Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/20/13
AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
855 PM PDT MON AUG 19 2013
...A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH MIDWEEK...
...RED FLAG WARNING FOR DRY THUNDERSTORMS IN EFFECT...
.DISCUSSION...AS OF 8:40 PM PDT MONDAY...AN UPPER LOW OFF THE
CENTRAL CA COASTLINE CONTINUES TO DOMINATE THE WEATHER PATTERN.
ALL AFTERNOON AND EVENING A LINE OF THUNDERSTORMS EXTENDING FROM
NEAR HALF MOON BAY WEST OVER 100 NM OFFSHORE HAS PRODUCED
THOUSANDS OF LIGHTNING STRIKES. OVER THE PAST HOUR...THESE
THUNDERSTORMS CONTINUES TO BUILD EAST OVER LAND...WITH LIGHTNING
REPORTED AS FAR EAST AS LOS GATOS. IN FACT...IN A ONE HOUR
PERIOD...ENDING AT 7:55 PM...2570 LIGHTNING STRIKES WERE REPORTED
FROM THIS LINE OF THUNDERSTORMS.
THESE THUNDERSTORMS ARE FORECAST TO CONTINUE THROUGH THE OVERNIGHT
HOURS...AND ACTUALLY BACK BUILD TO THE SOUTH AND EAST. BOTH THE NAM
AND HRRR INDICATE THAT THESE STORMS WILL CONTINUE THROUGH THE
12Z TIME FRAME BEFORE THE LOW SHIFTS SLIGHTLY TO THE WEST ALLOWING
THE CONVECTION TO SHIFT TO THE WEST. THE MAIN CONCERN WITH ALL OF
THESE LIGHTNING STRIKES ARE THE POSSIBILITY OF FIRE STARTS.
OTHERWISE...CURRENT FORECAST LOOKS RIGHT ON TRACK WITH THE MAIN
FOCUS OF THUNDERSTORMS FROM THE SF BAY SOUTHWARD THOUGH THE
MORNING HOURS ON TUESDAY. PLEASE CONTINUE TO MONITOR THE FORECAST
FOR THE LATEST INFORMATION REGARDING THE THUNDERSTORMS ACROSS THE
AREA.
.PREVIOUS DISCUSSION...AS OF 2:26 PM PDT MONDAY...MID/UPPER LEVEL
LOW POSITIONED ABOUT 200 MILES TO THE SOUTHWEST OF MONTEREY THIS
AFTERNOON. THIS FEATURE CONTINUES TO PULL MID-LEVEL MOISTURE
ACROSS THE REGION AND HAS CONTRIBUTED TO ELEVATED CONVECTION
ACROSS THE COASTAL WATERS. AS THE LOW REMAINS OFF THE CENTRAL
COAST...THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL REMAIN IN THE
FORECAST FOR PORTIONS OF THE REGION. CHANCES INCREASE ACROSS THE
NORTH AND DIMINISH OVER THE SOUTH TONIGHT THROUGH WEDNESDAY AS
500-700MB MOISTURE INCREASES AND THE LOW BEGINS TO LIFT TO THE
NORTH-NORTHEAST AND APPROACH THE SAN FRANCISCO BAY REGION.
WITH RESPECT TO TEMPERATURES...AFTERNOON TEMPERATURES WILL BE
SLIGHTLY BELOW SEASONAL AVERAGE THROUGH MIDWEEK AS THE AIR MASS
ASSOCIATED WITH THE UPPER LOW APPROACHES THE REGION. WARMEST
CONDITIONS WILL BE INLAND WITH COOLER TEMPERATURES ALONG THE COAST
WITH PERSISTENT ONSHORE FLOW. INLAND TEMPERATURES MAY BE SLOWER TO
WARM OVER THE NORTH WHERE HIGH CLOUDINESS IS MORE LIKELY.
THE INCREASED MOISTURE WILL KEEP OVERNIGHT TEMPERATURES FROM
FALLING MUCH...AND WILL ALSO ALLOW FOR PATCHY FOG DEVELOPMENT
THROUGH MIDWEEK.
BY THURSDAY THE UPPER LOW QUICKLY GETS PICKED UP BY THE MEAN FLOW
AND PULLS WELL NORTH OF THE REGION. THIS PATTERN WILL BE REPLACED
BY MID/UPPER LEVEL TROUGH OFF THE WEST COAST AND WILL MAINTAIN
BELOW NORMAL TEMPERATURES AND A DRY FORECAST LATE THIS WEEK THROUGH
EARLY NEXT WEEK.
&&
.AVIATION...AS OF 4:50 PM PDT MONDAY...AN AREA OF CONVECTION WAS
LOCATED OUT OVER THE COASTAL WATERS. MULTIPLE LIGHTNING STRIKES
HAVE BEEN OBSERVED PARTIALLY BY A LAND BASED NETWORK AND PARTIALLY
BY SATELLITE. BEST CHANCES FOR ADDITIONAL CONVECTION IS OVER THE
SOUTHERN HALF OF THE FORECAST AREA THROUGH THE EVENING.
VICINITY OF KSFO...COORD DISCUSSIONS WITH CWSU AND AGREEMENT IS
THAT VFR WILL HOLD FOR THE EVENING. STRATUS SHOULD AT LEAST HOLD
OFF TIL MUCH LATER TONIGHT IF NOT ALL NIGHT. WEST WIND GUSTS TO 20-22
KNOTS TIL 04Z. MODERATE CONFIDENCE.
KSFO BRIDGE APPROACH...VFR.
MONTEREY BAY AREA TERMINALS...IFR IS REPORTED AT KSNS. FAVORABLE
WEATHER CONDITIONS FOR VFR TO HOLD AT KMRY TIL 06Z. DIFFICULT
FORECASTS THE LAST FEW DAYS SO CONFIDENCE IS ON THE LOW SIDE.
&&
.FIRE WEATHER...AS OF 11:10 AM PDT MONDAY...A STATIONARY UPPER
LEVEL LOW OFF THE SOUTH-CENTRAL CALIFORNIA COAST CONTINUES TO DRAW
MONSOONAL MOISTURE NORTH AND WEST ACROSS CALIFORNIA. THUNDERSTORMS
HAVE THUS FAR BEEN CONFINED TO AREAS WELL TO THE EAST OF THE
DISTRICT...BUT THE MODELS CONTINUE TO FORECAST INCREASING MID
LEVEL MOISTURE AND INSTABILITY ACROSS THE REGION TODAY.
THUS...THUNDERSTORM CHANCES REMAIN IN THE FORECAST.
INITIALLY...ISOLATED THUNDERSTORMS WILL PRODUCE LITTLE...IF
ANY...RAINFALL. WILL CONTINUE WITH A RED FLAG WARNING FOR MOST
INLAND PORTIONS OF THE DISTRICT. THE MODELS HAVE BACKED OFF
SLIGHTLY ON THE AMOUNT OF MOISTURE AND INSTABILITY ACROSS OUR
REGION OVER THE NEXT FEW DAYS...BUT NOT ENOUGH TO WARRANT A
CANCELING OF THE WARNING.
THE LOW WILL BEGIN TO LIFT TO THE NORTH ON TUESDAY AND
THUNDERSTORM CHANCES WILL END FROM SOUTH TO NORTH BEGINNING ON
TUESDAY MORNING. WILL THEREFORE MAINTAIN A RED FLAG WARNING FOR
MONTEREY AND SAN BENITO COUNTIES ONLY THROUGH MIDDAY TUESDAY...BUT
CONTINUE THE WARNING THROUGH AT LEAST TUESDAY NIGHT FOR THE SF BAY
AREA. THUNDERSTORMS WILL LIKELY PRODUCE DECENT RAINFALL BY LATE
MONDAY...BUT EVEN THEN NEW FIRE STARTS WILL STILL BE POSSIBLE
GIVEN HOW DRY THE FUELS ARE.
&&
.FIRE WEATHER...
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.TNGT...RED FLAG WARNING...MOST INLAND PORTIONS OF THE SAN
FRANCISCO AND MONTEREY BAY AREAS.
&&
$$
PUBLIC FORECAST: RILEY/RGASS
AVIATION/MARINE: CANEPA
FIRE WEATHER: DYKEMA
VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO
FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
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WWW.YOUTUBE.COM/NWSBAYAREA
AREA FORECAST DISCUSSION
NWS RENO NV
201 PM PDT SUN AUG 18 2013
.SYNOPSIS...
SHOWERS AND THUNDERSTORMS WILL INCREASE THIS AFTERNOON AND
CONTINUE THROUGH THURSDAY AS LOW PRESSURE OFF THE CENTRAL
CALIFORNIA COAST REMAINS IN PLACE BEFORE MOVING INLAND BY MIDWEEK.
THE STRONGER STORMS WILL PRODUCE HEAVY RAINFALL, HAIL AND FREQUENT
LIGHTNING. ABOVE NORMAL TEMPERATURES ARE EXPECTED ON MONDAY,
BEFORE COOLING BACK TO NEAR SEASONAL NORMALS FOR THE REMAINDER OF
THE UPCOMING WEEK.
&&
.SHORT TERM...
CURRENT WATER VAPOR IMAGERY SHOWS THE UPPER LOW PARKED JUST OFF
THE CALIFORNIA COASTLINE NEAR MONTEREY BAY. SOUTHERLY FLOW
BETWEEN THIS LOW AND HIGH PRESSURE ACROSS SOUTHERN NEW MEXICO HAS
ALLOWED MOISTURE TO SURGE NORTH ACROSS SOUTHERN CALIFORNIA AND
SOUTHERN NEVADA WITH THE 12Z RAOB AT LAS VEGAS REPORTING A
PRECIPITABLE WATER VALUE OF 1.17 INCHES.
MODEL GUIDANCE IS IN GOOD AGREEMENT THAT THE UPPER LOW WILL
REMAIN JUST OFF THE CENTRAL CALIFORNIA COASTLINE THROUGH
WEDNESDAY WITH MOISTURE INCREASING ACROSS THE SIERRA AND WESTERN
NEVADA. THE MAIN CHALLENGE IN THE SHORT TERM WILL BE TIMING THE
INDIVIDUAL SHORT WAVES THAT ROTATE AROUND THE UPPER LOW AND PROVIDE
FORCING FOR THUNDERSTORM ACTIVITY.
THE BEST CHANCE OF THUNDERSTORMS THIS AFTERNOON WILL BE NEAR THE
SIERRA CREST IN MONO AND ALPINE COUNTIES. RECENT RUNS OF THE SHORT
TERM HRRR MODEL SUGGEST A BROADER AREA OF CONVECTION WILL DEVELOP
ACROSS MONO AND MINERAL COUNTIES AND LIFT TO THE NORTHWEST TOWARDS
THE INTERSTATE 80 CORRIDOR THIS EVENING. THE 12Z NAM DEPICTS A
VERY WEAK SHORTWAVE ROTATING AROUND THE UPPER LOW ACROSS WESTERN
NEVADA THIS EVENING WHICH MAY ACT AS THE FORCING FOR THIS
CONVECTION. GIVEN THE RUN TO RUN CONSISTENCY OF THE HRRR THIS
MORNING...DECIDED TO INCREASE POPS ACROSS MONO AND MINERAL
COUNTIES THROUGH MIDNIGHT.
SCATTERED THUNDERSTORMS ARE POSSIBLE ACROSS THE ENTIRE FORECAST
AREA ON MONDAY AS MODEL PRECIPITABLE WATER VALUES INCREASE TO 0.75
INCHES NEAR RENO. WITH THE STORMS TURNING WETTER AND STORM MOTIONS
AROUND 10 KTS, THE MAIN CONCERN WILL BE LOCALLY HEAVY RAIN AND
THE POTENTIAL FOR FLASH FLOODING. MOISTURE WILL INCREASE FURTHER
ON TUESDAY WITH MODEL PRECIPITABLE WATER VALUES NEAR 0.95 INCHES
ACROSS WESTERN NEVADA. A FLASH FLOOD WATCH MAY BE NECESSARY ON
TUESDAY AS THE DEEP MOISTURE WILL BE WELL ESTABLISHED AND STORM
MOTIONS WILL REMAIN SLOW (AROUND 10 KTS).
AREAS OF SMOKE HAVE BEEN ADDED TO THE FORECAST GRIDS FOR THIS
AFTERNOON AND EVENING IN THE CARSON AND WASHOE VALLEYS DUE TO THE
BRUNSWICK FIRE LOCATED TO THE EAST OF CARSON CITY. ALSO INCLUDED
MENTION OF SMOKE ACROSS PORTIONS OF SOUTHERN LYON, WESTERN MINERAL
AND EAST CENTRAL MONO COUNTIES THANKS TO SPRING PEAK WILDFIRE
LOCATED TO THE EAST OF BODIE. MYRICK
.LONG TERM...WEDNESDAY THROUGH SUNDAY...
THERE IS STILL GOOD AGREEMENT AMONG MEDIUM RANGE MODELS WITH THE LOW
LIFTING NORTH ACROSS NORTHERN CALIFORNIA WEDNESDAY INTO THURSDAY AND
MOVING INTO SOUTHERN OREGON AS AN OPEN WAVE BY THURSDAY NIGHT OR
FRIDAY MORNING. THUNDERSTORMS WILL CONTINUE TO BE A THREAT THROUGH
THURSDAY WITH THE BEST CHANCES IN NORTHEAST CALIFORNIA AND NORTHWEST
NEVADA NORTH OF HIGHWAY 50 WHERE THERE IS DIFLUENT FLOW ALOFT AND
THE BEST DYNAMICS AND LIFT. HEAVY RAIN IS THE GREATEST CONCERN
WEDNESDAY AND THURSDAY AS PRECIPITABLE WATER VALUES REMAIN AT
0.8-1.0 INCH. WHILE STORM MOTIONS DO INCREASE BY THURSDAY, TRAINING
AND/OR BACK BUILDING STORMS COULD STILL PRODUCE AREAS OF HEAVY RAIN.
HAIL AND GUSTY OUTFLOW WINDS ARE ALSO POSSIBLE.
DRY AND STABLE SOUTHWEST FLOW RESULTS ACROSS THE AREA BEHIND THE
EXITING LOW, ENDING ALL THUNDERSTORM CHANCES THROUGH THE WEEKEND AND
KEEPING SKIES MOSTLY CLEAR. BREEZY AFTERNOON WINDS ARE EXPECTED EACH
DAY, BUT GUSTS SHOULD BE AT OR BELOW 30 MPH. TEMPERATURES WILL BE
SLIGHTLY BELOW NORMAL WEDNESDAY AND THURSDAY, ESPECIALLY ACROSS
NORTHEAST CALIFORNIA CLOSER TO THE CORE OF THE LOW. HIGHS WILL
REBOUND TO NEAR NORMAL FOR THE WEEKEND. DJ
&&
.AVIATION...
CONVECTIVE TOWERS HAVE DEVELOPED THIS AFTERNOON ALONG THE SIERRA
CREST SOUTH OF LAKE TAHOE. THE BEST CHANCE OF STORMS THROUGH 00Z
WILL BE AT KMMH, KTRK AND KTVL. THE MAIN THREATS FROM ANY STORMS
THAT FORM WILL BE ERRATIC AND GUSTY WINDS, LOCALLY HEAVY RAIN AND
SMALL HAIL. A COMPLEX OF SHOWERS AND THUNDERSTORMS MAY LIFT
NORTHWEST ACROSS WESTERN NEVADA BETWEEN 00-09Z IMPACTING KCXP AND
KRNO, BUT CONFIDENCE IN TIMING AND LOCATION AT THIS TIME IS LOW.
SMOKE FROM THE BRUNSWICK FIRE TO THE EAST OF CARSON CITY MAY
REDUCE SLANTWISE VISIBILITIES AT KCXP AND KRNO THROUGH THIS
EVENING.
THUNDERSTORM CHANCES INCREASE AT ALL TERMINALS ON MONDAY AND
TUESDAY AS A SLOW MOVING AREA OF LOW PRESSURE REMAINS PARKED OFF
THE CENTRAL CALIFORNIA COAST WITH DEEP MOISTURE IN PLACE ACROSS
THE SIERRA AND WESTERN NEVADA. MYRICK
&&
.REV WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
CA...NONE.
&&
$$
FOR MORE INFORMATION FROM THE NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/RENO (ALL LOWER CASE)
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1027 AM MDT SUN AUG 18 2013
.UPDATE...UPPER LEVEL RIDGE WILL BRING ANOTHER VERY WARM DAY TO
THE AREA. THE TAIL END OF A SHORT WAVE TROUGH MOVING ACROSS THE
NORTHERN ROCKIES AND NORTHERN PLAINS WITH PRODUCE SOME LIFT OVER
THE AREA THIS AFTERNOON AND EVENING. AIRMASS IS STILL ON THE DRY
SIDE...BUT MOISTURE HAS INCREASED. THE 12Z SATURDAY SOUNDING AT
GRAND JUNCTION SHOWED 0.40 OF AN INCH WHILE TODAY`S 12Z SOUNDING
SHOWED 0.82. THIS INCREASE IN MOISTURE WILL RESULT MORE CONVECTION
OVER THE MOUNTAINS TODAY. CAPES STILL LESS THAN 500 J/KG ALONG THE
FRONT RANGE AND OVER THE MOUNTAINS. SO ANY CONVECTION THAT FORMS
SHOULD BE HIGH BASED AND WEAK WITH GUSTY OUTFLOW WINDS BEING THE
MAIN CONCERN.
OVER THE EASTERN PLAINS...WHERE LOW LEVEL MOISTURE WILL BE
GREATER. DEW POINTS WILL BE IN THE 50S TO LOWER 60S. THIS WILL
LEAD TO CAPES OF 1000-2000 J/KG. AIRMASS WILL LIKELY BE
CAPPED...ESPECIALLY OVER FAR EASTERN COLORADO AND EASTWARD.
SOUTHEAST WINDS WILL INCREASE THIS AFTERNOON. THESE SOUTHEAST
WINDS COMBINED WITH NORTHWEST WINDS ALOFT MAY PRODUCE ENOUGH
SHEAR FOR A COUPLE OF SEVERE STORMS. THE AREA OF BEST INSTABILITY
AND SHEAR WILL BE EAST OF A LINE FROM FORT MORGAN TO LIMON. WILL
MENTION A SEVERE THREAT IN THE HAZARDOUS WEATHER OUTLOOK. COVERAGE
OF STORMS WILL BE ISOLATED BECAUSE OF A CAP IN PLACE...BUT SHOULD
BE ABLE TO BREAK IN A FEW SPOTS BECAUSE OF THE SHORT WAVE TROUGH
AND CONVERGENCE ALONG OUTFLOW BOUNDARIES.
&&
.AVIATION...LIGHT WINDS THIS MORNING WILL TURN EASTERLY THIS
AFTERNOON. SCATTERED THUNDERSTORMS OVER THE HIGHER TERRAIN WILL
PUSH OUTFLOW WINDS ACROSS THE DENVER LATE THIS AFTERNOON AND MAY
CAUSE WIND TO SHIFT WESTERLY FOR A SHORT TIME. JUST A SLIGHT
CHANCE FOR A THUNDERSTORMS AT THE DENVER AIRPORTS WITH A SLIGHTLY
BETTER CHANCE OVER THE EASTERN PLAINS. VARIABLE WINDS WILL BE
POSSIBLE 21-03Z BECAUSE OF OUTFLOW FROM THUNDERSTORMS. EVENTUALLY
WINDS WILL SETTLE SOUTHERLY BY 06Z.
&&
.PREV DISCUSSION... /ISSUED 357 AM MDT SUN AUG 18 2013/
SHORT TERM...ONCE AGAIN SOME STRATUS AND FOG WERE DEVELOPING OVER
THE NERN PLAINS EARLY THIS MORNING. A WELL DEFINED DENVER CYCLONE
WAS OVER SWRN WELD COUNTY AND WILL LIKELY PULL SOME OF THIS
STRATUS BACK WESTWARD ACROSS MUCH OF WELD COUNTY BY 12Z. APPEARS
THE LOW CLOUDS WILL LINGER THRU THE LATE MORNING HOURS ACROSS THE
NERN PLAINS BEFORE BREAKING UP BY 18Z.
FOR THIS AFTN AN UPPER LEVEL RIDGE WILL BE OVER THE AREA WITH WEAK
MID LVL FLOW. THERE WILL BE AN INCREASE IN SUBTROPICAL MOISTURE
WITH PRECIPITABLE WATER SLOWLY RISING. OVERALL INSTABILITY IS NOT
THAT UNSTABLE ACROSS THE HIGHER TERRAIN AND FRONT RANGE WHERE CAPES
WILL BE BLO 500 J/KG. OVER THE NERN PLAINS CAPES WILL BE BETTER
WITH VALUES RANGING FM 1500-2000 J/KG. WILL SEE SOME HIGH BASED
SHOWER AND TSTM ACTIVITY OVER THE HIGHER TERRAIN WITH OUTFLOW
BOUNDARIES TRIGGERING STRONGER STORMS OVER THE PLAINS WHERE
INSTABILITY WILL BE BETTER. AS FOR HIGHS 850-700 MB TEMPS WOULD
SUPPORT READINGS IN THE LOW TO MID 90S OVER NERN CO WITH A FEW UPPER
90S POSSIBLE ALONG THE FRONT RANGE.
BY TONIGHT TSTM ACTIVITY SHOULD GRADUALLY END IN THE EARLY EVENING
HOURS. MAY SEE SOME REDEVELOP OF STRATUS AND FOG OVER THE NERN
PLAINS AFTER MIDNIGHT.
LONG TERM...MODELS SHOW LITTLE MOVEMENT IN THE STRONG UPPER
LEVEL RIDGE CENTERED JUST EAST OF THE CONTINENTAL DIVIDE ON
MONDAY DURING THE UPCOMING WEEK. ALTHOUGH 500MB HEIGHTS ARE
PROGGED TO GRADUALLY LOWER LATER IN THE WEEK AS THE SWIFT ZONAL
FLOW UP ALONG THE U.S./CANADIAN BORDER DIPS SOUTH AS THE CUTOFF
LOW NOW OFF THE CALIFORNIA COAST FILLS AND EJECTS NEWRD OVER THE
NRN ROCKIES BY FRIDAY. THIS WOULD CAUSE TEMPERATURES LOCALLY TO
MODERATE SOME...GOING FROM ABOVE AVERAGE ON MONDAY-WEDNESDAY TO
BELOW AVERAGE BY THE WEEKEND. A PERSISTENT ALBEIT LIGHT
SOUTHWESTERLY 700-500MB FLOW WILL CONTINUE TO ADVECT MINOR WAVES
OF MOIST UNSTABLE SUBTROPICAL AIR UP OVER WESTERN COLORADO
BENEATH THE UPPER RIDGE DURING THE UPCOMING WEEK. THIS WILL RESULT
IN DAILY ROUNDS OF ISOLATED TO SCATTERED T-STORMS PRIMARILY ALONG
AND WEST OF THE CONTINENTAL DIVIDE. LIGHT STEERING WINDS AND
GRADUALLY HIGHER PRECIPITABLE WATER VALUES MAY RESULT IN LOCALLY
HEAVY RAINFALL FROM THESE SLOW MOVING STORM CELLS. EAST OF THE
MOUNTAINS...ATMOSPHERE APPEARS QUITE DRY AND CAPPED FOR MUCH OF
THE WEEK RESULTING IN LITTLE IF ANY T-STORM DEVELOPMENT. HOWEVER
ON WEDNESDAY...MODELS DO SHOW AN INCREASE IN DEWPOINTS AND PW
VALUES ON THE PLAINS WITH THE PASSAGE OF A WEAK 700-500MB
SHORTWAVE TROUGH. AT PRESENT TIME...DO NOT HAVE ANY T-STORMS IN
THE FCST FOR WEDNESDAY EAST OF THE MTNS WITH QUITE ABIT OF CIN
AROUND. HOWEVER SHOULD THE MODELS CONTINUE TO INDICATE THIS
INCREASE IN LOW/MID-LEVEL MOISTURE WITH EACH RUN...WILL PROBABLY
NEED TO ADD AT LEAST A SLIGHT CHANCE OF AFTERNOON/EVENING STORMS
FOR THE PLAINS WEDNESDAY AFTERNOON AND EVENING.
AVIATION...DENVER CYCLONE WAS OVER SWRN WELD COUNTY AND IS FCST
TO STAY OVER SRN WELD THIS MORNING. LATEST HRRR KEEPS THE STRATUS
AND FOG TO THE NORTH AND NE OF DIA AS SFC WINDS STAY WSW SO WILL
KEEP OUT OF THE TAF. BY EARLY AFTN WINDS WILL BECOME LIGHT ENE
HOWEVER OUTFLOW BOUNDARIES FM HIGH BASED CONVECTION OVER THE
FOOTHILLS MAY TRACK ACROSS IN THE 21Z-23Z TIME FRAME WITH WINDS
SHIFTING TO THE NW WITH SPEEDS IN THE 10-20 MPH RANGE. AT THIS
TIME LOOKS LIKE TSTMS WILL STAY MOSTLY TO EAST SO WILL ONLY
MENTION VCTS. BY THIS EARLY THIS EVENING WINDS WILL BECOME WSW AND
THEN SSW BY 06Z.
HYDROLOGY...WIDELY SCATTERED THUNDERSTORMS WILL DEVELOP THIS
AFTERNOON HOWEVER RAINFALL AMOUNTS SHOULD BE UNDER ONE QUARTER
INCH IF THEY MOVE OVER THE BURN AREAS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....BAKER
UPDATE/AVIATION...MEIER
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
357 AM MDT SUN AUG 18 2013
.SHORT TERM...ONCE AGAIN SOME STRATUS AND FOG WERE DEVELOPING OVER
THE NERN PLAINS EARLY THIS MORNING. A WELL DEFINED DENVER CYCLONE
WAS OVER SWRN WELD COUNTY AND WILL LIKELY PULL SOME OF THIS
STRATUS BACK WESTWARD ACROSS MUCH OF WELD COUNTY BY 12Z. APPEARS
THE LOW CLOUDS WILL LINGER THRU THE LATE MORNING HOURS ACROSS THE
NERN PLAINS BEFORE BREAKING UP BY 18Z.
FOR THIS AFTN AN UPPER LEVEL RIDGE WILL BE OVER THE AREA WITH WEAK
MID LVL FLOW. THERE WILL BE AN INCREASE IN SUBTROPICAL MOISTURE
WITH PRECIPITABLE WATER SLOWLY RISING. OVERALL INSTABILITY IS NOT
THAT UNSTABLE ACROSS THE HIGHER TERRAIN AND FRONT RANGE WHERE CAPES
WILL BE BLO 500 J/KG. OVER THE NERN PLAINS CAPES WILL BE BETTER
WITH VALUES RANGING FM 1500-2000 J/KG. WILL SEE SOME HIGH BASED
SHOWER AND TSTM ACTIVITY OVER THE HIGHER TERRAIN WITH OUTFLOW
BOUNDARIES TRIGGERING STRONGER STORMS OVER THE PLAINS WHERE
INSTABILITY WILL BE BETTER. AS FOR HIGHS 850-700 MB TEMPS WOULD
SUPPORT READINGS IN THE LOW TO MID 90S OVER NERN CO WITH A FEW UPPER
90S POSSIBLE ALONG THE FRONT RANGE.
BY TONIGHT TSTM ACTIVITY SHOULD GRADUALLY END IN THE EARLY EVENING
HOURS. MAY SEE SOME REDEVELOP OF STRATUS AND FOG OVER THE NERN
PLAINS AFTER MIDNIGHT.
.LONG TERM...MODELS SHOW LITTLE MOVEMENT IN THE STRONG UPPER
LEVEL RIDGE CENTERED JUST EAST OF THE CONTINENTAL DIVIDE ON
MONDAY DURING THE UPCOMING WEEK. ALTHOUGH 500MB HEIGHTS ARE
PROGGED TO GRADUALLY LOWER LATER IN THE WEEK AS THE SWIFT ZONAL
FLOW UP ALONG THE U.S./CANADIAN BORDER DIPS SOUTH AS THE CUTOFF
LOW NOW OFF THE CALIFORNIA COAST FILLS AND EJECTS NEWRD OVER THE
NRN ROCKIES BY FRIDAY. THIS WOULD CAUSE TEMPERATURES LOCALLY TO
MODERATE SOME...GOING FROM ABOVE AVERAGE ON MONDAY-WEDNESDAY TO
BELOW AVERAGE BY THE WEEKEND. A PERSISTENT ALBEIT LIGHT
SOUTHWESTERLY 700-500MB FLOW WILL CONTINUE TO ADVECT MINOR WAVES
OF MOIST UNSTABLE SUBTROPICAL AIR UP OVER WESTERN COLORADO
BENEATH THE UPPER RIDGE DURING THE UPCOMING WEEK. THIS WILL RESULT
IN DAILY ROUNDS OF ISOLATED TO SCATTERED T-STORMS PRIMARILY ALONG
AND WEST OF THE CONTINENTAL DIVIDE. LIGHT STEERING WINDS AND
GRADUALLY HIGHER PRECIPITABLE WATER VALUES MAY RESULT IN LOCALLY
HEAVY RAINFALL FROM THESE SLOW MOVING STORM CELLS. EAST OF THE
MOUNTAINS...ATMOSPHERE APPEARS QUITE DRY AND CAPPED FOR MUCH OF
THE WEEK RESULTING IN LITTLE IF ANY T-STORM DEVELOPMENT. HOWEVER
ON WEDNESDAY...MODELS DO SHOW AN INCREASE IN DEWPOINTS AND PW
VALUES ON THE PLAINS WITH THE PASSAGE OF A WEAK 700-500MB
SHORTWAVE TROUGH. AT PRESENT TIME...DO NOT HAVE ANY T-STORMS IN
THE FCST FOR WEDNESDAY EAST OF THE MTNS WITH QUITE ABIT OF CIN
AROUND. HOWEVER SHOULD THE MODELS CONTINUE TO INDICATE THIS
INCREASE IN LOW/MID-LEVEL MOISTURE WITH EACH RUN...WILL PROBABLY
NEED TO ADD AT LEAST A SLIGHT CHANCE OF AFTERNOON/EVENING STORMS
FOR THE PLAINS WEDNESDAY AFTERNOON AND EVENING.
&&
.AVIATION...DENVER CYCLONE WAS OVER SWRN WELD COUNTY AND IS FCST
TO STAY OVER SRN WELD THIS MORNING. LATEST HRRR KEEPS THE STRATUS
AND FOG TO THE NORTH AND NE OF DIA AS SFC WINDS STAY WSW SO WILL
KEEP OUT OF THE TAF. BY EARLY AFTN WINDS WILL BECOME LIGHT ENE
HOWEVER OUTFLOW BOUNDAIRES FM HIGH BASED CONVECTION OVER THE
FOOTIHLLS MAY TRACK ACROSS IN THE 21Z-23Z TIMEFRAME WITH WINDS
SHIFTING TO THE NW WITH SPEEDS IN THE 10-20 MPH RANGE. AT THIS
TIME LOOKS LIKE TSTMS WILL STAY MOSTLY TO EAST SO WILL ONLY
MENTION VCTS. BY THIS EARLY THIS EVENING WINDS WILL BECOME WSW AND
THEN SSW BY 06Z.
&&
.HYDROLOGY...WIDELY SCATTERED THUNDERSTORMS WILL DEVELOP THIS
AFTERNOON HOWEVER RAINFALL AMOUNTS SHOULD BE UNDER ONE QUARTER
INCH IF THEY MOVE OVER THE BURN AREAS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....BAKER
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
558 AM EDT Sun Aug 18 2013
...UPDATED FOR HIGH RISK OF RIP CURRENTS AND RAIN TOTALS...
...UPDATED FOR ISSUANCE OF FLASH FLOOD WATCH FOR FLORIDA PANHANDE...
.UPDATE...
Overall, models have a poor handle on this current scenario.
Unfortunately, our 18/06z hi-res ARW mentioned earlier in the near
term section did not run due to technical difficulties. The decision
has been made to issue a flash flood watch for today for the Florida
zones west of the Apalachicola River. The watch was primarily based
on the following factors.
1) Radar shows moderate rain already entering Walton county, and
this area experience flooding yesterday. There is some extremely
heavy rain offshore of Walton county by about 65 miles gradually
inching eastward. The ground is saturated and flash flood guidance
is likely too high in some of the watch area, especially Walton
County.
2) There appears to be a warm frontal boundary situated just inland
from the coast. This could serve as a focus for convection later
this afternoon across already saturated areas.
3) Several of the recent HRRR runs show a scenario similar to 2)
happening, although they differ on the locations. In fact, some of
the runs show areas farther to the east around Tallahassee getting
some hefty totals today, but confidence is not yet high enough to
expand the watch beyond what is being issued, although trends will
have to be monitored closely.
Overall, this is a low confidence forecast. It would not be
surprising to see either the watch expanded later today, or perhaps
canceled early.
&&
.NEAR TERM [Through Today]...
The main concern for today is the potential for additional flooding.
We are watching with interest a fairly well defined MCS moving
northeastward south of Mobile this morning. Some of the models may
be having some trouble with this feature as the NAM appears to be on
the weak side and our local 18/00z ARW run does not see this feature
very well (uses 00z NAM boundary conditions). The 18/00z GFS does
see this feature, but based on recent satellite/radar trends, it may
be just a tad too far west with its axis of heaviest precip
associated with it. This raises some concern about the potential for
additional flash flooding over the western portions of the forecast
area today due to low flash flood guidance values if this feature
moves just slightly more to the east. There is also ongoing areal
flooding in Walton county, so flash flood guidance values are
probably overdone in that county by quite a bit.
The plan of action right now is to observe the trends in the MCS on
satellite/radar over the next few hours and wait for some additional
pieces of hi-res guidance to come in before making a decision about
whether or not to re-issue the flash flood watch over the western
areas. From a model perspective, the trends in the HRRR as well as
our local 18/06z ARW run will be important as our 06z ARW uses the
00z GFS for boundary conditions and may have a better handle on this
feature than our 00z run.
Persistent moderate onshore flow with higher gusts continues to
generate a high risk for rip currents for Walton...Bay and to a
lesser extent Gulf counties thru this eve.
&&
.SHORT TERM [Tonight through Tuesday]...
The large scale pattern continues to shift tonight. This is
highlighted by ridging over west half of Conus, Ern trough lifting
Newd with low opening up into OH Valley, and deep layer Atlc ridge
building WSW in its place into SE states. At surface, building
ridge aids in weakening quasi-stnry front and nudging it Nwd ending
its local focus for showers and thunderstorms. Low level flow also
begins to back to ESE. With low over Wrn Gulf, and trough axis
still to our west, and tropical moisture plume barely out of our
area, a good chance of post sundown convection across Wrn waters
and adjacent coast, Also, reinvigorated east coast sea breeze may
cross I-75 keep convection in Ern counties past sunset.
During the rest of the period, Ern trough lifts further Newd and
flattens out. This allows Wrn and Atlc ridges to advance Ewd and Wwd
respectively bridging by end of period cutting off tropical plume
and progressively diminishing depth of moisture column depth but
ridge not strong enough to suppress convection. This shifts
steering flow to deepening ELY. By Tues, front has largely
dissipated with surface high anchored over NE SC/NW GA thus we
transition to a more typical summertime pattern with Gulf and Atlc
seabreeze/ mesoscale boundary generated aftn and eve convection.
With PWATS remaining above 2 inches thru the period, expect a good
chance of convection each day and any seabreeze/ boundary clashes
could ignite strong to isold severe storms.
Will go with 30-50% NE-SW POP gradient tonight, 30-60% SE-NW on
Mon and 30-50% SE-NW on Tues. Min temps in low 70s tonight. Highs
Mon and Tues return to near climo with upper 80s NW to low 90s SE
with Max hear indices around 100 degrees.
&&
.LONG TERM [Tuesday Night through Saturday]...
Southeast low-level flow gradually backs to more of an easterly
direction as an upper level ridge builds into the region. This
should equate to more suppressed convective activity with time,
and overall PoPs show a decreasing trend through the extended
forecast. However, there should still be daily thunderstorm
chances. Temperatures will be closer to normal, perhaps warming to
slightly above normal by later in the week.
&&
.MARINE...
Local waters remain between ridge to our NE and weak area of low
pressure to our SW. this will keep winds and especially seas
elevated today. Introduced exercise caution for seas Wrn waters
thru this eve. Thereafter, expect light to moderate southeast
then east winds along with decreasing seas thru at least Thursday.
&&
.AVIATION...
[Through 06z Monday] MVFR to IFR conditions are expected to develop
during the early morning hours this morning. Another round of
convection is expected across the area later today, most likely at
KDHN and KECP.
&&
.FIRE WEATHER...
There are currently no fire weather concerns with moist conditions
in place.
&&
HYDROLOGY...
During the last 24hrs (thru 5am EDT)...ample rain fell with the
focus across the Florida Panhandle. This is reflected in the
following MESONET sites (in inches)
Southport 5.10 Panama City 4.45 and 3.56
Destin 3.84 Pan Cty Beach 3.06
Marianna 3.40 Chipley 4.06
Several local river systems have had (or will soon have) notable
rises and increased flows, except for perhaps the far southeast part
of our area in Taylor, Lafayette, and Dixie counties. The rivers, as
of a week ago, were running at lower levels than what we had seen
for most of July, so it has taken a considerable amount of rain to
move some to even a bankfull status. The next few river model runs
should be able to focus on the main threat areas, since these models
will have a more complete picture of the area rainfall the past few
days. A few rivers that may be particularly at risk include:
Choctawhatchee, Shoal, Apalachicola.
The most up to date, specific river forecast information can be
found on the AHPS web page at:
http:/water.weather.gov/ahps2/index.php?wfo=tae.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 89 73 91 73 91 / 60 30 50 30 40
Panama City 87 76 88 76 87 / 70 40 50 30 50
Dothan 86 72 89 72 90 / 70 40 60 30 50
Albany 87 72 90 72 91 / 70 30 60 40 50
Valdosta 89 72 91 72 92 / 60 30 50 40 40
Cross City 90 72 91 72 92 / 60 30 40 40 30
Apalachicola 86 77 86 77 86 / 60 40 50 30 40
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...HIGH RIP CURRENT RISK thru this Eve Walton...Bay and Gulf.
FLASH FLOOD WATCH Panhandle.
GA...None.
AL...None.
GM...None.
&&
$$
AVIATION/FIRE WX/NEAR TERM...DVD
HYDROLOGY...Block
Long Term...Lamers/Moore
Short Term/Marine...Block
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
455 AM EDT SUN AUG 18 2013
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS STILL SHOW AN AMPLIFIED UPPER
LEVEL PATTERN ACROSS THE EASTERN CONUS HIGHLIGHTED BY DEEP TROUGHING
ALONG AND JUST TO THE EAST OF THE MS RIVER VALLEY. SYNOPTIC
INFLUENCE FROM THIS FEATURE WILL RESULT IN THE POTENTIAL FOR SOME
VERY HEAVY RAINFALL ALONG THE NORTH-CENTRAL GULF COAST OVER THE NEXT
24 HOURS. HOWEVER...THIS ORGANIZED RAINFALL BANDING WILL BE HELD TO
OUR NORTHWEST BY A PROTECTIVE UPPER RIDGE THAT IS NOW IN PLACE OVER
THE FL PENINSULA. CLOSER TO THE SURFACE...THE RIDGE AXIS IS LOCATED
WELL TO OUR NORTH PROVIDING THE REGION WITH AN EAST TO SOUTHEAST
GRADIENT FLOW THAT WILL BE WITH US THROUGH THE EARLY PORTION OF THE
WEEK.
REGIONAL RADARS HAVE QUIETED DOWN CONSIDERABLY DURING THE PAST
SEVERAL HOURS WITH JUST A FEW TYPICAL NOCTURNAL MARINE SHOWERS WELL
OFFSHORE. THE RADAR SHOULD REMAIN ON THE QUIET SIDE THROUGH THE
MORNING HOURS OVER THE LAND MASS...HOWEVER THE INGREDIENTS ARE THERE
FOR ANOTHER ACTIVE THUNDERSTORM PATTERN ALONG THE FL WEST COAST
LATER THIS AFTERNOON AND EVENING. MORE ON THIS POTENTIAL IN THE
SHORT TERM DISCUSSION BELOW.
&&
.SHORT TERM (TODAY THROUGH TUESDAY)...
TODAY/TONIGHT...THE FINAL DAY OF THE WEEKEND WILL FEATURE GENERALLY
QUIET CONDITIONS FOR THE MORNING HOURS AS TEMPERATURES CLIMB TOWARD
THE LOWER 90S THROUGH A MIX OF SUN AND CLOUDS. THE LOW LEVEL
SYNOPTIC PATTERN WILL FEATURE EASTERLY FLOW THAT HAS BEEN A
RECURRING THEME THIS SUMMER AND IS THE FAVORED FLOW FOR AN ACTIVE
THUNDERSTORM PATTERN ALONG THE I-75 CORRIDOR DURING THE LATE
AFTERNOON AND EVENING HOURS. THERE MAY BE JUST ENOUGH BOUNDARY LAYER
FLOW TO KEEP ANY FEEBLE WEST COAST SEA-BREEZE FROM MOVING
INLAND...HOWEVER AT THE VERY LEAST WE WILL SEE A PARTIAL COLLAPSE OF
THE WIND FIELDS THIS AFTERNOON OVER THE NEARSHORE WATERS. THIS LACK
OF WIND WILL SET UP A SPEED CONVERGENCE ZONE NEAR THE COAST AND
SHOULD BE ENOUGH TO FORCE SCT-NMRS SHOWERS AND STORMS AFTER 3-4PM.
STORMS SHOULD GET GOING FIRST (EARLY TO MID AFTERNOON) OVER THE
SOUTHERN AND SOUTH-CENTRAL INTERIOR ZONES IN A SCT NATURE AND THEN
PROGRESS WEST AND NORTHWEST TOWARD THE TAMPA BAY AREA LATE IN THE
DAY (LATE AFTERNOON AND EARLY EVENING). IT WILL BE DURING THIS LATE
DAY / EVENING TIME FRAME THAT THE STORMS SHOULD BECOME MORE NMRS IN
NATURE. HAVE GONE WITH LIKELY 60% POPS ALONG THE ENTIRE I-75
CORRIDOR...HOWEVER...BASED ON THE LATEST HI-RESOLUTION CONVECTION
ALLOWING GUIDANCE SUITE...EVEN THIS COVERAGE MAY BE ON THE
CONSERVATIVE SIDE. GUIDANCE ALSO IS IN GOOD AGREEMENT THAT THE
ACTIVITY WILL LINGER WELL INTO THE EVENING...ESPECIALLY FOR THE
COASTAL ZONES. THIS IS AGAIN FAIRLY TYPICAL FOR THIS SYNOPTIC SETUP.
FINALLY AFTER 11 PM OR SO...WE SHOULD SEE THE LAST OF THE STORMS
DISSIPATE OR MOVE OFFSHORE...LEAVING THE LAND ZONES WITH A GENERALLY
DRY FORECAST FOR THE SECOND HALF OF THE NIGHT.
BOTTOM LINE...ANYONE WITH OUTDOOR OR TRAVEL PLANS ALONG THE I-75
CORRIDOR OR WITH NEAR SHORE BOATING PLANS FOR THE LATE DAY / EVENING
HOURS SHOULD BE PREPARED FOR RAPIDLY DEVELOPING CLUSTERS OF
STORMS.
MONDAY/TUESDAY...
OVERALL SYNOPTIC PATTERN CHANGES LITTLE FOR THE FIRST TWO DAYS OF
THE WORK WEEK. THE RIDGE ALOFT HOLDS POSITION...BUT NOT STRONG
ENOUGH TO SIGNIFICANTLY SUPPRESS CONVECTION...AND THE SURFACE RIDGE
POSITION KEEPS OUR FLOW FROM THE EAST. THE ONLY CHANGE IS A SLIGHT
DECREASE IN COLUMN MOISTURE INTO MONDAY AND EVEN A BIT MORE ON
TUESDAY. TOUGH TO SAY IF THIS LOSS OF MOISTURE WILL BE ENOUGH TO
SLOW THE STILL FAVORABLE FLOW PATTERN FOR WEST COAST THUNDERSTORMS.
BEST GUESS IS THAT THE COLUMN WILL NOT DRY OUT ENOUGH TO SUPPRESS
CONVECTIVE COVERAGE AND CONSIDERED GOING WITH LIKELY POPS BOTH DAYS
DURING THE LATE AFTERNOON / EVENING. FOR NOW...KEPT THE LIKELY POPS
ALONG THE SUNCOAST ON MONDAY WITH HIGH END CHANCE (50-55%) RAIN
CHANCES FOR TAMPA BAY AND THE NATURE COAST...THEN HELD POPS AROUND
50% FOR ALL ON TUESDAY. COVERAGE COULD CERTAINLY BE HIGHER THAN
CURRENTLY FORECAST...ESPECIALLY ON MONDAY. THE NEXT SHIFT CAN TAKE
A CLOSER LOOK AT THE MOISTURE FIELDS IN THE NEXT MODEL CYCLE OR TWO
AND ADJUST UPWARDS IF NECESSARY.
&&
.LONG TERM (WEDNESDAY THROUGH NEXT SATURDAY)...
AN UPPER LEVEL RIDGE ACROSS FL FROM THE ATLANTIC WILL SLOWLY WEAKEN
THROUGH FRI AS AN UPPER LEVEL TROUGH MOVES FROM THE MIDWEST TO THE
SOUTHEAST U.S. THIS TROUGH CONTINUES EASTWARD ON SAT TO THE EASTERN
SEABOARD. AT THE SURFACE HIGH PRESSURE CENTERED OVER THE OPEN
ATLANTIC IN THE VICINITY OF 30 TO 35 NORTH LATITUDE RIDGES WEST TO
THE GULF COASTAL STATES THROUGH THE PERIOD...WITH A PREVAILING
EASTERLY/SOUTHEASTERLY BOUNDARY LAYER FLOW ACROSS THE AREA.
EXPECT A GENERAL SUMMERTIME PATTERN EACH DAY WITH SCATTERED TO
NUMEROUS MAINLY AFTERNOON THUNDERSTORMS. THE EAST AND SE FLOW WILL
KEEP THE WEST COAST SEA BREEZE CLOSE TO THE COAST FOR THE FIRST
COUPLE OF DAYS WITH THE HIGHEST COVERAGE OVER COASTAL COUNTIES.
THE EAST/SE FLOW WEAKENS SOME FOR THE END OF THE WEEK AND ALLOWS THE
WEST COAST SEA BREEZE TO PUSH SLIGHTLY FURTHER INLAND WITH MORE
UNIFORM COVERAGE AREA WIDE. TEMPERATURES RUN ABOVE NORMAL BY UP TO 1
TO 3 DEGREES.
&&
.AVIATION...
VFR CONDITIONS THROUGH MORNING WITH LIGHT VARIABLE/EASTERLY WINDS.
VFR CONTINUES ALTHOUGH TSRA MAY BEGIN TO IMPACT THE TERMINALS IN THE
AFTERNOON AND EARLY EVENING. WINDS BECOMES SE AND INCREASE SLIGHTLY
DURING THE MORNING THEN SHIFT TO ONSHORE DURING THE AFTERNOON.
&&
.MARINE...
THE RIDGE AXIS WILL REMAIN TO THE NORTH OF THE FORECAST WATERS
THROUGH THE EARLY PORTION OF THE WEEK. THIS POSITION WILL KEEP A
PERSISTENT EAST TO SOUTHEAST FLOW IN PLACE OVER THE FORECAST WATERS.
BEST CHANCES FOR THUNDERSTORMS WILL BE IN THE EARLY MORNING
HOURS...AND THEN AGAIN LATE IN THE AFTERNOON AND EVENING AS STORMS
MOVE EAST TO WEST OFFSHORE.
&&
.FIRE WEATHER...
THE SURFACE RIDGE AXIS TO OUR NORTH WILL KEEP A PERSISTENT EAST TO
SOUTHEAST FLOW GOING ACROSS THE FLORIDA PENINSULA THROUGH THE EARLY
PORTION OF THE WEEK. THIS EASTERLY FLOW WILL RESULT IN SEVERAL DAYS
OF ACTIVE AFTERNOON AND EVENING THUNDERSTORMS...ESPECIALLY ALONG THE
I-75 CORRIDOR. RELATIVE HUMIDITY VALUES ARE EXPECTED TO REMAIN WELL
ABOVE CRITICAL LEVELS AND NO SIGNIFICANT FIRE WEATHER CONCERNS ARE
IN THE FORECAST.
FOG POTENTIAL...NO SIGNIFICANT FOG IS EXPECTED THROUGH THE EARLY
PART OF THE WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 91 77 92 79 / 60 50 50 40
FMY 91 76 93 77 / 60 40 60 30
GIF 92 74 94 74 / 50 20 50 20
SRQ 91 76 93 76 / 60 60 60 40
BKV 91 73 93 74 / 60 50 50 40
SPG 90 79 91 80 / 60 60 50 40
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...RUDE
AREA FORECAST DISCUSSION...RESENT
NWS TAMPA BAY RUSKIN FL
445 AM EDT SUN AUG 18 2013
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS STILL SHOW AN AMPLIFIED UPPER
LEVEL PATTERN ACROSS THE EASTERN CONUS HIGHLIGHTED BY DEEP TROUGHING
ALONG AND JUST TO THE EAST OF THE MS RIVER VALLEY. SYNOPTIC
INFLUENCE FROM THIS FEATURE WILL RESULT IN THE POTENTIAL FOR SOME
VERY HEAVY RAINFALL ALONG THE NORTH-CENTRAL GULF COAST OVER THE NEXT
24 HOURS. HOWEVER...THIS ORGANIZED RAINFALL BANDING WILL BE HELD TO
OUR NORTHWEST BY A PROTECTIVE UPPER RIDGE THAT IS NOW IN PLACE OVER
THE FL PENINSULA. CLOSER TO THE SURFACE...THE RIDGE AXIS IS LOCATED
WELL TO OUR NORTH PROVIDING THE REGION WITH AN EAST TO SOUTHEAST
GRADIENT FLOW THAT WILL BE WITH US THROUGH THE EARLY PORTION OF THE
WEEK.
REGIONAL RADARS HAVE QUIETED DOWN CONSIDERABLY DURING THE PAST
SEVERAL HOURS WITH JUST A FEW TYPICAL NOCTURNAL MARINE SHOWERS WELL
OFFSHORE. THE RADAR SHOULD REMAIN ON THE QUIET SIDE THROUGH THE
MORNING HOURS OVER THE LAND MASS...HOWEVER THE INGREDIENTS ARE THERE
FOR ANOTHER ACTIVE THUNDERSTORM PATTERN ALONG THE FL WEST COAST
LATER THIS AFTERNOON AND EVENING. MORE ON THIS POTENTIAL IN THE
SHORT TERM DISCUSSION BELOW.
&&
.SHORT TERM (TODAY THROUGH TUESDAY)...
TODAY/TONIGHT...THE FINAL DAY OF THE WEEKEND WILL FEATURE GENERALLY
QUIET CONDITIONS FOR THE MORNING HOURS AS TEMPERATURES CLIMB TOWARD
THE LOWER 90S THROUGH A MIX OF SUN AND CLOUDS. THE LOW LEVEL
SYNOPTIC PATTERN WILL FEATURE EASTERLY FLOW THAT HAS BEEN A
RECURRING THEME THIS SUMMER AND IS THE FAVORED FLOW FOR AN ACTIVE
THUNDERSTORM PATTERN ALONG THE I-75 CORRIDOR DURING THE LATE
AFTERNOON AND EVENING HOURS. THERE MAY BE JUST ENOUGH BOUNDARY LAYER
FLOW TO KEEP ANY FEEBLE WEST COAST SEA-BREEZE FROM MOVING
INLAND...HOWEVER AT THE VERY LEAST WE WILL SEE A PARTIAL COLLAPSE OF
THE WIND FIELDS THIS AFTERNOON OVER THE NEARSHORE WATERS. THIS LACK
OF WIND WILL SET UP A SPEED CONVERGENCE ZONE NEAR THE COAST AND
SHOULD BE ENOUGH TO FORCE SCT-NMRS SHOWERS AND STORMS AFTER 3-4PM.
STORMS SHOULD GET GOING FIRST (EARLY TO MID AFTERNOON) OVER THE
SOUTHERN AND SOUTH-CENTRAL INTERIOR ZONES IN A SCT NATURE AND THEN
PROGRESS WEST AND NORTHWEST TOWARD THE TAMPA BAY AREA LATE IN THE
DAY (LATE AFTERNOON AND EARLY EVENING). IT WILL BE DURING THIS LATE
DAY / EVENING TIME FRAME THAT THE STORMS SHOULD BECOME MORE NMRS IN
NATURE. HAVE GONE WITH LIKELY 60% POPS ALONG THE ENTIRE I-75
CORRIDOR...HOWEVER...BASED ON THE LATEST HI-RESOLUTION CONVECTION
ALLOWING GUIDANCE SUITE...EVEN THIS COVERAGE MAY BE ON THE
CONSERVATIVE SIDE. GUIDANCE ALSO IS IN GOOD AGREEMENT THAT THE
ACTIVITY WILL LINGER WELL INTO THE EVENING...ESPECIALLY FOR THE
COASTAL ZONES. THIS IS AGAIN FAIRLY TYPICAL FOR THIS SYNOPTIC SETUP.
FINALLY AFTER 11 PM OR SO...WE SHOULD SEE THE LAST OF THE STORMS
DISSIPATE OR MOVE OFFSHORE...LEAVING THE LAND ZONES WITH A GENERALLY
DRY FORECAST FOR THE SECOND HALF OF THE NIGHT.
BOTTOM LINE...ANYONE WITH OUTDOOR OR TRAVEL PLANS ALONG THE I-75
CORRIDOR OR WITH NEAR SHORE BOATING PLANS FOR THE LATE DAY / EVENING
HOURS SHOULD BE PREPARED FOR RAPIDLY DEVELOPING CLUSTERS OF
STORMS.
MONDAY/TUESDAY...
OVERALL SYNOPTIC PATTERN CHANGES LITTLE FOR THE FIRST TWO DAYS OF
THE WORK WEEK. THE RIDGE ALOFT HOLDS POSITION...BUT NOT STRONG
ENOUGH TO SIGNIFICANTLY SUPPRESS CONVECTION...AND THE SURFACE RIDGE
POSITION KEEPS OUR FLOW FROM THE EAST. THE ONLY CHANGE IS A SLIGHT
DECREASE IN COLUMN MOISTURE INTO MONDAY AND EVEN A BIT MORE ON
TUESDAY. TOUGH TO SAY IF THIS LOSS OF MOISTURE WILL BE ENOUGH TO
SLOW THE STILL FAVORABLE FLOW PATTERN FOR WEST COAST THUNDERSTORMS.
BEST GUESS IS THAT THE COLUMN WILL NOT DRY OUT ENOUGH TO SUPPRESS
CONVECTIVE COVERAGE AND CONSIDERED GOING WITH LIKELY POPS BOTH DAYS
DURING THE LATE AFTERNOON / EVENING. FOR NOW...KEPT THE LIKELY POPS
ALONG THE SUNCOAST ON MONDAY WITH HIGH END CHANCE (50-55%) RAIN
CHANCES FOR TAMPA BAY AND THE NATURE COAST...THEN HELD POPS AROUND
50% FOR ALL ON TUESDAY. COVERAGE COULD CERTAINLY BE HIGHER THAN
CURRENTLY FORECAST...ESPECIALLY ON MONDAY. THE NEXT SHIFT CAN TAKE
A CLOSER LOOK AT THE MOISTURE FIELDS IN THE NEXT MODEL CYCLE OR TWO
AND ADJUST UPWARDS IF NECESSARY.
&&
.LONG TERM (WEDNESDAY THROUGH NEXT SATURDAY)...
AN UPPER LEVEL RIDGE ACROSS FL FROM THE ATLANTIC WILL SLOWLY WEAKEN
THROUGH FRI AS AN UPPER LEVEL TROUGH MOVES FROM THE MIDWEST TO THE
SOUTHEAST U.S. THIS TROUGH CONTINUES EASTWARD ON SAT TO THE EASTERN
SEABOARD. AT THE SURFACE HIGH PRESSURE CENTERED OVER THE OPEN
ATLANTIC IN THE VICINITY OF 30 TO 35 NORTH LATITUDE RIDGES WEST TO
THE GULF COASTAL STATES THROUGH THE PERIOD...WITH A PREVAILING
EASTERLY/SOUTHEASTERLY BOUNDARY LAYER FLOW ACROSS THE AREA.
EXPECT A GENERAL SUMMERTIME PATTERN EACH DAY WITH SCATTERED TO
NUMEROUS MAINLY AFTERNOON THUNDERSTORMS. THE EAST AND SE FLOW WILL
KEEP THE WEST COAST SEA BREEZE CLOSE TO THE COAST FOR THE FIRST
COUPLE OF DAYS WITH THE HIGHEST COVERAGE OVER COASTAL COUNTIES.
THE EAST/SE FLOW WEAKENS SOME FOR THE END OF THE WEEK AND ALLOWS THE
WEST COAST SEA BREEZE TO PUSH SLIGHTLY FURTHER INLAND WITH MORE
UNIFORM COVERAGE AREA WIDE. TEMPERATURES RUN ABOVE NORMAL BY UP TO 1
TO 3 DEGREES.
&&
.AVIATION...
VFR CONDITIONS THROUGH MORNING WITH LIGHT VARIABLE/EASTERLY WINDS.
VFR CONTINUES ALTHOUGH TSRA MAY BEGIN TO IMPACT THE TERMINALS IN THE
AFTERNOON AND EARLY EVENING. WINDS BECOMES SE AND INCREASE SLIGHTLY
DURING THE MORNING THEN SHIFT TO ONSHORE DURING THE AFTERNOON.
&&
.MARINE...
THE RIDGE AXIS WILL REMAIN TO THE NORTH OF THE FORECAST WATERS
THROUGH THE EARLY PORTION OF THE WEEK. THIS POSITION WILL KEEP A
PERSISTENT EAST TO SOUTHEAST FLOW IN PLACE OVER THE FORECAST WATERS.
BEST CHANCES FOR THUNDERSTORMS WILL BE IN THE EARLY MORNING
HOURS...AND THEN AGAIN LATE IN THE AFTERNOON AND EVENING AS STORMS
MOVE EAST TO WEST OFFSHORE.
&&
.FIRE WEATHER...
THE SURFACE RIDGE AXIS TO OUR NORTH WILL KEEP A PERSISTENT EAST TO
SOUTHEAST FLOW GOING ACROSS THE FLORIDA PENINSULA THROUGH THE EARLY
PORTION OF THE WEEK. THIS EASTERLY FLOW WILL RESULT IN SEVERAL DAYS
OF ACTIVE AFTERNOON AND EVENING THUNDERSTORMS...ESPECIALLY ALONG THE
I-75 CORRIDOR. RELATIVE HUMIDITY VALUES ARE EXPECTED TO REMAIN WELL
ABOVE CRITICAL LEVELS AND NO SIGNIFICANT FIRE WEATHER CONCERNS ARE
IN THE FORECAST.
FOG POTENTIAL...NO SIGNIFICANT FOG IS EXPECTED THROUGH THE EARLY
PART OF THE WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 91 77 92 79 / 60 50 50 40
FMY 91 76 93 77 / 60 40 60 30
GIF 92 74 94 74 / 50 20 50 20
SRQ 91 76 93 76 / 60 60 60 40
BKV 91 73 93 74 / 60 50 50 40
SPG 90 79 91 80 / 60 60 50 40
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...RUDE
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
350 AM EDT SUN AUG 18 2013
.DISCUSSION...
TODAY-TONIGHT...
AN H30-H20 JET EXTENDING FROM THE LWR MS VALLEY TO CAPE COD WILL
SHIFT TO THE MID ATLC/CANADIAN MARITIMES...ALLOWING THE SUBTROPICAL
ATLC RIDGE AXIS TO ANCHOR ITSELF OVER THE DEEP SOUTH. THIS POSITION
WILL GENERATE A DEEP AND STEADY SERLY FLOW ACRS CENTRAL FL.
THE SE BREEZE WILL FAVORS THE WEST PENINSULA FOR DIURNAL CONVECTION
BUT WILL ALLOW FOR SLIGHTLY HIGHER COVERAGE OVER THE INTERIOR
COUNTIES AS WELL. RUC ANALYSIS SHOWS THE DRY AIR THAT WAS
APPROACHING THE SRN BAHAMAS SAT MORNING HAS NOT PUSHED AS FAR WEST
AS ANTICIPATED...H100-H70 AND H85-H50 MEAN RH LVLS OVER THE SW
ATLC/NRN BAHAMAS IS BTWN 70-85PCT...SUFFICIENT TO SUPPORT SCT
COVERAGE AREAWIDE.
INDEED...A CLUSTER OF SHRAS HAS PERSISTED JUST DOWNWIND OF THE NRN
BAHAMAS SINCE LATE LAST NIGHT...OWNING LARGELY TO A LCL POCKET OF
ENHANCED H85-H50 VORTICITY. WHILE THIS MID LVL ENERGY HAS BEEN
SLOWLY WEAKENING WITH TIME...SCT SHRAS HAVE PERSISTED IN THE SERLY
FLOW LONG ENOUGH TO PUSH ONSHORE. FURTHERMORE...GFS HAS BACKED OFF
ITS PREVIOUS DRY TREND...KEEPING PWAT VALUES ARND 2.0" THRU THE DAY
BEFORE DIMINISHING TO ARND 1.7" BY DAYBREAK MON.
THE MID LVL VORT GRADIENT IS RATHER TIGHT AS THE AFOREMENTIONED
IMPULSE IS PARKED NEXT TO A TORPID AIRMASS OVER THE W PENINSULA.
WHILE THIS MAY GIVE A COUPLE OF STORMS SOME PUNCH...OVERALL STORM
POTENTIAL WILL REMAIN LOW AS THE THERMODYNAMIC PROFILE REMAINS
WEAK...H50 TEMPS BTWN -6C AND -7C...H85-H50 BLO 6.0C/KM. ANY STRONG
ACTIVITY WOULD TEND TO FORM ALONG AND W OF THE FL TURNPIKE AS THE
DEEP SERLY FLOW WILL PUSH THE SEA BREEZE PRETTY FAR INLAND BY THE
PEAK CONVECTIVE HRS OF 18Z-24Z.
GIVEN THE DEPTH AND STEADY STRENGTH OF THE SERLY FLOW...MOS GUIDANCE
POPS LOOK A BIT ON THE HIGH SIDE. WILL CAP POPS AT 50PCT OVER THE
INTERIOR FROM OSCEOLA CO. NWD...40PCT ELSEWHERE. ONSHORE FLOW WILL
KEEP MAX TEMPS IN THE U80S/L90 ALONG THE COAST...INTERIOR WARMING TO
THE L/M90S. MIN TEMPS L/M70S.
MON-SAT...
THE UPPER LEVEL AND SURFACE RIDGE AXES REMAIN NORTH OF CENTRAL
FLORIDA THROUGH SATURDAY. DEEP LAYER EAST TO SOUTHEAST FLOW OFF THE
ATLANTIC WILL BE THE NORM THROUGH THE BALANCE OF THE FORECAST CYCLE.
TIME HEIGHT CROSS SECTIONS FOR THE SOUTHERN COASTAL SITES SHOW BULK
OF THE MOISTURE FROM 850MB/APPROX 5000 FEET AND BELOW. THE
COMBINATION OF WEAK UPPER LEVEL DISTURBANCES MOVING EAST TO WEST IN
THE UPPER LEVEL FLOW AND LIMITED DEPTH OF MOISTURE RESULT IN A 30 TO
40 PERCENT CHANCE OF AFTERNOON SHOWERS AND LIGHTNING STORMS OVER THE
INTERIOR. LINGERING STORMS AND SHOWERS UNTIL MID TO LATE EVENING
THEN PRECIP FREE OVER THE INTERIOR. THE EAST TO SOUTHEAST FLOW IS
DEEP ENOUGH WITH WINDS THROUGH 10000 FEET STRONG ENOUGH TO PUT IN A
SLIGHT CHANCE OF COASTAL SHOWERS.
HIGHS EACH DAY SHOULD RANGE FROM AROUND 90 AT THE COAST TO THE LOW
90S FOR THE INTERIOR. MORNING LOWS RANGE FROM THE MID 70S FOR THE
INTERIOR TO THE UPPER 70S AT THE COAST WITH SOME AROUND 80 DEGREE
READINGS AT THE BEACHES.
&&
.AVIATION...
VFR ALL SITES UNLESS OTHERWISE NOTED.
THRU 18/15Z...ISOLD MVFR SHRAS S OF KMLB. BTWN 18/15Z-18/19Z...SCT
MVFR SHRAS/IFR TSRAS DVLPG ALONG THE COAST AND MVG W-NW 10-15KTS.
BTWN 18/19Z-18/23Z...INTERIOR SITES SCT MVFR SHRAS/IFR TSRAS...
COASTAL SITES ISOLD MVFR SHRAS/ISOLD TSRAS WITH OCNL E/SE SFC WND
G20-22KTS. BTWN 18/23Z-19/03Z...CHC MVFR SHRAS/IFR TSRAS INTERIOR
SITES...SLGT CHC COASTAL SITES. AFT 19/03Z...SLGT CHC MVFR SHRAS
COASTAL SITES.
&&
.MARINE...
TODAY-TONIGHT...SUBTROPICAL RIDGE AXIS WILL CONSOLIDATE ITSELF OVER
THE DEEP SOUTH...RESULTING IN A GENTLE TO MODERATE E/SE BREEZE ACRS
THE LCL ATLC WATERS. THE ERLY FETCH EXTENDS WELL INTO THE W ATLC AND
WILL PUSH A 1-2FT LONG PD SWELL INTO THE E FL COAST...PUSHING SEAS
INTO THE 2-3FT RANGE NEARSHORE...3-4FT OFFSHORE. CHOPPY SHORT PD
WIND WAVES WILL PREVAIL S OF VERO BEACH DUE TO THE SHADOW EFFECT OF
GRAND BAHAMA ISLAND. SCT SHRAS AND ISOLD TSRAS.
MON-THU...THE ATLANTIC RIDGE WILL REMAIN NORTH OF THE EAST CENTRAL
FLORIDA COASTAL WATERS. A LONG 10 TO 15 KNOT EASTERLY FLOW AND FETCH
WILL BE FAVORABLE FOR SEAS 4 FEET OR LESS WITH A SMALL LONG PERIOD
SWELL COMPONENT.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 89 78 90 76 / 40 20 40 20
MCO 93 76 93 75 / 50 30 40 20
MLB 90 78 90 78 / 40 20 30 20
VRB 89 78 90 77 / 40 20 30 20
LEE 91 76 93 77 / 50 40 50 20
SFB 93 77 93 77 / 50 30 40 20
ORL 92 77 93 77 / 50 30 40 20
FPR 89 78 90 76 / 40 20 30 20
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM/AVIATION...BRAGAW
LONG TERM/IMPACT WX...WIMMER
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
208 AM EDT Sun Aug 18 2013
.NEAR TERM [Through Today]...
The main concern for today is the potential for additional flooding.
We are watching with interest a fairly well defined MCS moving
northeastward south of Mobile this morning. Some of the models may
be having some trouble with this feature as the NAM appears to be on
the weak side and our local 18/00z ARW run does not see this feature
very well (uses 00z NAM boundary conditions). The 18/00z GFS does
see this feature, but based on recent satellite/radar trends, it may
be just a tad too far west with its axis of heaviest precip
associated with it. This raises some concern about the potential for
additional flash flooding over the western portions of the forecast
area today due to low flash flood guidance values if this feature
moves just slightly more to the east. There is also ongoing areal
flooding in Walton county, so flash flood guidance values are
probably overdone in that county by quite a bit.
The plan of action right now is to observe the trends in the MCS on
satellite/radar over the next few hours and wait for some additional
pieces of hi-res guidance to come in before making a decision about
whether or not to re-issue the flash flood watch over the western
areas. From a model perspective, the trends in the HRRR as well as
our local 18/06z ARW run will be important as our 06z ARW uses the
00z GFS for boundary conditions and may have a better handle on this
feature than our 00z run.
&&
.SHORT TERM [Tonight through Tuesday]...
The large scale pattern continues to shift tonight. This is
highlighted by ridging over west half of Conus, Ern trough lifting
Newd with low opening up into OH Valley, and deep layer Atlc ridge
building WSW in its place into SE states. At surface, building
ridge aids in weakening quasi-stnry front and nudging it Nwd ending
its local focus for showers and thunderstorms. Low level flow also
begins to back to ESE.
During the rest of the period, Ern trough lifts further Newd and
flattens out. This allows Wrn and Atlc ridges to advance Ewd and Wwd
respectively bridging by end of period cutting off tropical plume.
This shifts steering flow to ELY allowing local gradients to tighten
some. By Tues, front has largely dissipated with surface high
anchored over NE SC/NW GA thus we transition to a more typical
summertime pattern with Gulf and Atlc seabreeze/mesoscale boundary
generated aftn and eve convection.
Will go with 30-40% tonight, 30-60% on Mon and 30-50% Tues E-W POP
gradient. Min temps in low 70s tonight. Highs Mon and Tues upper 80s
NW to low 90s SE with Max hear indices around 100 degrees.
&&
.LONG TERM [Tuesday Night through Saturday]...
Southeast low-level flow gradually backs to more of an easterly
direction as an upper level ridge builds into the region. This
should equate to more suppressed convective activity with time,
and overall PoPs show a decreasing trend through the extended
forecast. However, there should still be daily thunderstorm
chances. Temperatures will be closer to normal, perhaps warming to
slightly above normal by later in the week.
&&
.MARINE...
With some breezy southeast winds being observed over the western
waters at the moment (peak winds to near 20 knots), we have
inserted a SCEC headline through tonight west of AAF. The winds
will be slightly weaker in the eastern half of our coastal zones,
but could still approach 15 knots at times. Winds and seas will
lessen somewhat tomorrow morning, followed by a stretch of
easterly flow with winds around 10 knots and seas 3 feet or less.
&&
.AVIATION...
[Through 06z Monday] MVFR to IFR conditions are expected to develop
during the early morning hours this morning. Another round of
convection is expected across the area later today, most likely at
KDHN and KECP.
&&
.FIRE WEATHER...
There are currently no fire weather concerns with moist conditions
in place.
&&
HYDROLOGY...
Several local river systems have had (or will soon have) notable
rises and increased flows, except for perhaps the far southeast part
of our area in Taylor, Lafayette, and Dixie counties. The rivers, as
of a week ago, were running at lower levels than what we had seen
for most of July, so it has taken a considerable amount of rain to
move some to even a bankfull status. The next few river model runs
should be able to focus on the main threat areas, since these models
will have a more complete picture of the area rainfall the past few
days. A few rivers that may be particularly at risk include:
Choctawhatchee, Shoal, Apalachicola.
The most up to date, specific river forecast information can be
found on the AHPS web page at:
http:/water.weather.gov/ahps2/index.php?wfo=tae.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 89 73 91 73 91 / 60 30 50 30 40
Panama City 87 76 88 76 87 / 60 40 50 30 50
Dothan 86 72 89 72 90 / 70 40 60 30 50
Albany 87 72 90 72 91 / 60 30 60 40 50
Valdosta 89 72 91 72 92 / 50 30 50 40 40
Cross City 90 72 91 72 92 / 50 30 40 40 30
Apalachicola 86 77 86 77 86 / 50 40 50 30 40
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
AVIATION/FIRE WX/NEAR TERM...DVD
HYDROLOGY...DVD
Long Term...Lamers/Moore
Short Term/Marine...Block
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
250 PM EDT SUN AUG 18 2013
.SHORT TERM /TONIGHT THROUGH MONDAY/...
PRIMARY CONCERNS FOR THE SHORT TERM PERIOD WILL BE WHERE MODERATE
TO HEAVY RAIN AXIS SETS UP AND WHAT NEEDS TO BE DONE WITH THE
FLASH FLOOD WATCH AS A RESULT. AFTER A WET START TO THE
DAY...ACTIVITY HAS DWINDLED FOR THE MOST PART WITH JUST SOME
PASSING SHOWERS THROUGH THE ATLANTA METRO NOW HEADING INTO
NORTHEAST GEORGIA. FOCUS NOW SHIFTS TO THE SOUTHEAST WHERE LOCAL
WRF AND HRRR HAVE BEEN BEEN HONING IN ON WITH THUNDERSTORMS
DEVELOPING NICELY OVER THE FAR SOUTHEAST AT THIS HOUR. SPC SREF
SHOWS INSTABILITY INCREASING AS WARM FRONT EASES NORTHWARD WITH
AREAS AROUND TOOMBS AND MONTGOMERY COUNTIES SHOWING IN EXCESS OF
1000 J/KG OF AVAILABLE CAPE. WOULD EXPECT A LINE OF SHOWERS AND
STORMS TO DEVELOP IN THIS AREA AND PROGRESS TOWARD MACON LATER THIS
AFTERNOON INTO THE EVENING. ADDITIONAL ACTIVITY COULD FORM AHEAD
OF THIS AS WELL IN THE MORE UNSTABLE SECTION FROM COLUMBUS TO JUST
SOUTH OF ATHENS.
ALSO WATCHING GULF INITIATED STORMS AS THESE LOOK TO AFFECT THE
SOUTH AS WELL TONIGHT WITH STORMS ALREADY PUSHING INTO THE GEORGIA
PORTION FROM THE FLORIDA PANHANDLE. THERE IS SOME DISPARITY IN
SHORT TERM MODELS ON HOW THIS WILL EVENTUALLY EVOLVE THIS EVENING
WITH NAM12 INDICATING MORE DEVELOPMENT ON THE WESTERN SIDE OF THE
AREA VERSUS THE SOUTH. THIS UNCERTAINTY IS PROBLEMATIC GIVEN THE
FLOOD WATCH ORIENTATION WHICH IS CURRENTLY OVER THE WEST. IF
CURRENT TRENDS HOLD HOWEVER...THE SOUTHERN SECTIONS WOULD BE MORE
UNDER THE GUN. WITH THE UNCERTAINTY INVOLVED...WILL LET THE
EVENING SHIFT TAKE ANOTHER LOOK AT THIS DEVELOPING EVENT TO SEE
IF FLOOD WATCH NEEDS TO CONTINUE AND FOR WHAT AREAS.
FOR MONDAY...PRETTY MUCH THE SAME PATTERN BUT WITH WEDGE
CONTINUING TO WEAKEN AND MORE MOISTURE AVAILABLE FOR THE NORTHERN
ZONES AS WELL AS INSTABILITY. WENT LIKELY FOR MOST
AREAS...FAVORING THE SOUTH ONCE AGAIN...CLOSER TO THE VICINITY OF
STALLED OUT BOUNDARY. STILL USED SOME SLIGHT CAD INFLUENCES FOR
THE HIGH TEMPS MONDAY BUT SHOULD WARM NICELY TO UPPER 70S NORTH TO
LOWER 80S SOUTH.
DEESE
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
BUMPED POPS UP SOME INTO THURSDAY TO ACCOUNT FOR THE VERY MOIST
AIRMASS OVER THE AREA. OTHERWISE NO MAJOR CHANGES.
BDL
PREVIOUS DISCUSSION...
THE WET PATTERN CONTINUES INTO THE EXTENDED. THE STATIONARY FRONT
OVER SOUTH GA TODAY WILL MOVE SLOWLY NORTHWARD THROUGH MONDAY AND
SHOULD BE SOME WHERE BETWEEN ATL AND MCN BY TUE MORNING. THIS FRONT
WILL WEAKEN SOME BUT IT WILL STILL ACT AS A GUIDE FOR GULF MOISTURE
TO MOVE NORTHWARD ACROSS THE REGION THROUGH THE MIDDLE OF THE WEEK.
THE WEDGE LOOKS TO FINALLY BREAK DOWN SOMETIME MONDAY WHICH WILL
ALSO ALLOW FOR A MORE DIURNALLY DRIVEN PRECIP PATTERN THROUGH DAY 7.
BEST TIMING FOR THE HEAVIEST RAIN WILL BE IN THE SHORT TERM BUT DEEP
TROPICAL MOISTURE REMAINS OVER THE REGION THROUGH WED/THU WITH
PRECIPITABLE WATERS IN THE 1.5 TO 2.0 INCH RANGE THROUGH THU. THE
DEEPER MOISTURE MOVES NORTH AND EAST OF THE STATE BY THU NIGHT BUT
THE DIURNAL CONVECTIVE TREND WILL CONTINUE INTO NEXT WEEKEND. TEMPS
WILL BEGIN TO REBOUND BY TUE AND BE BACK TO NEAR SEASONAL NORMS BY
THU/FRI.
01
&&
.AVIATION...
18Z UPDATE...
CHALLENGING FORECAST CYCLE AS WE DEAL WITH COOL HIGH PRESSURE FOR
NORTHERN TAF SITES AND STATIONARY FRONT FOR THE SOUTHERN MOST
SITES. THIS HAS RESULTED IN SITES FROM ATL SOUTHWARD BECOMING MVFR
THIS AFTERNOON WITH EVEN SOME VFR FOR CSG. EXPECT SITES NORTH OF
ATL TO REMAIN A THOUSAND FEET OR LESS THROUGH THE REMAINDER OF THE
EVENING. ALL SITES WILL GO IFR BY LATE THIS EVENING AND THEN LIFR
FOR THE EARLY MORNING HOURS. SHRA LOOK TO REDEVELOP BY THIS
EVENING AS WELL AND HAVE INCLUDED TEMPO THROUGH 02Z FOR ALL SITES.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM ON ALL ELEMENTS
DEESE
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 69 81 69 79 / 50 60 50 70
ATLANTA 69 79 70 79 / 70 50 40 60
BLAIRSVILLE 65 76 66 78 / 70 50 50 60
CARTERSVILLE 69 79 69 78 / 70 50 50 60
COLUMBUS 71 83 72 85 / 50 60 40 70
GAINESVILLE 68 78 69 76 / 70 50 50 70
MACON 70 82 70 82 / 40 60 40 60
ROME 69 80 70 80 / 70 50 50 60
PEACHTREE CITY 70 80 71 79 / 60 50 40 60
VIDALIA 72 86 72 86 / 40 60 40 40
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR THE FOLLOWING
ZONES: BARTOW...BIBB...BLECKLEY...BUTTS...CARROLL...CATOOSA...
CHATTAHOOCHEE...CHATTOOGA...CHEROKEE...CLAYTON...COBB...COWETA...
CRAWFORD...CRISP...DADE...DEKALB...DODGE...DOOLY...DOUGLAS...
FANNIN...FAYETTE...FLOYD...GILMER...GORDON...HARALSON...HARRIS...
HEARD...HENRY...HOUSTON...LAMAR...MACON...MARION...MERIWETHER...
MONROE...MURRAY...MUSCOGEE...NORTH FULTON...PAULDING...PEACH...
PICKENS...PIKE...POLK...PULASKI...ROCKDALE...SCHLEY...SOUTH
FULTON...SPALDING...STEWART...SUMTER...TALBOT...TAYLOR...
TELFAIR...TROUP...TWIGGS...UPSON...WALKER...WEBSTER...
WHITFIELD...WILCOX.
&&
$$
SHORT TERM...DEESE
LONG TERM....BDL
AVIATION...DEESE
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
156 PM EDT SUN AUG 18 2013
.PREV DISCUSSION... /ISSUED 1005 AM EDT SUN AUG 18 2013/
UPDATE...MODELS DEPICT SHORTWAVE IN MEAN FLOW MOVING FROM THE
GULF COAST UP THE WESTERN SIDE OF THE STATE. THIS HAS ALLOWED
FOCUS FOR RAINFALL TO SHIFT FROM THE SOUTHERN PORTIONS AS HAS BEEN
THE CASE THE PAST FEW DAYS TO MAINLY NORTHWEST GEORGIA THIS
MORNING. PROBLEMATIC FORECAST FOR THE REMAINDER OF TODAY WITH
SHORTWAVE CONTINUING TO EXERT INFLUENCE BUT ALSO MAJOR
CONTRIBUTING FACTORS FROM WEDGE AND HOW IT ERODES IF ANY AND
STATIONARY FRONT TO THE SOUTH AND HOW MUCH IT LIFTS NORTH IF ANY.
WILL LEAN TOWARD THE GFS WHICH HAS AN UNUSUAL SOLUTION OF A
STRONGER WEDGE THAN THE NAM12. THIS WILL KEEP FRONT TO THE SOUTH
AND WEDGE IN PLACE ALTHOUGH NOT QUITE AS STRONG AS YESTERDAY AS
EVIDENCED BY ATLANTAS TEMP OF 70 ALREADY. SHOULD SEE WAVES OF
PRECIP REDEVELOP WITH WESTERN SIDE REMAINING FAVORED. OTHER THAN
ELEVATED CONVECTION...FEEL THERE IS STILL AN OPPORTUNITY FOR SOME
SURFACE BASED ACTIVITY OVER THE EXTREME SOUTH LATE WHERE HRRR AND
WRF INDICATE MORE PRONOUNCED ACTIVITY. SHEAR IS MARGINAL BUT IN
VICINITY OF FRONT WILL NEED TO WATCH CLOSELY FOR ANY POTENTIAL
ROTATION IN STRONGER CELLS. OTHERWISE...FLOOD WATCH AND REMAINING
GRIDS LOOK ON TARGET AND NO CHANGES PLANNED.
PREV DISCUSSION... /ISSUED 734 AM EDT SUN AUG 18 2013/
SHORT TERM /TODAY THROUGH MONDAY/...
/ISSUED AT 445 AM EDT SUN AUG 18 2013/
LATEST SURFACE ANALYSIS SHOWS A WARM FRONT JUST SOUTH OF COLUMBUS
AND AUGUSTA...BUT JUST NORTH OF MACON. NAM AND ECMWF DRIFT THE FRONT
NORTHWARD AT LEAST INTO WEST CENTRAL GA THIS AFTERNOON AS THE UPPER
LOW CURRENTLY OVER WEST KY/TN BEGINS TO KICK EASTWARD LATER THIS
AFTERNOON. THE GFS HOLDS THE COOL WEDGE OVER THE NORTHEAST AND EAST
CENTRAL ZONES THROUGH TONIGHT...WHICH WILL MAKE TEMPS TRICKY TODAY.
SURFACE ANALYSIS ALSO SHOWS AN AREA OF LOW PRESSURE ALONG THE LA
COAST WHERE IT APPEARS TO BE DRIFTING NORTHWARD. NAM AND ECMWF DRIFT
THE SURFACE LOW WNW TODAY WHILE THE GFS DRIFTS IT NNE INTO SE LA.
THE GFS SEEMS TO INITIALIZE SLIGHTLY BETTER WITH THIS FEATURE AND
WITH THE UPPER LOW TO THE NORTH...WOULD NOT BE SURPRISED TO SEE THIS
SURFACE LOW DRIFT NNE AS THE GFS SUGGEST. THIS WOULD ALLOW THE WARM
FRONT TO ALSO DRIFT NORTH...AT LEAST INTO THE WEST CENTRAL ZONES
MAYBE FROM NEAR AUGUSTA TO ATLANTA TO ROME AS THE WEDGE MAY HOLD
STRONG FOR AREAS NE OF THIS LINE. EITHER WAY... MODELS SUGGEST THE
FRONT COULD PROVIDE A FOCUS FOR PERIODS OF HEAVY RAIN ACROSS THE NW
AND WEST CENTRAL ZONES TODAY...WHERE 1 TO 2 INCHES WITH ISOLATED
HIGHER AMOUNTS MAY BE POSSIBLY THROUGH 8 PM THIS EVENING AS THE
UPPER LOW BEGINS TO LIFT TO THE ENE. DECIDED TO PLAY IT SAFE AND
POST A FLASH FLOOD WATCH FOR THE WESTERN ZONES THROUGH 8 PM THIS
EVENING...GENERALLY FOR AREAS ALONG AND WEST OF A BLUE RIDGE TO
ATLANTA TO MACON LINE. THE WEDGE MAY HOLD STRONG ENOUGH TO THE EAST
TO ONLY ALLOW OCCASIONAL LIGHT TO MODERATE RAINS. WITH MUCH
UNCERTAINTY ON THE PROGRESSION OF THE WARM FRONT TODAY...
TEMPERATURES WILL BE VERY TRICKY. DECIDED TO TAKE A BLEND BETWEEN
THE WARMER MET AND COOLER MAV NUMBERS...WITH A LEAN TOWARD THE
COOLER GFS OVER THE EASTERN ZONES WHERE THE WEDGE WILL LIKELY
PERSIST. WILL ALSO WORD FOR ISOLATED THUNDERSTORMS ACROSS THE ENTIRE
FORECAST AREA THIS AFTERNOON AS THE UPPER LOW INTERACTS WITH
INCREASING INSTABILITIES ALONG AND SOUTH OF THE WARM FRONT. EXPECT
THE WEDGE INFLUENCE TO WEAKEN EVEN MORE ON MONDAY AS THE UPPER LOW
SHEARS OFF TO THE NE TONIGHT...LEAVING AN ACTIVE WEAK TROUGH IN ITS
PLACE. THIS COUPLED WITH HIGH PRESSURE OFF THE MID ATLANTIC COAST
WILL STILL PROVIDE FOR AN ESE WIND FLOW TONIGHT AND ON MONDAY. SO
DESPITE A WARMING TREND...STILL EXPECT WELL BELOW NORMAL HIGHS ON
MONDAY FOR MOST AREAS. A DEEPER SE WIND FLOW AND INCREASING
INSTABILITIES NORTHWARD WILL WARRANT A CHANCE OF THUNDERSTORMS ALL
ZONES FOR MONDAY AFTERNOON.
39
LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
/ISSUED AT 445 AM EDT SUN AUG 18 2013/
THE WET PATTERN CONTINUES INTO THE EXTENDED. THE STATIONARY FRONT
OVER SOUTH GA TODAY WILL MOVE SLOWLY NORTHWARD THROUGH MONDAY AND
SHOULD BE SOME WHERE BETWEEN ATL AND MCN BY TUE MORNING. THIS
FRONT WILL WEAKEN SOME BUT IT WILL STILL ACT AS A GUIDE FOR GULF
MOISTURE TO MOVE NORTHWARD ACROSS THE REGION THROUGH THE MIDDLE OF
THE WEEK. THE WEDGE LOOKS TO FINALLY BREAK DOWN SOMETIME MONDAY
WHICH WILL ALSO ALLOW FOR A MORE DIURNALLY DRIVEN PRECIP PATTERN
THROUGH DAY 7. BEST TIMING FOR THE HEAVIEST RAIN WILL BE IN THE
SHORT TERM BUT DEEP TROPICAL MOISTURE REMAINS OVER THE REGION
THROUGH WED/THU WITH PRECIPITABLE WATERS IN THE 1.5 TO 2.0 INCH
RANGE THROUGH THU. THE DEEPER MOISTURE MOVES NORTH AND EAST OF THE
STATE BY THU NIGHT BUT THE DIURNAL CONVECTIVE TREND WILL CONTINUE
INTO NEXT WEEKEND. TEMPS WILL BEGIN TO REBOUND BY TUE AND BE BACK
TO NEAR SEASONAL NORMS BY THU/FRI.
01
HYDROLOGY...
/ISSUED AT 445 AM EDT SUN AUG 18 2013/
AN UPPER LOW PRESSURE SYSTEM TO THE NORTHWEST WILL INTERACT WITH A A
WARM FRONT DRIFTING NORTH TODAY TO PRODUCE A CHANCE OF HEAVY RAIN
ACROSS MAINLY NORTHWEST AND WEST CENTRAL GA TODAY. MODEL AND HPC QPF
NUMBERS SUGGEST ANYWHERE FROM 1 TO 2 INCHES WITH ISOLATED HIGHER
AMOUNTS IS POSSIBLE THROUGH THE AFTERNOON AND EVENING HOURS TODAY.
THEREFORE... HAVE POSTED A FLASH FLOOD WATCH THROUGH 8 PM THIS
EVENING FOR AREAS ALONG AND WEST OF A BLUE RIDGE TO ATLANTA TO MACON
LINE WHERE THE GREATEST RAINFALL AMOUNTS ARE EXPECTED. HOWEVER...
STILL MUCH UNCERTAINTY ON LOCATION...INTENSITY AND DURATION OF
CONVECTION THROUGH THE AFTERNOON AND EVENING HOURS...SO SOME AREAS
EAST OF THE WATCH COULD STILL SEE PERIODS OF BRIEF HEAVY RAIN. /39
CLIMATE...
