THE GRADIENT SHOULD REMAIN LIGHT INTO THE EVENING HOURS...AS WINDS
REMAIN MORE SOUTHERLY THAN EASTERLY. THE LOW LEVEL INVERSION SETTING
UP LATER THIS EVENING AND OVERNIGHT SHOULD KEEP WINDS ASSOCIATED
WITH AN APPROACHING LOW LEVEL JET ABOVE THE SURFACE. BECAUSE OF
THIS...WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT
LEVELS INTO EARLY SATURDAY MORNING.
OUTLOOK...
A COLD FRONT WILL MOVE THROUGH SATURDAY NIGHT THROUGH EARLY SUNDAY,
BRINGING SHOWERS AND THUNDERSTORMS THROUGH THE AREA WATERS. THE
SOUTHERLY FLOW AHEAD OF THE FRONT WILL START TO BUILD SEAS AND WE
WILL SEE 5-6 FT SEAS BY SATURDAY EVENING ON THE OCEAN FRONT. AS THE
FRONT MOVES THROUGH, THE WINDS WILL TURN TO THE WEST AND BECOME
QUITE GUSTY, AROUND 25 KNOTS, WHICH WILL AID IN KEEPING THE SEAS AT
OR ABOVE 5 FEET THROUGH MUCH OF SUNDAY. SEAS SHOULD START TO SUBSIDE
BY LATE SUNDAY AFTERNOON OR EVENING.
HIGH PRESSURE BUILDS IN ON SUNDAY AND PERSISTS THROUGH THE MIDWEEK
PERIOD, KEEPING WINDS AND WAVES BELOW SMALL CRAFT ADVISORY CRITERIA.
&&
.TIDES/COASTAL FLOODING...
TIDES ARE RUNNING ABOUT ONE-HALF TO THREE-QUARTERS OF A FOOT ABOVE
PREDICTED EARLY THIS MORNING ON THE OCEAN FRONT. MOST PLACES ON THE
OCEAN FRONT WOULD NEED DEPARTURES CLOSE TO A FOOT TO GET CLOSE TO
THE MINOR TIDAL FLOODING BENCHMARK THIS AFTERNOON. BOTH THE MDL
EXTRATROPICAL SURGE GUIDANCE AND DBOFS BRING CAPE MAY CLOSE TO THE
MINOR TIDAL FLOODING BENCHMARK EARLY THIS AFTERNOON. IN ADDITION...
THE STEVENS INSTITUTE OF TECHNOLOGY CMS MODEL BRING LEWES DELAWARE
CLOSE FOR THE EARLY AFTERNOON HIGH TIDE.
FOR NOW...NO ACTION WILL BE TAKEN...AS IT WOULD APPEAR THAT ALL
OCEAN LOCATIONS WILL REMAIN BELOW THE THRESHOLD FOR THE EARLY
AFTERNOON HIGH TIDE CYCLE.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MEOLA
NEAR TERM...HAYES
SHORT TERM...HAYES
LONG TERM...MEOLA
AVIATION...HAYES/MEOLA
MARINE...HAYES/MEOLA
TIDES/COASTAL FLOODING...HAYES
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
119 AM EDT FRI SEP 21 2012
.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO MOVE NORTHEASTWARD TONIGHT AND
WEAKEN ON FRIDAY. THEN, A COLD FRONT WILL APPROACH FROM THE WEST
AND CROSS THE REGION ON SATURDAY NIGHT. HIGH PRESSURE WILL THEN
BUILD IN FROM THE WEST AND REMAIN OVER THE AREA THROUGH MIDWEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
NO SIGNIFICANT CHANGES TO THE FORECAST WITH THE UPDATE...BUT THERE
ARE A COUPLE OF THINGS TO WATCH FOR THE OVERNIGHT.
FIRST IS THE LOW CLOUDS. A BANK OF LOW CLOUDINESS HAS DEVELOPED
ACROSS THE SOUTHERN POCONOS AND PARTS OF SUSSEX COUNTY NEW JERSEY.
THE AREA HAS EXPANDED CONSIDERABLY IN THE PAST TWO HOURS...AND THE
LOWER CLOUDS PROBABLY SPREAD INTO THE LEHIGH VALLEY AND NORTHWEST
NEW JERSEY DURING THE NEXT 2 OR 3 HOURS.
THERE IS ALSO THE POTENTIAL FOR LOW CLOUDS TO AFFECT PORTIONS OF
NEW JERSEY AND DELAWARE DURING THE EARLY MORNING HOURS. THE LOW
CLOUD PRODUCT IS SHOWING CLOUDINESS ABOUT 85 MILES SOUTHEAST OF
KACY. WHILE THE AREA HAS NOT GOTTEN ANY BETTER ORGANIZED...THE LOW
LEVEL EAST SOUTHEAST FLOW WOULD BRING THESE CLOUDS TO THE NEW
JERSEY COAST AFTER 0600 UTC. THE FORECAST ALREADY INCLUDES THE
MENTION OF CLOUDS THERE...SO THIS ASPECT OF THE FORECAST IS
COVERED WELL.
THE NEXT PROBLEM IS THE POTENTIAL FOR LIGHT SHOWER ACTIVITY ACROSS
PORTIONS OF EASTERN NEW JERSEY. KDIX IS SHOWING SOME LIGHT RETURNS
(GENERALLY LESS THAN 10 DBZ) MOVING WEST TOWARD THE CAPE MAY
COAST. AN AREA OF MORE SUBSTANTIAL SHOWERS IS MOVING NORTH ABOUT
85 TO 90 MILES SOUTHEAST OF KACY. THE LATEST HRRR AND 0000 UTC NAM
SUGGEST THAT SOME OF THIS ACTIVITY WILL AFFECT EASTERN NEW JERSEY
(MAINLY FROM OCEAN COUNTY SOUTH TO CAPE MAY COUNTY) BEFORE
DAYBREAK.
THE ACTIVITY OUT THERE NOW LENDS SOME CREDENCE TO THE HRRR AND
NAM SOLUTIONS...AND A SLIGHT CHANCE OF SHOWERS WILL BE INCLUDED IN
THE ABOVEMENTIONED AREAS. TRENDS WILL BE FOLLOWED IN THE EVENT THE
SHOWERS BECOME MORE WIDESPREAD.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THIS EVENING/...
THE EXTENT OF MORNING LOW CLOUDS WILL BE THE MAIN CONCERN FRIDAY,
BUT THE MODELS INDICATE SUFFICIENT MIXING TO OCCUR BY MID-MORNING,
WITH LOW CLOUDS DISSIPATING. THE REMAINDER OF FRIDAY WILL FEATURE
FAIR WEATHER WITH MIXED SUN AND CLOUDS AS WEAKENING HIGH PRESSURE
REMAINS TO OUR NORTHEAST. A SOUTHERLY TO SOUTHEASTERLY FLOW WILL
DEVELOP THROUGH THE DAY AHEAD OF AN APPROACHING COLD FRONT FROM
THE GREAT LAKES AND OHIO VALLEY REGION. THIS FLOW WILL BRING
WARMER, MOISTER AIR TO THE REGION, AND MAXIMUM TEMPERATURES ARE
EXPECTED TO BE A FEW DEGREES WARMER THAN ON THURSDAY. OVERALL, A
BLEND OF CONTINUITY WITH STAT GUIDANCE WAS USED FOR TEMPERATURES.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
THE PD BEGINS WITH WK HIGH PRESSURE TO THE NE. THEN A CDFNT OVER
THE MIDWEST WILL APPROACH AND CROSS THE REGION LATER SATURDAY INTO
SATURDAY NIGHT. MDLS CONTINUE TO KEEP MOST OF THE PRECIP TO OUR W
UNTIL LATE AFTN AT THE EARLIEST AND THE BULK OF THE PRECIP DOES
NOT OCCUR UNTIL EVENING. THERE IS STILL SOME DISAGREEMENT WITHIN
THE MDLS AS TO THE ACTUAL TIMING OF THE FRONT, BUT AT LEAST THE
FIRST HALF OF SATURDAY SHOULD BE NICE AND LIKELY MORE. WHEN THE
FRONT CROSSES THE REGIONS, IT WILL BE ACCOMPANIED BY SHRA AND SOME
TSRA BUT TIME OF DAY COULD HAVE AN IMPACT ON WHAT OCCURS AND
SEVERE POTENTIAL, BUT THE POSSIBILITY EXISTS FOR SOME HVY RAIN.
STRONG HIGH PRESSURE THEN BUILDS IN FROM THE MIDDLE OF THE COUNTRY
FOR THE FIRST PART OF NEXT WEEK. ANOTHER CDFNT COULD APPROACH
AROUND WEDNESDAY. TEMPS WILL START OUT ABOVE NRML ON SAT, THEN
WILL DROP BELOW NRML FOR THE FIRST FEW FULL DAYS OF FALL (THE
AUTUMNAL EQUINOX IS SATURDAY AT 1049 AM).
&&
.AVIATION /05Z FRIDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
WITH THE EXCEPTION OF KACY (WITH HAS MVFR CEILINGS ON ITS
DOORSTEP)...CONDITIONS ARE VFR AT THE TERMINAL LOCATIONS EARLY THIS
MORNING. HOWEVER...THAT IS EXPECTED TO CHANGE AS MVFR/IFR CONDITIONS
DEVELOP...MAINLY FROM TWO AREAS OF LOW CLOUDS.
THE FIRST AREA OF LOW CLOUDS EXTENDS FROM THE SOUTHERN POCONOS INTO
CENTRAL NEW JERSEY (ROUGHLY FROM KMPO TO NEAR KWRI). MOISTURE IS
SPREADING OUT UNDER A LOW INVERSION (NEAR 1000 FEET) IN THIS AREA.
BASED ON EXPANSION OF THE AREA...KABE...KTTN AND KPNE SHOULD BE
AFFECTED BEFORE 0800 UTC. KPHL...KILG AND KMIV SHOULD BE AFFECT
BETWEEN 0800 UTC AND 1000 UTC. THERE IS LESS CONFIDENCE CONCERNING
THE MVFR CEILINGS AT KPHL...AND TRENDS WILL NEED TO BE MONITORED.
THE LOW CLOUDS PROBABLY REMAIN IN PLACE THROUGH ABOUT 1300 TO 1440
UTC...WHEN THE DECK LIFTS INTO A VFR CEILINGS.
THE SECOND AREA OF LOW CLOUDS EXTENDS FROM THE SOUTHEAST NEW JERSEY
COAST OUT 85 NM SOUTHEAST OF KACY. THE GECOCAT LOW CLOUD PRODUCT
SUGGESTS THAT THIS AREA IS NOT GETTING MUCH BETTER ORGANIZED...BUT
MVFR/IFR CEILINGS ARE EXPECTED AT KACY THROUGH ABOUT 1400 UTC IN
ASSOCIATION WITH THIS AREA.
THE CLOUD DECKS SHOULD BREAK BY 1600 UTC...WITH VFR CONDITIONS
RETURNING. A LIGHT NORTHEAST WINDS SHOULD BECOME SOUTH THIS
AFTERNOON...WITH LOCAL SEA AND BAY BREEZES DEVELOPING.
THIS STARTS WITH VFR CONDITIONS...BUT AFTER 0600 UTC THE QUESTION
AGAIN BECOMES HOW MUCH MVFR/IFR STRATUS DEVELOPS? MODEL SOUNDINGS
SUGGEST THAT IFR CEILINGS DEVELOP BETWEEN 0600 AND 0900 UTC SATURDAY
AT MOST LOCATIONS...BUT IT IS UNCLEAR RIGHT NOW JUST HOW WIDESPREAD
THE LOW CLOUDS MIGHT GET. THE STRATUS LATE TONIGHT AND EARLY
SATURDAY MORNING WILL BE ADDRESSED WITH THE 1200 UTC TERMINAL
FORECAST ISSUANCE.
OUTLOOK...
SATURDAY THROUGH SATURDAY NIGHT...VFR CONDITIONS TO START...THEN
BECOMING SUB-VFR IN SHOWERS AND THUNDERSTORMS IN THE AFTERNOON/EVENING
AS A COLD FRONT CROSSES THE REGION.
SUNDAY THROUGH TUESDAY...THE COLD FRONT MOVES OFFSHORE EARLY ON
SUNDAY AND CONDITIONS WILL IMPROVE TO VFR FROM WEST TO EAST. HIGH
PRESSURE THEN BUILDS IN KEEPING GOOD FLYING CONDITIONS ACROSS
REGION.
&&
.MARINE...
GENERALLY SUB-ADVISORY CONDITIONS ARE EXPECTED ON THE WATERS
TONIGHT AND THROUGH FRIDAY. THROUGH EARLY EVENING, A FEW WIND
GUSTS APPROACHING 20 KNOTS AND SEAS APPROACHING 5 FEET ARE
POSSIBLE FOR OUR NORTHERN COASTAL WATERS, BUT OTHERWISE, WINDS
WILL PRIMARILY BE IN THE 10 TO 15 KNOT RANGE. SEAS OF 3 TO 4 FEET
ARE EXPECTED FOR THE COASTAL WATERS TONIGHT THROUGH FRIDAY, WITH 1
TO 2 FOOT SEAS FOR DELAWARE BAY.
OUTLOOK...
HIGH PRESSURE WILL START THE OUTLOOK PD WITH RATHER CALM CONDS ON
THE AREA WATERS, BUT A COLD FRONT WILL MOVE ACROSS THE AREA WATERS
SATURDAY NIGHT INTO EARLY SUNDAY. THE SOUTHERLY FLOW AHEAD OF THE
FRONT WILL START TO BUILD SEAS AND WE COULD SEE 5-6 FT SEAS BY
SATURDAY EVENING ON THE OCEAN FRONT. AS THE FRONT MOVES BY, THE
WINDS BECOME WESTERLY AND GUSTY KEEPING THE SEAS AT OR ABOVE 5
FEET THROUGH MUCH OF SUNDAY. SEAS SHOULD START TO SUBSIDE BY LATE
SUNDAY AFTERNOON OR EVENING. SCA FLAGS WILL LIKELY BE NEEDED FOR A
PORTION OF SAT INTO SUN.
HIGH PRESSURE BUILDS IN THE START OF THE WEEK WITH SUB-ADVISORY
CONDITIONS EXPECTED.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...NIERENBERG
NEAR TERM...HAYES
SHORT TERM...KLINE
LONG TERM...NIERENBERG
AVIATION...HAYES/NIERENBERG
MARINE...KLINE/NIERENBERG
AREA FORECAST DISCUSSION
NWS MIAMI FL
928 PM EDT SAT SEP 22 2012
.UPDATE...
ALL THE URBAN FLOOD ADVISORIES ISSUED EARLIER IN THE EVENING HAVE
BEEN DROPPED.. LATEST RADAR RETURNS INDICATE JUST LIGHT TO
MODERATE SHOWERS ACROSS THE CWA.
THE SHORT TERM FORECAST WAS UPDATED TO REFLECT THE LACK OF
CONVECTION CURRENTLY ACROSS THE REGION. HOWEVER...LATEST GUIDANCE
AND WATER VAPOR IMAGERY INDICATED AN UPPER LEVEL SHORT WAVE TROUGH
ENTERING THE EASTERN GULF THAT COULD TRIGGER ANOTHER ROUND OF
CONVECTION DURING THE EARLY MORNING HOURS ON SUNDAY. THE OOZ SOUNDING
INDICATED CONSIDERABLE MOISTURE LINGERING ACROSS THE AREA WITH THE
PWAT NEAR 2.4 INCHES WITH WESTERLY FLOW THROUGH MOST OF THE
ATMOSPHERE. THE RECENT GUIDANCE ALSO INDICATED THE POTENTIAL FOR
ADDITIONAL CONVECTION OVER NIGHT. SO FOR THE REMAINING EVENING
HOURS JUST ISOLATED TO SCATTERED SHOWERS AND AN OCCASIONAL
THUNDERSTORM IS FORECAST WITH GREATER COVERAGE AND AN INCREASE IN
POTENTIAL FOR SHOWERS AND THUNDERSTORMS EXPECTED DURING THE EARLY
MORNING HOURS ON SUNDAY.
60
&&
.PREV DISCUSSION... /ISSUED 759 PM EDT SAT SEP 22 2012/
AVIATION...AREAS OF LIGHT RAIN ACROSS THE EAST COAST WILL
DIMINISH. HOWEVER, ADDITIONAL SHOWERS ARE POSSIBLE
OVERNIGHT...ESPECIALLY TOWARDS DAWN SUNDAY. THERE IS THE POTENTIAL
FOR THUNDERSTORMS AS WELL. MAINTAINED VCSH OVERNIGHT WITH PROB30
OF MVFR CONDITIONS ALL EAST COAST SITES BEGINNING SUN MORNING AND
INTO EARLY AFTERNOON. IFR WILL AGAIN BE POSSIBLE AT TIMES IN HEAVY
RAIN.
PREV DISCUSSION... /ISSUED 234 PM EDT SAT SEP 22 2012/
SHORT TERM (TONIGHT-MONDAY NIGHT)... AFTER A BUSY START TO THE
DAY THIS MORNING DUE TO FLOODING ALONG THE EAST COAST FROM MIAMI-
DADE TO PALM BEACH...THE LATEST HRRR MODEL REFLECTIVITIES HAVE
INITIALIZED WELL WITH THE CURRENT PATTERN AND CONTINUE TO INDICATE
ANOTHER ROUND OF ACTIVITY REDEVELOPING THROUGH THE MID TO LATE
AFTERNOON AND EVENING PERIODS. FOR COVERAGE...IT IS INDICATING THE
BULK OF THE HEAVIEST ACTIVITY SETTING UP OVER THE SOUTHERN HALF OF
THE LOCAL AREA WITH ANOTHER 1-2 INCHES OF RAINFALL POSSIBLE IN THE
HEAVIEST ACTIVITY. THIS SEEMS REASONABLE AS THE LATEST VISIBLE
SATELLITE IMAGERY SHOWS THE LARGEST BREAKS IN CLOUD COVERAGE OVER
THESE SOUTHERN AREAS WHERE TEMPERATURES HAVE QUICKLY INCREASED
OVER THE PAST 1-2 HRS. AS A RESULT...FLOODING REMAINS THE MAIN
CONCERN INTO THE EVENING HOURS. IF THIS ACTIVITY SETS UP OVER THE
SAME AREAS AS THIS MORNING WHERE 2-4 INCHES WERE RECORDED...MAINLY
FROM AROUND JUST SE OF CUTLER BAY TO NORTH MIAMI BEACH...FLASH
FLOODING CANNOT BE RULED OUT.
TONIGHT THROUGH SUNDAY NIGHT...THE COLD FRONT ENTERING THE REGION
FROM THE NORTH IS PROGGED TO CONTINUE SOUTH INTO NORTHERN AND
CENTRAL FLORIDA THROUGH THE FIRST HALF OF THE DAY SUNDAY FOLLOWED BY
A SURGE OF MUCH DRIER AIR BEFORE STALLING. UNFORTUNATELY...THE DEEP
LAY MOISTURE AXIS WITH AROUND 2" PWAT VALUES EXTENDING FROM NE TO SW
ACROSS THE AREA WILL REMAIN IN PLACE THROUGH SUNDAY WITH ONLY SOME
DRYING POSSIBLE ACROSS THE NORTHERN HALF OR THE LAKE REGION BY
TOMORROW NIGHT. THIS COMBINED WITH WEAK UPPER PULSES OF ENERGY
TRANSLATING NORTHEAST AHEAD OF THE BROAD UPPER TROUGH JUST WEST OF
THE AREA WILL KEEP THE RAIN AND FLOOD CHANCES AS THE PRIMARY
CONCERNS THROUGH SUNDAY. ADDITIONAL RAINFALL ACCUMULATIONS COULD
REACH THE 1 TO 3 INCH RANGE WITH LOCALIZED HIGHER AMOUNTS
POSSIBLE.
MONDAY AND MONDAY NIGHT...THE LATEST NUMERICAL GUIDANCE REMAINS IN
DECENT AGREEMENT AND INDICATES THE BROAD UPPER TROUGH OVER THE
EASTERN STATES SHIFTING EAST AND THE MUCH DRIER AIR THAT WAS
PREVIOUSLY DISCUSSED SHIFTING FARTHER SOUTH INTO OUR AREA IN THE
WAKE OF THE FRONTAL BOUNDARY. AS A RESULT...DRY AIR WITH LOWER
RAINFALL CHANCES CAN BE ANTICIPATED.
LONG TERM...(TUESDAY-FRIDAY)
THE UPPER RIDGE OVER THE ROCKIES BEGINS TO BREAK DOWN AS AN UPPER
LOW MOVES FROM THE PACIFIC NORTHWEST TOWARD THE CENTRAL ROCKIES.
THIS SHOVES THE E U.S. TROUGH NE WITH THE COLD FRONT STALLED N OF
LAKE OKEECHOBEE. THIS DRIES THE ATMOSPHERE SOMEWHAT FROM THE N TO
S ACROSS FLA BUT LONG RANGE MODELS STILL APPEAR TO DEVELOP AN
UPPER LOW OVER THE GULF AND WITH THE SW FLOW MAY KEEP AMPLE
ATMOSPHERIC MOISTURE OVER THE AREA. PLUS...ANOTHER TROPICAL WAVE
MAY NEAR THE AREA MIDWEEK NEXT WEEK. AT HIS TIME...WILL STAY WITH
GUIDANCE.
MARINE...
RAIN CHANCES WILL REMAIN UP ACROSS THE MARINE AREAS THROUGH SUNDAY
BEFORE DRIER AIR ASSOCIATED WITH A COLD FRONT SPREADS SOUTH ACROSS
THE AREA MONDAY. MODERATE NORTHEAST WINDS WILL FOLLOW THIS BOUNDARY
AND LEAD TO INCREASING SEAS MONDAY THROUGH TUESDAY OVER THE ATLANTIC
WATERS.
FIRE WEATHER...
ALTHOUGH SOME DRIER AIR IS FORECAST TO SPREAD SOUTH INTO THE AREA
THROUGH THE FIRST HALF OF THE UPCOMING WEEK...RELATIVE HUMIDITIES
ARE FORECAST TO REMAIN ABOVE CRITICAL LEVELS EACH DAY. AS A
RESULT...THERE ARE NO RED FLAG CONCERNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 74 81 77 86 / 60 60 50 20
FORT LAUDERDALE 75 86 75 86 / 60 70 50 30
MIAMI 75 88 75 88 / 60 70 60 30
NAPLES 74 87 74 89 / 50 40 40 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...60/BD
AVIATION/RADAR...57/DG
AREA FORECAST DISCUSSION
NWS MIAMI FL
759 PM EDT SAT SEP 22 2012
.AVIATION...AREAS OF LIGHT RAIN ACROSS THE EAST COAST WILL
DIMINISH. HOWEVER, ADDITIONAL SHOWERS ARE POSSIBLE
OVERNIGHT...ESPECIALLY TOWARDS DAWN SUNDAY. THERE IS THE POTENTIAL
FOR THUNDERSTORMS AS WELL. MAINTAINED VCSH OVERNIGHT WITH PROB30
OF MVFR CONDITIONS ALL EAST COAST SITES BEGINNING SUN MORNING AND
INTO EARLY AFTERNOON. IFR WILL AGAIN BE POSSIBLE AT TIMES IN HEAVY
RAIN.
&&
.PREV DISCUSSION... /ISSUED 234 PM EDT SAT SEP 22 2012/
SHORT TERM (TONIGHT-MONDAY NIGHT)... AFTER A BUSY START TO THE
DAY THIS MORNING DUE TO FLOODING ALONG THE EAST COAST FROM MIAMI-
DADE TO PALM BEACH...THE LATEST HRRR MODEL REFLECTIVITIES HAVE
INITIALIZED WELL WITH THE CURRENT PATTERN AND CONTINUE TO INDICATE
ANOTHER ROUND OF ACTIVITY REDEVELOPING THROUGH THE MID TO LATE
AFTERNOON AND EVENING PERIODS. FOR COVERAGE...IT IS INDICATING THE
BULK OF THE HEAVIEST ACTIVITY SETTING UP OVER THE SOUTHERN HALF OF
THE LOCAL AREA WITH ANOTHER 1-2 INCHES OF RAINFALL POSSIBLE IN THE
HEAVIEST ACTIVITY. THIS SEEMS REASONABLE AS THE LATEST VISIBLE
SATELLITE IMAGERY SHOWS THE LARGEST BREAKS IN CLOUD COVERAGE OVER
THESE SOUTHERN AREAS WHERE TEMPERATURES HAVE QUICKLY INCREASED
OVER THE PAST 1-2 HRS. AS A RESULT...FLOODING REMAINS THE MAIN
CONCERN INTO THE EVENING HOURS. IF THIS ACTIVITY SETS UP OVER THE
SAME AREAS AS THIS MORNING WHERE 2-4 INCHES WERE RECORDED...MAINLY
FROM AROUND JUST SE OF CUTLER BAY TO NORTH MIAMI BEACH...FLASH
FLOODING CANNOT BE RULED OUT.
TONIGHT THROUGH SUNDAY NIGHT...THE COLD FRONT ENTERING THE REGION
FROM THE NORTH IS PROGGED TO CONTINUE SOUTH INTO NORTHERN AND
CENTRAL FLORIDA THROUGH THE FIRST HALF OF THE DAY SUNDAY FOLLOWED BY
A SURGE OF MUCH DRIER AIR BEFORE STALLING. UNFORTUNATELY...THE DEEP
LAY MOISTURE AXIS WITH AROUND 2" PWAT VALUES EXTENDING FROM NE TO SW
ACROSS THE AREA WILL REMAIN IN PLACE THROUGH SUNDAY WITH ONLY SOME
DRYING POSSIBLE ACROSS THE NORTHERN HALF OR THE LAKE REGION BY
TOMORROW NIGHT. THIS COMBINED WITH WEAK UPPER PULSES OF ENERGY
TRANSLATING NORTHEAST AHEAD OF THE BROAD UPPER TROUGH JUST WEST OF
THE AREA WILL KEEP THE RAIN AND FLOOD CHANCES AS THE PRIMARY
CONCERNS THROUGH SUNDAY. ADDITIONAL RAINFALL ACCUMULATIONS COULD
REACH THE 1 TO 3 INCH RANGE WITH LOCALIZED HIGHER AMOUNTS
POSSIBLE.
MONDAY AND MONDAY NIGHT...THE LATEST NUMERICAL GUIDANCE REMAINS IN
DECENT AGREEMENT AND INDICATES THE BROAD UPPER TROUGH OVER THE
EASTERN STATES SHIFTING EAST AND THE MUCH DRIER AIR THAT WAS
PREVIOUSLY DISCUSSED SHIFTING FARTHER SOUTH INTO OUR AREA IN THE
WAKE OF THE FRONTAL BOUNDARY. AS A RESULT...DRY AIR WITH LOWER
RAINFALL CHANCES CAN BE ANTICIPATED.
LONG TERM...(TUESDAY-FRIDAY)
THE UPPER RIDGE OVER THE ROCKIES BEGINS TO BREAK DOWN AS AN UPPER
LOW MOVES FROM THE PACIFIC NORTHWEST TOWARD THE CENTRAL ROCKIES.
THIS SHOVES THE E U.S. TROUGH NE WITH THE COLD FRONT STALLED N OF
LAKE OKEECHOBEE. THIS DRIES THE ATMOSPHERE SOMEWHAT FROM THE N TO
S ACROSS FLA BUT LONG RANGE MODELS STILL APPEAR TO DEVELOP AN
UPPER LOW OVER THE GULF AND WITH THE SW FLOW MAY KEEP AMPLE
ATMOSPHERIC MOISTURE OVER THE AREA. PLUS...ANOTHER TROPICAL WAVE
MAY NEAR THE AREA MIDWEEK NEXT WEEK. AT HIS TIME...WILL STAY WITH
GUIDANCE.
MARINE...
RAIN CHANCES WILL REMAIN UP ACROSS THE MARINE AREAS THROUGH SUNDAY
BEFORE DRIER AIR ASSOCIATED WITH A COLD FRONT SPREADS SOUTH ACROSS
THE AREA MONDAY. MODERATE NORTHEAST WINDS WILL FOLLOW THIS BOUNDARY
AND LEAD TO INCREASING SEAS MONDAY THROUGH TUESDAY OVER THE ATLANTIC
WATERS.
FIRE WEATHER...
ALTHOUGH SOME DRIER AIR IS FORECAST TO SPREAD SOUTH INTO THE AREA
THROUGH THE FIRST HALF OF THE UPCOMING WEEK...RELATIVE HUMIDITIES
ARE FORECAST TO REMAIN ABOVE CRITICAL LEVELS EACH DAY. AS A
RESULT...THERE ARE NO RED FLAG CONCERNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 74 81 77 86 / 80 60 50 20
FORT LAUDERDALE 75 86 75 86 / 90 70 50 30
MIAMI 75 88 75 88 / 80 70 60 30
NAPLES 74 87 74 89 / 80 40 40 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MIAMI FL
242 PM EDT FRI SEP 21 2012
.SHORT TERM...(TONIGHT-SUNDAY NIGHT)
THE LATEST RUC13 400 MB ANALYSIS AND WATER VAPOR LOOP SHOWED THE
LOCAL AREA UNDER MOIST SOUTHWEST UPPER FLOW AHEAD OF A LARGE SCALE
UPPER TROUGH CENTERED OVER MUCH OF THE COUNTRY. SEVERAL WEAK
PIECES OF ENERGY TRANSLATING NORTHEAST OVER THE STATE WITHIN THIS
SW UPPER FLOW COMBINED WITH THE OLD FRONTAL BOUNDARY AT THE
SURFACE THAT IS FORECAST TO SLOWLY SHIFT SOUTH INTO THE LOCAL AREA
THIS WEEKEND WILL KEEP THE RAIN CHANCES IN THE FORECAST. FOR THIS
EVENING...THE LATEST HRRR GUIDANCE INDICATES SCATTERED STORMS
SETTING UP FROM NAPLES TO THE LAKE REGION...WHICH IS VERY SIMILAR
TO YESTERDAY AFTERNOON/EVENING. ON SATURDAY...THE LATEST GFS
SOLUTION INDICATES A SURFACE WAVE DEVELOPING ALONG THIS BOUNDARY
AS A WEAK VORT MAX LIFTS NORTHEAST OVER THE AREA THROUGH THE DAY.
THIS COMBINED WITH PLENTY OF DEEP LAYER MOISTURE COULD LEAD TO AN
ENHANCED PERIOD OF RAINFALL TOMORROW ONCE AGAIN TOMORROW. IF THIS
DOES OCCUR...WEAK LOW LEVEL FLOW COULD TRANSLATE TO FLOODING
CONCERNS DEPENDING ON WHERE THE BULK OF THE ACTIVITY BECOMES
CONCENTRATED.
SATURDAY NIGHT THROUGH SUNDAY NIGHT...WHATS LEFT OF THE PREVIOUSLY
DISCUSSED BOUNDARY OR DEEP LAYER MOISTURE AXIS IN PLACE ACROSS S FL
IS FORECAST TO SLIGHTLY SHIFT FARTHER SOUTH AS ANOTHER REINFORCING
COLD FRONT SURGES SOUTH INTO THE REGION AND THE LARGE SCALE UPPER
TROUGH BEGINS TO SHIFT EAST. THE GFS APPEARS TO BE SLIGHTLY FASTER
THAN THE ECMWF AND NAM SOLUTIONS AND BEGINS TO INTRODUCE SOME DRIER
AIR AROUND THE LAKE REGION COME SUNDAY NIGHT INTO MONDAY. 85/AG
.LONG TERM...(MONDAY-THURSDAY)
THE UPPER TROUGH BEGINS TO SHIFT SLOWLY EAST AS THE UPPER RIDGE
OVER THE ROCKIES BEGINS TO BREAK DOWN AS ANOTHER MID LEVEL TROUGH
MOVES FROM THE PACIFIC NORTHWEST INTO THE ROCKIES. SOME SLIGHT
DRYING /DECREASE MAY OCCUR INITIALLY AS DRIER AIR FILTERS IN THE
THE NW BUT THE MODELS HINT AT AN UPPER LOW DEVELOPING OVER THE
GULF AND MOVING NE ACROSS THE FLA PENINSULA IN THE LATTER PERIODS.
WILL STAY CLOSE TO EXTENDED GUIDANCE AND SEE WHAT DEVELOPS. JR
&&
.MARINE...
LIGHT EASTERLY WINDS WILL PERSIST THROUGH THE WEEKEND
WITH SEAS REMAINING AROUND NORMAL. A STALLED FRONTAL BOUNDARY
COMBINED WITH AN UPPER TROUGH OF LOW PRESSURE WILL KEEP THE
RAINFALL CHANCES ELEVATED THROUGH THE WEEKEND. WINDS AND SEAS CAN
LOCALLY BECOME HIGHER IN AND AROUND ANY HEAVY SHOWERS OR STORMS.
&&
.FIRE WEATHER...
NO CONCERNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 75 83 76 84 / 50 70 60 40
FORT LAUDERDALE 75 85 74 84 / 50 70 60 40
MIAMI 75 86 74 86 / 50 70 60 40
NAPLES 75 86 75 84 / 50 50 50 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...85/AG
AVIATION/RADAR...84/AK
AREA FORECAST DISCUSSION
NWS MIAMI FL
140 PM EDT FRI SEP 21 2012
.AVIATION...
A LARGE AREA OF SHOWERS AND ISOLATED THUNDERSTORMS REMAINS
OFFSHORE OVER THE BAHAMAS AND THE SOUTHEASTERN ATLANTIC COASTAL
WATERS. CLOUD COVER AND LOW LEVEL WARMING AND DRYING DUE TO
OVERNIGHT CONVECTION HAS LIMITED SHOWER DEVELOPMENT THUS FAR
ACROSS THE REGION. A WEAK BOUNDARY REMAINS NEAR LAKE OKEECHOBEE
AND A FEW THUNDERSTORMS ARE BEGINNING TO DEVELOP ALONG IT. THE
HRRR IS SHOWING THAT STORMS MAY FIRE SOUTHWEST ALONG THIS BOUNDARY
TOWARDS KAPF OVER THE NEXT COUPLE HOURS. FOR THE EAST COAST TAF
SITES...THERE IS A LOT OF UNCERTAINTY TO WHEN SHOWERS AND STORMS
WILL REDEVELOP ALONG THE COASTLINE. IT MAY NOT BE UNTIL LATE IN
THE AFTERNOON/EARLY EVENING. SHOWERS AND/OR THUNDERSTORMS ARE ALSO
POSSIBLE OVERNIGHT AND THEN THROUGH THE END OF THE TAF PERIOD AS
DEEP MOISTURE AND EAST TO NORTHEAST FLOW REMAINS OVER THE REGION.
&&
.PREV DISCUSSION... /ISSUED 1031 AM EDT FRI SEP 21 2012/
UPDATE...
THE LATEST RUC13 400 MB ANALYSIS AND THE MORNING WATER VAPOR
LOOP SHOWED THE LOCAL AREA UNDER MOIST SOUTHWEST UPPER FLOW AHEAD
OF A LARGE SCALE UPPER TROUGH CENTERED OVER MUCH OF THE COUNTRY.
SEVERAL WEAK PIECES OF ENERGY TRANSLATING NORTHEAST OVER THE STATE
WITHIN THIS SW UPPER FLOW COMBINED WITH THE OLD FRONTAL BOUNDARY
AT THE SURFACE LINGERING AROUND THE LAKE REGION AND A WAVE PASSING
SOUTH OF THE AREA WILL HELP KEEP THE RAIN CHANCES IN THE FORECAST.
ONE PULSE OF ENERGY ASSOCIATED WITH THE OVERNIGHT RAINFALL LAST
NIGHT IS NOW LIFTING NORTHEAST OF THE AREA...WHICH HAS LED TO A
DOWNWARD TREND IN THE RAINFALL COVERAGE LOCALLY THIS MORNING.
THERE IS ANOTHER NOTABLE SHORTWAVE TROUGH LOCATED JUST NORTH OF
THE YUCATAN PENINSULA WITH SOME SCATTERED CONVECTION DEVELOPING
OUT AHEAD OF IT. MODELS ARE PICKING UP ON THIS AND GENERALLY
INDICATE IT LIFTING NORTHEAST TOWARD THE AREA THROUGH THE DAY
TODAY. CONSIDERING THE EXTENSIVE CLOUD COVERAGE IN PLACE AND THE
DRY LAYER NOTED JUST ABOVE THE SURFACE FROM THE MORNING UPPER AIR
SOUNDING MAY BECOME THE LIMITING FACTORS TODAY FOR ANY EARLY
CONVECTION BEING TRIGGERED. THEREFORE...WILL SLIGHTLY SCALE BACK
THE RAINFALL CHANCES THROUGH A GOOD PORTION OF THE AFTERNOON.
OTHERWISE...THE PREVIOUS PACKAGE REMAINS ON TRACK AT THIS TIME.
85/AG
PREV DISCUSSION... /ISSUED 734 AM EDT FRI SEP 21 2012/
AVIATION...
SCATTERED TO NUMEROUS SHOWERS AND EMBEDDED THUNDERSTORMS OVER THE
LOCAL ATLANTIC AND GULF WATERS WILL CONTINUE MOVING NORTH AND
NORTHWEST...AND WEAKEN AS THEY MOVE TOWARDS THE SHORE. KEPT -RA
AND VCSH FOR ALL TAFS THIS MORNING. DEEP MOISTURE AND THE NORTHERN
END OF A TROPICAL WAVE IS EXPECTED TO MOVE ACROSS THE REGION THIS
AFTERNOON. CLOUD COVER AND RAINFALL OVERNIGHT MAY DELAY THIS
ACTIVITY FROM MOVING IN UNTIL AFTER 16Z...WHICH IS SHOWN BY THE
LATEST HRRR RUN. RAIN WITH EMBEDDED THUNDERSTORMS IS POSSIBLE AT
ALL THE TAF SITES IN THE AFTERNOON AND INTO THE EVENING HOURS.
PREVAILING MVFR CONDITIONS MAY BE POSSIBLE AROUND 18Z THROUGH THE
AFTERNOON HOURS AS SHOWERS AND EMBEDDED STORMS MOVE FROM THE SOUTH
AND SOUTHEAST. FOR NOW WILL KEEP VFR CONDITIONS AND AMEND AS
NECESSARY AND REASSESS FOR THE 18Z TAFS.
PREV DISCUSSION... /ISSUED 344 AM EDT FRI SEP 21 2012/
DISCUSSION...A LARGE SCALE MID LEVEL TROUGH...EXTENDING FROM S
CANADA INTO THE CENTRAL GULF OF MEX...WILL CONTINUE TO COVER THE E
HALF OF THE U.S. TODAY AND INTO THE WEEKEND AS A STRONG ATLC RIDGE
SE OF S FLA AND ANOTHER OVER THE ROCKY MTN W REMAIN IN PLACE WHICH
ANCHOR THE UPPER TROUGH IN PLACE. AT THE SURFACE...A WEAKENING
FRONTAL BOUNDARY...LOCATED OVER THE LAKE OKEECHOBEE REGION...WILL
BECOME DIFFUSE TODAY INTO THIS EVENING WHILE A TROPICAL WAVE MOVES
WESTWARD S OF THE AREA BUT WITH THE NORTHERN TIP OF THE WAVE
BRUSHING S FLA. THE MID AND UPPER LEVEL WIND FLOW WILL BE WEAK
SOUTHWESTERLY AND AT THE LOW LEVEL EASTERLY. PRECIPITABLE WATER AT
OR ABOVE 2 INCHES COMBINED WITH SEA BREEZES EACH COAST...THE
BOUNDARY TO THE N...THE WAVE TO THE S AND WITH DIURNAL HEATING
NUMEROUS AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS CAN BE
EXPECTED TODAY AND AGAIN ON ON SATURDAY WITH A POSSIBLE DECREASE
SUNDAY. STEERING WINDS WILL BE LIGHT AN LOCALLY HEAVY RAINS EXPECTED
AGAIN.
EXTENDED PERIOD...MONDAY THROUGH THURSDAY...THE UPPER TROUGH BEGINS
TO SHIFT SLOWLY EAST AS THE UPPER RIDGE OVER THE ROCKIES BEGINS TO
BREAK DOWN AS ANOTHER MID LEVEL TROUGH MOVES FROM THE PACIFIC
NORTHWEST INTO THE ROCKIES. SOME SLIGHT DRYING/DECREASE MAY OCCUR
INITIALLY AS DRIER AIR FILTERS IN THE THE NW BUT THE MODELS HINT AT
AN UPPER LOW DEVELOPING OVER THE GULF AND MOVING NE ACROSS THE FLA
PENINSULA IN THE LATTER PERIODS. WILL STAY CLOSE TO EXTENDED
GUIDANCE AND SEE WHAT DEVELOPS.
MARINE...EASTERLY WINDS WILL CONTINUE THROUGH THE PERIOD WITH WINDS
LESS THAN 15 KNOTS AND SEAS LESS THAN 4 FEET BOTH IN THE GULF AND
ATLANTIC WATERS.
FIRE WEATHER...NO PROBLEMS OR CONCERNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 77 83 76 84 / 40 50 40 40
FORT LAUDERDALE 77 85 74 84 / 40 50 40 40
MIAMI 77 86 74 86 / 40 50 40 40
NAPLES 74 86 75 84 / 50 50 40 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...85/AG
AVIATION/RADAR...84/AK
AREA FORECAST DISCUSSION
NWS MIAMI FL
1031 AM EDT FRI SEP 21 2012
.UPDATE...
THE LATEST RUC13 400 MB ANALYSIS AND THE MORNING WATER VAPOR
LOOP SHOWED THE LOCAL AREA UNDER MOIST SOUTHWEST UPPER FLOW AHEAD
OF A LARGE SCALE UPPER TROUGH CENTERED OVER MUCH OF THE COUNTRY.
SEVERAL WEAK PIECES OF ENERGY TRANSLATING NORTHEAST OVER THE STATE
WITHIN THIS SW UPPER FLOW COMBINED WITH THE OLD FRONTAL BOUNDARY
AT THE SURFACE LINGERING AROUND THE LAKE REGION AND A WAVE PASSING
SOUTH OF THE AREA WILL HELP KEEP THE RAIN CHANCES IN THE FORECAST.
ONE PULSE OF ENERGY ASSOCIATED WITH THE OVERNIGHT RAINFALL LAST
NIGHT IS NOW LIFTING NORTHEAST OF THE AREA...WHICH HAS LED TO A
DOWNWARD TREND IN THE RAINFALL COVERAGE LOCALLY THIS MORNING.
THERE IS ANOTHER NOTABLE SHORTWAVE TROUGH LOCATED JUST NORTH OF
THE YUCATAN PENINSULA WITH SOME SCATTERED CONVECTION DEVELOPING
OUT AHEAD OF IT. MODELS ARE PICKING UP ON THIS AND GENERALLY
INDICATE IT LIFTING NORTHEAST TOWARD THE AREA THROUGH THE DAY
TODAY. CONSIDERING THE EXTENSIVE CLOUD COVERAGE IN PLACE AND THE
DRY LAYER NOTED JUST ABOVE THE SURFACE FROM THE MORNING UPPER AIR
SOUNDING MAY BECOME THE LIMITING FACTORS TODAY FOR ANY EARLY
CONVECTION BEING TRIGGERED. THEREFORE...WILL SLIGHTLY SCALE BACK
THE RAINFALL CHANCES THROUGH A GOOD PORTION OF THE AFTERNOON.
OTHERWISE...THE PREVIOUS PACKAGE REMAINS ON TRACK AT THIS TIME.
85/AG
&&
.PREV DISCUSSION... /ISSUED 734 AM EDT FRI SEP 21 2012/
AVIATION...
SCATTERED TO NUMEROUS SHOWERS AND EMBEDDED THUNDERSTORMS OVER THE
LOCAL ATLANTIC AND GULF WATERS WILL CONTINUE MOVING NORTH AND
NORTHWEST...AND WEAKEN AS THEY MOVE TOWARDS THE SHORE. KEPT -RA
AND VCSH FOR ALL TAFS THIS MORNING. DEEP MOISTURE AND THE NORTHERN
END OF A TROPICAL WAVE IS EXPECTED TO MOVE ACROSS THE REGION THIS
AFTERNOON. CLOUD COVER AND RAINFALL OVERNIGHT MAY DELAY THIS
ACTIVITY FROM MOVING IN UNTIL AFTER 16Z...WHICH IS SHOWN BY THE
LATEST HRRR RUN. RAIN WITH EMBEDDED THUNDERSTORMS IS POSSIBLE AT
ALL THE TAF SITES IN THE AFTERNOON AND INTO THE EVENING HOURS.
PREVAILING MVFR CONDITIONS MAY BE POSSIBLE AROUND 18Z THROUGH THE
AFTERNOON HOURS AS SHOWERS AND EMBEDDED STORMS MOVE FROM THE SOUTH
AND SOUTHEAST. FOR NOW WILL KEEP VFR CONDITIONS AND AMEND AS
NECESSARY AND REASSESS FOR THE 18Z TAFS.
PREV DISCUSSION... /ISSUED 344 AM EDT FRI SEP 21 2012/
DISCUSSION...A LARGE SCALE MID LEVEL TROUGH...EXTENDING FROM S
CANADA INTO THE CENTRAL GULF OF MEX...WILL CONTINUE TO COVER THE E
HALF OF THE U.S. TODAY AND INTO THE WEEKEND AS A STRONG ATLC RIDGE
SE OF S FLA AND ANOTHER OVER THE ROCKY MTN W REMAIN IN PLACE WHICH
ANCHOR THE UPPER TROUGH IN PLACE. AT THE SURFACE...A WEAKENING
FRONTAL BOUNDARY...LOCATED OVER THE LAKE OKEECHOBEE REGION...WILL
BECOME DIFFUSE TODAY INTO THIS EVENING WHILE A TROPICAL WAVE MOVES
WESTWARD S OF THE AREA BUT WITH THE NORTHERN TIP OF THE WAVE
BRUSHING S FLA. THE MID AND UPPER LEVEL WIND FLOW WILL BE WEAK
SOUTHWESTERLY AND AT THE LOW LEVEL EASTERLY. PRECIPITABLE WATER AT
OR ABOVE 2 INCHES COMBINED WITH SEA BREEZES EACH COAST...THE
BOUNDARY TO THE N...THE WAVE TO THE S AND WITH DIURNAL HEATING
.NUMEROUS AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS CAN BE
EXPECTED TODAY AND AGAIN ON ON SATURDAY WITH A POSSIBLE DECREASE
SUNDAY. STEERING WINDS WILL BE LIGHT AN LOCALLY HEAVY RAINS EXPECTED
AGAIN.
EXTENDED PERIOD...MONDAY THROUGH THURSDAY...THE UPPER TROUGH BEGINS
TO SHIFT SLOWLY EAST AS THE UPPER RIDGE OVER THE ROCKIES BEGINS TO
BREAK DOWN AS ANOTHER MID LEVEL TROUGH MOVES FROM THE PACIFIC
NORTHWEST INTO THE ROCKIES. SOME SLIGHT DRYING/DECREASE MAY OCCUR
INITIALLY AS DRIER AIR FILTERS IN THE THE NW BUT THE MODELS HINT AT
AN UPPER LOW DEVELOPING OVER THE GULF AND MOVING NE ACROSS THE FLA
PENINSULA IN THE LATTER PERIODS. WILL STAY CLOSE TO EXTENDED
GUIDANCE AND SEE WHAT DEVELOPS.
