Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/05/13
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
250 PM MST TUE SEP 3 2013
.SYNOPSIS...
A WEATHER DISTURBANCE WILL LEAD TO A SOMEWHAT ELEVATED CHANCE OF
SHOWERS AND THUNDERSTORMS TODAY AND TONIGHT. THE BEST CHANCE OF
THUNDERSTORMS WILL BE OVER THE HIGHER TERRAIN OF SOUTH CENTRAL
ARIZONA. THE REMAINDER OF THE WORK WEEK WILL HAVE ONLY SLIGHT
CHANCES FOR THUNDERSTORMS ALONG WITH SOMEWHAT ABOVE NORMAL
TEMPERATURES. SATURDAY THROUGH MONDAY...STORM CHANCES WILL BE
CONFINED EAST OF THE LOWER COLORADO RIVER VALLEY.
&&
.DISCUSSION...
REST OF TODAY AND TONIGHT...
KIWA RADAR DATA COMMS LINE NOW REPAIRED. STORM ACTIVITY SO FAR THIS
AFTERNOON HAS ESSENTIALLY BEEN OVER EASTERN ARIZONA...MAINLY IN A
NORTH-SOUTH CORRIDOR FROM THE WESTERN MOGOLLON RIM DOWN THROUGH
EASTERN PIMA COUNTY. THIS CORRESPONDS WELL WITH NAM FORECASTS OF
MOST FAVORABLE AREA...DRIVEN BY UPPER DIVERGENCE AHEAD OF
APPROACHING SHORT WAVE FROM THE EAST...AS WELL AS TIMING. WITH DEW
POINTS IN THE MID 50S OVER THE LOWER DESERTS OF CENTRAL ARIZONA...IT
WILL BE DIFFICULT TO GET A LOT OF STORMS TO SURVIVE OFF THE HIGHER
TERRAIN. EARLIER RUNS OF THE HRRR MODEL LOOK TO BE OVERDONE...SO
FAR...AND NOW LATEST RUN IS LESS ENTHUSIASTIC ABOUT STORM COVERAGE.
HOWEVER...WIND PRODUCTION SHOULD BE EFFICIENT AND THUS ADDED MENTION
OF BLOWING DUST TO THE CENTRAL DESERT ZONES...INCLUDING PHOENIX.
STILL ENOUGH FORCING AND UPSTREAM STORMS TO KEEP CHANCE WORDING...AS
OPPOSED TO SLIGHT CHANCE. FOR OUR WESTERN AREAS...WHERE MOISTURE IS
RICHER...ANTICIPATE LESS ACTION THAN LAST NIGHT GIVEN THAT THE
REMNANT WAVE FROM FORMER T.S. KIKO HAS PASSED. HOWEVER...HIGHER
TERRAIN OF SAN DIEGO AND WESTERN RIVERSIDE COUNTIES AS WELL AS
MOUNTAINS OF NORTHERN BAJA DO HAVE SOME STORMS WHICH CAN SEND
OUTFLOWS TO TRIGGER NEW STORMS. THE WAVE WILL BE MOVING SLOW ENOUGH
THAT THERE COULD BE SPOTTY LINGERING SHOWER ACTIVITY OVERNIGHT.
WEDNESDAY THROUGH MONDAY...
THE SHORT WAVE MAY KEEP WEAK ACTIVITY GOING OVER SOUTHEAST
CALIFORNIA AND SOUTHWEST ARIZONA WEDNESDAY BUT CAPE WILL BE QUIET
MODEST. BOTH NAM AND GFS SHOW A DECLINE OF MOISTURE...EVIDENT IN
1000-500 MB MEAN MIXING RATIOS...BUT THE GFS IS MORE AGGRESSIVE THAN
THE NAM. THUS ONLY SLIGHT CHANCES WILL PREVAIL...DESPITE A
CLIMATOLOGICALLY FAVORABLE WIND FLOW PATTERN. SHORT WAVES EMANATING
FROM MEXICO WILL BE SOMETHING OF AN X FACTOR...MOST NOTABLY FRIDAY.
OVER THE WEEKEND...GFS DEPICTS THE PERSISTENT TROUGHING NEAR THE
WEST COAST TO SHIFT INLAND BUT THE RIDGE AXIS STAYS JUST FAR ENOUGH
NORTH TO KEEP MOISTURE FROM GOING AWAY ENTIRELY. THE ECWMF BRINGS IN
A BUNCH OF MOISTURE ASSOCIATED WITH TROPICAL REMNANTS. WAY TOO EARLY
TO BUY OFF ON THE LATTER SCENARIO BUT WILL HOLD ON TO LOW GRADE
MONSOON WITH POPS BEING CONFINED TO AREAS EAST OF THE LOWER COLORADO
RIVER VALLEY SATURDAY THROUGH MONDAY.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...
SHOWER AND SOME THUNDERSTORMS ARE NOW DEVELOPING ACROSS FAR EASTERN
ARIZONA AND NEAR TUCSON AS OF JUST AFTER NOON. EXPECTING THIS
ACTIVITY TO BECOME MORE WIDESPREAD THROUGHOUT THE AFTERNOON AS IT
MOVES TO THE WEST AND LIKELY AFFECTING THE METRO PHOENIX AREA
BETWEEN 00-04Z TODAY. EXPECT BLOWING DUST FROM STORM
OUTFLOWS...GUSTY WINDS AND HEAVY RAIN POSSIBLE WITH STORMS THAT DO
DEVELOP THIS EVENING.
SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...
EXPECT TODAY TO BE QUIETER IN TERMS OF WEATHER COMPARED TO YESTERDAY
WITH STORM DEVELOPMENT MAINLY FOCUSED ACROSS CENTRAL ARIZONA LATER
THIS AFTERNOON AND EVENING. THIS ACTIVITY COULD DRIFT NEAR THE KBLH
TERMINAL THROUGH THE EVENING.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
DRIER AIR ACROSS THE REGION WILL LIKELY KEEP MOST THUNDERSTORM
ACTIVITY CONFINED TO THE HIGHER TERRAIN EAST OF PHOENIX...WITH JUST
SOME ISOLATED STORMS POSSIBLE INTO THE DESERTS EACH AFTERNOON AND
EVENING. HUMIDITIES EACH AFTERNOON WILL DROP INTO THE UPPER TEENS TO
MIDDLE TWENTIES PERCENT RANGE ACROSS THE LOWER DESERTS...WITH GOOD
OVERNIGHT RECOVERY ANTICIPATED. OUTSIDE OF THUNDERSTORMS...WINDS
WILL FAVOR THE TYPICAL DIURNAL UPSLOPE/DOWNVALLEY PATTERNS. MEDIUM
RANGE FORECAST MODELS BEGIN TO DIVERGE BY THE LATE WEEKEND WITH
REGARDS TO THE UPPER LEVEL PATTERN AND AMOUNT OF MONSOON MOISTURE
ACROSS THE REGION. WILL CONTINUE TO MONITOR THE EVOLUTION OF THE
PATTERN AND ANY POTENTIAL FIRE WEATHER IMPACTS OVER THE NEXT FEW
PERIODS. WITH THE DEEP MOISTURE FORECAST TO MOVE INTO THE REGION BY
ONE MODEL...HUMIDITIES AND RAINFALL CHANCES COULD SEE A HEALTHY
BOOST BY THE LATE WEEKEND.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...AJ
AVIATION...KUHLMAN
FIRE WEATHER...NOLTE/KUHLMAN
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
1233 PM MST TUE SEP 3 2013
.UPDATE...UPDATED AVIATION DISCUSSION.
&&
.SYNOPSIS...
MONSOON MOISTURE CONTINUES TO BE SPREAD OVER THE REGION...WITH A
CHANCE OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS TODAY AND
TONIGHT. THE BEST CHANCE OF THUNDERSTORMS WILL BE OVER SOUTH CENTRAL
ARIZONA...INCLUDING PHOENIX...AS A WEATHER DISTURBANCE MOVING OUT OF
WEST TEXAS HELPS TO INCREASE THE THUNDERSTORMS THREAT TODAY AND
TONIGHT. THE REMAINDER OF THE WEEK AND UPCOMING WEEKEND WITH SEE A
REDUCED THREAT OF THUNDERSTORMS...ALONG WITH WARMER AFTERNOON
TEMPERATURES.
&&
.DISCUSSION...
CLEAR SKIES AS OF MID MORNING OVER THE FORECAST AREA IS ALLOWING
SURFACE HEATING TO PROGRESS. SATELLITE IMAGERY SHOWS A NORTH-SOUTH
ORIENTED BAND OF CLOUDINESS NEAR THE AZ/NM BORDER AND APPEARS TO BE
ASSOCIATED WITH A DIFLUENT AREA AHEAD OF AN APPROACHING SHORT WAVE
CURRENTLY OVER FAR WEST TEXAS. A LARGER INVERTED TROUGH IS CENTERED
WELL SOUTHEAST OF THAT. MOISTURE TRENDS OVERNIGHT AND THIS MORNING
HAVE BEEN A MIXED BAG WHEN LOOKING AT GPS IPW DATA. BOTH THE NAM AND
GFS SHOW 1000-700 MB MEAN MIXING RATIOS DECREASING DURING THE DAY
DESPITE THE ARRIVAL OF THE SHORT WAVE...THOUGH SOME OF THAT MAY BE
ATTRIBUTED TO THE DIURNAL CYCLE. BOTH MODELS HAVE THE AXIS OF THE
SHORT WAVE AT 250 MB CLOSE TO THE AZ/NM BORDER AT 00Z THIS
AFTERNOON. THEY ALSO SHOW A BATCH OF UPPER LEVEL DIVERGENCE OVER
EASTERN PORTIONS OF THE FORECAST AREA...MAINLY ZONE 24 DEVELOPING
THIS AFTERNOON. THE NAM A BIT FASTER...21Z...THAN THE GFS...00Z.
HOWEVER...IT APPEARS TO BE RELATIVELY SHORT LIVED AND DISSIPATES
OVER SOUTHEAST ARIZONA DURING THE EVENING. DIVERGENCE FIELDS NOT
OVERLY IMPRESSIVE BUT SHOULD HELP MAKE STORM DEVELOPMENT EASIER OVER
THE HIGHER TERRAIN. HRRR MODEL SHOWS ISOLATED STORM DEVELOPMENT OVER
OUR AREA THIS AFTERNOON BEFORE BECOMING MORE WIDESPREAD THIS EVENING
OVER SOUTH-CENTRAL ARIZONA. MEANWHILE...BOTH THE 06Z VERSIONS OF THE
NMM6KM AND LOCAL WRF SHOW VERY LITTLE FOR THIS AFTERNOON/EVENING.
SAME IS TRUE FOR RUC/RAP. THIS LOOKS UNDERDONE AND THUS PLAN ON
HOLDING ON TO ELEVATED POPS FOR TONIGHT. WILL CONTINUE TO EVALUATE.
&&
.PREVIOUS DISCUSSION ISSUED AT 300 AM...
TODAY AND TONIGHT...
MONSOON MOISTURE CONTINUED TO BE SPREAD OVER THE REGION THIS
MORNING...WITH ANOTHER THREAT OF AFTERNOON AND EVENING THUNDER-
STORMS. HOWEVER THE BEST CHANCE OF STORMS WILL DEVELOP OVER SOUTH
CENTRAL ARIZONA...INCLUDING PHOENIX AND CASA GRANDE...AS AN INVERTED
TROF FROM WEST TEXAS MOVES INTO SOUTHEAST AZ THIS AFTERNOON AND
EVENING. THIS FEATURE CAN BE SEEN IN WATER VAPOR IMAGERY THIS
MORNING...WITH THE NORTH/SOUTH BAND OF CLOUDS AND ISOLATED
THUNDERSTORMS IN WESTERN NEW MEXICO HIGHLIGHTING THE DEFORMATION
ZONE ASSOCIATED WITH ITS LEADING EDGE. THEREFORE THE HIGHEST PRECIP
PROBABILITIES TODAY ARE FORECAST IN SOUTH CENTRAL ARIZONA. IT IS
ALSO EXPECTED THAT CONSIDERABLE CONVECTIVE DEBRIS CLOUDS AND
ISOLATED SHOWERS/THUNDERSTORMS WILL CONTINUE TO MOVE WESTWARD...AND
INTO PORTIONS OF SOUTHWEST ARIZONA OVERNIGHT.
WEDNESDAY THROUGH MONDAY...
WE WILL BE SHIFTING INTO A SLIGHTLY DRIER AND MORE STABLE FLOW
REGIME THIS PERIOD. HOWEVER A FEW WEAK UPPER LEVEL PERTURBATIONS ARE
FORECAST TO MOVE INTO AZ FROM NORTHWEST MEXICO SOMETIME THU OR FRI.
THEREFORE WE WILL GO WITH A LOW GRADE MONSOON...MEANING ONLY A
SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...
SHOWER AND SOME THUNDERSTORMS ARE NOW DEVELOPING ACROSS FAR EASTERN
ARIZONA AND NEAR TUCSON AS OF JUST AFTER NOON. EXPECTING THIS
ACTIVITY TO BECOME MORE WIDESPREAD THROUGHOUT THE AFTERNOON AS IT
MOVES TO THE WEST AND LIKELY AFFECTING THE METRO PHOENIX AREA
BETWEEN 00-04Z TODAY. EXPECT BLOWING DUST FROM STORM
OUTFLOWS...GUSTY WINDS AND HEAVY RAIN POSSIBLE WITH STORMS THAT DO
DEVELOP THIS EVENING.
SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...
EXPECT TODAY TO BE QUIETER IN TERMS OF WEATHER COMPARED TO YESTERDAY
WITH STORM DEVELOPMENT MAINLY FOCUSED ACROSS CENTRAL ARIZONA LATER
THIS AFTERNOON AND EVENING. THIS ACTIVITY COULD DRIFT NEAR THE KBLH
TERMINAL THROUGH THE EVENING.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
DRIER AIR ACROSS THE REGION WILL LIKELY KEEP MOST THUNDERSTORM
ACTIVITY CONFINED TO THE HIGHER TERRAIN EAST OF PHOENIX...WITH JUST
SOME ISOLATED STORMS POSSIBLE INTO THE DESERTS EACH AFTERNOON AND
EVENING. HUMIDITIES EACH AFTERNOON WILL DROP INTO THE UPPER TEENS TO
MIDDLE TWENTIES PERCENT RANGE ACROSS THE LOWER DESERTS...WITH GOOD
OVERNIGHT RECOVERY ANTICIPATED. OUTSIDE OF THUNDERSTORMS...WINDS
WILL FAVOR THE TYPICAL DIURNAL UPSLOPE/DOWNVALLEY PATTERNS. MEDIUM
RANGE FORECAST MODELS BEGIN TO DIVERGE BY THE LATE WEEKEND WITH
REGARDS TO THE UPPER LEVEL PATTERN AND AMOUNT OF MONSOON MOISTURE
ACROSS THE REGION. WILL CONTINUE TO MONITOR THE EVOLUTION OF THE
PATTERN AND ANY POTENTIAL FIRE WEATHER IMPACTS OVER THE NEXT FEW
PERIODS. WITH THE DEEP MOISTURE FORECAST TO MOVE INTO THE REGION BY
ONE MODEL...HUMIDITIES AND RAINFALL CHANCES COULD SEE A HEALTHY
BOOST BY THE LATE WEEKEND.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...AJ
PREVIOUS DISCUSSION...VASQUEZ
AVIATION...KUHLMAN
FIRE WEATHER...NOLTE/KUHLMAN
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
1030 AM MST TUE SEP 3 2013
.SYNOPSIS...
MONSOON MOISTURE CONTINUES TO BE SPREAD OVER THE REGION...WITH A
CHANCE OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS TODAY AND
TONIGHT. THE BEST CHANCE OF THUNDERSTORMS WILL BE OVER SOUTH CENTRAL
ARIZONA...INCLUDING PHOENIX...AS A WEATHER DISTURBANCE MOVING OUT OF
WEST TEXAS HELPS TO INCREASE THE THUNDERSTORMS THREAT TODAY AND
TONIGHT. THE REMAINDER OF THE WEEK AND UPCOMING WEEKEND WITH SEE A
REDUCED THREAT OF THUNDERSTORMS...ALONG WITH WARMER AFTERNOON
TEMPERATURES.
&&
.DISCUSSION...
CLEAR SKIES AS OF MID MORNING OVER THE FORECAST AREA IS ALLOWING
SURFACE HEATING TO PROGRESS. SATELLITE IMAGERY SHOWS A NORTH-SOUTH
ORIENTED BAND OF CLOUDINESS NEAR THE AZ/NM BORDER AND APPEARS TO BE
ASSOCIATED WITH A DIFLUENT AREA AHEAD OF AN APPROACHING SHORT WAVE
CURRENTLY OVER FAR WEST TEXAS. A LARGER INVERTED TROUGH IS CENTERED
WELL SOUTHEAST OF THAT. MOISTURE TRENDS OVERNIGHT AND THIS MORNING
HAVE BEEN A MIXED BAG WHEN LOOKING AT GPS IPW DATA. BOTH THE NAM AND
GFS SHOW 1000-700 MB MEAN MIXING RATIOS DECREASING DURING THE DAY
DESPITE THE ARRIVAL OF THE SHORT WAVE...THOUGH SOME OF THAT MAY BE
ATTRIBUTED TO THE DIURNAL CYCLE. BOTH MODELS HAVE THE AXIS OF THE
SHORT WAVE AT 250 MB CLOSE TO THE AZ/NM BORDER AT 00Z THIS
AFTERNOON. THEY ALSO SHOW A BATCH OF UPPER LEVEL DIVERGENCE OVER
EASTERN PORTIONS OF THE FORECAST AREA...MAINLY ZONE 24 DEVELOPING
THIS AFTERNOON. THE NAM A BIT FASTER...21Z...THAN THE GFS...00Z.
HOWEVER...IT APPEARS TO BE RELATIVELY SHORT LIVED AND DISSIPATES
OVER SOUTHEAST ARIZONA DURING THE EVENING. DIVERGENCE FIELDS NOT
OVERLY IMPRESSIVE BUT SHOULD HELP MAKE STORM DEVELOPMENT EASIER OVER
THE HIGHER TERRAIN. HRRR MODEL SHOWS ISOLATED STORM DEVELOPMENT OVER
OUR AREA THIS AFTERNOON BEFORE BECOMING MORE WIDESPREAD THIS EVENING
OVER SOUTH-CENTRAL ARIZONA. MEANWHILE...BOTH THE 06Z VERSIONS OF THE
NMM6KM AND LOCAL WRF SHOW VERY LITTLE FOR THIS AFTERNOON/EVENING.
SAME IS TRUE FOR RUC/RAP. THIS LOOKS UNDERDONE AND THUS PLAN ON
HOLDING ON TO ELEVATED POPS FOR TONIGHT. WILL CONTINUE TO EVALUATE.
&&
.PREVIOUS DISCUSSION ISSUED AT 300 AM...
TODAY AND TONIGHT...
MONSOON MOISTURE CONTINUED TO BE SPREAD OVER THE REGION THIS
MORNING...WITH ANOTHER THREAT OF AFTERNOON AND EVENING THUNDER-
STORMS. HOWEVER THE BEST CHANCE OF STORMS WILL DEVELOP OVER SOUTH
CENTRAL ARIZONA...INCLUDING PHOENIX AND CASA GRANDE...AS AN INVERTED
TROF FROM WEST TEXAS MOVES INTO SOUTHEAST AZ THIS AFTERNOON AND
EVENING. THIS FEATURE CAN BE SEEN IN WATER VAPOR IMAGERY THIS
MORNING...WITH THE NORTH/SOUTH BAND OF CLOUDS AND ISOLATED
THUNDERSTORMS IN WESTERN NEW MEXICO HIGHLIGHTING THE DEFORMATION
ZONE ASSOCIATED WITH ITS LEADING EDGE. THEREFORE THE HIGHEST PRECIP
PROBABILITIES TODAY ARE FORECAST IN SOUTH CENTRAL ARIZONA. IT IS
ALSO EXPECTED THAT CONSIDERABLE CONVECTIVE DEBRIS CLOUDS AND
ISOLATED SHOWERS/THUNDERSTORMS WILL CONTINUE TO MOVE WESTWARD...AND
INTO PORTIONS OF SOUTHWEST ARIZONA OVERNIGHT.
WEDNESDAY THROUGH MONDAY...
WE WILL BE SHIFTING INTO A SLIGHTLY DRIER AND MORE STABLE FLOW
REGIME THIS PERIOD. HOWEVER A FEW WEAK UPPER LEVEL PERTURBATIONS ARE
FORECAST TO MOVE INTO AZ FROM NORTHWEST MEXICO SOMETIME THU OR FRI.
THEREFORE WE WILL GO WITH A LOW GRADE MONSOON...MEANING ONLY A
SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL...
ISOLATED THUNDERSHOWER ACTIVITY WILL CONTINUE TO PERCOLATE NORTHWARD
ACROSS THE PHOENIX METRO THIS MORNING...GENERATING LIGHT SHOWER AND
VERY BRIEF VARIABLE BREEZINESS. THESE SHOWERS SHOULD DISSIPATE
THROUGH THE MID MORNING. EXPECT MOSTLY SCT CLOUD COVER TO LINGER
THROUGH THE DAY BEFORE MORE SUBSTANTIAL CB DEVELOPMENT COVERS THE
EASTERN AND SOUTHEASTERN HORIZONS. EARLY AFTERNOON WINDS MAY FAVOR
MORE SOUTHERLY HEADINGS THAN ANY WEST COMPONENT...ESPECIALLY FOR
KPHX. MEDIUM CONFIDENCE IN STORM ACTIVITY BUILDING AND MOVING INTO
PHOENIX THIS AFTERNOON...AND INTRODUCED VCSH FOR KPHX AND SHORT
WINDOWS OF VCTS FOR KIWA AND KSDL FOLLOWED BY ADDITIONAL VCSH AFTER
04/00Z. EXPECT BLOWING DUST FROM STORM OUTFLOWS...GUSTY WINDS AND
HEAVY RAIN POSSIBLE WITH STORMS THAT DO DEVELOP THIS EVENING.
SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...
LIGHT AND VARIABLE MORNING WINDS WILL TURN WESTERLY FOR KIPL AND
EASTERLY FOR KBLH THROUGH THE DAY. EXPECT SCT TO BKN CLOUD COVER TO
PERSIST THROUGH THE DAY WITH CIGS AOA 15KFT OR GREATER. GIVEN STORM
ACTIVITY ACROSS THE REGION MONDAY EVENING...EXPECT TODAY TO BE
QUIETER IN TERMS OF WEATHER...LEAVING MENTION OF WEATHER OUT OF KIPL
AND ONLY VCSH MENTION IN KBLH FOR THE LATE EVENING. STORM
DEVELOPMENT IS EXPECTED ACROSS CENTRAL ARIZONA LATER THIS AFTERNOON
AND EVENING AND MAY DRIFT NEAR THE KBLH TERMINAL THROUGH THE
EVENING.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
DRIER AIR ACROSS THE REGION WILL LIKELY KEEP MOST THUNDERSTORM
ACTIVITY CONFINED TO THE HIGHER TERRAIN EAST OF PHOENIX...WITH JUST
SOME ISOLATED STORMS MOVING INTO THE DESERTS EACH AFTERNOON AND
EVENING. HUMIDITIES EACH AFTERNOON WILL DROP INTO THE 20 TO 30
PERCENT RANGE ACROSS THE LOWER DESERTS...WITH GOOD OVERNIGHT
RECOVERY ANTICIPATED. OUTSIDE OF THUNDERSTORMS...WINDS WILL FAVOR
THE TYPICAL DIURNAL UPSLOPE/DOWNVALLEY PATTERNS. MEDIUM RANGE
FORECAST MODELS BEGIN TO DIVERGE BY THE LATE WEEKEND WITH REGARDS TO
THE UPPER LEVEL PATTERN AND AMOUNT OF MONSOON MOISTURE ACROSS THE
REGION. WILL CONTINUE TO MONITOR THE EVOLUTION OF THE PATTERN AND
ANY POTENTIAL FIRE WEATHER IMPACTS OVER THE NEXT FEW PERIODS. WITH
THE DEEP MOISTURE FORECAST TO MOVE INTO THE REGION BY ONE
MODEL...HUMIDITIES AND RAINFALL CHANCES COULD SEE A HEALTHY BOOST BY
THE LATE WEEKEND.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...AJ
PREVIOUS DISCUSSION...VASQUEZ
AVIATION...NOLTE
FIRE WEATHER...NOLTE/PERCHA
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1059 AM MDT TUE SEP 3 2013
.UPDATE...
ISSUED AT 1057 AM MDT TUE SEP 3 2013
CLOUD PLUME EXTENDED ALONG THE AZ/NM BORDER UP INTO SE UT/SW CO
THIS MORNING. LOOKED LIKE A WEAK SHORTWAVE WAS PUSHING INTO SE UT
ON SATELLITE WATER VAPOR...WHICH THE RUC13 CAPTURED REASONABLY
WELL AND TRACKS IT N-NE AS IT WEAKENS. WILL ADD MENTION OF
ISOLATED STORMS TO NW CO TODAY...OTHERWISE CURRENT FORECAST LOOKS
ON TRACK WITH ISOLATED TO SCATTERED STORMS MAINLY OVER THE HIGHER
TERRAIN FROM FROM THE UINTA MTNS TO FLATTOPS AND SOUTH THIS
AFTERNOON. LOCALLY HEAVY RAINFALL POSSIBLE GIVEN DECENT MOISTURE
AND SLOW STORM MOVEMENT.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 429 AM MDT TUE SEP 3 2013
STAGNANT PATTERN WHICH FEATURED HIGH PRESSURE CENTERED OVER THE
COLORADO SPRINGS AREA WILL PERSIST TODAY. AS A RESULT...A WEAK
INFLUX OF MONSOON MOISTURE ALONG WITH SOME RECYCLING OF MOISTURE
OVER THE REGION WILL CONTINUE. EARLY THIS MORNING...A WEAK
DISTURBANCE MOVING OVER SOUTHEAST UTAH WAS RESPONSIBLE FOR A FEW
THUNDERSTORMS STRETCHING FROM MEXICAN HAT TO THE NORTHWEST FLANKS
OF THE ABAJO MOUNTAINS. ANOTHER DISTURBANCE FARTHER SOUTH HAS THE
POTENTIAL OF PROLONGING THIS ACTIVITY WHILE POSSIBLE IMPACTING
PORTIONS OF SOUTHWEST COLORADO AS WELL. MODEL CONSENSUS FAVORED
SOME LIGHT SHOWERS AND A FEW EMBEDDED THUNDERSTORMS LINGERING OVER
THIS AREA PAST SUNRISE AND THEREFORE BOOSTED LOW END POPS THIS
MORNING.
FROM LATE MORNING INTO THE AFTERNOON...DIURNAL PROCESSES WILL TAKE
OVER WITH STORMS DEVELOPING OVER THE HIGH TERRAIN. MAIN THREAT
FROM TODAY/S STORMS WILL BE HEAVY RAIN AS PRECIPITABLE WATER
VALUES RANGE FROM 0.8 TO NEAR 1.0 INCH ACROSS REGION. LIGHT FLOW
WILL RESULT IN SLOW MOVING STORMS WHICH COULD RESULT IN LOCALIZED
RUNOFF ISSUES...ESPECIALLY OVER BURN SCARS AND STEEP TERRAIN.
EXPECT LITTLE CHANGE IN AFTERNOON HIGHS FOR THE REGION...THOUGH
TIMING AND PLACEMENT OF DEVELOPING STORM CELLS WILL RESULT LOCAL
DEVIATIONS.
H5 00Z HAND ANALYSIS HAD THE CENTER OF THE SUBTROPICAL HIGH NOSING
ACROSS THE CENTRAL NM/CO BORDER. THE HIGH WILL BE MAKING ROOTS IN
CENTRAL COLORADO OVER THE NEXT SEVERAL DAYS AS STRONG TROUGHING
ALONG EACH NORTHERN COAST OF THE CONUS STAGNATES THE WX PATTERN.
WATER VAPOR IMAGERY SHOWED DRIER AIR IN THE PLAINS BEHIND A COLD
FRONT PROGRESSING THROUGH THE EASTERN TROUGH. THIS DRIER AIR WILL
BE ADVECTED EASTWARD AROUND THE BASE OF THE HIGH AND EFFECTIVELY
CUTTING OFF THE DIRECT FLOW OF MONSOONAL MOISTURE INTO OUR CWA.
MOISTURE HOWEVER WILL SATURATE THE CENTER OF THE HIGH PRESSURE
CELL OVER COLORADO AND PROVIDE ENOUGH FUEL TO FIRE MAINLY
DIURNALLY DRIVEN CONVECTION THROUGH THE MID WEEK PERIOD. OUR CWA
WILL BE ON THE WESTERN AXIS OF THE HIGH SO STORM MOTION WILL
GENERALLY BE FROM THE SOUTH TO SOUTHWEST AT 15 MPH OR LESS. WITH
THE WARMER TEMPERATURES ALOFT INSTABILITY...THEREFORE CAPE...WILL
BE LIMITED TO A SMALL PORTION OF THE PROFILE AND STORMS SHOULD NOT
BE ORGANIZED. THIS SHOULD FAVOR THE TERRAIN FOR STORM FORMATION
WITH ONLY A FEW ISOLATED STORMS SURVIVING INTO THE VALLEYS FROM
FAVORABLE OUTFLOW INTERACTIONS. BRIEF MODERATE TO HEAVY RAINFALL
WILL BE POSSIBLE BUT DEEP CONVECTION SHOULD BE LIMITED UNDER THE
SUBSIDENCE OF THE HIGH PRESSURE. HIGH TEMPERATURES WILL BE WELL
ABOVE NORMAL AND FOR NOW DO NOT LOOK TO STRAY TO FAR FROM
PERSISTENCE WEDNESDAY INTO THURSDAY. MEANING HIGHS IN THE 90S
LOWER VALLEYS...WITH MID 60S TO MID 70S OVER THE MOUNTAINS.
.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 429 AM MDT TUE SEP 3 2013
THE LOW PRESSURE SYSTEM ANCHORED OFF THE PACIFIC NORTHWEST OVER
THE PAST SEVERAL DAYS WILL BEGIN TO DRIFT INLAND THURSDAY NIGHT...
MOVING SLOWLY EASTWARD ACROSS THE NORTHWEST INTO MONDAY. THIS
WON/T BRING AN APPRECIABLE CHANGE IN WEATHER ACROSS THE REGION AS
FLOW BETWEEN THE NORTHWEST LOW AND THE SOUTHERN PLAINS CONTINUES
TO CARRY MONSOON MOISTURE ACROSS THE REGION LATE THIS WEEK...
THROUGH THE WEEKEND...AND INTO EARLY NEXT WEEK. AS A RESULT...
EXPECT MAINLY DIURNAL SHOWERS AND THUNDERSTORMS WILL CONTINUE
THROUGH THE PERIOD WITH LOCALLY HEAVY RAIN THE MAIN STORM THREAT.
CONSEQUENTLY...TEMPERATURES WILL CONTINUE TO RUN NEAR AND A LITTLE
ABOVE NORMAL THROUGH THE PERIOD.
HOWEVER...AS THE TROUGH PASSES TO THE NORTH OF THE AREA SUNDAY
NIGHT INTO MONDAY...MODELS HINT AT A COOL FRONT DROPPING OVER THE
NORTHERN HALF OF THE FORECAST AREA. ALONG WITH MILDER TEMPERATURES
BEHIND THE FRONT...DRIER AIR WILL LIMIT AFTERNOON CONVECTION NORTH
OF THE I-70 CORRIDOR.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1057 AM MDT TUE SEP 3 2013
ISOLATED TO SCATTERED THUNDERSTORMS CAN BE EXPECTED MAINLY OVER
THE HIGHER TERRAIN BETWEEN 18Z AND 02Z TODAY...THOUGH WITH A SLOW
NORTHEAST STORM MOTION EXPECTED...WILL ALSO CARRY VCTS AT KRIL
AND KEGE. BRIEF MVFR OR POSSIBLY IFR VISIBLITY IS POSSIBLE IN
HEAVY RAIN FROM THE STRONGER STORMS. STORMS WILL DIMINISH DURING
THE LATTER PART OF THE EVENING THOUGH ISOLATED LIGHT SHOWERS WILL
CONTINUE INTO WEDNESDAY MORNING. SHOWER INTENSITY WILL BE LIGHT SO
VFR CONDITIONS WILL PREVAIL FROM 06Z TO 12Z.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
UPDATE...JAD
SHORT TERM...NL/15
LONG TERM...NL
AVIATION...TGJT
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
321 AM EDT Tue Sep 3 2013
.NEAR TERM [Rest of Today]...
As of 07 UTC, TLH radar showed some showers beginning to develop
over the adjacent coastal waters of the Gulf of Mexico. Similar to
what was portrayed yesterday, the HRRR develops a considerable band
of convection near the coast between 10 UTC and 14 UTC, gradually
spreading it into our Florida zones through the morning hours. The
result in that scenario would be relatively high coverage of rain,
with some localized heavy rain. The raw GFS QPF portrays a similar
scenario, although the MAV PoPs tell a different story. Given the
recent favorable performance of the HRRR and its assessment of
current conditions, we have trended the PoP forecast towards the
past few runs of the HRRR (03-05z runs). This includes "likely"
(60-70%) PoPs for portions of the Florida Panhandle and Big Bend
during the morning hours, with a dry forecast north of a DHN-MGR
line in our Alabama and Georgia zones. By afternoon, there is more
uncertainty, but the current thinking is that morning convection
would stabilize our Florida zones leading to diminishing coverage
there, while additional thunderstorms develop along a weak front in
the northern parts of our area. The afternoon PoP is a general 50%.
Given that we have increased the expected rain and cloud cover in
the Florida Panhandle this morning, high temperatures were cut back
in those area to the upper 80s / around 90.
&&
.SHORT TERM [Tonight Through Thursday]...
Energy in the base of the eastern U.S. trough will slip south of the
area at the start of the period. While the trough will lose some
amplitude as its axis moves east of the area, the ridge over the
plains will only weakly ridge eastward. Overall, the forecast area
will remain in a regime of weak northwesterly flow aloft with low
level onshore flow. A surface ridge will remain south of the area
with a lee-side trough extending from the Carolina Piedmont into
central GA. A cold front over the Tennessee and Lower Mississippi
Valley will approach from the north on Thursday. PoPs and temps will
be close to climatology through the period. Organized severe weather
and flooding is not anticipated. However, as on most summer days, an
isolated strong to severe storm will be possible each afternoon.
&&
.LONG TERM [Thursday Night through Monday]...
Upper troughing will continue down the eastern seaboard through
Sunday before ridging builds in from the west early next week. The
aforementioned cold front will drop down into our CWA Thursday
becoming quasi-stationary Friday into Saturday. Will keep PoPs in
the chance category each day with temps near seasonal levels.
&&
.AVIATION...
[Through 06 UTC Wednesday] Most terminals are expected to have at
least brief MVFR restrictions this morning in fog or low stratus.
Some are likely to get to the IFR or LIFR range, especially around
sunrise. ECP and TLH may see some early thunderstorms, perhaps
developing near the coast as early as 12-13 UTC and then spreading
inland during the morning hours. ABY, DHN, and VLD may be affected
by scattered TSRA during the afternoon.
&&
.MARINE...
Outside of any thunderstorms, and with a weak pressure gradient in
place, light mainly onshore winds and minimal seas are expected over
the coastal waters this week.
&&
.FIRE WEATHER...
Relative humidity is expected to remain well above critical
thresholds for the next several days.
&&
.HYDROLOGY...
Forecast rainfall is not expected to cause any problems on area
rivers this week. Outside of the Suwannee River Basin, all rivers in
the forecast area remain in recession. The Aucilla River will
continue to fall slowly and is currently forecast to be below flood
stage at Lamont on Thursday. On the Suwannee, Wilcox at US19 has the
best chance of reaching flood stage late in the week. However, the
current forecast has it cresting just below this weekend.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 89 74 92 73 92 / 60 20 40 20 30
Panama City 86 76 88 76 88 / 60 20 30 20 20
Dothan 92 71 91 72 91 / 50 20 30 20 30
Albany 93 73 92 73 91 / 50 20 30 20 30
Valdosta 93 73 93 74 93 / 50 20 40 20 30
Cross City 89 73 90 72 91 / 50 20 40 20 40
Apalachicola 86 76 88 75 89 / 70 20 30 20 20
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
Near Term/Aviation/Fire Weather...Lamers
Long Term...Barry/Hernandez
Rest of Discussion...Wool
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
120 PM EDT TUE SEP 3 2013
.PREV DISCUSSION... /ISSUED 953 AM EDT TUE SEP 3 2013/
UPDATE...
WEAK COLD FRONT MOVING INTO N GA. BEST CHANCES FOR SHOWERS AND
STORMS APPEAR TO BE S OF FRONT ACROSS CENTRAL AND PORTIONS OF N
GA THIS AFTERNOON WHERE BEST INSTABILITY IS FORECAST. BDL
PREV DISCUSSION... /ISSUED 729 AM EDT TUE SEP 3 2013/
SHORT TERM /TODAY THROUGH WEDNESDAY/...
DEEP UPPER TROUGH IN PLACE OVER THE EASTERN HALF OF THE COUNTRY...
WITH THE TROUGH AXIS PARALLEL TO THE SOUTHERN APPALACHIANS AT THE
START OF THE SHORT TERM. ASSOCIATED SURFACE FRONT CURRENTLY LOCATED
FROM NEAR THE UPPER OHIO VALLEY...STRETCHING THROUGH THE MID-SOUTH
AND TO NEAR THE RED RIVER AT AFD TIME. THE FRONT WILL WORK ITS WAY
SOUTHEAST THROUGH THE DAY...WITH DRIER AIR BEGINNING TO FILTER INTO
THE STATE FOR TONIGHT. SHORT-TERM GUIDANCE IS IN PRETTY GOOD
AGREEMENT WITH THE MASS FIELDS. NOT A LOT OF SYNOPTIC LIFT TO SPEAK
OF TODAY AS THE FRONT CONTINUES TO OCCLUDE...BUT THERE SHOULD BE AT
LEAST SOME SYNOPTIC CONTRIBUTION IN THE FORM OF WEAK DIVERGENCE
ALOFT /RIGHT ENTRANCE REGION OF THE BARELY-THERE UPPER JET/ AND OF
COURSE DPVA AHEAD OF THE SHORTWAVE ITSELF...BOTH OF THESE MAXIMIZED
ACROSS CENTRAL GEORGIA FOR THIS AFTERNOON.
OF IMMEDIATE CONCERN IS THE EVOLUTION OF CONVECTION THROUGH THE
EARLY MORNING HOURS. PRE-FRONTAL CONVECTION HAS FIRED ACROSS
NORTHWEST GEORGIA AT AFD TIME...AND IN SIMILAR MANNER TO YESTERDAY
MORNING THE CONVECTION FIRED ALONG AN INSTABILITY GRADIENT IN AN
AREA WHERE CIN IS MINIMIZED. LATEST RUNS OF THE HRRR ARE ACTUALLY
PICKING UP ON THIS AND PUSHING A CONVECTIVE COMPLEX ACROSS NORTH
GEORGIA BETWEEN NOW AND APPROXIMATELY 13Z. BASED ON WHAT HAPPENED
LAST NIGHT...THIS IS NOT AT ALL AN UNREASONABLE SOLUTION...AND OTHER
HIRES GUIDANCE POINTING TO THE SAME THING. ARW MEMBERS NOT QUITE SO
PRONOUNCED AS THE NMM THOUGH. HRRR HAS NOT BEEN DOING WELL THE PAST
FEW DAYS BUT PERHAPS IT HAS FINALLY CAUGHT UP...AND IN ANY CASE THE
OVERALL PATTERN IS SUPPORTIVE OF DEVELOPMENT OF THESE OVERNIGHT
CONVECTIVE COMPLEXES. AS WAS THE CASE YESTERDAY...WHATEVER DOES
DEVELOP ACROSS NORTH GEORGIA EARLY THIS MORNING WILL LIKELY
DISSIPATE BY MID-MORNING /AFTER SUNRISE/ AS MIXING INCREASES.