RECORDS FOR 08-18
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAHN 103 1995 70 1905 76 1946 62 1979
1976
1964
KATL 101 2000 70 1981 80 2000 62 1964
1995 1905 1879
KCSG 104 2000 78 1981 78 2000 62 1948
1995
KMCN 104 2000 75 1981 77 2000 63 1948
1905 1995
1951
&&
.AVIATION...
18Z UPDATE...
CHALLENGING FORECAST CYCLE AS WE DEAL WITH COOL HIGH PRESSURE FOR
NORTHERN TAF SITES AND STATIONARY FRONT FOR THE SOUTHERN MOST
SITES. THIS HAS RESULTED IN SITES FROM ATL SOUTHWARD BECOMING MVFR
THIS AFTERNOON WITH EVEN SOME VFR FOR CSG. EXPECT SITES NORTH OF
ATL TO REMAIN A THOUSAND FEET OR LESS THROUGH THE REMAINDER OF THE
EVENING. ALL SITES WILL GO IFR BY LATE THIS EVENING AND THEN LIFR
FOR THE EARLY MORNING HOURS. SHRA LOOK TO REDEVELOP BY THIS
EVENING AS WELL AND HAVE INCLUDED TEPO THROUGH 02Z FOR ALL SITES.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM ON LL ELEMENTS
DEESE
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 75 69 81 70 / 50 50 50 50
ATLANTA 74 68 79 71 / 70 70 50 40
BLAIRSVILLE 69 65 77 65 / 70 70 50 50
CARTERSVILLE 74 68 80 70 / 80 70 50 50
COLUMBUS 75 71 82 72 / 100 60 50 40
GAINESVILLE 72 68 78 69 / 60 70 50 50
MACON 76 71 83 71 / 50 40 50 40
ROME 72 68 81 70 / 90 80 40 50
PEACHTREE CITY 74 67 80 70 / 80 60 50 40
VIDALIA 82 72 86 72 / 60 50 50 40
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR THE FOLLOWING
ZONES: BARTOW...BIBB...BLECKLEY...BUTTS...CARROLL...CATOOSA...
CHATTAHOOCHEE...CHATTOOGA...CHEROKEE...CLAYTON...COBB...COWETA...
CRAWFORD...CRISP...DADE...DEKALB...DODGE...DOOLY...DOUGLAS...
FANNIN...FAYETTE...FLOYD...GILMER...GORDON...HARALSON...HARRIS...
HEARD...HENRY...HOUSTON...LAMAR...MACON...MARION...MERIWETHER...
MONROE...MURRAY...MUSCOGEE...NORTH FULTON...PAULDING...PEACH...
PICKENS...PIKE...POLK...PULASKI...ROCKDALE...SCHLEY...SOUTH
FULTON...SPALDING...STEWART...SUMTER...TALBOT...TAYLOR...
TELFAIR...TROUP...TWIGGS...UPSON...WALKER...WEBSTER...
WHITFIELD...WILCOX.
&&
$$
SHORT TERM...DEESE
LONG TERM....BDL
AVIATION...DEESE
AREA FORECAST DISCUSSION...CORRECTED
NWS COLUMBIA SC
1142 AM EDT SUN AUG 18 2013
.SYNOPSIS...
THE LOW LEVEL WEDGE OVER OUR REGION WILL SLOWLY WEAKEN
TODAY...PROVIDING A CHANCE OF LATE DAY SHOWERS AND THUNDERSTORMS
OVER PORTIONS OF THE REGION. SEASONAL TEMPERATURES...ALONG WITH A
CHANCE OF MAINLY AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS...ARE EXPECT THIS WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST SATELLITE IMAGES AND SURFACE OBS REVEAL WEDGE BEGINNING TO
BREAK ACROSS SOUTHERN PORTIONS OF THE CSRA AND SW MIDLANDS...WITH
DECREASING CLOUDINESS ACROSS THAT REGION AND SOUTH ACROSS SE GA.
DIURNAL HEATING WILL LEAD TO INCREASING INSTABILITIES ACROSS SE
GA AND NEAR OUR S/SW FA. LATEST HRRR AND NARRE SUGGESTS CONVECTION
DEVELOPING DURING THE MID AFTN ACROSS SE GA...DRIFING NORTH INTO
THE CSRA AND PORTIONS OF THE MIDLANDS LATE THIS AFTN AND EVE.
STILL SOME UNCERTAINTIES AND MODEL DIFFERENCES WITH REGARDS TO
TIMING/LOCATION/COVERAGE OF PRECIP TODAY. WILL MAINTAIN BEST POPS
CSRA. WEDGE COULD POSSIBLY SHIFT BACK TO THE SOUTH SOME TONIGHT.
&&
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
THE WEDGE IS EXPECTED TO WEAKEN OVER THE MIDLANDS AND CSRA BY
MONDAY. A DEEP MOIST SOUTHERLY FLOW WILL BE ACROSS THE AREA WITH
WEAK MOISTURE FLUX. PRECIPITABLE WATER REMAINS AT OR ABOVE 2
INCHES. THE AIR MASS IS FORECAST TO BECOME MODERATELY UNSTABLE.
SO...WITH DIURNAL HEATING...EXPECT AT LEAST SCATTERED CONVECTION.
WE COULD ALSO SEE CONVECTION DEVELOP ALONG THE SEA-BREEZE FRONT.
WENT WITH HIGH CHANCE POPS FOR MONDAY WITH HIGHS IN THE MID TO
UPPER 80S AND LOWS AROUND 70.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
WEAK UPPER TROUGHINESS TO OUR N AND NW...WHILE UPPER HIGH BUILDS
WESTWARD FROM THE ATLANTIC REMAINING CENTERED JUST TO OUR S AND SE.
SURFACE FRONT EXPECTED TO CONTINUE SLOWLY LIFTING NORTH OR
WEAKENING. IT APPEARS SUFFICIENT ATMOSPHERIC MOISTURE AND
INSTABILITY WILL REMAIN. MODEL CONSENSUS POPS ARE TRENDING
DOWN...THOUGH STILL ABOVE CL IMO AT LEAST THROUGH MIDWEEK...AND
WILL EXPECT POPS TO BECOME MORE DIURNALLY FAVORED WITH DAYTIME
HEATING. TEMPS SHOULD BEGIN TRENDING UP MORE TOWARDS CL IMO.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
CIGS ARE SLOWLY IMPROVING AND ARE MOSTLY MVFR AT THE TERMINALS AT
15Z. WILL EXPECT CONTINUED GRADUAL IMPROVEMENT IN CIGS WITH
DIURNAL HEATING AND WITH WEDGE SLOWLY ERODING/LIFTING NORTH.
LATEST HIGH RES MODELS INDICATING CONVECTION DEVELOPING ACROSS SE
GA BY MID AFTN...DRIFTING NORTH INTO OUR FA BY LATE AFTN/EVE. FOR
NOW...WILL HANDLE WITH VCSH AT AGS/DNL/OGB. WILL AMEND LATER FOR
STRONGER MENTION IF/WHEN CONFIDENCE WARRANTS. CIGS COULD LOWER
AGAIN TONIGHT AS WEDGE TRIES TO BUILD BACK TO THE
SOUTH...ESPECIALLY AT THE MORE NORTHERN TERMINALS CAE/CUB. WILL
ADDRESS THAT IN LATER TAF ISSUANCES.
EXTENDED AVIATION OUTLOOK...LATE NIGHT/EARLY MORNING
FOG/STRATUS. CHANCE OF AFTERNOON/EVENING THUNDERSTORMS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1132 AM EDT SUN AUG 18 2013
.SYNOPSIS...
THE WEDGE PATTERN WILL LINGER OVER OUR AREA TODAY THEN WEAKEN
MONDAY. SEASONABLE TEMPERATURES WILL RETURN BY MIDWEEK AS HIGH
PRESSURE OVER THE WESTERN ATLANTIC RIDGES INTO THE SOUTHEASTERN
STATES.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST SATELLITE IMAGES AND SURFACE OBS REVEAL WEDGE BEGINNING TO
BREAK ACROSS SOUTHERN PORTIONS OF THE CSRA AND SW MIDLANDS...WITH
DECREASING CLOUDINESS ACROSS THAT REGION AND SOUTH ACROSS SE GA.
DIURNAL HEATING WILL LEAD TO INCREASING INSTABILITIES ACROSS SE
GA AND NEAR OUR S/SW FA. LATEST HRRR AND NARRE SUGGESTS CONVECTION
DEVELOPING DURING THE MID AFTN ACROSS SE GA...DRIFING NORTH INTO
THE CSRA AND PORTIONS OF THE MIDLANDS LATE THIS AFTN AND EVE.
STILL SOME UNCERTAINTIES AND MODEL DIFFERENCES WITH REGARDS TO
TIMING/LOCATION/COVERAGE OF PRECIP TODAY. WILL MAINTAIN BEST POPS
CSRA. WEDGE COULD POSSIBLY SHIFT BACK TO THE SOUTH SOME TONIGHT.
&&
.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
THE WEDGE IS EXPECTED TO WEAKEN OVER THE MIDLANDS AND CSRA BY
MONDAY. A DEEP MOIST SOUTHERLY FLOW WILL BE ACROSS THE AREA WITH
WEAK MOISTURE FLUX. PRECIPITABLE WATER REMAINS AT OR ABOVE 2
INCHES. THE AIR MASS IS FORECAST TO BECOME MODERATELY UNSTABLE.
SO...WITH DIURNAL HEATING...EXPECT AT LEAST SCATTERED CONVECTION.
WE COULD ALSO SEE CONVECTION DEVELOP ALONG THE SEA-BREEZE FRONT.
WENT WITH HIGH CHANCE POPS FOR MONDAY WITH HIGHS IN THE MID TO
UPPER 80S AND LOWS AROUND 70.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
WEAK UPPER TROUGHINESS TO OUR N AND NW...WHILE UPPER HIGH BUILDS
WESTWARD FROM THE ATLANTIC REMAINING CENTERED JUST TO OUR S AND SE.
SURFACE FRONT EXPECTED TO CONTINUE SLOWLY LIFTING NORTH OR
WEAKENING. IT APPEARS SUFFICIENT ATMOSPHERIC MOISTURE AND
INSTABILITY WILL REMAIN. MODEL CONSENSUS POPS ARE TRENDING
DOWN...THOUGH STILL ABOVE CL IMO AT LEAST THROUGH MIDWEEK...AND
WILL EXPECT POPS TO BECOME MORE DIURNALLY FAVORED WITH DAYTIME
HEATING. TEMPS SHOULD BEGIN TRENDING UP MORE TOWARDS CL IMO.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
CIGS ARE SLOWLY IMPROVING AND ARE MOSTLY MVFR AT THE TERMINALS AT
15Z. WILL EXPECT CONTINUED GRADUAL IMPROVEMENT IN CIGS WITH
DIURNAL HEATING AND WITH WEDGE SLOWLY ERODING/LIFTING NORTH.
LATEST HIGH RES MODELS INDICATING CONVECTION DEVELOPING ACROSS SE
GA BY MID AFTN...DRIFTING NORTH INTO OUR FA BY LATE AFTN/EVE. FOR
NOW...WILL HANDLE WITH VCSH AT AGS/DNL/OGB. WILL AMEND LATER FOR
STRONGER MENTION IF/WHEN CONFIDENCE WARRANTS. CIGS COULD LOWER
AGAIN TONIGHT AS WEDGE TRIES TO BUILD BACK TO THE
SOUTH...ESPECIALLY AT THE MORE NORTHERN TERMINALS CAE/CUB. WILL
ADDRESS THAT IN LATER TAF ISSUANCES.
EXTENDED AVIATION OUTLOOK...LATE NIGHT/EARLY MORNING
FOG/STRATUS. CHANCE OF AFTERNOON/EVENING THUNDERSTORMS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
1005 AM EDT SUN AUG 18 2013
.UPDATE...MODELS DEPICT SHORTWAVE IN MEAN FLOW MOVING FROM THE
GULF COAST UP THE WESTERN SIDE OF THE STATE. THIS HAS ALLOWED
FOCUS FOR RAINFALL TO SHIFT FROM THE SOUTHERN PORTIONS AS HAS BEEN
THE CASE THE PAST FEW DAYS TO MAINLY NORTHWEST GEORGIA THIS
MORNING. PROBLEMATIC FORECAST FOR THE REMAINDER OF TODAY WITH
SHORTWAVE CONTINUING TO EXERT INFLUENCE BUT ALSO MAJOR
CONTRIBUTING FACTORS FROM WEDGE AND HOW IT ERODES IF ANY AND
STATIONARY FRONT TO THE SOUTH AND HOW MUCH IT LIFTS NORTH IF ANY.
WILL LEAN TOWARD THE GFS WHICH HAS AN UNUSUAL SOLUTION OF A
STRONGER WEDGE THAN THE NAM12. THIS WILL KEEP FRONT TO THE SOUTH
AND WEDGE IN PLACE ALTHOUGH NOT QUITE AS STRONG AS YESTERDAY AS
EVIDENCED BY ATLANTAS TEMP OF 70 ALREADY. SHOULD SEE WAVES OF
PRECIP REDEVELOP WITH WESTERN SIDE REMAINING FAVORED. OTHER THAN
ELEVATED CONVECTION...FEEL THERE IS STILL AN OPPORTUNITY FOR SOME
SURFACE BASED ACTIVITY OVER THE EXTREME SOUTH LATE WHERE HRRR AND
WRF INDICATE MORE PRONOUNCED ACTIVITY. SHEAR IS MARGINAL BUT IN
VICINITY OF FRONT WILL NEED TO WATCH CLOSELY FOR ANY POTENTIAL
ROTATION IN STRONGER CELLS. OTHERWISE...FLOOD WATCH AND REMAINING
GRIDS LOOK ON TARGET AND NO CHANGES PLANNED.
&&
.PREV DISCUSSION... /ISSUED 734 AM EDT SUN AUG 18 2013/
SHORT TERM /TODAY THROUGH MONDAY/...
/ISSUED AT 445 AM EDT SUN AUG 18 2013/
LATEST SURFACE ANALYSIS SHOWS A WARM FRONT JUST SOUTH OF COLUMBUS
AND AUGUSTA...BUT JUST NORTH OF MACON. NAM AND ECMWF DRIFT THE FRONT
NORTHWARD AT LEAST INTO WEST CENTRAL GA THIS AFTERNOON AS THE UPPER
LOW CURRENTLY OVER WEST KY/TN BEGINS TO KICK EASTWARD LATER THIS
AFTERNOON. THE GFS HOLDS THE COOL WEDGE OVER THE NORTHEAST AND EAST
CENTRAL ZONES THROUGH TONIGHT...WHICH WILL MAKE TEMPS TRICKY TODAY.
SURFACE ANALYSIS ALSO SHOWS AN AREA OF LOW PRESSURE ALONG THE LA
COAST WHERE IT APPEARS TO BE DRIFTING NORTHWARD. NAM AND ECMWF DRIFT
THE SURFACE LOW WNW TODAY WHILE THE GFS DRIFTS IT NNE INTO SE LA.
THE GFS SEEMS TO INITIALIZE SLIGHTLY BETTER WITH THIS FEATURE AND
WITH THE UPPER LOW TO THE NORTH...WOULD NOT BE SURPRISED TO SEE THIS
SURFACE LOW DRIFT NNE AS THE GFS SUGGEST. THIS WOULD ALLOW THE WARM
FRONT TO ALSO DRIFT NORTH...AT LEAST INTO THE WEST CENTRAL ZONES
MAYBE FROM NEAR AUGUSTA TO ATLANTA TO ROME AS THE WEDGE MAY HOLD
STRONG FOR AREAS NE OF THIS LINE. EITHER WAY... MODELS SUGGEST THE
FRONT COULD PROVIDE A FOCUS FOR PERIODS OF HEAVY RAIN ACROSS THE NW
AND WEST CENTRAL ZONES TODAY...WHERE 1 TO 2 INCHES WITH ISOLATED
HIGHER AMOUNTS MAY BE POSSIBLY THROUGH 8 PM THIS EVENING AS THE
UPPER LOW BEGINS TO LIFT TO THE ENE. DECIDED TO PLAY IT SAFE AND
POST A FLASH FLOOD WATCH FOR THE WESTERN ZONES THROUGH 8 PM THIS
EVENING...GENERALLY FOR AREAS ALONG AND WEST OF A BLUE RIDGE TO
ATLANTA TO MACON LINE. THE WEDGE MAY HOLD STRONG ENOUGH TO THE EAST
TO ONLY ALLOW OCCASIONAL LIGHT TO MODERATE RAINS. WITH MUCH
UNCERTAINTY ON THE PROGRESSION OF THE WARM FRONT TODAY...
TEMPERATURES WILL BE VERY TRICKY. DECIDED TO TAKE A BLEND BETWEEN
THE WARMER MET AND COOLER MAV NUMBERS...WITH A LEAN TOWARD THE
COOLER GFS OVER THE EASTERN ZONES WHERE THE WEDGE WILL LIKELY
PERSIST. WILL ALSO WORD FOR ISOLATED THUNDERSTORMS ACROSS THE ENTIRE
FORECAST AREA THIS AFTERNOON AS THE UPPER LOW INTERACTS WITH
INCREASING INSTABILITIES ALONG AND SOUTH OF THE WARM FRONT. EXPECT
THE WEDGE INFLUENCE TO WEAKEN EVEN MORE ON MONDAY AS THE UPPER LOW
SHEARS OFF TO THE NE TONIGHT...LEAVING AN ACTIVE WEAK TROUGH IN ITS
PLACE. THIS COUPLED WITH HIGH PRESSURE OFF THE MID ATLANTIC COAST
WILL STILL PROVIDE FOR AN ESE WIND FLOW TONIGHT AND ON MONDAY. SO
DESPITE A WARMING TREND...STILL EXPECT WELL BELOW NORMAL HIGHS ON
MONDAY FOR MOST AREAS. A DEEPER SE WIND FLOW AND INCREASING
INSTABILITIES NORTHWARD WILL WARRANT A CHANCE OF THUNDERSTORMS ALL
ZONES FOR MONDAY AFTERNOON.
39
LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
/ISSUED AT 445 AM EDT SUN AUG 18 2013/
THE WET PATTERN CONTINUES INTO THE EXTENDED. THE STATIONARY FRONT
OVER SOUTH GA TODAY WILL MOVE SLOWLY NORTHWARD THROUGH MONDAY AND
SHOULD BE SOME WHERE BETWEEN ATL AND MCN BY TUE MORNING. THIS
FRONT WILL WEAKEN SOME BUT IT WILL STILL ACT AS A GUIDE FOR GULF
MOISTURE TO MOVE NORTHWARD ACROSS THE REGION THROUGH THE MIDDLE OF
THE WEEK. THE WEDGE LOOKS TO FINALLY BREAK DOWN SOMETIME MONDAY
WHICH WILL ALSO ALLOW FOR A MORE DIURNALLY DRIVEN PRECIP PATTERN
THROUGH DAY 7. BEST TIMING FOR THE HEAVIEST RAIN WILL BE IN THE
SHORT TERM BUT DEEP TROPICAL MOISTURE REMAINS OVER THE REGION
THROUGH WED/THU WITH PRECIPITABLE WATERS IN THE 1.5 TO 2.0 INCH
RANGE THROUGH THU. THE DEEPER MOISTURE MOVES NORTH AND EAST OF THE
STATE BY THU NIGHT BUT THE DIURNAL CONVECTIVE TREND WILL CONTINUE
INTO NEXT WEEKEND. TEMPS WILL BEGIN TO REBOUND BY TUE AND BE BACK
TO NEAR SEASONAL NORMS BY THU/FRI.
01
HYDROLOGY...
/ISSUED AT 445 AM EDT SUN AUG 18 2013/
AN UPPER LOW PRESSURE SYSTEM TO THE NORTHWEST WILL INTERACT WITH A A
WARM FRONT DRIFTING NORTH TODAY TO PRODUCE A CHANCE OF HEAVY RAIN
ACROSS MAINLY NORTHWEST AND WEST CENTRAL GA TODAY. MODEL AND HPC QPF
NUMBERS SUGGEST ANYWHERE FROM 1 TO 2 INCHES WITH ISOLATED HIGHER
AMOUNTS IS POSSIBLE THROUGH THE AFTERNOON AND EVENING HOURS TODAY.
THEREFORE... HAVE POSTED A FLASH FLOOD WATCH THROUGH 8 PM THIS
EVENING FOR AREAS ALONG AND WEST OF A BLUE RIDGE TO ATLANTA TO MACON
LINE WHERE THE GREATEST RAINFALL AMOUNTS ARE EXPECTED. HOWEVER...
STILL MUCH UNCERTAINTY ON LOCATION...INTENSITY AND DURATION OF
CONVECTION THROUGH THE AFTERNOON AND EVENING HOURS...SO SOME AREAS
EAST OF THE WATCH COULD STILL SEE PERIODS OF BRIEF HEAVY RAIN. /39
CLIMATE...
RECORDS FOR 08-18
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAHN 103 1995 70 1905 76 1946 62 1979
1976
1964
KATL 101 2000 70 1981 80 2000 62 1964
1995 1905 1879
KCSG 104 2000 78 1981 78 2000 62 1948
1995
KMCN 104 2000 75 1981 77 2000 63 1948
1905 1995
1951
AVIATION...
12Z UPDATE...
LIFR/IFR CIGS/VIS WILL GRADUALLY IMPROVE TO LOW MVFR CIGS BY 16-17Z
THIS MORNING... EXCEPT VFR AT CSG AND MCN BY THEN. GFS HOLDS THE
WEDGE IN OVER THE ATLANTA TAF SITES THROUGH TONIGHT... WHILE THE NAM
SHOWS A WARM/SE WIND FLOW SPREADING NORTH OF ATLANTA DURING THE
AFTERNOON. WILL LEAN TOWARD THE GFS AND HOLD WINDS ESE AT 8-10KTS
TODAY WITH PREVAILING MVFR CIGS AND -SHRA AS AMPLE MOISTURE
CONTINUES TO RIDE OVER THE COOL ESE SURFACE FLOW. MAY HEAR A RUMBLE
OF THUNDER THIS AFTERNOON AS THE WARM FRONT NEARS ATL...BUT WILL
CONTINUE TO JUST MENTION -SHRA FOR NOW. EXPECT IFR CIGS TO RETURN TO
ATL BY 02-03Z THIS EVENING...THEN POSSIBLY LIFR BY 06-08Z TONIGHT
WITH IMPROVEMENT TO MVFR BY 15Z MON...AND POSSIBLY VFR BY 18Z MON.
//ATL CONFIDENCE...12Z UPDATE...
MEDIUM ON ALL ELEMENTS.
39
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 75 69 81 70 / 50 50 50 40
ATLANTA 74 68 79 71 / 70 70 50 40
BLAIRSVILLE 71 65 77 65 / 70 70 50 30
CARTERSVILLE 74 68 80 70 / 80 70 50 30
COLUMBUS 82 71 82 72 / 100 60 50 40
GAINESVILLE 73 68 78 69 / 60 70 50 40
MACON 83 71 83 71 / 50 40 50 40
ROME 75 68 81 70 / 90 80 40 30
PEACHTREE CITY 76 67 80 70 / 60 60 50 40
VIDALIA 86 72 86 72 / 70 50 50 40
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR THE FOLLOWING
ZONES: BARTOW...BIBB...BLECKLEY...BUTTS...CARROLL...CATOOSA...
CHATTAHOOCHEE...CHATTOOGA...CHEROKEE...CLAYTON...COBB...COWETA...
CRAWFORD...CRISP...DADE...DEKALB...DODGE...DOOLY...DOUGLAS...
FANNIN...FAYETTE...FLOYD...GILMER...GORDON...HARALSON...HARRIS...
HEARD...HENRY...HOUSTON...LAMAR...MACON...MARION...MERIWETHER...
MONROE...MURRAY...MUSCOGEE...NORTH FULTON...PAULDING...PEACH...
PICKENS...PIKE...POLK...PULASKI...ROCKDALE...SCHLEY...SOUTH
FULTON...SPALDING...STEWART...SUMTER...TALBOT...TAYLOR...
TELFAIR...TROUP...TWIGGS...UPSON...WALKER...WEBSTER...
WHITFIELD...WILCOX.
&&
$$
SHORT TERM...DEESE
LONG TERM....BDL
AVIATION...DEESE
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
137 AM EDT SUN AUG 18 2013
.UPDATE...
/ISSUED AT 1010 PM EDT SAT AUG 17 2013/
HAVE TWEAKED THE POPS THROUGH 06Z BASED ON RADAR. SINCE HEAVY RAIN
HAS MOVED EAST OF THE CWA FOR THE TIME BEING...HAVE REMOVED HEAVY
RAIN WORDING FOR THE EVENING. NOT SURE HOW RAIN WILL DEVELOP AFTER
06Z SO HAVE MADE NO CHANGES FOR THE 06Z TO 12Z GRIDS. WILL LET FLOOD
WATCH GO ON UNTIL EXPIRATION AT 12Z. FLASH FLOOD GUIDANCE IS SO LOW
IN THE WATCH AREA THAT ANOTHER ROUND OF SHOWERS COULD CAUSE
PROBLEMS.
41
.PREVIOUS...
WET PATTERN TO CONTINUE FOR THE REMAINDER OF THE WEEKEND
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
LOW LEVEL FLOW OVER 300K ISENTROPIC SURFACE HAS BECOME MORE
SOUTHERLY AND CROSS FLOW ALLOWING FOR ENHANCED LIFT NORTH OF
FRONTAL BOUNDARY OVER SOUTH GEORGIA. ENTRENCHED WEDGE ALSO
PROVIDING FOR ADDITIONAL FOCUS FOR THE DEVELOPMENT OF WIDESPREAD
LIGHT TO MODERATE RAIN OVER THE AREA. IN SITU CONDITIONS WITHIN
WEDGE ONLY HELPING TO STRENGTHEN ITS GRIP ON THE LOCAL AREA WITH
TEMPS REMAINING IN THE 60S FOR ALL OF NORTH GEORGIA. HAVE PRETTY
MUCH KEPT STEADY TEMPS IN THE FORECAST FOR THE SHORT TERM PERIOD
WHICH IS SOME 3 TO 6 DEGREES BELOW MODEL GUIDANCE WHICH IS NOT
PERFORMING WELL WITH THIS SUMMER WEDGE SCENARIO.
FOR TONIGHT...AXIS OF PRECIP SHOULD REMAIN IN ROUGHLY THE SAME
LOCATION AS MAIN FEATURES ARE STEADY STATE THROUGH THE OVERNIGHT
HOURS. EXPECT AT LEAST SOME DIURNAL INFLUENCES TO PRECIP COVERAGE
AND WILL GRADUALLY DECREASE...BUT KEEP A LARGE AREA OF LIKELY
THROUGH SUNDAY MORNING. GFS AS WELL AS SHORT TERM HRRR AND WRF IN
AGREEMENT IN DEPICTING A STRONG SHORTWAVE PUSHING OUT OF THE GULF
TOWARD DAYBREAK SUNDAY IN CONJUNCTION WITH A POSSIBLE BREAKDOWN OF
WEDGE FOR THE EXTREME SOUTHERN SECTIONS. SHOULD SEE REDEVELOPMENT
OF SHOWERS ON THE WEST SIDE OF THE FORECAST AREA WITH CONVECTIVE
ELEMENTS INCREASING AS WELL WHICH WILL LEAD TO HIGHER RAINFALL
RATES FROM COLUMBUS TO MACON. UPPER LEVEL FEATURE WILL LIFT NORTH
THROUGH LA GRANGE AND ATLANTA INTO THE AFTERNOON WITH CATEGORICAL
POPS EXPECTED ONCE AGAIN. BEST CAPE REMAINS TO THE SOUTH BUT THE
ADDITION OF SHORTWAVE ENERGY COULD HELP OVERCOME A LACK OF
INSTABILITY FOR THE NORTH AND WILL NEED TO BE MONITORED CLOSELY.
AT THE VERY LEAST...POTENTIAL FOR HEAVIER SUSTAINED SHOWERS WILL
INCREASE SUNDAY. WILL LET MID SHIFT TAKE ANOTHER LOOK BUT MAY NEED
TO EXTEND FLOOD WATCH THROUGH THE REMAINDER OF SUNDAY.
PRETTY MUCH THE SAME INTO SUNDAY NIGHT WITH FOCUS SHIFTING TO
NORTHWEST GA WITH SHORTWAVE. HAVE BACKED OFF OF CATEGORICAL AS
DIURNAL INFLUENCES SHOULD STILL BE IN PLAY BUT STILL PAINTING
LIKELY FOR THE FIRST PART OF THE OVERNIGHT PERIOD.
DEESE
.LONG TERM /MONDAY THROUGH SATURDAY/...
CHANGES TO THE LONG TERM ARE MINOR. HAVE TWEAKED POPS BASED OFF
THE LATEST MODELS. OTHER THAN THAT...ADJUSTED TEMPERATURES DOWN
A DEGREE OR SO FROM GUIDANCE FOR MONDAY. PREVIOUS DISCUSSION
FOLLOWS.
11
/ISSUED AT 452 AM EDT SAT AUG 17 2013/
THE GFS AND ECMWF MODELS REMAIN CONSISTENT IN CONTINUING THIS WET
PATTERN THROUGH THE WEEKEND AND INTO NEXT WEEK. THE STATIONARY
FRONT OVER SOUTH GA WILL MOVE SLOWLY NORTHWARD THROUGH MONDAY/TUE
THEN GRADUALLY DISSIPATE. AN EASTERLY LOW LEVEL FLOW WITH
ATLANTIC MOISTURE AND OVERRUNNING TROPICAL MOISTURE FROM THE GULF
WILL COMBINE WITH A SERIES OF UPPER LEVEL DISTURBANCES TO PRODUCE
WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS THROUGH WED/THU. BEST
TIMING FOR HEAVY RAIN WILL BE IN THE SHORT TERM BUT DEEP TROPICAL
MOISTURE REMAIN OVER THE REGION THROUGH DAY 6/7. PRECIPITABLE
WATERS REMAIN IN THE 1.5 TO 2.0 INCH RANGE THROUGH THU. THE
MODELS ARE TRYING TO ERODE THE WEDGE A BIT TO FAST ALLOWING
INSTABILITIES TO INCREASE ACROSS THE AREA MONDAY. THERE APPEARS TO
BE NO EROSION MECHANISM AND REINFORCEMENT OF THE COLD AIR DAMMING
IS LIKELY TO CONTINUE WITH SOLAR SHELTERING FROM OVERRUNNING
MOISTURE AND ANY EVAPORATIONAL COOLING. THIS WEDGE SHOULD CONTINUE
AT LEAST INTO EARLY NEXT WEEK ALLOWING INSTABILITY INDICES TO STAY
LOW FOR THIS TIME OF YEAR. WILL DEFINITELY NEED TO WATCH THIS AS IT
WILL PLAY A BIG ROLE IN OUR WEATHER PATTERN. TEMPS SHOULD BEGIN TO
REBOUND BY TUE BUT STILL STAY A BIT BELOW SEASONAL NORMS.
01
&&
.HYDROLOGY...
WITH CHANGING MODEL DEPICTIONS OF PRECIP PATTERN COMES CHANGES IN
ANTICIPATED HEAVIEST PRECIP CORE. EXPECTING CONVECTIVE ELEMENTS TO
EMANATE OUT OF THE GULF TONIGHT AND TRANSITION ON THE WESTERN SIDE
OF THE FORECAST AREA SUNDAY. THIS WILL PUT US SLIGHTLY OUT OF
PHASE WITH CURRENT FLOOD WATCH BUT FEELING IS THAT EVEN AREAS OVER
THE SOUTH THAT RECEIVE LESS RAINFALL COULD STILL REALIZE FLOODING
GIVEN EXTREMELY LOW FLASH FLOOD GUIDANCE VALUES. HAVE FLOOD WATCH
GOING THROUGH 12Z SUNDAY NIGHT WITH POSSIBLE EXPANSION BY MID
SHIFT IN BOTH TIME AND AREA.
&&
.CLIMATE...
RECORDS FOR 08-17
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAHN 105 1954 73 1939 76 2010 60 1967
2007 1948
1995
KATL 101 2007 74 1939 76 2010 62 1948
1954 1892 2000 1892
1995
KCSG 102 2000 82 1979 78 2001 66 1961
KMCN 103 2000 76 1939 77 2010 60 1967
1954 1952
RECORDS FOR 08-18
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAHN 103 1995 70 1905 76 1946 62 1979
1976
1964
KATL 101 2000 70 1981 80 2000 62 1964
1995 1905 1879
KCSG 104 2000 78 1981 78 2000 62 1948
1995
KMCN 104 2000 75 1981 77 2000 63 1948
1905 1995
1951
RECORDS FOR 08-19
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAHN 105 1925 75 1981 75 1934 61 1976
KATL 99 1925 69 1897 76 2010 63 1879
2007
1993
KCSG 100 2000 78 1992 78 2010 64 1958
1977
KMCN 101 1983 77 1977 77 1999 64 2006
1925 1976
RECORDS FOR 08-20
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAHN 107 1925 75 1976 77 1983 59 1943
1953
KATL 100 1925 77 1953 80 1925 59 1927
1927
KCSG 102 1983 78 1981 77 2010 66 1961
1948
KMCN 105 1925 74 1897 76 2010 62 1943
1983
1936
&&
.AVIATION...
06Z UPDATE...
LIFR/IFR CIGS/VIS HAVE SETTLED ACROSS MOST TAF SITES EARLY THIS
MORNING...AND THIS CONDITIONS WILL LIKELY PERSIST THROUGH LATE
MORNING...BEFORE IMPROVING TO LOW MVFR CIGS FOR THE AFTERNOON. GFS
HOLDS THE WEDGE IN OVER THE ATLANTA TAF SITES THROUGH TONIGHT...
WHILE THE NAM SHOWS A WARM/SOUTHERLY WIND FLOW SPREADING NORTH OF
ATLANTA DURING THE AFTERNOON. WILL LEAN TOWARD THE GFS AND HOLD
WINDS ESE AT 8-10KTS TODAY WITH PREVAILING -SHRA AS AMPLE MOISTURE
CONTINUES TO OVER THE COOL EASTERLY SURFACE FLOW. MAY HERE A RUMBLE
OF THUNDER DURING THE AFTERNOON AS THE WARM FRONT NEARS ATL...BUT
WILL JUST MENTION -SHRA`S. EXPECT IFR CIGS TO RETURN THIS EVENING
AND PERSIST OVERNIGHT.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM TO HIGH ON ALL ELEMENTS.
39
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 64 71 68 82 / 100 70 50 40
ATLANTA 64 72 69 81 / 80 100 70 50
BLAIRSVILLE 61 69 64 78 / 80 100 70 40
CARTERSVILLE 64 71 68 82 / 70 100 70 40
COLUMBUS 69 81 72 85 / 80 80 60 50
GAINESVILLE 63 71 68 79 / 80 100 70 40
MACON 68 79 71 85 / 100 60 50 50
ROME 66 71 69 84 / 60 100 70 40
PEACHTREE CITY 66 73 69 82 / 80 100 70 50
VIDALIA 69 82 72 87 / 100 40 30 50
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH SUNDAY MORNING FOR THE FOLLOWING
ZONES: BALDWIN...BIBB...BLECKLEY...BUTTS...CHATTAHOOCHEE...
CRAWFORD...CRISP...DODGE...DOOLY...EMANUEL...GLASCOCK...GREENE...
HANCOCK...HARRIS...HOUSTON...JASPER...JEFFERSON...JOHNSON...
JONES...LAMAR...LAURENS...MACON...MARION...MERIWETHER...MONROE...
MONTGOMERY...MORGAN...MUSCOGEE...PEACH...PIKE...PULASKI...
PUTNAM...SCHLEY...STEWART...SUMTER...TALBOT...TALIAFERRO...
TAYLOR...TELFAIR...TOOMBS...TREUTLEN...TROUP...TWIGGS...UPSON...
WARREN...WASHINGTON...WEBSTER...WHEELER...WILCOX...WILKES...
WILKINSON.
&&
$$
SHORT TERM...DEESE
LONG TERM....11
AVIATION...41
AREA FORECAST DISCUSSION
NWS GOODLAND KS
545 PM MDT MON AUG 19 2013
.SHORT TERM...(TONIGHT THROUGH TUESDAY AFTERNOON)
ISSUED AT 203 PM MDT MON AUG 19 2013
AS OF 3 PM CDT...2 PM MDT...SKIES ACROSS THE TRI-STATE AREA WERE
CLEAR. TEMPERATURES HAVE RESPONDED NICELY WITH THE LACK OF CLOUD
COVER AND RANGED FROM THE MID 80S TO LOW 90S. WINDS WERE FROM THE
SOUTHEAST AT 10 TO 15 MPH WITH GUSTS TO 20 MPH. THE RIDGE OF HIGH
PRESSURE OVER THE SOUTHWEST HAS STRENGTHENED SOME TODAY. SUBSIDENCE
ALOFT WAS ENTRENCHED OVER THE REGION AT THIS TIME.
FOR THE REST OF TODAY AND TONIGHT...WITH THE INFLUENCE OF THE RIDGE
AND SUBSIDENCE ALOFT FIRMLY IN PLACE...PRECIPITATION CHANCES WILL BE
NEAR ZERO. THE HRRR KEEPS SUGGESTING A ISOLATED SHOWER OR STORM IS
POSSIBLE OVER CHEYENNE COUNTY COLORADO BUT NO OTHER MODEL IS
PRODUCING PRECIPITATION OVER THE FORECAST AREA. TEMPERATURES FOR
TONIGHT ARE EXPECTED TO FALL INTO THE LOW 60S UNDER MOSTLY CLEAR
SKIES. LIGHT WINDS AND SOME LINGERING LOW LEVEL MOISTURE MAY ALLOW
FOR SOME PATCHY LIGHT FOG TO FORM...MAINLY ACROSS SOUTHWEST
NEBRASKA. DID NOT THINK THIS WAS WORTHY OF A MENTION IN THE GRIDS AS
VISIBILITIES SHOULD NOT FALL LOWER THAN 4 MILES AT WORSE.
FOR TOMORROW...THE RIDGE OF HIGH PRESSURE WILL STRENGTHEN SLIGHTLY
AGAIN. MODELS PROJECT THAT 850 MB TEMPERATURES WILL WARM A DEGREE OR
TWO OVER TODAYS 850 TEMPS SO A SIMILAR RESPONSE IS EXPECTED IN
SURFACE TEMPERATURES. AS A RESULT...HIGH TEMPERATURES IN THE MID TO
UPPER 90S ARE FORECAST UNDER CLEAR SKIES. SOUTH TO SOUTHEAST WINDS
WILL CONTINUE AS A LEE TROUGH TO THE WEST WILL CONTINUE TO INFLUENCE
THE LOW LEVEL FLOW. BASED ON THE UPPER LEVEL PATTERN AND THE LACK OF
A STRONG DISTURBANCE...PRECIPITATION IS NOT FORECAST FOR TOMORROW.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 203 PM MDT MON AUG 19 2013
THE UPPER HIGH CURRENTLY OVER COLORADO/ARIZONA IS FORECAST TO
MOVE EAST TO KANSAS/OKLAHOMA BY THE END OF THE WEEK AND
ULTIMATELY WIND UP OVER ILLINOIS BY THE END OF THE PERIOD. THIS
WILL BE THE PRIMARY FEATURE AFFECTING THE WEATHER...AND IN GENERAL
THIS WILL TRANSLATE INTO A WARM AND DRY PERIOD FOR THE FORECAST
AREA.
ONE POSSIBLE CAVEAT TO THE DRY SCENARIO MENTIONED ABOVE WILL BE A
WEAK SHORT WAVE TROUGH FORECAST BY THE NAM AND GFS TO RIDE OVER
THE TOP OF THE RIDGE WEDNESDAY NIGHT. BOTH MODELS INDICATE A
CHANCE FOR SCATTERED CONVECTION WED NIGHT WHILE THE ECMWF KEEPS
THINGS DRY AND THE GEM SHOWS CONVECTION JUST NORTH OF THE AREA.
FOR NOW HAVE KEPT PREVIOUS FORECAST OF LOW CHANCE POPS DURING THIS
TIME WITH AN EMPHASIS ON THE NORTHWEST AND CENTRAL COUNTIES.
TEMPERATURES WILL BE ABOVE NORMAL IN THE LOW-MID 90S FOR MUCH OF
THE PERIOD WHICH IS 5-8 DEGREES ABOVE NORMAL...WHILE LOWS REMAIN
GENERALLY IN THE 60S.
AT THE END OF THE PERIOD AND INTO THE MIDDLE OF NEXT WEEK WHEN THE
UPPER HIGH HAS SHIFTED EAST...THERE WILL BE AN INCREASING WINDOW
OF OPPORTUNITY FOR SCATTERED CONVECTION AS THE AREA COMES UNDER
MORE OF A WEAK SOUTHWEST FLOW ALOFT. UNTIL THEN...PRECIP CHANCES
LOOK MEAGER.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 530 PM MDT MON AUG 19 2013
VFR CONDITIONS WILL PREVAIL FOR KGLD FOR MOST OF THE TAF PERIOD
WITH A BRIEF PERIOD OF MVFR VISIBILITY IN THE MORNING WHILE KMCK
MAY SEE A BRIEF PERIOD IN THE MORNING OF IFR VISIBILITY AND
CEILINGS. INCLUDED A TEMPO GROUP OF 5SM FOR KGLD FROM 12Z TO 13Z
TO ACCOUNT FOR POSSIBLE FOG DEVELOPING AND A PREVAILING GROUP OF
3SM AT 09Z FOR KMCK WITH A TEMPO GROUP FROM 11Z TO 13Z WITH 1SM
AND CEILINGS AT 800FT. KMCK HAS A PREVAILING GROUP SINCE MULTIPLE
GUIDANCES AGREED WITH VISIBILITY GOING DOWN IN THE MORNING.
SUBSIDENCE...ALONG WITH WINDS GOING VERY LIGHT TO CALM AND DEWPOINTS
IN THE LOW 60S...ADDS TO CONFIDENCE THAT KMCK WILL SEE REDUCTIONS
IN VISIBILITY IN THE MORNING AND KGLD POSSIBLY SEEING SOME REDUCTIONS IN
VISIBILITY. ANY FOG THAT DEVELOPS SHOULD DIMINISH BY MID-MORNING...SO
HAVE VFR CONDITIONS PREVAILING AT 14Z FOR KMCK. TOMORROW AFTERNOON
SOUTHERLY WINDS SHOULD INCREASE...AND HIGH CLOUDS SHOULD RETURN.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...RRH
LONG TERM...DLF
AVIATION...ALW
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1050 AM EDT SUN AUG 18 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL BRING INCREASED CHANCES FOR RAIN
SOUTH OF PITTSBURGH THROUGH THE DAY SUNDAY...AND ALL LOCATIONS
SUNDAY NIGHT AND MONDAY. HIGH PRESSURE BY MID WEEK WILL PROVIDE
GENERALLY DRY AND WARM CONDITIONS.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WITH 1045AM UPDATE...PRIMARY CHANGE WAS TO BACK OFF POPS ACROSS
THE SOUTHEASTERN COUNTIES DURING THE AFTERNOON HOURS. CURRENT
RADAR AND HRRR FORECASTS INDICATE THAT THE RAINFALL ACROSS GARRETT
AND TUCKER COUNTIES HAS ALREADY REACHED ITS PEAK COVERAGE...WITH
RAIN BEGINNING TO PUSH OFF TO THE EAST. HAVE ACCORDINGLY DROPPED
POPS TO CHANCE BY THE AFTERNOON. MEANWHILE...ALTHOUGH RAIN HAS HAD
A HARD TIME PUSHING NORTH OF THE MASON-DIXON LINE SO FAR THIS
MORNING IN OHIO...THE RAIN SHOULD MAKE A RENEWED PUSH DURING THE
AFTERNOON HOURS. PREVIOUS DISCUSSION FOLLOWS.
WHILE THE LEADING SURFACE AND MID-LEVEL SYSTEM THAT WILL AFFECT
THE SOUTHEASTERN PORTIONS OF THE AREA THROUGH THE MORNING WILL
SHIFT OFF TO THE EAST BY AFTERNOON...THE MAIN UPPER LEVEL SYSTEM
WILL REMAIN WELL TO THE WEST OF THE AREA. AS IT SLOWLY
APPROACHES...AND THE JET STREAK MAXIMA CENTERS ITSELF NEARLY ALONG
THE NORTHWESTERN PERIPHERY OF THE FORECAST AREA BY
AFTERNOON...UPPER LEVEL DIVERGENCE SHOULD INCREASE AS THE RIGHT
ENTRANCE REGION OF THIS JET STREAK SURGES NORTHEASTWARD TOWARD OUR
AREA DURING THE AFTERNOON. AS SUCH...THE CHANCE OF SHOWERS LOOKS
TO AGAIN INCREASE FROM THE SOUTHWEST GOING INTO THE AFTERNOON. ALL
IN ALL...A CLOUDY DAY LOOKS TO BE IN STORE ACROSS THE REGION WITH
TEMPERATURES LIKELY HELD BACK FROM RECENT READINGS BECAUSE OF THE
CLOUDS. FRIES
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
UPR LOPRES OVER IN/KY WILL PHASE INTO BELT OF MDT WLYS OVER GRTLKS
RGN SUN NGT THRU MON. ALTHOUGH LIFT WILL DIMINISH THRU THIS TIME...
SHWRS XPCD TO FORM SUN NGT AND SPREAD ACRS MUCH OF THE FCST AREA
THRU MON. POPS WERE INCRD CNTRL/ERN ZONES.
POPS ALSO WERE DECRD MON NGT OWING TO RAPID PHASING AND DEPARTURE
OF THE WAVE AND INFLUENCE OF DVLPG SFC HIPRES IN ITS WAKE. A
SECOND SHRTWV TROF WILL APRCH THE RGN ON TUE...BUT LMTD MSTR WILL
LEAD TO WEAK INSTBY AND LKLY WILL SUPPRESS SHWR DVLPMT.
CLDS WILL LMT HEATING ON MON...WITH MAXIMA IN THE MID-UPR 70S
COMMON. BETTER HEATING XPCD ON TUE AS CLDS WILL BE LMTD TO DIURNAL
CU AMID TEMPS IN THE UPR 70S-LWR 80S.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
DRY WEATHER EXPECTED FOR EARLY PORTION OF LONG TERM WITH EASTERN
RIDGE AND LARGE SFC HIGH. STILL UNCERTAINTY WITH TIMING AND
EFFECTS OF WEAK COLD FRONT WHICH WILL PASS THROUGH THURSDAY
NIGHT/FRIDAY. WILL INCLUDE MENTION OF CHC/SCHC POPS LATE THU INTO
EARLY FRIDAY.
HIGH PRESSURE RETURNS BY THE WEEKEND.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS ARE EXPECTED THROUGH MOST OF THE FORECAST PERIOD.
RESTRICTIONS ARE POSSIBLE LATE THIS AFTERNOON AT ZZV AND
MGW...AND WILL INCLUDE TEMPO GROUP FOR MVFR CIG RESTRICTIONS.
.OUTLOOK.../MONDAY THROUGH THURSDAY/...
INCRG CVRG OF SHWRS AND TSTMS MAY LEAD TO OCNL CIG/VSBY
RESTRICTIONS MON. SFC HIPRES RETURNS BY MID-WK.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
212 AM EDT SUN AUG 18 2013
.SYNOPSIS...
LOW PRESSURE MOVES SLOWLY NORTHEAST ALONG THE MID ATLANTIC COAST
THIS WEEKEND. HIGH PRESSURE RETURNS MONDAY NIGHT THROUGH
WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
LATEST ANALYSIS SHOWED HI PRES CNTRD OVR NEW ENGLAND...WITH WEAK
LO PRES CNTRD JUST SW OF CAPE HATTERAS. CURRENT FCST IN GOOD
SHAPE...AS LATEST RDR INDICATED AREAS OF RAIN N OF THE LO WERE
SPREADING FARTHER NWRD INTO THE CWA. 00Z RUC IN GENERAL AGREEMENT
WITH THE GFS SHOWING THE WEAK LO PRES AREA MOVNG NE OVRNGT TO A
POSITION JUST E OF VA BEACH BY 12Z SUN. THIS WILL RESULT IN AREAS
OF RAIN SHIFTING INTO THE NRN HALF OF THE REGION LATER TNGT INTO
SUN MORNG. SO...WILL HAVE LIKELY TO CAT POPS EVERYWHERE. LO TEMPS
RANGING FM THE MID 60S TO ARND 70.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/...
LO LVL WEDGE TO HANG ON INTO SUN NGT. LO PRES CONTS TO TRACK NE
OFF THE VA/MD CST SUN...THEN NE AWAY FM THE RGN SUN NGT INTO MON.
RA ASSOCIATED W/ THAT LO TO MOVE OVR MNLY ERN PORTIONS OF THE FA
SUN MRNG BEFORE EXITING. MDLS SHOWING AREA OF RA TO PUSH NWD
THROUGH WRN HALF OF VA SUN/SUN NGT. MUCH OF THE FA BY SUN AFTN
THROUGH SUN NGT MAY BE LEFT W/ JUST CLDNS AND ONLY SPOTTY RA. BY
MON...TROUGH ALOFT APPROACHES FM THE W...CROSSING THE RGN LT MON
INTO MON NGT POSSIBLY ENHANCING TSTM PTNTL. ON TUE...SFC HI PRES
TAKES UP RESIDENCE INVOF CAROLINAS/FAR WRN ATLC...W/ WNW FLO
ALOFT. TSTM PTNTL ON TUE LWR ACRS ALL BUT FAR SRN VA/NE NC...W/
OVERALL WX CONDS RETURNING TO THOSE MORE TYPICAL OF AUG.
HI TEMPS SUN FM THE M70S NW TO L80S SE. LO TEMPS SUN NGT FM THE
M60S TO ARND 70F. HI TEMPS MON IN THE L/M80S. HI TEMPS TUE IN THE
M/U80S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
RATHER BENIGN WEATHER IN STORE AS A RATHER FLAT/ZONAL PATTERN
TAKES PLACE DURING THE MID TO LATE WORK WEEK TIMEFRAME. SURFACE
HIGH PRESSURE BECOMES CENTERED JUST SOUTH OF THE AREA ON WED/THU
AND PUSHES THE STALLED COASTAL BOUNDARY FARTHER SOUTH INTO THE
CAROLINAS. A FEW SPOKES OF MOISTURE COULD SNEAK UP INTO NE NC AND
POSSIBLY FAR SRN VA ON WEDNESDAY AND TOUCH OFF DIURNALLY-DRIVEN
AFTERNOON SHOWERS AND THUNDERSTORMS. FOR THURSDAY...A THERMAL
TROUGH DEVELOPS AND SHOULD HELP SHOWERS AND STORMS DEVELOP FURTHER
NORTH INTO CTRL VA THURSDAY AFTERNOON. A LOW PRESSURE SYSTEM
CROSSING THROUGH NEW ENGLAND IS THEN EXPECTED TO DRAG A FRONT
ACROSS THE REGION ON FRIDAY...FOCUSING BETTER PRECIP CHANCES ALONG
THIS BOUNDARY. BEHIND THE FRONT...HIGH PRESSURE RETURNS TO THE
AREA WITH DRIER AND SLIGHTLY COOLER TEMPS ANTICIPATED. HIGHS WILL
GENERALLY BE IN THE MID TO UPPER 80S AND LOWS IN THE 60S (LOWER
70S AT TIMES IN FAR SE VA/NE NC).
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
SFC LOW HAS LOCATED OVER NE NC (PER LATEST SFC OBS) AS HIGH
PRESSURE REMAINS WEDGED INTO CNTRL VA. LATEST RADAR TRENDS SHOW
BROAD AREA OF SCATTERED TO NUMEROUS SHOWERS LIFTING THROUGH THE
LOCAL AREA IN ADVANCE OF THE LOW...BUT LESS COVERAGE OBSERVED OVER
NC EARLY THIS MORNING. SOME OF THE SHOWERS HAVE BEEN HEAVY WITH
SEVERAL SITES REPORTING IFR VSBYS. IN ADDITION...ABUNDANT MOISTURE HAS
RESULTED IN IFR OVC SKIES WITH DECKS GENERALLY 700 TO 1500
FT...EXPECT THE ERN SHORE WHERE CIGS GENERALLY 4 TO 6K FT. SOME
LOCALES HAVE DROPPED TO LIFR CIGS. ALL TAF SITES FORECAST TO DROP
BELOW IFR CIGS THROUGH AT LEAST MID MORNING...AND POSSIBLY CONTINUING
THROUGH EARLY AFTERNOON. THE EXCEPTION WILL BE THE ERN SHORE AND
TAF SITE KSBY. MET GUIDANCE REMAINS RATHER PESSIMISTIC...KEEPING
IFR CIGS THROUGH THE ENTIRE DAY AND INTO TONIGHT (SUN NIGHT).
HOWEVER...WILL IMPROVE CONDITIONS TO MVFR MID TO LATE MORNING
(CIGS 1500-2500 FT AGL) AND INTO THE AFTERNOON AS THE SFC LOW LIFTS
OFFSHORE. WINDS THIS MORNING WILL BE FROM THE E/NE...GENERALLY
AOB 10 KT. THE EXCEPTION WILL BE ALONG THE COAST AS WINDS COULD
GUST UP TO 20 KT. AS THE LOW LIFTS OFFSHORE THROUGH THE
AFTERNOON...WINDS WILL BACK TO THE N-NW AOB 10 KT. EXPECT SHOWERS
TO DIMINISH THROUGH MID MORNING...WITH ONLY ISOLATED TO WIDELY
SCATTERED SHOWERS THIS AFTERNOON AS THE COASTAL FRONT REMAINS
ALONG THE COAST.
STRATUS AND/OR FOG IS POSSIBLE MONDAY MORNING AS THERE IS LITTLE
CHANGE IN THE AMBIENT AIRMASS. A TROUGH SWINGS ACROSS THE AREA
MONDAY AFTERNOON PRODUCING A CHANCE OF SHOWERS AND TSTMS. CONDITIONS
IMPROVE THROUGH MIDWEEK.
&&
.MARINE...
A COASTAL LOW PRESSURE SYSTEM WILL PUSH NORTHEAST UP THE CAROLINA
COASTS AND INTO AREA WATERS TONIGHT AS IT TRAVELS ALONG A STALLED
BOUNDARY. THE COMBINATION OF A TIGHTENING SURFACE PRESSURE
GRADIENT AND COOL MARINE AIR MOVING OVER WARMER WATER TEMPS WILL
RESULT IN BREEZY AND PERSISTENT NE WINDS TONIGHT INTO SUNDAY
MORNING. A SURGE OF 15-20 KT WINDS THIS EVENING INTO SUNDAY
MORNING WILL INCREASE WAVES IN THE CHES BAY TO 4 FT (LOCALLY UP TO 5
FT NEAR THE MOUTH OF THE BAY)...AND INCREASE SEAS TWD 5 FT CLOSER
TO 20 NM FROM CAPE CHARLES LIGHT TO CURRITUCK LIGHT. SCA FLAGS
HAVE BEEN ISSUED FOR THE CHES BAY AND THE RIVERS AS WELL AS THE SRN
COASTAL WATERS THROUGH EARLY SUNDAY MORNING. AS THE COASTAL LOW
PUSHES NORTHEAST OVERNIGHT...THE TIGHTENED PRESSURE GRADIENT WILL
SHIFT NORTHEAST AND CAUSE WIND SPEEDS TO DIMINISH. AS THIS
OCCURS...SEAS WILL ALSO BEGIN TO SUBSIDE BELOW 5 FT JUST BEFORE
DAYBREAK. CHES BAY WILL BE SLOWER TO RESPOND TO SUBSIDING
CONDITIONS AND SCA FLAGS WILL PERSIST HERE THROUGH AT LEAST MID
MORNING BEFORE WINDS/WAVES TAPER OFF.
LOW PRESSURE CONTINUES ITS NORTHEAST TRACK DURING THE REST OF
SUNDAY AND AWAY FROM THE WATERS BY MONDAY MORNING. HIGH PRESSURE
RETURNS TO THE MID ATLANTIC REGION TUESDAY AND WEDNESDAY. FOR
SUNDAY...WINDS WILL CONTINUE TO BE N-NE AOB 15 KT NORTH AND
AOB 10 KT SOUTH. AFTER THAT...WINDS WILL GRADUALLY SHIFT AROUND TO
THE WEST AOB 10 KT WITH WAVES/SEAS AVERAGING 1-3 FT.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EDT THIS AFTERNOON FOR
ANZ630>632-634>636-638-654.
SMALL CRAFT ADVISORY UNTIL 8 AM EDT THIS MORNING FOR ANZ656.
SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 6 PM EDT THIS
EVENING FOR ANZ650-652.
&&
$$
SYNOPSIS...ALB
NEAR TERM...ALB/TMG
SHORT TERM...ALB
LONG TERM...BMD
AVIATION...SAM
MARINE...SAM/JAB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
748 PM EDT MON AUG 19 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 422 PM EDT MON AUG 19 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW ZONAL FLOW ACROSS MUCH OF
SRN CANADA. SHORTWAVE TROF THAT WAS OVER MT/SRN SASKATCHEWAN 24HRS
AGO IS NOW OVER THE UPPER LAKES THOUGH MUCH OF THE ENERGY APPEARS TO
BE SETTLING SSE INTO THE WEAKENING REMNANT OF THE TROF THAT HAS BEEN
OVER THE LOWER MISSISSIPPI VALLEY THE LAST FEW DAYS. WAVE PRODUCED A
CLUSTER OF SHRA/TSRA OVER WRN LAKE SUPERIOR THIS MORNING. THE SHRA
RAPIDLY DIMINISHED AS THEY APPROACHED WRN UPPER MI AND DISSIPATED
SOON AFTER REACHING THAT AREA. SO...FAR NO NEW SHRA/TSRA HAVE
DEVELOPED WITH DAYTIME HEATING.
LATEST SPC MESOANALYSIS SHOWS MLCAPE OF 500-1000J/KG OVER ROUGHLY
THE W HALF OF UPPER MI. VIS SATELLITE IMAGERY SHOWS CU DEVELOPING
OVER THE LAST COUPLE OF HRS...AND LATEST OBS ALONG THE SHORE
INDICATE LAKE BREEZE JUST BEGINNING TO DEVELOP OFF LAKE SUPERIOR.
PERHAPS A FEW SHRA/TSRA MAY YET DEVELOP OVER THE NEXT COUPLE OF HRS
AS LAKE BREEZE MAKES SOME INLAND PROGRESS. SINCE LATEST HIGH RES
RAPID REFRESH MODEL STILL GENERATES SOME CONVECTION OVER THE NCNTRL
LATE THIS AFTN...WILL HOLD ONTO SCHC POPS FOR THE NEXT SEVERAL HRS.
IF ANY SHRA/TSRA DO DEVELOP...THEY WILL DISSIPATE WITH LOSS OF
DAYTIME HEATING...ESPECIALLY SINCE HEIGHTS ARE IN THE PROCESS OF
STEADILY RISING AND DEEP LAYER QVECTOR DIVERGENCE IS DEVELOPING.
THERE IS SOME THETA-E ADVECTION OVERNIGHT...AND THE GEM SUGGESTS
SOME ISOLD CONVECTION LATE TONIGHT/TUE MORNING AT LEADING EDGE OF
THETA-E AXIS APPROACHING WRN UPPER MI. HOWEVER...WITH 850MB WINDS
ANTICYCLONIC AND NOT MUCH OF A LOW-LEVEL JET...POTENTIAL OF ANY
ISOLD CONVECTION LATE SEEMS VERY UNLIKELY. WILL CARRY DRY FCST THRU
THE OVERNIGHT. ALTHOUGH SKIES WILL TURN MOSTLY CLEAR...A LIGHT BUT
STEADY SW WIND AND INCREASED COLUMN MOISTURE WILL WORK TO LIMIT THE
DIURNAL TEMP FALL. UNDER S TO SW WINDS...THE HIGHEST MIN TEMPS WILL
BE IN THE DOWNSLOPE AREAS NEAR LAKE SUPERIOR OVER THE W HALF. EXPECT
MINS IN THE MID 60S THERE. INLAND...MID 50S TO AROUND 60F SHOULD BE
THE RULE.
ON TUE...PRES GRADIENT TIGHTENS A BIT BTWN SFC HIGH OVER THE MID
ATLANTIC STATES AND A LOW PRES TROF MOVING ACROSS THE NRN
PLAINS/SCNTRL CANADA. STRENGTHENING SW FLOW WILL BRING AN INCREASE
IN LOW-LEVEL DWPTS TUE...RESULTING IN A MUCH MORE UNCOMFORTABLE DAY.
MIXING TOWARD 800MB ON FCST SOUNDINGS SUGGESTS MAX TEMPS EASILY INTO
THE MID/UPPER 80S. STRONGER SW WINDS WILL PREVENT LAKE BREEZE
DEVELOPMENT OFF LAKE SUPERIOR AND SHOULD LEAD TO SOME OF THE
WARMEST READINGS IN THE DOWNSLOPE AREAS NEAR THE LAKE. EXPECT SOME
LOCATIONS TO REACH OR JUST EXCEED 90F. S/SW WINDS WILL KEEP
CONDITIONS COOLER NEAR LAKE MICHIGAN. COMBINATION OF TEMPS WELL INTO
THE 80S AND HIGHER DWPTS INTO THE 60S WILL MAKE TUE THE MOST
UNCOMFORTABLE DAY SINCE THE HOT WEATHER STRETCH IN MID JULY. NAM
SHOWS MLCAPE INCREASING TO 2000-3000J/KG TUE AFTN WHILE THE GFS IS
LOWER IN THE 1000-2000J/KG RANGE. LACK OF LAKE BREEEZE DEVELOPMENT
OFF LAKE SUPERIOR WILL BE ONE MISSING FORCING MECHANISM TO TRIGGER
CONVECTION. SINCE THERE ARE HINTS OF A SUBTLE SHORTWAVE MOVING
TOWARD THE UPPER LAKES...OPTED TO MAINTAIN SCHC POPS OVER PORTIONS
OF CNTRL UPPER MI WHERE THERE IS SOME LOW-LEVEL CONVERGENCE AS A
RESULT OF LAKE MICHIGAN LAKE BREEZE COMPONENT. IN THE ABSENCE OF ANY
SHORTWAVE...TUE WILL LIKELY END UP DRY ACROSS THE BOARD.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 422 PM EDT MON AUG 19 2013
NORTHERN STREAM UPPER TROUGH WILL SLIDE THROUGH THE AREA DURING
THE FIRST PART OF THE LONG TERM PERIOD AND LEAD TO A DECENT CHANCE
OF RAIN OVER THE AREA WEDNESDAY.
FIRST FOR TUESDAY NIGHT...THERE MAY BE SOME SHOWERS/THUNDERSTORMS
OVER LAKE SUPERIOR ON AHEAD OF THE COLD FRONT. THIS A CONTINUATION
OF THE CONVECTION THAT DEVELOPS IN SOUTHWEST ONTARIO AND NORTHEAST
MINNESOTA FROM THE AFTERNOON AND A WEAK SHORTWAVE MOVING EAST
ACROSS LAKE SUPERIOR. IN ADDITION...THIS IS ALSO THE AREA OF THE
STRENGTHENING LOW LEVEL JET AND 850-700MB THERMAL RIDGE. WITH STORM
MOTIONS TO THE EAST...WOULD THINK ISLE ROYALE AND NORTHERN LAKE
SUPERIOR WOULD HAVE THE BEST SHOT OF SEEING PRECIPITATION...BUT IT
COULD BRUSH THE KEWEENAW PENINSULA.
ON WEDNESDAY...THE MAIN SHORTWAVE WILL BE MOVING THROUGH SOUTHWEST
ONTARIO AND BE DISCONNECTED FROM THE COLD FRONT MOVING EAST ACROSS
WESTERN LAKE SUPERIOR ON WEDNESDAY MORNING. BUT...THERE ARE HINTS
THAT A SECOND WEAKER WAVE WILL BE SLIDING EAST ACROSS NORTHERN
WISCONSIN AND WESTERN UPPER MICHIGAN IN THE AFTERNOON. IF THIS
OCCURS...IT WOULD ASSIST WITH CONVECTIVE DEVELOPMENT AS THE COLD
FRONT MOVES THROUGH WESTERN/CENTRAL U.P. DURING THE DAY WEDNESDAY.
MODELS SEEM TO HAVE SPED IT UP A TOUCH WITH IT MOVING THROUGH THE
WESTERN U.P. IN THE LATE MORNING OR EARLY AFTERNOON AND THEN THE
CENTRAL U.P. IN THE MID AFTERNOON HOURS. IT THEN EXITS THE AREA
OVER LAKE MICHIGAN DURING THE EVENING. WITH THE WARM...HUMID
AIRMASS...INSTABILITY WILL BE PRETTY GOOD FOR U.P. STANDARDS (MLCAPE
VALUES OF 1500-3000 J/KG DEPENDING ON THE MODEL) WHICH ARE AIDED BY
STEEP MID LEVEL LAPSE RATES (AROUND 7-7.5C/KM FROM 850-700MB). THIS
HELPS BOOST HAIL CAPE VALUES TOWARDS 800 J/KG...BUT WITH FREEZING
LEVELS AROUND 12KFT...IT MAY COUNTERACT THE HAIL POTENTIAL. 0-6KM
AND EFFECTIVE SHEAR VALUES ARE MARGINAL FOR THUNDERSTORM
ORGANIZATION (ONLY AROUND 20-25KTS) AND FAIRLY UNIDIRECTIONAL. 09Z
SREF RUN AGREES WITH THAT BASIC IDEA AND ONLY HAS 50 PERCENT PROBS
FOR EFFECTIVE SHEAR OVER 30KTS. BUT WITH THE COLD FRONT...WOULD
EXPECT SOME CLUSTERS OR LINE OF STORMS TO FORM. STORM MOTION AND
MOVEMENT OF THE COLD FRONT WOULD SUPPORT AN EAST TO SOUTHEAST
MOVEMENT OF THE THUNDERSTORMS. FINALLY...THINK THERE WILL BE SOME
WIND THREAT DUE TO DCAPE VALUES PEAKING OVER THE SOUTH CENTRAL WHERE
THERE WILL BE LESS OF AN INFLUENCE OF CLOUDS TO AID
DESTABILIZATION. THUS...HAVE TRENDED SOME LOCATIONS UP TO
SHOWERS/THUNDERSTORMS LIKELY OVER THE CENTRAL AND WEST-CENTRAL IN
THE AFTERNOON. SPC HAS WESTERN/CENTRAL PORTIONS OF THE U.P. IN A
SLIGHT RISK AND THAT SEEMS REASONABLE AT THIS POINT ALTHOUGH THE
LIMITED SHEAR LEAVES SOME CONCERN FOR WIDESPREAD SEVERE WEATHER.
THE WARM AIR AHEAD OF THE COLD FRONT WILL PRODUCE ANOTHER WARM
DAY...ESPECIALLY OVER THE CENTRAL/EAST (HIGHS IN UPPER 80S OR
LOWER 90S). THE WEST MAY BE LIMITED BY MID CLOUDS MOVING IN AHEAD OF
THE COLD FRONT AND HAVE HIGHS IN THE 80S THERE.
AS THE UPPER TROUGH SHIFT EAST ON THURSDAY...HIGH PRESSURE WILL
BUILD OVER THE AREA WHILE AN UPPER RIDGE BUILD OVER THE NORTH
CENTRAL CONUS AND CENTRAL CANADA. WITH THIS HIGH IN PLACE...EXPECT
ANOTHER PERIOD OF DRIER WEATHER INTO THE FIRST PART OF THE WEEKEND.
A SECONDARY SHORTWAVE MOVES THROUGH ON THURSDAY...BUT WITH THE DRY
ATMOSPHERE...DON/T EXPECT MUCH MORE THAN PASSING MID CLOUDS.
TEMPERATURES DURING THE LONG TERM PERIOD WILL BE COOLEST ON
THURSDAY/FRIDAY BEHIND THE COLD FRONT (HIGHS IN THE
70S)...BUT THEN AS THE HIGH SHIFTS EAST SATURDAY...SOUTH-SOUTHWEST
LOW LEVEL FLOW WILL ALLOW TEMPERATURES TO WARM BACK ABOVE NORMAL
FOR THE WEEKEND (HIGHS AROUND 80S...ALTHOUGH THE LATEST ECMWF IS
SHOWING VALUES NEAR 90).
MODELS DIFFER SOMEWHAT FOR SATURDAY INTO MONDAY...DUE TO CONVECTION
FIRING OR NOT FIRING ALONG THE REMNANTS OF THE COLD FRONT
STRETCHING FROM SOUTHERN MINNESOTA THROUGH THE OHIO RIVER VALLEY.
THE ECMWF HAS BEEN SHOWING THIS FRONT SLOWLY PUSHING NORTH AS A
WARM FRONT THROUGH THE WEEKEND...WHICH WOULD GIVE BETTER CHANCES
FOR PRECIPITATION FOR THE END OF THE WEEKEND INTO THE BEGINNING OF
NEXT WEEK. THE GFS ON THE OTHERHAND AS BEEN SHOWING A STRONGER HIGH
LINGERING OVER THE AREA AND KEEPING THE BROAD AREA OF LOW PRESSURE
FOCUSED IN THE DAKOTAS (SIMILAR TO WHAT WE HAVE EXPERIENCED OVER
THE LAST COUPLE OF DAYS). BOTH MODELS HAVE BEEN VARYING ON THEIR
SOLUTIONS OVER THE LAST COUPLE OF DAYS...SO CONFIDENCE IS LIMITED
THIS FAR OUT. THEREFORE...WILL FOLLOW A GENERAL CONSENSUS WITH
CHANCE OR SLIGHT CHANCE POPS FOR THE WEEKEND INTO EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 742 PM EDT MON AUG 19 2013
WITH RELATIVELY DRY LOW-LEVELS PERSISTING...VFR CONDITIONS ARE
EXPECTED THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW. A WEAK DISTURBANCE
PASSING OVER THE UPPER LAKES HAS PRODUCED AN AREA OF SHRA OVER ERN
LAKE SUPERIOR THIS EVENING...BUT AT THIS POINT EXPECT TAF SITES TO
REMAIN DRY. AS WITH RECENT NIGHTS...INCREASING SW WINDS TONIGHT ABOVE
NOCTURNAL INVERSION WILL APPROACH LLWS CRITERIA. DAYTIME MIXING WILL
RESULT IN SW WIND GUSTS BETWEEN 15 AND 20 KNOTS ON TUESDAY.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 422 PM EDT MON AUG 19 2013
OVERALL...EXPECT WINDS LESS THAN 20KT THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. ONE PERIOD OF STRONGER WINDS (GUSTS TO 20-25KT)
MAY OCCUR TUE NIGHT AS PRES GRADIENT TIGHTENS DUE TO APPROACHING
COLD FRONT. THE ARRIVAL OF MORE HUMID AIR TUE/WED MAY RESULT IN SOME
FOG FORMATION OVER THE COOLER LAKE WATERS. HOWEVER...FOG WILL BE
MUCH MORE LIKELY TO DEVELOP IF SOME SHOWERS OCCUR OVER THE LAKE. ANY
FOG WILL DISSIPATE WED AFTN/EVENING FOLLOWING A COLD FRONTAL PASSAGE
AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...SRF
AVIATION...VOSS
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
411 PM EDT SUN AUG 18 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 409 PM EDT SUN AUG 18 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A RIDGE OVER THE SRN U.S.
ROCKIES WITH A TROF LINGERING OVER THE LWR MISSISSIPPI VALLEY. TO
THE N...ZONAL FLOW DOMINATES SRN CANADA. THERE ARE A COUPLE OF
SHORTWAVES OF INTEREST UPSTREAM IN THIS ZONAL FLOW. THE FIRST IS
OVER SE MANITOBA...AND THE SECOND IS OVER SRN SASKATCHEWAN/ERN MT.
THE FIRST WAVE IS GENERATING CONVECTION OVER FAR SE MANITOBA INTO
ADJACENT NRN ONTARIO. THE SECOND WAVE IS GENERATING SCT SHRA/TSRA
OVER THE WRN DAKOTAS INTO SRN SASKATCHEWAN. CLOSER TO HOME...12Z
SOUNDINGS FROM KGRB/KMPX SHOWED VERY DRY MID LEVELS AND A HEALTHY
CAP...AND THUS NO PCPN IS OCCURRING OVER THE FCST AREA THIS AFTN.
SOME CI AND A RATHER THICK ELEVATED SMOKE LAYER HAS HELD TEMPS DOWN
A BIT FROM EXPECTATIONS WITH READINGS MOSTLY IN THE UPPER 70S TO LOW
80S AS OF 19Z. NEAR LAKE MICHIGAN...SOUTHERLY WINDS OFF THE LAKE ARE
HOLDING TEMPS TO THE LOW/MID 70S.
AFTER A DRY START TO THE SHORT TERM...ATTENTION TURNS TO THE
POTENTIAL OF SHRA/TSRA LATE TONIGHT/MON AS THE PAIR OF SHORTWAVES
CURRENTLY OVER SE MANITOBA AND OVER SRN SASKATCHEWAN/ERN MT MOVES
EASTWARD. INITIAL DRY/CAPPED AIR MASS WILL ENSURE DRY WEATHER ACROSS
THE FCST AREA THIS EVENING. THEN...SW FLOW AHEAD OF SHORTWAVES WILL
TRANSPORT INTO THE UPPER LAKES THE MORE HUMID AIR MASS EVIDENT OVER
THE CNTRL PLAINS THIS MORNING PER 12Z RAOBS. WHILE THE ANTECEDENT
DRY AIR WILL WORK TO DELAY SHRA...DEGREE OF MOISTENING/MAGNITUDE OF
THETA-E ADVECTION SUGGESTS THERE WILL BE SOME RISK OF PCPN. THERE MAY
BE 2 RATHER DISTINCT CLUSTERS OF SCT SHRA/TSRA. THE FIRST ASSOCIATED
WITH THE SE MANITOBA SHORTWAVE COULD REACH NW LAKE SUPERIOR/ISLE
ROYALE AREA EARLY IN THE OVERNIGHT. 850-300MB THICKNESS FIELD
SUGGESTS SOME OF THE CURRENT SHRA/TSRA ASSOCIATED WITH THE WAVE MAY
TAKE A SHARP TURN TO THE RIGHT AS THEY APPROACH THE LAKE...SO IT
REMAINS TO BE SEEN WHERE THESE SHRA MAY END UP. THE SECOND AREA OF
CONVECTION MAY DEVELOP ACROSS NRN MN TOWARD WRN LAKE SUPERIOR LATE
IN THE NIGHT OR MON MORNING WITH THE FOLLOWING SHORTWAVE. IN BOTH
CASES...THERE IS AN INDICATION OF WEAKENING MOISTURE TRANSPORT
EASTWARD WITH TIME...SO SHRA WILL PROBABLY BE ON A DIMINISHING TREND
AS THEY MOVE TOWARD LAKE SUPERIOR/UPPER MI. AT THIS POINT...SEE NO
REASON TO DEVIATE MUCH FROM INHERITED FCST WHICH BROUGHT CHC POPS TO
WRN LAKE SUPERIOR OVERNIGHT AND SCHC POPS TO WRN UPPER MI LATE.
INCREASING COLUMN MOISTURE AND STIRRING S TO SW WINDS WILL WORK TO
KEEP TEMPS HIGHER THAN LAST NIGHT. EXPECT MINS IN THE MID 60S IN THE
DOWNSLOPE AREAS NEAR LAKE SUPERIOR. MINS IN THE MID 50S TO PERHAPS
AS LOW AS 50F IN TRADITIONAL COLD SPOTS SHOULD BE THE RULE INLAND.
ON MON...SHORTWAVE TROF MOVES ACROSS THE UPPER LAKES...BUT WILL BE
WEAKENING AS EVIDENT IN HEIGHT FIELD AND DEEP LAYER FORCING PER
QVECTORS. IF ANY SHRA/TSRA REACH THE W LATE TONIGHT...THEY WILL
LIKELY WEAKEN IN THE MORNING. DURING THE AFTN...MLCAPE IS FCST TO
INCREASE TO POSSSIBLY AS MUCH AS 800-1000J/KG. HOWEVER...WITH
DIMINISHING FORCING AND POTENTIALLY LITTLE IN THE WAY OF LAKE BREEZE
CONVERGENCE...COVERAGE OF ANY DIURNALLY DRIVEN CONVECTION WILL
PROBABLY BE QUITE LIMITED. WILL MAINTAIN JUST SCHC POPS FOR THE AFTN
HRS. MAX TEMPS SHOULD GENERALLY BE IN THE MID 80S PER FCST
SOUNDINGS. OF COURSE...SOUTHERLY WINDS WILL KEEP AREAS NEAR LAKE
MICHIGAN A LITTLE COOLER.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 409 PM EDT SUN AUG 18 2013
STARTING OUT ON MONDAY EVENING THE UPPER AIR PATTERN LOOKS ZONAL
WITH WEAK TROUGHING OVER THE GREAT LAKES AND A RIDGE CENTERED OVER
THE SOUTHWEST CONUS. RIDGE WILL HAVE HARD TIME AMPLIFYING FARTHER
NORTH INTO CANADA THIS WEEK THOUGH AS STRONGER WESTERLIES H5-H3
STREAM ACROSS SOUTHERN TIER OF CANADA OUT OF A MORE OR LESS
PERSISTENT TROUGH SET UP OVER GULF OF ALASKA. EVENTUALLY...WEDNESDAY
NIGHT INTO THURSDAY...LARGER SCALE HEIGHTS FALL SOME AS STRONGER
SHORTWAVE/JET MAX...PART OF WHICH IS STREAMING TOWARD WESTERN SHORE
OF BRITISH COLUMBIA TODAY...DIGS ACROSS NORTHERN ONTARIO TO WESTERN
QUEBEC. SFC COLD FRONT CROSSES UPPER LAKES WEDNESDAY AFTN INTO
WEDNESDAY NIGHT JUST AHEAD OF BETTER HEIGHT FALLS BEGIN LATE
WEDNESDAY. FRONT REPRESENTS BEST CHANCE OF SHRA/TSRA THIS WEEK. HIGH
PRESSURE BUILDS IN BEHIND THE FRONT...BUT QUESTION OF THE DAY IS FOR
HOW LONG. THIS WILL HAVE IMPACT ON FORECAST FOR FRIDAY THROUGH NEXT
WEEKEND.
INITIAL SHORTWAVE THAT ROLLS ACROSS UPPER LAKES ON MONDAY WILL
MAINLY BE EAST OF CWA MONDAY EVENING. SOUNDINGS SHOW PERHAPS MID
CLOUDS THROUGH THE NIGHT BUT WITH SUBSIDENCE IN WAKE OF WAVE...NOT
EXPECTING ANY SHRA/TSRA. ANOTHER WARM NIGHT IN THE 60S WITH STEADY
SW SFC WINDS BENEATH STRONGER WINDS AT 950-925MB. STRONGER WINDS
ALOFT FADE BY TUESDAY AFTN WHICH MAY RESULT IN LOCALIZED BACKING OF
WINDS/LAKE BREEZE ALONG LK SUPERIOR NCNTRL. LAKE MODIFICATION ONLY
ALONG LK MICHIGAN ELSEWHERE. MID CLOUDS MAY DAMPEN SUN INITIALLY...
BUT SHOULD SEE FULL SUN FOR A WHILE BTWN MID MORNING AND MID AFTN
ALLOWING TEMPS TO WARM WELL INTO THE 80S AND PROBABLY TO THE LOWER
90S IN SOME WESTERN CWA LOCATIONS. WILL HAVE TO REACH AT LEAST MID
80S BEFORE CU BEGINS TO FORM AND CONVECTIVE TEMPS ARE ON THE HIGH
SIDE IN THE LOWER 90S. SUPPOSE ALONG THE CONVERGENCE OF LAKE BREEZE
THERE COULD BE AN ISOLD STORM GIVEN MLCAPES OVER 2000J/KG. MOISTURE
THAT IS AROUND PER SOUNDINGS IS VERY SHALLOW SO WITHOUT MUCH
ADDITIONAL LARGE SCALE SUPPORT...THINK CHANCES ARE VERY MINIMAL. IF
A STORM CAN FORM...WOULD HAVE POTENTIAL FOR GUSTY WINDS AS DCAPE
VALUES ARE OVER 1000J/KG. SOUNDINGS POINT TO QUIET...WARM AND HUMID
CONDITIONS TUESDAY NIGHT IN THE WARM SECTOR. MAY SEE A TOUCH OF
FOG...THOUGH SOME WIND JUST OFF THE SFC WILL LIMIT THE EXTENT.
MOIST ONSHORE FLOW MAY LEAD TO MORE FOG CLOSER TO LK MICHIGAN SHORE.
WARM WEATHER CONTINUES ON WEDNESDAY. AFTER A WARM START NEAR 70
DEGREES IN SOME SPOTS IT WILL NOT TAKE MUCH TO SEE READINGS REACH
THOSE SIMILAR TO TUESDAY. COLD FRONT MAKES IT TO MN ARROWHEAD JUST
TO WEST OF DLH BY MIDDAY SO A LOT OF TIME FOR WARMING IN A CAPPED
AIRMASS WITH WARM NOSE AROUND 800MB. SOUNDINGS THROUGH 00Z THURSDAY
LOOK PRETTY DRY WHICH MAKES SENSE AS PRIMARY SHORTWAVE AND MOISTURE
ADVECTION IS NORTH OVR ONTARIO. SW WINDS COULD INCREASE THROUGH THE
DAY AS 950-925MB WINDS INCREASE. STILL THINK TEMPS ON WEDNESDAY MAY
END UP A BIT WARMER THAN TUESDAY WITH LATER ARRIVAL TO FRONT AND AS
H85 TEMPS ARE NEAR +20C TO START THE DAY. DOWNSLOPE MAY LEAD TO
FURTHER WARMING ALONG LK SUPERIOR FROM ONTONAGON TO MUNISING. WILL
BUMP TEMPS INTO UPR 80S ON AVERAGE AND PUSH DOWNSLOPE AREAS TO
AROUND 90. INSTABILITY OBVIOUSLY PRESENT AHEAD OF FRONT WITH THE
VERY WARM TEMPERATURES AND INCREASE IN BLYR MOISTURE /DWPNTS ARE WELL
INTO THE 60S/. RESULT IS MLCAPES 1500-2000J/KG JUST AHEAD OF THE
FRONT. THINK QUALITY OF MOISTURE ULTIMATELY WILL LIMIT CONVECTION
COVERAGE WITH THE FROPA. GIVEN THE INSTABILITY AND DEEP LAYER SHEAR
UP TO 30 KTS THERE IS AT LEAST A MARGINAL POTENTIAL FOR ISOLD SVR
STORMS THROUGH WEDNESDAY EVENING. HIGHER FREEZING LEVEL OVER 14KFT
AND DRY AIR ALOFT /DCAPE OVER 1000J/KG/ POINTS TO STRONG WIND GUSTS
AS MAIN HAZARD.
GOOD AGREEMENT THAT STRONG DRYING/SUBSIDENCE ENDS ANY SHRA/TSRA
OVERNIGHT WEDNESDAY NIGHT WITH THURSDAY STILL LOOKING MUCH COOLER
AND MAINLY DRY AS HIGH PRESSURE BUILDS ACROSS UPPER GREAT LAKES.
GUSTY NORTH TO NORTHWEST WINDS ALONG WITH COLD AIR ADVECTION SHOULD
KICK UP WINDS AND WAVES ON LK SUPERIOR LEADING TO ELEVATED SWIM
RISK. TEMPS WILL STRUGGLE TO 70 DEGREES NEAR LK SUPERIOR AND COULD
REACH LOWER 80S FAR SOUTH.
EVEN THOUGH THURSDAY IS AGREED UPON FOR COOLER AND MAINLY DRY
WEATHER THE FORECAST FOR THURSDAY NIGHT INTO FRIDAY NOT NEARLY AS
CLEAR CUT. GFS MAINTAINS CONTINUITY WITH RECENT RUNS BY SHOWING
SPRAWLING HIGH SHUNTING MAIN FRONTAL BOUNDARY AND FOCUS FOR RETURN
FLOW SHRA/TSRA OVER THE NORTHERN PLAINS AND OHIO VALLEY UNTIL AT
LEAST SATURDAY NIGHT. MEANWHILE...ECMWF UP TO 12Z RUN TODAY WAS
CONSISTENT SINCE 00Z RUN ON 17 AUG INDICATING ONLY A BRIEF HIGH
PRESSURE INTRUSION. ECMWF THEN SHOWS NEXT SHORTWAVE IN WESTERLY FLOW
FORMING A STRONGER SFC-H85 LOW OVER THE NORTHERN PLAINS THURSDAY
WITH ASSOCIATED WARM AIR ADVECTION SHRA/TSRA IMPACTING UPPER LAKES
AS EARLY AS THURSDAY NIGHT AND FRIDAY. ECMWF CERTAINLY ON THE
AMPLIFIED SIDE COMPARED TO ECMWF ENSEMBLE WHICH LOOKS MORE LIKE THE
OPERATIONAL GFS. LATEST ECMWF HAS BACKED AWAY FROM THIS IDEA THOUGH
JUST ADDING MORE UNCERTAINTY TO THIS TIME FRAME. DROPPED POPS FOR
THU NIGHT AND FRIDAY TO SLIGHT CHANCE...BUT WANTED TO KEEP SOME POPS
IN THERE IN CASE MODELS SHIFT BACK TO WETTER IDEA. MUDDLED FORECAST
CONTINUES THROUGH NEXT WEEKEND AS TIMING FOR SYSTEMS MOVING
THROUGH REST OF THE WEEKEND IS STILL OUT OF WHACK BTWN THE GFS AND
ECMWF. CONSENSUS APPROACH WORKS FOR NOW UNTIL THESE DETAILS CAN BE
BETTER SORTED OUT. AFTER THE COOLER TEMPS THURSDAY AND FRIDAY...SEEMS
THAT TEMPS WILL REACH BACK TOWARD NORMAL AND MAYBE EVEN ABOVE NORMAL
IF THERE IS NOT MUCH IN WAY OF CLOUDS OR PRECIPITATION.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 127 PM EDT SUN AUG 18 2013
WITH SW FLOW OF RELATIVELY DRY AIR...EXPECT VFR CONDITIONS TO
PREVAIL THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW. THERE ARE A COUPLE
OF ITEMS OF NOTE. FIRST...INCREASING SW WINDS ABOVE NOCTURNAL
INVERSION TONIGHT WILL APPROACH LLWS CRITERIA. SECOND...DISTURBANCE
APPROACHING FROM THE W MAY BRING ISOLD/SCT CONVECTION INTO UPPER MI
LATE TONIGHT THRU MON MORNING. HOWEVER...AT THIS POINT...CONFIDENCE
IS VERY LOW ON ACTUAL OCCURRENCE OF CONVECTION...AND IF THERE IS ANY
CONVECTION...CONFIDENCE IS EVEN LOWER ON LOCATION/COVERAGE. THUS...
NO MENTION OF SHRA/TSRA WAS INCLUDED IN THIS FCST ISSUANCE.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 409 PM EDT SUN AUG 18 2013
OVERALL...EXPECT WINDS LESS THAN 20 KTS THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. SOME STRONGER SW WIND GUSTS UP TO 20-25KT MAY
OCCUR TONIGHT UNDER A SHARPER PRES GRADIENT AHEAD OF AN APPROACHING
DISTURBANCE. THE ARRIVAL OF MORE HUMID AIR FOR TUE/WED MAY RESULT IN
SOME FOG FORMATION OVER THE COOLER LAKE WATERS. HOWEVER...FOG WILL
BE MUCH MORE LIKELY TO DEVELOP IF SOME SHOWERS OCCUR OVER THE LAKE.