MARINE...EASTERLY WINDS WILL CONTINUE THROUGH THE PERIOD WITH WINDS
LESS THAN 15 KNOTS AND SEAS LESS THAN 4 FEET BOTH IN THE GULF AND
ATLANTIC WATERS.
FIRE WEATHER...NO PROBLEMS OR CONCERNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 87 76 87 76 / 60 40 50 40
FORT LAUDERDALE 88 76 85 77 / 60 40 50 40
MIAMI 87 75 87 76 / 60 40 50 40
NAPLES 88 73 87 74 / 70 50 50 40
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...85/AG
AVIATION/RADAR...84/AK
AREA FORECAST DISCUSSION
NWS MIAMI FL
734 AM EDT FRI SEP 21 2012
.AVIATION...
SCATTERED TO NUMEROUS SHOWERS AND EMBEDDED THUNDERSTORMS OVER THE
LOCAL ATLANTIC AND GULF WATERS WILL CONTINUE MOVING NORTH AND
NORTHWEST...AND WEAKEN AS THEY MOVE TOWARDS THE SHORE. KEPT -RA
AND VCSH FOR ALL TAFS THIS MORNING. DEEP MOISTURE AND THE NORTHERN
END OF A TROPICAL WAVE IS EXPECTED TO MOVE ACROSS THE REGION THIS
AFTERNOON. CLOUD COVER AND RAINFALL OVERNIGHT MAY DELAY THIS
ACTIVITY FROM MOVING IN UNTIL AFTER 16Z...WHICH IS SHOWN BY THE
LATEST HRRR RUN. RAIN WITH EMBEDDED THUNDERSTORMS IS POSSIBLE AT
ALL THE TAF SITES IN THE AFTERNOON AND INTO THE EVENING HOURS.
PREVAILING MVFR CONDITIONS MAY BE POSSIBLE AROUND 18Z THROUGH THE
AFTERNOON HOURS AS SHOWERS AND EMBEDDED STORMS MOVE FROM THE SOUTH
AND SOUTHEAST. FOR NOW WILL KEEP VFR CONDITIONS AND AMEND AS
NECESSARY AND REASSESS FOR THE 18Z TAFS.
&&
.PREV DISCUSSION... /ISSUED 344 AM EDT FRI SEP 21 2012/
DISCUSSION...A LARGE SCALE MID LEVEL TROUGH...EXTENDING FROM S
CANADA INTO THE CENTRAL GULF OF MEX...WILL CONTINUE TO COVER THE E
HALF OF THE U.S. TODAY AND INTO THE WEEKEND AS A STRONG ATLC RIDGE
SE OF S FLA AND ANOTHER OVER THE ROCKY MTN W REMAIN IN PLACE WHICH
ANCHOR THE UPPER TROUGH IN PLACE. AT THE SURFACE...A WEAKENING
FRONTAL BOUNDARY...LOCATED OVER THE LAKE OKEECHOBEE REGION...WILL
BECOME DIFFUSE TODAY INTO THIS EVENING WHILE A TROPICAL WAVE MOVES
WESTWARD S OF THE AREA BUT WITH THE NORTHERN TIP OF THE WAVE
BRUSHING S FLA. THE MID AND UPPER LEVEL WIND FLOW WILL BE WEAK
SOUTHWESTERLY AND AT THE LOW LEVEL EASTERLY. PRECIPITABLE WATER AT
OR ABOVE 2 INCHES COMBINED WITH SEA BREEZES EACH COAST...THE
BOUNDARY TO THE N...THE WAVE TO THE S AND WITH DIURNAL HEATING
..NUMEROUS AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS CAN BE
EXPECTED TODAY AND AGAIN ON ON SATURDAY WITH A POSSIBLE DECREASE
SUNDAY. STEERING WINDS WILL BE LIGHT AN LOCALLY HEAVY RAINS EXPECTED
AGAIN.
EXTENDED PERIOD...MONDAY THROUGH THURSDAY...THE UPPER TROUGH BEGINS
TO SHIFT SLOWLY EAST AS THE UPPER RIDGE OVER THE ROCKIES BEGINS TO
BREAK DOWN AS ANOTHER MID LEVEL TROUGH MOVES FROM THE PACIFIC
NORTHWEST INTO THE ROCKIES. SOME SLIGHT DRYING/DECREASE MAY OCCUR
INITIALLY AS DRIER AIR FILTERS IN THE THE NW BUT THE MODELS HINT AT
AN UPPER LOW DEVELOPING OVER THE GULF AND MOVING NE ACROSS THE FLA
PENINSULA IN THE LATTER PERIODS. WILL STAY CLOSE TO EXTENDED
GUIDANCE AND SEE WHAT DEVELOPS.
MARINE...EASTERLY WINDS WILL CONTINUE THROUGH THE PERIOD WITH WINDS
LESS THAN 15 KNOTS AND SEAS LESS THAN 4 FEET BOTH IN THE GULF AND
ATLANTIC WATERS.
FIRE WEATHER...NO PROBLEMS OR CONCERNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 87 76 87 76 / 60 40 50 40
FORT LAUDERDALE 88 76 85 77 / 60 40 50 40
MIAMI 87 75 87 76 / 60 40 50 40
NAPLES 88 73 87 74 / 70 50 50 40
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...85/AG
AVIATION/RADAR...84/AK
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
437 PM CDT FRI SEP 21 2012
.MESOSCALE DISCUSSION...
300 PM CDT
CONTINUE TO MONITOR POTENTIAL FOR A COUPLE SEVERE STORMS ACROSS
THE SOUTHERN FORECAST AREA...PRIMARILY ALONG AND SOUTH OF U.S.
HIGHWAY 24.
STRONG WELL-ALIGNED UPPER AND MID LEVEL NORTHWESTERLY JETS
CONTINUE TO PROGRESS SOUTHEAST FROM IA WITH AN
ELONGATED SHORT WAVE...POSSIBLY TWO...IMPULSE FROM SOUTHERN MN
INTO SOUTHEAST IA. LATEST HAND SURFACE ANALYSIS DEPICTS A 1005 MB
SURFACE LOW NEAR PITTSFIELD IN WEST CENTRAL IL WITH STRONG
PRESSURE FALLS OF ALMOST 5 MB/3 HR IN ADVANCE. THIS IS WELL
ALIGNED WITH ROBUST LOW-LEVEL TD ADVECTION /8-14F CLIMBS PER
HOUR/ INTO THE MID TO UPPER 50S FROM SPI/TAZ SOUTHEASTWARD ACROSS
THE ILX CWA. THIS AREA HIGHLIGHTS WHERE THE DEVELOPING SURFACE
WARM FRONT IS AND LIKELY NEAR THE NORTHERN EXTENT OF ANY SURFACE-
BASED UPDRAFT POTENTIAL. DEW POINTS REMAIN LOW NORTH OF THIS
AREA...INCLUDING IN THE SOUTHERN FORECAST AREA WHERE NAMELY MID
40S PREVAIL ALONG WITH MORE OF AN EASTERLY WIND COMPONENT. WHILE
THE MOISTENING BOUNDARY LAYER IS MOVING NORTH QUICKLY IN ADVANCE
OF THE LOW...AT THIS TIME IT DOES NOT LOOK TO MAKE IT ALL THE WAY
TO THE SOUTHERN FORECAST AREA. SO THE MAIN CONCERNS REMAIN FOR
ELEVATED STORMS.
MID-LEVEL FLOW ANALYZED BY UPSTREAM PROFILES AND THE RAP MODEL OF
OVER 50 KT IS CONTRIBUTING TO DEEP LAYER SHEAR AT OR IN EXCESS OF
60 KT INTO CENTRAL IL. STRENGTHENING SOUTHERLY 850 MB FLOW AND
MOISTURE TRANSPORT AHEAD OF THE DEVELOPING LOW PRESSURE IS
FURTHERING THE CROSSOVER COMPONENT NEAR THE INTERSTATE 74 CORRIDOR
AND UP TO THE SOUTHERN CWA. INSTABILITY IS SOMEWHAT MEAGER...BUT
LIKELY UNDERDONE BY MOST GUIDANCE GIVEN THE CONVECTIVE
TRENDS...AND COULD BE NEAR 500 J/KG. TOGETHER THIS COULD SUPPORT
BRIEF ELEVATED SUPERCELLS OR POSSIBLY A SMALL ARC/CLUSTER OF
STORMS TRACKING ACROSS THE FAR SOUTHERN FORECAST AREA BETWEEN 4
AND 7 PM...CAPABLE OF MAINLY A HAIL THREAT.
MTF
&&
.DISCUSSION...
348 PM CDT
COOL THROUGH THE WEEKEND THEN TEMPERATURES MODERATE FIRST PART OF
NEXT WEEK. A SHORT BREAK IN THREAT OF RAIN THIS EVENING THEN
CHANCES RETURN OVERNIGHT THROUGH SAT MORNING.
MULTIPLE MINOR SHORT WAVES IN THE UPPER FLOW TURNING FROM SSE TO
SE AS THEY CROSS THE UPPER MIDWEST AND THEN SE TO ESE AS THEY
ROTATE ACROSS THE MID MS VALLEY AND THE WESTERN GREAT LAKES INTO
THE BASE OF THE UPPER TROUGH THE REST OF TODAY AND THIS EVENING.
FURTHER UPSTREAM OVER SOUTHERN MANITOBA IS A STRONGER SHORT WAVE
PROGGED TO REACH SOUTHERN WI BY 12Z SAT. AS THIS DISTURBANCE
APPROACHES LATE TONIGHT A CHANCE OF RAIN RETURNS
OVERNIGHT...ENDING MIDDAY WITH THIS SHORT WAVE TROUGH PROGGED TO
CONTINUE ON TO NORTHERN IND BY 18Z SAT. HIGHEST CHANCES WILL BE
ACROSS THE NE 1/2 OF THE FORECAST AREA...ALONG AND N OF THE
PROJECTED PATH OF THE VORT MAX.
IN THE WAKE OF THE SHORT WAVE/WAVES MOVING ACROSS THE AREA TODAY
WEAK LOW LEVEL COLD AIR ADVECTION TO TAKE PLACE. THIS...COMBINED
WITH EXPECTED SHOWERS AND EXTENSIVE CLOUDINESS...WILL KEEP
TEMPERATURES DURING SAT LIMITED TO THE UPPER 50S AND LOWER 60S.
WITH THE PASSAGE OF THE STRONGER SHORT WAVE DURING SAT MORNING
STRONGER COLD AIR ADVECTION TO TAKE PLACE WITH 850HPA
TEMPERATURES DROPPING TO AROUND 0C FOR THE AFTERNOON. DESPITE THE
COLD AIR ADVECTION SURFACE HEATING IS EXPECTED TO MITIGATE THE
COOLING AS CLOUDS CLEAR DURING THE DAY IN THE WAKE OF THE SHORT
WAVE.
A HIGH PRESSURE RIDGE IS TO BE BUILDING FROM THE NORTHERN PLAINS
ACROSS THE MO RIVER VALLEY DURING THE DAY SAT AND THE UPPER AND
MID MS VALLEY AND LOWER OH VALLEY DURING SAT NIGHT. CLEAR
SKIES...DEW POINTS IN THE MID 20S TO LOWER 30S...AND LACK OF
BOUNDARY LAYER MIXING AS SURFACE WINDS BECOME NIL ARE EXPECTED TO
LEAD TO SAT NIGHT LOWS IN THE LOWER AND MID 30S ACROSS MUCH OF
THE LOCAL FORECAST AREA. FROST A GOOD POSSIBILITY ACROSS THE W
AND SW PORTIONS OF THE FORECAST AREA...CLOSEST TO THE SURFACE
RIDGE AXIS...OVERNIGHT SAT AND EARLY SUN MORNING.
YET ANOTHER SHORT WAVE IS SHOWN BY MODELS DROPPING OVER THE UPPER
MIDWEST AND THE WESTERN GREAT LAKES DURING SUN. HOWEVER...WITH A
VERY DRY AIR MASS IN PLACE POPS ONLY IN THE SINGLE DIGITS. EVEN
CLOUDS WILL BE HARD TO COME BY WITH JUST SOME CIRRUS ASSOCIATED
WITH THE JET MAX MOVING OVERHEAD. WITH THE UPPER TROUGH
BROADENING OVER THE REGION AND THE CENTER OF THE CENTER OF THE
LARGE SCALE UPPER CYCLONE REESTABLISHING ITSELF OVER SOUTHERN
HUDSON BAY AND NW QUEBEC BY MON MORNING THE MID LATITUDE UPPER
FLOW BACKS TO OUT OF THE WNW. WITH THE UPPER LOW FURTHER NORTH
DISTURBANCES ROTATING AROUND IT WILL TRACK OVER THE NORTH WOODS
AND THE NORTHERN GREAT LAKES KEEPING CHANCES OF PRECIPITATION LOW
THROUGH MON NIGHT.
HOWEVER...A COLD FRONT IS PROGGED TO SLIP SE ACROSS THE LOCAL
AREA TUE AND TUE NIGHT BEFORE BECOMING STATIONARY FROM NE MO
ACROSS CENTRAL IL TO NORTHERN IND BY WED MORNING. INCREASING FLOW
FROM THE CENTRAL PLAINS ENE ACROSS THE MID MS VALLEY WILL RESULT
IN INCREASING WARM AIR ADVECTION AS WELL AS MID AND LOWER LEVEL
MOISTURE TRANSPORT INTO THE AREA WITH CHANCES OF SHOWERS AND
THUNDERSTORMS...MAINLY FOR THE N 1/2 TO 3/4 OF THE LOCAL FORECAST
AREA TUE THROUGH WED BEFORE A STRONG SHORT WAVE DROPPING ACROSS
THE UPPER MIDWEST AND WESTERN GREAT LAKES PUSHES THE SURFACE FRONT
FURTHER TO THE S AND ANOTHER LARGE SURFACE ANTICYCLONE BUILDS OVER
THE UPPER MIDWEST AND THE GREAT LAKES DURING WED AND WED NIGHT.
WED NIGHT THROUGH FRI WILL HAVE LOW POPS AS THE HIGH PRESSURE WILL
DOMINATE THE WEATHER OVER THE REGION...CONTINUING TO FEED COOL DRY
AIR ACROSS THE AREA.
TRS
.CLIMATE...
RECORD LOW SEP 23
CHICAGO 29 1995
ROCKFORD 29 1974
EARLIEST FIRST FREEZE DATE
CHICAGO SEP 22 1995 /32F/
ROCKFORD SEP 13 1975 /32F/
AVERAGE FIRST FREEZE DATE
CHICAGO OCT 15
ROCKFORD OCT 7
TRS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 2130Z...
* NORTHEAST WINDS BECOMING VARIABLE THROUGH EARLY EVENING.
* OFF AND ON SHOWERS WITH POSSIBLE PERIODS OF LOWER CIGS/VSBYS.
RATZER
//DISCUSSION...UPDATED 2130Z...
NORTHEAST WINDS HAVE BEEN INCREASING A BIT WITH GUSTS AROUND 15
KTS NOTED ACROSS NORTHERN IL. THIS APPEARS TO BE IN RESPONSE TO
RAPID PRESSURE FALLS WITH QUICK MOVING DEEPENING LOW PRESSURE
SYSTEM WORKING ITS WAY EAST ACROSS CENTRAL IL. EXPECT BRIEFLY
GUSTY NNE WINDS FOR THE NEXT COUPLE OF HOURS OR SO...BEFORE LOW
MOVES QUICKLY OFF INTO INDIANA EARLY THIS EVENING. PERIOD OF
LIGHTER VARIABLE/WEST WINDS APPEAR LIKELY DURING THE EVENING AS
THE GRADIENT WEAKENS...AHEAD OF THE NEXT COLD FRONT WHICH
APPROACHES THE AREA QUICKLY LATE TONIGHT/EARLY SATURDAY. ALSO
SHOULD SEE A BREAK FROM THE LIGHT RAIN/SHOWERS BETWEEN SYSTEMS
DURING THE EVENING HOURS.
RATZER
PREVIOUS DISCUSSION FROM 18Z...
AN ACTIVE WEATHER PATTERN OVER THE NEXT 36 HOURS WILL BRING
MULTIPLE CONCERNS TO THOSE WITH AVIATION INTERESTS. A PAIR OF
UPPER LEVEL DISTURBANCES ARE MOVING OVER THE AREA THIS
AFTERNOON...AND BOTH IN TANDEM ARE HELPING TO BRING RAIN TO THE
AREA. WHILE THIS WAS MORE SHOWERY EARLIER...THIS IS LIKELY TO BE A
MORE PERSISTENT RAIN AT TAF SITES THIS AFTERNOON...ESPECIALLY
RFD...DPA...AND ORD. TEMPORARY MVFR VISIBILITIES HAVE BEEN SEEN
ACROSS SOUTHWEST WI WITHIN THE RAIN AREA...AND GIVEN THE MID-LEVEL
FORCING AND JUST OVERALL IMPRESSIVE DYNAMICS...WOULD NOT BE
SURPRISED TO SEE SOME OF THAT AND MAYBE EVEN BRIEF MVFR CIGS. A
SURFACE REFLECTION TO THE UPPER LEVEL WAVES WILL BE DEFINED IN A
LOW PRESSURE ACROSS WESTERN IL BY MID TO LATE AFTERNOON. THIS WILL
HELP TO EVOLVE THE WIND FIELD INTO MORE NORTHERLY ACROSS MOST OF
THE TAF SITES THAN ORIGINALLY THOUGHT...AND POTENTIALLY EVEN
NORTHEASTERLY BY LATE AFTERNOON AND EARLY EVENING. WIND SPEEDS
WILL LIKELY BE UNDER 10 KT DURING THAT PERIOD...THOUGH THEY MAY BE
CLOSE. SPEEDS WILL DROP TONIGHT AND THE DIRECTION SHOULD AGAIN
BECOME VARIABLE. ANOTHER VIGOROUS UPPER LEVEL DISTURBANCE WILL
MOVE OVER THE AREA SATURDAY MORNING LIKELY CREATING SHOWERS BUT IN
PARTICULAR BRINGING A SURGE OF STRONGER NORTHWEST WINDS AND COLDER
AIR. THIS WILL SET THE STAGE FOR WIND GUSTS IN THE 25-30 KT
BALLPARK FROM MID TO LATE MORNING SATURDAY INTO THE AFTERNOON. IN
ADDITION...COLD AIR ADVECTION STRATOCUMULUS WILL LIKELY BE MVFR
IMMEDIATELY BEHIND THE COLD FRONT SATURDAY MORNING AND GRADUALLY
RAISE THROUGH THE DAY.
//ORD AND MDW CONFIDENCE...UPDATED 2130Z...
* HIGH CONFIDENCE IN NNE WINDS REMAINDER OF AFTERNOON HOURS. LOWER
CONFIDENCE IN DIRECTION DURING THE EVENING...WITH LOWER SPEEDS
AND MORE VARIABLE/WEST DIRECTION EXPECTED.
* MEDIUM TO HIGH CONFIDENCE OF STAYING ABOVE MVFR EXCEPT FOR BRIEF
PERIODS. NOT ANTICIPATING IFR THIS EVENING.
RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
* SATURDAY NIGHT THROUGH MONDAY...VFR.
* TUESDAY...CHANCE OF SHOWERS.
* WEDNESDAY...CHANCE OF THUNDERSTORMS SOUTH...OTHERWISE VFR.
* THURSDAY...VFR
MTF
&&
.MARINE...
230 PM CDT
LOW PRESSURE OVER THE UPPER GREAT LAKES WILL TRACK NORTHEAST
TOWARD HUDSON BAY OVERNIGHT TONIGHT AND THEN RAPIDLY DEEPEN
TOMORROW AS STRONG HIGH PRESSURE BUILDS ACROSS THE NORTHERN
PLAINS. A SERIES OF MID LEVEL IMPULSES WILL BRING REINFORCING
SHOTS OF COLD AIR OVER THE WESTERN GREAT LAKES TOMORROW. THE
RESULTANT STRONG COLD ADVECTION WILL LEAD TO RAPIDLY
STRENGTHENING NORTHERLY WINDS TOMORROW...LIKELY REACHING GALE
FORCE DURING THE AFTERNOON HOURS. THE PRESSURE GRADIENT AND COLD
ADVECTION WILL BE STRONGEST OVER THE FAR NORTHERN PORTIONS OF THE
LAKE...SO HAVE HOISTED A GALE WARNING FOR THE NORTHERN ONE-THIRD
OF THE LAKE. THE WINDOW OF OPPORTUNITY FOR THE STRONGEST WINDS
WILL BE DURING THE AFTERNOON AND EVENING HOURS WHEN HIGH PRESSURE
SPREADING INTO THE WESTERN GREAT LAKES SHOULD HELP ALLOW WINDS TO
SUBSIDE BELOW GALE FORCE. FOR THE SOUTHERN PORTIONS OF THE
LAKE...WINDS AND WAVES SHOULD QUICKLY RISE TO SMALL CRAFT
ADVISORY LEVELS TOMORROW AS WELL...WITH THE INDIANA WATERS
REACHING SMALL CRAFT ADVISORY LEVELS SOONER THAN THE ILLINOIS
WATERS...AND LINGERING LONGER...INTO MONDAY MORNING DUE TO THE
GENERALLY NORTHERLY FETCH SETTING UP OVER THE LAKE. BY MONDAY
AFTERNOON...ANOTHER DEEPENING LOW TRACKING JUST NORTH OF THE
GREAT LAKES MAY POSSIBLY BRING ANOTHER BRIEF PERIOD OF
SOUTHWESTERLY GALES TO THE FAR NORTHERN PORTION OF THE LAKE...
BUT WILL NOT ISSUE ANY HEADLINES AT THIS TIME SINCE THE STRENGTH
OF THE WINDS WILL BE HIGHLY DEPENDENT ON THE EXACT TRACK OF THE
LOW.
THE OTHER CONCERN FOR LAKE MICHIGAN WILL BE WATERSPOUT POTENTIAL.
LAKE SFC WATER TEMPERATURES REMAIN UNUSUALLY HIGH...WITH A
TEMPERATURE OF 17C AT THE NORTH BUOY AND 20C AT THE SOUTH BUOY
THIS AFTERNOON. WHEN THE MUCH COOLER AIR PLUNGES OVER LAKE
MICHIGAN...LAKE SFC TO 850MB DELTA-T VALUES WILL REACH AS HIGH AS
22-23C...INDICATIVE OF A VERY UNSTABLE ENVIRONMENT OVER LAKE
MICHIGAN. WHILE CONVERGENCE BOUNDARIES ARE NOT LIKELY OVER THE
LAKE...WATERSPOUT POTENTIAL WILL REMAIN HIGH DUE TO LAKE EFFECT
RAIN SHOWERS AND DEEP LAYER CONVECTIVE CLOUD DEVELOPMENT.
CONDITIONS WILL BE CONDUCIVE TO WATERSPOUTS FROM THIS EVENING
THROUGH MONDAY EVENING...ESPECIALLY FOR THE NORTHERN AND EASTERN
PORTIONS OF THE LAKE.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...HIGH RIP CURRENT RISK...INZ001-INZ002...10 AM SATURDAY TO 10 AM
MONDAY.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563...2 PM SATURDAY TO 11
PM SATURDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...4 PM
SATURDAY TO MIDNIGHT MONDAY.
SMALL CRAFT ADVISORY...LMZ744-LMZ745...10 AM SATURDAY TO 10 AM
MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
351 PM CDT FRI SEP 21 2012
.MESOSCALE DISCUSSION...
300 PM CDT
CONTINUE TO MONITOR POTENTIAL FOR A COUPLE SEVERE STORMS ACROSS
THE SOUTHERN FORECAST AREA...PRIMARILY ALONG AND SOUTH OF U.S.
HIGHWAY 24.
STRONG WELL-ALIGNED UPPER AND MID LEVEL NORTHWESTERLY JETS
CONTINUE TO PROGRESS SOUTHEAST FROM IA WITH AN
ELONGATED SHORT WAVE...POSSIBLY TWO...IMPULSE FROM SOUTHERN MN
INTO SOUTHEAST IA. LATEST HAND SURFACE ANALYSIS DEPICTS A 1005 MB
SURFACE LOW NEAR PITTSFIELD IN WEST CENTRAL IL WITH STRONG
PRESSURE FALLS OF ALMOST 5 MB/3 HR IN ADVANCE. THIS IS WELL
ALIGNED WITH ROBUST LOW-LEVEL TD ADVECTION /8-14F CLIMBS PER
HOUR/ INTO THE MID TO UPPER 50S FROM SPI/TAZ SOUTHEASTWARD ACROSS
THE ILX CWA. THIS AREA HIGHLIGHTS WHERE THE DEVELOPING SURFACE
WARM FRONT IS AND LIKELY NEAR THE NORTHERN EXTENT OF ANY SURFACE-
BASED UPDRAFT POTENTIAL. DEW POINTS REMAIN LOW NORTH OF THIS
AREA...INCLUDING IN THE SOUTHERN FORECAST AREA WHERE NAMELY MID
40S PREVAIL ALONG WITH MORE OF AN EASTERLY WIND COMPONENT. WHILE
THE MOISTENING BOUNDARY LAYER IS MOVING NORTH QUICKLY IN ADVANCE
OF THE LOW...AT THIS TIME IT DOES NOT LOOK TO MAKE IT ALL THE WAY
TO THE SOUTHERN FORECAST AREA. SO THE MAIN CONCERNS REMAIN FOR
ELEVATED STORMS.
MID-LEVEL FLOW ANALYZED BY UPSTREAM PROFILES AND THE RAP MODEL OF
OVER 50 KT IS CONTRIBUTING TO DEEP LAYER SHEAR AT OR IN EXCESS OF
60 KT INTO CENTRAL IL. STRENGTHENING SOUTHERLY 850 MB FLOW AND
MOISTURE TRANSPORT AHEAD OF THE DEVELOPING LOW PRESSURE IS
FURTHERING THE CROSSOVER COMPONENT NEAR THE INTERSTATE 74 CORRIDOR
AND UP TO THE SOUTHERN CWA. INSTABILITY IS SOMEWHAT MEAGER...BUT
LIKELY UNDERDONE BY MOST GUIDANCE GIVEN THE CONVECTIVE
TRENDS...AND COULD BE NEAR 500 J/KG. TOGETHER THIS COULD SUPPORT
BRIEF ELEVATED SUPERCELLS OR POSSIBLY A SMALL ARC/CLUSTER OF
STORMS TRACKING ACROSS THE FAR SOUTHERN FORECAST AREA BETWEEN 4
AND 7 PM...CAPABLE OF MAINLY A HAIL THREAT.
MTF
&&
.DISCUSSION...
348 PM CDT
COOL THROUGH THE WEEKEND THEN TEMPERATURES MODERATE FIRST PART OF
NEXT WEEK. A SHORT BREAK IN THREAT OF RAIN THIS EVENING THEN
CHANCES RETURN OVERNIGHT THROUGH SAT MORNING.
MULTIPLE MINOR SHORT WAVES IN THE UPPER FLOW TURNING FROM SSE TO
SE AS THEY CROSS THE UPPER MIDWEST AND THEN SE TO ESE AS THEY
ROTATE ACROSS THE MID MS VALLEY AND THE WESTERN GREAT LAKES INTO
THE BASE OF THE UPPER TROUGH THE REST OF TODAY AND THIS EVENING.
FURTHER UPSTREAM OVER SOUTHERN MANITOBA IS A STRONGER SHORT WAVE
PROGGED TO REACH SOUTHERN WI BY 12Z SAT. AS THIS DISTURBANCE
APPROACHES LATE TONIGHT A CHANCE OF RAIN RETURNS
OVERNIGHT...ENDING MIDDAY WITH THIS SHORT WAVE TROUGH PROGGED TO
CONTINUE ON TO NORTHERN IND BY 18Z SAT. HIGHEST CHANCES WILL BE
ACROSS THE NE 1/2 OF THE FORECAST AREA...ALONG AND N OF THE
PROJECTED PATH OF THE VORT MAX.
IN THE WAKE OF THE SHORT WAVE/WAVES MOVING ACROSS THE AREA TODAY
WEAK LOW LEVEL COLD AIR ADVECTION TO TAKE PLACE. THIS...COMBINED
WITH EXPECTED SHOWERS AND EXTENSIVE CLOUDINESS...WILL KEEP
TEMPERATURES DURING SAT LIMITED TO THE UPPER 50S AND LOWER 60S.
WITH THE PASSAGE OF THE STRONGER SHORT WAVE DURING SAT MORNING
STRONGER COLD AIR ADVECTION TO TAKE PLACE WITH 850HPA
TEMPERATURES DROPPING TO AROUND 0C FOR THE AFTERNOON. DESPITE THE
COLD AIR ADVECTION SURFACE HEATING IS EXPECTED TO MITIGATE THE
COOLING AS CLOUDS CLEAR DURING THE DAY IN THE WAKE OF THE SHORT
WAVE.
A HIGH PRESSURE RIDGE IS TO BE BUILDING FROM THE NORTHERN PLAINS
ACROSS THE MO RIVER VALLEY DURING THE DAY SAT AND THE UPPER AND
MID MS VALLEY AND LOWER OH VALLEY DURING SAT NIGHT. CLEAR
SKIES...DEW POINTS IN THE MID 20S TO LOWER 30S...AND LACK OF
BOUNDARY LAYER MIXING AS SURFACE WINDS BECOME NIL ARE EXPECTED TO
LEAD TO SAT NIGHT LOWS IN THE LOWER AND MID 30S ACROSS MUCH OF
THE LOCAL FORECAST AREA. FROST A GOOD POSSIBILITY ACROSS THE W
AND SW PORTIONS OF THE FORECAST AREA...CLOSEST TO THE SURFACE
RIDGE AXIS...OVERNIGHT SAT AND EARLY SUN MORNING.
YET ANOTHER SHORT WAVE IS SHOWN BY MODELS DROPPING OVER THE UPPER
MIDWEST AND THE WESTERN GREAT LAKES DURING SUN. HOWEVER...WITH A
VERY DRY AIR MASS IN PLACE POPS ONLY IN THE SINGLE DIGITS. EVEN
CLOUDS WILL BE HARD TO COME BY WITH JUST SOME CIRRUS ASSOCIATED
WITH THE JET MAX MOVING OVERHEAD. WITH THE UPPER TROUGH
BROADENING OVER THE REGION AND THE CENTER OF THE CENTER OF THE
LARGE SCALE UPPER CYCLONE REESTABLISHING ITSELF OVER SOUTHERN
HUDSON BAY AND NW QUEBEC BY MON MORNING THE MID LATITUDE UPPER
FLOW BACKS TO OUT OF THE WNW. WITH THE UPPER LOW FURTHER NORTH
DISTURBANCES ROTATING AROUND IT WILL TRACK OVER THE NORTH WOODS
AND THE NORTHERN GREAT LAKES KEEPING CHANCES OF PRECIPITATION LOW
THROUGH MON NIGHT.
HOWEVER...A COLD FRONT IS PROGGED TO SLIP SE ACROSS THE LOCAL
AREA TUE AND TUE NIGHT BEFORE BECOMING STATIONARY FROM NE MO
ACROSS CENTRAL IL TO NORTHERN IND BY WED MORNING. INCREASING FLOW
FROM THE CENTRAL PLAINS ENE ACROSS THE MID MS VALLEY WILL RESULT
IN INCREASING WARM AIR ADVECTION AS WELL AS MID AND LOWER LEVEL
MOISTURE TRANSPORT INTO THE AREA WITH CHANCES OF SHOWERS AND
THUNDERSTORMS...MAINLY FOR THE N 1/2 TO 3/4 OF THE LOCAL FORECAST
AREA TUE THROUGH WED BEFORE A STRONG SHORT WAVE DROPPING ACROSS
THE UPPER MIDWEST AND WESTERN GREAT LAKES PUSHES THE SURFACE FRONT
FURTHER TO THE S AND ANOTHER LARGE SURFACE ANTICYCLONE BUILDS OVER
THE UPPER MIDWEST AND THE GREAT LAKES DURING WED AND WED NIGHT.
WED NIGHT THROUGH FRI WILL HAVE LOW POPS AS THE HIGH PRESSURE WILL
DOMINATE THE WEATHER OVER THE REGION...CONTINUING TO FEED COOL DRY
AIR ACROSS THE AREA.
TRS
.CLIMATE...
RECORD LOW SEP 23
CHICAGO 29 1995
ROCKFORD 29 1974
EARLIEST FIRST FREEZE DATE
CHICAGO SEP 22 1995 /32F/
ROCKFORD SEP 13 1975 /32F/
AVERAGE FIRST FREEZE DATE
CHICAGO OCT 15
ROCKFORD OCT 7
TRS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* VARIABLE WIND DIRECTIONS/SPEEDS THROUGH THE EVENING RUSH.
* OFF AND ON SHOWERS WITH POSSIBLE PERIODS OF LOWER CIGS/VSBYS.
LENNING
//DISCUSSION...UPDATED 18Z...
AN ACTIVE WEATHER PATTERN OVER THE NEXT 36 HOURS WILL BRING
MULTIPLE CONCERNS TO THOSE WITH AVIATION INTERESTS. A PAIR OF
UPPER LEVEL DISTURBANCES ARE MOVING OVER THE AREA THIS
AFTERNOON...AND BOTH IN TANDEM ARE HELPING TO BRING RAIN TO THE
AREA. WHILE THIS WAS MORE SHOWERY EARLIER...THIS IS LIKELY TO BE A
MORE PERSISTENT RAIN AT TAF SITES THIS AFTERNOON...ESPECIALLY
RFD...DPA...AND ORD. TEMPORARY MVFR VISIBILITIES HAVE BEEN SEEN
ACROSS SOUTHWEST WI WITHIN THE RAIN AREA...AND GIVEN THE MID-LEVEL
FORCING AND JUST OVERALL IMPRESSIVE DYNAMICS...WOULD NOT BE
SURPRISED TO SEE SOME OF THAT AND MAYBE EVEN BRIEF MVFR CIGS. A
SURFACE REFLECTION TO THE UPPER LEVEL WAVES WILL BE DEFINED IN A
LOW PRESSURE ACROSS WESTERN IL BY MID TO LATE AFTERNOON. THIS WILL
HELP TO EVOLVE THE WIND FIELD INTO MORE NORTHERLY ACROSS MOST OF
THE TAF SITES THAN ORIGINALLY THOUGHT...AND POTENTIALLY EVEN
NORTHEASTERLY BY LATE AFTERNOON AND EARLY EVENING. WIND SPEEDS
WILL LIKELY BE UNDER 10 KT DURING THAT PERIOD...THOUGH THEY MAY BE
CLOSE. SPEEDS WILL DROP TONIGHT AND THE DIRECTION SHOULD AGAIN
BECOME VARIABLE. ANOTHER VIGOROUS UPPER LEVEL DISTURBANCE WILL
MOVE OVER THE AREA SATURDAY MORNING LIKELY CREATING SHOWERS BUT IN
PARTICULAR BRINGING A SURGE OF STRONGER NORTHWEST WINDS AND COLDER
AIR. THIS WILL SET THE STAGE FOR WIND GUSTS IN THE 25-30 KT
BALLPARK FROM MID TO LATE MORNING SATURDAY INTO THE AFTERNOON. IN
ADDITION...COLD AIR ADVECTION STRATOCUMULUS WILL LIKELY BE MVFR
IMMEDIATELY BEHIND THE COLD FRONT SATURDAY MORNING AND GRADUALLY
RAISE THROUGH THE DAY.
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE REGARDING WINDS. EXPECT THEY WILL PROMPT SOME
REFUSALS FROM TIME TO TIME NO MATTER WHICH CONFIGURATION IS
USED. LATEST TRENDS SUGGEST THEY WOULD BE NORTHEASTERLY FOR A
WHILE THIS AFTERNOON...BUT STILL SOUTHWESTERLY JUST A COUPLE
THOUSAND FEET UP.
* MEDIUM TO HIGH CONFIDENCE OF STAYING ABOVE MVFR EXCEPT FOR BRIEF
PERIODS. NOT ANTICIPATING IFR THIS EVENING.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
* SATURDAY NIGHT THROUGH MONDAY...VFR.
* TUESDAY...CHANCE OF SHOWERS.
* WEDNESDAY...CHANCE OF THUNDERSTORMS SOUTH...OTHERWISE VFR.
* THURSDAY...VFR
MTF
&&
.MARINE...
230 PM CDT
LOW PRESSURE OVER THE UPPER GREAT LAKES WILL TRACK NORTHEAST
TOWARD HUDSON BAY OVERNIGHT TONIGHT AND THEN RAPIDLY DEEPEN
TOMORROW AS STRONG HIGH PRESSURE BUILDS ACROSS THE NORTHERN
PLAINS. A SERIES OF MID LEVEL IMPULSES WILL BRING REINFORCING
SHOTS OF COLD AIR OVER THE WESTERN GREAT LAKES TOMORROW. THE
RESULTANT STRONG COLD ADVECTION WILL LEAD TO RAPIDLY
STRENGTHENING NORTHERLY WINDS TOMORROW...LIKELY REACHING GALE
FORCE DURING THE AFTERNOON HOURS. THE PRESSURE GRADIENT AND COLD
ADVECTION WILL BE STRONGEST OVER THE FAR NORTHERN PORTIONS OF THE
LAKE...SO HAVE HOISTED A GALE WARNING FOR THE NORTHERN ONE-THIRD
OF THE LAKE. THE WINDOW OF OPPORTUNITY FOR THE STRONGEST WINDS
WILL BE DURING THE AFTERNOON AND EVENING HOURS WHEN HIGH PRESSURE
SPREADING INTO THE WESTERN GREAT LAKES SHOULD HELP ALLOW WINDS TO
SUBSIDE BELOW GALE FORCE. FOR THE SOUTHERN PORTIONS OF THE
LAKE...WINDS AND WAVES SHOULD QUICKLY RISE TO SMALL CRAFT
ADVISORY LEVELS TOMORROW AS WELL...WITH THE INDIANA WATERS
REACHING SMALL CRAFT ADVISORY LEVELS SOONER THAN THE ILLINOIS
WATERS...AND LINGERING LONGER...INTO MONDAY MORNING DUE TO THE
GENERALLY NORTHERLY FETCH SETTING UP OVER THE LAKE. BY MONDAY
AFTERNOON...ANOTHER DEEPENING LOW TRACKING JUST NORTH OF THE
GREAT LAKES MAY POSSIBLY BRING ANOTHER BRIEF PERIOD OF
SOUTHWESTERLY GALES TO THE FAR NORTHERN PORTION OF THE LAKE...
BUT WILL NOT ISSUE ANY HEADLINES AT THIS TIME SINCE THE STRENGTH
OF THE WINDS WILL BE HIGHLY DEPENDENT ON THE EXACT TRACK OF THE
LOW.
THE OTHER CONCERN FOR LAKE MICHIGAN WILL BE WATERSPOUT POTENTIAL.
LAKE SFC WATER TEMPERATURES REMAIN UNUSUALLY HIGH...WITH A
TEMPERATURE OF 17C AT THE NORTH BUOY AND 20C AT THE SOUTH BUOY
THIS AFTERNOON. WHEN THE MUCH COOLER AIR PLUNGES OVER LAKE
MICHIGAN...LAKE SFC TO 850MB DELTA-T VALUES WILL REACH AS HIGH AS
22-23C...INDICATIVE OF A VERY UNSTABLE ENVIRONMENT OVER LAKE
MICHIGAN. WHILE CONVERGENCE BOUNDARIES ARE NOT LIKELY OVER THE
LAKE...WATERSPOUT POTENTIAL WILL REMAIN HIGH DUE TO LAKE EFFECT
RAIN SHOWERS AND DEEP LAYER CONVECTIVE CLOUD DEVELOPMENT.
CONDITIONS WILL BE CONDUCIVE TO WATERSPOUTS FROM THIS EVENING
THROUGH MONDAY EVENING...ESPECIALLY FOR THE NORTHERN AND EASTERN
PORTIONS OF THE LAKE.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...HIGH RIP CURRENT RISK...INZ001-INZ002...10 AM SATURDAY TO 10 AM
MONDAY.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563...2 PM SATURDAY TO 11
PM SATURDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...4 PM
SATURDAY TO MIDNIGHT MONDAY.
SMALL CRAFT ADVISORY...LMZ744-LMZ745...10 AM SATURDAY TO 10 AM
MONDAY.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
307 PM CDT FRI SEP 21 2012
.MESOSCALE DISCUSSION...
300 PM CDT
CONTINUE TO MONITOR POTENTIAL FOR A COUPLE SEVERE STORMS ACROSS
THE SOUTHERN FORECAST AREA...PRIMARILY ALONG AND SOUTH OF U.S.
HIGHWAY 24.
STRONG WELL-ALIGNED UPPER AND MID LEVEL NORTHWESTERLY JETS
CONTINUE TO PROGRESS SOUTHEAST FROM IA WITH AN
ELONGATED SHORT WAVE...POSSIBLY TWO...IMPULSE FROM SOUTHERN MN
INTO SOUTHEAST IA. LATEST HAND SURFACE ANALYSIS DEPICTS A 1005 MB
SURFACE LOW NEAR PITTSFIELD IN WEST CENTRAL IL WITH STRONG
PRESSURE FALLS OF ALMOST 5 MB/3 HR IN ADVANCE. THIS IS WELL
ALIGNED WITH ROBUST LOW-LEVEL TD ADVECTION /8-14F CLIMBS PER
HOUR/ INTO THE MID TO UPPER 50S FROM SPI/TAZ SOUTHEASTWARD ACROSS
THE ILX CWA. THIS AREA HIGHLIGHTS WHERE THE DEVELOPING SURFACE
WARM FRONT IS AND LIKELY NEAR THE NORTHERN EXTENT OF ANY SURFACE-
BASED UPDRAFT POTENTIAL. DEW POINTS REMAIN LOW NORTH OF THIS
AREA...INCLUDING IN THE SOUTHERN FORECAST AREA WHERE NAMELY MID
40S PREVAIL ALONG WITH MORE OF AN EASTERLY WIND COMPONENT. WHILE
THE MOISTENING BOUNDARY LAYER IS MOVING NORTH QUICKLY IN ADVANCE
OF THE LOW...AT THIS TIME IT DOES NOT LOOK TO MAKE IT ALL THE WAY
TO THE SOUTHERN FORECAST AREA. SO THE MAIN CONCERNS REMAIN FOR
ELEVATED STORMS.
MID-LEVEL FLOW ANALYZED BY UPSTREAM PROFILES AND THE RAP MODEL OF
OVER 50 KT IS CONTRIBUTING TO DEEP LAYER SHEAR AT OR IN EXCESS OF
60 KT INTO CENTRAL IL. STRENGTHENING SOUTHERLY 850 MB FLOW AND
MOISTURE TRANSPORT AHEAD OF THE DEVELOPING LOW PRESSURE IS
FURTHERING THE CROSSOVER COMPONENT NEAR THE INTERSTATE 74 CORRIDOR
AND UP TO THE SOUTHERN CWA. INSTABILITY IS SOMEWHAT MEAGER...BUT
LIKELY UNDERDONE BY MOST GUIDANCE GIVEN THE CONVECTIVE
TRENDS...AND COULD BE NEAR 500 J/KG. TOGETHER THIS COULD SUPPORT
BRIEF ELEVATED SUPERCELLS OR POSSIBLY A SMALL ARC/CLUSTER OF
STORMS TRACKING ACROSS THE FAR SOUTHERN FORECAST AREA BETWEEN 4
AND 7 PM...CAPABLE OF MAINLY A HAIL THREAT.
MTF
&&
//PREV DISCUSSION...
338 AM CDT
SYNOPSIS...AN UPPER LEVEL TROUGH WILL REMAIN CENTERED OVER THE
WESTERN GREAT LAKES THROUGH SATURDAY...WITH LOBES OF ENERGY
ROTATING AROUND IT. AS SUCH...LOOKING AT A VERY COOL AND RAINY END
TO THE WORK WEEK. THE TROUGH AXIS SHIFTS EAST LATE THIS WEEKEND
WITH A SECOND TROUGH SINKING SOUTH INTO ONTARIO ON TUESDAY. THIS
SECOND TROUGH REMAINS NORTH OF THE CWA ALLOWING SOUTHWEST WINDS TO
USHER IN MORE SEASONAL TEMPS BY TUESDAY. THE UPPER LEVEL TROUGH
SINKS SOUTH INTO THE CWA LATE NEXT WEEK RESULTING IN ANOTHER ROUND
OF SHOWERS AND BELOW NORMAL TEMPS.
TODAY THROUGH SATURDAY...
AN UPPER LEVEL JET STREAK REMAINS OVER THE NORTHERN PLAINS...WITH
ITS LEFT JET EXIT REGION SETTING UP OVER NORTHEASTERN IOWA. AT THE
SAME TIME AN UPPER LEVEL SHORTWAVE CURRENTLY IN EAST CENTRAL MN
BASED ON WV IMAGERY...WILL SLIDE THROUGH CENTRAL WI THIS MORNING.
SHOWERS HAVE ALREADY DEVELOPED ALONG THE NOSE OF THE JET AND
SHORTWAVE THIS MORNING...AND EXPECTING THE SHOWERS TO MOVE INTO THE
RFD AREA BY MID MORNING AND SPREAD EASTWARD. THE GREATEST CHANCE
FOR PRECIP WILL BE ALONG THE IL/WI STATE LINE WHERE FORCING LOOKS TO
BE MAXIMIZED. SHOWERS ARE EXPECTED NORTH OF I-80...AND SOME COULD
BE HEAVY AT TIMES.
A WEAK SURFACE LOW OVER EASTERN SOUTH DAKOTA WILL SINK SOUTH AND
STRENGTHEN OVER MISSOURI THIS AFTERNOON. CONVECTION WITH THIS LOW
LOOKS MORE LIKELY SOUTH OF THE CWA...BUT INCREASED POPS ALONG AND
SOUTH OF THE I-80 CORRIDOR LATE THIS AFTERNOON WITH THERE BEING A
GOOD CHANCE SOME OF THE SHRA THAT FORM OUT AHEAD OF THE LOW WILL
CROSS INTO THE CWA. MODEL SOUNDINGS ARE NOT IMPRESSIVE WITH
REGARDS TO THUNDER...THEREFORE WENT WITH JUST SHOWERS. THIS
SOUTHERN SYSTEM MAY ALSO AFFECT THE RAIN SHOWERS TO THE NORTH.
DEPENDING ON HOW STRONG THE LOW GETS AND HOW SIGNIFICANT THE SHRA
AND TSRA ARE OUT AHEAD OF IT...THERE IS A CHANCE THAT THE SOUTHERN
SYSTEM COULD STEAL MOISTURE FROM THE SHRA ALONG THE IL/WI BORDER.
THIS MAY TURN INTO A HIGH POP/LOW QPF SITUATION DEPENDING ON HOW
THINGS DEVELOP. ALL IN ALL...THE BEST CHANCE FOR MEASURABLE PRECIP
THROUGH TONIGHT REMAINS NORTH OF THE I-80 CORRIDOR...ESPECIALLY
ALONG THE IL/WI BORDER.