HOWEVER...IF SUCH A CONVECTIVE COMPLEX DEVELOPS /AS IT DID
YESTERDAY/...IT WILL LIKELY WREAK HAVOC ON HIGH TEMPS TODAY /AS IT
DID YESTERDAY/. AT THIS POINT IT IS NEARLY IMPOSSIBLE TO TRY TO PIN
DOWN THOSE DETAILS BUT SUFFICE IT TO SAY THAT WE COULD SEE SOME BIG
BUSTS AGAIN TODAY /AS WE DID YESTERDAY/.
CAPES INCREASE TO BETWEEN 1500-2000 J/KG THIS AFTERNOON AHEAD OF THE
FRONT...MAINLY FROM APPROXIMATELY THE ATLANTA METRO AREA AND POINT
SOUTH. EXPECT CONVECTION TO FIRE AGAIN THIS AFTERNOON WITH BEST
COVERAGE ACROSS CENTRAL GEORGIA BUT ISOLATED TO SCATTERED CONVECTION
POSSIBLE UP INTO THE METRO AREA. EXPECT THE BULK IF NOT ALL OF THE
ACTIVITY TO DIE DOWN BY 06Z AND THUS HAVE NO POPS ACROSS THE AREA
OVERNIGHT. THE FRONT WILL CONTINUE TO SAG SOUTH AND WE SHOULD SEE A
NOTICEABLE DIFFERENCE IN LOW TEMPS BETWEEN WHAT WE HAVE THIS MORNING
AND TONIGHT...GENERALLY DOWN 3-5 DEGREES.
FRONT SHOULD STALL SOMEWHERE ACROSS THE AREA ON WEDNESDAY...KEEPING
THE CHANCE FOR CONVECTION ACROSS CENTRAL GEORGIA MAINLY DURING THE
AFTERNOON. INFLUENCE OF DRIER AIR WILL BE FELT ACROSS NORTH GEORGIA
BUT NO REAL CAA ALOFT TO SPEAK OF SO DO NOT THINK THAT TEMPS
WEDNESDAY WILL BE MUCH IF AT ALL COOLER THAN THOSE TODAY. /AND
ACTUALLY IF WE HAVE RAIN-COOLED AIR FROM CONVECTION THIS MORNING
MESSING WITH TEMPS TODAY...THEN WEDNESDAY COULD ACTUALLY BE WARMER./
ALL THAT SAID...WENT WITH A GENERAL BIAS-ADJUSTED BLEND.
TDP
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
MODELS CONSISTENT IN KEEPING DRY AIR ACROSS NORTH GEORGIA THROUGH
THE END OF THE WEEK AS THE FRONTAL BOUNDARY STALLS JUST SOUTH OF
THE CWA. DRYING ALOFT AND LOW PRECIPITABLE WATER SHOULD KEEP
CONVECTION OUT OF MUCH OF THE CWA THROUGH THURSDAY NIGHT...EXCEPT
FOR SLIGHT CHANCE AFTERNOON AND EVENING ALONG THE LAST ROW OR TWO
OF COUNTIES SOUTH OF COLUMBUS TO MACON. MOISTURE BEGINS SPREADING
BACK INTO THE FORECAST AREA ON FRIDAY AS LOW LEVEL WINDS TURN TO
THE EAST AND SOUTHEAST. HOWEVER WITH UPPER RIDGE BUILDING OVER THE
SOUTHEAST STATES THROUGH THE END OF THE PERIOD...EXPECTING ONLY
LOW CHANCE OR SLIGHT CHANCE AFTERNOON AND EVENING THUNDERSTORMS
ACROSS THE AREA.
41
&&
.AVIATION...
18Z UPDATE...
SOME MVFR/VFR CEILINGS TO START BUT MAINLY VFR CONDITIONS WITH SCT-BKN
3000-5000 FT CU. BEST CHANCES FOR THUNDERSTORMS LOOK TO BE ACROSS
MAINLY CENTRAL GA THIS AFTERNOON/EARLY EVENING. SURFACE WINDS W-NW
10 KTS OR LESS DIMINISHING WITH SUNSET. PATCHY TO AREAS OF FOG LATE
TONIGHT.
//ATL CONFIDENCE...18Z UPDATE...
LOW-MEDIUM CONFIDENCE FOR MVFR CEILINGS 18-20Z.
MEDIUM CONFIDENCE FOR NO CONVECTION.
HIGH CONFIDENCE ALL OTHER ELEMENTS INTO TONIGHT.
BDL
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 90 68 89 66 / 40 20 10 5
ATLANTA 88 70 89 67 / 30 10 5 5
BLAIRSVILLE 84 61 84 61 / 50 10 5 5
CARTERSVILLE 89 65 88 64 / 20 10 5 5
COLUMBUS 91 72 91 69 / 30 20 20 10
GAINESVILLE 87 68 87 67 / 60 10 10 5
MACON 91 69 92 68 / 30 20 20 10
ROME 88 65 89 63 / 20 5 5 5
PEACHTREE CITY 89 66 88 63 / 30 20 5 5
VIDALIA 90 72 91 71 / 40 20 20 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BDL
LONG TERM....17
AVIATION...BDL
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
953 AM EDT TUE SEP 3 2013
.UPDATE...
WEAK COLD FRONT MOVING INTO N GA. BEST CHANCES FOR SHOWERS AND
STORMS APPEAR TO BE S OF FRONT ACROSS CENTRAL AND PORTIONS OF N
GA THIS AFTERNOON WHERE BEST INSTABILITY IS FORECAST. BDL
&&
.PREV DISCUSSION... /ISSUED 729 AM EDT TUE SEP 3 2013/
SHORT TERM /TODAY THROUGH WEDNESDAY/...
DEEP UPPER TROUGH IN PLACE OVER THE EASTERN HALF OF THE COUNTRY...
WITH THE TROUGH AXIS PARALLEL TO THE SOUTHERN APPALACHIANS AT THE
START OF THE SHORT TERM. ASSOCIATED SURFACE FRONT CURRENTLY LOCATED
FROM NEAR THE UPPER OHIO VALLEY...STRETCHING THROUGH THE MID-SOUTH
AND TO NEAR THE RED RIVER AT AFD TIME. THE FRONT WILL WORK ITS WAY
SOUTHEAST THROUGH THE DAY...WITH DRIER AIR BEGINNING TO FILTER INTO
THE STATE FOR TONIGHT. SHORT-TERM GUIDANCE IS IN PRETTY GOOD
AGREEMENT WITH THE MASS FIELDS. NOT A LOT OF SYNOPTIC LIFT TO SPEAK
OF TODAY AS THE FRONT CONTINUES TO OCCLUDE...BUT THERE SHOULD BE AT
LEAST SOME SYNOPTIC CONTRIBUTION IN THE FORM OF WEAK DIVERGENCE
ALOFT /RIGHT ENTRANCE REGION OF THE BARELY-THERE UPPER JET/ AND OF
COURSE DPVA AHEAD OF THE SHORTWAVE ITSELF...BOTH OF THESE MAXIMIZED
ACROSS CENTRAL GEORGIA FOR THIS AFTERNOON.
OF IMMEDIATE CONCERN IS THE EVOLUTION OF CONVECTION THROUGH THE
EARLY MORNING HOURS. PRE-FRONTAL CONVECTION HAS FIRED ACROSS
NORTHWEST GEORGIA AT AFD TIME...AND IN SIMILAR MANNER TO YESTERDAY
MORNING THE CONVECTION FIRED ALONG AN INSTABILITY GRADIENT IN AN
AREA WHERE CIN IS MINIMIZED. LATEST RUNS OF THE HRRR ARE ACTUALLY
PICKING UP ON THIS AND PUSHING A CONVECTIVE COMPLEX ACROSS NORTH
GEORGIA BETWEEN NOW AND APPROXIMATELY 13Z. BASED ON WHAT HAPPENED
LAST NIGHT...THIS IS NOT AT ALL AN UNREASONABLE SOLUTION...AND OTHER
HIRES GUIDANCE POINTING TO THE SAME THING. ARW MEMBERS NOT QUITE SO
PRONOUNCED AS THE NMM THOUGH. HRRR HAS NOT BEEN DOING WELL THE PAST
FEW DAYS BUT PERHAPS IT HAS FINALLY CAUGHT UP...AND IN ANY CASE THE
OVERALL PATTERN IS SUPPORTIVE OF DEVELOPMENT OF THESE OVERNIGHT
CONVECTIVE COMPLEXES. AS WAS THE CASE YESTERDAY...WHATEVER DOES
DEVELOP ACROSS NORTH GEORGIA EARLY THIS MORNING WILL LIKELY
DISSIPATE BY MID-MORNING /AFTER SUNRISE/ AS MIXING INCREASES.
HOWEVER...IF SUCH A CONVECTIVE COMPLEX DEVELOPS /AS IT DID
YESTERDAY/...IT WILL LIKELY WREAK HAVOC ON HIGH TEMPS TODAY /AS IT
DID YESTERDAY/. AT THIS POINT IT IS NEARLY IMPOSSIBLE TO TRY TO PIN
DOWN THOSE DETAILS BUT SUFFICE IT TO SAY THAT WE COULD SEE SOME BIG
BUSTS AGAIN TODAY /AS WE DID YESTERDAY/.
CAPES INCREASE TO BETWEEN 1500-2000 J/KG THIS AFTERNOON AHEAD OF THE
FRONT...MAINLY FROM APPROXIMATELY THE ATLANTA METRO AREA AND POINT
SOUTH. EXPECT CONVECTION TO FIRE AGAIN THIS AFTERNOON WITH BEST
COVERAGE ACROSS CENTRAL GEORGIA BUT ISOLATED TO SCATTERED CONVECTION
POSSIBLE UP INTO THE METRO AREA. EXPECT THE BULK IF NOT ALL OF THE
ACTIVITY TO DIE DOWN BY 06Z AND THUS HAVE NO POPS ACROSS THE AREA
OVERNIGHT. THE FRONT WILL CONTINUE TO SAG SOUTH AND WE SHOULD SEE A
NOTICEABLE DIFFERENCE IN LOW TEMPS BETWEEN WHAT WE HAVE THIS MORNING
AND TONIGHT...GENERALLY DOWN 3-5 DEGREES.
FRONT SHOULD STALL SOMEWHERE ACROSS THE AREA ON WEDNESDAY...KEEPING
THE CHANCE FOR CONVECTION ACROSS CENTRAL GEORGIA MAINLY DURING THE
AFTERNOON. INFLUENCE OF DRIER AIR WILL BE FELT ACROSS NORTH GEORGIA
BUT NO REAL CAA ALOFT TO SPEAK OF SO DO NOT THINK THAT TEMPS
WEDNESDAY WILL BE MUCH IF AT ALL COOLER THAN THOSE TODAY. /AND
ACTUALLY IF WE HAVE RAIN-COOLED AIR FROM CONVECTION THIS MORNING
MESSING WITH TEMPS TODAY...THEN WEDNESDAY COULD ACTUALLY BE WARMER./
ALL THAT SAID...WENT WITH A GENERAL BIAS-ADJUSTED BLEND.
TDP
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
MODELS CONSISTENT IN KEEPING DRY AIR ACROSS NORTH GEORGIA THROUGH
THE END OF THE WEEK AS THE FRONTAL BOUNDARY STALLS JUST SOUTH OF
THE CWA. DRYING ALOFT AND LOW PRECIPITABLE WATER SHOULD KEEP
CONVECTION OUT OF MUCH OF THE CWA THROUGH THURSDAY NIGHT...EXCEPT
FOR SLIGHT CHANCE AFTERNOON AND EVENING ALONG THE LAST ROW OR TWO
OF COUNTIES SOUTH OF COLUMBUS TO MACON. MOISTURE BEGINS SPREADING
BACK INTO THE FORECAST AREA ON FRIDAY AS LOW LEVEL WINDS TURN TO
THE EAST AND SOUTHEAST. HOWEVER WITH UPPER RIDGE BUILDING OVER THE
SOUTHEAST STATES THROUGH THE END OF THE PERIOD...EXPECTING ONLY
LOW CHANCE OR SLIGHT CHANCE AFTERNOON AND EVENING THUNDERSTORMS
ACROSS THE AREA.
41
AVIATION...
12Z UPDATE...
MAINLY VFR THIS MORNING...WITH POCKETS OF MVFR FOG AROUND. TEMPO
IFR CIG CONDITIONS DID NOT MATERIALIZE...BUT METRO TAFS DID SEE
BRIEF THUNDER AROUND 10Z. BEST CHANCE THUNDER TODAY REMAINS AT
CSG/MCN WHERE HAVE INCLUDED TEMPO 18-22Z. OTHER TAFS JUST WENT
VCSH. IMPROVING CONDITIONS AFTER 00Z AND VFR THROUGH THE REST OF
THE PERIOD FOR NOW...THOUGH THERE ARE SOME HINTS AT BRIEF MVFR FOG
WEDNESDAY MORNING.. W TO NW WINDS...5-10KT DURING THE DAY AND LESS
THAN 5KT AT NIGHT.
//ATL CONFIDENCE...12Z UPDATE...
LOW ON POTENTIAL FOR BRIEF MVFR/IFR CIGS THIS MORNING.
MEDIUM ON CONVECTION THIS AFTERNOON.
HIGH ON ALL OTHER ELEMENTS.
TDP
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 90 68 89 66 / 40 20 10 5
ATLANTA 88 70 89 67 / 30 10 5 5
BLAIRSVILLE 84 61 84 61 / 50 10 5 5
CARTERSVILLE 89 65 88 64 / 20 10 5 5
COLUMBUS 91 72 91 69 / 30 20 20 10
GAINESVILLE 87 68 87 67 / 60 10 10 5
MACON 91 69 92 68 / 30 20 20 10
ROME 88 65 89 63 / 20 5 5 5
PEACHTREE CITY 89 66 88 63 / 30 20 5 5
VIDALIA 90 72 91 71 / 40 20 20 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BDL
LONG TERM....17
AVIATION...BDL
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
729 AM EDT TUE SEP 3 2013
.PREV DISCUSSION... /ISSUED 357 AM EDT TUE SEP 3 2013/
SHORT TERM /TODAY THROUGH WEDNESDAY/...
DEEP UPPER TROUGH IN PLACE OVER THE EASTERN HALF OF THE COUNTRY...
WITH THE TROUGH AXIS PARALLEL TO THE SOUTHERN APPALACHIANS AT THE
START OF THE SHORT TERM. ASSOCIATED SURFACE FRONT CURRENTLY LOCATED
FROM NEAR THE UPPER OHIO VALLEY...STRETCHING THROUGH THE MID-SOUTH
AND TO NEAR THE RED RIVER AT AFD TIME. THE FRONT WILL WORK ITS WAY
SOUTHEAST THROUGH THE DAY...WITH DRIER AIR BEGINNING TO FILTER INTO
THE STATE FOR TONIGHT. SHORT-TERM GUIDANCE IS IN PRETTY GOOD
AGREEMENT WITH THE MASS FIELDS. NOT A LOT OF SYNOPTIC LIFT TO SPEAK
OF TODAY AS THE FRONT CONTINUES TO OCCLUDE...BUT THERE SHOULD BE AT
LEAST SOME SYNOPTIC CONTRIBUTION IN THE FORM OF WEAK DIVERGENCE
ALOFT /RIGHT ENTRANCE REGION OF THE BARELY-THERE UPPER JET/ AND OF
COURSE DPVA AHEAD OF THE SHORTWAVE ITSELF...BOTH OF THESE MAXIMIZED
ACROSS CENTRAL GEORGIA FOR THIS AFTERNOON.
OF IMMEDIATE CONCERN IS THE EVOLUTION OF CONVECTION THROUGH THE
EARLY MORNING HOURS. PRE-FRONTAL CONVECTION HAS FIRED ACROSS
NORTHWEST GEORGIA AT AFD TIME...AND IN SIMILAR MANNER TO YESTERDAY
MORNING THE CONVECTION FIRED ALONG AN INSTABILITY GRADIENT IN AN
AREA WHERE CIN IS MINIMIZED. LATEST RUNS OF THE HRRR ARE ACTUALLY
PICKING UP ON THIS AND PUSHING A CONVECTIVE COMPLEX ACROSS NORTH
GEORGIA BETWEEN NOW AND APPROXIMATELY 13Z. BASED ON WHAT HAPPENED
LAST NIGHT...THIS IS NOT AT ALL AN UNREASONABLE SOLUTION...AND OTHER
HIRES GUIDANCE POINTING TO THE SAME THING. ARW MEMBERS NOT QUITE SO
PRONOUNCED AS THE NMM THOUGH. HRRR HAS NOT BEEN DOING WELL THE PAST
FEW DAYS BUT PERHAPS IT HAS FINALLY CAUGHT UP...AND IN ANY CASE THE
OVERALL PATTERN IS SUPPORTIVE OF DEVELOPMENT OF THESE OVERNIGHT
CONVECTIVE COMPLEXES. AS WAS THE CASE YESTERDAY...WHATEVER DOES
DEVELOP ACROSS NORTH GEORGIA EARLY THIS MORNING WILL LIKELY
DISSIPATE BY MID-MORNING /AFTER SUNRISE/ AS MIXING INCREASES.
HOWEVER...IF SUCH A CONVECTIVE COMPLEX DEVELOPS /AS IT DID
YESTERDAY/...IT WILL LIKELY WREAK HAVOC ON HIGH TEMPS TODAY /AS IT
DID YESTERDAY/. AT THIS POINT IT IS NEARLY IMPOSSIBLE TO TRY TO PIN
DOWN THOSE DETAILS BUT SUFFICE IT TO SAY THAT WE COULD SEE SOME BIG
BUSTS AGAIN TODAY /AS WE DID YESTERDAY/.
CAPES INCREASE TO BETWEEN 1500-2000 J/KG THIS AFTERNOON AHEAD OF THE
FRONT...MAINLY FROM APPROXIMATELY THE ATLANTA METRO AREA AND POINT
SOUTH. EXPECT CONVECTION TO FIRE AGAIN THIS AFTERNOON WITH BEST
COVERAGE ACROSS CENTRAL GEORGIA BUT ISOLATED TO SCATTERED CONVECTION
POSSIBLE UP INTO THE METRO AREA. EXPECT THE BULK IF NOT ALL OF THE
ACTIVITY TO DIE DOWN BY 06Z AND THUS HAVE NO POPS ACROSS THE AREA
OVERNIGHT. THE FRONT WILL CONTINUE TO SAG SOUTH AND WE SHOULD SEE A
NOTICEABLE DIFFERENCE IN LOW TEMPS BETWEEN WHAT WE HAVE THIS MORNING
AND TONIGHT...GENERALLY DOWN 3-5 DEGREES.
FRONT SHOULD STALL SOMEWHERE ACROSS THE AREA ON WEDNESDAY...KEEPING
THE CHANCE FOR CONVECTION ACROSS CENTRAL GEORGIA MAINLY DURING THE
AFTERNOON. INFLUENCE OF DRIER AIR WILL BE FELT ACROSS NORTH GEORGIA
BUT NO REAL CAA ALOFT TO SPEAK OF SO DO NOT THINK THAT TEMPS
WEDNESDAY WILL BE MUCH IF AT ALL COOLER THAN THOSE TODAY. /AND
ACTUALLY IF WE HAVE RAIN-COOLED AIR FROM CONVECTION THIS MORNING
MESSING WITH TEMPS TODAY...THEN WEDNESDAY COULD ACTUALLY BE WARMER./
ALL THAT SAID...WENT WITH A GENERAL BIAS-ADJUSTED BLEND.
TDP
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
MODELS CONSISTENT IN KEEPING DRY AIR ACROSS NORTH GEORGIA THROUGH
THE END OF THE WEEK AS THE FRONTAL BOUNDARY STALLS JUST SOUTH OF
THE CWA. DRYING ALOFT AND LOW PRECIPITABLE WATER SHOULD KEEP
CONVECTION OUT OF MUCH OF THE CWA THROUGH THURSDAY NIGHT...EXCEPT
FOR SLIGHT CHANCE AFTERNOON AND EVENING ALONG THE LAST ROW OR TWO
OF COUNTIES SOUTH OF COLUMBUS TO MACON. MOISTURE BEGINS SPREADING
BACK INTO THE FORECAST AREA ON FRIDAY AS LOW LEVEL WINDS TURN TO
THE EAST AND SOUTHEAST. HOWEVER WITH UPPER RIDGE BUILDING OVER THE
SOUTHEAST STATES THROUGH THE END OF THE PERIOD...EXPECTING ONLY
LOW CHANCE OR SLIGHT CHANCE AFTERNOON AND EVENING THUNDERSTORMS
ACROSS THE AREA.
41
&&
.AVIATION...
12Z UPDATE...
MAINLY VFR THIS MORNING...WITH POCKETS OF MVFR FOG AROUND. TEMPO
IFR CIG CONDITIONS DID NOT MATERIALIZE...BUT METRO TAFS DID SEE
BRIEF THUNDER AROUND 10Z. BEST CHANCE THUNDER TODAY REMAINS AT
CSG/MCN WHERE HAVE INCLUDED TEMPO 18-22Z. OTHER TAFS JUST WENT
VCSH. IMPROVING CONDITIONS AFTER 00Z AND VFR THROUGH THE REST OF
THE PERIOD FOR NOW...THOUGH THERE ARE SOME HINTS AT BRIEF MVFR FOG
WEDNESDAY MORNING.. W TO NW WINDS...5-10KT DURING THE DAY AND LESS
THAN 5KT AT NIGHT.
//ATL CONFIDENCE...12Z UPDATE...
LOW ON POTENTIAL FOR BRIEF MVFR/IFR CIGS THIS MORNING.
MEDIUM ON CONVECTION THIS AFTERNOON.
HIGH ON ALL OTHER ELEMENTS.
TDP
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 90 68 89 66 / 40 20 10 5
ATLANTA 88 70 89 67 / 30 10 5 5
BLAIRSVILLE 84 61 84 61 / 50 10 5 5
CARTERSVILLE 89 65 88 64 / 20 10 5 5
COLUMBUS 91 72 91 69 / 30 20 20 10
GAINESVILLE 87 68 87 67 / 60 10 10 5
MACON 91 69 92 68 / 30 20 20 10
ROME 88 65 89 63 / 20 5 5 5
PEACHTREE CITY 89 66 88 63 / 30 20 5 5
VIDALIA 90 72 91 71 / 40 20 20 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
357 AM EDT TUE SEP 3 2013
.SHORT TERM /TODAY THROUGH WEDNESDAY/...
DEEP UPPER TROUGH IN PLACE OVER THE EASTERN HALF OF THE COUNTRY...
WITH THE TROUGH AXIS PARALLEL TO THE SOUTHERN APPALACHIANS AT THE
START OF THE SHORT TERM. ASSOCIATED SURFACE FRONT CURRENTLY LOCATED
FROM NEAR THE UPPER OHIO VALLEY...STRETCHING THROUGH THE MID-SOUTH
AND TO NEAR THE RED RIVER AT AFD TIME. THE FRONT WILL WORK ITS WAY
SOUTHEAST THROUGH THE DAY...WITH DRIER AIR BEGINNING TO FILTER INTO
THE STATE FOR TONIGHT. SHORT-TERM GUIDANCE IS IN PRETTY GOOD
AGREEMENT WITH THE MASS FIELDS. NOT A LOT OF SYNOPTIC LIFT TO SPEAK
OF TODAY AS THE FRONT CONTINUES TO OCCLUDE...BUT THERE SHOULD BE AT
LEAST SOME SYNOPTIC CONTRIBUTION IN THE FORM OF WEAK DIVERGENCE
ALOFT /RIGHT ENTRANCE REGION OF THE BARELY-THERE UPPER JET/ AND OF
COURSE DPVA AHEAD OF THE SHORTWAVE ITSELF...BOTH OF THESE MAXIMIZED
ACROSS CENTRAL GEORGIA FOR THIS AFTERNOON.
OF IMMEDIATE CONCERN IS THE EVOLUTION OF CONVECTION THROUGH THE
EARLY MORNING HOURS. PRE-FRONTAL CONVECTION HAS FIRED ACROSS
NORTHWEST GEORGIA AT AFD TIME...AND IN SIMILAR MANNER TO YESTERDAY
MORNING THE CONVECTION FIRED ALONG AN INSTABILITY GRADIENT IN AN
AREA WHERE CIN IS MINIMIZED. LATEST RUNS OF THE HRRR ARE ACTUALLY
PICKING UP ON THIS AND PUSHING A CONVECTIVE COMPLEX ACROSS NORTH
GEORGIA BETWEEN NOW AND APPROXIMATELY 13Z. BASED ON WHAT HAPPENED
LAST NIGHT...THIS IS NOT AT ALL AN UNREASONABLE SOLUTION...AND OTHER
HIRES GUIDANCE POINTING TO THE SAME THING. ARW MEMBERS NOT QUITE SO
PRONOUNCED AS THE NMM THOUGH. HRRR HAS NOT BEEN DOING WELL THE PAST
FEW DAYS BUT PERHAPS IT HAS FINALLY CAUGHT UP...AND IN ANY CASE THE
OVERALL PATTERN IS SUPPORTIVE OF DEVELOPMENT OF THESE OVERNIGHT
CONVECTIVE COMPLEXES. AS WAS THE CASE YESTERDAY...WHATEVER DOES
DEVELOP ACROSS NORTH GEORGIA EARLY THIS MORNING WILL LIKELY
DISSIPATE BY MID-MORNING /AFTER SUNRISE/ AS MIXING INCREASES.
HOWEVER...IF SUCH A CONVECTIVE COMPLEX DEVELOPS /AS IT DID
YESTERDAY/...IT WILL LIKELY WREAK HAVOC ON HIGH TEMPS TODAY /AS IT
DID YESTERDAY/. AT THIS POINT IT IS NEARLY IMPOSSIBLE TO TRY TO PIN
DOWN THOSE DETAILS BUT SUFFICE IT TO SAY THAT WE COULD SEE SOME BIG
BUSTS AGAIN TODAY /AS WE DID YESTERDAY/.
CAPES INCREASE TO BETWEEN 1500-2000 J/KG THIS AFTERNOON AHEAD OF THE
FRONT...MAINLY FROM APPROXIMATELY THE ATLANTA METRO AREA AND POINT
SOUTH. EXPECT CONVECTION TO FIRE AGAIN THIS AFTERNOON WITH BEST
COVERAGE ACROSS CENTRAL GEORGIA BUT ISOLATED TO SCATTERED CONVECTION
POSSIBLE UP INTO THE METRO AREA. EXPECT THE BULK IF NOT ALL OF THE
ACTIVITY TO DIE DOWN BY 06Z AND THUS HAVE NO POPS ACROSS THE AREA
OVERNIGHT. THE FRONT WILL CONTINUE TO SAG SOUTH AND WE SHOULD SEE A
NOTICEABLE DIFFERENCE IN LOW TEMPS BETWEEN WHAT WE HAVE THIS MORNING
AND TONIGHT...GENERALLY DOWN 3-5 DEGREES.
FRONT SHOULD STALL SOMEWHERE ACROSS THE AREA ON WEDNESDAY...KEEPING
THE CHANCE FOR CONVECTION ACROSS CENTRAL GEORGIA MAINLY DURING THE
AFTERNOON. INFLUENCE OF DRIER AIR WILL BE FELT ACROSS NORTH GEORGIA
BUT NO REAL CAA ALOFT TO SPEAK OF SO DO NOT THINK THAT TEMPS
WEDNESDAY WILL BE MUCH IF AT ALL COOLER THAN THOSE TODAY. /AND
ACTUALLY IF WE HAVE RAIN-COOLED AIR FROM CONVECTION THIS MORNING
MESSING WITH TEMPS TODAY...THEN WEDNESDAY COULD ACTUALLY BE WARMER./
ALL THAT SAID...WENT WITH A GENERAL BIAS-ADJUSTED BLEND.
TDP
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
MODELS CONSISTENT IN KEEPING DRY AIR ACROSS NORTH GEORGIA THROUGH
THE END OF THE WEEK AS THE FRONTAL BOUNDARY STALLS JUST SOUTH OF
THE CWA. DRYING ALOFT AND LOW PRECIPITABLE WATER SHOULD KEEP
CONVECTION OUT OF MUCH OF THE CWA THROUGH THURSDAY NIGHT...EXCEPT
FOR SLIGHT CHANCE AFTERNOON AND EVENING ALONG THE LAST ROW OR TWO
OF COUNTIES SOUTH OF COLUMBUS TO MACON. MOISTURE BEGINS SPREADING
BACK INTO THE FORECAST AREA ON FRIDAY AS LOW LEVEL WINDS TURN TO
THE EAST AND SOUTHEAST. HOWEVER WITH UPPER RIDGE BUILDING OVER THE
SOUTHEAST STATES THROUGH THE END OF THE PERIOD...EXPECTING ONLY
LOW CHANCE OR SLIGHT CHANCE AFTERNOON AND EVENING THUNDERSTORMS
ACROSS THE AREA.
41
&&
AVIATION...
06Z UPDATE...
VFR AT TAF TIME BUT EXPECT MVFR FOG TO DEVELOP OVERNIGHT. WILL
PROBABLY SEE FEW-SCT IFR TO MVFR CLOUDS WITH BKN MID LEVEL...BUT
CANNOT RULE OUT A BRIEF IFR CIG SO HAVE INCLUDED THAT IN TEMPO
GROUPS. CIGS LIFTING AFTER 13Z OR SO. BEST CHANCE THUNDER AT
CSG/MCN BUT DID INCLUDE VCSH FOR NORTHERN TAFS THIS AFTERNOON. FOR
NOW...VFR EXPECTED THROUGH THE END OF THE PERIOD. W TO NW WINDS
BETWEEN 5-10KT THIS AFTERNOON...NEARLY CALM OVERNIGHT.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM ON MORNING CIGS.
MEDIUM ON AFTERNOON CONVECTION.
HIGH ON WINDS.
TDP
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 90 68 89 66 / 30 20 10 5
ATLANTA 88 70 89 67 / 30 10 5 5
BLAIRSVILLE 84 61 84 61 / 40 10 5 5
CARTERSVILLE 89 65 88 64 / 40 10 5 5
COLUMBUS 91 72 91 69 / 30 20 20 10
GAINESVILLE 87 68 87 67 / 40 10 10 5
MACON 91 69 92 68 / 30 20 20 10
ROME 88 65 89 63 / 40 5 5 5
PEACHTREE CITY 89 66 88 63 / 30 20 5 5
VIDALIA 90 72 91 71 / 40 20 20 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...TDP
LONG TERM....41
AVIATION...TDP
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1006 PM CDT WED SEP 4 2013
.DISCUSSION...
840 PM CDT
FOR EVENING UPDATE...
MAINLY ONLY MINOR ADJUSTMENTS BASED ON OBS/SATELLITE TRENDS THIS
EVENING.
SURFACE COLD FRONT WAS JUST ENTERING FAR NORTHEASTERN LAKE COUNTY
IL AT 01Z PER SFC OBS AND EXTRAPOLATION OF BOUNDARY THAT WAS
PROMINENT EARLIER IN KMKX REFLECTIVITY DATA. FRONT WILL CONTINUE
TO BACK-DOOR ITS WAY ACROSS NORTHEAST IL THROUGH THE REMAINDER OF
THE EVENING HOURS AND EVENTUALLY PUSHING INTO CENTRAL IL/IN
OVERNIGHT. WHILE COOLER TEMPS WILL SPREAD IN BEHIND THE FRONT...IT
APPEARS THE STRONGER COOLING/DRYING WILL LAG THE FRONT INTO THE
DAY THURSDAY GIVEN MODEST NORTHEAST WINDS OVERNIGHT.
TEMPS/HUMIDITY WILL ACTUALLY BE A LITTLE HIGHER BEHIND THE FRONT
TONIGHT THAN LAST NIGHT.
GOES 11-3.9 MICRON IR IMAGERY DOES INDICATE AREA OF LOW CLOUDS
(1100-1400 FT BASES) DEVELOPING BEHIND THE FRONT FROM EASTERN WI
INTO WESTERN LOWER MICHIGAN AT 01Z...THOUGH 18Z WRF-NAM SOUNDINGS
AND TSECTS APPEAR TO HAVE BACKED OFF A BIT ON THE DEPTH OF MOISTURE
THAT DEVELOPS OVER FAR NORTHERN/NORTHWESTERN IL BEHIND THE FRONT
OVERNIGHT AS WELL AS AREA OF LIGHT PRECIP OVER NORTHWEST IL. 00Z
RAOB ANALYSIS AT 925-850MB LEVELS DOES INDICATE LOW LEVEL THERMAL
RIDGE ALONG IA/MN BORDER REGION THAT MAY CONTINUE TO SUPPORT SOME
ASCENT ABOVE THE LOW LEVEL FRONTAL ZONE GIVEN STRONG NORTHWESTERLY
JET AND PRESENCE OF SHEARED MID-LEVEL SHORT WAVE...SO AM A LITTLE
HESITANT TO PULL CLOUDS/SPRINKLES OF GOING FORECAST. WILL SHIFT
TIMING A COUPLE HOURS PAST MIDNIGHT BUT OTHERWISE LEAVE ALONE AT
THIS POINT WITH LOCAL 8 KM WRF-ARW RUN ALSO STILL PRODUCING A LITTLE
QPF OVER SOUTHWEST WI/NORTHWEST IL TOWARD MORNING.
OTHERWISE...OTHER THAN ADJUSTMENTS TO HOURLY TEMP/WIND AND SKY COVER
GRIDS NO OTHER SIGNIFICANT CHANGES MADE TO NEAR TERM OF FORECAST FOR
THE OVERNIGHT HOURS.
RATZER
//PREV DISCUSSION...
300 PM CDT
THE FORECAST CHALLENGES ARE MAINLY TEMPERATURES AS SUMMER LOOKS TO
WIN OUT OVER AUTUMN IN THE EARLY GOING OF SEPTEMBER.
SYNOPSIS...IMPRESSIVELY DEEP UPPER TROUGH OVER EASTERN CANADA IS
BEING REINFORCED THIS AFTERNOON WITH A VIGOROUS JET DIVING INTO
THE UPPER GREAT LAKES. AS A GEE-WHIZ AND A SIGN OF THE CHANGE IN
SEASONS...NOT HERE YET BUT UP NORTH...850MB TEMPS AT CWZC ON THE
SOUTHERN END OF JAMES BAY DROPPED FROM +11C LAST NIGHT TO -5C THIS
MORNING UNDER THAT UPPER TROUGH. AN ASSOCIATED SURFACE COLD FRONT
IS DRAPED FROM LAKE ONTARIO THROUGH CENTRAL WI INTO SOUTHERN MN.
THIS FRONT HAS BEEN MOVING SLOWLY BUT CONSISTENTLY SOUTHWARD TODAY
WITH A RIBBON OF STRATUS/STRATOCU BEHIND IT. ALSO SEEN UPSTREAM IS A
SHEARING OUT SHORTWAVE ACROSS NW MN WHICH WILL CONTINUE TO MOVE
SOUTHEASTWARD.
TONIGHT...GIVEN THE COLD FRONT ORIENTATION AND THE LOSS OF MIXING
OF WESTERLY WINDS...EXPECT THE SURFACE COLD FRONT TO PROGRESS
QUICKER DOWN THE LAKE THIS EVENING...REACHING CHICAGO BY JUST
AFTER SUNDOWN OR SO. THIS WILL MEAN A TURN TO NORTHEAST WINDS AND
A DROP IN TEMPERATURE BY SEVERAL DEGREES LIKELY IN JUST A COUPLE
HOURS. READINGS SHOULD THEN STABILIZE NEAR THE LAKE GIVEN THE
STILL MILD WATER TEMPERATURES. THE NAM AND RAP SOUNDINGS ALONG
WITH COLD AIR ADVECTION AND RH FIELDS SUPPORT AT LEAST PATCHY
STRATUS MAKING IT DOWN INTO THE AREA NOT LONG BEHIND THE FRONT.
LOW-LEVEL THERMAL PROFILES ALSO HOVER AROUND LAPSE RATES
SUPPORTIVE OF LAKE-INDUCED CLOUDS. WITH THESE FORECASTS MESHING
WITH OBSERVATIONAL TRENDS UPSTREAM...HAVE BUMPED UP SKY COVER
LATER THIS EVE INTO OVERNIGHT. ALSO...AFOREMENTIONED SHEARING
SHORT WAVE OVER NW MN WILL RIDE A TIGHT 600-800MB THERMAL GRADIENT
INTO NW/NC IL BY EARLY OVERNIGHT. NAM FORECAST SOUNDINGS OVER RFD
WOULD CONTINUE TO SUPPORT A CHANCE FOR SOME SPRINKLES LATE AS THE
WAVE OVERRIDES SOME OF THE LOWER LEVEL MOISTURE. SO CONTINUE THAT
IN THE FORECAST BUT HAVE JUST BACKED UP IN TIME. WHILE A COLD
FRONT IS EASING THROUGH...TEMPERATURES WILL END UP SEVERAL DEGREES
WARMER THAN LAST NIGHT WITH MORE OF A WIND COMPONENT AND
INCREASING CLOUD COVER ACTING AS INSULATION.
THURSDAY THROUGH SATURDAY...FAIRLY QUIET WEATHER INTO FRIDAY
CONTINUES TO BE THE TREND IN THE WEATHER PATTERN. NORTHEAST WINDS
WILL CONTINUE INTO THU WITH TEMPERATURES IN THE 70S ACROSS AREAS
NORTH OF I-80. WARM AIR ADVECTION BEGINS FRIDAY AS THE HIGHS
SHIFTS EAST. THE 04.00 EC WAS FAIRLY SHARP WITH THIS ALOFT AND
HAVING A COINCIDENT SHORT WAVE WITH OUTPUT QPF. ITS MORE CURRENT
RUN IS MORE IN LINE WITH OTHER GUIDANCE...THAT IS DRIER AND
CONTINUE AS SUCH IN THE FORECAST. NEXT SHORT WAVE DROPS OVER THE
GREAT LAKES WITH ASSOCIATED WEAK SURFACE COLD FRONT OOZING
SOUTHWARD ON SAT. BEST LAPSE RATES AND MOISTURE ARE REALLY
CONFINED TO THE FRONT...SO DO NOT INTRODUCE SHOWER CHANCES UNTIL
SAT AFTERNOON AND AT THAT LOW AT THIS TIME. TEMPS RIGHT NOW LOOK
TO BE IN THE MID 80S FOR SAT GIVEN LOCAL CLIMATOLOGY...AND GIVEN
LOW-LEVEL THERMAL VALUES WHAT THEY WERE TODAY BUT WITH EVEN MORE
SW ADVECTION.