ANY FOG WILL DISSIPATE THU FOLLOWING A COLD FRONTAL PASSAGE AND THE
ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...JLA
AVIATION...ROLFSON
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
128 PM EDT SUN AUG 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 344 AM EDT SUN AUG 18 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW UPR RDG STRETCHING
FM THE NCENTRAL PLAINS INTO THE UPR LKS TO THE S OF ZONAL FLOW OVER
SRN CANADA AND N OF CLOSED LO IN THE MID MS RIVER VALLEY. THE CWA IS
DOMINATED BY THE SW LLVL FLOW ON THE WRN FLANK OF SFC HI PRES OVER
THE NE CONUS. LOCAL 00Z RAOBS DEPICT SHARP SUBSIDENCE INVRN BTWN
H75-85 WITH DRY MID LVLS UNDER THE UPR RDG AXIS. THERE IS A SHRTWV
TRACKING EWD WITHIN THE ZONAL FLOW AND OVER A STNRY FNT IN
ONTARIO...BUT ONLY SOME HI CLDS ON THE SRN EDGE OF THIS DISTURBANCE
ARE SPILLING INTO LK SUP. THE SW FLOW ARND THE SFC HI TO THE E IS
TAPPING FAIRLY DRY LLVL AIR SHOWN ON THE 00Z MPX/GRB RAOBS...WHERE
THE H85 DEWPT WAS 7C AT BOTH SITES. MORE HUMID AIR IS PRESENT OVER
THE CENTRAL HI PLAINS...WHERE THE 00Z H85 DEWPT WAS 16C AT NORTH
PLATTE NEBRASKA.
MAIN FCST CONCERNS IN THE SHORT TERM WL BE TEMPS WITH SPRAWLING RDG
DOMINATING. LATER TNGT...FOCUS SHIFTS TO WHETHER THERE MIGHT BE A
FEW SHRA/TS OVER THE FAR WRN CWA AS SHRTWV EMBEDDED IN ZONAL FLOW
ALF TAPS SOME OF THE MORE HUMID H85 AIR IN THE CENTRAL HI PLAINS.
TDAY...WITH UPR RDG/SUBSIDENCE INVRN/MID LVL DRY AIR LINGERING OVER
UPR MI...EXPECT ANOTHER DRY DAY FOR UPR MI WITH NOTHING MORE THAN
SOME DIURNAL CU. H85 TEMPS ARE FCST TO BE 14-15C BY 00Z MON...UP TO
1C HIER THAN AT 00Z SUN. MIXING TO H8 AS OBSVD YDAY YIELDS HI TEMPS
80-85 AWAY FM THE MODERATING INFLUENCE OF LK MI IN CONTINUED LLVL SW
FLOW. THE DEEP MIXING MIGHT ALLOW FOR SOME GUSTS UP TO 20 MPH OVER
MAINLY THE NW CWA WHERE THE PRES GRADIENT WL BE A BIT TIGHTER/H925
WIND UP TO 20-25KTS. WITH MIN RH DROPPING TO ARND 35 PCT AS DEWPTS
MIX OUT DOWN TO THE LO 50S AND RECENT DRYNESS...FIRE WX CONCERNS WL
BE A BIT ELEVATED IN THAT AREA.
TNGT...MODELS REMAIN CONSISTENT SHOWING SHRTWV EMBEDDED IN ZONAL
FLOW OVER SRN SASKATCHEWAN SHIFTING ESEWD TOWARD THE UPR LKS AND
WEAKENING THE UPR RDG...WITH 00Z-12Z MON H5 HGT FALLS UP TO 40M OVER
THE CWA. AT THE SAME TIME...PERSISTENT SW FLOW IS PROGGED TO TAP
SOMEWHAT MORE HUMID H85 AIR NOW SHOWING UP IN THE CENTRAL PLAINS...
WITH FAIRLY VIGOROUS H85 THETA E ADVECTION INTO THE WRN CWA AFT 06Z.
THE MAIN PROBLEM FOR SHRA/TS DVLPMNT IS THE VERY DRY/STABLE
ANTECEDENT AIRMASS. IN FACT...NAM/GFS FCST SDNGS SHOW THE PROFILE
REMAINING TOO STABLE FOR CONVECTION EVEN OVER THE W EXCEPT PERHAPS
AT IWD TOWARD 12Z. ALTHOUGH THE BULK OF ANY SHRA/TS WL LIKELY BE TO
THE NW TOWARD LOWER HGTS/STNRY FNT IN ONTARIO...OPTED TO RETAIN
GOING SCHC POPS REACHING THE WRN LAND CWA IN THE 09Z-12Z TIME GIVEN
THE ARRIVAL OF THE HIER H85 THETA E...SSI FALLING TO NEAR -2C AND
AXIS OF H85-5 QVECTOR CNVGC FCST TO REACH THIS AREA IN THE 06Z-12Z
TIME. COMBINATION OF INCRSG PWAT TOWARD 1.5 INCH LATE OVER THE W AND
STEADY WSW H925 FLOW WITH WINDS UP TO 25-30KTS WL HOLD MIN TEMPS UP
OVER THE NW IN THE DOWNSLOPE AREAS NEAR LK SUP. BEST CHC FOR SOME
MINS IN THE COOLER 50S WL BE OVER THE INTERIOR SCENTRAL AND E...
WHERE WINDS WL BE LIGHTER AND DRIER AIR WL LINGER LONGEST.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 344 AM EDT SUN AUG 18 2013
MOST ATTENTION IN THE LONG TERM WAS FOCUSED ON TEMPS /MAINLY
THROUGH MID WEEK/ AND PRECIP /MAINLY WED INTO WED NIGHT/ WITH A COLD
FRONT MOVING INTO THE CWA.
LARGE SCALE WISE...AT 12Z MON...THERE WILL BE UPPER LEVEL HIGH
PRESSURE OVER MUCH OF THE CONUS...WITH ZONAL FLOW OVER CANADA. AT
THE SFC...THE CWA WILL BE BETWEEN HIGH PRESSURE COVERING MOST OF THE
CONUS AND A TROUGH OVER SASKATCHEWAN/MANITOBA. A SHORTWAVE WILL BE
OVER THE FAR WRN CWA AT 12Z MON...AND WILL TO THE CENTRAL CWA BY 18Z
MON. PRECIP WITH THE SHORTWAVE IS UNCERTAIN...BUT WILL CONTINUE TO
FAVOR LESSER PRECIP SOLUTIONS DUE TO THE SHORTWAVE PASSING BEFORE
PEAK HEATING AND THAT IT WILL BE PUSHING INTO HIGH PRESSURE.
STILL...MAY BE SOME ISOLATED SHOWERS/THUNDERSTORMS THAT TRY TO POP
UP. HIGHS WILL BE IN THE UPPER 70S TO MID 80S ON MON AS 850MB TEMPS
INCREASE TO AROUND 15C.
THE ZONAL FLOW WILL CONTINUE TO PUSH DYING PIECES OF ENERGY INTO THE
CWA TUE...BUT SAME STORY AS MON WITH THE SHORTWAVE PUSHING INTO THE
HIGH PRESSURE. BY 18Z TUE...850MB TEMPS WILL BE AROUND 18C...SO
HIGHS WILL BE EVEN WARMER IN THE 80S TO AROUND 90.
THE BIGGER QUESTION FOR THE FORECAST COMES ON WED AS A SFC
TROUGH/COLD FRONT MOVES INTO THE CWA LATER IN THE DAY INTO THE EARLY
OVERNIGHT HOURS WED NIGHT. GIVEN FORCING COMBINED WITH INSTABILITY
/CAPE VALUES AROUND 1500-2500 J/KG/ SHOULD LEAD TO SHOWERS AND
THUNDERSTORMS MOVING INTO/DEVELOPING ACROSS THE CWA. INCREASED POPS
SOME AS CONFIDENCE CONTINUES TO IMPROVE. WITH THE INSTABILITY AND
0-6KM BULK SHEAR AROUND 20KTS...A SEVERE STORM OR TWO CANNOT BE
RULED OUT...BUT IT IS STILL PRETTY EARLY FOR THAT DETERMINATION.
HIGHS ON WED LOOK TO BE SIMILAR TO TUESDAY.
POST COLD FROPA...THURSDAY IS THE MOST PREDICTABLE DAY AS COOLER
850MB TEMPS AROUND 14C WILL BE OVER THE CWA. THIS SHOULD RESULT IN
HIGHS IN THE 70S TO AROUND 80 /WARMEST SCENTRAL/. CONFIDENCE
DECREASES SIGNIFICANTLY AFTER THURSDAY AS MODELS SHOW WIDELY
DIFFERENT SOLUTIONS...MAINLY FOR TEMPS. THE ECMWF BRINGS A STRONG
UPPER RIDGE OVER THE REGION FRI INTO SAT...WHICH WOULD RESULT IN
VERY WARM TEMPS AGAIN. THE GFS KEEP THE STRONGEST PART OF THAT RIDGE
WELL TO OUR W...SO TEMPS ARE NOT AS WARM. WILL JUST GO WITH A
CONSENSUS OF MODEL GUIDANCE AT THIS TIME AND FOCUS ON SHORTER TERM
ISSUES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 127 PM EDT SUN AUG 18 2013
WITH SW FLOW OF RELATIVELY DRY AIR...EXPECT VFR CONDITIONS TO
PREVAIL THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW. THERE ARE A COUPLE
OF ITEMS OF NOTE. FIRST...INCREASING SW WINDS ABOVE NOCTURNAL
INVERSION TONIGHT WILL APPROACH LLWS CRITERIA. SECOND...DISTURBANCE
APPROACHING FROM THE W MAY BRING ISOLD/SCT CONVECTION INTO UPPER MI
LATE TONIGHT THRU MON MORNING. HOWEVER...AT THIS POINT...CONFIDENCE
IS VERY LOW ON ACTUAL OCCURRENCE OF CONVECTION...AND IF THERE IS ANY
CONVECTION...CONFIDENCE IS EVEN LOWER ON LOCATION/COVERAGE. THUS...
NO MENTION OF SHRA/TSRA WAS INCLUDED IN THIS FCST ISSUANCE.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 344 AM EDT SUN AUG 18 2013
OVERALL...EXPECT WINDS LESS THAN 20 KTS THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. SOME STRONGER SW WINDS UP TO 20-25 KTS MAY
IMPACT THE W AND NCENTRAL TONIGHT UNDER A SHARPER PRES GRADIENT
AHEAD OF AN APPROACHING DISTURBANCE. THE ARRIVAL OF MORE HUMID AIR
FOR TUE/WED WILL RESULT IN SOME FOG FORMATION OVER THE COOLER LAKE
WATERS. ANY FOG WILL DISSIPATE ON THU FOLLOWING A COLD FRONTAL
PASSAGE AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...TITUS
LONG TERM...KC
AVIATION...ROLFSON
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
724 AM EDT SUN AUG 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 344 AM EDT SUN AUG 18 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW UPR RDG STRETCHING
FM THE NCENTRAL PLAINS INTO THE UPR LKS TO THE S OF ZONAL FLOW OVER
SRN CANADA AND N OF CLOSED LO IN THE MID MS RIVER VALLEY. THE CWA IS
DOMINATED BY THE SW LLVL FLOW ON THE WRN FLANK OF SFC HI PRES OVER
THE NE CONUS. LOCAL 00Z RAOBS DEPICT SHARP SUBSIDENCE INVRN BTWN
H75-85 WITH DRY MID LVLS UNDER THE UPR RDG AXIS. THERE IS A SHRTWV
TRACKING EWD WITHIN THE ZONAL FLOW AND OVER A STNRY FNT IN
ONTARIO...BUT ONLY SOME HI CLDS ON THE SRN EDGE OF THIS DISTURBANCE
ARE SPILLING INTO LK SUP. THE SW FLOW ARND THE SFC HI TO THE E IS
TAPPING FAIRLY DRY LLVL AIR SHOWN ON THE 00Z MPX/GRB RAOBS...WHERE
THE H85 DEWPT WAS 7C AT BOTH SITES. MORE HUMID AIR IS PRESENT OVER
THE CENTRAL HI PLAINS...WHERE THE 00Z H85 DEWPT WAS 16C AT NORTH
PLATTE NEBRASKA.
MAIN FCST CONCERNS IN THE SHORT TERM WL BE TEMPS WITH SPRAWLING RDG
DOMINATING. LATER TNGT...FOCUS SHIFTS TO WHETHER THERE MIGHT BE A
FEW SHRA/TS OVER THE FAR WRN CWA AS SHRTWV EMBEDDED IN ZONAL FLOW
ALF TAPS SOME OF THE MORE HUMID H85 AIR IN THE CENTRAL HI PLAINS.
TDAY...WITH UPR RDG/SUBSIDENCE INVRN/MID LVL DRY AIR LINGERING OVER
UPR MI...EXPECT ANOTHER DRY DAY FOR UPR MI WITH NOTHING MORE THAN
SOME DIURNAL CU. H85 TEMPS ARE FCST TO BE 14-15C BY 00Z MON...UP TO
1C HIER THAN AT 00Z SUN. MIXING TO H8 AS OBSVD YDAY YIELDS HI TEMPS
80-85 AWAY FM THE MODERATING INFLUENCE OF LK MI IN CONTINUED LLVL SW
FLOW. THE DEEP MIXING MIGHT ALLOW FOR SOME GUSTS UP TO 20 MPH OVER
MAINLY THE NW CWA WHERE THE PRES GRADIENT WL BE A BIT TIGHTER/H925
WIND UP TO 20-25KTS. WITH MIN RH DROPPING TO ARND 35 PCT AS DEWPTS
MIX OUT DOWN TO THE LO 50S AND RECENT DRYNESS...FIRE WX CONCERNS WL
BE A BIT ELEVATED IN THAT AREA.
TNGT...MODELS REMAIN CONSISTENT SHOWING SHRTWV EMBEDDED IN ZONAL
FLOW OVER SRN SASKATCHEWAN SHIFTING ESEWD TOWARD THE UPR LKS AND
WEAKENING THE UPR RDG...WITH 00Z-12Z MON H5 HGT FALLS UP TO 40M OVER
THE CWA. AT THE SAME TIME...PERSISTENT SW FLOW IS PROGGED TO TAP
SOMEWHAT MORE HUMID H85 AIR NOW SHOWING UP IN THE CENTRAL PLAINS...
WITH FAIRLY VIGOROUS H85 THETA E ADVECTION INTO THE WRN CWA AFT 06Z.
THE MAIN PROBLEM FOR SHRA/TS DVLPMNT IS THE VERY DRY/STABLE
ANTECEDENT AIRMASS. IN FACT...NAM/GFS FCST SDNGS SHOW THE PROFILE
REMAINING TOO STABLE FOR CONVECTION EVEN OVER THE W EXCEPT PERHAPS
AT IWD TOWARD 12Z. ALTHOUGH THE BULK OF ANY SHRA/TS WL LIKELY BE TO
THE NW TOWARD LOWER HGTS/STNRY FNT IN ONTARIO...OPTED TO RETAIN
GOING SCHC POPS REACHING THE WRN LAND CWA IN THE 09Z-12Z TIME GIVEN
THE ARRIVAL OF THE HIER H85 THETA E...SSI FALLING TO NEAR -2C AND
AXIS OF H85-5 QVECTOR CNVGC FCST TO REACH THIS AREA IN THE 06Z-12Z
TIME. COMBINATION OF INCRSG PWAT TOWARD 1.5 INCH LATE OVER THE W AND
STEADY WSW H925 FLOW WITH WINDS UP TO 25-30KTS WL HOLD MIN TEMPS UP
OVER THE NW IN THE DOWNSLOPE AREAS NEAR LK SUP. BEST CHC FOR SOME
MINS IN THE COOLER 50S WL BE OVER THE INTERIOR SCENTRAL AND E...
WHERE WINDS WL BE LIGHTER AND DRIER AIR WL LINGER LONGEST.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 344 AM EDT SUN AUG 18 2013
MOST ATTENTION IN THE LONG TERM WAS FOCUSED ON TEMPS /MAINLY
THROUGH MID WEEK/ AND PRECIP /MAINLY WED INTO WED NIGHT/ WITH A COLD
FRONT MOVING INTO THE CWA.
LARGE SCALE WISE...AT 12Z MON...THERE WILL BE UPPER LEVEL HIGH
PRESSURE OVER MUCH OF THE CONUS...WITH ZONAL FLOW OVER CANADA. AT
THE SFC...THE CWA WILL BE BETWEEN HIGH PRESSURE COVERING MOST OF THE
CONUS AND A TROUGH OVER SASKATCHEWAN/MANITOBA. A SHORTWAVE WILL BE
OVER THE FAR WRN CWA AT 12Z MON...AND WILL TO THE CENTRAL CWA BY 18Z
MON. PRECIP WITH THE SHORTWAVE IS UNCERTAIN...BUT WILL CONTINUE TO
FAVOR LESSER PRECIP SOLUTIONS DUE TO THE SHORTWAVE PASSING BEFORE
PEAK HEATING AND THAT IT WILL BE PUSHING INTO HIGH PRESSURE.
STILL...MAY BE SOME ISOLATED SHOWERS/THUNDERSTORMS THAT TRY TO POP
UP. HIGHS WILL BE IN THE UPPER 70S TO MID 80S ON MON AS 850MB TEMPS
INCREASE TO AROUND 15C.
THE ZONAL FLOW WILL CONTINUE TO PUSH DYING PIECES OF ENERGY INTO THE
CWA TUE...BUT SAME STORY AS MON WITH THE SHORTWAVE PUSHING INTO THE
HIGH PRESSURE. BY 18Z TUE...850MB TEMPS WILL BE AROUND 18C...SO
HIGHS WILL BE EVEN WARMER IN THE 80S TO AROUND 90.
THE BIGGER QUESTION FOR THE FORECAST COMES ON WED AS A SFC
TROUGH/COLD FRONT MOVES INTO THE CWA LATER IN THE DAY INTO THE EARLY
OVERNIGHT HOURS WED NIGHT. GIVEN FORCING COMBINED WITH INSTABILITY
/CAPE VALUES AROUND 1500-2500 J/KG/ SHOULD LEAD TO SHOWERS AND
THUNDERSTORMS MOVING INTO/DEVELOPING ACROSS THE CWA. INCREASED POPS
SOME AS CONFIDENCE CONTINUES TO IMPROVE. WITH THE INSTABILITY AND
0-6KM BULK SHEAR AROUND 20KTS...A SEVERE STORM OR TWO CANNOT BE
RULED OUT...BUT IT IS STILL PRETTY EARLY FOR THAT DETERMINATION.
HIGHS ON WED LOOK TO BE SIMILAR TO TUESDAY.
POST COLD FROPA...THURSDAY IS THE MOST PREDICTABLE DAY AS COOLER
850MB TEMPS AROUND 14C WILL BE OVER THE CWA. THIS SHOULD RESULT IN
HIGHS IN THE 70S TO AROUND 80 /WARMEST SCENTRAL/. CONFIDENCE
DECREASES SIGNIFICANTLY AFTER THURSDAY AS MODELS SHOW WIDELY
DIFFERENT SOLUTIONS...MAINLY FOR TEMPS. THE ECMWF BRINGS A STRONG
UPPER RIDGE OVER THE REGION FRI INTO SAT...WHICH WOULD RESULT IN
VERY WARM TEMPS AGAIN. THE GFS KEEP THE STRONGEST PART OF THAT RIDGE
WELL TO OUR W...SO TEMPS ARE NOT AS WARM. WILL JUST GO WITH A
CONSENSUS OF MODEL GUIDANCE AT THIS TIME AND FOCUS ON SHORTER TERM
ISSUES.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 723 AM EDT SUN AUG 18 2013
WITH SW FLOW OF DRY AIR...EXPECT VFR CONDITIONS TO PREVAIL AT ALL 3
TAF SITES THIS FCST PERIOD. DAYTIME MIXING WL CAUSE A GUSTY WIND BY
LATE MRNG. THESE WINDS WL DIMINISH TOWARD SUNSET...BUT WITH INCRSG
SW WINDS ABOVE NOCTURNAL INVERSION TNGT...CONDITIONS WILL APPROACH
LLWS CRITERIA.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 344 AM EDT SUN AUG 18 2013
OVERALL...EXPECT WINDS LESS THAN 20 KTS THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. SOME STRONGER SW WINDS UP TO 20-25 KTS MAY
IMPACT THE W AND NCENTRAL TONIGHT UNDER A SHARPER PRES GRADIENT
AHEAD OF AN APPROACHING DISTURBANCE. THE ARRIVAL OF MORE HUMID AIR
FOR TUE/WED WILL RESULT IN SOME FOG FORMATION OVER THE COOLER LAKE
WATERS. ANY FOG WILL DISSIPATE ON THU FOLLOWING A COLD FRONTAL
PASSAGE AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...TITUS
LONG TERM...KC
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
346 AM EDT SUN AUG 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 344 AM EDT SUN AUG 18 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW UPR RDG STRETCHING
FM THE NCENTRAL PLAINS INTO THE UPR LKS TO THE S OF ZONAL FLOW OVER
SRN CANADA AND N OF CLOSED LO IN THE MID MS RIVER VALLEY. THE CWA IS
DOMINATED BY THE SW LLVL FLOW ON THE WRN FLANK OF SFC HI PRES OVER
THE NE CONUS. LOCAL 00Z RAOBS DEPICT SHARP SUBSIDENCE INVRN BTWN
H75-85 WITH DRY MID LVLS UNDER THE UPR RDG AXIS. THERE IS A SHRTWV
TRACKING EWD WITHIN THE ZONAL FLOW AND OVER A STNRY FNT IN
ONTARIO...BUT ONLY SOME HI CLDS ON THE SRN EDGE OF THIS DISTURBANCE
ARE SPILLING INTO LK SUP. THE SW FLOW ARND THE SFC HI TO THE E IS
TAPPING FAIRLY DRY LLVL AIR SHOWN ON THE 00Z MPX/GRB RAOBS...WHERE
THE H85 DEWPT WAS 7C AT BOTH SITES. MORE HUMID AIR IS PRESENT OVER
THE CENTRAL HI PLAINS...WHERE THE 00Z H85 DEWPT WAS 16C AT NORTH
PLATTE NEBRASKA.
MAIN FCST CONCERNS IN THE SHORT TERM WL BE TEMPS WITH SPRAWLING RDG
DOMINATING. LATER TNGT...FOCUS SHIFTS TO WHETHER THERE MIGHT BE A
FEW SHRA/TS OVER THE FAR WRN CWA AS SHRTWV EMBEDDED IN ZONAL FLOW
ALF TAPS SOME OF THE MORE HUMID H85 AIR IN THE CENTRAL HI PLAINS.
TDAY...WITH UPR RDG/SUBSIDENCE INVRN/MID LVL DRY AIR LINGERING OVER
UPR MI...EXPECT ANOTHER DRY DAY FOR UPR MI WITH NOTHING MORE THAN
SOME DIURNAL CU. H85 TEMPS ARE FCST TO BE 14-15C BY 00Z MON...UP TO
1C HIER THAN AT 00Z SUN. MIXING TO H8 AS OBSVD YDAY YIELDS HI TEMPS
80-85 AWAY FM THE MODERATING INFLUENCE OF LK MI IN CONTINUED LLVL SW
FLOW. THE DEEP MIXING MIGHT ALLOW FOR SOME GUSTS UP TO 20 MPH OVER
MAINLY THE NW CWA WHERE THE PRES GRADIENT WL BE A BIT TIGHTER/H925
WIND UP TO 20-25KTS. WITH MIN RH DROPPING TO ARND 35 PCT AS DEWPTS
MIX OUT DOWN TO THE LO 50S AND RECENT DRYNESS...FIRE WX CONCERNS WL
BE A BIT ELEVATED IN THAT AREA.
TNGT...MODELS REMAIN CONSISTENT SHOWING SHRTWV EMBEDDED IN ZONAL
FLOW OVER SRN SASKATCHEWAN SHIFTING ESEWD TOWARD THE UPR LKS AND
WEAKENING THE UPR RDG...WITH 00Z-12Z MON H5 HGT FALLS UP TO 40M OVER
THE CWA. AT THE SAME TIME...PERSISTENT SW FLOW IS PROGGED TO TAP
SOMEWHAT MORE HUMID H85 AIR NOW SHOWING UP IN THE CENTRAL PLAINS...
WITH FAIRLY VIGOROUS H85 THETA E ADVECTION INTO THE WRN CWA AFT 06Z.
THE MAIN PROBLEM FOR SHRA/TS DVLPMNT IS THE VERY DRY/STABLE
ANTECEDENT AIRMASS. IN FACT...NAM/GFS FCST SDNGS SHOW THE PROFILE
REMAINING TOO STABLE FOR CONVECTION EVEN OVER THE W EXCEPT PERHAPS
AT IWD TOWARD 12Z. ALTHOUGH THE BULK OF ANY SHRA/TS WL LIKELY BE TO
THE NW TOWARD LOWER HGTS/STNRY FNT IN ONTARIO...OPTED TO RETAIN
GOING SCHC POPS REACHING THE WRN LAND CWA IN THE 09Z-12Z TIME GIVEN
THE ARRIVAL OF THE HIER H85 THETA E...SSI FALLING TO NEAR -2C AND
AXIS OF H85-5 QVECTOR CNVGC FCST TO REACH THIS AREA IN THE 06Z-12Z
TIME. COMBINATION OF INCRSG PWAT TOWARD 1.5 INCH LATE OVER THE W AND
STEADY WSW H925 FLOW WITH WINDS UP TO 25-30KTS WL HOLD MIN TEMPS UP
OVER THE NW IN THE DOWNSLOPE AREAS NEAR LK SUP. BEST CHC FOR SOME
MINS IN THE COOLER 50S WL BE OVER THE INTERIOR SCENTRAL AND E...
WHERE WINDS WL BE LIGHTER AND DRIER AIR WL LINGER LONGEST.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 344 AM EDT SUN AUG 18 2013
MOST ATTENTION IN THE LONG TERM WAS FOCUSED ON TEMPS /MAINLY
THROUGH MID WEEK/ AND PRECIP /MAINLY WED INTO WED NIGHT/ WITH A COLD
FRONT MOVING INTO THE CWA.
LARGE SCALE WISE...AT 12Z MON...THERE WILL BE UPPER LEVEL HIGH
PRESSURE OVER MUCH OF THE CONUS...WITH ZONAL FLOW OVER CANADA. AT
THE SFC...THE CWA WILL BE BETWEEN HIGH PRESSURE COVERING MOST OF THE
CONUS AND A TROUGH OVER SASKATCHEWAN/MANITOBA. A SHORTWAVE WILL BE
OVER THE FAR WRN CWA AT 12Z MON...AND WILL TO THE CENTRAL CWA BY 18Z
MON. PRECIP WITH THE SHORTWAVE IS UNCERTAIN...BUT WILL CONTINUE TO
FAVOR LESSER PRECIP SOLUTIONS DUE TO THE SHORTWAVE PASSING BEFORE
PEAK HEATING AND THAT IT WILL BE PUSHING INTO HIGH PRESSURE.
STILL...MAY BE SOME ISOLATED SHOWERS/THUNDERSTORMS THAT TRY TO POP
UP. HIGHS WILL BE IN THE UPPER 70S TO MID 80S ON MON AS 850MB TEMPS
INCREASE TO AROUND 15C.
THE ZONAL FLOW WILL CONTINUE TO PUSH DYING PIECES OF ENERGY INTO THE
CWA TUE...BUT SAME STORY AS MON WITH THE SHORTWAVE PUSHING INTO THE
HIGH PRESSURE. BY 18Z TUE...850MB TEMPS WILL BE AROUND 18C...SO
HIGHS WILL BE EVEN WARMER IN THE 80S TO AROUND 90.
THE BIGGER QUESTION FOR THE FORECAST COMES ON WED AS A SFC
TROUGH/COLD FRONT MOVES INTO THE CWA LATER IN THE DAY INTO THE EARLY
OVERNIGHT HOURS WED NIGHT. GIVEN FORCING COMBINED WITH INSTABILITY
/CAPE VALUES AROUND 1500-2500 J/KG/ SHOULD LEAD TO SHOWERS AND
THUNDERSTORMS MOVING INTO/DEVELOPING ACROSS THE CWA. INCREASED POPS
SOME AS CONFIDENCE CONTINUES TO IMPROVE. WITH THE INSTABILITY AND
0-6KM BULK SHEAR AROUND 20KTS...A SEVERE STORM OR TWO CANNOT BE
RULED OUT...BUT IT IS STILL PRETTY EARLY FOR THAT DETERMINATION.
HIGHS ON WED LOOK TO BE SIMILAR TO TUESDAY.
POST COLD FROPA...THURSDAY IS THE MOST PREDICTABLE DAY AS COOLER
850MB TEMPS AROUND 14C WILL BE OVER THE CWA. THIS SHOULD RESULT IN
HIGHS IN THE 70S TO AROUND 80 /WARMEST SCENTRAL/. CONFIDENCE
DECREASES SIGNIFICANTLY AFTER THURSDAY AS MODELS SHOW WIDELY
DIFFERENT SOLUTIONS...MAINLY FOR TEMPS. THE ECMWF BRINGS A STRONG
UPPER RIDGE OVER THE REGION FRI INTO SAT...WHICH WOULD RESULT IN
VERY WARM TEMPS AGAIN. THE GFS KEEP THE STRONGEST PART OF THAT RIDGE
WELL TO OUR W...SO TEMPS ARE NOT AS WARM. WILL JUST GO WITH A
CONSENSUS OF MODEL GUIDANCE AT THIS TIME AND FOCUS ON SHORTER TERM
ISSUES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 126 AM EDT SUN AUG 18 2013
WITH RELATIVELY DRY LOW-LEVELS...VFR CONDITIONS WILL PREVAIL THRU
THE FCST PERIOD AT KIWD/KCMX/KSAW. ONLY ITEM OF NOTE IS THAT
INCREASING SW WINDS ABOVE NOCTURNAL INVERSION EARLY THIS MRNG WILL
APPROACH LLWS CRITERIA.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 344 AM EDT SUN AUG 18 2013
OVERALL...EXPECT WINDS LESS THAN 20 KTS THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. SOME STRONGER SW WINDS UP TO 20-25 KTS MAY
IMPACT THE W AND NCENTRAL TONIGHT UNDER A SHARPER PRES GRADIENT
AHEAD OF AN APPROACHING DISTURBANCE. THE ARRIVAL OF MORE HUMID AIR
FOR TUE/WED WILL RESULT IN SOME FOG FORMATION OVER THE COOLER LAKE
WATERS. ANY FOG WILL DISSIPATE ON THU FOLLOWING A COLD FRONTAL
PASSAGE AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...TITUS
LONG TERM...KC
AVIATION...VOSS
MARINE...KC
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
131 AM EDT SUN AUG 18 2013
.SYNOPSIS...
LOW PRESSURE WILL EXIT NE OF THE AREA THIS EVENING...AND OFF THE
OUTER BANKS BY DAYBREAK SUNDAY. A FRONTAL SYSTEM DRAPED ALONG THE
IMMEDIATE COAST OF THE CAROLINAS AND HIGH PRESSURE RIDGING
SOUTHWEST ACROSS THE CENTRAL CAROLINAS...WILL BOTH PERSIST INTO
EARLY NEXT WEEK. THE FRONT WILL FINALLY DISSIPATE BY MIDWEEK WITH
WEAK HIGH PRESSURE REMAINING ACROSS THE AREA. THE CHANCE FOR
CONVECTION WILL EXIST EACH AFTERNOON AND EVENING THROUGH THE MID
WEEK PERIOD OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 1:30 AM SUNDAY...NO CHANGES TO THE FORECAST WITH THE LATEST
UPDATE. PREVIOUS DISCUSSION FOLLOWS:
MODELS...HAVING A PROBLEM WITH THE CLUSTER OF SHOWERS AND STORMS
JUST WEST OF THE GA-SC BORDER. HRRR SEEMS TO HAVE CAUGHT ON
SOMEWHAT...THE GFS SHOWS A VERY WEAK S/W TROF OR IMPULSE ALOFT AS
A POSSIBLE CAUSE...AND THE NAM INDICATES SUBSIDENCE FOR THE REST
OF TONIGHT. SREF CONTINUES TO ILLUSTRATE VERY LITTLE IN THE
PROBABILITY OF MEASURE-ABLE RAINFALL EAST OF THE I-95 CORRIDOR TO
THE CAROLINA COASTS. WILL STICK WITH THE HRRR OUTPUT...AND RAISE
CHANCE POPS ALONG THE IMMEDIATE COAST AFTER 06Z FOR THE SOUTHERN
COASTAL ZONES. WILL THEN FOLLOW THE HRRR AND INDICATE POPS ALONG
THE COAST REACHING THE NC-SC COASTAL BORDER AFTER DAYBREAK SUN.
TONIGHTS WX MAP/FEATURES RESEMBLES WHAT ONE WOULD OBSERVE DURING
THE LATE FALL THROUGH EARLY SPRING MONTHS. IE. SFC HIGH
NOSING/RIDGING FROM THE NE STATES AND A COASTAL TROF/FRONT ALONG
THE IMMEDIATE COAST. DO NOT EXPECT THE COASTAL FRONT/TROF TO MOVE
ONSHORE OVERNIGHT DUE TO THE CORRELATION WITH SFC AND UPPER
TROFFINESS NOT PRESENT ACROSS TX/OK. AS FOR TONIGHT...A NEARLY
SATURATED ATM TO EXIST WITH PWS 2+ INCHES. THE SFC BASED
INSTABILITY HOWEVER... WILL BE LACKING VIA LATEST HRRR RUNS AND
VARIOUS PROGGED NAMBUFR SOUNDINGS ACROSS THE FA. THE LATEST SREF
PROBABILITY OF MEASURE-ABLE PCPN INDICATES THE BEST PROBS WILL
OCCUR FROM ACROSS THE LEE-SIDE OF THE APPALACHIANS TO WEST OF
I-95. WILL CONTINUE TO OUTLINE ALONG OR WEST OF THE I-95 CORRIDOR
FOR PCPN POPS. AS FOR MIN TEMPS...SLIGHTLY TWEAKED THE IMMEDIATE
COASTAL COUNTIES UPWARDS DUE TO THE CLOSE PROXIMITY TO THE 80
DEGREE SSTS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...THE OLD FRONT WILL REMAIN ACROSS THE AREA
THROUGH THE PERIOD. AN UPPER LOW TO THE WEST WILL MAINTAIN SW FLOW
ALOFT SUNDAY BUT HIGH PRESSURE RIDGING IN FROM THE EAST WILL SHIFT
THE BEST LIFT AND DEEP MOISTURE TO THE WEST AND NORTH OF THE FA.
MAIN FOCUS FOR PRECIP SUNDAY WILL BE THE FRONT AND DIURNAL HEATING
SO FORECAST HAS CHANCE POPS FOR THE AFTERNOON AND EVENING HOURS AND
SLIGHT CHANCE IN THE MORNING AND OVERNIGHT SUNDAY INTO MONDAY
MORNING. MAXIMUMS SUNDAY WILL BE WARMER AND SHOULD REACH THE LOW TO
MID 80S UNDER PARTLY TO MOSTLY CLOUDY.
ON MONDAY...THE UPPER LOW TO THE WEST WILL EJECT NORTHEASTWARD AND
BRING UPPER SUPPORT FOR PRECIPITATION TO THE AREA AGAIN WITH THE
FRONT IN THE AREA. THE FORECAST WILL HAVE SLIGHTLY HIGHER CHANCE
POPS FOR MONDAY THAN SUNDAY...AGAIN FOCUSING ON THE PRIME DIURNAL
PERIOD FOR CONVECTION. MAXIMUMS MONDAY SHOULD REACH THE MID TO
UPPER 80S UNDER PARTLY TO MOSTLY CLOUDY SKIES. MINS SUNDAY NIGHT
AND MONDAY NIGHT SHOULD BE WITHIN A COUPLE DEGREES OF 70.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 3 PM SATURDAY...THE 500 MB UPPER LEVEL RIDGE AXIS TRIES TO
BUILD WESTWARD AND WILL ALIGNED ALONG A LINE FROM MOBILE TO
SAVANNAH AND OUR REGION WILL BE ON THE SOUTHERN FRINGES OF THE
NORTHWEST FLOW ON TUESDAY. AS THE WEEK PROGRESSES AN UPPER LEVEL
TROUGH FORMS ALONG THE EAST COAST ON FRIDAY AND WILL DRIVE THE
HIGH PRESSURE RIDGE SOUTHWARD.
AT THE SURFACE THE FRONTAL BOUNDARY WILL REMAIN AND THE MODELS
CONTINUE TO SHOW THIS WEAKNESS IN THE SURFACE PRESSURE PATTERN
THROUGH AT LEAST FRIDAY. PRECIPITABLE WATERS WILL REMAIN HIGH AND
THE ONLY UPPER LEVEL SUPPORT MAY BE FROM SHORTWAVE IN THE NORTHWEST
FLOW. THE UNCERTAINTY IS HOW MUCH IMPACT THESE DISTURBANCES WILL
HAVE ON THE COAST. SO WITH THE CONFIDENCE NOT HIGH WENT WITH A
CHANCE OF DIURNAL CONVECTION EACH DAY AND ONLY A SLIGHT CHANCE
OVERNIGHT.
MAXIMUM TEMPERATURES ARE EXPECTED TO BE IN THE UPPER 80S TO NEAR 90
EACH DAY AND LOWS IN THE LOWER 70 INLAND AND MID 70S AT THE
BEACHES.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AS OF 06Z...EXPECT PREDOMINANTLY IFR CIGS ACROSS THE CWA OVERNIGHT
WITH A COOL MOIST AIR MASS IN PLACE. SOME MVFR/IFR VSBYS ARE ALSO
POSSIBLE AFTER 06Z...ESPECIALLY AT THE INLAND SITES. KFLO HAS THE
BEST CHANCE OF DEVELOPING LIFR CIGS...AS THE STRATUS HAS BEEN MOST
PERSISTENT AT THIS TERMINAL. KFLO/KLBT MAY ALSO SEE -RA IN THE EARLY
MORNING HOURS AS A SHORTWAVE MOVES OVER THE CENTRAL CAROLINAS.
LIFR/IFR CONDITIONS SHOULD IMPROVE TO MVFR THROUGH THE MORNING
HOURS...BECOMING VFR AT ALL TERMS BY MIDDAY. HAVE ADDED VCSH FOR THE
COASTAL TERMS TO ACCOUNT FOR SCATTERED AFTN SHOWERS AS A WEAK
FRONTAL BOUNDARY LINGERS NEAR THE CAROLINA COAST. THE WINDS WILL BE
LIGHT AND VARIABLE FOR MUCH OF THE PERIOD...BECOMING SOUTH-SOUTHEAST
AOB 10 KTS IN THE AFTN AT KILM/KCRE/KMYR.
EXTENDED OUTLOOK...ISOLATED TO SCATTERED AFTN SHOWERS AND T-STORMS
ARE POSSIBLE THROUGH THE EXTENDED PERIOD.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1:30 AM SUNDAY...NO CHANGES TO THE FORECAST WITH THE LATEST
UPDATE. PREVIOUS DISCUSSION FOLLOWS:
SFC PRESSURE PATTERN AND GRADIENT SOMEWHAT DIFFUSE AND LOOSE
ACROSS THE ATLANTIC WATERS. THE COASTAL FRONTS LOCATION ALONG THE
IMMEDIATE COAST HAS MADE WIND DIRECTIONS RATHER TRICKY. THE SFC PG
WILL REMAIN RATHER LOOSE. AS A RESULT...WIND SPEEDS OVERNIGHT WILL
BE AROUND 10 KT. AS FOR THE DIRECTION...WILL TRY TO FIND A
DOMINATE DIRECTION IN LIEU OF GOING VARIABLE IN DIRECTION.
SIGNIFICANT SEAS WILL PRIMARILY BE A RESULT OF WIND DRIVEN WAVES
RUNNING AT 3 TO 5 SECOND PERIODS...WITH HEIGHTS OF 2 TO 3 FT.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...A WEAK GRADIENT WILL REMAIN OVER THE FORECAST
AREA THROUGH THE PERIOD WITH THE DECAYING FRONT NEARBY. WINDS MAY
WELL BE DRIVEN MORE BY MESOSCALE PROCESSES THAN THE ACTUAL GRADIENT.
THIS MAY MEAN E TO SE WINDS BY DAY AND W TO NW WINDS OVER NIGHT DUE
TO LAND AND SEA BREEZE EFFECTS AND THE SHIFTING POSITION OF THE OLD
FRONT. SPEEDS WILL BE 10 KT OR LESS THROUGH THE PERIOD. SEAS INVOF
2 FT ARE EXPECTED THROUGH THE PERIOD.
LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 3 PM SATURDAY...THE WEAKNESS FROM THE FRONTAL BOUNDARY ALONG
THE COAST APPEARS TO CONTINUE THROUGH THE PERIOD. WITH THIS WEAK
PRESSURE GRADIENT THE WINDS TO BE LESS THAN 10 KNOTS AND VARIABLE.
THE LOCAL WAVE MODEL COUPLED WITH THE WAVEWATCH III MODEL IS SHOWING
SEAS AROUND 2 FEET THROUGH THE ENTIRE PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DCH
NEAR TERM...DCH/REK
SHORT TERM...RAN
LONG TERM...DRH
AVIATION...BJR
MARINE...DCH/REK/DRH/RAN
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
940 PM CDT MON AUG 19 2013
.UPDATE...
ISSUED AT 940 PM CDT MON AUG 19 2013
THE MAIN ISSUE OVERNIGHT WILL BE POSSIBLE FOG FORMATION. CLEAR SKY
AND HIGH LOW LEVEL MOISTURE WILL BE PRESENT...BUT THERE MAY BE
ENOUGH LOW LEVEL MIXING TO PREVENT FOG. 01Z RAP INDICATES A 30-40
KNOT LOW LEVEL JET FROM SOUTH CENTRAL NORTH DAKOTA INTO NORTHWEST
MINNESOTA. ALTHOUGH MIXING WILL NOT BE VERY DEEP DUE TO
NIGHTTIME...THERE SHOULD BE ENOUGH MIXING TO PREVENT CALM WINDS AT
THE SURFACE FOR THIS AREA. FURTHER TO THE SOUTHEAST...AWAY FROM
THE STRONGER 925MB-850MB WINDS...MODELS INDICATE VERY LIGHT FLOW.
AT LEAST PATCHY FOG SHOULD OCCUR HERE...AND INSERTED WITHIN
PORTIONS OF WEST CENTRAL MINNESOTA. THE MAIN AREAS TO WATCH WILL
BE AROUND LAKES AND THE BEMIDJI AREA (WHERE 1 TO 3 INCHES OF RAIN
FELL THIS AFTERNOON). OTHERWISE...MIN TEMPS AND OTHER PARAMETERS
ARE IN GOOD SHAPE.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 340 PM CDT MON AUG 19 2013
PRIMARY CHALLENGES ARE TEMPERATURES THROUGH THE PERIOD AND
PRECIPITATION CHANCES TUESDAY NIGHT. MODELS ARE IN REASONABLE
AGREEMENT AND WILL USE A BLENDED SOLUTION.
A NEARLY STATIONARY ISOLATED CLUSTER OF SHOWERS AND ISOLATED
THUNDERSTORMS HAS DEVELOPED ACROSS SOUTHERN BELTRAMI COUNTY THIS
AFTERNOON...POSSIBLY DUE TO SOME KIND OF LAKE BREEZE INTERACTIONS...
SO ADDED SOME CHANCE POPS IN THIS AREA UNTIL 02 UTC. REST OF THE
FORECAST AREA IS HOT AND DRY WITH LITTLE CLOUD COVER. WHAT LITTLE
CU HAS DEVELOPED WILL DISSIPATE AFTER SUNSET WITH CLEAR SKIES
OVERNIGHT. WITH A WARM AIR MASS AND ELEVATED SOUTHERLY WIND...LOWS
WILL DROP INTO THE MID TO UPPER 60S.
IT/S SAFE TO SAY TUESDAY WILL BE THE HOTTEST DAY SO FAR OF THE
YEAR. AN 850 HPA +28 C THERMAL RIDGE WILL MOVE ACROSS THE FORECAST
AREA AHEAD OF AN ADVANCING COLD FRONT. WITH A DRY ADIABATIC
BOUNDARY LAYER DEEPENING TO 700 TO 600 HPA...IT WILL NOT BE
DIFFICULT FOR MUCH OF THIS HEAT TO MIX TO THE SURFACE. EXPECT
AFTERNOON HIGHS REGION WIDE IN THE LOWER TO MID 90S. ONLY
EXCEPTION MAY BE THE FAR NORTHWEST FORECAST AREA WHICH WILL BE
UNDER THE INFLUENCE OF THE COLD FRONTAL PASSAGE A BIT EARLIER IN
THE DAY. WITH DEW POINT TEMPERATURES ALONG AND AHEAD OF THE FRONT
IN THE 60S...HEAT INDICIES NEARING 100 DEGREES NOT OUT OF THE
QUESTION. WILL HOLD ON A HEAT ADVISORY...BUT SOMETHING TO CONSIDER
IN LATER SHIFTS.
WILL HOLD 20 POPS TUESDAY EVENING AND OVERNIGHT FOR THE CHANCE FOR
SOME CONVECTIVE DEVELOPMENT ALONG AND AHEAD OF THE COLD FRONT.
MLCAPE UP TO 2000 J/KG IS POSSIBLE...BUT 0 TO 6 KM BULK SHEAR IS
RATHER WEAK WITH THE PRIMARY UPPER JET NORTH OF THE CANADIAN
BORDER. VERY WARM MID-LEVEL TEMPERATURES WILL PLAY HAVOC WITH
EROSION OF THE CAP AND DEEP LAYERED MOISTURE IS MISSING. MAIN
INGREDIENTS FOR CONVECTION JUST DON/T SEEM TO ALIGN...SO WHILE
THERE EXISTS SOME CHANCE FOR SHOWERS AND THUNDERSTORMS...
CONFIDENCE IS LOW.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 340 PM CDT MON AUG 19 2013
WEDNESDAY AND THURSDAY WILL BE DRY AS SURFACE HIGH PRESSURE BUILDS
ACROSS THE REGION...BUT COOLER IN THE WAKE OF TUESDAY NIGHT/S FRONTAL
PASSAGE. DAYTIME HIGHS WILL BE IN THE 80S WITH LIGHT WINDS.
OVERNIGHT LOWS WILL RANGE FROM THE MID 50S TO THE MID 60S.
FOR FRIDAY INTO EARLY NEXT WEEK AREA IS ON THE NORTHERN EDGE OF AN
UPPER RIDGE. SEVERAL SHORT WAVES ARE FORECAST TO RIDE FROM THE
PACIFIC COAST 500 MB TROUGH NORTH AND NORTHEAST THRU WYOMING AND
THEN ACROSS NORTH DAKOTA-MINNESOTA THRU THE PERIOD. ANY SHORT WAVE
MAY CAUSE DEVELOPMENT OF ISOLD-SCT TSRA AT ANYTIME THRU THIS PD...SO
WILL GO ALONG WITH CENTRAL REGION ALL BLEND TOOL AND KEEP LOW POPS
IN MOST DAYS FRI-MON. STILL WARM AND HUMID WITH HIGHS IN THE 80S.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 645 PM CDT MON AUG 19 2013
CLEAR SKY EXPECTED THROUGH MUCH OF THE PERIOD. THE POTENTIAL EXISTS
FOR FOG TUESDAY MORNING...BUT CONFIDENCE IS VERY LOW. THE BEST
POTENTIAL SEEMS TO BE ACROSS WEST CENTRAL MINNESOTA WHERE LOW
LEVEL MOISTURE IS A TAD HIGHER...WHICH WOULD AFFECT KBJI (RAIN
ALSO FELL OVER KBJI TODAY). WILL MONITOR THIS POTENTIAL AND
INSERT IF CONFIDENCE INCREASES.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...TG
SHORT TERM...ROGERS
LONG TERM...RIDDLE
AVIATION...TG
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
645 PM CDT MON AUG 19 2013
.UPDATE...
ISSUED AT 645 PM CDT MON AUG 19 2013
THE SHOWERS/THUNDER HAVE ENDED OR MOVED EAST OF BEMIDJI AND WILL
BE ABLE TO GO WITH A DRY FORECAST THE REMAINDER OF THE OVERNIGHT.
NO OTHER UPDATES NEEDED AT THIS POINT. WILL BE MONITORING DEW
POINTS VALUES OVER THE NEXT FEW HOURS AND ADJUST MIN TEMPS WITH
NEXT UPDATE IF NEEDED. FOG FORMATION IS ALSO POSSIBLE...MOST
LIKELY ACROSS PORTIONS OF WEST CENTRAL MINNESOTA WHERE LOW LEVEL
MOISTURE IS A TAD HIGHER. 21Z RAP INDICATES THIS POTENTIAL...AND
WILL MONITOR THE NEXT FEW RAP RUNS IN ORDER TO INCREASE
CONFIDENCE.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 340 PM CDT MON AUG 19 2013
PRIMARY CHALLENGES ARE TEMPERATURES THROUGH THE PERIOD AND
PRECIPITATION CHANCES TUESDAY NIGHT. MODELS ARE IN REASONABLE
AGREEMENT AND WILL USE A BLENDED SOLUTION.
A NEARLY STATIONARY ISOLATED CLUSTER OF SHOWERS AND ISOLATED
THUNDERSTORMS HAS DEVELOPED ACROSS SOUTHERN BELTRAMI COUNTY THIS
AFTERNOON...POSSIBLY DUE TO SOME KIND OF LAKE BREEZE INTERACTIONS...
SO ADDED SOME CHANCE POPS IN THIS AREA UNTIL 02 UTC. REST OF THE
FORECAST AREA IS HOT AND DRY WITH LITTLE CLOUD COVER. WHAT LITTLE
CU HAS DEVELOPED WILL DISSIPATE AFTER SUNSET WITH CLEAR SKIES
OVERNIGHT. WITH A WARM AIR MASS AND ELEVATED SOUTHERLY WIND...LOWS
WILL DROP INTO THE MID TO UPPER 60S.
IT/S SAFE TO SAY TUESDAY WILL BE THE HOTTEST DAY SO FAR OF THE
YEAR. AN 850 HPA +28 C THERMAL RIDGE WILL MOVE ACROSS THE FORECAST
AREA AHEAD OF AN ADVANCING COLD FRONT. WITH A DRY ADIABATIC
BOUNDARY LAYER DEEPENING TO 700 TO 600 HPA...IT WILL NOT BE
DIFFICULT FOR MUCH OF THIS HEAT TO MIX TO THE SURFACE. EXPECT
AFTERNOON HIGHS REGION WIDE IN THE LOWER TO MID 90S. ONLY
EXCEPTION MAY BE THE FAR NORTHWEST FORECAST AREA WHICH WILL BE
UNDER THE INFLUENCE OF THE COLD FRONTAL PASSAGE A BIT EARLIER IN
THE DAY. WITH DEW POINT TEMPERATURES ALONG AND AHEAD OF THE FRONT
IN THE 60S...HEAT INDICIES NEARING 100 DEGREES NOT OUT OF THE
QUESTION. WILL HOLD ON A HEAT ADVISORY...BUT SOMETHING TO CONSIDER
IN LATER SHIFTS.
WILL HOLD 20 POPS TUESDAY EVENING AND OVERNIGHT FOR THE CHANCE FOR
SOME CONVECTIVE DEVELOPMENT ALONG AND AHEAD OF THE COLD FRONT.
MLCAPE UP TO 2000 J/KG IS POSSIBLE...BUT 0 TO 6 KM BULK SHEAR IS
RATHER WEAK WITH THE PRIMARY UPPER JET NORTH OF THE CANADIAN
BORDER. VERY WARM MID-LEVEL TEMPERATURES WILL PLAY HAVOC WITH
EROSION OF THE CAP AND DEEP LAYERED MOISTURE IS MISSING. MAIN
INGREDIENTS FOR CONVECTION JUST DON/T SEEM TO ALIGN...SO WHILE
THERE EXISTS SOME CHANCE FOR SHOWERS AND THUNDERSTORMS...
CONFIDENCE IS LOW.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 340 PM CDT MON AUG 19 2013
WEDNESDAY AND THURSDAY WILL BE DRY AS SURFACE HIGH PRESSURE BUILDS
ACROSS THE REGION...BUT COOLER IN THE WAKE OF TUESDAY NIGHT/S FRONTAL
PASSAGE. DAYTIME HIGHS WILL BE IN THE 80S WITH LIGHT WINDS.
OVERNIGHT LOWS WILL RANGE FROM THE MID 50S TO THE MID 60S.
FOR FRIDAY INTO EARLY NEXT WEEK AREA IS ON THE NORTHERN EDGE OF AN
UPPER RIDGE. SEVERAL SHORT WAVES ARE FORECAST TO RIDE FROM THE
PACIFIC COAST 500 MB TROUGH NORTH AND NORTHEAST THRU WYOMING AND
THEN ACROSS NORTH DAKOTA-MINNESOTA THRU THE PERIOD. ANY SHORT WAVE
MAY CAUSE DEVELOPMENT OF ISOLD-SCT TSRA AT ANYTIME THRU THIS PD...SO
WILL GO ALONG WITH CENTRAL REGION ALL BLEND TOOL AND KEEP LOW POPS
IN MOST DAYS FRI-MON. STILL WARM AND HUMID WITH HIGHS IN THE 80S.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 645 PM CDT MON AUG 19 2013
CLEAR SKY EXPECTED THROUGH MUCH OF THE PERIOD. THE POTENTIAL EXISTS
FOR FOG TUESDAY MORNING...BUT CONFIDENCE IS VERY LOW. THE BEST
POTENTIAL SEEMS TO BE ACROSS WEST CENTRAL MINNESOTA WHERE LOW
LEVEL MOISTURE IS A TAD HIGHER...WHICH WOULD AFFECT KBJI (RAIN
ALSO FELL OVER KBJI TODAY). WILL MONITOR THIS POTENTIAL AND
INSERT IF CONFIDENCE INCREASES.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...TG
SHORT TERM...ROGERS
LONG TERM...RIDDLE
AVIATION...TG
AREA FORECAST DISCUSSION
NWS BISMARCK ND
116 PM CDT SUN AUG 18 2013
.UPDATE...
ISSUED AT 116 PM CDT SUN AUG 18 2013
A SHORTWAVE OVER NORTHEASTERN MONTANA CONTINUES TO GENERATE
ELEVATED SHOWERS WITH ISOLATED THUNDERSTORMS OVER WESTERN NORTH
DAKOTA. THIS WAVE IS STILL PROGGED TO MOVE INTO WESTERN AND
CENTRAL NORTH DAKOTA LATER THIS AFTERNOON.
AT THE SURFACE...DEWPOINTS ARE IN THE UPPER 60S OVER SOUTH CENTRAL
AND SOUTHEASTERN NORTH DAKOTA. LAPS IS ANALYZING SURFACE-BASED
CAPE AROUND 3800 J/KG OVER SOUTH CENTRAL NORTH DAKOTA AS A RESULT.
HOWEVER...IT IS ALSO ANALYZING CIN OF 180 J/KG...WHICH IS QUITE A
HURDLE TO OVERCOME. NEVERTHELESS...SOME CLEARING IS NOTED WEST OF
A LINE FROM MINOT TO DICKINSON TO BOWMAN. ASSUMING THE RELATIVE CLEARING
LINE MAINTAINS ITS CURRENT DIRECTION AND SPEED...THE AREA FROM
BISMARCK TO JAMESTOWN SOUTH SHOULD CLEAR OUT BETWEEN 21Z-24Z
ALLOWING FOR RAPID HEATING DURING THE LATE AFTERNOON. THIS MAY
PRODUCE ENOUGH DIABATIC FORCING TO OVERCOME THE CAP. ANY STORMS
THAT DO DEVELOP SHOULD RAPIDLY BECOME SEVERE. HOWEVER...THERE IS
STILL SOME UNCERTAINTY AS TO WHETHER STORMS WILL DEVELOP IN THE
FIRST PLACE. THEREFORE MAINTAINED THE LOW-END CHANCE POPS.
AS A RESULT...NOT TOO MANY CHANGES WERE MADE TO THE ONGOING
FORECAST. THE UPDATED PRODUCTS HAVE BEEN SENT.
UPDATE ISSUED AT 1025 AM CDT SUN AUG 18 2013
A RATHER COMPLEX WEATHER PATTERN IS SETTING UP OVER WESTERN AND
CENTRAL NORTH DAKOTA TODAY. A SHORTWAVE OVER SOUTHERN MANITOBA HAS
FINALLY GENERATED ENOUGH LIFT FOR THE CAP TO BREAK SOUTH OF LAKE WINNIPEG.
A LINE OF THUNDERSTORMS HAVE DEVELOPED NEAR WINNIPEG ALONG A STALLED
SURFACE BOUNDARY EXTENDING INTO WESTERN AND CENTRAL NORTH DAKOTA.
DO NOT ANTICIPATED THUNDERSTORMS TO DEVELOP SOUTHWESTWARD ALONG
THIS BOUNDARY AS THE CAP (PER 12Z SOUNDING) APPEARS RATHER STRONG
OVER NORTH DAKOTA TODAY.
HOWEVER...A SECOND SHORTWAVE MOVING ACROSS MONTANA IS GENERATING
ELEVATED CONVECTION OVER EASTERN MONTANA INTO NORTHWESTERN SOUTH
DAKOTA. THIS WAVE WILL CONTINUE TO PUSH EAST OVER WESTERN AND
CENTRAL NORTH DAKOTA TODAY. THUNDERSTORMS SHOULD REMAIN ELEVATED
WEST THROUGH THE EARLY AFTERNOON. HOWEVER...AS THE WAVE MOVES INTO
CENTRAL NORTH DAKOTA LATER THIS AFTERNOON...THE CAP IS PROGGED TO
BEGIN TO ERODE AND THUNDERSTORMS COULD BECOME ROOTED IN THE
BOUNDARY LAYER ALONG THE AFOREMENTIONED STALLED FRONT. GIVEN THE
DEEPER CONVECTION POTENTIAL COMBINED WITH MUCAPE VALUES AROUND
2000 J/KG AND DEEP LAYER SHEAR BETWEEN 30-35 KNOTS...THINK THE
SEVERE THREAT WILL DEVELOP PRIMARILY OVER SOUTH CENTRAL AND
SOUTHEASTERN NORTH DAKOTA BETWEEN 22Z-03Z.
UPDATED THE FORECAST TO SPEED UP THE ONSET OF ELEVATED
THUNDERSTORMS WEST THIS MORNING BASED ON RADAR TRENDS. ALSO
REFOCUSED THE TIMING OF SEVERE THUNDERSTORM POTENTIAL TO LATER
THIS AFTERNOON/EVENING. THE UPDATED PRODUCTS HAVE BEEN SENT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN CONCERN IN THE NEAR TERM WILL BE THE CHANCES OF
THUNDERSTORMS...INCLUDING THE POSSIBILITY OF SEVERE WEATHER.
EARLY MORNING WATER VAPOR IMAGERY SHOWED A WAVE MOVING ACROSS
SOUTHERN PARTS OF SASKATCHEWAN / MANITOBA...WITH ANOTHER WAVE IN
NORTHWEST MONTANA. CONVECTION WITH THE CANADIAN WAVE HAS BEEN
SPARSE...AND THE LATEST NAM / RAP KEEPS THE FORECAST AREA DRY
EARLY THIS MORNING AS THE WAVE PASSES. THE BIGGER CONCERN WILL BE
THE MONTANA WAVE AS IT INTERACTS WITH A WEAK BOUNDARY MOVING
THROUGH THE REGION. A FEW SHOWERS / THUNDERSTORMS ARE POSSIBLE IN
WESTERN NORTH DAKOTA LATER SUNDAY MORNING AS THE WAVE
APPROACHES...BUT DO NOT EXPECT THOSE TO BE SEVERE.
THE SEVERE THREAT IS EXPECTED TO INCREASE THIS AFTERNOON AND
EVENING AS THE MONTANA WAVE HELPS INITIATE THUNDERSTORMS ALONG THE
SLOW MOVING BOUNDARY. THAT BEING SAID...THE CAP REMAINS A
POTENTIAL LIMITING FACTOR DUE TO WARM H7 TEMPERATURES. THE NAM
AND GFS DISAGREE IN REGARDS TO HOW FAST THE MID LEVELS COOL
TODAY...WITH THE NAM BEING MORE AGGRESSIVE. THE NAM WAS ALSO
QUICKER TO INITIATE CONVECTION ALONG THE BOUNDARY ON
SATURDAY...AND AFTER SEEING THE LACK OF DEVELOPMENT ACROSS NORTH
DAKOTA...CONFIDENCE IN HOW WIDESPREAD THE CONVECTIVE DEVELOPMENT
WILL BE IS NOT HIGH. WILL CARRY CHANCE POPS NEAR THE BOUNDARY
TOWARDS LATE AFTERNOON / EARLY EVENING...AND LET LATER SHIFTS
MONITOR TRENDS WITH THE CAP AND POTENTIAL DEVELOPMENT.
IN REGARDS TO THE SEVERE WEATHER THREAT...EXPECT THE MAIN THREAT
AREA TO BE FROM THE SOUTH CENTRAL PART OF THE STATE AND TOWARDS
THE JAMES RIVER VALLEY. THE PRIMARY HAZARD SHOULD BE DAMAGING
WINDS WITH INVERTED V SOUNDINGS...WHILE WARM MID LEVEL
TEMPERATURES COULD LIMIT THE HAIL THREAT TO SOME DEGREE. ELEVATED
LIFTED CONDENSATION LEVELS SHOULD ALSO LIMIT THE TORNADO
POTENTIAL. THE THUNDERSTORM CHANCES ARE EXPECTED TO DIMINISH FROM
WEST TO EAST AS THE WAVE PASSES...WITH DRY WEATHER EXPECTED AGAIN
BY LATE TONIGHT.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN HIGHLIGHTS IN THE EXTENDED WILL BE HOT TEMPERATURES
MONDAY AND TUESDAY...WELL INTO 90S...WITH NEAR RECORD HIGHS FOR
BISMARCK TUESDAY. THIS MAY LEAD TO A POSSIBLE HEAT ADVISORY
TUESDAY AFTERNOON ACROSS PORTIONS OF SOUTH CENTRAL NORTH DAKOTA. A
STRONG COLD FRONT WILL FOLLOW FOR TUESDAY NIGHT SUPPRESSING HIGHS
BACK INTO THE 80S FOR THE REST OF THE WEEK.
IN TERMS OF PRECIPITATION CHANCES...THE PATTERN BECOMES MORE ACTIVE
WITH PERIODIC SHOWERS AND THUNDERSTORMS AS A PACIFIC LOW/TROUGH
EJECTS SEVERAL SHORTWAVES VIA A PERSISTENT FETCH OF SOUTHWEST FLOW
ALOFT STRAIGHT INTO NORTH DAKOTA.
FOR MONDAY AND TUESDAY...BEHIND A DEPARTING SHORTWAVE MONDAY MORNING
WILL BE BROAD RIDGING TAKING CONTROL. A LACK OF SHORTWAVE ACTIVITY
MONDAY WITH H85 TEMPS CLIMBING TO AROUND +26C TO +28C...BOTH MONDAY
AND TUESDAY...WILL MAKE THESE THE TWO HOTTEST DAYS IN THE EXTENDED.
PERHAPS A BIT WARMER TUESDAY. LOOKING AT RECORD HIGHS AT THE MAJOR
CITIES MONDAY AND TUESDAY...IT WOULD APPEAR THAT ONLY BISMARCK
WOULD COME CLOSEST TO POSSIBLY TYING A RECORD TUESDAY. THE RECORD IS
100 DEGREES SET BACK IN 1976. WE WILL BE CLOSE TO THAT WITH 98F AS A
FORECAST HIGH TEMPERATURE. WITH MANY SCHOOLS STARTING THIS
WEEK...HAVE TO REALLY CONSIDER THE HEAT IN THE AFTERNOON AS THE HEAT
INDICES WILL BE VERY CLOSE TO 100 DEGREES. WILL HIGHLIGHT THIS IN THE
HAZARDOUS WEATHER OUTLOOK FOR NOW AND BRIEF THE ONCOMING SHIFT THAT
AN ADVISORY MAY BECOME NECESSARY. GFS SOUNDINGS SHOW THAT ENOUGH OF
A CAP REMAINS IN PLACE THROUGH 00Z WEDNESDAY TO INHIBIT CONVECTION.
HAVE DISCOUNTED THE NAM SOLUTION WHICH GENERATES PRECIPITATION EARLY
IN THE DAY...WHILE THE OTHER MODELS KEEP IT DRY DURING THE DAYLIGHT
HOURS.
TUESDAY NIGHT/WEDNESDAY MORNING...A STRONG COLD FRONT WILL PUSH FROM
NORTHWEST TO SOUTHEAST. EXPECT A CHANCE FOR SHOWERS/THUNDERSTORMS
WITH THIS FRONT. H85 TEMPERATURES TAKE A DIGGER WITH +17C IN THE
NORTH WEDNESDAY AFTERNOON TO +20 IN THE SOUTHWEST. SHOULD BE
REFRESHING WITH HIGHS AROUND 80F NORTH TO MID 80S SOUTHWEST. THE
THREAT FOR AN ISOLATED SHOWER/THUNDERSTORM WILL LINGER IN THE SOUTH
THROUGH THE DAY WEDNESDAY.
THURSDAY THROUGH SUNDAY...SOUTHWEST FLOW ALOFT OPENS THE WAY FOR
SEVERAL SHORTWAVE TROUGHS TO MIGRATE THROUGH. UPPER RIDGE WILL BE
DOMINATE IN THE CENTRAL CONUS. THE TIMING OF THE AFOREMENTIONED
SHORTWAVES WILL CHANGE BETWEEN NOW AND LATER IN THE WEEK...BUT THE
HIGHER END CHANCES FOR SHOWERS/THUNDERSTORMS BEGIN TO INCREASE
THURSDAY AND CONTINUE INTO THE WEEKEND. THE ALLBLEND CAPTURES THIS
TREND WELL AND WILL MAINTAIN THAT. THE ECMWF IS A BIT MORE
AGGRESSIVE WITH THE SUCCESSIVE WAVES AND LARGER PRECIPITATION AREAS
VERSUS THE GFS...BUT THE OVERALL PATTERN IN BOTH MODELS IS SIMILAR.
HIGHS WILL REMAIN IN THE 80S WITH LOWS IN THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 116 PM CDT SUN AUG 18 2013
VFR CONDITIONS ARE EXPECTED OVER WESTERN AND CENTRAL NORTH DAKOTA
THROUGH THE TAF PERIOD. LIGHT SHOWERS WITH ISOLATED THUNDERSTORMS
WILL GRADUALLY SPREAD EAST OVER WESTERN AND CENTRAL NORTH DAKOTA
THIS AFTERNOON AND EVENING. HOWEVER...SCATTERED COVERAGE IS
EXPECTED SO ONLY INDICATED VCTS IN THE AFFECTED TAF SITES. AFTER
THIS EVENING...VFR CONDITIONS AND LIGHT/VARIABLE WINDS ARE
EXPECTED OVER WESTERN AND CENTRAL NORTH DAKOTA THROUGH THE
REMAINDER OF THE TAF PERIOD.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TM
SHORT TERM...CK
LONG TERM...KS
AVIATION...AC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1025 AM CDT SUN AUG 18 2013
.UPDATE...
ISSUED AT 1025 AM CDT SUN AUG 18 2013
A RATHER COMPLEX WEATHER PATTERN IS SETTING UP OVER WESTERN AND
CENTRAL NORTH DAKOTA TODAY. A SHORTWAVE OVER SOUTHERN MANITOBA HAS
FINALLY GENERATED ENOUGH LIFT FOR THE CAP TO BREAK SOUTH OF LAKE WINNIPEG.
A LINE OF THUNDERSTORMS HAVE DEVELOPED NEAR WINNIPEG ALONG A STALLED
SURFACE BOUNDARY EXTENDING INTO WESTERN AND CENTRAL NORTH DAKOTA.
DO NOT ANTICIPATED THUNDERSTORMS TO DEVELOP SOUTHWESTWARD ALONG
THIS BOUNDARY AS THE CAP (PER 12Z SOUNDING) APPEARS RATHER STRONG
OVER NORTH DAKOTA TODAY.
HOWEVER...A SECOND SHORTWAVE MOVING ACROSS MONTANA IS GENERATING
ELEVATED CONVECTION OVER EASTERN MONTANA INTO NORTHWESTERN SOUTH
DAKOTA. THIS WAVE WILL CONTINUE TO PUSH EAST OVER WESTERN AND
CENTRAL NORTH DAKOTA TODAY. THUNDERSTORMS SHOULD REMAIN ELEVATED
WEST THROUGH THE EARLY AFTERNOON. HOWEVER...AS THE WAVE MOVES INTO
CENTRAL NORTH DAKOTA LATER THIS AFTERNOON...THE CAP IS PROGGED TO
BEGIN TO ERODE AND THUNDERSTORMS COULD BECOME ROOTED IN THE
BOUNDARY LAYER ALONG THE AFOREMENTIONED STALLED FRONT. GIVEN THE
DEEPER CONVECTION POTENTIAL COMBINED WITH MUCAPE VALUES AROUND
2000 J/KG AND DEEP LAYER SHEAR BETWEEN 30-35 KNOTS...THINK THE
SEVERE THREAT WILL DEVELOP PRIMARILY OVER SOUTH CENTRAL AND
SOUTHEASTERN NORTH DAKOTA BETWEEN 22Z-03Z.
UPDATED THE FORECAST TO SPEED UP THE ONSET OF ELEVATED
THUNDERSTORMS WEST THIS MORNING BASED ON RADAR TRENDS. ALSO
REFOCUSED THE TIMING OF SEVERE THUNDERSTORM POTENTIAL TO LATER
THIS AFTERNOON/EVENING. THE UPDATED PRODUCTS HAVE BEEN SENT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN CONCERN IN THE NEAR TERM WILL BE THE CHANCES OF
THUNDERSTORMS...INCLUDING THE POSSIBILITY OF SEVERE WEATHER.
EARLY MORNING WATER VAPOR IMAGERY SHOWED A WAVE MOVING ACROSS
SOUTHERN PARTS OF SASKATCHEWAN / MANITOBA...WITH ANOTHER WAVE IN
NORTHWEST MONTANA. CONVECTION WITH THE CANADIAN WAVE HAS BEEN
SPARSE...AND THE LATEST NAM / RAP KEEPS THE FORECAST AREA DRY
EARLY THIS MORNING AS THE WAVE PASSES. THE BIGGER CONCERN WILL BE
THE MONTANA WAVE AS IT INTERACTS WITH A WEAK BOUNDARY MOVING
THROUGH THE REGION. A FEW SHOWERS / THUNDERSTORMS ARE POSSIBLE IN
WESTERN NORTH DAKOTA LATER SUNDAY MORNING AS THE WAVE
APPROACHES...BUT DO NOT EXPECT THOSE TO BE SEVERE.
THE SEVERE THREAT IS EXPECTED TO INCREASE THIS AFTERNOON AND
EVENING AS THE MONTANA WAVE HELPS INITIATE THUNDERSTORMS ALONG THE
SLOW MOVING BOUNDARY. THAT BEING SAID...THE CAP REMAINS A
POTENTIAL LIMITING FACTOR DUE TO WARM H7 TEMPERATURES. THE NAM
AND GFS DISAGREE IN REGARDS TO HOW FAST THE MID LEVELS COOL
TODAY...WITH THE NAM BEING MORE AGGRESSIVE. THE NAM WAS ALSO
QUICKER TO INITIATE CONVECTION ALONG THE BOUNDARY ON
SATURDAY...AND AFTER SEEING THE LACK OF DEVELOPMENT ACROSS NORTH
DAKOTA...CONFIDENCE IN HOW WIDESPREAD THE CONVECTIVE DEVELOPMENT
WILL BE IS NOT HIGH. WILL CARRY CHANCE POPS NEAR THE BOUNDARY
TOWARDS LATE AFTERNOON / EARLY EVENING...AND LET LATER SHIFTS
MONITOR TRENDS WITH THE CAP AND POTENTIAL DEVELOPMENT.
IN REGARDS TO THE SEVERE WEATHER THREAT...EXPECT THE MAIN THREAT
AREA TO BE FROM THE SOUTH CENTRAL PART OF THE STATE AND TOWARDS
THE JAMES RIVER VALLEY. THE PRIMARY HAZARD SHOULD BE DAMAGING
WINDS WITH INVERTED V SOUNDINGS...WHILE WARM MID LEVEL
TEMPERATURES COULD LIMIT THE HAIL THREAT TO SOME DEGREE. ELEVATED
LIFTED CONDENSATION LEVELS SHOULD ALSO LIMIT THE TORNADO
POTENTIAL. THE THUNDERSTORM CHANCES ARE EXPECTED TO DIMINISH FROM
WEST TO EAST AS THE WAVE PASSES...WITH DRY WEATHER EXPECTED AGAIN
BY LATE TONIGHT.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN HIGHLIGHTS IN THE EXTENDED WILL BE HOT TEMPERATURES
MONDAY AND TUESDAY...WELL INTO 90S...WITH NEAR RECORD HIGHS FOR
BISMARCK TUESDAY. THIS MAY LEAD TO A POSSIBLE HEAT ADVISORY
TUESDAY AFTERNOON ACROSS PORTIONS OF SOUTH CENTRAL NORTH DAKOTA. A
STRONG COLD FRONT WILL FOLLOW FOR TUESDAY NIGHT SUPPRESSING HIGHS
BACK INTO THE 80S FOR THE REST OF THE WEEK.
IN TERMS OF PRECIPITATION CHANCES...THE PATTERN BECOMES MORE ACTIVE
WITH PERIODIC SHOWERS AND THUNDERSTORMS AS A PACIFIC LOW/TROUGH
EJECTS SEVERAL SHORTWAVES VIA A PERSISTENT FETCH OF SOUTHWEST FLOW
ALOFT STRAIGHT INTO NORTH DAKOTA.
FOR MONDAY AND TUESDAY...BEHIND A DEPARTING SHORTWAVE MONDAY MORNING
WILL BE BROAD RIDGING TAKING CONTROL. A LACK OF SHORTWAVE ACTIVITY
MONDAY WITH H85 TEMPS CLIMBING TO AROUND +26C TO +28C...BOTH MONDAY
AND TUESDAY...WILL MAKE THESE THE TWO HOTTEST DAYS IN THE EXTENDED.
PERHAPS A BIT WARMER TUESDAY. LOOKING AT RECORD HIGHS AT THE MAJOR
CITIES MONDAY AND TUESDAY...IT WOULD APPEAR THAT ONLY BISMARCK
WOULD COME CLOSEST TO POSSIBLY TYING A RECORD TUESDAY. THE RECORD IS
100 DEGREES SET BACK IN 1976. WE WILL BE CLOSE TO THAT WITH 98F AS A
FORECAST HIGH TEMPERATURE. WITH MANY SCHOOLS STARTING THIS
WEEK...HAVE TO REALLY CONSIDER THE HEAT IN THE AFTERNOON AS THE HEAT
INDICES WILL BE VERY CLOSE TO 100 DEGREES. WILL HIGHLIGHT THIS IN THE
HAZARDOUS WEATHER OUTLOOK FOR NOW AND BRIEF THE ONCOMING SHIFT THAT
AN ADVISORY MAY BECOME NECESSARY. GFS SOUNDINGS SHOW THAT ENOUGH OF
A CAP REMAINS IN PLACE THROUGH 00Z WEDNESDAY TO INHIBIT CONVECTION.
HAVE DISCOUNTED THE NAM SOLUTION WHICH GENERATES PRECIPITATION EARLY
IN THE DAY...WHILE THE OTHER MODELS KEEP IT DRY DURING THE DAYLIGHT
HOURS.
TUESDAY NIGHT/WEDNESDAY MORNING...A STRONG COLD FRONT WILL PUSH FROM
NORTHWEST TO SOUTHEAST. EXPECT A CHANCE FOR SHOWERS/THUNDERSTORMS
WITH THIS FRONT. H85 TEMPERATURES TAKE A DIGGER WITH +17C IN THE
NORTH WEDNESDAY AFTERNOON TO +20 IN THE SOUTHWEST. SHOULD BE
REFRESHING WITH HIGHS AROUND 80F NORTH TO MID 80S SOUTHWEST. THE
THREAT FOR AN ISOLATED SHOWER/THUNDERSTORM WILL LINGER IN THE SOUTH
THROUGH THE DAY WEDNESDAY.
THURSDAY THROUGH SUNDAY...SOUTHWEST FLOW ALOFT OPENS THE WAY FOR
SEVERAL SHORTWAVE TROUGHS TO MIGRATE THROUGH. UPPER RIDGE WILL BE
DOMINATE IN THE CENTRAL CONUS. THE TIMING OF THE AFOREMENTIONED
SHORTWAVES WILL CHANGE BETWEEN NOW AND LATER IN THE WEEK...BUT THE
HIGHER END CHANCES FOR SHOWERS/THUNDERSTORMS BEGIN TO INCREASE
THURSDAY AND CONTINUE INTO THE WEEKEND. THE ALLBLEND CAPTURES THIS
TREND WELL AND WILL MAINTAIN THAT. THE ECMWF IS A BIT MORE
AGGRESSIVE WITH THE SUCCESSIVE WAVES AND LARGER PRECIPITATION AREAS
VERSUS THE GFS...BUT THE OVERALL PATTERN IN BOTH MODELS IS SIMILAR.
HIGHS WILL REMAIN IN THE 80S WITH LOWS IN THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 633 AM CDT SUN AUG 18 2013
FOG HAS DEVELOPED EARLY THIS MORNING IN NORTHWEST NORTH DAKOTA.
WILL ADD FOG TO KISN FOR A FEW HOURS THIS MORNING...WITH IMPROVEMENT
EXPECTED BY MID MORNING AS PER THE HRRR. 11-3.9 MICRON SATELLITE
IMAGERY SUGGESTS A SMALL AREA OF STRATUS COULD MOVE INTO KJMS IN THE
NEXT HOUR OR TWO. WILL CARRY A CEILING AROUND 700 FT TO START THE
FORECAST...AND THEN TREND TO VFR BY MID MORNING.
THE CHANCE OF THUNDERSTORMS WILL BE A CONCERN FOR ALL TAF SITES AS
AN UPPER LEVEL DISTURBANCE MOVES ACROSS THE REGION TODAY. WILL
CARRY VCTS AT THE AERODROMES...BUT AM NOT CONFIDENT ENOUGH IN THE
TIMING TO ADD A TEMPO OR PREVAILING GROUP. THE THUNDERSTORM THREAT
SHOULD END FROM WEST TO EAST...WITH DRY WEATHER AGAIN AT ALL
AERODROMES LATER TONIGHT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TM
SHORT TERM...CK
LONG TERM...KS
AVIATION...CK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
633 AM CDT SUN AUG 18 2013
.UPDATE ISSUED AT 633 AM CDT SUN AUG 18 2013...
THE LATEST FOG/STRATUS LOOP SHOWS A COUPLE OF PROBLEM AREAS. ONE
WAS SEEN OVER NORTHWEST NORTH DAKOTA WITH CROSBY HAVING
VISIBILITIES OF LESS THAN A QUARTER OF A MILE...BUT THIS IS
ISOLATED AS TIOGA WAS AT 3 MILES. MID/UPPER LEVEL CLOUDS ARE
APPROACHING AND THIS SHOULD HELP VISIBILITIES IMPROVE A BIT. WILL
MONITOR AND ISSUE A NOW-CAST TO COVER THE ISOLATED DENSE FOG AREA
NEAR CROSBY. THE OTHER AREA WAS IN THE FAR SOUTHEAST...FROM ASHLEY
TO JAMESTOWN WHERE A COMBINATION OF FOG/STRATUS WAS OCCURRING.
LOCAL/REGIONAL RADAR IS NOW SHOWING ISOLATED SHOWERS WORKING THEIR
WAY INTO WESTERN NORTH DAKOTA...WITH LIGHTNING CONFINED FROM GLASGOW
WEST. CURRENT FORECAST REMAINS ON TRACK.
UPDATE ISSUED AT 533 AM CDT SUN AUG 18 2013
SENT A QUICK UPDATE TO ADD PATCHY FOG TO THE NORTHWEST. THE HRRR
VISIBILITY FORECAST APPEARS TO HAVE A GOOD HANDLE ON THE
SITUATION...AND WILL FOLLOW ITS GENERAL TREND. THE REMAINDER OF
THE FORECAST IS STILL ON TRACK.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN CONCERN IN THE NEAR TERM WILL BE THE CHANCES OF
THUNDERSTORMS...INCLUDING THE POSSIBILITY OF SEVERE WEATHER.
EARLY MORNING WATER VAPOR IMAGERY SHOWED A WAVE MOVING ACROSS
SOUTHERN PARTS OF SASKATCHEWAN / MANITOBA...WITH ANOTHER WAVE IN
NORTHWEST MONTANA. CONVECTION WITH THE CANADIAN WAVE HAS BEEN
SPARSE...AND THE LATEST NAM / RAP KEEPS THE FORECAST AREA DRY
EARLY THIS MORNING AS THE WAVE PASSES. THE BIGGER CONCERN WILL BE
THE MONTANA WAVE AS IT INTERACTS WITH A WEAK BOUNDARY MOVING
THROUGH THE REGION. A FEW SHOWERS / THUNDERSTORMS ARE POSSIBLE IN
WESTERN NORTH DAKOTA LATER SUNDAY MORNING AS THE WAVE
APPROACHES...BUT DO NOT EXPECT THOSE TO BE SEVERE.
THE SEVERE THREAT IS EXPECTED TO INCREASE THIS AFTERNOON AND
EVENING AS THE MONTANA WAVE HELPS INITIATE THUNDERSTORMS ALONG THE
SLOW MOVING BOUNDARY. THAT BEING SAID...THE CAP REMAINS A
POTENTIAL LIMITING FACTOR DUE TO WARM H7 TEMPERATURES. THE NAM
AND GFS DISAGREE IN REGARDS TO HOW FAST THE MID LEVELS COOL
TODAY...WITH THE NAM BEING MORE AGGRESSIVE. THE NAM WAS ALSO
QUICKER TO INITIATE CONVECTION ALONG THE BOUNDARY ON
SATURDAY...AND AFTER SEEING THE LACK OF DEVELOPMENT ACROSS NORTH
DAKOTA...CONFIDENCE IN HOW WIDESPREAD THE CONVECTIVE DEVELOPMENT
WILL BE IS NOT HIGH. WILL CARRY CHANCE POPS NEAR THE BOUNDARY
TOWARDS LATE AFTERNOON / EARLY EVENING...AND LET LATER SHIFTS
MONITOR TRENDS WITH THE CAP AND POTENTIAL DEVELOPMENT.
IN REGARDS TO THE SEVERE WEATHER THREAT...EXPECT THE MAIN THREAT
AREA TO BE FROM THE SOUTH CENTRAL PART OF THE STATE AND TOWARDS
THE JAMES RIVER VALLEY. THE PRIMARY HAZARD SHOULD BE DAMAGING
WINDS WITH INVERTED V SOUNDINGS...WHILE WARM MID LEVEL
TEMPERATURES COULD LIMIT THE HAIL THREAT TO SOME DEGREE. ELEVATED
LIFTED CONDENSATION LEVELS SHOULD ALSO LIMIT THE TORNADO
POTENTIAL. THE THUNDERSTORM CHANCES ARE EXPECTED TO DIMINISH FROM
WEST TO EAST AS THE WAVE PASSES...WITH DRY WEATHER EXPECTED AGAIN
BY LATE TONIGHT.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN HIGHLIGHTS IN THE EXTENDED WILL BE HOT TEMPERATURES
MONDAY AND TUESDAY...WELL INTO 90S...WITH NEAR RECORD HIGHS FOR
BISMARCK TUESDAY. THIS MAY LEAD TO A POSSIBLE HEAT ADVISORY
TUESDAY AFTERNOON ACROSS PORTIONS OF SOUTH CENTRAL NORTH DAKOTA. A
STRONG COLD FRONT WILL FOLLOW FOR TUESDAY NIGHT SUPPRESSING HIGHS
BACK INTO THE 80S FOR THE REST OF THE WEEK.
IN TERMS OF PRECIPITATION CHANCES...THE PATTERN BECOMES MORE ACTIVE
WITH PERIODIC SHOWERS AND THUNDERSTORMS AS A PACIFIC LOW/TROUGH
EJECTS SEVERAL SHORTWAVES VIA A PERSISTENT FETCH OF SOUTHWEST FLOW
ALOFT STRAIGHT INTO NORTH DAKOTA.
FOR MONDAY AND TUESDAY...BEHIND A DEPARTING SHORTWAVE MONDAY MORNING
WILL BE BROAD RIDGING TAKING CONTROL. A LACK OF SHORTWAVE ACTIVITY
MONDAY WITH H85 TEMPS CLIMBING TO AROUND +26C TO +28C...BOTH MONDAY
AND TUESDAY...WILL MAKE THESE THE TWO HOTTEST DAYS IN THE EXTENDED.
PERHAPS A BIT WARMER TUESDAY. LOOKING AT RECORD HIGHS AT THE MAJOR
CITIES MONDAY AND TUESDAY...IT WOULD APPEAR THAT ONLY BISMARCK
WOULD COME CLOSEST TO POSSIBLY TYING A RECORD TUESDAY. THE RECORD IS
100 DEGREES SET BACK IN 1976. WE WILL BE CLOSE TO THAT WITH 98F AS A
FORECAST HIGH TEMPERATURE. WITH MANY SCHOOLS STARTING THIS
WEEK...HAVE TO REALLY CONSIDER THE HEAT IN THE AFTERNOON AS THE HEAT
INDICES WILL BE VERY CLOSE TO 100 DEGREES. WILL HIGHLIGHT THIS IN THE
HAZARDOUS WEATHER OUTLOOK FOR NOW AND BRIEF THE ONCOMING SHIFT THAT
AN ADVISORY MAY BECOME NECESSARY. GFS SOUNDINGS SHOW THAT ENOUGH OF
A CAP REMAINS IN PLACE THROUGH 00Z WEDNESDAY TO INHIBIT CONVECTION.
HAVE DISCOUNTED THE NAM SOLUTION WHICH GENERATES PRECIPITATION EARLY
IN THE DAY...WHILE THE OTHER MODELS KEEP IT DRY DURING THE DAYLIGHT
HOURS.
TUESDAY NIGHT/WEDNESDAY MORNING...A STRONG COLD FRONT WILL PUSH FROM
NORTHWEST TO SOUTHEAST. EXPECT A CHANCE FOR SHOWERS/THUNDERSTORMS
WITH THIS FRONT. H85 TEMPERATURES TAKE A DIGGER WITH +17C IN THE
NORTH WEDNESDAY AFTERNOON TO +20 IN THE SOUTHWEST. SHOULD BE
REFRESHING WITH HIGHS AROUND 80F NORTH TO MID 80S SOUTHWEST. THE
THREAT FOR AN ISOLATED SHOWER/THUNDERSTORM WILL LINGER IN THE SOUTH
THROUGH THE DAY WEDNESDAY.
THURSDAY THROUGH SUNDAY...SOUTHWEST FLOW ALOFT OPENS THE WAY FOR
SEVERAL SHORTWAVE TROUGHS TO MIGRATE THROUGH. UPPER RIDGE WILL BE
DOMINATE IN THE CENTRAL CONUS. THE TIMING OF THE AFOREMENTIONED
SHORTWAVES WILL CHANGE BETWEEN NOW AND LATER IN THE WEEK...BUT THE
HIGHER END CHANCES FOR SHOWERS/THUNDERSTORMS BEGIN TO INCREASE
THURSDAY AND CONTINUE INTO THE WEEKEND. THE ALLBLEND CAPTURES THIS
TREND WELL AND WILL MAINTAIN THAT. THE ECMWF IS A BIT MORE
AGGRESSIVE WITH THE SUCCESSIVE WAVES AND LARGER PRECIPITATION AREAS
VERSUS THE GFS...BUT THE OVERALL PATTERN IN BOTH MODELS IS SIMILAR.
HIGHS WILL REMAIN IN THE 80S WITH LOWS IN THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 633 AM CDT SUN AUG 18 2013
FOG HAS DEVELOPED EARLY THIS MORNING IN NORTHWEST NORTH DAKOTA.
WILL ADD FOG TO KISN FOR A FEW HOURS THIS MORNING...WITH IMPROVEMENT
EXPECTED BY MID MORNING AS PER THE HRRR. 11-3.9 MICRON SATELLITE
IMAGERY SUGGESTS A SMALL AREA OF STRATUS COULD MOVE INTO KJMS IN THE
NEXT HOUR OR TWO. WILL CARRY A CEILING AROUND 700 FT TO START THE
FORECAST...AND THEN TREND TO VFR BY MID MORNING.