RAIN TRANSITIONS EASTWARD WITH THE SHORTWAVE IN THE EVENING AND
OVERNIGHT. WITH THE UPPER LEVEL JET LYING JUST SOUTH OF THE
CWA...ANOTHER CHILLY NIGHT IS EXPECTED WITH OUTLYING AREAS IN THE
LOW TO MID 40S...AND AROUND 50 DOWNTOWN.
A COLD FRONT APPROACHES FROM THE NORTHWEST EARLY SATURDAY
BRINGING ANOTHER CHANCE OF RAIN. THE UPPER LEVEL JET WEAKENS AS
THE FRONT ARRIVES...RESULTING IN LESS SYNOPTIC SUPPORT THAN
FRIDAYS RAIN. FORCING AND MOISTURE ALONG THE FRONT ALSO DIMINISH
AS THE FRONT PASSES THROUGH NORTHERN ILLINOIS. HOWEVER...EXPECTING
MEASURABLE PRECIP NORTH OF A LA SALLE-FOWLER LINE FROM THE PREDAWN
HOURS THROUGH THE MID AFTERNOON HOURS. BY EVENING THE FRONT WILL
BE THROUGH THE WITH NORTHWEST WINDS AND A STRONG PUSH OF COLD AIR.
BROUGHT LOW TEMPS DOWN BY A FEW DEGREES ACROSS THE BOARD FOR
SATURDAY NIGHT. GUIDANCE SUGGESTS CLEARING SKIES AND THE 850 HPA
0 DEGREE ISOTHERM WILL BE SOUTH OF THE CWA BY 12Z
SUNDAY...THEREFORE HAVE TEMPS IN OUTLYING AREAS IN THE 30S AND
TEMPS AROUND 40 DOWNTOWN. AREAS PRONE TO SLIGHTLY COLDER TEMPS
LIKE AURORA AND ROCHELLE MAY DIP BELOW FREEZING. EXPECTING FROST
TO DEVELOP ALONG AND NORTH OF THE I-80 AND OUTSIDE OF THE CHICAGO
METRO AREA. WILL HOLD OFF ON ANY FROST RELATED HEADLINES NOW SINCE
NOT SURE HOW MUCH OF THE CWA IS STILL GROWING OR SENSITIVE TO
FROST GIVEN THIS SUMMERS DROUGHT. NOT TO MENTION SOIL TEMPS ARE
STILL RELATIVELY WARM FOR THIS TIME OF YEAR...WHICH MAY RESULT IN
FROST DEVELOPING ON ELEVATED SURFACES SUCH AS
ROOFS...VEHICLES...AND HANGING PLANTS.
SUNDAY THROUGH TUESDAY...
HIGH PRESSURE MOVES IN SUNDAY AND BY MONDAY SOUTHWEST WINDS RETURN.
TEMPS SLOWLY WARM WITH SUNDAY NIGHT LOOKING LIKE ANOTHER NIGHT IN
THE UPPER 30S IN OUTLYING AREAS. HIGH TEMPS ON MONDAY WILL BE BELOW
AVERAGE BUT IN THE MID 60S.
A SURFACE LOW FORMS OVER THE MID MISSISSIPPI RIVER VALLEY TUESDAY
AFTERNOON WITH A CHANCE OF SHRA ACROSS MOST OF THE CWA TUESDAY AND
TUESDAY NIGHT. MODEL SOUNDINGS DO NOT LOOK FAVORABLE FOR CONVECTION
AT THIS TIME. TUESDAY LOOKS LIKE THE WARMEST DAY WITH NEAR NORMAL
TEMPS IN THE 70S.
WEDNESDAY AND THURSDAY...
THE UPPER LEVEL TROUGH BEGINS TO SINK SOUTH INTO WISCONSIN TUESDAY
NIGHT INTO WEDNESDAY. A COLD FRONT PASSES SOUTH THROUGH THE CWA ON
WEDNESDAY RESULTING IN A CHANCE OF SHOWERS. THERE IS NOT A SIGNIFICANT
PUSH OF COOL AIR BEHIND THE FRONT...THEREFORE TEMPS FOR LATE NEXT
WEEK LOOK ONLY SLIGHTLY BELOW NORMAL.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* VARIABLE WIND DIRECTIONS/SPEEDS THROUGH THE EVENING RUSH.
* OFF AND ON SHOWERS WITH POSSIBLE PERIODS OF LOWER CIGS/VSBYS.
LENNING
//DISCUSSION...UPDATED 18Z...
AN ACTIVE WEATHER PATTERN OVER THE NEXT 36 HOURS WILL BRING
MULTIPLE CONCERNS TO THOSE WITH AVIATION INTERESTS. A PAIR OF
UPPER LEVEL DISTURBANCES ARE MOVING OVER THE AREA THIS
AFTERNOON...AND BOTH IN TANDEM ARE HELPING TO BRING RAIN TO THE
AREA. WHILE THIS WAS MORE SHOWERY EARLIER...THIS IS LIKELY TO BE A
MORE PERSISTENT RAIN AT TAF SITES THIS AFTERNOON...ESPECIALLY
RFD...DPA...AND ORD. TEMPORARY MVFR VISIBILITIES HAVE BEEN SEEN
ACROSS SOUTHWEST WI WITHIN THE RAIN AREA...AND GIVEN THE MID-LEVEL
FORCING AND JUST OVERALL IMPRESSIVE DYNAMICS...WOULD NOT BE
SURPRISED TO SEE SOME OF THAT AND MAYBE EVEN BRIEF MVFR CIGS. A
SURFACE REFLECTION TO THE UPPER LEVEL WAVES WILL BE DEFINED IN A
LOW PRESSURE ACROSS WESTERN IL BY MID TO LATE AFTERNOON. THIS WILL
HELP TO EVOLVE THE WIND FIELD INTO MORE NORTHERLY ACROSS MOST OF
THE TAF SITES THAN ORIGINALLY THOUGHT...AND POTENTIALLY EVEN
NORTHEASTERLY BY LATE AFTERNOON AND EARLY EVENING. WIND SPEEDS
WILL LIKELY BE UNDER 10 KT DURING THAT PERIOD...THOUGH THEY MAY BE
CLOSE. SPEEDS WILL DROP TONIGHT AND THE DIRECTION SHOULD AGAIN
BECOME VARIABLE. ANOTHER VIGOROUS UPPER LEVEL DISTURBANCE WILL
MOVE OVER THE AREA SATURDAY MORNING LIKELY CREATING SHOWERS BUT IN
PARTICULAR BRINGING A SURGE OF STRONGER NORTHWEST WINDS AND COLDER
AIR. THIS WILL SET THE STAGE FOR WIND GUSTS IN THE 25-30 KT
BALLPARK FROM MID TO LATE MORNING SATURDAY INTO THE AFTERNOON. IN
ADDITION...COLD AIR ADVECTION STRATOCUMULUS WILL LIKELY BE MVFR
IMMEDIATELY BEHIND THE COLD FRONT SATURDAY MORNING AND GRADUALLY
RAISE THROUGH THE DAY.
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE REGARDING WINDS. EXPECT THEY WILL PROMPT SOME
REFUSALS FROM TIME TO TIME NO MATTER WHICH CONFIGURATION IS
USED. LATEST TRENDS SUGGEST THEY WOULD BE NORTHEASTERLY FOR A
WHILE THIS AFTERNOON...BUT STILL SOUTHWESTERLY JUST A COUPLE
THOUSAND FEET UP.
* MEDIUM TO HIGH CONFIDENCE OF STAYING ABOVE MVFR EXCEPT FOR BRIEF
PERIODS. NOT ANTICIPATING IFR THIS EVENING.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
* SATURDAY NIGHT THROUGH MONDAY...VFR.
* TUESDAY...CHANCE OF SHOWERS.
* WEDNESDAY...CHANCE OF THUNDERSTORMS SOUTH...OTHERWISE VFR.
* THURSDAY...VFR
MTF
&&
.MARINE...
230 PM CDT
LOW PRESSURE OVER THE UPPER GREAT LAKES WILL TRACK NORTHEAST
TOWARD HUDSON BAY OVERNIGHT TONIGHT AND THEN RAPIDLY DEEPEN
TOMORROW AS STRONG HIGH PRESSURE BUILDS ACROSS THE NORTHERN
PLAINS. A SERIES OF MID LEVEL IMPULSES WILL BRING REINFORCING
SHOTS OF COLD AIR OVER THE WESTERN GREAT LAKES TOMORROW. THE
RESULTANT STRONG COLD ADVECTION WILL LEAD TO RAPIDLY STRENGTHENING
NORTHERLY WINDS TOMORROW...LIKELY REACHING GALE FORCE DURING THE
AFTERNOON HOURS. THE PRESSURE GRADIENT AND COLD ADVECTION WILL BE
STRONGEST OVER THE FAR NORTHERN PORTIONS OF THE LAKE...SO HAVE
HOISTED A GALE WARNING FOR THE NORTHERN ONE-THIRD OF THE LAKE. THE
WINDOW OF OPPORTUNITY FOR THE STRONGEST WINDS WILL BE DURING THE
AFTERNOON AND EVENING HOURS WHEN HIGH PRESSURE SPREADING INTO THE
WESTERN GREAT LAKES SHOULD HELP ALLOW WINDS TO SUBSIDE BELOW GALE
FORCE. FOR THE SOUTHERN PORTIONS OF THE LAKE...WINDS AND WAVES
SHOULD QUICKLY RISE TO SMALL CRAFT ADVISORY LEVELS TOMORROW AS
WELL...WITH THE INDIANA WATERS REACHING SMALL CRAFT ADVISORY
LEVELS SOONER THAN THE ILLINOIS WATERS...AND LINGERING
LONGER...INTO MONDAY MORNING DUE TO THE GENERALLY NORTHERLY FETCH
SETTING UP OVER THE LAKE. BY MONDAY AFTERNOON...ANOTHER DEEPENING
LOW TRACKING JUST NORTH OF THE GREAT LAKES MAY POSSIBLY BRING
ANOTHER BRIEF PERIOD OF SOUTHWESTERLY GALES TO THE FAR NORTHERN
PORTION OF THE LAKE...BUT WILL NOT ISSUE ANY HEADLINES AT THIS
TIME SINCE THE STRENGTH OF THE WINDS WILL BE HIGHLY DEPENDENT ON
THE EXACT TRACK OF THE LOW.
THE OTHER CONCERN FOR LAKE MICHIGAN WILL BE WATERSPOUT POTENTIAL.
LAKE SFC WATER TEMPERATURES REMAIN UNUSUALLY HIGH...WITH A
TEMPERATURE OF 17C AT THE NORTH BUOY AND 20C AT THE SOUTH BUOY
THIS AFTERNOON. WHEN THE MUCH COOLER AIR PLUNGES OVER LAKE
MICHIGAN...LAKE SFC TO 850MB DELTA-T VALUES WILL REACH AS HIGH AS
22-23C...INDICATIVE OF A VERY UNSTABLE ENVIRONMENT OVER LAKE
MICHIGAN. WHILE CONVERGENCE BOUNDARIES ARE NOT LIKELY OVER THE
LAKE...WATERSPOUT POTENTIAL WILL REMAIN HIGH DUE TO LAKE EFFECT
RAIN SHOWERS AND DEEP LAYER CONVECTIVE CLOUD DEVELOPMENT.
CONDITIONS WILL BE CONDUCIVE TO WATERSPOUTS FROM THIS EVENING
THROUGH MONDAY EVENING...ESPECIALLY FOR THE NORTHERN AND EASTERN
PORTIONS OF THE LAKE.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...HIGH RIP CURRENT RISK...INZ001-INZ002...10 AM SATURDAY TO 10 AM
MONDAY.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563...2 PM SATURDAY TO 11
PM SATURDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...4 PM
SATURDAY TO MIDNIGHT MONDAY.
SMALL CRAFT ADVISORY...LMZ744-LMZ745...10 AM SATURDAY TO 10 AM
MONDAY.
&&
$$
AREA FORECAST DISCUSSION...CORRECTION
NWS LINCOLN IL
300 PM CDT FRI SEP 21 2012
.DISCUSSION...
ISSUED 300 PM CDT FRI SEP 21 2012
SHORT TERM...TODAY THROUGH MONDAY
INITIAL CONCERN IS SLIGHT RISK OF SEVERE STORMS INTO EARLY EVENING
MAINLY EAST OF THE IL RIVER. SHORT RANGE MODELS FAIRLY SIMILAR
THROUGH MON WITH STRONG UPPER LEVEL TROF DIGGING SOUTHWARD INTO
THE GREAT LAKES AND OHIO VALLEY REGION BY SAT WITH BELOW NORMAL
TEMPS EXPECTED THIS WEEKEND. PATCHY FROST STILL A POSSIBILITY OVER
THE IL RIVER VALLEY LATER SAT NIGHT AND IN EASTERN IL LATER SUNDAY
NIGHT. MET AND MAV GUIDANCE TEMPS SIMILAR THROUGH SUNDAY NIGHT AND
STAYED FAIRLY CLOSE TO.
MID AFTERNOON SURFACE MAP SHOWS 1006 MB LOW PRESSURE DEEPENING
ALONG THE EASTERN IA/MO BORDER WITH ITS WARM FRONT LIFTING
NORTHWARD TOWARD I-74...AS ENE WINDS TURN SOUTH WITH ITS PASSAGE AND
DEWPOINTS IN THE UPPER 30S AND 40S RISE INTO THE MID TO UPPER 50S.
TEMPS RISING AS WELL INTO THE UPPER 70S AND LOWER 80S IN SW IL IN
WARM SECTOR WHERE ALSO MORE SUNSHINE. SOME INSTABILITY WITH CAPES
PEAKING FROM 1000-1500 J/KG EAST OF THE IL RIVER THIS AFTERNOON
WITH INCREASING WIND SHEAR AS WELL DURING MID/LATE AFTERNOON INTO
EARLY EVENING AS 35-40KT WSW LOW LEVEL JET WHILE ALSO GETTING
STRONGER THAN 80-100 KT JET ALOFT DIVING SE INTO IL LATE TODAY
ALONG WITH A SHORT WAVE MOVING INTO CENTRAL IL FROM IA LATE TODAY.
VGP PARMETERS ARE FAVORABLE FOR ISOLATED TORNADOES IN SE IL LATE
THIS AFTERNOON/EARLY EVENING. SO CONCUR WITH SPC/S UPGRADE TO A
SLIGHT RISK OF SEVERE STORMS FROM MID AFTERNOON INTO EARLY EVENING
MAINLY SE OF THE IL RIVER. SPC HAS 15% RISK OF LARGE HAIL AND
DAMAGING WIND GUSTS ALONG WITH 5% RISK OF TORNADOES.
LOW PRESSURE DEEPENS A BIT MORE TO 1005 MB AND DIVES SE INTO SW IL
BY SUNSET AND THEN TURN NE ACROSS THE OHIO RIVER THIS EVENING.
RUC13 AND HRRR MODELS KEEP HEALTHY CHANCES OF SHOWERS AND
THUNDERSTORMS OVER EASTERN IL THROUGH MID EVENING AND THEN
DIMINISH BY LATE EVENING AND TRENDED FORECAST IN THAT DIRECTION.
WESTERN IL SHOULD BE DRY THIS EVENING WITH CONVECTION EAST OF
THERE. LOWS TONIGHT RANGE FROM THE LOWER 40S NW OF THE IL RIVER TO
THE LOWER 50S SE OF I-70 IN SE IL.
UNSEASONABLY STRONG 533 DM 500 MB DOUBLE BARREL LOW OVER NW
ONTARIO TO CONTINUE DIGGING SOUTHWARD INTO THE GREAT LAKES AND
OHIO VALLEY TONIGHT/SAT WHILE SENDING A STRONG SHORT WAVE FROM
LAKE WINNIPEG SE INTO EASTERN IA/NORTHERN IL/SW WI BY SUNRISE SAT
AND INTO NORTHERN INDIANA BY 18Z/1 PM SAT. CONTINUE 20% CHANCE OF
SHOWERS LATE TONIGHT NORTH OF PEORIA AND 20-30% CHANCE NE OF I-74
SAT MORNING ALONG WITH GUSTS NORTH WINDS UP TO 30 MPH NE AREAS.
HIGHS AROUND 60F FROM I-74 NE SAT AND MID 60S IN SE IL AND SW OF
SPRINGFIELD.
1026 MB HIGH PRESSURE OVER SASKETCHEWAN TO BUILD INTO THE EASTERN
PLAINS SUNDAY AND RETURN LIGHER WINDS TO THE AREA BUT CONTINUE
COOL WEATHER. FROST IS LIKELY OVER THE IL RIVER VALLEY LATER SAT
NIGHT WITH LOWS IN THE MID 30S. APPEARS SHY OF RECORD LOWS AROUND
30F EARLY SUNDAY MORNING SEP 23 BUT NEAR FREEZING TEMPS POSSIBLE
IN NW IL NW OF KNOX AND STARK COUNTIES. PATCHY FROST IS POSSIBLE
OVER EASTERN IL LATER SUNDAY NIGHT WITH LOW IN THE MID TO UPPER
30S AS SURFACE HIGH DRIFTS OVER CENTRAL/SE IL AND EVENTUALLY INTO
THE OHIO RIVER VALLEY BY DAWN MON. HIGHS SUNDAY STAYING COOL IN THE
LOW TO MID 60S DESPITE A FAIR AMOUNT OF SUNSHINE.
LONG TERM...MONDAY NIGHT THROUGH FRIDAY
UNSETTLED WEATHER PATTERN TAKING SHAPE LATER MON NIGHT THROUGH MID
WEEK AS SEVERAL SHORT WAVES WILL EJECT FROM THE CENTRAL PLAINS
TOWARD IL AND ALSO HAVE A FRONTAL BOUNDARY MOVING SOUTHWARD AND
POSSIBLY LINGERING NEAR CENTRAL/SE IL FOR A FEW DAYS DURING
MIDWEEK. THIS WILL KEEP CHANCES FOR SHOWERS AND THUNDERSTORMS
AROUND FOR A FEW DAY BUT THINK GFS IS LINGERING QPF TOO LONGER
INTO LATE WEEK AND LEANED TOWARD THE FURTHER SOUTH ECWMF MODEL
WITH THE FRONT BY THU/FRI. GENERALLY STAYED CLOSE TO ALLBLEND POPS
DURING NEXT WORK WEEK AND LINGERED SLIGHT CHANCES SOUTHERN AREAS
AROUND THU. TEMPERATURES TO WARM BACK TO NORMAL BY TUE AND COOLING
OFF FROM NORTH TO SOUTH LATER NEXT WEEK AND COULD BE MORE OF A
TEMPERATURE CONTRAST THAN WHAT ALLBLEND IS SHOWING DURING 2ND HALF
OF NEXT WEEK DEPENING ON POSITION OF FRONTAL BOUNDARY.
KH
&&
.AVIATION...
ISSUED 1238 PM CDT FRI SEP 21 2012
FEW SCATTERED STORMS BEGINNING TO DEVELOP...AND SHOULD INCREASE
DURING THE AFTERNOON. WINDS WILL SHIFT AS THE LOW IS PROGGED TO
CROSS THE AREA THROUGH THE EVENING. KEPT VCTS IN THE TAFS AT THIS
TIME...AND WILL HAVE TO WATCH FOR LOWER CEILING DEVELOPMENT LATER
WITH THE STORM FORMATION.
GOETSCH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
259 PM CDT FRI SEP 21 2012
.DISCUSSION...
ISSUED 225 PM CDT FRI SEP 21 2012
SHORT TERM...TODAY THROUGH MONDAY
INITIAL CONCERN IS SLIGHT RISK OF SEVERE STORMS INTO EARLY EVENING
MAINLY EAST OF THE IL RIVER. SHORT RANGE MODELS FAIRLY SIMILAR
THROUGH MON WITH STRONG UPPER LEVEL TROF DIGGING SOUTHWARD INTO
THE GREAT LAKES AND OHIO VALLEY REGION BY SAT WITH BELOW NORMAL
TEMPS EXPECTED THIS WEEKEND. PATCHY FROST STILL A POSSIBILITY OVER
THE IL RIVER VALLEY LATER SAT NIGHT AND IN EASTERN IL LATER SUNDAY
NIGHT.
MID AFTERNOON SURFACE MAP SHOWS 1006 MB LOW PRESSURE DEEPENING
ALONG THE EASTERN IA/MO BORDER WITH ITS WARM FRONT LIFTING
NORTHWARD TOWARD I-74...AS ENE WINDS TURN SOUTH WITH ITS PASSAGE AND
DEWPOINTS IN THE UPPER 30S AND 40S RISE INTO THE MID TO UPPER 50S.
TEMPS RISING AS WELL INTO THE UPPER 70S AND LOWER 80S IN SW IL IN
WARM SECTOR WHERE ALSO MORE SUNSHINE. SOME INSTABILITY WITH CAPES
PEAKING FROM 1000-1500 J/KG EAST OF THE IL RIVER THIS AFTERNOON
WITH INCREASING WIND SHEAR AS WELL DURING MID/LATE AFTERNOON INTO
EARLY EVENING AS 35-40KT WSW LOW LEVEL JET WHILE ALSO GETTING
STRONGER THAN 80-100 KT JET ALOFT DIVING SE INTO IL LATE TODAY
ALONG WITH A SHORT WAVE MOVING INTO CENTRAL IL FROM IA LATE TODAY.
VGP PARMETERS ARE FAVORABLE FOR ISOLATED TORNADOES IN SE IL LATE
THIS AFTERNOON/EARLY EVENING. SO CONCUR WITH SPC/S UPGRADE TO A
SLIGHT RISK OF SEVERE STORMS FROM MID AFTERNOON INTO EARLY EVENING
MAINLY SE OF THE IL RIVER. SPC HAS 15% RISK OF LARGE HAIL AND
DAMAGING WIND GUSTS ALONG WITH 5% RISK OF TORNADOES.
LOW PRESSURE DEEPENS A BIT MORE TO 1005 MB AND DIVES SE INTO SW IL
BY SUNSET AND THEN TURN NE ACROSS THE OHIO RIVER THIS EVENING.
RUC13 AND HRRR MODELS KEEP HEALTHY CHANCES OF SHOWERS AND
THUNDERSTORMS OVER EASTERN IL THROUGH MID EVENING AND THEN
DIMINISH BY LATE EVENING AND TRENDED FORECAST IN THAT DIRECTION.
WESTERN IL SHOULD BE DRY THIS EVENING WITH CONVECTION EAST OF
THERE. LOWS TONIGHT RANGE FROM THE LOWER 40S NW OF THE IL RIVER TO
THE LOWER 50S SE OF I-70 IN SE IL.
UNSEASONABLY STRONG 533 DM 500 MB DOUBLE BARREL LOW OVER NW
ONTARIO TO CONTINUE DIGGING SOUTHWARD INTO THE GREAT LAKES AND
OHIO VALLEY TONIGHT/SAT WHILE SENDING A STRONG SHORT WAVE FROM
LAKE WINNIPEG SE INTO EASTERN IA/NORTHERN IL/SW WI BY SUNRISE SAT
AND INTO NORTHERN INDIANA BY 18Z/1 PM SAT. CONTINUE 20% CHANCE OF
SHOWERS LATE TONIGHT NORTH OF PEORIA AND 20-30% CHANCE NE OF I-74
SAT MORNING ALONG WITH GUSTS NORTH WINDS UP TO 30 MPH NE AREAS.
HIGHS AROUND 60F FROM I-74 NE SAT AND MID 60S IN SE IL AND SW OF
SPRINGFIELD.
1026 MB HIGH PRESSURE OVER SASKETCHEWAN TO BUILD INTO THE EASTERN
PLAINS SUNDAY AND RETURN LIGHER WINDS TO THE AREA BUT CONTINUE
COOL WEATHER. FROST IS LIKELY OVER THE IL RIVER VALLEY LATER SAT
NIGHT WITH LOWS IN THE MID 30S. APPEARS SHY OF RECORD LOWS AROUND
30F EARLY SUNDAY MORNING SEP 23 BUT NEAR FREEZING TEMPS POSSIBLE
IN NW IL NW OF KNOX AND STARK COUNTIES. PATCHY FROST IS POSSIBLE
OVER EASTERN IL LATER SUNDAY NIGHT WITH LOW IN THE MID TO UPPER
30S AS SURFACE HIGH DRIFTS OVER CENTRAL/SE IL AND EVENTUALLY INTO
THE OHIO RIVER VALLEY BY DAWN MON. HIGHS SUNDAY STAYING COOL IN THE
LOW TO MID 60S DESPITE A FAIR AMOUNT OF SUNSHINE.
LONG TERM...MONDAY NIGHT THROUGH FRIDAY
UNSETTLED WEATHER PATTERN TAKING SHAPE LATER MON NIGHT THROUGH MID
WEEK AS SEVERAL SHORT WAVES WILL EJECT FROM THE CENTRAL PLAINS
TOWARD IL AND ALSO HAVE A FRONTAL BOUNDARY MOVING SOUTHWARD AND
POSSIBLY LINGERING NEAR CENTRAL/SE IL FOR A FEW DAYS DURING
MIDWEEK. THIS WILL KEEP CHANCES FOR SHOWERS AND THUNDERSTORMS
AROUND FOR A FEW DAY BUT THINK GFS IS LINGERING QPF TOO LONGER
INTO LATE WEEK AND LEANED TOWARD THE FURTHER SOUTH ECWMF MODEL
WITH THE FRONT BY THU/FRI. GENERALLY STAYED CLOSE TO ALLBLEND POPS
DURING NEXT WORK WEEK AND LINGERED SLIGHT CHANCES SOUTHERN AREAS
AROUND THU. TEMPERATURES TO WARM BACK TO NORMAL BY TUE AND COOLING
OFF FROM NORTH TO SOUTH LATER NEXT WEEK AND COULD BE MORE OF A
TEMPERATURE CONTRAST THAN WHAT ALLBLEND IS SHOWING DURING 2ND HALF
OF NEXT WEEK DEPENING ON POSITION OF FRONTAL BOUNDARY.
KH
&&
.AVIATION...
ISSUED 1238 PM CDT FRI SEP 21 2012
FEW SCATTERED STORMS BEGINNING TO DEVELOP...AND SHOULD INCREASE
DURING THE AFTERNOON. WINDS WILL SHIFT AS THE LOW IS PROGGED TO
CROSS THE AREA THROUGH THE EVENING. KEPT VCTS IN THE TAFS AT THIS
TIME...AND WILL HAVE TO WATCH FOR LOWER CEILING DEVELOPMENT LATER
WITH THE STORM FORMATION.
GOETSCH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
138 PM CDT FRI SEP 21 2012
.UPDATE...
A SIGNIFICANT CHANGE HAS BEEN MADE TO THE FCST.
CONVECTIVE TEMPERATURE HAS BEEN ACHIEVED IN THE SOUTHERN PART OF
THE CWFA WITH TSRA DEVELOPMENT IN THE PAST HR. RAP TRENDS INDICATE
CONVECTION IS DEVELOPING ALONG A THETA E GRADIENT WITH STRONG
LIFT. THUS A NARROW LINE OF CONVECTION WILL MOVE GENERALLY EAST
THROUGH MID AFTERNOON AFFECTING AREAS SOUTH OF I-80 AND EAST OF
THE MISSISSIPPI.
THE LIGHT RAIN WILL CONTINUE MOVING EAST THROUGH MID AFTERNOON AND
ALL BUT THE FAR NORTHEAST AND EAST PARTS SHOULD BE RAIN FREE BY
MID AFTERNOON.
TEMPERATURES WILL RESPOND APPROPRIATELY WITH THE RAIN ENDING. THE
EXTREME SOUTHERN PARTS OF THE CWFA MAY HIT 80 BEFORE THE END OF
THE DAY. ..08..
&&
.AVIATION...
TSRA HAS DEVELOPED ALONG THE MISSISSIPPI RIVER AND IS MOVING EAST.
KBRL SHOULD NOT SEE ANY TSRA AND THE TSRA SHOULD REMAIN SOUTH OF
KMLI. OTHERWISE VFR WX IS EXPECTED TO CONTINUE THROUGH 00Z/22 WITH
WINDS BECOMING LIGHT. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1152 AM CDT FRI SEP 21 2012
.UPDATE...
ANOTHER UPDATE HAS BEEN DONE TO THE FCST TO REFLECT CURRENT TRENDS.
A WEAK LOW WAS IN CENTRAL IOWA NEAR KDSM AT 15Z WITH A WARM FRONT
EXTENDING SOUTHEAST THROUGH THE FAR SOUTHERN PARTS OF THE CWFA.
THE RAIN HAS DEVELOPED A MESO HIGH AROUND KDBQ WHICH IS RESULTING
IN STRONGER WINDS IN THE I-80 TO HWY 30 CORRIDOR IN THE WESTERN CWFA.
TRENDS FROM THE RAP SHOW THE WEAK LOW PASSING JUST SOUTH OF THE
CWFA WITH THE MESO HIGH MOVING EAST ALONG THE WI/IL BORDER THROUGH
THE AFTERNOON. FORCING IN THE 700-600MB LAYER CONTINUES TO DEPICT
THE LIGHT RAIN REASONABLY WELL. THIS FORCING MOVES EAST DURING THE
AFTERNOON WITH CONDENSATION PRESSURE DEFICITS RISING. THUS THE
RAIN WILL BE ENDING BY EARLY AFTERNOON IN THE FAR WESTERN CWFA
WITH ALL BUT THE EASTERN THIRD TURNING DRY BY MID AFTERNOON.
TEMPERATURES WILL BE INTERESTING TODAY. UNTIL THE RAIN
ENDS...TEMPERATURES WILL REMAIN IN THE 50S. ONCE THE RAIN DOES END
TEMPERATURES WILL BEGIN TO RECOVER. AREAS SOUTH OF AN KOTM TO KGBG
LINE WILL NOT SEE ANY RAIN TODAY AND WILL BE IN THE WARM SECTOR
WITH READINGS IN THE 70S. ..08..
&&
.AVIATION...
THE RAIN ACROSS EASTERN IOWA AND WI/IL HAS CREATED AN AREA OF HIGH
PRESSURE AROUND KDBQ. A WEAK LOW WEST OF KDSM WILL MOVE INTO
NORTHEAST MISSOURI AND ILLINOIS THROUGH 00Z/22. THE RAIN WILL END
FROM WEST TO EAST WITH ALL TAF SITES BEING RAIN FREE BY 00Z/22.
VFR CIGS ARE EXPECTED IN THE RAIN. LIGHT WINDS ARE EXPECTED FOR A
TIME AFT 00Z/22 WHICH MAY ALLOW SOME MVFR VSBYS TO DVLP. A COLD
FRONT WILL ARRIVE AFT 06Z/22 BRINGING A THREAT OF MORE RAIN.
HOWEVER...VFR CONDITIONS ARE EXPECTED TO CONTINUE. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
920 AM CDT FRI SEP 21 2012
.UPDATE...
AN UPDATE HAS BEEN DONE TO THE FCST TO REFLECT CURRENT TRENDS.
BASED ON RADAR TRENDS AND INPUT FROM THE RAP MODEL...POPS HAVE
BEEN ADJUSTED AND INCREASED IN SOME AREAS FOR THE MORNING HOURS.
THE RAP AGREES WITH THE 12Z SOUNDING IN THAT MOST OF THE
CONVERGENCE AND FORCING IS IN THE 700-600MB LAYER WITH AREAS BELOW
750MB REMAINING QUITE DRY.
AS SUCH THERE SHOULD BE INTERMITTENT SPRINKLES ACROSS THE AREA
WITH POCKETS OF RAIN THIS MORNING. THE FORCING MOVES EAST DURING
THE AFTERNOON SO THERE SHOULD BE A GENERAL TREND OF PRECIPITATION
ENDING FROM WEST TO EAST DURING THE AFTERNOON HOURS.
TEMPERATURES WILL BE HIGHLY DEPENDENT UPON CLOUDS/PRECIP TODAY AND
READINGS ARE EXPECTED TO REMAIN IN THE 50S THROUGH THE MORNING.
SOME RECOVERY SHOULD BE SEE DURING THE AFTERNOON ONCE THE RAIN
ENDS WITH THE WESTERN CWFA HAVING THE BEST CHANCE AT GETTING INTO
THE LOWER 60S. ..08..
&&
.PREV DISCUSSION... /ISSUED 643 AM CDT FRI SEP 21 2012/
AVIATION... /ISSUED 308 AM CDT FRI SEP 21 2012/
VFR WX TO CONTINUE THROUGH 12Z/22. A SHORTWAVE WILL DROP SOUTHEAST
ACROSS THE AREA EARLY THIS MORNING AND INTO FRIDAY. IT WILL BRING
AN AREA OF -RA SWEEPING ACROSS THE AREA THIS MORNING FROM
NORTHWEST TO SOUTHEAST ENDING IN EASTERN IA APPROXIMATELY 21Z.
CLOUD BASES TO STAY AOA 4KFT WITH VISIBILITIES 6SM OR BETTER.
WINDS TO GRADUALLY TURN FROM SOUTHEAST EARLY THIS MORNING BECOMING EAST
TO NORTHEAST BY MID DAY FRIDAY AS THE SURFACE LOW MOVES SOUTHEAST
FROM IOWA INTO MISSOURI SOUTHWEST OF THE TERMINALS. WIND SPEEDS
SHOULD INCREASE INTO THE 10-15KT RANGE ABOUT MID DAY...BEFORE
DIMINISHING AGAIN. A COLD FRONT WILL ARRIVE LATE TONIGHT INTO
EARLY SATURDAY MORNING WITH NORTH WINDS BECOMING GUSTY BEHIND THE
FRONT. THERE WILL BE ANOTHER ROUND OF SCATTERED -RA MAINLY NORTH
OF INTERSTATE 80 ASSOCIATED WITH THIS FRONT.
HAASE
PREV DISCUSSION... /ISSUED 308 AM CDT FRI SEP 21 2012/
SYNOPSIS...
DEEP TROUGH 2 TO 3 STANDARD DEVIATIONS FROM NORMAL SITUATED FROM
ABOUT JAMES BAY TO THE UPPER MIDWEST/GREAT LAKES. A SERIES OF
SHORT WAVE TROUGHS WAS ROTATING AROUND THE MAIN VORTEX. ONE OF
THESE WAVES WAS PRODUCING LIGHT RAIN ACROSS SOUTHERN MN AND
NORTHERN IA AND WAS MOVING SOUTHEAST. MOST OF THE VISIBILITIES IN
THIS AREA OF RAIN HAS BEEN ABOUT 10 MILES AS THE LOW LEVELS ARE
RATHER DRY. THIS DRY AIR WAS NOTED ON THE KDVN/KMSP 00Z/21
SOUNDINGS. A SIGNIFICANT WAVE AND REINFORCING COLD FRONT WAS
MOVING RAPIDLY SOUTHWARD IN MANITOBA WHERE TEMPERATURES THERE ARE
IN THE 30S. MEANWHILE...CURRENT TEMPERATURES IN THE DVN CWA RANGED
FROM 42 AT DUBUQUE TO 59 AT FORT MADISON. LIGHT RAIN WAS NOTED AT
INDEPENDENCE AT 3 AM WITH THE VISIBILITY AT 10 MILES.
HAASE
SHORT TERM...TODAY AND TONIGHT...
FORECAST FOCUS MAINLY ON RAIN CHANCES AND TEMPERATURES.
TODAY...LIGHT RAIN WILL SPREAD INTO OUR NORTHERN CWA THIS MORNING
AND HAVE RAISED POPS TO LIKELY. FORECAST SOUNDINGS SUGGEST LOW
LEVELS MOISTEN UP AND CONDENSATION PRESSURE DEFICITS LOWER
SIGNIFICANTLY THIS MORNING. OPERATIONAL MODELS FAVOR THE BULK OF
THE RAIN IN OUR NORTH WITH ONLY CHANCE POPS TO THE SOUTH. THIS
WAVE MOVES QUICKLY OFF TO THE EAST THIS AFTERNOON WITH THE RAIN
ENDING FROM WEST TO EAST. THE RAIN AND CLOUDS SHOULD HOLD
TEMPERATURES THIS AFTERNOON ONLY IN THE LOWER TO MID 60S NORTH.
HOWEVER EXPECTING A BIT MORE SUNSHINE IN THE FAR SOUTH AND HAVE
RAISED MAX TEMPS INTO THE LOWER 70S.
TONIGHT...SHOULD BE A DRY EVENING BUT THEN A POTENT SHORT WAVE AND
REINFORCING COLD FRONT WILL BE ARRIVING AFTER MIDNIGHT. THE MAIN
ENERGY APPEARS TO REMAIN TO THE NORTH IN MN AND WI BUT OUR
NORTHERN CWA DOES GET GRAZED SO WILL KEEP THE RAIN CHANCES GOING THERE.
THE SOUTHERN CWA SHOULD REMAIN DRY. WITH THE PASSAGE OF THE COLD
FRONT WINDS WILL TURN NORTH AND BECOME GUSTY TOWARDS MORNING.
MINIMUM TEMPERATURES WILL BE ABOUT 40 TO 45.
HAASE
LONG TERM...SATURDAY THROUGH THURSDAY...
THE LARGE UPPER TROF COVERING MOST OF THE EASTERN U.S. AND CANADA
WILL CONTINUE TO FEED COLD CANADIAN AIR INTO THE REGION OVER THE
WEEKEND. A SHORTWAVE CURRENTLY OVER NORTHERN MANITOBA WILL DIVE
SOUTH AND MOVE JUST NORTHEAST OF THE FORECAST AREA SATURDAY MORNING.
FORCING WITH THE WAVE IS PROGGED TO BRUSH THE FAR NORTHEAST
COUNTIES SO LOW CHANCE POPS NORTHEAST STILL LOOK REASONABLE
ESPECIALLY WITH THE LIMITED MOISTURE THE SYSTEM WILL HAVE TO WORK
WITH. THE SYSTEM WILL SWEEP THROUGH THE AREA QUICKLY AND SHOULD BE
WELL EAST OF THE CWFA BY 18Z WITH SUBSIDENCE IN PLACE THROUGH THE
AFTERNOON...SO THE POPS WERE REMOVED AFTER 18Z.
THIS S/W WILL DRAG ANOTHER RE-ENFORCING SHOT OF COLD AIR INTO THE
MID MISSISSIPPI VALLEY SATURDAY NIGHT. H8 TEMPS ARE PROGGED TO
DROP INTO THE 0 TO -2C RANGE OVER THE NORTHEAST HALF OF THE CWFA
BY 12Z SUNDAY. BY LATE SATURDAY NIGHT THE SURFACE RIDGE WILL BE
JUST WEST OF THE CWFA ALLOWING NORTH WINDS TO DIMINISH TO LESS
THAN 5 MPH. CLEAR SKIES ARE ALSO EXPECTED AND MODEL SURFACE
DEWPOINTS ARE PROGGED TO BE ANYWHERE FROM THE MID 20S PER THE 00Z
NAM TO THE LOWER 30S WITH MOST OF THE SOLUTIONS CLUSTERED AROUND
30. EVEN IF THE HIGH END OF THE DEWPOINT RANGE VERIFIES THIS
SHOULD BE LOW ENOUGH FOR WINDS TO DECOUPLE ALLOWING TEMPERATURES
TO DROP INTO THE LOW TO MID 30S. IF THE LOWER NAM DEWPOINTS VERIFY
THEN SOME UPPER 20S IN THE LOW SPOTS OVER THE NORTH ARE NOT OUT OF
THE QUESTION. THE PREVIOUS FORECAST HAD MINS IN THE 30 TO 35 RANGE
WHICH...AT THIS POINT...LOOK REASONABLE AND ARE WITHIN ONE DEGREE
OF RECORD LOWS FOR THE 23RD. CONDITIONS CONTINUE TO LOOK FAVORABLE
LATE SATURDAY NIGHT/SUNDAY MORNING FOR A WIDESPREAD FROST OVER
THE MOST OF THE AREA AS WELL AS A FREEZE OVER THE NORTH HALF TO
ONE THIRD.
THE SURFACE HIGH WILL MOVE THROUGH THE CWFA SUNDAY AND SUNDAY
NIGHT. RETURN FLOW WILL DEVELOP WEST OF THE MISSISSIPPI RIVER BY
LATE SUNDAY BUT THE EAST WILL REMAIN IN THE GRIP OF THE HIGH
THROUGH MONDAY MORNING. THIS SHOULD ALLOW TEMPERATURES EAST OF
MISSISSIPPI RIVER TO DROP BACK INTO THE MID 30S SUNDAY NIGHT WITH
THE LIGHT SOUTHERLY FLOW WEST OF THE RIVER KEEPING MINS IN THE
UPPER 30S TO AROUND 40.
THE REST OF THE WEEK SHOULD SEE THE UPPER FLOW OVER THE REGION
FLATTENING SOME AS THE UPPER TROF TAKES UP RESIDENCE OVER THE
GREAT LAKES AND NEW ENGLAND STATES. AT THE SAME TIME THE WEST
COAST RIDGE BREAKS DOWN IN RESPONSE TO PACIFIC ENERGY MOVING INTO
THE CENTRAL PLAINS. THE COMBINATION OF A COLD AIRMASS OVER THE
GREAT LAKES AND WARM AIR MOVING NORTH AHEAD OF THE WESTERN S/W WILL
SET UP A DECENT BAROCLINIC ZONE OVER THE MIDWEST FOR THE MID TO
LATE WEEK. THE 00Z GFS/ECMWF ARE IN GOOD AGREEMENT DEVELOPING A
WARM FRONT NEAR OR SOUTH OF THE CWFA BY LATE TUESDAY AND KEEPING
IT CLOSE BY THROUGH THURSDAY. WITH THE BOUNDARY IN THE AREA LOW
POPS FAVORING THE SOUTH TUESDAY THROUGH THURSDAY LOOK REASONABLE.
TEMPERATURES MID TO LATE WEEK SHOULD BE NEAR TO JUST BELOW NORMAL.
DLF
CLIMATE...
RECORD LOWS FOR SEPTEMBER 23...
BURLINGTON 33 1913
CEDAR RAPIDS 30 1989
DUBUQUE 31 1974
MOLINE 31 1995
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
937 PM CDT SAT SEP 22 2012
.UPDATE...
ISSUED AT 930 PM CDT SAT SEP 22 2012
THE FORECAST WAS UPDATED TO INCLUDE A SLIGHT CHANCE OF SHOWERS
WITH AN ISOLATED THUNDERSTORM MAINLY 06Z-15Z...TIED TO A NORTHWEST
TO SOUTHEAST AXIS OF LOWER-MID LEVEL FRONTOGENESIS (PARTICULARLY
800-700MB LAYER). LATEST NAM12 MODEL SOLUTION SUGGESTS 150-300
J/KG OF MUCAPE WITHIN THE ZONE OF STRONGEST WARM FRONTOGENESIS A
750MB...FROM TRIBUNE TO GARDEN CITY TO ASHLAND...SO A FEW
LIGHTNING STRIKES WILL ALSO BE POSSIBLE. THE 3KM HRRR HAS SHOWN A
RUN-TO-RUN CONSISTENCY IN GENERATING SHOWERS ALONG THIS
FRONTOGENETIC ZONE. SHOWERS WILL SHIFT TO THE EAST BY DAYBREAK
INTO SOUTH CENTRAL KS/NORTH CENTRAL OK WITH POPS DIMINISHING IN
THE GRIDS BY MID-MORNING SUNDAY.
&&
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 248 PM CDT SAT SEP 22 2012
THE MAIN FORECAST CHALLENGES ARE INCREASING CLOUDS TONIGHT AND A FEW
SPRINKLES, THEN HIGH TEMPERATURES ON SUNDAY AHEAD OF A WARM FRONT.
MODELS IN AGREEMENT WITH MOVING A COLD UPPER LEVEL TROUGH SLOWLY
EASTWARD ACROSS THE UPPER MIDWEST INTO SUNDAY WITH NORTHWEST FLOW
ALOFT CONTINUING OVER THE CENTRAL PLAINS. AS THE UPPER TROUGH
MOVES EAST, A RIDGE OF COOLER SURFACE HIGH PRESSURE WILL SLOWLY
PROGRESS EASTWARD FROM THE MISSOURI VALLEY INTO THE MID
MISSISSIPPI VALLEY ALLOWING A WARM FRONT TO PUSH NORTH INTO
EASTERN COLORADO TO JUST SOUTH OF ELKHART AND INTO CENTRAL
OKLAHOMA ON SUNDAY AFTERNOON. MID AND UPPER LEVEL MOISTURE AND
CLOUDINESS IS ALSO FORECAST TO INCREASE AROUND AND AFTER MIDNIGHT
ACROSS WESTERN KANSAS AS WEAK 800-700MB FRONTOGENESIS AND
ISENTROPIC LIFT EVOLVE ALOFT AHEAD OF THE SURFACE WARM FRONT. DEEP
MOISTURE AND CAPE ARE LACKING FOR ELEVATED THUNDERSTORMS, HOWEVER
COULD BE ENOUGH LIFT FOR SOME LIGHT SHOWERS OR SPRINKLES MAINLY IN
THE FORM OF VIRGA. WILL KEEP A SILENT POP GOING AFTER MIDNIGHT
TONIGHT WITH INCREASING CLOUDINESS.
FOR TONIGHT LOOK FOR INCREASING CLOUDINESS WITH SOUTHEAST WINDS
DECREASING TO 10 TO 15 MPH. OVERNIGHT LOWS WILL RANGE FROM THE LOWER
40S FROM DIGHTON TO SAINT JOHN AND NORTH TO THE MID AND UPPER 40S
ELSEWHERE. THESE TEMPS ARE A FEW DEGREES WARMER THAN CURRENT
GUIDANCE DUE TO CLOUDINESS EXPECTED. THEN FOR SUNDAY, MODELS
CONTINUE TO SHOW INCREASING UPPER LEVEL MOISTURE IN THE FORM OF
CIRRUS CLOUDS. HIGH TEMPERATURES WERE LOWERED A FEW DEGREES FROM
PREVIOUS FORECAST WITH EXPECTED HIGH LEVEL CLOUDINESS AND
SOUTHEASTERLY UPSLOPE FLOW AHEAD OF THE WARM FRONT. WINDS LOOK TO
INCREASE TO 15 TO 25 MPH BY LATE MORNING INTO THE AFTERNOON WITH
HIGHS FROM THE MID 70S NORTH OF A GARDEN CITY TO DODGE CITY TO
MEDICINE LODGE LINE AND WARMER LOW TO MID 80S SOUTH.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 329 PM CDT SAT SEP 22 2012
FORECAST CHALLENGES LIE AHEAD THROUGH THE MIDDLE OF THE WEEK WITH
REGARD TO PRECIPITATION AND CONVECTIVE CHANCES AND TO A LESSER
EXTENT TEMPERATURES.
WARMER OVERNIGHT LOWS WILL BE EXPECTED ON SUNDAY NIGHT AS A BETTER
AS WARMER BOUNDARY LAYER AIR ADVECTS INTO SW KANSAS AHEAD OF THE
EASTERN COLORADO TROUGH AND PANHANDLES SURFACE LOW. MONDAY SHOULD
REMAIN DRY AND WARMING ACROSS THE SOUTHERN HALF OF WESTERN KANSAS.