MTF
EXTENDED FORECAST SAT NIGHT-WED...WEAK COLD FRONT CONTINUES TO DROP
SOUTH THROUGH THE AREA SATURDAY EVENING INTO SUNDAY. WILL KEEP LOW
POPS FOR SATURDAY NIGHT...AND FOR THE SOUTHERN PART OF THE FORECAST
AREA SUNDAY. HIGH PRESSURE MOVES ACROSS THE LAKES SUNDAY WITH
NORTHEAST SURFACE WINDS. THIS SHOULD BRING DRY AND A LITTLE COOLER
WEATHER...ESPECIALLY NEAR THE LAKE. SUNDAY NIGHT INTO MONDAY THE
UPPER RIDGE AXIS SHIFTS EAST TOWARD THE GREAT LAKES AND THE SURFACE
HIGH SHIFTS EAST BRINGING A RETURN TO SOUTHERLY FLOW AND WARMER
WEATHER. GUIDANCE PRODUCING SLIGHT CHANCE POPS MOST PERIODS DAYS 4
THOUGH 7 BUT DON`T SEE ANY REAL FOCUS FOR THUNDERSTORMS SUNDAY NIGHT
THROUGH MONDAY NIGHT OR TUESDAY. AS UPPER RIDGE AXIS PUSHES EAST
THROUGH THE GREAT LAKES THE HEAT DOMES SPREADS EAST. TUESDAY LOOKS
ESPECIALLY WARM WITH GFS 925 MB TEMPS 26-28C AND ECMWF EVEN A BIT
WARMER WITH STRONG WSW FLOW. LOOKING AT CIPS ANALOGS...SIMILAR
PATTERNS IN LATE AUGUST AND SEPTEMBER YIELDED SURFACE TEMPS MOSTLY
IN THE LOWER 90S. HAVE BUMPED UP MAX TEMPS OVER GUIDANCE FOR
TUESDAY. NOT GOING TO GO WILD WITH TEMPS 6 DAYS OUT...BUT WILL
CONTINUE TO MONITOR. COULD SEE NEAR RECORD HIGHS TUESDAY IF MODELS
PAN OUT AND WE GET ENOUGH SUNSHINE. UPPER TROF MOVES ACROSS THE
UPPER LAKES AND TRAILING SURFACE COLD FRONT APPROACHES THE FORECAST
AREA TUESDAY NIGHT INTO WEDNESDAY FOR THE BEST CHANCE OF
THUNDERSTORMS IN THE EXTENDED PERIOD.
ALLSOPP
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* TIMING OF WIND SHIFT ASSOCIATED WITH FRONTAL PASSAGE.
KREIN
//DISCUSSION...UPDATED 00Z...
MAIN CONCERN FOR THE PERIOD WILL BE TIMING OF THE WIND SHIFT
ASSOCIATED WITH A COLD FRONT PUSHING DOWN LAKE MICHIGAN. WINDS
WILL REMAIN WLY-WNWLY AT LESS THAN 10 KT IN A WEAK GRADIENT
PATTERN AHEAD OF THE FRONT. LATEST OBSERVATIONS AND SHORT RANGE
MODEL GUIDANCE SUGGESTS THAT THE WIND SHIFT WITH THE FRONTAL
PASSAGE SHOULD BE FAIRLY ABRUPT...SO HAVE ADJUSTED THE WIND
DIRECTION IN THE FORECAST TO REFLECT THIS ABRUPT SHIFT TO NELY. AS
COOLER AIR FILTERS IN BEHIND THE FRONT...SOME GUSTINESS IS LIKELY
BUT THERE MAY BE A LAG BETWEEN THE INITIAL WIND SHIFT AND THE
INCREASING COLD ADVECTION FOLLOWING THE FROPA...SO HAVE MAINTAINED
THE TIMING OF THE GUSTINESS IN THE GOING FORECAST. THE ONLY OTHER
ADJUSTMENT IS TO REMOVE THE MENTION OF MVFR CIGS. WHILE THERE MAY
STILL BE SOME LOWER ST/STRATOCU DEVELOPMENT FOLLOWING THE
FROPA...FORECAST MOISTURE PROFILES ARE TRENDING A BIT DRIER SO
CURRENTLY DO NOT FEEL THAT MVFR CIGS ARE AS LIKELY.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* MEDIUM CONFIDENCE IN TIMING OF THE WIND SHIFT WITH THE FROPA.
* MEDIUM TO HIGH CONFIDENCE IN WIND TRENDS OTHER THAN TIMING THE FROPA.
* MEDIUM CONFIDENCE IN CLOUD COVER TRENDS.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
KREIN
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...VFR. WX NIL.
SATURDAY...CHANCE TSRA LATE AFTERNOON AND OVERNIGHT.
SUNDAY...SLIGHT CHANCE OF TSRA...OTHERWISE VFR.
MONDAY...SLIGHT CHANCE OF TSRA EARLY...OTHERWISE VFR.
TUESDAY...SLIGHT CHANCE OF TSRA...OTHERWISE VFR.
KREIN
&&
.MARINE...
229 PM CDT
A COLD FRONT IS STARTING TO MAKE ITS WAY DOWN LAKE MICHIGAN THIS
AFTERNOON WITH A PUSH OF NORTH-NORTHEASTERLY FLOW BEHIND THE FRONT
INCREASING THE WINDS INTO THE 15 TO 20 KT RANGE WITH OCCASIONAL
GUSTS TO 25 KT POSSIBLE. THE FRONT SHOULD CLEAR THE SOUTH END OF THE
LAKE AROUND MIDNIGHT TONIGHT. WITH A DECENT FETCH DOWN THE
LAKE...WAVES ARE EXPECTED TO BUILD INTO THE 3 TO 6 FT RANGE AT THE
SOUTH END OF THE LAKE PROMPTING A SMALL CRAFT ADVISORY FOR MAINLY
THE ILLINOIS NEARSHORE WATERS LATE THIS EVENING AND OVERNIGHT.
THESE CONDITIONS SHOULD SUBSIDE BACK BELOW CRITERIA THURSDAY
AFTERNOON AS HIGH PRESSURE PASSES OVER THE LAKE. AS THE HIGH
SHIFTS OVER THE EASTERN LAKES FRIDAY...SOUTHERLY FLOW INCREASES
AGAIN ACROSS THE LAKE. ANOTHER FRONT IS EXPECTED TO SAG SOUTH
ACROSS THE LAKE SATURDAY NIGHT INTO EARLY SUNDAY.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM THURSDAY TO 5 AM
FRIDAY.
IN...BEACH HAZARDS STATEMENT...INZ001...4 AM THURSDAY TO 5 AM FRIDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...4 AM
THURSDAY TO 3 PM THURSDAY.
&&
$$
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FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
841 PM CDT WED SEP 4 2013
.DISCUSSION...
840 PM CDT
FOR EVENING UPDATE...
MAINLY ONLY MINOR ADJUSTMENTS BASED ON OBS/SATELLITE TRENDS THIS
EVENING.
SURFACE COLD FRONT WAS JUST ENTERING FAR NORTHEASTERN LAKE COUNTY
IL AT 01Z PER SFC OBS AND EXTRAPOLATION OF BOUNDARY THAT WAS
PROMINENT EARLIER IN KMKX REFLECTIVITY DATA. FRONT WILL CONTINUE
TO BACK-DOOR ITS WAY ACROSS NORTHEAST IL THROUGH THE REMAINDER OF
THE EVENING HOURS AND EVENTUALLY PUSHING INTO CENTRAL IL/IN
OVERNIGHT. WHILE COOLER TEMPS WILL SPREAD IN BEHIND THE FRONT...IT
APPEARS THE STRONGER COOLING/DRYING WILL LAG THE FRONT INTO THE
DAY THURSDAY GIVEN MODEST NORTHEAST WINDS OVERNIGHT.
TEMPS/HUMIDITY WILL ACTUALLY BE A LITTLE HIGHER BEHIND THE FRONT
TONIGHT THAN LAST NIGHT.
GOES 11-3.9 MICRON IR IMAGERY DOES INDICATE AREA OF LOW CLOUDS
(1100-1400 FT BASES) DEVELOPING BEHIND THE FRONT FROM EASTERN WI
INTO WESTERN LOWER MICHIGAN AT 01Z...THOUGH 18Z WRF-NAM SOUNDINGS
AND TSECTS APPEAR TO HAVE BACKED OFF A BIT ON THE DEPTH OF MOISTURE
THAT DEVELOPS OVER FAR NORTHERN/NORTHWESTERN IL BEHIND THE FRONT
OVERNIGHT AS WELL AS AREA OF LIGHT PRECIP OVER NORTHWEST IL. 00Z
RAOB ANALYSIS AT 925-850MB LEVELS DOES INDICATE LOW LEVEL THERMAL
RIDGE ALONG IA/MN BORDER REGION THAT MAY CONTINUE TO SUPPORT SOME
ASCENT ABOVE THE LOW LEVEL FRONTAL ZONE GIVEN STRONG NORTHWESTERLY
JET AND PRESENCE OF SHEARED MID-LEVEL SHORT WAVE...SO AM A LITTLE
HESITANT TO PULL CLOUDS/SPRINKLES OF GOING FORECAST. WILL SHIFT
TIMING A COUPLE HOURS PAST MIDNIGHT BUT OTHERWISE LEAVE ALONE AT
THIS POINT WITH LOCAL 8 KM WRF-ARW RUN ALSO STILL PRODUCING A LITTLE
QPF OVER SOUTHWEST WI/NORTHWEST IL TOWARD MORNING.
OTHERWISE...OTHER THAN ADJUSTMENTS TO HOURLY TEMP/WIND AND SKY COVER
GRIDS NO OTHER SIGNIFICANT CHANGES MADE TO NEAR TERM OF FORECAST FOR
THE OVERNIGHT HOURS.
RATZER
&&
.PREV DISCUSSION...
300 PM CDT
THE FORECAST CHALLENGES ARE MAINLY TEMPERATURES AS SUMMER LOOKS TO
WIN OUT OVER AUTUMN IN THE EARLY GOING OF SEPTEMBER.
SYNOPSIS...IMPRESSIVELY DEEP UPPER TROUGH OVER EASTERN CANADA IS
BEING REINFORCED THIS AFTERNOON WITH A VIGOROUS JET DIVING INTO
THE UPPER GREAT LAKES. AS A GEE-WHIZ AND A SIGN OF THE CHANGE IN
SEASONS...NOT HERE YET BUT UP NORTH...850MB TEMPS AT CWZC ON THE
SOUTHERN END OF JAMES BAY DROPPED FROM +11C LAST NIGHT TO -5C THIS
MORNING UNDER THAT UPPER TROUGH. AN ASSOCIATED SURFACE COLD FRONT
IS DRAPED FROM LAKE ONTARIO THROUGH CENTRAL WI INTO SOUTHERN MN.
THIS FRONT HAS BEEN MOVING SLOWLY BUT CONSISTENTLY SOUTHWARD TODAY
WITH A RIBBON OF STRATUS/STRATOCU BEHIND IT. ALSO SEEN UPSTREAM IS A
SHEARING OUT SHORTWAVE ACROSS NW MN WHICH WILL CONTINUE TO MOVE
SOUTHEASTWARD.
TONIGHT...GIVEN THE COLD FRONT ORIENTATION AND THE LOSS OF MIXING
OF WESTERLY WINDS...EXPECT THE SURFACE COLD FRONT TO PROGRESS
QUICKER DOWN THE LAKE THIS EVENING...REACHING CHICAGO BY JUST
AFTER SUNDOWN OR SO. THIS WILL MEAN A TURN TO NORTHEAST WINDS AND
A DROP IN TEMPERATURE BY SEVERAL DEGREES LIKELY IN JUST A COUPLE
HOURS. READINGS SHOULD THEN STABILIZE NEAR THE LAKE GIVEN THE
STILL MILD WATER TEMPERATURES. THE NAM AND RAP SOUNDINGS ALONG
WITH COLD AIR ADVECTION AND RH FIELDS SUPPORT AT LEAST PATCHY
STRATUS MAKING IT DOWN INTO THE AREA NOT LONG BEHIND THE FRONT.
LOW-LEVEL THERMAL PROFILES ALSO HOVER AROUND LAPSE RATES
SUPPORTIVE OF LAKE-INDUCED CLOUDS. WITH THESE FORECASTS MESHING
WITH OBSERVATIONAL TRENDS UPSTREAM...HAVE BUMPED UP SKY COVER
LATER THIS EVE INTO OVERNIGHT. ALSO...AFOREMENTIONED SHEARING
SHORT WAVE OVER NW MN WILL RIDE A TIGHT 600-800MB THERMAL GRADIENT
INTO NW/NC IL BY EARLY OVERNIGHT. NAM FORECAST SOUNDINGS OVER RFD
WOULD CONTINUE TO SUPPORT A CHANCE FOR SOME SPRINKLES LATE AS THE
WAVE OVERRIDES SOME OF THE LOWER LEVEL MOISTURE. SO CONTINUE THAT
IN THE FORECAST BUT HAVE JUST BACKED UP IN TIME. WHILE A COLD
FRONT IS EASING THROUGH...TEMPERATURES WILL END UP SEVERAL DEGREES
WARMER THAN LAST NIGHT WITH MORE OF A WIND COMPONENT AND
INCREASING CLOUD COVER ACTING AS INSULATION.
THURSDAY THROUGH SATURDAY...FAIRLY QUIET WEATHER INTO FRIDAY
CONTINUES TO BE THE TREND IN THE WEATHER PATTERN. NORTHEAST WINDS
WILL CONTINUE INTO THU WITH TEMPERATURES IN THE 70S ACROSS AREAS
NORTH OF I-80. WARM AIR ADVECTION BEGINS FRIDAY AS THE HIGHS
SHIFTS EAST. THE 04.00 EC WAS FAIRLY SHARP WITH THIS ALOFT AND
HAVING A COINCIDENT SHORT WAVE WITH OUTPUT QPF. ITS MORE CURRENT
RUN IS MORE IN LINE WITH OTHER GUIDANCE...THAT IS DRIER AND
CONTINUE AS SUCH IN THE FORECAST. NEXT SHORT WAVE DROPS OVER THE
GREAT LAKES WITH ASSOCIATED WEAK SURFACE COLD FRONT OOZING
SOUTHWARD ON SAT. BEST LAPSE RATES AND MOISTURE ARE REALLY
CONFINED TO THE FRONT...SO DO NOT INTRODUCE SHOWER CHANCES UNTIL
SAT AFTERNOON AND AT THAT LOW AT THIS TIME. TEMPS RIGHT NOW LOOK
TO BE IN THE MID 80S FOR SAT GIVEN LOCAL CLIMATOLOGY...AND GIVEN
LOW-LEVEL THERMAL VALUES WHAT THEY WERE TODAY BUT WITH EVEN MORE
SW ADVECTION.
MTF
EXTENDED FORECAST SAT NIGHT-WED...WEAK COLD FRONT CONTINUES TO DROP
SOUTH THROUGH THE AREA SATURDAY EVENING INTO SUNDAY. WILL KEEP LOW
POPS FOR SATURDAY NIGHT...AND FOR THE SOUTHERN PART OF THE FORECAST
AREA SUNDAY. HIGH PRESSURE MOVES ACROSS THE LAKES SUNDAY WITH
NORTHEAST SURFACE WINDS. THIS SHOULD BRING DRY AND A LITTLE COOLER
WEATHER...ESPECIALLY NEAR THE LAKE. SUNDAY NIGHT INTO MONDAY THE
UPPER RIDGE AXIS SHIFTS EAST TOWARD THE GREAT LAKES AND THE SURFACE
HIGH SHIFTS EAST BRINGING A RETURN TO SOUTHERLY FLOW AND WARMER
WEATHER. GUIDANCE PRODUCING SLIGHT CHANCE POPS MOST PERIODS DAYS 4
THOUGH 7 BUT DON`T SEE ANY REAL FOCUS FOR THUNDERSTORMS SUNDAY NIGHT
THROUGH MONDAY NIGHT OR TUESDAY. AS UPPER RIDGE AXIS PUSHES EAST
THROUGH THE GREAT LAKES THE HEAT DOMES SPREADS EAST. TUESDAY LOOKS
ESPECIALLY WARM WITH GFS 925 MB TEMPS 26-28C AND ECMWF EVEN A BIT
WARMER WITH STRONG WSW FLOW. LOOKING AT CIPS ANALOGS...SIMILAR
PATTERNS IN LATE AUGUST AND SEPTEMBER YIELDED SURFACE TEMPS MOSTLY
IN THE LOWER 90S. HAVE BUMPED UP MAX TEMPS OVER GUIDANCE FOR
TUESDAY. NOT GOING TO GO WILD WITH TEMPS 6 DAYS OUT...BUT WILL
CONTINUE TO MONITOR. COULD SEE NEAR RECORD HIGHS TUESDAY IF MODELS
PAN OUT AND WE GET ENOUGH SUNSHINE. UPPER TROF MOVES ACROSS THE
UPPER LAKES AND TRAILING SURFACE COLD FRONT APPROACHES THE FORECAST
AREA TUESDAY NIGHT INTO WEDNESDAY FOR THE BEST CHANCE OF
THUNDERSTORMS IN THE EXTENDED PERIOD.
ALLSOPP
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* TIMING OF WIND SHIFT ASSOCIATED WITH FRONTAL PASSAGE.
KREIN
//DISCUSSION...UPDATED 00Z...
MAIN CONCERN FOR THE PERIOD WILL BE TIMING OF THE WIND SHIFT
ASSOCIATED WITH A COLD FRONT PUSHING DOWN LAKE MICHIGAN. WINDS
WILL REMAIN WLY-WNWLY AT LESS THAN 10 KT IN A WEAK GRADIENT
PATTERN AHEAD OF THE FRONT. LATEST OBSERVATIONS AND SHORT RANGE
MODEL GUIDANCE SUGGESTS THAT THE WIND SHIFT WITH THE FRONTAL
PASSAGE SHOULD BE FAIRLY ABRUPT...SO HAVE ADJUSTED THE WIND
DIRECTION IN THE FORECAST TO REFLECT THIS ABRUPT SHIFT TO NELY. AS
COOLER AIR FILTERS IN BEHIND THE FRONT...SOME GUSTINESS IS LIKELY
BUT THERE MAY BE A LAG BETWEEN THE INITIAL WIND SHIFT AND THE
INCREASING COLD ADVECTION FOLLOWING THE FROPA...SO HAVE MAINTAINED
THE TIMING OF THE GUSTINESS IN THE GOING FORECAST. THE ONLY OTHER
ADJUSTMENT IS TO REMOVE THE MENTION OF MVFR CIGS. WHILE THERE MAY
STILL BE SOME LOWER ST/STRATOCU DEVELOPMENT FOLLOWING THE
FROPA...FORECAST MOISTURE PROFILES ARE TRENDING A BIT DRIER SO
CURRENTLY DO NOT FEEL THAT MVFR CIGS ARE AS LIKELY.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* MEDIUM CONFIDENCE IN TIMING OF THE WIND SHIFT WITH THE FROPA.
* MEDIUM TO HIGH CONFIDENCE IN WIND TRENDS OTHER THAN TIMING THE FROPA.
* MEDIUM CONFIDENCE IN CLOUD COVER TRENDS.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
KREIN
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...VFR. WX NIL.
SATURDAY...CHANCE TSRA LATE AFTERNOON AND OVERNIGHT.
SUNDAY...SLIGHT CHANCE OF TSRA...OTHERWISE VFR.
MONDAY...SLIGHT CHANCE OF TSRA EARLY...OTHERWISE VFR.
TUESDAY...SLIGHT CHANCE OF TSRA...OTHERWISE VFR.
KREIN
&&
.MARINE...
229 PM CDT
A COLD FRONT IS STARTING TO MAKE ITS WAY DOWN LAKE MICHIGAN THIS
AFTERNOON WITH A PUSH OF NORTH-NORTHEASTERLY FLOW BEHIND THE FRONT
INCREASING THE WINDS INTO THE 15 TO 20 KT RANGE WITH OCCASIONAL
GUSTS TO 25 KT POSSIBLE. THE FRONT SHOULD CLEAR THE SOUTH END OF THE
LAKE AROUND MIDNIGHT TONIGHT. WITH A DECENT FETCH DOWN THE
LAKE...WAVES ARE EXPECTED TO BUILD INTO THE 3 TO 6 FT RANGE AT THE
SOUTH END OF THE LAKE PROMPTING A SMALL CRAFT ADVISORY FOR MAINLY
THE ILLINOIS NEARSHORE WATERS LATE THIS EVENING AND OVERNIGHT.
THESE CONDITIONS SHOULD SUBSIDE BACK BELOW CRITERIA THURSDAY
AFTERNOON AS HIGH PRESSURE PASSES OVER THE LAKE. AS THE HIGH
SHIFTS OVER THE EASTERN LAKES FRIDAY...SOUTHERLY FLOW INCREASES
AGAIN ACROSS THE LAKE. ANOTHER FRONT IS EXPECTED TO SAG SOUTH
ACROSS THE LAKE SATURDAY NIGHT INTO EARLY SUNDAY.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM THURSDAY TO 5 AM
FRIDAY.
IN...BEACH HAZARDS STATEMENT...INZ001...4 AM THURSDAY TO 5 AM FRIDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...4 AM
THURSDAY TO 3 PM THURSDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
623 PM CDT WED SEP 4 2013
.DISCUSSION...
300 PM CDT
THE FORECAST CHALLENGES ARE MAINLY TEMPERATURES AS SUMMER LOOKS TO
WIN OUT OVER AUTUMN IN THE EARLY GOING OF SEPTEMBER.
SYNOPSIS...IMPRESSIVELY DEEP UPPER TROUGH OVER EASTERN CANADA IS
BEING REINFORCED THIS AFTERNOON WITH A VIGOROUS JET DIVING INTO
THE UPPER GREAT LAKES. AS A GEE-WHIZ AND A SIGN OF THE CHANGE IN
SEASONS...NOT HERE YET BUT UP NORTH...850MB TEMPS AT CWZC ON THE
SOUTHERN END OF JAMES BAY DROPPED FROM +11C LAST NIGHT TO -5C THIS
MORNING UNDER THAT UPPER TROUGH. AN ASSOCIATED SURFACE COLD FRONT
IS DRAPED FROM LAKE ONTARIO THROUGH CENTRAL WI INTO SOUTHERN MN.
THIS FRONT HAS BEEN MOVING SLOWLY BUT CONSISTENTLY SOUTHWARD TODAY
WITH A RIBBON OF STRATUS/STRATOCU BEHIND IT. ALSO SEEN UPSTREAM IS A
SHEARING OUT SHORTWAVE ACROSS NW MN WHICH WILL CONTINUE TO MOVE
SOUTHEASTWARD.
TONIGHT...GIVEN THE COLD FRONT ORIENTATION AND THE LOSS OF MIXING
OF WESTERLY WINDS...EXPECT THE SURFACE COLD FRONT TO PROGRESS
QUICKER DOWN THE LAKE THIS EVENING...REACHING CHICAGO BY JUST
AFTER SUNDOWN OR SO. THIS WILL MEAN A TURN TO NORTHEAST WINDS AND
A DROP IN TEMPERATURE BY SEVERAL DEGREES LIKELY IN JUST A COUPLE
HOURS. READINGS SHOULD THEN STABILIZE NEAR THE LAKE GIVEN THE
STILL MILD WATER TEMPERATURES. THE NAM AND RAP SOUNDINGS ALONG
WITH COLD AIR ADVECTION AND RH FIELDS SUPPORT AT LEAST PATCHY
STRATUS MAKING IT DOWN INTO THE AREA NOT LONG BEHIND THE FRONT.
LOW-LEVEL THERMAL PROFILES ALSO HOVER AROUND LAPSE RATES
SUPPORTIVE OF LAKE-INDUCED CLOUDS. WITH THESE FORECASTS MESHING
WITH OBSERVATIONAL TRENDS UPSTREAM...HAVE BUMPED UP SKY COVER
LATER THIS EVE INTO OVERNIGHT. ALSO...AFOREMENTIONED SHEARING
SHORT WAVE OVER NW MN WILL RIDE A TIGHT 600-800MB THERMAL GRADIENT
INTO NW/NC IL BY EARLY OVERNIGHT. NAM FORECAST SOUNDINGS OVER RFD
WOULD CONTINUE TO SUPPORT A CHANCE FOR SOME SPRINKLES LATE AS THE
WAVE OVERRIDES SOME OF THE LOWER LEVEL MOISTURE. SO CONTINUE THAT
IN THE FORECAST BUT HAVE JUST BACKED UP IN TIME. WHILE A COLD
FRONT IS EASING THROUGH...TEMPERATURES WILL END UP SEVERAL DEGREES
WARMER THAN LAST NIGHT WITH MORE OF A WIND COMPONENT AND
INCREASING CLOUD COVER ACTING AS INSULATION.
THURSDAY THROUGH SATURDAY...FAIRLY QUIET WEATHER INTO FRIDAY
CONTINUES TO BE THE TREND IN THE WEATHER PATTERN. NORTHEAST WINDS
WILL CONTINUE INTO THU WITH TEMPERATURES IN THE 70S ACROSS AREAS
NORTH OF I-80. WARM AIR ADVECTION BEGINS FRIDAY AS THE HIGHS
SHIFTS EAST. THE 04.00 EC WAS FAIRLY SHARP WITH THIS ALOFT AND
HAVING A COINCIDENT SHORT WAVE WITH OUTPUT QPF. ITS MORE CURRENT
RUN IS MORE IN LINE WITH OTHER GUIDANCE...THAT IS DRIER AND
CONTINUE AS SUCH IN THE FORECAST. NEXT SHORT WAVE DROPS OVER THE
GREAT LAKES WITH ASSOCIATED WEAK SURFACE COLD FRONT OOZING
SOUTHWARD ON SAT. BEST LAPSE RATES AND MOISTURE ARE REALLY
CONFINED TO THE FRONT...SO DO NOT INTRODUCE SHOWER CHANCES UNTIL
SAT AFTERNOON AND AT THAT LOW AT THIS TIME. TEMPS RIGHT NOW LOOK
TO BE IN THE MID 80S FOR SAT GIVEN LOCAL CLIMATOLOGY...AND GIVEN
LOW-LEVEL THERMAL VALUES WHAT THEY WERE TODAY BUT WITH EVEN MORE
SW ADVECTION.
MTF
EXTENDED FORECAST SAT NIGHT-WED...WEAK COLD FRONT CONTINUES TO DROP
SOUTH THROUGH THE AREA SATURDAY EVENING INTO SUNDAY. WILL KEEP LOW
POPS FOR SATURDAY NIGHT...AND FOR THE SOUTHERN PART OF THE FORECAST
AREA SUNDAY. HIGH PRESSURE MOVES ACROSS THE LAKES SUNDAY WITH
NORTHEAST SURFACE WINDS. THIS SHOULD BRING DRY AND A LITTLE COOLER
WEATHER...ESPECIALLY NEAR THE LAKE. SUNDAY NIGHT INTO MONDAY THE
UPPER RIDGE AXIS SHIFTS EAST TOWARD THE GREAT LAKES AND THE SURFACE
HIGH SHIFTS EAST BRINGING A RETURN TO SOUTHERLY FLOW AND WARMER
WEATHER. GUIDANCE PRODUCING SLIGHT CHANCE POPS MOST PERIODS DAYS 4
THOUGH 7 BUT DON`T SEE ANY REAL FOCUS FOR THUNDERSTORMS SUNDAY NIGHT
THROUGH MONDAY NIGHT OR TUESDAY. AS UPPER RIDGE AXIS PUSHES EAST
THROUGH THE GREAT LAKES THE HEAT DOMES SPREADS EAST. TUESDAY LOOKS
ESPECIALLY WARM WITH GFS 925 MB TEMPS 26-28C AND ECMWF EVEN A BIT
WARMER WITH STRONG WSW FLOW. LOOKING AT CIPS ANALOGS...SIMILAR
PATTERNS IN LATE AUGUST AND SEPTEMBER YIELDED SURFACE TEMPS MOSTLY
IN THE LOWER 90S. HAVE BUMPED UP MAX TEMPS OVER GUIDANCE FOR
TUESDAY. NOT GOING TO GO WILD WITH TEMPS 6 DAYS OUT...BUT WILL
CONTINUE TO MONITOR. COULD SEE NEAR RECORD HIGHS TUESDAY IF MODELS
PAN OUT AND WE GET ENOUGH SUNSHINE. UPPER TROF MOVES ACROSS THE
UPPER LAKES AND TRAILING SURFACE COLD FRONT APPROACHES THE FORECAST
AREA TUESDAY NIGHT INTO WEDNESDAY FOR THE BEST CHANCE OF
THUNDERSTORMS IN THE EXTENDED PERIOD.
ALLSOPP
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* TIMING OF WIND SHIFT ASSOCIATED WITH FRONTAL PASSAGE.
KREIN
//DISCUSSION...UPDATED 00Z...
MAIN CONCERN FOR THE PERIOD WILL BE TIMING OF THE WIND SHIFT
ASSOCIATED WITH A COLD FRONT PUSHING DOWN LAKE MICHIGAN. WINDS
WILL REMAIN WLY-WNWLY AT LESS THAN 10 KT IN A WEAK GRADIENT
PATTERN AHEAD OF THE FRONT. LATEST OBSERVATIONS AND SHORT RANGE
MODEL GUIDANCE SUGGESTS THAT THE WIND SHIFT WITH THE FRONTAL
PASSAGE SHOULD BE FAIRLY ABRUPT...SO HAVE ADJUSTED THE WIND
DIRECTION IN THE FORECAST TO REFLECT THIS ABRUPT SHIFT TO NELY. AS
COOLER AIR FILTERS IN BEHIND THE FRONT...SOME GUSTINESS IS LIKELY
BUT THERE MAY BE A LAG BETWEEN THE INITIAL WIND SHIFT AND THE
INCREASING COLD ADVECTION FOLLOWING THE FROPA...SO HAVE MAINTAINED
THE TIMING OF THE GUSTINESS IN THE GOING FORECAST. THE ONLY OTHER
ADJUSTMENT IS TO REMOVE THE MENTION OF MVFR CIGS. WHILE THERE MAY
STILL BE SOME LOWER ST/STRATOCU DEVELOPMENT FOLLOWING THE
FROPA...FORECAST MOISTURE PROFILES ARE TRENDING A BIT DRIER SO
CURRENTLY DO NOT FEEL THAT MVFR CIGS ARE AS LIKELY.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* MEDIUM CONFIDENCE IN TIMING OF THE WIND SHIFT WITH THE FROPA.
* MEDIUM TO HIGH CONFIDENCE IN WIND TRENDS OTHER THAN TIMING THE FROPA.
* MEDIUM CONFIDENCE IN CLOUD COVER TRENDS.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
KREIN
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...VFR. WX NIL.
SATURDAY...CHANCE TSRA LATE AFTERNOON AND OVERNIGHT.
SUNDAY...SLIGHT CHANCE OF TSRA...OTHERWISE VFR.
MONDAY...SLIGHT CHANCE OF TSRA EARLY...OTHERWISE VFR.
TUESDAY...SLIGHT CHANCE OF TSRA...OTHERWISE VFR.
KREIN
&&
.MARINE...
229 PM CDT
A COLD FRONT IS STARTING TO MAKE ITS WAY DOWN LAKE MICHIGAN THIS
AFTERNOON WITH A PUSH OF NORTH-NORTHEASTERLY FLOW BEHIND THE FRONT
INCREASING THE WINDS INTO THE 15 TO 20 KT RANGE WITH OCCASIONAL
GUSTS TO 25 KT POSSIBLE. THE FRONT SHOULD CLEAR THE SOUTH END OF THE
LAKE AROUND MIDNIGHT TONIGHT. WITH A DECENT FETCH DOWN THE
LAKE...WAVES ARE EXPECTED TO BUILD INTO THE 3 TO 6 FT RANGE AT THE
SOUTH END OF THE LAKE PROMPTING A SMALL CRAFT ADVISORY FOR MAINLY
THE ILLINOIS NEARSHORE WATERS LATE THIS EVENING AND OVERNIGHT.
THESE CONDITIONS SHOULD SUBSIDE BACK BELOW CRITERIA THURSDAY
AFTERNOON AS HIGH PRESSURE PASSES OVER THE LAKE. AS THE HIGH
SHIFTS OVER THE EASTERN LAKES FRIDAY...SOUTHERLY FLOW INCREASES
AGAIN ACROSS THE LAKE. ANOTHER FRONT IS EXPECTED TO SAG SOUTH
ACROSS THE LAKE SATURDAY NIGHT INTO EARLY SUNDAY.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM THURSDAY TO 5 AM
FRIDAY.
IN...BEACH HAZARDS STATEMENT...INZ001...4 AM THURSDAY TO 5 AM FRIDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...4 AM
THURSDAY TO 3 PM THURSDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS DES MOINES IA
340 AM CDT TUE SEP 3 2013
.SHORT TERM.../TODAY/...
ISSUED AT 336 AM CDT TUE SEP 3 2013
BENIGN FORECAST ON TAP FOR TODAY. WE WILL HAVE SOME FOG TO DEAL
WITH THIS MORNING. SOUNDINGS SHOWING A VERY SHALLOW LAYER OF
MOISTURE WHICH IS PRODUCING PATCHY TO AREAS OF FOG REDUCING
VISIBILITIES TO BETWEEN A QUARTER TO A HALF MILE IN A FEW SPOTS.
VISIBILITIES GENERALLY BETWEEN 3 AND 5 MILES ELSEWHERE THAT FOG
EXISTS. THE FOG SHOULD BE VERY SHALLOW AND AS SUCH SHOULD BURN OFF
QUICKLY WITH SUNRISE. FOR THE REST OF TODAY...SURFACE HIGH PRESSURE
WILL SLOWLY SHIFT EAST THROUGH TODAY ALLOWING LIGHT SURFACE WINDS TO
SHIFT TO THE SOUTH. AIRMASS WILL STILL BE DRY WITH DEWPOINTS
STARTING OUT IN THE 40S AND 50S AND ONLY REACHING MID 50S BY LATE
AFTERNOON. ALOFT HIGH PRESSURE OVER THE ROCKIES/HIGH PLAINS WILL
KEEP THE AREA IN A NW FLOW. THE MODELS DO HINT AT A SHORTWAVE
APPROACHING THE NW VERY LATE THIS AFTERNOON BUT LIKELY NOT AFFECTING
OUR FORECAST AREA UNTIL THE EVENING. I DID RAISE HIGHS TODAY GIVEN
AMPLE SUN AND NOT A LOT OF MOISTURE AROUND BUT THIS IS TEMPERED BY
THE NW FLOW ALOFT AND SHALLOW WARMING WITH LITTLE MIXING. WIND
SPEEDS THROUGH 800 MB ARE BARELY 10 KTS. JUST A NICE EARLY
SEPTEMBER DAY.
.LONG TERM.../TONIGHT THROUGH MONDAY/...
ISSUED AT 336 AM CDT TUE SEP 3 2013
PATTERN WILL REMAIN ESSENTIALLY UNCHANGED THROUGH THE WEEK WITH
TEMPS THE PRIMARY CONCERN...FOLLOWED BY VERY SUBTLE PRECIP CHANCES.
TEMPS WILL CONTINUE TO WARM INTO WED AS H85/H7 RIDGE DRIFTS EAST AND
CURRENT SURFACE HIGH BECOMES LESS DOMINATE. A BRIEF RESURGENCE OF
A GREAT LAKES HIGH MAY BACK DOOR SOME SLIGHTLY COOLER TEMPERATURES
INTO IA BY THU...BUT THIS WILL BE SHORT LIVED AS RETURN FLOW
INCREASES ONCE AGAIN TO END THE WORK WEEK. NAM DRAWS IN COOLER AND
DRIER AIRMASS BUT THIS IS SOMEWHAT OF AN OUTLIER SO STAYED CLOSER
TO CONSENSUS. HAVE ALSO INCLUDED A SMALL PATCH OF SLIGHT CHANCES
WEST CENTRAL WED NIGHT IN SOME WEAK THERMODYNAMIC FORCING...BUT
SOUNDINGS SUGGEST ANYTHING THAT DOES FORM WOULD BE QUITE WEAK AND
ELEVATED. 305/310K ISENT ANALYSIS SHOWS VERY WEAK LIFT IN LIGHT WINDS.
MUCH ABOVE NORMAL TEMPERATURES BECOME THE MAIN THEME HEADING INTO
THE WEEKEND AND EARLY NEXT WEEK AS UPPER LEVEL RIDGE CROSSES THE
CENTRAL PLAINS INTO THE MID MS VALLEY. THIS WILL BOOST TEMPERATURES
EVEN FURTHER ABOVE NORMAL WITH HIGHS CREEPING THROUGH THE 90S.
PRECIP CHANCES GRADUALLY INCREASE LATE IN THE WEEKEND AS WEAK
SHORT WAVES TOP THE RIDGE AND POTENTIALLY INDUCE A WEAK
BAROCLINIC/FRONTOGENETICAL ZONE NW-SE ACROSS NERN IA. STRONGER
WARM ADVECTION SURGE LIFTS INTO THE UPPER MS VALLEY SUN
NIGHT...POSSIBLY GLANCING NRN IA BUT ALSO LIKELY INTRODUCING THE
WARMEST TEMPS OF THE PERIOD. HAVE NUDGED READINGS HIGHER...BUT
THESE MAY NOT EVEN BE WARM ENOUGH CONSIDERING MIXING AND FAVORABLE
SSW WINDS BY MON. NRN PLAINS SHORT WAVE WILL EVENTUALLY INCREASE
KINEMATIC FORCING INTO THE SIOUXLAND AREA BY LATE MON WHICH WOULD
ALSO BE COINCIDENT WITH THE ASSOCIATED FRONTAL BOUNDARY LEADING TO
SOMEWHAT BETTER PRECIP CHANCES. BEST POTENTIAL MAY BE JUST BEYOND
THE VALID PERIOD INTO MON NIGHT HOWEVER WITH FROPA EVENTUALLY DROPPING
TEMPS BACK CLOSER TO NORMAL INTO NEXT WEEK.
&&
.AVIATION...03/06Z
ISSUED AT 1135 PM CDT MON SEP 2 2013
MVFR TO IFR FOG POSSIBLY OVER THE NORTH AND NORTHEAST TAF AREAS
AND HAVE FOD/MCW/ALO DOWN TO IFR BY 09Z AS DEW POINT DEPRESSION IS
UNDER 2 WITH LIGHT WINDS. THE LATEST HRRR AND HOPWRF SHOW
VISIBILITY DROPPING BY 09Z THROUGH 12Z...AND LEANED TOWARD THIS
TIMING. LOW CONFIDENCE WITH ANY FOG AT DSM AND IF FOG DOES DEVELOP
IT WILL BE SHORTLY BEFORE SUNRISE AND NOT PERSIST TOO LONG.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...FAB
LONG TERM...SMALL
AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1142 PM CDT MON SEP 2 2013
...UPDATED AVIATION DISCUSSION...
.SHORT TERM.../TONIGHT /...
ISSUED AT 325 PM CDT MON SEP 2 2013
HIGH PRESSURE EXTENDING FROM NRN MN INTO KS WILL SETTLE OVER THE
STATE TONIGHT. WINDS WILL DIMINISH WITH SUNSET AND BE NEAR CALM
OVERNIGHT EXPECT TO SEE AREAS OF FOG DEVELOP TONIGHT. NOT ENOUGH
CONFIDENCE FOR ANY HEADLINES...BUT WILL HAVE FOG MENTIONED IN THE
WORDING OF THE FORECAST. TEMPS TONIGHT WILL BE IN THE 40S FOR MUCH
OF THE CWA...SOME LOW TO MID 50S IN THE SOUTH.
.LONG TERM.../TUESDAY THROUGH MONDAY/...