THE CHANCE OF THUNDERSTORMS WILL BE A CONCERN FOR ALL TAF SITES AS
AN UPPER LEVEL DISTURBANCE MOVES ACROSS THE REGION TODAY. WILL
CARRY VCTS AT THE AERODROMES...BUT AM NOT CONFIDENT ENOUGH IN THE
TIMING TO ADD A TEMPO OR PREVAILING GROUP. THE THUNDERSTORM THREAT
SHOULD END FROM WEST TO EAST...WITH DRY WEATHER AGAIN AT ALL
AERODROMES LATER TONIGHT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KS
SHORT TERM...CK
LONG TERM...KS
AVIATION...CK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
533 AM CDT SUN AUG 18 2013
.UPDATE...
ISSUED AT 533 AM CDT SUN AUG 18 2013
SENT A QUICK UPDATE TO ADD PATCHY FOG TO THE NORTHWEST. THE HRRR
VISIBLITY FORECAST APPEARS TO HAVE A GOOD HANDLE ON THE
SITUATION...AND WILL FOLLOW ITS GENERAL TREND. THE REMAINDER OF
THE FORECAST IS STILL ON TRACK.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN CONCERN IN THE NEAR TERM WILL BE THE CHANCES OF
THUNDERSTORMS...INCLUDING THE POSSIBILITY OF SEVERE WEATHER.
EARLY MORNING WATER VAPOR IMAGERY SHOWED A WAVE MOVING ACROSS
SOUTHERN PARTS OF SASKATCHEWAN / MANITOBA...WITH ANOTHER WAVE IN
NORTHWEST MONTANA. CONVECTION WITH THE CANADIAN WAVE HAS BEEN
SPARSE...AND THE LATEST NAM / RAP KEEPS THE FORECAST AREA DRY
EARLY THIS MORNING AS THE WAVE PASSES. THE BIGGER CONCERN WILL BE
THE MONTANA WAVE AS IT INTERACTS WITH A WEAK BOUNDARY MOVING
THROUGH THE REGION. A FEW SHOWERS / THUNDERSTORMS ARE POSSIBLE IN
WESTERN NORTH DAKOTA LATER SUNDAY MORNING AS THE WAVE
APPROACHES...BUT DO NOT EXPECT THOSE TO BE SEVERE.
THE SEVERE THREAT IS EXPECTED TO INCREASE THIS AFTERNOON AND
EVENING AS THE MONTANA WAVE HELPS INITIATE THUNDERSTORMS ALONG THE
SLOW MOVING BOUNDARY. THAT BEING SAID...THE CAP REMAINS A
POTENTIAL LIMITING FACTOR DUE TO WARM H7 TEMPERATURES. THE NAM
AND GFS DISAGREE IN REGARDS TO HOW FAST THE MID LEVELS COOL
TODAY...WITH THE NAM BEING MORE AGGRESSIVE. THE NAM WAS ALSO
QUICKER TO INITIATE CONVECTION ALONG THE BOUNDARY ON
SATURDAY...AND AFTER SEEING THE LACK OF DEVELOPMENT ACROSS NORTH
DAKOTA...CONFIDENCE IN HOW WIDESPREAD THE CONVECTIVE DEVELOPMENT
WILL BE IS NOT HIGH. WILL CARRY CHANCE POPS NEAR THE BOUNDARY
TOWARDS LATE AFTERNOON / EARLY EVENING...AND LET LATER SHIFTS
MONITOR TRENDS WITH THE CAP AND POTENTIAL DEVELOPMENT.
IN REGARDS TO THE SEVERE WEATHER THREAT...EXPECT THE MAIN THREAT
AREA TO BE FROM THE SOUTH CENTRAL PART OF THE STATE AND TOWARDS
THE JAMES RIVER VALLEY. THE PRIMARY HAZARD SHOULD BE DAMAGING
WINDS WITH INVERTED V SOUNDINGS...WHILE WARM MID LEVEL
TEMPERATURES COULD LIMIT THE HAIL THREAT TO SOME DEGREE. ELEVATED
LIFTED CONDENSATION LEVELS SHOULD ALSO LIMIT THE TORNADO
POTENTIAL. THE THUNDERSTORM CHANCES ARE EXPECTED TO DIMINISH FROM
WEST TO EAST AS THE WAVE PASSES...WITH DRY WEATHER EXPECTED AGAIN
BY LATE TONIGHT.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN HIGHLIGHTS IN THE EXTENDED WILL BE HOT TEMPERATURES
MONDAY AND TUESDAY...WELL INTO 90S...WITH NEAR RECORD HIGHS FOR
BISMARCK TUESDAY. THIS MAY LEAD TO A POSSIBLE HEAT ADVISORY
TUESDAY AFTERNOON ACROSS PORTIONS OF SOUTH CENTRAL NORTH DAKOTA. A
STRONG COLD FRONT WILL FOLLOW FOR TUESDAY NIGHT SUPPRESSING HIGHS
BACK INTO THE 80S FOR THE REST OF THE WEEK.
IN TERMS OF PRECIPITATION CHANCES...THE PATTERN BECOMES MORE ACTIVE
WITH PERIODIC SHOWERS AND THUNDERSTORMS AS A PACIFIC LOW/TROUGH
EJECTS SEVERAL SHORTWAVES VIA A PERSISTENT FETCH OF SOUTHWEST FLOW
ALOFT STRAIGHT INTO NORTH DAKOTA.
FOR MONDAY AND TUESDAY...BEHIND A DEPARTING SHORTWAVE MONDAY MORNING
WILL BE BROAD RIDGING TAKING CONTROL. A LACK OF SHORTWAVE ACTIVITY
MONDAY WITH H85 TEMPS CLIMBING TO AROUND +26C TO +28C...BOTH MONDAY
AND TUESDAY...WILL MAKE THESE THE TWO HOTTEST DAYS IN THE EXTENDED.
PERHAPS A BIT WARMER TUESDAY. LOOKING AT RECORD HIGHS AT THE MAJOR
CITIES MONDAY AND TUESDAY...IT WOULD APPEAR THAT ONLY BISMARCK
WOULD COME CLOSEST TO POSSIBLY TYING A RECORD TUESDAY. THE RECORD IS
100 DEGREES SET BACK IN 1976. WE WILL BE CLOSE TO THAT WITH 98F AS A
FORECAST HIGH TEMPERATURE. WITH MANY SCHOOLS STARTING THIS
WEEK...HAVE TO REALLY CONSIDER THE HEAT IN THE AFTERNOON AS THE HEAT
INDICES WILL BE VERY CLOSE TO 100 DEGREES. WILL HIGHLIGHT THIS IN THE
HAZARDOUS WEATHER OUTLOOK FOR NOW AND BRIEF THE ONCOMING SHIFT THAT
AN ADVISORY MAY BECOME NECESSARY. GFS SOUNDINGS SHOW THAT ENOUGH OF
A CAP REMAINS IN PLACE THROUGH 00Z WEDNESDAY TO INHIBIT CONVECTION.
HAVE DISCOUNTED THE NAM SOLUTION WHICH GENERATES PRECIPITATION EARLY
IN THE DAY...WHILE THE OTHER MODELS KEEP IT DRY DURING THE DAYLIGHT
HOURS.
TUESDAY NIGHT/WEDNESDAY MORNING...A STRONG COLD FRONT WILL PUSH FROM
NORTHWEST TO SOUTHEAST. EXPECT A CHANCE FOR SHOWERS/THUNDERSTORMS
WITH THIS FRONT. H85 TEMPERATURES TAKE A DIGGER WITH +17C IN THE
NORTH WEDNESDAY AFTERNOON TO +20 IN THE SOUTHWEST. SHOULD BE
REFRESHING WITH HIGHS AROUND 80F NORTH TO MID 80S SOUTHWEST. THE
THREAT FOR AN ISOLATED SHOWER/THUNDERSTORM WILL LINGER IN THE SOUTH
THROUGH THE DAY WEDNESDAY.
THURSDAY THROUGH SUNDAY...SOUTHWEST FLOW ALOFT OPENS THE WAY FOR
SEVERAL SHORTWAVE TROUGHS TO MIGRATE THROUGH. UPPER RIDGE WILL BE
DOMINATE IN THE CENTRAL CONUS. THE TIMING OF THE AFOREMENTIONED
SHORTWAVES WILL CHANGE BETWEEN NOW AND LATER IN THE WEEK...BUT THE
HIGHER END CHANCES FOR SHOWERS/THUNDERSTORMS BEGIN TO INCREASE
THURSDAY AND CONTINUE INTO THE WEEKEND. THE ALLBLEND CAPTURES THIS
TREND WELL AND WILL MAINTAIN THAT. THE ECMWF IS A BIT MORE
AGGRESSIVE WITH THE SUCCESSIVE WAVES AND LARGER PRECIPITATION AREAS
VERSUS THE GFS...BUT THE OVERALL PATTERN IN BOTH MODELS IS SIMILAR.
HIGHS WILL REMAIN IN THE 80S WITH LOWS IN THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 320 AM CDT SUN AUG 18 2013
STRATUS DEVELOPMENT WILL HAVE TO BE MONITORED AGAIN EARLY THIS
MORNING...BUT THE STRATUS IS MUCH FARTHER SOUTH THAN YESTERDAY AT
THIS TIME. THE NAM STILL INCREASES H925 RELATIVE HUMIDITY ACROSS
SOUTH CENTRAL NORTH DAKOTA INTO THE JAMES RIVER VALLEY...AND WILL
HINT AT POSSIBLE STRATUS WITH SCATTED CLOUDS AROUND 1500 FT AT
KJMS.
THE NEXT CONCERN WILL BE THE CHANCE OF THUNDERSTORMS AS A FRONTAL
BOUNDARY MOVES ACROSS THE REGION. CONFIDENCE IN TIMING / PLACEMENT
OF THE CONVECTION IS STILL NOT HIGH...AND WILL CARRY VCTS AT THE
TERMINALS TO SUGGEST THUNDERSTORMS ARE POSSIBLE. OVERALL...WILL
STAY WITH VFR FORECASTS AND MONITOR TRENDS EARLY THIS MORNING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CK
SHORT TERM...CK
LONG TERM...KS
AVIATION...CK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
320 AM CDT SUN AUG 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN CONCERN IN THE NEAR TERM WILL BE THE CHANCES OF
THUNDERSTORMS...INCLUDING THE POSSIBILITY OF SEVERE WEATHER.
EARLY MORNING WATER VAPOR IMAGERY SHOWED A WAVE MOVING ACROSS
SOUTHERN PARTS OF SASKATCHEWAN / MANITOBA...WITH ANOTHER WAVE IN
NORTHWEST MONTANA. CONVECTION WITH THE CANADIAN WAVE HAS BEEN
SPARSE...AND THE LATEST NAM / RAP KEEPS THE FORECAST AREA DRY
EARLY THIS MORNING AS THE WAVE PASSES. THE BIGGER CONCERN WILL BE
THE MONTANA WAVE AS IT INTERACTS WITH A WEAK BOUNDARY MOVING
THROUGH THE REGION. A FEW SHOWERS / THUNDERSTORMS ARE POSSIBLE IN
WESTERN NORTH DAKOTA LATER SUNDAY MORNING AS THE WAVE
APPROACHES...BUT DO NOT EXPECT THOSE TO BE SEVERE.
THE SEVERE THREAT IS EXPECTED TO INCREASE THIS AFTERNOON AND
EVENING AS THE MONTANA WAVE HELPS INITIATE THUNDERSTORMS ALONG THE
SLOW MOVING BOUNDARY. THAT BEING SAID...THE CAP REMAINS A
POTENTIAL LIMITING FACTOR DUE TO WARM H7 TEMPERATURES. THE NAM
AND GFS DISAGREE IN REGARDS TO HOW FAST THE MID LEVELS COOL
TODAY...WITH THE NAM BEING MORE AGGRESSIVE. THE NAM WAS ALSO
QUICKER TO INITIATE CONVECTION ALONG THE BOUNDARY ON
SATURDAY...AND AFTER SEEING THE LACK OF DEVELOPMENT ACROSS NORTH
DAKOTA...CONFIDENCE IN HOW WIDESPREAD THE CONVECTIVE DEVELOPMENT
WILL BE IS NOT HIGH. WILL CARRY CHANCE POPS NEAR THE BOUNDARY
TOWARDS LATE AFTERNOON / EARLY EVENING...AND LET LATER SHIFTS
MONITOR TRENDS WITH THE CAP AND POTENTIAL DEVELOPMENT.
IN REGARDS TO THE SEVERE WEATHER THREAT...EXPECT THE MAIN THREAT
AREA TO BE FROM THE SOUTH CENTRAL PART OF THE STATE AND TOWARDS
THE JAMES RIVER VALLEY. THE PRIMARY HAZARD SHOULD BE DAMAGING
WINDS WITH INVERTED V SOUNDINGS...WHILE WARM MID LEVEL
TEMPERATURES COULD LIMIT THE HAIL THREAT TO SOME DEGREE. ELEVATED
LIFTED CONDENSATION LEVELS SHOULD ALSO LIMIT THE TORNADO
POTENTIAL. THE THUNDERSTORM CHANCES ARE EXPECTED TO DIMINISH FROM
WEST TO EAST AS THE WAVE PASSES...WITH DRY WEATHER EXPECTED AGAIN
BY LATE TONIGHT.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 320 AM CDT SUN AUG 18 2013
THE MAIN HIGHLIGHTS IN THE EXTENDED WILL BE HOT TEMPERATURES
MONDAY AND TUESDAY...WELL INTO 90S...WITH NEAR RECORD HIGHS FOR
BISMARCK TUESDAY. THIS MAY LEAD TO A POSSIBLE HEAT ADVISORY
TUESDAY AFTERNOON ACROSS PORTIONS OF SOUTH CENTRAL NORTH DAKOTA. A
STRONG COLD FRONT WILL FOLLOW FOR TUESDAY NIGHT SUPPRESSING HIGHS
BACK INTO THE 80S FOR THE REST OF THE WEEK.
IN TERMS OF PRECIPITATION CHANCES...THE PATTERN BECOMES MORE ACTIVE
WITH PERIODIC SHOWERS AND THUNDERSTORMS AS A PACIFIC LOW/TROUGH
EJECTS SEVERAL SHORTWAVES VIA A PERSISTENT FETCH OF SOUTHWEST FLOW
ALOFT STRAIGHT INTO NORTH DAKOTA.
FOR MONDAY AND TUESDAY...BEHIND A DEPARTING SHORTWAVE MONDAY MORNING
WILL BE BROAD RIDGING TAKING CONTROL. A LACK OF SHORTWAVE ACTIVITY
MONDAY WITH H85 TEMPS CLIMBING TO AROUND +26C TO +28C...BOTH MONDAY
AND TUESDAY...WILL MAKE THESE THE TWO HOTTEST DAYS IN THE EXTENDED.
PERHAPS A BIT WARMER TUESDAY. LOOKING AT RECORD HIGHS AT THE MAJOR
CITIES MONDAY AND TUESDAY...IT WOULD APPEAR THAT ONLY BISMARCK
WOULD COME CLOSEST TO POSSIBLY TYING A RECORD TUESDAY. THE RECORD IS
100 DEGREES SET BACK IN 1976. WE WILL BE CLOSE TO THAT WITH 98F AS A
FORECAST HIGH TEMPERATURE. WITH MANY SCHOOLS STARTING THIS
WEEK...HAVE TO REALLY CONSIDER THE HEAT IN THE AFTERNOON AS THE HEAT
INDICES WILL BE VERY CLOSE TO 100 DEGREES. WILL HIGHLIGHT THIS IN THE
HAZARDOUS WEATHER OUTLOOK FOR NOW AND BRIEF THE ONCOMING SHIFT THAT
AN ADVISORY MAY BECOME NECESSARY. GFS SOUNDINGS SHOW THAT ENOUGH OF
A CAP REMAINS IN PLACE THROUGH 00Z WEDNESDAY TO INHIBIT CONVECTION.
HAVE DISCOUNTED THE NAM SOLUTION WHICH GENERATES PRECIPITATION EARLY
IN THE DAY...WHILE THE OTHER MODELS KEEP IT DRY DURING THE DAYLIGHT
HOURS.
TUESDAY NIGHT/WEDNESDAY MORNING...A STRONG COLD FRONT WILL PUSH FROM
NORTHWEST TO SOUTHEAST. EXPECT A CHANCE FOR SHOWERS/THUNDERSTORMS
WITH THIS FRONT. H85 TEMPERATURES TAKE A DIGGER WITH +17C IN THE
NORTH WEDNESDAY AFTERNOON TO +20 IN THE SOUTHWEST. SHOULD BE
REFRESHING WITH HIGHS AROUND 80F NORTH TO MID 80S SOUTHWEST. THE
THREAT FOR AN ISOLATED SHOWER/THUNDERSTORM WILL LINGER IN THE SOUTH
THROUGH THE DAY WEDNESDAY.
THURSDAY THROUGH SUNDAY...SOUTHWEST FLOW ALOFT OPENS THE WAY FOR
SEVERAL SHORTWAVE TROUGHS TO MIGRATE THROUGH. UPPER RIDGE WILL BE
DOMINATE IN THE CENTRAL CONUS. THE TIMING OF THE AFOREMENTIONED
SHORTWAVES WILL CHANGE BETWEEN NOW AND LATER IN THE WEEK...BUT THE
HIGHER END CHANCES FOR SHOWERS/THUNDERSTORMS BEGIN TO INCREASE
THURSDAY AND CONTINUE INTO THE WEEKEND. THE ALLBLEND CAPTURES THIS
TREND WELL AND WILL MAINTAIN THAT. THE ECMWF IS A BIT MORE
AGGRESSIVE WITH THE SUCCESSIVE WAVES AND LARGER PRECIPITATION AREAS
VERSUS THE GFS...BUT THE OVERALL PATTERN IN BOTH MODELS IS SIMILAR.
HIGHS WILL REMAIN IN THE 80S WITH LOWS IN THE UPPER 50S TO MID 60S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 320 AM CDT SUN AUG 18 2013
STRATUS DEVELOPMENT WILL HAVE TO BE MONITORED AGAIN EARLY THIS
MORNING...BUT THE STRATUS IS MUCH FARTHER SOUTH THAN YESTERDAY AT
THIS TIME. THE NAM STILL INCREASES H925 RELATIVE HUMIDITY ACROSS
SOUTH CENTRAL NORTH DAKOTA INTO THE JAMES RIVER VALLEY...AND WILL
HINT AT POSSIBLE STRATUS WITH SCATTED CLOUDS AROUND 1500 FT AT
KJMS.
THE NEXT CONCERN WILL BE THE CHANCE OF THUNDERSTORMS AS A FRONTAL
BOUNDARY MOVES ACROSS THE REGION. CONFIDENCE IN TIMING / PLACEMENT
OF THE CONVECTION IS STILL NOT HIGH...AND WILL CARRY VCTS AT THE
TERMINALS TO SUGGEST THUNDERSTORMS ARE POSSIBLE. OVERALL...WILL
STAY WITH VFR FORECASTS AND MONITOR TRENDS EARLY THIS MORNING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CK
LONG TERM...KS
AVIATION...CK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1240 AM CDT SUN AUG 18 2013
.UPDATE...
ISSUED AT 1239 AM CDT SUN AUG 18 2013
EARLY MORNING REGIONAL RADAR MOSAIC SHOWS A FEW SHOWERS / ISOLATED
THUNDERSTORMS MOVING ACROSS SOUTHERN MANITOBA...WITH ANOTHER SMALL
CLUSTER IN CENTRAL MONTANA. THE HRRR STILL SUGGESTS THE WAVE
RESPONSIBLE FOR THE ACTIVITY IN SOUTHERN MANITOBA MAY BE ABLE TO
GENERATE AN ISOLATED THUNDERSTORM IN FAR NORTH CENTRAL NORTH
DAKOTA EARLY THIS MORNING. THE WAVE RESPONSIBLE FOR THE CONVECTION
IN CENTRAL MONTANA WILL NOT ARRIVE UNTIL AFTER 12Z SUNDAY...SO
WILL KEEP THE WEST DRY OVERNIGHT...WITH THE CHANCES INCREASING BY
SUNDAY AFTERNOON.
UPDATE ISSUED AT 939 PM CDT SAT AUG 17 2013
THE SURFACE TROUGH HAS INCHED EASTWARD...EXTENDING FROM A LOW IN
MANITOBA TO NEAR TIOGA/STANLEY TO NEAR DICKINSON. 00Z SOUNDINGS
INDICATED STRONG CAP IN PLACE AT GLASGOW/BISMARCK/INTERNATIONAL
FALLS AND POINTS SOUTH. STILL MONITORING RADAR AND SATELLITE FOR
ANY EVIDENCE OF CONVECTION...SINCE AFTER SUNSET THE CAP MAY WEAKEN
- ESPECIALLY WITH THE APPROACH/ARRIVAL OF AN UPPER LEVEL
SHORTWAVE.
LOOKING AT WATER VAPOR SAT LOOP...ONE SHORTWAVE IMPULSE IS OVER
SOUTHEASTERN SASKATCHEWAN - POISED TO CATCH UP TO THE SURFACE
TROUGH. SEEING EVIDENCE OF MID CLOUDS IN THE RADAR LOOPS AND SAT
PICS OVER SOUTHEASTERN SASKATCHEWAN TO SOUTHWESTERN MANITOBA. WILL KEEP
MONITORING FOR ANY DEVELOPMENT...AND HENCE HAVE KEPT SLIGHT
CHANCES IN THE NORTH CENTRAL FOR TONIGHT.
A SECOND SHORTWAVE SEEN IN THE WATER VAPOR LOOP WAS APPROACHING
NORTH CENTRAL MONTANA...AND THIS FEATURE IS PROGGED TO MOVE
EASTWARD SLOWLY OVERNIGHT AND ITS LEADING EDGE IS PROGGED TO REACH
NORTHWESTERN NORTH DAKOTA BY DAYBREAK SUNDAY...FOLLOWED BY A
LARGER IMPULSE LATE MORNING/AFTERNOON IN WESTERN NORTH DAKOTA.
MADE MINOR CHANGES TO TEMPERATURES AND WINDS TO REFLECT CURRENT
TRENDS...BUT NO CHANGES IN LOW TEMPERATURES TONIGHT.
UPDATE ISSUED AT 635 PM CDT SAT AUG 17 2013
THE SURFACE TROUGH EXTENDED FROM A LOW IN NORTHERN MANITOBA TO NEAR
TIOGA/WILLISTON TO NEAR BOWMAN. MID-LEVEL CAP IN PLACE WITH H700
THERMAL RIDGE EXTENDING FROM NEAR HETTINGER TO DEVILS LAKE. AT UPPER
LEVELS...A SHORTWAVE WAS MOVING EASTWARD ACROSS SOUTHEASTERN
SASKATCHEWAN INTO SOUTHERN MANITOBA...AND AGITATED CUMULUS/TOWERING
CUMULUS SEEN IN THE VISIBLE SATELLITE PICS HAD BECOME
THUNDERSTORMS ACROSS SOUTHEASTERN SASKATCHEWAN/SOUTHWESTERN
MANITOBA AROUND 5 PM CDT...BUT HAVE SINCE DIMINISHED. BEST 0-6KM
SHEAR IS ACROSS THIS AREA OF SOUTH CENTRAL CANADA. SUSPECT HIGH-
BASED STORMS...AND BEST DOWNDRAFT CAPE AXIS EXTENDS FROM SOUTHERN
MANITOBA TO THE SURFACE TROUGH AREA OF WESTERN NORTH DAKOTA. TIME
WILL TELL LATER THIS EVENING WHETHER THERE IS ENOUGH ENERGY IN THE
UPPER LEVEL SHORTWAVE TO BREAK THE MID-LEVEL CAP IN PLACE - WITH
THE WEAKEST PART OF THE MID-LEVEL CAP ACROSS NORTHERN NORTH
DAKOTA. THUS THE NORTH CENTRAL (BOTTINEAU/MINOT/KENMARE AREAS)
APPEAR TO HAVE THE BEST SHOT AT SEEING CONVECTION IN NORTH DAKOTA.
OTHER THAN THE MINOT AREA...THE NEXT AREA TO WATCH IS ALONG THE
SURFACE TROUGH WHERE LOW LEVEL CONVERGENCE MAY BE ABLE TO LINK
WITH PLENTY OF CAPE ABOVE THE MID-LEVEL CAP AROUND/AFTER SUNSET.
THE ONGOING FORECAST HAD SLIGHT CHANCES IN THE NORTH CENTRAL THIS
EVENING AND SAW NO REASON TO CHANGE THAT AT THIS TIME.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 343 PM CDT SAT AUG 17 2013
THE MAIN FORECAST CHALLENGE FOR THE PERIOD WILL BE THE PRECIP CHANCES
LATER THIS EVENING AND AGAIN ON SUNDAY.
A WEAK SURFACE BOUNDARY IS BEGINNING TO ENTER WESTERN NORTH DAKOTA
THIS AFTERNOON. A STRONG CAP IN PLACE SHOULD INHIBIT AFTERNOON
CONVECTION ALONG THE BOUNDARY. HOWEVER...AS THIS BOUNDARY PUSHES
INTO CENTRAL NORTH DAKOTA THIS EVENING...THUNDERSTORMS COULD DEVELOP
OVER NORTH CENTRAL NORTH DAKOTA PROXIMATE TO THE BEST UPPER LEVEL
DYNAMICS AND WEAKEST CAP. THE 12Z ECMWF/NAM AND 17Z HRRR PROG THIS
SCENARIO SO DECIDED TO KEEP SLIGHT CHANCE POPS IN THE GRIDS NORTH
CENTRAL TONIGHT. SOME STORMS COULD BECOME STRONG SO WILL HIGHLIGHT
THIS THREAT IN THE HWO FOR NOW.
AS THE BOUNDARY MOVES INTO EASTERN NORTH DAKOTA SUNDAY...IT IS
PROGGED TO BECOME STALLED ACROSS CENTRAL NORTH DAKOTA. AN UPPER WAVE
IS FORECAST TO MOVE OVER NORTH DAKOTA THROUGH THE DAY SUNDAY. AS IT
DOES...THE CHANCES FOR THUNDERSTORMS WILL GRADUALLY OVERSPREAD THE
STATE FROM WEST TO EAST. STORMS SHOULD REMAIN BELOW SEVERE CRITERIA
THROUGH SUNDAY AFTERNOON...BUT COULD STRENGTHEN TO SEVERE SUNDAY
EVENING. SEE LONG TERM DISCUSSION BELOW FOR MORE DETAILS.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 343 PM CDT SAT AUG 17 2013
THE MAIN FORECAST HIGHLIGHT FOR THE EXTENDED PERIOD WILL BE THE
POTENTIAL FOR SEVERE THUNDERSTORMS SUNDAY EVENING.
THEREAFTER...PROGRESSIVE WEST TO SOUTHWEST FLOW WITH MULTIPLE
EMBEDDED UPPER LEVEL IMPULSES IS FORECAST THROUGH THE REMAINDER OF
THE PERIOD. 12Z MODEL DETERMINISTIC MODEL GUIDANCE IS IN GOOD
AGREEMENT THROUGH MID BEFORE SOLUTIONS DIVERGE LATE WEEK.
THE POTENTIAL FOR SEVERE THUNDERSTORMS WILL INCREASE SUNDAY
EVENING AS THE COMBINED FORCING FROM THE SURFACE FRONTAL BOUNDARY
AND UPPER LEVEL WAVE ERODES THE CAP. THIS FORCING SHOULD BE
SUFFICIENT ENOUGH TO BREAK THE CAP BY EARLY SUNDAY EVENING AND ALLOW
CONVECTION TO FIRE ALONG THE SURFACE FRONTAL BOUNDARY. THE
ANTECEDENT ENVIRONMENT WILL BE FAVORABLE FOR THE DEVELOPMENT OF
SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL AND MOST OF EASTERN
NORTH DAKOTA...WITH ML CAPE FORECAST TO BE NEAR 2000 J/KG BY LATE
SUNDAY AFTERNOON/EVENING...INCREASING BOUNDARY LAYER MOISTURE
(DEWPOINTS INCREASING INTO THE 60S)...AND 0-6 KM BULK SHEAR TO BE
IN THE 25 TO 35 M/S RANGE. FURTHERMORE...THE LATEST DAY 2 OUTLOOK
FROM SPC HAS PARTS OF CENTRAL AND MOST OF EASTERN NORTH DAKOTA IN
THE SLIGHT RISK. HAIL AND DAMAGING WINDS LOOK TO BE THE MAIN
THREATS AND AT THIS TIME WILL HIGHLIGHT THE POSSIBILITY OF SEVERE
THUNDERSTORMS IN THE HWO AND STATE FORECAST.
FOLLOWING THE FRONTAL PASSAGE/SHORTWAVE MONDAY...DAYTIME UPPER
LEVEL RIDGING WILL GIVE WAY TO WESTERLY FLOW ALOFT. THIS WILL
CONTINUE THROUGH TUESDAY EVENING AHEAD OF THE EXPECTED COLD FRONT
WEDNESDAY AND THURSDAY. CANNOT RULE OUT THE POSSIBILITY OF
THUNDERSTORMS/SHOWERS ACROSS THE AREA...AS SEVERAL WEAK IMPULSES
MOVE OVER THE STATE. PRECIPITATION CHANCES WILL THEN INCREASE AS
A COLD FRONT AND AN UPPER LEVEL SHORT WAVE APPROACH NORTHERN
NORTH DAKOTA LATE TUESDAY NIGHT/EARLY WEDNESDAY MORNING...AND AS THEY
MOVE OVER THE AREA WEDNESDAY. SIMILAR TO PREVIOUS RUNS...THE 12Z
ECWMF CONTINUES TO PAINT A DECENT AREA OF SHOWERS/THUNDERSTORMS
OVER THE WEST AND CENTRAL. HOWEVER...THE 12Z GFS CONTINUES TO KEEP
NORTH DAKOTA DRY AS IT FORECASTS UPPER LEVEL RIDGING TAKING PLACE.
WILL KEEP THE ALLBLEND SOLUTION...TO SPLIT THE DIFFERENCE BETWEEN
THE ECWMF AND GFS. FOR FRIDAY AND SATURDAY...PRECIPITATION CHANCES
WILL CONTINUE AS SOUTHWESTERLY FLOW TAKES HOLD.
MEANWHILE...H850 TEMPERATURES WILL INCREASE TO BETWEEN +26 AND +30 C
ON TUESDAY. THIS WILL TRANSLATE TO SURFACE TEMPERATURES IN THE
90S...WITH NEAR 100 DEGREE READING FOR FAR SOUTHERN NORTH DAKOTA.
COOLER TEMPERATURES ARE FORECAST ONCE THE COLD FRONT PASSES
THROUGH THE AREA WEDNESDAY...WHERE TEMPERATURES ARE EXPECTED TO BE
MAINLY IN THE 80S DURING THE DAY AND UPPER 50S/LOWER 60S AT NIGHT
THROUGH SATURDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1239 AM CDT SUN AUG 18 2013
STRATUS DEVELOPMENT WILL HAVE TO BE MONITORED AGAIN EARLY THIS
MORNING...BUT THE STRATUS IS MUCH FARTHER SOUTH THAN YESTERDAY AT
THIS TIME. THE NAM STILL INCREASES H925 RELATIVE HUMIDITY ACROSS
SOUTH CENTRAL NORTH DAKOTA INTO THE JAMES RIVER VALLEY...AND WILL
HINT AT POSSIBLE STRATUS WITH SCATTED CLOUDS AROUND 1500 FT AT
KJMS.
THE NEXT CONCERN WILL BE THE CHANCE OF THUNDERSTORMS AS A FRONTAL
BOUNDARY MOVES ACROSS THE REGION. CONFIDENCE IN TIMING / PLACEMENT
OF THE CONVECTION IS STILL NOT HIGH...AND WILL CARRY VCTS AT THE
TERMINALS TO SUGGEST THUNDERSTORMS ARE POSSIBLE. OVERALL...WILL
STAY WITH VFR FORECASTS AND MONITOR TRENDS EARLY THIS MORNING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CK
SHORT TERM...TM
LONG TERM...LTH
AVIATION...CK
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
654 PM EDT SUN AUG 18 2013
.SYNOPSIS...
SEVERAL WEAK WEATHER SYSTEMS WILL DRIFT SLOWLY THROUGH THE GREAT
LAKES FROM TONIGHT THROUGH MID-WEEK...AS TEMPERATURES AND
HUMIDITY CONTINUE TO SLOWLY INCREASE AT THE SAME TIME. NEITHER OF
THE DISTURBANCES IS EXPECTED TO BRING MUCH COVERAGE OF RAIN...BUT
THREATS FOR SHOWERS OR A FEW THUNDERSTORMS ON A LIMITED BASIS WILL
BE PRESENT TONIGHT INTO MONDAY MAINLY EAST OF I-71...AND ON
WEDNESDAY ESPECIALLY SOUTH OF I-70. IN BOTH CASES...MOST AREAS
WILL STAY DRY...WITH MUGGY AND WARM AFTERNOONS AND MILD NIGHTS WITH
LIGHT WINDS. ABOVE NORMAL TEMPERATURES WILL REMAIN ENTRENCHED
THROUGH THE WEEK INTO NEXT WEEKEND...AS A VERY TYPICAL LATE SUMMER
PATTERN REMAINS IN PLACE.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
A QUICK UPDATE EARLY THIS EVE TO CLEAN UP SKY/RAIN CHANCE IN
ACCORDANCE WITH SATELLITE/RADAR TRENDS. PREVIOUS SCNTL OHIO RAIN
AREA HAS FIZZLED QUICKLY SO LOWERED EARLY-MID EVENING RAIN CHANCES
THERE. ALSO ACCOUNTED FOR POSSIBILITY THAT PULSEY/DISORGANIZED
UPDRAFTS OVER CNTL KY MAY WANDER INTO OWEN/GRANT COUNTIES THROUGH
01Z. RECENT HRRR RUNS HAVE BACKED AWAY FROM ISOLD CONVECTION ALONG
THE DIFFERENTIAL HEATING ZONE ON THE EDGE OF THE AFTN THICKER
CLOUD SHIELD FROM OWEN/GRANT UP THROUGH CLINTON COUNTY...THOUGH
LOW LEVEL MOISTURE IS POOLED HERE...WITH DWPT AT KILN AT 66F. CHCS
FOR DIURNALLY TIED CONVECTION HAVE WANED CONSIDERABLY GIVEN
SATELLITE TRENDS...SO RAIN CHANCES REDUCED HERE FOR THE EVENING.
ALSO...BASED ON LATEST DATA...THE LATE EVE/OVERNIGHT RAIN CHANCES
IN THE SCIOTO VALLEY AND UP TOWARD LICKING COUNTY MAY NEED TO BE
PULLED ALTOGETHER. WILL MONITOR.
PREVIOUS DISCUSSION FOLLOWS BELOW....
DISORGANIZED SHIELD OF VERY LIGHT
RAIN/SPRINKLES HAS BEEN PUSHING STEADILY NORTHEAST THROUGH THE
AFTERNOON UP THE SCIOTO RIVER VALLEY...IMMEDIATELY IN ADVANCE OF A
MID-LEVEL VORTICITY MAX SEEN SWIRLING BOTH ON VISIBLE SATELLITE
IMAGERY AND ON RADAR MOSAICS OVER NRN KENTUCKY. THIS IS NEAR THE
NOSE OF A NARROW 250MB JETLET /115KT/ THAT IS SHIFTING NORTHEAST
AND ALLOWING THE OPENING/SHEARING OF THE OLD CLOSED LOW THAT HAD
BEEN SPINNING WELL SOUTHWEST OF THE AREA THE PAST FEW DAYS. THE
MID/UPPER LEVEL SHORTWAVE TROUGH IS POSITIVELY TILTED...AND
WEAKENING WITH TIME...WITH DECREASING LARGE SCALE ASCENT AND VERY
WEAK SURFACE FEATURES UNDERNEATH. THE 18.18Z RAP HAD A NICE HANDLE
ON THE MID LEVEL VORT MAX DRIVING NORTHEAST THROUGH SCNTL OH...AND
CONTINUES TO LIFT THIS FEATURE OUT OF THE AREA THROUGH MID
EVENING...WITH THE SHIELD OF LIGHT RAIN/SPRINKLES LIKELY EXITING
THE AREA BY 00Z OR SO...IF IT DOESN/T FALL APART COMPLETELY BEFORE
THEN. MESOANALYSIS CURRENTLY /19Z/ SHOWS A FAIRLY NICE
DIFFERENTIAL HEATING ZONE /CAPE AXIS/ ON THE IMMEDIATE WEST SIDE
OF THE RAIN SHIELD...RUNNING FROM OWEN/GRANT COUNTIES UP THROUGH
THE WILMINGTON AREA TOWARDS CMH. VARIOUS AND SUNDRY CONVECTION
ALLOWING MODEL RUNS /3-4KM RESOLUTION/ HAVE TRIED TO DEVELOP
ISOLATED STORMS IN THIS CORRIDOR IN THE NEXT FEW HOURS UP THROUGH
ABOUT 02Z...SO WE ARE IN NO HURRY TO DECREASE/SHRINK RAIN CHANCES
WEST OR SOUTHWEST OF CURRENT RAIN SHIELD OVER SCNTL OH. WHILE
MLCAPE IS LARGELY WEAK /300-700 J/KG/...THE PASSING OF THE
MID/UPPER LEVEL PV ANOMALY ACROSS THIS AREA THROUGH THE NEXT FEW
HOURS MAY AGITATE THE WEAK BAROCLINIC ZONE FOR A STORM OR TWO.
LATER THIS EVENING/OVERNIGHT...ONE MORE SURGE /IF YOU CAN CALL IT
THAT - IT IS QUITE WEAK/ OF MOISTURE ADVECTION RIDES FROM ERN
TN/KY INTO CNTL/ERN OH AND MAY PROMOTE SOME -SHRA REGENERATION
OVER THE SCIOTO VALLEY AND UP TOWARD/EAST OF CMH...SO WE HOLD ON
TO HIGHER RAIN CHANCES HERE LATER THIS EVENING AND OVERNIGHT. NOT
SURE IF THIS WILL LEAD TO MUCH ACTIVITY OR NOT...CONFIDENCE IS
LOW...BUT THE SIGNAL HAS BEEN PRESENT FOR A FEW DAYS THUS DON/T
WANT TO BACK AWAY YET. KEPT MIN TEMP FORECAST RIGHT WHERE IT WAS
FOR THE MOST PART...WELL TRENDED IN THE LOWER 60S MOST
AREAS...THOUGH MIXED OUT DEW POINTS IN WCNTL OHIO/ERN IND SUGGEST
SOME MID TO UPPER 50S IN THAT AREA WHERE PRECIPITABLE WATER
MINIMUM EXISTS.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
THE LAST WEAK SURGE OF MOISTURE MAY LINGER SHOWER CHANCES IN THE
EAST IN THE MORNING...AND THERE MAY BE JUST ENOUGH DIURNAL INSTBY
FOR A SHOWER/STORM IN THE FAR EAST/SOUTH IN THE AFTERNOON...BUT
MONDAY IS LARGELY A DRY DAY FOR THE FORECAST AREA WITH INCREASING
SUBSIDENCE IN THE WAKE OF THE DEPARTING SHORTWAVE TROUGH WHICH
WILL BE SHEARING DOWNSTREAM THROUGH PA/NY. DESPITE ITS
DEPARTURE...THERE REMAINS A WEAKNESS IN THE LARGER SCALE HEIGHT
FIELD BETWEEN TWO LARGE ANTICYCLONES OFF THE SOUTHEAST CONUS AND
OVER THE CNTL CONUS. THIS WEAKNESS IS A SOURCE OF LINGERING WEAK
SHORTWAVE ENERGY...AND WITH THIS AXIS LINGERING IN THE FAR
SOUTH/EAST...THUS THE SMALL RAIN CHANCES LINGERING UNTIL THAT AXIS
CAN CLEAR IN THE MID AFTERNOON HOURS. MOST AREAS WILL SEE A FAIR
AMOUNT OF SUNSHINE ON MONDAY...WITH TEMPS ADDING A FEW MORE
DEGREES TO PUT MOST AREAS IN THE LOW-MID 80S.
BRIEF SHORTWAVE RIDGING SLIDES IN FOR MONDAY NIGHT...WITH SKIES
GOING CLEAR. THIS SHOULD ALLOW A LITTLE BETTER TEMP DROP WITH
PWAT DROPPING OFF BACK TOWARD 1 INCH /BELOW SEASONAL NORMS/.
THUS...SIDED WITH SOME OF THE MOS DATASETS THAT ALLOWED COOL SPOTS
TO DROP OFF PRETTY DECENTLY MON NIGHT INTO THE UPPER 50S. WITH
SUCH LIGHT WINDS OVER THE NEXT COUPLE NIGHTS...ALMOST CERTAIN TO
BE COMMON SUMMER NIGHT FOG IN LOW LYING AREAS...BUT NOT SEEING A
GREAT SIGNAL FOR SOMETHING WIDESPREAD TO INCLUDE IN THE FORECAST
AS OF YET.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
SURFACE HIGH PRESSURE WILL ESTABLISH ITSELF TO OUR SE ON TUESDAY IN
WAKE OF DEPARTING UPR LVL SYSTEM. WE SHOULD SEE A MOSTLY SUNNY TO
PARTLY SUNNY DAY. MODELS HAD BEEN SUGGESTING THAT PERHAPS A POP OF
SHOWER OR STORM COULD OCCUR IN THE FAR SOUTH DURING THE HEAT OF THE
DAY. THIS STILL MAY OCCUR...BUT DO NOT FEEL IT WARRANTS A 20 POP
MENTION SO HAVE ALLOW THE FORECAST TO REMAIN DRY. HIGHS WILL BE A
LITTLE WARMER...GENERALLY IN THE MID 80S.
FOR THE PERIOD TUESDAY NIGHT INTO WEDNESDAY NIGHT...MAJORITY OF
MODELS HAVE COME MORE IN LINE ON WHAT WILL HAPPEN TO EMBEDDED S/WV
ENERGY WITHIN THE NW FLOW ALOFT. IT APPEARS THIS ENERGY WILL DEVELOP
INTO A CLOSED LOW TO OUR WEST...THEN WILL SLOWLY PROGRESS EAST THROUGH
THE REGION WEDNESDAY INTO WEDNESDAY NIGHT. ECMWF/GFS SUGGEST THAT
SOME EMBEDDED S/WV ENERGY MOVING NE AROUND DEVELOPING CLOSED LOW
COULD SPARK A FEW SHOWERS AND THUNDERSTORMS BEGINNING ACRS OUR SW
TUESDAY NIGHT. HAVE GIVEN ALL LOCATIONS AT LEAST A THREAT FOR
SHOWERS AND STORMS ON WEDNESDAY WITH THE HIGHER CHANCES FAVORING THE
SRN ZONES DUE TO HIGHER INSTABILITY AND MOISTURE. HAVE ALLOWED POPS
TO FALL OFF OVERNIGHT WEDNESDAY NIGHT AS SYSTEM HEADS EAST. HIGHS ON
WEDNESDAY WILL BE SLIGHTLY COOLER...ESPECIALLY SOUTHWEST CLOSER TO
THE UPR LVL LOW.
FOR THE PERIOD THURSDAY INTO FRIDAY NIGHT...MODELS CONTINUE TO
STRUGGLE ON HOW LONG WAVE TROUGH ENERGY WILL DIG SE INTO SE CANADA
AND NEW ENGLAND DURING THE PERIOD. AS SUCH...ASSOCIATED COLD FRONT
AND WHERE IT WILL END UP...I.E. WILL IT PUSH THROUGH...STALL OUT
OVER OUR AREA...OR PERHAPS FALL APART...IS STILL IN QUESTION. HAVE
TAKEN A BLEND OF WPC AND THE LATEST 18.12Z ECMWF...WHICH ALLOWS THE
FRONT TO APPROACH THE REGION FROM THE NORTH THURSDAY NIGHT...SLOW IT
UP AS IT PUSHES INTO THE REMAINDER OF THE AREA ON FRIDAY...THEN
WASHES IT OUT FRIDAY NIGHT INTO SATURDAY AS ANOTHER HIGH PRESSURE
RIDGE BUILDS IN FROM THE NORTH. GIVEN LACK OF STRONG UPR
SUPPORT...AS IT IS FCST TO REMAIN WELL OFF TO THE NE...ALONG WITH
WEAK LOW LEVEL FORCING...HAVE KEPT POPS LOW THURSDAY NIGHT INTO
FRIDAY. HAVE THEN ALLOWED CONDITIONS TO DRY OUT BY FRIDAY NIGHT.
TEMPERATURES WILL BE CLOUD DEPENDENT BUT SHOULD SEE A SLIGHT BUMP UP
AHEAD OF THE FRONT ON THURSDAY WITH SIMILAR OR SLIGHTLY COOLER
CONDITIONS POSSIBLE ON FRIDAY.
SURFACE HIGH PRESSURE WILL MOVE EAST THROUGH THE UPCOMING WEEKEND AS
A MID LVL RIDGE BEGINS TO NUDGE INTO FROM THE CNTRL PLAINS.
CONDITIONS SHOULD REMAIN DRY. TEMPERATURES WILL BE SEASONABLY WARM
FOR LATE AUGUST.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
SHOWERS OVER THE SOUTHERN SCIOTO VALLEY WILL MOVE NORTH AND AFFECT
CMH/LCK TAF SITES LATER THIS AFTERNOON FOR A BRIEF PERIOD.
ATTM...COVERED THIS WITH VICINITY SHOWER AND NO RESTRICTION TO
VSBY BUT IF THEY HOLD TOGETHER WILL AMEND TO BRING INTO MVFR VSBY
DURING A TEMPO GROUP. THIS IS THE ONLY AREA WITH MVFR CIGS AS WELL
TODAY.
WITH THE LOSS OF DAYTIME HEATING...ANY SHOWERS WILL QUICKLY
DIMINISH THIS EVENING AND CU FIELD OVER REMAINING TAF SITES WILL
ALSO DISSIPATE. WHILE THE AXIS OF THE UPPER LOW IS STILL ALONG AND
SSW OF THE REGION...THE ENERGY THAT IS SPARKING THE RAIN IN THE
SOUTHEAST WILL BE TRANSLATING EAST THROUGH PA TONIGHT.
IF THE CLEARING AND LIGHT WINDS ARE REALIZED...SOME DAYBREAK FOG
WITH GENERALLY MVFR VSBYS WILL OCCUR.
OUTLOOK...NO SIGNIFICANT WEATHER EXPECTED.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...BINAU
NEAR TERM...BINAU
SHORT TERM...BINAU
LONG TERM...HICKMAN
AVIATION...FRANKS
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
426 PM EDT SUN AUG 18 2013
.SYNOPSIS...
SEVERAL WEAK WEATHER SYSTEMS WILL DRIFT SLOWLY THROUGH THE GREAT
LAKES FROM TONIGHT THROUGH MID-WEEK...AS TEMPERATURES AND
HUMIDITY CONTINUE TO SLOWLY INCREASE AT THE SAME TIME. NEITHER OF
THE DISTURBANCES IS EXPECTED TO BRING MUCH COVERAGE OF RAIN...BUT
THREATS FOR SHOWERS OR A FEW THUNDERSTORMS ON A LIMITED BASIS WILL
BE PRESENT TONIGHT INTO MONDAY MAINLY EAST OF I-71...AND ON
WEDNESDAY ESPECIALLY SOUTH OF I-70. IN BOTH CASES...MOST AREAS
WILL STAY DRY...WITH MUGGY AND WARM AFTERNOONS AND MILD NIGHTS WITH
LIGHT WINDS. ABOVE NORMAL TEMPERATURES WILL REMAIN ENTRENCHED
THROUGH THE WEEK INTO NEXT WEEKEND...AS A VERY TYPICAL LATE SUMMER
PATTERN REMAINS IN PLACE.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
DISORGANIZED SHIELD OF VERY LIGHT RAIN/SPRINKLES HAS BEEN PUSHING
STEADILY NORTHEAST THROUGH THE AFTERNOON UP THE SCIOTO RIVER
VALLEY...IMMEDIATELY IN ADVANCE OF A MID-LEVEL VORTICITY MAX SEEN
SWIRLING BOTH ON VISIBLE SATELLITE IMAGERY AND ON RADAR MOSAICS
OVER NRN KENTUCKY. THIS IS NEAR THE NOSE OF A NARROW 250MB JETLET
/115KT/ THAT IS SHIFTING NORTHEAST AND ALLOWING THE
OPENING/SHEARING OF THE OLD CLOSED LOW THAT HAD BEEN SPINNING WELL
SOUTHWEST OF THE AREA THE PAST FEW DAYS. THE MID/UPPER LEVEL
SHORTWAVE TROUGH IS POSITIVELY TILTED...AND WEAKENING WITH
TIME...WITH DECREASING LARGE SCALE ASCENT AND VERY WEAK SURFACE
FEATURES UNDERNEATH. THE 18.18Z RAP HAD A NICE HANDLE ON THE MID
LEVEL VORT MAX DRIVING NORTHEAST THROUGH SCNTL OH...AND CONTINUES
TO LIFT THIS FEATURE OUT OF THE AREA THROUGH MID EVENING...WITH
THE SHIELD OF LIGHT RAIN/SPRINKLES LIKELY EXITING THE AREA BY 00Z
OR SO...IF IT DOESN/T FALL APART COMPLETELY BEFORE THEN.
MESOANALYSIS CURRENTLY /19Z/ SHOWS A FAIRLY NICE DIFFERENTIAL
HEATING ZONE /CAPE AXIS/ ON THE IMMEDIATE WEST SIDE OF THE RAIN
SHIELD...RUNNING FROM OWEN/GRANT COUNTIES UP THROUGH THE
WILMINGTON AREA TOWARDS CMH. VARIOUS AND SUNDRY CONVECTION
ALLOWING MODEL RUNS /3-4KM RESOLUTION/ HAVE TRIED TO DEVELOP ISOLATED
STORMS IN THIS CORRIDOR IN THE NEXT FEW HOURS UP THROUGH ABOUT
02Z...SO WE ARE IN NO HURRY TO DECREASE/SHRINK RAIN CHANCES WEST
OR SOUTHWEST OF CURRENT RAIN SHIELD OVER SCNTL OH. WHILE MLCAPE IS
LARGELY WEAK /300-700 J/KG/...THE PASSING OF THE MID/UPPER LEVEL
PV ANOMALY ACROSS THIS AREA THROUGH THE NEXT FEW HOURS MAY AGITATE THE
WEAK BAROCLINIC ZONE FOR A STORM OR TWO.
LATER THIS EVENING/OVERNIGHT...ONE MORE SURGE /IF YOU CAN CALL IT
THAT - IT IS QUITE WEAK/ OF MOISTURE ADVECTION RIDES FROM ERN
TN/KY INTO CNTL/ERN OH AND MAY PROMOTE SOME -SHRA REGENERATION
OVER THE SCIOTO VALLEY AND UP TOWARD/EAST OF CMH...SO WE HOLD ON
TO HIGHER RAIN CHANCES HERE LATER THIS EVENING AND OVERNIGHT. NOT
SURE IF THIS WILL LEAD TO MUCH ACTIVITY OR NOT...CONFIDENCE IS
LOW...BUT THE SIGNAL HAS BEEN PRESENT FOR A FEW DAYS THUS DON/T
WANT TO BACK AWAY YET. KEPT MIN TEMP FORECAST RIGHT WHERE IT WAS
FOR THE MOST PART...WELL TRENDED IN THE LOWER 60S MOST
AREAS...THOUGH MIXED OUT DEW POINTS IN WCNTL OHIO/ERN IND SUGGEST
SOME MID TO UPPER 50S IN THAT AREA WHERE PRECIPITABLE WATER
MINIMUM EXISTS.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
THE LAST WEAK SURGE OF MOISTURE MAY LINGER SHOWER CHANCES IN THE
EAST IN THE MORNING...AND THERE MAY BE JUST ENOUGH DIURNAL INSTBY
FOR A SHOWER/STORM IN THE FAR EAST/SOUTH IN THE AFTERNOON...BUT
MONDAY IS LARGELY A DRY DAY FOR THE FORECAST AREA WITH INCREASING
SUBSIDENCE IN THE WAKE OF THE DEPARTING SHORTWAVE TROUGH WHICH
WILL BE SHEARING DOWNSTREAM THROUGH PA/NY. DESPITE ITS
DEPARTURE...THERE REMAINS A WEAKNESS IN THE LARGER SCALE HEIGHT
FIELD BETWEEN TWO LARGE ANTICYCLONES OFF THE SOUTHEAST CONUS AND
OVER THE CNTL CONUS. THIS WEAKNESS IS A SOURCE OF LINGERING WEAK
SHORTWAVE ENERGY...AND WITH THIS AXIS LINGERING IN THE FAR
SOUTH/EAST...THUS THE SMALL RAIN CHANCES LINGERING UNTIL THAT AXIS
CAN CLEAR IN THE MID AFTERNOON HOURS. MOST AREAS WILL SEE A FAIR
AMOUNT OF SUNSHINE ON MONDAY...WITH TEMPS ADDING A FEW MORE
DEGREES TO PUT MOST AREAS IN THE LOW-MID 80S.
BRIEF SHORTWAVE RIDGING SLIDES IN FOR MONDAY NIGHT...WITH SKIES
GOING CLEAR. THIS SHOULD ALLOW A LITTLE BETTER TEMP DROP WITH
PWAT DROPPING OFF BACK TOWARD 1 INCH /BELOW SEASONAL NORMS/.
THUS...SIDED WITH SOME OF THE MOS DATASETS THAT ALLOWED COOL SPOTS
TO DROP OFF PRETTY DECENTLY MON NIGHT INTO THE UPPER 50S. WITH
SUCH LIGHT WINDS OVER THE NEXT COUPLE NIGHTS...ALMOST CERTAIN TO
BE COMMON SUMMER NIGHT FOG IN LOW LYING AREAS...BUT NOT SEEING A
GREAT SIGNAL FOR SOMETHING WIDESPREAD TO INCLUDE IN THE FORECAST
AS OF YET.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
SURFACE HIGH PRESSURE WILL ESTABLISH ITSELF TO OUR SE ON TUESDAY IN
WAKE OF DEPARTING UPR LVL SYSTEM. WE SHOULD SEE A MOSTLY SUNNY TO
PARTLY SUNNY DAY. MODELS HAD BEEN SUGGESTING THAT PERHAPS A POP OF
SHOWER OR STORM COULD OCCUR IN THE FAR SOUTH DURING THE HEAT OF THE
DAY. THIS STILL MAY OCCUR...BUT DO NOT FEEL IT WARRANTS A 20 POP
MENTION SO HAVE ALLOW THE FORECAST TO REMAIN DRY. HIGHS WILL BE A
LITTLE WARMER...GENERALLY IN THE MID 80S.
FOR THE PERIOD TUESDAY NIGHT INTO WEDNESDAY NIGHT...MAJORITY OF
MODELS HAVE COME MORE IN LINE ON WHAT WILL HAPPEN TO EMBEDDED S/WV
ENERGY WITHIN THE NW FLOW ALOFT. IT APPEARS THIS ENERGY WILL DEVELOP
INTO A CLOSED LOW TO OUR WEST...THEN WILL SLOWLY PROGRESS EAST THROUGH
THE REGION WEDNESDAY INTO WEDNESDAY NIGHT. ECMWF/GFS SUGGEST THAT
SOME EMBEDDED S/WV ENERGY MOVING NE AROUND DEVELOPING CLOSED LOW
COULD SPARK A FEW SHOWERS AND THUNDERSTORMS BEGINNING ACRS OUR SW
TUESDAY NIGHT. HAVE GIVEN ALL LOCATIONS AT LEAST A THREAT FOR
SHOWERS AND STORMS ON WEDNESDAY WITH THE HIGHER CHANCES FAVORING THE
SRN ZONES DUE TO HIGHER INSTABILITY AND MOISTURE. HAVE ALLOWED POPS
TO FALL OFF OVERNIGHT WEDNESDAY NIGHT AS SYSTEM HEADS EAST. HIGHS ON
WEDNESDAY WILL BE SLIGHTLY COOLER...ESPECIALLY SOUTHWEST CLOSER TO
THE UPR LVL LOW.
FOR THE PERIOD THURSDAY INTO FRIDAY NIGHT...MODELS CONTINUE TO
STRUGGLE ON HOW LONG WAVE TROUGH ENERGY WILL DIG SE INTO SE CANADA
AND NEW ENGLAND DURING THE PERIOD. AS SUCH...ASSOCIATED COLD FRONT
AND WHERE IT WILL END UP...I.E. WILL IT PUSH THROUGH...STALL OUT
OVER OUR AREA...OR PERHAPS FALL APART...IS STILL IN QUESTION. HAVE
TAKEN A BLEND OF WPC AND THE LATEST 18.12Z ECMWF...WHICH ALLOWS THE
FRONT TO APPROACH THE REGION FROM THE NORTH THURSDAY NIGHT...SLOW IT
UP AS IT PUSHES INTO THE REMAINDER OF THE AREA ON FRIDAY...THEN
WASHES IT OUT FRIDAY NIGHT INTO SATURDAY AS ANOTHER HIGH PRESSURE
RIDGE BUILDS IN FROM THE NORTH. GIVEN LACK OF STRONG UPR
SUPPORT...AS IT IS FCST TO REMAIN WELL OFF TO THE NE...ALONG WITH
WEAK LOW LEVEL FORCING...HAVE KEPT POPS LOW THURSDAY NIGHT INTO
FRIDAY. HAVE THEN ALLOWED CONDITIONS TO DRY OUT BY FRIDAY NIGHT.
TEMPERATURES WILL BE CLOUD DEPENDENT BUT SHOULD SEE A SLIGHT BUMP UP
AHEAD OF THE FRONT ON THURSDAY WITH SIMILAR OR SLIGHTLY COOLER
CONDITIONS POSSIBLE ON FRIDAY.
SURFACE HIGH PRESSURE WILL MOVE EAST THROUGH THE UPCOMING WEEKEND AS
A MID LVL RIDGE BEGINS TO NUDGE INTO FROM THE CNTRL PLAINS.
CONDITIONS SHOULD REMAIN DRY. TEMPERATURES WILL BE SEASONABLY WARM
FOR LATE AUGUST.
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
SHOWERS OVER THE SOUTHERN SCIOTO VALLEY WILL MOVE NORTH AND AFFECT
CMH/LCK TAF SITES LATER THIS AFTERNOON FOR A BRIEF PERIOD.
ATTM...COVERED THIS WITH VICINITY SHOWER AND NO RESTRICTION TO
VSBY BUT IF THEY HOLD TOGETHER WILL AMEND TO BRING INTO MVFR VSBY
DURING A TEMPO GROUP. THIS IS THE ONLY AREA WITH MVFR CIGS AS WELL
TODAY.
WITH THE LOSS OF DAYTIME HEATING...ANY SHOWERS WILL QUICKLY
DIMINISH THIS EVENING AND CU FIELD OVER REMAINING TAF SITES WILL
ALSO DISSIPATE. WHILE THE AXIS OF THE UPPER LOW IS STILL ALONG AND
SSW OF THE REGION...THE ENERGY THAT IS SPARKING THE RAIN IN THE
SOUTHEAST WILL BE TRANSLATING EAST THROUGH PA TONIGHT.
IF THE CLEARING AND LIGHT WINDS ARE REALIZED...SOME DAYBREAK FOG
WITH GENERALLY MVFR VSBYS WILL OCCUR.
OUTLOOK...NO SIGNIFICANT WEATHER EXPECTED.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...BINAU
NEAR TERM...BINAU
SHORT TERM...BINAU
LONG TERM...HICKMAN
AVIATION...FRANKS
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
154 AM EDT SUN AUG 18 2013
.SYNOPSIS...
HIGH PRESSURE OVER NEW ENGLAND WILL REMAIN IN CONTROL OF THE WEATHER
INTO THURSDAY. A WEAK UPPER LEVEL DISTURBANCE WILL PASS TO THE
SOUTHEAST SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
THE HRRR MODEL CAME AROUND AND AGREES WITH THE CURRENT SITUATION
WHERE HIGH CLOUDS CONTINUE TO RACE NORTH INTO THE EASTERN HALF OF
THE FORECAST AREA THIS EVENING. THIS IS IN RESPONSE TO MOISTURE
PLUME RACING NORTH OUT OF THE GULF OF MEXICO AT THIS TIME. UPDATED
GRIDS AND ZONE FORECAST TO REFLECT CLOUD COVER CHANGES IN THE
EASTERN HALF OF THE AREA. EXPECTING SKIES TO REMAIN MOSTLY CLEAR
IN THE WEST HALF OVERNIGHT. SHOULD SEE SOME RETREATING OF CLOUD
COVER TO THE EAST AFTER MIDNIGHT TONIGHT.
NOT EXPECTING TO MAKE ANY MAJOR CHANGES TO THE REST OF THE FIELDS
WITH THIS UPDATE.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/...
THE AIR MASS WILL CONTINUE TO WARM A LITTLE MORE EACH DAY SO HIGHS
SUN MOSTLY FROM THE UPPER 70S EAST TO LOWER 80S WEST WILL WARM TO
LOW TO MID 80S FAR EAST TO MID TO UPPER 80S WEST BY WED.
THE WEAK UPPER LEVEL TROF OVER THE LOWER OH RIVER VALLEY SUN WILL
LIFT NE INTO THE CWA BY EARLY MON WHILE WEAKENING THEN SHIFT EAST
THRU TUE. THE MODELS DIFFER ON HOW FAR NW THE DEEPER MOISTURE AND
RAIN THREAT WILL BE PULLED. THINK BEST MOVE MAY BE TO TRY AND
MAINTAIN CONTINUITY AND KEEP MAINLY A SLIGHT CHANCE FOR THE SE SUN
EVE THRU MON.
THE MODELS INDICATE ANOTHER WEAK UPPER TROF DROPPING SE INTO THE
AREA TUE WITH MAYBE SOME ISOLATED CONVECTIVE DEVELOPMENT. ANOTHER
WEAK TROF PROGGED TO BE APPROACHING LERI BY END OF WED NIGHT BUT
SURFACE FRONT STILL LOOKS TO BE FAR ENOUGH TO THE NW TO ALLOW WED
NIGHT TO SAY DRY.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
A WARMER AND MORE HUMID AIR MASS IS EXPECTED WEDNESDAY INTO THURSDAY
AS HIGH PRESSURE PERSISTS OVER THE SOUTHEASTERN US. THERE IS A PIECE
OF JET ENERGY MOVING ACROSS ONTARIO ON THURSDAY THAT WILL PUSH A
WEAK COLD FRONT TOWARD NORTHERN OHIO AND NW PA. THERE MAY BE JUST
ENOUGH CONVERGENCE ALONG A LAKE INDUCED BOUNDARY TO ALLOW FOR A
MENTION OF LATE AFTERNOON AND EVENING THUNDERSTORMS. MODELS THEN
STRUGGLE ON WHAT TO DO FRIDAY INTO SATURDAY. IF THE ECMWF IS CORRECT
WE WILL REMAIN WARM AND HUMID AS THE WEAK FRONTAL BOUNDARY FROM
THURSDAY EVENING LIFTS NORTH AS A WARM FRONT INTO FRIDAY NIGHT.
HAVE LEANED TOWARD THE WARMER ECMWF SOLUTION IN THE EXTENDED WITH
HIGHS WELL INTO THE 80S.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
GENERALLY VFR CONDITIONS WILL PERSIST OVERNIGHT AND THROUGH
SUNDAY ALTHOUGH COULD SEE PATCHY EARLY MORNING FOG/MIST RESULTING
IN MVFR VISIBILITIES AROUND SUNRISE. DECENT MOISTURE AROUND 5K
FEET WORKS IN FROM THE SOUTH. HAVE CONTINUED THE BKN DECK FOR
LATER TODAY. CAK/YNG MAY EVEN SEE SOME LIGHT RAIN AFTER 03Z MON
BUT NOT IN TAF JUST YET.
OUTLOOK...NON-VFR POSSIBLE IN EARLY MORNING FOG MONDAY THROUGH
THURSDAY.
&&
.MARINE...
HIGH PRESSURE WILL GENERALLY REMAIN TO THE EAST AND SOUTHEAST OF
LAKE ERIE THROUGH TUESDAY. THIS WILL ALLOW ONSHORE FLOW TO DEVELOP
EACH AFTERNOON. OTHERWISE WE WILL WATCH THE HIGH SLOWLY WEAKEN AND
DRIFT FURTHER SOUTH ALLOWING EASTERLY WINDS TO SHIFT TO A SOUTH AND
SOUTHWEST DIRECTION. THIS WIND SHIFT WILL BE IN RESPONSE TO
DEEPENING LOW PRESSURE OVER NORTHERN ONTARIO. WHILE WINDS WONT BE
ALL THAT STRONG THEY WILL INCREASE TO 10 TO 15 KNOTS FROM THE
SOUTHWEST ON WEDNESDAY INTO THURSDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...ADAMS
NEAR TERM...LOMBARDY
SHORT TERM...ADAMS
LONG TERM...MULLEN
AVIATION...OUDEMAN
MARINE...MULLEN
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
158 AM EDT SUN AUG 18 2013
.SYNOPSIS...
A WEDGE OF COOL HIGH PRESSURE WILL REMAIN IN PLACE OVER THE
CAROLINAS THROUGH THE WEEKEND...THEN GRADUALLY WEAKEN EARLY NEXT
WEEK. MEANWHILE A SERIES OF LOWS WILL RIDE UP ALONG A STATIONARY
FRONTAL BOUNDARY LOCATED ALONG THE CAROLINA COAST BRINGING MOIST
TROPICAL AIR INTO THE SOUTHEAST. THIS WILL GENERATE WIDESPREAD
SHOWERS ACROSS THE AREA THROUGH THE FIRST PART OF THE WEEK. DRIER
AND WARMER WEATHER IS EXPECTED TO RETURN BY THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 1045 PM EDT SATURDAY...SEVERAL BANDS OF SCATTERED SHOWERS
CONTINUE TO PUSH NORTHWARD ACROSS THE REGION WITH THE HEAVIEST RAIN
CURRENTLY FALLING ACROSS THE NORTH CAROLINA PIEDMONT. AS FOR SKY
COVER...MOST LOCATIONS ARE SEEING LOW STRATUS AS THE MOIST BOUNDARY
LAYER SETTLES...WHILE OTHER LOCATIONS ARE SEEING A MIXTURE OF
LOW/MID LEVEL STRATUS. LATEST NAM AND HRRR GUIDANCE LINE UP
WELL WITH THE POP TREND IN THE FORECAST. HOWEVER...DID MAKE A FEW
CHANGES TO THE NEAR TERM POP GRIDS TO ACCOUNT FOR HEAVIER SHOWERS
ACROSS THE NC PIEDMONT AND FURTHER SOUTH INTO THE NORTHEAST GA
MOUNTAINS. OTHERWISE...DID NOT MAKE ANY SIGNIFICANT CHANGES OTHER
THAN ADJUSTING TEMPERATURE AND DEWPOINT TRENDS TO REFLECT LATEST
OBSERVATIONS.
PREVIOUS DISCUSSION...
AS OF 245 PM...CWFA REMAINS IN THE DEEP SLY FLOW BETWEEN UPPER LOW
NEAR THE JUNCTION OF THE OH AND MS RIVERS AND THE BERMUDA ANTI-
CYCLONE. A SERIES OF WAVES WILL MOVE THRU THIS FLOW ALONG WITH A
SERIES OF JET STREAKS PROVIDING SYNOPTIC SCALE LIFT AND UPPER
DIVERGENCE. THIS FLOW ALSO KEEPS A PLUME OF TROPICAL MOISTURE OVER
THE CWFA. PW VALUES ARE NEAR 2 INCHES WHICH IS HIGH...BUT NOT
EXCESSIVELY SO. ISENTROPIC LIFT WILL CONTINUE TO INCREASE ACROSS THE
AREA INTO THE EARLY EVENING BRINGING WIDESPREAD RAINFALL BACK ACROSS
THE AREA. WITH THE FORCING AND PW VALUES...EXPECT MODERATE RAINFALL
AMOUNTS FOR BASIN AVERAGES. CANNOT RULE OUT SOME HEAVY RAINFALL
ADDING UP AFTER A SERIES OF MODERATE RAIN LEADING TO SOME HIGH WATER
LEVELS. HOWEVER...THE THREAT OF ANY WIDESPREAD HEAVY RAINFALL AND/OR
FLOODING IS QUITE LOW. THE BEST ISENTROPIC LIFT MOVES OFF THE THE
NORTH OVERNIGHT AS LOW LEVEL FLOW BECOMES MORE SWLY...AND BEST
FORCING RETREATS TO THE WEST. HOWEVER...LOW LEVEL MOISTURE REMAINS
QUITE HIGH. THEREFORE... EXPECT WIDESPREAD RAINFALL TO DIMINISH WITH
BEST CHC LINGERING OVER THE MTNS. AREAS OF FOG SHUD DEVELOP TOWARD
MORNING AND COULD BECOME DENSE IN AREAS...ESPECIALLY IF WEDGE BEGINS
TO ERODE. LOWS WILL BE A FEW DEGREES BELOW NORMAL.
SUNDAY...UPPER LOW BEGINS TO OPEN UP AND MOVE NORTHEAST THRU THE OH
VALLEY AS THE RIDGING BEGINS TO MOVE IN FROM THE EAST. THIS HELPS
TURN THE FLOW MORE SWLY ENDING THE THREAT OF STRONG ISENTROPIC LIFT
OVER THE AREA. THIS MAY ALSO HELP ERODE THE LOW LEVEL CAD INVERSION
ALLOWING A WEAK SWLY SFC FLOW TO DEVELOP. THIS SHOULD ALLOW THE LOW
LEVELS TO DRY SLIGHTLY CREATING A BREAK IN THE LOW CLOUDS AND SOME
HEATING TO DEVELOP. THIS SHUD ALSO LEAD TO WEAK INSTABILITY DURING
THE AFTERNOON. AGAIN...BEST PRECIP CHC WILL BE OVER THE WEST WHERE
MOISTURE AND FORCING ARE HIGHEST AND IMPINGING RIDGE HAS LESS
INFLUENCE. WITHOUT THE CONTINUATION OF NELY WINDS...LOW CLOUDS AND
STEADY PRECIP...TEMPS WILL BE ABLE TO RISE THRU THE DAY. IN FACT...
LOW LEVEL THICKNESSES WILL BE HIGHER. ANY SUNSHINE WOULD ALLOW A
QUICK RISE IN TEMPS. HOWEVER...EXPECT THERE WILL BE ENUF CLOUDS...
EVEN WITH LOW CLOUDS ERODING...TO RETARD SIGNIFICANT HEATING. THAT
SAID...EXPECT HAVE GONE WITH THE BIAS CORRECTED MOS WHICH IS COOLER
BUT STILL ALLOWS TEMPS TO RISE INTO THE 70S ACROSS THE AREA.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY/...
AS OF 245 PM EDT SATURDAY...A CLOSED UPPER LOW OVER THE WEST WILL
OPEN UP AS IT LEFTS NE ACROSS THE OHIO VALLEY SUN NIGHT INTO MONDAY.
A LOW AMPLITUDE UPPER RIDGE OF HIGH WILL BUILD SOUTH OF THE CWA
TUESDAY WITH A SERIES OF UPPER DISTURBANCES RIPPLING THROUGH THE
REGION IN WEAK WESTERLY FLOW ALOFT.
AT THE SURFACE...THE LATEST NAM HAS TRENDED A BIT FASTER WITH THE
EROSION OF THE COOL AIR WEDGE BY SUN NIGHT WHILE THE GFS KEEPS THE
WEDGE AT LEAST THROUGH MIDDAY MONDAY. NONETHELESS...WE WILL SEE
RETURN SOUTHERLY FLOW BY MONDAY AFTERNOON AS THE HIGH SHIFTS
OFFSHORE AND CONTINUES TO RIDGE INTO THE REGION. THE HIGH WILL
REMAIN CENTERED OFFSHORE TUESDAY WITH CONTINUED SE FLOW REGIME OVER
THE CWA. IN RESPONSE TO THE RETURN FLOW...MODEL SOUNDINGS INDICATE
THAT SBCAPE VALUES WILL BE AROUND 700-1500J/KG WITH PW VALUES
REACHING 2 INCHES BOTH MON AND TUE AFTERNOON. IN ADDITION...THE
MAGNITUDE OF THE MBE VELOCITY WILL BE LESS THAN 10 KTS MEANING
STORMS WILL MOVE SLOWLY. SO LOCALIZED FLASH FLOODING CAN NOT BE
RULED OUT. TEMPERATURES WILL WARM UP INTO THE LOWER 80S EAST OF THE
MOUNTAINS BY MONDAY BUT STILL WE ARE LOOKING AT AROUND 3-5 DEGREES
BELOW NORMAL VALUES.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 200 PM EDT SATURDAY...THE GLOBAL MODELS AGREE THAT AN UPPER
RIDGE WILL PREVAIL OVER THE SE STATES TUE NIGHT INTO THU BEFORE
BECOMING NORTHERLY FLOW ALOFT BY FRI AS AN UPPER TROUGH OVER THE
SOUTH-CENTRAL CANADA DIGS DOWN INTO THE MID ATLANTIC STATES. THE
UPPER FLOW WILL REMAIN NORTHERLY OVER THE REGION THROUGH THE END OF
THE MEDIUM RANGE PERIOD AS A BROAD UPPER RIDGE OF H5 HIGH REMAINS
ANCHORED OVER THE CENTRAL CONUS.
AT THE SURFACE...MOIST SE FLOW WILL PREVAIL TUE NIGHT INTO FRIDAY AS
THE BERMUDA HIGH PRESSURE CONTINUES TO RIDGE INTO THE CWA. MODEL
SOUNDINGS INDICATE THAT ATMOS WILL BE GENERALLY UNCAPPED WITH SBCAPE
VALUES RANGING FROM 1000 TO 2000J/KG ON EACH AFTERNOON. HENCE I HAVE
MENTIONED DIURNAL 30-40 PERCENT POPS DURING THIS PERIOD. BY FRI
NIGHT...THE LATEST 12Z GFS INDICATES THE BERMUDA HIGH WILL WEAKEN
AND SHIFT EAST OF THE AREA AS ANOTHER HIGH PRESSURE CENTERED OVER
THE GREAT LAKES REGION GRADUALLY RIDGES DOWN INTO THE SE STATES.
MEANWHILE...THE 00Z ECMWF KEEPS THE BERMUDA HIGH OVER THE REGION
THROUGH THE END OF THE MEDIUM RANGE PERIOD. GIVEN THE
UNCERTAINTY..HAVE CARRIED LOWER POPS ON SAT. TEMPERATURES WILL
REMAIN A FEW DEGREES BELOW NORMAL THRU THE PERIOD.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AT KCLT...LGT RAIN AND DRIZZLE EXPECTED THRU DAYBREAK WITH LIFR
CONDITIONS...CIGS APPROACHING MINIMUMS. EXPECTING IFR
VSBY...POSSIBLY LOWERING TO LIFR AS WELL. A WEAK WEDGE IS EXPECTED
TO ERODE DURING THE DAY TODAY...BUT MODELS OFTEN ARE TOO FAST AT
IMPROVING CONDITIONS. A MODEL BLEND DOES RESULT IN SLOWER
IMPROVEMENT TREND...BUT STILL EXPECT VFR CONDITIONS BY EARLY/MID
AFTN. GUIDANCE ALSO IN DECENT AGREEMENT THAT WHILE THE WEDGE
ERODES...THERE WILL NOT BE MUCH INSTBY FOR DEEP CONVECTION THIS FAR
NORTH. STILL EXPECT TO SEE AT LEAST SHRA...SO PROB30 FOR THAT. LIGHT
S/SWLY LLVL FLOW AND LINGERING MOISTURE WILL PROBABLY RESULT IN A
RETURN OF LOWER STRATUS AFTER SUNSET THIS EVENING. WINDS WILL BE
CALM OR LIGHT/VRB. PROBABLY FAVOR A N/NE DIRECTION THRU ABOUT LATE
MORNING...THEN SOME OF THE GUIDANCE HAS WINDS TURN OUT OF THE SOUTH.
EITHER WAY...SHUD BE LESS THAN 5 KTS.
ELSEWHERE...EXPECTING IFR/LIFR CIGS THRU MID MORNING ACRS THE
REGION. HOWEVER...STARTING OUT WITH A FEW POCKETS OF HIGHER CIGS DUE
TO SOME MOD RAIN THAT MIXED OUT SOME OF THE MOISTURE. HAVE TEMPO FOR
THE CHANGEABLE HGTS...BUT THINGS SHUD SETTLE BACK TO IFR.
OTHERWISE...BASICALLY THE SAME CONCERNS AS KCLT IN ABOVE PARAGRAPH.
OUTLOOK...SOME IMPROVEMENT TO MOSTLY VFR EXPECTED EARLY NEXT WEEK.
SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS WILL LIKELY CAUSE
RESTRICTIONS BY MID TO LATE WEEK AS DIURNAL EFFECTS DOMINATE.
CONFIDENCE TABLE...
06-12Z 12-18Z 18-24Z 00-06Z
KCLT HIGH 86% MED 73% HIGH 94% MED 71%
KGSP HIGH 81% HIGH 83% HIGH 93% MED 69%
KAVL MED 79% MED 76% MED 77% MED 72%
KHKY MED 76% HIGH 82% HIGH 96% HIGH 86%
KGMU HIGH 84% HIGH 84% HIGH 82% MED 76%
KAND HIGH 88% MED 76% MED 70% HIGH 86%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...PAT
NEAR TERM...CDG/RWH
SHORT TERM...JOH
LONG TERM...JOH
AVIATION...ARK
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
315 AM CDT SUN AUG 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 314 AM CDT SUN AUG 18 2013
WARM AIR ADVECTION REGIME IN FULL SWING THIS MORNING WITH 35+ KT LOW
LEVEL JET ACROSS EASTERN SODAK AND TOP OF UPPER RIDGE NUDGING
OVERHEAD. EARLY MORNING SURFACE ANALYSIS SHOW 6 MB PRESSURE IN
PLACE...TIGHTEST ACROSS SODAK WITH HIGH PRESSURE STILL LOCKED IN
PLACE ACROSS THE SOUTHERN GREAT LAKES/NORTHEAST CONUS. PRESSURE
GRADIENT SHOULD CONTINUE TO TIGHTEN ACROSS THE FORECAST AREA TODAY
IN RESPONSE TO APPROACHING INVERTED SURFACE TROUGH AND UPPER SHORT
WAVE...CURRENTLY OVER SASKATCHEWAN/MONTANA BORDER PER WATER VAPOR
IMAGERY. GOOD MIXING TO AROUND 850MB SHOULD RESULT WITH TEMPERATURES
WARMING TO THE LOW TO UPPER 80S ACROSS THE AREA. THERE IS STILL A
RIBBON OF RESIDUAL MOISTURE IN PLACE THAT WILL ALSO LIKELY RESULT IN
SOME CU DEVELOPMENT THIS AFTERNOON...ESPECIALLY ACROSS SE SODAK.
CONVECTION THAT INITIATES ALONG TRAILING TROUGH ASSOCIATED WITH
APPROACHING SHORT WAVE SHOULD REMAIN NORTHWEST OF THE REGION THIS
EVENING. STRONG THERMAL CAP IN PLACE WILL REALLY LIMIT ANY POTENTIAL
FOR CONVECTION APPROACHING THE FSD CWA...HOWEVER AS WAVE TRAVERSES
THE UPPER RIDGE OVERHEAD LATE EVENING/EARLY MONDAY...THERE IS A
SMALL POSSIBILITY OF ELEVATED ISOLATED STORMS ACCOMPANYING THE
WEAKENING BOUNDARY TOWARD THE HURON AREA. A 30+ KT LLJ ALSO DEVELOPS
WHICH NOSES INTO NE SODAK AND COULD PROVIDE SOME ADDITIONAL LIFT FOR
CONVECTION. AGAIN...MUCH OF THE ACTIVITY SHOULD STAY NORTH OF THE
AREA...WHERE THE STRONGEST CONVERGENCE AND FORCING EXISTS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 314 AM CDT SUN AUG 18 2013
MONDAY INTO TUESDAY LOOKS HOT...DRY WITH ONLY AN AVERAGE SOUTHERLY
WIND. WARM AIR IN THE LOWER AND MID LEVELS BUILDS INTO THE REGION
WITH STEADY TO RISING HEIGHTS ALOFT. THIS SUPPORTS VERY WARM
READINGS...ESPECIALLY ON TUESDAY AS A WEAK BOUNDARY TO THE NORTH MAY
ENHANCE MIXING JUST A BIT IN THE NORTH AND WEST CWA. AIMING FOR 85
TO 90 IN THE EASTERN CWA AND 90 TO 95 IN THE WEST ON MONDAY WITH
MAINLY 90S ON TUESDAY. CENTRAL PARTS OF SOUTH DAKOTA COULD TOUCH THE
CENTURY MARK TUESDAY. WARM MONDAY NIGHT AND TUESDAY NIGHT WITH LOWS
FROM THE UPPER 60S TO AROUND 70.
DURING THE WEDNESDAY THROUGH SATURDAY TIME FRAME...A FAIRLY FLAT
RIDGE WILL BE FOUND ACROSS THE NORTHERN AND CENTRAL PLAINS WITH FAST
MID AND UPPER LEVEL MAINLY WESTERLY FLOW ACROSS SOUTHERN CANADA.
EACH MODEL IS IN FAIRLY GOOD AGREEMENT WITH THIS ASSESSMENT AND
SUSPECT THIS WILL KEEP MOSTLY ABOVE NORMAL TEMPERATURES IN PLACE AND
MAINLY DRY CONDITIONS. AS A JET STREAK PASSES WEDNESDAY NIGHT INTO
THURSDAY THERE WILL BE A SMALL CHANCE FOR THUNDERSTORMS BUT THE
BETTER CHANCES LIKELY OFF TO THE NORTH A BIT. FOR NOW THE ECMWF IS
THE WARMEST WHILE THE GFS AND GEM ARE A LITTLE MORE AGGRESSIVE WITH
THE COOLER AIR THAT LEAKS SOUTH ON WEDNESDAY INTO THURSDAY. WILL
LEAN A LITTLE MORE TOWARDS THE ECMWF OUTPUT AS THE JET STREAK SEEMS
PRETTY FAR NORTH AND THE GEM AND GFS MAY BE OVERDOING THE COOLER AIR
JUST A BIT. THIS MEANS CONTINUED ABOVE NORMAL TEMPERATURES THROUGH
THE ENTIRE PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1040 PM CDT SAT AUG 17 2013
00Z NAM12 AND LATEST RUC13 MODELS ARE CONTINUING TO SHOW THE SAME
TRENDS AS THEIR EARLIER COUNTERPARTS DID. BOTH ARE IN GOOD AGREEMENT
IN BRINGING SOME OF THE STRATUS CURRENTLY IN CENTRAL NEBRASKA
NORTHWARD TONIGHT ALONG THE LOW LEVEL JET. IN OUR FAR WEST...LOWER
END MVFR CEILINGS ARE LIKELY IN GREGORY COUNTY SOUTH DAKOTA. AT
THIS TIME...IT APPEARS THAT THE MAIN PORTION OF THIS STRATUS WILL
STAY TO THE WEST OF KHON DEEPER INTO CENTRAL SOUTH DAKOTA...BUT AM
CONCERNED THAT SOME MVFR FOG WILL DEVELOP IN THE JAMES RIVER VALLEY
AROUND SUNRISE. AS FOR CLOUDS...KEPT THE STRATUS POTENTIAL AT KHON
ONLY IN THE MVFR SCATTERED CATEGORY. FURTHER EAST...BOTH MODELS
ALSO SHOW A STRIPE OF HIGHER BASED STRATUS EXTENDING NORTHEASTWARD
FROM CENTRAL NEB TOWARD THE I 29 CORRIDOR...AS WINDS AROUND 800MB
VEER FROM THE SOUTH TO SOUTHWEST OVERNIGHT. EVIDENCE OF THIS
HAPPENING IS ALREADY OCCURRING WITH O NEILL NEB SHOWING 5000 FOOT
SCATTERED...AND SCATTERED HIGH BASED STRATUS EXTENDING SOUTH OF
THERE. THIS FAR NORTH...THE HIGHER BASED STRATUS SHOULD BE NEAR
4000 FEET AGL AND COULD VERY WELL GO BROKEN AT KFSD BEFORE
SUNRISE...POSSIBLY STAYING SCATTERED AT KSUX.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...08
AVIATION...MJ
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1228 PM CDT SUN AUG 18 2013
.UPDATE...FOR 18Z AVIATION.
&&
.AVIATION...18Z TAF DISCUSSION.
VFR CONDITIONS AT ISSUANCE WILL BE SHORT LIVED THIS AFTERNOON AS
LIGHT RAINS AND LOWER CIGS MOVE INTO THE STATE FROM THE SOUTH.
THESE WILL LIKELY NOT BE CONSTANT...SO CIGS WILL BE UP AND DOWN
FROM HOUR TO HOUR...AND ANY HEAVIER RAINS WILL BRING REDUCED VIS.
WILL PREVAIL THE MOST LIKELY WORST-CASE SCENARIO THROUGH THE
AFTERNOON AND EVENING AT EACH TERMINAL. RAINS WILL TAPER OFF AFTER
00Z FOR KBNA AND KCKV...BUT MAY CONTINUE THROUGH THE NIGHT AT
KCSV.
ALSO LOOKING FOR LIFR TO IFR CONDITIONS FLIGHT CATEGORIES LATE
TONIGHT...AND IMPROVING TO MVFR BY 14-15Z ON MONDAY. WINDS WILL
BE LIGHT OUT OF THE SOUTHEAST.
UNGER
&&
.PREV DISCUSSION... /ISSUED 854 AM CDT SUN AUG 18 2013/
UPDATE...
RADAR CURRENTLY SHOWING LITTLE IF ANY SHOWER ACTIVITY THIS
MORNING. AS THE CLOSED UPPER LOW BEGINS TO OPEN UP AND WEAKEN
LATER TODAY...SOME ATMOSPHERIC DRYING CAN BE EXPECTED WITH TIME.
850 MB FLOW SHOWING SOME CYCLONIC CURVATURE BUT THE BETTER
CONVERGENCE IS WELL SOUTH. PLENTY OF CLOUDINESS AROUND AND THAT
WILL PREVENT MUCH IN THE WAY OF CAPE BUILDUP IN THE AFTERNOON.
HOWEVER...LATEST HRRR STILL SHOWING SOME DEVELOPMENT LATER THIS
MORNING WITH THE ACTIVITY EXPECTED TO LIFT NORTHWARD.
FOR THE UPDATE...WILL LOWER POPS TO A SMALL DEGREE ACROSS EASTERN
AND CENTRAL AREAS. OTW...REMAINDER OF FCST APPEARS TO BE ON TRACK.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
27
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
854 AM CDT SUN AUG 18 2013
.UPDATE...
RADAR CURRENTLY SHOWING LITTLE IF ANY SHOWER ACTIVITY THIS
MORNING. AS THE CLOSED UPPER LOW BEGINS TO OPEN UP AND WEAKEN
LATER TODAY...SOME ATMOSPHERIC DRYING CAN BE EXPECTED WITH TIME.
850 MB FLOW SHOWING SOME CYCLONIC CURVATURE BUT THE BETTER
CONVERGENCE IS WELL SOUTH. PLENTY OF CLOUDINESS AROUND AND THAT
WILL PREVENT MUCH IN THE WAY OF CAPE BUILDUP IN THE AFTERNOON.
HOWEVER...LATEST HRRR STILL SHOWING SOME DEVELOPMENT LATER THIS
MORNING WITH THE ACTIVITY EXPECTED TO LIFT NORTHWARD.
FOR THE UPDATE...WILL LOWER POPS TO A SMALL DEGREE ACROSS EASTERN
AND CENTRAL AREAS. OTW...REMAINDER OF FCST APPEARS TO BE ON TRACK.
&&
.PREV DISCUSSION... /ISSUED 535 AM CDT SUN AUG 18 2013/
UPDATE...FOR 12Z AVIATION FORECASTS.
AVIATION...EXPECT IFR CONDITIONS AT CSV AND CKV THROUGH 16Z AND
MVFR CONDITIONS AT BNA. CONDITIONS AT ALL STATIONS GENERALLY
IMPROVING TO VFR BY 16Z-19Z AND CONTINUING THROUGH 01Z. AFTER 01Z
EXPECT CONDITIONS TO, ONCE AGAIN, DETERIORATE TO MVFR AND IFR
CONDITIONS, WITH LOWERING CIGS AND DEVELOPMENT OF PATCHY FOG.
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE ALSO EXPECTED
DURING THE FORECAST PERIOD.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
21
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
401 PM CDT SUN AUG 18 2013
.SHORT TERM...