SOUTH CENTRAL KANSAS COULD BE THE WARMEST INTO TUESDAY, AS A SURFACE
LOW REMAINS QUASI-STATIONARY OR SLOWLY EAST DURING THE TIMEFRAME.
ALTHOUGH THE ATMOSPHERE WOULD BE CONDITIONALLY UNSTABLE, THE LOW`
CONVERGENCE REGIONS IN AND OF ITSELF MIGHT NOT BE ENOUGH TO SET OFF
SHOWERS AND THUNDERSTORMS. A BETTER CATALYST APPEARS IN THE MODELS
IN THE FORM OF SHORTWAVES BEGINNING AS EARLY AS TUESDAY OR TUESDAY
EVENING. WEAK LOW AMPLITUDE TROUGHING WILL REMAIN IN PLACE OVER THE
WESTERN STATES AND INTO THE CENTRAL ROCKIES DURING THIS PERIOD WHICH
WILL ALLOW OPPORTUNITIES FOR MULTIPLE SHORTWAVE IMPULSES TO INFLUENCE
WESTERN AND CENTRAL KANSAS. BY THE MIDDLE OF THE WEEKEND, NEGATIVE
VORTICITY ADVECTION AND INCREASED SUBSIDENCE SHOULD BEGIN TO
MAKE AN IMPACT AND ELIMINATE CHANCES FOR SHOWERS OR STORMS.
TEMPERATURES WILL REMAIN SEASONAL THROUGH THE PERIOD, GENERALLY IN
THE LOW 80S TO UPPER 70S.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 641 PM CDT SAT SEP 22 2012
AN EAST TO SOUTHEAST WIND WILL REMAIN 12 TO 15 KNOTS THROUGH MOST
OF THE EVENING AND OVERNIGHT HOURS...MAINLY FOR DDC AND GCK
TERMINALS. WINDS WILL FALL TO AROUND 5 KNOTS FARTHER NORTH AT HYS
CLOSER TO THE CENTER OF THE SURFACE HIGH (WHICH WILL BE MOVING
SOUTH THROUGH THE EASTERN DAKOTAS AND NEBRASKA THROUGH TONIGHT).
THERE IS A VERY SLIGHT CHANCE FOR LIGHT RAIN SHOWERS AFFECTING
DDC OR GCK TERMINALS DURING THE OVERNIGHT HOURS TONIGHT...BUT LACK
OF MOISTURE AND LARGE SCALE UPWARD VERTICAL MOTION WILL PREVENT
ANY WIDESPREAD PRECIPITATION AND CONFIDENCE IS NOT HIGH ENOUGH TO
INTRODUCE A MENTION OF PRECIPITATION IN THE TAFS, SO WILL BE
KEEPING THEM DRY FOR TONIGHT.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 45 76 53 83 / 20 20 0 0
GCK 46 76 52 83 / 20 10 0 0
EHA 49 85 59 89 / 10 10 0 0
LBL 47 84 56 89 / 10 10 0 0
HYS 42 74 52 76 / 10 10 0 0
P28 46 76 56 92 / 20 20 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...UMSCHEID
SHORT TERM...KRUSE
LONG TERM...RUSSELL
AVIATION...UMSCHEID
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
848 PM EDT SAT SEP 22 2012
.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA TONIGHT AND EARLY SUNDAY. HIGH
PRESSURE RETURNS FOR THE FIRST HALF OF NEXT WEEK. ANOTHER COLD
FRONT MOVES ACROSS THE REGION EARLY THURSDAY...FOLLOWED BY HIGH
PRESSURE BUILDING IN FROM THE NORTH LATE THURSDAY AND FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
SURFACE COLD FRONT CONTINUES MOVING EASTWARD TOWARD WESTERN VA. CU
FIELD BEGINNING TO INCREASE ALONG/JUST EAST OF THE MTNS...ALTHOUGH
NO SHWRS/TSTMS HAVE DVLPD ATTM. EXPECT A NARROW BAND OF
SHWRS/ISOLATED TSTMS TO DEVELOP ALONG/JUST AHD OF FRONT BY 20-21Z
JUST WEST OF CWA...THEN MOVE STEADILY EWD ACROSS CWA THROUGH 06Z.
BOTH HRRR AND RUC SUGGEST AN INCREASE IN AREAL COVERAGE OF
PRECIPITATION OVER PREVIOUS FORECAST...PRIMARILY SRN PTNS OF CWA. SO
HAVE INCREASED POPS A BIT ACROSS PTNS OF SE VA/NE NC. SPC
MESOANALYSIS PAGE SUGGESTS SFC CAPE IN TO 1000-1500 J/KG RANGE...BUT
MIXED LAYER CAPE BARELY REACHES 1000 J/KG. THUS...DO NOT SEE A LOT OF
TSTM ACTVTY OCCURRING..AND HAVE MAINTAINED ISOLATED WORDING IN
GRIDS/TEXT PRODUCTS. ENOUGH OF AN INVERTED V SHAPE TO LOWEST
PART OF SOUNDINGS TO SUGGEST ANY TSTMS COULD BE ACCOMPANIED BY
GUSTY WINDS. SVR THREAT...HWVR...APPEARS SMALL. MIN TEMPS LITTLE
CHANGED FROM PREVIOUS FORECAST...WITH MOST INLAND AREAS DROPPING
INTO THE 50S...AND CSTL SECTIONS IN THE 60-65 RANGE.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
DRY WEATHER AND MOSTLY CLR SKIES ANTICIPATED SUN/MON AS HIGH
PRESSURE MOVES INTO REGION FROM THE MIDWEST. ANY PRECIP ASSOCIATED
WITH COLD FRONT EXPECTED TO BE OFFSHORE AND OUT OF THE AREA BY
12Z. MAX TEMPS SUN AROUND 70 NW SECTIONS TO MID 70S PTNS NE NC. A
LITTLE COOLER MONDAY WITH MOST AREAS IN THE 70-74 RANGE. MIN TEMPS
BOTH SUN/MON NIGHTS MAINLY IN THE 40S UNDER CLR SKIES/LIGHT WINDS.
DEEPER WARM ADVECTION AHEAD OF MIDWEST TROF WILL CAUSE AN INCREASE
IN MID/HIGH CLOUDS ON TUESDAY. THESE CLOUDS WILL KEEP MAX TEMPS
FROM REACHING POTENTIAL WRN/CNTRL SECTIONS OF CWA..ALTHOUGH ALL
AREAS EXPECTED TO GET INTO THE LOW/MID 70S.
DRIER AIR COMING INTO AREA...ALONG WITH DECENT DAYTIME MIXING...WILL
FAVOR AFTERNOON SURFACE DEW POINTS A FEW DEGREES LOWER THAN
GUIDANCE...AND HAVE GONE CLOSE TO NAM MIXED LAYER DEW POINTS EACH
AFTERNOON SUNDAY THROUGH TUESDAY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
THE LAST HALF OF THE UPCOMING WEEK LOOKS TO BE MAINLY DRY WITH NEAR
TO SLIGHTLY ABOVE NORMAL TEMPERATURES. A DEEP UPPER LEVEL LOW OVER
EASTERN CANADA WILL SWING A TROUGH THROUGH THE NORTHEASTERN STATES.
UPPER LEVEL RIDGING OVER WESTERN CANADA WILL SHIFT EAST AND THE
RESULT WILL BE INCREASING 50H HEIGHTS OVER THE SOUTHEASTERN STATES
LATE NEXT WEEK.
MODELS ARE IN FAIRLY GOOD AGREEMENT WITH BRINGING A COLD FRONT
THROUGH THE MID ATLANTIC STATES EARLY THURSDAY...ABOUT 6 TO 12 HOURS
EARLIER THAN THEY DID FRIDAY. DUE TO THE AFOREMENTIONED RIDGING TO
OUR SW...THE FRONT WILL HAVE MINIMAL EFFECT ON PCPN OR COOLING. THE
WARMEST DAY APPEARS TO BE WEDNESDAY BUT TEMPERATURES AT 85H ONLY
FALL SLIGHTLY BEHIND THE FRONT THURSDAY AND FRIDAY. MOISTURE WILL BE
LIMITED ALONG THE FRONT AND KEPT POPS AOB 20 PERCENT THROUGH THE
PERIOD.
HIGH TEMPERATURES IN THE UPR 70S TO LWR 80S WEDNESDAY AND COOL
SLIGHTLY TO THE MID 70S TO AROUND 80 THURSDAY. CLOUD COVER FROM WEAK
SHORT WAVES AND POSSIBLY SOME UPSLOPE LOW LEVEL FLOW MAY HOLD
TEMPERATURES DOWN A BIT FRIDAY AND SATURDAY AND KEPT HIGHS IN THE
70S.
FORECAST LOWS RANGE FROM THE 50S INLAND TO THE LOWER 60S NEAR THE
COAST THROUGH THE PERIOD.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
AS OF 00Z...A LINE OF SHOWERS AND TSTMS ASSOCIATED WITH A PRE
FRONTAL TROUGH IS MOVING ACROSS SOUTH CENTRAL VA. IF THE LINE
HOLDS TOGETHER...A BRIEF PERIOD OF HEAVY PRECIP AND GUSTY 25KT WINDS
MAY IMPACT KPHF AND KORF AROUND 03/04Z. EXPECT CLEARING CONDITIONS
AS A COLD FRONT CROSSES THE FA OVERNIGHT...TURNING WINDS TO THE NW
AND THEN N. HIGH PRESSURE NUDGES E FOR SUN CREATING VFR CONDITIONS.
VFR CONDITIONS WILL PERSIST AS HIGH PRESSURE CONTINUES TO BUILD IN
FROM THE W MON INTO TUE.
&&
.MARINE...
SCA IN EFFECT FOR ALL OF THE WATERS TNGT AND EARLY SUNDAY AS A
NORTHERLY SURGE DEVELOPS BEHIND A STRONG COLD FRONT. SEAS WERE
APPROACHING 5 FT AT BUOY 09 AND KEPT SCA NORTH OF PARRAMORE ISLAND
THAT BEGINS AT 21Z. THE REST OF THE WATERS EXCEPT CURRITUCK SOUND
HAVE SCA BEGIN AT 00Z. MOST OF THE SCA CONDITIONS SHOULD HOLD OFF
UNTIL AFTER FRONTAL PASSAGE...BETWEEN 03 AND 06Z AND CONTINUE INTO
THE COASTAL WATERS BETWEEN 06 AND 09Z. SCA BEGINS OVER CURRITUCK
SOUND AT 06Z.
WINDS INCREASE FROM THE NORTH TO BETWEEN 20 AND 25 KNOTS OVER THE
BAY AND COASTAL WATERS BEFORE DIMINISHING IN THE LATE MORNING.
CURRENT SCA IN EFFECT OVER BAY AND INLAND WATERS UNTIL 18Z MAY BE
LIFTED PRIOR TO THAT.
THE SCA FOR THE COASTAL WATERS SUNDAY AFTN WILL BE MAINLY PREDICATED
ON THE SUSTAINING OF 5 FT SEAS WHICH IS QUESTIONABLE AT THIS POINT.
CURRENT GRIDS HAVE 5 FT SEAS CONTINUING THROUGH 12Z MONDAY.
A SECONDARY SURGE IS EXPECTED MONDAY MORNING...MAINLY SUPPORTED BY
MOS GUIDE AND A TIGHTENING OF THE PRESSURE GRADIENT. IT APPEARS
THAT MOST OF THE IMPACT OF THIS SURGE WILL BE OVER THE SOUTHERN
COASTAL WATERS. THE NEED FOR AN SCA IS UNCERTAIN AT THIS TIME.
QUIET MARINE CONDITIONS ARE EXPECTED FOR MUCH OF THE UPCOMING WEEK
BEYOND MONDAY.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EDT SUNDAY FOR ANZ630>632-
634>638.
SMALL CRAFT ADVISORY FROM 2 AM TO 2 PM EDT SUNDAY FOR ANZ633.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT SUNDAY FOR ANZ650-652-654-
656-658.
&&
$$
SYNOPSIS...LSA/WRS
NEAR TERM...WRS
SHORT TERM...WRS
LONG TERM...LSA
AVIATION...DAP
MARINE...LSA
AREA FORECAST DISCUSSION...UPDATED
NWS PITTSBURGH PA
445 AM EDT FRI SEP 21 2012
.SYNOPSIS...
A WEAKENING COLD FRONT WILL SLOWLY PUSH EASTWARD INTO THE REGION
TODAY. A LOW PRESSURE SYSTEM WILL CROSS OHIO TONIGHT INTO EARLY
SATURDAY AND RETURN SHOWERS TO MUCH OF THE AREA. THE COLD FRONT WILL
SHIFT EAST OF THE AREA BY LATE IN THE DAY ON SATURDAY, WITH A
CANADIAN AIR MASS BUILDING INTO THE AREA FOR SUNDAY INTO MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A BROAD 500MB TROUGH
CENTERED ACROSS THE UPPER MIDWEST WITH THE UPPER OHIO VALLEY IN A
SOUTHWESTERLY FLOW AHEAD OF THIS FEATURE. A PLUME OF MID-LEVEL
MOISTURE IS ADVECTING ACROSS THE AREA. AT THE SURFACE, A COLD
FRONT EXTENDS FROM MICHIGAN SOUTHWESTWARD ACROSS INDIANA AND HAS
SLOWED AS IT TRANSVERSES ACROSS THE OHIO VALLEY.
TODAY...THE COLD FRONT WILL SLIDE ACROSS OHIO AND BECOME MORE POORLY
DEFINED AS IT ENTERS WESTERN PA THIS EVENING. A FEW SHOWERS ARE
NOT OUT OF THE QUESTION AS WEAK FORCING FROM THE FRONT PUSHES INTO
THE AREA THIS AFTERNOON. HOWEVER, GFS/NAM MODEL SOUNDINGS INDICATE
A LAYER OF RELATIVELY DRY AIR IN THE 1000-850MB LAYER INHIBITING
THE DEVELOPMENT OF SHOWERS. WITH THIS IN MIND, HAVE GONE WITH SCHC
POPS EARLY THIS AFTERNOON, INCREASING TO CHC POPS NORTH AND WEST OF
PITTSBURGH BY 00Z AS THE LOWER LEVELS BECOME SATURATED.
TONIGHT...A WEAK SURFACE LOW IS PROGGED TO MOVE ALONG AND JUST NORTH
OF THE OHIO RIVER, ALLOWING FOR WARM AIR ADVECTION TO OCCUR OVER
MUCH OF THE OHIO VALLEY OVERNIGHT. AS THE LOW LIFTS NORTHEASTWARD INTO
EASTERN OHIO NEAR DAWN, POPS RAMP UP FROM CHC TO LIKELY WITH THE
BEST FORCING TO THE NW OF PITTSBURGH. CHANCE POPS ARE FORECAST
ELSEWHERE. IN WAA OVERNIGHT, TEMPS WILL ONLY DROP INTO THE MID TO
UPPER 50S ACROSS MOST OF THE AREA.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
GFS/ECMWF ARE IN REASONABLE AGREEMENT WITH THE MID-LEVEL SYNOPTIC
FEATURES THROUGH THIS PERIOD WITH MORE DIFFICULTY IN RESOLVING THE
SURFACE FRONTAL BOUNDARY. WITH SOME UNCERTAINTY IN ITS TRACK, THE
AFOREMENTIONED LOW IS PROGGED TO WEAKEN INTO A SURFACE TROUGH AS
IT PUSHES INTO THE AREA ON SATURDAY. THUS, LIKELY POPS CONTINUE
NORTH AND WEST OF PITTSBURGH WITH CHC POPS SOUTHWARD. WITH THE
FRONT IN THE VICINITY OF THE AREA, A CLOUDY DAY IS ANTICIPATED AND
THIS ALONG WITH SHOWERS SHOULD LIMIT HIGHS TO AROUND 5 DEGREES
BELOW SEASONAL NORMALS ON SATURDAY.
THE CANADIAN AIR MASS BEHIND THE FRONT WON`T BEGIN TO ADVECT INTO
THE AREA UNTIL LATE ON SATURDAY INTO SATURDAY NIGHT. IT WILL BE A
SHORT WAVE CURRENTLY DROPPING SOUTHWARD INTO MANITOBA THAT WILL
SWING AROUND THE BASE OF THE TROUGH AND FINALLY KICK THE FRONT
EAST OF THE AREA BY 06Z ON SUNDAY. THIS FEATURE WILL ALLOW FOR
LIKELY POPS AS IT CROSSES AREAS NORTH OF PITTSBURGH SATURDAY
NIGHT.
THE AREA WILL BE IN COLD AIR ADVECTION ON SUNDAY INTO SUNDAY NIGHT
IN THE WAKE OF THE FRONT. WITH THIS IN MIND, CHC POPS CONTINUE
ACROSS LOCATIONS NORTH OF PITTSBURGH THROUGHOUT THE DAY. COOLEST
TEMPS ARE FORECAST IN THIS WINDOW WITH HIGHS 10 DEGREES BELOW NORMAL
SUNDAY AND 10-15 DEGREES BELOW NORMAL SUNDAY NIGHT. PATCHY FROST
IS FORECAST TO DEVELOP NEAR DAWN ACROSS THE EASTERN RIDGES AS
CLEARING OCCURS BY EARLY MONDAY MORNING. A FROST ADVISORY MAY BE
NEEDED FOR THIS PERIOD.
THE FORECAST IS DRY ACROSS THE AREA ON MONDAY AS THE MID-LEVEL
TROUGH PUSHES EASTWARD AND A SURFACE HIGH BUILDS INTO THE AREA FROM
THE WEST. THE COOLEST 850MB TEMPS (0-2C) WILL REACH THE AREA BY 12Z
MONDAY. THUS, HIGHS ON MONDAY ARE FORECAST TO BE AROUND 10 DEGREES
BELOW NORMAL EVEN DESPITE MORE ABUNDANT SUNSHINE.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
MODELS ARE IN DECENT AGREEMENT THAT HIGH PRESSURE WILL BUILD OVER
THE OHIO VALLEY LATER THROUGH THE MIDDLE OF THE WEEK. THE
DETERMINISTIC MODELS THEN DIVERGE ON THE TIMING OF THE NEXT UPPER
LEVEL SHORTWAVE AND FRONT FOR WEDNESDAY AND THURSDAY. DURING THIS
TIME PERIOD, OPTED TO REMAIN CLOSE TO HPC GUIDANCE LEANING TOWARDS
THE SLOWER ECMWF BUT NOT DISCOUNTING THE GFS COMPLETELY. WITH COLD
TEMPERATURES ALOFT THROUGH A GOOD PART OF THE LONG
TERM, TEMPERATURES WERE KEPT 5-10 DEGREES BELOW
NORMAL, MODERATING TO NEAR NORMAL BY THE END OF THE WEEK.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
VFR CONDITIONS WILL CONTINUE ACROSS THE UPPER OHIO VALLEY INTO
THIS AFTERNOON. PREFRONTAL MIDDLE CLOUDS WILL PROVIDE VFR
CEILINGS TODAY. AS THE FRONT DRAWS CLOSER TODAY A FRONTAL BAND
OF MVFR SHOWERS WILL MOVE EAST THROUGH THE UPPER OHIO VALLEY LATE
THIS AFTERNOON AND TONIGHT.
SURFACE WINDS WILL BE FROM THE SOUTHWEST AT 5 TO 8 KTS THIS MORNING
AND THEN INCREASE TO 10 KTS WITH GUSTS TO 20 KTS BY MIDDAY, SHIFTING
TO WEST WITH THE COLD FRONTAL PASSAGE THIS EVENING.
.OUTLOOK /TONIGHT THROUGH TUESDAY/...
TEMPORARY RESTRICTIONS WILL BE POSSIBLE THROUGH SUNDAY DUE TO BANDS
OF SHOWERS ASSOCIATED THE PASSAGE OF AT LEAST TWO SECONDARY COLD
FRONTS. HIGH PRESSURE WILL FOLLOW WITH VFR FOR MONDAY AND TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
436 AM EDT FRI SEP 21 2012
.SYNOPSIS...
A WEAKENING COLD FRONT WILL SLOWLY PUSH EASTWARD INTO THE REGION
TODAY. A LOW PRESSURE SYSTEM WILL CROSS OHIO TONIGHT INTO EARLY
SATURDAY AND RETURN SHOWERS TO MUCH OF THE AREA. THE COLD FRONT WILL
SHIFT EAST OF THE AREA BY LATE IN THE DAY ON SATURDAY, WITH A
CANADIAN AIR MASS BUILDING INTO THE AREA FOR SUNDAY INTO MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A BROAD 500MB TROUGH
CENTERED ACROSS THE UPPER MIDWEST WITH THE UPPER OHIO VALLEY IN A
SOUTHWESTERLY FLOW AHEAD OF THIS FEATURE. A PLUME OF MID-LEVEL
MOISTURE IS ADVECTING ACROSS THE AREA. AT THE SURFACE, A COLD
FRONT EXTENDS FROM MICHIGAN SOUTHWESTWARD ACROSS INDIANA AND HAS
SLOWED AS IT TRANSVERSES ACROSS THE OHIO VALLEY.
TODAY...THE COLD FRONT WILL SLIDE ACROSS OHIO AND BECOME MORE POORLY
DEFINED AS IT ENTERS WESTERN PA THIS EVENING. A FEW SHOWERS ARE
NOT OUT OF THE QUESTION AS WEAK FORCING FROM THE FRONT PUSHES INTO
THE AREA THIS AFTERNOON. HOWEVER, GFS/NAM MODEL SOUNDINGS INDICATE
A LAYER OF RELATIVELY DRY AIR IN THE 1000-850MB LAYER INHIBITING
THE DEVELOPMENT OF SHOWERS. WITH THIS IN MIND, HAVE GONE WITH SCHC
POPS EARLY THIS AFTERNOON, INCREASING TO CHC POPS NORTH AND WEST OF
PITTSBURGH BY 00Z AS THE LOWER LEVELS BECOME SATURATED.
TONIGHT...A WEAK SURFACE LOW IS PROGGED TO MOVE ALONG AND JUST NORTH
OF THE OHIO RIVER, ALLOWING FOR WARM AIR ADVECTION TO OCCUR OVER
MUCH OF THE OHIO VALLEY OVERNIGHT. AS THE LOW LIFTS NORTHEASTWARD INTO
EASTERN OHIO NEAR DAWN, POPS RAMP UP FROM CHC TO LIKELY WITH THE
BEST FORCING TO THE NW OF PITTSBURGH. CHANCE POPS ARE FORECAST
ELSEWHERE. IN WAA OVERNIGHT, TEMPS WILL ONLY DROP INTO THE MID TO
UPPER 50S ACROSS MOST OF THE AREA.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
GFS/ECMWF ARE IN REASONABLE AGREEMENT WITH THE MID-LEVEL SYNOPTIC
FEATURES THROUGH THIS PERIOD WITH MORE DIFFICULTY IN RESOLVING THE
SURFACE FRONTAL BOUNDARY. WITH SOME UNCERTAINTY IN ITS TRACK, THE
AFOREMENTIONED LOW IS PROGGED TO WEAKEN INTO A SURFACE TROUGH AS
IT PUSHES INTO THE AREA ON SATURDAY. THUS, LIKELY POPS CONTINUE
NORTH AND WEST OF PITTSBURGH WITH CHC POPS SOUTHWARD. WITH THE
FRONT IN THE VICINITY OF THE AREA, A CLOUDY DAY IS ANTICIPATED AND
THIS ALONG WITH SHOWERS SHOULD LIMIT HIGHS TO AROUND 5 DEGREES
BELOW SEASONAL NORMALS ON SATURDAY.
THE CANADIAN AIR MASS BEHIND THE FRONT WON`T BEGIN TO ADVECT INTO
THE AERA UNTIL LATE ON SATURDAY INTO SATURDAY NIGHT. IT WILL BE A
SHORT WAVE CURRENTLY DROPPING SOUTHWARD INTO MANITOBA THAT WILL
SWING AROUND THE BASE OF THE TROUGH AND FINALLY KICK THE FRONT
EAST OF THE AREA BY 06Z ON SUNDAY. THIS FEATURE WILL ALLOW FOR
LIKELY POPS AS IT CROSSES AREAS NORTH OF PITTSBURGH SATURDAY
NIGHT.
THE AREA WILL BE IN COLD AIR ADVECTION ON SUNDAY INTO SUNDAY NIGHT
IN THE WAKE OF THE FRONT. WITH THIS IN MIND, CHC POPS CONTINUE
ACROSS LOCATIONS NORTH OF PITTSBURGH THROUGHOUT THE DAY. COOLEST
TEMPS ARE FORECAST IN THIS WINDOW WITH HIGHS 10 DEGREES BELOW NORMAL
SUNDAY AND 10-15 DEGREES BELOW NORMAL SUNDAY NIGHT. PATCHY FROST
IS FORECAST TO DEVELOP NEAR DAWN ACROSS THE EASTERN RIDGES AS
CLEARING OCCURS BY EARLY MONDAY MORNING. A FROST ADVISORY MAY BE
NEEDED FOR THIS PERIOD.
THE FORECAST IS DRY ACROSS THE AREA ON MONDAY AS THE MID-LEVEL
TROUGH PUSHES EASTWARD AND A SURFACE HIGH BUILDS INTO THE AREA FROM
THE WEST. THE COOLEST 850MB TEMPS (0-2C) WILL REACH THE AREA BY 12Z
MONDAY. THUS, HIGHS ON MONDAY ARE FORECAST TO BE AROUND 10 DEGREES
BELOW NORMAL EVEN DESPITE MORE ABUNDANT SUNSHINE.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
MODELS ARE IN DECENT AGREEMENT THAT HIGH PRESSURE WILL BUILD OVER
THE OHIO VALLEY LATER THROUGH THE MIDDLE OF THE WEEK. THE
DETERMINISTIC MODELS THEN DIVERGE ON THE TIMING OF THE NEXT UPPER
LEVEL SHORTWAVE AND FRONT FOR WEDNESDAY AND THURSDAY. DURING THIS
TIME PERIOD, OPTED TO REMAIN CLOSE TO HPC GUIDANCE LEANING TOWARDS
THE SLOWER ECMWF BUT NOT DISCOUNTING THE GFS COMPLETELY. WITH COLD
TEMPERATURES ALOFT THROUGH A GOOD PART OF THE LONG
TERM, TEMPERATURES WERE KEPT 5-10 DEGREES BELOW
NORMAL, MODERATING TO NEAR NORMAL BY THE END OF THE WEEK.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
VFR CONDITIONS WILL CONTINUE ACROSS THE UPPER OHIO VALLEY INTO
THIS AFTERNOON. PREFRONTAL MIDDLE CLOUDS WILL PROVIDE VFR
CEILINGS TODAY. AS THE FRONT DRAWS CLOSER TODAY A FRONTAL BAND
OF MVFR SHOWERS WILL MOVE EAST THROUGH THE UPPER OHIO VALLEY LATE
THIS AFTERNOON AND TONIGHT.
SURFACE WINDS WILL BE FROM THE SOUTHWEST AT 5 TO 8 KTS THIS MORNING
AND THEN INCREASE TO 10 KTS WITH GUSTS TO 20 KTS BY MIDDAY, SHIFTING
TO WEST WITH THE COLD FRONTAL PASSAGE THIS EVENING.
.OUTLOOK /TONIGHT THROUGH TUESDAY/...
TEMPORARY RESTRICTIONS WILL BE POSSIBLE THROUGH SUNDAY DUE TO BANDS
OF SHOWERS ASSOCIATED THE PASSAGE OF AT LEAST TWO SECONDARY COLD
FRONTS. HIGH PRESSURE WILL FOLLOW WITH VFR FOR MONDAY AND TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
SYNOPSIS...WOODRUM
NEAR TERM...WOODRUM
SHORT TERM...WOODRUM
LONG TERM...
AVIATION...
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
237 AM EDT FRI SEP 21 2012
.SYNOPSIS...
A WEAKENING COLD FRONT WILL SLOWLY PUSH EASTWARD INTO THE REGION
TODAY. A LOW PRESSURE SYSTEM WILL CROSS OHIO TONIGHT INTO EARLY
SATURDAY AND RETURN SHOWERS TO MUCH OF THE AREA. THE COLD FRONT WILL
SHIFT EAST OF THE AREA BY LATE IN THE DAY ON SATURDAY, WITH A
CANADIAN AIR MASS BUILDING INTO THE AREA FOR SUNDAY INTO MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
06Z ENHANCED SHORT TERM FORECAST HAS BEEN ISSUED TO ADJUST POPS TO
SCHC EARLY TODAY, RAMPING UP TO LIKELY BY THE OVERNIGHT HOURS FOR
LOCATIONS NORTH AND WEST OF THE PITTSBURGH METRO.
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A BROAD 500MB TROUGH
CENTERED ACROSS THE UPPER MIDWEST WITH THE UPPER OHIO VALLEY IN A
SOUTHWESTERLY FLOW AHEAD OF THIS FEATURE. A PLUME OF MID-LEVEL
MOISTURE IS ADVECTING ACROSS THE AREA. AT THE SURFACE, A COLD FRONT
EXTENDS FROM MICHIGAN SOUTHWESTWARD ACROSS INDIANA AND HAS SLOWED AS
IT TRANSVERSES ACROSS THE OHIO VALLEY.
TODAY...THE COLD FRONT WILL SLIDE ACROSS OHIO AND BECOME MORE POORLY
DEFINED AS IT ENTERS WESTERN PA THIS EVENING. HIRES MODELS INDICATE
A FEW SHOWERS ARE NOT OUT OF THE QUESTION AS WEAK FORCING FROM THE
FRONT PUSHES INTO THE AREA THIS AFTERNOON. HOWEVER, GFS/NAM MODEL
SOUNDINGS INDICATE A LAYER OF RELATIVELY DRY AIR IN THE 1000-850MB
LAYER INHIBITING THE DEVELOPMENT OF SHOWERS. WITH THIS IN MIND, HAVE GONE
WITH SCHC POPS THIS AFTERNOON, INCREASING TO CHC POPS NORTH AND
WEST OF PITTSBURGH BY 00Z AS THE LOWER LEVELS BECOME SATURATED
LATE.
TONIGHT...A WEAK SURFACE LOW IS PROGGED TO MOVE ALONG AND JUST NORTH
OF THE OHIO RIVER, ALLOWING FOR WARM AIR ADVECTION TO OCCUR OVER
MUCH OF THE OHIO VALLEY OVERNIGHT. AS THE LOW LIFTS NORTHEASTWARD INTO
EASTERN OHIO NEAR DAWN, POPS RAMP UP FROM CHC TO LIKELY WITH THE
BEST FORCING IN THE NW OF PITTSBURGH. CHANCE POPS ARE FORECAST
ELSEWHERE. IN WAA OVERNIGHT, TEMPS WILL ONLY DROP INTO THE UPPER
50S ACROSS MOST OF THE AREA.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
MODELS IN AGREEMENT ON OVERALL PATTERN BUT DIFFER IN EXACT DETAILS
OF SPEED OF SHORTWAVES UNDER VORTEX DROPPING SOUTH OVER THE GREAT
LAKES. APPEARS THAT THE FIRST SHORTWAVE WILL CROSS REGION FRIDAY
NIGHT INTO EARLY SATURDAY AND THUS HAVE ADDED LIKELY POPS IN THIS PERIOD.
BEHIND THIS SYSTEM ANOTHER FAST MOVING DISTURBANCE IN NORTHWEST
FLOW WILL MOVE ACROSS THE EASTERN LAKES SATURDAY NIGHT...KEEPING
CHANCE POPS IN THE FORECAST. STILL A CHANCE OF SHOWERS IN COLD
NORTHWEST FLOW SUNDAY WITH HIGHER POPS ACROSS THE NORTH AND RIDGES
BEFORE SURFACE RIDGE BEGINS TO DIMINISH SHOWERS LATE SUNDAY AS IT
MOVES EAST. COOL TEMPERATURES A CLOSE BLEND OF MOS WHICH WAS IN
LINE WITH FORECAST 850MB TEMPS.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
UPPER LEVEL TROUGH WILL CONTINUE TO HAVE INFLUENCE LATE SUNDAY
NIGHT INTO MONDAY MAINTAINING THE CHANCE FOR SHOWERS DOWNWIND OF
LAKE ERIE TO START THE PERIOD. MODELS ARE IN DECENT AGREEMENT THAT
HIGH PRESSURE WILL BUILD OVER THE OHIO VALLEY LATER MONDAY THROUGH
THE MIDDLE OF THE WEEK. THE DETERMINISTIC MODELS THEN DIVERGE ON
THE TIMING OF THE NEXT UPPER LEVEL SHORTWAVE AND FRONT FOR
WEDNESDAY AND THURSDAY. DURING THIS TIME PERIOD...OPTED TO REMAIN
CLOSE TO HPC GUIDANCE LEANING TOWARDS THE SLOWER ECMWF BUT NOT
DISCOUNTING THE GFS COMPLETELY. WITH COLD TEMPERATURES ALOFT
THROUGH A GOOD PART OF THE LONG TERM...TEMPERATURES WERE KEPT 5-10
DEGREES BELOW NORMAL...MODERATING TO NEAR NORMAL BY THE END OF THE
WEEK.
&&
.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
VFR CONDITIONS WILL CONTINUE ACROSS THE UPPER OHIO VALLEY INTO
THIS AFTERNOON. PREFRONTAL MIDDLE CLOUDS WILL PROVIDE VFR
CEILINGS TODAY. AS THE FRONT DRAWS CLOSER TODAY A FRONTAL BAND
OF MVFR SHOWERS WILL MOVE EAST THROUGH THE UPPER OHIO VALLEY LATE
THIS AFTERNOON AND TONIGHT.
SURFACE WINDS WILL BE FROM THE SOUTHWEST AT 5 TO 8 KTS THIS MORNING
AND THEN INCREASE TO 10 KTS WITH GUSTS TO 20 KTS BY MIDDAY
...SHIFTING TO WEST WITH THE COLD FRONTAL PASSAGE THIS EVENING.
.OUTLOOK /TONIGHT THROUGH TUESDAY/...
TEMPORARY RESTRICTIONS WILL BE POSSIBLE THROUGH SUNDAY DUE TO BANDS
OF SHOWERS ASSOCIATED THE PASSAGE OF AT LEAST TWO SECONDARY COLD
FRONTS. HIGH PRESSURE WILL FOLLOW WITH VFR FOR MONDAY AND TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
SYNOPSIS...WOODRUM
NEAR TERM...WOODRUM
SHORT TERM...
LONG TERM...
AVIATION...
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
459 PM EDT FRI SEP 21 2012
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 458 PM EDT FRI SEP 21 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A DEEP MID/UPPER LEVEL TROUGH
FROM HUDSON BAY INTO THE WRN GREAT LAKES. THE SHRTWV THAT BROUGHT AN
AREA OF RAIN AND SOME TSRA TO UPPER MI THIS MORNING HAS MOVED
QUICKLY EAST OF LAKE SUPERIOR. ANOTHER VIGOROUS UPSTREAM SHRTWV/VORT
WAS LOCATED JUST SE OF LAKE WINNIPEG. SOME LIGHTNING HAS ALSO
ACCOMPANIED A LINE OF SHOWERS AHEAD OF THIS FEATURE. AT THE
SFC...LOW PRES WAS LOCATED OVER ERN LAKE SUPERIOR. THE COLD FRONT
ASSOCIATED WITH THE UPSTREAM SHRTWV HAS MOVED INTO THE NW CORNER OF
MN HAS BRINGING VERY GUSTY WINDS TO AROUND 35KT IN ITS WAKE. RADAR
INDICATED SCT SHOWERS LINGERING OVER THE AREA SUPPORTED BY SHALLOW
INSTABILITY AND LAKE MOISTURE AS 850/700 MB TEMPS REMAIN NEAR
0C/-10C.
TONIGHT...EXPECT A BRIEF PERIOD OF MORE LIMITED SHRA COVERAGE THIS
EVENING AS THE LOW LEVEL TROUGH AND BATCH OF SHRA OVER CNTRL UPPER
MI MOVES TO THE EAST. HOWEVER SOME LAKE ENHANCED SHOWERS SHOULD
STILL LINGER NEAR AREAS FAVORED BY NW FLOW. SATELLITED TRENDS AND
MODELS SUGGEST THAT THE MAIN IMPACTS OF THE MANITOBA SHRTWV WILL
SLIDE WELL TO THE WEST AND SOUTH OF UPPER MICHIGAN. HOWEVER...AS IT
MOVES TO THE SOUTH WINDS WILL VEER MORE NRLY AND COLDER AIR WILL
PUSH INTO THE AREA. LAKE EFFECT SHOWERS SHOULD THEN INCREASE FOR N
FLOW AREAS AS 850 MB TEMPS FALL TO AROUND -2C.
SATURDAY...THE BULK OF THE COLDER AIR MOVES IN WITH 850/700 MB TEMPS
FALLING TO AROUND -3C/-12C. NAM FCST SOUNDINGS SUGGEST THAT LAKE
INDUCED CAPE MAY CLIMB INTO THE 500-1000 J/KG RANGE. EXPECT HEAVIEST
PCPN OVER LOCATIONS FAVORED BY NNW FLOW...ESPECIALLY OVER N CNTRL INTO E
UPPER MI. ALTHOUGH LIGHTNING WOULD BE UNUSUAL WITH LAKE EFFECT
PCPN...WITH THE VERY COLD AIR ALOFT (500 MB TEMP TO -30C) CANNOT
RULE OUT SOME ISOLD TSRA AS WAS OBSERVED THIS MORNING. SIMILAR TO
THE LAST FEW DAYS...PERIODS OF GRAUPEL/SLEET MAY ALSO ACCOMPANY THE
HEAVIER SHOWERS. WITH WET-BULB ZERO HEIGHTS DOWN TO NEAR 1500 FT
AGL. SOME SNOW COULD BE POSSIBLE OVER HIGHER TERRAIN BUT WOULD
LIKELY BE VERY TRANSIENT/BRIEF. GALES OVER LAKE SUPERIOR WILL ALSO
BRING SOME STRONGER WINDS TO SHORELINE LOCATIONS POSSIBLY REACHING
ADVY CRITERIA (45 MPH GUSTS) AT THE MOST EXPOSED LOCATIONS.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 458 PM EDT FRI SEP 21 2012
SAT NGT...A HEALTHY LAKE EFFECT/ENHANCED SHRA REGIME WL CONT WITH
DEEP CYC NW FLOW OF CHILLY AIR /H85 TEMPS -3 TO -5C/ UNDER
PERSISTENT SHARP UPR TROF AXIS...ESPECIALLY FOR THOSE AREAS ON THE
CYC SIDE OF TRACK OF SHRTWV THAT IS FCST TO DIG SHARPLY THRU THE NNW
FLOW ALF. GIVEN THE INTENSITY OF THE TROF AND LOCATION OF H3 UPR JET
AXIS THRU MN/WI...PREFER THOSE MODELS THAT SHOW A FARTHER W TRACK
FOR THIS DISTURBANCE. RETAINED MENTION OF TS OVER MAINLY AREAS NEAR
THE E HALF OF LK SUP WHERE NAM SHOW SBCAPE UP TO 300-400 J/KG.
NOT OUT OF THE QUESTION THAT ANY -SHRA OVER THE INTERIOR W COULD MIX
WITH SN OVER THE HIER TERRAIN LATER AT HGT IN PRESENCE OF DIURNAL
COOLING/MIN TEMPS FALLING CLOSE TO 32 AS 12Z NAM SHOWS H100-85 THKNS
AND WBZ HGT FALLING TO 1300-1305M/NEAR 1K FT AGL. WITH MORE OF A
LAKE WARMING INFLUENCE ELSEHWERE...PTYPE WL BE RA...BUT DID RETAIN
MENTION OF MIX WITH SLEET/GRAUPEL FOR AREAS IMPACTED BY SOME HEAVIER
SHRA.
SUN...AS CLOSED LO/CORE OF COLD MID LVL TEMPS LIFTS NEWD INTO
QUEBEC...MODELS SHOW SLOWLY RISING HGTS UNDER LARGER SCALE DNVA/
SINKING INVRN BASE/RISING H85 OVER THE UPR LKS. SINCE THE LLVL FLOW
IS PROGGED TO BACK MORE W AND ADVECT DRIER LLVL AIR INTO THE AREA AS
SFC HI PRES CENTER SINKS TOWARD THE MID MS RIVER VALLEY LATE IN THE
DAY IN THE PRESENCE OF DIURNAL HEATING THAT WL DISRUPT THE LAKE
EFFECT PROCESS...EXPECT STEADILY DCRSG POPS THAT WL LINGER LONGEST
DOWNWIND OF LK SUP E OF MQT WHERE LOWER H85 TEMPS AND LLVL
MOISTENING OF THE DRIER FLOW WL BE MORE PERSISTENT.
SUN NGT...DNVA/LOWERING INVRN BASE AND BACKING/DRYING FLOW TO WSW
BTWN HI PRES MOVING INTO THE OH RIVER VALLEY AND SHRTWV DIGGING SEWD
FM MANITOBA WL CONSPIRE TO FINALLY DIMINISH ANY LINGERING LK EFFECT
PCPN OVER THE E. DESPITE PARTIAL CLEARING BEFORE SOME MID/HI CLDS IN
ADVANCE OF APRCHG SHRTWV ARRIVE...LLVL WARMING/STEADY WSW FLOW THAT
MAINTAINS SOME MIXING WL RESTRICT DIURNAL TEMP FALL DESPITE PWAT
FALLING AS LO AS 0.30 INCH. WHERE THE PRES GRADIENT IS SLOWER TO
TIGHTEN UP AND CLDS ARRIVE LATER NEAR THE WI BORDER...MIN TEMPS MAY
APRCH 32.
MON...SHRTWV EMBEDDED IN NW FLOW ALF ON WRN FLANK OF SLOWLY
RETREATING UPR TROF IS PROGGED TO SWING SEWD THRU ONTARIO. ALTHOUGH
SOME OF THE MORE IMPRESSIVE DVPA/DEEP LYR QVECTOR CNVGC IS PROGGED
TO BRUSH MAINLY THE NE HALF OF THE CWA...DRYNESS OF FCST SDNGS/
ABSENCE OF ANY LLVL MSTR ADVECTION INDICATE ANY SHRA WL BE FEW AND
FAR BTWN. MAINTAINED THEME OF LO CHC POPS OVER PORTIONS OF THE NE
CWA CLOSER TO MORE IMPRESSIVE DYNAMICS. WARMING H85 TEMPS IN STEADY
WSW FLOW AHEAD OF ATTENDANT COLD FNT WL PUSH MAX TEMPS ABV
NORMAL...BUT GUSTY SFC WINDS WL MAKE THE AIR FEEL COOLER. MIXING TO
H85 ON GFS FCST SDNGS INDICATES MAX TEMPS WL RISE INTO THE 60S AT
MOST SPOTS.
MON NGT THRU TUE NGT...AS LO PRES TROF CROSSES THE CWA ON MON NGT
WITH WSHFT TO THE N...WENT WITH LO CHC POPS MAINLY IN THE UPSLOPE
AREAS NEAR LK SUP. THEN TRAILING HI PRES MOVING IN FM CNTRL CAN WL
BRING A PERIOD OF DRY WX ON TUE. BUT AS COOLER AIR /WITH H85 TEMPS
DROPPING AOB 0C/ ARRIVES ON TUE NGT...SOME LK EFFECT PCPN MAY DVLP
MAINLY OVER THE NCNTRL IN AREAS FAVORED BY FCST LLVL NLY FLOW. AWAY
FM THE MODERATING INFLUENCE OF LK SUP AND CLOSER TO INCOMING HI PRES
CENTER BLDG INTO MN...TENDED BLO GUIDANCE FOR MIN TEMPS TOWARD 32
OVER THE INTERIOR W.
EXTENDED...SFC HI PRES IS FCST TO DOMINATE UNDER RISING HGTS AS UPR
TROF IN CAN SLOWLY LIFTS TO THE NE. EXPECT DRY WX THRU THIS PERIOD
WITH WIDE DIURNAL TEMP VARIATIONS...ESPECIALLY OVER THE INTERIOR
AWAY FM THE MODERATING INFLUENCE OF THE LKS. OVERALL HOWEVER...TEMPS
SHOULD AVG BLO NORMAL DURING THIS TIME.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 136 PM EDT FRI SEP 21 2012
A SERIES OF SHORTWAVES WILL ROTATE THROUGH THE AREA AROUND A LARGE
UPPER TROUGH IN PLACE OVER THE REGION. LAKE ENHANCED RAIN SHOWERS IN
THE WAKE OF THE FIRST SHRTWV OVER ERN LAKE SUPERIOR WILL AFFECT
CMX/SAW THIS AFTERNOON. HOWEVER...IT APPEARS MAIN SHOWER CHANCES
COULD STAY AWAY FROM IWD FOR MOST OF THE DAY IN WAKE OF THE WAVE.
CONDITIONS SHOULD STAY VFR OR MAYBE HIGH END MVFR. WINDS WILL TURN
MORE NORTHERLY THROUGH THE TAF PERIOD...RESULTING IN CONDITIONS
COMING BACK DOWN AT SAW AND IWD LATE IN THE PERIOD AS WINDS COME OFF
LAKE SUPERIOR. MVFR CONDITIONS ARE EXPECTED LATE TONIGHT AND SAT
MORNING WITH INTERMITTENT LAKE EFFECT RAIN SHOWERS.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 458 PM EDT FRI SEP 21 2012
A LAKE ENHANCED LOW OVER ERN LAKE SUPERIOR WILL BE SLOW TO MOVE
OFF LK SUPERIOR TONIGHT WHILE HIGH PRESSURE RIDGE BUILDS FROM SCNTRL
CANADA INTO THE NORTHERN PLAINS. THE PRESSURE GRADIENT WILL TIGHTEN
AND EXPECT NNW WINDS TO INCREASE TO GALES LATE TONIGHT OVER NORTH
CENTRAL SECTIONS OF LK SUPERIOR. THERE IS A RISK OF WATERSPOUTS
TONIGHT...PER NOMOGRAM OUTPUT...AS VERY COLD AIR MOVES OVER THE
RELATIVELY WARM WATER BEFORE THE WINDS INCREASE.
GALES ARE EXPECTED SAT INTO SAT EVENING FOR THE CNTRL AND EAST
PORTIONS OF LAKE SUPERIOR AS THE SFC LOW DEEPENS TO THE E AND COLDER
AIR MOVES OVER THE LAKE...CREATING A VERY UNSTABLE TEMP PROFILE.
EXPECT WINDS ON SAT NIGHT INTO SUN NIGHT TO SLOWLY DIMINISH AND
GRADUALLY BACK TO THE W AS A HI PRES CENTER MOVES FROM THE NORTHERN
PLAINS INTO THE OHIO RIVER VALLEY. ANOTHER ROUND OF WSW GALES IS
POSSIBLE LATE SUN NIGHT INTO MON AS THE PRES GRADIENT TIGHTENS
BETWEEN THE RETREATING HI TO THE SE AND ANOTHER LO PRES TROF
DROPPING SEWD FROM CENTRAL CANADA THRU ONTARIO TOWARD LAKE SUPERIOR.