ISSUED AT 325 PM CDT MON SEP 2 2013
MAJORITY OF EXTENDED STILL LOOKS TRANQUIL WITH A GRADUAL WARMING
TREND. NORTHWEST FLOW PATTERN STILL EXPECTED ALOFT WITH LARGE
AMPLIFIED RIDGING ACROSS THE WESTERN US AND SFC HIGH PRESSURE
DOMINATING THE REGION TUESDAY INTO EARLY WEDNESDAY. WEAK SHORTWAVE
TROUGH STILL ON TAP TO DROP SOUTHEASTWARD THROUGH IOWA WEDNESDAY
INTO WEDNESDAY NIGHT. MOISTURE CONTINUES TO LOOK LIMITED WITH THE
BEST THETA-E ADVECTION TO THE WEST OF THE CWA NOW. THEREFORE HAVE
REMOVED ALL POPS FOR WEDNESDAY AND STUCK WITH MAINLY INCREASED CLOUD
COVER. UPPER RIDGE TO BREAK DOWN TOWARD THE WEEKEND...WITH AN UPPER
TROUGH MOVING ASHORE INTO THE NORTHERN ROCKIES SUNDAY. MOISTURE
RETURN TO INCREASE IN SOUTHERLY FLOW WITH WAA AND THETA-E ADVECTION
KICKING IN WITH PASSAGE OF A WEAK WARM FRONT SUNDAY. MAY SEE SOME
CHANCE FOR THUNDERSTORMS ACROSS THE NORTHERN CWA SUNDAY INTO SUNDAY
NIGHT. UPPER TROUGH TO TRACK EASTWARD ACROSS THE NORTHERN US AND
INTO THE GREAT LAKES REGION MONDAY INTO TUESDAY. ASSOCIATED COLD
FRONT TO DROP THROUGH THE CWA LATE MONDAY INTO MONDAY NIGHT. THIS
WILL PROVIDE ANOTHER CHANCE FOR PRECIPITATION ACROSS THE MAINLY THE
NORTHERN CWA MONDAY NIGHT. H85 TEMPS CLIMB INTO THE LOWER/MID 20S
CELSIUS AHEAD OF THE FRONT FRIDAY INTO SATURDAY/SUNDAY...SO HAVE
TEMPS WARMING BACK INTO THE UPPER 80S TO LOW 90S. ANOTHER
COOLER...DRY PERIOD SETTING UP BEYOND THE CURRENT FORECAST PERIOD
TOWARD THE MIDDLE TO END OF NEXT WEEK.
&&
.AVIATION...03/06Z
ISSUED AT 1135 PM CDT MON SEP 2 2013
MVFR TO IFR FOG POSSIBLY OVER THE NORTH AND NORTHEAST TAF AREAS
AND HAVE FOD/MCW/ALO DOWN TO IFR BY 09Z AS DEW POINT DEPRESSION IS
UNDER 2 WITH LIGHT WINDS. THE LATEST HRRR AND HOPWRF SHOW
VISIBILITY DROPPING BY 09Z THROUGH 12Z...AND LEANED TOWARD THIS
TIMING. LOW CONFIDENCE WITH ANY FOG AT DSM AND IF FOG DOES DEVELOP
IT WILL BE SHORTLY BEFORE SUNRISE AND NOT PERSIST TOO LONG.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...MS SEP13
LONG TERM...BEERENDS
AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS JACKSON KY
259 AM EDT TUE SEP 3 2013
.UPDATE...
ISSUED AT 1218 AM EDT TUE SEP 3 2013
LINE OF SHOWERS AND THUNDERSTORMS CONTINUE TO MOVE ALONG THE FAR
SOUTHERN AND EASTERN RELMS OF THE CWA. WITH A FEW MORE SHOWERS
DEVELOPING BEHIND MAIN LINE...WENT AHEAD AND ADDED IN A FEW MORE
HOURS OF SCT AND ISOLATED POPS BEHIND THE INITIAL LINE OF HIGHER
POPS. STILL EXPECT MUCH OF THE REGION TO BE CLEAR OVER THE NEXT 2 TO
3 HOURS. ALSO LOADED IN LATEST TEMPERATURE AND WIND OBSERVATIONS TO
MAKE SURE ONGOING FORECAST WAS MATCHING UP WELL WITH CURRENT
CONDITIONS.
UPDATE ISSUED AT 605 PM EDT MON SEP 2 2013
UPDATED THE FORECAST TO BETTER REFLECT CURRENT CONDITIONS AND MODEL
TRENDS. INCREASED THE CHANCES OF PRECIPITATION 10-20 PERCENT BASED
ON WHAT WAS SHOWING UP ON THE RADAR AND THE OUTPUT FROM THE RAPID
REFRESH MODEL. ALSO HAVE THE PRECIPITATION ENDING TONIGHT AND NOT
EXTEND INTO TUESDAY. THE NAM BUFR WAS SHOWING A DECREASE IN MID LEVEL
MOISTURE AND INCREASED CAPPING STARTING TO OCCUR OVER THE NEXT FEW
HOURS. THIS SHOULD HELP THE LOW THE THREAT FOR STRONG TO SEVERE
THUNDERSTORMS BY 8 PM. THE REST OF THE FORECAST IS ON TRACK.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 338 PM EDT MON SEP 2 2013
ISOLATED SHOWERS AND THUNDERSTORMS WERE AFFECTING THE AREA AT MID
AFTERNOON. THEY WERE INCREASING IN COVERAGE ALONG A LINE FROM
LOUISVILLE KY TO ZANESVILLE OH...ALONG AND AHEAD OF A COLD FRONT.
HAVE FOLLOWED THE FORECAST OF THE HRRR MODEL THROUGH THIS EVENING...
SHOWING THE GREATEST CONCENTRATION OF CONVECTION ALONG AND JUST AHEAD
OF THE COLD FRONT AS IT MOVES SE...WITH A BIT OF A DROP OFF IN
ACTIVITY AFTER NIGHTFALL. THIS PLACES HIGHEST POPS IN OUR NW COUNTIES
DURING THE LATE AFTERNOON AND EARLY EVENING. HAVE KEPT THEM IN THE
HIGH CHANCE RANGE THERE...AND USED POPS LOWER IN THE CHANCE RANGE
DURING THE NIGHT AS THE FRONT MOVES FURTHER SE. A FEW STRAGGLING
SHOWERS COULD BE LINGERING NEAR THE VA BORDER ON TUESDAY MORNING AS
THE FRONT LEAVES. HIGH PRESSURE BUILDING IN FROM THE NW BEHIND THE
FRONT WILL BRING IN A DRIER AIR MASS...WITH SKIES BECOMING MOSTLY
CLEAR FROM NW TO SE LATE TONIGHT AND TUESDAY AND PERSISTING THROUGH
TUESDAY NIGHT.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 259 AM EDT TUE SEP 3 2013
THE UPPER LEVEL PATTERN WILL START OFF AMPLIFIED WITH A LARGE RIDGE
CENTERED ACROSS THE ROCKIES...AN UPPER LOW CENTERED OFF THE PACIFIC
NORTHWEST COAST...AND DEEP TROUGHING EXTENDED FROM EASTERN CANADA
DOWN THROUGH NEW ENGLAND. THE MODELS ARE IN GOOD AGREEMENT...WITH A
GRADUAL DAMPENING TO TAKE PLACE IN GENERAL ACROSS THE WESTERN HALF
OF THE CONUS AS THE PACIFIC NORTHWEST UPPER LOW ADVANCES EAST ON THE
NORTHERN PERIPHERY OF THE RIDGE...WEAKENING BOTH FEATURES IN THE
PROCESS. THE TROUGHING TO THE EAST WILL BE SLOWER TO PULL OUT UNTIL
THE ROCKIES RIDGE SLIDES EAST INTO THE MISSISSIPPI VALLEY BY THE END
OF THE WEEK AND INTO EARLY NEXT WEEK.
ALL OF THIS WILL RESULT IN AN EXTENDED PERIOD OF GENERALLY DRY
WEATHER ACROSS EASTERN KENTUCKY...WITH SURFACE HIGH PRESSURE
REMAINING PARKED ACROSS THE AREA THROUGH FRIDAY...BEFORE IT BECOMES
MORE CONGEALED OFF OF THE THE EASTERN SEABOARD FOR THE WEEKEND AND
EARLY NEXT WEEK. ENOUGH MOISTURE MAY THEN RETURN TO JUSTIFY HANGING
ONTO SOME SLIGHT CHANCE POPS ALONG THE SOUTHEAST TERRAIN SUNDAY AND
MONDAY AFTERNOONS.
FOR TEMPERATURES...LOWS WILL START OUT IN THE 50S THROUGH THE END OF
THE WORK WEEK...WITH HIGHS MAINLY IN THE LOW TO MID 80S. WARMER AND
MORE HUMID AIR WILL THEN GRADUALLY INCREASE ACROSS THE AREA...
ALTHOUGH PEAK DEW POINTS IN THE AFTERNOON LOOK TO HOLD IN THE LOW TO
MID 60S...SO NOT AS BALMY AS WHAT WE HAVE BEEN ACCUSTOMED TO OVER
THE PAST SEVERAL DAYS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 219 AM EDT TUE SEP 3 2013
CONVECTION ASSOCIATED WITH A PASSING COLD FRONT IS CONTINUING TO MAKE
ITS WAY OUT OF EASTERN KY TONIGHT. IN ITS WAKE...A BAND OF CLOUDS
AND LOW LEVEL MOISTURE REMAIN ACROSS SOUTHEASTRN KY...EXITING THE
REGION AT A MUCH SLOWER RATE. JUST TO OUR NE...LATEST OBSERVATIONS ARE
SHOWING CONSIDERABLE DRYING. THIS BRINGS SOME UNCERTAINTY TO THE
FORECAST FOR THE TAF SITES CONCERNING THE DEVELOPMENT OF FOG OVERNIGHT.
IF THE LOWER DEW POINTS UPSTREAM AND DRY AIR ARE ABLE TO MAKE IT INTO
THE REGION THERE SHOULD BE NO FOG. HOWEVER IF THIS DRY AIR MOVES IN
AND TRAPS THE MOISTURE NEAR THE SURFACE AS MANY OF THE MODELS AND
GUIDANCE ARE PREDICTING...MUCH OF THE REGION COULD SEE SOME DEGREE OF
BR. THAT BEING SAID...FORECASTED TOWARDS FOG BUT DID NOT GO QUITE AS
LOW AS GUIDANCE SINCE DRY AIR WILL PROBABLY PLAY A BIGGER ROLE THAN
WHAT THE MODELS ARE PICKING UP ON. EXPECT KJKL AND KSME TO STAY MVFR
OR GREATER WITH THE N/NE WINDS COMING IN...WHILE LONDON COULD DROP
DOWN LOWER TO IFR /WITH POSSIBLE LIFR. WILL CONTINUE TO MONITOR
ONGOING CONDITIONS AND AMMEND AS NEEDED. ONCE FOG MIXES OUT AND LIFTS
IN THE MORNING...HIGH PRESSURE OVERHEAD SHOULD MAKE FOR VFR
CONDITIONS THROUGH THE REMAINDER OF THE TAF PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JMW
SHORT TERM...HAL
LONG TERM...GEOGERIAN/DUSTY
AVIATION...JMW
AREA FORECAST DISCUSSION
NWS JACKSON KY
220 AM EDT TUE SEP 3 2013
.UPDATE...
ISSUED AT 1218 AM EDT TUE SEP 3 2013
LINE OF SHOWERS AND THUNDERSTORMS CONTINUE TO MOVE ALONG THE FAR
SOUTHERN AND EASTERN RELMS OF THE CWA. WITH A FEW MORE SHOWERS
DEVELOPING BEHIND MAIN LINE...WENT AHEAD AND ADDED IN A FEW MORE
HOURS OF SCT AND ISOLATED POPS BEHIND THE INITIAL LINE OF HIGHER
POPS. STILL EXPECT MUCH OF THE REGION TO BE CLEAR OVER THE NEXT 2 TO
3 HOURS. ALSO LOADED IN LATEST TEMPERATURE AND WIND OBSERVATIONS TO
MAKE SURE ONGOING FORECAST WAS MATCHING UP WELL WITH CURRENT
CONDITIONS.
UPDATE ISSUED AT 605 PM EDT MON SEP 2 2013
UPDATED THE FORECAST TO BETTER REFLECT CURRENT CONDITIONS AND MODEL
TRENDS. INCREASED THE CHANCES OF PRECIPITATION 10-20 PERCENT BASED
ON WHAT WAS SHOWING UP ON THE RADAR AND THE OUTPUT FROM THE RAPID
REFRESH MODEL. ALSO HAVE THE PRECIPITATION ENDING TONIGHT AND NOT
EXTEND INTO TUESDAY. THE NAM BUFR WAS SHOWING A DECREASE IN MID LEVEL
MOISTURE AND INCREASED CAPPING STARTING TO OCCUR OVER THE NEXT FEW
HOURS. THIS SHOULD HELP THE LOW THE THREAT FOR STRONG TO SEVERE
THUNDERSTORMS BY 8 PM. THE REST OF THE FORECAST IS ON TRACK.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 338 PM EDT MON SEP 2 2013
ISOLATED SHOWERS AND THUNDERSTORMS WERE AFFECTING THE AREA AT MID
AFTERNOON. THEY WERE INCREASING IN COVERAGE ALONG A LINE FROM
LOUISVILLE KY TO ZANESVILLE OH...ALONG AND AHEAD OF A COLD FRONT.
HAVE FOLLOWED THE FORECAST OF THE HRRR MODEL THROUGH THIS EVENING...
SHOWING THE GREATEST CONCENTRATION OF CONVECTION ALONG AND JUST AHEAD
OF THE COLD FRONT AS IT MOVES SE...WITH A BIT OF A DROP OFF IN
ACTIVITY AFTER NIGHTFALL. THIS PLACES HIGHEST POPS IN OUR NW COUNTIES
DURING THE LATE AFTERNOON AND EARLY EVENING. HAVE KEPT THEM IN THE
HIGH CHANCE RANGE THERE...AND USED POPS LOWER IN THE CHANCE RANGE
DURING THE NIGHT AS THE FRONT MOVES FURTHER SE. A FEW STRAGGLING
SHOWERS COULD BE LINGERING NEAR THE VA BORDER ON TUESDAY MORNING AS
THE FRONT LEAVES. HIGH PRESSURE BUILDING IN FROM THE NW BEHIND THE
FRONT WILL BRING IN A DRIER AIR MASS...WITH SKIES BECOMING MOSTLY
CLEAR FROM NW TO SE LATE TONIGHT AND TUESDAY AND PERSISTING THROUGH
TUESDAY NIGHT.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 338 PM EDT MON SEP 2 2013
THE UPPER LEVEL PATTERN WILL START OFF AMPLIFIED WITH A LARGE RIDGE
CENTERED ACROSS THE ROCKIES...AN UPPER LOW CENTERED OFF THE PACIFIC
NORTHWEST COAST...AND DEEP TROUGHING EXTENDED FROM EASTERN CANADA
DOWN THROUGH NEW ENGLAND. THE MODELS ARE IN GOOD AGREEMENT...WITH A
GRADUAL DAMPENING TO TAKE PLACE IN GENERAL ACROSS THE WESTERN HALF
OF THE CONUS AS THE PACIFIC NORTHWEST UPPER LOW ADVANCES EAST ON THE
NORTHERN PERIPHERY OF THE RIDGE...WEAKENING BOTH FEATURES IN THE
PROCESS. THE TROUGHING TO THE EAST WILL BE SLOWER TO PULL OUT UNTIL
THE ROCKIES RIDGE SLIDES EAST INTO THE MISSISSIPPI VALLEY BY THE END
OF THE WEEK AND INTO EARLY NEXT WEEK.
ALL OF THIS WILL RESULT IN AN EXTENDED PERIOD OF GENERALLY DRY
WEATHER ACROSS EASTERN KENTUCKY...WITH SURFACE HIGH PRESSURE
REMAINING PARKED ACROSS THE AREA THROUGH FRIDAY...BEFORE IT BECOMES
MORE CONGEALED OFF OF THE THE EASTERN SEABOARD FOR THE WEEKEND AND
EARLY NEXT WEEK. ENOUGH MOISTURE MAY THEN RETURN TO JUSTIFY HANGING
ONTO SOME SLIGHT CHANCE POPS ALONG THE SOUTHEAST TERRAIN SATURDAY
THROUGH MONDAY.
FOR TEMPERATURES...LOWS WILL START OUT IN THE 50S THROUGH THE END OF
THE WORK WEEK...WITH HIGHS MAINLY IN THE LOW TO MID 80S. WARMER AND
MORE HUMID AIR WILL THEN GRADUALLY INCREASE ACROSS THE
AREA...ALTHOUGH PEAK DEW POINTS IN THE AFTERNOON LOOK TO HOLD IN THE
LOW TO MID 60S...SO NOT AS BALMY AS WHAT WE HAVE BEEN ACCUSTOMED TO
OVER THE PAST SEVERAL DAYS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 219 AM EDT TUE SEP 3 2013
CONVECTION ASSOCIATED WITH A PASSING COLD FRONT IS CONTINUING TO MAKE
ITS WAY OUT OF EASTERN KY TONIGHT. IN ITS WAKE...A BAND OF CLOUDS
AND LOW LEVEL MOISTURE REMAIN ACROSS SOUTHEASTRN KY...EXITING THE
REGION AT A MUCH SLOWER RATE. JUST TO OUR NE...LATEST OBSERVATIONS ARE
SHOWING CONSIDERABLE DRYING. THIS BRINGS SOME UNCERTAINTY TO THE
FORECAST FOR THE TAF SITES CONCERNING THE DEVELOPMENT OF FOG OVERNIGHT.
IF THE LOWER DEW POINTS UPSTREAM AND DRY AIR ARE ABLE TO MAKE IT INTO
THE REGION THERE SHOULD BE NO FOG. HOWEVER IF THIS DRY AIR MOVES IN
AND TRAPS THE MOISTURE NEAR THE SURFACE AS MANY OF THE MODELS AND
GUIDANCE ARE PREDICTING...MUCH OF THE REGION COULD SEE SOME DEGREE OF
BR. THAT BEING SAID...FORECASTED TOWARDS FOG BUT DID NOT GO QUITE AS
LOW AS GUIDANCE SINCE DRY AIR WILL PROBABLY PLAY A BIGGER ROLE THAN
WHAT THE MODELS ARE PICKING UP ON. EXPECT KJKL AND KSME TO STAY MVFR
OR GREATER WITH THE N/NE WINDS COMING IN...WHILE LONDON COULD DROP
DOWN LOWER TO IFR /WITH POSSIBLE LIFR. WILL CONTINUE TO MONITOR
ONGOING CONDITIONS AND AMMEND AS NEEDED. ONCE FOG MIXES OUT AND LIFTS
IN THE MORNING...HIGH PRESSURE OVERHEAD SHOULD MAKE FOR VFR
CONDITIONS THROUGH THE REMAINDER OF THE TAF PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JMW
SHORT TERM...HAL
LONG TERM...GEOGERIAN
AVIATION...JMW
AREA FORECAST DISCUSSION
NWS JACKSON KY
1219 AM EDT TUE SEP 3 2013
.UPDATE...
ISSUED AT 1218 AM EDT TUE SEP 3 2013
LINE OF SHOWERS AND THUNDERSTORMS CONTINUE TO MOVE ALONG THE FAR
SOUTHERN AND EASTERN RELMS OF THE CWA. WITH A FEW MORE SHOWERS
DEVELOPING BEHIND MAIN LINE...WENT AHEAD AND ADDED IN A FEW MORE
HOURS OF SCT AND ISOLATED POPS BEHIND THE INITIAL LINE OF HIGHER
POPS. STILL EXPECT MUCH OF THE REGION TO BE CLEAR OVER THE NEXT 2 TO
3 HOURS. ALSO LOADED IN LATEST TEMPERATURE AND WIND OBSERVATIONS TO
MAKE SURE ONGOING FORECAST WAS MATCHING UP WELL WITH CURRENT
CONDITIONS.
UPDATE ISSUED AT 605 PM EDT MON SEP 2 2013
UPDATED THE FORECAST TO BETTER REFLECT CURRENT CONDITIONS AND MODEL
TRENDS. INCREASED THE CHANCES OF PRECIPITATION 10-20 PERCENT BASED
ON WHAT WAS SHOWING UP ON THE RADAR AND THE OUTPUT FROM THE RAPID
REFRESH MODEL. ALSO HAVE THE PRECIPITATION ENDING TONIGHT AND NOT
EXTEND INTO TUESDAY. THE NAM BUFR WAS SHOWING A DECREASE IN MID LEVEL
MOISTURE AND INCREASED CAPPING STARTING TO OCCUR OVER THE NEXT FEW
HOURS. THIS SHOULD HELP THE LOW THE THREAT FOR STRONG TO SEVERE
THUNDERSTORMS BY 8 PM. THE REST OF THE FORECAST IS ON TRACK.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 338 PM EDT MON SEP 2 2013
ISOLATED SHOWERS AND THUNDERSTORMS WERE AFFECTING THE AREA AT MID
AFTERNOON. THEY WERE INCREASING IN COVERAGE ALONG A LINE FROM
LOUISVILLE KY TO ZANESVILLE OH...ALONG AND AHEAD OF A COLD FRONT.
HAVE FOLLOWED THE FORECAST OF THE HRRR MODEL THROUGH THIS EVENING...
SHOWING THE GREATEST CONCENTRATION OF CONVECTION ALONG AND JUST AHEAD
OF THE COLD FRONT AS IT MOVES SE...WITH A BIT OF A DROP OFF IN
ACTIVITY AFTER NIGHTFALL. THIS PLACES HIGHEST POPS IN OUR NW COUNTIES
DURING THE LATE AFTERNOON AND EARLY EVENING. HAVE KEPT THEM IN THE
HIGH CHANCE RANGE THERE...AND USED POPS LOWER IN THE CHANCE RANGE
DURING THE NIGHT AS THE FRONT MOVES FURTHER SE. A FEW STRAGGLING
SHOWERS COULD BE LINGERING NEAR THE VA BORDER ON TUESDAY MORNING AS
THE FRONT LEAVES. HIGH PRESSURE BUILDING IN FROM THE NW BEHIND THE
FRONT WILL BRING IN A DRIER AIR MASS...WITH SKIES BECOMING MOSTLY
CLEAR FROM NW TO SE LATE TONIGHT AND TUESDAY AND PERSISTING THROUGH
TUESDAY NIGHT.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 338 PM EDT MON SEP 2 2013
THE UPPER LEVEL PATTERN WILL START OFF AMPLIFIED WITH A LARGE RIDGE
CENTERED ACROSS THE ROCKIES...AN UPPER LOW CENTERED OFF THE PACIFIC
NORTHWEST COAST...AND DEEP TROUGHING EXTENDED FROM EASTERN CANADA
DOWN THROUGH NEW ENGLAND. THE MODELS ARE IN GOOD AGREEMENT...WITH A
GRADUAL DAMPENING TO TAKE PLACE IN GENERAL ACROSS THE WESTERN HALF
OF THE CONUS AS THE PACIFIC NORTHWEST UPPER LOW ADVANCES EAST ON THE
NORTHERN PERIPHERY OF THE RIDGE...WEAKENING BOTH FEATURES IN THE
PROCESS. THE TROUGHING TO THE EAST WILL BE SLOWER TO PULL OUT UNTIL
THE ROCKIES RIDGE SLIDES EAST INTO THE MISSISSIPPI VALLEY BY THE END
OF THE WEEK AND INTO EARLY NEXT WEEK.
ALL OF THIS WILL RESULT IN AN EXTENDED PERIOD OF GENERALLY DRY
WEATHER ACROSS EASTERN KENTUCKY...WITH SURFACE HIGH PRESSURE
REMAINING PARKED ACROSS THE AREA THROUGH FRIDAY...BEFORE IT BECOMES
MORE CONGEALED OFF OF THE THE EASTERN SEABOARD FOR THE WEEKEND AND
EARLY NEXT WEEK. ENOUGH MOISTURE MAY THEN RETURN TO JUSTIFY HANGING
ONTO SOME SLIGHT CHANCE POPS ALONG THE SOUTHEAST TERRAIN SATURDAY
THROUGH MONDAY.
FOR TEMPERATURES...LOWS WILL START OUT IN THE 50S THROUGH THE END OF
THE WORK WEEK...WITH HIGHS MAINLY IN THE LOW TO MID 80S. WARMER AND
MORE HUMID AIR WILL THEN GRADUALLY INCREASE ACROSS THE
AREA...ALTHOUGH PEAK DEW POINTS IN THE AFTERNOON LOOK TO HOLD IN THE
LOW TO MID 60S...SO NOT AS BALMY AS WHAT WE HAVE BEEN ACCUSTOMED TO
OVER THE PAST SEVERAL DAYS.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 605 PM EDT MON SEP 2 2013
LOCALIZED MVFR POSSIBLE WITH SHOWERS AND THUNDERSTORMS MOVING ACROSS
THE AREA AHEAD OF AND ALONG WITH THE FRONT. SOME TEMPO IFR IS ALSO
POSSIBLE WITH THE HEAVIEST OF THE STORMS. SHOWERS WILL DIE OUT
OVERNIGHT AFTER A COLD FRONT PASSES. THE GREATEST UNCERTAINTY IS WITH
THE FOG DEVELOPMENT TONIGHT. THERE IS SOME DRY AIR BEHIND THE
FRONT...HOWEVER THE ATMOSPHERE MAY BE ABLE TO DECOUPLE BEFORE THE DRY
AIR MIXES DOWN TO THE SURFACE. ANOTHER VARIABLE IS HOW MUCH RAIN IS
GOING TO FALL AS THE FRONT PASSES. THE MORE RAIN...THE GREATER THE
CHANCE FOR SEEING SOME VFR. WILL BE STAYING WITH MVFR WITH THE
PASSING SHOWERS AND NEAR DAWN WITH THE MIST. AFTER 13Z...IT SHOULD BE
VFR FOR QUITE A WHILE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JMW
SHORT TERM...HAL
LONG TERM...GEOGERIAN
AVIATION...JJ
AREA FORECAST DISCUSSION
NWS GRAY ME
1235 PM EDT TUE SEP 3 2013
.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA FROM WEST TO EAST TODAY...
PROVIDING THE FOCUS FOR THUNDERSTORMS THIS AFTERNOON. THE FRONT
WILL SWEEP OUT ALL THE WET AND HUMID WEATHER BY TONIGHT. A SECOND
COLD FRONT COMES THROUGH WEDNESDAY NIGHT...PROVIDING A BRIEF SHOT
OF MUCH COOLER AIR FOR THE END OF THE WEEK. HIGH PRESSURE WILL
BUILD ACROSS THE REGION LATE THURSDAY THROUGH SATURDAY. ANOTHER
COLD FRONT WILL CROSS NEW ENGLAND SATURDAY NIGHT AND SUNDAY
FOLLOWED BY HIGH PRESSURE AND DRIER AIR FOR MONDAY.
&&
.NEAR TERM /TODAY/...
1230PM UPDATE...
COLD FRONT HAS MADE ITS WAY TO PORTSMOUTH BUT NOT QUITE TO
PORTLAND YET. CONVECTION IS LOOKING A LITTLE BIT LESS LIKELY AS A
STRONG CUMULUS FIELD HAS YET TO FORM. HOWEVER... SOME VERTICAL
ENHANCEMENT TO CLOUD TOPS IN NORTHWEST MAINE OVER OXFORD COUNTY
INDICATE THAT SHOWERS ARE LIKELY TO FORM THERE SOON. STILL EXPECT
THE POTENTIAL FOR THUNDERSTORMS TO FORM ALL ALONG THE BOUNDARY
WITH STRONG TO OCCASIONALLY SEVERE THUNDERSTORMS POSSIBLE. HAVE
UPDATED POPS TO REFLECT CURRENT THINKING REGARDING TIMING AND
AREAL COVERAGE OF CONVECTION.
10AM UPDATE...
HAVE UPDATED THE FORECAST TO ADJUST POP AND SKY FORECAST. LOW
CLOUDS OVER MAINE ARE ERODING AND SHIFTING TO THE EAST... ALLOWING
FOR A CLEAR SLOT TO FORM OVER MUCH OF NEW HAMPSHIRE AND NOW INTO
WESTERN MAINE. EXPECT THIS TREND TO CONTINUE WITH MUCH OF THE AREA
BREAKING OUT OF THE CLOUDS OVER THE NEXT FEW HOURS. COLD FRONT IS
PUSHING INTO WESTERN NEW HAMPSHIRE AT THIS TIME... AND WILL BE
LOCATED NEAR THE MAINE BORDER BY EARLY AFTERNOON. THIS SHOULD
PROVIDE THE FOCUS FOR THUNDERSTORMS TODAY. STILL UNCERTAIN HOW
WIDESPREAD STORMS WILL BE... BUT TIMING SHOULD BE AROUND OR
SHORTLY AFTER NOON... SHIFTING EAST THROUGH THE AFTERNOON.
FORECAST SOUNDINGS SHOW CAPE VALUES OF 1000 TO 1500 ACROSS WESTERN
MAINE AHEAD OF THE FRONT THIS AFTERNOON. THIS WILL COMBINE WITH
30 TO 40 KTS OF SHEAR TO CREATE THE POSSIBILITY OF STRONG OR
SEVERE THUNDERSTORMS INCLUDING SUPERCELLS. THE GREATEST THREAT
WILL BE FROM DAMAGING WINDS BUT LARGE HAIL IS ALSO POSSIBLE.
7AM UPDATE...
HAVE UPDATED THE GRIDS TO ADD AREAS OF DRIZZLE ACROSS THE REGION
PER LATEST SURFACE OBSERVATIONS. THIS DRIZZLE AND AREAS OF FOG
WILL SLOWLY BE LIFTING AND MIXING OUT THIS MORNING. STILL EXPECT
SHOWERS AND THUNDERSTORMS TO ERUPT DURING THE MIDDAY PERIOD. A FEW
SHOWERS ASSOCIATED WITH THE FRONT ALREADY IN EASTERN NEW YORK
STATE EARLY THIS MORNING.
REST OF THE FORECAST PACKAGE WILL REMAIN RELATIVELY UNCHANGED.
ORIGINAL DISCUSSION...
LOW CLOUDS AND FOG WILL SLOWLY MIX OUT ACROSS THE REGION THIS
MORNING. EASTERN AREAS...ESPECIALLY NEAR THE COASTLINE...WILL BE
SLOW TO IMPROVE. IN THE MEANTIME...THE LATEST HRRR MODEL RUN
CONTINUES TO SHOW SHOWER AND THUNDERSTORM ACTIVITY DEVELOPING OVER
EASTERN NEW HAMPSHIRE AROUND 17Z. THIS PRECIPITATION IS IN
ASSOCIATION WITH AN APPROACHING COLD FRONT. WITH APPROACHING UPPER
LEVEL TROUGH...WIND MAX AND MODEST INSTABILITY...EXPECT A FEW
STORMS TO CONTAIN DAMAGING WINDS OR HAIL.
HAVE THEREFORE ADDED ENHANCED WORDING TO THE FORECAST PACKAGE.
THUNDERSTORMS WILL CONTINUE UNTIL THIS EVENING...HOWEVER SOME OF
THE CONVECTIVE ACTIVITY WILL HAVE A CHALLENGING TIME MAKING IT
THROUGH ANY REMAINING LOW CLOUDS AND FOG ALONG THE MIDCOAST.
LOOK FOR 70S IN MOST AREAS...HOWEVER SOUTHERN NEW HAMPSHIRE MAY
TIP THE 80 DEGREE MARK.
&&
.SHORT TERM /TONIGHT AND WEDNESDAY/...
THE PRECIPITATION EXITS THE REGION THIS EVENING AS THE COLD FRONT
MOVES EAST. DRIER AIR WILL FILTER INTO THE FORECAST AREA FROM THE
WEST. HOWEVER...PLENTY OF LOW LEVEL MOISTURE FROM RECENT HEAVY
RAINS WILL ALLOW FOR MORE PATCHY FOG TO DEVELOP.
BY WEDNESDAY...THE UPPER LEVEL TROUGH WILL PUSH EAST OF THE
REGION...AND WE WILL BE IN BETWEEN SYSTEMS. A STRONG COLD FRONT
WILL APPROACH FROM THE WEST...BUT MUCH OF THE CLOUDINESS AND ANY
PRECIPITATION WILL HOLD OFF UNTIL AFTER DARK.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
MODELS ARE IN GOOD AGREEMENT ON THE LONGWAVE PATTERN THROUGH THE
FORECAST PERIOD. THE UPPER TROUGH LINGERS ACROSS THE REGION
THROUGH THE UPCOMING WEEKEND BEFORE THE UPSTREAM RIDGE ACROSS THE
INTER-MOUNTAIN WEST FINALLY WEAKENS...AND THE FLOW BECOMES MORE
ZONAL ACROSS THE FORECAST AREA. WE BEGIN THE PERIOD WITH A
RELATIVELY DEEP TROUGH ACROSS THE AREA...AND A SURFACE COLD FRONT
MAKING ITS WAY SOUTHWARD ACROSS THE REGION WEDNESDAY NIGHT AND
EARLY THURSDAY. THIS FRONT WILL USHER BELOW NORMAL TEMPERATURES
INTO THE AREA FOR THURSDAY AND FRIDAY AS HIGH PRESSURE BUILDS
SOUTH AND EAST FROM THE GREAT LAKES. A RETURN FLOW AROUND THE
HIGH WILL INTRODUCE MILDER AIR INTO THE REGION SATURDAY. ANOTHER
SHORTWAVE WILL DRIVE A STRONG COLD FRONT ACROSS THE AREA SATURDAY
NIGHT AND SUNDAY WITH HIGH PRESSURE AND DRY AIR TO FOLLOW FOR
MONDAY.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
SHORT TERM...AREAS OF LOW CLOUDINESS AND FOG WILL SLOWLY MIX OUT
OVER THE REGION THIS MORNING...WITH THE LAST AREA TO CLEAR BEING EASTERN
AREAS THIS MORNING...ESPECIALLY NEAR THE COASTLINE. HOWEVER...THE
IMPROVEMENT WILL BE BRIEF WITH SCATTERED SHOWERS AND THUNDERSTORMS
DEVELOPING AFTER NOON TODAY FROM WEST TO EAST. THE LOCALLY STRONG
SHOWERS AND STORMS WILL END THIS EVENING...FOLLOWED BY MORE IFR
AND ISOLATED LIFR CONDITIONS IN DEVELOPING FOG. VFR CONDITIONS ON
WEDNESDAY.
LONG TERM...
WEDNESDAY NIGHT - THURSDAY...SCATTERED MVFR IN SHOWERS AND THUNDERSTORMS.
&&
.MARINE...
SHORT TERM...A COLD FRONT WILL CROSS THE WATERS TODAY WITH
THUNDERSTORMS POSSIBLE. WINDS AND SEAS WILL BE FAIRLY QUIET
OUTSIDE OF THUNDERSTORMS.
LONG TERM...
FRIDAY NIGHT - SATURDAY...WINDS AND SEAS MAY APPROACH SMALL CRAFT
ADVISORY CRITERIA.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
NEAR TERM UPDATE... KIMBLE
AREA FORECAST DISCUSSION
NWS GRAY ME
1005 AM EDT TUE SEP 3 2013
.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA FROM WEST TO EAST TODAY...
PROVIDING THE FOCUS FOR THUNDERSTORMS THIS AFTERNOON. THE FRONT
WILL SWEEP OUT ALL THE WET AND HUMID WEATHER BY TONIGHT. A SECOND
COLD FRONT COMES THROUGH WEDNESDAY NIGHT...PROVIDING A BRIEF SHOT
OF MUCH COOLER AIR FOR THE END OF THE WEEK. HIGH PRESSURE WILL
BUILD ACROSS THE REGION LATE THURSDAY THROUGH SATURDAY. ANOTHER
COLD FRONT WILL CROSS NEW ENGLAND SATURDAY NIGHT AND SUNDAY
FOLLOWED BY HIGH PRESSURE AND DRIER AIR FOR MONDAY.
&&
.NEAR TERM /TODAY/...
10AM UPDATE...
HAVE UPDATED THE FORECAST TO ADJUST POP AND SKY FORECAST. LOW
CLOUDS OVER MAINE ARE ERODING AND SHIFTING TO THE EAST... ALLOWING
FOR A CLEAR SLOT TO FORM OVER MUCH OF NEW HAMPSHIRE AND NOW INTO
WESTERN MAINE. EXPECT THIS TREND TO CONTINUE WITH MUCH OF THE AREA
BREAKING OUT OF THE CLOUDS OVER THE NEXT FEW HOURS. COLD FRONT IS
PUSHING INTO WESTERN NEW HAMPSHIRE AT THIS TIME... AND WILL BE
LOCATED NEAR THE MAINE BORDER BY EARLY AFTERNOON. THIS SHOULD
PROVIDE THE FOCUS FOR THUNDERSTORMS TODAY. STILL UNCERTAIN HOW
WIDESPREAD STORMS WILL BE... BUT TIMING SHOULD BE AROUND OR
SHORTLY AFTER NOON... SHIFTING EAST THROUGH THE AFTERNOON.
FORECAST SOUNDINGS SHOW CAPE VALUES OF 1000 TO 1500 ACROSS WESTERN
MAINE AHEAD OF THE FRONT THIS AFTERNOON. THIS WILL COMBINE WITH
30 TO 40 KTS OF SHEAR TO CREATE THE POSSIBILITY OF STRONG OR
SEVERE THUNDERSTORMS INCLUDING SUPERCELLS. THE GREATEST THREAT
WILL BE FROM DAMAGING WINDS BUT LARGE HAIL IS ALSO POSSIBLE.
7AM UPDATE...
HAVE UPDATED THE GRIDS TO ADD AREAS OF DRIZZLE ACROSS THE REGION
PER LATEST SURFACE OBSERVATIONS. THIS DRIZZLE AND AREAS OF FOG
WILL SLOWLY BE LIFTING AND MIXING OUT THIS MORNING. STILL EXPECT
SHOWERS AND THUNDERSTORMS TO ERUPT DURING THE MIDDAY PERIOD. A FEW
SHOWERS ASSOCIATED WITH THE FRONT ALREADY IN EASTERN NEW YORK
STATE EARLY THIS MORNING.
REST OF THE FORECAST PACKAGE WILL REMAIN RELATIVELY UNCHANGED.
ORIGINAL DISCUSSION...
LOW CLOUDS AND FOG WILL SLOWLY MIX OUT ACROSS THE REGION THIS
MORNING. EASTERN AREAS...ESPECIALLY NEAR THE COASTLINE...WILL BE
SLOW TO IMPROVE. IN THE MEANTIME...THE LATEST HRRR MODEL RUN
CONTINUES TO SHOW SHOWER AND THUNDERSTORM ACTIVITY DEVELOPING OVER
EASTERN NEW HAMPSHIRE AROUND 17Z. THIS PRECIPITATION IS IN
ASSOCIATION WITH AN APPROACHING COLD FRONT. WITH APPROACHING UPPER
LEVEL TROUGH...WIND MAX AND MODEST INSTABILITY...EXPECT A FEW
STORMS TO CONTAIN DAMAGING WINDS OR HAIL.
HAVE THEREFORE ADDED ENHANCED WORDING TO THE FORECAST PACKAGE.
THUNDERSTORMS WILL CONTINUE UNTIL THIS EVENING...HOWEVER SOME OF
THE CONVECTIVE ACTIVITY WILL HAVE A CHALLENGING TIME MAKING IT
THROUGH ANY REMAINING LOW CLOUDS AND FOG ALONG THE MIDCOAST.
LOOK FOR 70S IN MOST AREAS...HOWEVER SOUTHERN NEW HAMPSHIRE MAY
TIP THE 80 DEGREE MARK.
&&
.SHORT TERM /TONIGHT AND WEDNESDAY/...
THE PRECIPITATION EXITS THE REGION THIS EVENING AS THE COLD FRONT
MOVES EAST. DRIER AIR WILL FILTER INTO THE FORECAST AREA FROM THE
WEST. HOWEVER...PLENTY OF LOW LEVEL MOISTURE FROM RECENT HEAVY
RAINS WILL ALLOW FOR MORE PATCHY FOG TO DEVELOP.