Tonight and Tomorrow
Generally dry conditions with high temperatures near normal, with
low temperatures slightly below normal can be expected tonight and
tomorrow. Currently, showers and thunderstorms are developing across
much of the higher terrain of West Texas. The NAM and HRRR have a
pretty good handle on this convection, which is aided by a
disturbance rotating around the periphery of the upper level high
centered over New Mexico. At this time, I believe the majority of
the convection will remain west of our area late this
afternoon/evening, but an isolated shower or thunderstorm cannot be
ruled out across our extreme western counties. For now, I have kept
POPS below 15 percent and will continue to monitor.
Low temperatures overnight will once again fall into the 60s across
most of the area...as winds become light and dewpoint temperatures
remain in the 50s. Slightly above normal temperatures are forecast
on Monday, with highs generally in the mid to upper 90s. An isolated
shower is once again possible across mainly the northern Edwards
Plateau or Western Concho Valley on Monday, but coverage should
remain isolated enough to negate a mention in the grids at this
time.
Daniels
Monday night through Wednesday
Look for dry conditions and temperatures close to seasonal normals.
The good news is flow aloft remains from the east. So, afternoon
highs will not be as hot as they could be, because the 850 mb
thermal ridge remains mainly west of our area. Thus, I`m thinking
highs mainly in the mid 90s and lows around 70 look reasonable.
Huber
.LONG TERM...
Wednesday night through Sunday
An upper-level disturbance may bring showers and thunderstorms to
some of our central and southern counties Thursday and Friday.
Models this run continue to bring an inverted upper-level trough
into our area during the Thursday to Friday time frame. The GFS MOS
data still does not indicate anything other than around a 10 percent
chance for rain for this time frame. However, I decided to continue
the slight chance pops as we had in our previous forecast package,
especially given the potential for at least some rain with easterly
waves this time of year. Otherwise, cooler air at 850 mb continues
to move over West Central Texas for all periods of the long term.
Thus, I`m expecting afternoon highs at or possibly a degree or two
below seasonal normals, with overnight lows very close to
persistence.
Huber
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 68 97 68 94 70 / 5 5 5 5 5
San Angelo 67 99 68 95 70 / 5 5 5 5 5
Junction 65 97 68 95 68 / 5 0 5 10 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
Daniels/Huber
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
127 PM EDT SUN AUG 18 2013
.SYNOPSIS...
A COOL WEDGE OF HIGH PRESSURE WILL REMAIN SITUATED ALONG
THE LEE OF THE CENTRAL APPALACHIANS THIS MORNING BEFORE
SLOWLY WEAKENING FROM WEST TO EAST THIS AFTERNOON. LOW
PRESSURE TRACKING ALONG COASTAL NORTH CAROLINA WILL PASS
OFFSHORE LATER TODAY AHEAD OF ANOTHER UPPER LEVEL DISTURBANCE
THAT WILL AFFECT THE MOUNTAINS OVERNIGHT. THIS UPPER LEVEL
TROUGH OF LOW PRESSURE IS EXPECTED TO PASS ACROSS THE REGION
FROM THE WEST MONDAY KEEPING THE THREAT OF SHOWERS AROUND
INTO MONDAY EVENING.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM EDT SUNDAY...
12Z RNK SOUNDING SHOWS AN IMPRESSIVE WEDGE FOR LATE AUGUST WITH
EAST/NORTHEAST WINDS UP TO 750 MB. ABV THIS LAYER...WINDS HAVE
ALREADY VEERED TO THE SOUTHWEST AND THESE VEERING WINDS ABV THE
WEDGE WILL CONTINUE THROUGH THE DAY RESULTING IN A MORE SHALLOW
LAYER OF MOISTURE AND REDUCED PRECIP RATES.
CHANNELED VORTICITY MOVING THROUGH THE SOUTHWEST FLOW ALOFT WILL
CONTINUE TO GENERATE LIGHT PRECIP...ESPECIALLY ALONG THE THE BLUE
RIDGE AND THE EASTERN SLOPES WITH A LOW LEVEL EASTERLY COMPONENT
TO THE WIND. THEREFORE...CONTINUED LIKELY POPS FOR THIS AREA
THROUGH MUCH OF THE DAY.
VISIBLE SATELLITE IMAGERY IS SHOWING SOME BREAKS IN THE CLOUDS
ACROSS FAR SW VA AND NE TN. MESOSCALE MODELS INCLUDING THE LOCAL
WRF AND HRRR SUGGEST THESE BREAKS MAY EXPAND INTO THE FAR WESTERN
PORTION OF THE FORECAST AREA...INCLUDING NW NC...THE MOUNTAIN
EMPIRE...THE CLINCH VALLEY AND PERHAPS BLF. THIS WILL GENERATE
SOME INSTABILITY AND MAY IGNITE SCATTERED SHOWERS AND ISOLATED
STORMS LATE THIS AFTERNOON.
IN THE EAST...BROUGHT DOWN HIGH TEMPS A COUPLE OF DEGREES AS WE
EXPECT THE WEDGE TO HOLD IN THIS AREA THROUGH THE DAY.
UPPER LOW OPENS UP THIS EVENING WITH CHANNELED VORTICITY CLIPPING
ACROSS THE WEST OVERNIGHT. FORECAST PWATS SHOW SOME DECREASE PER
MORE OF A WEST/SW FLOW...WHILE DYNAMICS LOOK QUITE GOOD UNDER THE
RIGHT REAR OF A 3H JET MAX. PROGGED SWATH OF LOW LEVEL CONVERGENCE
ALSO INDICATED ESPCLY OVER THE SOUTHERN TIER THROUGH MUCH OF THE
NIGHT. MODELS IN TURN DEVELOP A BAND OF CONVECTION OVER THE WEST
EARLY TONIGHT...AND MOVE IT EAST ACROSS THE SOUTHERN TIER COUNTIES
WITH SOME DEGREE OF UNCERTAINTY IN HOW ORGANZIED COVERAGE MAY BE.
THINK ENOUGH CONFIDENCE TO INCLUDE ANOTHER ROUND OF LIKELY POPS
SOUTH TONIGHT WITH DECENT CHANCES ELSW EXCEPT PERHAPS THE FAR EAST
WHERE SOME OF THE WEDGE MAY STILL BE LINGERING. KEPT LOWS IN
BETWEEN THE COOLER MET AND WARMER MAV MOS GIVEN CLOUDS/SHRA AND
ONLY A SLIGHT DECREASE IN DEWPOINTS LATE.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY/...
AS OF 256 AM EDT SUNDAY...
A CLOSED LOW TO THE WEST WILL OPEN INTO A TROUGH ON MONDAY
AS IT TRACKS OVER THE OHIO VALLEY. MODELS SHOWING ONE
SIGNIFICANT SHORT WAVE COMING ACROSS THE AREA MONDAY
MORNING...THEN ANY SHORT WAVES IN THE AFTERNOON STAY SOUTH.
WILL HAVE THE HIGHEST POPS FOR SHOWERS IN THE MORNING...TAPERING
TO SCATTERED CONVECTION IN THE AFTERNOON. FROM MONDAY
AFTERNOON INTO MID WEEK...THE WEATHER PATTERN SHIFTS BACK TO
MOSTLY DIURNAL CONVECTION...FIRING IN THE AFTERNOON...WANING
DURING THE EVENING. THE BEST AREAL COVERAGE OF CONVECTION WILL
BE TO THE SOUTH WHERE THE HIGHEST AMOUNT OF MOISTURE WILL RESIDE.
MORNING SHOWERS AND CLOUDS WILL KEEP MONDAY AFTERNOONS HIGH A
FEW DEGREES COOLER THAN NORMAL. HOWEVER...TEMPERATURES WILL BE
WARMER THAN THIS WEEKEND WITH 70S IN THE WEST TO LOWER 80S IN
THE EAST. TEMPERATURES ARE BACK TO NORMAL ON TUESDAY WITH NEAR
80F IN THE WEST TO MID TO UPPER 80S ACROSS THE EAST.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 1245 PM EDT SATURDAY...
DURING THIS PORTION OF THE FORECAST...MODEL GUIDANCE TRANSITIONS
FROM A NEAR ZONAL FLOW ACROSS THE AREA...TO ONE THAT HAS SOME DEGREE
OF A NORTHWEST FLOW ORIENTATION. THIS COMES WITH DIFFERENCES IN THE
POSITION OF A BUILDING UPPER HIGH/RIDGE. THE GFS SOLUTION IS FARTHER
WEST WITH THE HIGH...KS/MO...AND AS SUCH HAS A STEEPER ANGLE OF THE
NORTHWEST FLOW OVER THE REGION...AND A BETTER SHOT FOR UPSTREAM
DISTURBANCES TO HEAD INTO OR NEAR THE REGION. THE ECWMF OFFERS A
SOLUTION WITH THE CENTER OF THE UPPER HIGH OVER THE LOWER OHIO
VALLEY...WITH STEEPER NORTHWEST FLOW ON ITS EASTERN SIDE MORE OVER
NY/PA THAN OVER OUR REGION. THE OPERATIONAL GFS SOLUTION OFFERS A
COOLER AND POTENTIALLY WETTER SOLUTION AS COMPARED TO THE
OPERATIONAL ECMWF.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 120 PM EDT SUNDAY...
WITH WEDGE REMAINING ALONG THE EASTERN SEABOARD...DEEP MOISTURE PLUME...
AND A NEVER ENDING STREAM OF AMORPHOUS SHORT WAVE ENERGY WAFTING BY...
THERE DOES NOT APPEAR TO BE A VERY COMPELLING REASON TO BUY OFF ON THE
BIG IMPROVEMENT ADVERTISED BY MOS FOR CIGS...WITH THE POSSIBLE EXCEPTION
OF KBLF IN THE SHORT TERM. THUS...WILL TREND THINGS TOWARD A PERSISTANCE
FORECAST AND KEEP CIGS LOW. WITH NO CLEAR CUT DYNAMIC FEATURES TO LATCH
ON TO WILL USE SHRA AS PREVAILING WX OR IN VICINITY AT ALL SITES
THROUGH THE PERIOD...THOUGH EXPECT THE PCPN TO GENERALLY BE ON
THE LIGHT/SPOTTY SIDE.
AS SFC LOW ALONG THE COAST PULLS AWAY THE HIGH PRESSURE CENTER WILL BUILD
SOUTHWARD AND OUT OF THE DEATH WEDGE POSITION. THUS AFTER DAYBREAK TOMORROW...
THINGS SHOULD MIX OUT AND WINDS LOOK SHIFT TO A LIGHT SWLY DIRECTION. EXPECT
A BRIEF IMPROVEMENT EARLY TOMORROW...POSSIBLY TO VFR...BEFORE CONVECTIVE CLOUDS
REDEVELOP AND TURN INTO CONVECTIVE PCPN.
...AVIATION EXTENDED...
WILL TRANSITION TO A WEATHER PATTERN MORE TYPICAL OF MID AUGUST BY
TUESDAY...WITH SOUTHERLY FLOW BECOMING REESTABLISHED...AND
RAINFALL TAKING THE FORM OF DIURNALLY DRIVEN SHOWERS AND
THUNDERSTORMS. TOWARD THE END OF THE WEEK...LONG RANGE MODELS
BEGIN TO DISAGREE AS TO THE PLACEMENT OF AN UPPER RIDGE...WITH THE
GFS MODEL KEEPING THE RIDGE OVER THE PLAINS...WHILE THE ECMWF
CALLS FOR THE RIDGE TO BUILD EAST OF THE MISSISSIPPI RIVER.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...DS/JH
NEAR TERM...JH/PH
SHORT TERM...RCS
LONG TERM...DS
AVIATION...MBS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
942 AM EDT SUN AUG 18 2013
.SYNOPSIS...
A COOL WEDGE OF HIGH PRESSURE WILL REMAIN SITUATED ALONG
THE LEE OF THE CENTRAL APPALACHIANS THIS MORNING BEFORE
SLOWLY WEAKENING FROM WEST TO EAST THIS AFTERNOON. LOW
PRESSURE TRACKING ALONG COASTAL NORTH CAROLINA WILL PASS
OFFSHORE LATER TODAY AHEAD OF ANOTHER UPPER LEVEL DISTURBANCE
THAT WILL AFFECT THE MOUNTAINS OVERNIGHT. THIS UPPER LEVEL
TROUGH OF LOW PRESSURE IS EXPECTED TO PASS ACROSS THE REGION
FROM THE WEST MONDAY KEEPING THE THREAT OF SHOWERS AROUND
INTO MONDAY EVENING.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM EDT SUNDAY...
12Z RNK SOUNDING SHOWS AN IMPRESSIVE WEDGE FOR LATE AUGUST WITH
EAST/NORTHEAST WINDS UP TO 750 MB. ABV THIS LAYER...WINDS HAVE
ALREADY VEERED TO THE SOUTHWEST AND THESE VEERING WINDS ABV THE
WEDGE WILL CONTINUE THROUGH THE DAY RESULTING IN A MORE SHALLOW
LAYER OF MOISTURE AND REDUCED PRECIP RATES.
CHANNELED VORTICITY MOVING THROUGH THE SOUTHWEST FLOW ALOFT WILL
CONTINUE TO GENERATE LIGHT PRECIP...ESPECIALLY ALONG THE THE BLUE
RIDGE AND THE EASTERN SLOPES WITH A LOW LEVEL EASTERLY COMPONENT
TO THE WIND. THEREFORE...CONTINUED LIKELY POPS FOR THIS AREA
THROUGH MUCH OF THE DAY.
VISIBLE SATELLITE IMAGERY IS SHOWING SOME BREAKS IN THE CLOUDS
ACROSS FAR SW VA AND NE TN. MESOSCALE MODELS INCLUDING THE LOCAL
WRF AND HRRR SUGGEST THESE BREAKS MAY EXPAND INTO THE FAR WESTERN
PORTION OF THE FORECAST AREA...INCLUDING NW NC...THE MOUNTAIN
EMPIRE...THE CLINCH VALLEY AND PERHAPS BLF. THIS WILL GENERATE
SOME INSTABILITY AND MAY IGNITE SCATTERED SHOWERS AND ISOLATED
STORMS LATE THIS AFTERNOON.
IN THE EAST...BROUGHT DOWN HIGH TEMPS A COUPLE OF DEGREES AS WE
EXPECT THE WEDGE TO HOLD IN THIS AREA THROUGH THE DAY.
UPPER LOW OPENS UP THIS EVENING WITH CHANNELED VORTICITY CLIPPING
ACROSS THE WEST OVERNIGHT. FORECAST PWATS SHOW SOME DECREASE PER
MORE OF A WEST/SW FLOW...WHILE DYNAMICS LOOK QUITE GOOD UNDER THE
RIGHT REAR OF A 3H JET MAX. PROGGED SWATH OF LOW LEVEL CONVERGENCE
ALSO INDICATED ESPCLY OVER THE SOUTHERN TIER THROUGH MUCH OF THE
NIGHT. MODELS IN TURN DEVELOP A BAND OF CONVECTION OVER THE WEST
EARLY TONIGHT...AND MOVE IT EAST ACROSS THE SOUTHERN TIER COUNTIES
WITH SOME DEGREE OF UNCERTAINTY IN HOW ORGANZIED COVERAGE MAY BE.
THINK ENOUGH CONFIDENCE TO INCLUDE ANOTHER ROUND OF LIKELY POPS
SOUTH TONIGHT WITH DECENT CHANCES ELSW EXCEPT PERHAPS THE FAR EAST
WHERE SOME OF THE WEDGE MAY STILL BE LINGERING. KEPT LOWS IN
BETWEEN THE COOLER MET AND WARMER MAV MOS GIVEN CLOUDS/SHRA AND
ONLY A SLIGHT DECREASE IN DEWPOINTS LATE.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY/...
AS OF 256 AM EDT SUNDAY...
A CLOSED LOW TO THE WEST WILL OPEN INTO A TROUGH ON MONDAY
AS IT TRACKS OVER THE OHIO VALLEY. MODELS SHOWING ONE
SIGNIFICANT SHORT WAVE COMING ACROSS THE AREA MONDAY
MORNING...THEN ANY SHORT WAVES IN THE AFTERNOON STAY SOUTH.
WILL HAVE THE HIGHEST POPS FOR SHOWERS IN THE MORNING...TAPERING
TO SCATTERED CONVECTION IN THE AFTERNOON. FROM MONDAY
AFTERNOON INTO MID WEEK...THE WEATHER PATTERN SHIFTS BACK TO
MOSTLY DIURNAL CONVECTION...FIRING IN THE AFTERNOON...WANING
DURING THE EVENING. THE BEST AREAL COVERAGE OF CONVECTION WILL
BE TO THE SOUTH WHERE THE HIGHEST AMOUNT OF MOISTURE WILL RESIDE.
MORNING SHOWERS AND CLOUDS WILL KEEP MONDAY AFTERNOONS HIGH A
FEW DEGREES COOLER THAN NORMAL. HOWEVER...TEMPERATURES WILL BE
WARMER THAN THIS WEEKEND WITH 70S IN THE WEST TO LOWER 80S IN
THE EAST. TEMPERATURES ARE BACK TO NORMAL ON TUESDAY WITH NEAR
80F IN THE WEST TO MID TO UPPER 80S ACROSS THE EAST.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 1245 PM EDT SATURDAY...
DURING THIS PORTION OF THE FORECAST...MODEL GUIDANCE TRANSITIONS
FROM A NEAR ZONAL FLOW ACROSS THE AREA...TO ONE THAT HAS SOME DEGREE
OF A NORTHWEST FLOW ORIENTATION. THIS COMES WITH DIFFERENCES IN THE
POSITION OF A BUILDING UPPER HIGH/RIDGE. THE GFS SOLUTION IS FARTHER
WEST WITH THE HIGH...KS/MO...AND AS SUCH HAS A STEEPER ANGLE OF THE
NORTHWEST FLOW OVER THE REGION...AND A BETTER SHOT FOR UPSTREAM
DISTURBANCES TO HEAD INTO OR NEAR THE REGION. THE ECWMF OFFERS A
SOLUTION WITH THE CENTER OF THE UPPER HIGH OVER THE LOWER OHIO
VALLEY...WITH STEEPER NORTHWEST FLOW ON ITS EASTERN SIDE MORE OVER
NY/PA THAN OVER OUR REGION. THE OPERATIONAL GFS SOLUTION OFFERS A
COOLER AND POTENTIALLY WETTER SOLUTION AS COMPARED TO THE
OPERATIONAL ECMWF.
&&
.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
AS OF 700 AM EDT SUNDAY...
POOR FLYING CONDITIONS WILL PERSIST INTO THIS AFTERNOON AS A
WEDGE OF COOL AIR AGAINST THE EASTERN SLOPES OF THE MOUNTAINS
KEEPS LOW CIGS AND SPOTTY -RA/-DZ IN PLACE. MAY SEE SOME
IMPROVEMENT OVER THE WESTERN LOCATIONS...MAINLY KBLF/KLWB BY
AFTERNOON WHEN A PERIOD OF VFR LOOKS LIKELY ESPCLY AROUND KBLF.
OTRW VEERING FLOW ALOFT WITH LOW PRESSURE ALONG THE COAST AND
UPPER ENERGY PASSING ACROSS WILL KEEP WIDESPREAD LIGHT TO MODERATE
RAIN GOING ESPCLY BLUE RIDGE THIS MORNING WHERE AIDED BY EASTERLY
UPSLOPE FLOW. THIS SHOULD MAKE FOR CONTINUED MVFR/IFR THROUGH
MIDDAY SUNDAY BEFORE THE WEDGE STARTS TO WEAKEN FROM WEST TO EAST.
LOW CONFIDENCE IN JUST HOW FAST THE IFR CIGS MAY LIFT FROM
KROA/KBCB EAST AS SOUNDINGS INDICATE THE WEDGE HOLDING FOR MUCH
OF THE DAY WHILE ERODING FAR WEST AHEAD OF ANOTHER PIECE OF UPPER
LEVEL LOW PRESSURE. GIVEN TIMING BEING MID AUGUST WILL SHOW MORE
IMPROVEMENT TO MVFR AT KDAN LATER THIS AFTERNOON WITH SOME
LINGERING -RA/-DZ TAPERING TO PATCHY FOG WHICH COULD LINGER INTO
THE EVENING. KBCB LOOKS TO BE THE BREAK BETWEEN THE WEDGE ERODING
IN THE WEST AND LOW CIGS LINGERING IN THE EAST SO LEANED MORE
PESSIMISTIC GIVEN USUAL TENDENCY FOR LOW LEVEL MOISTURE TO BE
SLOWER TO SCOUR THERE AND AT KROA WHERE EAST TO SE FLOW LOOKS TO
HOLD FOR MOST OF THE DAY.
BY THIS EVENING...THE UPPER LOW WILL BEGIN TO OPEN INTO A TROUGH
AND WILL GRADUALLY SHIFT NORTHEAST. AS THIS OCCURS...WINDS WILL
BECOME INCREASINGLY WESTERLY BUT RATHER LIGHT AND COULD GO OVERTOP
THE LINGERING COOL POOL LEAVING LOW CIGS AND FOG IN PLACE OUT EAST.
HOWEVER ANOTHER PASSING SPEED MAX ASSOCIATED WITH THIS SYSTEM MAY
GENERATE ADDED SHRA ESPCLY WEST OF THE BLUE RIDGE INTO TONIGHT
WHERE WILL INCLUDE A VCSH MENTION. OTRW KEEPING CIGS MOSTLY MVFR
WEST TO IFR EAST AS LOW LEVEL MOISTURE WILL BE HARD TO SCOUR AT
NIGHT ESPCLY IF ANY ADDED SHRA DEVELOP AND MOVE EAST.
WILL TRANSITION TO A WEATHER PATTERN MORE TYPICAL OF MID AUGUST BY
TUESDAY...WITH SOUTHERLY FLOW BECOMING REESTABLISHED...AND
RAINFALL TAKING THE FORM OF DIURNALLY DRIVEN SHOWERS AND
THUNDERSTORMS. TOWARD THE END OF THE WEEK...LONG RANGE MODELS
BEGIN TO DISAGREE AS TO THE PLACEMENT OF AN UPPER RIDGE...WITH THE
GFS MODEL KEEPING THE RIDGE OVER THE PLAINS...WHILE THE ECMWF
CALLS FOR THE RIDGE TO BUILD EAST OF THE MISSISSIPPI RIVER.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...DS/JH
NEAR TERM...JH/PH
SHORT TERM...RCS
LONG TERM...DS
AVIATION...JH/MBS/NF
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1034 PM CDT MON AUG 19 2013
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND TUESDAY
ISSUED AT 227 PM CDT MON AUG 19 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A SHORTWAVE
TROUGH MOVING EAST OVER EASTERN MINNESOTA EARLY THIS AFTERNOON.
EARLIER SHOWERS AND STORMS OVER NORTHWEST WISCONSIN FIZZLED AND
THINGS REMAIN QUIET DESPITE DECENT MU CAPES OF OVER 1000 J/KG. WILL
LEAVE A SLIGHT CHANCE OF PRECIP FOR THE REST OF THE AFTERNOON OVER
N-C WISCONSIN THOUGH. CLOUD COVER HAS HELD BACK TEMPS
SOMEWHAT...AND ARE ONLY IN THE UPPER 70S ACROSS THE NORTH. LOOKING
FARTHER UPSTREAM...PLENTY OF CLEAR CONDITIONS OVER THE NORTHERN
PLAINS. SMALL PRECIP CHANCES AND TEMPS ARE THE MAIN FORECAST
CONCERNS IN THE SHORT-TERM.
TONIGHT...THE SHORTWAVE TROUGH MOVING OVER THE WESTERN GREAT LAKES
WILL SHEAR APART INTO TWO FEATURES. ONE WAVE WILL CONTINUE TO MOVE
EAST OVER SOUTHERN ONTARIO WHILE THE OTHER DIVES SOUTH ACROSS IOWA.
AS THIS OCCURS...BAND OF MID AND HIGH LEVEL MOISTURE WILL GET
STRETCHED AND DIMINISH...SO ANTICIPATE CLEARING SKIES TO OCCUR THIS
EVENING. THEN THE 850MB MOISTURE PLUME OVER THE CENTRAL AND
NORTHERN PLAINS EDGES EAST AND NOSES INTO WESTERN AND NORTHERN
WISCONSIN LATE TONIGHT. SCT TO WIDELY SCT CLOUDS ARE OCCURRING
WITHIN THIS MOISTURE PLUME AND BUFKIT SOUNDINGS AT RHI INDICATE
SKINNY CAPE UPWARDS OF 1000 J/KG DEVELOPING BY 09Z. WITH MOISTURE
TRANSPORT OCCURRING...CHANCES OF PRECIP ARE NOT NEGLIGIBLE...BUT
PLENTY OF DRY AIR EXISTS ABOVE 850MB AND MID-LEVEL LAPSE RATES ARE
RATHER POOR. WILL CONTINUE WITH THE DRY FORECAST. MUGGIER CONDITIONS
WITH LOWS IN THE UPPER 50S TO LOW 60S.
TUESDAY...LOW LEVEL MOISTURE PLUME WILL STRETCH FROM KANSAS TO
NORTHWEST WISCONSIN...PUSHING DEWPOINTS INTO THE MIDDLE 60S. WITH
TEMPS RISING INTO THE MID TO UPPER 80S...SHOULD SEE A DECENT CU
FIELD DEVELOP OVER CENTRAL AND NORTH-CENTRAL WISCONSIN. DESPITE
MID-LEVEL CAPPING...ML CAPES TOMORROW WILL REACH UPWARDS OF 2K J/KG
WITH NO CIN. NO TRIGGER ALOFT SO WILL GO WITH THE CONSENSUS WHICH
IS A DRY FORECAST.
.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
ISSUED AT 227 PM CDT MON AUG 19 2013
FOCUS OF THIS PERIOD OF THE FORECAST WILL BE THE COLD FRONT
PASSAGE WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. THIS COLD FRONT
WILL BE SUPPORTED BY A SHORT WAVE TROUGH DROPPING INTO THE
NORTHERN GREAT LAKES REGION ALONG WITH A RRQ REGION OF THE UPPER
JET. INCREASING MOIST WARM UNSTABLE AIR MASS PRODUCING CAPES FROM
2500 TO 3000 J/KG FOR THE AFTERNOON HOURS AHEAD OF THE FRONT.
GOING HWO WILL CONTINUE TO HIGHLIGHT THE SVR THREAT. HEAT INDEX
NUMBERS ALSO CLIMB INTO THE LOWER 90S AHEAD OF THE FRONT ON
WEDNESDAY.
MEDIUM RANGE MODELS CONSISTENT WITH DRIVING THE FRONT SOUTH ON
THURSDAY FOR DRIER CONDITIONS AND MORE NORMAL TEMPERATURES.
PRECIPITATION TRENDS BECOME A CHALLENGE AGAIN LATER FRIDAY INTO
NEXT MONDAY. RETURN FLOW FRIDAY NIGHT INTO SATURDAY MAY PRODUCE A
PERIOD OF WAA CONVECTION...FOLLOWED BY PERIODS OF CONVECTION ON
THE NORTHERN PERIMETER OF THE BUILDING UPPER RIDGE LATER WEEKEND
INTO NEXT MONDAY. ORIENTATION OF THIS RIDGE WILL PLAY A ROLE WHERE
THE BEST CHANCE OF CONVECTION OCCURS. WITH THE BUILDING RIDGE
AGAIN THIS WEEKEND INTO NEXT WEEK...THE WARM AND MORE HUMID
AIR MASS WILL RETURN. HEAT INDEX NUMBERS LIKELY TO CLIMB BACK INTO
THE LOWER 90S EXCEPT FOR LOCATIONS ACROSS THE NORTH WHWERE
CONVECTION CAN DEVELOP.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1031 PM CDT MON AUG 19 2013
LITTLE CHG TO THE FCST REASONING FM EARLIER TNGT. INCREASED
MOISTURE COULD RESULT IN SOME MVFR VSBYS BY MORNING IN FG/HZ.
DEEPENING MIXING WL BRING BACK THE GUSTINESS TO THE WIND AGAIN
TOMORROW. INCREASED MOISTURE COULD RESULT IN SOME LOWER-END VFR
CIGS BY EARLY TOMORROW AFTN...ESP IN C/N-C WI. ATM WL DESTABILIZE
SOME AND THERE DOESN/T APPEAR TO BE ANY CINH REMAINING IN FCST
SOUDNINGS. BUT GIVEN THE LACK OF A TRIGGER...EXPECT CONVECTION TO
BE ISOLD AT BEST AND THUS IT STILL APPEARS THAT THE RISK OF
GETTING TSRA AT TAF SITES NOT GREAT ENOUGH TO WARRANT INCLUSION IN
TAFS AT THIS POINT.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TDH
AVIATION.......SKOWRONSKI
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
636 PM CDT MON AUG 19 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 249 PM CDT MON AUG 19 2013
MAIN FORECAST CONCERNS ARE ON ANY POTENTIAL PRECIPITATION TONIGHT
AND THEN TEMPERATURES FOR TUESDAY.
CURRENTLY AS OF 19Z...
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING
ALONG THE WEST COAST OF BRITISH COLUMBIA...UPPER RIDGING FROM THE
SOUTHWESTERN U.S. INTO THE DAKOTAS...AND A SHORTWAVE TROUGH OVER
CENTRAL MN. THE MAIN IMPACT TO THE FORECAST AREA WITH THE SHORTWAVE
TROUGH HAS BEEN TO SPREAD SOME MID AND HIGH CLOUDS ACROSS. DRY AIR
IN THE MID LEVELS OF THE ATMOSPHERE SEEN ON THE 12Z MPX SOUNDING...
AS WELL AS A CAPPING INVERSION AT 750MB ON THAT SOUNDING...HAS
PREVENTED THE SHORTWAVE FROM PRODUCING PRECIPITATION IN THE FORECAST
AREA. THE CLOUD COVER HAS ALSO HELD BACK TEMPERATURES FROM REACHING
THEIR MAXIMUM POTENTIAL. 16C 850MB TEMP ON THE MPX SOUNDING WAS
ADVECTING EAST INTO THE FORECAST AREA...WHICH NORMALLY WOULD SUPPORT
MID TO EVEN UPPER 80S WITH CLEAR SKIES. HOWEVER...THE CLOUDS HAVE
HELD TEMPS DOWN INTO THE UPPER 70S TO LOW 80S THUS FAR. LOW LEVEL
SOUTHERLY FLOW HAS SLOWLY BEEN BRINGING IN MORE MOISTURE WITH
DEWPOINTS IN THE UPPER 50S TO LOW 60S. TO THE NORTHWEST...A COLD
FRONT STRETCHED FROM CENTRAL MANITOBA INTO WESTERN MONTANA. AHEAD OF
THE FRONT...12Z RAOBS SHOWED EVEN WARMER AIR ACROSS THE NORTHERN
PLAINS...WITH 850MB READINGS OF 20-25C AT BIS...ABR...UNR AND GGW.
700MB TEMPS WERE WARMING AS WELL...BETWEEN 8-13C.
SYNOPTIC OVERVIEW...
THE SHORTWAVE TROUGH OVER CENTRAL MN IS PROGGED TO DROP SOUTH
THROUGH THE FORECAST AREA THIS EVENING...WITH THE EXTENSION OF THE
UPPER RIDGE OVER THE DAKOTAS FOLLOWING IN BEHIND IT FOR THE
OVERNIGHT HOURS INTO TUESDAY.
DETAILS...
GIVEN THE DRY AIRMASS IN PLACE SUB THE MID-CLOUD LAYER AS WELL AS
THE CAPPING...NOT ANTICIPATING ANY PRECIPITATION TO ACCOMPANY THE
SHORTWAVE AS IT DROPS THROUGH THE FORECAST AREA THIS EVENING. WE
SHOULD SEE SOME CLEARING AS WELL...BOTH OF THE MID/HIGH CLOUDS AND
DIURNAL CUMULUS...AS SUBSIDENCE WORKS IN BEHIND THE SHORTWAVE
TROUGH. 850MB MOISTURE TRANSPORT THEN KICKS IN...TRANSPORTING MORE
LOW LEVEL MOISTURE INTO THE AREA. THE 19.12Z NAM/REGIONAL CANADIAN
BOTH DEVELOP A FEW ACCAS TYPE SHOWERS AND THUNDERSTORMS ON THE EDGE
OF THIS MOISTURE TRANSPORT FROM SOUTHEAST MN INTO NORTHWEST WI.
THESE ARE REALLY THE ONLY MODELS SHOWING THIS...AND WITH A BROAD
850MB MOISTURE TRANSPORT PLUME PROGGED COMBINED WITH SUBSIDENCE...
THINK THEY ARE OVERDONE AND KEPT A DRY FORECAST GOING. WORTH KEEPING
AN EYE ON...THOUGH.
THE MORE MOISTURE COMING IN COMBINED WITH DAYTIME HEATING SHOULD
YIELD TO PLENTY OF CUMULUS ON TUESDAY. LITTLE IN THE WAY OF CAPPING
IS PROGGED TOMORROW WITH MLCIN VALUES DROPPING TO 30-40 J/KG IN THE
AFTERNOON...WHILE MLCAPES GROW TO 1500-2500 J/KG. HOWEVER...THERE IS
NO TRIGGER PRESENT TO ALLOW THE RELEASE OF THE INSTABILITY.
THEREFORE...DRY CONDITIONS ARE FORECAST THROUGH TUESDAY.
TEMPERATURES TONIGHT EXPECTED TO BE WARMER...ESPECIALLY OVER THE
NORTHWEST HALF OF THE FORECAST AREA...DUE TO A SOUTHERLY BREEZE AND
HIGHER DEWPOINTS. THE SOUTHERLY BREEZE SHOULD PRECLUDE VALLEY
FOG PRETTY MUCH EVERYWHERE EXCEPT FOR THE WISCONSIN RIVER VALLEY.
850MB AND 925MB TEMPS ARE PROGGED ABOUT 2-3C HIGHER ON TUESDAY
AFTERNOON COMPARED TO THIS AFTERNOON. THESE WARMER TEMPS COMBINED
WITH MORE SUN WILL LEAD TO WARMER CONDITIONS...LIKELY BY 5 OR SO
DEGREES.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 249 PM CDT MON AUG 19 2013
HAZARDS...
HEAT INDICES MAY GET CLOSE TO ADVISORY CRITERIA ON WEDNESDAY AND
AGAIN SUNDAY AND MONDAY. ALSO MONITORING POTENTIAL SEVERE WEATHER
FOR LATE WEDNESDAY.
SYNOPTIC OVERVIEW...
TROUGHING ALONG THE WEST COAST OF BRITISH COLUMBIA IS FORECAST
CONCERN NUMBER 1...WITH MODELS STRUGGLING A BIT ON THE AMPLITUDE OF
THE TROUGH AS IT CROSSES SOUTHERN CANADA THE NEXT COUPLE OF DAYS.
SOME PAST GFS RUNS INDICATED THE TROUGH COULD DIP INTO NORTHERN
MINNESOTA LATE WEDNESDAY...WHEREAS THE ECMWF AS WELL AS THE 19.12Z
GFS KEEP IT TO THE NORTH CROSSING NORTHERN ONTARIO. THIS IS
IMPORTANT AS IT IMPACTS HOW FAR SOUTH DYNAMICAL FORCING WILL REACH
INTO THE FORECAST AREA. ADDITIONALLY...THIS SHORTWAVE TROUGH IS
GOING TO DICTATE THE SPEED OF THE COLD FRONT OVER MONTANA...THE
FORCING ON THE FRONT...AND HOW FAR SOUTH THE FRONT GETS HEADING INTO
THURSDAY AND THURSDAY NIGHT. GOOD MODEL AGREEMENT PERSISTS HEADING
INTO NEXT WEEKEND AS THE SUMMER HEAT RIDGE BUILDS AND STRENGTHENS
OVER THE NATIONS HEARTLAND. VERY LITTLE MOVEMENT OF THIS RIDGE IS
SUGGESTED BY MONDAY.
TUESDAY NIGHT THROUGH THURSDAY...
FOCUS IS ON THE COLD FRONT APPROACHING THE AREA. ALL MODELS ARE
SHOWING AN ELEVATED MIX LAYER...I.E. THE WARMER 850MB AND 700MB AIR
PRESENT CURRENTLY OVER THE NORTHERN PLAINS...ADVECTING INTO THE
FORECAST AREA TUESDAY NIGHT AND WEDNESDAY AHEAD OF THE FRONT. THE
EXACT WARMTH IS ONE FACTOR THAT WILL PLAY INTO WHETHER OR NOT THIS
FRONT CAN INITIATE CONVECTION WEDNESDAY AFTERNOON. ANOTHER FACTOR IS
MOISTURE...WHICH THE 19.12Z GFS AND NAM BOTH APPEAR TO BE OVERDOING
THE SURFACE DEWPOINTS. THEY PROG VALUES IN THE 70-75 RANGE WHILE
MIXING AND THE DRYING SOILS SHOULD RESULT IN READINGS MORE IN THE
MID/UPPER 60S. THESE MIXED LAYER DEWPOINTS RESULT IN MLCIN VALUES OF
30-50 J/KG. A THIRD FACTOR OF CONCERN IS LOW LEVEL CONVERGENCE...
WHICH THE NAM AND GFS BOTH PROG WEAK TO NOTHING PRIOR TO THEIR
CONVECTIVE SCHEMES GOING OFF. THUS...THERE IS PLENTY OF UNCERTAINTY
ON THE EXTENT OF POTENTIAL CONVECTION. IN REALITY...THERE IS A
BETTER SHOT FOR CONVECTION ONCE THE FRONT PASSES...DUE TO THE
DEVELOPMENT OF A POST-FRONTAL LOW TO MID LEVEL FRONTOGENESIS ZONE.
HAVE TAILORED PRECIPITATION CHANCES IN THIS WAY WITH HIGHER VALUES
WEDNESDAY NIGHT. PRECIPITATION CHANCES CONTINUE INTO THURSDAY...
MAINLY SOUTH OF I-90...WHERE THE FRONTOGENESIS ZONE MAY STILL BE
LINGERING. THIS IS ALL DEPENDS ON HOW FAR SOUTH THE FRONT MAKES
IT...THOUGH.
FOR SEVERE WEATHER POTENTIAL...THE 0-6KM SHEAR IS SERIOUSLY LAGGING
THE FRONT. 25 KT IS ABOUT THE HIGHEST AT 00Z AND THATS UP NEAR EAU
CLAIRE. 0-3 KM IS NOT MUCH BETTER WITH SIMILAR VALUES. THUS THINKING
THAT IF THERE IS A SEVERE RISK...MORE LIKELY IT IS UP NORTH OF HWY
10 DURING THE LATE AFTERNOON/EVENING HOURS.
ON THE TEMPERATURE SIDE OF THINGS...925MB READINGS FROM THE
ECMWF/GFS ARE PROGGED TO CLIMB TO 24-26C LATE WEDNESDAY. WITH PLENTY
OF SUN MUCH OF THE DAY AND A SOUTHWEST BREEZE...HIGHS SHOULD TOP OUT
BETWEEN THE UPPER 80S AND MID 90S. DEWPOINTS MIXING DOWN INTO THE
MID TO UPPER 60S WILL HELP TO HOLD HEAT INDICES BELOW ADVISORY
CRITERIA. 925MB TEMPS COOLING TO 20-22C FOR THURSDAY LIKELY TO DROP
TEMPS 5-10 DEGREES FROM WEDNESDAY.
THURSDAY NIGHT THROUGH MONDAY...
INITIAL FOCUS FOR THIS TIME PERIOD IS THE RETURN BACK NORTH OF THE
COLD FRONT...I.E. SWITCHING TO A WARM FRONT...AND IF ANY CONVECTION
CAN FIRE ON THAT. THE 19.00Z ECMWF IS THE MOST BULLISH ON FIRING
CONVECTION FOR THURSDAY NIGHT AND FRIDAY AS THE FRONT LIFTS THROUGH
THE FORECAST AREA. 19.12Z GFS/CANADIAN ARE BOTH DRY.
NEXT CONCERN TURNS TO THE HEAT FOR THE WEEKEND INTO MONDAY AS THE
STRONG SUBTROPICAL RIDGE FORMS OVER NEBRASKA...IOWA...KANSAS AND
MISSOURI. THE BULK OF THE HEAT WITH 850MB TEMPS OF 24C OR HIGHER
LOOKS TO STAY WELL OFF TO THE WEST OVER THE DAKOTAS INTO WESTERN
PORTIONS OF NEBRASKA AND KANSAS. HOWEVER...THEY SHOULD STILL TOP OUT
IN THE 18-22C RANGE FOR SATURDAY THROUGH MONDAY...WITH THE HIGHER
READINGS OF 20-22C LIKELY OCCURRING SUNDAY AND MONDAY. THESE ARE
1.5-2 STANDARD DEVIATIONS ABOVE NORMAL...WHICH WOULD IMPLY CLOSE TO
BUT NOT REACHING OR EXCEEDING RECORD HIGHS. LOW TEMPERATURES COULD
TURN OUT QUITE WARM AS WELL WITH A PERSISTENT SOUTH TO SOUTHWEST
BREEZE. INDICATIONS FROM THE 19.12Z ECMWF THAT THE WELL ABOVE NORMAL
TEMPERATURES COULD STICK AROUND WELL BEYOND MONDAY.
PRECIPITATION CHANCES FOR THE WEEKEND INTO EARLY NEXT WEEK SHOULD
STAY CONFINED MOSTLY NORTH OF THE FORECAST AREA...WHERE THE WARM
FRONT FROM THURSDAY NIGHT/FRIDAY WILL BE LOCATED. THERE ARE
POSSIBILITIES THAT THE FRONT COULD SLIP BACK SOUTH INTO NORTHERN
SECTIONS OF THE FORECAST AREA AT TIMES SUNDAY NIGHT AND
MONDAY...THUS HAVE SOME CHANCES IN FOR THIS PERIOD.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 636 PM CDT MON AUG 19 2013
VFR CONDITIONS SHOULD PREVAIL INTO TUESDAY WITH NEARLY ZONAL UPPER
AIR FLOW SETUP TO THE WEST. SMALL AREA OF MAINLY MID LEVEL MOISTURE
BEHIND PASSING SHORT WAVE TROUGH COULD KEEP A BIT MORE CLOUDS AROUND
TONIGHT THAN PREVIOUS DIURNAL TRENDS BUT STILL UNEVENTFUL.
QUITE A BIT OF SMOKE MIXED IN NOW FROM FIRES ACROSS INTERMOUNTAIN
WEST SO OPTED TO MENTION BRIEF WINDOW OF SLIGHTLY OBSCURED
VISIBILITIES DUE TO HAZE TOWARD DAYBREAK. IMPACT ON AVIATION SHOULD
BE MINIMAL THOUGH.
VERY QUIET ON TUESDAY AGAIN WITH POSSIBILITY OF A FEW CUMULUS
CLOUDS. GRADIENT WILL KEEP STEADY SOUTH TO SOUTHWEST LOW LEVEL WINDS
IN PLACE WELL INTO MID WEEK.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...SHEA
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
.SHORT TERM...TONIGHT AND MONDAY
ISSUED AT 256 PM CDT SUN AUG 18 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
CENTERED OVER THE NE U.S...BUT WITH A RIDGE AXIS THAT EXTENDS WEST
INTO THE GREAT LAKES. THE MAIN STORM TRACK REMAINS NORTH OF THE
REGION OVER SOUTHERN CANADA...BUT IS GRADUALLY SINKING TO THE
SOUTH. AS THIS OCCURS...A SHORTWAVE OVER EASTERN MONTANA IS MOVING
EAST AND PRODUCING THUNDERSTORMS...WHICH WILL TRACK TOWARDS THE
REGION TOMORROW. BESIDES TEMPERATURES...SMALL THUNDERSTORM CHANCES
REMAIN THE MAIN FORECAST CONCERNS.
TONIGHT...THE SHORTWAVE TROUGH OVER EASTERN MONTANA WILL MOVE EAST
INTO THE NORTHERN MISSISSIPPI VALLEY BY 12Z MONDAY. THE 850MB
MOISTURE AND INSTABILITY AXES WILL SHIFT INTO NORTHEAST MINNESOTA BY
THIS TIME...WHICH LOOKS TOO FAR WEST FOR MUCH OF AN IMPACT ON THE
FORECAST AREA. OTHERWISE...SCATTERED HIGH CLOUDS WILL BE PASSING
OVERHEAD FOR MUCH OF NIGHT...AND THEN SEE THE HIGH CLOUDS THICKEN
AND LOWER A BIT LATE AS THE SHORTWAVE DRAWS CLOSER. THE PRESSURE
GRADIENT WILL BE TIGHTENING TONIGHT...WHICH SHOULD ALLOW A LIGHT SW
WIND TO PERSIST AND KEEP ANY FOG FROM FORMING. LOWS WILL CONTINUE
THEIR WARMING TREND...AND RESIDE IN THE 50S.
MONDAY...THE SHORTWAVE TROUGH WILL MOVE INTO WISCONSIN. FORCING
WITH THE WAVE APPEARS TO SUBTLY WEAKEN...SO WILL LIKELY NEED THE
HELP OF DIURNAL INSTABILITY TO GET CONVECTION GOING. THE MOISTURE
AXIS WILL BE SNEAKING INTO NORTH-CENTRAL WISCONSIN IN THE
AFTERNOON...BUT PROGGED NAM SOUNDINGS AT 21Z NEAR EAGLE RIVER SHOW
DECENT CAPPING CENTERED AT ABOUT 800 MB. USING A PARCEL OF
82/62...ML CAPES WILL REACH AROUND 1000 J/KG...WHILE CINS REMAIN A
ROBUST 70-80 J/KG. UNLESS THE CAP IS ADVERTISED TOO
STRONGLY...CANNOT SEE MORE THAN ISOLATED STORM DEVELOPMENT GIVEN THE
WEAK FORCING. IF STORMS DO DEVELOP...WEAK SHEAR ALOFT WILL KEEP THE
SEVERE THREAT RATHER LOW. MADE ONLY MINOR TWEAKS TO TIMING AND
COVERAGE OF POPS. DESPITE AN INCREASE IN CLOUD COVER...LOW LEVEL
TEMPS WILL ALSO BE WARMING...AND PUSH HIGHS INTO THE MIDDLE 80S.
.LONG TERM...MONDAY NIGHT THROUGH SUNDAY
ISSUED AT 256 PM CDT SUN AUG 18 2013
TUESDAY THROUGH NEXT WEEKEND WILL BE HIGHLIGHTED WITH ABOVE
NORMAL TEMPERATURES. THE NEXT MAIN CHANCE FOR WIDESPREAD
PRECIPITATION WILL BE STARTING WEDNESDAY AFTERNOON OVER NORTHWEST
WISCONSIN THEN OVER THE REST OF THE STATE WEDNESDAY NIGHT INTO
THURSDAY WITH THE PASSAGE OF A COLD FRONT.
THERE IS A SMALLER CHANCE OF CONVECTION ON TUESDAY OVER THE
NORTHWEST HALF OF THE STATE DUE TO CONTINUED WAA...AND IN A REGION
OF UPPER DIVERGENCE AHEAD OF THE WESTERLIES OVER THE NORTHERN
PLAINS. CONVECTION MAY BE CONFINED TOWARD WESTERN PORTION OF THE
STATE BUT WILL LEAVE PARTS OF NC WI WITH SMALL CHANCE DUE TO TOTAL
TOTALS INCREASE IN THE AFTERNOON.
THE WESTERLY FLOW OVER THE NORTHERN PLAINS BEGINS TO BUCKLE
WEDNESDAY AS A SHORT WAVE TROUGH DEVELOPS OVER SOUTHERN CANADA
AND A COLD FRONT SAGS INTO THE NORTHERN GREAT LAKES REGION
INCLUDING NORTHWEST WISCONSIN. MEDIUM RANGE MODELS ARE IN GOOD
AGREEMENT WITH THE TIMING OFF THIS FRONT AND CONVECTION UNTIL
WEDNESDAY NIGHT FOR MOST LOCATIONS EXCEPT NORTH CENTRAL WISCONSIN.
SEVERE POTENTIAL REMAINS FOR WEDNESDAY AFTERNOON INTO WEDNESDAY
NIGHT. TOTAL TOTALS CLIMB INTO THE LOWER 50S WITH THE FRONT WHILE
PWATS INCREASE TO NEAR 2.00
GFS...GEM DROP THE CONVECTION AND FRONT WELL SOUTH ON THURSDAY
FOR A DRIER TREND WHICH COULD LAST INTO FRIDAY. BUT THE ECMWF
SLOWS THIS FRONT DOWN WHILE A HIGH PRESSURE SYSTEM DRIFTS OVER
THE NORTHERN GREAT LAKES REGION THURSDAY THROUGH FRIDAY.
THE UPPER RIDGE CONTINUES TO BUILD INTO THE WEEKEND FOR MORE HEAT
ALONG WITH CHANCES OF CONVECTION ON THE PERIPHERY OF THE RIDGE OR
MAINLY THE NORTHERN GREAT LAKES REGION.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1210 PM CDT SUN AUG 18 2013
VFR CONDITIONS WILL PROVIDE GOOD FLYING WEATHER OVER THE
TAF PERIOD. A TIGHTER PRESSURE GRADIENT WILL PREVENT FOG FROM
FORMING LATE TONIGHT. THEN A WEAK DISTURBANCE WILL APPROACH
NORTH-CENTRAL WISCONSIN MONDAY MORNING. CLOUDS WILL BE ON THE
INCREASE DURING THE MORNING HOURS WITH A LOW PROBABILITY OF SHOWERS
ARRIVING. CHANCES IMPROVE MARGINALLY DURING THE AFTERNOON.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TDH
AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1210 PM CDT SUN AUG 18 2013
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND MONDAY
ISSUED AT 350 AM CDT SUN AUG 18 2013
THE MAIN FCST CONCERNS ARE TEMPERATURES AND SMALL PCPN CHANCES.
WV IMAGERY AND RUC ANALYSIS INDICATED UPPER LEVEL RIDGING OVER THE
ROCKIES AND NORTHERN PLAINS...WITH STRONG ZONAL FLOW OVER THE
NORTHERN TIER OF THE U.S. AND CANADA. THE MAIN SHORT-WAVE ENERGY
WAS TRACKING THROUGH SOUTHERN SASK AND MANITOBA. THE WSTRN
PERIPHERY OF A LARGE SFC HIGH PRESSURE SYSTEM WAS STILL SITUATED
OVER WI...WITH STRONG RETURN FLOW SETTING UP IN ADVANCE OF A COLD
FRONT MOVG THROUGH THE DAKOTAS.
HIGH PRESSURE WILL ONCE AGAIN DOMINATE OUR WEATHER TODAY...WITH
UPPER LEVEL ENERGY REMAINING WELL TO OUR NORTH. EXPECT DIURNAL
CUMULUS CLOUDS TO DEVELOP AGAIN TODAY...ALONG WITH AN INCREASE IN
HIGH CLOUDS ACROSS N WI. MIXING THROUGH 825-800 MB SHOULD YIELD
MAX TEMPS IN THE LOWER TO MIDDLE 80S.
A S/W TROF IS EXPECTED TO MOVE INTO NW WI LATE TONIGHT. SOME WAA
WILL ALSO OCCUR OVER NW/NC WI...WITH SOME ELEVATED INSTABILITY
WORKING ITS WAY TOWARD OUR NW COUNTIES BY MORNING. GENERAL MODEL
CONCENSUS IS TO KEEP ANY PCPN JUST NW OF GRB CWA THROUGH 12Z...
SO WILL GO WITH A DRY FCST FOR NOW. THINK THAT FOG WILL LESS OF
THREAT THAN IT HAS BEEN FOR THE PAST SEVERAL NIGHTS...AS THE SFC
PRESSURE GRADIENT TIGHTENS UP AND BOUNDARY LAYER FLOW INCREASES TO
15-20 KTS. TEMPS SHOULD BE A FEW DEGREES WARMER...WITH LOWS IN THE
50S.
ON MONDAY...A S/W TROF WILL MOVE THROUGH NORTHERN WI...PERHAPS
TRIGGERING ISOLD TSTMS WITHIN A WEAK INSTABILITY AXIS OVER NC AND
FAR NE WI. INCREASING SW WINDS SHOULD PULL WARMER TEMPS INTO THE
REGION...BOOSTING HIGHS INTO THE MIDDLE TO UPPER 80S AT MOST
LOCATIONS.
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY
ISSUED AT 350 AM CDT SUN AUG 18 2013
SUMMER TIME PATTERN EXPECTED THROUGH MUCH OF THE WEEK. THE BIG
STORY WILL BE THE HEAT WITH HIGHS WELL INTO THE 80S AND SOME 90S
TUESDAY AND WEDNESDAY. COLD FRONT IS EXPECTED TO ENTER NORTHWEST
WISCONSIN WEDNESDAY AFTERNOON...PASS ACROSS THE AREA WEDNESDAY
NIGHT AND THEN PUSH SOUTH OF THE AREA ON THURSDAY. WITH THE HEAT
AND HUMIDITY IN PLACE ALONG WITH 0-6 KM SHEAR...THERE IS STILL
SOME POTENTIAL FOR STRONG OR SEVERE STORMS ACROSS THE AREA...WHICH
IS ALREADY IN THE HAZARDOUS WEATHER OUTLOOK.
BEYOND WEDNESDAY NIGHT...IT APPEARS THE GFS/CANADIAN ARE TAKING
THE LEAD IN MODEL TRENDS FOR THURSDAY/THURSDAY NIGHT. THIS IS UNUSUAL
SINCE THE ECMWF USUALLY PERFORMS BETTER IN THE OUTER PERIODS. ON THE
00Z RUN TONIGHT...THE GFS/CANADIAN PUSH THE FRONT FAR ENOUGH SOUTH
OF THE AREA TO ALLOW FOR DRY CONDITIONS LATER THURSDAY MORNING
INTO THURSDAY AFTERNOON. HAVE REMOVED POPS ACROSS THE NORTH ON
THURSDAY AND CONTINUED A SMALL CHANCE ACROSS THE SOUTH. FIGURING
THE SMALL CHANCE WOULD BE FOR ANY LINGERING MORNING CONVECTION.
STILL A LOT OF UNCERTAINTY WHEN CONVECTION WOULD RETURN THURSDAY
NIGHT/FRIDAY OR EVEN FRIDAY NIGHT AMONG THE MODELS. WILL LEAVE
FRIDAY/SATURDAY FORECAST ALONE DUE TO LARGE MODEL UNCERTAINTY.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1210 PM CDT SUN AUG 18 2013
VFR CONDITIONS WILL PROVIDE GOOD FLYING WEATHER OVER THE
TAF PERIOD. A TIGHTER PRESSURE GRADIENT WILL PREVENT FOG FROM
FORMING LATE TONIGHT. THEN A WEAK DISTURBANCE WILL APPROACH
NORTH-CENTRAL WISCONSIN MONDAY MORNING. CLOUDS WILL BE ON THE
INCREASE DURING THE MORNING HOURS WITH A LOW PROBABILITY OF SHOWERS
ARRIVING. CHANCES IMPROVE MARGINALLY DURING THE AFTERNOON.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....KIECKBUSCH
LONG TERM......ECKBERG
AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
634 AM CDT SUN AUG 18 2013
UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND MONDAY
ISSUED AT 350 AM CDT SUN AUG 18 2013
THE MAIN FCST CONCERNS ARE TEMPERATURES AND SMALL PCPN CHANCES.
WV IMAGERY AND RUC ANALYSIS INDICATED UPPER LEVEL RIDGING OVER THE
ROCKIES AND NORTHERN PLAINS...WITH STRONG ZONAL FLOW OVER THE
NORTHERN TIER OF THE U.S. AND CANADA. THE MAIN SHORT-WAVE ENERGY
WAS TRACKING THROUGH SOUTHERN SASK AND MANITOBA. THE WSTRN
PERIPHERY OF A LARGE SFC HIGH PRESSURE SYSTEM WAS STILL SITUATED
OVER WI...WITH STRONG RETURN FLOW SETTING UP IN ADVANCE OF A COLD
FRONT MOVG THROUGH THE DAKOTAS.
HIGH PRESSURE WILL ONCE AGAIN DOMINATE OUR WEATHER TODAY...WITH
UPPER LEVEL ENERGY REMAINING WELL TO OUR NORTH. EXPECT DIURNAL
CUMULUS CLOUDS TO DEVELOP AGAIN TODAY...ALONG WITH AN INCREASE IN
HIGH CLOUDS ACROSS N WI. MIXING THROUGH 825-800 MB SHOULD YIELD
MAX TEMPS IN THE LOWER TO MIDDLE 80S.
A S/W TROF IS EXPECTED TO MOVE INTO NW WI LATE TONIGHT. SOME WAA
WILL ALSO OCCUR OVER NW/NC WI...WITH SOME ELEVATED INSTABILITY
WORKING ITS WAY TOWARD OUR NW COUNTIES BY MORNING. GENERAL MODEL
CONCENSUS IS TO KEEP ANY PCPN JUST NW OF GRB CWA THROUGH 12Z...
SO WILL GO WITH A DRY FCST FOR NOW. THINK THAT FOG WILL LESS OF
THREAT THAN IT HAS BEEN FOR THE PAST SEVERAL NIGHTS...AS THE SFC
PRESSURE GRADIENT TIGHTENS UP AND BOUNDARY LAYER FLOW INCREASES TO
15-20 KTS. TEMPS SHOULD BE A FEW DEGREES WARMER...WITH LOWS IN THE
50S.
ON MONDAY...A S/W TROF WILL MOVE THROUGH NORTHERN WI...PERHAPS
TRIGGERING ISOLD TSTMS WITHIN A WEAK INSTABILITY AXIS OVER NC AND
FAR NE WI. INCREASING SW WINDS SHOULD PULL WARMER TEMPS INTO THE
REGION...BOOSTING HIGHS INTO THE MIDDLE TO UPPER 80S AT MOST
LOCATIONS.
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY
ISSUED AT 350 AM CDT SUN AUG 18 2013
SUMMER TIME PATTERN EXPECTED THROUGH MUCH OF THE WEEK. THE BIG
STORY WILL BE THE HEAT WITH HIGHS WELL INTO THE 80S AND SOME 90S
TUESDAY AND WEDNESDAY. COLD FRONT IS EXPECTED TO ENTER NORTHWEST
WISCONSIN WEDNESDAY AFTERNOON...PASS ACROSS THE AREA WEDNESDAY
NIGHT AND THEN PUSH SOUTH OF THE AREA ON THURSDAY. WITH THE HEAT
AND HUMIDITY IN PLACE ALONG WITH 0-6 KM SHEAR...THERE IS STILL
SOME POTENTIAL FOR STRONG OR SEVERE STORMS ACROSS THE AREA...WHICH
IS ALREADY IN THE HAZARDOUS WEATHER OUTLOOK.
BEYOND WEDNESDAY NIGHT...IT APPEARS THE GFS/CANADIAN ARE TAKING
THE LEAD IN MODEL TRENDS FOR THURSDAY/THURSDAY NIGHT. THIS IS UNUSUAL
SINCE THE ECMWF USUALLY PERFORMS BETTER IN THE OUTER PERIODS. ON THE
00Z RUN TONIGHT...THE GFS/CANADIAN PUSH THE FRONT FAR ENOUGH SOUTH
OF THE AREA TO ALLOW FOR DRY CONDITIONS LATER THURSDAY MORNING
INTO THURSDAY AFTERNOON. HAVE REMOVED POPS ACROSS THE NORTH ON
THURSDAY AND CONTINUED A SMALL CHANCE ACROSS THE SOUTH. FIGURING
THE SMALL CHANCE WOULD BE FOR ANY LINGERING MORNING CONVECTION.
STILL A LOT OF UNCERTAINTY WHEN CONVECTION WOULD RETURN THURSDAY
NIGHT/FRIDAY OR EVEN FRIDAY NIGHT AMONG THE MODELS. WILL LEAVE
FRIDAY/SATURDAY FORECAST ALONE DUE TO LARGE MODEL UNCERTAINTY.
&&
.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 626 AM CDT SUN AUG 18 2013
PATTERN IS SIMILAR TO THE PAST 4 OR 5 DAYS...WITH A FEW MINOR
DIFFERENCES. HIGH PRESSURE REMAINS OVER THE REGION...ALTHOUGH
THE PRESSURE GRADIENT IS STARTING TO INCREASE TO OUR NORTHWEST
AS A COLD FRONT APPROACHES FROM THE DAKOTAS. THERE IS ALSO AN
INCREASE IN HIGH CLOUDS ARRIVING FROM THE NORTHERN PLAINS.
LINGERING PATCHY FOG WILL DISSIPATE QUICKLY THIS MORNING...WITH
DIURNAL CUMULUS REFORMING BY LATE MORNING...THEN DISSIPATING BY
EARLY EVG. EXPECT FOG TO BE LESS OF A THREAT TONIGHT...AS LOW
LEVEL WINDS GRADUALLY INCREASE. SCT SHRA/ISOLD TSRA MAY MAKE
THEIR WAY INTO NW WI LATE TONIGHT...BUT SHOULD NOT APPROACH THE
RHI TAF SITE UNTIL AFTER 12Z/MON.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....KIECKBUSCH
LONG TERM......ECKBERG
AVIATION.......KIECKBUSCH
FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND MONDAY
ISSUED AT 350 AM CDT SUN AUG 18 2013
THE MAIN FCST CONCERNS ARE TEMPERATURES AND SMALL PCPN CHANCES.
WV IMAGERY AND RUC ANALYSIS INDICATED UPPER LEVEL RIDGING OVER THE
ROCKIES AND NORTHERN PLAINS...WITH STRONG ZONAL FLOW OVER THE
NORTHERN TIER OF THE U.S. AND CANADA. THE MAIN SHORT-WAVE ENERGY
WAS TRACKING THROUGH SOUTHERN SASK AND MANITOBA. THE WSTRN
PERIPHERY OF A LARGE SFC HIGH PRESSURE SYSTEM WAS STILL SITUATED
OVER WI...WITH STRONG RETURN FLOW SETTING UP IN ADVANCE OF A COLD
FRONT MOVG THROUGH THE DAKOTAS.
HIGH PRESSURE WILL ONCE AGAIN DOMINATE OUR WEATHER TODAY...WITH
UPPER LEVEL ENERGY REMAINING WELL TO OUR NORTH. EXPECT DIURNAL
CUMULUS CLOUDS TO DEVELOP AGAIN TODAY...ALONG WITH AN INCREASE IN
HIGH CLOUDS ACROSS N WI. MIXING THROUGH 825-800 MB SHOULD YIELD
MAX TEMPS IN THE LOWER TO MIDDLE 80S.
A S/W TROF IS EXPECTED TO MOVE INTO NW WI LATE TONIGHT. SOME WAA
WILL ALSO OCCUR OVER NW/NC WI...WITH SOME ELEVATED INSTABILITY
WORKING ITS WAY TOWARD OUR NW COUNTIES BY MORNING. GENERAL MODEL
CONCENSUS IS TO KEEP ANY PCPN JUST NW OF GRB CWA THROUGH 12Z...
SO WILL GO WITH A DRY FCST FOR NOW. THINK THAT FOG WILL LESS OF
THREAT THAN IT HAS BEEN FOR THE PAST SEVERAL NIGHTS...AS THE SFC
PRESSURE GRADIENT TIGHTENS UP AND BOUNDARY LAYER FLOW INCREASES TO
15-20 KTS. TEMPS SHOULD BE A FEW DEGREES WARMER...WITH LOWS IN THE
50S.
ON MONDAY...A S/W TROF WILL MOVE THROUGH NORTHERN WI...PERHAPS
TRIGGERING ISOLD TSTMS WITHIN A WEAK INSTABILITY AXIS OVER NC AND
FAR NE WI. INCREASING SW WINDS SHOULD PULL WARMER TEMPS INTO THE
REGION...BOOSTING HIGHS INTO THE MIDDLE TO UPPER 80S AT MOST
LOCATIONS.
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY
ISSUED AT 350 AM CDT SUN AUG 18 2013
SUMMER TIME PATTERN EXPECTED THROUGH MUCH OF THE WEEK. THE BIG
STORY WILL BE THE HEAT WITH HIGHS WELL INTO THE 80S AND SOME 90S
TUESDAY AND WEDNESDAY. COLD FRONT IS EXPECTED TO ENTER NORTHWEST
WISCONSIN WEDNESDAY AFTERNOON...PASS ACROSS THE AREA WEDNESDAY
NIGHT AND THEN PUSH SOUTH OF THE AREA ON THURSDAY. WITH THE HEAT
AND HUMIDITY IN PLACE ALONG WITH 0-6 KM SHEAR...THERE IS STILL
SOME POTENTIAL FOR STRONG OR SEVERE STORMS ACROSS THE AREA...WHICH
IS ALREADY IN THE HAZARDOUS WEATHER OUTLOOK.
BEYOND WEDNESDAY NIGHT...IT APPEARS THE GFS/CANADIAN ARE TAKING
THE LEAD IN MODEL TRENDS FOR THURSDAY/THURSDAY NIGHT. THIS IS UNUSUAL
SINCE THE ECMWF USUALLY PERFORMS BETTER IN THE OUTER PERIODS. ON THE
00Z RUN TONIGHT...THE GFS/CANADIAN PUSH THE FRONT FAR ENOUGH SOUTH
OF THE AREA TO ALLOW FOR DRY CONDITIONS LATER THURSDAY MORNING
INTO THURSDAY AFTERNOON. HAVE REMOVED POPS ACROSS THE NORTH ON
THURSDAY AND CONTINUED A SMALL CHANCE ACROSS THE SOUTH. FIGURING
THE SMALL CHANCE WOULD BE FOR ANY LINGERING MORNING CONVECTION.
STILL A LOT OF UNCERTAINTY WHEN CONVECTION WOULD RETURN THURSDAY
NIGHT/FRIDAY OR EVEN FRIDAY NIGHT AMONG THE MODELS. WILL LEAVE
FRIDAY/SATURDAY FORECAST ALONE DUE TO LARGE MODEL UNCERTAINTY.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1031 PM CDT SAT AUG 17 2013
SFC HIGH WILL BE A LITTLE FARTHER OFF TO THE SE TNGT...SO THERE WL
BE A BIT OF A SFC PRESSURE GRADIENT ACRS THE AREA...BUT PROBABLY
NOT ENOUGH TO PREVENT DECOUPLING AND WINDS EVENTUALLY GOING CALM
AT MOST LOCATIONS. EXPECT SOME MIFG TO DEVELOP AGAIN TNGT. GIVEN
CHGS DESCRIBED ABV...CONDITIONS ACRS N-C WI WL BE A BIT LESS
FAVORABLE THAN YDA...SO FG THERE WL BE MORE PATCHY THAN LAST NGT.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....KIECKBUSCH
LONG TERM......ECKBERG
AVIATION.......SKOWRONSKI
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1100 PM MDT SAT AUG 17 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 412 PM MDT SAT AUG 17 2013
VISIBLE SATELLITE IMAGERY SHOWS A HIGH LAYER OF SMOKE CONTINUING TO
MOVE SOUTHEAST OVER MUCH OF THE FORECAST AREA TODAY...WITH SOME CU
DEVELOPING OVER THE MOUNTAINS ON THE WESTERN PERIPHERY OF THE SMOKE
LAYER. LLVL INSTABILITY LOOKS WEAK OUT WEST BUT LAPSE RATES
ARE QUITE STEEP WITH SFC TEMPERATURES WARMING INTO THE MID TO UPPER
80S. WITH AN UPPER LEVEL SHORTWAVE MOVING UP FROM UTAH...COULD SEE
SOME MORE VIGOROUS CU TOWERS DEVELOP INTO ISOLATED SHOWERS AND
THUNDERSTORMS LATE THIS AFTERNOON AND EARLY EVENING MAINLY ALONG AND
WEST OF THE LARAMIE RANGE. RUC MODEL HINTS AT A FEW TRYING TO
DEVELOP ACROSS THE EASTERN PLAINS AS WELL IN MOIST UPSLOPE
FLOW...BUT AM NOT CONFIDENT THE CAP WILL BREAK IN THIS AREA TO
DEVELOP MUCH MORE THAN VERY LIGHT SHOWERS. 12Z UPSTREAM RAOBS AND
NAM FORECAST OBS SUGGEST A VERY DEEP MIXING LAYER UP TO 500 MB OR
SO THIS AFTERNOON...HOWEVER WINDS ALOFT REMAIN WEAK. CURRENTLY
SEEING A FEW LOCATIONS ACROSS THE REGION GUSTING 20 TO 25 MPH OR
SO...AND THINK THAT WILL CONTINUE TO BE THE TREND THROUGH THE REST
OF THE AFTERNOON. HUMIDITIES HAVE DROPPED TO THE UPPER SINGLE
DIGITS TO LOW TEENS WITHIN THE LEESIDE TROUGH AND POINTS FURTHER
WEST IN THE ZONE OF GUSTY WINDS...BUT AGAIN WINDS SHOULD REMAIN
BELOW CRITICAL FIRE WEATHER THRESHOLDS SO WILL JUST CONTINUE TO
MENTION HEIGHTENED FIRE WEATHER CONCERNS FOR LATE THIS AFTERNOON.
THE LEESIDE PRESSURE TROUGH WILL REMAIN OVER THE CWA TONIGHT...WITH
MOIST SOUTH TO SOUTHEAST FLOW TO CONTINUE OVER THE EASTERN PLAINS.
WILL GO WITH THE A PERSISTENCE FORECAST WHICH MEANS THE LOW
STRATUS DECK AND FOG WILL RETURN FOR EASTERN PORTIONS OF THE
NEBRASKA PANHANDLE EARLY SUNDAY MORNING. SIMILAR TO THE PREVIOUS
COUPLE OF NIGHTS...THE FOG COULD BE DENSE AT TIMES WITH
VISIBILITIES DROPPING TO ONE HALF MILE OR LESS. THE STRATUS WILL
STEADILY MIX OUT AFTER SUNRISE.
A STRONGER SHORTWAVE WILL MOVE EAST ACROSS THE NORTHERN ROCKIES AND
PLAINS ON SUNDAY AND WILL DROP A WEAK COOL FRONT ACROSS THE FORECAST
AREA LATE SUNDAY AFTERNOON AND EVENING. AHEAD OF THE FRONT...WILL
SEE BREEZY CONDITIONS RETURN TO THE FORECAST AREA IN THE AFTERNOON.
GUIDANCE SUGGESTS THE RETURN OF THE MONSOONAL PLUME TOMORROW AS
WELL SO AFTERNOON HUMIDITIES WILL NOT DRY OUT AS MUCH AS TODAY.
HOWEVER...CONDITIONS WILL REMAIN DRY AND BREEZY ALONG AND WEST OF
THE LARAMIE RANGE SO FIRE WEATHER CONCERNS WILL REMAIN ELEVATED
THROUGH EARLY SUNDAY AFTERNOON. THE INCREASE IN MOISTURE AND FRONT
MOVING SOUTH ACROSS THE REGION WILL BRING A BROADER COVERAGE OF
SHOWERS AND TSTORMS TO THE FORECAST AREA LATE IN THE AFTERNOON AND
EVENING. LOOKING AT MODERATE RAINFALL ALONG WITH GUSTY WINDS FROM
THIS ACTIVITY.
WINDS BEHIND THE FRONT WILL QUICKLY VEER FROM THE NORTH BACK TO THE
SOUTHEAST ON MONDAY BUT WILL REMAIN RELATIVELY LIGHT UNDER WEAK FLOW
ALOFT WITH MINIMAL ENERGY MOVING OVERHEAD. SO COULD SEE A FEW
AFTERNOON SHOWERS AND THUNDERSTORMS ONCE AGAIN IN THIS WEAK UPSLOPE
REGIME...BUT COVERAGE WILL BE LESS THAN SUNDAY DUE TO LACK OF
SIGNIFICANT FORCING.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 412 PM MDT SAT AUG 17 2013
LOOKS LIKE A TRANSITION TO A MORE MOIST AND WETTER PATTERN COULD BE
IN STORE FOR THE EXTENDED ESPECIALLY WEDNESDAY INTO FRIDAY. RIDGE
WILL BE CENTERED AROUND COLORADO ON TUESDAY WITH THE BEST MONSOONAL
MOISTURE TO THE SOUTHWEST ACROSS WESTERN COLORADO AND UTAH. BOTH
THE GFS AND ECMWF HAVE THE RIDGE SHIFTING EASTWARD TOWARD THE
CENTRAL PLAINS BY LATE WEDNESDAY AND INTO THURSDAY. THIS CAUSES
MIDLEVEL FLOW TO GO SOUTHERLY WITH 700-500MB MOISTURE ON THE
INCREASE. AT THE SAME TIME...A SFC HIGH WILL BE POSITIONED OVER THE
DAKOTAS BY WEDNESDAY NIGHT WITH EAST WINDS TRANSPORTING HIGHER SFC
DEWPOINTS UP ALONG THE LARAMIE RANGE. HAVE CHANCE TO SLIGHT CHANCE
POPS OVER MUCH OF SOUTHEAST WY ON WEDNESDAY AND THURSDAY AFTNS AND
EVENINGS WITH PW VALUES RISING UP TO AROUND 1 INCH. WHILE CAPE
VALUES ARE NOT PARTICULARLY HIGH (LESS THAN 1000 J/KG)...STEERING
FLOW IS WEAK (AROUND 10-15 KTS) SO HEAVY RAIN WILL BE THE PRIMARY
THREAT. TUESDAY WILL LIKELY BE THE WARMEST AND DRIEST DAY BEFORE
INCREASING MOISTURE AND CLOUD COVER CAUSE HIGHS TO FALL AROUND 5-10
DEGREES FOR WEDNESDAY THROUGH FRIDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY EVENING)
ISSUED AT 1057 PM MDT SAT AUG 17 2013
FOG EXPECTED TO AGAIN DEVELOP OVER PORTIONS OF THE NEBRASKA
PANHANDLE AFTER MIDNIGHT TONIGHT AND LAST THROUGH MID SUNDAY
MORNING BEFORE COMPLETELY DISSIPATING. LIFR CONDITIONS AT TIMES
WITH THE FOG. ISOLATED THUNDERSTORMS EXPECTED SUNDAY AFTERNOON
WITH ERRATIC GUSTY WINDS NEAR THUNDERSTORM ACTIVITY.
&&
.FIRE WEATHER...
ISSUED AT 412 PM MDT SAT AUG 17 2013
AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL REMAIN OVERHEAD THROUGH
EARLY NEXT WEEK AND WILL MAINTAIN ABOVE NORMAL TEMPERATURES
THROUGH THIS TIME. MOSTLY DRY CONDITIONS WILL CONTINUE FOR THE
REST OF THIS EVENING OUTSIDE OF AN ISOLATED THUNDERSTORM OR TWO
DEVELOPING OVER THE MOUNTAINS. AFTERNOON HUMIDITIES HAVE DROPPED TO
BETWEEN 5 AND 15 PERCENT ALONG AND WEST OF THE LARAMIE RANGE
WITHIN A DRY AND WELL MIXED ENVIRONMENT. IN ADDITION...WINDS IN
THIS AREA ARE GUSTING BETWEEN 20 AND 25 MPH AT TIMES. DRY
CONDITIONS WILL PERSIST THROUGH LATE THIS AFTERNOON BUT WINDS
SHOULD STEADILY EASE. THEREFORE...THESE HEIGHTENED FIRE WEATHER
CONDITIONS ARE EXPECTED TO IMPROVE THROUGH THE REMAINDER OF TODAY.
FOR SUNDAY...MORE MIDLEVEL MOISTURE WILL MOVE OVERHEAD WHICH WILL
KEEP AFTERNOON HUMIDITIES BETWEEN 15 AND 20 PERCENT. GUSTS WILL
ONCE AGAIN BE AROUND 20 TO 25 MPH AND WILL BECOME MORE WIDESPREAD
OVER AND NEAR THE MOUNTAINS IN THE AFTERNOON. IN ADDITION...A WEAK
FRONT MOVING SOUTH ACROSS THE DISTRICT WILL BRING A BETTER
COVERAGE OF SHOWERS AND THUNDERSTORMS IN THE LATE AFTERNOON AND
EVENING.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM...RJM
LONG TERM...FINCH
AVIATION...LIEBL
FIRE WEATHER...RJM
AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
1112 PM PDT MON AUG 19 2013
...A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH MIDWEEK...
...RED FLAG WARNING FOR DRY THUNDERSTORMS IN EFFECT...
.DISCUSSION...AS OF 8:40 PM PDT MONDAY...AN UPPER LOW OFF THE
CENTRAL CA COASTLINE CONTINUES TO DOMINATE THE WEATHER PATTERN.
ALL AFTERNOON AND EVENING A LINE OF THUNDERSTORMS EXTENDING FROM
NEAR HALF MOON BAY WEST OVER 100 NM OFFSHORE HAS PRODUCED
THOUSANDS OF LIGHTNING STRIKES. OVER THE PAST HOUR...THESE
THUNDERSTORMS CONTINUES TO BUILD EAST OVER LAND...WITH LIGHTNING
REPORTED AS FAR EAST AS LOS GATOS. IN FACT...IN A ONE HOUR
PERIOD...ENDING AT 7:55 PM...2570 LIGHTNING STRIKES WERE REPORTED
FROM THIS LINE OF THUNDERSTORMS.
THESE THUNDERSTORMS ARE FORECAST TO CONTINUE THROUGH THE OVERNIGHT
HOURS...AND ACTUALLY BACK BUILD TO THE SOUTH AND EAST. BOTH THE NAM
AND HRRR INDICATE THAT THESE STORMS WILL CONTINUE THROUGH THE
12Z TIME FRAME BEFORE THE LOW SHIFTS SLIGHTLY TO THE WEST ALLOWING
THE CONVECTION TO SHIFT TO THE WEST. THE MAIN CONCERN WITH ALL OF
THESE LIGHTNING STRIKES ARE THE POSSIBILITY OF FIRE STARTS.
OTHERWISE...CURRENT FORECAST LOOKS RIGHT ON TRACK WITH THE MAIN
FOCUS OF THUNDERSTORMS FROM THE SF BAY SOUTHWARD THOUGH THE
MORNING HOURS ON TUESDAY. PLEASE CONTINUE TO MONITOR THE FORECAST
FOR THE LATEST INFORMATION REGARDING THE THUNDERSTORMS ACROSS THE
AREA.
.PREVIOUS DISCUSSION...AS OF 2:26 PM PDT MONDAY...MID/UPPER LEVEL
LOW POSITIONED ABOUT 200 MILES TO THE SOUTHWEST OF MONTEREY THIS
AFTERNOON. THIS FEATURE CONTINUES TO PULL MID-LEVEL MOISTURE
ACROSS THE REGION AND HAS CONTRIBUTED TO ELEVATED CONVECTION
ACROSS THE COASTAL WATERS. AS THE LOW REMAINS OFF THE CENTRAL
COAST...THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL REMAIN IN THE
FORECAST FOR PORTIONS OF THE REGION. CHANCES INCREASE ACROSS THE
NORTH AND DIMINISH OVER THE SOUTH TONIGHT THROUGH WEDNESDAY AS
500-700MB MOISTURE INCREASES AND THE LOW BEGINS TO LIFT TO THE
NORTH-NORTHEAST AND APPROACH THE SAN FRANCISCO BAY REGION.
WITH RESPECT TO TEMPERATURES...AFTERNOON TEMPERATURES WILL BE
SLIGHTLY BELOW SEASONAL AVERAGE THROUGH MIDWEEK AS THE AIR MASS
ASSOCIATED WITH THE UPPER LOW APPROACHES THE REGION. WARMEST
CONDITIONS WILL BE INLAND WITH COOLER TEMPERATURES ALONG THE COAST
WITH PERSISTENT ONSHORE FLOW. INLAND TEMPERATURES MAY BE SLOWER TO
WARM OVER THE NORTH WHERE HIGH CLOUDINESS IS MORE LIKELY.
THE INCREASED MOISTURE WILL KEEP OVERNIGHT TEMPERATURES FROM
FALLING MUCH...AND WILL ALSO ALLOW FOR PATCHY FOG DEVELOPMENT
THROUGH MIDWEEK.
BY THURSDAY THE UPPER LOW QUICKLY GETS PICKED UP BY THE MEAN FLOW
AND PULLS WELL NORTH OF THE REGION. THIS PATTERN WILL BE REPLACED
BY MID/UPPER LEVEL TROUGH OFF THE WEST COAST AND WILL MAINTAIN
BELOW NORMAL TEMPERATURES AND A DRY FORECAST LATE THIS WEEK THROUGH
EARLY NEXT WEEK.
&&
.AVIATION...AS OF 11:00 PM PDT MONDAY...QUITE A BUSY EVE. LINE OF
ELEVATED CONVECTION HAS BEEN TIED CLOSELY TO WHERE RECENT MODEL
FORECASTS HAVE SHOWN TOTAL TOTALS INDEX TO BE AT A MAXIMUM. THE
UPPER LOW OFF THE CENTRAL COAST IS FORECAST TO REMAIN NEARLY
STATIONARY OVERNIGHT. BEST CHANCES FOR ADDITIONAL CONVECTION WILL
REMAIN OVER THE SOUTHERN HALF OF THE FORECAST AREA TONIGHT.
VICINITY OF KSFO...STRATUS COULD HOLD OFF FOR MUCH OF THE NIGHT.
MODERATE CONFIDENCE.
KSFO BRIDGE APPROACH...VFR.
MONTEREY BAY AREA TERMINALS...IFR TONIGHT. CLEARING IS EXPECTED BY
LATE TUESDAY MORNING.
&&
.FIRE WEATHER...AS OF 11:10 AM PDT MONDAY...A STATIONARY UPPER
LEVEL LOW OFF THE SOUTH-CENTRAL CALIFORNIA COAST CONTINUES TO DRAW
MONSOONAL MOISTURE NORTH AND WEST ACROSS CALIFORNIA. THUNDERSTORMS
HAVE THUS FAR BEEN CONFINED TO AREAS WELL TO THE EAST OF THE
DISTRICT...BUT THE MODELS CONTINUE TO FORECAST INCREASING MID
LEVEL MOISTURE AND INSTABILITY ACROSS THE REGION TODAY.
THUS...THUNDERSTORM CHANCES REMAIN IN THE FORECAST.
INITIALLY...ISOLATED THUNDERSTORMS WILL PRODUCE LITTLE...IF
ANY...RAINFALL. WILL CONTINUE WITH A RED FLAG WARNING FOR MOST
INLAND PORTIONS OF THE DISTRICT. THE MODELS HAVE BACKED OFF
SLIGHTLY ON THE AMOUNT OF MOISTURE AND INSTABILITY ACROSS OUR
REGION OVER THE NEXT FEW DAYS...BUT NOT ENOUGH TO WARRANT A
CANCELING OF THE WARNING.
THE LOW WILL BEGIN TO LIFT TO THE NORTH ON TUESDAY AND
THUNDERSTORM CHANCES WILL END FROM SOUTH TO NORTH BEGINNING ON
TUESDAY MORNING. WILL THEREFORE MAINTAIN A RED FLAG WARNING FOR
MONTEREY AND SAN BENITO COUNTIES ONLY THROUGH MIDDAY TUESDAY...BUT
CONTINUE THE WARNING THROUGH AT LEAST TUESDAY NIGHT FOR THE SF BAY
AREA. THUNDERSTORMS WILL LIKELY PRODUCE DECENT RAINFALL BY LATE
MONDAY...BUT EVEN THEN NEW FIRE STARTS WILL STILL BE POSSIBLE
GIVEN HOW DRY THE FUELS ARE.
&&
.FIRE WEATHER...
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.TNGT...RED FLAG WARNING...MOST INLAND PORTIONS OF THE SAN
FRANCISCO AND MONTEREY BAY AREAS.
&&
$$
PUBLIC FORECAST: RILEY/RGASS
AVIATION/MARINE: CANEPA
FIRE WEATHER: RILEY
VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO
FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.SANFRANCISCOBAYAREA.GOV
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA
AREA FORECAST DISCUSSION
NWS SAN JOAQUIN VALLEY - HANFORD CA
1102 PM PDT MON AUG 19 2013
.UPDATE...RAISED POPS AND SKY COVER THRU TUESDAY EVENING OVER THE
MOUNTAINS AND DESERT.
&&
.SYNOPSIS...
A LOW PRESSURE CENTER OFF THE CENTRAL COAST WILL BRING A CHANCE OF
MAINLY AFTERNOON AND EVENING THUNDERSTORMS OVER THE SIERRA NEVADA
THROUGH WEDNESDAY. THERE WILL ALSO BE A SLIGHT CHANCE OF
THUNDERSHOWERS FOR THE SAN JOAQUIN VALLEY THROUGH EARLY TUESDAY
MORNING. THE LOW WILL LIFT NORTHEAST OUT OF THE REGION BY THURSDAY
AND BRING A RETURN OF DRIER WEATHER FOR THE END OF THE WEEK.
&&
.DISCUSSION...AFTER A VERY ACTIVE EVENING LATEST RADAR IMAGERY
SHOWS SHOWERS AND ISOLATED THUNDERSTORMS DIMINISHING FROM FRESNO
COUNTY AND NORTHWARD OVER THE SAN JOAQUIN VALLEY AND SIERRA
NEVADA. ANOTHER ROUND OF SHOWERS AND ISOLATED THUNDERSTORMS IS
POSSIBLE OVER THE MOUNTAINS...SIERRA FOOTHILLS AND DESERT BY TUE
AFTERNOON. CUTOFF LOW REMAINS CENTERED OFF THE COAST OF PT
CONCEPTION AND IS EXPECTED TO MOVE NORTHEASTWARD TOWARD THE SF BAY
AREA BY WEDNESDAY EVENING. HAVE INCREASED POPS FOR TUE AND TUE
EVENING AS CUTOFF LOW WILL REMAIN STATIONARY OFF THE CENTRAL CA
COAST.
&&
.PREVIOUS DISCUSSION...
UPPER LOW OFF THE COAST IN CONJUNCTION WITH LARGE SCALE UPPER
RIDGE OVER THE FOUR CORNERS IS PROVIDING A SQUEEZE PLAY TO STREAM
MID LEVEL SUB TROPICAL MOISTURE INTO THE CENTRAL CA INTERIOR.
T-STORMS ARE ONCE AGAIN FIRING UP OVER THE SIERRA AND ALONG THE
TEHACHAPI RANGE ATTM. UPSLOPE CONDITIONS IN ASSOCIATION WITH
MODERATE MUCAPES FROM THE VEGAS SOUNDING OF OVER 2000 J/KG ARE
PROVIDING ENOUGH LIFT TO GET IT GOING AGAIN TODAY. BLENDED PWAT
VALUES OF 1.0-1.5 ARE OVER THE REGION WILL PROVIDE ENOUGH MOISTURE
TO SUPPORT THUNDERSTORMS. ACTIVE PATTERN WILL CONTINUE INTO THE
OVERNIGHT HOURS AS UPPER LOW REMAINS STATIONARY OFF THE COAST AND
MOISTURE FEED CONTINUES.
19Z RUN OF THE HRRR IS PAINTING MOST OF THE CWA WITH QPF FOR THIS
EVENING. EVEN SPREADS QPF INTO THE VALLEY AND OVER TO THE WEST
SIDE OF THE SJV. SOME FLASH FLOODING IS POSSIBLE WITH THE STORMS
IN THE MOUNTAINS AS MOVEMENT IS ONLY AROUND 10 MPH. ADDITIONAL
FIRE STARTS ARE ALSO POSSIBLE WITH NUMEROUS LIGHTNING STROKES
ASSOCIATED THE STORMS.
THE UPPER LOW BEGINS TO OPEN UP AND LIFT NE. BOTH THE MEAN
ENSEMBLE GFS AND THE 12Z OPERATIONAL ECM ARE IN DECENT AGREEMENT
WITH LIFTING THE FEATURE NE BY WED AND SW FLOW ALOFT SETTING UP
WITH DRIER CONDITIONS. EPAC TROUGH WILL DIG SOUTH AND FEED ANOTHER
ROUND OF SUB TROPICAL MOISTURE INTO THE REGION. HAVE INTRODUCED
POPS FOR SUNDAY AND MONDAY OVER THE SIERRA AND OVER THE
TEHACHAPIS.
&&
.AVIATION...