FOLLOWING THE PASSAGE OF THIS TROF ON MON...WINDS WILL DIMINISH AND
VEER TO THE N AHEAD OF HI PRES APPROACHING FROM THE NW.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING FROM 2 PM SATURDAY TO 1 AM EDT SUNDAY FOR LSZ251-
267.
GALE WARNING FROM 6 AM SATURDAY TO 1 AM EDT SUNDAY FOR LSZ244-
245-248>250-264>266.
GALE WARNING FROM 6 AM TO 2 PM EDT SATURDAY FOR LSZ263.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KC
AVIATION...JLB
MARINE...JLB/KC
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
1257 PM CDT FRI SEP 21 2012
.UPDATE...
ISSUED AT 1257 PM CDT FRI SEP 21 2012
ISOLATED THUNDERSTORMS CONTINUE TO MOVE EAST OVER WEST CENTRAL
ILLINOIS. THE ONE CURRRENTLY ENTERING MACOUPIN COUNTY EARLIER
PRODUCED NICKEL SIZE. HAIL. THERE MAY BE SOME ADDITIONAL
DEVELOPMENT OVER THE EASTERN COUNTIES THIS AFTERNOON FOR TWO
REASONS. FIRST IS ASSOCIATED WITH THIS CURRENT ACTIVITY WHICH IS
ALONG A WEAK FRONT THAT IS LIFTING NORTHWARD. SECOND WILL BE WHEN
A PRE-FRONTAL TROUGH THAT IS CURRENTLY ENTERING THE WESTERN PART
OF THE CWA MOVES INTO ILLINOIS LATER THIS AFTERNOON. INSTABILITY
WILL BE INCREASING OVER ILLINOIS THIS AFTERNOON WHICH MAY BE
ENOUGH TO ALLOW FOR FURTHER DEVELOPMENT.
ISSUED AT 938 AM CDT FRI SEP 21 2012
SKIES HAVE CLEARED OVER CENTRAL AND SOUTHEASTERN MO AS MID LEVEL
VORT MIN HAS MOVED INTO MISSOURI. THIS CLEARING WILL CONTINUE TO
WORK EAST THIS MORNING INTO THE EARLY AFTERNOON. HAVE LOWERED POPS
THE REST OF THE MORNING BASED ON THIS TREND. TEMPERATURES JUMPED
INTO THE MID 60S THIS PAST HOUR WHERE THE CLEARING HAS OCCURRED...
SO THINK HIGHS IN THE UPPER 70S/LOWER 80S STILL LOOK REASONABLE
WITH MID 70S ELSEWHERE.
SURFACE LOW IS NOW OVER WESTERN IOWA WITH A COLD FRONT EXTENDING
SOUTH SOUTHWESTWARD INTO NORTH CENTRAL OKLAHOMA. DEWPOINTS ARE
CLIMBING INTO THE MIDDLE 50S TO AROUND 60 AHEAD OF THIS FRONT
WHICH THE RAP SHOWS MOVING ACROSS THE CWA BETWEEN 18-03Z. THE
HIGHER DEWPOINTS AND STEEPENING LAPSE RATES WILL CONTRIBUTE TO
INCREASING MUCAPES WITH IMPRESSIVE DEEP LAYER SHEAR. MAY SEE A
FEW STRONG TO POSSIBLY SEVERE THUNDERSTORMS AHEAD OF THE FRONT
THIS LATER THIS AFTERNOON AND EARLY THIS EVENING.
BRITT
&&
.SHORT TERM...
ISSUED AT 311 AM CDT FRI SEP 21 2012
(TODAY)
MAIN ISSUE IS THE FRONTAL BOUNDARY THAT MOVED THROUGH ON WEDNESDAY
AND STALLED OVER SOUTHERN MISSOURI AND STRONGER SHORTWAVE THAT IS
SLIDING SOUTHEAST INTO FORECAST AREA TODAY. ELEVATED CONVECTION HAS
FIRED UP OVER WFO SGF FORECAST AREA EARLY THIS MORNING AND SLIDING
OFF TO THE SOUTHEAST AWAY FROM OUR AREA. THIS ACTIVITY IS FIRING ON
NOSE OF DECENT LOW LEVEL JET WITH PLENTY OF LOW LEVEL MOISTURE AND
INSTABILITY.
HOWEVER...MODELS HAVE THIS ACTIVITY LIFTING TO THE NORTHEAST DURING
THE DAY TODAY AS SURFACE LOW DEVELOPS ALONG STALLED FRONTAL
BOUNDARY...THEN AS IT LIFTS OUT OF REGION...ACTIVITY TO ADVECT
NORTHEASTWARD THROUGH FORECAST AREA. BEST CHANCES OF RAIN WILL BE
ALONG AND SOUTH OF I-44 IN MISSOURI AND ALONG AND SOUTH OF I-70 IN
ILLINOIS. TEMPERATURES WILL BE DEPENDENT ON CLOUD COVER AND PCPN.
FOR NOW...WENT WITH THE WARMER GUIDANCE...HIGHS IN THE MID 70S TO
LOW 80S.
BYRD
&&
.LONG TERM...
ISSUED AT 311 AM CDT FRI SEP 21 2012
(TONIGHT THROUGH SUNDAY)
ANY LINGERING CONVECTION ALONG THE SURFACE COLD FRONT LATE THIS
AFTERNOON SHOULD QUICKLY RACE OUT OF SE SECTIONS OF OUR CWA BY
EARLY THIS EVENING. LAST IN THE SERIES OF SHORTWAVES DROPPING DOWN
THE BACK SIDE OF THE LONG WAVE TROF WILL THEN SWING FROM THE UPPER
MISSISSIPPI VALLEY INTO THE OHIO VALLEY TONIGHT-
SATURDAY...USHERING ANOTHER STRONG CANADIAN HIGH INTO THE REGION
THAT WILL DOMINATE OUR WEATHER FOR THE UPCOMING WEEKEND.
AMS WITH THIS CHUNK OF CANADIAN AIR IS PROGGED TO BE A FEW DEGREES
COLDER THAN THE AIR THAT PUSHED INTO THE REGION THE MIDDLE OF THIS
WEEK. WHETHER THIS IS REAL OR NOT REMAINS TO BE SEEN...BUT IT
CERTAINLY POINTS TO BELOW AVERAGE TEMPERATURES THROUGHOUT THE
UPCOMING WEEKEND. SINCE WE WILL BE AWAITING THE ARRIVAL OF THE
TRULY COLD AIR TONIGHT MAY NOT BE TOO CHILLY...AND LIKE THE
DEPICTIONS OF THE SHORT RANGE MODELS THAT SUGGEST LEADING EDGE OF
STRONG CANADIAN HIGH JUST BEGINNING TO NOSE INTO NW SECTIONS OF
OUR CWA BY 12Z SATURDAY.
HIGHS BOTH SATURDAY AND SUNDAY SHOULD PRIMARILY BE IN THE
60S...WITH THE COLDEST NIGHT OCCURRING SATURDAY NIGHT WHEN LOWS
WILL RANGE FROM THE UPPER 30S TO LOWER 40S. FROST THREAT NOT
TOTALLY OUT OF THE QUESTION...BUT WILL MONITOR A FEW MORE MODEL
CYCLES TO DETERMINE WHETHER THIS NEEDS TO BE INTRODUCED INTO
FORECAST PRODUCTS.
(MONDAY THROUGH THURSDAY)
MEAN TROF POSITION BEGINS TO WORK EAST FOR THE START OF THE NEW WORK
WEEK. WARMER AIR WILL BEGIN TO PUSH EAST IN RESPONSE TO THIS
MOVEMENT...AND SHOULD SET UP A ZONE OF ISENTROPIC LIFT MONDAY NIGHT
AND INTO TUESDAY THAT COULD PRODUCE A FEW SHOWERS AND THUNDERSTORMS.
MEDIUM RANGE SOLUTIONS ARE ALSO IN FAIRLY GOOD AGREEMENT THAT A
SHORTWAVE WILL DROP INTO THE UPPER GREAT LAKES AND ALLOW A COLD
FRONT TO BACK DOOR AND STALL OVER THE AREA DURING THE MIDDLE OF THE
WEEK...CONTINUING A THREAT OF SHOWERS AND THUNDERSTORMS.
SPECIFIC TEMPERATURES THROUGHOUT THE MEDIUM RANGE WILL BE
MODULATED BY THE AMOUNT OF CLOUD COVER....BUT IN GENERAL
HIGH TEMPS SHOULD BE REBOUNDING INTO THE 70S WITH LOWER 80S
POSSIBLE TUESDAY-THURSDAY OVER SW SECTIONS OF AREA.
TRUETT
&&
.AVIATION...
ISSUED AT 1257 PM CDT FRI SEP 21 2012
HAVE GONE WITH DRY AND VFR TAFS AT THIS POINT...THOUGH WILL NEED
TO MONITOR THE POTENTIAL FOR DEVELOPMENT IN THE ST. LOUIS METRO
AREA THE NEXT FEW HOURS AS A PRE-FRONTAL TROUGH CURRENTLY OVER
CENTRAL MO MOVES EASTWARD. THERE ARE NO CLOUDS DEVELOPING ALONG
THIS TROUGH...SO THINK THAT ANY SCT -SHRA/-TSRA WILL DEVELOP TO
THE EAST OF THESE SITES. OTHERWISE WINDS WILL BECOME GUSTY FROM
THE WEST BEHIND THE TROUGH...AND THEN BECOME LIGHT TONIGHT BEFORE
INCREASING FROM THE NORTHWEST BEHIND A COLD FRONT ON SATURDAY
MORNING.
SPECIFICS FOR KSTL...CHANCES FOR RAIN IS DECREASING AS PRE-FRONTAL
TROUGH IS QUICKLY APPROACHING FROM THE WEST. WINDS WILL TURN FROM
THE WEST IN THE NEXT TWO HOURS AND THEN TURN LIGHT TONIGHT BEFORE
INCREASING FROM THE NORTHWEST MID-MORNING SATURDAY. EXPECT DRY AND
VFR THE NEXT 30 HOURS.
BRITT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
1010 AM CDT FRI SEP 21 2012
.UPDATE...
ISSUED AT 938 AM CDT FRI SEP 21 2012
SKIES HAVE CLEARED OVER CENTRAL AND SOUTHEASTERN MO AS MID LEVEL
VORT MIN HAS MOVED INTO MISSOURI. THIS CLEARING WILL CONTINUE TO
WORK EAST THIS MORNING INTO THE EARLY AFTERNOON. HAVE LOWERED POPS
THE REST OF THE MORNING BASED ON THIS TREND. TEMPERATURES JUMPED
INTO THE MID 60S THIS PAST HOUR WHERE THE CLEARING HAS OCCURRED...
SO THINK HIGHS IN THE UPPER 70S/LOWER 80S STILL LOOK REASONABLE
WITH MID 70S ELSEWHERE.
SURFACE LOW IS NOW OVER WESTERN IOWA WITH A COLD FRONT EXTENDING
SOUTH SOUTHWESTWARD INTO NORTH CENTRAL OKLAHOMA. DEWPOINTS ARE
CLIMBING INTO THE MIDDLE 50S TO AROUND 60 AHEAD OF THIS FRONT
WHICH THE RAP SHOWS MOVING ACROSS THE CWA BETWEEN 18-03Z. THE
HIGHER DEWPOINTS AND STEEPENING LAPSE RATES WILL CONTRIBUTE TO
INCREASING MUCAPES WITH IMPRESSIVE DEEP LAYER SHEAR. MAY SEE A
FEW STRONG TO POSSIBLY SEVERE THUNDERSTORMS AHEAD OF THE FRONT
THIS LATER THIS AFTERNOON AND EARLY THIS EVENING.
BRITT
&&
.SHORT TERM...
ISSUED AT 311 AM CDT FRI SEP 21 2012
(TODAY)
MAIN ISSUE IS THE FRONTAL BOUNDARY THAT MOVED THROUGH ON WEDNESDAY
AND STALLED OVER SOUTHERN MISSOURI AND STRONGER SHORTWAVE THAT IS
SLIDING SOUTHEAST INTO FORECAST AREA TODAY. ELEVATED CONVECTION HAS
FIRED UP OVER WFO SGF FORECAST AREA EARLY THIS MORNING AND SLIDING
OFF TO THE SOUTHEAST AWAY FROM OUR AREA. THIS ACTIVITY IS FIRING ON
NOSE OF DECENT LOW LEVEL JET WITH PLENTY OF LOW LEVEL MOISTURE AND
INSTABILITY.
HOWEVER...MODELS HAVE THIS ACTIVITY LIFTING TO THE NORTHEAST DURING
THE DAY TODAY AS SURFACE LOW DEVELOPS ALONG STALLED FRONTAL
BOUNDARY...THEN AS IT LIFTS OUT OF REGION...ACTIVITY TO ADVECT
NORTHEASTWARD THROUGH FORECAST AREA. BEST CHANCES OF RAIN WILL BE
ALONG AND SOUTH OF I-44 IN MISSOURI AND ALONG AND SOUTH OF I-70 IN
ILLINOIS. TEMPERATURES WILL BE DEPENDENT ON CLOUD COVER AND PCPN.
FOR NOW...WENT WITH THE WARMER GUIDANCE...HIGHS IN THE MID 70S TO
LOW 80S.
BYRD
&&
.LONG TERM...
ISSUED AT 311 AM CDT FRI SEP 21 2012
(TONIGHT THROUGH SUNDAY)
ANY LINGERING CONVECTION ALONG THE SURFACE COLD FRONT LATE THIS
AFTERNOON SHOULD QUICKLY RACE OUT OF SE SECTIONS OF OUR CWA BY
EARLY THIS EVENING. LAST IN THE SERIES OF SHORTWAVES DROPPING DOWN
THE BACK SIDE OF THE LONG WAVE TROF WILL THEN SWING FROM THE UPPER
MISSISSIPPI VALLEY INTO THE OHIO VALLEY TONIGHT-
SATURDAY...USHERING ANOTHER STRONG CANADIAN HIGH INTO THE REGION
THAT WILL DOMINATE OUR WEATHER FOR THE UPCOMING WEEKEND.
AMS WITH THIS CHUNK OF CANADIAN AIR IS PROGGED TO BE A FEW DEGREES
COLDER THAN THE AIR THAT PUSHED INTO THE REGION THE MIDDLE OF THIS
WEEK. WHETHER THIS IS REAL OR NOT REMAINS TO BE SEEN...BUT IT
CERTAINLY POINTS TO BELOW AVERAGE TEMPERATURES THROUGHOUT THE
UPCOMING WEEKEND. SINCE WE WILL BE AWAITING THE ARRIVAL OF THE
TRULY COLD AIR TONIGHT MAY NOT BE TOO CHILLY...AND LIKE THE
DEPICTIONS OF THE SHORT RANGE MODELS THAT SUGGEST LEADING EDGE OF
STRONG CANADIAN HIGH JUST BEGINNING TO NOSE INTO NW SECTIONS OF
OUR CWA BY 12Z SATURDAY.
HIGHS BOTH SATURDAY AND SUNDAY SHOULD PRIMARILY BE IN THE
60S...WITH THE COLDEST NIGHT OCCURRING SATURDAY NIGHT WHEN LOWS
WILL RANGE FROM THE UPPER 30S TO LOWER 40S. FROST THREAT NOT
TOTALLY OUT OF THE QUESTION...BUT WILL MONITOR A FEW MORE MODEL
CYCLES TO DETERMINE WHETHER THIS NEEDS TO BE INTRODUCED INTO
FORECAST PRODUCTS.
(MONDAY THROUGH THURSDAY)
MEAN TROF POSITION BEGINS TO WORK EAST FOR THE START OF THE NEW WORK
WEEK. WARMER AIR WILL BEGIN TO PUSH EAST IN RESPONSE TO THIS
MOVEMENT...AND SHOULD SET UP A ZONE OF ISENTROPIC LIFT MONDAY NIGHT
AND INTO TUESDAY THAT COULD PRODUCE A FEW SHOWERS AND THUNDERSTORMS.
MEDIUM RANGE SOLUTIONS ARE ALSO IN FAIRLY GOOD AGREEMENT THAT A
SHORTWAVE WILL DROP INTO THE UPPER GREAT LAKES AND ALLOW A COLD
FRONT TO BACK DOOR AND STALL OVER THE AREA DURING THE MIDDLE OF THE
WEEK...CONTINUING A THREAT OF SHOWERS AND THUNDERSTORMS.
SPECIFIC TEMPERATURES THROUGHOUT THE MEDIUM RANGE WILL BE
MODULATED BY THE AMOUNT OF CLOUD COVER....BUT IN GENERAL
HIGH TEMPS SHOULD BE REBOUNDING INTO THE 70S WITH LOWER 80S
POSSIBLE TUESDAY-THURSDAY OVER SW SECTIONS OF AREA.
TRUETT
&&
.AVIATION...
ISSUED AT 622 AM CDT FRI SEP 21 2012
OVERRUNNING PCPN DEVELOPED OVERNIGHT OVER SOUTHWESTERN MO AND IS
TRACKING TO THE EAST AND SOUTHEAST...AWAY FROM TAF SITES. FOR
NOW...WILL JUST SEE VFR CIGS WITH WINDS PICKING UP FROM THE SOUTH
AHEAD OF NEXT COLD FRONT. AS FOR PCPN CHANCES AS SYSTEM LIFTS
NORTHEAST THROUGH REGION...HARD TO PIN DOWN TIMING AND COVERAGE.
FOR NOW JUST HAVE VCNTY SHOWER MENTION AT METRO AREA TAFS AFTER
17Z. THEN WINDS BEGIN TO VEER TO THE WEST BEHIND THE
FRONT...AROUND 20Z AT KCOU...21Z AT KUIN AND AROUND 22Z AT METRO
AREA TAFS. BY THIS EVENING...WINDS TO DIMINISH FROM THE NORTHWEST
AND MID AND HIGH CLOUDS THIN OUT.
SPECIFICS FOR KSTL...OVERRUNNING PCPN DEVELOPED OVERNIGHT OVER
SOUTHWESTERN MO AND IS TRACKING TO THE EAST AND SOUTHEAST...AWAY
FROM METRO AREA. FOR NOW...WILL JUST SEE VFR CIGS WITH WINDS PICKING
UP FROM THE SOUTH AHEAD OF NEXT COLD FRONT. AS FOR PCPN CHANCES AS
SYSTEM LIFTS NORTHEAST THROUGH REGION...HARD TO PIN DOWN TIMING
AND COVERAGE. FOR NOW JUST HAVE VCNTY SHOWER MENTION AT KSTL AFTER
17Z. THEN WINDS BEGIN TO VEER TO THE WEST BEHIND THE
FRONT...AROUND 22Z AT KSTL. BY 05Z SATURDAY...WINDS TO DIMINISH
FROM THE NORTHWEST AND MID AND HIGH CLOUDS THIN OUT.
BYRD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS BUFFALO NY
139 PM EDT FRI SEP 21 2012
.SYNOPSIS...
A WEAK COLD FRONT REACHING THE EASTERN GREAT LAKES REGION WILL BRING
A CHANCE OF SHOWERS TODAY...AND POSSIBLY A THUNDERSTORM. A GREATER
CHANCE FOR WIDESPREAD RAINFALL WILL HAPPEN FRIDAY NIGHT INTO
SATURDAY AS A STRONGER COLD FRONT MOVES IN. BEHIND THE COLD FRONT
MUCH COOLER AIR WILL POUR OVER THE EASTERN GREAT LAKES THIS WEEKEND
FOR THE START OF THE AUTUMN EQUINOX.
&&
.NEAR TERM /THROUGH TONIGHT/...
REGIONAL RADARS CONTINUING TO SHOW SCATTERED SHOWER ACTIVITY
BLOSSOMING ACROSS THE AREA. LATEST HRRR AND WRF SUGGESTING THAT
THERE WILL BE ENOUGH INSTABILITY DEVELOPING IN THE VICINITY OF
THE DIFFUSE FRONTAL BOUNDARY..TO CONTINUE THE RISK FOR AT LEAST
SCATTERED SHOWER ACTIVITY THIS AFTERNOON...PRIMARILY EAST OF THE
GENESEE VALLEY. SATELLITE LOOP DOES SHOW SOME CLEARING WILL BE
WORKING INTO THE AREA FROM THE SOUTHWEST AND THIS MAY ALLOW
ATMOSPHERE TO DESTABILIZE A BIT MORE...WITH SOME OUTSIDE RISK FOR
THUNDERSTORM ACTIVITY. COVERAGE SHOULD BE VERY LIMITED.
TEMPERATURES AT 850 HPA AVERAGE BETWEEN 8 AND 10C TODAY...WITH THE
HIGHEST TEMPERATURES OVER THE FINGER LAKES REGION. EXPECT SFC
HIGHS TO BE ABLE TO SLOWLY CLIMB INTO THE UPPER 60S AND LOWER 70S
THIS AFTERNOON. ACROSS THE NORTHERN FINGER LAKES REGION SEVERAL
MID 70 READINGS ARE POSSIBLE.
TONIGHT THE FIRST BATCH OF SHOWERS WILL CARRY OFF TO THE EAST. AFTER
A BRIEF LULL ANOTHER MORE WIDESPREAD AND HEAVIER AREA OF RAIN
SHOWERS WILL ENTER THE CWA FROM THE OHIO VALLEY AS A POTENT UPPER
LEVEL TROUGH BEGINS TO PUSH INTO THE CENTRAL GREAT LAKES. MOISTURE
POOLING AHEAD OF A COLD FRONT WILL FEED RAIN SHOWERS ACROSS WESTERN
NEW YORK AND STRETCHING TOWARDS THE NORTH COUNTRY THROUGH THE
OVERNIGHT. WITH GOOD FRONTOGENETIC FORCING ALONG A BAROCLINIC
ZONE...AND DEEP MOISTURE WILL HAVE CATEGORICAL POPS ACROSS PORTIONS
OF WNY AND TOWARDS THE NORTH COUNTRY. FARTHER INLAND NEAR THE FINGER
LAKES REGION FORCING WILL NOT BE AS GREAT AND WILL HAVE HIGH END CHC
POPS.
ANOTHER MILD NIGHT AHEAD OF THE STRONGER COLD FRONT. OVERNIGHT LOWS
IN THE 50S...WITH THE MILDEST AIR LIKELY ACROSS THE FINGER LAKES
WHERE LESS EVAPORATIVE COOLING FROM FALLING RAIN WILL OCCUR.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
SATURDAY WILL START OFF WITH A CLOSED 500 MB LOW ACROSS THE UPPER
LAKES. THIS WILL GRADUALLY MOVE EAST AND LIFT INTO HUDSON BAY TOWARD
THE LATTER HALF OF THE WEEKEND. THIS WILL BRING IN PROGRESSIVELY
COLDER AIR INTO THE REGION...WITH PERIODS OF UNSETTLED SHOWERY
WEATHER.
ALTHOUGH IT IS A FAIRLY SUBTLE FEATURE...MODEL GUIDANCE (00Z
GFS/NAM/RGEM) IS IN GOOD AGREEMENT THAT A WAVE OF LOW PRESSURE WILL
LIFT NORTH OF LAKE ONTARIO SATURDAY MORNING AND INTO QUEBEC SATURDAY
AFTERNOON. ITS THIS FEATURE WHICH WILL GENERATE THE STEADIEST
SHOWERS DUE TO ASSOCIATED WARM AIR ADVECTION IN THE MID-LEVELS. THE
COLD FRONT WILL EXTEND TO THE SOUTH OF THIS...WITH THIS BOUNDARY
LIKELY TO BRING A ROUND OF SHOWERS TO MOST DURING THE DAY SATURDAY.
EXPECT A FAIRLY SOLID LINE OF SHOWERS TO CROSS FROM WEST TO EAST ON
SATURDAY...PROBABLY IMPACTING WEST OF ROCHESTER MAINLY DURING THE
MORNING HOURS...THEN MOVING EAST OF LAKE ONTARIO SATURDAY AFTERNOON.
WITH THE LATER TIMING...DAYTIME HEATING WILL HAVE TIME TO WARM
TEMPERATURES EAST OF LAKE ONTARIO. OUTSIDE OF THE WARMER DAYTIME
HIGHS...IT WILL ALSO HELP DESTABILIZE THE ATMOSPHERE. THERE IS A
CHANCE OF THUNDERSTORMS SATURDAY AFTERNOON EAST OF LAKE ONTARIO.
WIND PROFILES SHOW FAIRLY STRONG WINDS ALOFT...WITH 850 MB WINDS 40
TO 50 KTS. IF THUNDERSTORMS DEVELOP EARLY ENOUGH...THIS COULD RESULT
IN GUSTY WINDS AT THE SURFACE...HOWEVER THAT RISK IS STILL MARGINAL
WITH CLOUDS LIKELY TO LIMIT HEATING.
AFTER THIS...THE FRONT WILL USHER IN MUCH COOLER AIR BOTH AT THE
SURFACE AND ALOFT. EXPECT THE FRONT TO INITIALLY BE FOLLOWED BY DRY
WEATHER...BUT AS COOLER AIR ALOFT BUILDS IN...CHANCES FOR LAKE
ENHANCED SHOWERS WILL INCREASE. A SECONDARY COLD FRONT IS FORECAST
TO CROSS SATURDAY EVENING BY SOME MODELS...THOUGH THE 00Z NAM/GFS
ARE QUITE DIFFERENT IN HANDLING THIS...AND IN WIND FORECASTS.
BECAUSE OF THESE DIFFERENCES...HEDGE THE FORECAST A BIT TO ACCOUNT
FOR UNCERTAINTY IN WIND DIRECTION/SPEED. IN GENERAL...LAKE
EFFECT/LAKE ENHANCED SHOWERS WILL BECOME MORE FAVORABLE SATURDAY
NIGHT AND INTO SUNDAY. 850 MB TEMPERATURES WILL FALL TO NEAR 0C BY
SUNDAY MORNING...WITH DELTA T VALUES EXCEEDING 20C AND LAKE INDUCED
CAPES EXCEEDING 1500 J/JG...THEREFORE ANTICIPATE PLUMES OF MODERATE
TO OCCASIONAL HEAVY LAKE EFFECT RAINS TO DEVELOP...PRIMARILY IN
FAVORED WEST NORTHWEST FLOW AREAS.
LAKE ACTIVITY SHOULD CONTINUE INTO SUNDAY NIGHT...DIMINISHING AS WINDS
DO. THERE WILL BE ANOTHER CHANCE FOR FROST ACROSS INTERIOR PORTIONS
OF THE SOUTHERN TIER...DEPENDING ON HOW LONG SKIES CLEAR OUT.
SATURDAY CONTINUES TO LOOKS LIKE THE WARMER OF THE TWO WEEKEND DAYS
WITH HIGHS IN THE LOWER 70S AHEAD OF THE FRONT...BUT COOLING BACK
INTO THE LOWER TO MID 60S ACROSS THE WEST. SUNDAY LOOKS QUITE COOL
WITH HIGHS IN THE UPPER 50S TO LOWER 60S. A BRISK WIND WILL MAKE
THESE READINGS FEEL EVEN COOLER.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
LATEST MEDIUM RANGE MODELS AND ENSEMBLE GUIDANCE IN GOOD AGREEMENT
THAT HEIGHTS WILL INCREASE AT THE START OF THE PERIOD WITH
DIMINISHING OVER-LAKE INSTABILITY. THIS SHOULD RESULT IN A PERIOD OF
DRIER AND MILDER WEATHER...BEFORE THE NEXT COLD FRONT PUSHES THROUGH
BY MID WEEK. HIGH PRESSURE WILL BUILD DOWN ACROSS THE REGION
WEDNESDAY NIGHT AND BECOME ESTABLISHED ACROSS THE AREA THURSDAY
PROVIDING ANOTHER PERIOD OF FAIR WEATHER.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
VFR FLIGHT CONDITIONS AT 18Z WILL PERSIST THROUGH THE FIRST HALF
OF THE TAF PERIOD. A WEAK COLD FRONT WILL PASS THROUGH THE AREA
THIS AFTERNOON TRIGGERING SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS. THE THUNDERSTORM ACTIVITY COULD PRODUCE LOCALLY
HEAVY RAINS BRINGING A BRIEF PERIOD OF IFR CONDITIONS.
A STRONGER COLD FRONT WILL NEAR THE CWA LATE IN THE TAF CYCLE...WITH
STRONG FORCING AND DEEP MOISTURE BRINGING ANOTHER ROUND OF RAIN
SHOWERS...WHICH COULD BE MODERATE AT TIMES ACROSS WNY. ALONG WITH
THE RAIN FLIGHT CONDITIONS WILL DETERIORATE TO MVFR TO IFR...LARGELY
WEST OF THE GENESEE VALLEY BY 12Z.
OUTLOOK...
SATURDAY...AREAS OF MVFR/IFR WITH SHOWERS.
SUNDAY...VFR/MVFR WITH A CHANCE OF SHOWERS...ESPECIALLY SOUTHEAST OF
THE LAKES.
MONDAY THROUGH WEDNESDAY...MAINLY VFR.
&&
.MARINE...
A SOUTH TO SOUTHWESTERLY BREEZE WILL CONTINUE TO FEED 4 FOOT WAVES
ACROSS THE NORTHEASTERN SHORELINES OF LAKE ONTARIO AND INTO THE
MOUTH OF THE SAINT LAWRENCE AND BAYS ON THE EAST END OF LAKE
ONTARIO. WILL CONTINUE THIS SCA THROUGH THE EARLY AFTERNOON
HOURS...WHERE DIMINISHING WINDS SHOULD ALLOW WAVE HEIGHTS TO FALL.
LATER SATURDAY BEHIND A SFC COLD FRONT WINDS AND WAVES WILL
INCREASE OVER THE EASTERN GREAT LAKES WITH SMALL CRAFT ADVISORIES
POSSIBLE LATE SATURDAY AND THROUGH THE REMAINDER OF THE WEEKEND.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...THOMAS
NEAR TERM...THOMAS/TMA
SHORT TERM...APFFEL
LONG TERM...TMA
AVIATION...THOMAS/TMA
MARINE...THOMAS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1117 AM EDT FRI SEP 21 2012
.SYNOPSIS...
A WEAK COLD FRONT REACHING THE EASTERN GREAT LAKES REGION WILL BRING
A CHANCE OF SHOWERS TODAY...AND POSSIBLY A THUNDERSTORM. A GREATER
CHANCE FOR WIDESPREAD RAINFALL WILL HAPPEN FRIDAY NIGHT INTO
SATURDAY AS A STRONGER COLD FRONT MOVES IN. BEHIND THE COLD FRONT
MUCH COOLER AIR WILL POUR OVER THE EASTERN GREAT LAKES THIS WEEKEND
FOR THE START OF THE AUTUMN EQUINOX.
&&
.NEAR TERM /THROUGH TONIGHT/...
REGIONAL RADARS CONTINUING TO SHOW SCATTERED SHOWER ACTIVITY
BLOSSOMING ACROSS THE AREA. LATEST HRRR AND WRF SUGGESTING THAT
THERE WILL BE ENOUGH INSTABILITY DEVELOPING IN THE VICINITY OF
THE DIFFUSE FRONTAL BOUNDARY..TO CONTINUE THE RISK FOR AT LEAST
SCATTERED SHOWER ACTIVITY THIS AFTERNOON...PRIMARILY EAST OF THE
GENESEE VALLEY. SATELLITE LOOP DOES SHOW SOME CLEARING WILL BE
WORKING INTO THE AREA FROM THE SOUTHWEST AND THIS MAY ALLOW
ATMOSPHERE TO DESTABILIZE A BIT MORE...WITH SOME OUTSIDE RISK FOR
THUNDERSTORM ACTIVITY. COVERAGE SHOULD BE VERY LIMITED.
TEMPERATURES AT 850 HPA AVERAGE BETWEEN 8 AND 10C TODAY...WITH THE
HIGHEST TEMPERATURES OVER THE FINGER LAKES REGION. EXPECT SFC
HIGHS TO BE ABLE TO SLOWLY CLIMB INTO THE UPPER 60S AND LOWER 70S
THIS AFTERNOON. ACROSS THE NORTHERN FINGER LAKES REGION SEVERAL
MID 70 READINGS ARE POSSIBLE.
TONIGHT THE FIRST BATCH OF SHOWERS WILL CARRY OFF TO THE EAST. AFTER
A BRIEF LULL ANOTHER MORE WIDESPREAD AND HEAVIER AREA OF RAIN
SHOWERS WILL ENTER THE CWA FROM THE OHIO VALLEY AS A POTENT UPPER
LEVEL TROUGH BEGINS TO PUSH INTO THE CENTRAL GREAT LAKES. MOISTURE
POOLING AHEAD OF A COLD FRONT WILL FEED RAIN SHOWERS ACROSS WESTERN
NEW YORK AND STRETCHING TOWARDS THE NORTH COUNTRY THROUGH THE
OVERNIGHT. WITH GOOD FRONTOGENETIC FORCING ALONG A BAROCLINIC
ZONE...AND DEEP MOISTURE WILL HAVE CATEGORICAL POPS ACROSS PORTIONS
OF WNY AND TOWARDS THE NORTH COUNTRY. FARTHER INLAND NEAR THE FINGER
LAKES REGION FORCING WILL NOT BE AS GREAT AND WILL HAVE HIGH END CHC
POPS.
ANOTHER MILD NIGHT AHEAD OF THE STRONGER COLD FRONT. OVERNIGHT LOWS
IN THE 50S...WITH THE MILDEST AIR LIKELY ACROSS THE FINGER LAKES
WHERE LESS EVAPORATIVE COOLING FROM FALLING RAIN WILL OCCUR.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
SATURDAY WILL START OFF WITH A CLOSED 500 MB LOW ACROSS THE UPPER
LAKES. THIS WILL GRADUALLY MOVE EAST AND LIFT INTO HUDSON BAY TOWARD
THE LATTER HALF OF THE WEEKEND. THIS WILL BRING IN PROGRESSIVELY
COLDER AIR INTO THE REGION...WITH PERIODS OF UNSETTLED SHOWERY
WEATHER.
ALTHOUGH IT IS A FAIRLY SUBTLE FEATURE...MODEL GUIDANCE (00Z
GFS/NAM/RGEM) IS IN GOOD AGREEMENT THAT A WAVE OF LOW PRESSURE WILL
LIFT NORTH OF LAKE ONTARIO SATURDAY MORNING AND INTO QUEBEC SATURDAY
AFTERNOON. ITS THIS FEATURE WHICH WILL GENERATE THE STEADIEST
SHOWERS DUE TO ASSOCIATED WARM AIR ADVECTION IN THE MID-LEVELS. THE
COLD FRONT WILL EXTEND TO THE SOUTH OF THIS...WITH THIS BOUNDARY
LIKELY TO BRING A ROUND OF SHOWERS TO MOST DURING THE DAY SATURDAY.
EXPECT A FAIRLY SOLID LINE OF SHOWERS TO CROSS FROM WEST TO EAST ON
SATURDAY...PROBABLY IMPACTING WEST OF ROCHESTER MAINLY DURING THE
MORNING HOURS...THEN MOVING EAST OF LAKE ONTARIO SATURDAY AFTERNOON.
WITH THE LATER TIMING...DAYTIME HEATING WILL HAVE TIME TO WARM
TEMPERATURES EAST OF LAKE ONTARIO. OUTSIDE OF THE WARMER DAYTIME
HIGHS...IT WILL ALSO HELP DESTABILIZE THE ATMOSPHERE. THERE IS A
CHANCE OF THUNDERSTORMS SATURDAY AFTERNOON EAST OF LAKE ONTARIO.
WIND PROFILES SHOW FAIRLY STRONG WINDS ALOFT...WITH 850 MB WINDS 40
TO 50 KTS. IF THUNDERSTORMS DEVELOP EARLY ENOUGH...THIS COULD RESULT
IN GUSTY WINDS AT THE SURFACE...HOWEVER THAT RISK IS STILL MARGINAL
WITH CLOUDS LIKELY TO LIMIT HEATING.
AFTER THIS...THE FRONT WILL USHER IN MUCH COOLER AIR BOTH AT THE
SURFACE AND ALOFT. EXPECT THE FRONT TO INITIALLY BE FOLLOWED BY DRY
WEATHER...BUT AS COOLER AIR ALOFT BUILDS IN...CHANCES FOR LAKE
ENHANCED SHOWERS WILL INCREASE. A SECONDARY COLD FRONT IS FORECAST
TO CROSS SATURDAY EVENING BY SOME MODELS...THOUGH THE 00Z NAM/GFS
ARE QUITE DIFFERENT IN HANDLING THIS...AND IN WIND FORECASTS.
BECAUSE OF THESE DIFFERENCES...HEDGE THE FORECAST A BIT TO ACCOUNT
FOR UNCERTAINTY IN WIND DIRECTION/SPEED. IN GENERAL...LAKE
EFFECT/LAKE ENHANCED SHOWERS WILL BECOME MORE FAVORABLE SATURDAY
NIGHT AND INTO SUNDAY. 850 MB TEMPERATURES WILL FALL TO NEAR 0C BY
SUNDAY MORNING...WITH DELTA T VALUES EXCEEDING 20C AND LAKE INDUCED
CAPES EXCEEDING 1500 J/JG...THEREFORE ANTICIPATE PLUMES OF MODERATE
TO OCCASIONAL HEAVY LAKE EFFECT RAINS TO DEVELOP...PRIMARILY IN
FAVORED WEST NORTHWEST FLOW AREAS.
LAKE ACTIVITY SHOULD CONTINUE INTO SUNDAY NIGHT...DIMINISHING AS WINDS
DO. THERE WILL BE ANOTHER CHANCE FOR FROST ACROSS INTERIOR PORTIONS
OF THE SOUTHERN TIER...DEPENDING ON HOW LONG SKIES CLEAR OUT.
SATURDAY CONTINUES TO LOOKS LIKE THE WARMER OF THE TWO WEEKEND DAYS
WITH HIGHS IN THE LOWER 70S AHEAD OF THE FRONT...BUT COOLING BACK
INTO THE LOWER TO MID 60S ACROSS THE WEST. SUNDAY LOOKS QUITE COOL
WITH HIGHS IN THE UPPER 50S TO LOWER 60S. A BRISK WIND WILL MAKE
THESE READINGS FEEL EVEN COOLER.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
LATEST MEDIUM RANGE MODELS AND ENSEMBLE GUIDANCE IN GOOD AGREEMENT
THAT HEIGHTS WILL INCREASE AT THE START OF THE PERIOD WITH
DIMINISHING OVER-LAKE INSTABILITY. THIS SHOULD RESULT IN A PERIOD OF
DRIER AND MILDER WEATHER...BEFORE THE NEXT COLD FRONT PUSHES THROUGH
BY MID WEEK. HIGH PRESSURE WILL BUILD DOWN ACROSS THE REGION
WEDNESDAY NIGHT AND BECOME ESTABLISHED ACROSS THE AREA THURSDAY
PROVIDING ANOTHER PERIOD OF FAIR WEATHER.
&&
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
VFR FLIGHT CONDITIONS AT 12Z WILL PERSIST THROUGH THE FIRST HALF OF
THE TAF PERIOD. A WEAK COLD FRONT WILL ENTER INTO THE CWA THROUGH
THE DAY TIME TRIGGERING A FEW SHOWERS. ACTIVITY IS MOST LIKELY
FARTHER EASTWARD THROUGH THE CWA AND WILL CONTINUE TO PLACE -SHRA IN
THE KART TAF...WHILE HOLDING VCSH ELSEWHERE WHERE ACTIVITY WILL BE
LESS IN COVERAGE AREA AND DIFFICULT TO TIME. ANY THUNDER TODAY WILL
ALSO LIKELY BE GENESEE VALLEY EASTWARD...THOUGH WITH ONLY LITTLE
INSTABILITY DO NOT EXPECT MUCH...AND IT IS STILL TO EARLY TO PLACE
ANY THUNDER IN THE TAF.
THIS ACTIVITY WILL CLEAR FROM WEST TO EAST THROUGH THE DAY WITH
POSSIBLY SOME SUNSHINE LATER THIS AFTERNOON ACROSS THE WEST. THERE
MAY BE A FEW LIGHT GUSTS ACROSS THE NIAGARA FRONTIER AIRFIELDS IN
THIS SUNSHINE AS MIXING HEIGHTS INCREASE.
A STRONGER COLD FRONT WILL NEAR THE CWA LATE IN THE TAF CYCLE...WITH
STRONG FORCING AND DEEP MOISTURE BRINGING ANOTHER ROUND OF RAIN
SHOWERS...WHICH COULD BE MODERATE AT TIMES ACROSS WNY. ALONG WITH
THE RAIN FLIGHT CONDITIONS WILL DETERIORATE TO MVFR TO IFR...LARGELY
WEST OF THE GENESEE VALLEY BY 12Z.
OUTLOOK...
SATURDAY...AREAS OF MVFR/IFR WITH SHOWERS.
SUNDAY...VFR/MVFR WITH A CHANCE OF SHOWERS...ESPECIALLY SOUTHEAST OF
THE LAKES.
MONDAY AND TUESDAY...MAINLY VFR.
&&
.MARINE...
A SOUTH TO SOUTHWESTERLY BREEZE WILL CONTINUE TO FEED 4 FOOT WAVES
ACROSS THE NORTHEASTERN SHORELINES OF LAKE ONTARIO AND INTO THE
MOUTH OF THE SAINT LAWRENCE AND BAYS ON THE EAST END OF LAKE
ONTARIO. WILL CONTINUE THIS SCA THROUGH THE EARLY AFTERNOON
HOURS...WHERE DIMINISHING WINDS SHOULD ALLOW WAVE HEIGHTS TO FALL.
LATER SATURDAY BEHIND A SFC COLD FRONT WINDS AND WAVES WILL
INCREASE OVER THE EASTERN GREAT LAKES WITH SMALL CRAFT ADVISORIES
POSSIBLE LATE SATURDAY AND THROUGH THE REMAINDER OF THE WEEKEND.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EDT THIS AFTERNOON FOR LOZ045.
&&
$$
SYNOPSIS...THOMAS
NEAR TERM...THOMAS/TMA
SHORT TERM...APFFEL
LONG TERM...TMA
AVIATION...THOMAS
MARINE...THOMAS/TMA
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1016 PM EDT SAT SEP 22 2012
.SYNOPSIS...
A COLD FRONT WILL MOVE ACROSS THE AREA AND OFFSHORE LATE TONIGHT.
CANADIAN HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT AND SETTLE
OVER THE REGION THROUGH THE MIDDLE OF NEXT WEEK. A SECOND COLD
FRONT WILL MOVE IN FROM THE GREAT LAKES BY THE END OF THE WEEK AND
DISSIPATE OVER THE REGION.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 PM SATURDAY...UPSTREAM RADARS (MAINLY GSP AND RAX) SHOW
SHOWERS AND EVEN ISOLATED T-STORMS ALONG THE FRONT PUSHING EAST INTO
CENTRAL NORTH CAROLINA. THE TRAJECTORY OF THE CURRENTLY-OBSERVED
CONVECTIVE ACTIVITY WILL KEEP IT NORTH OF OUR FORECAST AREA...
HOWEVER MODELS (PARTICULARLY THE LAST SEVERAL HRRR RUNS) CONTINUE TO
SHOW AT LEAST ISOLATED SHOWERS MOVING ACROSS PORTIONS OF OUR AREA
OVERNIGHT. I`M KEEPING A SMALL 20 POP ACROSS OUR NORTHERN TIER OF
COUNTIES DOWN INTO DARLINGTON...DILLON AND NORTHERN COLUMBUS
COUNTIES...WITH THE EXPECTATION THAT MOST OF THE WEATHER ASSOCIATED
WITH THIS FRONTAL PASSAGE WILL REMAIN TO OUR NORTH. PREVIOUS
DISCUSSION FROM 730 PM FOLLOWS...
THE INLAND CUMULUS CLOUD COVER HAS NEARLY DISSIPATED LEAVING ONLY
SOME CIRRUS ALONG THE CAROLINA COAST. LOOKING UPSTREAM THERE IS A
BAND OF CLOUD COVER ASSOCIATED WITH A RATHER STRONG COLD FRONT IN
THE PIEDMONT OF NORTH CAROLINA. THIS FRONT WILL SLIDE SOUTHEAST AND
OFFSHORE LATE TONIGHT...BRINGING IN WHAT SHOULD TURN OUT TO BE THE
CHILLEST AIRMASS WE`VE SEEN SINCE BACK IN THE SPRING. UNTIL THE
FRONT ARRIVES SKIES SHOULD REMAIN MOSTLY CLEAR...WITH THE EXCEPTION
OF THE CIRRUS NEAR THE BEACHES ASSOCIATED WITH A DISTURBANCE IN THE
JET STREAM OFFSHORE.
MODELS ARE SHOWING ONLY SMALL CHANCES OF SHOWERS AS THE FRONT PUSHES
OVERHEAD LATER TONIGHT. THERE ARE NO FAVORABLE JET DYNAMICS TO SPEAK
OF. LAPSE RATES ARE FAIRLY STEEP ABOVE THE NOCTURNAL INVERSION UP
THROUGH ABOUT 650 MB (12000 FT) BUT THE MODELS ALL SHOW A SMALL
SUBSIDENCE INVERSION AT 650 MB THAT MAY CAP OFF ANY GROWING CUMULUS
TOWERS THERE. SHOWER ACTIVITY WILL DEPEND SOLELY ON LOW-LEVEL
CONVERGENCE ALONG THE ACTUAL FRONT ITSELF TO PUSH PARCELS UP THROUGH
850 MB WHERE THEY CAN RISE UNASSISTED THROUGH 650 MB. THIS SHOULD
GIVE ENOUGH VERTICAL CLOUD DEPTH (NEARLY 10000 FT) FOR ISOLATED
LIGHT SHOWERS. MODELS SHOW THE BEST OVERLAP BETWEEN STRONGER
LOW-LEVEL CONVERGENCE AND ELEVATED INSTABILITY WILL BE ACROSS OUR
INLAND COUNTIES NORTH OF FLORENCE...AND THIS IS WHERE WE`LL MAINTAIN
A 20 POP...MAINLY BETWEEN 03Z AND 06Z. ANY SHOWER ACTIVITY SHOULD
HAVE LESS THAN 10 PERCENT COVERAGE SOUTH OF FLORENCE AND CLOSER TO
THE COAST.
LOWS SHOULD REACH 59-63 INLAND AND MID 60S AT THE IMMEDIATE
COAST...NO CHANGED SIGNIFICANTLY FROM THE PREVIOUS FORECAST.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...A COLD FRONT WILL MOVE THROUGH THE FORECAST
AREA AND OFFSHORE PRIOR TO SUNRISE SUN. THE AIRMASS WILL NOT BE
SUPPORTIVE OF PRECIPITATION GIVEN THE MAGNITUDE OF DRY AIR IN THE
COLUMN WITH A BONE DRY ATMOSPHERE THROUGH THE PERIOD...ABOVE 5-6
KFT...AS HIGH PRESSURE APPROACHES FROM THE NW AND SETTLES
OVERHEAD MON AND MON NIGHT. THEREFORE WILL KEEP POPS WELL BELOW
THRESHOLD.