BY WEDNESDAY...THE UPPER LEVEL TROUGH WILL PUSH EAST OF THE
REGION...AND WE WILL BE IN BETWEEN SYSTEMS. A STRONG COLD FRONT
WILL APPROACH FROM THE WEST...BUT MUCH OF THE CLOUDINESS AND ANY
PRECIPITATION WILL HOLD OFF UNTIL AFTER DARK.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
MODELS ARE IN GOOD AGREEMENT ON THE LONGWAVE PATTERN THROUGH THE
FORECAST PERIOD. THE UPPER TROUGH LINGERS ACROSS THE REGION
THROUGH THE UPCOMING WEEKEND BEFORE THE UPSTREAM RIDGE ACROSS THE
INTER-MOUNTAIN WEST FINALLY WEAKENS...AND THE FLOW BECOMES MORE
ZONAL ACROSS THE FORECAST AREA. WE BEGIN THE PERIOD WITH A
RELATIVELY DEEP TROUGH ACROSS THE AREA...AND A SURFACE COLD FRONT
MAKING ITS WAY SOUTHWARD ACROSS THE REGION WEDNESDAY NIGHT AND
EARLY THURSDAY. THIS FRONT WILL USHER BELOW NORMAL TEMPERATURES
INTO THE AREA FOR THURSDAY AND FRIDAY AS HIGH PRESSURE BUILDS
SOUTH AND EAST FROM THE GREAT LAKES. A RETURN FLOW AROUND THE
HIGH WILL INTRODUCE MILDER AIR INTO THE REGION SATURDAY. ANOTHER
SHORTWAVE WILL DRIVE A STRONG COLD FRONT ACROSS THE AREA SATURDAY
NIGHT AND SUNDAY WITH HIGH PRESSURE AND DRY AIR TO FOLLOW FOR
MONDAY.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
SHORT TERM...AREAS OF LOW CLOUDINESS AND FOG WILL SLOWLY MIX OUT
OVER THE REGION THIS MORNING...WITH THE LAST AREA TO CLEAR BEING EASTERN
AREAS THIS MORNING...ESPECIALLY NEAR THE COASTLINE. HOWEVER...THE
IMPROVEMENT WILL BE BRIEF WITH SCATTERED SHOWERS AND THUNDERSTORMS
DEVELOPING AFTER NOON TODAY FROM WEST TO EAST. THE LOCALLY STRONG
SHOWERS AND STORMS WILL END THIS EVENING...FOLLOWED BY MORE IFR
AND ISOLATED LIFR CONDITIONS IN DEVELOPING FOG. VFR CONDITIONS ON
WEDNESDAY.
LONG TERM...
WEDNESDAY NIGHT - THURSDAY...SCATTERED MVFR IN SHOWERS AND THUNDERSTORMS.
&&
.MARINE...
SHORT TERM...A COLD FRONT WILL CROSS THE WATERS TODAY WITH
THUNDERSTORMS POSSIBLE. WINDS AND SEAS WILL BE FAIRLY QUIET
OUTSIDE OF THUNDERSTORMS.
LONG TERM...
FRIDAY NIGHT - SATURDAY...WINDS AND SEAS MAY APPROACH SMALL CRAFT
ADVISORY CRITERIA.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
NEAR TERM UPDATE... KIMBLE
AREA FORECAST DISCUSSION
NWS GRAY ME
657 AM EDT TUE SEP 3 2013
.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA FROM WEST TO EAST TODAY...
PROVIDING THE FOCUS FOR THUNDERSTORMS AGAIN THIS AFTERNOON. THE
FRONT WILL SWEEP OUT ALL THE WET AND HUMID WEATHER BY TONIGHT. A
SECOND COLD FRONT COMES THROUGH WEDNESDAY NIGHT...PROVIDING A
BRIEF SHOT OF MUCH COOLER AIR FOR THE END OF THE WEEK. HIGH
PRESSURE WILL BUILD ACROSS THE REGION LATE THURSDAY THROUGH
SATURDAY. ANOTHER COLD FRONT WILL CROSS NEW ENGLAND SATURDAY NIGHT
AND SUNDAY FOLLOWED BY HIGH PRESSURE AND DRIER AIR FOR MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE...
HAVE UPDATED THE GRIDS TO ADD AREAS OF DRIZZLE ACROSS THE REGION
PER LATEST SURFACE OBSERVATIONS. THIS DRIZZLE AND AREAS OF FOG
WILL SLOWLY BE LIFTING AND MIXING OUT THIS MORNING. STILL EXPECT
SHOWERS AND THUNDERSTORMS TO ERUPT DURING THE MIDDAY PERIOD. A FEW
SHOWERS ASSOCIATED WITH THE FRONT ALREADY IN EASTERN NEW YORK
STATE EARLY THIS MORNING.
REST OF THE FORECAST PACKAGE WILL REMAIN RELATIVELY UNCHANGED.
PREV DISC...
LOW CLOUDS AND FOG WILL SLOWLY MIX OUT ACROSS THE REGION THIS
MORNING. EASTERN AREAS...ESPECIALLY NEAR THE COASTLINE...WILL BE
SLOW TO IMPROVE. IN THE MEANTIME...THE LATEST HRRR MODEL RUN
CONTINUES TO SHOW SHOWER AND THUNDERSTORM ACTIVITY DEVELOPING OVER
EASTERN NEW HAMPSHIRE AROUND 17Z. THIS PRECIPITATION IS IN
ASSOCIATION WITH AN APPROACHING COLD FRONT. WITH APPROACHING UPPER
LEVEL TROUGH...WIND MAX AND MODEST INSTABILITY...EXPECT A FEW
STORMS TO CONTAIN DAMAGING WINDS OR HAIL.
HAVE THEREFORE ADDED ENHANCED WORDING TO THE FORECAST PACKAGE.
THUNDERSTORMS WILL CONTINUE UNTIL THIS EVENING...HOWEVER SOME OF
THE CONVECTIVE ACTIVITY WILL HAVE A CHALLENGING TIME MAKING IT
THROUGH ANY REMAINING LOW CLOUDS AND FOG ALONG THE MIDCOAST.
LOOK FOR 70S IN MOST AREAS...HOWEVER SOUTHERN NEW HAMPSHIRE MAY
TIP THE 80 DEGREE MARK.
&&
.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
THE PRECIPITATION EXITS THE REGION THIS EVENING AS THE COLD FRONT
MOVES EAST. DRIER AIR WILL FILTER INTO THE FORECAST AREA FROM THE
WEST. HOWEVER...PLENTY OF LOW LEVEL MOISTURE FROM RECENT HEAVY
RAINS WILL ALLOW FOR MORE PATCHY FOG TO DEVELOP.
BY WEDNESDAY...THE UPPER LEVEL TROUGH WILL PUSH EAST OF THE
REGION...AND WE WILL BE IN BETWEEN SYSTEMS. A STRONG COLD FRONT
WILL APPROACH FROM THE WEST...BUT MUCH OF THE CLOUDINESS AND ANY
PRECIPITATION WILL HOLD OFF UNTIL AFTER DARK.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
MODELS ARE IN GOOD AGREEMENT ON THE LONGWAVE PATTERN THROUGH THE
FORECAST PERIOD. THE UPPER TROUGH LINGERS ACROSS THE REGION
THROUGH THE UPCOMING WEEKEND BEFORE THE UPSTREAM RIDGE ACROSS THE
INTERMOUNTAIN WEST FINALLY WEAKENS...AND THE FLOW BECOMES MORE
ZONAL ACROSS THE FORECAST AREA. WE BEGIN THE PERIOD WITH A
RELATIVELY DEEP TROUGH ACROSS THE AREA...AND A SURFACE COLD FRONT
MAKING ITS WAY SOUTHWARD ACROSS THE REGION WEDNESDAY NIGHT AND
EARLY THURSDAY. THIS FRONT WILL USHER BELOW NORMAL TEMPERATURES
INTO THE AREA FOR THURSDAY AND FRIDAY AS HIGH PRESSURE BUILDS
SOUTH AND EAST FROM THE GREAT LAKES. A RETURN FLOW AROUND THE
HIGH WILL INTRODUCE MILDER AIR INTO THE REGION SATURDAY. ANOTHER
SHORTWAVE WILL DRIVE A STRONG COLD FRONT ACROSS THE AREA SATURDAY
NIGHT AND SUNDAY WITH HIGH PRESSURE AND DRY AIR TO FOLLOW FOR
MONDAY.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
SHORT TERM...AREAS OF LOW CLOUDINESS AND FOG WILL SLOWLY MIX OUT
OVER THE REGION THIS MORNING...WITH THE LAST AREA TO CLEAR BEING EASTERN
AREAS THIS MORNING...ESPECIALLY NEAR THE COASTLINE. HOWEVER...THE
IMPROVEMENT WILL BE BRIEF WITH SCATTERED SHOWERS AND THUNDERSTORMS
DEVELOPING AFT NOONTIME TODAY FROM WEST TO EAST. THE LOCALLY
STRONG SHOWERS AND STORMS WILL END THIS EVENING...FOLLOWED BY MORE
IFR AND ISOLATED LIFR CONDITIONS IN DEVELOPING FOG. VFR CONDITIONS
ON WEDNESDAY.
LONG TERM...
WED NIGHT - THU...SCT MVFR IN SHOWERS AND TSTMS.
&&
.MARINE...
SHORT TERM...A COLD FRONT WILL CROSS THE WATERS ON TODAY WITH
THUNDERSTORMS POSSIBLE AGAIN. WINDS AND SEAS WILL BE FAIRLY QUIET
OUTSIDE OF THUNDERSTORMS.
LONG TERM...
FRI NIGHT - SAT...WINDS AND SEAS MAY APPROACH SMALL CRAFT.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAY ME
307 AM EDT TUE SEP 3 2013
.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA FROM WEST TO EAST TODAY...
PROVIDING THE FOCUS FOR THUNDERSTORMS AGAIN THIS AFTERNOON. THE
FRONT WILL SWEEP OUT ALL THE WET AND HUMID WEATHER BY TONIGHT. A
SECOND COLD FRONT COMES THROUGH WEDNESDAY NIGHT...PROVIDING A
BRIEF SHOT OF MUCH COOLER AIR FOR THE END OF THE WEEK. HIGH
PRESSURE WILL BUILD ACROSS THE REGION LATE THURSDAY THROUGH
SATURDAY. ANOTHER COLD FRONT WILL CROSS NEW ENGLAND SATURDAY NIGHT
AND SUNDAY FOLLOWED BY HIGH PRESSURE AND DRIER AIR FOR MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LOW CLOUDS AND FOG WILL SLOWLY MIX OUT ACROSS THE REGION THIS
MORNING. EASTERN AREAS...ESPECIALLY NEAR THE COASTLINE...WILL BE
SLOW TO IMPROVE. IN THE MEANTIME...THE LATEST HRRR MODEL RUN
CONTINUES TO SHOW SHOWER AND THUNDERSTORM ACTIVITY DEVELOPING OVER
EASTERN NEW HAMPSHIRE AROUND 17Z. THIS PRECIPITATION IS IN
ASSOCIATION WITH AN APPROACHING COLD FRONT. WITH APPROACHING UPPER
LEVEL TROUGH...WIND MAX AND MODEST INSTABILITY...EXPECT A FEW
STORMS TO CONTAIN DAMAGING WINDS OR HAIL.
HAVE THEREFORE ADDED ENHANCED WORDING TO THE FORECAST PACKAGE.
THUNDERSTORMS WILL CONTINUE UNTIL THIS EVENING...HOWEVER SOME OF
THE CONVECTIVE ACTIVITY WILL HAVE A CHALLENGING TIME MAKING IT
THROUGH ANY REMAINING LOW CLOUDS AND FOG ALONG THE MIDCOAST.
LOOK FOR 70S IN MOST AREAS...HOWEVER SOUTHERN NEW HAMPSHIRE MAY
TIP THE 80 DEGREE MARK.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
THE PRECIPITATION EXITS THE REGION THIS EVENING AS THE COLD FRONT
MOVES EAST. DRIER AIR WILL FILTER INTO THE FORECAST AREA FROM THE
WEST. HOWEVER...PLENTY OF LOW LEVEL MOISTURE FROM RECENT HEAVY
RAINS WILL ALLOW FOR MORE PATCHY FOG TO DEVELOP.
BY WEDNESDAY...THE UPPER LEVEL TROUGH WILL PUSH EAST OF THE
REGION...AND WE WILL BE IN BETWEEN SYSTEMS. A STRONG COLD FRONT
WILL APPROACH FROM THE WEST...BUT MUCH OF THE CLOUDINESS AND ANY
PRECIPITATION WILL HOLD OFF UNTIL AFTER DARK.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
MODELS ARE IN GOOD AGREEMENT ON THE LONGWAVE PATTERN THROUGH THE
FORECAST PERIOD. THE UPPER TROUGH LINGERS ACROSS THE REGION
THROUGH THE UPCOMING WEEKEND BEFORE THE UPSTREAM RIDGE ACROSS THE
INTERMOUNTAIN WEST FINALLY WEAKENS...AND THE FLOW BECOMES MORE
ZONAL ACROSS THE FORECAST AREA. WE BEGIN THE PERIOD WITH A
RELATIVELY DEEP TROUGH ACROSS THE AREA...AND A SURFACE COLD FRONT
MAKING ITS WAY SOUTHWARD ACROSS THE REGION WEDNESDAY NIGHT AND
EARLY THURSDAY. THIS FRONT WILL USHER BELOW NORMAL TEMPERATURES
INTO THE AREA FOR THURSDAY AND FRIDAY AS HIGH PRESSURE BUILDS
SOUTH AND EAST FROM THE GREAT LAKES. A RETURN FLOW AROUND THE
HIGH WILL INTRODUCE MILDER AIR INTO THE REGION SATURDAY. ANOTHER
SHORTWAVE WILL DRIVE A STRONG COLD FRONT ACROSS THE AREA SATURDAY
NIGHT AND SUNDAY WITH HIGH PRESSURE AND DRY AIR TO FOLLOW FOR
MONDAY.
&&
.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
SHORT TERM...AREAS OF LOW CLOUDINESS AND FOG WILL SLOWLY MIX OUT
OVER THE REGION THIS MORNING...WITH THE LAST AREA TO CLEAR BEING EASTERN
AREAS THIS MORNING...ESPECIALLY NEAR THE COASTLINE. HOWEVER...THE
IMPROVEMENT WILL BE BRIEF WITH SCATTERED SHOWERS AND THUNDERSTORMS
DEVELOPING AFT NOONTIME TODAY FROM WEST TO EAST. THE LOCALLY
STRONG SHOWERS AND STORMS WILL END THIS EVENING...FOLLOWED BY MORE
IFR AND ISOLATED LIFR CONDITIONS IN DEVELOPING FOG. VFR CONDITIONS
ON WEDNESDAY.
LONG TERM...
WED NIGHT - THU...SCT MVFR IN SHOWERS AND TSTMS.
&&
.MARINE...
SHORT TERM...A COLD FRONT WILL CROSS THE WATERS ON TODAY WITH
THUNDERSTORMS POSSIBLE AGAIN. WINDS AND SEAS WILL BE FAIRLY QUIET
OUTSIDE OF THUNDERSTORMS.
LONG TERM...
FRI NIGHT - SAT...WINDS AND SEAS MAY APPROACH SMALL CRAFT.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
735 PM EDT WED SEP 4 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 407 PM EDT WED SEP 4 2013
WV IMAGERY AND RUC ANALYSIS INDICATED NW MID/UPPER LEVEL THROUGH THE
UPPER GREAT LAKES BETWEEN A LOW OVER NRN QUEBEC AND A RIDGE FROM
COLORADO THROUGH THE WRN PLAINS. WITH CONFLUENT FLOW AND 700-300 MB
QVECTOR DIV BUILDING INTO THE AREA...EXPECT MAINLY CLEAR SKIES TO
PREVAIL WITH ONLY SOME BANDS OF CIRRUS THROUGH THE ERN CWA...PER VIS
IMAGERY. AT THE SFC...HIGH PRES FROM SRN MANITOBA INTO NW ONTARIO
WAS BUILDING INTO THE NRN GREAT LAKES WITH INFLUX OF DRY AIR ON NRN
ACYC FLOW. LOWER DEWPOINTS UPSTREAM FROM LAKE SUPERIOR (READINGS IN
THE UPPER 30S) WERE FILTERING TOWARD UPPER MI.
TONIGHT...EVEN WITH PWAT VALUES AROUND 0.50 INCH CLIMBING TO NEAR
0.75 INCH...WITH HIGH PRES BUILDING INTO UPPER MI...MOSTLY CLEAR
SKIES AND LIGHT WINDS ALLOW TEMPS TO DROP OFF TOWARD THE LOWER END
OF GUIDANCE. READINGS INTO THE UPPER 30S INLAND WEST AND LOW TO MID
40S OVER THE EAST AND ALONG THE GREAT LAKES ARE EXPECTED. PATCHY
FROST MAY BE POSSIBLE IN THE TYPICAL COLD SPOTS FROM REPUBLIC AND
CHAMPION TO AMASA...IRON RIVER AND WATERSMEET.
THURSDAY...UNDER ABUNDANT SUNSHINE WITH 850 MB TEMPS IN THE 6C TO
10C RANGE...TEMPS WILL REBOUND CLOSER TO SEASONAL AVERAGES WITH HIGHS
RANGING FROM THE UPPER 60S EAST TO THE LOWER 70S WEST.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 407 PM EDT WED SEP 4 2013
HIGH PRESSURE WILL KEEP WEATHER QUIET THURSDAY NIGHT THROUGH EARLY
FRIDAY AFTERNOON. AS THE HIGH CENTERS OVER THE EASTERN
SEABOARD...UPPER MICHIGAN IS POSITIONED ON THE NORTHWESTERN
PERIPHERY OF THE RIDGE...MAKING US VULNERABLE FOR WEAK WAVES TO
SLIDE THROUGH. THE FIRST OF THESE SLIDES OUT AHEAD OF THE MAIN
TROUGH ON FRIDAY AFTERNOON. MODELS ARE MOSTLY IN AGREEMENT...WITH
THE EXCEPTION OF THE GFS WHICH BRINGS THE MAIN TROUGH IN MUCH
QUICKER...SO STRAYED FROM THAT SOLUTION. USED PRIMARILY THE
GEM/ECMWF FOR THIS LONG TERM FORECAST.
WEAK MOISTURE ADVECTION/CONVERGENCE SHOWS UP FOR THE MID LEVELS AND
FOCUSES ACROSS THE WEST AND NORTHERN PORTIONS OF THE CWA EARLIER IN
THE DAY...PRIMARILY OVER THE KEWEENAW AND LAKE SUPERIOR. THROUGHOUT
THE DAY THIS REGION MOVES EAST-SOUTHEASTWARD TOWARDS QUEBEC...SO
KEPT PCP CHANCES FAR EAST INTO FRIDAY EVENING. OVERALL...850-500MB
QVECTOR CONVERGENCE IS PALTRY BUT WARRANTS SOME SLIGHT CHANCE/CHANCE
POPS. LOW LEVELS ARE FAIRLY DRY THOUGH...AND INSTABILITY IS MINIMAL.
WILL KEEP THE POPS PRIMARILY OVER THE LAKE AND FAR EAST FOR NOW.
FRIDAY NIGHT THROUGH SATURDAY THE STRONGER TROUGH MOVES THROUGH THE
GREAT LAKES AS LOW PRESSURE OVER JAMES BAY ON FRIDAY MOVES INTO
QUEBEC. MOISTURE IS DEEPER AND INSTABILITY IS GREATER THIS GO
AROUND...WHICH WILL SUPPORT SHOWERS AND TSTORMS ACROSS THE CWA. THE
WESTERN CWA IS LIKELY TO SEE SHOWERS/A FEW TSTORMS STARTING LATER
FRIDAY NIGHT AND CONTINUING THROUGH MAINLY SATURDAY MORNING. WITH
GREATER INSTABILITY BUILDING TOWARDS SATURDAY AFTERNOON ALONG THE WI
BORDER AND CENTRAL U.P. LINGERED CHANCE POPS THERE THROUGH THE
AFTERNOON.
THE BEST MOISTURE IS CENTRAL AND EAST HOWEVER...AND SFC BASED CAPE
IS AROUND 1000-500 J/KG FOR THE AFTERNOON. WITH THE FRONT PASSING
THROUGH THE CENTRAL CWA AROUND 18Z AND NORTHWEST FLOW ALOFT...EXPECT
WE WILL SEE SOME ACTIVITY. 0-6KM BULK SHEAR IS AROUND 20-30
KNOTS...SO DO NOT EXPECT ANYTHING TOO GET TOO ORGANIZED. ANY SEVERE
THREAT AS OF RIGHT NOW LOOKS TO BE VERY ISOLATED.
ON SUNDAY HIGH PRESSURE BRINGS A BRIEF BREAK TO THE PRECIPITATION.
MONDAY AND TUESDAY A WARM FRONT LIFTS ACROSS THE MIDWEST WITH A
STRONGER LOW PRESSURE SYSTEM IN THE NORTHERN PLAINS. THIS LOW WILL
MOVE NORTHEASTWARD INTO ONTARIO...AND EVENTUALLY BRING A COLD FRONT
ACROSS UPPER MI ON WEDNESDAY. HAVE CHANCE POPS IN THE FORECAST FOR
NOW...GIVEN DIFFERENCES BETWEEN MODELS IN THE LOCATION OF THE LOW
PRESSURE SYSTEM DURING THESE TIMES.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 734 PM EDT WED SEP 4 2013
WITH HIGH PRESSURE BUILDING INTO THE REGION...EXPECT VFR CONDITIONS
AND LIGHT WINDS THROUGH THE FCST PERIOD. &&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 407 PM EDT WED SEP 4 2013
WITH HIGH PRES BUILDING INTO THE UPPER LAKES...WINDS WILL DIMINISH
TO LESS THAN 20 KTS LATER TONIGHT INTO THURSDAY. SW WINDS WILL
INCREASE ON FRIDAY IN THE TIGHTER PRESSURE GRADIENT BETWEEN THE
EXITING HIGH PRESSURE AND A COLD FRONT THAT ARRIVES THIS WEEKEND.
EXPECT WINDS ON FRIDAY TO STAY LESS THAN 25 KTS. WINDS FOR THE
REMAINDER OF THE FORECAST PERIOD WILL REMAIN LESS THAN 20 KNOTS DUE
TO WEAKER PRESSURE GRADIENT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
BEACH HAZARDS STATEMENT UNTIL 10 PM EDT THIS EVENING FOR MIZ005-
006.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...MCD
AVIATION...VOSS
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
206 AM EDT TUE SEP 3 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 317 PM EDT MON SEP 2 2013
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW CONFLUENT NW FLOW
ALF OVER THE UPR GRT LKS TO THE W OF DEPARTING VIGOROUS SHRTWV
MOVING INTO QUEBEC AND E OF SLOWLY PROGRESSIVE UPR RDG IN THE
PLAINS. WITH LINGERING LLVL MSTR SHOWN ON THE 12Z INL/ GRB/APX
RAOBS...PLENTY OF LO CLDS LINGER OVER MUCH OF THE UPR LKS IN THE
LINGERING LLVL CYC NNW FLOW BTWN HI PRES CENTERED NEAR THE RED RIVER
VALLEY AND SFC LO IN QUEBEC. STRONG DNVA/SUBSIDENCE IN THE WAKE OF
THE DEPARTING DISTURBANCE HAS CAUSED THE SUBSIDENCE INVRN AT INL AND
APX TO SHARPEN AND FALL TO NEAR H875 AT 12Z. AT YPL...THE 12Z ROAB
SHOWS THE SUBSIDENCE INVRN HAS REACHED NEAR THE SFC. IN CONCERT WITH
LLVL DRYING...THE LO CLDS HAVE DSPTD ALONG AN AXIS FM NW ONTARIO
INTO WRN/NCENTRAL LK SUP AND THE KEWEENAW. THE SUBSIDENCE/LLVL
DRYING HAS ALSO TENDED TO DIMINISH THE -DZ/SPRINKLES THAT WERE
OCCURRING EARLIER.
MAIN FCST CONCERNS IN THE SHORT TERM ARE LO CLD TRENDS AND IMPACT ON
TEMPS TNGT.
TNGT...AS HI PRES BLDS SLOWLY EWD IN THE CONFLUENT NW FLOW ALF UNDER
RISING HGTS...EXPECT LINGERING LO CLDS OVER THE W AND CENTRAL TO
DIMINISH FAIRLY QUICKLY AS THE LLVL FLOW BACKS/BECOMES MORE ACYC AND
DRIER SFC-H925 AIR OVERSPREADS THE AREA. THE LO CLDS ARE LIKELY TO
BE MORE RESILIENT E OF MQT-ESC WITH A MORE NEUTRAL FLOW AND LESS
DRYING IN THE SFC-H925 LYR EXACERBATED BY LONGER FETCH OVER LK SUP
IN PERSISTENT NNW FLOW. THE LOWEST MIN TEMPS SHOULD OCCUR OVER THE
INTERIOR W...WHERE WINDS WL BE LIGHTER AND SKIES MOCLR AS PWAT IS
FCST TO FALL UNDER 0.5 INCH TOWARD 50-60 PCT OF NORMAL. UPSTREAM
TEMPS THIS MRNG FELL AS LO AS 40...SO GOING FCST TEMPS BOTTOMING OUT
IN THE UPR 30S AT THE COLD SPOTS OVER THE INTERIOR W LOOK ON TRACK.
PERSISTENT CLDS/ONSHORE FLOW WL CAUSE TEMPS TO RUN MUCH WARMER OVER
THE E. STEADY N WIND WL MAINTAIN HIER WAVES/HI SWIM RISK OVER THE
ALGER/MQT COUNTY BEACHES...BUT TEMPS WL BE CHILLY AND UNDER 60
DEGREES.
TUE...AS HI PRES BLDS TOWARD THE OH VALLEY...THE LLVL FLOW WL BACK
TO THE W. THIS WSHFT...LLVL DRYING AND DESCENDING SUBSIDENCE INVRN
WL BREAK UP ANY LINGERING LO CLDS OVER THE E IN THE MRNG. WITH
PLENTY OF AFTN SUNSHINE AND H85 TEMPS FCST TO WARM TO BTWN 16C OVER
THE W AND 12Z OVER THE E BY 00Z WED...EXPECT A MUCH WARMER AFTN.
MIXING TO H85 ON FCST SDNGS YIELDS HI TEMPS 75-80 OVER THE W HALF
AWAY FM LK MODERATION.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 427 PM EDT MON SEP 2 2013
NW FLOW WILL REMAIN STUCK ACROSS THE UPPER GREAT LAKES THROUGH AT
LEAST SUNDAY. AS IS TYPICAL WITH THE FAST PACED NW FLOW...TIMING OF
SMALLER DISTURBANCES WILL BE KEY IN OUR UPCOMING WEATHER...WHICH CAN
BE MORE DIFFICULT TO PREDICT.
AT 00Z WEDNESDAY OUR FIRST DISTURBANCE WILL BE SET UP ACROSS S
MANITOBA /COLD FRONT/. THE SFC-500MB LOW WILL BE SITUATED ACROSS
HUDSON BAY AND W QUEBEC...WITH THE TAIL END OF THE COLD FRONT
CROSSING LAKE SUPERIOR IN THE EVENING...BEFORE PUSHING ACROSS UPPER
MI OVERNIGHT.
OUR TUESDAY WARM-UP TO NEAR NORMAL AND SLIGHTLY ABOVE NORMAL
TEMPERATURES WILL BE SHORT LIVED...AS WE RETURN TO THE 60S FOR HIGHS
ON WEDNESDAY. 850MB TEMPS WILL FALL TO 7-10C WEDNESDAY...WHICH WILL
BE QUITE A DIFFERENCE FROM JUST 24 HOURS EARLIER WHERE THEY WERE
12-16C.
WITH CONTINUED N-NW FLOW OFF LAKE SUPERIOR 850MB TEMPS WILL CONTINUE
TO FALL TO 4-9C BY DAYBREAK THURSDAY...WITH -2C JUST NE OF LAKE
SUPERIOR. UNDER A MOSTLY CLEAR SKY...TEMPS IN THE LOW TO MID 40S MAY
NEED TO BE ADJUSTED LOWER. HUMIDITY VALUES WILL LIKELY FALL INTO THE
LOW TO MID 30S THURSDAY...ON 40S DEW POINTS AND LIGHT NW WINDS LESS
THAN 10KTS AS THE SFC HIGH SITS OVER THE UPPER GREAT LAKES. TEMPS
SHOULD JUMP BACK TO NEAR NORMAL VALUES ONCE AGAIN /70S/.
THE SFC HIGH WILL SINK TO THE OHIO VALLEY THURSDAY NIGHT...WITH
INCREASED WAA ON W WINDS..WITH TEMPS ON FRIDAY NEARING THE 80 DEGREE
MARK ACROSS THE ENTIRE CWA. THE CHANCE FOR WET WEATHER WILL RETURN
FRIDAY NIGHT THROUGH SATURDAY AS ANOTHER COLD FRONT SINKS ACROSS
FROM THE NW...FOLLOWED BY ANOTHER STRONGER SFC HIGH FOR SATURDAY
NIGHT THROUGH SUNDAY.
THERE WILL BE A CHANGE IN THE WORKS TO OUR FAR W AND E 500MB LOWS
STARTING MID WEEK...AS THE ENTIRE 500MB PATTERN BEGINS TO SLOWLY
SHIFT E. THIS WILL ALLOW THE RIDGE CENTERED OVER THE PLAINS STATE TO
BE PUSHED E ACROSS THE UPPER GREAT LAKES SUNDAY THROUGH MONDAY...IN
ADVANCE OF THE PACIFIC NW LOW MOVING TO THE CANADA/ND BORDER.
ONLY HAVE SLIGHT CHANCE THUNDER GOING FOR AND HIGH CHANCE POPS FOR
MONDAY...GIVEN THAT THE SYSTEM WILL LIKELY STILL BE SET UP ACROSS
THE DAKOTAS...AND TIMING IS A CONCERN INITIALLY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 205 AM EDT TUE SEP 3 2013
HIGH PRES CURRENTLY OVER THE UPPER MISSISSIPPI VALLEY WILL STEADILY
MOVE SE OVER THE NEXT 24HRS WHILE A COLD FRONT DROPS SE...REACHING
LAKE SUPERIOR THIS EVENING. THE DRY AIR MASS ASSOCIATED WITH THE
HIGH WILL CONTINUE TO DOMINATE...RESULTING IN MAINLY CLEAR SKIES/VFR
CONDITIONS AT KIWD/KCMX/KSAW THRU THIS FCST PERIOD. HOWEVER...
TYPICAL OF THESE QUIET/RADIATIONAL COOLING NIGHTS...PATCHES OF
MAINLY SHALLOW FOG WILL AFFECT KIWD OVERNIGHT...RESULTING IN OCNL
WIDE VIS FLUCTUATIONS. UNDER TIGHTENING PRES GRADIENT JUST AHEAD OF
APPROACHING COLD FRONT...INCREASING WINDS ABOVE DEVELOPING NOCTURNAL
INVERSION MAY RESULT IN LLWS THIS EVENING AT ALL TERMINALS.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 317 PM EDT MON SEP 2 2013
NNW WINDS UP TO 30 KTS WITH A FEW LINGERING GALE FORCE GUSTS OVER
THE E LATE THIS AFTERNOON WILL DIMINISH TONIGHT WITH THE APPROACH OF
HI PRES FROM THE W. EXPECT A WSW WIND UP TO 20-25 KTS ON TUE...
STRONGEST OVER THE NCENTRAL WHERE THIS FLOW IS ACCENTUATED BETWEEN
THE KEWEENAW AND ISLE ROYALE...TO SHIFT TO THE NNW ON TUE NIGHT
BEHIND A COLD FRONTAL PASSAGE AND LINGER THRU THE DAY ON WED. THE
MOST PERSISTENT AND STRONGER WINDS DURING THIS EVENT WILL OCCUR OVER
THE E UNDER A SHARPER PRES GRADIENT. THEN PLAN ON WINDS UNDER 25 KTS
ON THU THRU SAT AS A RELATIVELY WEAK PRES GRADIENT AND HI OVERWATER
STABILITY DOMINATE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
BEACH HAZARDS STATEMENT UNTIL 6 AM EDT EARLY THIS MORNING FOR
MIZ005-006.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KF
AVIATION...ROLFSON
MARINE...KC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
627 PM CDT WED SEP 4 2013
.SYNOPSIS...
ISSUED AT 342 PM CDT WED SEP 4 2013
UPPER RIDGE OF HIGH PRESSURE CENTERED OVER THE CENTRAL HIGH PLAINS
CONTINUES TO DOMINATE THE OVERALL SYNOPTIC PATTERN...WITH A TROUGH
OF LOW PRESSURE OVER THE NORTHEASTERN STATES...AND ONE OFF THE
PACIFIC NORTHWEST COAST. AT THE SURFACE...A TROUGH OF LOW PRESSURE
ARCHES FROM EAST CENTRAL COLORADO ACROSS THE PANHANDLE INTO SOUTHERN
SOUTH DAKOTA. SURFACE HIGH PRESSURE REMAINS OFF TO THE EAST ACROSS
THE MID MISSISSIPPI RIVER VALLEY. AS OF 20Z TEMPERATURES RANGED
FROM THE MID 80S OVER THE HEART OF THE SANDHILLS...TO THE MID 90S
ALONG THE NORTH PLATTE RIVER VALLEY NEAR KOGA.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 342 PM CDT WED SEP 4 2013
THUNDERSTORM CHANCES AND ABNORMALLY WARM TEMPERATURES HIGHLIGHT THE
SHORT TERM DISCUSSION. DESPITE LARGE SCALE SUBSIDENCE ASSOCIATED
WITH THE UPPER LEVEL RIDGE...SUFFICIENT DAYTIME HEATING WILL COMBINE
WITH A WEAK MIDLEVEL DISTURBANCE TO SPARK OFF ISOLATED CONVECTION
ACROSS WESTERN AND SOUTHWEST NEBRASKA THIS EVENING. OBJECTIVE
ANALYSIS INDICATES 1000-2000 J/KG OF MUCAPE WITH EFFECTIVE SHEAR ON
THE ORDER OF 30 KTS. ISOLATED STRONG WIND GUSTS WOULD BE POSSIBLE
WITHIN OR NEAR ANY CELL THAT DEVELOPS...ESPECIALLY GIVEN THE
PROJECTED INVERTED V SOUNDINGS WITH LARGE T/TD SPREADS. THE
ACTIVITY MAY CONTINUE ACROSS THE HEART OF THE CWA OVERNIGHT AS A LLJ
RE-DEVELOPS WITH INCREASING CONVERGENCE & WAA...FOR THIS WILL CARRY
A SLIGHT CHANCE MENTION THROUGH 15Z THURSDAY FROM WEST TO EAST.
ADDITIONAL STORMS WILL BE POSSIBLE THURSDAY AFTERNOON...WITH THE
AMPLIFIED RIDGE ATOP THE CWA...AND SUBSEQUENT WEAK DISTURBANCES
PASSING THROUGH THE FLOW.
AS FOR TEMPERATURES...HIGHS WILL REMAIN WELL ABOVE AVERAGE AS H85
T/S WARM WELL ABOVE 30C FOR MOST LOCATIONS. HIGHS ON THURSDAY WILL
TOP OUT ONCE AGAIN IN THE LOW TO MID 90S FOR MOST LOCATIONS.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 342 PM CDT WED SEP 4 2013
FOR THE MID-RANGE FORECAST...WEATHER WILL BE HOT AND DRY. MODEL
OUTPUT STATISTICS FROM THE THREE AVAILABLE BULLETINS INDICATE
ANOTHER HEAT WAVE IN THE MIDDLE RANGE OF THE FORECAST. IT SEEMS THAT
100 PLUS IS NOT OUT OF THE QUESTION FRIDAY OVER ALL OF CENTRAL AND
WESTERN NEBRASKA WITH THE HOTTEST WEATHER ALONG THE NEBRASKA-SOUTH
DAKOTA STATE LINE.
THE GFS SHOWS THE HOTTEST AIR SINKING SOUTH TO SOUTH CENTRAL AND
SOUTHWEST NEBRASKA FOR SATURDAY AS A WEAK FRONT DRIFTS ACROSS INTO
NEBRASKA...BUT THAT LASTS ONLY ONE DAY. AS THE FRONT COMES INTO
NORTHERN NEBRASKA...IT WILL GENERATE SOME LIFT. A CROSS-SECTION
THROUGH NORTHERN NEBRASKA SHOWS INSTABILITY ABOVE 700MB AND SOME
HUMIDITY 75 PERCENT OR HIGHER. HOWEVER...BELOW THAT LEVEL...THE AIR
IS FAIRLY DRY AT 40-50 PERCENT. THE RESULT IS THAT PRECIPITATION
WILL BE SPOTTY AND FAIRLY LIGHT.
IT IS NOT UNTIL MONDAY THAT SIGNIFICANT RELIEF FROM THE HOT AND DRY
WEATHER CAN BE EXPECTED. AT THAT TIME...A MODERATE FRONT WILL MOVE
THROUGH NEBRASKA. THE GFS IS ABOUT 12 HOURS FASTER WITH THE FRONT
THAN IS THE GEM AND THE 12Z ECMWF IS ABOUT SIX HOURS FASTER THAN THE
GEM. THE DIFFERENCES AMONG THE MODELS COULD HAVE AN EFFECT ON THE
TIMING OF THE PRECIPITATION AND ALSO ON THE TEMPERATURES ON TUESDAY.
STILL...THERE IS ENOUGH AGREEMENT THAT WE CAN NUDGE THE CURRENT
FORECAST TO A BLEND OF THE THREE EXTENDED MODELS. THIS SHOULD BRING
TEMPERATURES 5-15 DEGREES LOWER MONDAY OR TUESDAY AND A CHANCE FOR
PRECIPITATION...THOUGH THERE IS STILL UNCERTAINTY REGARDING THE
TIMING...AMOUNT AND EXTENT OF THE PRECIPITATION. STILL...IT DOES
APPEAR THAT THE BETTER CHANCES FOR PRECIPITATION WILL BE IN THAT
MONDAY THROUGH WEDNESDAY PERIOD.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 626 PM CDT WED SEP 4 2013
THE HRRR MODEL SHOWS THE STORMS ACROSS WRN NEB MOVING SOUTH
THROUGH KOGA TONIGHT WHILE THE RAP MODEL LIFTS THEM NORTH THROUGH
KVTN AND AREAS WEST. THE LATEST RADAR DOES INDEED SHOW SOME STORMS
MOVING NORTH AND SOME TRYING TO MOVE SOUTH. THUS THE FCST IS A BIT
UNCERTAIN WITH THE TRACK OF THE STORMS. EITHER WAY...THE ACTIVITY
COULD LAST UNTIL 05Z AND THEN DISSIPATE IF NOT SOONER. THE LOW
LEVEL JET INCREASES TONIGHT AND THE MODELS SUGGEST A NEW SMALL
AREA OF STORMS COULD FORM ALONG BUT MOSTLY EAST OF HIGHWAY 83.
THIS ACTIVITY...IF IT FORMS...WOULD MOVE OFF EAST OF THE FCST AREA
BY 12Z THURSDAY. VFR IS EXPECTED THEREAFTER.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...JACOBS
SHORT TERM...JACOBS
LONG TERM...SPRINGER
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
1030 PM PDT MON SEP 2 2013
.SYNOPSIS...A VERY SLOW DRYING TREND IS EXPECTED THROUGH MUCH OF THE
WEEK...WITH CHANCES FOR SHOWERS AND THUNDERSTORMS GRADUALLY
DECREASING. TEMPERATURES WILL BE A FEW DEGREES ABOVE NORMAL IN MOST
AREAS.
&&
.UPDATE...SHOWERS/THUNDERSTORMS CONTINUING OVER SOUTHERN PORTIONS OF
THE AREA WITH NEW ACTIVITY DEVELOPING OVER CENTRAL AND SOUTHERN
MOHAVE AND SOUTHERN CLARK COUNTIES. THE ACTIVITY IN CLARK SEEMS TO
BE GENERATING ALONG AN OUTFLOW BOUNDARY AND THE STORMS ARE NOT
REALLY LASTING THAT LONG WHEN THEY DO DEVELOP. HOWEVER...THE STORMS
IN MOHAVE COUNTY LOOK TO BE DEVELOPING AHEAD OF A DISTURBANCE THAT
SHOWS UP NICELY IN BOTH THE RUC AND NAM12 MODELS. THESE STORMS ARE
LIKELY TO CONTINUE DEVELOPING NORTHWARD OVER THE NEXT FEW HOURS AND
COVERAGE MAY ALSO CONTINUE TO EXPAND. BEHIND THIS DISTURBANCE SKIES
WERE GENERALLY CLEARING AND THAT CLEARING WILL EVENTUALLY WORK INTO
MOHAVE COUNTY OVERNIGHT.