SCATTERED SHOWERS AND THUNDERSTORMS WITH LOCAL MVFR/IFR CONDITIONS
EXPECTED TO REDEVELOP OVER THE MOUNTAINS AND MOJAVE DESERT AFTER 18Z
TUESDAY. OTHERWISE...MAINLY VFR CONDITIONS WILL PREVAIL THROUGHOUT
THE CENTRAL CALIFORNIA INTERIOR DURING THE NEXT 24 HOURS.
&&
.AIR QUALITY ISSUES...
NONE.
&&
.CERTAINTY...
THE LEVEL OF CERTAINTY FOR DAYS 1 AND 2 IS MEDIUM.
THE LEVEL OF CERTAINTY FOR DAYS 3 THROUGH 7 IS HIGH.
THIS INFORMATION IS PROVIDED AS PART OF A TRIAL PROJECT CONDUCTED
BY THE NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD.
CERTAINTY LEVELS INCLUDE LOW...MEDIUM...AND HIGH. PLEASE VISIT
WWW.WEATHER.GOV/HNX/CERTAINTY.PHP /ALL LOWER CASE/ FOR ADDITIONAL
INFORMATION AND/OR TO PROVIDE FEEDBACK.
&&
.CLIMATE...
RECORDS
SITE DATE HI_MAX:YEAR LO_MAX:YEAR HI_MIN:YEAR LO_MIN:YEAR
KFAT 08-19 108:1892 67:1976 74:2012 54:1916
KFAT 08-20 108:1919 76:1959 75:1986 54:1974
KFAT 08-21 108:1919 80:1968 76:1913 51:1959
KBFL 08-19 109:1950 78:1959 79:1961 52:1913
KBFL 08-20 112:1950 77:1959 79:1950 52:1912
KBFL 08-21 110:1919 80:1968 77:1982 51:1918
&&
.HNX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING UNTIL 11 PM PDT THIS EVENING CAZ094-097.
&&
$$
PUBLIC...BSO
AVN/FW...JEB
SYNOPSIS...ANDERSEN
WEATHER.GOV/HANFORD
AREA FORECAST DISCUSSION
NWS GOODLAND KS
241 AM MDT TUE AUG 20 2013
.SHORT TERM...(TONIGHT THROUGH TUESDAY AFTERNOON)
ISSUED AT 203 PM MDT MON AUG 19 2013
AS OF 3 PM CDT...2 PM MDT...SKIES ACROSS THE TRI-STATE AREA WERE
CLEAR. TEMPERATURES HAVE RESPONDED NICELY WITH THE LACK OF CLOUD
COVER AND RANGED FROM THE MID 80S TO LOW 90S. WINDS WERE FROM THE
SOUTHEAST AT 10 TO 15 MPH WITH GUSTS TO 20 MPH. THE RIDGE OF HIGH
PRESSURE OVER THE SOUTHWEST HAS STRENGTHENED SOME TODAY. SUBSIDENCE
ALOFT WAS ENTRENCHED OVER THE REGION AT THIS TIME.
FOR THE REST OF TODAY AND TONIGHT...WITH THE INFLUENCE OF THE RIDGE
AND SUBSIDENCE ALOFT FIRMLY IN PLACE...PRECIPITATION CHANCES WILL BE
NEAR ZERO. THE HRRR KEEPS SUGGESTING A ISOLATED SHOWER OR STORM IS
POSSIBLE OVER CHEYENNE COUNTY COLORADO BUT NO OTHER MODEL IS
PRODUCING PRECIPITATION OVER THE FORECAST AREA. TEMPERATURES FOR
TONIGHT ARE EXPECTED TO FALL INTO THE LOW 60S UNDER MOSTLY CLEAR
SKIES. LIGHT WINDS AND SOME LINGERING LOW LEVEL MOISTURE MAY ALLOW
FOR SOME PATCHY LIGHT FOG TO FORM...MAINLY ACROSS SOUTHWEST
NEBRASKA. DID NOT THINK THIS WAS WORTHY OF A MENTION IN THE GRIDS AS
VISIBILITIES SHOULD NOT FALL LOWER THAN 4 MILES AT WORSE.
FOR TOMORROW...THE RIDGE OF HIGH PRESSURE WILL STRENGTHEN SLIGHTLY
AGAIN. MODELS PROJECT THAT 850 MB TEMPERATURES WILL WARM A DEGREE OR
TWO OVER TODAYS 850 TEMPS SO A SIMILAR RESPONSE IS EXPECTED IN
SURFACE TEMPERATURES. AS A RESULT...HIGH TEMPERATURES IN THE MID TO
UPPER 90S ARE FORECAST UNDER CLEAR SKIES. SOUTH TO SOUTHEAST WINDS
WILL CONTINUE AS A LEE TROUGH TO THE WEST WILL CONTINUE TO INFLUENCE
THE LOW LEVEL FLOW. BASED ON THE UPPER LEVEL PATTERN AND THE LACK OF
A STRONG DISTURBANCE...PRECIPITATION IS NOT FORECAST FOR TOMORROW.
.LONG TERM...(FRIDAY THROUGH MONDAY)
ISSUED AT 241 AM MDT TUE AUG 20 2013
BROAD UPPER-LEVEL RIDGE DOMINATES THE WX PATTERN THIS WEEKEND AND
INTO EARLY NEXT WEEK. OVER NORTH AMERICA AT THE SYNOPTIC SCALE THIS
RIDGE WILL BE OVER THE CENTRAL PLAINS ON FRIDAY...GRADUALLY BUILDING
TO BECOME AN UPPER-HIGH CENTERED OVER MISSOURI BY EARLY NEXT WEEK.
H5 SOUTH-SOUTHWEST FLOW FROM THIS PATTERN WILL BE UNFAVORABLE FOR
DEVELOPMENT OF STORMS WITH THE NEAREST CHANCE FOR FORCING BEING WHEN
A SHORTWAVE TROUGH MOVES NORTH OVER COLORADO SATURDAY...WHICH ONLY
YUMA COUNTY WOULD HAVE A SHOT AT FOR STORMS SAT NIGHT AT BEST.
SINCE THE THREAT FOR PRECIP VERY LOW OVER THE EXTENDED PERIOD THE
PRIMARY FORECAST CONCERNS WERE MAX/MIN TEMPS AND WINDS. GUIDANCE WAS
PARTICULARLY SOLID FOR TEMPS WITH GFS/ECMWF AND THEIR ENSEMBLES
GIVING SIMILAR RANGES IN THE LOW TO MID 90S THROUGH THE PERIOD...A
BIT ABOVE NORMAL FOR LATE AUGUST BUT NOT UNCOMMON AT ALL. WINDS WILL
BE LIGHT TO BREEZY OUT OF THE SOUTH...WITH A VERY NICE HIGH PLAINS
NOCTURNAL LOW-LEVEL JET EACH NIGHT WITH A 35-45KT MAXIMA AT 850MB.
UNFORTUNATELY THIS LLJ WILL NOT MEAN MUCH FOR THE WEATHER PATTERN
WITH NO STORMS AVAILABLE TO TAKE ADVANTAGE OF IT...WITH SURFACE
WINDS KEEPING UP OR EVEN INCREASING IN THE OVERNIGHT PERIODS BEING
THE MAIN EFFECT OF THIS PHENOMENON.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1059 PM MDT MON AUG 19 2013
VFR TO IFR CONDITIONS FORECAST FOR THE 6Z TAFS. PREVIOUS TAFS LOOK
VERY REASONABLE. AS SUCH MADE ONLY A FEW MODIFICATIONS. BASED ON
YESTERDAY/S OBS AND THE CURRENT DEW POINTS COMPARED TO YESTERDAY/S
EARLY MORNING OBS...AM THINKING FOG IS VERY LIKELY AROUND 12Z.
DEW POINTS ARE ACTUALLY A FEW DEGREES HIGHER NOW THAN WHEN FOG
FORMED YESTERDAY MORNING...AND THERE IS NO REASON THE DEW POINTS
WILL FALL DURING THE NIGHT. WITH A DEEP DRY LAYER ABOVE THE SHALLOW
SATURATION AT THE SURFACE...DO NOT BELIEVE THE FOG WILL LAST VERY
LONG AND SHOULD BE VERY SHORT- LIVED. OTHERWISE WINDS WILL BECOME
BREEZY DURING THE AFTERNOON THEN BECOME LIGHT BY THE EARLY
EVENING.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...RRH
LONG TERM...JJM
AVIATION...JTL
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1120 PM MDT MON AUG 19 2013
.SHORT TERM...(TONIGHT THROUGH TUESDAY AFTERNOON)
ISSUED AT 203 PM MDT MON AUG 19 2013
AS OF 3 PM CDT...2 PM MDT...SKIES ACROSS THE TRI-STATE AREA WERE
CLEAR. TEMPERATURES HAVE RESPONDED NICELY WITH THE LACK OF CLOUD
COVER AND RANGED FROM THE MID 80S TO LOW 90S. WINDS WERE FROM THE
SOUTHEAST AT 10 TO 15 MPH WITH GUSTS TO 20 MPH. THE RIDGE OF HIGH
PRESSURE OVER THE SOUTHWEST HAS STRENGTHENED SOME TODAY. SUBSIDENCE
ALOFT WAS ENTRENCHED OVER THE REGION AT THIS TIME.
FOR THE REST OF TODAY AND TONIGHT...WITH THE INFLUENCE OF THE RIDGE
AND SUBSIDENCE ALOFT FIRMLY IN PLACE...PRECIPITATION CHANCES WILL BE
NEAR ZERO. THE HRRR KEEPS SUGGESTING A ISOLATED SHOWER OR STORM IS
POSSIBLE OVER CHEYENNE COUNTY COLORADO BUT NO OTHER MODEL IS
PRODUCING PRECIPITATION OVER THE FORECAST AREA. TEMPERATURES FOR
TONIGHT ARE EXPECTED TO FALL INTO THE LOW 60S UNDER MOSTLY CLEAR
SKIES. LIGHT WINDS AND SOME LINGERING LOW LEVEL MOISTURE MAY ALLOW
FOR SOME PATCHY LIGHT FOG TO FORM...MAINLY ACROSS SOUTHWEST
NEBRASKA. DID NOT THINK THIS WAS WORTHY OF A MENTION IN THE GRIDS AS
VISIBILITIES SHOULD NOT FALL LOWER THAN 4 MILES AT WORSE.
FOR TOMORROW...THE RIDGE OF HIGH PRESSURE WILL STRENGTHEN SLIGHTLY
AGAIN. MODELS PROJECT THAT 850 MB TEMPERATURES WILL WARM A DEGREE OR
TWO OVER TODAYS 850 TEMPS SO A SIMILAR RESPONSE IS EXPECTED IN
SURFACE TEMPERATURES. AS A RESULT...HIGH TEMPERATURES IN THE MID TO
UPPER 90S ARE FORECAST UNDER CLEAR SKIES. SOUTH TO SOUTHEAST WINDS
WILL CONTINUE AS A LEE TROUGH TO THE WEST WILL CONTINUE TO INFLUENCE
THE LOW LEVEL FLOW. BASED ON THE UPPER LEVEL PATTERN AND THE LACK OF
A STRONG DISTURBANCE...PRECIPITATION IS NOT FORECAST FOR TOMORROW.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 203 PM MDT MON AUG 19 2013
THE UPPER HIGH CURRENTLY OVER COLORADO/ARIZONA IS FORECAST TO
MOVE EAST TO KANSAS/OKLAHOMA BY THE END OF THE WEEK AND
ULTIMATELY WIND UP OVER ILLINOIS BY THE END OF THE PERIOD. THIS
WILL BE THE PRIMARY FEATURE AFFECTING THE WEATHER...AND IN GENERAL
THIS WILL TRANSLATE INTO A WARM AND DRY PERIOD FOR THE FORECAST
AREA.
ONE POSSIBLE CAVEAT TO THE DRY SCENARIO MENTIONED ABOVE WILL BE A
WEAK SHORT WAVE TROUGH FORECAST BY THE NAM AND GFS TO RIDE OVER
THE TOP OF THE RIDGE WEDNESDAY NIGHT. BOTH MODELS INDICATE A
CHANCE FOR SCATTERED CONVECTION WED NIGHT WHILE THE ECMWF KEEPS
THINGS DRY AND THE GEM SHOWS CONVECTION JUST NORTH OF THE AREA.
FOR NOW HAVE KEPT PREVIOUS FORECAST OF LOW CHANCE POPS DURING THIS
TIME WITH AN EMPHASIS ON THE NORTHWEST AND CENTRAL COUNTIES.
TEMPERATURES WILL BE ABOVE NORMAL IN THE LOW-MID 90S FOR MUCH OF
THE PERIOD WHICH IS 5-8 DEGREES ABOVE NORMAL...WHILE LOWS REMAIN
GENERALLY IN THE 60S.
AT THE END OF THE PERIOD AND INTO THE MIDDLE OF NEXT WEEK WHEN THE
UPPER HIGH HAS SHIFTED EAST...THERE WILL BE AN INCREASING WINDOW
OF OPPORTUNITY FOR SCATTERED CONVECTION AS THE AREA COMES UNDER
MORE OF A WEAK SOUTHWEST FLOW ALOFT. UNTIL THEN...PRECIP CHANCES
LOOK MEAGER.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1059 PM MDT MON AUG 19 2013
VFR TO IFR CONDITIONS FORECAST FOR THE 6Z TAFS. PREVIOUS TAFS LOOK
VERY REASONABLE. AS SUCH MADE ONLY A FEW MODIFICATIONS. BASED ON
YESTERDAY/S OBS AND THE CURRENT DEW POINTS COMPARED TO YESTERDAY/S
EARLY MORNING OBS...AM THINKING FOG IS VERY LIKELY AROUND 12Z.
DEW POINTS ARE ACTUALLY A FEW DEGREES HIGHER NOW THAN WHEN FOG
FORMED YESTERDAY MORNING...AND THERE IS NO REASON THE DEW POINTS
WILL FALL DURING THE NIGHT. WITH A DEEP DRY LAYER ABOVE THE SHALLOW
SATURATION AT THE SURFACE...DO NOT BELIEVE THE FOG WILL LAST VERY
LONG AND SHOULD BE VERY SHORT- LIVED. OTHERWISE WINDS WILL BECOME
BREEZY DURING THE AFTERNOON THEN BECOME LIGHT BY THE EARLY
EVENING.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...RRH
LONG TERM...DLF
AVIATION...JTL
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
406 AM EDT TUE AUG 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 405 AM EDT TUE AUG 20 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW REBOUNDING UPR RDG
INTO THE UPR GRT LKS ON THE SRN FLANK OF ZONAL FLOW OVER CANADA. A
PRONOUNCED H5 THERMAL RDG IS EVIDENT STRETCHING FM THE NRN PLAINS
THRU NW MN AND INTO NW ONTARIO...WITH THE 00Z H5 TEMP UP TO -7C AT
INL...COMPARED TO THE -11C OBS AT APX CLOSER TO DEPARTING SHRTWV IN
THE CENTRAL LKS. THE COMBINATION OF THE ASSOCIATED MID LVL CAPPING
AND SUBSIDENCE RELATED TO DEEP LYR QVECTOR DVGC ACCOMPANYING THE
BLDG RDG IS RESULTING IN MOCLR SKIES OVER THE CWA EARLY THIS MRNG
DESPITE ADVECTION OF SOMEWHAT HIER LLVL MSTR WITH H85 DEWPTS UP TO
16C AT MPX IN THE SW FLOW ARND SFC HI PRES IN THE MID ATLANTIC
STATES. DESPITE THE MOCLR SKIES...THE STEADY SW FLOW IS RESULTING IN
ABV NORMAL TEMPS EARLY THIS MRNG...ESPECIALLY OVER THE W HALF OF UPR
MI IN THE DOWNSLOPE AREAS NEAR LK SUP...WHERE READINGS ARE HAVING A
HARD TIME FALLING BLO 70. BUT EVEN WARMER AIR IS TO THE W...WITH 00Z
H85 TEMPS RANGING FM 14C AT GRB AND APX TO 17C AT MPX...19C AT
INL...AND A TOASTY 25C AT BISMARCK. THERE IS ANOTHER SHRTWV SHIFTING
EWD THRU THE NRN PLAINS...BUT THE 00Z BISMARCK RAOB IS SO DRY THERE
IS NO PCPN OR EVEN ANY CLD COVER.
MAIN FCST CONCERNS IN THE SHORT TERM FOCUS ON TEMPS AND SMALL SHRA/
TS CHCS.
TODAY...UPR MI IS FCST TO REMAIN UNDER THE UPR RDG AXIS...WITH H5
THERMAL RDG/TEMPS ARND -7C NOTED ABOVE SHIFTING OVHD IN MID LVL
SUBSIDENCE REGIME. CONTINUED SW FLOW ARND STAGNANT SFC HI PRES IN
THE MID ATLANTIC IS FCST TO LIFT H85 TEMPS UP TO 17-18C OVER THE E
TO 18-19C OVER THE W BY 00Z WED. MIXING TO H8 ON GFS/NAM FCST SDNGS
YIELDS HI TEMPS REACHING TO ARND 90 AWAY FM THE COOLING INFLUENCE OF
LK MI...SO PREFER TO HEDGE TOWARD THE HI END OF GUIDANCE FOR MAX
TEMPS FCST. THIS SW FLOW WL ALSO ADVECT THE HIER LLVL MSTR SHOWN ON
THE 00Z MPX RAOB INTO THE UPR LKS...RESULTING IN A MORE HUMID AND
UNCOMFORTABLE DAY AS SFC DEWPTS RUN WELL INTO THE 60S. DESPITE THE
INCRSG HEAT/HUMIDITY THAT WL LIFT MUCAPE AOA 2000J/KG THIS AFTN PER
MODIFIED GFS/NAM FCST SDNGS FOR SFC T/TD 90/65...SUSPECT THE MID LVL
WARMTH/DRYNESS/STABILITY WL SUPPRESS CONVECTION. ONE POSITIVE FOR
SHRA/TS WOULD BE THE APRCH LATER THIS AFTN OF SHRTWV NOW MOVING THRU
THE NRN PLAINS...BUT CONSIDERING GFS/NAM MOS POPS AOB 10 PCT...
PRESENCE OF VERY WARM H5 AIR/SHARPER CAPPING...AND ABSENCE OF
APPRECIABLE LK BREEZE CNVGC WITH SUPPRESSION OF LK SUP BREEZE IN
SYNOPTIC SW FLOW...OPTED TO GO DRY FOR THE ENTIRE CWA TODAY.
TNGT...STEADY SW FLOW WITH H925 WINDS UP TO 30-35KTS UNDER
SHARPENING PRES GRADIENT BTWN MID ATLANTIC HI PRES AND APRCHG COLD
FNT IN MN ASSOCIATED WITH SHRTWV RIDING E IN THE ZONAL FLOW THRU
CANADA IS FCST TO LIFT H85 TEMPS AOA 20C OVER THE WRN CWA OVERNGT.
WL TEND AOA THE HI END OF GUIDANCE FOR MIN TEMPS...ESPECIALLY IN THE
DOWNSLOPE AREAS NEAR LK SUP OVER THE W HALF. CONCERNED THE ARRIVAL
OF SOME DEEP LYR QVECTOR CNVGC/STEEPENING LAPSE RATES WITH FALLING
H5 TEMPS TOWARD -10C IN ADVANCE OF THE FNT LATE TNGT MIGHT GENERATE
SOME SHRA/TS OVER AT LEAST THE NW HALF OF THE CWA. ALTHOUGH THE BULK
OF THE NUMERICAL MODELS SHOW A DRY FCST FOR THE CWA THRU 12Z WED...
OPTED TO RETAIN SOME SCHC POPS OVER THE MAINLY WRN/NCENTRAL LK SUP
SINCE THERE WL BE SOME DYNAMIC SUPPORT AND THE GFS AS WELL AS THE
LOCAL WRF/ARW MODELS DO GENERATE SOME PCPN.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 405 AM EDT TUE AUG 20 2013
NOT TOO MUCH HAS CHANGED SINCE 24 HOURS AGO...AND AM WELL IN
AGREEMENT WITH THE PREVIOUS SHIFT. STILL HAVE SOME
UNCERTAINTY...ESPECIALLY WITH SOME SPECIFIC ITEMS...BUT WILL TALK
ABOUT THAT IN MORE DETAIL BELOW.
FOR WED...A NRN STREAM TROUGH WILL SLIDE ACROSS THE CWA WED INTO WED
NIGHT...WHICH WILL BRING INCREASED CHANCES OF PRECIP FOR THAT
PERIOD. WITH 850MB TEMPS AROUND 20C AT PEAK HEATING WED
AFTERNOON...HIGH TEMPS AHEAD OF THE FRONT AND ASSOCIATED PRECIP AND
CLOUD COVER SHOULD BE ABLE TO GET INTO THE LOW 90S /AWAY FROM LAKE
MICHIGAN FROM MODERATING SW WINDS AND IMMEDIATE SHORES OF LAKE
SUPERIOR/. THE SW-NE ORIENTED COLD FRONT LOOKS TO MOVE INTO WRN
UPPER MI AROUND 18Z WED...WITH SOME VARIABILITY BETWEEN THE MODELS
/ECMWF AND GFS SHOWING THIS SOLUTION AND THE NAM AND GEM BEING
FASTER/. BY 00Z THU...MODELS SHOW THE COLD FRONT FROM ERN LAKE
SUPERIOR INTO SCENTRAL UPPER MI...WITH THE FRONT JUST E OF THE CWA
BY 06Z THU. SHOULD SEE CAPE VALUES OF 1500-2500J/KG AND POSSIBLY AS
HIGH AS 3000J/KG AHEAD OF THE FRONT. 0-6KM SHEAR LOOKS TO BE ON THE
LOW SIDE FOR ORGANIZED THUNDERSTORMS AT AROUND 20KTS...AND THAT IS
MOSTLY UNIDIRECTIONAL. STORM MODE SHOULD BE MULTICELL CLUSTERS AND
BEST THREAT FOR SEVERE WEATHER WILL BE MORE ISOLATED DAMAGING
WINDS...ESPECIALLY OVER THE SCENTRAL CWA WHERE DCAPE VALUES WILL BE
ENHANCED. HAIL THREAT WILL BE MORE MINIMAL DUE TO WEAK SHEAR AND THE
FREEZING LEVEL BEING AROUND 12KFT. WILL CONTINUE TO SHOW LIKELY POPS
OVER MUCH OF THE AREA TIMED CLOSE TO EXPECTED FROPA. WITH THE
UNCERTAINTY IN FRONTAL TIMING...HIGH TEMPS MAY BE MORE IN JEOPARDY
IF THE FRONT COMES THROUGH FASTER AND CONVECTIVE COVERAGE/INTENSITY
IS MORE UNCERTAIN.
BY LATE WED NIGHT...SHOULD SEE ALL PRECIP AND MOST CLOUDS CLEARED
OUT AS AS SFC HIGH MOVES IN FROM THE W...AND WITH 850MB TEMPS AROUND
12C BY 12Z THU...LOW TEMPS SHOULD BE ABLE TO QUICKLY FALL OFF TO
AROUND 50F OVER PARTS OF THE INTERIOR W.
WHILE A COUPLE OF UPPER SHORTWAVES MOVE THROUGH THU AND FRI...THE
SFC HIGH WILL BE DIRECTLY OVER THE CWA LATE THU INTO THU NIGHT...AND
WILL HAVE JUST MOVED E OFF THE CWA BY LATE FRI...SO IT WILL BE TOO
DRY FOR ANY PRECIP OVER THE CWA RESULTING FROM THE SHORTWAVES. 850MB
TEMPS COOL SOME MORE WITH CONTINUED NLY FLOW AND THE SHORTWAVE ON
THU TO AROUND 10-11C...RESULTING IN MUCH COOLER HIGH TEMPS IN THE
70S /OR POSSIBLY LOW 80S OVER FAR SCENTRAL UPPER MI/. FRI TEMPS LOOK
SIMILAR IF NOT A DEGREE OR TWO COOLER IN MOST LOCATIONS.
MORE UNCERTAIN ON LATER TIME FRAMES...BUT SOME PRECIP LOOKS POSSIBLE
LATE FRI NIGHT INTO EARLY SAT NIGHT AS A WARM FRONT/WAA MOVES INTO
THE CWA. MODELS AGREE ON BRINGING UPPER RIDGING ACROSS THE CWA SAT
AND SUN...RESULTING IN 850MB TEMPS INCREASING TO AROUND 20C BY 00Z
MON. THINK TEMPS MAY BE TOO LOW IN THE EXTENDED /SOMEWHAT FOR
SAT...BUT MORE SO FOR SUN/...BUT UNCERTAINTY RELATING TO PRECIP/CLOUDS
MAKES IT HARD TO JUSTIFY INCREASING TEMPS SIGNIFICANTLY. THINK THAT
CONSENSUS OF GUIDANCE WILL BE FAIRLY REPRESENTATIVE FOR SAT AND SUN.
MUCH DECREASED CONFIDENCE ON MON AS MODELS HAVE DIFFICULTY HANDLING
CONVECTION POSSIBILITIES NEAR/OVER THE CWA. WILL CONTINUE TO USE
CONSENSUS OF GUIDANCE FOR MON GIVEN THE LIMITED CONFIDENCE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 122 AM EDT TUE AUG 20 2013
WITH RELATIVELY DRY LOW-LEVELS PERSISTING...VFR CONDITIONS ARE
EXPECTED THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW. AS WITH RECENT
NIGHTS...INCREASING SW WINDS TONIGHT ABOVE NOCTURNAL INVERSION WILL
APPROACH LLWS CRITERIA. DAYTIME MIXING WILL RESULT IN SW WIND GUSTS
BETWEEN 15 AND 20 KNOTS ON TUESDAY.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 405 AM EDT TUE AUG 20 2013
OVERALL...EXPECT WINDS LESS THAN 20KT THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. ONE PERIOD OF STRONGER WINDS (GUSTS TO 20-25KT)
MAY OCCUR TONIGHT AS PRES GRADIENT TIGHTENS AHEAD OF APPROACHING
COLD FRONT...BUT HI OVERWATER STABILITY WITH INFLUX OF VERY WARM
AIRMASS WILL LIMIT THE INCREASE OF WIND SPEED NEAR THE COOLER LAKE
SURFACE. THE ARRIVAL OF MORE HUMID AIR MAY RESULT IN SOME FOG
FORMATION OVER THE COOLER LAKE WATERS...BUT RESTRICTED THE FOG
FORECAST TO AREAS WHERE SOME SHOWERS OR THUNDERSTORMS ARE EXPECTED.
ANY FOG WILL DISSIPATE WED AFTN/EVENING FOLLOWING A COLD FRONTAL
PASSAGE AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TITUS
AVIATION...VOSS
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
123 AM EDT TUE AUG 20 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 422 PM EDT MON AUG 19 2013
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW ZONAL FLOW ACROSS MUCH OF
SRN CANADA. SHORTWAVE TROF THAT WAS OVER MT/SRN SASKATCHEWAN 24HRS
AGO IS NOW OVER THE UPPER LAKES THOUGH MUCH OF THE ENERGY APPEARS TO
BE SETTLING SSE INTO THE WEAKENING REMNANT OF THE TROF THAT HAS BEEN
OVER THE LOWER MISSISSIPPI VALLEY THE LAST FEW DAYS. WAVE PRODUCED A
CLUSTER OF SHRA/TSRA OVER WRN LAKE SUPERIOR THIS MORNING. THE SHRA
RAPIDLY DIMINISHED AS THEY APPROACHED WRN UPPER MI AND DISSIPATED
SOON AFTER REACHING THAT AREA. SO...FAR NO NEW SHRA/TSRA HAVE
DEVELOPED WITH DAYTIME HEATING.
LATEST SPC MESOANALYSIS SHOWS MLCAPE OF 500-1000J/KG OVER ROUGHLY
THE W HALF OF UPPER MI. VIS SATELLITE IMAGERY SHOWS CU DEVELOPING
OVER THE LAST COUPLE OF HRS...AND LATEST OBS ALONG THE SHORE
INDICATE LAKE BREEZE JUST BEGINNING TO DEVELOP OFF LAKE SUPERIOR.
PERHAPS A FEW SHRA/TSRA MAY YET DEVELOP OVER THE NEXT COUPLE OF HRS
AS LAKE BREEZE MAKES SOME INLAND PROGRESS. SINCE LATEST HIGH RES
RAPID REFRESH MODEL STILL GENERATES SOME CONVECTION OVER THE NCNTRL
LATE THIS AFTN...WILL HOLD ONTO SCHC POPS FOR THE NEXT SEVERAL HRS.
IF ANY SHRA/TSRA DO DEVELOP...THEY WILL DISSIPATE WITH LOSS OF
DAYTIME HEATING...ESPECIALLY SINCE HEIGHTS ARE IN THE PROCESS OF
STEADILY RISING AND DEEP LAYER QVECTOR DIVERGENCE IS DEVELOPING.
THERE IS SOME THETA-E ADVECTION OVERNIGHT...AND THE GEM SUGGESTS
SOME ISOLD CONVECTION LATE TONIGHT/TUE MORNING AT LEADING EDGE OF
THETA-E AXIS APPROACHING WRN UPPER MI. HOWEVER...WITH 850MB WINDS
ANTICYCLONIC AND NOT MUCH OF A LOW-LEVEL JET...POTENTIAL OF ANY
ISOLD CONVECTION LATE SEEMS VERY UNLIKELY. WILL CARRY DRY FCST THRU
THE OVERNIGHT. ALTHOUGH SKIES WILL TURN MOSTLY CLEAR...A LIGHT BUT
STEADY SW WIND AND INCREASED COLUMN MOISTURE WILL WORK TO LIMIT THE
DIURNAL TEMP FALL. UNDER S TO SW WINDS...THE HIGHEST MIN TEMPS WILL
BE IN THE DOWNSLOPE AREAS NEAR LAKE SUPERIOR OVER THE W HALF. EXPECT
MINS IN THE MID 60S THERE. INLAND...MID 50S TO AROUND 60F SHOULD BE
THE RULE.
ON TUE...PRES GRADIENT TIGHTENS A BIT BTWN SFC HIGH OVER THE MID
ATLANTIC STATES AND A LOW PRES TROF MOVING ACROSS THE NRN
PLAINS/SCNTRL CANADA. STRENGTHENING SW FLOW WILL BRING AN INCREASE
IN LOW-LEVEL DWPTS TUE...RESULTING IN A MUCH MORE UNCOMFORTABLE DAY.
MIXING TOWARD 800MB ON FCST SOUNDINGS SUGGESTS MAX TEMPS EASILY INTO
THE MID/UPPER 80S. STRONGER SW WINDS WILL PREVENT LAKE BREEZE
DEVELOPMENT OFF LAKE SUPERIOR AND SHOULD LEAD TO SOME OF THE
WARMEST READINGS IN THE DOWNSLOPE AREAS NEAR THE LAKE. EXPECT SOME
LOCATIONS TO REACH OR JUST EXCEED 90F. S/SW WINDS WILL KEEP
CONDITIONS COOLER NEAR LAKE MICHIGAN. COMBINATION OF TEMPS WELL INTO
THE 80S AND HIGHER DWPTS INTO THE 60S WILL MAKE TUE THE MOST
UNCOMFORTABLE DAY SINCE THE HOT WEATHER STRETCH IN MID JULY. NAM
SHOWS MLCAPE INCREASING TO 2000-3000J/KG TUE AFTN WHILE THE GFS IS
LOWER IN THE 1000-2000J/KG RANGE. LACK OF LAKE BREEEZE DEVELOPMENT
OFF LAKE SUPERIOR WILL BE ONE MISSING FORCING MECHANISM TO TRIGGER
CONVECTION. SINCE THERE ARE HINTS OF A SUBTLE SHORTWAVE MOVING
TOWARD THE UPPER LAKES...OPTED TO MAINTAIN SCHC POPS OVER PORTIONS
OF CNTRL UPPER MI WHERE THERE IS SOME LOW-LEVEL CONVERGENCE AS A
RESULT OF LAKE MICHIGAN LAKE BREEZE COMPONENT. IN THE ABSENCE OF ANY
SHORTWAVE...TUE WILL LIKELY END UP DRY ACROSS THE BOARD.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 422 PM EDT MON AUG 19 2013
NORTHERN STREAM UPPER TROUGH WILL SLIDE THROUGH THE AREA DURING
THE FIRST PART OF THE LONG TERM PERIOD AND LEAD TO A DECENT CHANCE
OF RAIN OVER THE AREA WEDNESDAY.
FIRST FOR TUESDAY NIGHT...THERE MAY BE SOME SHOWERS/THUNDERSTORMS
OVER LAKE SUPERIOR ON AHEAD OF THE COLD FRONT. THIS A CONTINUATION
OF THE CONVECTION THAT DEVELOPS IN SOUTHWEST ONTARIO AND NORTHEAST
MINNESOTA FROM THE AFTERNOON AND A WEAK SHORTWAVE MOVING EAST
ACROSS LAKE SUPERIOR. IN ADDITION...THIS IS ALSO THE AREA OF THE
STRENGTHENING LOW LEVEL JET AND 850-700MB THERMAL RIDGE. WITH STORM
MOTIONS TO THE EAST...WOULD THINK ISLE ROYALE AND NORTHERN LAKE
SUPERIOR WOULD HAVE THE BEST SHOT OF SEEING PRECIPITATION...BUT IT
COULD BRUSH THE KEWEENAW PENINSULA.
ON WEDNESDAY...THE MAIN SHORTWAVE WILL BE MOVING THROUGH SOUTHWEST
ONTARIO AND BE DISCONNECTED FROM THE COLD FRONT MOVING EAST ACROSS
WESTERN LAKE SUPERIOR ON WEDNESDAY MORNING. BUT...THERE ARE HINTS
THAT A SECOND WEAKER WAVE WILL BE SLIDING EAST ACROSS NORTHERN
WISCONSIN AND WESTERN UPPER MICHIGAN IN THE AFTERNOON. IF THIS
OCCURS...IT WOULD ASSIST WITH CONVECTIVE DEVELOPMENT AS THE COLD
FRONT MOVES THROUGH WESTERN/CENTRAL U.P. DURING THE DAY WEDNESDAY.
MODELS SEEM TO HAVE SPED IT UP A TOUCH WITH IT MOVING THROUGH THE
WESTERN U.P. IN THE LATE MORNING OR EARLY AFTERNOON AND THEN THE
CENTRAL U.P. IN THE MID AFTERNOON HOURS. IT THEN EXITS THE AREA
OVER LAKE MICHIGAN DURING THE EVENING. WITH THE WARM...HUMID
AIRMASS...INSTABILITY WILL BE PRETTY GOOD FOR U.P. STANDARDS (MLCAPE
VALUES OF 1500-3000 J/KG DEPENDING ON THE MODEL) WHICH ARE AIDED BY
STEEP MID LEVEL LAPSE RATES (AROUND 7-7.5C/KM FROM 850-700MB). THIS
HELPS BOOST HAIL CAPE VALUES TOWARDS 800 J/KG...BUT WITH FREEZING
LEVELS AROUND 12KFT...IT MAY COUNTERACT THE HAIL POTENTIAL. 0-6KM
AND EFFECTIVE SHEAR VALUES ARE MARGINAL FOR THUNDERSTORM
ORGANIZATION (ONLY AROUND 20-25KTS) AND FAIRLY UNIDIRECTIONAL. 09Z
SREF RUN AGREES WITH THAT BASIC IDEA AND ONLY HAS 50 PERCENT PROBS
FOR EFFECTIVE SHEAR OVER 30KTS. BUT WITH THE COLD FRONT...WOULD
EXPECT SOME CLUSTERS OR LINE OF STORMS TO FORM. STORM MOTION AND
MOVEMENT OF THE COLD FRONT WOULD SUPPORT AN EAST TO SOUTHEAST
MOVEMENT OF THE THUNDERSTORMS. FINALLY...THINK THERE WILL BE SOME
WIND THREAT DUE TO DCAPE VALUES PEAKING OVER THE SOUTH CENTRAL WHERE
THERE WILL BE LESS OF AN INFLUENCE OF CLOUDS TO AID
DESTABILIZATION. THUS...HAVE TRENDED SOME LOCATIONS UP TO
SHOWERS/THUNDERSTORMS LIKELY OVER THE CENTRAL AND WEST-CENTRAL IN
THE AFTERNOON. SPC HAS WESTERN/CENTRAL PORTIONS OF THE U.P. IN A
SLIGHT RISK AND THAT SEEMS REASONABLE AT THIS POINT ALTHOUGH THE
LIMITED SHEAR LEAVES SOME CONCERN FOR WIDESPREAD SEVERE WEATHER.
THE WARM AIR AHEAD OF THE COLD FRONT WILL PRODUCE ANOTHER WARM
DAY...ESPECIALLY OVER THE CENTRAL/EAST (HIGHS IN UPPER 80S OR
LOWER 90S). THE WEST MAY BE LIMITED BY MID CLOUDS MOVING IN AHEAD OF
THE COLD FRONT AND HAVE HIGHS IN THE 80S THERE.
AS THE UPPER TROUGH SHIFT EAST ON THURSDAY...HIGH PRESSURE WILL
BUILD OVER THE AREA WHILE AN UPPER RIDGE BUILD OVER THE NORTH
CENTRAL CONUS AND CENTRAL CANADA. WITH THIS HIGH IN PLACE...EXPECT
ANOTHER PERIOD OF DRIER WEATHER INTO THE FIRST PART OF THE WEEKEND.
A SECONDARY SHORTWAVE MOVES THROUGH ON THURSDAY...BUT WITH THE DRY
ATMOSPHERE...DON/T EXPECT MUCH MORE THAN PASSING MID CLOUDS.
TEMPERATURES DURING THE LONG TERM PERIOD WILL BE COOLEST ON
THURSDAY/FRIDAY BEHIND THE COLD FRONT (HIGHS IN THE
70S)...BUT THEN AS THE HIGH SHIFTS EAST SATURDAY...SOUTH-SOUTHWEST
LOW LEVEL FLOW WILL ALLOW TEMPERATURES TO WARM BACK ABOVE NORMAL
FOR THE WEEKEND (HIGHS AROUND 80S...ALTHOUGH THE LATEST ECMWF IS
SHOWING VALUES NEAR 90).
MODELS DIFFER SOMEWHAT FOR SATURDAY INTO MONDAY...DUE TO CONVECTION
FIRING OR NOT FIRING ALONG THE REMNANTS OF THE COLD FRONT
STRETCHING FROM SOUTHERN MINNESOTA THROUGH THE OHIO RIVER VALLEY.
THE ECMWF HAS BEEN SHOWING THIS FRONT SLOWLY PUSHING NORTH AS A
WARM FRONT THROUGH THE WEEKEND...WHICH WOULD GIVE BETTER CHANCES
FOR PRECIPITATION FOR THE END OF THE WEEKEND INTO THE BEGINNING OF
NEXT WEEK. THE GFS ON THE OTHERHAND AS BEEN SHOWING A STRONGER HIGH
LINGERING OVER THE AREA AND KEEPING THE BROAD AREA OF LOW PRESSURE
FOCUSED IN THE DAKOTAS (SIMILAR TO WHAT WE HAVE EXPERIENCED OVER
THE LAST COUPLE OF DAYS). BOTH MODELS HAVE BEEN VARYING ON THEIR
SOLUTIONS OVER THE LAST COUPLE OF DAYS...SO CONFIDENCE IS LIMITED
THIS FAR OUT. THEREFORE...WILL FOLLOW A GENERAL CONSENSUS WITH
CHANCE OR SLIGHT CHANCE POPS FOR THE WEEKEND INTO EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 122 AM EDT TUE AUG 20 2013
WITH RELATIVELY DRY LOW-LEVELS PERSISTING...VFR CONDITIONS ARE
EXPECTED THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW. AS WITH RECENT
NIGHTS...INCREASING SW WINDS TONIGHT ABOVE NOCTURNAL INVERSION WILL
APPROACH LLWS CRITERIA. DAYTIME MIXING WILL RESULT IN SW WIND GUSTS
BETWEEN 15 AND 20 KNOTS ON TUESDAY.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 422 PM EDT MON AUG 19 2013
OVERALL...EXPECT WINDS LESS THAN 20KT THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. ONE PERIOD OF STRONGER WINDS (GUSTS TO 20-25KT)
MAY OCCUR TUE NIGHT AS PRES GRADIENT TIGHTENS DUE TO APPROACHING
COLD FRONT. THE ARRIVAL OF MORE HUMID AIR TUE/WED MAY RESULT IN SOME
FOG FORMATION OVER THE COOLER LAKE WATERS. HOWEVER...FOG WILL BE
MUCH MORE LIKELY TO DEVELOP IF SOME SHOWERS OCCUR OVER THE LAKE. ANY
FOG WILL DISSIPATE WED AFTN/EVENING FOLLOWING A COLD FRONTAL PASSAGE
AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...SRF
AVIATION...VOSS
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
341 AM CDT TUE AUG 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT TUE AUG 20 2013
TODAY AND TONIGHT...850MB WINDS CONTINUE FROM THE SOUTH WITH A
SLIGHT SOUTHWEST COMPONENT. SPEEDS INCREASE TO AROUND 25 KTS
SUPPORTING 15 TO 25 MPH SFC WIND SPEEDS. A DRYLINE BULGE SHOULD
DEVELOP ACROSS WRN NEB AND THE SANDHILLS SUPPORTING DEEPER
MIXING. SOME OF GUIDANCE SUGGESTS LOW 100S FOR HIGHS. THE PROBLEM
AREA IS NRN NEB AND VALENTINE WHERE HOT DRY AIR WILL BLOW NORTH
OFF THE SANDHILLS. IF THE SANDHILLS ARE DRY THEN THIS AREA WILL
RISE ABOVE 100.
FOR NOW TEMPS ARE A BLEND OF TRIED AND TRUE GUIDANCE FOR HIGHS IN
THE 90S TO 100. WITH H700MB TEMPS RISING TOWARD 16C THIS AFTN
ACROSS WRN NEB THERE COULD BE SOME LOW 100S BUT WE WOULD LIKE TO
SEE A MORE SWRLY COMPONENT TO THE 850 MB WINDS AND 700MB WINDS
DUE WEST VS THE RAP FCSTING SOUTHWEST WINDS AT 700MB.
ISOLATED TSTMS ARE POSSIBLE THIS AFTN ACROSS NWRN NEB AS A COLD
FRONT DROPS IN. A SLIGHT COOLING ALOFT TONIGHT MIGHT ALLOW A FEW
STORMS TO FORM FARTHER EAST ACROSS NRN NEB. OTHERWISE THE HEAT
CONTINUES TODAY WITH DEW POINTS IN THE UPPER 60S EAST OF HIGHWAY
83. THE DRYLINE BULGE SHOULD REACH TO HIGHWAY 83 THIS AFTN AND
THEN RETREAT WEST THIS EVENING.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 341 AM CDT TUE AUG 20 2013
SUMMER LIKE WEATHER THROUGH MUCH OF THE MID TO LONG RANGE
FORECAST. UPPER LEVEL RIDGE WILL CONTINUE TO MIGRATE EAST AND
BECOME CENTERED OVER THE PLAINS BY THE WEEKEND. MODELS IN GOOD
AGREEMENT WITH THE 500 MB HEIGHT OF THE HIGH REACHING 1594M TO
1595M.
AT THE SFC A COLD FRONT WILL PUSH ACROSS THE AREA WED...WHICH
SHOULD BE THE FOCUS FOR ISOLD THUNDERSTORMS BY EARLY AFTERNOON AS
CAP WEAKENS. INITIALLY MOISTURE IS LIMIT IN THE COLUMN...WITH
PRECIP H2O AROUND AN INCH...NEAR THE 50 PERCENTILE FOR
AUGUST...HOWEVER AN INCREASE THROUGHOUT THE DAY...POOLING ALONG
THE BOUNDARY...IS EXPECTED. THE DEW PTS ARE EXPECTED IN THE MID
AND UPPER 60S FOR THE AFTERNOON...AND SHOULD BE ENOUGH TO HELP
BREAK THE CAP. SOUNDINGS SUGGEST HIGH BASED STORMS NEAR 8K TO 10K
FEET. DIRECTIONAL SHEAR IS DECENT...HOWEVER LIMITED SPEED SHEAR.
A FEW STRONG STORMS CAN NOT BE RULED OUT...AND WILL BE MONITORED.
WEAK SECONDARY BOUNDARY AND UPPER LEVEL WAVE WILL PUSH INTO THE
NW WED EVENING AND ACROSS NRN NEB THURSDAY. SLIGHT CHANCE POPS
WARRANTED AT THIS TIME...ALTHOUGH CONVECTION ALONG THE COLD FRONT
MAY CAUSE THIS DISTURBANCE TO DIMINISH IN EFFECT. LINGERING
CLOUDS AND SLIGHTLY COOLER AIR BEHIND THE COLD FRONT WILL HOLD
TEMPS IN THE 80S FOR MOST AREAS THURS.
BY FRIDAY THE RIDGE WILL BEGIN TO END THE MAIN THREAT FOR STORMS.
A LEESIDE TROUGH DEVELOPS WHILE A LARGE SFC HIGH EXPENDS ACROSS
THE GREAT LAKES. ACTIVITY IS LIKELY ALONG THE HIGHER TERRAIN/SFC
TROUGH TO THE WEST AND MAY IMPACT THE FAR WESTERN ZONES DUE TO
WESTERLY WINDS. HAVE INCLUDED A SLIGHT CHANCE FOR THE EASTERN
PANHANDLE LATE SATURDAY AS A STRONGER UPPER LEVEL WAVE CROSSES
THE NORTHERN/CENTRAL ROCKIES...OTHERWISE DRY. WITH THE INFLUENCE
OF THE RIDGE...HIGHS WARM BACK INTO THE LOWER TO MID 90S...WELL
ABOVE NORMAL FOR THE LAST HALF OF AUGUST.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 101 AM CDT TUE AUG 20 2013
STATISTICAL OUTPUT FROM ONE MODEL INDICATES SOME RISK OF
VISIBILITY BELOW 5SM IN THE PLATTE RIVER VALLEY AROUND LBF. THE
INDICATED PROBABILITY OF THAT VISIBILITY RANGE IS ABOUT 50
PERCENT. THE OTHER STATISTICAL BULLETIN DOES NOT INDICATE ANY
RESTRICTION. THEREFORE...UNLESS THERE IS A STRONGER SIGNAL LATER
IN SATELLITE IMAGERY OR IN THE SURFACE OBSERVATIONS...WE WILL NOT
INCLUDE THE RESTRICTION IN THE TERMINAL FORECAST FOR LBF.
OTHERWISE...NO RESTRICTIVE CEILING OR VISIBILITY IS EXPECTED IN
CENTRAL AND WESTERN NEBRASKA TONIGHT THROUGH TUESDAY. BY ABOUT
16Z TUESDAY...SOUTH WIND 170-200 WILL INCREASE TO 8-12G16-22KT
AND DECREASE AGAIN 00-02Z.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...MASEK
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1141 PM CDT MON AUG 19 2013
.UPDATE...
ISSUED AT 940 PM CDT MON AUG 19 2013
THE MAIN ISSUE OVERNIGHT WILL BE POSSIBLE FOG FORMATION. CLEAR SKY
AND HIGH LOW LEVEL MOISTURE WILL BE PRESENT...BUT THERE MAY BE
ENOUGH LOW LEVEL MIXING TO PREVENT FOG. 01Z RAP INDICATES A 30-40
KNOT LOW LEVEL JET FROM SOUTH CENTRAL NORTH DAKOTA INTO NORTHWEST
MINNESOTA. ALTHOUGH MIXING WILL NOT BE VERY DEEP DUE TO
NIGHTTIME...THERE SHOULD BE ENOUGH MIXING TO PREVENT CALM WINDS AT
THE SURFACE FOR THIS AREA. FURTHER TO THE SOUTHEAST...AWAY FROM
THE STRONGER 925MB-850MB WINDS...MODELS INDICATE VERY LIGHT FLOW.
AT LEAST PATCHY FOG SHOULD OCCUR HERE...AND INSERTED WITHIN
PORTIONS OF WEST CENTRAL MINNESOTA. THE MAIN AREAS TO WATCH WILL
BE AROUND LAKES AND THE BEMIDJI AREA (WHERE 1 TO 3 INCHES OF RAIN
FELL THIS AFTERNOON). OTHERWISE...MIN TEMPS AND OTHER PARAMETERS
ARE IN GOOD SHAPE.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 340 PM CDT MON AUG 19 2013
PRIMARY CHALLENGES ARE TEMPERATURES THROUGH THE PERIOD AND
PRECIPITATION CHANCES TUESDAY NIGHT. MODELS ARE IN REASONABLE
AGREEMENT AND WILL USE A BLENDED SOLUTION.
A NEARLY STATIONARY ISOLATED CLUSTER OF SHOWERS AND ISOLATED
THUNDERSTORMS HAS DEVELOPED ACROSS SOUTHERN BELTRAMI COUNTY THIS
AFTERNOON...POSSIBLY DUE TO SOME KIND OF LAKE BREEZE INTERACTIONS...
SO ADDED SOME CHANCE POPS IN THIS AREA UNTIL 02 UTC. REST OF THE
FORECAST AREA IS HOT AND DRY WITH LITTLE CLOUD COVER. WHAT LITTLE
CU HAS DEVELOPED WILL DISSIPATE AFTER SUNSET WITH CLEAR SKIES
OVERNIGHT. WITH A WARM AIR MASS AND ELEVATED SOUTHERLY WIND...LOWS
WILL DROP INTO THE MID TO UPPER 60S.
IT/S SAFE TO SAY TUESDAY WILL BE THE HOTTEST DAY SO FAR OF THE
YEAR. AN 850 HPA +28 C THERMAL RIDGE WILL MOVE ACROSS THE FORECAST
AREA AHEAD OF AN ADVANCING COLD FRONT. WITH A DRY ADIABATIC
BOUNDARY LAYER DEEPENING TO 700 TO 600 HPA...IT WILL NOT BE
DIFFICULT FOR MUCH OF THIS HEAT TO MIX TO THE SURFACE. EXPECT
AFTERNOON HIGHS REGION WIDE IN THE LOWER TO MID 90S. ONLY
EXCEPTION MAY BE THE FAR NORTHWEST FORECAST AREA WHICH WILL BE
UNDER THE INFLUENCE OF THE COLD FRONTAL PASSAGE A BIT EARLIER IN
THE DAY. WITH DEW POINT TEMPERATURES ALONG AND AHEAD OF THE FRONT
IN THE 60S...HEAT INDICIES NEARING 100 DEGREES NOT OUT OF THE
QUESTION. WILL HOLD ON A HEAT ADVISORY...BUT SOMETHING TO CONSIDER
IN LATER SHIFTS.
WILL HOLD 20 POPS TUESDAY EVENING AND OVERNIGHT FOR THE CHANCE FOR
SOME CONVECTIVE DEVELOPMENT ALONG AND AHEAD OF THE COLD FRONT.
MLCAPE UP TO 2000 J/KG IS POSSIBLE...BUT 0 TO 6 KM BULK SHEAR IS
RATHER WEAK WITH THE PRIMARY UPPER JET NORTH OF THE CANADIAN
BORDER. VERY WARM MID-LEVEL TEMPERATURES WILL PLAY HAVOC WITH
EROSION OF THE CAP AND DEEP LAYERED MOISTURE IS MISSING. MAIN
INGREDIENTS FOR CONVECTION JUST DON/T SEEM TO ALIGN...SO WHILE
THERE EXISTS SOME CHANCE FOR SHOWERS AND THUNDERSTORMS...
CONFIDENCE IS LOW.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 340 PM CDT MON AUG 19 2013
WEDNESDAY AND THURSDAY WILL BE DRY AS SURFACE HIGH PRESSURE BUILDS
ACROSS THE REGION...BUT COOLER IN THE WAKE OF TUESDAY NIGHT/S FRONTAL
PASSAGE. DAYTIME HIGHS WILL BE IN THE 80S WITH LIGHT WINDS.
OVERNIGHT LOWS WILL RANGE FROM THE MID 50S TO THE MID 60S.
FOR FRIDAY INTO EARLY NEXT WEEK AREA IS ON THE NORTHERN EDGE OF AN
UPPER RIDGE. SEVERAL SHORT WAVES ARE FORECAST TO RIDE FROM THE
PACIFIC COAST 500 MB TROUGH NORTH AND NORTHEAST THRU WYOMING AND
THEN ACROSS NORTH DAKOTA-MINNESOTA THRU THE PERIOD. ANY SHORT WAVE
MAY CAUSE DEVELOPMENT OF ISOLD-SCT TSRA AT ANYTIME THRU THIS PD...SO
WILL GO ALONG WITH CENTRAL REGION ALL BLEND TOOL AND KEEP LOW POPS
IN MOST DAYS FRI-MON. STILL WARM AND HUMID WITH HIGHS IN THE 80S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1141 PM CDT MON AUG 19 2013
THE POTENTIAL EXISTS FOR FOG AT KBJI. THE AIRPORT RECEIVED VERY
LITTLE RAINFALL THIS PAST AFTERNOON...BUT AREAS JUST TO THE EAST
RECEIVED 1 TO 3 INCHES. WIND SPEEDS ALONG AND WEST OF THE VALLEY
WILL BE 5-10 KNOTS OVERNIGHT...BUT LIGHT AND VARIABLE AT KBJI.
CONFIDENCE HAS INCREASED IN FOG FORMATION...AND MENTIONED IN THE
KBJI TAF. OTHERWISE...MOSTLY CLEAR SKY THROUGH THE PERIOD WITH
ONLY WIDELY SCATTERED THUNDERSTORMS TUESDAY EVENING.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...TG
SHORT TERM...ROGERS
LONG TERM...RIDDLE
AVIATION...TG
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
351 AM CDT TUE AUG 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 351 AM CDT TUE AUG 20 2013
MAIN FORECAST CONCERNS ARE ON THUNDERSTORM CHANCES WEDNESDAY INTO
THURSDAY AND HIGH TEMPERATURES LATE IN THE WEEKEND INTO EARLY NEXT
WEEK.
LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED A
SHORTWAVE TROUGH OVER SOUTHERN WISCONSIN AND NORTHERN
ILLINOIS...DRIFTING SOUTH. RIDGING WAS MOVING INTO THE UPPER
MISSISSIPPI RIVER VALLEY PROVIDING MOSTLY CLEAR TO PARTLY CLOUDY
SKIES AND QUIET CONDITIONS OVER THE AREA. SURFACE OBSERVATIONS
SHOWED A COLD FRONT EXTENDING FROM SOUTHERN MANITOBA THROUGH
WESTERN NORTH DAKOTA INTO EASTERN WYOMING WITH A BROAD HIGH
CENTERED OVER THE OHIO RIVER VALLEY. THE FORECAST AREA IS LOCATED
BETWEEN THESE TWO FEATURES WITH WARM SOUTHERLY FLOW ACROSS THE
REGION.
THE SHORTWAVE TROUGH WILL CLOSE INTO A WEAK UPPER LOW OVER ILLINOIS
TODAY. MEANWHILE...THE COLD FRONT WILL DRIFT SOUTHEAST AND BY LATE
THIS AFTERNOON IS EXPECTED TO STRETCH FROM NORTHWEST MINNESOTA
THROUGH EASTERN NORTH DAKOTA INTO CENTRAL SOUTH DAKOTA. THE UPPER
LEVEL RIDGING SHOULD WIN OUT TODAY PROVIDING PARTLY TO MOSTLY
SUNNY SKIES. INTERESTING TO NOTE THAT AFTERNOON MLCAPE VALUES
CLIMB TO 2500 TO 3500 J/KG THIS AFTERNOON ACROSS MUCH OF THE
FORECAST AREA. WITHOUT ANY REAL TRIGGER TO GET CONVECTION TO FIRE
THINKING THE AREA SHOULD REMAIN DRY THROUGH THE DAY. WILL HAVE TO
KEEP A CLOSE EYE ON THE POTENTIAL FOR AN ISOLATED SHOWER OR STORM
UNDER PEAK HEATING LATE THIS AFTERNOON. PLAN ON HIGH TEMPERATURES
CLIMBING INTO THE UPPER 80S TO AROUND 90. THE COLD FRONT WILL
CONTINUE ITS SOUTHEAST MOVEMENT TONIGHT INTO WEDNESDAY MORNING.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 351 AM CDT TUE AUG 20 2013
THE COLD FRONT WILL BE POSITIONED FROM FAR NORTHWEST WISCONSIN INTO
EXTREME NORTHWEST IOWA EARLY WEDNESDAY MORNING. FORECAST MODELS ARE
SHOWING SOME DIFFERENCES ON WHEN THE FRONT WILL MOVE INTO THE
FORECAST AREA. THE NAM OFFERS THE FASTEST SOLUTION BRINGING THE
FRONT INTO THE FORECAST AREA LATE WEDNESDAY MORNING...SHIFTING
SOUTH OF THE INTERSTATE 90 CORRIDOR WEDNESDAY EVENING AND STALLING
OVER NORTHERN IOWA/ILLINOIS. THE ECMWF HAS THE SLOWEST SOLUTION
AND DOESN/T BRING THE FRONT INTO THE FORECAST AREA UNTIL WEDNESDAY
EVENING. THE ECMWF SOLUTION SUGGESTS THAT A SHORTWAVE WILL TRIGGER
SHOWERS AND STORMS OVER NORTHWEST WISCONSIN WEDNESDAY
AFTERNOON...SPREADING SOUTHEAST DURING THE LATE AFTERNOON AND
EVENING HOURS. SHOWERS AND STORMS THEN FIRE ALONG THE FRONT
THROUGH THE OVERNIGHT HOURS WITH THE FRONT FINALLY PUSHING SOUTH
OF THE AREA BY EARLY THURSDAY AFTERNOON. THERE REMAINS TIMING
ISSUES TO WORK OUT...BUT THINKING THERE REMAINS A CHANCE OF SEEING
SEVERE THUNDERSTORMS ON WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT.
0-6KM BULK SHEAR IS THE MOST FAVORABLE FOR SEVERE STORMS OVER
NORTH CENTRAL WISCONSIN...WHERE VALUES RANGE FROM 30 TO 40 KTS.
PLENTY OF INSTABILITY TO WORK WITH AHEAD OF THE FRONT WITH MLCAPE
VALUES CLIMBING TO AROUND 2000 J/KG. THE MAIN THREATS FROM THE
STORMS WILL BE LARGE HAIL AND DAMAGING WINDS. SHEAR IS VERY
MARGINAL AT BEST OVER SOUTHEAST MINNESOTA...NORTHEAST IOWA...AND
SOUTHWEST WISCONSIN...BUT THINKING THE STRONG INSTABILITY WILL BE
ENOUGH TO OVERCOME THE LACK OF STRONG SHEAR. THE FRONT FINALLY
SHIFTS SOUTH OF THE AREA LATE ON THURSDAY AS HIGH PRESSURE BUILDS
IN. THE FRONT ATTEMPTS TO LIFT NORTH AS A WARM FRONT ON FRIDAY
GENERATING SOME SHOWERS AND STORMS ALONG IT. LATEST GUIDANCE
SUGGESTS THAT THE FRONT WASHES OUT AS A SURFACE HIGH HOLDS STRONG
OVER THE WESTERN GREAT LAKES. UPPER RIDGE THEN BUILDS OVER THE
REGION SATURDAY INTO SUNDAY WITH WARMING TEMPERATURES EXPECTED.
WILL HAVE TO KEEP A CLOSE EYE ON SHORTWAVES ROTATING THROUGH THE
NORTHERN PERIPHERY OF THE RIDGE OVER NORTHERN WISCONSIN WHERE
SHOWERS STORMS WILL BE POSSIBLE. 850 MB STANDARDIZED ANOMALIES
CLIMB TO PLUS 2 ON SUNDAY...SUGGESTING THE POTENTIAL FOR NEAR
RECORD HIGH TEMPERATURES. 925 MB TEMPERATURES WARM TO 28 C ON
SUNDAY BEFORE ANOTHER COLD FRONT SLIPS SOUTH THROUGH THE REGION ON
MONDAY. HIGHS ON SUNDAY AND MONDAY SHOULD CLIMB INTO THE UPPER 80S
TO LOWER 90S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1148 PM CDT MON AUG 19 2013
TRANQUIL...ZONAL FLOW WILL KEEP THINGS RELATIVELY QUIET A COUPLE
MORE DAYS. PASSING...WEAK SHORT WAVE TROUGH HAS LEFT SOME RESIDUAL
MOISTURE IN LOW TO MID LEVELS CREATING SHORT LIVED VFR CEILINGS THIS
EVENING BUT THOSE SHOULD DISSIPATE OVERNIGHT.
SMOKE IN AIRMASS SWEEPING IN FROM WESTERN FOREST FIRES COULD DROP
VISIBILITIES INTO 5-6SM AT TIMES EARLY TUESDAY...OTHERWISE VFR. MORE
DIURNAL CUMULUS POSSIBLE AS WELL WITH STEADY SOUTH TO SOUTHWEST LOW
LEVEL FLOW INTO MID WEEK.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...SHEA
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1148 PM CDT MON AUG 19 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 249 PM CDT MON AUG 19 2013
MAIN FORECAST CONCERNS ARE ON ANY POTENTIAL PRECIPITATION TONIGHT
AND THEN TEMPERATURES FOR TUESDAY.
CURRENTLY AS OF 19Z...
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING
ALONG THE WEST COAST OF BRITISH COLUMBIA...UPPER RIDGING FROM THE
SOUTHWESTERN U.S. INTO THE DAKOTAS...AND A SHORTWAVE TROUGH OVER
CENTRAL MN. THE MAIN IMPACT TO THE FORECAST AREA WITH THE SHORTWAVE
TROUGH HAS BEEN TO SPREAD SOME MID AND HIGH CLOUDS ACROSS. DRY AIR
IN THE MID LEVELS OF THE ATMOSPHERE SEEN ON THE 12Z MPX SOUNDING...
AS WELL AS A CAPPING INVERSION AT 750MB ON THAT SOUNDING...HAS
PREVENTED THE SHORTWAVE FROM PRODUCING PRECIPITATION IN THE FORECAST
AREA. THE CLOUD COVER HAS ALSO HELD BACK TEMPERATURES FROM REACHING
THEIR MAXIMUM POTENTIAL. 16C 850MB TEMP ON THE MPX SOUNDING WAS
ADVECTING EAST INTO THE FORECAST AREA...WHICH NORMALLY WOULD SUPPORT
MID TO EVEN UPPER 80S WITH CLEAR SKIES. HOWEVER...THE CLOUDS HAVE
HELD TEMPS DOWN INTO THE UPPER 70S TO LOW 80S THUS FAR. LOW LEVEL
SOUTHERLY FLOW HAS SLOWLY BEEN BRINGING IN MORE MOISTURE WITH
DEWPOINTS IN THE UPPER 50S TO LOW 60S. TO THE NORTHWEST...A COLD
FRONT STRETCHED FROM CENTRAL MANITOBA INTO WESTERN MONTANA. AHEAD OF
THE FRONT...12Z RAOBS SHOWED EVEN WARMER AIR ACROSS THE NORTHERN
PLAINS...WITH 850MB READINGS OF 20-25C AT BIS...ABR...UNR AND GGW.
700MB TEMPS WERE WARMING AS WELL...BETWEEN 8-13C.
SYNOPTIC OVERVIEW...
THE SHORTWAVE TROUGH OVER CENTRAL MN IS PROGGED TO DROP SOUTH
THROUGH THE FORECAST AREA THIS EVENING...WITH THE EXTENSION OF THE
UPPER RIDGE OVER THE DAKOTAS FOLLOWING IN BEHIND IT FOR THE
OVERNIGHT HOURS INTO TUESDAY.
DETAILS...
GIVEN THE DRY AIRMASS IN PLACE SUB THE MID-CLOUD LAYER AS WELL AS
THE CAPPING...NOT ANTICIPATING ANY PRECIPITATION TO ACCOMPANY THE
SHORTWAVE AS IT DROPS THROUGH THE FORECAST AREA THIS EVENING. WE
SHOULD SEE SOME CLEARING AS WELL...BOTH OF THE MID/HIGH CLOUDS AND
DIURNAL CUMULUS...AS SUBSIDENCE WORKS IN BEHIND THE SHORTWAVE
TROUGH. 850MB MOISTURE TRANSPORT THEN KICKS IN...TRANSPORTING MORE
LOW LEVEL MOISTURE INTO THE AREA. THE 19.12Z NAM/REGIONAL CANADIAN
BOTH DEVELOP A FEW ACCAS TYPE SHOWERS AND THUNDERSTORMS ON THE EDGE
OF THIS MOISTURE TRANSPORT FROM SOUTHEAST MN INTO NORTHWEST WI.
THESE ARE REALLY THE ONLY MODELS SHOWING THIS...AND WITH A BROAD
850MB MOISTURE TRANSPORT PLUME PROGGED COMBINED WITH SUBSIDENCE...
THINK THEY ARE OVERDONE AND KEPT A DRY FORECAST GOING. WORTH KEEPING
AN EYE ON...THOUGH.
THE MORE MOISTURE COMING IN COMBINED WITH DAYTIME HEATING SHOULD
YIELD TO PLENTY OF CUMULUS ON TUESDAY. LITTLE IN THE WAY OF CAPPING
IS PROGGED TOMORROW WITH MLCIN VALUES DROPPING TO 30-40 J/KG IN THE
AFTERNOON...WHILE MLCAPES GROW TO 1500-2500 J/KG. HOWEVER...THERE IS
NO TRIGGER PRESENT TO ALLOW THE RELEASE OF THE INSTABILITY.
THEREFORE...DRY CONDITIONS ARE FORECAST THROUGH TUESDAY.
TEMPERATURES TONIGHT EXPECTED TO BE WARMER...ESPECIALLY OVER THE
NORTHWEST HALF OF THE FORECAST AREA...DUE TO A SOUTHERLY BREEZE AND
HIGHER DEWPOINTS. THE SOUTHERLY BREEZE SHOULD PRECLUDE VALLEY
FOG PRETTY MUCH EVERYWHERE EXCEPT FOR THE WISCONSIN RIVER VALLEY.
850MB AND 925MB TEMPS ARE PROGGED ABOUT 2-3C HIGHER ON TUESDAY
AFTERNOON COMPARED TO THIS AFTERNOON. THESE WARMER TEMPS COMBINED
WITH MORE SUN WILL LEAD TO WARMER CONDITIONS...LIKELY BY 5 OR SO
DEGREES.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 249 PM CDT MON AUG 19 2013
HAZARDS...
HEAT INDICES MAY GET CLOSE TO ADVISORY CRITERIA ON WEDNESDAY AND
AGAIN SUNDAY AND MONDAY. ALSO MONITORING POTENTIAL SEVERE WEATHER
FOR LATE WEDNESDAY.
SYNOPTIC OVERVIEW...
TROUGHING ALONG THE WEST COAST OF BRITISH COLUMBIA IS FORECAST
CONCERN NUMBER 1...WITH MODELS STRUGGLING A BIT ON THE AMPLITUDE OF
THE TROUGH AS IT CROSSES SOUTHERN CANADA THE NEXT COUPLE OF DAYS.
SOME PAST GFS RUNS INDICATED THE TROUGH COULD DIP INTO NORTHERN
MINNESOTA LATE WEDNESDAY...WHEREAS THE ECMWF AS WELL AS THE 19.12Z
GFS KEEP IT TO THE NORTH CROSSING NORTHERN ONTARIO. THIS IS
IMPORTANT AS IT IMPACTS HOW FAR SOUTH DYNAMICAL FORCING WILL REACH
INTO THE FORECAST AREA. ADDITIONALLY...THIS SHORTWAVE TROUGH IS
GOING TO DICTATE THE SPEED OF THE COLD FRONT OVER MONTANA...THE
FORCING ON THE FRONT...AND HOW FAR SOUTH THE FRONT GETS HEADING INTO
THURSDAY AND THURSDAY NIGHT. GOOD MODEL AGREEMENT PERSISTS HEADING
INTO NEXT WEEKEND AS THE SUMMER HEAT RIDGE BUILDS AND STRENGTHENS
OVER THE NATIONS HEARTLAND. VERY LITTLE MOVEMENT OF THIS RIDGE IS
SUGGESTED BY MONDAY.
TUESDAY NIGHT THROUGH THURSDAY...
FOCUS IS ON THE COLD FRONT APPROACHING THE AREA. ALL MODELS ARE
SHOWING AN ELEVATED MIX LAYER...I.E. THE WARMER 850MB AND 700MB AIR
PRESENT CURRENTLY OVER THE NORTHERN PLAINS...ADVECTING INTO THE
FORECAST AREA TUESDAY NIGHT AND WEDNESDAY AHEAD OF THE FRONT. THE
EXACT WARMTH IS ONE FACTOR THAT WILL PLAY INTO WHETHER OR NOT THIS
FRONT CAN INITIATE CONVECTION WEDNESDAY AFTERNOON. ANOTHER FACTOR IS
MOISTURE...WHICH THE 19.12Z GFS AND NAM BOTH APPEAR TO BE OVERDOING
THE SURFACE DEWPOINTS. THEY PROG VALUES IN THE 70-75 RANGE WHILE
MIXING AND THE DRYING SOILS SHOULD RESULT IN READINGS MORE IN THE
MID/UPPER 60S. THESE MIXED LAYER DEWPOINTS RESULT IN MLCIN VALUES OF
30-50 J/KG. A THIRD FACTOR OF CONCERN IS LOW LEVEL CONVERGENCE...
WHICH THE NAM AND GFS BOTH PROG WEAK TO NOTHING PRIOR TO THEIR
CONVECTIVE SCHEMES GOING OFF. THUS...THERE IS PLENTY OF UNCERTAINTY
ON THE EXTENT OF POTENTIAL CONVECTION. IN REALITY...THERE IS A
BETTER SHOT FOR CONVECTION ONCE THE FRONT PASSES...DUE TO THE
DEVELOPMENT OF A POST-FRONTAL LOW TO MID LEVEL FRONTOGENESIS ZONE.
HAVE TAILORED PRECIPITATION CHANCES IN THIS WAY WITH HIGHER VALUES
WEDNESDAY NIGHT. PRECIPITATION CHANCES CONTINUE INTO THURSDAY...
MAINLY SOUTH OF I-90...WHERE THE FRONTOGENESIS ZONE MAY STILL BE
LINGERING. THIS IS ALL DEPENDS ON HOW FAR SOUTH THE FRONT MAKES
IT...THOUGH.
FOR SEVERE WEATHER POTENTIAL...THE 0-6KM SHEAR IS SERIOUSLY LAGGING
THE FRONT. 25 KT IS ABOUT THE HIGHEST AT 00Z AND THATS UP NEAR EAU
CLAIRE. 0-3 KM IS NOT MUCH BETTER WITH SIMILAR VALUES. THUS THINKING
THAT IF THERE IS A SEVERE RISK...MORE LIKELY IT IS UP NORTH OF HWY
10 DURING THE LATE AFTERNOON/EVENING HOURS.
ON THE TEMPERATURE SIDE OF THINGS...925MB READINGS FROM THE
ECMWF/GFS ARE PROGGED TO CLIMB TO 24-26C LATE WEDNESDAY. WITH PLENTY
OF SUN MUCH OF THE DAY AND A SOUTHWEST BREEZE...HIGHS SHOULD TOP OUT
BETWEEN THE UPPER 80S AND MID 90S. DEWPOINTS MIXING DOWN INTO THE
MID TO UPPER 60S WILL HELP TO HOLD HEAT INDICES BELOW ADVISORY
CRITERIA. 925MB TEMPS COOLING TO 20-22C FOR THURSDAY LIKELY TO DROP
TEMPS 5-10 DEGREES FROM WEDNESDAY.
THURSDAY NIGHT THROUGH MONDAY...
INITIAL FOCUS FOR THIS TIME PERIOD IS THE RETURN BACK NORTH OF THE
COLD FRONT...I.E. SWITCHING TO A WARM FRONT...AND IF ANY CONVECTION
CAN FIRE ON THAT. THE 19.00Z ECMWF IS THE MOST BULLISH ON FIRING
CONVECTION FOR THURSDAY NIGHT AND FRIDAY AS THE FRONT LIFTS THROUGH
THE FORECAST AREA. 19.12Z GFS/CANADIAN ARE BOTH DRY.
NEXT CONCERN TURNS TO THE HEAT FOR THE WEEKEND INTO MONDAY AS THE
STRONG SUBTROPICAL RIDGE FORMS OVER NEBRASKA...IOWA...KANSAS AND
MISSOURI. THE BULK OF THE HEAT WITH 850MB TEMPS OF 24C OR HIGHER
LOOKS TO STAY WELL OFF TO THE WEST OVER THE DAKOTAS INTO WESTERN
PORTIONS OF NEBRASKA AND KANSAS. HOWEVER...THEY SHOULD STILL TOP OUT
IN THE 18-22C RANGE FOR SATURDAY THROUGH MONDAY...WITH THE HIGHER
READINGS OF 20-22C LIKELY OCCURRING SUNDAY AND MONDAY. THESE ARE
1.5-2 STANDARD DEVIATIONS ABOVE NORMAL...WHICH WOULD IMPLY CLOSE TO
BUT NOT REACHING OR EXCEEDING RECORD HIGHS. LOW TEMPERATURES COULD
TURN OUT QUITE WARM AS WELL WITH A PERSISTENT SOUTH TO SOUTHWEST
BREEZE. INDICATIONS FROM THE 19.12Z ECMWF THAT THE WELL ABOVE NORMAL
TEMPERATURES COULD STICK AROUND WELL BEYOND MONDAY.
PRECIPITATION CHANCES FOR THE WEEKEND INTO EARLY NEXT WEEK SHOULD
STAY CONFINED MOSTLY NORTH OF THE FORECAST AREA...WHERE THE WARM
FRONT FROM THURSDAY NIGHT/FRIDAY WILL BE LOCATED. THERE ARE
POSSIBILITIES THAT THE FRONT COULD SLIP BACK SOUTH INTO NORTHERN
SECTIONS OF THE FORECAST AREA AT TIMES SUNDAY NIGHT AND
MONDAY...THUS HAVE SOME CHANCES IN FOR THIS PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1148 PM CDT MON AUG 19 2013
TRANQUIL...ZONAL FLOW WILL KEEP THINGS RELATIVELY QUIET A COUPLE
MORE DAYS. PASSING...WEAK SHORT WAVE TROUGH HAS LEFT SOME RESIDUAL
MOISTURE IN LOW TO MID LEVELS CREATING SHORT LIVED VFR CEILINGS THIS
EVENING BUT THOSE SHOULD DISSIPATE OVERNIGHT.
SMOKE IN AIRMASS SWEEPING IN FROM WESTERN FOREST FIRES COULD DROP
VISIBILITIES INTO 5-6SM AT TIMES EARLY TUESDAY...OTHERWISE VFR. MORE
DIURNAL CUMULUS POSSIBLE AS WELL WITH STEADY SOUTH TO SOUTHWEST LOW
LEVEL FLOW INTO MID WEEK.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...SHEA
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1051 AM CDT TUE AUG 20 2013
.DISCUSSION...
347 AM CDT
NEAR TERM FORECAST CONCERNS FOCUS ON CONTINUED SLOW WARMING TREND IN
TEMPERATURES TODAY AND WEDNESDAY. COLD FRONT SAGGING INTO THE AREA
EARLY THURSDAY...AND ASSOCIATED POTENTIAL FOR SHOWERS/THUNDERSTORMS
ALONG AND AHEAD OF THIS FRONT WEDNESDAY NIGHT INTO THURSDAY BECOME
THE MAIN FOCUS IN THE MID-WEEK PERIOD. LONGER TERM...EXPECT A BIT OF
A COOL DOWN BEHIND THE FRONT FRIDAY AND SATURDAY...THEN THE
POTENTIAL FOR A LATE-AUGUST HEAT WAVE BY EARLY NEXT WEEK AS UPPER
RIDGE BUILDS OVER THE REGION.
EARLY MORNING SURFACE ANALYSIS DEPICTS HIGH PRESSURE ALONG/OFF THE
MID-ATLANTIC COAST REGION...WITH WEAKER RIDGING EXTENDING BACK TO
THE WEST ACROSS THE MIDWEST. LIGHT SOUTHERLY FLOW HAD DEVELOPED WEST
OF THE RIDGE...WITH THE WFO LOT CWA GENERALLY ON THE EASTERN
PERIPHERY OF THIS RETURN FLOW ACROSS THE CENTRAL CONUS. ALOFT...IR
SATELLITE LOOP SHOWS A SLOW MOVING MID-UPPER LEVEL CIRCULATION OVER
ILLINOIS...PRODUCING A PATCHY HIGH CIRRUS DECK ACROSS THE AREA. THIS
CIRCULATION WILL CONTINUE TO DRIFT SOUTHEAST ACROSS DOWNSTATE IL AND
EVENTUALLY SOUTHERN INDIANA THROUGH TONIGHT...WITH RELATIVELY DRY
LOW/MID LEVELS IN DVN/ILX 00Z SOUNDINGS SUGGESTING MAINLY JUST SOME
ADDITIONAL PATCHY HIGH CLOUDS WITH THIS FEATURE. AREA OF WARM/MOIST
LOW LEVEL ADVECTION WITH ANOTHER SHORT WAVE OVER WESTERN MINNESOTA
AND IOWA WAS PRODUCING SOME LOWER CLOUDS THIS MORNING...BUT
ORIENTATION OF MOISTURE TRANSPORT SHOULD FOCUS THESE LOWER CLOUDS
FROM IA/MN INTO WI THROUGH TODAY. THUS...PARTLY CLOUDY CONDITIONS
TODAY SHOULD ALLOW CONTINUED WARMING OF TEMPS FROM THE PAST SEVERAL
DAYS. SOUTHWEST FLOW IN LOW LEVELS INCREASES INTO WEDNESDAY AS
STRONGER SHORT WAVE MOVES ALONG THE U.S./CANADIAN BORDER...
MAINTAINING WARM ADVECTION ACROSS THE CWA. VARIOUS MODEL THERMAL
FIELDS AND 925-850MB LOCAL CLIMATOLOGY SUPPORT TEMPS REACHING UPPER
80S IN MOST LOCATIONS TODAY...WITH A FEW MID 80S IN THE FAR
SOUTHEAST. HIGHS WEDNESDAY EXPECTED FROM AROUND 90 IN WARMER
NORTHERN IL SPOTS INCLUDING CITY OF CHICAGO...WITH UPPER 80S IN THE
SOUTHEAST. MINS WILL GENERALLY BE IN THE 60S BOTH TONIGHT AND
WEDNESDAY NIGHT...WITH LOWS ONLY AROUND 70 IN THE CITY...AND MORE
HUMIDITY WEDNESDAY NIGHT AS LOW LEVEL MOISTURE INCREASES AHEAD OF
APPROACHING COLD FRONT. SOUTHWEST WINDS TODAY SHOULD PREVENT THE
LAKE BREEZE FROM AFFECTING MUCH MORE THAN THE IMMEDIATE ILLINOIS
SHORE AREAS...AND STRONGER SOUTHWEST WINDS WEDNESDAY SHOULD PRECLUDE
A LAKE BREEZE ALTOGETHER.
NEXT ITEM OF INTEREST IS THE AFOREMENTIONED COLD FRONT...WHICH
GUIDANCE CONTINUES TO INDICATE WILL SAG INTO FAR NORTHERN ILLINOIS
EARLY THURSDAY MORNING...AND PUSH SOUTH ACROSS THE CWA DURING THE
DAY. MAIN QUESTION WITH THIS FRONT IS WITH THE AMOUNT/COVERAGE OF
SHOWERS AND THUNDERSTORMS THAT MAY OCCUR WITH IT. MAIN UPPER LEVEL
SHORT WAVE AND JET SUPPORT PASSES WELL NORTH OF THE AREA ACROSS
ONTARIO AND THE NORTHERN LAKES WEDNESDAY INTO EARLY THURSDAY...WITH
CONVERGENCE ALONG/AHEAD OF THE LOW LEVEL FRONTAL BOUNDARY THE MAIN
SOURCE OF FORCING FOR STORMS FARTHER SOUTH INTO THE MIDWEST.
THUNDERSTORMS ARE MUCH MORE LIKELY ACROSS PARTS OF MINNESOTA...
WISCONSIN AND MICHIGAN WEDNESDAY AFTERNOON/EVENING...WHERE
INSTABILITY WILL BE MAXIMIZED DUE TO DIURNAL HEATING OF MOIST AXIS
ALONG THE FRONT. WHILE A FEW STORMS COULD MAKE IT INTO FAR NORTHERN
IL DURING THE EVENING OR OVERNIGHT HOURS...THE TIMING WILL BE FAIRLY
UNFAVORABLE FOR SIGNIFICANT COVERAGE AS THE BOUNDARY LAYER COOLS AND
STABILIZES OVERNIGHT. CAN ONLY JUSTIFY CHANCE POPS WEDNESDAY NIGHT
ACROSS THE NORTH...AND DURING THE DAY THURSDAY FARTHER SOUTH ACROSS
THE CWA AS THE FRONT CONTINUES TO DRIFT SOUTH WITHIN A WEAK
SHEAR/WEAK UPPER SUPPORT ENVIRONMENT. SOMEWHAT DIFFUSE FRONT
EVENTUALLY STALLS IN A NORTHWEST-SOUTHEAST ORIENTATION FROM IA INTO
CENTRAL IL THURSDAY NIGHT...AND HAVE MAINTAINED SOME SLIGHT CHANCE
POPS FOR SOME ISOLATED SHRA/TSRA ACROSS THE FAR SOUTH/SOUTHWEST
PARTS OF THE CWA NEAR THE FRONT.
AS THE FRONT PUSHES SOUTH INTO THE CWA THURSDAY...HIGH PRESSURE WILL
BUILD SOUTHEAST ACROSS THE GREAT LAKES REGION. NORTH/NORTHEAST WINDS
WILL BRING COOLER AIR AND ONSHORE WINDS WHICH WILL MAKE FOR SHORT
COOL-DOWN FROM OUR CURRENT MID-WEEK WARMTH...THOUGH WITH TEMPS STILL
NEAR/ABOVE NORMAL IN THE 80-85 RANGE. ONSHORE FLOW MAY LIMIT LAKE
MICHIGAN SHORE SITES TO THE UPPER 70S FRIDAY AND SATURDAY.
LONGER RANGE GUIDANCE CONTINUES TO INDICATE NORTHEASTWARD EXPANSION
OF THE UPPER RIDGE WHICH IS CURRENTLY OVER THE SOUTHWESTERN CONUS
THIS WEEKEND. WITH BUILDING HEIGHTS OVER THE AREA SUNDAY AND THE
SURFACE HIGH PRESSURE MOVING OFF TO THE EAST AND ALLOWING A RETURN
OF SOUTH WINDS...TEMPS SHOULD BEGIN THEIR CLIMB BACK INTO THE UPPER
80S/AROUND 90...POTENTIALLY 90+. HEAT BUILDS INTO MONDAY...THOUGH
MODELS DO SHOW DIFFERENCES IN MAINTAINING THE RIDGE OVERHEAD AS
NEW 00Z ECMWF SHOWS SOME RUN TO RUN INCONSISTENCY AND FLATTENS IT
MORE QUICKLY WITH A SHORT WAVE TROUGH PROPAGATING SOUTHEAST ACROSS
THE GREAT LAKES MONDAY. IN ANY CASE... IT DOES APPEAR THAT A LATE-
AUGUST HEAT WAVE IS IN STORE FOR THE AREA LATE THIS WEEKEND INTO
EARLY NEXT WEEK.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* NONE.
KB
//DISCUSSION...UPDATED 12Z...
THE REGION REMAINS UNDER THE INFLUENCE OF HIGH PRESSURE TO OUR EAST
AND AN APPROACHING COLD FRONT TO THE NORTHWEST. A MODEST SOUTHWEST
GRADIENT WILL DEVELOP BETWEEN THESE FEATURES TODAY...WITH WINDS
PICKING UP THIS MORNING WITH GUSTS INTO THE MID TEENS BY LATE
MORNING AND THROUGH THE AFTERNOON. SOME DIURNAL CUMULUS CLOUDS WILL
DEVELOP WITH BASES AROUND 050 TODAY. BY MID TO LATE THIS
EVENING...EXPECT WINDS TO DIMINISH BACK BELOW 10 KT. WINDS WILL BE A
LITTLE GUSTIER DURING THE DAY WEDNESDAY...WITH GUSTS INTO THE HIGH
TEENS EXPECTED. THE COLD FRONT IS NOT EXPECTED TO IMPACT THE AREA
UNTIL LATE WEDNESDAY NIGHT/EARLY THURSDAY...WELL BEYOND THE CURRENT
TAF PERIOD.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.
KB
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
WEDNESDAY NIGHT...CHC TSRA.
THURSDAY...CHC TSRA.
FRIDAY...VFR.
SATURDAY...SLT CHC TSRA.
SUNDAY...VFR.
MONDAY...VFR.
BMD
&&
.MARINE...
242 AM CDT
SOUTH TO SOUTHWEST WINDS ARE EXPECTED TO REMAIN FRESH OVER LAKE
MICHIGAN THROUGH WEDNESDAY NIGHT WHEN A COLD FINALLY BEGINS TO
SLIDE SOUTH ACROSS THE LAKE. WINDS WILL GENERALLY BE IN THE 15 TO
25 KT RANGE UNTIL THEN OVER THE NORTH HALF OF THE LAKE...AND UP TO
20 KTS AT TIMES FOR THE SOUTH HALF OF THE LAKE. OUTSIDE OF AN
INITIAL PERIOD OF GUSTY NORTHERLY WINDS BEHIND THE FRONT...WINDS
ARE EXPECTED TO SUBSIDE AS HIGH PRESSURE BUILDS OVER THE AREA
THURSDAY NIGHT AND FRIDAY. WINDS ARE EXPECTED TO TURN SOUTH TO
SOUTHWEST AGAIN NEXT WEEKEND...AND INCREASE ESPECIALLY OVER THE
NORTH HALF OF THE LAKE AHEAD OF ANOTHER COLD FRONT.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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[top]
Area Forecast Discussion
National Weather Service Lincoln IL
1026 AM CDT Tue Aug 20 2013
.DISCUSSION...
ISSUED 1026 AM CDT Tue Aug 20 2013
9 AM surface map showed high pressure centered over the mid-
Atlantic coast, with ridging extending west into southern IL and
MO. This put most of central IL in a very light wind regime,
though light return southerly flow on the back side of the ridge had
pushed east to the I-55 corridor. Aloft, water vapor imagery
indicated a cutoff mid-level low circulating over west central IL
and an additional shortwave in western KY. 12Z ILX sounding was
quite dry in the mid levels and high-res models focus better
ascent ahead of the KY shortwave as it drifts northeast this
afternoon. A very isolated shower or storm is possible in the far
southeast this afternoon where RAP soundings show little to no cap in
place, however feel if anything does develop should be confined
farther east into southern IN and have maintained a dry forecast.
Otherwise, mostly sunny skies will dominate the CWA today. Mixing
to around 850MB supports highs of 85-89F.
25
&&
.AVIATION...
ISSUED 600 AM CDT Tue Aug 20 2013
MVFR and local IFR vsbys still possible due to ground fog until
13z...esp at DEC and CMI...otherwise VFR conditions are expected
over the remainder of this forecast period. Weak upper level
disturbance moving acrs the area without much in the way of
weather as the atmosphere, except near gound level, was quite
dry. Forecast soundings continue to indicate sct-bkn cumulus
will develop late this morning with bases of 4500-5000 feet.
Will continue to carry mostly scattered bases today with the
better chances of seeing some bkn cigs at times just east of
I-55. What clouds that do form during peak heating today should
once again quickly dissipate late this afternoon with a mainly
clear sky dominating tonight. The threat for more fog again
late tonight/early Wednesday morning appears to be less than
the past few mornings due to a southerly breeze expected to
hold up just enough to prevent any widespread development so
will leave the mention of fog out of the TAFs tonight. Winds
today will be out of the south at 5 to 10 kts.
Smith
&&
.PREV DISCUSSION...
ISSUED 225 AM CDT Tue Aug 20 2013
Illinois remains on the periphery of high pressure that was
centered near the mid-Atlantic coast early this morning. Have seen
some high clouds rotating around an upper level circulation that
was very evident on water vapor imagery, dropping along the
Mississippi River in far western Illinois.
Primary forecast focus remains on rain chances later this week,
along with extended period of very warm conditions.
SHORT TERM...Today through Thursday...
Upper circulation to continue to carve out a broad trough over
Illinois today, with model guidance showing some potential for a
small closed circulation forming by late tonight before the trough
swings eastward. Currently appears that any rain with this feature
will remain to our east. Temperatures continue a slow but steady
rise and should reach the upper 80s most areas by Wednesday.