COLD AIR ADVECTION IS STRONG IN THE WAKE OF THIS FRONT. 850 MB
TEMPS DROP TO 9 TO 11 DEG C ON SUN AND TO 8 TO 10 DEG C ON MON.
THIS EQUATES TO TEMPS FALLING BELOW NORMAL FOR THIS TIME OF YEAR.
SKIES SHOULD BE MAINLY SUNNY BY DAY AND CLEAR AT NIGHT. GIVEN THE
COLDER AIR WILL BE JUST ARRIVING ON SUN...WE SHOULD STILL BE ABLE
TO REACH THE UPPER 70S TO LOWER 80S DURING THE AFTERNOON...SO
ABOUT NORMAL. THEN ON MON...WITH THE CHILLY AIR WELL
ESTABLISHED...WE WILL DO WELL TO REACH THE MID AND UPPER 70S.
RADIATIONAL COOLING WILL AMPLIFY THE COLD AIR ADVECTION...
ESPECIALLY MON NIGHT WHEN WINDS WILL BE VERY LIGHT IF NOT CALM
MOST OF THE NIGHT. LOWS SUN NIGHT WILL BE IN THE LOWER TO MID 50S
WITH SOME UPPER 40S ACROSS SOME LOCATIONS WELL INLAND. EXPECT MORE
WIDESPREAD 40S MON NIGHT WITH PERHAPS SOME MID 40S IN THOSE
TRADITIONALLY COLD POCKETS. LOWER 50S SHOULD HANG ON NEAR THE
BEACHES.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 3 PM SATURDAY...DRY AND FAIRLY TYPICAL EARLY FALL WEATHER
TO PERSIST THROUGH THE EXTENDED. FLAT 5H FLOW WILL TRANSITION TO
SUBTLE S/W RIDGING THURSDAY...BEFORE GENERAL TROUGHINESS
REDEVELOPS ACROSS THE EAST. AT THE SURFACE...HIGH PRESSURE WILL
DOMINATE THROUGH THE PERIOD...BROKEN UP ONLY BY A WEAK COLD FRONT
EARLY FRIDAY. COOL NE FLOW TUE WILL KEEP TEMPS BELOW
CLIMO...BEFORE WARMING TO ABOVE WED/THU. EVEN AS TEMPS WARM...VERY
DRY AIR ALOFT WILL INHIBIT ANY CONVECTION. HIGH PRESSURE DRIFTS
AWAY/WEAKENS LATE THURSDAY AHEAD OF A COLD FRONT APPROACHING FROM
THE NORTH. THESE CREATE THE ONLY RAIN CHANCES THROUGH THE
EXTENDED...BUT EVEN THIS WILL BE CAPPED AT SCHC SINCE FRONT LOOKS
MOISTURE STARVED DUE TO LACK OF ANTECEDENT MOISTURE ADVECTION.
FRONT DISSIPATES ACROSS THE AREA BY EARLY SATURDAY BRINGING A
RENEWED SHOT OF COOL/DRY AIR FOR THE START OF THE WKND.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
AS OF 00Z...HIGH CONFIDENCE FOR VFR THROUGH THE VALID PERIOD. AN
APPROACHING COLD FRONT WILL PROPAGATE ACROSS THE AREA LATE
OVERNIGHT...MOVING OFFSHORE BY SUNDAY MORNING. EXPECT LINGERING
FEW/SCT MID TO HIGH CLOUDS OVERNIGHT AND INTO THE LATE MORNING HOURS
ON SUNDAY...WITH A LOW CHANCE FOR AN ISOLATED -SHRA INLAND
OVERNIGHT. CURRENT SOUTH-SOUTHWEST WINDS AOB 12 KTS WILL DECREASE TO
AOB 5 KTS LATER THIS EVENING. AS THE FRONT PROGRESS EASTWARD...A
WINDSHIFT WILL OCCUR WITH WINDS BECOMING NORTH INTO THE MORNING
HOURS...AND NORTHEAST BY SUNDAY AFTERNOON. EXPECT SUSTAINED WINDS TO
INCREASE TO AOB 10 KTS BY THE AFTERNOON...WITH THE EARLIER
ANTICIPATED MID LAYER CLOUDS DISSIPATING...GIVING WAY TO NEARLY
CLEAR SKIES.
THE EXTENDED OUTLOOK...VFR THROUGH THE PERIOD.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 PM SATURDAY...PREVIOUS FORECAST IS ON-TRACK AND NO
CHANGES ARE NEEDED. PREVIOUS DISCUSSION FROM 730 PM FOLLOWS...
SOUTH-SOUTHWEST WINDS THIS EVENING WILL TURN NORTHERLY LATE TONIGHT
AS A RATHER STRONG COLD FRONT MOVES ACROSS THE WATERS. MODELS SHOW
ONLY A LOW PROBABILITY FOR SHOWERS ACCOMPANYING THE FRONT...AND
WE`VE INCLUDED ONLY ISOLATED SHOWER ACTIVITY IN OUR FORECAST ACROSS
THE NC WATERS LATE. SEAS ARE CURRENTLY AROUND 2 FT BUT SHOULD BUILD
TO 3 FT AWAY FROM SHORE LATER THIS EVENING...AND PERHAPS TO 4 FT OUT
NEAR 20 MILES FROM SHORE AS THE FRONT PASSES OVERHEAD LATE.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...A COLD FRONT WILL BE MOVING ACROSS THE
WATERS AT THE START OF THE PERIOD. WINDS WILL BE IN THE PROCESS OF
SHIFTING TO THE NE SUN MORNING WITH A MODEST TIGHTENING OF THE
PRESSURE GRADIENT DEVELOPING. THE TIGHTEST OF THIS GRADIENT IS
EXPECTED LATE SUN NIGHT INTO MON AND THIS IS WHEN THE SURGE SHOULD
BE MAXIMIZED. HIGHEST WINDS WILL BE NEAR 20 KT LATE SUN NIGHT INTO
MON WITH GUSTS TO 25 KT. SEAS WILL BUILD...REACHING NEAR 6 FT
ACROSS PORTIONS OF THE OUTER WATERS ON MON...HIGHEST ACROSS
AMZ250 AND AMZ252. WINDS WILL TREND LOWER LATER MON AFTERNOON AND
MON NIGHT WITH SEAS FOLLOWING SUIT MON NIGHT.
LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 3 PM SATURDAY...HIGH PRESSURE RIDGING DOWN THE COAST WILL
SLOWLY LOSE ITS GRIP ON THE WATERS DURING THE WEEK. ALTHOUGH NE
WINDS WILL PREVAIL TUE AND WED...SPEEDS DECREASE THROUGH MID WEEK
FROM AROUND 10 KTS EARLY TUESDAY TO 5 KTS OR LESS MUCH OF WEDNESDAY
AS PRESSURE GRADIENT RELAXES. ALTHOUGH A LOW AMPLITUDE E/SE SWELL
WILL EXIST WITHIN THE WAVE SPECTRUM...SEAS WILL BE ALMOST ENTIRELY
WIND DRIVEN TUE/WED...FALLING FROM 2-4 FT EARLY TUESDAY TO 1-2 FT
LATE WEDNESDAY. ON THURSDAY...LIGHT WINDS VEER THROUGH NEARLY ALL
DIRECTIONS AHEAD OF A COLD FRONT WHICH WILL APPROACH AT THE TAIL END
OF THE PERIOD. SEAS REMAIN 1-2 FT...GROWING TO 2-3 FT BY FRIDAY
MORNING.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA
SHORT TERM...RJD
LONG TERM...JDW
AVIATION...SGL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
156 PM EDT FRI SEP 21 2012
.SYNOPSIS...
THE FIRST DAY OF FALL WILL BE WARM AND BREEZY AHEAD OF A COLD FRONT.
THE COLD FRONT MOVES THROUGH THE REGION LATE SATURDAY AND SATURDAY
NIGHT...REACHING THE CAROLINA COAST SUNDAY MORNING. A NOTICEABLY
COOLER AIR MASS IS IN PLACE BEHIND THE FRONT FOR SUNDAY AND MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1010 AM FRIDAY...
THE LATEST SURFACE ANALYSIS SHOWED A VERY WEAK SURFACE TROUGH OVER
THE WESTERN PIEDMONT THIS MORNING...THOUGH OVER CENTRAL NORTH
CAROLINA THERE EXISTED VIA MSAS A SURFACE THETA-E TROUGH...MOISTURE
FLUX DIVERGENCE...AND LIFTED INDICES IN THE DOUBLE DIGITS ABOVE ZERO
CELSIUS. ALOFT...THERE WAS CONVERGENCE OVER CENTRAL NORTH CAROLINA
AT 300MB WITH THE JET AXIS JUST OFFSHORE...AND DRY AIR NOTED ON
WATER VAPOR IMAGERY. THE 12Z KMHX SOUNDING WAS STABLE...WHILE THE
12Z KGSO SOUNDING SHOWED SOME COOLING AROUND 600MB AS COMPARED TO
00Z FRIDAY. THE VISIBLE IMAGERY SHOWED LOW CLOUDS TOWARD THE
MOUNTAINS WHERE GUIDANCE SHOWS THE BEST LOW-LEVEL MOISTURE REMAINING
DURING THE DAY...AND WHERE THE LATEST HRRR WRF AND THE RUC SHOWS THE
POTENTIAL FOR JUST A FEW SHOWERS IN BETTER MOISTURE AND INSTABILITY.
06Z GFS BUFR SOUNDINGS ARE CERTAINLY STABLE TO DEEP CONVECTION...AND
THE RUC...GFS...AND NAM FORECAST SUBSIDENCE FOR THE DAY. 1000-850MB
THICKNESSES SUPPORT HIGH TEMPERATURES OF 80 TO 85...WARMEST OVER THE
FAR SOUTHWEST PIEDMONT. AMDAR SOUNDINGS TOWARD GSO SUGGESTS THAT
WITH MIXING THERE SHOULD BE A FEW WIND GUSTS IN THE LOWER TEENS
KNOTS DURING THE LATE MORNING BEFORE OVERALL BOUNDARY LAYER WINDS
BECOME FAIRLY LIGHT FOR THE MOST PART BY MID AFTERNOON. -DJF
A SERIES OF POTENT SHORTWAVES WILL PIVOT ABOUT THE UPPER VORTEX OVER
SOUTHERN ONTARIO...DEEPENING THE LONGWAVE TROUGH IN PLACE ACROSS THE
EASTERN US AND IN THE PROCESS AND PROPELLING A COLD FRONT INTO THE
OHIO AND TN VALLEYS BY DAYBREAK SATURDAY. DRY CONDITIONS WILL
CONTINUE TONIGHT ACROSS THE CAROLINAS AS SURFACE HIGH PRESSURE
CENTERED OVER THE REGION SHIFTS OFFSHORE. RISING HUMIDITY LEVELS
OVERNIGHT BRING A THREAT OF SOME PATCHY FOG AREA/STATEWIDE. LOWS IN
THE UPPER 50S TO LOWER 60S. -CBL
&&
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
AS OF 130 AM FRIDAY...
MODELS ARE IN GOOD AGREEMENT WITH TIMING OF AFOREMENTIONED COLD
FRONT THROUGH THE AREA...PUSHING IT THROUGH CENTRAL NC BETWEEN 00Z
TO 06Z SUNDAY. LOW-LEVEL THICKNESSES INCREASE ANOTHER 10 METERS IN
THE W-SWLY FLOW AHEAD OF THE FRONT...WHICH SHOULD YIELD A GOOD 3
DEGREE FAHRENHEIT INCREASE IN HIGHS ON SATURDAY...PLACING CENTRAL NC
FIRMLY INTO THE MID 80S. THIS LATE ARRIVAL OF THE FRONT WILL NOT
BENEFIT AN ALREADY MOISTURE DEPRIVED SYSTEM...WITH MODELS QUICKLY
ERASING WANING CONDITIONAL INSTABILITY OF 500 TO 1000 J/KG MLCAPE
WITH INCREASING BL CIN. WITH THE PRIMARY FORCING COMING IN THE FORM
OF SHALLOW LOW LEVEL CONVERGENCE/FGEN...IT WILL BE HARD PRESSED TO
SEE MUCH MORE THAN A WEAKENING LINE/BAND OF SHOWERS...POSSIBLY AN
ISOLATED LIGHTNING STRIKE. WILL KEEP POPS IN THE 20 TO 30 PERCENT
RANGE...HIGHEST IN THE NW PIEDMONT WHERE THE FRONT COULD INTERACT
WITH SOME WANING INSTABILITY. NW TO SE DELAYED COLD DRY AIR ADVECTION
WILL MAKE FOR A WIDE RANGE IN TEMPERATURES SATURDAY NIGHT...RANGING
FROM THE MID 50S NW TO MID 60S SE.
$$
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 230 AM FRIDAY...
A SURFACE FRONT IS PROGGED TO BE NEAR THE COAST EARLY SUNDAY
MORNING...WITH COOLER AND DRIER AIR FILTERING INTO CENTRAL NC AS
SURFACE HIGH PRESSURE BUILDS EAST. FAIR WEATHER CONDITIONS ARE
EXPECTED FOR THE MAJORITY OF THE LONG TERM PERIOD AS SURFACE HIGH
PRESSURE AND FLAT RIDGING ALOFT DOMINATES THE WEATHER. ANOTHER
FRONTAL SYSTEM MAY AFFECT THE AREA LATE WEDNESDAY INTO THURSDAY...
BUT UNCERTAINTY HAS INCREASED IN THE MODELS AND WILL THEREFORE LEAVE
THE FORECAST DRY FOR NOW. HIGHS ARE EXPECTED TO BE IN THE LOW/MID
70S EARLY IN THE PERIOD BEFORE MODERATING SLIGHTLY TO THE UPPER
70S/LOWER 80S AS RETURN FLOW COMMENCES. INITIALLY OVERNIGHT LOWS
WILL GENERALLY BE IN THE UPPER 40S TO LOW/MID 50S...WITH MID/UPPER
50S LIKELY BY THE END OF THE PERIOD.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 155 PM FRIDAY...
THROUGH THE 18Z VALID TAF PERIOD...VFR CONDITIONS ARE EXPECTED.
OVERNIGHT BETWEEN 2K AND 3K FEET...BASED ON MODEL SOUNDINGS...WINDS
SHOULD INCREASE CLOSE TO 30KT. THIS SHOULD KEEP THE AIR MASS MIXED
ENOUGH THAT THE PROBABILITY OF IFR FOG SHOULD BE LOW. THE LATEST
SREF PROBABILITIES FOR FOG WITH VISIBILITIES UNDER 3 MILES DO NOT
EVEN REGISTER IN CENTRAL NORTH CAROLINA OVERNIGHT INTO EARLY
SATURDAY. STILL...THERE COULD BE AT LEAST SOME MVFR FOG ESPECIALLY
TOWARD KRWI FOR A PERIOD OVERNIGHT WHERE THE SURFACE WIND SHOULD BE
A LITTLE LIGHTER RELATIVE TO THE REST OF CENTRAL NORTH CAROLINA.
WITH MIXING SATURDAY MORNING...WINDS SHOULD BEGIN TO GUST INTO THE
TEENS KNOTS FROM THE SOUTHWEST.
BEYOND THE 18Z VALID TAF PERIOD...A COLD FRONT MOVES THROUGH CENTRAL
NORTH CAROLINA LATE SATURDAY THROUGH THE EARLY MORNING HOURS OF
SUNDAY. THE BEST SUPPORT FOR SHOWERS AND THUNDERSTORMS IS NORTH OF
CENTRAL NORTH CAROLINA...BUT THE POTENTIAL FOR ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS EXISTS FROM VERY LATE SATURDAY AFTERNOON
BEGINNING IN THE IMMEDIATE TRIAD...ENDING IN THE PREDAWN HOURS
SUNDAY IN THE COASTAL PLAIN. A GUSTY WIND WOULD ACCOMPANY ANY
THUNDERSTORM. FROM SUNDAY THROUGH WEDNESDAY...EXPECT PREDOMINANT VFR
CONDITIONS...THOUGH AS THE WEEK CONTINUES...THERE SHOULD BE AN
INCREASE IN THE POTENTIAL FOR LOCAL LATE NIGHT AND EARLY MORNING
SUB-VFR CONDITIONS PRIMARILY AT KRWI.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DJF
NEAR TERM...DJF/CBL
SHORT TERM...CBL
LONG TERM...KRR
AVIATION...DJF
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1011 AM EDT FRI SEP 21 2012
.SYNOPSIS...
HIGH PRESSURE WILL HOLD OVER THE REGION THROUGH SATURDAY. A COLD
FRONT WILL CROSS THE REGION SATURDAY NIGHT...THEN A COOLER AIR MASS
WILL ARRIVE FOR SUNDAY THROUGH MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1010 AM FRIDAY...
THE LATEST SURFACE ANALYSIS SHOWED A VERY WEAK SURFACE TROUGH OVER
THE WESTERN PIEDMONT THIS MORNING...THOUGH OVER CENTRAL NORTH
CAROLINA THERE EXISTED VIA MSAS A SURFACE THETA-E TROUGH...MOISTURE
FLUX DIVERGENCE...AND LIFTED INDICES IN THE DOUBLE DIGITS ABOVE ZERO
CELSIUS. ALOFT...THERE WAS CONVERGENCE OVER CENTRAL NORTH CAROLINA
AT 300MB WITH THE JET AXIS JUST OFFSHORE...AND DRY AIR NOTED ON
WATER VAPOR IMAGERY. THE 12Z KMHX SOUNDING WAS STABLE...WHILE THE
12Z KGSO SOUNDING SHOWED SOME COOLING AROUND 600MB AS COMPARED TO
00Z FRIDAY. THE VISIBLE IMAGERY SHOWED LOW CLOUDS TOWARD THE
MOUNTAINS WHERE GUIDANCE SHOWS THE BEST LOW-LEVEL MOISTURE REMAINING
DURING THE DAY...AND WHERE THE LATEST HRRR WRF AND THE RUC SHOWS THE
POTENTIAL FOR JUST A FEW SHOWERS IN BETTER MOISTURE AND INSTABILITY.
06Z GFS BUFR SOUNDINGS ARE CERTAINLY STABLE TO DEEP CONVECTION...AND
THE RUC...GFS...AND NAM FORECAST SUBSIDENCE FOR THE DAY. 1000-850MB
THICKNESSES SUPPORT HIGH TEMPERATURES OF 80 TO 85...WARMEST OVER THE
FAR SOUTHWEST PIEDMONT. AMDAR SOUNDINGS TOWARD GSO SUGGESTS THAT
WITH MIXING THERE SHOULD BE A FEW WIND GUSTS IN THE LOWER TEENS
KNOTS DURING THE LATE MORNING BEFORE OVERALL BOUNDARY LAYER WINDS
BECOME FAIRLY LIGHT FOR THE MOST PART BY MID AFTERNOON. -DJF
A SERIES OF POTENT SHORTWAVES WILL PIVOT ABOUT THE UPPER VORTEX OVER
SOUTHERN ONTARIO...DEEPENING THE LONGWAVE TROUGH IN PLACE ACROSS THE
EASTERN US AND IN THE PROCESS AND PROPELLING A COLD FRONT INTO THE
OHIO AND TN VALLEYS BY DAYBREAK SATURDAY. DRY CONDITIONS WILL
CONTINUE TONIGHT ACROSS THE CAROLINAS AS SURFACE HIGH PRESSURE
CENTERED OVER THE REGION SHIFTS OFFSHORE. RISING HUMIDITY LEVELS
OVERNIGHT BRING A THREAT OF SOME PATCHY FOG AREA/STATEWIDE. LOWS IN
THE UPPER 50S TO LOWER 60S. -CBL
&&
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
AS OF 130 AM FRIDAY...
MODELS ARE IN GOOD AGREEMENT WITH TIMING OF AFOREMENTIONED COLD
FRONT THROUGH THE AREA...PUSHING IT THROUGH CENTRAL NC BETWEEN 00Z
TO 06Z SUNDAY. LOW-LEVEL THICKNESSES INCREASE ANOTHER 10 METERS IN
THE W-SWLY FLOW AHEAD OF THE FRONT...WHICH SHOULD YIELD A GOOD 3
DEGREE FAHRENHEIT INCREASE IN HIGHS ON SATURDAY...PLACING CENTRAL NC
FIRMLY INTO THE MID 80S. THIS LATE ARRIVAL OF THE FRONT WILL NOT
BENEFIT AN ALREADY MOISTURE DEPRIVED SYSTEM...WITH MODELS QUICKLY
ERASING WANING CONDITIONAL INSTABILITY OF 500 TO 1000 J/KG MLCAPE
WITH INCREASING BL CIN. WITH THE PRIMARY FORCING COMING IN THE FORM
OF SHALLOW LOW LEVEL CONVERGENCE/FGEN...IT WILL BE HARD PRESSED TO
SEE MUCH MORE THAN A WEAKENING LINE/BAND OF SHOWERS...POSSIBLY AN
ISOLATED LIGHTNING STRIKE. WILL KEEP POPS IN THE 20 TO 30 PERCENT
RANGE...HIGHEST IN THE NW PIEDMONT WHERE THE FRONT COULD INTERACT
WITH SOME WANING INSTABILITY. NW TO SE DELAYED COLD DRY AIR ADVECTION
WILL MAKE FOR A WIDE RANGE IN TEMPERATURES SATURDAY NIGHT...RANGING
FROM THE MID 50S NW TO MID 60S SE.
$$
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 230 AM FRIDAY...
A SURFACE FRONT IS PROGGED TO BE NEAR THE COAST EARLY SUNDAY
MORNING...WITH COOLER AND DRIER AIR FILTERING INTO CENTRAL NC AS
SURFACE HIGH PRESSURE BUILDS EAST. FAIR WEATHER CONDITIONS ARE
EXPECTED FOR THE MAJORITY OF THE LONG TERM PERIOD AS SURFACE HIGH
PRESSURE AND FLAT RIDGING ALOFT DOMINATES THE WEATHER. ANOTHER
FRONTAL SYSTEM MAY AFFECT THE AREA LATE WEDNESDAY INTO THURSDAY...
BUT UNCERTAINTY HAS INCREASED IN THE MODELS AND WILL THEREFORE LEAVE
THE FORECAST DRY FOR NOW. HIGHS ARE EXPECTED TO BE IN THE LOW/MID
70S EARLY IN THE PERIOD BEFORE MODERATING SLIGHTLY TO THE UPPER
70S/LOWER 80S AS RETURN FLOW COMMENCES. INITIALLY OVERNIGHT LOWS
WILL GENERALLY BE IN THE UPPER 40S TO LOW/MID 50S...WITH MID/UPPER
50S LIKELY BY THE END OF THE PERIOD.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
AS OF 1010 AM FRIDAY...
24-HR TAF PERIOD:
EXPECT VFR CONDITIONS TO PREVAIL THE REMAINDER OF THE TAF PERIOD IN
ASSOCIATION WITH DRY HIGH PRESSURE OVER THE AREA. THERE COULD BE
SOME EARLY MORNING FOG AGAIN SATURDAY MORNING...HOWEVER LATEST FCST
SOUNDINGS ARE SHOWING LESS IN THE WAY OF FOG...POTENTIALLY DUE TO A
STEADY SWLY BREEZE OF ABOUT 3 TO 5 KTS...AND THUS HAVE OPTED NOT TO
INCLUDE ANY FOG AT THIS TIME.
OUTLOOK:
STRENGTHENING SOUTHERLY RETURN FLOW AHEAD OF AN APPROACHING COLD
FRONT WILL RESULT IN BREEZY SOUTHWESTERLY WINDS OF 10-20KT DURING
THE DAY ON SATURDAY. A COLD FRONT WILL PUSH SOUTHEAST THROUGH THE
AREA BETWEEN 00 TO 06Z SUNDAY. A FEW SHOWERS OR STORMS MAY ACCOMPANY
THE PASSAGE OF THE COLD FRONT...AND COULD PRODUCE A BRIEF PERIOD OF
SUB-VFR CONDITIONS IN RAIN. OTHERWISE...VFR CONDITIONS ARE EXPECTED
SUNDAY THROUGH TUESDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CBL
NEAR TERM...DJF/CBL
SHORT TERM...CBL
LONG TERM...KRR
AVIATION...CBL
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1140 AM CDT FRI SEP 21 2012
.DISCUSSION...
WATER VAPOR LOOP INDICATED CIRCULATION CENTER OVER NORTH LAKE
WINNIPEG AND MOVING SOUTH ABOUT 35 KNOTS. CANADIAN RADAR INDICATED
PRECIPITATION WAS SOUTH AND EAST OF SHORT WAVE. SO WILL TRIM BACK
POPS OVER THE NORTHERN RED RIVER VALLEY AND SHIFT MORE OVER
NORTHWEST MN.
COLD FRONT OVER SOUTHERN MAN WILL MOVE QUICKLY ACROSS THE FORECAST
AREA THIS AFTERNOON AND EVENING. FRONT FORECAST TO REACH SOUTHERN MN
BY MIDNIGHT. LOWERED TEMPS A TAD FOR THIS AFTERNOON.
MODEL SOUNDINGS INDICATED GOOD MIXING UP TO 800 HPA FOR THIS
AFTERNOON AND EARLY EVENING. POTENTIAL TO MIX DOWN ABOUT 40 KNOTS
WIND. RESPECTABLE PRESSURE RISES EXPECTED JUST NORTH OF COLD FRONT.
THINK WINDS WILL BE STRONGEST POST FRONTAL FOR ONE TO THREE HOURS.
WILL EXTEND WIND ADVISORY FOR THE FORECAST AREA OUTSIDE OF WOODED
AREA IN EASTERN ZONES AND EXTEND IN TIME TO 03Z SAT.
&&
.PREVIOUS DISCUSSION.../ISSUED 328 AM CDT FRI SEP 21 2012/
WATER VAPOR SHOWS A VORT MAX NEAR PARK RAPIDS WITH A ELONGATED
VORT LOBE NORTHWEST INTO SOUTHEAST MANITOBA. JUST WEST OF THIS
VORT LOBE REMAINS CLOUDS AND A FEW SHOWERS WHICH HAVE CONTINUED TO
DROP SOUTHEAST ACROSS THE FCST AREA. CANADIAN RADARS AND SATELLITE
INDICATE THE LAST OF THE SHOWERS NOW BTWN GFK/DVL WITH CLEARING
UPSTREAM AT BRANDON MB. COORD WITH MPX AND DID INCLUDE A LOW POP
FOR REMAINING -SHRA IN THE 12Z-15Z FRI TIME PERIOD IN WCNTRL MN
BASED ON LATEST HRRR MODEL.
THEN FOCUS TODAY WILL BE ON POTENT AND FAST MOVING UPPER LOW WHICH
WILL DROP SOUTH TODAY. CURRENTLY IN NRN MANITOBA...UPR LOW WILL
DROP INTO NORTH CENTRAL MINNESOTA NR BAUDETTE AT 00Z. ON WEST SIDE
OF UPPER LOW WILL BE SOME SIGNIFICANT DRYING ALOFT ALONG WITH A
130KT 300 MB JET. AS SYSTEMS DROP SOUTH...A COLD FRONT WILL DROP
SOUTH ON ITS WEST SIDE AND ENTER FAR NE ND AROUND 18Z THEN DROP
SOUTH THROUGH GFK 20Z TIME FRAME AND THEN TOWARD FARGO 22Z TIME
FRAME. NAM12 AND RAPID REFRESH MODEL SOUNDINGS ALL SHOW A PERIOD OF
GOOD MIXING UP PAST 850 MB WITH UNIDIRECTIONAL FLOW FROM THE NORTH
JUST BEHIND FRONTAL PASSAGE. 850 MB WINDS OF 35-40 KTS WILL BE
PRESENT AND SHOULD BE ABLE TO BE MIXED DOWN. ALSO 3 HR PRESSURE
RISES IN THE 6 MB RANGE WILL OCCUR BEHIND FRONT. FAVORED NORTH WIND
DIRECTION SHOULD ENHANCE WIND POTENTIAL IN THE RED RIVER VALLEY
ESPECIALLY. BASED ON WIND POTENTIAL DID A WIND ADV FOR THIS AFTN FOR
DVL BASIN INTO MOST OF THE RED RIVER VALLEY. WOULD APPEAR BASED ON
TRACK OF UPPER LOW MOST OF THE STEADIER LIGHT RAIN WILL IMPACT THE
FAR EASTERN FCST AREA THIS AFTN INTO EVE....WITH CHANCE SHOWERS
FARTHER WEST INTO ERN ND.
MODEL RH FIELDS INDICATE FAST CLEARING OVER ALL BUT FAR EAST
DURING TONIGHT PERIOD AS HIGH PRESSURE MOVES INTO SE SASK AND
NORTH CNTRL ND. LOCATION OF HIGH WOULD FAVOR BEST CHC OF WELL
BELOW FREEZING TEMPS OVER THE MOT-BIS REGION. ALL MODELS SFC TEMPS
DO INDICATE SOME UPR 20S AS FAR EAST AS LANGDON-COOPERSTOWN AREAS
AS WINDS DIMINISH THERE LATE TONIGHT. BUT STILL SOME UNCERTAINTY
ON THIS SO DID A FREEZE WATCH INSTEAD OF FREEZE WARNING AT THIS
STAGE. FARTHER EAST INTO THE RED RIVER VALLEY WINDS SHOULD STAY UP
10 KTS OR SO EVEN LATE AT NIGHT. TEMPS WILL FALL INTO THE 32-35 RANGE
BUT WINDS WILL PRECLUDE ANY TRUE FROST. NO HEADLINES ATTM....BUT
AGAIN LATER SHIFTS CAN EVALUATE IT FOR ANY PSBL ADVISORY HEADLINES
INTO THE RED RIVER VALLEY OR NW MN.
HIGH PRESSURE WILL BE OVER CNTRL ND SATURDAY. EXPECT GOOD DEAL OF DIURNAL
CU TO FORM EAST OF THE RED RIVER PER RH FIELDS. SHOULD BE COOL
WITH HIGHS UPPER 40S FAR EAST TO MID 50S.
SAT NIGHT-EARLY SUNDAY MORNING LOOKS LIKE A WIDESPREAD FREEZE
EVENT. HIGH PRESSURE PROGGED A BIT SLOWER THAN PAST RUNS INDICATED
WITH HIGH PRESSURE OVER THE VALLEY AT 12Z SUN. GEM MODEL A BIT
SLOWER STILL. WENT FROST IN GRIDS AND LOWS MOSTLY 25 TO 30. COORD
WITH NEIGHBORING OFFICES WILL HOLD OFF ON ANY HEADLINES FOR SAT
NIGHT EVENT AS PLENTY OF TIME TO DO ADD THEM.
SUNDAY WILL START OFF COOL AND WARM UP NICELY WITH LIGHT SOUTHERLY
WINDS AND PLENTY OF SUN.
LONG TERM (MONDAY-THURSDAY)...
MAINLY DRY WEATHER IS EXPECTED THROUGHOUT THIS PERIOD...WITH THE
MAIN FORECAST CHALLENGE BEING TEMPS. TEMPS ON MONDAY LOOK TO BE
ABOVE AVERAGE IN THE UPPER 60S TO MID 70S...WITH 850 MB TEMPS RISING
INTO THE LOW TEENS OVER SOUTHERN PORTIONS OF THE AREA. RECENT
OPERATIONAL MODEL RUNS HAVE SHOWN A SERIES OF IMPULSES DROPPING
SOUTHWARD INTO THE UPPER MIDWEST THROUGH MID-WEEK ON THE WESTERN
EDGE OF THE SLOWLY PROGRESSING UPPER LOW OVER EASTERN NORTH AMERICA.
AS A RESULT...TUESDAY AND WEDNESDAY HAVE TRENDED A BIT COOLER WITH
HIGHS IN THE 50S AND 60S AND LOWS IN THE 30S TO LOW 40S..AS CANADIAN
HIGH PRESSURE BUILDS SOUTH. IT APPEARS SOME WARMER AIR WILL BEGIN TO
WORK ITS WAY BACK INTO THE AREA BY THURSDAY AS THE PESKY EASTERN US
UPPER LOW FINALLY SHIFTS EAST AND MORE ZONAL MID/UPPER FLOW SPREADS
ACROSS THE CENTRAL US. PRECIP CHANCES WITH ANY OF THE IMPULSES
AFFECTING THE REGION ARE TOO LOW FOR ANY MENTION AT THIS TIME.
.AVIATION...
FOCUS TODAY WILL BE ON WINDS. LOOK FOR A NORTHWEST WIND 5 TO 15
KTS THIS MORNING INCREASING A BIT LATE MORNING-EARLY AFTN. FRONT
WILL HIT DVL-GFK-TVF AREAS IN THE 19Z-20Z TIME PERIOD WITH A WIND
SHIFT TO THE NORTH-NORTHWEST AND LIKELY GUSTS OVER 35 KTS. WIND
WILL HIT FARGO CLOSER TO 21-22Z WITH WIND SHIFT AND GUSTS THERE.
BEMIDJI WILL SEE LESS WIND BUT MORE SHOWERS THIS AFTN. ATTM
EXPECT VFR CLOUDS IN THE SHOWERS BUT COULD SEE SOME MVFR CIGS.
WINDS WILL DIMINISH THIS EVE.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...WIND ADVISORY FROM 4 PM THIS AFTERNOON TO 10 PM CDT THIS
EVENING FOR NDZ028>030-038-039-049-052-053.
FREEZE WATCH FROM LATE TONIGHT THROUGH SATURDAY MORNING FOR
NDZ006-007-014-015-024-026-028-054.
WIND ADVISORY UNTIL 10 PM CDT THIS EVENING FOR NDZ006>008-
014>016-024-026-027-054.
MN...WIND ADVISORY FROM 4 PM THIS AFTERNOON TO 10 PM CDT THIS EVENING
FOR MNZ002-003-022-027-029>031-040.
WIND ADVISORY UNTIL 10 PM CDT THIS EVENING FOR MNZ001-004-005-
007-008-013>015.
&&
$$
HOPPES
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
328 AM CDT FRI SEP 21 2012
.SHORT TERM...
WATER VAPOR SHOWS A VORT MAX NEAR PARK RAPIDS WITH A ELONGATED
VORT LOBE NORTHWEST INTO SOUTHEAST MANITOBA. JUST WEST OF THIS
VORT LOBE REMAINS CLOUDS AND A FEW SHOWERS WHICH HAVE CONTINUED TO
DROP SOUTHEAST ACROSS THE FCST AREA. CANADIAN RADARS AND SATELLITE
INDICATE THE LAST OF THE SHOWERS NOW BTWN GFK/DVL WITH CLEARING
UPSTREAM AT BRANDON MB. COORD WITH MPX AND DID INCLUDE A LOW POP
FOR REMAINING -SHRA IN THE 12Z-15Z FRI TIME PERIOD IN WCNTRL MN
BASED ON LATEST HRRR MODEL.
THEN FOCUS TODAY WILL BE ON POTENT AND FAST MOVING UPPER LOW WHICH
WILL DROP SOUTH TODAY. CURRENTLY IN NRN MANITOBA...UPR LOW WILL
DROP INTO NORTH CENTRAL MINNESOTA NR BAUDETTE AT 00Z. ON WEST SIDE
OF UPPER LOW WILL BE SOME SIGNIFICANT DRYING ALOFT ALONG WITH A
130KT 300 MB JET. AS SYSTEMS DROP SOUTH...A COLD FRONT WILL DROP
SOUTH ON ITS WESTSIDE AND ENTER FAR NE ND AROUND 18Z THEN DROP
SOUTH THROUGH GFK 20Z TIME FRAME AND THEN TOWARD FARGO 22Z TIME
FRAME. NAM12 AND RAPID REFRESH MODEL SOUNDINGS ALL SHOW A PERIOD
OF GOOD MIXING UP PAST 850 MB WITH UNIDIRECTIONAL FLOW FROM THE
NORTH JUST BEHIND FRONTAL PASSAGE. 850 MB WINDS OF 35-40 KTS WILL
BE PRESENT AND SHOULD BE ABLE TO BE MIXED DOWN. ALSO 3 HR PRESSURE
RISES IN THE 6 MB RANGE WILL OCCUR BEHIND FRONT. FAVORED NORTH
WIND DIRECTION SHOULD ENHANCE WIND POTENTIAL IN THE RED RIVER
VALLEY ESPECIALLY. BASED ON WIND POTENTIAL DID A WIND ADV FOR THIS
AFTN FOR DVL BASIN INTO MOST OF THE RED RIVER VALLEY. WOULD APPEAR
BASED ON TRACK OF UPPER LOW MOST OF THE STEADIER LIGHT RAIN WILL
IMPACT THE FAR EASTERN FCST AREA THIS AFTN INTO EVE....WITH CHANCE
SHOWERS FARTHER WEST INTO ERN ND.
MODEL RH FIELDS INDICATE FAST CLEARING OVER ALL BUT FAR EAST
DURING TONIGHT PERIOD AS HIGH PRESSURE MOVES INTO SE SASK AND
NORTH CNTRL ND. LOCATION OF HIGH WOULD FAVOR BEST CHC OF WELL
BELOW FREEZING TEMPS OVER THE MOT-BIS REGION. ALL MODELS SFC TEMPS
DO INDICATE SOME UPR 20S AS FAR EAST AS LANGDON-COOPERSTOWN AREAS
AS WINDS DIMINISH THERE LATE TONIGHT. BUT STILL SOME UNCERTAINITY
ON THIS SO DID A FREEZE WATCH INSTEAD OF FREEZE WARNING AT THIS
STAGE. FARTHER EAST INTO THE RED RIVER VALLEY WINDS SHOULD STAY UP
10 KTS OR SO EVEN LATE AT NIGHT. TEMPS WILL FALL INTO THE 32-35 RANGE
BUT WINDS WILL PRECLUDE ANY TRUE FROST. NO HEADLINES ATTM....BUT
AGAIN LATER SHIFTS CAN EVALUATE IT FOR ANY PSBL ADVISORY HEADLINES
INTO THE RED RIVER VALLEY OR NW MN.
HIGH PRESSURE WILL BE OVER CNTRL ND SATURDAY. EXPECT GOOD DEAL OF DIURNAL
CU TO FORM EAST OF THE RED RIVER PER RH FIELDS. SHOULD BE COOL
WITH HIGHS UPPER 40S FAR EAST TO MID 50S.
SAT NIGHT-EARLY SUNDAY MORNING LOOKS LIKE A WIDESPREAD FREEZE
EVENT. HIGH PRESSURE PROGGED A BIT SLOWER THAN PAST RUNS INDICATED
WITH HIGH PRESSURE OVER THE VALLEY AT 12Z SUN. GEM MODEL A BIT
SLOWER STILL. WENT FROST IN GRIDDS AND LOWS MOSTLY 25 TO 30. COORD
WITH NEIGHBORING OFFICES WILL HOLD OFF ON ANY HEADLINES FOR SAT
NIGHT EVENT AS PLENTY OF TIME TO DO ADD THEM.
SUNDAY WILL START OFF COOL AND WARM UP NICELY WITH LIGHT SOUTHERLY
WINDS AND PLENTY OF SUN.
LONG TERM (MONDAY-THURSDAY)...
MAINLY DRY WEATHER IS EXPECTED THROUGHOUT THIS PERIOD...WITH THE
MAIN FORECAST CHALLENGE BEING TEMPS. TEMPS ON MONDAY LOOK TO BE
ABOVE AVERAGE IN THE UPPER 60S TO MID 70S...WITH 850 MB TEMPS RISING
INTO THE LOW TEENS OVER SOUTHERN PORTIONS OF THE AREA. RECENT
OPERATIONAL MODEL RUNS HAVE SHOWN A SERIES OF IMPULSES DROPPING
SOUTHWARD INTO THE UPPER MIDWEST THROUGH MID-WEEK ON THE WESTERN
EDGE OF THE SLOWLY PROGRESSING UPPER LOW OVER EASTERN NORTH AMERICA.
AS A RESULT...TUESDAY AND WEDNESDAY HAVE TRENDED A BIT COOLER WITH
HIGHS IN THE 50S AND 60S AND LOWS IN THE 30S TO LOW 40S..AS CANADIAN
HIGH PRESSURE BUILDS SOUTH. IT APPEARS SOME WARMER AIR WILL BEGIN TO
WORK ITS WAY BACK INTO THE AREA BY THURSDAY AS THE PESKY EASTERN US
UPPER LOW FINALLY SHIFTS EAST AND MORE ZONAL MID/UPPER FLOW SPREADS
ACROSS THE CENTRAL US. PRECIP CHANCES WITH ANY OF THE IMPULSES
AFFECTING THE REGION ARE TOO LOW FOR ANY MENTION AT THIS TIME.
.AVIATION...
FOCUS TODAY WILL BE ON WINDS. LOOK FOR A NORTHWEST WIND 5 TO 15
KTS THIS MORNING INCREASING A BIT LATE MORNING-EARLY AFTN. FRONT
WILL HIT DVL-GFK-TVF AREAS IN THE 19Z-20Z TIME PERIOD WITH A WIND
SHIFT TO THE NORTH-NORTHWEST AND LIKELY GUSTS OVER 35 KTS. WIND
WILL HIT FARGO CLOSER TO 21-22Z WITH WIND SHIFT AND GUSTS THERE.
BEMIDJIJ WILL SEE LESS WIND BUT MORE SHOWERS THIS AFTN. ATTM
EXPECT VFR CLOUDS IN THE SHOWERS BUT COULD SEE SOME MVFR CIGS.
WINDS WILL DIMINISH THIS EVE.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...FREEZE WATCH FROM LATE TONIGHT THROUGH SATURDAY MORNING FOR
NDZ006-007-014-015-024-026-028-054.
WIND ADVISORY FROM 1 PM THIS AFTERNOON TO 6 PM CDT THIS EVENING
FOR NDZ006>008-014>016-026-027-054.
WIND ADVISORY FROM 3 PM THIS AFTERNOON TO 7 PM CDT THIS EVENING
FOR NDZ029-030-039.
MN...WIND ADVISORY FROM 1 PM THIS AFTERNOON TO 6 PM CDT THIS EVENING
FOR MNZ001-004-007.
WIND ADVISORY FROM 3 PM THIS AFTERNOON TO 7 PM CDT THIS EVENING
FOR MNZ002-003.
&&
$$
RIDDLE/MAKOWSKI
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
141 AM EDT FRI SEP 21 2012
.SYNOPSIS...
A WEAK COLD FRONT WILL PUSH EAST OF THE AREA TONIGHT. LOW PRESSURE
WILL MOVE ACROSS THE CENTRAL LAKES EARLY SATURDAY DRAGGING A STRONG
COLD FRONT ACROSS THE AREA.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
RUC CONTINUES TO OUTPERFORM HRRR THIS EVENING. PROBABLY WILL SEE
JUST WIDELY SCT SPRINKLES SHIFT EAST REST OF THE NIGHT BUT WILL KEEP
SLIGHT CHANCE POPS THAT DECREASE WEST TO EAST REST OF THE NIGHT AS
TROUGH AND FIRST WAVES OF ENERGY SHIFT INTO THE EAST.
SLIGHT UPWARD ADJUSTMENT TO TEMPS FOR ADDED CLOUDS OVERNIGHT BUT
MAINLY FOR EAST HALF OF CWA WHERE CLOUDS SHOULD PERSIST LONGER.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/...
MODELS STILL NOT IN TOTAL AGREEMENT ON THE TRACK AND TIMING OF THE
NEXT COLD FRONT THAT WILL MOVE ACROSS THE AREA FRIDAY NIGHT INTO
SATURDAY MORNING. NAM STILL THE FASTEST OF THE 3 MODELS. BASICALLY
RAIN WILL DEVELOP FROM THE WEST TOMORROW EVENING AND MOVE ACROSS THE
AREA FRIDAY NIGHT. COULD SEE A FEW LINGERING SHOWERS IN THE EAST
SATURDAY MORNING...BUT MOST OF AREA WILL SEE LULL SATURDAY MORNING.
THEN SECONDARY TROUGH FORECAST TO ROTATE ACROSS THE AREA SATURDAY
AFTERNOON INTO SATURDAY NIGHT. BY 12Z SUNDAY 850 TEMPS DIP TO 0C
SETTING UP POTENTIAL FOR SOME LAKE EFFECT SHOWERS IN THE SNOWBELT
EAST OF CLEVELAND.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
THE LONG TERM PORTION BEGINS ON MONDAY WITH THE GFS AND ECMWF
SIMILAR. BOTH SHOW HIGH SURFACE PRESSURE ACROSS THE TENNESSEE AND
LOWER OHIO VALLEY AND AN UPPER LOW OVER HUDSON BAY. 850MB TEMPS
ACROSS THE AREA ALSO SIMILAR AT 2 TO 4C. GFS HOWEVER SHOWS DRY AIR
ACROSS THE AREA WHILE THE ECMWF IS A BIT MORE MOIST WITH MORE OF A
NORTHWEST FLOW ALOFT. GIVEN THE DIFFERENCE WILL SIDE WITH THE NEWER
GFS. WILL HAVE A SLIGHT CHANCE OF A SHOWER IN THE SNOW BELT
COUNTIES BUT WITH THE DRY AIR IN PLACE...NOT LOOKING FOR MUCH.
TUESDAY MODELS COME MORE INTO PHASE WITH THE UPPER TROF NOW
EXTENDING AVER THE GREAT LAKES AND THE SURFACE HIGH NOW MOVING OFF
THE MID ATLANTIC COAST. THE GFS HOWEVER SHOWS AN EMBEDDED SHORT WAVE
WITH ASSOCIATED MOISTURE MOVING ACROSS THE AREA DURING THE DAY WHILE
THE ECMWF DOES NOT SHOW THIS. WILL SIDE MORE TOWARD THE DRIER ECMWF
GIVEN EVERYTHING ELSE IS FAIRLY CLOSE. THE MODELS DO SHOW WARMER AIR
MOVING INTO THE AREA WHICH WOULD FAVOR MORE OF A PARTLY SUNNY DAY VS
CLOUDS. WEDNESDAY A SHORT WAVE RIDGE WILL BE MOVING ACROSS WESTERN
ONTARIO KICKING THE UPPER TROF FURTHER EAST ACROSS THE GREAT LAKES.
MODELS START TO DIFFER AGAIN WITH THE GFS TAKING A COLD FRONT SOUTH
ACROSS THE REGION WHILE THE ECMWF IS MUCH SLOWER. WILL SIDE HERE
WITH THE GFS AGAIN AND BRING THE FRONT THROUGH GIVEN THE SIZE AND
POSITION OF THE SURFACE HIGH TO OUR NORTH.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
WEAK COLD FRONT CONTINUES TO MOVE ACROSS THE EASTERN HALF OF THE
REGION. THERE ARE STILL A FEW SPRINKLES AHEAD OF IT BUT BELIEVE
ONLY THE KERI AREA MAY SEE THEM. OTHERWISE EXPECT TO SEE VFR
CEILINGS FLUCTUATE IN HEIGHT INTO FRIDAY EVENING. THERE MAY BE
SOME POCKETS OF MVFR VISIBILITIES AS CEILINGS LOWER TO LOW END VFR
AFTER 00Z SATURDAY. ANY PERSIST RAIN WILL LIKELY OCCUR AFTER 02Z.