&&
.PREV DISCUSSION...
139 PM PDT MON SEP 2 2013
.SHORT TERM...SATELLITE AND AREA RADARS SHOWED THUNDERSTORMS MAINLY
CONFINED TO THE HIGHER TERRAIN OF LINCOLN...CLARK AND NORTHERN
MOHAVE COUNTIES THIS AFTERNOON. THESE ARE THE AREAS IN THE FLASH
FLOOD WATCH...SO THE WATCH LOOKS GOOD AT THIS TIME AND PLAN TO LEAVE
IT AS IS. THE MAIN FEATURE OF INTEREST IS THE MID LEVEL CIRCULATION
APPROACHING SOUTHERN CALIFORNIA FROM THE SOUTH. THIS FEATURE APPEARS
TO BE COMPRISED OF A PRE EXISTING UPPER LEVEL LOW WHICH WAS OFF THE
BAJA COAST PLUS PART OF THE CIRCULATION FROM THE REMNANTS OF
TROPICAL STORM KIKO. THIS FEATURE IS EXPECTED TO TRACK NORTH ACROSS
SOUTHEAST CALIFORNIA TONIGHT AND TUESDAY MORNING. WITH DEEP MOISTURE
STILL IN PLACE...BELIEVE THIS FEATURE SHOULD BE ABLE TO PRODUCE AT
LEAST LIGHT RAIN OVER THE WESTERN ZONES...SO RAISED POPS OVERNIGHT.
REMNANT ENERGY COULD LINGER OVER THE NORTHERN AND WESTERN ZONES
TUESDAY AFTERNOON...SO KEPT HIGHER POPS THERE. THE MAIN CONCERN WITH
THUNDERSTORMS CONTINUES TO BE FLASH FLOODING...BUT COVERAGE IS NOT
EXPECTED TO BE HIGH ENOUGH ON TUESDAY TO JUSTIFY EXTENDING THE FLASH
FLOOD WATCH. EXPECT LITTLE CHANGE IN TEMPERATURES FROM TODAY TO
TUESDAY...EXCEPT IN AREAS WHERE THUNDERSTORMS OCCUR.
.LONG TERM...WEDNESDAY THROUGH MONDAY...NO SIGNIFICANT CHANGES TO
THE LONG TERM FORECAST THIS AFTERNOON. THE WEATHER WILL BE DOMINATED
BY A TROUGH OF LOW PRESSURE OVER THE PACIFIC NORTHWEST...AN AREA OF
HIGH PRESSURE OVER THE ROCKIES/CENTRAL U.S...AND WHATEVER LOCAL
MOISTURE IS LEFT OVER AND RECYCLED EACH DAY. THIS LOOKS TO BRING
MAINLY A DIURNAL CYCLE OF SHOWERS/THUNDERSTORMS TO THE REGION. NO
TWO MODELS APPEAR TO AGREE ON A SIGNIFICANT FEATURE THAT WOULD BRING
ADDITIONAL DYNAMICS TO THE AREA. THE BEST CHANCES OF SCATTERED
CONVECTION WILL BE OVER THE HIGHER TERRAIN ACROSS THE EASTERN
CWA...WITH ISOLATED CHANCES IN THE VALLEYS AND BASINS. OVERALL THERE
APPEARS TO BE A GRADUAL DRYING TREND THROUGH THE PERIOD. THIS IS
MOST SIGNIFICANT OVER THE WEEKEND WHEN THE TROUGH PUSHES
ONSHORE...LIKELY BRINGING SOME ADDITIONAL DRYING FROM THE NORTHWEST.
TEMPERATURES WILL LIKELY REMAIN JUST ABOVE NORMAL THROUGH THE
PERIOD.
.AVIATION...FOR MCCARRAN...THUNDERSTORM CHANCES AT THE TERMINAL WILL
BE LOW THROUGH THE WEEK...ESPECIALLY FROM WEDNESDAY ONWARD. THERE
WILL BE THUNDERSTORM CHANCES IN ALL APPROACH CORRIDORS TUESDAY...AND
CHANCES SHOULD BE LIMITED TO THE MORMON MESA AND PEACH SPRINGS
CORRIDORS BEGINNING ON WEDNESDAY. WINDS WILL GENERALLY FOLLOW NORMAL
DIURNAL PATTERNS...EXCEPT OUTFLOW BOUNDARIES FROM THUNDERSTORMS
COULD BRING PERIODS OF GUSTY AND SHIFTING WINDS.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...CHANCES FOR THUNDERSTORMS WILL CONTINUE AREAWIDE
THROUGH TUESDAY...THEN DECREASE FROM THE WEST BEGINNING ON
WEDNESDAY. WINDS WILL GENERALLY FOLLOW NORMAL DIURNAL
PATTERNS...EXCEPT OUTFLOW BOUNDARIES FROM THUNDERSTORMS COULD BRING
PERIODS OF GUSTY AND SHIFTING WINDS.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
AZ...NONE.
CA...NONE.
&&
$$
UPDATE...JENSEN
PREV DISCUSSION...MORGAN/WOLCOTT
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1230 AM CDT TUE SEP 3 2013
.UPDATE...
ISSUED AT 1230 AM CDT TUE SEP 3 2013
SURFACE HIGH PRESSURE OVER IOWA WILL CONTINUE TO MOVE SOUTH AND EAST
TONIGHT. SURFACE LOW PRESSURE OVER MONTANA AND WYOMING IS FORECAST
TO APPROACH THE WESTERN DAKOTAS BY DAYBREAK. CURRENT FORECAST IS ON
TRACK WITH LIGHT SOUTHEAST WINDS...AND TEMPERATURE TREND ON TRACK
WITH MIDNIGHT TEMPERATURES IN THE 50S OVER MOST OF THE JAMES RIVER
BASIN TO THE LOWER 70S FAR WEST. LOW TEMPERATURES TONIGHT SHOULD
REACH THE LOWER 50S EASTERN PORTIONS OF CENTRAL NORTH DAKOTA TO THE
LOWER 60S FAR WEST. NO BIG CHANGES THIS UPDATE.
UPDATE ISSUED AT 946 PM CDT MON SEP 2 2013
SURFACE HIGH PRESSURE OVER MINNESOTA WILL CONTINUE TO MOVE SOUTH
AND EAST TONIGHT AS LOW PRESSURE IN EASTERN MONTANA MOVES INTO THE
WESTERN DAKOTAS BY 12 UTC TUESDAY. INCREASING MID AND HIGH LEVEL
CLOUDINESS CONTINUES TO SPILL OVER THE WESTERN RIDGE INTO THE
DAKOTAS AND WILL INCREASE CLOUD COVER ACROSS THE WEST TONIGHT.
LATEST 01 UTC HRRR AND RAP INDICATE SHOWERS MOVING INTO THE FAR
WEST AROUND 12 UTC TUESDAY. WILL KEEP THE OVERNIGHT PERIOD DRY FOR
NOW BUT WILL INTRODUCE ISOLATED THUNDERSHOWERS INTO THE FAR
SOUTHWEST AT 12 UTC...A COUPLE HOURS EARLIER THAN THE PREVIOUS
FORECAST. OTHERWISE NO CHANGES TO THE GOING FORECAST. CURRENT
FORECAST LOW TEMPERATURES LOOK REASONABLE WITH TUESDAY MORNING
LOWS A GOOD 5-10 DEGREES WARMER THAN THIS MORNING.
UPDATE ISSUED AT 641 PM CDT MON SEP 2 2013
NO UPDATES THIS EVENING OTHER THAN POPULATING WITH THE LATEST
SENSIBLE WEATHER GRIDS AND INTERPOLATING THROUGH MID EVENING. HIGH
PRESSURE OVER THE EASTERN DAKOTAS WILL CONTINUE TO MOVE EAST AS
LOW PRESSURE DEVELOPS IN EASTERN MONTANA.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 303 PM CDT MON SEP 2 2013
A RETURN TO WARM TEMPERATURES WILL HIGHLIGHT THE SHORT TERM
FORECAST.
THE 12 UTC GUIDANCE SUITE IS IN GOOD AGREEMENT ON LEE SURFACE
TROUGHING ACROSS EASTERN MONTANA AND WYOMING DEEPENING THROUGH
TONIGHT...THEN FILLING ON TUESDAY AS STRONG SURFACE HIGH PRESSURE
PROPAGATES FROM CANADA INTO THE NORTHERN PLAINS LATE IN THE DAY
ON TUESDAY WITH A STRONG SURFACE COLD FRONT ON THE LEADING EDGE OF
THE HIGH PRESSURE MAKING IT INTO APPROXIMATELY THE US HIGHWAY 2
CORRIDOR BY LATE AFTERNOON. HIGHS ON TUESDAY ARE FORECAST TO CLIMB
INTO THE UPPER 80S AND LOWER 90S SOUTH OF THE AFOREMENTIONED COLD
FRONT. ISOLATED THUNDERSTORMS ARE POSSIBLE WEST OF HIGHWAY 83
TUESDAY AFTERNOON AS THE SHORTWAVE CURRENTLY ACROSS NORTHEAST UTAH
CRESTS THE RIDGE LATE TUESDAY AFTERNOON INTO WESTERN NORTH DAKOTA.
SHEAR AND INSTABILITY PROFILES ARE NOT SUPPORTIVE OF SEVERE
CONVECTION.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 303 PM CDT MON SEP 2 2013
A BACKDOOR COLD FRONT MOVING THROUGH THE NORTHERN PLAINS TUESDAY
NIGHT WILL BRING COOLER TEMPERATURES TO WEST AND CENTRAL NORTH
DAKOTA ON WEDNESDAY...STILL ABOUT 5 DEGREES ABOVE NORMAL...WITH
HIGHS FROM THE MID 70S NORTH TO MID 80S SOUTH. THE WARMING TREND
THEN RESUMES THURSDAY INTO FRIDAY AS THE UPPER LEVEL RIDGE SHIFTS
EAST INTO THE GREAT PLAINS. STILL EXPECTING MOSTLY DRY CONDITIONS
OVER NORTH DAKOTA THROUGH THURSDAY NIGHT WITH A DRY NORTHWEST FLOW
ALOFT. MAY SEE A FEW SCATTERED SHOWERS/ISOLATED T-STORMS TUESDAY
EVENING AS AN EMBEDDED S/WV IMPULSE SLIDES EAST-SOUTHEAST THROUGH
THE DAKOTAS...AND AS THE COLD FRONT MOVES SOUTH ACROSS THE STATE.
WHILE INSTABILITY AND SHEAR PARAMETERS DO NOT INDICATE SEVERE
WEATHER...CANNOT COMPLETELY RULE OUT A STRONGER STORM OR TWO NEAR
THE COLD FRONT IN THE EVENING WHERE THE 12Z ECMWF INDICATES A
BRIEF PERIOD OF MODEST INSTABILITY NEAR 1500 J/KG.
AS WE HEAD INTO THE COMING WEEKEND...MODELS PROJECT THE RIDGE TO
BREAKDOWN AS A CLOSED UPPER LOW (NOW OFF THE PACIFIC NORTHWEST
U.S. COAST) MOVES INLAND THURSDAY...THEN EAST ACROSS THE
ROCKIES/TOWARDS THE NORTHERN PLAINS FRI NIGHT-SAT...AND EVENTUALLY
INTO THE REGION SUN-MON. AS THIS FEATURE APPROACHES...WILL START
TO SEE INCREASING CHANCES FOR PRECIPITATION WITH SLIGHT CHANCES
FRI/FRI NIGHT...AND BETTER CHANCES SATURDAY THROUGH MONDAY. THIS
FEATURE IS ALSO EXPECTED TO BRING COOLER WEATHER TO THE NORTHERN
PLAINS REGION...WHICH AT THIS TIME STILL LOOKS TO OCCUR POSSIBLY
SUNDAY WITH A BETTER CHANCE OF COOLER WEATHER NEXT SUNDAY NIGHT
INTO THE EARLY PORTIONS OF THE FOLLOWING WORK WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1230 AM CDT TUE SEP 3 2013
HIGH PRESSURE OVER IOWA AND LOW PRESSURE OVER MONTANA WILL RESULT IN
LIGHT EAST TO SOUTHEAST WINDS THROUGH 15Z AT TAF SITES.
AN UPPER LEVEL SHORTWAVE THAT WAS CURRENTLY OVER MONTANA/WYOMING IS
FORECAST TO ENTER WESTERN NORTH DAKOTA AFT 09Z AND MOVE SOUTHEAST
ACROSS NORTH DAKOTA TODAY. AS THIS OCCURS A SURFACE COLD FRONT THAT
WAS OVER MANITOBA AND SASKATCHEWAN IS FORECAST TO ENTER NORTH DAKOTA
AROUND 18Z AND MOVE SOUTHWARD ACROSS THE STATE AND EXIT NORTH DAKOTA
BY 06Z TUESDAY NIGHT/WEDNESDAY MORNING.
THESE FEATURES WILL PROVIDE A SLIGHT CHANCE OF THUNDERSTORMS ON
TUESDAY MAINLY WEST OF THE HIGHWAY 83 CORRIDOR. HOWEVER COVERAGE
WILL BE ISOLATED AND THUS WILL NOT MENTION A VCTS AT TAF SITES AT
THIS TIME. OTHERWISE VFR CONDITIONS AREA FORECAST. SOUTHERLY FLOW
ACROSS THE AREA WILL SHIFT NORTH AT KISN AND KMOT TUESDAY AFTERNOON
BEHIND THE COLD FRONT. SOUTHERN TAF SITES OF KDIK/KBIS/KJMS SHOULD
SEE A WIND SHIFT DURING THE EVENING HOURS AS THE FRONT MAKES ITS WAY
SOUTHWARD SLOWLY.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JV
SHORT TERM...AYD
LONG TERM...NH
AVIATION...JV
AREA FORECAST DISCUSSION...UPDATE
NWS PORTLAND OR
708 PM PDT WED SEP 4 2013
.SYNOPSIS...AN UPPER LEVEL LOW WILL CONTINUE THE THREAT FOR SHOWERS
AND THUNDERSTORMS TONIGHT THROUGH THURSDAY. LOCALIZED HEAVY RAINFALL
IS EXPECTED THURSDAY AND FRIDAY AS THE LOW MOVES OVER THE AREA.
SHOWERS WILL DECREASE FRIDAY EVENING AS THE HIGH PRESSURE BEGINS TO
BUILD BEHIND THE LOW. DRIER WEATHER IS EXPECTED THIS WEEKEND WITH
WARMING AND CONTINUED DRY WEATHER EXPECTED NEXT WEEK.
&&
.QUICK EVENING UPDATE...A SOUTH TO NORTH ELONGATED MID TO UPPER LEVEL
CLOUD DECK CONTINUES TO STREAM NORTHWARD OVER THE CASCADES AND
FOOTHILLS THIS EVENING. THESE CLOUDS HAVE PRODUCED QUITE THE VIRGA
STORM WITH NO MEASURABLE RAIN REPORTED AT ANY RAWS OR ASOS STATIONS
THUS FAR. HOWEVER...A TV STATION VIEWER DID REPORT SPRINKLES IN VIDA.
ASIDE FROM THAT...IT IS RELATIVELY QUIET HERE IN THE VERY SHORT TERM.
AS A RESULT...POPS WERE CUT OUT OF THE FORECAST THROUGH 03Z AND
TRIMMED SUBSTANTIALLY THROUGH 06Z.
THE UPPER LEVEL LOW PRESSURE CURRENTLY NEAR 130W WILL GENERALLY MOVE
TOWARDS THE CENTRAL OREGON COAST OVERNIGHT. AS IT DOES
SO...INCREASING DIFFLUENCE ALOFT AND NEGATIVE 700-500MB THETA LAPSE
RATES...ROUGHLY COINCIDENT WITH THE CIRRUS SHIELD PUSHING INTO COOS
BAY...WILL EXPAND NORTHEASTWARD OVERNIGHT. THIS AFTERNOONS RUNS OF
THE HRRR HAVE BEEN INSISTENT THAT A NARROW BAND OF SHOWERS WILL
DEVELOP IN RESPONSE TOWARDS 06Z NEAR EUGENE...BEFORE TRAINING
NORTH-NORTHWESTWARD TOWARDS CORVALLIS...PACIFIC CITY...TILLAMOOK AND
ASTORIA OVERNIGHT. THIS SEEMS PLAUSIBLE BASED ON THE GFS AND EC
ALTHOUGH CONFIDENCE IS STILL NOT TERRIBLY HIGH. NONETHELESS...IT IS
HARD TO IGNORE...SO POPS WERE SCALED UPWARD OVERNIGHT IN THIS
REGION...WITH CHANCE WORDING OF THUNDERSTORMS. ELSEWHERE...POPS WERE
GENERALLY NUDGED DOWN A TAD FOR THE 06-12Z PERIOD TONIGHT AS THE HRRR
INSISTS THIS BAND OF SHOWERS WILL REMAIN VERY FOCUS AND NARROW.
HOWEVER...CHANCE SHOWER WORDING AND SLIGHT CHANCE THUNDER WAS LEFT IN
THE FORECAST DUE TO THE SYNOPTIC PATTERN BEING FAVORABLE FOR
CONVECTION TO DEVELOP ANYWHERE ACROSS THE CWA OVERNIGHT...AND DUE TO
THE POSSIBILITY THE HRRR MAY BE OFF IN THE PLACEMENT OF THIS
DEVELOPING BAND OF SHOWERS. /NEUMAN
.SHORT TERM...A DEEP UPPER LEVEL LOW JUST OFFSHORE THE NORTHERN
OREGON COAST...CURRENTLY CENTERED NEAR 45N 129W...WILL SLOWLY THE
SOUTHERN OREGON COAST TONIGHT AND THURSDAY MORNING BEFORE MOVING
INLAND OVER NW OREGON THURSDAY AFTERNOON AND NIGHT. THIS LOW WILL
CONTINUE THE THREAT FOR SHOWERS AND THUNDERSTORMS THROUGH THURSDAY
NIGHT.
RADAR IMAGERY SHOWS A BAND OF SHOWERS MOVING OVER THE WILLAPA HILLS
EARLY THIS AFTERNOON. THERE HAS BEEN A COUPLE OF LIGHTNING STRIKES
WITH THESE SHOWERS CONFIRMING ATMOSPHERIC INSTABILITY. WATER VAPOR
IMAGERY SHOWS AN UPPER SHORTWAVE/JET ROUNDING THE BASE OF THE LOW
HEADING TOWARDS THE PORTLAND FORECAST AREA. THIS FEATURE WILL
STRENGTHEN AS THE LOW NEARS AND PROVIDE LIFT. INSTABILITY WILL ALSO
INCREASE AS COOLER AIR ALOFT MOVES IN AND MID LEVEL LAPSE RATES
INCREASE. MEANWHILE THE FLOW WILL TURN SOUTH TO SOUTHEASTERLY. THESE
VARIABLES ALL SUPPORT THE POSSIBILITY FOR NOCTURNAL THUNDERSTORMS
TONIGHT THROUGH THURSDAY MORNING.
ONSHORE FLOW WILL RETURN THURSDAY AFTERNOON AS THE UPPER LOW
CONTINUES TO PUSH INLAND. THIS WILL DIMINISH ELEVATED INSTABILITY
THURSDAY...BUT COOLING TEMPERATURES ALOFT WILL KEEP A CONTINUED
THREAT OF ISOLATED THUNDERSTORM ACTIVITY WITH LOCALLY HEAVY
SHOWERS THROUGH THURSDAY EVENING. THE THUNDERSTORM THREAT WILL
DECREASE THURSDAY AFTERNOON AND EVENING AND THE SHOWERS WILL BECOME
MORE PERSISTENT AND HEAVIER. FORECAST CONFIDENCE IN THE LOCATION OF
HIGHER QPF IS LOW AS THESE AREAS WILL DEPEND ON WHERE THE DEFORMATION
ZONE PIVOTS. RAINFALL IN EXCESS OF 1" IS EXPECTED...WITH
LOCALIZED AREAS POSSIBLY REACHING 1.5-2". CERTAINLY APPEARS SOME
MINOR FLOODING ISSUES WHEREVER THE HEAVY RAINFALL AXIS SETS
UP...WHICH WILL MOST LIKELY BE BETWEEN SALEM AND THE WASHINGTON
BORDER.
SHOWERS WILL CONTINUE FRIDAY AS CYCLONIC FLOW ON THE BACKSIDE OF THE
LOW LINGERS OVER THE AREA. MODELED 850MB FLOW SUGGESTS SOME
OROGRAPHIC ENHANCEMENT TO THE RAIN ON FRIDAY. SHOWERS WILL DECREASE
FRIDAY NIGHT AS THE LOW PUSHES FURTHER EAST AND HIGH PRESSURE BEGINS
TO BUILD.
.LONG TERM...SATURDAY EVENING THROUGH WEDNESDAY...
AFTER THE FALL LIKE WEATHER EXPECTED OVER THE NEXT COUPLE OF
DAYS...IT APPEARS THAT SUMMER WILL MAKE ITS RETURN IN THE EXTENDED
PERIOD. THE CLOSED LOW THAT IS IMPACTING THE REGION THIS WEEK IS
MODELED TO BE EJECTED INTO THE ROCKIES DURING THE SAT NIGHT INTO
SUNDAY TIMEFRAME. THIS WILL OPEN THE DOOR FOR A STRONG LATE SEASON
RIDGE TO BUILD INTO THE PAC NW NEXT WEEK. THE LATEST MEDIUM RANGE
MODELS INDICATE THAT 500 MB HEIGHTS WILL NEAR 590 DM OVER THE
REGION...WITH 850 MB TEMPS NEAR 20C BY TUE OR WED. MEANWHILE A
THERMAL INDUCED SURFACE TROUGH IS PROGGED TO BUILD ALONG THE
COAST...BRINGING AN EASTERLY COMPONENT TO THE LOW LEVEL FLOW.
THUS...IT IS LOOKING MORE AND MORE LIKELY THAT WE WILL SEE A
SIGNIFICANT WARM UP NEXT WEEK. HIGH TEMPS WERE BUMPED UP INTO THE
UPPER 80S FOR THE INTERIOR LOWLANDS FOR BOTH TUE AND WED. THE
OFFSHORE FLOW PATTERN WOULD ALSO ALLOW THE COAST TO SEE SOME OF THEIR
WARMEST TEMPERATURES OF THE SEASON.
&&
.AVIATION...MID TO HIGH LEVEL CLOUDS CONTINUE TO STREAM NORTH
ACROSS THE REGION THIS AFTERNOON WITH CIGS NEAR 6K-10K FT. SOME
MVFR CIGS REMAIN STUBBORN TO LIFT...MAINLY RIGHT ALONG THE
COLUMBIA RIVER. EXPECT WIDESPREAD VFR CONDITIONS THROUGH 04Z THIS
EVENING ALONG THE COAST...AND AT LEAST THROUGH 12Z THURSDAY
MORNING FOR INLAND SITES. MVFR CIGS AROUND 2500 FT WILL IMPACT
LOCATIONS ALONG THE COAST AND THE COLUMBIA RIVER AGAIN THROUGH
EARLY THURSDAY WITH INCREASING SHOWERS. OVERNIGHT ISOLATED
THUNDERSTORMS ARE POSSIBLE INLAND.
KPDX AND APPROACHES...VARIABLE HIGH AND MID CLOUDS WITH VFR
CONDITIONS TODAY. MVFR CIGS RETURN IN LOW STRATUS AND INCREASING
SHOWERS AFTER 08Z TONIGHT. THERE IS A 20 PERCENT CHANCE FOR
OVERNIGHT THUNDERSTORMS STARTING AROUND 03Z. /27
&&
.MARINE...RATHER BENIGN CONDITIONS CONTINUE THROUGH THE REMAINDER
OF THIS WEEK AS AN UPPER LOW OFF THE COAST WILL VERY SLOWLY DRIFT
E TODAY AND TONIGHT...THEN INLAND OVER THE PAC NW THU. GRADIENTS
WILL REMAIN WEAK WITH WINDS 15 KT OR LESS AND SEAS 3 TO 5 FT.
AS HIGH PRES BUILDS OVER THE NE PAC FRI AND THIS WEEKEND...WILL
HAVE A RETURN TO N TO NW WINDS OF 15 TO 20 KT...STRONGEST IN
AFTERNOONS AND EVENINGS. GUSTS TO 25 KT ARE POSSIBLE MAINLY OVER
THE CENTRAL COASTAL WATERS. SEAS WILL RUN 3 TO 6 FT...LARGEST S OF
NEWPORT DUE TO MORE WIND WAVES.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WA...NONE.
PZ...NONE.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1134 PM EDT WED SEP 4 2013
.SYNOPSIS...
HIGH PRESSURE WILL PROVIDE SEASONABLY COOL AND MAINLY DRY WEATHER
THROUGH THE END OF THE WEEK. THE COOLEST TEMPERATURES WILL OCCUR
THURSDAY INTO FRIDAY BEHIND A CANADIAN COLD FRONT. THERE IS THE
POTENTIAL FOR THE FIRST FROST OF THE SEASON ACROSS NORTHERN
PENNSYLVANIA LATE THURSDAY NIGHT INTO EARLY FRIDAY MORNING.
&&
.NEAR TERM /THROUGH THURSDAY/...
ALL IS WELL WITH CURR FCST BASED ON TRENDS AND RECENT RUC OUTPUT.
THE TEMPS MAY STAY UP EARLY IN THE NRN TIER WHERE THE CLOUDS GET
THICK FOR A LITTLE. SHOWERS ALONG THE FRONT ARE BROKEN AND SEEM
LIKE THEY WOULD NOT LAST VERY LONG AT ANY ONE LOCATION.
PREV...
BAND OF CLOUDS ASSOCD WITH THE FRONTAL LIFT IS ALMOST TO NRN
TIER...RIGHT ON TIME. NO CHANGES PLANNED FOR THIS 8 PM UPDATE.
PREV DISC...
MOISTURE CHALLENGED SFC FRONT DROPPING SOUTHWARD THROUGH THE
EASTERN GREAT LAKES TONIGHT. LEADING EDGE OF FRONTAL CLOUDS IS NOW
APPROACHING NORTHERN LAKE ONTARIO SHORELINE...AND EXPECT CLOUDS TO
BEGIN SETTLING SOUTH OF THE FINGER LAKES LATER THIS EVENING AND
SOUTH OF THE PA/NY BORDER BY OR SHORTLY PAST MIDNIGHT. VERY NARROW
RIBBON OF 1.00"+ PW ACCOMPANYING THE FRONT AND NLY BOUNDARY LAYER
FLOW WILL PREVENT MUCH IN THE WAY OF MEASURABLE PRECIPITATION WITH
THE FROPA...AND AREAS SOUTH OF I80 PROBABLY WON`T SEE ANY. KEPT
SLGT CHC TO CHC POPS GOING ALONG AND NORTH OF RT 6 OVER NORTHERN
TIER LATE TONIGHT AND EARLY THURSDAY.
THE AFOREMENTIONED COLD FRONT WILL PUSH SEWD ACRS THE AREA
THURSDAY MORNING. INCREASING NWLY COMPONENT WILL KEEP NW BREEZES
GOING OVERNIGHT...HOLDING TEMPERATURES ABOVE GUIDANCE AND IN THE
50S THROUGHOUT CENTRAL PA.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/...
A TASTE OF AUTUMN IS IN STORE FOR THE AREA ON THURSDAY WITH
STRONGLY CHANNELED NORTHWEST FLOW AND 850 MB TEMPS IN THE +6 TO
+10C RANGE ACROSS THE NORTHERN TWO THIRDS OF CENTRAL PA.
ANOMALOUSLY DRY AIR AND DOWNSLOPING FLOW ALONG WITH THE RELATIVELY
STRONG EARLY SEPT SUN ANGLE WILL HELP MAKE UP THE TEMPERATURE
DEFICIT WITH AFTERNOON HIGHS WARMING TO THE UPPER 70S ACROSS SOUTH
CENTRAL AND SOUTHEASTERN AREAS...WOULD NOT BE SURPRISED TO SEE A
FEW MAXES NEAR 80 GIVEN THE STRONG MIXING AND VERY DRY AIR MASS
WHICH USUALLY HELPS TO ADD A FEW DEGREES TO DAYTIME HIGHS IN THESE
SITUATIONS (AND PARTICULARLY WHEN IT`S BEEN AS DRY AS WE HAVE BEEN
THE LAST SEVERAL WEEKS). MAXES FARTHER NORTH WILL REACH THE LOWER
TO MID 70S ACROSS THE CENTRAL MOUNTAINS...AND UPPER 60S ACROSS THE
FAR NORTH.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
CANADIAN HIGH PRESSURE CONTINUES TO BUILD FROM THE UPPER MIDWEST
AND WILL DOMINATE THE PATTERN ON THROUGH THE END OF THE WORK WEEK AS
IT MIGRATES ACROSS THE GRT LKS TO THE MID- ATLANTIC COAST BY 06Z
SAT. A LARGE UPPER LEVEL RIDGE WILL REMAIN OVER THE CENTRAL UNITED
STATES THAT WILL ALLOW FOR FAIR AND DRY WEATHER TO BE EXPECTED.
ALONG WITH THIS WILL BE A TASTE OF FALL...WITH TEMPERATURES
AVERAGING BELOW NORMAL. THE HIGHLIGHT OF THE PERIOD COULD BE THE
FIRST FROST OF THE SEASON ACROSS THE NRN TIER. A CONSENSUS OF THE
04/12Z MOS GUIDANCE STRONGLY SUGGESTS THAT LOWS WILL DIP INTO THE
LOWER TO MID 30S. SOME OF THE GUIDANCE TAKES BFD BELOW FREEZING
WHICH IS NOT OUT OF THE QUESTION...AND IF THIS WERE TO OCCUR...IT
WOULD BE AHEAD SCHEDULE BUT NOT OVERLY IMPRESSIVE OR RECORD-
BREAKING FOR THE AREA. SO FAR...IT WILL BE CHILLY EVERYWHERE
FRIDAY MORNING WITH TEMPS LKLY DROPPING INTO THE MID- UPPER 40S IN
THE LWR SUSQ VLY (ESPECIALLY AWAY FROM THE HRB/YORK/LNS METRO
AREAS. EXPANDED THE PATCHY FROST ACROSS THE NORTHERN ZONES AND
WILL CONTINUE TO HIGHLIGHT THE FROST POTENTIAL IN THE HWO.
04/12Z MODEL AND ENSEMBLE GUIDANCE IS IN GENERAL AGREEMENT WITH
THE UPPER LEVEL PATTERN EVOLUTION THROUGH THE MEDIUM RANGE PERIOD.
THE NWP GUIDANCE IS DEPICTING A BROADENING/FLATTENING OF THE UPPER
TROUGH ACROSS EASTERN CANADA/NERN U.S OVER THE WEEKEND FOLLOWED BY
INCREASING HEIGHTS/UPPER RIDGING THROUGH EARLY NEXT WEEK...AS THE
PERSISTENT ROCKIES/HIGH PLAINS ANTICYCLONE MIGRATES ESEWD TOWARD
THE OZARKS. AT THE SFC...ANOTHER NW FLOW/CANADIAN COLD FRONT
SHOULD PUSH THROUGH THE AREA ON SUNDAY FOLLOWED BY HIGH PRESSURE
TAKING UP RESIDENCE IN NEW ENGLAND. THIS IS WHERE THE MODELS BEGIN
TO DIVERGE. THE CANADIAN CONTINUES TO ALLOW FOR A DEEPER
TROUGH..WHERE THE GFS AND THE EC TAKE A SHALLOWER TROUGH AND MORE
ZONAL FLOW ACROSS THE PA REGION. THE RH/S WILL BE MORE NEUTRAL TO
DRIER AND THE BOUNDARY MAY STALL OUT NEAR SRN PA AND LIFT BACK
NWD AS A WARM FRONT. TEMPS SHOULD TREND WARMER AFTER ENDING THE
WEEK ON A COOL NOTE...WITH THE PCPN PATTERN BECOMING A LITTLE MORE
UNSETTLED FROM SUN-TUE.
&&
.AVIATION /04Z THURSDAY THROUGH MONDAY/...
ONLY MINOR CHANGES MADE TO THE 03Z TAFS.
EARLIER DISCUSSION BELOW.
DECIDED TO TAKE OUT MENTION OF LOWER CIGS AND FOG LATER.
DEWPOINTS NOT REAL HIGH...AND WIND SHOULD KEEP POTENTIAL
FOR FOG AND LOWER SC TO A MINIMUM. PERHAPS A SPRINKLE ACROSS
THE FAR NORTH...BUT HARD EVEN TO SEE THAT.
MAIN THING WILL BE GUSTY WINDS ON THU...GIVEN THE SPEED
OF THE STRONG COLD FRONT.
WITH VERY COLD AIR IN PLACE FRIDAY MORNING...SOME POTENTIAL
FOR FOG IN SPOTS LIKE BFD AND IPT...GIVEN THE WARM WATER
TEMPS OF THE AREA RIVERS ETC.
OUTLOOK...
FRI...PATCHY AM FOG POSSIBLE.
SAT...VFR.
SUN...SCT SHRA POSSIBLE WITH FROPA.
MON...VFR WITH HIGH PRESSURE BUILDING IN.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DEVOIR
NEAR TERM...DANGELO/DEVOIR
SHORT TERM...DEVOIR/CERU
LONG TERM...CERU/STEINBUGL
AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1036 PM EDT WED SEP 4 2013
.SYNOPSIS...
HIGH PRESSURE WILL PROVIDE SEASONABLY COOL AND MAINLY DRY WEATHER
THROUGH THE END OF THE WEEK. THE COOLEST TEMPERATURES WILL OCCUR
THURSDAY INTO FRIDAY BEHIND A CANADIAN COLD FRONT. THERE IS THE
POTENTIAL FOR THE FIRST FROST OF THE SEASON ACROSS NORTHERN
PENNSYLVANIA LATE THURSDAY NIGHT INTO EARLY FRIDAY MORNING.
&&
.NEAR TERM /THROUGH THURSDAY/...
ALL IS WELL WITH CURR FCST BASED ON TRENDS AND RECENT RUC OUTPUT.
THE TEMPS MAY STAY UP EARLY IN THE NRN TIER WHERE THE CLOUDS GET
THICK FOR A LITTLE. SHOWERS ALONG THE FRONT ARE BROKEN AND SEEM
LIKE THEY WOULD NOT LAST VERY LONG AT ANY ONE LOCATION.
PREV...
BAND OF CLOUDS ASSOCD WITH THE FRONTAL LIFT IS ALMOST TO NRN
TIER...RIGHT ON TIME. NO CHANGES PLANNED FOR THIS 8 PM UPDATE.
PREV DISC...
MOISTURE CHALLENGED SFC FRONT DROPPING SOUTHWARD THROUGH THE
EASTERN GREAT LAKES TONIGHT. LEADING EDGE OF FRONTAL CLOUDS IS NOW
APPROACHING NORTHERN LAKE ONTARIO SHORELINE...AND EXPECT CLOUDS TO
BEGIN SETTLING SOUTH OF THE FINGER LAKES LATER THIS EVENING AND
SOUTH OF THE PA/NY BORDER BY OR SHORTLY PAST MIDNIGHT. VERY NARROW
RIBBON OF 1.00"+ PW ACCOMPANYING THE FRONT AND NLY BOUNDARY LAYER
FLOW WILL PREVENT MUCH IN THE WAY OF MEASURABLE PRECIPITATION WITH
THE FROPA...AND AREAS SOUTH OF I80 PROBABLY WON`T SEE ANY. KEPT
SLGT CHC TO CHC POPS GOING ALONG AND NORTH OF RT 6 OVER NORTHERN
TIER LATE TONIGHT AND EARLY THURSDAY.
THE AFOREMENTIONED COLD FRONT WILL PUSH SEWD ACRS THE AREA
THURSDAY MORNING. INCREASING NWLY COMPONENT WILL KEEP NW BREEZES
GOING OVERNIGHT...HOLDING TEMPERATURES ABOVE GUIDANCE AND IN THE
50S THROUGHOUT CENTRAL PA.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/...
A TASTE OF AUTUMN IS IN STORE FOR THE AREA ON THURSDAY WITH
STRONGLY CHANNELED NORTHWEST FLOW AND 850 MB TEMPS IN THE +6 TO
+10C RANGE ACROSS THE NORTHERN TWO THIRDS OF CENTRAL PA.
ANOMALOUSLY DRY AIR AND DOWNSLOPING FLOW ALONG WITH THE RELATIVELY
STRONG EARLY SEPT SUN ANGLE WILL HELP MAKE UP THE TEMPERATURE
DEFICIT WITH AFTERNOON HIGHS WARMING TO THE UPPER 70S ACROSS SOUTH
CENTRAL AND SOUTHEASTERN AREAS...WOULD NOT BE SURPRISED TO SEE A
FEW MAXES NEAR 80 GIVEN THE STRONG MIXING AND VERY DRY AIR MASS
WHICH USUALLY HELPS TO ADD A FEW DEGREES TO DAYTIME HIGHS IN THESE
SITUATIONS (AND PARTICULARLY WHEN IT`S BEEN AS DRY AS WE HAVE BEEN
THE LAST SEVERAL WEEKS). MAXES FARTHER NORTH WILL REACH THE LOWER
TO MID 70S ACROSS THE CENTRAL MOUNTAINS...AND UPPER 60S ACROSS THE
FAR NORTH.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
CANADIAN HIGH PRESSURE CONTINUES TO BUILD FROM THE UPPER MIDWEST
AND WILL DOMINATE THE PATTERN ON THROUGH THE END OF THE WORK WEEK AS
IT MIGRATES ACROSS THE GRT LKS TO THE MID- ATLANTIC COAST BY 06Z
SAT. A LARGE UPPER LEVEL RIDGE WILL REMAIN OVER THE CENTRAL UNITED
STATES THAT WILL ALLOW FOR FAIR AND DRY WEATHER TO BE EXPECTED.
ALONG WITH THIS WILL BE A TASTE OF FALL...WITH TEMPERATURES
AVERAGING BELOW NORMAL. THE HIGHLIGHT OF THE PERIOD COULD BE THE
FIRST FROST OF THE SEASON ACROSS THE NRN TIER. A CONSENSUS OF THE
04/12Z MOS GUIDANCE STRONGLY SUGGESTS THAT LOWS WILL DIP INTO THE
LOWER TO MID 30S. SOME OF THE GUIDANCE TAKES BFD BELOW FREEZING
WHICH IS NOT OUT OF THE QUESTION...AND IF THIS WERE TO OCCUR...IT
WOULD BE AHEAD SCHEDULE BUT NOT OVERLY IMPRESSIVE OR RECORD-
BREAKING FOR THE AREA. SO FAR...IT WILL BE CHILLY EVERYWHERE
FRIDAY MORNING WITH TEMPS LKLY DROPPING INTO THE MID- UPPER 40S IN
THE LWR SUSQ VLY (ESPECIALLY AWAY FROM THE HRB/YORK/LNS METRO
AREAS. EXPANDED THE PATCHY FROST ACROSS THE NORTHERN ZONES AND
WILL CONTINUE TO HIGHLIGHT THE FROST POTENTIAL IN THE HWO.
04/12Z MODEL AND ENSEMBLE GUIDANCE IS IN GENERAL AGREEMENT WITH
THE UPPER LEVEL PATTERN EVOLUTION THROUGH THE MEDIUM RANGE PERIOD.