Main focus shifts to an upper wave moving across southwest Canada
early this morning. Broad east-west ridging over the southern U.S.
should start to amplify across the Rockies Wednesday night,
allowing the wave to dig more as it sweeps through the Great Lakes
region. The guidance is generally in agreement with the resulting
surface front pushing all the way through the state on Thursday.
Still some question as to whether or not this is overly aggressive
for this time of year, especially the NAM solution as it brings
temps all the way down to the lower 50s by Friday morning behind
the front. Rain-wise, have introduced some slight chance PoPs
after midnight Wednesday night across the northern CWA, and a
broad area of 30% chances east of a Macomb to Lawrenceville line
on Thursday. Have lingered some slights into Thursday night and
Friday, as the ECMWF model shows some hints of the front pushing
back northeast.
LONG TERM...Friday through Monday...
Broad dome of high pressure aloft to cover most of the country
this weekend and early next week. Convective systems traversing
the northern flank of the ridge should stay to our north, with
core of the upper high nearly overhead. After a brief cool down on
Friday, gradual warming will take place through early next week,
with highs near 90 becoming more common. Humidity levels not
expected to get out of hand due to the recent dry conditions, so
heat index values will only be a few degrees warmer than the
observed temperatures.
Geelhart
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CARIBOU ME
604 AM EDT TUE AUG 20 2013
.SYNOPSIS...
A WEAK FRONTAL BOUNDARY WILL PUSH INTO NORTHERN AREAS TODAY. THE
FRONT WILL LIFT BACK NORTH TONIGHT INTO WEDNESDAY AS HIGH
PRESSURE MOVES ONTO THE MID ATLANTIC COAST.
&&
.NEAR TERM /THROUGH TONIGHT/...
604 AM UPDATE...MADE SOME ADJUSTMENTS TO THE POP/WX/QPF GRIDS FOR
EARLY THIS MORNING BASED ON THE LATEST RADAR TRENDS AND
OBSERVATIONS. SCATTERED SHOWERS ARE MOVING ACROSS CENTRAL AND
SOUTHERN PISCATAQUIS COUNTY...FURTHER SOUTH THEN EARLIER EXPECTED.
THE HRRR DID NOT DO A GOOD JOB WITH THE SOUTHERN EXTENT OF THE
SHOWERS EARLY THIS MORNING. THE GFS AND RUC HAD A SOMEWHAT BETTER
HANDLE ON THE SHOWERS. SHOWERS ACROSS AROOSTOOK COUNTY HAVE PUT
DOWN A FEW HUNDREDTHS TO AROUND ONE TENTH OF AN INCH OF RAIN
DURING THE PAST FEW HOURS. EXPECT MUCH OF THE SHOWER ACTIVITY TO
PUSH OUT OF THE CWA BY MID MORNING WITH A BIT OF A BREAK BEFORE
MORE SHOWERS AND STORMS FIRE UP THIS AFTERNOON.
A WEAK BACKDOOR COLD FRONT IS SLIPPING SOUTH INTO NORTHERN MAINE
EARLY THIS MORNING IN RESPONSE TO AN AREA OF LOW PRESSURE THAT
TRACKED ACROSS THE NW ATLANTIC AND IS NOW NEAR THE SOUTHERN TIP OF
GREENLAND. THE FRONT ALTHOUGH WEAK WILL PROVIDE SOME CONVERGENCE
AND A FOCUSING MECHANISM FOR CONVECTION TODAY INTO THIS EVENING.
OVERALL THE ATMOSPHERIC CONDITIONS LOOK MORE FAVORABLE FOR
CONVECTION TODAY WHEN COMPARED TO YESTERDAY. THE PRECIPITABLE H20
WHICH WAS 1.05 INCHES ON THE 00Z KCAR SOUNDING IS EXPECTED TO
INCREASE TO AROUND 1.3 INCHES AND SFC DEW POINTS WHICH WERE IN THE
50S MONDAY AFTERNOON WILL LIKELY CLIMB INTO THE LOW 60S TODAY. THE
SBCAPE IS PROGGED AT 500-1000 J/KG ON THE NAM...AND MUCH HIGHER ON
THE GFS WHICH LOOKS OVERDONE. BOTH THE NAM AND GFS HAVE THE 0-6 KM
SHEAR AROUND 35 KT THIS AFTERNOON SO SOME OF THE STORMS MAY BECOME
ORGANIZED ENOUGH TO PRODUCE GUSTY WIND AND HEAVY DOWNPOURS AND AN
ISOLATED STORM COULD BECOME SEVERE. THE MOST LIKELY AREAS FOR
STORMS WILL BE ACROSS NORTHERN MAINE FROM THE KATAHDIN REGION
NORTH AND ACROSS EASTERN MAINE ABOUT AS FAR SOUTH AS NORTHERN
WASHINGTON COUNTY. THE WARMEST TEMPS TODAY WILL BE ACROSS INTERIOR
DOWNEAST AREAS WHERE THERE WILL BE MORE SUNSHINE AND A MUCH LOWER
CHANCE OF CONVECTION. HIGHS WILL LIKELY REACH THE MID 80S IN THE
BANGOR AREA AND NOT GET OUT OF THE 70S FROM THE KATAHDIN REGION
NORTH. THE CONVECTION SHOULD DIE OFF FAIRLY QUICKLY THIS EVENING
WITH THE LOSS OF DAYTIME HEATING AS THE ATMOSPHERE RAPIDLY
STABILIZES. LOWS TONIGHT WILL BE FAIRLY UNIFORM ACROSS THE REGION
FROM THE UPPER 50S TO LOW 60S AND A BIT ON THE MUGGY SIDE TOO.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL BE BUILDING OFF THE MID ATLANTIC COAST ON
WEDNESDAY AS A FRONTAL BOUNDARY PUSHES SOUTH INTO EASTERN CANADA.
THE COMBINATION OF THE HIGH TO THE SOUTH AND FRONT TO THE NORTH
WILL BRING A VERY WARM AND BREEZY DAY ON WEDNESDAY WITH A PARTLY
TO MOSTLY SUNNY SKY. THE GRADIENT WILL ALLOW A BREEZE TO CONTINUE
OVERNIGHT MAINLY ACROSS THE NORTH. THIS MAY RESULT IN WARMER LOWS
NORTH THAN DOWNEAST. LOWS THROUGHOUT THE REGION SHOULD BE IN THE
LOW 60S. WARM AND HUMID CONDITIONS WILL CONTINUE THURSDAY. A
STRONG FRONTAL BOUNDARY WILL PUSH DOWN INTO THE AREA LATE THURSDAY
WITH SHOWERS AND THUNDERSTORMS LIKELY ESPECIALLY IN NORTHERN AND
WESTERN AREAS LATE IN THE DAY.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A STRONG COLD FRONT WILL PUSH ACROSS THE AREA THURSDAY NIGHT. THIS
WILL GIVE WAY TO A PARTLY SUNNY AND LESS HUMID DAY ON FRIDAY AS A
WEAK UPPER LEVEL TROUGH FOLLOWS THE FRONT. A LARGE AREA OF HIGH
PRESSURE WILL THEN BUILD INTO THE REGION OVER THE WEEKEND BRINGING
SUNNY AND DRY DAYS BOTH SATURDAY AND SUNDAY. HIGH PRESSURE WILL
BRING A SUNNY START TO MONDAY. WARM ADVECTION BEHIND THE HIGH AND
AHEAD OF A TROUGH OF LOW PRESSURE DIPPING DOWN FROM THE NORTHWEST
WILL THEN BRING SOME INCREASING CLOUDS MONDAY AFTERNOON. THIS WILL
BE FOLLOWED BY A CHANCE FOR A SHOWER OR THUNDERSTORM LATE IN THE
DAY ESPECIALLY IN WESTERN AREAS AS THE FRONT PUSHES IN.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
NEAR TERM: VFR THROUGH TONIGHT...EXCEPT MVFR WITH VERY BRIEF IFR
IN HEAVIER SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING
AT THE NORTHERN TERMINALS.
SHORT TERM: VFR CONDITIONS ARE EXPECTED WEDNESDAY INTO EARLY
THURSDAY. CONDITIONS MAY LOWER TO MVFR OR IFR IN SHOWERS AND
THUNDERSTORMS LATE THURSDAY OR THURSDAY EVENING. VFR CONDITIONS
WILL RETURN FRIDAY AND CONTINUE THROUGH THE WEEKEND.
&&
.MARINE...
NEAR TERM: THE SEAS ARE RUNNING AROUND 2-3 FT ON THE COASTAL WATERS
AND AROUND 1 FT ON THE INTRA-COASTAL WATERS. LITTLE CHANGE IS
EXPECTED IN THE SEA STATE THROUGH TONIGHT WITH BOTH THE WIND AND
SEAS REMAINING WELL BELOW SCA LEVELS.
SHORT TERM: WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SCA
WEDNESDAY THROUGH THE COMING WEEKEND.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...CB
SHORT TERM...BLOOMER
LONG TERM...BLOOMER
AVIATION...CB/BLOOMER
MARINE...CB/BLOOMER
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
729 AM EDT TUE AUG 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 405 AM EDT TUE AUG 20 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW REBOUNDING UPR RDG
INTO THE UPR GRT LKS ON THE SRN FLANK OF ZONAL FLOW OVER CANADA. A
PRONOUNCED H5 THERMAL RDG IS EVIDENT STRETCHING FM THE NRN PLAINS
THRU NW MN AND INTO NW ONTARIO...WITH THE 00Z H5 TEMP UP TO -7C AT
INL...COMPARED TO THE -11C OBS AT APX CLOSER TO DEPARTING SHRTWV IN
THE CENTRAL LKS. THE COMBINATION OF THE ASSOCIATED MID LVL CAPPING
AND SUBSIDENCE RELATED TO DEEP LYR QVECTOR DVGC ACCOMPANYING THE
BLDG RDG IS RESULTING IN MOCLR SKIES OVER THE CWA EARLY THIS MRNG
DESPITE ADVECTION OF SOMEWHAT HIER LLVL MSTR WITH H85 DEWPTS UP TO
16C AT MPX IN THE SW FLOW ARND SFC HI PRES IN THE MID ATLANTIC
STATES. DESPITE THE MOCLR SKIES...THE STEADY SW FLOW IS RESULTING IN
ABV NORMAL TEMPS EARLY THIS MRNG...ESPECIALLY OVER THE W HALF OF UPR
MI IN THE DOWNSLOPE AREAS NEAR LK SUP...WHERE READINGS ARE HAVING A
HARD TIME FALLING BLO 70. BUT EVEN WARMER AIR IS TO THE W...WITH 00Z
H85 TEMPS RANGING FM 14C AT GRB AND APX TO 17C AT MPX...19C AT
INL...AND A TOASTY 25C AT BISMARCK. THERE IS ANOTHER SHRTWV SHIFTING
EWD THRU THE NRN PLAINS...BUT THE 00Z BISMARCK RAOB IS SO DRY THERE
IS NO PCPN OR EVEN ANY CLD COVER.
MAIN FCST CONCERNS IN THE SHORT TERM FOCUS ON TEMPS AND SMALL SHRA/
TS CHCS.
TODAY...UPR MI IS FCST TO REMAIN UNDER THE UPR RDG AXIS...WITH H5
THERMAL RDG/TEMPS ARND -7C NOTED ABOVE SHIFTING OVHD IN MID LVL
SUBSIDENCE REGIME. CONTINUED SW FLOW ARND STAGNANT SFC HI PRES IN
THE MID ATLANTIC IS FCST TO LIFT H85 TEMPS UP TO 17-18C OVER THE E
TO 18-19C OVER THE W BY 00Z WED. MIXING TO H8 ON GFS/NAM FCST SDNGS
YIELDS HI TEMPS REACHING TO ARND 90 AWAY FM THE COOLING INFLUENCE OF
LK MI...SO PREFER TO HEDGE TOWARD THE HI END OF GUIDANCE FOR MAX
TEMPS FCST. THIS SW FLOW WL ALSO ADVECT THE HIER LLVL MSTR SHOWN ON
THE 00Z MPX RAOB INTO THE UPR LKS...RESULTING IN A MORE HUMID AND
UNCOMFORTABLE DAY AS SFC DEWPTS RUN WELL INTO THE 60S. DESPITE THE
INCRSG HEAT/HUMIDITY THAT WL LIFT MUCAPE AOA 2000J/KG THIS AFTN PER
MODIFIED GFS/NAM FCST SDNGS FOR SFC T/TD 90/65...SUSPECT THE MID LVL
WARMTH/DRYNESS/STABILITY WL SUPPRESS CONVECTION. ONE POSITIVE FOR
SHRA/TS WOULD BE THE APRCH LATER THIS AFTN OF SHRTWV NOW MOVING THRU
THE NRN PLAINS...BUT CONSIDERING GFS/NAM MOS POPS AOB 10 PCT...
PRESENCE OF VERY WARM H5 AIR/SHARPER CAPPING...AND ABSENCE OF
APPRECIABLE LK BREEZE CNVGC WITH SUPPRESSION OF LK SUP BREEZE IN
SYNOPTIC SW FLOW...OPTED TO GO DRY FOR THE ENTIRE CWA TODAY.
TNGT...STEADY SW FLOW WITH H925 WINDS UP TO 30-35KTS UNDER
SHARPENING PRES GRADIENT BTWN MID ATLANTIC HI PRES AND APRCHG COLD
FNT IN MN ASSOCIATED WITH SHRTWV RIDING E IN THE ZONAL FLOW THRU
CANADA IS FCST TO LIFT H85 TEMPS AOA 20C OVER THE WRN CWA OVERNGT.
WL TEND AOA THE HI END OF GUIDANCE FOR MIN TEMPS...ESPECIALLY IN THE
DOWNSLOPE AREAS NEAR LK SUP OVER THE W HALF. CONCERNED THE ARRIVAL
OF SOME DEEP LYR QVECTOR CNVGC/STEEPENING LAPSE RATES WITH FALLING
H5 TEMPS TOWARD -10C IN ADVANCE OF THE FNT LATE TNGT MIGHT GENERATE
SOME SHRA/TS OVER AT LEAST THE NW HALF OF THE CWA. ALTHOUGH THE BULK
OF THE NUMERICAL MODELS SHOW A DRY FCST FOR THE CWA THRU 12Z WED...
OPTED TO RETAIN SOME SCHC POPS OVER THE MAINLY WRN/NCENTRAL LK SUP
SINCE THERE WL BE SOME DYNAMIC SUPPORT AND THE GFS AS WELL AS THE
LOCAL WRF/ARW MODELS DO GENERATE SOME PCPN.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 405 AM EDT TUE AUG 20 2013
NOT TOO MUCH HAS CHANGED SINCE 24 HOURS AGO...AND AM WELL IN
AGREEMENT WITH THE PREVIOUS SHIFT. STILL HAVE SOME
UNCERTAINTY...ESPECIALLY WITH SOME SPECIFIC ITEMS...BUT WILL TALK
ABOUT THAT IN MORE DETAIL BELOW.
FOR WED...A NRN STREAM TROUGH WILL SLIDE ACROSS THE CWA WED INTO WED
NIGHT...WHICH WILL BRING INCREASED CHANCES OF PRECIP FOR THAT
PERIOD. WITH 850MB TEMPS AROUND 20C AT PEAK HEATING WED
AFTERNOON...HIGH TEMPS AHEAD OF THE FRONT AND ASSOCIATED PRECIP AND
CLOUD COVER SHOULD BE ABLE TO GET INTO THE LOW 90S /AWAY FROM LAKE
MICHIGAN FROM MODERATING SW WINDS AND IMMEDIATE SHORES OF LAKE
SUPERIOR/. THE SW-NE ORIENTED COLD FRONT LOOKS TO MOVE INTO WRN
UPPER MI AROUND 18Z WED...WITH SOME VARIABILITY BETWEEN THE MODELS
/ECMWF AND GFS SHOWING THIS SOLUTION AND THE NAM AND GEM BEING
FASTER/. BY 00Z THU...MODELS SHOW THE COLD FRONT FROM ERN LAKE
SUPERIOR INTO SCENTRAL UPPER MI...WITH THE FRONT JUST E OF THE CWA
BY 06Z THU. SHOULD SEE CAPE VALUES OF 1500-2500J/KG AND POSSIBLY AS
HIGH AS 3000J/KG AHEAD OF THE FRONT. 0-6KM SHEAR LOOKS TO BE ON THE
LOW SIDE FOR ORGANIZED THUNDERSTORMS AT AROUND 20KTS...AND THAT IS
MOSTLY UNIDIRECTIONAL. STORM MODE SHOULD BE MULTICELL CLUSTERS AND
BEST THREAT FOR SEVERE WEATHER WILL BE MORE ISOLATED DAMAGING
WINDS...ESPECIALLY OVER THE SCENTRAL CWA WHERE DCAPE VALUES WILL BE
ENHANCED. HAIL THREAT WILL BE MORE MINIMAL DUE TO WEAK SHEAR AND THE
FREEZING LEVEL BEING AROUND 12KFT. WILL CONTINUE TO SHOW LIKELY POPS
OVER MUCH OF THE AREA TIMED CLOSE TO EXPECTED FROPA. WITH THE
UNCERTAINTY IN FRONTAL TIMING...HIGH TEMPS MAY BE MORE IN JEOPARDY
IF THE FRONT COMES THROUGH FASTER AND CONVECTIVE COVERAGE/INTENSITY
IS MORE UNCERTAIN.
BY LATE WED NIGHT...SHOULD SEE ALL PRECIP AND MOST CLOUDS CLEARED
OUT AS AS SFC HIGH MOVES IN FROM THE W...AND WITH 850MB TEMPS AROUND
12C BY 12Z THU...LOW TEMPS SHOULD BE ABLE TO QUICKLY FALL OFF TO
AROUND 50F OVER PARTS OF THE INTERIOR W.
WHILE A COUPLE OF UPPER SHORTWAVES MOVE THROUGH THU AND FRI...THE
SFC HIGH WILL BE DIRECTLY OVER THE CWA LATE THU INTO THU NIGHT...AND
WILL HAVE JUST MOVED E OFF THE CWA BY LATE FRI...SO IT WILL BE TOO
DRY FOR ANY PRECIP OVER THE CWA RESULTING FROM THE SHORTWAVES. 850MB
TEMPS COOL SOME MORE WITH CONTINUED NLY FLOW AND THE SHORTWAVE ON
THU TO AROUND 10-11C...RESULTING IN MUCH COOLER HIGH TEMPS IN THE
70S /OR POSSIBLY LOW 80S OVER FAR SCENTRAL UPPER MI/. FRI TEMPS LOOK
SIMILAR IF NOT A DEGREE OR TWO COOLER IN MOST LOCATIONS.
MORE UNCERTAIN ON LATER TIME FRAMES...BUT SOME PRECIP LOOKS POSSIBLE
LATE FRI NIGHT INTO EARLY SAT NIGHT AS A WARM FRONT/WAA MOVES INTO
THE CWA. MODELS AGREE ON BRINGING UPPER RIDGING ACROSS THE CWA SAT
AND SUN...RESULTING IN 850MB TEMPS INCREASING TO AROUND 20C BY 00Z
MON. THINK TEMPS MAY BE TOO LOW IN THE EXTENDED /SOMEWHAT FOR
SAT...BUT MORE SO FOR SUN/...BUT UNCERTAINTY RELATING TO PRECIP/CLOUDS
MAKES IT HARD TO JUSTIFY INCREASING TEMPS SIGNIFICANTLY. THINK THAT
CONSENSUS OF GUIDANCE WILL BE FAIRLY REPRESENTATIVE FOR SAT AND SUN.
MUCH DECREASED CONFIDENCE ON MON AS MODELS HAVE DIFFICULTY HANDLING
CONVECTION POSSIBILITIES NEAR/OVER THE CWA. WILL CONTINUE TO USE
CONSENSUS OF GUIDANCE FOR MON GIVEN THE LIMITED CONFIDENCE.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 727 AM EDT TUE AUG 20 2013
EXPECT VFR CONDITIONS THRU THE FCST PERIOD AT ALL 3 TAF SITES WITH A
RELATIVELY DRY LLVL AIRMASS DOMINATING. WITH DAYTIME HEATING/
MIXING...A GUSTY SW WIND WL DVLP BY LATE MRNG. AFTER SUNSET...AN
INVERSION WL FORM AND RESULT IN LLWS WITH STRENGTHENING NOCTURNAL SW
LLJ UNDER SHARPENING PRES GRADIENT AHEAD OF APRCHG COLD FNT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 405 AM EDT TUE AUG 20 2013
OVERALL...EXPECT WINDS LESS THAN 20KT THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. ONE PERIOD OF STRONGER WINDS (GUSTS TO 20-25KT)
MAY OCCUR TONIGHT AS PRES GRADIENT TIGHTENS AHEAD OF APPROACHING
COLD FRONT...BUT HI OVERWATER STABILITY WITH INFLUX OF VERY WARM
AIRMASS WILL LIMIT THE INCREASE OF WIND SPEED NEAR THE COOLER LAKE
SURFACE. THE ARRIVAL OF MORE HUMID AIR MAY RESULT IN SOME FOG
FORMATION OVER THE COOLER LAKE WATERS...BUT RESTRICTED THE FOG
FORECAST TO AREAS WHERE SOME SHOWERS OR THUNDERSTORMS ARE EXPECTED.
ANY FOG WILL DISSIPATE WED AFTN/EVENING FOLLOWING A COLD FRONTAL
PASSAGE AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TITUS
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
622 AM CDT TUE AUG 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT TUE AUG 20 2013
TODAY AND TONIGHT...850MB WINDS CONTINUE FROM THE SOUTH WITH A
SLIGHT SOUTHWEST COMPONENT. SPEEDS INCREASE TO AROUND 25 KTS
SUPPORTING 15 TO 25 MPH SFC WIND SPEEDS. A DRYLINE BULGE SHOULD
DEVELOP ACROSS WRN NEB AND THE SANDHILLS SUPPORTING DEEPER
MIXING. SOME OF GUIDANCE SUGGESTS LOW 100S FOR HIGHS. THE PROBLEM
AREA IS NRN NEB AND VALENTINE WHERE HOT DRY AIR WILL BLOW NORTH
OFF THE SANDHILLS. IF THE SANDHILLS ARE DRY THEN THIS AREA WILL
RISE ABOVE 100.
FOR NOW TEMPS ARE A BLEND OF TRIED AND TRUE GUIDANCE FOR HIGHS IN
THE 90S TO 100. WITH H700MB TEMPS RISING TOWARD 16C THIS AFTN
ACROSS WRN NEB THERE COULD BE SOME LOW 100S BUT WE WOULD LIKE TO
SEE A MORE SWRLY COMPONENT TO THE 850 MB WINDS AND 700MB WINDS
DUE WEST VS THE RAP FCSTING SOUTHWEST WINDS AT 700MB.
ISOLATED TSTMS ARE POSSIBLE THIS AFTN ACROSS NWRN NEB AS A COLD
FRONT DROPS IN. A SLIGHT COOLING ALOFT TONIGHT MIGHT ALLOW A FEW
STORMS TO FORM FARTHER EAST ACROSS NRN NEB. OTHERWISE THE HEAT
CONTINUES TODAY WITH DEW POINTS IN THE UPPER 60S EAST OF HIGHWAY
83. THE DRYLINE BULGE SHOULD REACH TO HIGHWAY 83 THIS AFTN AND
THEN RETREAT WEST THIS EVENING.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 341 AM CDT TUE AUG 20 2013
SUMMER LIKE WEATHER THROUGH MUCH OF THE MID TO LONG RANGE
FORECAST. UPPER LEVEL RIDGE WILL CONTINUE TO MIGRATE EAST AND
BECOME CENTERED OVER THE PLAINS BY THE WEEKEND. MODELS IN GOOD
AGREEMENT WITH THE 500 MB HEIGHT OF THE HIGH REACHING 1594M TO
1595M.
AT THE SFC A COLD FRONT WILL PUSH ACROSS THE AREA WED...WHICH
SHOULD BE THE FOCUS FOR ISOLD THUNDERSTORMS BY EARLY AFTERNOON AS
CAP WEAKENS. INITIALLY MOISTURE IS LIMIT IN THE COLUMN...WITH
PRECIP H2O AROUND AN INCH...NEAR THE 50 PERCENTILE FOR
AUGUST...HOWEVER AN INCREASE THROUGHOUT THE DAY...POOLING ALONG
THE BOUNDARY...IS EXPECTED. THE DEW PTS ARE EXPECTED IN THE MID
AND UPPER 60S FOR THE AFTERNOON...AND SHOULD BE ENOUGH TO HELP
BREAK THE CAP. SOUNDINGS SUGGEST HIGH BASED STORMS NEAR 8K TO 10K
FEET. DIRECTIONAL SHEAR IS DECENT...HOWEVER LIMITED SPEED SHEAR.
A FEW STRONG STORMS CAN NOT BE RULED OUT...AND WILL BE MONITORED.
WEAK SECONDARY BOUNDARY AND UPPER LEVEL WAVE WILL PUSH INTO THE
NW WED EVENING AND ACROSS NRN NEB THURSDAY. SLIGHT CHANCE POPS
WARRANTED AT THIS TIME...ALTHOUGH CONVECTION ALONG THE COLD FRONT
MAY CAUSE THIS DISTURBANCE TO DIMINISH IN EFFECT. LINGERING
CLOUDS AND SLIGHTLY COOLER AIR BEHIND THE COLD FRONT WILL HOLD
TEMPS IN THE 80S FOR MOST AREAS THURS.
BY FRIDAY THE RIDGE WILL BEGIN TO END THE MAIN THREAT FOR STORMS.
A LEESIDE TROUGH DEVELOPS WHILE A LARGE SFC HIGH EXPENDS ACROSS
THE GREAT LAKES. ACTIVITY IS LIKELY ALONG THE HIGHER TERRAIN/SFC
TROUGH TO THE WEST AND MAY IMPACT THE FAR WESTERN ZONES DUE TO
WESTERLY WINDS. HAVE INCLUDED A SLIGHT CHANCE FOR THE EASTERN
PANHANDLE LATE SATURDAY AS A STRONGER UPPER LEVEL WAVE CROSSES
THE NORTHERN/CENTRAL ROCKIES...OTHERWISE DRY. WITH THE INFLUENCE
OF THE RIDGE...HIGHS WARM BACK INTO THE LOWER TO MID 90S...WELL
ABOVE NORMAL FOR THE LAST HALF OF AUGUST.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 620 AM CDT TUE AUG 20 2013
VFR IS EXPECTED TODAY AND TONIGHT. ISOLATED THUNDERSTORMS ARE
POSSIBLE LATE THIS AFTERNOON ACROSS SHERIDAN AND CHERRY COUNTIES
AND ELSEWHERE ACROSS NORTHERN NEBRASKA TONIGHT. OTHERWISE SCT-
BKN250 CLOUDS ARE EXPECTED TO MOVE THROUGH TODAY AND TONIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...MASEK
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
717 AM EDT TUE AUG 20 2013
.SYNOPSIS...
A REMNANT FRONTAL BOUNDARY WILL REMAIN NEARLY STALLED AND WEAKEN
ACROSS THE REGION THROUGH MID WEEK. A MODERATELY STRONG COLD
FRONT IS EXPECTED LATE FRIDAY NIGHT. THIS WILL USHER COOLER AND
DRIER AIR THIS COMING WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 717 AM TUESDAY...DENSE FOG ADVISORY ISSUED FOR PREVALENT
1/4 MILE VSBYS ALONG THE COAST AND COASTAL INTERIOR. VSBYS AER
EXPECTED TO IMPROVE BY 9AM. THE PREVIOUS DISCUSIION FOLLOWS.
AN OLD FRONTAL BOUNDARY REMAINS STALLED OVER THE AREA AND MODEL
GUIDANCE DEVELOPS ANOTHER UPPER LOW OVER THE MISSISSIPPI VALLEY
DURING THE PERIOD. THE NET RESULT SHOULD BE MORE OF THE SAME
ACROSS THE AREA TODAY WITH SCATTERED SHOWERS AND THUNDERSTORMS
EXPECTED...MAINLY DURING THE AFTERNOON AND EARLY EVENING. MAXIMUM
TEMPERATURES SHOULD REACH THE MIDDLE 80S UNDER A PARTLY TO MOSTLY
CLOUDY SKY. MINS TONIGHT SHOULD FALL TO THE LOWER 70S. AT THIS
TIME DO NOT ANTICIPATE NEEDING A DENSE FOG ADVISORY BUT WIDESPREAD
FOG IS EXPECTED THIS AM...PARTICULARLY OVER EASTERN SECTIONS OF
THE AREA.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...NEAR SEASONABLE TEMPERATURES ON WEDNESDAY AS
SURFACE HIGH PRESSURE SITS NOT ONLY OVER THE WEST ATLANTIC BUT ALSO
THE SOUTHEASTERN U.S. UPPER LEVEL RIDGE OVER THE WEST ATLANTIC
BEGINS TO RETREAT TO THE EAST WHILE TROUGHINESS STRENGTHENS OVER
OHIO VALLY. ISO TO WIDELY SCATTERED CONVECTION JUST ABOUT AREA-WIDE
BUT STABILIZING OCEAN AIR TO MAKE FOR SLIGHTLY LOWER POPS ALONG THE
COAST. THE UPPER SYSTEM SWINGS BY TO OUR NORTH LATE THURSDAY INTO
THURSDAY NIGHT AND SHOULD LEAD TO A SMALL UPTICK IN RAIN CHANCES.
SOME MID LEVEL DRY AIR WILL ADVECT INTO THE REGION BEHIND THE
TROUGH.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 3 AM TUESDAY...WESTERN U.S. UPPER RIDGE BUILDS FOR MOST OF THE
PERIOD ALLOWING FOR EASTERN TROUGH TO SHARPEN. PREFRONTAL SURFACE
TROUGH IN THE NW FLOW DRIVEN INTO THE REGION ON FRIDAY TO TOUCH OFF
STORMS DESPITE POSSIBLE RELATIVE DRYNESS IN THE MID LEVELS. THIS IS
FOLLOWED BY WHAT MAY BE A MODERATELY STRONG COLD FRONTAL PASSAGE
FRIDAY NIGHT OR SATURDAY MORNING. SUNDAY AND MONDAY SHOULD BRING IN
SOME COOL AND DRY AIR BY AUGUST STANDARDS.
&&
.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
AS OF 12Z...LIFR CONDITIONS PRETTY WIDESPREAD THIS MORNING.
CLIMATOLOGICAL TRENDS SUGGEST STRATUS WILL SCATTER BETWEEN 15-16Z.
QUITE A BIT OF MID AND HIGH CLOUDS ABOVE MAY RETARD THE MIXING
PROCESS. HRRR MODEL INDICATES ISOLATED/SCATTERED CONVECTION WILL
FORM ALONG THE RESULTANT BOUNDARY AROUND MIDDAY. COVERAGE WILL BE
SUCH THAT A VCSH SHOULD COVER IT. MOST OF THE ACTIVITY WILL BE
SLIGHTLY INLAND FROM THE COASTAL TERMINALS. CONVECTION ENDS BY EARLY
EVENING...WITH ANOTHER ROUND OF FOG/STRATUS EXPECTED AFTER
MIDNIGHT.
EXTENDED OUTLOOK...EARLY MORNING FOG/STRATUS POSSIBLE WEDNESDAY AND
THURSDAY...ESPECIALLY INLAND. ISOLATED SHOWERS/T-STORMS WEDNESDAY
THROUGH FRIDAY...BECOMING MORE WIDELY SCATTERED ON SATURDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM TUESDAY...OUTSIDE OF LIGHT AND VARIABLE WINDS EARLY TODAY
DUE TO THE LAND BREEZE FORCING THE FRONT OFF THE COAST...EXPECT SE
TO S FLOW AT 10 KT OR LESS THROUGH THE PERIOD. SEAS ARE EXPECTED TO
RUN 2 TO 3 FT.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...HIGH PRESSURE WILL BE LOCATED WELL OFF THE
COAST BUT THERE WILL ALSO BE A SECONDARY CENTER OVER THE
SOUTHEASTERN U.S. THIS WILL KEEP WIND AND SEAS MINIMAL WITH A
PREDOMINANTLY SWRLY DIRECTION ALTHOUGH THE FLOW MAY BACK TO S OR
EVEN SE AT TIMES ESP ALONG THE IMMEDIATE COAST IN ASSOCIATION WITH
THE SEA BREEZE. AN UPPER LEVEL TROUGH MAY BE STRONG ENOUGH TO ERODE
THE STRENGTH OF BOTH SURFACE HIGHS LATER THURSDAY. A LIGHT SW WIND
WILL BE FOUND ACROSS A LARGE PART OF THE SOUTHEAST COAST WHILE THE
RELATIVELY TRANQUIL SEA STATE REMAINS UNCHANGED.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 3 AM TUESDAY...WEAK SW FLOW AHEAD OF A PREFRONTAL TROUGH WILL
VEER TO W OR EVEN NW AS THE TROUGH PASSES BY MIDDAY. NO APPRECIABLE
INCREASE IN WIND SPEED AS EXPECTED WITH THE PASSAGE OF THE WIND
SHIFT. LATE FRIDAY NIGHT THIS WILL BE FOLLOWED BY AN ACTUAL FRONTAL
PASSAGE. A FURTHER VEERING AND INCREASE IN WIND SPEED AND SEAS
EXPECTED.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR SCZ053>056.
NC...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR NCZ099-
105>110.
MARINE...NONE.
&&
$$
NEAR TERM...RAN/8
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
703 AM EDT TUE AUG 20 2013
.SYNOPSIS...
A FRONT WILL REMAIN NEARLY STALLED AND WEAKEN ACROSS THE REGION
THROUGH THE MIDDLE OF THE WEEK. A MODERATELY STRONG COLD FRONT IS
EXPECTED LATE FRIDAY NIGHT. THIS WILL USHER IN SOME COOLER AND
DRIER AIR THIS COMING WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM TUESDAY...AN OLD FRONTAL BOUNDARY REMAINS STALLED OVER
THE AREA AND MODEL GUIDANCE DEVELOPS ANOTHER UPPER LOW OVER THE
MISSISSIPPI VALLEY DURING THE PERIOD. THE NET RESULT SHOULD BE MORE
OF THE SAME ACROSS THE AREA TODAY WITH SCATTERED SHOWERS AND
THUNDERSTORMS EXPECTED...MAINLY DURING THE AFTERNOON AND EARLY
EVENING. MAXIMUM TEMPERATURES SHOULD REACH THE MIDDLE 80S UNDER A
PARTLY TO MOSTLY CLOUDY SKY. MINS TONIGHT SHOULD FALL TO THE LOWER
70S. AT THIS TIME DO NOT ANTICIPATE NEEDING A DENSE FOG ADVISORY
BUT WIDESPREAD FOG IS EXPECTED THIS AM...PARTICULARLY OVER EASTERN
SECTIONS OF THE AREA.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...NEAR SEASONABLE TEMPERATURES ON WEDNESDAY AS
SURFACE HIGH PRESSURE SITS NOT ONLY OVER THE WEST ATLANTIC BUT ALSO
THE SOUTHEASTERN U.S. UPPER LEVEL RIDGE OVER THE WEST ATLANTIC
BEGINS TO RETREAT TO THE EAST WHILE TROUGHINESS STRENGTHENS OVER
OHIO VALLY. ISO TO WIDELY SCATTERED CONVECTION JUST ABOUT AREA-WIDE
BUT STABILIZING OCEAN AIR TO MAKE FOR SLIGHTLY LOWER POPS ALONG THE
COAST. THE UPPER SYSTEM SWINGS BY TO OUR NORTH LATE THURSDAY INTO
THURSDAY NIGHT AND SHOULD LEAD TO A SMALL UPTICK IN RAIN CHANCES.
SOME MID LEVEL DRY AIR WILL ADVECT INTO THE REGION BEHIND THE
TROUGH.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 3 AM TUESDAY...WESTERN U.S. UPPER RIDGE BUILDS FOR MOST OF THE
PERIOD ALLOWING FOR EASTERN TROUGH TO SHARPEN. PREFRONTAL SURFACE
TROUGH IN THE NW FLOW DRIVEN INTO THE REGION ON FRIDAY TO TOUCH OFF
STORMS DESPITE POSSIBLE RELATIVE DRYNESS IN THE MID LEVELS. THIS IS
FOLLOWED BY WHAT MAY BE A MODERATELY STRONG COLD FRONTAL PASSAGE
FRIDAY NIGHT OR SATURDAY MORNING. SUNDAY AND MONDAY SHOULD BRING IN
SOME COOL AND DRY AIR BY AUGUST STANDARDS.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 12Z...LIFR CONDITIONS PRETTY WIDESPREAD THIS MORNING.
CLIMATOLOGICAL TRENDS SUGGEST STRATUS WILL SCATTER BETWEEN 15-16Z.
QUITE A BIT OF MID AND HIGH CLOUDS ABOVE MAY RETARD THE MIXING
PROCESS. HRRR MODEL INDICATES ISOLATED/SCATTERED CONVECTION WILL
FORM ALONG THE RESULTANT BOUNDARY AROUND MIDDAY. COVERAGE WILL BE
SUCH THAT A VCSH SHOULD COVER IT. MOST OF THE ACTIVITY WILL BE
SLIGHTLY INLAND FROM THE COASTAL TERMINALS. CONVECTION ENDS BY EARLY
EVENING...WITH ANOTHER ROUND OF FOG/STRATUS EXPECTED AFTER
MIDNIGHT.
EXTENDED OUTLOOK...EARLY MORNING FOG/STRATUS POSSIBLE WEDNESDAY AND
THURSDAY...ESPECIALLY INLAND. ISOLATED SHOWERS/T-STORMS WEDNESDAY
THROUGH FRIDAY...BECOMING MORE WIDELY SCATTERED ON SATURDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM TUESDAY...OUTSIDE OF LIGHT AND VARIABLE WINDS EARLY TODAY
DUE TO THE LAND BREEZE FORCING THE FRONT OFF THE COAST...EXPECT SE
TO S FLOW AT 10 KT OR LESS THROUGH THE PERIOD. SEAS ARE EXPECTED TO
RUN 2 TO 3 FT.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...HIGH PRESSURE WILL BE LOCATED WELL OFF THE
COAST BUT THERE WILL ALSO BE A SECONDARY CENTER OVER THE
SOUTHEASTERN U.S. THIS WILL KEEP WIND AND SEAS MINIMAL WITH A
PREDOMINANTLY SWRLY DIRECTION ALTHOUGH THE FLOW MAY BACK TO S OR
EVEN SE AT TIMES ESP ALONG THE IMMEDIATE COAST IN ASSOCIATION WITH
THE SEA BREEZE. AN UPPER LEVEL TROUGH MAY BE STRONG ENOUGH TO ERODE
THE STRENGTH OF BOTH SURFACE HIGHS LATER THURSDAY. A LIGHT SW WIND
WILL BE FOUND ACROSS A LARGE PART OF THE SOUTHEAST COAST WHILE THE
RELATIVELY TRANQUIL SEA STATE REMAINS UNCHANGED.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 3 AM TUESDAY...WEAK SW FLOW AHEAD OF A PREFRONTAL TROUGH WILL
VEER TO W OR EVEN NW AS THE TROUGH PASSES BY MIDDAY. NO APPRECIABLE
INCREASE IN WIND SPEED AS EXPECTED WITH THE PASSAGE OF THE WIND
SHIFT. LATE FRIDAY NIGHT THIS WILL BE FOLLOWED BY AN ACTUAL FRONTAL
PASSAGE. A FURTHER VEERING AND INCREASE IN WIND SPEED AND SEAS
EXPECTED.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MBB
NEAR TERM...RAN
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...43
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
625 AM EDT TUE AUG 20 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH MID
WEEK WITH A WEAK COLD FRONT CROSSING THE AREA LATE THURSDAY. HIGH
PRESSURE THEN BUILDS BACK INTO THE AREA FOR THE REST OF THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
A FANTASTIC TUESDAY IS ON TAP FOR TODAY. FOG OUT THERE IS LESS
WIDESPREAD THAN YESTERDAY MORNING AND IS RESTRICTED TO THE LOW
SPOTS/VALLEYS. SOME STRATOCU FLOATING AROUND ACROSS NRN OH...BUT
OTHERWISE A MOSTLY CLEAR START. HIGH PRESSURE WILL REMAIN IN
CONTROL ACROSS THE REGION. AN UPPER WAVE WILL CLOSE OFF AND CUT
OFF...REMAINING TO OUR WEST. RIGHT NOW JUST SOME HIGH CLOUD
ASSOCIATED WITH IT. NOT EXPECTING TOO MUCH TO MAKE IT TO THE I-75
CORRIDOR. OTHERWISE JUST A FEW CUMULUS THIS AFTERNOON. WILL TACK
ON A COUPLE MORE DEGREES TO YESTERDAYS HIGHS MAKING IT LOWER AND
MID 80S. MINOR CHANGES FOR THIS EARLY MORNING UPDATE.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
CONTINUED QUIET TONIGHT. MAY BE GETTING A FEW CLOUDS ENCROACH FROM
THE SOUTH OVERNIGHT AS THE UPPER LOW TO OUR WEST BEGINS TO DRIFT
TO SOUTHERN OHIO FOR WEDNESDAY. THIS UPPER LOW WILL LIKELY BE
ENOUGH TO PROVIDE FOR A LITTLE INSTABILITY. SHOWERS/TS WILL BE FAR
FROM WIDESPREAD AND WILL REMAIN IN CLOSE PROXIMITY TO THE UPPER
LOW. THEREFORE HAVE CONTINUED THE LOW PRECIP CHANCES ALONG/SOUTH
OF US 30. MID 80S WEDNESDAY. NOT OUT OF THE QUESTION THAT THERE
MAY BE AN ISOLATED SHOWER/TS WEDNESDAY NIGHT/EARLY THURSDAY ACROSS
THE EASTERN PORTION OF THE AREA WITH UPPER LOW PULLING INTO PA.
UPSTREAM A SHORTWAVE WITH MUCH OF ITS PUSH ACROSS THE NORTHERN
LAKES AND CANADA WILL ABSORB THE LINGERING LOW ACROSS WESTERN PA
THURSDAY. THIS SYSTEM WILL BRING A COLD FRONT ACROSS THURSDAY
AFTERNOON/EVENING. EXPECTING SCATTERED CONVECTION WITH THIS FRONT.
HIGH PRESSURE BUILDS ACROSS THE GREAT LAKES FOR FRIDAY. THE MODEL
TREND HAS BEEN FOR THIS HIGH TO BUILD IN WELL BRINGING DRIER AND
SOMEWHAT COOLER AIR TO THE AREA FOR FRIDAY AND PUSHING THE FRONT
SOUTH OF THE CWA. THERE IS A CHANCE THAT THE FRONT COULD BE
SLOWER...BUT WITH THE BUILDING RIDGE ACROSS THE PLAINS WOULD WANT
TO BELIEVE THAT THE HIGH WILL WIN OUT.
AFTER MILD AND SOMEWHAT HUMID CONDITIONS THURSDAY...WILL SHAVE A
FEW DEGREES OFF OF HIGHS AND BRING IN THE CLEARING FOR FRIDAY.
FRIDAY NIGHT HAS THE POTENTIAL TO BE COOL AGAIN...WITH LOWS IN THE
50S. SOME UPPER 40S NOT OUT OF THE QUESTION.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
DRY TO START WITH HIGH PRESSURE IN CONTROL AT THE SURFACE. THE
HIGH WILL MOVE SOUTHEAST ON MONDAY. DRY WEATHER FOR THE WEEKEND.
HOWEVER THE 12Z ECMWF WAS GIVING SOME QPF ON SUNDAY OVER NORTHWEST
OHIO. THE 00Z RUN WAS KEEPING THE QPF NORTH. WITH SO MUCH HIGH
PRESSURE AT THE SURFACE AND HIGH PRESSURE BUILDING IN ALOFT...KEPT
IT DRY.
FOR MONDAY AND MONDAY NIGHT SOME OF THE OLD MODEL RUNS HAD QPF WITH
SOME MOISTURE CATCHING THE AREA IN THE NORTHWEST FLOW. THE 00Z ECMWF
WAS STILL HINTING AT THIS. KEPT 20% POPS FROM THE PREVIOUS FORECAST.
CONFIDENCE IS LOW IN THIS WITH PLENTY OF RIDGING AND DRYING ALOFT
GOING ON.
TEMPERATURES WILL BE WARMING TO ABOVE NORMAL READINGS FOR THIS
PERIOD.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
A RIDGE WILL CONTINUE WEST TO EAST ACROSS THE FORECAST AREA
THROUGH THE TAF PERIOD.
AN AREA OF BROKEN CLOUDS AT 6000 FEET WAS MOVING ACROSS THE
REGION FOR THE EARLY MORNING HOURS. OTHERWISE THE TEMPERATURE AND DEW
POINT SPREADS WERE GETTING SMALLER. NOT EXPECTING THE IFR FOG AND
STRATUS TO BE AS WIDESPREAD AS IT WAS YESTERDAY...THE AIRMASS
DRIED OUT SOME ESPECIALLY ALOFT. MAINLY FOG IS EXPECTED. THE HRRR
MODEL WHICH DID A VERY GOOD JOB WITH THE STRATUS AND FOG MONDAY
MORNING. THIS MORNING THE HRRR MODEL IS NOT FORECASTING ANY MVFR
OR IFR STRATUS AND NO IFR VISIBILITIES. THIS SEEMS GOOD. MOST TAF
SITES EXCEPT CLE AND ERI WILL HAVE SOME FOG. THE BEST CHANCE FOR
SIGNIFICANT IFR CONDITIONS WILL BE CAK AND YNG...ELSEWHERE IFR FOG
WILL BE BRIEF. THE FOG WILL BURN OFF BY 10 AM AND THEN SOME
SCATTERED CUMULUS WILL DEVELOP AND DISSIPATE IN THE EVENING. A
LAKE BREEZE WILL OCCUR.
OUTLOOK ...NON-VFR POSSIBLE IN EARLY MORNING FOG WEDNESDAY THROUGH
THURSDAY AND IN THUNDERSTORMS THURSDAY AFTERNOON AND EVENING.
&&
.MARINE...
A RIDGE WILL CONTINUE OVER THE LAKE TODAY AND THEN START TO WEAKEN
ON WEDNESDAY. THE FLOW WILL BE MAINLY LIGHT WITH AN ONSHORE FLOW
DURING THE AFTERNOONS.
A SOUTHWEST FLOW WEDNESDAY NIGHT AND THURSDAY AHEAD OF A COLD FRONT
THAT WILL MOVE THROUGH DURING THE AFTERNOON. SPECIAL MARINE WARNINGS
FOR THUNDERSTORMS MAY BE NEEDED THURSDAY AFTERNOON. THE BIGGEST
QUESTION IS HOW STRONG WILL THE WINDS BE BEHIND THE COLD FRONT. IT
IS POSSIBLE THAT THE WINDS COULD PROMPT THE NEED FOR A SMALL CRAFT
ADVISORY FOR THURSDAY EVENING THROUGH DAYBREAK FRIDAY. THIS WILL
HAVE TO BE MONITORED.
HIGH PRESSURE WILL THEN BUILD OVER THE LAKE ON FRIDAY AND CONTINUE
OVER THE EASTERN LAKES THROUGH MUCH OF THE WEEKEND. THE FLOW WILL BE
NORTHEAST AT TIMES. IT DOES NOT LOOK LIKE THE WINDS WILL BE STRONG
ENOUGH TO NEED A SMALL CRAFT ADVISORY.
THE HIGH WILL MOVE EAST FOR EARLY NEXT WEEK WITH A SOUTHWEST FLOW ON
THE LAKE.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...OUDEMAN
NEAR TERM...OUDEMAN
SHORT TERM...OUDEMAN
LONG TERM...KIELTYKA
AVIATION...KIELTYKA
MARINE...KIELTYKA
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
329 AM EDT TUE AUG 20 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH MID
WEEK WITH A WEAK COLD FRONT CROSSING THE AREA LATE THURSDAY. HIGH
PRESSURE THEN BUILDS BACK INTO THE AREA FOR THE REST OF THE WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
A FANTASTIC TUESDAY IS ON TAP FOR TODAY. FOG OUT THERE IS LESS
WIDESPREAD THAN YESTERDAY MORNING AND IS RESTRICTED TO THE LOW
SPOTS/VALLEYS. SOME STRATOCU FLOATING AROUND FROM SANDUSKY TO
UPPER SANDUSKY...BUT OTHERWISE A MOSTLY CLEAR START. HIGH PRESSURE
WILL REMAIN IN CONTROL ACROSS THE REGION. AN UPPER WAVE WILL CLOSE
OFF AND CUT OFF...REMAINING TO OUR WEST. RIGHT NOW JUST SOME HIGH
CLOUD ASSOCIATED WITH IT. NOT EXPECTING TOO MUCH TO MAKE IT TO THE
I-75 CORRIDOR. OTHERWISE JUST A FEW CUMULUS THIS AFTERNOON. WILL
TACK ON A COUPLE MORE DEGREES TO YESTERDAYS HIGHS MAKING IT LOWER
AND MID 80S.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
CONTINUED QUIET TONIGHT. MAY BE GETTING A FEW CLOUDS ENCROACH FROM
THE SOUTH OVERNIGHT AS THE UPPER LOW TO OUR WEST BEGINS TO DRIFT
TO SOUTHERN OHIO FOR WEDNESDAY. THIS UPPER LOW WILL LIKELY BE
ENOUGH TO PROVIDE FOR A LITTLE INSTABILITY. SHOWERS/TS WILL BE FAR
FROM WIDESPREAD AND WILL REMAIN IN CLOSE PROXIMITY TO THE UPPER
LOW. THEREFORE HAVE CONTINUED THE LOW PRECIP CHANCES ALONG/SOUTH
OF US 30. MID 80S WEDNESDAY. NOT OUT OF THE QUESTION THAT THERE
MAY BE AN ISOLATED SHOWER/TS WEDNESDAY NIGHT/EARLY THURSDAY ACROSS
THE EASTERN PORTION OF THE AREA WITH UPPER LOW PULLING INTO PA.
UPSTREAM A SHORTWAVE WITH MUCH OF ITS PUSH ACROSS THE NORTHERN
LAKES AND CANADA WILL ABSORB THE LINGERING LOW ACROSS WESTERN PA
THURSDAY. THIS SYSTEM WILL BRING A COLD FRONT ACROSS THURSDAY
AFTERNOON/EVENING. EXPECTING SCATTERED CONVECTION WITH THIS FRONT.
HIGH PRESSURE BUILDS ACROSS THE GREAT LAKES FOR FRIDAY. THE MODEL
TREND HAS BEEN FOR THIS HIGH TO BUILD IN WELL BRINGING DRIER AND
SOMEWHAT COOLER AIR TO THE AREA FOR FRIDAY AND PUSHING THE FRONT
SOUTH OF THE CWA. THERE IS A CHANCE THAT THE FRONT COULD BE
SLOWER...BUT WITH THE BUILDING RIDGE ACROSS THE PLAINS WOULD WANT
TO BELIEVE THAT THE HIGH WILL WIN OUT.
AFTER MILD AND SOMEWHAT HUMID CONDITIONS THURSDAY...WILL SHAVE A
FEW DEGREES OFF OF HIGHS AND BRING IN THE CLEARING FOR FRIDAY.
FRIDAY NIGHT HAS THE POTENTIAL TO BE COOL AGAIN...WITH LOWS IN THE
50S. SOME UPPER 40S NOT OUT OF THE QUESTION.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
DRY TO START WITH HIGH PRESSURE IN CONTROL AT THE SURFACE. THE
HIGH WILL MOVE SOUTHEAST ON MONDAY. DRY WEATHER FOR THE WEEKEND.
HOWEVER THE 12Z ECMWF WAS GIVING SOME QPF ON SUNDAY OVER NORTHWEST
OHIO. THE 00Z RUN WAS KEEPING THE QPF NORTH. WITH SO MUCH HIGH
PRESSURE AT THE SURFACE AND HIGH PRESSURE BUILDING IN ALOFT...KEPT
IT DRY.
FOR MONDAY AND MONDAY NIGHT SOME OF THE OLD MODEL RUNS HAD QPF WITH
SOME MOISTURE CATCHING THE AREA IN THE NORTHWEST FLOW. THE 00Z ECMWF
WAS STILL HINTING AT THIS. KEPT 20% POPS FROM THE PREVIOUS FORECAST.
CONFIDENCE IS LOW IN THIS WITH PLENTY OF RIDGING AND DRYING ALOFT
GOING ON.
TEMPERATURES WILL BE WARMING TO ABOVE NORMAL READINGS FOR THIS
PERIOD.
&&
.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
A RIDGE WILL CONTINUE WEST TO EAST ACROSS THE FORECAST AREA
THROUGH THE TAF PERIOD.
AN AREA OF BROKEN CLOUDS AT 6000 FEET WAS MOVING ACROSS THE
REGION FOR THE EARLY MORNING HOURS. OTHERWISE THE TEMPERATURE AND DEW
POINT SPREADS WERE GETTING SMALLER. NOT EXPECTING THE IFR FOG AND
STRATUS TO BE AS WIDESPREAD AS IT WAS YESTERDAY...THE AIRMASS
DRIED OUT SOME ESPECIALLY ALOFT. MAINLY FOG IS EXPECTED. THE HRRR
MODEL WHICH DID A VERY GOOD JOB WITH THE STRATUS AND FOG MONDAY
MORNING. THIS MORNING THE HRRR MODEL IS NOT FORECASTING ANY MVFR
OR IFR STRATUS AND NO IFR VISIBILITIES. THIS SEEMS GOOD. MOST TAF
SITES EXCEPT CLE AND ERI WILL HAVE SOME FOG. THE BEST CHANCE FOR
SIGNIFICANT IFR CONDITIONS WILL BE CAK AND YNG...ELSEWHERE IFR FOG
WILL BE BRIEF. THE FOG WILL BURN OFF BY 10 AM AND THEN SOME
SCATTERED CUMULUS WILL DEVELOP AND DISSIPATE IN THE EVENING. A
LAKE BREEZE WILL OCCUR.
OUTLOOK ...NON-VFR POSSIBLE IN EARLY MORNING FOG WEDNESDAY THROUGH
THURSDAY AND IN THUNDERSTORMS THURSDAY AFTERNOON AND EVENING.
&&
.MARINE...
A RIDGE WILL CONTINUE OVER THE LAKE TODAY AND THEN START TO WEAKEN
ON WEDNESDAY. THE FLOW WILL BE MAINLY LIGHT WITH AN ONSHORE FLOW
DURING THE AFTERNOONS.
A SOUTHWEST FLOW WEDNESDAY NIGHT AND THURSDAY AHEAD OF A COLD FRONT
THAT WILL MOVE THROUGH DURING THE AFTERNOON. SPECIAL MARINE WARNINGS
FOR THUNDERSTORMS MAY BE NEEDED THURSDAY AFTERNOON. THE BIGGEST
QUESTION IS HOW STRONG WILL THE WINDS BE BEHIND THE COLD FRONT. IT
IS POSSIBLE THAT THE WINDS COULD PROMPT THE NEED FOR A SMALL CRAFT
ADVISORY FOR THURSDAY EVENING THROUGH DAYBREAK FRIDAY. THIS WILL
HAVE TO BE MONITORED.
HIGH PRESSURE WILL THEN BUILD OVER THE LAKE ON FRIDAY AND CONTINUE
OVER THE EASTERN LAKES THROUGH MUCH OF THE WEEKEND. THE FLOW WILL BE
NORTHEAST AT TIMES. IT DOES NOT LOOK LIKE THE WINDS WILL BE STRONG
ENOUGH TO NEED A SMALL CRAFT ADVISORY.
THE HIGH WILL MOVE EAST FOR EARLY NEXT WEEK WITH A SOUTHWEST FLOW ON
THE LAKE.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...OUDEMAN
NEAR TERM...OUDEMAN
SHORT TERM...OUDEMAN
LONG TERM...KIELTYKA
AVIATION...KIELTYKA
MARINE...KIELTYKA
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
203 AM EDT TUE AUG 20 2013
.SYNOPSIS...
SURFACE HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH MID
WEEK WITH A WEAK COLD FRONT CROSSING THE AREA LATE THURSDAY. HIGH
PRESSURE THEN BUILDS BACK INTO THE AREA FOR THE REST OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
SKIES CLEARED OUT ACROSS THE FORECAST AREA THIS EVENING WITH
SUNSET AS DIURNAL CUMULUS DISSIPATED. MODELS AND SATELLITE IMAGERY
INDICATE SHORTWAVE TROUGH MOVING EAST ACROSS ILLINOIS WILL HEAD
OUR WAY OVERNIGHT. HOWEVER...IT APPEARS THIS FEATURE WILL CONTINUE
TO WEAKEN WITH TIME. SOME CLOUDS ASSOCIATED WITH THE FEATURE WILL
APPROACH THE FORECAST AREA TOWARD MORNING. FAIR WEATHER WILL BE
THE RULE THROUGH THE NIGHT. SO LITTLE CHANGE EXPECTED WITH THIS
PACKAGE.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/...
HIGH PRESSURE WILL WEAKEN ON TUESDAY AS ANOTHER PIECE OF JET
ENERGY DIGS INTO THE UPPER LEVEL TROUGH THAT PERSISTS OVER THE
REGION. AS ANOTHER AREA OF WEAK MIDDLE LEVEL LOW PRESSURE DEVELOPS
OVER SOUTHERN OHIO IT WILL INCREASE THE INSTABILITY ACROSS THE
COUNTY WARNING AREA. THE CHANCES OF SHOWERS...MAYBE SOME
THUNDER...WILL INCREASE ACROSS THE SOUTH AND WEST WEDNESDAY
AFTERNOON THEN GRADUALLY SPREAD ACROSS THE EASTERN HALF OF THE
AREA WEDNESDAY EVENING THROUGH THE OVERNIGHT. THIS UPPER LOW MAY
CONTINUE TO KEEP LOW CHANCES OF RAIN ACROSS EASTERN OHIO AND
WESTERN PA INTO THURSDAY BUT THE UPPER LOW WELL GET A NUDGE FROM A
COLD FRONT THAT WILL ATTEMPT TO MOVE INTO NW OHIO AND SOUTHERN
ONTARIO BY THURSDAY AFTERNOON. THIS FRONT SHOULD BE SOUTH OF THE
COUNTY WARNING AREA BY FRIDAY MORNING. HOWEVER THERE IS CONCERN
THAT THE WEAKENING FRONT MAY MOVE THROUGH SLOWER THAN ANTICIPATED.
TEMPERATURES WILL LIKELY BE ABOVE AVERAGE TUESDAY INTO WEDNESDAY
BEFORE INCREASING CLOUD COVER ON THURSDAY TRIMS A COUPLE DEGREES.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
SURFACE HIGH PRESSURE WILL TAKE CONTROL ON FRIDAY WITH HIGHS NEAR
SEASONAL LEVELS.
THE MODELS DIFFER ON SOME OF THE WEAKER FEATURES DURING THE PERIOD.
IN GENERAL...THERE SHOULD BE A SMALL THREAT FOR SHRA AND TSRA AS
WEAK UPPER TROFS DIVE SE ACROSS THE LERI AREA WHILE A SURFACE
BOUNDARY MAY SET UP NEAR LERI. INITIALLY THE SURFACE HIGH WILL
STILL BE IN CONTROL ON SAT WITH FAIRLY DRY AIR SO WILL HOLD OFF
ANY THREAT FOR PRECIP ON SAT THEN SLOWLY ALLOW THE POP TO INCREASE
SOME SUN INTO MON AS INCREASING MOISTURE SHOULD RETURN TO THE AREA.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
A RIDGE WILL CONTINUE WEST TO EAST ACROSS THE FORECAST AREA
THROUGH THE TAF PERIOD.
AN AREA OF BROKEN CLOUDS AT 6000 FEET WAS MOVING ACROSS THE
REGION FOR THE EARLY MORNING HOURS. OTHERWISE THE TEMPERATURE AND DEW
POINT SPREADS WERE GETTING SMALLER. NOT EXPECTING THE IFR FOG AND
STRATUS TO BE AS WIDESPREAD AS IT WAS YESTERDAY...THE AIRMASS
DRIED OUT SOME ESPECIALLY ALOFT. MAINLY FOG IS EXPECTED. THE HRRR
MODEL WHICH DID A VERY GOOD JOB WITH THE STRATUS AND FOG MONDAY
MORNING. THIS MORNING THE HRRR MODEL IS NOT FORECASTING ANY MVFR
OR IFR STRATUS AND NO IFR VISIBILITIES. THIS SEEMS GOOD. MOST TAF
SITES EXCEPT CLE AND ERI WILL HAVE SOME FOG. THE BEST CHANCE FOR
SIGNIFICANT IFR CONDITIONS WILL BE CAK AND YNG...ELSEWHERE IFR FOG
WILL BE BRIEF. THE FOG WILL BURN OFF BY 10 AM AND THEN SOME
SCATTERED CUMULUS WILL DEVELOP AND DISSIPATE IN THE EVENING. A
LAKE BREEZE WILL OCCUR.
OUTLOOK ...NON-VFR POSSIBLE IN EARLY MORNING FOG WEDNESDAY THROUGH
THURSDAY AND IN THUNDERSTORMS THURSDAY AFTERNOON AND EVENING.
&&
.MARINE...
HIGH PRESSURE IN CONTROL OF THE REGION WILL KEEP WINDS MAINLY UNDER
15 KNOTS THRU SAT. A COLD FRONT CROSSING THE LAKE THU MAY BRIEFLY
KICK WINDS UP TO 10 TO 20 KNOTS OUT OF THE SW AHEAD OF THE FRONT
THEN WINDS TURN NORTH AND SHOULD SETTLE BACK INTO A 5 TO 15 KNOT
RANGE BY FRI BEFORE TURNING EAST FOR SAT.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...MULLEN
NEAR TERM...LOMBARDY
SHORT TERM...MULLEN
LONG TERM...ADAMS
AVIATION...KIELTYKA
MARINE...ADAMS
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
707 AM EDT TUE AUG 20 2013
.SYNOPSIS...
HIGH PRESSURE OFF OF THE EAST COAST WILL CONTROL THE WEATHER
ACROSS PA THROUGH MIDWEEK. A COLD FRONT WILL PUSH THROUGH THE
REGION LATE THURSDAY OR EARLY FRIDAY. CANADIAN HIGH PRESSURE WILL
THEN BUILD SOUTHEAST INTO PENNSYLVANIA NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MODIS 11-3.7UM IMAGERY SHOWING WIDESPREAD VALLEY FOG ACROSS
CENTRAL PA EARLY THIS AM. MANY LOCATIONS AOB 1/4SM VSBY AT
09Z...SO HAVE ISSUED A DENSE FOG ADVISORY THRU 13Z. 3KM HRRR SFC
RH SUGGESTS THE FOG WILL BURN OFF IN MANY LOCATIONS BY ARND
12Z...BUT WILL LIKELY LINGER IN A FEW LOCATIONS UNTIL 14Z.
LARGE SCALE SUBSIDENCE UNDER HIGH PRESSURE SHOULD ENSURE ABUNDANT
SUNSHINE LATER TODAY WITH A RETURN TO MORE SUMMER-LIKE CONDITIONS.
ENS MEAN 8H TEMPS NR 16C SHOULD SUPPORT HIGH TEMPS IN THE 80S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
CLEAR SKIES AND A CALM WIND UNDER SFC HIGH SHOULD RESULT IN LATE
NIGHT VALLEY FOG AGAIN TONIGHT. HOWEVER...RH/S WILL BE MUCH LOWER
GOING INTO THE EVENING HRS...SO EXPECT THE DENSE FOG TO BE ISOLATED
TO THE DEEP RIVER/STREAM VALLEYS OF THE ALLEGHENIES.
SFC HIGH WILL RETREAT OFF THE E COAST ON WED AND CUT-OFF UPPER
LOW...CURRENTLY OVR ILLINOIS...WILL BE LIFTING UP THE OHIO VALLEY
TOWARD PA. LG SCALE FORCING AND INCREASINGLY MOIST SOUTHERLY FLOW
AHEAD OF THIS FEATURE COULD RESULT IN A FEW LATE DAY SHRA/TSRA
ACROSS THE SOUTHERN COUNTIES. TEMPS/HUMIDITY WILL CONTINUE TO
CREEP UP...WITH AFTN READINGS LIKELY RANGING FROM THE L80S OVR THE
ALLEGHENY PLATEAU...TO THE U80S IN THE SUSQ VALLEY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
LITTLE SPREAD NOTED AMONG 00Z MED RANGE GUIDANCE...ALL OF WHICH
SHOW UPPER LOW OPENING UP AS IT LIFTS INTO PA WED NIGHT AND
THURSDAY. THIS WEAKENING SHORTWAVE THEN MERGES WITH MAIN BRANCH OF
JET AS IT AND ASSOC COLD FRONT DIVE SE INTO PA LATE THURSDAY. BASED
ON THIS SCENARIO...HAVE INTRODUCED A CHC OF SHRA/TSRA WED NITE
ACROSS THE SOUTH AND THE ENTIRE AREA BY THU PM.
WIDESPREAD AGREEMENT AMONG MED RANGE GUIDANCE THAT CENTRAL PA WILL
SEE A RETURN TO COOLER/LESS HUMID CONDS FRI-SUN...AS CANADIAN
HIGH PRES AND ASSOC NEGATIVE PWAT ANOMALIES BUILD SE INTO PA. HAVE
REDUCED MIN TEMPS NEXT WEEKEND GIVEN THE POTENTIAL OF RAD COOLING.
HOWEVER...ECMWF ENS MEAN 8H TEMPS NR 12C SHOULD RESULT IN DAYTIME
HIGHS NR LATE AUGUST NORMALS. BY LATE SUNDAY OR MONDAY...SFC HIGH
WILL LIKELY PASS SOUTH OF PA...BRINGING RETURN SW FLOW OF
WARMER/MORE HUMID CONDS AND THE CHC OF CONVECTION ON EASTERN
PERIPHERY OF BUILDING UPPER LVL RIDGE OVR THE MIDWEST.
&&
.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
HIGH PRESSURE WILL CONTROL THE WEATHER ACROSS PA THIS MIDWEEK.
WIDESPREAD DENSE VALLEY FOG ACROSS CENTRAL PA EARLY THIS MORNING
AS STRONG RADIATIONAL COOLING BROUGHT TEMPS DOWN TO THE DEWPOINTS.
AN AREA FROM KUNV-KIPT REMAINED MVFR WHILE REMAINDER OF TAF SITES
SLIPPED TO VLIFR. THE FOG /ASSOCIATED LOW CLOUDS WHEN IT LIFTS/ WILL
BE STUBBORN FOR ANOTHER HOUR OR TWO /13-14Z/ BEFORE RAPID
IMPROVEMENT BRINGS CONDITIONS UP TO VFR AREAWIDE. WINDS WILL BE
LIGHT FROM THE WEST AND LARGE SCALE SUBSIDENCE WILL KEEP CLOUDS TO
A MINIMUM.
FOG RETURNS AGAIN LATE TONIGHT...BUT WITH RH LOWER THIS EVE FOG
WILL NOT BE AS WIDESPREAD AND THICK AS THIS MORNING /CONFINED
MAINLY TO THE VALLEYS/...BEFORE GIVING WAY TO ANOTHER WIDESPREAD
VFR DAY ON WED.
OUTLOOK...
WED-THU...VFR.
FRI...MVFR WITH SCT SHRA/TSRA.
SAT...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR PAZ004>006-
010>012-017>019-024>028-033>037-041-042-045-046-049>053-
056>059-063>066.
&&
$$
SYNOPSIS...FITZGERALD
NEAR TERM...FITZGERALD
SHORT TERM...FITZGERALD
LONG TERM...FITZGERALD
AVIATION...RXR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
601 AM EDT TUE AUG 20 2013
.SYNOPSIS...
HIGH PRESSURE OFF OF THE EAST COAST WILL CONTROL THE WEATHER
ACROSS PA THROUGH MIDWEEK. A COLD FRONT WILL PUSH THROUGH THE
REGION LATE THURSDAY OR EARLY FRIDAY. CANADIAN HIGH PRESSURE WILL
THEN BUILD SOUTHEAST INTO PENNSYLVANIA NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MODIS 11-3.7UM IMAGERY SHOWING WIDESPREAD VALLEY FOG ACROSS
CENTRAL PA EARLY THIS AM. MANY LOCATIONS AOB 1/4SM VSBY AT
09Z...SO HAVE ISSUED A DENSE FOG ADVISORY THRU 13Z. 3KM HRRR SFC
RH SUGGESTS THE FOG WILL BURN OFF IN MANY LOCATIONS BY ARND
12Z...BUT WILL LIKELY LINGER IN A FEW LOCATIONS UNTIL 14Z.
LARGE SCALE SUBSIDENCE UNDER HIGH PRESSURE SHOULD ENSURE ABUNDANT
SUNSHINE LATER TODAY WITH A RETURN TO MORE SUMMER-LIKE CONDITIONS.
ENS MEAN 8H TEMPS NR 16C SHOULD SUPPORT HIGH TEMPS IN THE 80S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
CLEAR SKIES AND A CALM WIND UNDER SFC HIGH SHOULD RESULT IN LATE
NIGHT VALLEY FOG AGAIN TONIGHT. HOWEVER...RH/S WILL BE MUCH LOWER
GOING INTO THE EVENING HRS...SO EXPECT THE DENSE FOG TO BE ISOLATED
TO THE DEEP RIVER/STREAM VALLEYS OF THE ALLEGHENIES.
SFC HIGH WILL RETREAT OFF THE E COAST ON WED AND CUT-OFF UPPER
LOW...CURRENTLY OVR ILLINOIS...WILL BE LIFTING UP THE OHIO VALLEY
TOWARD PA. LG SCALE FORCING AND INCREASINGLY MOIST SOUTHERLY FLOW
AHEAD OF THIS FEATURE COULD RESULT IN A FEW LATE DAY SHRA/TSRA
ACROSS THE SOUTHERN COUNTIES. TEMPS/HUMIDITY WILL CONTINUE TO
CREEP UP...WITH AFTN READINGS LIKELY RANGING FROM THE L80S OVR THE
ALLEGHENY PLATEAU...TO THE U80S IN THE SUSQ VALLEY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
LITTLE SPREAD NOTED AMONG 00Z MED RANGE GUIDANCE...ALL OF WHICH
SHOW UPPER LOW OPENING UP AS IT LIFTS INTO PA WED NIGHT AND
THURSDAY. THIS WEAKENING SHORTWAVE THEN MERGES WITH MAIN BRANCH OF
JET AS IT AND ASSOC COLD FRONT DIVE SE INTO PA LATE THURSDAY. BASED
ON THIS SCENARIO...HAVE INTRODUCED A CHC OF SHRA/TSRA WED NITE
ACROSS THE SOUTH AND THE ENTIRE AREA BY THU PM.
WIDESPREAD AGREEMENT AMONG MED RANGE GUIDANCE THAT CENTRAL PA WILL
SEE A RETURN TO COOLER/LESS HUMID CONDS FRI-SUN...AS CANADIAN
HIGH PRES AND ASSOC NEGATIVE PWAT ANOMALIES BUILD SE INTO PA. HAVE
REDUCED MIN TEMPS NEXT WEEKEND GIVEN THE POTENTIAL OF RAD COOLING.
HOWEVER...ECMWF ENS MEAN 8H TEMPS NR 12C SHOULD RESULT IN DAYTIME
HIGHS NR LATE AUGUST NORMALS. BY LATE SUNDAY OR MONDAY...SFC HIGH
WILL LIKELY PASS SOUTH OF PA...BRINGING RETURN SW FLOW OF
WARMER/MORE HUMID CONDS AND THE CHC OF CONVECTION ON EASTERN
PERIPHERY OF BUILDING UPPER LVL RIDGE OVR THE MIDWEST.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
HIGH PRESSURE CENTERED NEAR BERMUDA WILL CONTROL THE WEATHER
ACROSS PA THIS MIDWEEK.
DWPT DEPRESSIONS RUNNING BTWN 0-3F ACROSS CENTRAL PA AND
ADDITIONAL RADIATIONAL COOLING WILL RESULT IN WIDESPREAD FOG EARLY
THIS MORNING. SOME OF THE FOG WILL BE DENSE...ESP IN THE DEEP
VALLEYS OF THE ALLEGHENIES AND WHERE THERE WAS RAINFALL YESTERDAY.
THE FOG AND ASSOCIATED LOW CLOUDS WILL BEGIN TO BURN-OFF SHORTLY
AFTER SUNRISE. THOUGH MVFR MAY LINGER INTO THE MID MORNING...THE
REMAINDER OF THE DAY WILL BE VFR.
FOG RETURNS FOR LATE TUE NIGHT...THOUGH NOT AS WIDESPREAD AND
THICK AS THIS MORNING.
OUTLOOK...
WED-THU...VFR.
FRI...MVFR WITH SCT SHRA/TSRA.
SAT...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR PAZ004>006-
010>012-017>019-024>028-033>037-041-042-045-046-049>053-
056>059-063>066.
&&
$$
SYNOPSIS...FITZGERALD
NEAR TERM...FITZGERALD
SHORT TERM...FITZGERALD
LONG TERM...FITZGERALD
AVIATION...RXR
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
626 AM CDT TUE AUG 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 351 AM CDT TUE AUG 20 2013
MAIN FORECAST CONCERNS ARE ON THUNDERSTORM CHANCES WEDNESDAY INTO
THURSDAY AND HIGH TEMPERATURES LATE IN THE WEEKEND INTO EARLY NEXT
WEEK.
LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED A
SHORTWAVE TROUGH OVER SOUTHERN WISCONSIN AND NORTHERN
ILLINOIS...DRIFTING SOUTH. RIDGING WAS MOVING INTO THE UPPER
MISSISSIPPI RIVER VALLEY PROVIDING MOSTLY CLEAR TO PARTLY CLOUDY
SKIES AND QUIET CONDITIONS OVER THE AREA. SURFACE OBSERVATIONS
SHOWED A COLD FRONT EXTENDING FROM SOUTHERN MANITOBA THROUGH
WESTERN NORTH DAKOTA INTO EASTERN WYOMING WITH A BROAD HIGH
CENTERED OVER THE OHIO RIVER VALLEY. THE FORECAST AREA IS LOCATED
BETWEEN THESE TWO FEATURES WITH WARM SOUTHERLY FLOW ACROSS THE
REGION.
THE SHORTWAVE TROUGH WILL CLOSE INTO A WEAK UPPER LOW OVER ILLINOIS
TODAY. MEANWHILE...THE COLD FRONT WILL DRIFT SOUTHEAST AND BY LATE
THIS AFTERNOON IS EXPECTED TO STRETCH FROM NORTHWEST MINNESOTA
THROUGH EASTERN NORTH DAKOTA INTO CENTRAL SOUTH DAKOTA. THE UPPER
LEVEL RIDGING SHOULD WIN OUT TODAY PROVIDING PARTLY TO MOSTLY
SUNNY SKIES. INTERESTING TO NOTE THAT AFTERNOON MLCAPE VALUES
CLIMB TO 2500 TO 3500 J/KG THIS AFTERNOON ACROSS MUCH OF THE
FORECAST AREA. WITHOUT ANY REAL TRIGGER TO GET CONVECTION TO FIRE
THINKING THE AREA SHOULD REMAIN DRY THROUGH THE DAY. WILL HAVE TO
KEEP A CLOSE EYE ON THE POTENTIAL FOR AN ISOLATED SHOWER OR STORM
UNDER PEAK HEATING LATE THIS AFTERNOON. PLAN ON HIGH TEMPERATURES
CLIMBING INTO THE UPPER 80S TO AROUND 90. THE COLD FRONT WILL
CONTINUE ITS SOUTHEAST MOVEMENT TONIGHT INTO WEDNESDAY MORNING.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 351 AM CDT TUE AUG 20 2013
THE COLD FRONT WILL BE POSITIONED FROM FAR NORTHWEST WISCONSIN INTO
EXTREME NORTHWEST IOWA EARLY WEDNESDAY MORNING. FORECAST MODELS ARE
SHOWING SOME DIFFERENCES ON WHEN THE FRONT WILL MOVE INTO THE
FORECAST AREA. THE NAM OFFERS THE FASTEST SOLUTION BRINGING THE
FRONT INTO THE FORECAST AREA LATE WEDNESDAY MORNING...SHIFTING
SOUTH OF THE INTERSTATE 90 CORRIDOR WEDNESDAY EVENING AND STALLING
OVER NORTHERN IOWA/ILLINOIS. THE ECMWF HAS THE SLOWEST SOLUTION
AND DOESN/T BRING THE FRONT INTO THE FORECAST AREA UNTIL WEDNESDAY
EVENING. THE ECMWF SOLUTION SUGGESTS THAT A SHORTWAVE WILL TRIGGER
SHOWERS AND STORMS OVER NORTHWEST WISCONSIN WEDNESDAY
AFTERNOON...SPREADING SOUTHEAST DURING THE LATE AFTERNOON AND
EVENING HOURS. SHOWERS AND STORMS THEN FIRE ALONG THE FRONT
THROUGH THE OVERNIGHT HOURS WITH THE FRONT FINALLY PUSHING SOUTH
OF THE AREA BY EARLY THURSDAY AFTERNOON. THERE REMAINS TIMING
ISSUES TO WORK OUT...BUT THINKING THERE REMAINS A CHANCE OF SEEING
SEVERE THUNDERSTORMS ON WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT.
0-6KM BULK SHEAR IS THE MOST FAVORABLE FOR SEVERE STORMS OVER
NORTH CENTRAL WISCONSIN...WHERE VALUES RANGE FROM 30 TO 40 KTS.
PLENTY OF INSTABILITY TO WORK WITH AHEAD OF THE FRONT WITH MLCAPE
VALUES CLIMBING TO AROUND 2000 J/KG. THE MAIN THREATS FROM THE
STORMS WILL BE LARGE HAIL AND DAMAGING WINDS. SHEAR IS VERY
MARGINAL AT BEST OVER SOUTHEAST MINNESOTA...NORTHEAST IOWA...AND
SOUTHWEST WISCONSIN...BUT THINKING THE STRONG INSTABILITY WILL BE
ENOUGH TO OVERCOME THE LACK OF STRONG SHEAR. THE FRONT FINALLY
SHIFTS SOUTH OF THE AREA LATE ON THURSDAY AS HIGH PRESSURE BUILDS
IN. THE FRONT ATTEMPTS TO LIFT NORTH AS A WARM FRONT ON FRIDAY
GENERATING SOME SHOWERS AND STORMS ALONG IT. LATEST GUIDANCE
SUGGESTS THAT THE FRONT WASHES OUT AS A SURFACE HIGH HOLDS STRONG
OVER THE WESTERN GREAT LAKES. UPPER RIDGE THEN BUILDS OVER THE
REGION SATURDAY INTO SUNDAY WITH WARMING TEMPERATURES EXPECTED.
WILL HAVE TO KEEP A CLOSE EYE ON SHORTWAVES ROTATING THROUGH THE
NORTHERN PERIPHERY OF THE RIDGE OVER NORTHERN WISCONSIN WHERE
SHOWERS STORMS WILL BE POSSIBLE. 850 MB STANDARDIZED ANOMALIES
CLIMB TO PLUS 2 ON SUNDAY...SUGGESTING THE POTENTIAL FOR NEAR
RECORD HIGH TEMPERATURES. 925 MB TEMPERATURES WARM TO 28 C ON
SUNDAY BEFORE ANOTHER COLD FRONT SLIPS SOUTH THROUGH THE REGION ON
MONDAY. HIGHS ON SUNDAY AND MONDAY SHOULD CLIMB INTO THE UPPER 80S
TO LOWER 90S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 626 AM CDT TUE AUG 20 2013
VFR CONDITIONS ARE EXPECTED THROUGH TOMORROW MORNING WITH SOME
5-8KFT ALTOCUMULUS TO CONTEND WITH TODAY. A PASSING MID LEVEL
TROUGH IS AIDING IN THE DEVELOPMENT OF THIS BKN TO OVC MID LEVEL
DECK THAT EXTENDS FROM NORTHERN WISCONSIN DOWN THROUGH IOWA. WINDS
WILL BE ON THE INCREASE OUT OF THE SOUTH-SOUTHWEST TODAY AS THE
PRESSURE GRADIENT CONTINUES TO TIGHTEN UP ACROSS THE REGION.
EXPECT GUSTS OF 16-20KTS LATER THIS MORNING ON INTO THE AFTERNOON.
SKIES WILL CLEAR BY TONIGHT AS DRIER UPPER LEVEL AIR MOVES IN
FROM THE NORTH.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
315 PM MST TUE AUG 20 2013
.UPDATE...TO AVIATION DISCUSSION...
&&
.SYNOPSIS...
STRONG HIGH PRESSURE ALOFT WILL KEEP TEMPERATURES WELL ABOVE NORMAL
ACROSS THE REGION THROUGH WEDNESDAY. TEMPERATURES WILL THEN SLOWLY
FALL FROM THURSDAY ONWARD INTO THE UPCOMING WEEKEND AS THE HIGH
PRESSURE WEAKENS. THUNDERSTORM ACTIVITY WILL BE MAINLY CONFINED TO
THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX THROUGH FRIDAY...THEN
INCREASE DRAMATICALLY FROM SATURDAY ONWARD INTO EARLY NEXT WEEK AS
DEEP SOUTHERLY FLOW ALOFT DEVELOPS OVER THE REGION...WHICH WILL THEN
BEGIN TO IMPORT DEEP MOISTURE NORTHWARD INTO THE DESERT SOUTHWEST.
&&
.DISCUSSION...
LATEST RAP SHOWS AN ELONGATED RIDGE STRETCHING FROM SOUTHERN AZ
TOWARDS THE FOUR CORNERS WITH EMBEDDED ANTICYCLONIC VORTICITY ACROSS
SOUTH-CENTRAL AZ. MEANWHILE...SURFACE DEWPOINTS CONTINUE TO MIX OUT
AND HAVE DROPPED INTO THE LOWER 50S IN THE PHOENIX AREA AND INTO THE
UPPER 40S AT YUMA. CONVECTION HAS INITIATED THIS AFTERNOON ACROSS
SOUTHERN GILA COUNTY...BUT HAS MAINLY BEEN DRIVEN BY OROGRAPHIC
CONVERGENCE...PARTICULARLY NEAR PINAL PEAK AND THE SKY ISLANDS OF SE
AZ INCLUDING MOUNT LEMMON. HIGHEST COVERAGE OF STORMS IS EXPECTED IN
THESE AREAS LATE THIS AFTERNOON AND THIS EVENING...HOWEVER WEAK
STEERING FLOW ASSOCIATED WITH THE ANTICYCLONE WILL MAKE IT
UNFAVORABLE FOR CELLS TO REACH THE LOWER DESERTS. POPS REMAIN LESS
THAN 10 PERCENT FOR THE PHOENIX AREA.
THIS WEEKEND...LATEST GFS/ECMWF CONTINUE TO INDICATE THAT DEEPER
MOISTURE WILL BE ADVECTED INTO THE DESERT SOUTHWEST AND POPS WERE
INCREASED THIS MORNING FOR THE SATURDAY-MONDAY PERIOD. ADDITIONAL
ADJUSTMENTS WERE MADE THIS AFTERNOON TO LOWER HIGH
TEMPERATURES...DUE TO THE EXPECTED CLOUDINESS AND SCATTERED
PRECIPITATION.
&&
.PREVIOUS DISCUSSION...
A VERY SLOW INCREASE IN CONVECTIVE ACTIVITY IS LIKELY FROM WEDNESDAY
ONWARD INTO FRIDAY AS LEFTOVER MOISTURE FROM THUNDERSTORMS OVER
MEXICO IS PUSHED NORTHWARD INTO THE REGION. THE MAIN CONCERN OVER
THE NEXT COUPLE OF DAYS IS THE VERY HOT TEMPERATURES. CURRENT MODEL
DATA IS FORECASTING AFTERNOON 850MB TEMPERATURES IN THE 28-30C RANGE
BOTH TODAY AND ON WEDNESDAY. THESE TEMPERATURES SUPPORT HIGHS IN THE
LOWER DESERTS IN THE 110-114F RANGE EACH DAY...WITH EXCESSIVE HEAT
CRITERIA BEING MET ACROSS THE LOWER DESERTS. TEMPERATURES SHOULD
COOL A BIT ON THURSDAY AND FRIDAY AS THE RIDGE WEAKENS...WITH 500MB
HEIGHTS FALLING FROM THE 590-592DM RANGE ON WEDNESDAY TO THE
586-588DM RANGE BY FRIDAY.
A DRAMATIC UPTICK IN THE MONSOON ACTIVITY NOW APPEARS QUITE LIKELY
FROM SATURDAY ONWARD INTO EARLY NEXT WEEK AS THE MAIN LONG-WAVE
UPPER RIDGE AXIS SHIFTS OFF TO THE EAST OVER THE CENTRAL PLAINS AND
A LONG-WAVE TROF DIGS SOUTHWARD JUST OFF THE WEST COAST. THIS
PATTERN CHANCE WILL ALLOW DEEP SOUTHERLY FLOW TO DEVELOP ALL THE WAY
FROM THE DEEP TROPICS OFF THE WEST COAST OF MEXICO NORTHWARD INTO
THE SOUTHWEST US. ATMOSPHERIC MOISTURE VALUES ARE EXPECTED TO
SHARPLY INCREASE OVER THE REGION...WITH THE ECMWF SHOWING 1000-700MB
MIXING RATIOS RISING FROM AROUND 8 G/KG ON FRIDAY TO 12-16 G/KG FROM
SUNDAY ONWARD INTO NEXT TUESDAY...WITH PWATS IN THE 1.80-2.00 INCH
RANGE. IN ADDITION...BOTH THE GFS AND ECMWF TAKE A POTENTIAL
TROPICAL CYCLONE NORTHWESTWARD ALONG OR JUST WEST OF THE WEST COAST
OF BAJA CALIFORNIA. THE COMBINATION OF THE DEEP SOUTHERLY FLOW AND
POSSIBLE TROPICAL LOW PRESSURE TO THE WEST WILL LIKELY PRODUCE THE
1ST SIGNIFICANT GULF SURGE THAT WE HAVE SEEN FOR A WHILE...LIKELY
PUSHING SFC DEWPOINTS UP WELL INTO THE 60S...OR EVEN LOWER 70S
ACROSS THE LOWER DESERTS LATE FRIDAY NIGHT OR EARLY SATURDAY...WHICH
WOULD ALLOW WIDESPREAD THUNDERSTORM ACTIVITY TO DEVELOP EACH
DAY...WITH THE POTENTIAL FOR HEAVY RAINFALL FROM THESE
STORMS...ESPECIALLY IF A TROPICAL SYSTEM DOES INDEED TRACK
NORTHWESTWARD ALONG OR NEAR BAJA CALIFORNIA. THE INCREASE IN
CLOUDS...MOISTURE...AND RAINFALL IS EXPECTED TO PUSH HIGH
TEMPERATURES DOWNWARD TO BELOW-NORMAL VALUES...PERHAPS KEEPING HIGHS
BELOW 100F AT SOME LOWER DESERT LOCATIONS ON ONE OR MORE OF THE DAYS.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...