OUTLOOK...AREAS OF NON VFR IN SHOWERS FRI NIGHT THROUGH SATURDAY NIGHT
FOR ALL LOCATIONS. NON VFR MAY CONTINUE INTO SUNDAY NIGHT ACROSS
NE OHIO INTO NW PA.
&&
.MARINE...
LAKE REMAINS CHOPPY WITH A SSW FLOW. HAVE ALLOWED THE WEST END SMALL
CRAFT TO EXPIRE WITH SUSTAINED WIND SPEEDS UNDER 22 KNOTS. THINK THE
2 TO 4 FEET WILL HOLD ACROSS THE EAST END AS WE ARE EXPECTING A
SUBTLE WIND SHIFT THIS EVENING BUT WINDS RELAXING SOME. IN GENERAL
SOUTHWEST FLOW CONTINUES WITH UPPER TROUGH/CYCLONIC FLOW ACROSS THE
NORTHERN AND CENTRAL LAKES FROM FRIDAY INTO SATURDAY. BETWEEN THOSE
TWO DAYS THERE WILL BE SLIGHT FLUCTUATIONS IN THE WIND DIRECTION
WITH WEAK DISTURBANCES MOVING ACROSS. BY SATURDAY NIGHT THE UPPER
TROUGH SWINGS ACROSS THE EASTERN LAKES AND THE WEST-NORTHWEST FLOW
INCREASES. IT IS UNCERTAIN HOW STRONG WINDS MAY BE WITH ONE MODEL
HINTING AT GALES AND ANOTHER MUCH LESS. FOR NOW WILL STICK AT 20-25
KNOTS. SMALL CRAFT ADVISORY POSSIBLE SATURDAY AND LIKELY SUNDAY. IT
WILL NOT TAKE MUCH TO KICK UP THE LAKE THIS TIME OF YEAR. HIGH
PRESSURE BUILDS ACROSS THE LAKE EARLY NEXT WEEK.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DJB
NEAR TERM...DJB
SHORT TERM...DJB
LONG TERM...TK
AVIATION...MULLEN
MARINE...OUDEMAN
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
115 PM CDT FRI SEP 21 2012
.UPDATE...SEE AVIATION.
&&
.AVIATION...18Z TAFS.
VFR. SFC LOW PRES SYS WL TREK E ACROSS THE OHVLY THIS AFTN-EVE.
MAINLY CI SOUTH OF THE BOUNDARY WITH SOME B/L MOISTENING IN THE
MODELS LATE TNGT...STILL KEPT VFR. COLD FRONT EXPECTED TO PUSH
INTO THE REGION AROUND 22/12Z...WITH NW WIND SHIFT AND SCT
MIDDECK SAT.
&&
.PREV DISCUSSION... /ISSUED 905 AM CDT FRI SEP 21 2012/
UPDATE...CONVECTION MOVING INTO WEST TN. LATEST IR SATELLITE
IMAGES SHOW CLOUD TOPS WARMING SIGNIFICANTLY. THIS IS USUALLY A
PRECURSOR TO DE-INTENSIFICATION. HRRR MESO MODEL ALSO INDICATES
THAT THIS AREA WILL WEAKEN WHILE SPREADING EWD AND NEWD. THUS IT
SEEMS OUR SLGT CHC POP FOR THE NRN AND NWRN COUNTIES WILL BE OK.
NO SIGNIFICANT CHANGES FOR NOW.
PREV DISCUSSION... /ISSUED 635 AM CDT FRI SEP 21 2012/
UPDATE...FOR 12Z AVIATION FORECAST
AVIATION...
COMPLEX OVER SOUTHEAST MISSOURI THIS MORNING ON THE NOSE OF A 45
KNOT SOUTHWESTERLY LOW LEVEL JET AND IS IN THE RIGHT REAR QUADRANT
OF A 65 KNOT WESTERLY MID-LEVEL JET. H-TRIPLE-R HAS THIS FEATURE
INITIALIZED WELL AND WORKS IT EASTWARD WHILE WEAKENING IT ACROSS
FAR WESTERN KENTUCKY AND WESTERN TENNESSEE THROUGH ABOUT 15Z THEN
DRAGS WHATS LEFT ACROSS NORTHERN MIDDLE TENNESSEE AND CONTINUES
TO WEAKEN AS IT APPROACHES NASHVILLE. WILL FORECAST VCSH FOR
CLARKSVILLE FROM ABOUT 15Z UNTIL 17Z AND FOR NASHVILLE FROM ABOUT
18Z UNTIL 20Z. WINDS WILL PICK UP IN SPEED TODAY AND BECOME GUSTY
ACROSS THE MID STATE AS SURFACE PRESSURE GRADIENT TIGHTENS. EXPECT
FROPA AT CLARKSVILLE AROUND 08Z TONIGHT AND AROUND 11Z AT
NASHVILLE WITH WIND SHIFTING TO THE WEST.
BOYD
PREV DISCUSSION... /ISSUED 329 AM CDT FRI SEP 21 2012/
DISCUSSION...
LATEST ANALYSIS SHOWING WEAK QUASI-STATIONARY FRONT DRAPED NORTH/
WEST OF THE MID-STATE...WITH UPPER TROUGH/WEAK IMPULSE MOVING OUT
OF THE PLAINS. STORMS FIRING SOUTH KS/MO IN VICINITY OF SFC BOUNDARY
AS WELL AS INCOMING LLJET.
THESE APPROACHING FEATURES WILL BE FLAVOR OF TODAY/TONIGHT/SAT
PLATEAU. UPPER TROUGH/LLJET WILL CONTINUE SLIDING EAST TODAY WHILE
WEAK FRONT HOLDS VERY CLOSE TO CURRENT LOCATION. BETTER MOISTURE/
INSTABILITY DOES WORK FURTHER NORTH ACROSS OH VALLEY WHILE MOISTURE
ON THE SOUTHERN FLANK OF REMAINS LIMITED. ULTIMATELY HOWEVER A FEW
SHOWERS/STORMS MAY MOVE IN/DEVELOP ACROSS THE EXTREME NORTH LATER
TODAY/TONIGHT AS UPPER TROUGH/IMPULSE/LLJET WORK INTO THE CWA 06-12Z
SAT. WEAK FRONT THEN PASSES 12-18Z OR SO WHICH COULD BRING A FEW
SHOWERS TO THE PLATEAU SAT ON THE BACK END.
ONCE THESE FEATURES MOVE EAST SAT NIGHT...PCPN CHANCES REALLY DIP
AGAIN PRESUMABLY INTO LATE NEXT WEEK. SFC/LL HIGH REMAINS STRONG
MOST OF THE WORKWEEK WHILE UPPER FLOW REALLY DAMPENS. A FEW WEAK
SHORTWAVES WILL PASS JUST NORTH BUT THE OH VALLEY LOOKS TO BE THE
TARGET OF SIGNIFICANT PCPN WITH PRESENCE OF DEEPER MOISTURE THERE.
AT THIS POINT WILL BRING SMALL CHANCE SHOWERS BACK INTO THE
NORTHEAST THU WITH NEXT WEAK FRONT BUT EXTENDED PERIOD WILL BE DRY
FOR THE MOST...WITH TEMPS GOING BACK ABOVE SEASON NORMALS AFTER
COOL SPELL SUN/MON.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
04
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
905 AM CDT FRI SEP 21 2012
.UPDATE...CONVECTION MOVING INTO WEST TN. LATEST IR SATELLITE
IMAGES SHOW CLOUD TOPS WARMING SIGNIFICANTLY. THIS IS USUALLY A
PRECURSOR TO DE-INTENSIFICATION. HRRR MESO MODEL ALSO INDICATES
THAT THIS AREA WILL WEAKEN WHILE SPREADING EWD AND NEWD. THUS IT
SEEMS OUR SLGT CHC POP FOR THE NRN AND NWRN COUNTIES WILL BE OK.
NO SIGNIFICANT CHANGES FOR NOW.
&&
.PREV DISCUSSION... /ISSUED 635 AM CDT FRI SEP 21 2012/
UPDATE...FOR 12Z AVIATION FORECAST
AVIATION...
COMPLEX OVER SOUTHEAST MISSOURI THIS MORNING ON THE NOSE OF A 45
KNOT SOUTHWESTERLY LOW LEVEL JET AND IS IN THE RIGHT REAR QUADRANT
OF A 65 KNOT WESTERLY MID-LEVEL JET. H-TRIPLE-R HAS THIS FEATURE
INITIALIZED WELL AND WORKS IT EASTWARD WHILE WEAKENING IT ACROSS
FAR WESTERN KENTUCKY AND WESTERN TENNESSEE THROUGH ABOUT 15Z THEN
DRAGS WHATS LEFT ACROSS NORTHERN MIDDLE TENNESSEE AND CONTINUES
TO WEAKEN AS IT APPROACHES NASHVILLE. WILL FORECAST VCSH FOR
CLARKSVILLE FROM ABOUT 15Z UNTIL 17Z AND FOR NASHVILLE FROM ABOUT
18Z UNTIL 20Z. WINDS WILL PICK UP IN SPEED TODAY AND BECOME GUSTY
ACROSS THE MID STATE AS SURFACE PRESSURE GRADIENT TIGHTENS. EXPECT
FROPA AT CLARKSVILLE AROUND 08Z TONIGHT AND AROUND 11Z AT
NASHVILLE WITH WIND SHIFTING TO THE WEST.
BOYD
PREV DISCUSSION... /ISSUED 329 AM CDT FRI SEP 21 2012/
DISCUSSION...
LATEST ANALYSIS SHOWING WEAK QUASI-STATIONARY FRONT DRAPED NORTH/
WEST OF THE MID-STATE...WITH UPPER TROUGH/WEAK IMPULSE MOVING OUT
OF THE PLAINS. STORMS FIRING SOUTH KS/MO IN VICINITY OF SFC BOUNDARY
AS WELL AS INCOMING LLJET.
THESE APPROACHING FEATURES WILL BE FLAVOR OF TODAY/TONIGHT/SAT
PLATEAU. UPPER TROUGH/LLJET WILL CONTINUE SLIDING EAST TODAY WHILE
WEAK FRONT HOLDS VERY CLOSE TO CURRENT LOCATION. BETTER MOISTURE/
INSTABILITY DOES WORK FURTHER NORTH ACROSS OH VALLEY WHILE MOISTURE
ON THE SOUTHERN FLANK OF REMAINS LIMITED. ULTIMATELY HOWEVER A FEW
SHOWERS/STORMS MAY MOVE IN/DEVELOP ACROSS THE EXTREME NORTH LATER
TODAY/TONIGHT AS UPPER TROUGH/IMPULSE/LLJET WORK INTO THE CWA 06-12Z
SAT. WEAK FRONT THEN PASSES 12-18Z OR SO WHICH COULD BRING A FEW
SHOWERS TO THE PLATEAU SAT ON THE BACK END.
ONCE THESE FEATURES MOVE EAST SAT NIGHT...PCPN CHANCES REALLY DIP
AGAIN PRESUMABLY INTO LATE NEXT WEEK. SFC/LL HIGH REMAINS STRONG
MOST OF THE WORKWEEK WHILE UPPER FLOW REALLY DAMPENS. A FEW WEAK
SHORTWAVES WILL PASS JUST NORTH BUT THE OH VALLEY LOOKS TO BE THE
TARGET OF SIGNIFICANT PCPN WITH PRESENCE OF DEEPER MOISTURE THERE.
AT THIS POINT WILL BRING SMALL CHANCE SHOWERS BACK INTO THE
NORTHEAST THU WITH NEXT WEAK FRONT BUT EXTENDED PERIOD WILL BE DRY
FOR THE MOST...WITH TEMPS GOING BACK ABOVE SEASON NORMALS AFTER
COOL SPELL SUN/MON.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
18
AREA FORECAST DISCUSSION
NWS AMARILLO TX
1127 PM CDT THU SEP 20 2012
.AVIATION...
A BOUNDARY DIVING SOUTHWARD HAS CAUSED SURFACE WINDS AT KGUY AND
KDHT TO SHIFT TO THE NORTH...AND WINDS SHOULD REMAIN THAT WAY
THROUGH 23 Z FRIDAY. THERE A CHANCE FOR A BRIEF SHIFT TO THE SOUTH
AT KDHT AS ANOTHER BOUNDARY MOVES NORTHWARD. HAVE KEPT PREVAILING
WINDS AT KDHT OUT OF THE NORTH AS THE BOUNDARIES SHOULD CONVERGE
SOUTH OF THE TERMINAL. THIS CONVERGING OF BOUNDARIES SHOULD ALSO SLOW
THE SOUTHERN PROGRESSION OF THE NORTHERN BOUNDARY. AS SUCH HAVE KEPT
SURFACE WINDS OUT OF THE SOUTH FOR KAMA UNTIL SUNRISE FRIDAY. WINDS
WILL SLOWLY ROTATE EASTWARD THROUGHOUT THE DAY THEN TAKE A MORE
SOUTHEAST DIRECTION TOWARDS THE END OF THE TAF PERIOD. VFR CONDITIONS
SHOULD PREVAIL AT ALL TERMINALS THROUGH THE TAF PERIOD.
&&
.PREV DISCUSSION... /ISSUED 832 PM CDT THU SEP 20 2012/
UPDATE...
MID LEVEL ATMOSPHERIC CAPPING INVERSION PREVAILED ACROSS THE PNHDLS
THIS AFTERNOON AND EVENING. THEREFORE...HAVE REMOVED LOW POPS FOR ERN
ZONES FOR THIS EVENING. UPDATED PRODUCTS OUT SHORTLY.
ANDRADE
PREV DISCUSSION... /ISSUED 602 PM CDT THU SEP 20 2012/
AVIATION...
NOT MUCH CHANGE FROM THE PREVIOUS TAF PACKAGE. VRF CONDITIONS
EXPECTED TO PREVAIL THROUGHOUT THE TAF. A COLD FRONT CONTINUES TO
APPROACH THE TAF SITES AND SHOULD FIRST IMPACT KGUY AROUND 4 Z.
SURFACE WINDS WILL SHIFT AROUND TO THE N/NW AND COULD CAUSE BRIEF
WIND GUSTS UP TO 20 KTS IMMEDIATELY BEHIND THE FRONT. KDHT SHOULD
FOLLOW SUIT NOT LONG AFTER KGUY. KAMA SHOULD SEE THE WINDS SHIFT
DURING THE LATE MORNING HOURS ON FRIDAY. ISOLATED THUNDERSTORMS
REMAIN A SLIGHT POSSIBILITY THIS EVENING HOWEVER CONFIDENCE IS ON THE
SIDE OF NO IMPACTS TO THE TERMINALS.
PREV DISCUSSION... /ISSUED 344 PM CDT THU SEP 20 2012/
DISCUSSION...
A STRONG UPPER LOW OVER HUDSON BAY ALONG WITH AN AMPLIFIED RIDGE
ACROSS THE WESTERN CONUS IS MAINTAINING NORTHWEST FLOW ALOFT ACROSS
THE PANHANDLES. A SUBTLE SHORTWAVE TROUGH WILL MOVE OUT OF THE
ROCKIES AND ACROSS THE TEXAS PANHANDLE TONIGHT. A DRY AIR MASS
REMAINS ACROSS THE AREA WITH DEWPOINTS ONLY IN THE UPPER 30S TO THE
MID 40S. HOWEVER DESPITE THIS LACK OF SUBSTANTIAL MOISTURE...HAVE
LEFT IN MENTION OF ISOLATED THUNDERSTORMS IN THE EASTERN TEXAS
PANHANDLE WHERE LIFT FROM THIS SHORTWAVE CAN INTERACT WITH SLIGHTLY
HIGHER MOISTURE VALUES. SPC RUC MESOSCALE ANALYSIS SHOWS SOME
INSTABILITY IN THIS AREA WITH SBCAPES AROUND 1500 J/KG. HOWEVER A
FAIRLY STRONG CAP ALSO EXISTS IN THIS AREA SO THUNDER DEVELOPMENT
LOOKS PRETTY SLIM. LOWS TONIGHT WILL BE SLIGHTLY WARMER WITH LOWS
RANGING FROM THE UPPER 40S IN THE WESTERN OKLAHOMA PANHANDLE TO
NEAR 60 DEGREES IN THE SOUTHEAST TEXAS PANHANDLE.
A COLD FRONT WILL PUSH SOUTH ACROSS THE PANHANDLES FRIDAY. CAN SEE A
PERIOD OF GUSTY WINDS INITIALLY BEHIND THE FRONT ALTHOUGH WINDS
WILL DIMINISH DURING THE DAY AS SURFACE HIGH PRESSURE BUILDS ACROSS
THE CENTRAL PLAINS. GIVEN THE NORTHERLY FETCH...HAVE LEANED TOWARD
THE COOLER MAV GUIDANCE WITH HIGH TEMPS IN THE 80S TO THE LOWER 90S
IN THE FAR SOUTHEAST TEXAS PANHANDLE.
THE WESTERN CONUS UPPER RIDGE WILL SLIDE TO THE EAST OVER THE
WEEKEND WHERE IT WILL FLATTEN EARLY NEXT WEEK IN RESPONSE TO AN
UPPER LOW MOVING ACROSS THE GREAT BASIN. ALTHOUGH THE FIRST DAY OF
FALL IS SATURDAY...TEMPERATURES WILL BE MORE SUMMER-LIKE OVER THE
WEEKEND AND EARLY NEXT WEEK DUE TO SOUTHERLY WINDS AND RISING
HEIGHTS. MEDIUM RANGE MODELS ARE COMING INTO BETTER AGREEMENT WITH
THE UPPER LOW AS IT MOVES ACROSS THE CENTRAL PLAINS MID WEEK. THE
FLOW ALOFT WILL TRANSITION TO THE SOUTHWEST ALLOWING FOR THE
TRANSPORT OF MOISTURE ACROSS THE AREA. THIS LOW CAN TAP INTO THIS
MOISTURE AND BRING THE NEXT CHANCE OF RAIN TO THE AREA BY AROUND
THURSDAY. HOWEVER SINCE THIS IS STILL QUITE AWAYS OFF INTO THE
FUTURE HAVE OPTED TO KEEP THE INHERITED DRY FORECAST INTACT.
CLK
FIRE WEATHER...
AFTERNOON RELATIVE HUMIDITY VALUES CAN DROP TO AROUND 20 PERCENT
ACROSS THE OKLAHOMA PANHANDLE AND THE NORTHERN TEXAS PANHANDLE
FRIDAY. HOWEVER 20 FOOT WINDS ARE EXPECTED TO STAY BELOW 15
MPH...PRECLUDING ELEVATED AND CRITICAL FIRE WEATHER CONDITIONS. A
WIND SHIFT TO THE NORTH WILL OCCUR FRIDAY AS A COLD FRONT
DROPS SOUTH ACROSS THE AREA. GUSTY WINDS CAN ALSO DEVELOP
BEHIND THIS FRONT BUT WILL DIMINISH LATER IN THE DAY. SLIGHTLY COOLER
AIR BEHIND THIS FRONT WILL SPREAD ACROSS THE AREA SATURDAY WHICH WILL
LEAD TO MINIMUM RELATIVE HUMIDITIES TO STAY ABOVE 20 PERCENT.
UNSEASONABLY WARM TEMPERATURES WILL RESULT IN RELATIVE HUMIDITY
VALUES TO FALL TO AROUND 15 TO 20 PERCENT IN THE WESTERN OKLAHOMA
PANHANDLE AND THE NORTHWEST TEXAS PANHANDLE SUNDAY AND MONDAY.
HOWEVER 20 FOOT WINDS ARE EXPECTED TO BE BELOW 15 MPH...PRECLUDING
ELEVATED AND CRITICAL FIRE WEATHER CONDITIONS. RELATIVE HUMIDITIES
SHOULD STAY NEAR OR ABOVE 20 PERCENT AFTER MONDAY AND WHILE 20 FOOT
WINDS FOR THE MOST PART WILL STAY BELOW 15 MPH...THEY CAN INCREASE TO
AROUND 15 TO 20 PERCENT AT TIMES. HOWEVER THE STRONGER WINDS ARE
EXPECTED TO OCCUR WHERE RELATIVE HUMIDITY VALUES WILL BE ABOVE
CRITICAL THRESHOLDS. THE CHANCE FOR WETTING RAINS IS SLIM THROUGH THE
NEXT SEVEN DAYS.
CLK
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
OK...NONE.
&&
$$
14/02
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
256 PM CDT FRI SEP 21 2012
.SHORT TERM...TONIGHT THROUGH MONDAY
256 PM CDT FRI SEP 21 2012
FORECAST CONCERNS INCLUDE RAIN TONIGHT INTO SATURDAY/POSSIBLE RAIN
AND SNOW MIX...THEN INCREASING CONFIDENCE FOR A WIDESPREAD FREEZE
SATURDAY NIGHT.
THIS AFTERNOON/S WATER VAPOR IMAGERY FEATURES A DEEP LONGWAVE TROUGH
ENTRENCHED ACROSS EASTERN CANADA/CENTRAL CONUS. EMBEDDED WITHIN THIS
LARGE TROUGH WAS A FAIRLY WEAK SHORTWAVE TROUGH ZIPPING EAST ACROSS
SOUTHERN WI. IMPRESSIVE 700MB CONVERGENCE PER THE RAP ENOUGH TO
SQUEEZE OUT FAIRLY STEADY LIGHT-MODERATE RAIN AREA ACROSS SOUTHERN
WI/NORTHERN IL. COOL CYCLONIC FLOW ALOFT/STEEP LAPSE RATES ALSO
PRODUCING SCATTERED SHOWERS ACROSS NORTHERN/CENTRAL WI. A STRONGER
SHORTWAVE TROUGH WAS LOCATED OVER SOUTHEASTERN MANITOBA DROPPING
SOUTHWARD TOWARD OUR AREA. THIS WAVE WILL BE OUR WEATHER-MAKER
TONIGHT INTO SATURDAY. OTHERWISE...AFTERNOON TEMPERATURES WERE
SOME 10 DEGREES BELOW SEASONAL NORMALS WITH READINGS AT 2 PM IN THE
MIDDLE 50S TO LOWER 60S.
21.12Z NCEP MODEL SUITE ALONG WITH THE 21.09Z SREF ALL IN GREAT
AGREEMENT THROUGH THE SHORT TERM...LENDING TO FAIRLY HIGH FORECAST
CONFIDENCE.
FOR TONIGHT...THE AFOREMENTIONED MID-LEVEL SHORTWAVE OVER
SOUTHEASTERN MANITOBA WILL SWING SOUTH INTO THE AREA. NAM INDICATING
STRONG/DEEP PV-ADVECTION IN THE 850-300MB LAYER ALONG WITH
IMPRESSIVE QG RESPONSE...ESPECIALLY IN THE 700-500MB LAYER. GIVEN
STRONG/CONSISTENT SIGNAL...GOING WITH DEFINITE RAINSHOWERS ALONG
AND NORTHEAST OF THE MISSISSIPPI RIVER MAINLY AFTER MIDNIGHT. LOOKING AT
THE NAM PLAN VIEW/BUFKIT DATA SHOWS WETBULB ZERO HEIGHTS GETTING
PRETTY LOW WHERE RAINSHOWERS WILL BE OCCURRING....HOVERING AROUND
2000 FEET AGL IN SOME CASES. THIS BEING THE CASE...WILL CONTINUE THE
POSSIBILITY OF SOME SNOW MIXING IN AT TIMES FOR AREAS MAINLY ALONG
AND NORTHEAST OF I-94. HOWEVER...WITH SUCH WARM GROUND YET...NO
ACCUMULATION IS EXPECTED.
LOOKS LIKE SOME LINGERING DEFORMATION AREA SHOWERS FOR SATURDAY
MORNING ACROSS SOUTHERN WI AS THE WAVE MOVES OFF TO THE EAST.
OTHERWISE...SUBSIDENCE BUILDS IN FOR THE REST OF THE DAY ALONG WITH
INCREASING PRESSURE GRADIENT BETWEEN DEPARTING WAVE AND HIGH
PRESSURE BUILDING IN FROM THE DAKOTAS. INCREASED WIND SPEEDS A BIT
TO ACCOUNT FOR THIS. PLAN ON BREEZY NORTHWEST WINDS IN THE 15 TO 25
MPH RANGE WITH HIGHS ONLY IN THE 50S. WILL DEFINITELY FEEL LIKE AN
AUTUMN DAY TO USHER THE FIRST DAY OF AUTUMN...WHICH STARTS AT 949 AM
CDT.
ALL ATTENTION THEN TURNS TO HOW COLD WILL IT GET SATURDAY NIGHT AND
THE POTENTIAL FOR A WIDESPREAD FREEZE. HIGH PRESSURE CONTINUES TO
MOVE TOWARD THE REGION FROM THE DAKOTAS...SPILLING CHILLY AIR INTO
THE REGION. NAM DEPICTING 850MB LAYER TEMPERATURES LOWERING INTO THE
ZERO TO -4C RANGE ACROSS THE AREA BY 12Z SUNDAY UNDER CLEAR SKIES.
THIS WOULD NORMALLY LEAD TO WIDESPREAD FREEZING TEMPERATURES AT THE
SURFACE. ONE CONCERN HOWEVER WILL BE WIND AND AMOUNT OF DECOUPLING
WITH THE RIDGE AXIS REMAINING WEST OF THE AREA ALL NIGHT. BOTH GFS AND
NAM SHOW PRESSURE GRADIENT SLACKENING GOING INTO SATURDAY EVENING.
GIVEN THIS...COULD SEE WINDS STAYING UP AROUND 5 MPH OR SO...LEADING
TO SOME STIRRING/MIXING OF THE LOWER BOUNDARY LAYER WHICH WOULD IN
TURN PREVENT TEMPERATURES FROM DROPPING MUCH BELOW THE FREEZING
MARK. HOWEVER...IF WE DO DECOUPLE AND GO CALM...TEMPERATURES COULD
REALLY TAKE A TUMBLE FOR A WIDESPREAD HARD FREEZE. WITH THIS IN
MIND...WILL GO AHEAD AN POST A FREEZE WATCH VALID FROM 1 AM THROUGH
8 AM SATURDAY.
REST OF SUNDAY INTO MONDAY LOOKS QUIET WITH A WARMING TREND AS THE
DEEP TROUGH THAT WAS ENTRENCHED ACROSS THE AREA STARTS TO FILL A BIT
AND LIFT NORTHEAST. LOOKS LIKE HIGHS WILL BE IN THE 50S TO LOWER 60S ON
SUNDAY...WARMING INTO THE 60S TO A FEW LOWER 70S ON MONDAY.
.LONG TERM...MONDAY NIGHT THROUGH FRIDAY
256 PM CDT FRI SEP 21 2012
LATEST GFS AND ECMWF IN GENERALLY GOOD AGREEMENT THROUGH WEDNESDAY.
BOTH MODELS SHOW A WEAK COLD FRONT DROPPING SOUTH ACROSS THE AREA
MONDAY/MONDAY NIGHT WITH MORE OR LESS JUST A WINDSHIFT EXPECTED.
PLAN ON HIGHS MONDAY AND TUESDAY IN THE MID 60S TO A FEW LOWER 70S.
A SLIGHTLY COOLER AIRMASS SEEPS INTO THE AREA ON WEDNESDAY WITH
HIGHS IN THE 60S. FOR THURSDAY INTO FRIDAY...THE 21.12Z GFS SHOWS A
WEAK MID-LEVEL TROUGH ROTATING ACROSS THE CENTRAL CONUS WITH ANY PCPN
STAYING SOUTH OF OUR AREA. THE ECMWF SHOWS MORE VIGOROUS TROUGHING
INTO THE AREA AND THUS PRODUCES SOME PCPN FOR THE AREA THURSDAY
NIGHT INTO FRIDAY. WILL STICK WITH A DRY FORECAST FOR NOW AND GO
WITH MODEL CONSENSUS TEMPERATURES...WHICH YIELDS HIGHS THURSDAY AND FRIDAY
IN THE 60S.
&&
.AVIATION...THROUGH 18Z SATURDAY
1205 PM CDT FRI SEP 21 2012
VFR CONDITIONS EXPECTED FOR THE AFTERNOON INTO THE EVENING.
CONDITIONS THEN SHOULD DETERIORATE QUICKLY AS A STRONG SHORT WAVE
TROUGH OVER CANADA APPROACHES THE AREA. THIS WAVE WILL MOVE
QUICKLY ACROSS THE REGION TONIGHT AND PRODUCE STRONG FORCING WITH
UP TO 40 PVU/S OF VORTICITY ADVECTION IN THE 500-300 MB
LAYER...STRONG QG CONVERGENCE IN THE 850-300 MB LAYER AND AROUND
10 UBAR/S OF UP GLIDE ON THE 300K ISENTROPIC SURFACE. THIS FORCING
WILL PRODUCE AN AREA OF RAIN FOR BOTH TAF SITES OVERNIGHT. WILL
KEEP KRST VFR FOR THE MOST PART WITH THE POSSIBILITY OF SOME MVFR
CEILINGS. KLSE HAS A BETTER CHANCE OF SEEING BOTH MVFR VISIBILITY
AND CEILINGS. UP STREAM OBSERVATIONS OVER WESTERN ONTARIO ALREADY
INDICATE MVFR CEILINGS WITH THE PRECIPITATION AREA AND THE 21.13Z
HRRR SUGGEST VISIBILITIES AROUND 5 MILES IN THE HEAVIEST
PRECIPITATION. WINDS WILL ALSO BE AN ISSUE WITH THIS SYSTEM.
DESPITE THE CLOUDS...AS THE COLDER AIR MOVES IN QUICKLY IT WILL
SET UP STEEP LOW LEVEL LAPSE RATES AND EXPECT GUSTS TO BE PRODUCED
AT BOTH SITES DURING THE OVERNIGHT AND THROUGH ALL OF SATURDAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
256 PM CDT FRI SEP 21 2012
WI...FREEZE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY MORNING FOR
WIZ017-029-032>034-041>044-053>055-061.
MN...FREEZE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY MORNING FOR
MNZ079-086>088-094>096.
IA...FREEZE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY MORNING FOR
IAZ008>011-018-019-029-030.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION...04
AREA FORECAST DISCUSSION
NWS MIAMI FL
153 AM EDT SUN SEP 23 2012
.AVIATION...
WET PATTERN TO CONTINUE ACROSS SOUTH FLORIDA THROUGH THE NEXT 24
HOURS. COLD FRONT WILL PUSH FURTHER SOUTH ACROSS THE FLORIDA
PENINSULA THROUGH THE DAY. THIS COMBINED WITH PASSING UPPER LEVEL
DISTURBANCES WILL ENHANCE SHRA/TSRA DEVELOPMENT AGAIN TODAY. KEPT
VCSH THROUGH THE MORNING HOURS TRANSITIONING TO VCTS THROUGH THE
AFTERNOON. BRIEF PERIODS OF MVFR/IFR CAN BE EXPECTED WITHIN ANY
TSRAS AND HEAVY SHRAS.
&&
.PREV DISCUSSION... /ISSUED 928 PM EDT SAT SEP 22 2012/
UPDATE...
ALL THE URBAN FLOOD ADVISORIES ISSUED EARLIER IN THE EVENING HAVE
BEEN DROPPED.. LATEST RADAR RETURNS INDICATE JUST LIGHT TO
MODERATE SHOWERS ACROSS THE CWA.
THE SHORT TERM FORECAST WAS UPDATED TO REFLECT THE LACK OF
CONVECTION CURRENTLY ACROSS THE REGION. HOWEVER...LATEST GUIDANCE
AND WATER VAPOR IMAGERY INDICATED AN UPPER LEVEL SHORT WAVE TROUGH
ENTERING THE EASTERN GULF THAT COULD TRIGGER ANOTHER ROUND OF
CONVECTION DURING THE EARLY MORNING HOURS ON SUNDAY. THE OOZ SOUNDING
INDICATED CONSIDERABLE MOISTURE LINGERING ACROSS THE AREA WITH THE
PWAT NEAR 2.4 INCHES WITH WESTERLY FLOW THROUGH MOST OF THE
ATMOSPHERE. THE RECENT GUIDANCE ALSO INDICATED THE POTENTIAL FOR
ADDITIONAL CONVECTION OVER NIGHT. SO FOR THE REMAINING EVENING
HOURS JUST ISOLATED TO SCATTERED SHOWERS AND AN OCCASIONAL
THUNDERSTORM IS FORECAST WITH GREATER COVERAGE AND AN INCREASE IN
POTENTIAL FOR SHOWERS AND THUNDERSTORMS EXPECTED DURING THE EARLY
MORNING HOURS ON SUNDAY.
60
PREV DISCUSSION... /ISSUED 234 PM EDT SAT SEP 22 2012/
SHORT TERM (TONIGHT-MONDAY NIGHT)... AFTER A BUSY START TO THE
DAY THIS MORNING DUE TO FLOODING ALONG THE EAST COAST FROM MIAMI-
DADE TO PALM BEACH...THE LATEST HRRR MODEL REFLECTIVITIES HAVE
INITIALIZED WELL WITH THE CURRENT PATTERN AND CONTINUE TO INDICATE
ANOTHER ROUND OF ACTIVITY REDEVELOPING THROUGH THE MID TO LATE
AFTERNOON AND EVENING PERIODS. FOR COVERAGE...IT IS INDICATING THE
BULK OF THE HEAVIEST ACTIVITY SETTING UP OVER THE SOUTHERN HALF OF
THE LOCAL AREA WITH ANOTHER 1-2 INCHES OF RAINFALL POSSIBLE IN THE
HEAVIEST ACTIVITY. THIS SEEMS REASONABLE AS THE LATEST VISIBLE
SATELLITE IMAGERY SHOWS THE LARGEST BREAKS IN CLOUD COVERAGE OVER
THESE SOUTHERN AREAS WHERE TEMPERATURES HAVE QUICKLY INCREASED
OVER THE PAST 1-2 HRS. AS A RESULT...FLOODING REMAINS THE MAIN
CONCERN INTO THE EVENING HOURS. IF THIS ACTIVITY SETS UP OVER THE
SAME AREAS AS THIS MORNING WHERE 2-4 INCHES WERE RECORDED...MAINLY
FROM AROUND JUST SE OF CUTLER BAY TO NORTH MIAMI BEACH...FLASH
FLOODING CANNOT BE RULED OUT.
TONIGHT THROUGH SUNDAY NIGHT...THE COLD FRONT ENTERING THE REGION
FROM THE NORTH IS PROGGED TO CONTINUE SOUTH INTO NORTHERN AND
CENTRAL FLORIDA THROUGH THE FIRST HALF OF THE DAY SUNDAY FOLLOWED BY
A SURGE OF MUCH DRIER AIR BEFORE STALLING. UNFORTUNATELY...THE DEEP
LAY MOISTURE AXIS WITH AROUND 2" PWAT VALUES EXTENDING FROM NE TO SW
ACROSS THE AREA WILL REMAIN IN PLACE THROUGH SUNDAY WITH ONLY SOME
DRYING POSSIBLE ACROSS THE NORTHERN HALF OR THE LAKE REGION BY
TOMORROW NIGHT. THIS COMBINED WITH WEAK UPPER PULSES OF ENERGY
TRANSLATING NORTHEAST AHEAD OF THE BROAD UPPER TROUGH JUST WEST OF
THE AREA WILL KEEP THE RAIN AND FLOOD CHANCES AS THE PRIMARY
CONCERNS THROUGH SUNDAY. ADDITIONAL RAINFALL ACCUMULATIONS COULD
REACH THE 1 TO 3 INCH RANGE WITH LOCALIZED HIGHER AMOUNTS
POSSIBLE.
MONDAY AND MONDAY NIGHT...THE LATEST NUMERICAL GUIDANCE REMAINS IN
DECENT AGREEMENT AND INDICATES THE BROAD UPPER TROUGH OVER THE
EASTERN STATES SHIFTING EAST AND THE MUCH DRIER AIR THAT WAS
PREVIOUSLY DISCUSSED SHIFTING FARTHER SOUTH INTO OUR AREA IN THE
WAKE OF THE FRONTAL BOUNDARY. AS A RESULT...DRY AIR WITH LOWER
RAINFALL CHANCES CAN BE ANTICIPATED.
LONG TERM...(TUESDAY-FRIDAY)
THE UPPER RIDGE OVER THE ROCKIES BEGINS TO BREAK DOWN AS AN UPPER
LOW MOVES FROM THE PACIFIC NORTHWEST TOWARD THE CENTRAL ROCKIES.
THIS SHOVES THE E U.S. TROUGH NE WITH THE COLD FRONT STALLED N OF
LAKE OKEECHOBEE. THIS DRIES THE ATMOSPHERE SOMEWHAT FROM THE N TO
S ACROSS FLA BUT LONG RANGE MODELS STILL APPEAR TO DEVELOP AN
UPPER LOW OVER THE GULF AND WITH THE SW FLOW MAY KEEP AMPLE
ATMOSPHERIC MOISTURE OVER THE AREA. PLUS...ANOTHER TROPICAL WAVE
MAY NEAR THE AREA MIDWEEK NEXT WEEK. AT HIS TIME...WILL STAY WITH
GUIDANCE.
MARINE...
RAIN CHANCES WILL REMAIN UP ACROSS THE MARINE AREAS THROUGH SUNDAY
BEFORE DRIER AIR ASSOCIATED WITH A COLD FRONT SPREADS SOUTH ACROSS
THE AREA MONDAY. MODERATE NORTHEAST WINDS WILL FOLLOW THIS BOUNDARY
AND LEAD TO INCREASING SEAS MONDAY THROUGH TUESDAY OVER THE ATLANTIC
WATERS.
FIRE WEATHER...
ALTHOUGH SOME DRIER AIR IS FORECAST TO SPREAD SOUTH INTO THE AREA
THROUGH THE FIRST HALF OF THE UPCOMING WEEK...RELATIVE HUMIDITIES
ARE FORECAST TO REMAIN ABOVE CRITICAL LEVELS EACH DAY. AS A
RESULT...THERE ARE NO RED FLAG CONCERNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 81 77 86 77 / 60 50 20 20
FORT LAUDERDALE 86 75 86 77 / 70 50 30 30
MIAMI 88 75 88 77 / 70 60 30 30
NAPLES 87 74 89 74 / 40 40 20 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...15/JR
AVIATION/RADAR...10/CD
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
136 AM CDT SUN SEP 23 2012
...UPDATED SYNOPSIS...
.SYNOPSIS...
ISSUED AT 135 AM CDT SUN SEP 23 2012
A DEEP UPPER LEVEL CYCLONE WAS CENTERED SOUTH OF JAMES BAY, AND AN
UPPER LEVEL RIDGE EXTENDED FROM AN ANTICYCLONE IN SOUTHEAST NEW
MEXICO TO THE NORTHWEST TERRITORIES. A COMPACT UPPER LEVEL LOW
PRESSURE SYSTEM WAS DIGGING INTO WESTERN WASHINGTON BENEATH THE
CANADIAN RIDGE. A WEAK SUBTROPICAL JET WAS EVIDENT ON SATELLITE
IMAGERY FROM THE DEEP TROPICS TO SOUTHERN CALIFORNIA, AND
ABUNDANT HIGH LEVEL TROPICAL MOISTURE WAS FLOWING FROM THE SOUTH
PACIFIC AROUND A WEAK UPPER LEVEL TROUGH NEAR 32N/122W INTO THE
SOUTHWESTERN UNITED STATES. AT THE SURFACE, A LARGE CANADIAN HIGH
PRESSURE SYSTEM CENTERED IN THE EASTERN DAKOTAS COVERED MUCH OF THE
EASTERN UNITED STATES. TEMPERATURES AT 06Z IN THE COLD AIR WERE NEAR
OR BELOW FREEZING IN THE EASTERN DAKOTAS, NORTHERN IOWA AND
MINNESOTA. A STATIONARY FRONT EXTENDED FROM EASTERN COLORADO ACROSS
THE TEXAS PANHANDLE TO NORTH TEXAS. VERY WARM AIR WAS EVIDENT SOUTH
OF THE STATIONARY FRONT WITH H8 TEMPERATURES IN THE MID 20SC IN WEST
TEXAS AND THE TEXAS PANHANDLE. EAST TO SOUTHEAST LOW LEVEL FLOW
PREVAILED NORTH OF THE FRONT ACROSS WESTERN KANSAS.
A MID LEVEL DEFORMATION ZONE BETWEEN THE FLOW AROUND THE DEEP
CYCLONE IN ONTARIO AND INCREASING WESTERLY FLOW ACROSS THE ROCKIES
WAS RESULTING IN FRONTOGENESIS IN A BAND FROM EASTERN COLORADO
ACROSS SOUTHWEST KANSAS INTO NORTHWEST OKLAHOMA. WEAK MID LEVEL
INSTABILITY (CAPE VALUES AS MUCH AS 300 JOULES/KG) WAS BEING TAPPED
BY THE UPWARD VERTICAL MOTION IN THE FRONTOGENETIC REGION TO SUPPORT
DEVELOPMENT OF SHOWERS AND A FEW THUNDERSTORMS.
&&
.UPDATE...
ISSUED AT 930 PM CDT SAT SEP 22 2012
THE FORECAST WAS UPDATED TO INCLUDE A SLIGHT CHANCE OF SHOWERS
WITH AN ISOLATED THUNDERSTORM MAINLY 06Z-15Z...TIED TO A NORTHWEST
TO SOUTHEAST AXIS OF LOWER-MID LEVEL FRONTOGENESIS (PARTICULARLY
800-700MB LAYER). LATEST NAM12 MODEL SOLUTION SUGGESTS 150-300
J/KG OF MUCAPE WITHIN THE ZONE OF STRONGEST WARM FRONTOGENESIS A
750MB...FROM TRIBUNE TO GARDEN CITY TO ASHLAND...SO A FEW
LIGHTNING STRIKES WILL ALSO BE POSSIBLE. THE 3KM HRRR HAS SHOWN A
RUN-TO-RUN CONSISTENCY IN GENERATING SHOWERS ALONG THIS
FRONTOGENETIC ZONE. SHOWERS WILL SHIFT TO THE EAST BY DAYBREAK
INTO SOUTH CENTRAL KS/NORTH CENTRAL OK WITH POPS DIMINISHING IN
THE GRIDS BY MID-MORNING SUNDAY.
&&
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 248 PM CDT SAT SEP 22 2012
THE MAIN FORECAST CHALLENGES ARE INCREASING CLOUDS TONIGHT AND A FEW
SPRINKLES, THEN HIGH TEMPERATURES ON SUNDAY AHEAD OF A WARM FRONT.
MODELS IN AGREEMENT WITH MOVING A COLD UPPER LEVEL TROUGH SLOWLY
EASTWARD ACROSS THE UPPER MIDWEST INTO SUNDAY WITH NORTHWEST FLOW
ALOFT CONTINUING OVER THE CENTRAL PLAINS. AS THE UPPER TROUGH
MOVES EAST, A RIDGE OF COOLER SURFACE HIGH PRESSURE WILL SLOWLY
PROGRESS EASTWARD FROM THE MISSOURI VALLEY INTO THE MID
MISSISSIPPI VALLEY ALLOWING A WARM FRONT TO PUSH NORTH INTO
EASTERN COLORADO TO JUST SOUTH OF ELKHART AND INTO CENTRAL
OKLAHOMA ON SUNDAY AFTERNOON. MID AND UPPER LEVEL MOISTURE AND
CLOUDINESS IS ALSO FORECAST TO INCREASE AROUND AND AFTER MIDNIGHT
ACROSS WESTERN KANSAS AS WEAK 800-700MB FRONTOGENESIS AND
ISENTROPIC LIFT EVOLVE ALOFT AHEAD OF THE SURFACE WARM FRONT. DEEP
MOISTURE AND CAPE ARE LACKING FOR ELEVATED THUNDERSTORMS, HOWEVER
COULD BE ENOUGH LIFT FOR SOME LIGHT SHOWERS OR SPRINKLES MAINLY IN
THE FORM OF VIRGA. WILL KEEP A SILENT POP GOING AFTER MIDNIGHT
TONIGHT WITH INCREASING CLOUDINESS.
FOR TONIGHT LOOK FOR INCREASING CLOUDINESS WITH SOUTHEAST WINDS
DECREASING TO 10 TO 15 MPH. OVERNIGHT LOWS WILL RANGE FROM THE LOWER
40S FROM DIGHTON TO SAINT JOHN AND NORTH TO THE MID AND UPPER 40S
ELSEWHERE. THESE TEMPS ARE A FEW DEGREES WARMER THAN CURRENT
GUIDANCE DUE TO CLOUDINESS EXPECTED. THEN FOR SUNDAY, MODELS
CONTINUE TO SHOW INCREASING UPPER LEVEL MOISTURE IN THE FORM OF
CIRRUS CLOUDS. HIGH TEMPERATURES WERE LOWERED A FEW DEGREES FROM
PREVIOUS FORECAST WITH EXPECTED HIGH LEVEL CLOUDINESS AND
SOUTHEASTERLY UPSLOPE FLOW AHEAD OF THE WARM FRONT. WINDS LOOK TO
INCREASE TO 15 TO 25 MPH BY LATE MORNING INTO THE AFTERNOON WITH
HIGHS FROM THE MID 70S NORTH OF A GARDEN CITY TO DODGE CITY TO
MEDICINE LODGE LINE AND WARMER LOW TO MID 80S SOUTH.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 329 PM CDT SAT SEP 22 2012
FORECAST CHALLENGES LIE AHEAD THROUGH THE MIDDLE OF THE WEEK WITH
REGARD TO PRECIPITATION AND CONVECTIVE CHANCES AND TO A LESSER
EXTENT TEMPERATURES.
WARMER OVERNIGHT LOWS WILL BE EXPECTED ON SUNDAY NIGHT AS A BETTER
AS WARMER BOUNDARY LAYER AIR ADVECTS INTO SW KANSAS AHEAD OF THE
EASTERN COLORADO TROUGH AND PANHANDLES SURFACE LOW. MONDAY SHOULD
REMAIN DRY AND WARMING ACROSS THE SOUTHERN HALF OF WESTERN KANSAS.
SOUTH CENTRAL KANSAS COULD BE THE WARMEST INTO TUESDAY, AS A SURFACE
LOW REMAINS QUASI-STATIONARY OR SLOWLY EAST DURING THE TIMEFRAME.
ALTHOUGH THE ATMOSPHERE WOULD BE CONDITIONALLY UNSTABLE, THE LOW`
CONVERGENCE REGIONS IN AND OF ITSELF MIGHT NOT BE ENOUGH TO SET OFF
SHOWERS AND THUNDERSTORMS. A BETTER CATALYST APPEARS IN THE MODELS
IN THE FORM OF SHORTWAVES BEGINNING AS EARLY AS TUESDAY OR TUESDAY
EVENING. WEAK LOW AMPLITUDE TROUGHING WILL REMAIN IN PLACE OVER THE
WESTERN STATES AND INTO THE CENTRAL ROCKIES DURING THIS PERIOD WHICH
WILL ALLOW OPPORTUNITIES FOR MULTIPLE SHORTWAVE IMPULSES TO INFLUENCE
WESTERN AND CENTRAL KANSAS. BY THE MIDDLE OF THE WEEKEND, NEGATIVE
VORTICITY ADVECTION AND INCREASED SUBSIDENCE SHOULD BEGIN TO
MAKE AN IMPACT AND ELIMINATE CHANCES FOR SHOWERS OR STORMS.