THE NWP GUIDANCE IS DEPICTING A BROADENING/FLATTENING OF THE UPPER
TROUGH ACROSS EASTERN CANADA/NERN U.S OVER THE WEEKEND FOLLOWED BY
INCREASING HEIGHTS/UPPER RIDGING THROUGH EARLY NEXT WEEK...AS THE
PERSISTENT ROCKIES/HIGH PLAINS ANTICYCLONE MIGRATES ESEWD TOWARD
THE OZARKS. AT THE SFC...ANOTHER NW FLOW/CANADIAN COLD FRONT
SHOULD PUSH THROUGH THE AREA ON SUNDAY FOLLOWED BY HIGH PRESSURE
TAKING UP RESIDENCE IN NEW ENGLAND. THIS IS WHERE THE MODELS BEGIN
TO DIVERGE. THE CANADIAN CONTINUES TO ALLOW FOR A DEEPER
TROUGH..WHERE THE GFS AND THE EC TAKE A SHALLOWER TROUGH AND MORE
ZONAL FLOW ACROSS THE PA REGION. THE RH/S WILL BE MORE NEUTRAL TO
DRIER AND THE BOUNDARY MAY STALL OUT NEAR SRN PA AND LIFT BACK
NWD AS A WARM FRONT. TEMPS SHOULD TREND WARMER AFTER ENDING THE
WEEK ON A COOL NOTE...WITH THE PCPN PATTERN BECOMING A LITTLE MORE
UNSETTLED FROM SUN-TUE.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
DECIDED TO TAKE OUT MENTION OF LOWER CIGS AND FOG LATER.
DEWPOINTS NOT REAL HIGH...AND WIND SHOULD KEEP POTENTIAL
FOR FOG AND LOWER SC TO A MINIMUM. PERHAPS A SPRINKLE ACROSS
THE FAR NORTH...BUT HARD EVEN TO SEE THAT.
MAIN THING WILL BE GUSTY WINDS ON THU...GIVEN THE SPEED
OF THE STRONG COLD FRONT.
WITH VERY COLD AIR IN PLACE FRIDAY MORNING...SOME POTENTIAL
FOR FOG IN SPOTS LIKE BFD AND IPT...GIVEN THE WARM WATER
TEMPS OF THE AREA RIVERS ETC.
OUTLOOK...
FRI...PATCHY AM FOG POSSIBLE.
SAT...VFR.
SUN...SCT SHRA POSSIBLE WITH FROPA.
MON...VFR WITH HIGH PRESSURE BUILDING IN.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DEVOIR
NEAR TERM...DANGELO/DEVOIR
SHORT TERM...DEVOIR/CERU
LONG TERM...CERU/STEINBUGL
AVIATION...MARTIN
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
234 PM MDT TUE SEP 3 2013
.SHORT TERM...THIS EVENING THROUGH WEDNESDAY NIGHT
ISSUED AT 234 PM MDT TUE SEP 3 2013
WATER VAPOR IMAGERY HAS THE UPPER RIDGE BUILDING FROM THE ROCKIES
INTO THE PLAINS. SEVERAL SHORTWAVES ARE MOVING THROUGH THE RIDGE
WITH ONE OVER CENTRAL SOUTH DAKOTA...TWO SMALL WAVES IN WESTERN AND
CENTRAL WYOMING...AND A LARGER WAVE NEAR SALT LAKE CITY. RADAR HAS
CONVECTION EXTENDING THROUGH CENTRAL SOUTH DAKOTA...WITH NOT MUCH
HAPPENING OVER WYOMING WITH THE SMALLER WAVES. VISIBLE SATELLITE IS
SHOWING SOME CU DEVELOPING OVER THE BLACK HILLS...PARTS OF
NORTHEASTERN WYOMING AND SOUTHWEST SOUTH DAKOTA. AT THE SURFACE...AN
AREA OF LOW PRESSURE IS LOCATED OVER SOUTHWESTERN SOUTH DAKOTA WITH
A WARM FRONT EXTENDING THROUGH SOUTH CENTRAL SOUTH DAKOTA AND A LEE
TROF THROUGH THE BLACK HILLS AND EASTERN MONTANA.
FOR TONIGHT...NOT CONFIDENT IN THE PLACEMENT OF CONVECTION WITH THE
HRRR AND RAP MODELS SHOWING LITTLE IF ANY CONVECTION AND LESS MLCAPE
THAN THE NAM OR GFS. EXPECT SOME CONVECTION WILL FIRE DUE TO DIURNAL
HEATING...HOWEVER SHEAR IS NOT OVERLY IMPRESSIVE FOR SEVERE
POTENTIAL. MAIN CONCERN WITH ANY STORM THAT DEVELOPS TONIGHT WILL BE
HEAVY RAIN POTENTIAL. PWS ARE 200 PERCENT OF NORMAL WITH STORM
MOVEMENT AROUND 15KTS. HOWEVER WITH MY LACK OF CONFIDENCE ON STORM
DEVELOPMENT AND PLACEMENT HAVE DECIDED TO FORGO ANY TYPE OF HYDRO
HEADLINES AT THIS TIME.
ON WEDNESDAY/WEDNESDAY NIGHT...UPPER RIDGE SHOULD AMPLIFY FURTHER
INTO THE NORTHERN PLAINS. HOWEVER...TEMPS WILL BE FEW DEGREES COOLER
AS SURFACE LOW SHIFTS INTO EASTERN COLORADO AND PULLS IN SLIGHTLY
COOLER AIR FROM THE NORTH. BEST CHANCE FOR ANY CONVECTION WILL BE
ACROSS THE FAR WESTERN ZONES NEAR THE INVERTED TROF EXTENDING NORTH
FROM THE SURFACE LOW OVER EASTERN COLORADO AND POSSIBLY IN SOUTH
CENTRAL SOUTH DAKOTA WITH THE WARM FRONT EXTENDING THROUGH NORTHERN
NEBRASKA.
&&
.LONG TERM...THURSDAY THROUGH TUESDAY
ISSUED AT 234 PM MDT TUE SEP 3 2013
LONG WAVE RIDGE OVER CWA WITH A LONG WAVE TROF OVER THE LOWER GREAT
LAKES AND JUST OFF THE WEST COAST. GFS AND ECMWF SHOW PROGRESSION
OF STRONG SHORT WAVE OUT OF THE WEST COAST TROF TO ERN MT BY 12Z
MON AS LONG WAVE RIDGE UNDERGOES FLATTENING AND DISCONTINUOUS
RETROGRESSION TO 135W BY 12Z MON. RIDGE THEN AMPLIFIES AND MOVES
SLOWLY E WARD DURING MID WEEK.
THIS EVOLUTION ALLOWS SIGNIFICANT SURGE OF COOLER AIR FOLLOWING E
WARD MOVEMENT OF SHORT WAVE TROF AND A RETURN TO MORE SEASONAL
TEMPERATURES TUES. THE COLD FRONT AND UPPER SUPPORT LEADING THIS
SURGE WILL LIKELY RESULT IN SHOWERS AND TSTMS REFLECTED IN HIGHER
POPS SATURDAY INTO MONDAY.
STAYED QUITE CLOSE TO GUIDANCE WITH TEMPERATURES THROUGH THE
EXTENDED.
&&
.AVIATION...FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON
ISSUED AT 234 PM MDT TUE SEP 3 2013
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY
AND TONIGHT ACROSS THE AREA. OTHERWISE VFR CONDITIONS WILL CONTINUE
THROUGH THE PERIOD.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
SHORT TERM...MLS
LONG TERM...BARBER
AVIATION...BARBER
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
1144 PM CDT MON SEP 2 2013
.DISCUSSION...
UPDATED FOR 06Z AVIATION DISCUSSION
&&
.PREV DISCUSSION... /ISSUED 814 PM CDT MON SEP 2 2013/
UPDATE...
A COLD FRONT CURRENTLY STRETCHES FROM NEAR HUNTINGDON TENNESSEE TO
NEAR SEARCY ARKANSAS. SHOWER AND THUNDERSTORM ACTIVITY THAT WAS
OCCURRING ALONG AND AHEAD OF THE FRONT HAS DISSIPATED DUE TO THE
LOSS OF DAYTIME HEATING. HOWEVER...DON/T EXPECT THE RADAR SCOPE TO
STAY CLEAR OVERNIGHT. THE LATEST HRRR SHOWS ISOLATED SHRAS/TSRAS
POPPING UP OVERNIGHT SOUTH OF THE FRONT. THUS WILL CONTINUE WITH
SLIGHT CHANCE TO CHANCE POPS AT THIS TIME. MEANWHILE...DRIER AIR
WILL FILTER INTO NORTHERN LOCATIONS OF THE MIDSOUTH OVERNIGHT.
DEWPOINTS ARE IN THE UPPER 50S TO LOWER 60S JUST NORTHWEST OF THE
CWA. CURRENT FORECAST LOOKS GOOD...MAY SEND UPDATE WITH POPS
SHORTLY BEFORE MIDNIGHT REFLECTING CURRENT POSITION OF FRONT.
KRM
DISCUSSION... /ISSUED 243 PM CDT MON SEP 2 2013/
SHOWERS AND THUNDERSTORMS ARE DEVELOPING ACROSS THE MIDSOUTH AND
WILL LIKELY INTERRUPT MANY AFTERNOON LABOR DAY PLANS. HOWEVER...I
WOUND NOT CANCEL PLANS ALL TOGETHER...STORMS SHOULD NOT LAST MORE
THAN 30-45 MIN`S. SECURE ANY LAWN FURNITURE...SEEK SHELTER FROM
THE LIGHTNING AND RESUME THE FESTIVITIES AFTER STORMS PASS.
A COLD FRONT IS MOVING INTO THE MIDSOUTH. AT 2:00 PM IT WAS
LOCATED GENERALLY ALONG A LINE FROM PARIS TENNESSEE TO NEAR
INTERSTATE 40 IN EAST CENTRAL ARKANSAS. TO THE SOUTH OF THIS
BOUNDARY...SHOWERS AND THUNDERSTORMS WILL REMAIN LIKELY WITH A
DRIER COOLER AIRMASS WORKING INTO TO THE MIDSOUTH TO ITS NORTH AND
WEST. WINDS WILL SHIFT FROM THE NORTH BEHIND THE FRONT...BUT THE
DRIER AIR WILL TAKE SEVERAL MORE HOURS TO ARRIVE. CURRENTLY...DEW
POINTS ARE STILL IN THE LOW 70S ACROSS MOST OF NORTHEAST
ARKANSAS...BUT LOW 60S...EVEN UPPER 50S ARE NOT FAR AWAY IN
CENTRAL AND SOUTHWESTERN MISSOURI.
ONGOING CONVECTION MAINLY ACROSS WEST TENNESSEE...WILL CONTINUE TO
INCREASE IN COVERAGE...AS THEY MOVE TO THE EAST TO SOUTHEAST THIS
AFTERNOON AND TONIGHT. THEY ARE DEVELOPING IN A HIGH
INSTABILITY...LOW SHEAR ENVIRONMENT FEATURING CAPE`S APPROACHING
3000 AND LI`S IN THE -3 TO -6 RANGE. EFFECTIVE BULK SHEAR IS LESS
THAN 25 KTS. NEGATIVE 10C DEGREE LEVELS ARE CURRENTLY AROUND
20-21K FT WITH -20C AROUND 25K FT. THE LIKELIHOOD OF HAIL IS
FAIRLY LOW...BUT CERTAINLY CANNOT BE RULED OUT. THE MAIN THREAT
FROM ANY STRONG OR SEVERE STORMS WILL BE LOCALIZED DAMAGING WIND.
HOWEVER...EVEN THOUGH LIGHTNING IS NOT A SEVERE WEATHER
PARAMETER FOR WARNING PURPOSES...THAT IS TRULY THE MAIN THREAT
FROM THESE STORMS...ESPECIALLY CONSIDERING THE NUMBER OF OUTDOOR
ACTIVITIES ONGOING TODAY. KEEP AN EYE TO THE SKY. STORMS WILL
CONTINUE TONIGHT...BUT LIKELY BECOME CONFINED TO NORTH MISSISSIPPI
BY MIDNIGHT. FLOODING IS ALSO A CONCERN...RAINFALL RATES IN EXCESS
OF 2.5 INCHES PER HOUR AND TRAINING THUNDERSTORMS COULD RESULT IN
LOCALIZED FLOODING PROBLEMS. SEVERAL FLASH FLOOD WARNINGS HAVE
ALREADY BEEN ISSUED IN WEST TENNESSEE AND NORTH MISSISSIPPI.
TOMORROW...THAT COOLER DRIER AIRMASS WILL BE EVIDENT. NEAR NORMAL
TEMPERATURES...OR HIGHS GENERALLY IN THE MIDDLE TO UPPER 80S ARE
EXPECTED...BUT DEW POINTS WILL BE IN THE LOW TO MIDDLE 60S
INSTEAD OF THE LOW 70S RESULTING IN MUCH MORE PLEASANT CONDITIONS.
NO RAINFALL IS EXPECTED TOMORROW TROUGH THE END OF THE FORECAST
PERIOD. TEMPERATURES WILL BE NEAR TO SLIGHTLY ABOVE NORMAL AS A
RIDGE ALOFT DOMINATES OUR WEATHER PATTERN.
&&
.AVIATION...
06Z TAF CYCLE
MAIN CONCERN OVERNIGHT IS THE DEVELOPMENT OF FOG...ESPECIALLY IN
AREAS THAT HAD RAIN EARLIER. CLEARING SKIES...LIGHT WINDS AND
EARLIER RAIN HAVE ALREADY RESULTED IN LIFR VSBYS AT KMKL WHICH
COULD DETERIORATE TO VLIFR AT TIMES OVER THE NEXT FEW HOURS
DEPENDING ON WHETHER DRIER AIR FILTERS IN. DRIER AIR HAS WORKED
INTO KJBR SO VFR CONDS WILL PREVAIL THERE THROUGHOUT THE PERIOD.
EXPECT ENOUGH MIXING INVOF KMEM TO KEEP FOG DEVELOPMENT AT BAY.
KTUP DID NOT HAVE ANY RAIN SO ONLY SOME MVFR VSBYS IN LIGHT FOG
ARE POSSIBLE. VFR CONDS EXPECTED AREA WIDE ON TUESDAY. LIGHT
NORTH/CALM WINDS OVERNIGHT WILL BECOME NNE AT 7-10 KTS BY 03/15Z.
SJM
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 71 88 68 89 / 30 0 10 10
MKL 64 85 58 86 / 20 0 10 10
JBR 66 86 62 88 / 10 0 10 10
TUP 70 89 66 90 / 40 10 10 10
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
936 PM CDT Wed Sep 4 2013
.UPDATE...
Most of the convective activity that developed this afternoon across
West Central TX has dissipated. However, we are seeing storms over
the I-35 corridor from Waco to near San Antonio holding together,
continuing a general westerly trend. While most of this activity
will continue to weak, the HRRR is suggesting additional shower
development tonight across mainly the Heartland Counties overnight
(namely Brown, Coleman, San Saba, and McCulloch Counties). I trimmed
PoPs back across the southwest counties for the remainder of the
overnight period and extended the mention of isolated thunderstorms
through 08z to account for this possibility.
Dewpoints across the Big Country tanked into the mid 30s this
afternoon due to strong subsidence and associated dry air mixing to
the surface. This brought precipitable water values below 1 inch
across the northwest half of the forecast area with pwats near 1.4
inches across the southeast. The bulk of the deeper moisture will
remain to our south and east through tomorrow but we will see
similar pwat values again tomorrow, suggesting the potential for
additional diurnal convection, especially across the southern half
of the area. For tonight, dewpoints will be slow to recover and
should allow temperatures to fall into the upper 60s, especially in
areas where cloud cover will be sparse. Min temps were updated
accordingly.
Johnson
&&
.PREV DISCUSSION... /ISSUED 552 PM CDT WED SEP 3 2013/
DISCUSSION...
/See below for aviation discussion/
AVIATION...
VFR next 24 hours. Isolated thunderstorms possible Thursday afternoon
south of the I-20 corridor. However potential is too low to include
in TAFS.
04
PREV DISCUSSION... /ISSUED 352 PM CDT WED SEP 3 2013/
SHORT TERM...(Tonight and Thursday)
Isolated showers and a few storms possible this afternoon and early
this evening, and again on Thursday afternoon and evening.
West Central Texas remains on the edge of the large upper level high
pressure dominating much of the southern plains. Abundant moisture
with east winds prevailing at most levels will combine with
afternoon temperatures climbing into the mid 90s to produce a few
storms. These storms will mainly be along the edge of the ridge axis
itself, across the southern and eastern portions of the area. Have
inserted a mention of storms into the forecast itself through the
early evening hours tonight and again for a few hours Thursday
afternoon.
Otherwise, clouds having an impact on temperatures this afternoon
and expect of the same tomorrow. Readings in the mid and upper 90s
across the northern half of the area, while the southern half of the
area runs in the lower 90s.
LONG TERM...(Thursday Night through Wednesday)
The upper ridge will remain centered over the Southern Plains
through this weekend with above normal temperatures continuing.
Cannot rule out isolated convection developing again across far
southern counties Friday afternoon/early evening so will include
this potential this forecast cycle.
By early next week, a short wave trough will move east across
the Northern Plains and across the Great Lakes region by mid week.
This system will push the upper high east of the area for the latter
part of the extended period and allow afternoon highs to cool a few
degrees. The upper high will be situated over the Ohio and Tennessee
Valleys, which will result in deeper low to mid level southeasterly
flow across the area. This pattern would be more favorable for
diurnal convection, especially across southeast sections Monday
through Wednesday of next week. Kept the forecast dry for now given
uncertainties this far out and wait to see how models perform in
subsequent runs before considering adding POPS to the
forecast.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 68 96 71 96 71 / 0 5 5 5 5
San Angelo 69 95 69 96 70 / 5 10 10 10 10
Junction 68 95 69 95 70 / 10 10 10 10 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
25
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
615 AM CDT TUE SEP 3 2013
.DISCUSSION...
SEE 12Z AVIATION DISCUSSION.
&&
.AVIATION...
NAM/GFS FCST SOUNDINGS SHOW PW VALUES APPROACHING 2.00 INCHES AND
K INDEX VALUES IN THE LOWER 40S. A WEAK BOUNDARY OVER NORTH TEXAS
WILL GRADUALLY SLIP SOUTH TODAY AND WILL LIKELY PROVIDE A LOW
LEVEL FOCUS FOR SHRA/TSRA. LEANED A BIT TOWARD THE TEXAS TECH WRF
AND THE HRRR WHICH SHOWS SCATTERED SHRA/TSRA DEVELOPING LATER THIS
MORNING THROUGH THIS EVENING. RAP 13 AND TEXAS TECH KEEPS THE
PRECIP GOING THROUGH 03Z WHILE THE NAM/GFS HINT AT POSSIBLE
CONVECTION PERSISTING THROUGH 09Z. 43
&&
.PREV DISCUSSION... /ISSUED 439 AM CDT TUE SEP 3 2013/
DISCUSSION...
MOSTLY CLEAR SKIES ACROSS THE SOUTHERN HALF OF SOUTHEAST TEXAS
THIS MORNING WITH PARTLY CLOUDY SKIES ACROSS THE NORTHERN HALF.
HAD SOME LIGHT SHOWERS IN GRIMES AND WALKER COUNTIES THIS MORNING
THAT HAVE FIZZLED.
TODAY THE BOUNDARY CURRENTLY LOCATED IN NORTHERN TEXAS WILL
CONTINUE TO PUSH SOUTHWARDS. THE DRIER DEWPOINTS IN NORTHERN
OKLAHOMA WILL NOT MAKE IT THIS FAR SOUTHWARDS BUT DRIER UPPER
LEVEL AIR WILL BEGIN TO FILTER DOWN INTO THE AREA LATER TODAY. AS
THE BOUNDARY SAGS SOUTHWARDS SCATTERED SHOWERS AND THUNDERSTORMS
WILL START TO DEVELOP IN THE NORTHERN COUNTIES THEN BEGIN TO FORM
ALONG THE SEA BREEZE LATER IN THE AFTERNOON. THERE IS ALSO A
SHORTWAVE CURRENTLY MAKING ITS WAY AROUND THE BASE OF AN UPPER
LEVEL TROUGH LOCATED IN THE GREAT LAKES REGION WHICH COULD ENHANCE
LIFT. LIFT WILL ALSO COME FROM 200 MB DIFFLUENCE AS SOUTHEAST
TEXAS LIES IN BETWEEN AN UPPER LEVEL TROUGH AND RIDGE. AS THE
DRIER AIR WORKS ITS WAY DOWN IT SHOULD START TO LIMIT
PRECIPITATION. GFS FORECAST SOUNDINGS SHOW PWATS APPROACHING 2.00"
AHEAD OF THE BOUNDARY (~1.60" AFTER DRIER AIR PASSES) WITH K
INDEX VALUES ABOVE 40. NAM FORECAST SOUNDINGS ARE SIMILAR WITH
SLIGHTLY HIGHER CAPE VALUES. DCAPE VALUES ALSO ARE AROUND 1000
J/KG WHICH SPELLS THE POSSIBILITY OF SOME STORMS PRODUCING STRONG
WINDS. GIVEN THE MECHANISMS OF LIFT MENTIONED ABOVE... INSTABILITY
AND MOISTURE IN PLACE ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS
SEEMS POSSIBLE TODAY.
ON WEDNESDAY DRIER AIR WILL MOST LIKELY LIMIT PRECIPITATION IN THE
NORTHERN HALF OF THE CWA AS THE DAY WANES THOUGH. NOT CONVINCED
THIS DRIER AIR WILL MAKE ITS WAY SOUTH OF I-10 SO WILL CONTINUE
SLIGHT PRECIP CHANCES IN THE SOUTHERN HALF OF THE CWA. BY
THURSDAY AN UPPER LEVEL LOW WILL MOVE INTO THE PACIFIC NORTHWEST
PUSHING THE UPPER LEVEL RIDGE EASTWARDS. CHANCES OF PRECIP LOOK TO
BE LIMITED LATER IN THE WEEK AS THE RIDGE MOVES TOWARDS US. BY
THE WEEKEND THE RIDGE WILL BEGIN TO WEAKEN SPELLING SLIGHTLY
COOLER TEMPERATURES OR MORE AVERAGE TEMPERATURES FOR THIS TIME OF
YEAR. 23
MARINE...
NO FCST ISSUES. LIGHT WINDS & LOW SEAS EXPECTED AS A WEAK BOUNDARY
SLIPS INTO SE TX. 43
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 96 75 98 75 99 / 40 20 10 10 10
HOUSTON (IAH) 97 76 97 76 97 / 40 30 20 10 20
GALVESTON (GLS) 90 81 90 81 90 / 30 20 20 10 20
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...23
AVIATION/MARINE...43
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1131 PM CDT MON SEP 2 2013
.AVIATION...
/6Z TAFS/
VFR CONDITIONS PREVAIL ACROSS NORTH TEXAS. AS MENTIONED IN THE
DISCUSSION BELOW...WEAK FRONTAL BOUNDARY REMAINS PLACED ACROSS THE
METROPLEX LATE THIS EVENING AND COULD SERVE AS A FOCUS FOR
ISOLATED CONVECTION DURING THE OVERNIGHT HOURS GIVEN THE FAIRLY
MOIST LOW LEVELS. FOR NOW...WILL LEAVE MENTION OF ANY
PRECIPITATION OUT BUT WILL HAVE TO MONITOR THE NEXT 6 HOURS FOR
POSSIBLE DEVELOPMENT. OTHERWISE...VFR CONDITIONS WILL PREVAIL WITH
LGT/VAR WINDS BECOMING EAST/NORTHEAST IN THE METROPLEX BY
MORNING. FARTHER SOUTH...A MORE EASTERLY DIRECTION CAN BE
EXPECTED.
DUNN
&&
.UPDATE...
RAN A LATE EVENING UPDATE TO INTRODUCE A 20 PERCENT CHANCE OF
STORMS IN THE FORECAST FOR LOCATIONS ALONG AND EAST OF A LINE FROM
DECATUR TO CLEBURNE FOR TONIGHT THROUGH SUNRISE TOMORROW.
THE PRIMARY REASON FOR THIS LATE EVENING UPDATE WAS BECAUSE OF A
FRONTAL BOUNDARY MOVING SOUTH TOWARDS THE INTERSTATE 30 CORRIDOR
AS OF 11 PM CDT. LATE AFTERNOON TO EARLY EVENING THUNDERSTORM
ACTIVITY MASKED THE MOVEMENT OF THIS BOUNDARY...BUT WITH ALL
THUNDERSTORM ACTIVITY DISSIPATED...IT IS EASY TO SEE IT MOVING
SOUTH AT THIS TIME. 04Z/11PM SURFACE OBSERVATIONS HAVE THE FRONT
LOCATED NEAR A LINE FROM DECATUR TO MCKINNEY TO COOPER. SURFACE
DEW POINTS OUT AHEAD OF THIS BOUNDARY WERE OBSERVED IN THE LOWER
TO MID 70S WHILE DEW POINTS TO THE NORTH WERE IN THE LOWER 60S.
WHILE THE TEMPERATURE DIFFERENCE ON EITHER SIDE OF THE BOUNDARY
WAS SMALL AS OF 11 PM...THE DIFFERENCE IN MOISTURE REPRESENTS A
NICE THETA-E GRADIENT TO TRACK IN HIGH RESOLUTION MODEL OUTPUT.
THE 03Z RAP SHOWS THIS THETA-E GRADIENT NICELY...AND INDICATES
THAT THE RIDGE OF THETA-E ALONG AND JUST SOUTH OF THE BOUNDARY
WILL SHIFT SOUTH OVER THE METROPLEX...CONTINUING EAST ALONG THE
I-20 AND I-30 CORRIDORS TO THE EASTERN BOUNDARY OF OUR CWA.
ANYWHERE FROM 08 TO 10Z /3 TO 5 AM/ THE RAP INDICATES THAT THIS
BOUNDARY WILL STALL LEAVING THE THETA-E RIDGE IN PLACE OVER THE
METROPLEX EXTENDING EAST ALONG THE I-20 CORRIDOR. THE HRRR
INDICATES THAT ONCE THIS BOUNDARY STALLS...IT MAY SERVE AS A FOCUS
FOR OVERNIGHT THUNDERSTORM INITIATION. RAW MODEL OUTPUT FROM THE
02Z HRRR SHOWS SCATTERED RAIN SHOWERS AND THUNDERSTORMS DEVELOPING
FROM THE DALLAS/TARRANT COUNTY BORDER EASTWARD DOWN THE INTERSTATE
20 CORRIDOR FROM 08 TO 10Z. GRANTED...NOT ALL MODEL OUTPUT
SUPPORTS THIS SOLUTION...BUT SINCE THE BOUNDARY IS EASY TO TRACK
NOW AND IT IS MOVING SOUTH WITH HIGH THETA-E AIR OUT AHEAD OF
IT...WENT AHEAD AND FOLLOWED THIS GUIDANCE FOR THE FORECAST
UPDATE.
NO SEVERE WEATHER IS EXPECTED IF STORMS DEVELOP LATE TONIGHT/EARLY
TOMORROW MORNING...HOWEVER ANY STORM MAY PRODUCE LOCALLY HEAVY
RAINFALL AND STRONG OUTFLOW WINDS UPON COLLAPSING. THERE IS STILL
VERY LITTLE DEEP LAYER SHEAR...SO SINGLE CELL/PULSE TYPE
THUNDERSTORMS WOULD BE THE DOMINANT STORM MODE IF ANYTHING MANAGES
TO DEVELOP. THE BOUNDARY LOOKS TO WASH OUT AFTER SUNRISE...SO ANY
LINGERING THUNDERSTORM ACTIVITY SHOULD FOLLOW SUIT.
CAVANAUGH
&&
.PREV DISCUSSION... /ISSUED 332 PM CDT MON SEP 2 2013/
A WEAK COLD FRONT WILL EASE THROUGH THE REGION TONIGHT THROUGH
TUESDAY AND BRING ONLY SLIGHTLY COOLER AND DRIER AIR. ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP AHEAD
OF THE COLD FRONT TONIGHT AND AFFECT MAINLY THE SOUTHERN ZONES.
ANY STORMS THAT DEVELOP TONIGHT WILL BE AIDED BY LARGE SCALE LIFT
FROM DIFFLUENT NORTHERLY FLOW ALOFT. A FEW STRONG TO SEVERE STORMS
ARE POSSIBLE WITH A THREAT OF DAMAGING DOWNBURST WINDS. A FEW
STORMS MAY LINGER IN THE EXTREME SOUTHERN ZONES ON TUESDAY ALONG
AND AHEAD OF THE WEAK COLD FRONT.
UPPER LEVEL HIGH PRESSURE WILL BUILD BACK OVER THE STATE THE
MIDDLE OF THE WEEK THROUGH THE WEEKEND AND RESULT IN A RETURN OF
HOT DAYS...WARM NIGHTS AND LITTLE CHANCE FOR RAIN. EXPECT
AFTERNOON HIGHS FROM THE MIDDLE 90S TO AROUND 100 EACH DAY WITH
OVERNIGHT LOWS GENERALLY IN THE 70S.
LOOKING BEYOND THIS FORECAST CYCLE...BOTH THE GFS AND ECMWF SHOW
THE UPPER RIDGE BREAKING DOWN BY THE MIDDLE OF NEXT WEEK WITH A
SUBSTANTIAL COLD FRONT MOVING THROUGH THE NORTHERN AND CENTRAL
PLAINS. THE SECOND TO THIRD WEEK OF SEPTEMBER IS TYPICALLY WHEN WE
SEE THE FIRST DECENT COLD FRONT...SO THESE SOLUTIONS MAY NOT BE
TOO FAR OFF.
79
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 73 98 74 100 77 / 20 5 5 5 5
WACO, TX 74 97 73 99 75 / 20 10 10 10 10
PARIS, TX 68 96 69 95 70 / 20 5 5 5 5
DENTON, TX 67 97 70 99 72 / 20 5 5 5 5
MCKINNEY, TX 67 96 68 98 70 / 20 5 5 5 5
DALLAS, TX 74 97 76 100 77 / 20 5 5 5 5
TERRELL, TX 71 97 72 97 74 / 20 5 5 5 5
CORSICANA, TX 73 96 73 98 74 / 20 10 10 10 10
TEMPLE, TX 72 98 72 99 74 / 30 20 10 10 10
MINERAL WELLS, TX 67 97 71 98 74 / 10 5 5 5 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1120 PM CDT MON SEP 2 2013
.UPDATE...
RAN A LATE EVENING UPDATE TO INTRODUCE A 20 PERCENT CHANCE OF
STORMS IN THE FORECAST FOR LOCATIONS ALONG AND EAST OF A LINE FROM
DECATUR TO CLEBURNE FOR TONIGHT THROUGH SUNRISE TOMORROW.
THE PRIMARY REASON FOR THIS LATE EVENING UPDATE WAS BECAUSE OF A
FRONTAL BOUNDARY MOVING SOUTH TOWARDS THE INTERSTATE 30 CORRIDOR
AS OF 11 PM CDT. LATE AFTERNOON TO EARLY EVENING THUNDERSTORM
ACTIVITY MASKED THE MOVEMENT OF THIS BOUNDARY...BUT WITH ALL
THUNDERSTORM ACTIVITY DISSIPATED...IT IS EASY TO SEE IT MOVING
SOUTH AT THIS TIME. 04Z/11PM SURFACE OBSERVATIONS HAVE THE FRONT
LOCATED NEAR A LINE FROM DECATUR TO MCKINNEY TO COOPER. SURFACE
DEW POINTS OUT AHEAD OF THIS BOUNDARY WERE OBSERVED IN THE LOWER
TO MID 70S WHILE DEW POINTS TO THE NORTH WERE IN THE LOWER 60S.
WHILE THE TEMPERATURE DIFFERENCE ON EITHER SIDE OF THE BOUNDARY
WAS SMALL AS OF 11 PM...THE DIFFERENCE IN MOISTURE REPRESENTS A
NICE THETA-E GRADIENT TO TRACK IN HIGH RESOLUTION MODEL OUTPUT.
THE 03Z RAP SHOWS THIS THETA-E GRADIENT NICELY...AND INDICATES
THAT THE RIDGE OF THETA-E ALONG AND JUST SOUTH OF THE BOUNDARY
WILL SHIFT SOUTH OVER THE METROPLEX...CONTINUING EAST ALONG THE
I-20 AND I-30 CORRIDORS TO THE EASTERN BOUNDARY OF OUR CWA.
ANYWHERE FROM 08 TO 10Z /3 TO 5 AM/ THE RAP INDICATES THAT THIS
BOUNDARY WILL STALL LEAVING THE THETA-E RIDGE IN PLACE OVER THE
METROPLEX EXTENDING EAST ALONG THE I-20 CORRIDOR. THE HRRR
INDICATES THAT ONCE THIS BOUNDARY STALLS...IT MAY SERVE AS A FOCUS
FOR OVERNIGHT THUNDERSTORM INITIATION. RAW MODEL OUTPUT FROM THE
02Z HRRR SHOWS SCATTERED RAIN SHOWERS AND THUNDERSTORMS DEVELOPING
FROM THE DALLAS/TARRANT COUNTY BORDER EASTWARD DOWN THE INTERSTATE
20 CORRIDOR FROM 08 TO 10Z. GRANTED...NOT ALL MODEL OUTPUT
SUPPORTS THIS SOLUTION...BUT SINCE THE BOUNDARY IS EASY TO TRACK
NOW AND IT IS MOVING SOUTH WITH HIGH THETA-E AIR OUT AHEAD OF
IT...WENT AHEAD AND FOLLOWED THIS GUIDANCE FOR THE FORECAST
UPDATE.
NO SEVERE WEATHER IS EXPECTED IF STORMS DEVELOP LATE TONIGHT/EARLY
TOMORROW MORNING...HOWEVER ANY STORM MAY PRODUCE LOCALLY HEAVY
RAINFALL AND STRONG OUTFLOW WINDS UPON COLLAPSING. THERE IS STILL
VERY LITTLE DEEP LAYER SHEAR...SO SINGLE CELL/PULSE TYPE
THUNDERSTORMS WOULD BE THE DOMINANT STORM MODE IF ANYTHING MANAGES
TO DEVELOP. THE BOUNDARY LOOKS TO WASH OUT AFTER SUNRISE...SO ANY
LINGERING THUNDERSTORM ACTIVITY SHOULD FOLLOW SUIT.
CAVANAUGH
&&
.AVIATION...
/00Z TAFS/
VFR CONDITIONS PREVAIL ACROSS MOST OF NORTH TEXAS OUTSIDE OF
SCATTERED THUNDERSTORMS. EARLY EVENING SATELLITE IMAGERY SHOWS AN
AREA OF CU SOUTH OF WACO AND ANOTHER AREA ALONG THE RED RIVER AND
NORTHEAST OF THE METROPLEX. THESE ARE WHERE SCATTERED
THUNDERSTORMS ARE ONGOING AND SHOULD CONTINUE FOR THE NEXT COUPLE
OF HOURS. THE MAJOR AIRPORTS APPEAR TO BE UNDER THE INFLUENCE OF
WEAK SUBSIDENCE AT THE MOMENT AND WITH LOSS OF DAYTIME HEATING
RAPIDLY APPROACHING...THINK WIDESPREAD ADDITIONAL DEVELOPMENT
APPEARS UNLIKELY. WILL MAINTAIN VFR CONDS THROUGH THE PERIOD WITH
WINDS BECOMING NORTHERLY OVER THE NEXT FEW HOURS. VFR CONDS
EXPECTED ON TUESDAY.
DUNN
&&
.PREV DISCUSSION... /ISSUED 332 PM CDT MON SEP 2 2013/
A WEAK COLD FRONT WILL EASE THROUGH THE REGION TONIGHT THROUGH
TUESDAY AND BRING ONLY SLIGHTLY COOLER AND DRIER AIR. ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP AHEAD
OF THE COLD FRONT TONIGHT AND AFFECT MAINLY THE SOUTHERN ZONES.
ANY STORMS THAT DEVELOP TONIGHT WILL BE AIDED BY LARGE SCALE LIFT
FROM DIFFLUENT NORTHERLY FLOW ALOFT. A FEW STRONG TO SEVERE STORMS
ARE POSSIBLE WITH A THREAT OF DAMAGING DOWNBURST WINDS. A FEW
STORMS MAY LINGER IN THE EXTREME SOUTHERN ZONES ON TUESDAY ALONG
AND AHEAD OF THE WEAK COLD FRONT.
UPPER LEVEL HIGH PRESSURE WILL BUILD BACK OVER THE STATE THE
MIDDLE OF THE WEEK THROUGH THE WEEKEND AND RESULT IN A RETURN OF
HOT DAYS...WARM NIGHTS AND LITTLE CHANCE FOR RAIN. EXPECT
AFTERNOON HIGHS FROM THE MIDDLE 90S TO AROUND 100 EACH DAY WITH
OVERNIGHT LOWS GENERALLY IN THE 70S.
LOOKING BEYOND THIS FORECAST CYCLE...BOTH THE GFS AND ECMWF SHOW
THE UPPER RIDGE BREAKING DOWN BY THE MIDDLE OF NEXT WEEK WITH A
SUBSTANTIAL COLD FRONT MOVING THROUGH THE NORTHERN AND CENTRAL
PLAINS. THE SECOND TO THIRD WEEK OF SEPTEMBER IS TYPICALLY WHEN WE
SEE THE FIRST DECENT COLD FRONT...SO THESE SOLUTIONS MAY NOT BE
TOO FAR OFF.
79
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 73 98 74 100 77 / 20 5 5 5 5
WACO, TX 74 97 73 99 75 / 20 10 10 10 10
PARIS, TX 68 96 69 95 70 / 20 5 5 5 5
DENTON, TX 67 97 70 99 72 / 20 5 5 5 5
MCKINNEY, TX 67 96 68 98 70 / 20 5 5 5 5
DALLAS, TX 74 97 76 100 77 / 20 5 5 5 5
TERRELL, TX 71 97 72 97 74 / 20 5 5 5 5
CORSICANA, TX 73 96 73 98 74 / 20 10 10 10 10
TEMPLE, TX 72 98 72 99 74 / 30 20 10 10 10
MINERAL WELLS, TX 67 97 71 98 74 / 10 5 5 5 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/
AREA FORECAST DISCUSSION
NWS SPOKANE WA
449 PM PDT Wed Sep 4 2013
.SYNOPSIS...
Showers and thunderstorms will increase over the Inland Northwest
tonight into Thursday as a Pacific low pressure system approaches
the region. Some storms could be severe especially on Thursday.
Heavy rainfall will also be a concern especially for burn scar
areas along the East Slopes of the Cascades. The low pressure
system will move across the region on Friday and through the
weekend, resulting in much cooler temperatures with continued
showers and a chance for mountain thunderstorms. A significant
drying and warming trend is expected after Monday through much of
the upcoming week.
&&
.DISCUSSION...
Tonight: The moist southerly flow will continue over the Inland
Northwest. Afternoon and early evening convection will be limited
to the higher terrain of the northern mountains and the Blue
mountains where we can expect the surface based convection to
develop. Not much in a way of a trigger to fire off the
convection, despite our building low level instability. The GFS
and NAM are having issues on grasping the small scale features to
ignite the convection, and the HRRR seems to indicate not much
will happen during the time of peak heating. The high resolution
NAM does show nocturnal convection tracking north from Oregon and
reaching area late tonight and have adjusted my pops and weather
to that idea. Overnight lows will remain mild as low level
moisture and dewpoints continue to increase. /rfox.
VERY WET AND STORMY WEATHER PATTERN THROUGH THE END OF THE WORK
WEEK WITH HEAVY, STRONG OUTFLOW WINDS AND HAIL A CONCERN WITH
THUNDERSTORMS
Thursday through Friday night: A deep upper level low pressure
system spinning off the Pac NW coastline will slowly begin to push
into the region. As this system does so, multiple waves of energy
will pivot around with widespread rain showers and thunderstorms
expected. Rain showers with some embedded thunderstorms will be
lingering across the region through Thursday afternoon, mainly
across the northern portions of the forecast area. Looks like we
should see a short break in the storms across the basin in the
afternoon. This is expected to result in some sun breaks across
the basin, which will further destabilize the atmosphere before
the strongest impulse of energy will pivot across OR and into WA
by the evening hours. Models are showing strong upper level
dynamics with this next wave and steep mid level lapse rates of
roughly 7.5 C/KM. Pwats will continue to increase to up over 1.4
inches, which is 200% plus of normal. The 4km NAM simulated radar
reflectivity continues to show a convective system that rapidly
forms in southern WA and expands northward through the evening.