STORM ACTIVITY EXPECTED TO STAY OUT OF THE PHX METRO TONIGHT...WITH
ISOLATED DEVELOPMENT WELL TO THE EAST AND SOUTH OF THE AREA. THERE
ARE VERY SLIGHT CHANCES OF OUTFLOW INTRUSIONS LATER IN THE
EVENING...CONFIDENCE TOO LOW TO NOT INCLUDE IN THE 18Z TAFS. BREEZY
WEST WINDS WILL PERSIST THROUGH THE EARLY EVENING BEFORE TYPICAL
EAST DRAINAGE SETS UP IN THE LATE OVERNIGHT. MID TO UPPER LEVEL
DEBRIS CLOUDS MAY LINGER OVERHEAD AOA 12 TO 15KFT AGL.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
QUITE WEATHER DAY FOR THE TERMINALS WITH PATCHES OF FEW TO SCT SKIES
LINGERING THROUGH THE EARLY EVENING. SOUTHERLY WINDS WILL PERSIST AT
KBLH...WITH WEST WINDS DEVELOPING FOR KIPL OVERNIGHT. NO WEATHER
IMPACTS TO AVIATION OPERATIONS EXPECTED FOR THE TAF PERIOD.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
SOUTHERLY FLOW BETWEEN THE MONSOON HIGH IN THE SOUTHERN PLAINS AND A
LOW PRESSURE SYSTEM ALONG THE WEST COAST WILL TRANSPORT DEEPER
MOISTURE INTO THE DESERT SOUTHWEST. LATE WEEK THROUGH THE WEEKEND
WILL SEE ABOVE NORMAL RAIN CHANCES...PARTICULARLY ACROSS
ARIZONA...ALONG WITH AT OR BELOW NORMAL TEMPERATURES. RAINFALL
AMOUNTS MAY EVEN BE ENHANCED BY INCREASING TROPICAL MOISTURE SUNDAY
AND MONDAY...MAINLY EAST OF THE COLORADO RIVER. WINDS WILL BE
RELATIVELY LIGHT THROUGH FRIDAY AND FAVOR NORMAL DIURNAL SPEEDS AND
DIRECTIONS...WITH INCREASING MAINLY SOUTHERLY WIND EXPECTED OVER THE
WESTERN DESERTS THIS WEEKEND WITH GUSTS IN EXCESS OF 25 MPH
POSSIBLE.
$$
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...EXCESSIVE HEAT WARNING UNTIL 8 PM MST WEDNESDAY
AZZ022-023-027-028.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...PERCHA
AVIATION...NOLTE
FIRE WEATHER...CB/HIRSCH
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
130 PM MST TUE AUG 20 2013
.SYNOPSIS...
STRONG HIGH PRESSURE ALOFT WILL KEEP TEMPERATURES WELL ABOVE NORMAL
ACROSS THE REGION THROUGH WEDNESDAY. TEMPERATURES WILL THEN SLOWLY
FALL FROM THURSDAY ONWARD INTO THE UPCOMING WEEKEND AS THE HIGH
PRESSURE WEAKENS. THUNDERSTORM ACTIVITY WILL BE MAINLY CONFINED TO
THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX THROUGH FRIDAY...THEN
INCREASE DRAMATICALLY FROM SATURDAY ONWARD INTO EARLY NEXT WEEK AS
DEEP SOUTHERLY FLOW ALOFT DEVELOPS OVER THE REGION...WHICH WILL THEN
BEGIN TO IMPORT DEEP MOISTURE NORTHWARD INTO THE DESERT SOUTHWEST.
&&
.DISCUSSION...
LATEST RAP SHOWS AN ELONGATED RIDGE STRETCHING FROM SOUTHERN AZ
TOWARDS THE FOUR CORNERS WITH EMBEDDED ANTICYCLONIC VORTICITY ACROSS
SOUTH-CENTRAL AZ. MEANWHILE...SURFACE DEWPOINTS CONTINUE TO MIX OUT
AND HAVE DROPPED INTO THE LOWER 50S IN THE PHOENIX AREA AND INTO THE
UPPER 40S AT YUMA. CONVECTION HAS INITIATED THIS AFTERNOON ACROSS
SOUTHERN GILA COUNTY...BUT HAS MAINLY BEEN DRIVEN BY OROGRAPHIC
CONVERGENCE...PARTICULARLY NEAR PINAL PEAK AND THE SKY ISLANDS OF SE AZ
INCLUDING MOUNT LEMMON. HIGHEST COVERAGE OF STORMS IS EXPECTED IN
THESE AREAS LATE THIS AFTERNOON AND THIS EVENING...HOWEVER WEAK
STEERING FLOW ASSOCIATED WITH THE ANTICYCLONE WILL MAKE IT
UNFAVORABLE FOR CELLS TO REACH THE LOWER DESERTS. POPS REMAIN LESS
THAN 10 PERCENT FOR THE PHOENIX AREA.
THIS WEEKEND...LATEST GFS/ECMWF CONTINUE TO INDICATE THAT DEEPER
MOISTURE WILL BE ADVECTED INTO THE DESERT SOUTHWEST AND POPS WERE
INCREASED THIS MORNING FOR THE SATURDAY-MONDAY PERIOD. ADDITIONAL
ADJUSTMENTS WERE MADE THIS AFTERNOON TO LOWER HIGH
TEMPERATURES...DUE TO THE EXPECTED CLOUDINESS AND SCATTERED
PRECIPITATION.
&&
.PREVIOUS DISCUSSION...
A VERY SLOW INCREASE IN CONVECTIVE ACTIVITY IS LIKELY FROM WEDNESDAY
ONWARD INTO FRIDAY AS LEFTOVER MOISTURE FROM THUNDERSTORMS OVER
MEXICO IS PUSHED NORTHWARD INTO THE REGION. THE MAIN CONCERN OVER
THE NEXT COUPLE OF DAYS IS THE VERY HOT TEMPERATURES. CURRENT MODEL
DATA IS FORECASTING AFTERNOON 850MB TEMPERATURES IN THE 28-30C RANGE
BOTH TODAY AND ON WEDNESDAY. THESE TEMPERATURES SUPPORT HIGHS IN THE
LOWER DESERTS IN THE 110-114F RANGE EACH DAY...WITH EXCESSIVE HEAT
CRITERIA BEING MET ACROSS THE LOWER DESERTS. TEMPERATURES SHOULD
COOL A BIT ON THURSDAY AND FRIDAY AS THE RIDGE WEAKENS...WITH 500MB
HEIGHTS FALLING FROM THE 590-592DM RANGE ON WEDNESDAY TO THE
586-588DM RANGE BY FRIDAY.
A DRAMATIC UPTICK IN THE MONSOON ACTIVITY NOW APPEARS QUITE LIKELY
FROM SATURDAY ONWARD INTO EARLY NEXT WEEK AS THE MAIN LONG-WAVE
UPPER RIDGE AXIS SHIFTS OFF TO THE EAST OVER THE CENTRAL PLAINS AND
A LONG-WAVE TROF DIGS SOUTHWARD JUST OFF THE WEST COAST. THIS
PATTERN CHANCE WILL ALLOW DEEP SOUTHERLY FLOW TO DEVELOP ALL THE WAY
FROM THE DEEP TROPICS OFF THE WEST COAST OF MEXICO NORTHWARD INTO
THE SOUTHWEST US. ATMOSPHERIC MOISTURE VALUES ARE EXPECTED TO
SHARPLY INCREASE OVER THE REGION...WITH THE ECMWF SHOWING 1000-700MB
MIXING RATIOS RISING FROM AROUND 8 G/KG ON FRIDAY TO 12-16 G/KG FROM
SUNDAY ONWARD INTO NEXT TUESDAY...WITH PWATS IN THE 1.80-2.00 INCH
RANGE. IN ADDITION...BOTH THE GFS AND ECMWF TAKE A POTENTIAL
TROPICAL CYCLONE NORTHWESTWARD ALONG OR JUST WEST OF THE WEST COAST
OF BAJA CALIFORNIA. THE COMBINATION OF THE DEEP SOUTHERLY FLOW AND
POSSIBLE TROPICAL LOW PRESSURE TO THE WEST WILL LIKELY PRODUCE THE
1ST SIGNIFICANT GULF SURGE THAT WE HAVE SEEN FOR A WHILE...LIKELY
PUSHING SFC DEWPOINTS UP WELL INTO THE 60S...OR EVEN LOWER 70S
ACROSS THE LOWER DESERTS LATE FRIDAY NIGHT OR EARLY SATURDAY...WHICH
WOULD ALLOW WIDESPREAD THUNDERSTORM ACTIVITY TO DEVELOP EACH
DAY...WITH THE POTENTIAL FOR HEAVY RAINFALL FROM THESE
STORMS...ESPECIALLY IF A TROPICAL SYSTEM DOES INDEED TRACK
NORTHWESTWARD ALONG OR NEAR BAJA CALIFORNIA. THE INCREASE IN
CLOUDS...MOISTURE...AND RAINFALL IS EXPECTED TO PUSH HIGH
TEMPERATURES DOWNWARD TO BELOW-NORMAL VALUES...PERHAPS KEEPING HIGHS
BELOW 100F AT SOME LOWER DESERT LOCATIONS ON ONE OR MORE OF THE DAYS.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...
EXPECT A BIT OF MID/UPPER LEVEL DEBRIS CLOUDS...BASES AOA 14K
FEET...INTO THE MORNING HOURS WITH SOME HIGH BASED CU DEVELOPING IN
THE AFTERNOON. THREAT FOR THUNDERSTORMS TODAY IS REDUCED...MOST
LIKELY STORMS WILL STAY OUT OF THE DESERTS AND OVER HIGHER
TERRAIN...AS SUCH NO MENTION OF THUNDER WAS MADE IN THE 12Z TAFS.
WINDS WILL AGAIN FAVOR NORMAL DIURNAL SPEEDS AND DIRECTIONS NEXT 24
HOURS.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
NO AVIATION CONCERNS NEXT 24 HOURS...STORM THREATS ARE MINIMAL.
OUTSIDE OF SOME MORNING MID/UPPER LEVEL DEBRIS CLOUD...EXPECT
RELATIVELY SUNNY SKIES TODAY. WIND SHOULD FAVOR THE WEST AT KIPL
TODAY AND THE SOUTH/SOUTHWEST AT KBLH.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
SOUTHERLY FLOW BETWEEN THE MONSOON HIGH IN THE SOUTHERN PLAINS AND A
LOW PRESSURE SYSTEM ALONG THE WEST COAST WILL TRANSPORT DEEPER
MOISTURE INTO THE DESERT SOUTHWEST. LATE WEEK THROUGH THE WEEKEND
WILL SEE ABOVE NORMAL RAIN CHANCES...PARTICULARLY ACROSS
ARIZONA...ALONG WITH AT OR BELOW NORMAL TEMPERATURES. RAINFALL
AMOUNTS MAY EVEN BE ENHANCED BY INCREASING TROPICAL MOISTURE SUNDAY
AND MONDAY...MAINLY EAST OF THE COLORADO RIVER. WINDS WILL BE
RELATIVELY LIGHT THROUGH FRIDAY AND FAVOR NORMAL DIURNAL SPEEDS AND
DIRECTIONS...WITH INCREASING MAINLY SOUTHERLY WIND EXPECTED OVER THE
WESTERN DESERTS THIS WEEKEND WITH GUSTS IN EXCESS OF 25 MPH
POSSIBLE.
$$
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...EXCESSIVE HEAT WARNING UNTIL 8 PM MST WEDNESDAY
AZZ022-023-027-028.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...PERCHA
AVIATION...CB
FIRE WEATHER...CB/HIRSCH
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
905 AM MST TUE AUG 20 2013
.SYNOPSIS...
STRONG HIGH PRESSURE ALOFT WILL KEEP TEMPERATURES WELL ABOVE NORMAL
ACROSS THE REGION THROUGH WEDNESDAY. TEMPERATURES WILL THEN SLOWLY
FALL FROM THURSDAY ONWARD INTO THE UPCOMING WEEKEND AS THE HIGH
PRESSURE WEAKENS. THUNDERSTORM ACTIVITY WILL BE MAINLY CONFINED TO
THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX THROUGH FRIDAY...THEN
INCREASE DRAMATICALLY FROM SATURDAY ONWARD INTO EARLY NEXT WEEK AS
DEEP SOUTHERLY FLOW ALOFT DEVELOPS OVER THE REGION...WHICH WILL THEN
BEGIN TO IMPORT DEEP MOISTURE NORTHWARD INTO THE DESERT SOUTHWEST.
&&
.DISCUSSION...
LATEST RAP SHOWS THE CENTER OF THE ANTICYCLONIC CIRCULATION ACROSS
SOUTH-CENTRAL AZ. LATEST BLENDED TPW INDICATES THAT RELATIVELY DRY
AIR HAS WORKED ITS WAY INTO THE SONORAN DESERT. WARM POCKET ALOFT
ASSOCIATED WITH THE HIGH WILL YIELD WEAK LAPSE RATES WHICH WILL
INHIBIT CONVECTION AND POPS WERE LOWERED ACROSS MUCH OF THE AREA.
THIS IS ALSO IN LINE WITH ALL HI-RES CONVECTIVE ALLOWING MODELS.
BIGGER STORY TODAY WILL BE THE CONTINUATION OF THE EXCESSIVE HEAT
WITH HIGH TEMPERATURES AGAIN EXCEEDING 110 DEGREES IN PHOENIX. THE
EXCESSIVE HEAT WARNING REMAINS IN EFFECT THROUGH 8 PM FOR THE
GREATER PHOENIX AREA.
GFS/ECMWF CONTINUE TO INDICATE THAT CONDITIONS WILL MOISTEN UP THIS
WEEKEND...EITHER FROM AN APPROACHING INVERTED TROUGH...A GULF
SURGE...REMNANTS OF A TROPICAL SYSTEM OR A COMBINATION OF THE THREE.
POPS WERE INCREASED FROM SATURDAY INTO EARLY NEXT WEEK AND ARE NOW
AS HIGH AS 50 PERCENT FOR SUNDAY AFTERNOON/EVENING.
&&
.PREVIOUS DISCUSSION...
THUS...NOT EXPECTING MUCH CHANGE IN THE AMOUNT OF CONVECTIVE
ACTIVITY TODAY...WITH VIRTUALLY ALL ACTIVITY TO BE CONFINED TO THE
HIGHER TERRAIN NORTH AND EAST OF PHOENIX...WITH MAYBE SOME OUTFLOWS
MAKING THEIR WAY INTO THE LOWER DESERTS THIS EVENING. A VERY SLOW
INCREASE IN CONVECTIVE ACTIVITY IS LIKELY FROM WEDNESDAY ONWARD INTO
FRIDAY AS LEFTOVER MOISTURE FROM THUNDERSTORMS OVER MEXICO IS PUSHED
NORTHWARD INTO THE REGION. THE MAIN CONCERN OVER THE NEXT COUPLE OF
DAYS IS THE VERY HOT TEMPERATURES. CURRENT MODEL DATA IS FORECASTING
AFTERNOON 850MB TEMPERATURES IN THE 28-30C RANGE BOTH TODAY AND ON
WEDNESDAY. THESE TEMPERATURES SUPPORT HIGHS IN THE LOWER DESERTS IN
THE 110-114F RANGE EACH DAY...WITH EXCESSIVE HEAT CRITERIA BEING MET
ACROSS THE LOWER DESERTS. TEMPERATURES SHOULD COOL A BIT ON THURSDAY
AND FRIDAY AS THE RIDGE WEAKENS...WITH 500MB HEIGHTS FALLING FROM
THE 590-592DM RANGE ON WEDNESDAY TO THE 586-588DM RANGE BY FRIDAY.
A DRAMATIC UPTICK IN THE MONSOON ACTIVITY NOW APPEARS QUITE LIKELY
FROM SATURDAY ONWARD INTO EARLY NEXT WEEK AS THE MAIN LONG-WAVE
UPPER RIDGE AXIS SHIFTS OFF TO THE EAST OVER THE CENTRAL PLAINS AND
A LONG-WAVE TROF DIGS SOUTHWARD JUST OFF THE WEST COAST. THIS
PATTERN CHANCE WILL ALLOW DEEP SOUTHERLY FLOW TO DEVELOP ALL THE WAY
FROM THE DEEP TROPICS OFF THE WEST COAST OF MEXICO NORTHWARD INTO
THE SOUTHWEST US. ATMOSPHERIC MOISTURE VALUES ARE EXPECTED TO
SHARPLY INCREASE OVER THE REGION...WITH THE ECMWF SHOWING 1000-700MB
MIXING RATIOS RISING FROM AROUND 8 G/KG ON FRIDAY TO 12-16 G/KG FROM
SUNDAY ONWARD INTO NEXT TUESDAY...WITH PWATS IN THE 1.80-2.00 INCH
RANGE. IN ADDITION...BOTH THE GFS AND ECMWF TAKE A POTENTIAL
TROPICAL CYCLONE NORTHWESTWARD ALONG OR JUST WEST OF THE WEST COAST
OF BAJA CALIFORNIA. THE COMBINATION OF THE DEEP SOUTHERLY FLOW AND
POSSIBLE TROPICAL LOW PRESSURE TO THE WEST WILL LIKELY PRODUCE THE
1ST SIGNIFICANT GULF SURGE THAT WE HAVE SEEN FOR A WHILE...LIKELY
PUSHING SFC DEWPOINTS UP WELL INTO THE 60S...OR EVEN LOWER 70S
ACROSS THE LOWER DESERTS LATE FRIDAY NIGHT OR EARLY SATURDAY...WHICH
WOULD ALLOW WIDESPREAD THUNDERSTORM ACTIVITY TO DEVELOP EACH
DAY...WITH THE POTENTIAL FOR HEAVY RAINFALL FROM THESE
STORMS...ESPECIALLY IF A TROPICAL SYSTEM DOES INDEED TRACK
NORTHWESTWARD ALONG OR NEAR BAJA CALIFORNIA. THE INCREASE IN
CLOUDS...MOISTURE...AND RAINFALL IS EXPECTED TO PUSH HIGH
TEMPERATURES DOWNWARD TO BELOW-NORMAL VALUES...PERHAPS KEEPING HIGHS
BELOW 100F AT SOME LOWER DESERT LOCATIONS ON ONE OR MORE OF THE DAYS.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...
EXPECT A BIT OF MID/UPPER LEVEL DEBRIS CLOUDS...BASES AOA 14K
FEET...INTO THE MORNING HOURS WITH SOME HIGH BASED CU DEVELOPING IN
THE AFTERNOON. THREAT FOR THUNDERSTORMS TODAY IS REDUCED...MOST
LIKELY STORMS WILL STAY OUT OF THE DESERTS AND OVER HIGHER
TERRAIN...AS SUCH NO MENTION OF THUNDER WAS MADE IN THE 12Z TAFS.
WINDS WILL AGAIN FAVOR NORMAL DIURNAL SPEEDS AND DIRECTIONS NEXT 24
HOURS.
SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH...
NO AVIATION CONCERNS NEXT 24 HOURS...STORM THREATS ARE MINIMAL.
OUTSIDE OF SOME MORNING MID/UPPER LEVEL DEBRIS CLOUD...EXPECT
RELATIVELY SUNNY SKIES TODAY. WIND SHOULD FAVOR THE WEST AT KIPL
TODAY AND THE SOUTH/SOUTHWEST AT KBLH.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
SOUTHERLY FLOW BETWEEN THE MONSOON HIGH IN THE SOUTHERN PLAINS AND A
LOW PRESSURE SYSTEM ALONG THE WEST COAST WILL TRANSPORT DEEPER
MOISTURE INTO THE DESERT SOUTHWEST. LATE WEEK THROUGH THE WEEKEND
WILL SEE ABOVE NORMAL RAIN CHANCES...PARTICULARLY ACROSS
ARIZONA...ALONG WITH AT OR BELOW NORMAL TEMPERATURES. RAINFALL
AMOUNTS MAY EVEN BE ENHANCED BY INCREASING TROPICAL MOISTURE SUNDAY
AND MONDAY...MAINLY EAST OF THE COLORADO RIVER. WINDS WILL BE
RELATIVELY LIGHT THROUGH FRIDAY AND FAVOR NORMAL DIURNAL SPEEDS AND
DIRECTIONS...WITH INCREASING MAINLY SOUTHERLY WIND EXPECTED OVER THE
WESTERN DESERTS THIS WEEKEND WITH GUSTS IN EXCESS OF 25 MPH
POSSIBLE.
$$
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...EXCESSIVE HEAT WARNING ACROSS THE SOUTH CENTRAL DESERTS...
AZZ022...AZ023...AZZ027...AZZ028...FROM 10 AM TODAY THROUGH 8
PM WEDNESDAY.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...PERCHA
AVIATION...CB
FIRE WEATHER...CB/HIRSCH
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
259 PM CDT TUE AUG 20 2013
.DISCUSSION...
259 PM...MAIN FORECAST CONCERN/CHALLENGES ARE PRECIP COVERAGE/
TIMING WITH A COLD FRONT LATE WEDNESDAY INTO THURSDAY. CONCERNS
INTO THE EXTENDED INCLUDE POTENTIAL FOR A PROLONG PERIOD OF VERY
WARM/HOT WEATHER EARLY/MID NEXT WEEK.
IN THE SHORT TERM...SIMILAR TO MONDAY AFTERNOON...AN AREA OF
CIRRUS ALONG WITH A SCT/BKN CU FIELD HAS LIKELY HINDERED HIGH
TEMPS A DEGREE OR TWO WITH MOST AREAS IN THE MID 80S. WINDS ARE
BIT STRONGER WITH SOME GUSTS TO 20 MPH ACROSS NORTHERN IL. PATCHY
FOG DEVELOPED OVERNIGHT/THIS MORNING AND WHILE THERE IS LITTLE
CHANGE TO THE AIRMASS WITH DEWPOINTS STILL IN THE LOWER/MID 60S...
THE GRADIENT WILL BE SLIGHTLY STRONGER TONIGHT. THUS CONFIDENCE
REGARDING LIGHT FOG/HAZE ISN/T PARTICULARLY HIGH BUT OPTED TO
INCLUDE PATCHY FOG EXCEPT FOR THE IMMEDIATE METRO AREA/CHICAGO.
THE GRADIENT TIGHTENS A BIT MORE WEDNESDAY AND EXPECT WIND GUSTS
INTO THE 20-25 MPH RANGE ACROSS NORTHERN IL. THERMALLY...TEMPS DO
WARM A FEW DEGREES ALOFT AND EVEN WITH AN EXPECTED CU FIELD...
THINK MOST AREAS WILL TAG 90 WEDNESDAY AFTERNOON AND WIND SPEEDS
SHOULD BE STRONG ENOUGH TO PREVENT ANY LAKE BREEZE.
A COLD FRONT WILL MOVE SOUTH ACROSS THE MIDWEST/LAKES REGION
WEDNESDAY NIGHT AND THROUGH MUCH OF THE CWA DURING THE MID/LATE
MORNING OF THURSDAY. THIS MAKES FOR A TRICKY HIGH TEMP FORECAST AS
HIGHS IN THE SOUTH COULD EASILY BE IN THE UPPER 80S...WHILE WINDS
TURNING OFF THE LAKE WILL PROBABLY HOLD TEMPS STEADY MID DAY AND
THEN FALLING TEMPS INTO THE MID/LATE AFTERNOON. CONVECTION ALONG
AND AHEAD OF THE FRONT WEDNESDAY EVENING WILL LIKELY BE IN SOME
FORM OF DECAY AS IT SPREADS INTO FAR NORTHERN IL AROUND MIDNIGHT
AND CONTINUES SOUTH OVERNIGHT. UPPER LEVEL SUPPORT/DYNAMICS ALL
BEGIN TO WEAKEN INTO THURSDAY AND PRECIP CHANCES OR MORE
SPECIFICALLY QPF AMOUNTS ARE LOOKING RATHER MEAGER WITH PERHAPS
SOME AREAS REMAINING DRY. DIURNAL DEVELOPMENT ON THE FRONT IN THE
AFTERNOON COULD BRING ADDITIONAL PRECIP BUT PERHAPS ACROSS THE
FAR SOUTHERN CWA BY THAT TIME.
THE FASTER FROPA TIMING DRYS THINGS OUT THURSDAY NIGHT WITH HIGH
PRESSURE BUILDING ACROSS THE WESTERN LAKES FRIDAY AND SATURDAY.
THIS ENDS ANY CHANCE OF PRECIP DURING THIS TIME AND MUCH DRIER AIR
WILL SPREAD ACROSS THE AREA FRIDAY. IN FACT...SOUNDINGS WOULD
SUGGEST DEWPOINTS COULD DROP INTO THE 40S...MAYBE EVEN UPPER 30S
WITH AFTERNOON MIXING AND THUS HAVE SIGNIFICANTLY LOWERED DEWPOINTS
FRIDAY AFTERNOON.
THIS HIGH BEGINS TO MOVE EAST SATURDAY NIGHT AND SUNDAY AS
SOUTHERLY FLOW RETURNS. THE GENERAL TREND OF A SIGNIFICANT WARM
UP THAT MAY PERSIST FOR SEVERAL DAYS IS STILL ON TRACK...WITH ONE
EXCEPTION...THE 00Z ECMWF FROM THIS MORNING. THIS RUN SHOWED A
STRONG COLD FRONT PUSHING SOUTH INTO THE AREA MONDAY NIGHT INTO
TUESDAY. THIS FRONT STILL MAKES A RUN AT NORTHERN IL BY MIDWEEK
BUT IS WEAKER AND SLOWER WITH THE NEW 12Z ECMWF. MEANWHILE THE
GEM/GFS CONTINUE TO MAINTAIN DRY SOUTHERLY FLOW INTO MONDAY/
TUESDAY. GIVEN HOW DRY IT HAS BEEN AND APPEARS TO REMAIN...WILL
NOT INTRODUCE ANY POPS DURING THIS TIME PERIOD THIS FAR OUT.
RISING TEMPS ON THE BACK SIDE OF THE HIGH SEEM SOMEWHAT SLOWED BY
THE DEPARTING HIGH. THUS...WHILE TEMPS COULD REACH 90 SUNDAY...
FEEL MORE COMFORTABLE HOLDING IN THE UPPER 80S WITH TEMPS REACHING
90 PERHAPS LOWER 90S MANY LOCATIONS ON MONDAY. GIVEN THE SOMEWHAT
LOWER CONFIDENCE REGARDING THE FROPA POTENTIAL ON TUESDAY...HAVE
MAINTAINED HIGHS ONLY IN THE 80S FOR NOW. CMS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* NONE.
KJB
//DISCUSSION...UPDATED 18Z...
AN EXPANSIVE AREA OF SURFACE HIGH PRESSURE CONTINUES TO DOMINATE
ACROSS THE SOUTHERLY GREAT LAKES...ACROSS THE OHIO VALLEY AND THE
CENTRAL ATLANTIC COAST. THIS FEATURE WILL MOVE LITTLE OVER THE NEXT
24 HOURS. HOWEVER...A COLD FRONT IS EXPECTED TO BEGIN DROPPING
SOUTHWARD ACROSS THE NORTHERN WISCONSIN DURING THE DAY ON WEDNESDAY.
WITH A SLIGHTLY STRONGER PRESSURE GRADIENT DEVELOPING ACROSS THE
AREA...SOUTH-SOUTHWEST WINDS WILL INCREASE A BIT INTO
WEDNESDAY...WITH SOME GUSTS UP TO AROUND 18-20 KT DURING THE
AFTERNOON. THIS SHOULD KEEP THE THREAT OF ANY LAKE BREEZES LOW
THROUGH THE PERIOD.
OVERALL...THE PERIOD APPEARS TO REMAIN QUIET THROUGH WEDNESDAY
AFTERNOON. THE ONLY WEATHER ISSUE WILL BE ANOTHER DECENT POTENTIAL
FOR SOME GROUND FOG LATER TONIGHT AT ROCKFORD AND DUPAGE AFTER 09
UTC. THIS HAS OCCURRED THE LAST FEW MORNINGS...AND WITH LITTLE
OVERALL CHANGE EXPECTED TONIGHT...I WOULD EXPECT THAT SOME SHALLOW
FOG MAY AGAIN DEVELOP IN THESE LOCATIONS. THEREFORE...I ADDED A
TEMPO TO BOTH SITES FOR MIFG LATER TONIGHT.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.
KJB
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
WEDNESDAY NIGHT...CHC TSRA.
THURSDAY...CHC TSRA.
FRIDAY...VFR.
SATURDAY...SLT CHC TSRA.
SUNDAY...VFR.
MONDAY...VFR.
BMD
&&
.MARINE...
259 PM CDT
THE PRESSURE GRADIENT WILL CONTINUE TO TIGHTEN OVER THE LAKE DUE TO
DEEP LOW PRESSURE WELL TO THE NORTH AND AN APPROACHING COLD FRONT.
SOUTH/SOUTHWEST WINDS WILL PEAK ON WEDNESDAY...WITH SUSTAINED WINDS
ON THE NORTH HALF APPROACHING THE MID 20S KT RANGE. DESPITE STABLE
CONDITIONS...THIS SHOULD YIELD GUSTS TO 30 KT. WINDS ON THE SOUTH
HALF WILL INCREASE TO 15 TO 25 KT. THEN A FAIRLY STRONG COLD FRONT
WILL CROSS THE LAKE WEDNESDAY NIGHT THROUGH THURSDAY MORNING...WITH
WINDS TURNING NORTHERLY AND INCREASING. GUIDANCE HAS COME INTO LINE
TO SUPPORT A PERIOD OF NORTHERLY WINDS TO AROUND 25 KT ON THE SOUTH
HALF THURSDAY INTO THURSDAY EVENING BEFORE WINDS BEGIN TO DIMINISH
AS HIGH PRESSURE SPREADS IN FROM THE NORTH. THE STRONG NORTHERLY
FLOW AND HIGHER WAVES WILL LIKELY NECESSITATE A SMALL CRAFT ADVISORY
FOR ALL THE ILLINOIS AND INDIANA NEARSHORE ZONES THURSDAY
AFTERNOON THROUGH FRIDAY AFTERNOON. WINDS WILL BE FAIRLY LIGHT MOST
OF FRIDAY THROUGH EARLY SATURDAY BUT THEN SOUTHERLY WINDS WILL
INCREASE AGAIN ESPECIALLY ON THE NORTH HALF AS THE HIGH QUICKLY
SHIFTS EAST AND A WARM FRONT LIFTS NORTH.
RC
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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Area Forecast Discussion
National Weather Service Lincoln IL
1237 PM CDT Tue Aug 20 2013
.DISCUSSION...
ISSUED 1026 AM CDT Tue Aug 20 2013
9 AM surface map showed high pressure centered over the mid-
Atlantic coast, with ridging extending west into southern IL and
MO. This put most of central IL in a very light wind regime,
though light return southerly flow on the back side of the ridge had
pushed east to the I-55 corridor. Aloft, water vapor imagery
indicated a cutoff mid-level low circulating over west central IL
and an additional shortwave in western KY. 12Z ILX sounding was
quite dry in the mid levels and high-res models focus better
ascent ahead of the KY shortwave as it drifts northeast this
afternoon. A very isolated shower or storm is possible in the far
southeast this afternoon where RAP soundings show little to no cap in
place, however feel if anything does develop should be confined
farther east into southern IN and have maintained a dry forecast.
Otherwise, mostly sunny skies will dominate the CWA today. Mixing
to around 850MB supports highs of 85-89F.
&&
.AVIATION...
ISSUED 1236 PM CDT Tue Aug 20 2013
High pressure ridge finally shifting east of the region, and
allowing light southerly flow to develop which will persist
through 18Z/Wed. SCT diurnal cu with bases around 5K Ft will
briefly go BKN this afternoon, but predominant SCT conditions
should prevail. Similar cloud trends are expected to develop again
by late morning Wed. Some brief MVFR visibility restrictions could
develop within a few hours of sunrise however this should not be
as widespread as recent days due to ridge axis well east of the area.
25
&&
.PREV DISCUSSION...
ISSUED 225 AM CDT Tue Aug 20 2013
Illinois remains on the periphery of high pressure that was
centered near the mid-Atlantic coast early this morning. Have seen
some high clouds rotating around an upper level circulation that
was very evident on water vapor imagery, dropping along the
Mississippi River in far western Illinois.
Primary forecast focus remains on rain chances later this week,
along with extended period of very warm conditions.
SHORT TERM...Today through Thursday...
Upper circulation to continue to carve out a broad trough over
Illinois today, with model guidance showing some potential for a
small closed circulation forming by late tonight before the trough
swings eastward. Currently appears that any rain with this feature
will remain to our east. Temperatures continue a slow but steady
rise and should reach the upper 80s most areas by Wednesday.
Main focus shifts to an upper wave moving across southwest Canada
early this morning. Broad east-west ridging over the southern U.S.
should start to amplify across the Rockies Wednesday night,
allowing the wave to dig more as it sweeps through the Great Lakes
region. The guidance is generally in agreement with the resulting
surface front pushing all the way through the state on Thursday.
Still some question as to whether or not this is overly aggressive
for this time of year, especially the NAM solution as it brings
temps all the way down to the lower 50s by Friday morning behind
the front. Rain-wise, have introduced some slight chance PoPs
after midnight Wednesday night across the northern CWA, and a
broad area of 30% chances east of a Macomb to Lawrenceville line
on Thursday. Have lingered some slights into Thursday night and
Friday, as the ECMWF model shows some hints of the front pushing
back northeast.
LONG TERM...Friday through Monday...
Broad dome of high pressure aloft to cover most of the country
this weekend and early next week. Convective systems traversing
the northern flank of the ridge should stay to our north, with
core of the upper high nearly overhead. After a brief cool down on
Friday, gradual warming will take place through early next week,
with highs near 90 becoming more common. Humidity levels not
expected to get out of hand due to the recent dry conditions, so
heat index values will only be a few degrees warmer than the
observed temperatures.
Geelhart
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
418 PM EDT TUE AUG 20 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 416 PM EDT TUE AUG 20 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL MID/UPPER LEVEL
FLOW ACROSS SRN CANADA AND THE NRN CONUS ATOP RIDING OVER THE PLAINS
AND A CUTOFF LOW NEAR KSTL. THE MAIN UPSTREAM SHORTWAVE TROUGH WAS
LOCATED WELL UPSTREAM...FROM SASK INTO ERN ALBERTA. AT THE SFC...SW
FLOW PREVAILED THROUGH THE WRN GREAT LAKES BTWN HIGH PRES OVER THE
ERN OH VALLEY AND A TROUGH FROM NW ONTARIO INTO CNTRL ND. A COLD
FRONT EXTENDED FROM NEAR WINNIPEG INTO SRN SASK. ALTHOUGH VIS LOOP
SHOWED ABUNDANT CU ACROSS THE REGION AND A LAKE BREEZE BOUNDARY OFF
OF LAKE MI...CAPPING EVIDENT ON AREA SOUNDINGS WITH 800-700 MB TEMPS
AROUND 13C HAS SUPPRESSED ANY CONVECTION THAT WOULD PRODUCE ANY
SHRA/TSRA.
TONIGHT...AS THE ALBERTA/SASK MOVES INTO MANITOBA AND THE PLAINS
TROUGH SLIDES TO THE EAST THE STRONGEST LOW LEVEL MOISTURE
ADVECTION...FOCUS OF THE LOW LEVEL JET...AND 310K ISENTROPIC LIFT
THROUGH THE 850-700 MB FRONT WILL REMAIN JUST NORTH OF LAKE SUPERIOR
BUT MAY BRUSH THE NRN PORTION OF THE LAKE. OTHERWISE...THE PERSISTENT
SW FLOW THROUGH THE WRN LAKES WILL KEEP TEMPS WELL ABOVE
NORMAL...ESPECIALLY FOR DOWNSLOPE LOCATIONS NEAR LAKE SUPERIOR. MIN
READINGS IN THE MID 60S TO LOWER 70S...NEAR THE HIGHER END OF
GUIDANCE ARE EXPECTED.
WED...AS THE SHRTWV MOVES THROUGH NRN ONTARIO IT WILL DRAG THE COLD
FRONT THROUGH LAKE SUPERIOR AND UPPER MI. THE COMBINATION OF LOW
LEVEL CONV ALONG THE FRONT...REINFORCED BY THE LAKE SUPERIOR
BREEZE...AND WEAK TO MODERATE MID LEVEL QVECTOR CONV WITH THE TAIL
OF THE SHRTWV SHOULD TRIGGER TSRA OVER WEST UPPER MI IN THE EARLY
AFTERNOON WHICH WILL SPREAD INTO THE CNTRL CWA BY MID AND LATE
AFTERNOON. DEWPOINTS INTO THE UPPER 60S AND TEMPS IN THE UPPER 80S
WILL RESULT IN MLCAPE VALUES INTO THE 2K-3K J/KG RANGE. THE STRONG
INSTABILITY(BY U.P. STANDARDS) ALONG WITH 0-6KM SHEAR TO AROUND 30
KT WILL BE ENOUGH TO SUPPORT MULTICELL CLUSTERS WITH SOME SEVERE
THUNDERSTORMS. WITH DCAPE VALUES OF 1K J/KG...DAMAGING WINDS WILL BE
THE MAIN THREAT. SOME ISOLATED LARGE HAIL MAY ALSO BE POSSIBLE WITH
THE STRONGEST STORMS.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 416 PM EDT TUE AUG 20 2013
COLD FRONT AND ASSOCIATED SHOWERS/THUNDERSTORMS WILL BE MOVING
SOUTHEAST ACROSS CENTRAL AND EASTERN UPPER MICHIGAN AT THE
START OF THE LONG TERM PERIOD. EXPECT THESE STRONG TO POTENTIALLY
SEVERE THUNDERSTORMS TO BE SLIDING EAST-SOUTHEAST ACROSS THOSE AREAS
DURING THE EVENING HOURS AND BE MOVING INTO LAKE MICHIGAN TOWARDS
MIDNIGHT OR THE EARLY OVERNIGHT HOURS. 12Z MODELS TODAY SEEM TO BE
A LITTLE SLOWER WITH THE FRONTAL PASSAGE THAN YESTERDAY...SO WILL
FOLLOW THE IDEA OF THE MID SHIFT WITH THE TIMING.
A SHORTWAVE DIVING SOUTHEAST FROM LAKE WINNIPEG WEDNESDAY NIGHT
WILL CROSS THE U.P. ON THURSDAY MORNING. WITH THE DRY AIR AND
HIGH PRESSURE THAT ARRIVES BEHIND THE COLD FRONT...SHOULDN/T SEE
MUCH INFLUENCE FROM THE SHORTWAVE ON THE WEATHER AND EXPECT MOSTLY
SUNNY SKIES. HIGHS THURSDAY WILL BE MUCH COOLER (BY 10-15
DEGREES) THAN WEDNESDAY WITH THE NORTHERLY WINDS OFF LAKE SUPERIOR.
FORTUNATELY...MOST AREAS WILL SEE RAIN TOMORROW...OTHERWISE THERE
COULD BE AN ELEVATED FIRE WX RISK WITH NORTH WINDS OF 10-20MPH AND
RH VALUES FALLING TOWARDS 30 PERCENT.
ANOTHER SHORTWAVE ROUNDING THE UPPER RIDGE IN CENTRAL CANADA WILL
DIVE SOUTHEAST ACROSS THE EASTERN CWA ON FRIDAY. AT THIS
TIME...WOULD EXPECT SOME INCREASE IN CLOUD COVER BASED OFF
925-850MB MOISTURE AND DIURNAL HEATING OVER THE EASTERN PART OF THE
CWA (MAINLY FROM MARQUETTE/DICKINSON COUNTIES AND EAST). WON/T GO
TOO HIGH ON CLOUD COVER...BUT AT LEAST GIVE A PERIOD OF PARTLY
CLOUDY SKIES OVER THE EAST AS THAT MOISTURE MOVES THROUGH.
UPPER RIDGE THAT WAS OVER THE NORTHERN PLAINS AND CENTRAL CANADA
WILL THEN SHIFT EAST ON FRIDAY NIGHT WITH THE AXIS OF THE RIDGE
OVER UPPER MICHIGAN BY 12Z SATURDAY. THIS MOVEMENT OF THE RIDGE
WILL ALSO SLIDE THE SURFACE HIGH EAST OF THE AREA AND ALLOW
SOUTHERLY FLOW AND GRADUALLY WARMING TEMPERATURES TO RETURN. MODELS
ARE STILL STRUGGLING TO COME UP WITH A CONSENSUS ON THE SERIES OF
SHORTWAVES MOVING INTO THE UPPER RIDGE AND GRADUALLY BREAKING IT
DOWN FROM SATURDAY AFTERNOON THROUGH THE FIRST HALF OF NEXT WEEK.
THE FIRST WAVE WILL MOVE THROUGH THE AREA SATURDAY AFTERNOON AND
NIGHT (OVER THE NORTH HALF OF THE CWA) AND THE NEXT ONE LATE SUNDAY
AFTERNOON INTO MONDAY MORNING. THE DISCREPANCIES GROW FURTHER ON
MONDAY NIGHT INTO TUESDAY...WITH GFS BRINGING ANOTHER SHORTWAVE
THROUGH ON TUESDAY WHILE THE ECMWF/GEM HAS HIGH PRESSURE OVER THE
AREA. THESE PERIODS OF SHOWERS/THUNDERSTORMS ALSO LEADS TO
UNCERTAINTY WITH HIGHS BUT SHOULD AT LEAST BE ABOVE NORMAL.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 136 PM EDT TUE AUG 20 2013
EXPECT VFR CONDITIONS THROUGH THE FORECAST PERIOD AT ALL 3 TAF SITES
WITH A RELATIVELY DRY/CAPPED LOW LEVEL AIRMASS DOMINATING. GUSTY SW
WINDS AIDED BY DAYTIMME HEATING/MIXING WILL DIMINISH LATE TODAY.
AFTER SUNSET AN INVERSION WL FORM AND RESULT IN LLWS WITH
STRENGTHENING NOCTURNAL SW LOW LEVEL JET UNDER A SHARPENING PRES
GRADIENT AHEAD OF APPROACHING COLD FRONT. ANY SHRA/TSRA WITH THE
FRONT ARE EXPECTED TO HOLD OFF UNTIL AFTER THE TAF PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 416 PM EDT TUE AUG 20 2013
OVERALL...EXPECT WINDS LESS THAN 20KT THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. ONE PERIOD OF STRONGER WINDS (GUSTS TO 20-25KT)
MAY OCCUR TONIGHT AS THE PRES GRADIENT TIGHTENS AHEAD OF THE
APPROACHING COLD FRONT...BUT HIGH OVERWATER STABILITY WITH INFLUX
OF A VERY WARM AIRMASS WILL LIMIT THE INCREASE OF WIND SPEED NEAR THE
COOLER LAKE SURFACE. THE ARRIVAL OF MORE HUMID AIR MAY RESULT IN
SOME FOG FORMATION OVER THE COOLER LAKE WATERS...BUT RESTRICTED THE
FOG FORECAST TO AREAS WHERE SOME SHOWERS OR THUNDERSTORMS ARE
EXPECTED. ANY FOG WILL DISSIPATE WED AFTN AND EVENING FOLLOWING A
COLD FRONTAL PASSAGE AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
136 PM EDT TUE AUG 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 405 AM EDT TUE AUG 20 2013
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW REBOUNDING UPR RDG
INTO THE UPR GRT LKS ON THE SRN FLANK OF ZONAL FLOW OVER CANADA. A
PRONOUNCED H5 THERMAL RDG IS EVIDENT STRETCHING FM THE NRN PLAINS
THRU NW MN AND INTO NW ONTARIO...WITH THE 00Z H5 TEMP UP TO -7C AT
INL...COMPARED TO THE -11C OBS AT APX CLOSER TO DEPARTING SHRTWV IN
THE CENTRAL LKS. THE COMBINATION OF THE ASSOCIATED MID LVL CAPPING
AND SUBSIDENCE RELATED TO DEEP LYR QVECTOR DVGC ACCOMPANYING THE
BLDG RDG IS RESULTING IN MOCLR SKIES OVER THE CWA EARLY THIS MRNG
DESPITE ADVECTION OF SOMEWHAT HIER LLVL MSTR WITH H85 DEWPTS UP TO
16C AT MPX IN THE SW FLOW ARND SFC HI PRES IN THE MID ATLANTIC
STATES. DESPITE THE MOCLR SKIES...THE STEADY SW FLOW IS RESULTING IN
ABV NORMAL TEMPS EARLY THIS MRNG...ESPECIALLY OVER THE W HALF OF UPR
MI IN THE DOWNSLOPE AREAS NEAR LK SUP...WHERE READINGS ARE HAVING A
HARD TIME FALLING BLO 70. BUT EVEN WARMER AIR IS TO THE W...WITH 00Z
H85 TEMPS RANGING FM 14C AT GRB AND APX TO 17C AT MPX...19C AT
INL...AND A TOASTY 25C AT BISMARCK. THERE IS ANOTHER SHRTWV SHIFTING
EWD THRU THE NRN PLAINS...BUT THE 00Z BISMARCK RAOB IS SO DRY THERE
IS NO PCPN OR EVEN ANY CLD COVER.
MAIN FCST CONCERNS IN THE SHORT TERM FOCUS ON TEMPS AND SMALL SHRA/
TS CHCS.
TODAY...UPR MI IS FCST TO REMAIN UNDER THE UPR RDG AXIS...WITH H5
THERMAL RDG/TEMPS ARND -7C NOTED ABOVE SHIFTING OVHD IN MID LVL
SUBSIDENCE REGIME. CONTINUED SW FLOW ARND STAGNANT SFC HI PRES IN
THE MID ATLANTIC IS FCST TO LIFT H85 TEMPS UP TO 17-18C OVER THE E
TO 18-19C OVER THE W BY 00Z WED. MIXING TO H8 ON GFS/NAM FCST SDNGS
YIELDS HI TEMPS REACHING TO ARND 90 AWAY FM THE COOLING INFLUENCE OF
LK MI...SO PREFER TO HEDGE TOWARD THE HI END OF GUIDANCE FOR MAX
TEMPS FCST. THIS SW FLOW WL ALSO ADVECT THE HIER LLVL MSTR SHOWN ON
THE 00Z MPX RAOB INTO THE UPR LKS...RESULTING IN A MORE HUMID AND
UNCOMFORTABLE DAY AS SFC DEWPTS RUN WELL INTO THE 60S. DESPITE THE
INCRSG HEAT/HUMIDITY THAT WL LIFT MUCAPE AOA 2000J/KG THIS AFTN PER
MODIFIED GFS/NAM FCST SDNGS FOR SFC T/TD 90/65...SUSPECT THE MID LVL
WARMTH/DRYNESS/STABILITY WL SUPPRESS CONVECTION. ONE POSITIVE FOR
SHRA/TS WOULD BE THE APRCH LATER THIS AFTN OF SHRTWV NOW MOVING THRU
THE NRN PLAINS...BUT CONSIDERING GFS/NAM MOS POPS AOB 10 PCT...
PRESENCE OF VERY WARM H5 AIR/SHARPER CAPPING...AND ABSENCE OF
APPRECIABLE LK BREEZE CNVGC WITH SUPPRESSION OF LK SUP BREEZE IN
SYNOPTIC SW FLOW...OPTED TO GO DRY FOR THE ENTIRE CWA TODAY.
TNGT...STEADY SW FLOW WITH H925 WINDS UP TO 30-35KTS UNDER
SHARPENING PRES GRADIENT BTWN MID ATLANTIC HI PRES AND APRCHG COLD
FNT IN MN ASSOCIATED WITH SHRTWV RIDING E IN THE ZONAL FLOW THRU
CANADA IS FCST TO LIFT H85 TEMPS AOA 20C OVER THE WRN CWA OVERNGT.
WL TEND AOA THE HI END OF GUIDANCE FOR MIN TEMPS...ESPECIALLY IN THE
DOWNSLOPE AREAS NEAR LK SUP OVER THE W HALF. CONCERNED THE ARRIVAL
OF SOME DEEP LYR QVECTOR CNVGC/STEEPENING LAPSE RATES WITH FALLING
H5 TEMPS TOWARD -10C IN ADVANCE OF THE FNT LATE TNGT MIGHT GENERATE
SOME SHRA/TS OVER AT LEAST THE NW HALF OF THE CWA. ALTHOUGH THE BULK
OF THE NUMERICAL MODELS SHOW A DRY FCST FOR THE CWA THRU 12Z WED...
OPTED TO RETAIN SOME SCHC POPS OVER THE MAINLY WRN/NCENTRAL LK SUP
SINCE THERE WL BE SOME DYNAMIC SUPPORT AND THE GFS AS WELL AS THE
LOCAL WRF/ARW MODELS DO GENERATE SOME PCPN.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 405 AM EDT TUE AUG 20 2013
NOT TOO MUCH HAS CHANGED SINCE 24 HOURS AGO...AND AM WELL IN
AGREEMENT WITH THE PREVIOUS SHIFT. STILL HAVE SOME
UNCERTAINTY...ESPECIALLY WITH SOME SPECIFIC ITEMS...BUT WILL TALK
ABOUT THAT IN MORE DETAIL BELOW.
FOR WED...A NRN STREAM TROUGH WILL SLIDE ACROSS THE CWA WED INTO WED
NIGHT...WHICH WILL BRING INCREASED CHANCES OF PRECIP FOR THAT
PERIOD. WITH 850MB TEMPS AROUND 20C AT PEAK HEATING WED
AFTERNOON...HIGH TEMPS AHEAD OF THE FRONT AND ASSOCIATED PRECIP AND
CLOUD COVER SHOULD BE ABLE TO GET INTO THE LOW 90S /AWAY FROM LAKE
MICHIGAN FROM MODERATING SW WINDS AND IMMEDIATE SHORES OF LAKE
SUPERIOR/. THE SW-NE ORIENTED COLD FRONT LOOKS TO MOVE INTO WRN
UPPER MI AROUND 18Z WED...WITH SOME VARIABILITY BETWEEN THE MODELS
/ECMWF AND GFS SHOWING THIS SOLUTION AND THE NAM AND GEM BEING
FASTER/. BY 00Z THU...MODELS SHOW THE COLD FRONT FROM ERN LAKE
SUPERIOR INTO SCENTRAL UPPER MI...WITH THE FRONT JUST E OF THE CWA
BY 06Z THU. SHOULD SEE CAPE VALUES OF 1500-2500J/KG AND POSSIBLY AS
HIGH AS 3000J/KG AHEAD OF THE FRONT. 0-6KM SHEAR LOOKS TO BE ON THE
LOW SIDE FOR ORGANIZED THUNDERSTORMS AT AROUND 20KTS...AND THAT IS
MOSTLY UNIDIRECTIONAL. STORM MODE SHOULD BE MULTICELL CLUSTERS AND
BEST THREAT FOR SEVERE WEATHER WILL BE MORE ISOLATED DAMAGING
WINDS...ESPECIALLY OVER THE SCENTRAL CWA WHERE DCAPE VALUES WILL BE
ENHANCED. HAIL THREAT WILL BE MORE MINIMAL DUE TO WEAK SHEAR AND THE
FREEZING LEVEL BEING AROUND 12KFT. WILL CONTINUE TO SHOW LIKELY POPS
OVER MUCH OF THE AREA TIMED CLOSE TO EXPECTED FROPA. WITH THE
UNCERTAINTY IN FRONTAL TIMING...HIGH TEMPS MAY BE MORE IN JEOPARDY
IF THE FRONT COMES THROUGH FASTER AND CONVECTIVE COVERAGE/INTENSITY
IS MORE UNCERTAIN.
BY LATE WED NIGHT...SHOULD SEE ALL PRECIP AND MOST CLOUDS CLEARED
OUT AS AS SFC HIGH MOVES IN FROM THE W...AND WITH 850MB TEMPS AROUND
12C BY 12Z THU...LOW TEMPS SHOULD BE ABLE TO QUICKLY FALL OFF TO
AROUND 50F OVER PARTS OF THE INTERIOR W.
WHILE A COUPLE OF UPPER SHORTWAVES MOVE THROUGH THU AND FRI...THE
SFC HIGH WILL BE DIRECTLY OVER THE CWA LATE THU INTO THU NIGHT...AND
WILL HAVE JUST MOVED E OFF THE CWA BY LATE FRI...SO IT WILL BE TOO
DRY FOR ANY PRECIP OVER THE CWA RESULTING FROM THE SHORTWAVES. 850MB
TEMPS COOL SOME MORE WITH CONTINUED NLY FLOW AND THE SHORTWAVE ON
THU TO AROUND 10-11C...RESULTING IN MUCH COOLER HIGH TEMPS IN THE
70S /OR POSSIBLY LOW 80S OVER FAR SCENTRAL UPPER MI/. FRI TEMPS LOOK
SIMILAR IF NOT A DEGREE OR TWO COOLER IN MOST LOCATIONS.
MORE UNCERTAIN ON LATER TIME FRAMES...BUT SOME PRECIP LOOKS POSSIBLE
LATE FRI NIGHT INTO EARLY SAT NIGHT AS A WARM FRONT/WAA MOVES INTO
THE CWA. MODELS AGREE ON BRINGING UPPER RIDGING ACROSS THE CWA SAT
AND SUN...RESULTING IN 850MB TEMPS INCREASING TO AROUND 20C BY 00Z
MON. THINK TEMPS MAY BE TOO LOW IN THE EXTENDED /SOMEWHAT FOR
SAT...BUT MORE SO FOR SUN/...BUT UNCERTAINTY RELATING TO PRECIP/CLOUDS
MAKES IT HARD TO JUSTIFY INCREASING TEMPS SIGNIFICANTLY. THINK THAT
CONSENSUS OF GUIDANCE WILL BE FAIRLY REPRESENTATIVE FOR SAT AND SUN.
MUCH DECREASED CONFIDENCE ON MON AS MODELS HAVE DIFFICULTY HANDLING
CONVECTION POSSIBILITIES NEAR/OVER THE CWA. WILL CONTINUE TO USE
CONSENSUS OF GUIDANCE FOR MON GIVEN THE LIMITED CONFIDENCE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 136 PM EDT TUE AUG 20 2013
EXPECT VFR CONDITIONS THROUGH THE FORECAST PERIOD AT ALL 3 TAF SITES
WITH A RELATIVELY DRY/CAPPED LOW LEVEL AIRMASS DOMINATING. GUSTY SW
WINDS AIDED BY DAYTIMME HEATING/MIXING WILL DIMINISH LATE TODAY.
AFTER SUNSET AN INVERSION WL FORM AND RESULT IN LLWS WITH
STRENGTHENING NOCTURNAL SW LOW LEVEL JET UNDER A SHARPENING PRES
GRADIENT AHEAD OF APPROACHING COLD FRONT. ANY SHRA/TSRA WITH THE
FRONT ARE EXPECTED TO HOLD OFF UNTIL AFTER THE TAF PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 405 AM EDT TUE AUG 20 2013
OVERALL...EXPECT WINDS LESS THAN 20KT THRU THE PERIOD AS A
RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE
GREAT LAKES REGION. ONE PERIOD OF STRONGER WINDS (GUSTS TO 20-25KT)
MAY OCCUR TONIGHT AS PRES GRADIENT TIGHTENS AHEAD OF APPROACHING
COLD FRONT...BUT HI OVERWATER STABILITY WITH INFLUX OF VERY WARM
AIRMASS WILL LIMIT THE INCREASE OF WIND SPEED NEAR THE COOLER LAKE
SURFACE. THE ARRIVAL OF MORE HUMID AIR MAY RESULT IN SOME FOG
FORMATION OVER THE COOLER LAKE WATERS...BUT RESTRICTED THE FOG
FORECAST TO AREAS WHERE SOME SHOWERS OR THUNDERSTORMS ARE EXPECTED.
ANY FOG WILL DISSIPATE WED AFTN/EVENING FOLLOWING A COLD FRONTAL
PASSAGE AND THE ARRIVAL OF DRIER AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TITUS
AVIATION...JLB
MARINE...KC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
136 PM CDT TUE AUG 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT TUE AUG 20 2013
TODAY AND TONIGHT...850MB WINDS CONTINUE FROM THE SOUTH WITH A
SLIGHT SOUTHWEST COMPONENT. SPEEDS INCREASE TO AROUND 25 KTS
SUPPORTING 15 TO 25 MPH SFC WIND SPEEDS. A DRYLINE BULGE SHOULD
DEVELOP ACROSS WRN NEB AND THE SANDHILLS SUPPORTING DEEPER
MIXING. SOME OF GUIDANCE SUGGESTS LOW 100S FOR HIGHS. THE PROBLEM
AREA IS NRN NEB AND VALENTINE WHERE HOT DRY AIR WILL BLOW NORTH
OFF THE SANDHILLS. IF THE SANDHILLS ARE DRY THEN THIS AREA WILL
RISE ABOVE 100.
FOR NOW TEMPS ARE A BLEND OF TRIED AND TRUE GUIDANCE FOR HIGHS IN
THE 90S TO 100. WITH H700MB TEMPS RISING TOWARD 16C THIS AFTN
ACROSS WRN NEB THERE COULD BE SOME LOW 100S BUT WE WOULD LIKE TO
SEE A MORE SWRLY COMPONENT TO THE 850 MB WINDS AND 700MB WINDS
DUE WEST VS THE RAP FCSTING SOUTHWEST WINDS AT 700MB.
ISOLATED TSTMS ARE POSSIBLE THIS AFTN ACROSS NWRN NEB AS A COLD
FRONT DROPS IN. A SLIGHT COOLING ALOFT TONIGHT MIGHT ALLOW A FEW
STORMS TO FORM FARTHER EAST ACROSS NRN NEB. OTHERWISE THE HEAT
CONTINUES TODAY WITH DEW POINTS IN THE UPPER 60S EAST OF HIGHWAY
83. THE DRYLINE BULGE SHOULD REACH TO HIGHWAY 83 THIS AFTN AND
THEN RETREAT WEST THIS EVENING.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 341 AM CDT TUE AUG 20 2013
SUMMER LIKE WEATHER THROUGH MUCH OF THE MID TO LONG RANGE
FORECAST. UPPER LEVEL RIDGE WILL CONTINUE TO MIGRATE EAST AND
BECOME CENTERED OVER THE PLAINS BY THE WEEKEND. MODELS IN GOOD
AGREEMENT WITH THE 500 MB HEIGHT OF THE HIGH REACHING 1594M TO
1595M.
AT THE SFC A COLD FRONT WILL PUSH ACROSS THE AREA WED...WHICH
SHOULD BE THE FOCUS FOR ISOLD THUNDERSTORMS BY EARLY AFTERNOON AS
CAP WEAKENS. INITIALLY MOISTURE IS LIMIT IN THE COLUMN...WITH
PRECIP H2O AROUND AN INCH...NEAR THE 50 PERCENTILE FOR
AUGUST...HOWEVER AN INCREASE THROUGHOUT THE DAY...POOLING ALONG
THE BOUNDARY...IS EXPECTED. THE DEW PTS ARE EXPECTED IN THE MID
AND UPPER 60S FOR THE AFTERNOON...AND SHOULD BE ENOUGH TO HELP
BREAK THE CAP. SOUNDINGS SUGGEST HIGH BASED STORMS NEAR 8K TO 10K
FEET. DIRECTIONAL SHEAR IS DECENT...HOWEVER LIMITED SPEED SHEAR.
A FEW STRONG STORMS CAN NOT BE RULED OUT...AND WILL BE MONITORED.
WEAK SECONDARY BOUNDARY AND UPPER LEVEL WAVE WILL PUSH INTO THE
NW WED EVENING AND ACROSS NRN NEB THURSDAY. SLIGHT CHANCE POPS
WARRANTED AT THIS TIME...ALTHOUGH CONVECTION ALONG THE COLD FRONT
MAY CAUSE THIS DISTURBANCE TO DIMINISH IN EFFECT. LINGERING
CLOUDS AND SLIGHTLY COOLER AIR BEHIND THE COLD FRONT WILL HOLD
TEMPS IN THE 80S FOR MOST AREAS THURS.
BY FRIDAY THE RIDGE WILL BEGIN TO END THE MAIN THREAT FOR STORMS.
A LEESIDE TROUGH DEVELOPS WHILE A LARGE SFC HIGH EXPENDS ACROSS
THE GREAT LAKES. ACTIVITY IS LIKELY ALONG THE HIGHER TERRAIN/SFC
TROUGH TO THE WEST AND MAY IMPACT THE FAR WESTERN ZONES DUE TO
WESTERLY WINDS. HAVE INCLUDED A SLIGHT CHANCE FOR THE EASTERN
PANHANDLE LATE SATURDAY AS A STRONGER UPPER LEVEL WAVE CROSSES
THE NORTHERN/CENTRAL ROCKIES...OTHERWISE DRY. WITH THE INFLUENCE
OF THE RIDGE...HIGHS WARM BACK INTO THE LOWER TO MID 90S...WELL
ABOVE NORMAL FOR THE LAST HALF OF AUGUST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 100 PM CDT TUE AUG 20 2013
UPPER LEVEL HIGH PRESSURE WILL REMAIN IN FIRM CONTROL ACROSS
WESTERN AND NORTH CENTRAL NEBRASKA THIS AFTERNOON AND TONIGHT. A
WEAK COLD FRONT WILL MOVE INTO FAR NORTHWEST NEBRASKA...WHERE AN
ISOLATED THUNDERSTORM IS POSSIBLE. VFR CONDITIONS WILL
PREVAIL...WITH SURFACE WINDS SOUTH AT 5 TO 15 KTS.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...MASEK
AVIATION...TAYLOR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1159 AM EDT TUE AUG 20 2013
.SYNOPSIS...
A REMNANT FRONTAL BOUNDARY WILL REMAIN NEARLY STALLED AND WEAKEN
ACROSS THE REGION THROUGH MID WEEK. A MODERATELY STRONG COLD
FRONT IS EXPECTED LATE FRIDAY NIGHT. THIS WILL USHER COOLER AND
DRIER AIR THIS COMING WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1159 AM TUESDAY...OLD FRONTAL BOUNDARY REMAINS STALLED OVER
THE AREA AND HIGH PWAT VALUES WILL RESULT AREAS OF HEAVY RAIN ACROSS
THE AREA...FAVORED OVER THE EASTERN AND SOUTHERN ZONES WITH NUMEROUS
SHOWERS AND ISOLATED THUNDERSTORMS. MAXIMUM TEMPERATURES SHOULD
REACH THE MIDDLE 80S UNDER A PARTLY TO MOSTLY CLOUDY SKY. MINS
TONIGHT SHOULD FALL TO THE LOWER 70S.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...NEAR SEASONABLE TEMPERATURES ON WEDNESDAY AS
SURFACE HIGH PRESSURE SITS NOT ONLY OVER THE WEST ATLANTIC BUT ALSO
THE SOUTHEASTERN U.S. UPPER LEVEL RIDGE OVER THE WEST ATLANTIC
BEGINS TO RETREAT TO THE EAST WHILE TROUGHINESS STRENGTHENS OVER
OHIO VALLY. ISO TO WIDELY SCATTERED CONVECTION JUST ABOUT AREA-WIDE
BUT STABILIZING OCEAN AIR TO MAKE FOR SLIGHTLY LOWER POPS ALONG THE
COAST. THE UPPER SYSTEM SWINGS BY TO OUR NORTH LATE THURSDAY INTO
THURSDAY NIGHT AND SHOULD LEAD TO A SMALL UPTICK IN RAIN CHANCES.
SOME MID LEVEL DRY AIR WILL ADVECT INTO THE REGION BEHIND THE
TROUGH.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 3 AM TUESDAY...WESTERN U.S. UPPER RIDGE BUILDS FOR MOST OF THE
PERIOD ALLOWING FOR EASTERN TROUGH TO SHARPEN. PREFRONTAL SURFACE
TROUGH IN THE NW FLOW DRIVEN INTO THE REGION ON FRIDAY TO TOUCH OFF
STORMS DESPITE POSSIBLE RELATIVE DRYNESS IN THE MID LEVELS. THIS IS
FOLLOWED BY WHAT MAY BE A MODERATELY STRONG COLD FRONTAL PASSAGE
FRIDAY NIGHT OR SATURDAY MORNING. SUNDAY AND MONDAY SHOULD BRING IN
SOME COOL AND DRY AIR BY AUGUST STANDARDS.
&&
.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
AS OF 12Z...LIFR CONDITIONS PRETTY WIDESPREAD THIS MORNING.
CLIMATOLOGICAL TRENDS SUGGEST STRATUS WILL SCATTER BETWEEN 15-16Z.
QUITE A BIT OF MID AND HIGH CLOUDS ABOVE MAY RETARD THE MIXING
PROCESS. HRRR MODEL INDICATES ISOLATED/SCATTERED CONVECTION WILL
FORM ALONG THE RESULTANT BOUNDARY AROUND MIDDAY. COVERAGE WILL BE
SUCH THAT A VCSH SHOULD COVER IT. MOST OF THE ACTIVITY WILL BE
SLIGHTLY INLAND FROM THE COASTAL TERMINALS. CONVECTION ENDS BY EARLY
EVENING...WITH ANOTHER ROUND OF FOG/STRATUS EXPECTED AFTER
MIDNIGHT.
EXTENDED OUTLOOK...EARLY MORNING FOG/STRATUS POSSIBLE WEDNESDAY AND
THURSDAY...ESPECIALLY INLAND. ISOLATED SHOWERS/T-STORMS WEDNESDAY
THROUGH FRIDAY...BECOMING MORE WIDELY SCATTERED ON SATURDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1159 AM TUESDAY...OUTSIDE OF LIGHT AND VARIABLE WINDS EARLY TODAY
DUE TO THE LAND BREEZE FORCING THE FRONT OFF THE COAST...EXPECT SE
TO S FLOW AT 10 KT OR LESS THROUGH THE PERIOD. SEAS ARE EXPECTED TO
RUN 2 TO 3 FT.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...HIGH PRESSURE WILL BE LOCATED WELL OFF THE
COAST BUT THERE WILL ALSO BE A SECONDARY CENTER OVER THE
SOUTHEASTERN U.S. THIS WILL KEEP WIND AND SEAS MINIMAL WITH A
PREDOMINANTLY SWRLY DIRECTION ALTHOUGH THE FLOW MAY BACK TO S OR
EVEN SE AT TIMES ESP ALONG THE IMMEDIATE COAST IN ASSOCIATION WITH
THE SEA BREEZE. AN UPPER LEVEL TROUGH MAY BE STRONG ENOUGH TO ERODE
THE STRENGTH OF BOTH SURFACE HIGHS LATER THURSDAY. A LIGHT SW WIND
WILL BE FOUND ACROSS A LARGE PART OF THE SOUTHEAST COAST WHILE THE
RELATIVELY TRANQUIL SEA STATE REMAINS UNCHANGED.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 3 AM TUESDAY...WEAK SW FLOW AHEAD OF A PREFRONTAL TROUGH WILL
VEER TO W OR EVEN NW AS THE TROUGH PASSES BY MIDDAY. NO APPRECIABLE
INCREASE IN WIND SPEED AS EXPECTED WITH THE PASSAGE OF THE WIND
SHIFT. LATE FRIDAY NIGHT THIS WILL BE FOLLOWED BY AN ACTUAL FRONTAL
PASSAGE. A FURTHER VEERING AND INCREASE IN WIND SPEED AND SEAS
EXPECTED.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR SCZ053>056.
NC...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR NCZ099-
105>110.
MARINE...NONE.
&&
$$
NEAR TERM...RAN/8
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...BJR
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
.SHORT TERM...TONIGHT AND WEDNESDAY
ISSUED AT 230 PM CDT TUE AUG 20 2013
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A NEARLY
STATIONARY UPPER LOW SPINNING OVER THE CENTRAL MISSISSIPPI VALLEY
AND A COLD FRONT MOVING ACROSS THE NORTHERN PLAINS. AHEAD OF THE
FRONT...SOUTHWEST WINDS ARE ADVECTION MOISTURE IN THE 900-800MB
LAYER FROM THE CENTRAL PLAINS INTO WESTERN AND CENTRAL WISCONSIN
WHERE A WIDESPREAD CU FIELD FORMED MIDDAY. AREA RADARS SHOWED A FEW CELLS
POPPED UP THIS MORNING OVER IOWA BUT HAVE SINCE FIZZLED. NO OTHER
SIGNS OF SHOWERS POPPING DESPITE INHIBITION ERODING. AS THE FRONT
MOVES INTO THE REGION TOMORROW...SEVERE WEATHER CHANCES IS THE MAIN
FORECAST CONCERN.
TONIGHT...LOW LEVEL MOISTURE AXIS WILL INITIALLY EXTEND FROM CENTRAL
IOWA TO NORTH-CENTRAL WISCONSIN AT THE START OF THE PERIOD. WITH
SCT TO BKN 5-7KFT CIGS UPSTREAM...WILL KEEP SKIES SCT FOR A GOOD
PART OF THE NIGHT. HAVE NOT SEEN MORE SPECKLES ON RADAR ASSOCIATED
WITH THIS MOISTURE TRANSPORT REGIME...SO WILL STICK WITH A DRY
FORECAST DESPITE FORECAST SOUNDINGS SHOWING 1300 J/KG OF ELEVATED
CAPE. THE MOISTURE AXIS WILL SHIFT EAST THROUGH THE NIGHT AND REACH
EAST-CENTRAL AND NORTHEAST WISCONSIN AFTER MIDNIGHT. SO SHOULD SEE
SOME CLEARING OVER WESTERN SECTIONS AND AN INCREASE OF CLOUDS OVER
EASTERN WISCONSIN LATE. A WARM SOUTHWEST BREEZE AND INCREASING
MOISTURE WILL KEEP CONDITIONS MUGGY. LOWS MAINLY IN THE 60S.
WEDNESDAY...THE DAY WILL START OUT QUIET...AS THE MOISTURE AXIS
SHIFTS SOUTHEAST OF THE REGION...WHILE THE THERMAL AXIS ARRIVES
AHEAD OF A COLD FRONT WHICH WILL MOVE INTO NORTHWEST WISCONSIN BY
18Z. TEMPS SHOULD NOT HAVE MUCH OF A PROBLEM RISING INTO THE UPPER
80S TO LOW 90S AHEAD OF THE FRONT WEDNESDAY AFTERNOON. SOME HEAT
INDICES WILL LIKELY REACH INTO THE MIDDLE 90S. BUT THE BIGGER STORY
IS SEVERE WEATHER CHANCES WEDNESDAY AFTERNOON. THE COLD FRONT WILL
PUSH INTO NORTH-CENTRAL WISCONSIN MID TO LATE AFTERNOON DURING THE
TIME OF PEAK HEATING. THOUGH HEIGHT FALLS WILL EXIST WELL BEHIND
THE FRONT...CONVERGENCE AND FGEN ALONG THE FRONT LOOK DECENT. SOME
POTENTIAL FOR DEWPOINTS TO MIX OUT INTO THE MIDDLE 60S AHEAD OF THE
FRONT BUT THAT SHOULD NOT HURT INSTABILITY TOO MUCH. MODIFYING A NAM
PROGGED SOUNDING AT 21Z NEAR RHINELANDER USING A 88/68 PARCEL YIELDS
NEARLY 3500 J/KG OF ML CAPE. IF DEWPOINTS DO MIX OUT INTO THE MID
60S...INSTABILITY WILL DROP TO 2500 J/KG. FREEZING LEVELS ARE QUITE
HIGH AT 14.5 KFT...BUT MID-LEVEL LAPSE RATES OF 6.5-7 C/KM AND
PLENTY OF CAPE SAYS THAT LARGE HAIL IS ALSO A THREAT IN ADDITION TO
DAMAGING WINDS. 0-6KM BULK SHEAR IS 25-30 KTS WHICH SUGGESTS
MULTI-CELLS TO SOME SMALL BOWS ARE POSSIBLE. TIMING WISE...LOOKING
AT A MID AFTERNOON FOR N-C WISCONSIN...AND LATE AFTERNOON TO EARLY
EVENING OVER CENTRAL AND FAR NORTHEAST WISCONSIN.
.LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY
ISSUED AT 230 PM CDT TUE AUG 20 2013
LITTLE CHANGE WITH THE GOING FORECAST FOR WEDNESDAY NIGHT WITH
RESPECT TO THE POTENTIAL OF STRONG TO SEVERE STORMS. PLENTY OF
INSTABILITY WITH CAPES BETWEEN 2000 TO 3000 J/KG AVAILABLE ALONG
AND AHEAD OF A COLD FRONT DROPPING OVER THE GREAT LAKES REGION.
SHORT WAVE TROUGH DIVING INTO THE NORTHERN GREAT LAKES REGION WITH
A RRQ REGION OF A JET WILL BE ASSOCIATED WITH THE FRONTAL PASSAGE.
INCREASING W/NW MID LEVEL WINDS LATER AFTERNOON AND EVENING WILL
PROVIDE SOME DEEPER SHEAR WITH THE FRONT. DAMAGING WINDS AND HAIL
THE PRIMARY THREATS. PWATS NEAR 1.85 INCHES AHEAD AND ALONG THE
FRONT AND HEAVY RAIN FALL POSSIBLE AFTERNOON AND EVENING NEAR THE
RRQ REGION OF THE JET ACROSS THE NORTH IF STORMS TRAIN FOR A
PERIOD OF TIME.
HIGH PRESSURE DRIFTING OVER THE STATE THURSDAY INTO FRIDAY WILL
PROVIDE QUIET CONDITIONS ALONG WITH NEAR NORMAL TEMPERATURES AND A
DRIER AIR MASS.
WARM AND MORE HUMID AIR TO RETURN AGAIN THIS WEEKEND AND INTO
EARLY NEXT WEEK...AS THE UPPER RIDGE BUILDS INTO THE NORTHERN
PLAINS AND GREAT LAKES REGION. MDM RANGE MODELS IN GENERAL WERE
MAINLY FOCUSING PERIODS OF CONVECTION ON THE PERIMETER OF THE
RIDGE WITH PWATS INCREASING TO 1.50 TO 2.00 OVER THE NORTHERN
GREAT LAKES REGION. WITH THE RETURN OF AN UNSTABLE AIR MASS ALONG
WITH A CAP EDGE LOOMING NEAR OR OVER NORTHERN WISCONSIN...POTENTIAL
OF AT LEAST STRONG STORMS FOR LATER INTO THE WEEKEND AND INTO NEXT
WEEK FOR PART OF THE FORECAST AREA.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1208 PM CDT TUE AUG 20 2013
SCATTERED TO BROKEN CUMULUS CLOUDS WITH BASES BETWEEN
5000 AND 7000 FEET WILL MOVE ACROSS CENTRAL AND NORTH-CENTRAL
WISCONSIN THIS AFTERNOON AND INTO EAST-CENTRAL AND NORTHEAST
WISCONSIN TONIGHT. MOSTLY VFR TONIGHT THOUGH OUTSIDE OF ANY GROUND
FOG OR HAZE THAT FORMS TOWARD DAWN. A COLD FRONT WILL PRODUCE A LINE
OF STRONG SHOWERS AND THUNDERSTORMS WEDNESDAY AFTERNOON AND EVENING
AS IT MOVES ACROSS THE REGION.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......TDH
AVIATION.......MPC
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1211 PM CDT TUE AUG 20 2013
.UPDATE...
HIGH TEMPERATURES COULD BE A DEGREE OR TWO WARMER. ECMWF 925 MB
TEMPS AROUND 23 C WOULD SUPPORT A HIGH OF 85...BUT RAP AND NAM
SHOWING WE COULD BE A BIT WARMER. TEMPERATURES ACROSS THE AREA ARE
ALREADY IN THE LOWER 80S FOR THE MOST PART. ALSO...WE/VE ALREADY
SEEN A GOOD DEAL OF SUNSHINE AND WITH A GENERAL LACK OF MOISTURE WE
MIGHT SEE A BIT MORE SUNSHINE THEN EXPECTED...EVEN WITH SOME CAPE.
&&
.AVIATION/18Z TAFS/...
VFR CONDITIONS WILL CONTINUE THROUGHOUT THE DAY...WITH FEW OR SCT
PATCHY CUMULUS CLOUDS DEVELOPING. ADDITIONAL MOISTURE MOVING IN
FROM THE WEST LATER TONIGHT INTO TOMORROW MORNING COULD BRING A
MORE SOLID CLOUD DECK...BUT IT WOULD STILL BE ABOVE 3000 FT.
SOUTH OR SOUTHWEST WINDS WILL CONTINUE THROUGHOUT THE PERIOD.
PRECIP CHANCES LOOK LIKE THEY WILL HOLD OFF UNTIL AFTER 21Z
WEDNESDAY AT MSN AND 00Z THURSDAY AT MKE.
&&
.PREV DISCUSSION... /ISSUED 347 AM CDT TUE AUG 20 2013/
TODAY AND TONIGHT...FORECAST CONFIDENCE...HIGH
PATCHY FOG WITH SOME DENSE GROUND FOG IN THE RIVER VALLEYS AND USUAL
LOW AREAS EARLY THIS MORNING.
WEAK MID/UPPER LEVEL LOW WILL REMAIN NEARLY STATIONARY OVER ILLINOIS
TODAY BEFORE HEADING TO SOUTHERN INDIANA TONIGHT. MAIN MID/UPPER
JET EXTENDS ACROSS FAR SOUTHERN CANADA.
SOME MOISTURE SEEN ON THE NAM FORECAST SOUNDINGS AROUND 6 THSD FT
WITH A CAP AROUND 7 THSD FT. MID LEVELS REMAIN DRY AND WITH LITTLE
OR NO UPWARD MOTION THE 800 J/KG CAPE WILL LIKELY NOT BE ABLE TO
SUPPORT DEEP MOIST CONVECTION. THE NAM INCREASES THE 850 MB
MOISTURE TONIGHT ESPECIALLY OVER SOUTH CENTRAL WISCONSIN AND
WEAKENS/ELIMINATES THE CAP. THE SOUNDINGS HAVE AROUND 1600 J/KG OF
ELEVATED CAPE LIFTED FROM 5 THSD FT BUT AGAIN NO LIFTING MECHANISM.
WARMER AIRMASS STEADILY MOVING INTO THE REGION PER 925/850 MB
TEMPERATURE TRENDS. HOWEVER THE MAIN THERMAL RIDGE REMAINS TO THE
NORTHWEST.
SURFACE HIGH PRESSURE CENTERED OVER THE MID ATLANTIC STATES WITH A
WEAK SOUTH/SOUTHWEST LOW LEVEL FLOW. THEREFORE QUIET WEATHER IS
EXPECTED TO CONTINUE...WITH CONTINUED WARMING TEMPERATURES.
WEDNESDAY AND THURSDAY...FORECAST CONFIDENCE...MEDIUM
A COLD FRONT WILL APPROACH ON WEDNESDAY...WITH CURRENT MODEL
TIMING SUGGESTING MAINLY DRY WEATHER INTO THE AFTERNOON. GIVEN
THIS...KEPT WARM TEMPS AROUND 90 WITH SOUTHWEST WINDS AND SOME
SUNSHINE EXPECTED.
SOME TIMING DIFFERENCES WITH THE FRONT AND PRECIP CHANCES LATE
AFTERNOON INTO THE NIGHT. THE 00Z GFS AND NAM WERE A BIT QUICKER
THAN THE ECMWF AND CANADIAN...WITH STORMS IN THE NORTH BY EVENING.
INCREASED POPS A BIT LATE AFTERNOON...WITH SHOWERS THEN LIKELY
EVENING AND OVERNIGHT AS THE FRONT MOVES THROUGH. STORMS COULD
APPROACH OR REACH SEVERE LIMITS...LIKELY DEPENDING ON THE TIMING
OF THE FRONT AND REMAINING INSTABILITY. SPC DAY 2 CONVECTIVE
OUTLOOKS HIGHLIGHTS MOST OF THE CWA IN A SLIGHT RISK FOR SEVERE
STORMS.
COULD SEE A FEW LINGERING SHOWERS OR STORMS THURSDAY...MAINLY
DURING THE MORNING HOURS. WENT WITH A CONSENSUS OF MODEL HIGH
TEMPS FOR THURSDAY...AS MODELS NOT IN GREAT AGREEMENT WITH THE
EXTENT OF POST-FRONTAL COOLING.
FRIDAY THROUGH MONDAY...FORECAST CONFIDENCE...MEDIUM
HIGH PRESSURE IS EXPECTED TO BRING PLEASANT WEATHER FRIDAY...WITH
MOSTLY SUNNY SKIES AND NEAR NORMAL TEMPERATURES LIKELY.
MODELS DEPICT A WEAK SHORTWAVE SATURDAY...BUT NOT LOOKING
SUBSTANTIAL ENOUGH FOR POPS AT THIS TIME. DRY WEATHER WILL LIKELY
CONTINUE SUNDAY WITH GFS AND ECMWF SHOWING THE AXIS OF THE UPPER
RIDGE MOVING OVERHEAD. WILL PROBABLY SEE TEMPS CLIMB BACK ABOVE
NORMAL UNDER THE RIDGE.
THE LATEST ECMWF SHOWS A FRONT DROPPING THROUGH MONDAY...THOUGH
THE GFS MAINTAINS THE RIDGE AND WARM TEMPS SIMILAR TO THE
PREVIOUS ECMWF. KEPT THINGS MAINLY DRY FOR NOW...WITH ABOVE NORMAL
TEMPS CONTINUING.
AVIATION/12Z TAFS/...
PATCHY IFR/LIFR MAINLY IN RIVER VALLEYS AND LOW AREAS. AREAS OF MVFR
HAZE/FOG TIL AN HOUR OR TWO AFTER SUNRISE. THEN VFR CONDITIONS
EXPECTED TODAY AND THIS EVENING.
SCATTERED FAIR WEATHER DIURNAL CUMULUS EXPECTED LATE THIS MORNING
AND AFTERNOON.
SURFACE HIGH PRESSURE CENTERED OVER THE MID ATLANTIC STATES WITH A
WEAK SOUTH/SOUTHWEST LOW LEVEL FLOW.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...MEB
TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
WEDNESDAY THROUGH MONDAY...DDV
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1201 PM CDT TUE AUG 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 351 AM CDT TUE AUG 20 2013
MAIN FORECAST CONCERNS ARE ON THUNDERSTORM CHANCES WEDNESDAY INTO
THURSDAY AND HIGH TEMPERATURES LATE IN THE WEEKEND INTO EARLY NEXT
WEEK.
LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED A
SHORTWAVE TROUGH OVER SOUTHERN WISCONSIN AND NORTHERN
ILLINOIS...DRIFTING SOUTH. RIDGING WAS MOVING INTO THE UPPER
MISSISSIPPI RIVER VALLEY PROVIDING MOSTLY CLEAR TO PARTLY CLOUDY
SKIES AND QUIET CONDITIONS OVER THE AREA. SURFACE OBSERVATIONS
SHOWED A COLD FRONT EXTENDING FROM SOUTHERN MANITOBA THROUGH
WESTERN NORTH DAKOTA INTO EASTERN WYOMING WITH A BROAD HIGH
CENTERED OVER THE OHIO RIVER VALLEY. THE FORECAST AREA IS LOCATED
BETWEEN THESE TWO FEATURES WITH WARM SOUTHERLY FLOW ACROSS THE
REGION.
THE SHORTWAVE TROUGH WILL CLOSE INTO A WEAK UPPER LOW OVER ILLINOIS
TODAY. MEANWHILE...THE COLD FRONT WILL DRIFT SOUTHEAST AND BY LATE
THIS AFTERNOON IS EXPECTED TO STRETCH FROM NORTHWEST MINNESOTA
THROUGH EASTERN NORTH DAKOTA INTO CENTRAL SOUTH DAKOTA. THE UPPER
LEVEL RIDGING SHOULD WIN OUT TODAY PROVIDING PARTLY TO MOSTLY
SUNNY SKIES. INTERESTING TO NOTE THAT AFTERNOON MLCAPE VALUES
CLIMB TO 2500 TO 3500 J/KG THIS AFTERNOON ACROSS MUCH OF THE
FORECAST AREA. WITHOUT ANY REAL TRIGGER TO GET CONVECTION TO FIRE
THINKING THE AREA SHOULD REMAIN DRY THROUGH THE DAY. WILL HAVE TO
KEEP A CLOSE EYE ON THE POTENTIAL FOR AN ISOLATED SHOWER OR STORM
UNDER PEAK HEATING LATE THIS AFTERNOON. PLAN ON HIGH TEMPERATURES
CLIMBING INTO THE UPPER 80S TO AROUND 90. THE COLD FRONT WILL
CONTINUE ITS SOUTHEAST MOVEMENT TONIGHT INTO WEDNESDAY MORNING.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 351 AM CDT TUE AUG 20 2013
THE COLD FRONT WILL BE POSITIONED FROM FAR NORTHWEST WISCONSIN INTO
EXTREME NORTHWEST IOWA EARLY WEDNESDAY MORNING. FORECAST MODELS ARE
SHOWING SOME DIFFERENCES ON WHEN THE FRONT WILL MOVE INTO THE
FORECAST AREA. THE NAM OFFERS THE FASTEST SOLUTION BRINGING THE
FRONT INTO THE FORECAST AREA LATE WEDNESDAY MORNING...SHIFTING
SOUTH OF THE INTERSTATE 90 CORRIDOR WEDNESDAY EVENING AND STALLING
OVER NORTHERN IOWA/ILLINOIS. THE ECMWF HAS THE SLOWEST SOLUTION
AND DOESN/T BRING THE FRONT INTO THE FORECAST AREA UNTIL WEDNESDAY
EVENING. THE ECMWF SOLUTION SUGGESTS THAT A SHORTWAVE WILL TRIGGER
SHOWERS AND STORMS OVER NORTHWEST WISCONSIN WEDNESDAY
AFTERNOON...SPREADING SOUTHEAST DURING THE LATE AFTERNOON AND
EVENING HOURS. SHOWERS AND STORMS THEN FIRE ALONG THE FRONT
THROUGH THE OVERNIGHT HOURS WITH THE FRONT FINALLY PUSHING SOUTH
OF THE AREA BY EARLY THURSDAY AFTERNOON. THERE REMAINS TIMING
ISSUES TO WORK OUT...BUT THINKING THERE REMAINS A CHANCE OF SEEING
SEVERE THUNDERSTORMS ON WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT.
0-6KM BULK SHEAR IS THE MOST FAVORABLE FOR SEVERE STORMS OVER
NORTH CENTRAL WISCONSIN...WHERE VALUES RANGE FROM 30 TO 40 KTS.
PLENTY OF INSTABILITY TO WORK WITH AHEAD OF THE FRONT WITH MLCAPE
VALUES CLIMBING TO AROUND 2000 J/KG. THE MAIN THREATS FROM THE
STORMS WILL BE LARGE HAIL AND DAMAGING WINDS. SHEAR IS VERY
MARGINAL AT BEST OVER SOUTHEAST MINNESOTA...NORTHEAST IOWA...AND
SOUTHWEST WISCONSIN...BUT THINKING THE STRONG INSTABILITY WILL BE
ENOUGH TO OVERCOME THE LACK OF STRONG SHEAR. THE FRONT FINALLY
SHIFTS SOUTH OF THE AREA LATE ON THURSDAY AS HIGH PRESSURE BUILDS
IN. THE FRONT ATTEMPTS TO LIFT NORTH AS A WARM FRONT ON FRIDAY
GENERATING SOME SHOWERS AND STORMS ALONG IT. LATEST GUIDANCE
SUGGESTS THAT THE FRONT WASHES OUT AS A SURFACE HIGH HOLDS STRONG
OVER THE WESTERN GREAT LAKES. UPPER RIDGE THEN BUILDS OVER THE
REGION SATURDAY INTO SUNDAY WITH WARMING TEMPERATURES EXPECTED.
WILL HAVE TO KEEP A CLOSE EYE ON SHORTWAVES ROTATING THROUGH THE
NORTHERN PERIPHERY OF THE RIDGE OVER NORTHERN WISCONSIN WHERE
SHOWERS STORMS WILL BE POSSIBLE. 850 MB STANDARDIZED ANOMALIES
CLIMB TO PLUS 2 ON SUNDAY...SUGGESTING THE POTENTIAL FOR NEAR
RECORD HIGH TEMPERATURES. 925 MB TEMPERATURES WARM TO 28 C ON
SUNDAY BEFORE ANOTHER COLD FRONT SLIPS SOUTH THROUGH THE REGION ON
MONDAY. HIGHS ON SUNDAY AND MONDAY SHOULD CLIMB INTO THE UPPER 80S
TO LOWER 90S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1201 PM CDT TUE AUG 20 2013
SOME MID LEVEL CLOUDS EXPECTED TO REMAIN OVER THE AREA INTO THE
EARLY EVENING IN A BROAD AREA OF LOW LEVEL WARM AIR ADVECTION.
WOULD NOT BE SURPRISED IF A SHOWER OR TWO POPPED UP IN THIS WARM
AIR ADVECTION...BUT IF THEY DO...WOULD THINK THEY WOULD BE TOO
ISOLATED TO MAKE IT WORTH EVEN INCLUDING A VCSH AT THIS POINT. VFR
CONDITIONS EXPECTED FOR THE REMAINDER OF THE PERIOD AS A COLD
FRONT SLOWLY APPROACHES FROM THE NORTHWEST. WARM AIR SPREADING IN
AHEAD OF THE COLD FRONT WILL CAP OFF THE LOW LEVELS SO ONLY SOME
HIGH LEVEL CLOUDS EXPECTED TO START SPILLING IN WEDNESDAY MORNING.
THE GRADIENT WILL START TO TIGHTEN WEDNESDAY MORNING TO PUSH
SUSTAINED SPEEDS OVER 10 KNOTS BUT THE LOW LEVEL INVERSION WILL
NOT MIX OUT UNTIL AFTERNOON WHEN IT SHOULD GET GUSTY AS WELL.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...04