TEMPERATURES WILL REMAIN SEASONAL THROUGH THE PERIOD, GENERALLY IN
THE LOW 80S TO UPPER 70S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1258 AM CDT SUN SEP 23 2012
A LARGE CANADIAN HIGH PRESSURE SYSTEM WILL CONTINUE TO BUILD
SOUTHWARD FROM THE EASTERN DAKOTAS TO KENTUCKY BY MONDAY MORNING. A
TROUGH OF LOW PRESSURE WILL DEEPEN IN THE LEE OF THE ROCKIES TODAY.
A STATIONARY FRONT EXTENDING FROM SOUTHEAST COLORADO ACROSS THE
TEXAS PANHANDLE TO EXTREME NORTHERN TEXAS WILL BEGIN TO MOVE NORTH
AS A WARM FRONT TONIGHT AND WILL EXTEND FROM FROM NEAR ELKHART TO
EAST CENTRAL OKLAHOMA BY MONDAY MORNING.
MID LEVEL FRONTOGENESIS WILL SUPPORT CONTINUED DEVELOPMENT OF
SCATTERED SHOWERS IN SOUTHWEST KANSAS EARLY THIS MORNING. SHOWERS
WILL BE IN THE VICINITY OF GCK AND DDC FROM 07Z THROUGH 12Z BUT WILL
WEAKEN AND MOVE OFF TO THE SOUTHEAST AFTER 12Z. THE SHOWERS WILL BE
LIGHT AND WILL NOT RESULT IN SIGNIFICANT VISIBILITY RESTRICTIONS.
BROKEN CLOUDS WITH BASES AOA 100 WILL PREVAIL EARLY THIS MORNING
IMPROVING TO ONLY A FEW CLOUDS AOA 150 BY LATE MORNING. SOUTHEAST
WINDS 10 TO 15 KNOTS WILL PREVAIL THROUGH THE DAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 76 53 83 62 / 10 0 0 0
GCK 76 52 83 58 / 10 0 0 10
EHA 85 59 89 60 / 10 0 0 10
LBL 84 56 89 62 / 10 0 0 10
HYS 74 52 76 55 / 10 0 0 10
P28 76 56 92 66 / 20 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...UMSCHEID
SYNOPSIS...RUTHI
SHORT TERM...KRUSE
LONG TERM...RUSSELL
AVIATION...RUTHI
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
100 AM CDT SUN SEP 23 2012
...UPDATED AVIATION SECTION...
.UPDATE...
ISSUED AT 930 PM CDT SAT SEP 22 2012
THE FORECAST WAS UPDATED TO INCLUDE A SLIGHT CHANCE OF SHOWERS
WITH AN ISOLATED THUNDERSTORM MAINLY 06Z-15Z...TIED TO A NORTHWEST
TO SOUTHEAST AXIS OF LOWER-MID LEVEL FRONTOGENESIS (PARTICULARLY
800-700MB LAYER). LATEST NAM12 MODEL SOLUTION SUGGESTS 150-300
J/KG OF MUCAPE WITHIN THE ZONE OF STRONGEST WARM FRONTOGENESIS A
750MB...FROM TRIBUNE TO GARDEN CITY TO ASHLAND...SO A FEW
LIGHTNING STRIKES WILL ALSO BE POSSIBLE. THE 3KM HRRR HAS SHOWN A
RUN-TO-RUN CONSISTENCY IN GENERATING SHOWERS ALONG THIS
FRONTOGENETIC ZONE. SHOWERS WILL SHIFT TO THE EAST BY DAYBREAK
INTO SOUTH CENTRAL KS/NORTH CENTRAL OK WITH POPS DIMINISHING IN
THE GRIDS BY MID-MORNING SUNDAY.
&&
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 248 PM CDT SAT SEP 22 2012
THE MAIN FORECAST CHALLENGES ARE INCREASING CLOUDS TONIGHT AND A FEW
SPRINKLES, THEN HIGH TEMPERATURES ON SUNDAY AHEAD OF A WARM FRONT.
MODELS IN AGREEMENT WITH MOVING A COLD UPPER LEVEL TROUGH SLOWLY
EASTWARD ACROSS THE UPPER MIDWEST INTO SUNDAY WITH NORTHWEST FLOW
ALOFT CONTINUING OVER THE CENTRAL PLAINS. AS THE UPPER TROUGH
MOVES EAST, A RIDGE OF COOLER SURFACE HIGH PRESSURE WILL SLOWLY
PROGRESS EASTWARD FROM THE MISSOURI VALLEY INTO THE MID
MISSISSIPPI VALLEY ALLOWING A WARM FRONT TO PUSH NORTH INTO
EASTERN COLORADO TO JUST SOUTH OF ELKHART AND INTO CENTRAL
OKLAHOMA ON SUNDAY AFTERNOON. MID AND UPPER LEVEL MOISTURE AND
CLOUDINESS IS ALSO FORECAST TO INCREASE AROUND AND AFTER MIDNIGHT
ACROSS WESTERN KANSAS AS WEAK 800-700MB FRONTOGENESIS AND
ISENTROPIC LIFT EVOLVE ALOFT AHEAD OF THE SURFACE WARM FRONT. DEEP
MOISTURE AND CAPE ARE LACKING FOR ELEVATED THUNDERSTORMS, HOWEVER
COULD BE ENOUGH LIFT FOR SOME LIGHT SHOWERS OR SPRINKLES MAINLY IN
THE FORM OF VIRGA. WILL KEEP A SILENT POP GOING AFTER MIDNIGHT
TONIGHT WITH INCREASING CLOUDINESS.
FOR TONIGHT LOOK FOR INCREASING CLOUDINESS WITH SOUTHEAST WINDS
DECREASING TO 10 TO 15 MPH. OVERNIGHT LOWS WILL RANGE FROM THE LOWER
40S FROM DIGHTON TO SAINT JOHN AND NORTH TO THE MID AND UPPER 40S
ELSEWHERE. THESE TEMPS ARE A FEW DEGREES WARMER THAN CURRENT
GUIDANCE DUE TO CLOUDINESS EXPECTED. THEN FOR SUNDAY, MODELS
CONTINUE TO SHOW INCREASING UPPER LEVEL MOISTURE IN THE FORM OF
CIRRUS CLOUDS. HIGH TEMPERATURES WERE LOWERED A FEW DEGREES FROM
PREVIOUS FORECAST WITH EXPECTED HIGH LEVEL CLOUDINESS AND
SOUTHEASTERLY UPSLOPE FLOW AHEAD OF THE WARM FRONT. WINDS LOOK TO
INCREASE TO 15 TO 25 MPH BY LATE MORNING INTO THE AFTERNOON WITH
HIGHS FROM THE MID 70S NORTH OF A GARDEN CITY TO DODGE CITY TO
MEDICINE LODGE LINE AND WARMER LOW TO MID 80S SOUTH.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 329 PM CDT SAT SEP 22 2012
FORECAST CHALLENGES LIE AHEAD THROUGH THE MIDDLE OF THE WEEK WITH
REGARD TO PRECIPITATION AND CONVECTIVE CHANCES AND TO A LESSER
EXTENT TEMPERATURES.
WARMER OVERNIGHT LOWS WILL BE EXPECTED ON SUNDAY NIGHT AS A BETTER
AS WARMER BOUNDARY LAYER AIR ADVECTS INTO SW KANSAS AHEAD OF THE
EASTERN COLORADO TROUGH AND PANHANDLES SURFACE LOW. MONDAY SHOULD
REMAIN DRY AND WARMING ACROSS THE SOUTHERN HALF OF WESTERN KANSAS.
SOUTH CENTRAL KANSAS COULD BE THE WARMEST INTO TUESDAY, AS A SURFACE
LOW REMAINS QUASI-STATIONARY OR SLOWLY EAST DURING THE TIMEFRAME.
ALTHOUGH THE ATMOSPHERE WOULD BE CONDITIONALLY UNSTABLE, THE LOW`
CONVERGENCE REGIONS IN AND OF ITSELF MIGHT NOT BE ENOUGH TO SET OFF
SHOWERS AND THUNDERSTORMS. A BETTER CATALYST APPEARS IN THE MODELS
IN THE FORM OF SHORTWAVES BEGINNING AS EARLY AS TUESDAY OR TUESDAY
EVENING. WEAK LOW AMPLITUDE TROUGHING WILL REMAIN IN PLACE OVER THE
WESTERN STATES AND INTO THE CENTRAL ROCKIES DURING THIS PERIOD WHICH
WILL ALLOW OPPORTUNITIES FOR MULTIPLE SHORTWAVE IMPULSES TO INFLUENCE
WESTERN AND CENTRAL KANSAS. BY THE MIDDLE OF THE WEEKEND, NEGATIVE
VORTICITY ADVECTION AND INCREASED SUBSIDENCE SHOULD BEGIN TO
MAKE AN IMPACT AND ELIMINATE CHANCES FOR SHOWERS OR STORMS.
TEMPERATURES WILL REMAIN SEASONAL THROUGH THE PERIOD, GENERALLY IN
THE LOW 80S TO UPPER 70S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1258 AM CDT SUN SEP 23 2012
A LARGE CANADIAN HIGH PRESSURE SYSTEM WILL CONTINUE TO BUILD
SOUTHWARD FROM THE EASTERN DAKOTAS TO KENTUCKY BY MONDAY MORNING. A
TROUGH OF LOW PRESSURE WILL DEEPEN IN THE LEE OF THE ROCKIES TODAY.
A STATIONARY FRONT EXTENDING FROM SOUTHEAST COLORADO ACROSS THE
TEXAS PANHANDLE TO EXTREME NORTHERN TEXAS WILL BEGIN TO MOVE NORTH
AS A WARM FRONT TONIGHT AND WILL EXTEND FROM FROM NEAR ELKHART TO
EAST CENTRAL OKLAHOMA BY MONDAY MORNING.
MID LEVEL FRONTOGENESIS WILL SUPPORT CONTINUED DEVELOPMENT OF
SCATTERED SHOWERS IN SOUTHWEST KANSAS EARLY THIS MORNING. SHOWERS
WILL BE IN THE VICINITY OF GCK AND DDC FROM 07Z THROUGH 12Z BUT WILL
WEAKEN AND MOVE OFF TO THE SOUTHEAST AFTER 12Z. THE SHOWERS WILL BE
LIGHT AND WILL NOT RESULT IN SIGNIFICANT VISIBILITY RESTRICTIONS.
BROKEN CLOUDS WITH BASES AOA 100 WILL PREVAIL EARLY THIS MORNING
IMPROVING TO ONLY A FEW CLOUDS AOA 150 BY LATE MORNING. SOUTHEAST
WINDS 10 TO 15 KNOTS WILL PREVAIL THROUGH THE DAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 53 83 62 86 / 0 0 0 10
GCK 52 83 58 84 / 0 0 10 10
EHA 59 89 60 87 / 0 0 10 10
LBL 56 89 62 87 / 0 0 10 10
HYS 52 76 55 82 / 0 0 10 10
P28 56 92 66 90 / 0 0 0 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...UMSCHEID
SHORT TERM...KRUSE
LONG TERM...RUSSELL
AVIATION...RUTHI
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
145 PM PDT SUN SEP 23 2012
.SYNOPSIS...
HIGH PRESSURE AND HOT CONDITIONS WILL GIVE WAY TO A TROUGH OF LOW
PRESSURE ON MONDAY. THIS WILL BRING A CHANGE TO THE WEATHER...WITH
DEEPER AND MORE PERSISTENT LOW CLOUDS...AS WELL AS GUSTY WEST WINDS
IN THE MOUNTAINS AND DESERTS AT TIMES. A WARMING TREND SHOULD BEGIN
BY MIDWEEK AND CONTINUE THROUGH FRIDAY.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.SHORT TERM (TODAY THROUGH TUESDAY)...
THE HRRR MODEL WAS SLOW TO CLEAR THE LOW CLOUDS OUT OF THE COASTAL
WATERS TODAY...AND HAD THE RIGHT IDEA UP TO NOW. THERE IS STILL SOME
LOW CLOUDS SOUTH COAST THAT SHOULD DISSIPATE LATE AFTERNOON. IT
BRINGS A SLIVER OF LOW CLOUDS INTO THE EXTREME SOUTH COAST..QUITE
LOW IN FACT...AND SUPPORTS AT LEAST PATCHY DENSE FOG. HAVE PLACED
PATCHY DENSE FOG IN THE FORECAST FOR THE HIGHER COASTAL AREAS AND
LOWER VALLEY AREAS FOR TONIGHT.
FOR MONDAY AND TUESDAY...INLAND TROUGHING IS EXPECTED...AND
SHOULD INTRODUCE MORE LOW CLOUDS...AND COOLING... ESPECIALLY INLAND
COASTAL AREAS AND WESTERN VALLEYS. GUSTY WESTERLY WINDS WILL DESCEND
ON THE MOUNTAIN AND DESERT AREAS...WITH A PEAK ON MONDAY AFTERNOON
OR EARLY EVENING. SPEEDS SHOULD BE BELOW ADVISORY STRENGTH.
&&
.LONG TERM (WEDNESDAY THROUGH SATURDAY)...
THE MIDWEEK TROUGH IS EXPECTED TO PUSH EAST AND THE FLOW SHOULD
TREND OFFSHORE ON THURSDAY AND FRIDAY FOR LESS MARINE LAYER LOW
CLOUDS AND A WARMING TREND. THE GFS ENSEMBLE MEAN AND ECMWF PLACE
THE LOW SOMEWHERE FROM 100 TO 500 MILES TO OUR SOUTHWEST WHICH POINT
TOWARD EITHER HOT...OR EVEN HOTTER. I HAVE ADJUSTED THE TEMPERATURE
GRIDS UP TO REFLECT THE POTENTIAL FOR A GOOD WARMUP INTO NEXT
WEEKEND. A TROPICAL FEATURE COULD GET CLOSE ENOUGH TO GIVE US SOME
HIGH CLOUDS AND REINFORCE THE OFFSHORE FLOW...BUT WILL USE A TONED
DOWN APPROACH COMPARED TO THE GFS FOR NOW.
&&
.AVIATION...
232030Z...COASTAL AREAS...PATCHY LOW CLOUDS AND FOG LINGERING AT THE
BEACHES THIS AFTERNOON. CLOUD BASES ARE AROUND 300 FT MSL AND TOPS
AROUND 800 FT MSL. PATCHY VIS 3-5SM. THE LOW CLOUDS AND FOG WILL
LIKELY RETURN TO THE COASTAL AREA TAF SITES AFT 08Z MON. EXPECT
BKN-OVC CIGS WITH BASES AROUND 300 FT MSL AND TOPS NEAR 1000 FT
MSL...ALONG WITH PATCHY VIS 3-5SM...LOCALLY BLO 1SM. KSAN AND KCRQ
ARE THE MOST LIKELY TO BE AFFECTED WHILE KSNA IS NOT LIKELY TO BE
AFFECTED. EXPECT CLEARING TO THE BEACHES BY 17Z MON. ABV THE MARINE
LAYER...SCT CLOUDS LAYERED FROM 7000 FT TO 15000 FT THROUGH MON.
ELSEWHERE...SCT LAYERS 7000 FT TO 15000 FT.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC...SMALL
AVIATION/MARINE...PG
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
915 AM PDT SUN SEP 23 2012
.SYNOPSIS...
HIGH PRESSURE ALOFT OVER THE WEST WILL BRING ABOVE AVERAGE
TEMPERATURES TO THE REGION TODAY. BY MONDAY A TROUGH OF LOW PRESSURE
WILL BEGIN TO DEEPEN OVER THE WESTERN STATES...AND AFFECT THE AREA
THROUGH WEDNESDAY. IT WILL BRING MORE PERSISTENT LOW CLOUDS...AS
WELL AS GUSTY WEST WINDS TO THE MOUNTAINS AND DESERTS AT TIMES. A
WARMING TREND SHOULD BEGIN BY MIDWEEK AND CONTINUE THROUGH FRIDAY.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.SHORT TERM (TODAY THROUGH TUESDAY)...
THE HRRR MODEL IS SLOW TO CLEAR THE LOW CLOUDS OUT OF THE COASTAL
WATERS...AND IT LOOKS LIKE IF IT BRINGS IT BACK...IT WOULD BE AFTER
04Z THIS EVENING. WITH SUCH A LOW...STRONG INVERSION...WARM TO HOT
TODAY LOOKS GOOD.
FOR MONDAY AND TUESDAY...TROUGHING WILL INTRODUCE COOLING...MORE LOW
CLOUDS...AND COOLING...ESPECIALLY INLAND COASTAL AREAS AND WESTERN
VALLEYS. THE FIRST DECENT WESTERLY WINDS IN A WHILE SHOULD SHOW UP
IN THE MOUNTAINS AND DESERTS...PEAKING MONDAY SOMETIME LATE
AFTERNOON OR EARLY EVENING.
&&
.LONG TERM (WEDNESDAY THROUGH SATURDAY)...
ONSHORE FLOW WILL WEAKEN AND WEAK HIGH PRESSURE MAY RETURN FOR NEXT
WEEKEND FOR A WARMING TREND AND SHALLOWER MARINE LAYER.
PRECIPITATION FROM THE REMNANTS OF TROPICAL CYCLONE MIRIAM WILL MOST
LIKELY REMAIN TO THE SOUTH AND EAST OF SOUTHERN CALIFORNIA THOUGH
SOME HIGH CLOUDS ARE POSSIBLE AT TIMES NEXT WEEKEND.
&&
.AVIATION...
231530Z...COASTAL AREAS...LOW CLOUDS AND FOG HAVE BEGUN TO LIFT THIS
MORNING...BUT PATCHES REMAIN ALONG THE SOUTHERN SAN DIEGO COUNTY
COAST WHERE CIGS ARE LOCALLY BKN-OVC WITH BASES AROUND 200 FT MSL
AND TOPS TO 800 FT MSL. FOG WITH LOCAL VIS BLO 3SM ACCOMPANIES THE
LOW CLOUDS. EXPECT ONLY SCT LOW CLOUDS WITH UNRESTRICTED VIS BY 17Z.
THE LOW CLOUDS AND FOG WILL LIKELY TO RETURN TO THE COASTAL AREAS
AFT 08Z MON WITH CIGS AND VIS SIMILAR TO THIS MORNING. ABV THE
MARINE LAYER...SCT-BKN CLOUDS ABV 15000 FT THROUGH MON.
ELSEWHERE...SCT-BKN LAYERS ABV 15000 FT.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC...SMALL
AVIATION/MARINE...PG
AREA FORECAST DISCUSSION
NWS LINCOLN IL
300 PM CDT SUN SEP 23 2012
.DISCUSSION...
ISSUED 300 PM CDT SUN SEP 23 2012
12Z MODELS ARE FAIRLY SIMILAR EARLY THIS WEEK AND THEN DIVERGE
DURING 2ND HALF OF THE WEEK. USED A MODEL BLEND AND THINK GFS MAY
BE TOO FAR NORTH AND TOO WET WITH QPF THU NIGHT WHILE ECMWF MODEL
APPEARS TOO FAR SOUTH.
SHORT TERM...TODAY THROUGH TUESDAY NIGHT
WILL ISSUE FROST ADVISORY OVERNIGHT AND EARLY MONDAY MORNING FOR
ENTIRE CWA OF CENTRAL AND SOUTHEAST IL WITH LOWS GENERALLY IN THE
MID 30S. THESE LOWS ARE GENERALLY NEAR OR BELOW COOLER MET
GUIDANCE LOWS WHICH WORKED BETTER FOR LOWS EARLY THIS MORNING.
FROST WILL NOT BE QUITE AS WIDESPREAD IN AREAS SW OF SPRINGFIELD
WHERE LIGHT RETURN SSE FLOW STARTS AND SOME THIN CIRRUS CLOUDS BY
DAYBREAK. 1027 MB HIGH PRESSURE OVER WESTERN IA INTO NORTHERN MO TO
BY NEAR TAYLORVILLE BY 06Z/1 AM TONIGHT AND INTO THE LOWER OHIO
VALLEY BY DAWN MONDAY. THIS TO LIKELY BRING FROST TO REGION LATER
TONIGHT AND EARLY MON MORNING WITH LIGHT TO CALM WINDS AND CLEAR
SKIES AND LOW DEWPOINTS IN THE LOWER 30S. RECORD LOWS ARE MOSTLY
IN THE LOWER 30S AND CHAMPAIGN COULD GET CLOSE TO THEIR RECORD LOW
OF 33F SET ON SEP 24 1928. NOTE RECORD LOWS FOR SEP 24 BELOW.
HIGH PRESSURE DRIFTS EAST INTO THE MID ATLANTIC STATES BY SUNSET
MON WITH INCREASING MID/HIGH CLOUDS FROM SW TO NE DURING THE DAY
MONDAY. DEVELOPING BREEZY SOUTHERLY FLOW TO WARM UP HIGHS MOSTLY
IN THE LOWER 70S. SERIES OF SHORT WAVES TO EJECT FROM THE CENTRAL
PLAINS INTO CENTRAL/SE IL FROM MON NIGHT INTO THE REST OF THE WORK
WEEK BRINGING CHANCES OF SHOWERS AND THUNDERSTORMS. BEST CHANCES
APPEAR TO BE TUE NIGHT AND ESPECIALLY SOUTHERN AREAS. SPC HAS 5%
RISK OF MARGINAL LARGE HAIL AND GUSTY WINDS ALONG AND SOUTH OF A
RUSHVILLE TO DANVILLE LINE TUE AFTERNOON/EVENING WITH SOME WIND
SHHEAR THOUGH INSTABILITY IS SOMEWHAT LIMITED. TEMPS WARM UP
INTO THE UPPER 70S TO NEAR 80F TUE AND STAY NEAR OR A BIT ABOVE
NORMAL DURING MID WEEK.
LONG TERM...WEDNESDAY THROUGH SUNDAY
BEST CHANCES OF SHOWERS AND THUNDERSTORMS TO SHIFT INTO SOUTHERN
AREAS WED-FRI THOUGH GET A BIT FURTHER NORTH DURING THU NIGHT. NOT
TOO MANY CHANGES MADE TO EXTENDED FORECAST AND HAVE 20-40% CHANCE
OF CONVECTION SAT WITH HIGHEST CHANCES IN SE IL WITH ANOTHER
DISTURBANCE MOVING UP FROM THE SW.
KH
&&
.CLIMATE...
ISSUED 300 PM CDT SUN SEP 23 2012
RECORD LOWS FOR MONDAY MORNING SEP 24...
PEORIA........ 33F IN 1989
SPRINGFIELD... 33F IN 1989
LINCOLN....... 28F IN 1928
BLOOMINGTON... 33F IN 1942
CHAMPAIGN..... 33F IN 1928
DECATUR....... 31F IN 1928
EFFINGHAM..... 28F IN 1928
GALESBURG..... 33F IN 1942
MATTOON....... 30F IN 1928
PALESTINE..... 28F IN 1928
&&
.AVIATION...
ISSUED 1229 PM CDT SUN SEP 23 2012
VFR CONDITIONS WILL PREVAIL THROUGHOUT THE NEXT 24 HOURS.
THE LATEST SURFACE ANALYSIS INDICATED SURFACE HIGH PRESSURE
CENTERED IN WESTERN IA...WITH A RIDGE AXIS EXTENDING SOUTHEAST TO
THE OZARKS. MIXING IN THE LOWER LEVELS OF THE ATMOSPHERE AHEAD OF
THIS RIDGE WAS RESULTING IN OCCASIONAL GUSTS FROM THE NW. THE NAM
BUFKIT FORECAST SOUNDINGS INDICATE THE POTENTIAL FOR GUSTS UP TO
15KTS UNTIL 23-00Z WHEN WE LOSE THE MIXING AND START TO DECOUPLE
THE LOWER ATMOSPHERE. A LITTLE BIT OF MOISTURE EAST OF THE RIDGE
AXIS WILL ALSO RESULT IN FEW TO SCT CUMULUS AROUND 5KFT THIS
AFTERNOON...PARTICULARLY IN EASTERN IL.
THE LATEST NAM AND HRRR BOTH INDICATE THAT THE SURFACE RIDGE AXIS
WILL BE OVER CENTRAL IL LATE THIS EVENING...AND SHIFT EAST OF THE
AREA BY DAYBREAK. LOW LEVEL MIXING WILL ONCE AGAIN DEVELOP BY LATE
MORNING...PRODUCING A S-SSW WIND AROUND 10 KTS BY 15Z. DRY AIR
WILL ONCE AGAIN RESULT IN A CLEAR SKY THROUGH LATE MORNING IN ALL
OF CENTRAL AND EASTERN IL.
MILLER
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
FROST ADVISORY FROM 1 AM TO 8 AM CDT MONDAY FOR ILZ027>031-
036>038-040>057-061>063-066>068-071>073.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1229 PM CDT SUN SEP 23 2012
.DISCUSSION...
ISSUED 1109 AM CDT SUN SEP 23 2012
UPDATED THE FORECAST TO BUMP UP HIGH TEMPERTURES A FEW DEGREES
PARTICULARLY IN WEST CENTRAL IL. PLENTY OF MIXING IS ANTICIPATED...
MOST LIKELY ABOVE 850 MB...BASED ON THE 12Z ILX RAOB. THIS WOULD
RESULT IN HIGHS IN THE MID 60S ACROSS MUCH OF THE FORECAST AREA.
LOW LEVELS WINDS ARE NOT AS STRONG AS YESTERDAY...SO WEST TO
NORTHWEST WINDS OF 10 TO 15 MPH WITH OCCASIONAL GUSTS UP TO 20 MPH
WILL BE RULE. OTHERWISE...EVERYTHING ELSE IN THE CURRENT FORECAST
LOOKS GOOD. WILL BE ANALYZING THE POTENTIAL FOR FROST AGAIN
TONIGHT...ESPECIALLY EAST OF I-55...AND MAY NEED AN ADVISORY FOR
EARLY MONDAY MORNING IF IT APPEARS THAT THE FROST WILL BE
WIDESPREAD ENOUGH.
&&
.AVIATION...
ISSUED 1229 PM CDT SUN SEP 23 2012
VFR CONDITIONS WILL PREVAIL THROUGHOUT THE NEXT 24 HOURS.
THE LATEST SURFACE ANALYSIS INDICATED SURFACE HIGH PRESSURE
CENTERED IN WESTERN IA...WITH A RIDGE AXIS EXTENDING SOUTHEAST TO
THE OZARKS. MIXING IN THE LOWER LEVELS OF THE ATMOSPHERE AHEAD OF
THIS RIDGE WAS RESULTING IN OCCASIONAL GUSTS FROM THE NW. THE NAM
BUFKIT FORECAST SOUNDINGS INDICATE THE POTENTIAL FOR GUSTS UP TO
15KTS UNTIL 23-00Z WHEN WE LOSE THE MIXING AND START TO DECOUPLE
THE LOWER ATMOSPHERE. A LITTLE BIT OF MOISTURE EAST OF THE RIDGE
AXIS WILL ALSO RESULT IN FEW TO SCT CUMULUS AROUND 5KFT THIS
AFTERNOON...PARTICULARLY IN EASTERN IL.
THE LATEST NAM AND HRRR BOTH INDICATE THAT THE SURFACE RIDGE AXIS
WILL BE OVER CENTRAL IL LATE THIS EVENING...AND SHIFT EAST OF THE
AREA BY DAYBREAK. LOW LEVEL MIXING WILL ONCE AGAIN DEVELOP BY LATE
MORNING...PRODUCING A S-SSW WIND AROUND 10 KTS BY 15Z. DRY AIR
WILL ONCE AGAIN RESULT IN A CLEAR SKY THROUGH LATE MORNING IN ALL
OF CENTRAL AND EASTERN IL.
MILLER
&&
.CLIMATE...
ISSUED 200 AM CDT SUN SEP 23 2012
RECORD LOWS FOR MONDAY MORNING...
PEORIA........ 33F IN 1989
SPRINGFIELD... 33F IN 1989
LINCOLN....... 28F IN 1928
BLOOMINGTON... 33F IN 1942
CHAMPAIGN..... 33F IN 1928
DECATUR....... 31F IN 1928
EFFINGHAM..... 28F IN 1928
GALESBURG..... 33F IN 1942
MATTOON....... 30F IN 1928
PALESTINE..... 28F IN 1928
GEELHART
&&
.PREV DISCUSSION...
ISSUED 300 AM CDT SUN SEP 23 2012
EARLY MORNING SURFACE MAP SHOWED HIGH PRESSURE CENTERED OVER
NORTHEAST SOUTH DAKOTA...EXTENDING SOUTHWARD INTO THE MID
MISSISSIPPI VALLEY. SKIES MAINLY CLEAR THE LAST FEW HOURS OVER THE
FORECAST AREA...EXCEPT FOR SOME PATCHY STRATOCUMULUS FROM DECATUR
TO RANTOUL. WINDS IN MANY AREAS HAVE GONE CALM AND ALLOWED
TEMPERATURES TO DIP INTO THE UPPER 30S...WHILE SOME 40S HUNG ON
ESPECIALLY FROM PEORIA SOUTHEAST TO LAWRENCEVILLE...WHERE WINDS
HAVE REMAINED AROUND 5 MPH.
TEMPERATURES MONDAY MORNING REMAIN A CONCERN...ALONG WITH MORE
FROST POTENTIAL. HOWEVER...THE MAIN FORECAST ISSUE WILL BE WITH
PERIODIC SHOWERS AND THUNDERSTORMS...WITH A FRONTAL BOUNDARY THAT
WILL BE DRAPED OVER THE AREA MUCH OF THIS WEEK.
SHORT TERM...TODAY THROUGH TUESDAY...
THE CENTER OF THE HIGH SHOULD BE OVER SOUTHWEST INDIANA BY LATE
EVENING. TEMPERATURES TODAY WILL BE SIMILAR TO THOSE ON
SATURDAY...BUT WILL FEEL MORE PLEASANT WITH MUCH LOWER WIND
SPEEDS. MAIN FOCUS FOR FROST WILL BE ACROSS THE EASTERN CWA
TONIGHT. WILL NEED TO MONITOR THIS AREA FOR ANY ADVISORIES...BUT
WILL LET THE DAY SHIFT HANDLE THAT AFTER EVALUATING WHAT ENDS UP
HAPPENING THIS MORNING FROST-WISE. THERMAL GRADIENT AT 850 MB WILL
BE FOCUSING ALONG THE MISSISSIPPI RIVER LATE TONIGHT AND WILL MOVE
THROUGH THE CWA ON MONDAY. THE WARMER SURFACE TEMPS WILL BE ACROSS
THE WESTERN CWA...AS 850 MB TEMPS RISE TO +14C.
ANOTHER SURGE OF WARM AIR ALOFT WILL PUSH THROUGH THE CWA MONDAY
NIGHT...AS SOME ELEVATED CONVECTION DEVELOPS OUT IN MISSOURI
ALONG ANOTHER DEVELOPING FRONT...BEFORE SHIFTING EASTWARD INTO
ILLINOIS. CENTRAL AND SOUTHERN CWA APPEAR MORE LIKELY TO SEE SOME
OF THIS ARRIVE BY TUESDAY MORNING. MEANWHILE...THE MAIN COLD FRONT
WILL BE DROPPING SOUTHWARD ON TUESDAY...AS ANOTHER WAVE SWINGS
THROUGH THE UPPER GREAT LAKES IN ASSOCIATION WITH THE BROAD TROUGH
THAT HAS BEEN IN PLACE FOR SEVERAL DAYS NOW. MUCH OF THE CWA WILL
BE IN THE WARM SECTOR TUESDAY...ALLOWING CAPES TO RISE TO AROUND
1500 J/KG...SUPPORTING CONTINUED THUNDERSTORM CHANCES. MAY SEE
SOME STORMS WITH HAIL AND GUSTY WINDS...BUT SEVERE THREAT APPEARS
RELATIVELY LOW...WITH 5 PERCENT CHANCES MENTIONED IN THE LATEST
SPC DAY3 OUTLOOK. WILL CARRY THE HIGHEST RAIN CHANCES TUESDAY
NIGHT.
LONG TERM...WEDNESDAY THROUGH SATURDAY...
MAIN QUESTION IS HOW FAR THIS FRONT WILL MAKE IT...AS IT WILL
BECOME SANDWICHED BETWEEN THE NORTHERN AND SOUTHERN BRANCHES OF
THE JET STREAM. MOST OF THE EVENING MODELS HAVE IT GENERALLY ALONG
AN WEST-EAST AXIS CENTERED NEAR THE I-72 CORRIDOR BY WEDNESDAY
MORNING...THEN REACHING THE OHIO RIVER AREA TOWARD LATE EVENING AS
HIGH PRESSURE BUILDS INTO THE GREAT LAKES. THE NOTABLE EXCEPTION
IS THE GFS MODEL...WHICH KEEPS IT OVER CENTRAL ILLINOIS UNTIL A
DEVELOPING SURFACE LOW ARRIVES FRIDAY MORNING. THAT SOLUTION KEEPS
PERIODIC RAIN CHANCES GOING THROUGH FRIDAY...WHEREAS THE
ECMWF/CANADIAN SOLUTIONS WOULD LIKELY BRING DRY WEATHER TO THE
NORTHERN CWA FOR A GOOD PORTION OF THIS PERIOD. FOR THIS
FORECAST...WILL SLOWLY SPREAD THE SLIGHT CHANCE POPS SOUTHWARD
THROUGH THURSDAY...BEFORE BRINGING THEM BACK UP THURSDAY NIGHT
INTO THE 30-40 PERCENT RANGE AS A SHORTWAVE APPROACHES FROM THE
WEST IN THE SOUTHERN JET STREAM. ONCE THIS PARTICULAR WAVE CLEARS
THE AREA ON FRIDAY...DRY WEATHER IS EXPECTED AS THE WEEKEND
BEGINS.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
134 PM EDT SUN SEP 23 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 534 AM EDT SUN SEP 23 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A DEEP TROF OVER THE GREAT
LAKES REGION. LAST SIGNIFICANT SHORTWAVE ROTATING THRU TROF PASSED
ACROSS UPPER MI LATE YESTERDAY AFTN/EARLY EVENING...PROVIDING A GOOD
BOOST TO LAKE EFFECT PCPN. UNDER DEEP CYCLONIC FLOW/DEEP MOISTURE
(UPSTREAM 00Z CWPL SOUNDING SHOWED SATURATION TO 700MB) AND 850MB
TEMPS OF -2 TO -4C PER LATEST RUC ANALYSIS...LAKE EFFECT SHRA
CONTINUE WITHIN GENERAL NNW WIND FLOW. DESPITE DEEP
MOISTURE/FAVORABLE OVERWATER INSTABILITY...SHRA COVERAGE IS A LITTLE
LESS THAN EXPECTED. HOWEVER...DEEP CONVECTION/MOISTURE IS NO DOUBT
LEADING TO SOME BRIEF HVY RAINFALL/GRAUPEL WITH SOME OF THE SHRA.
MID/UPPER TROF OVER THE GREAT LAKES WILL BEGIN TO SHIFT E TODAY...
RESULTING IN RISING HEIGHTS. AT THE LOWER LEVELS...THE UPPER LAKES
WILL REMAIN FIRMLY WITHIN THE THERMAL TROF. WITH MORNING 850MB TEMPS
OF -2 TO -4C ONLY RISING TO 0 TO -2C BY LATE AFTN...LAKE EFFECT -SHRA
WILL CONTINUE THRU THE DAY. HOWEVER...RISING HEIGHTS ALONG WITH
ADVECTION OF DRIER AIR AT THE LOW LEVELS AS WINDS BACK MORE WESTERLY
WILL SPELL DIMINISHING SHRA FROM W TO E THRU THE DAY. BEING VERY
EARLY IN THE LAKE EFFECT SEASON...DIURNAL HEATING WILL ALSO DISRUPT
LAKE EFFECT PROCESSES THIS AFTN...AIDING THE DIMINISHING TREND.
SO...EXPECT LINGERING NW FLOW LAKE EFFECT SHRA OVER THE W TO END BY
EARLY AFTN. OVER THE E...LAKE EFFECT SHRA WILL DECREASE IN
COVERAGE...BUT PROBABLY NOT END UNTIL LATER THIS EVENING WHEN WINDS
BACK TO AN OFFSHORE DIRECTION. GIVEN VIGOROUS CONVECTION/DEEP CLOUD
DEPTH THIS MORNING...HEAVIER SHRA WILL CONTINUE TO MIX WITH GRAUPEL
AT TIMES.
WAA REGIME RAMPS UP ON WESTERLY WINDS TONIGHT AHEAD OF THE NEXT
SHORTWAVE TROF WHICH WILL BE DROPPING S TOWARD THE UPPER LAKES.
BEFORE HIGH CLOUDS ARRIVE AHEAD OF APPROACHING SHORTWAVE AND BEFORE
LOW-LEVEL WINDS BEGIN TO INCREASE SUBSTANTIALLY...TEMPS WILL HAVE AN
OPPORTUNITY TO FALL QUICKLY THIS EVENING UNDER DRY AIR MASS
(PRECIPITABLE WATER 50-60PCT OF NORMAL). FAVORED THE LOWER SIDE OF
GUIDANCE GIVEN THE COOL AFTN TODAY. TEMPS WILL PROBABLY SLIP BLO
FREEZING ACROSS A GOOD PORTION OF THE FCST AREA WELL INLAND FROM
LAKE SUPERIOR. TEMPS SHOULD BEGIN TO RISE SLOWLY OVERNIGHT AS
CLOUDS/WINDS INCREASE.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 534 AM EDT SUN SEP 23 2012
UPPER TROUGH THAT HAS BEEN PROVIDING THE COOL AND WET CONDITIONS
OVER THE LAST WEEK WILL HAVE SHIFTED EAST BY THE START OF THE
PERIOD. BUT...A SECONDARY WAVE WILL DROP S TOWARDS THAT AREA MON
AFTN AND THROUGH THE UPPER GREAT LAKES MON NIGHT. A SFC HIGH TO THE
S AND APPROACHING TROUGH/SHORTWAVE WILL LEAD TO STRONG SW LLVL
JET OVER THE CWA AT THE START OF THE LONG TERM PERIOD. WIND GUSTS
FOR MON WILL DEPEND ON HOW QUICKLY AREA CAN MIX INTO THE STRONGER
WINDS ALOFT...SINCE LLVL JET WILL QUICKLY SHIFT SE THROUGH THE DAY.
STRONGEST WINDS WILL BE OVER WRN LK SUPERIOR AND FAR WRN UPPER
MI...CLOSEST TO THE TIGHTENING PRESSURE GRADIENT. WITH H925-850
WINDS DURING THE MORNING IN THE 40-50KT RANGE WOULD THINK
EXPOSED...HIGHER TERRAIN LOCATIONS WOULD SEE GUSTS TO 40KTS NEAR
THE KEWEENAW AND EVEN HIGHER IF MIXING CAN OCCUR FASTER.
ELSEWHERE...WITH THE LLVL JET QUICKLY SHIFTING THROUGH...ONLY EXPECT
A FEW HOURS OF GUSTS TO 20-30KTS. FRONT WILL SLIDE FROM NW TO SE
ACROSS THE CWA MON AFTN INTO EARLY EVENING AND WINDS WILL QUICKLY
DIMINISH AS IT PUSHES THROUGH. AS FOR CLOUDS/PCPN...EXPECT MAINLY
MID CLOUDS TO AFFECT MUCH OF THE CWA THROUGH THE DAY. LLVLS DON/T
BECOME MOIST UNTIL WELL AFTER THE FRONT HAS SHIFTED TO THE S OF
THE AREA AND NRLY FLOW DROPS THE LOWER CLOUDS IN FROM WRN ONTARIO.
THEREFORE...EXPECT PCPN STAYING OVER NE LK SUPERIOR UNDER THE DEEPER
MOISTURE AND BETTER H850-700 Q-VECTOR CONV. THIS AREA WILL
ALSO HAVE ADDITIONAL MOISTURE FROM LEFT OVER LK ENHANCED PCPN
THAT WILL MOVE NE WITH THE SW WINDS. IT/S THOSE SHOWERS THAT COULD
SLIDE S AS THE WINDS SHIFT AND AFFECT FAR ERN UPPER MI LATE IN THE
AFTN AND EARLY EVENING. FINALLY...MONDAY WILL BE THE FIRST 60
DEGREE DAY IN A WEEK FOR MUCH OF UPPER MI...WITH WARM H850 TEMPS
EASILY PUSHING TEMPS INTO THE 60S.
LK ENHANCED CLOUDS INCREASING MON NIGHT AND COULD SEE SOME LIGHT
SHOWERS OVER THE NCNTRL HIGHER TERRAIN AS H850 TEMPS FALL ENOUGH TO
PUT DELTA-T VALUES TO 14. SHALLOW MOISTURE SHOULD LIMIT IT TO VERY
ISOLATED SHOWERS OVER THE NCNTRL CWA AND EXPECT THIS TO CONTINUE
INTO TUES. HIGH PRESSURE RIDGE WILL ALSO BEGIN TO SLIDE OVER THE
UPPER GREAT LAKES FROM THE CANADIAN PRAIRIES ON TUES AND LEAD TO A
DIMINISHING TREND TO POPS. HIGHS ON TUES SHOULD BE IN THE 50S AND
LOWER 60S...WITH THE WARMEST TEMPS AWAY FROM LK SUPERIOR WHERE THERE
WILL BE MORE SUN.
SECONDARY SHORTWAVE PROGGED TO DROP THROUGH THE UPPER GREAT LKS
ON TUES NIGHT. LLVL MOISTURE ASSOCIATED WITH THE FEATURE AND
H850 TEMPS FALLING TO AROUND -1C SHOULD LEAD TO LK ENHANCED
CLOUDS/SHOWERS REDEVELOPING UNDER NNW FLOW. WITH DECENT LLVL
MOISTURE FROM THE WAVE...EXPECT LK ENHANCED CLOUDS/SHOWERS TO
DEVELOP UNDER THE NNW FLOW THROUGH THE NIGHT. MAY BE A LITTLE
DEEPER MOISTURE OVER ERN LK SUPERIOR AND WITH THE SLIGHTLY COOLER
TEMPS...HAVE POPS INTO THE CHANCE CAT OVER SCNTRL/ERN PORTIONS OF
LK SUPERIOR AND SLIGHT CHANCES ONSHORE. EXPECT THESE SHOWERS TO
CONTINUE INTO THE FIRST HALF OF WED.
SFC HIGH AND UPPER RIDGING WILL THEN BUILD OVER THE CWA WED AFTN
INTO THURS AND PRODUCE DRY CONDITIONS. LLVL MOISTURE SHOULD EXIT AND
LEAD TO CLEARING SKIES WED NIGHT. THUS...EXPECT A COLD NIGHT WITH
THE AREA UNDER THE SFC HIGH AND PWATS AROUND 50 PERCENT OF NORMAL.
WILL FOLLOW PREVIOUS SHIFTS ON GOING BELOW GUIDANCE AND INTERIOR
TEMPS AROUND 30 DEGREES. THIS SHOULD PRODUCE ANOTHER FROST/FREEZE
OVER MUCH OF THE CWA.
UNCERTAINTY STARTS TO ARRIVE IN THE MODELS FOR FRI...AS
GFS/GEM/ECMWF ARE ALL SHOWING A SHORTWAVE APPROACHING THE UPPER
GREAT LAKES BUT DIFFER GREATLY IN TIMING AND LOCATION. THIS IS TO
BE EXPECTED AS THERE ARE INDICATIONS THAT IT BECOMES CUTOFF FROM
THE NRN STREAM FLOW DUE TO A STRONGER WAVE EXITING THE PAC NW. WITH
THIS UNCERTAINTY...AND DRY HIGH PRESSURE RIDGE LIKELY REMAINING
OVER THE CWA...WILL GO WITH A DRY FORECAST FOR FRI/SAT. STANDARDIZED
ANOMALIES OF H500 HEIGHTS ARE AROUND 0.5 TOWARDS FOR THE END OF THE
WEEK...WHICH SHOULD LEAD TO NORMAL TO ABOVE NORMAL TEMPERATURES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 134 PM EDT SUN SEP 23 2012
NW FLOW LAKE EFFECT CLOUDS AND SCATTERED SHOWERS WILL CONTINUE
TODAY...AND WILL BE CONTINUING TO WIND DOWN FROM W TO E AS
INCREASINGLY DRIER AIR ADVECTS INTO THE AREA. -SHRA HAVE ALREADY
ENDED AT KIWD...AND VFR CONDITIONS WILL BE THE RULE THRU THE FCST
PERIOD. AT KCMX THERE IS POTENTIAL FOR BRIEF PERIODS OF MVFR CIGS
THIS AFTERNOON AND EVENING...BUT VFR CONDITIONS WILL LIKELY PREVAIL.
AT KSAW...A FEW LAKE EFFECT RAIN SHOWERS ARE EXPECTED FOR THE FIRST
2 HOURS OR SO OF THE TAF PERIOD UNTIL WINDS TURN MORE NW...WHICH IS
NOT FAVORABLE FOR LAKE EFFECT...SO VFR CONDITIONS SHOULD BE THE
RULE. TIGHTENING PRES GRADIENT TONIGHT WILL LEAD TO POSSIBLE LLWS
TONIGHT...THEN GUSTY WINDS MONDAY...ESPECIALLY AT CMX.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 534 AM EDT SUN SEP 23 2012
SINCE HIGH PRES CURRENTLY OVER THE CNTRL STATES MOVES TO THE OHIO
VALLEY RATHER THAN ACROSS THE GREAT LAKES...WINDS WON`T DIMINISH
MUCH TODAY. SPEEDS WILL LIKELY REMAIN MOSTLY IN THE 15-25KT RANGE AS
NW WINDS BACK MORE WESTERLY. TONIGHT AND MON...TIGHTENING PRES
GRADIENT BTWN THE HIGH TO THE S AND AN APPROACHING COLD FRONT FROM
THE N WILL RESULT IN WINDS RAMPING UP TONIGHT THRU MON MORNING. WSW
GALES OF 35-40KT APPEAR LIKELY OVER MUCH OF THE LAKE. STRONGEST
WINDS WILL OCCUR BTWN ISLE ROYALE AND THE KEWEENAW AND IN PARTICULAR
AROUND THE W SIDE OF THE KEWEENAW DUE TO COASTAL CONVERGENCE. SOME
GUSTS MAY REACH 45KT. AS FRONT PASSES...WINDS WILL QUICKLY DIMINISH
LATE MON AFTN/EVENING. WINDS TUE THRU THU SHOULD BE UNDER 20KT AS
SFC HIGH PRES BUILDS OVER THE GREAT LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING FROM 8 AM TO 5 PM EDT MONDAY FOR LSZ245-265-267.
GALE WARNING FROM 2 AM TO 5 PM EDT MONDAY FOR LSZ263-264-266.
GALE WARNING FROM 5 AM TO 5 PM EDT MONDAY FOR LSZ243-244.
LAKE MICHIGAN...
GALE WATCH FROM MONDAY MORNING THROUGH MONDAY AFTERNOON FOR
LMZ221-248-250.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...SRF
AVIATION...TITUS
MARINE...ROLFSON