Sounding profiles across the region would support the possibility
for some large hail and strong winds with the thunderstorms that
develop Thursday evening.
A second impulse is expected to move into the region relatively
quickly behind the one for Thursday night pushing in Friday
morning into Friday afternoon. This will result in little relief
of the soaking rain across the region, especially for the northern
mountains and in the Cascades. This second impulse will not see as
strong stability profiles for severe thunderstorms. However, we
will remain in a very moist atmosphere with convective showers and
thunderstorms expected to bring continued heavy rainfall. 36 hour
rainfall totals from Thursday afternoon into Friday evening are
expected to be up around 1-2 inches possible for the northern
mountains over into the Cascades with some locally higher amounts
where multiple thunderstorms pass through. With the barrage of
heavy rainfall possible in the northern mountains over to the
Cascades and onto Waterville Plateau, we decided that we will
expand the Flash Flood Watch to cover all these areas. Recent 2012
and 2013 burn scar will be most susceptible to flash flooding, but
rainfall rates will be high enough for other non burned scared
areas as well; this will be especially so in steeper terrain. Mud
slides and debris flows will also be possible with this event.
Temperatures will trend much colder Thursday into Friday as the
cold upper level low pressure system nudges over the region.
High temperatures on Friday will be 10 to 15 degrees below normal.
/SVH
Saturday through Sunday night...Cooler and unsettled weather will
prevail across the Inland Northwest for the weekend as an upper
level low drifts over the region. Southwest flow around the eastern
flank of the low will place the focus for showers over the eastern half
of the forecast area. Pwats will continue to be in the range of 125
to 175 percent of normal. This deep moisture fetch will bring
wetting rains to much of the forecast area, but especially to the
northeast mountains of WA and the northern panhandle of Idaho. The
main forcing mechanism will come from upper level dynamics in the
base of the trough along with orographics. Models have some weak
surface based instability during the afternoon and evening hours but
this will depend on whether there are any breaks in the overcast. By
Sunday the GFS shows much less areal coverage of showers as it has
the upper low moving east to northwest Montana, placing more stable
air over eastern WA and mainly upslope flow driving the showers in
north ID. The ECMWF is slower moving the low to the east so some
residual showers remain in the forecast for Sunday night, mainly for
the panhandle mountains.
Daytime temperatures will be on the cool side, with most valley
locations in the 70s Saturday, then warming from west to east
Sunday. Overnight low will be mild, due to precipitation and cloud
cover. As the low moves east, more stable northerly flow could allow
for some fog development across the northeast valleys. /Kelch
Monday afternoon through Wednesday night...If the extended models
hold true to their latest solutions, the wet storm system that
will have lingered over the Inland Northwest will have exited the
region. Another ridge looks to rebound once again, although the
exact strength and location is a little more up in the air. While
this will promote a warming and drying trend, the upcoming
rainfall event may tend to keep temperatures from getting too out
of hand during each afternoon. The moist ground will also combine
with afternoon heating for scattered clouds, which would also act
to keep the region from reaching its full afternoon high
potential. Obviously areas that don`t receive as much rainfall
will have a better chance to dry out quicker, and the temperatures
will be higher. But overall, the main change to this portion of
the forecast was to shave off a few degrees from the high
temperatures each day, but keeping with the warm-up through
Wednesday.
Fog may also become an issue each night, at least over the
northern valleys, but possibly reaching further south as well.
While this isn`t included in the wording of the forecast, it is
something that we can fine tune after this weeks rain event. ty
&&
.AVIATION...
00Z TAFS: Moist and unstable southerly flow will continues over
the region. The air mass is moist and unstable enough to generate
random showers and thunderstorms with any minor disturbance
transiting the region. Models are doing a poor job of depicting
these sub-synoptic features. In general expect a few
thunderstorms mainly over mountains ringing the basin through 03Z
tonight...then a relatively quiet overnight period at all TAF
sites until 09Z-18Z when the approaching upper level low will
hurl a stronger and more well defined...and presumably more
confidently forecast...disturbance from south to north through the
forecast area. This will likely create a significant risk of
thunderstorms just about anywhere in the forecast
area...including all TAF sites...through the day Thursday.
Thunderstorms in the afternoon will be strong and organized. VFR
conditions expected at all TAF sites outside of thunderstorm
cores. /MJF
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 65 78 56 64 54 70 / 60 80 100 70 40 40
Coeur d`Alene 62 79 57 65 54 70 / 60 80 90 70 40 50
Pullman 62 78 55 66 48 72 / 60 80 90 50 20 20
Lewiston 68 84 61 73 59 80 / 60 80 80 40 20 10
Colville 59 80 58 66 51 74 / 60 80 100 80 70 50
Sandpoint 59 79 56 65 49 69 / 60 80 90 80 50 50
Kellogg 59 79 54 65 51 71 / 60 80 90 70 50 50
Moses Lake 65 80 58 69 54 76 / 70 80 90 60 30 10
Wenatchee 65 75 59 68 56 74 / 70 90 90 70 50 10
Omak 64 78 59 67 55 76 / 60 80 90 90 70 30
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Flash Flood Watch from late tonight through Friday afternoon for
Northern Panhandle.
WA...Flash Flood Watch from late tonight through Friday afternoon for
Northeast Mountains.
Flash Flood Watch from 2 AM PDT Thursday through Friday
afternoon for East Slopes Northern Cascades-Okanogan
Highlands-Okanogan Valley-Waterville Plateau-Wenatchee Area.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1139 AM PDT Tue Sep 3 2013
.SYNOPSIS...
Showers and thunderstorms will persist over the Inland Northwest
today and Wednesday. Some storms could be severe. A large area of
low pressure will move over the region for the end of the week,
leading to the potential for widespread heavy rain on Thursday and
continuing through Saturday. A drying and warming trend is
expected by the beginning of next week
&&
.DISCUSSION...
Updated the forecast for the rest of today to refine the
thunderstorm threat, touch up the sky cover and adjust our high
temperatures a bit. The leading edge of the shortwave trough of
lower pressure is just now beginning to wrap around into extreme
eastern WA. This wave is anticipated to push across the ID
Panhandle through the early afternoon hours. The main focus of
showers with this wave is across northeastern OR and beginning to
push into the Northeast Blue Mtns, L-C Valley and Camas Prairie.
This is the area where models are showing the best mid level
instability and where the best chances for scattered
thunderstorms will be through the early afternoon ahead of the
disturbance.
Satellite imagery is showing ample amounts of sunshine behind the
disturbance as some drier air loft filters in across the region.
Dew point temperatures will remain in the upper 50s through this
afternoon. Although the NAM looks to be overdoing dew point
temperatures a little bit, I do think we will see the potential
for uncapped surface based CAPEs between 500-1000 J/KG over parts
of the region this afternoon. Best chances for achieving our
convective temperature will be where clouds have cleared out
already and where clouds will clear out by the early afternoon
along the western edge of the shortwave disturbance. Convection
will begin over the higher terrain from the Cascades to the
Northeast Mountains and eventually over the Northeast Blue
Mountains. Surface based convection will be less likely over the
basin, but not out of the question. The HRRR has been consistent
with the best potential for stronger cells to develop over the
Northeast Blue Mountains and then drift northeastward into the L-C
Valley and over onto the southern Palouse. This will be the area
where we may see some stronger thunderstorms and I went ahead and
added heavy rain, gusty winds and small hail in the forecast for
the late afternoon hours.
Temperatures were bumped up a few degrees generally across extreme
eastern WA and into the ID Panhandle as clouds look as if they will
clear out a bit quicker than previously forecast. /SVH
&&
.AVIATION...
18Z TAFS: Scattered showers and thunderstorms are expected mainly
over the higher terrain today. A line of thunderstorms moving out
of northeast OR may impact KLWS through 20Z as a shortwave
disturbances moves across the area. This disturbance is
responsible for the cloud cover expanding across extreme eastern
WA and into the ID Panhandle. Surface based convection is expected
to fire up across the higher terrain this afternoon behind this
band as it shifts eastward. All taf sites (aside from KMWH) will
be at risk of seeing one of these thunderstorms this afternoon,
but best chances will be at KPUW and KLWS. Some storms may become
strong with gusty winds and small hail a possibility. /SVH
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 84 62 88 64 72 55 / 20 20 50 70 90 80
Coeur d`Alene 83 60 87 61 73 55 / 30 20 60 60 90 90
Pullman 84 59 88 62 70 54 / 60 20 50 60 90 60
Lewiston 88 65 93 68 76 60 / 60 20 50 60 90 70
Colville 88 55 91 59 74 57 / 50 30 60 60 100 100
Sandpoint 82 53 86 59 76 55 / 50 20 50 60 100 90
Kellogg 80 59 85 59 73 53 / 60 40 60 50 100 90
Moses Lake 87 59 89 65 72 57 / 10 10 30 80 90 80
Wenatchee 83 63 85 65 70 58 / 30 20 40 80 90 90
Omak 88 59 87 63 71 58 / 30 20 70 70 100 100
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
614 AM PDT Tue Sep 3 2013
.SYNOPSIS...
Showers and thunderstorms will persist over the Inland Northwest
today and Wednesday. Some storms could be severe. A large area of
low pressure will move over the region for the end of the week,
leading to the potential for widespread heavy rain on Thursday and
continuing through Saturday. A drying and warming trend is
expected by the beginning of next week
&&
.DISCUSSION...
The forecast for today has been updated mainly for this morning
based on current satellite and radar trends. Despite favorable mid
level instability for convective development...lack of large scale
forcing has kept most of the Inland Northwest dry as of 6 am.
Latest HRRR and 06z 4km NAM shows the bulk of the showers this
morning from the Blues into the Central Panhandle Mountains, and
near the Cascades. Latest trends support this so POPs were lowered
for the morning for most areas along with the remove of
thunderstorms during the morning all areas except in and near the
Cascades. JW
&&
.AVIATION...
12Z TAFS: Moist southerly flow ahead of an upper level low
pressure off the coast will continue to promote mid level and high
level ceilings across the forecast area through the next 24 hours. A
wave rounding the base of the upper low will trigger scattered
showers and isolated thunderstorms today. Thunderstorms will mainly
occur after 18Z after the air mass becomes increasingly unstable
from surface based heating leading. VFR conditions are expected at
all TAF sites outside of thunderstorm cores. Some drying aloft
moves in between 0-6z Wednesday which combined with loss of daytime
heating should result in showers/thunderstorms quickly diminishing.
However another wave approaches late tonight with main threat for
additional convection holding off til after 12z Wednesday. JW
&&
.PREV DISCUSSION... /ISSUED 501 AM PDT Tue Sep 3 2013/
..Strong to locally severe thunderstorms possible this afternoon
and again Wednesday afternoon...
..Heavy rainfall expected Thursday...
Today through Wednesday...Large closed low near 130W will remain
in place through Wednesday afternoon. This will result in a moist
and unstable southerly flow with scattered showers and
thunderstorms. Precipitable water values of 150-225 percent of
normal will support wet storms producing locally heavy rain. Storm
motions however of around 15-20 mph should limit the threat for
flash flooding through Wednesday although if any training cells
develop this could heighten the risk.
For today a short wave moving into western Oregon early this
morning will move north into the Washington Cascades by
afternoon...exiting into British Columbia during the afternoon.
Increased lift with this wave will lead to an increase in showers
across Central Washington this morning especially the Cascades.
Meanwhile monsoonal moisture will continue to work its way up into
Eastern Washington and North Idaho this morning which combined
with weak lift from the wave tracking to the west will lead to an
increase in showers as well. Meanwhile mid level instability could
trigger a few thunderstorms over the region this morning with the
best chances in the Cascades given stronger lift. Then for the
afternoon abundant low level moisture and some sun breaks should
allow for the atmosphere to destabilize further with GFS showing
uncapped CAPE values of 300-800 J/KG and the NAM 600-1200 J/KG.
This combined with 0-6km wind shear values of 30-50 knots (highest
near the Cascades) may lead to strong to locally severe storms
especially if the higher NAM CAPE values pan out. A combination of
drier air aloft and loss of day time heating should result in
convection quickly diminishing this evening.
Then late tonight into Wednesday another wave moves up from the
south bringing another round of convection. Confidence is low at
this time regarding areas with best instability with big
differences between the GFS and NAM especially over North Idaho.
However ECMWF and GFS show the best chances for thunderstorms in
the Cascades given closer proximity to low off the coast with good
upper level diffluence in this area. Shear values will again be
supportive for strong to locally severe storms. JW
Wednesday evening through next Tuesday...Through this portion of
the forecast period model guidance is similar showing a deep
closed low tracking from off the Oregon coast north along the
Cascades and then east across eastern WA on Sunday. While there
are some timing issues the models all indicate a very active and
very wet pattern through the weekend. By Monday and Tuesday the
upper low will eject east of the Rockies with high pressure
building in the eastern Pacific.
A moist and very unstable air mass will be over the Pac NW
Wednesday evening and any convection from Wednesday afternoon will
continue through at least the early evening hours.
Thursday through Friday will be the most active period as the
front tracks trough the region. The front is expected to move
north off the Oregon Cascades early Thursday morning and finally
eject east and out of the area Friday morning. The front will act
as a strong lifting mechanism and combine with upper level support
from the passing jet. Abundant Pacific moisture will be available
as southerly flow will increase PWATs to around 1.50 inches,
which is above 200 percent of normal. In addition the atmosphere
will become increasingly unstable. This convective nature will
result in showers and embedded thunderstorms with the potential of
widespread very heavy rain along the front as it moves through the
region. WPC has indicated the possibility of outing the area in an
excessive rainfall area from 12z Thursday- 12z Friday. As we get
nearer to this event there will most likely be flash flood watches
across the area. High cape values and decent 0-6km shear hints at
the possibility of some storms becoming better organized then what
we normally see in early September for the chance of strong
outflow winds and large hail.
Late Friday behind the front there should be drying from the
southwest. Saturday and Sunday the cold core will track across the
Inland Northwest. This will keep the atmosphere very unstable and
with lingering moisture we can expect showers and embedded
thunderstorms just about anywhere east of the Cascades.
By early Monday the upper level low will have ejected east of the
divide and high pressure will begin to build in the eastern Pacific.
This will result in a drier northwest flow. Afternoon heating and
up-sloping flow will support some chances of showers across the
Idaho Panhandle mountains...otherwise the forecast will be dry.
Temperatures below normal through Saturday will begin to rebound
Sunday with temperatures rising to a few degrees above normal by
Monday and Tuesday. /Tobin
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 80 62 88 64 74 56 / 40 20 50 50 80 80
Coeur d`Alene 79 60 87 61 74 55 / 50 20 60 40 80 90
Pullman 80 59 88 62 75 51 / 50 20 50 50 80 70
Lewiston 86 65 93 68 82 60 / 60 20 50 40 80 60
Colville 84 55 91 59 79 55 / 50 30 60 60 90 90
Sandpoint 76 53 86 59 74 54 / 70 20 50 40 80 100
Kellogg 76 59 85 59 75 53 / 70 40 60 30 80 90
Moses Lake 87 59 89 65 76 56 / 20 10 30 60 90 50
Wenatchee 84 63 85 65 74 59 / 40 20 40 70 90 60
Omak 84 59 87 63 78 58 / 60 20 70 70 90 90
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
631 PM CDT WED SEP 4 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 337 PM CDT WED SEP 4 2013
MAIN FORECAST CONCERNS IN THE SHORT TERM ARE ON TEMPERATURES AND
CLOUD COVER TONIGHT INTO THURSDAY MORNING.
LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED RIDGING
ACROSS ANCHORED OVER THE ROCKIES. TWO UPPER LOWS NOTED...ONE
CENTERED OVER THE EASTERN SHORE OF HUDSON BAY...AND THE OTHER WAS
JUST EDGING INTO THE PACIFIC NORTHWEST. A WEAK COLD FRONT
STRETCHED FROM CENTRAL MINNESOTA ACROSS CENTRAL WISCONSIN EAST
THROUGH NORTHERN LOWER MICHIGAN AND WAS SLOWLY DRIFTING SOUTH.
THERE HAS NOT BEEN ANY PRECIPITATION ASSOCIATED WITH THE FRONT
JUST A SLIGHT INCREASE IN CLOUD COVER.
SURFACE HIGH PRESSURE WILL BUILD INTO THE FORECAST AREA TONIGHT AS
THE COLD FRONT SLIDES SOUTH INTO CENTRAL IOWA AND SOUTHERN ILLINOIS.
THE STRATUS CURRENTLY OVER NORTHERN WISCONSIN...SLIPS SOUTHWEST
TONIGHT. LINGERING MOISTURE CENTERED AROUND 850 MB...WITH AN
ADDITIONAL POCKET LOCATED IN THE 700-450 MB LAYER...MAY BE ENOUGH TO
GENERATE SOME CLOUD COVER TONIGHT OVER NORTHEAST IOWA....SOUTHEAST
MINNESOTA...AND SOUTHWEST WISCONSIN. FORECAST SOUNDINGS SUGGEST THE
LOWER LEVEL MOISTURE WILL DRY OUT AS THE HIGH BUILDS IN. IF THE
CLOUD COVER LINGERS IT WILL HAVE AN IMPACT ON FOG POTENTIAL AND
TEMPERATURES OVERNIGHT. PLAN ON PARTLY CLOUDY TO MOSTLY CLEAR SKIES
TONIGHT WITH LOW TEMPERATURES RANGING FROM THE UPPER 30S TO LOWER 40S
OVER NORTHERN WISCONSIN TO THE MID TO UPPER 50S ACROSS NORTHEAST
IOWA.
HIGH PRESSURE WILL BE IN CONTROL ACROSS THE REGION ON THURSDAY
PROVIDING DRY AND QUIET WEATHER. THE MAIN CONCERN WILL BE ON
AFTERNOON DEWPOINTS...ESPECIALLY CLOSER TO THE CENTER OF THE HIGH
OVER CENTRAL INTO NORTH CENTRAL WISCONSIN. FORECAST SOUNDINGS SHOW
DRY AIR ALOFT WITH DEEP MIXING TO NEARLY 875 MB. LOOKING UPSTREAM
ACROSS UPPER MICHIGAN AND SOUTHERN ONTARIO...DEWPOINTS ARE ONLY IN
THE UPPER 30S TO LOWER 40S AND THIS AIR IS ADVECTING SOUTHWARD. HAVE
LOWERED AFTERNOON DEWPOINTS INTO THE LOWER 40S OVER WEST CENTRAL
THROUGH CENTRAL WISCONSIN WHERE DEEP MIXING SHOULD EASILY YIELD THESE
AFTERNOON VALUES. THIS WOULD PRODUCE RELATIVE HUMIDITY VALUES IN
THE 27 TO 30 PERCENT RANGE. THERE WILL NOT BE MUCH WIND UNDER THE
HIGH WITH WIND MAINLY LIGHT AND VARIABLE AT 5 MPH OR LESS OVER THESE
AREA. OTHERWISE...PLAN ON SKIES RANGING FROM PARTLY TO MOSTLY CLOUDY
OVER SOUTHEAST MINNESOTA INTO NORTHEAST IOWA...TO MOSTLY SUNNY OVER
NORTH CENTRAL WISCONSIN. A WEAK SHORTWAVE LOOKS TO MOVE ACROSS AREAS
ALONG AND WEST OF THE MISSISSIPPI RIVER WITH THE MAIN IMPACT BEING
AN INCREASE IN CLOUD COVER.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 337 PM CDT WED SEP 4 2013
THE HIGH WILL SLIDE EAST INTO THE EASTERN GREAT LAKES THURSDAY NIGHT
INTO FRIDAY. A COLD FRONT IS EXPECTED TO PUSH INTO NORTHWEST
MINNESOTA AND EASTERN SOUTH DAKOTA BY FRIDAY AFTERNOON. SOUTHERLY
FLOW WILL INCREASE ACROSS THE AREA ON FRIDAY AS THE FRONT APPROACHES
HELPING TO USHER IN A WARMER AND SLIGHTLY MORE HUMID AIRMASS. 925 MB
TEMPERATURES WARM TO AROUND 25 ACROSS WESTERN AND CENTRAL WISCONSIN
AND TO THE UPPER 20S ACROSS PORTIONS OF NORTHEAST IOWA AND SOUTHEAST
MINNESOTA. HIGH TEMPERATURES ARE EXPECTED TO WARM INTO THE MID
80S...WITH A FEW UPPER 80S POSSIBLE ALONG THE MISSISSIPPI RIVER
VALLEY AND CLOSER TO THE INTERSTATE 35 CORRIDOR. FORECAST MODELS ARE
ADVERTISING A WEAK SHORTWAVE MOVING ACROSS THE EASTERN DAKOTAS AND
PUSHING INTO THE UPPER MISSISSIPPI RIVER VALLEY LATE THURSDAY NIGHT
INTO EARLY FRIDAY MORNING. 850 MB MOISTURE TRANSPORT IS WEAK AND
FOCUSED INTO SOUTHWEST MINNESOTA AND WESTERN IOWA THURSDAY EVENING
THEN ATTEMPTS TO SHIFT EAST INTO THE AREA EARLY FRIDAY MORNING.
THERE ISN/T MUCH UPPER LEVEL SUPPORT FOR PRECIPITATION SO DECIDED TO
MAINTAIN A DRY FORECAST DURING THIS TIMEFRAME. THE FRONT IS EXPECTED
TO PUSH SOUTHEAST FRIDAY NIGHT INTO SATURDAY POSSIBLY INTERACTING
WITH WEAK UPPER LEVEL IMPULSES IN NORTHWEST FLOW ALOFT. THIS WILL
BRING SLIGHT CHANCES FOR SHOWERS AND STORMS TO THE FORECAST AREA
FRIDAY NIGHT INTO SATURDAY. THE PACIFIC NORTHWEST TROUGH FINALLY
MOVES EAST ACROSS THE NORTHERN PLAINS SUNDAY NIGHT THROUGH MONDAY
NIGHT BREAKING DOWN THE PERSISTENT RIDGING OVER THE UPPER MIDWEST.
THIS WILL BRING CHANCES FOR SHOWERS AND STORMS TO THE FORECAST
AREA...ESPECIALLY SUNDAY NIGHT INTO MONDAY NIGHT. WARM SOUTHERLY
FLOW WILL CONTINUE INTO EARLY NEXT WEEK. HIGHS WILL REMAIN WELL
ABOVE NORMAL THROUGH THE WEEKEND WITH SATURDAY LOOKING TO BE THE
WARMEST DAY WITH HIGHS IN THE MID TO UPPER 80S. THE WARM
TEMPERATURES WILL CONTINUE THROUGH THE MIDDLE OF NEXT WEEK.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 631 PM CDT WED SEP 4 2013
THE MAIN QUESTION FOR THE OVERNIGHT PERIOD IS WITH WHETHER ANY LOW
STRATUS WILL FORM ALONG THE NORTHERN SIDE OF A COLD FRONT THAT HAS
DROPPED THROUGH THE REGION. THERE CURRENTLY IS NOT A WHOLE LOT OF
LOW CLOUDS OUT THERE...WITH THE MAIN BAND CLOSE TO DETROIT AND
EXTENDING TO THE WEST TOWARD SOUTHERN LAKE MICHIGAN...BUT THAT IS
IT. SOME OF THE PREVIOUS FORECAST MODELS WERE SHOWING THAT THIS
STRATUS WILL BUILD WESTWARD OVERNIGHT...THOUGH SOME OF THE LATEST
RAP FORECASTS HAVE SHOWN THE HIGHER RH STAYING TO THE SOUTH OF THE
TAF SITES INTO TOMORROW MORNING. WILL KEEP THE STRATUS IN THE
TAFS AND CONTINUE TO EVALUATE THE POTENTIAL THIS EVENING.
OTHERWISE...WINDS WILL SHIFT AROUND TO THE SOUTHEAST TOMORROW AS
THE FRONT SAGS TO THE SOUTH AND A RIDGE OF HIGH PRESSURE DROPS
DOWN ACROSS WISCONSIN.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
239 PM CDT TUE SEP 3 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 239 PM CDT TUE SEP 3 2013
..CURRENTLY AS OF 19Z..
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED AN UPPER LOW
JUST OFF THE PACIFIC NORTHWEST COAST...SUBTROPICAL RIDGING FROM
COLORADO INTO ALBERTA...AND TROUGHING FROM HUDSON BAY DOWN ALONG THE
EAST COAST OF THE U.S.. WITHIN THIS TROUGHING...THE MAIN FEATURE OF
NOTE IS A POTENT SHORTWAVE DROPPING THROUGH NORTHERN MANITOBA AND
ONTARIO...WHICH IS REFLECTED AT THE SURFACE BY A COLD FRONT THAT IS
APPROACHING FAR NORTHWEST MN. HIGH PRESSURE AND DRY AIR DOMINATE THE
FORECAST AREA. THE DRY AIR IS REFLECTED WELL ON THE 12Z SOUNDINGS
FROM MPX...GRB AND DVN WITH PRECIPITABLE WATER VALUES AROUND 0.68
INCHES OR 80 PERCENT OF NORMAL. SOME MID AND HIGH CLOUDS HAVE BEEN
SPREADING INTO THE AREA FROM THE DAKOTAS AND MINNESOTA...ASSOCIATED
WITH SOME WEAK 850MB MOISTURE TRANSPORT AHEAD OF THE COLD FRONT...AS
WELL AS WEAK 320K ISENTROPIC LIFT. THE MID AND HIGH CLOUDS ALSO
REFLECT SEPARATION OF WARMTH ACROSS THE UPPER MIDWEST. 12Z SOUNDINGS
FROM BIS AND ABR HAD 925MB TEMPS AROUND 20C...WHEREAS GRB...DVN AND
MPX WERE AROUND 12C.
..HAZARDS..
NONE.
..SYNOPTIC OVERVIEW..
03.12Z MODEL GUIDANCE REMAINS CONSISTENT IN DEVELOPING AN
ANOMALOUSLY DEEP TROUGH OVER THE HUDSON BAY REGION DURING THE NEXT
24 HOURS. THIS TROUGH HELPS PROPEL THE COLD FRONT CURRENTLY DROPPING
INTO NORTHWEST MN THROUGH THE FORECAST AREA DURING THE DAY
WEDNESDAY. CANADIAN HIGH PRESSURE LOOKS TO BUILD INTO NORTHERN MN
AND UPPER MI BEHIND THE FRONT LATE WEDNESDAY.
..DETAILS..
PLENTIFUL DRY AIR IN THE LOW LEVELS OF THE TROPOSPHERE FOR THE NEXT
24 HOURS...COMBINED WITH CAPPING ADVECTING IN AT 800MB AHEAD OF THE
COLD FRONT DROPPING SOUTH WILL HELP TO KEEP CONDITIONS DRY THROUGH
THE SHORT TERM PERIOD. 03.12Z NAM BMJ CONVECTIVE SCHEME GOES OFF
WEDNESDAY AFTERNOON WEST OF THE MISSISSIPPI RIVER...BUT THINK IT IS
REMOVING THE CAPPING WAY TOO QUICK GIVEN THAT THE 03.12Z GFS DEPICTS
160 J/KG OF CIN AT THE SAME TIME.
ALTHOUGH CONDITIONS ARE EXPECTED TO BE DRY...THERE ARE SOME CLOUD
COVER CONCERNS WHICH TIE INTO TEMPERATURES AND POTENTIAL FOR VALLEY
FOG. INDICATIONS ARE THAT THE CURRENT CIRRUS OVER THE FORECAST AREA
WILL CLEAR THE AREA THIS EVENING. THE NEXT BATCH OF MID/HIGH CLOUDS
UPSTREAM OVER SOUTHERN SASKATCHEWAN AND NORTHERN NORTH DAKOTA LOOK
TO MOVE INTO THE AREA LATE TONIGHT AND PERSIST THROUGH MUCH OF
TOMORROW. GOOD RADIATIONAL COOLING CONDITIONS EXIST BETWEEN THE TWO
BATCHES OF CLOUDS...WHICH SHOULD ALLOW TEMPS TO BOTTOM OUT INTO THE
UPPER 40S TO MID 50S. THE INCREASE IN CLOUDS LATE TONIGHT ALONG WITH
MODELS INCREASING 950-975MB WINDS AHEAD OF THE FRONT SHOULD KEEP ANY
VALLEY FOG THAT FORMS TO MOSTLY THE MISSISSIPPI RIVER TRIBUTARIES...
THOUGH CANNOT RULE OUT PATCHES OF FOG IN THE MISSISSIPPI RIVER
VALLEY. 925MB TEMPS ON WEDNESDAY ARE PROGGED TO CLIMB TO 19-24C...
COOLEST OVER TAYLOR COUNTY. THESE READINGS COMBINED WITH SUNSHINE
FILTERING THROUGH THE CLOUDS WILL ALLOW HIGHS TO TOP OUT IN THE
UPPER 70S TO MID 80S. A FEW SPOTS MAY EVEN HIT THE UPPER 80S...
DEPENDING ON THE AMOUNT OF SUN...AND MOST LIKELY TO OCCUR IN THE
WISCONSIN RIVER VALLEY.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 239 PM CDT TUE SEP 3 2013
..HAZARDS..
1. HEAT. MODELS ARE HINTING AT A SURGE OF HEAT COMING INTO THE
FORECAST AREA ON SATURDAY. RIGHT NOW IT APPEARS HEAT INDICES WILL
STAY BELOW ADVISORY CRITERIA...THOUGH.
2. STORMS. THERE ARE CHANCES IN THE FORECAST FOR FRIDAY NIGHT AND
BEYOND. IF THERE IS ANY SEVERE POSSIBILITY...IT WOULD COME EARLY
NEXT WEEK...BUT THERE IS STILL PLENTY OF TIME FOR THIS TO CHANGE.
..SYNOPTIC OVERVIEW..
03.12Z ECMWF/GFS/CANADIAN AND ENSEMBLE DATA ALL SUGGEST A SLOW
PROGRESSION EASTWARD OF THE UPPER LEVEL PATTERN DURING THE NEXT 7
DAYS. MUCH OF THIS PROGRESSION HAS TO WAIT UNTIL FRIDAY BECAUSE OF
THE ANOMALOUSLY DEEP TROUGH SET UP OVER THE HUDSON BAY REGION AND
SOUTHEAST CANADA. BY MONDAY...MODELS PROG THAT THE UPPER LOW
CURRENTLY OFF THE PACIFIC NORTHWEST COAST WILL HAVE SLID INLAND INTO
MONTANA...WHILE THE RIDGE AXIS AHEAD OF IT OVER ALBERTA MOVES EAST
TO OVER THE FORECAST AREA. THEN FOR TUESDAY...INDICATIONS ARE THAT
TROUGHING WILL BE CROSSING MANITOBA...SENDING A COLD FRONT TOWARDS
THE AREA. THE CHANGE IN THE UPPER LEVEL PATTERN MEANS THAT BY THE
WEEKEND...WARM AIR ADVECTION WILL BE IN FORCE...BRINGING CONCERNS OF
CAPPING...PRECIPITATION AND POSSIBLY MUGGY CONDITIONS AGAIN.
..DETAILS..
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...DRY CONDITIONS WILL
DOMINATE THIS PERIOD WITH SUBSIDENCE AND DRY AIR IN PLACE...ALONG
WITH HIGH PRESSURE TRACKING SOUTHEAST ACROSS THE WESTERN GREAT LAKES
REGION. SKIES SHOULD CLEAR OUT NORTH TO SOUTH WEDNESDAY NIGHT AS THE
UPPER FLOW TURNS A BIT MORE NORTHERLY...FOLLOWED BY FULL SUN ON
THURSDAY AND SOME INCREASE IN WARM ADVECTION MID/HIGH CLOUDS LATE
THURSDAY NIGHT. VALLEY FOG CONCERNS...AT LEAST IN THE MISSISSIPPI
RIVER...SHOULD BE MINIMIZED BY POTENTIAL ISSUES WITH CLOUDS AND AN
EASTERLY BREEZE RIGHT ABOVE THE SURFACE. LOWS WILL ALSO BE ON THE
COOL SIDE...ESPECIALLY IN WISCONSIN WHERE THE HIGH TRACKS ACROSS.
HIGHS ON THURSDAY SHOULD BE A LITTLE COOLER THAN WEDNESDAY DUE TO
925MB TEMPS TOPPING OUT BETWEEN 18-22C.
FRIDAY THROUGH TUESDAY...FOCUS IS ON THE WARM ADVECTION PATTERN THAT
DEVELOPS.
1. TEMPERATURES...850MB ANOMALIES ARE PROGGED BETWEEN 0.5-1 ABOVE ON
FRIDAY AND SUNDAY...AND 1.5-2 ABOVE FOR SATURDAY...MONDAY AND
TUESDAY. THESE WILL KEEP US BELOW RECORDS BUT ABOVE TO WELL ABOVE
NORMAL NONETHELESS. 925MB TEMPS CLIMB TO 22-26C ON FRIDAY...24-29C
ON SATURDAY...COOL TO 18-21C ON SUNDAY AND MONDAY AND CLIMB BACK UP
TO 24-29C ON TUESDAY. THE WARMEST READINGS ARE SUGGESTED OVER
NORTHEAST IOWA. MEANWHILE...THE COOLEST READINGS ARE PROGGED OVER
TAYLOR/CLARK COUNTIES WHICH ARE CLOSER TO A CANADIAN HIGH TRACKING
ACROSS SOUTH CENTRAL CANADA AND THE UPPER GREAT LAKES.
2. MUGGY-NESS...GULF OF MEXICO MOISTURE WILL RETURN BACK INTO THE
REGION BUT ITS GOING TO TAKE SOME TIME DUE TO THE CANADIAN HIGH
MOVING ACROSS ON THURSDAY. ADDITIONALLY...THE DROUGHT CONDITIONS
THAT HAVE DEVELOPED WILL HELP TO MIX OUT THIS MOISTURE. THE BETTER
SHOT FOR MORE MUGGY CONDITIONS LOOKS TO COME THIS THE WEEKEND INTO
EARLY NEXT WEEK AS MOISTURE POOLS ALONG A FRONTAL BOUNDARY PROGGED
TO SET UP NEAR THE FORECAST AREA. EVEN STILL...DEWPOINTS DO NOT
APPEAR AS HIGH AS THEY WERE DURING THE HEAT WAVE LAST WEEK.
3. PRECIPITATION CHANCES...MODELS ARE IN GOOD AGREEMENT HOLDING
FRIDAY DRY. THERE COULD BE SOME ELEVATED CONVECTION ON THE EDGE OF
THE WARM SURGE / CAPPING OVER WISCONSIN FRIDAY NIGHT AND SATURDAY...
AND HAVE 20-30 PERCENT CHANCES FOR THEM. FROM SATURDAY NIGHT
ONWARDS...ALL BETS ARE OFF WITH THE 03.12Z ECMWF/CANADIAN/GFS ALL
SHOWING PERIODS OF PRECIPITATION. VERY HARD TO PIN THESE
DOWN...GIVEN FRONTAL BOUNDARY POSITION UNCERTAINTY. ADDITIONALLY...
THE IMPACT OF THE DROUGHT COULD END UP LIMITING THE AMOUNT OF
PRECIPITATION...PARTICULARLY IN THE DAYTIME. FOR NOW FOLLOWED A
MODEL CONSENSUS OF GENERALLY 20-40 PERCENT CHANCES EVERY 12 HOURS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1259 PM CDT TUE SEP 3 2013
MAIN FORECAST CONCERNS ARE ON VALLEY FOG POTENTIAL AT KLSE. VFR
CONDITIONS ARE EXPECTED AT KRST THROUGH THE FORECAST PERIOD. HIGH
PRESSURE WILL SLIDE SOUTHEAST OF THE REGION TONIGHT AS A WEAK COLD
FRONT SLIDES SOUTH OUT OF NORTH DAKOTA/NORTHERN MINNESOTA. CIRRUS
STREAMING ACROSS THE UPPER MISSISSIPPI RIVER VALLEY THIS AFTERNOON
AND EVENING SHOULD GRADUALLY THIN AND PUSH SOUTH OF THE AREA
GIVING WAY TO MOSTLY CLEAR SKIES. THIS WILL SET THE STAGE FOR
PATCHY VALLEY FOG ALONG THE MISSISSIPPI RIVER VALLEY IMPACTING
KLSE. WINDS JUST ABOVE THE SURFACE THROUGH 1200 FT INCREASE INTO
THE 10 TO 14 KT RANGE WHICH SHOULD INHIBIT DENSE FOG FORMATION AT
KLSE AS THE FRONTAL BOUNDARY SLIPS SOUTH INTO THE AREA. CONDITIONS
LOOK FAVORABLE FOR VALLEY FOG EARLY TONIGHT BUT THEN BECOME LESS
FAVORABLE LATE TONIGHT INTO EARLY WEDNESDAY MORNING AS THE WINDS
ALOFT INCREASE. THINKING PATCHY FOG AND VALLEY STRATUS WILL BE THE
MOST LIKELY OUTCOME AT KLSE TONIGHT. WILL HAVE TO MONITOR WINDS AT
BLUFF TOP TONIGHT VERY CLOSELY. IF THE GRADIENT DOESN/T INCREASE
AS FORECAST...DENSE FOG WOULD RESULT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
325 AM CDT TUE SEP 3 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 325 AM CDT TUE SEP 3 2013
SURFACE HIGH PRESSURE WAS CENTERED OVER THE FORECAST AREA RESULTING
IN CLEAR/CALM/COOL CONDITIONS. TEMPERATURES AT 3 AM RANGED FROM A
VERY CHILLY 38 DEGREES AT BLACK RIVER FALLS AND VOLK FIELD WI...TO
THE 40-50 DEGREE RANGE ELSEWHERE. FOG WAS ALSO NOTED ACROSS THE CRANBERRY
COUNTRY OF CENTRAL WI WITH VISIBILITIES LOCALLY BELOW A MILE.
LOOKING OUT THE OFFICE...FOG/STRATUS WAS ALSO FORMING DOWN IN THE
MISSISSIPPI RIVER CHANNEL. IMMEDIATE CONCERN WILL BE THE EXTENT OF
FOG THIS MORNING UNDER THE RIDGE OF HIGH PRESSURE. WILL MONITOR HERE
OVER THE NEXT HOUR TO SEE IF ANY HEADLINES WILL BE NEEDED. ONCE THE
FOG LIFTS THIS MORNING...LOOKING FOR A SUNNY DAY WITH TEMPERATURES
RIGHT AROUND NORMAL IN THE MIDDLE AND UPPER 70S.
HIGH PRESSURE WILL SLIP SOUTH AND EAST OF THE AREA TONIGHT AS A COLD
FRONT PUSHES SOUTHWARD OUT OF CANADA TO NEAR THE I-90 CORRIDOR BY
SUNRISE. NOT MUCH EXPECTED OUT OF THIS FRONT OTHER THAN SOME
INCREASE IN SOME MID/HIGH CLOUDS. OTHERWISE...LOOK FOR LOWS IN THE
50S...EXCEPT FOR A FEW UPPER 40 READINGS ACROSS THE CRANBERRY BOG
COUNTRY.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 325 AM CDT TUE SEP 3 2013
LOOK FOR THE COLD FRONT TO SLIP SOUTH OF THE AREA ON WEDNESDAY. THE
NAM TRIES TO DEVELOP CONVECTION JUST WEST OF THE AREA DURING THE
AFTERNOON IN RESPONSE TO WEAK ISENTROPIC UPGLIDE IN THE 850-700MB
LAYER OVER THIS FRONTAL BOUNDARY. THE NAM IS THE ONLY MODEL DOING
THIS BUT WARRANTS KEEPING AN EYE ON. WILL LEAVE FORECAST DRY FOR NOW
WITH AT LEAST LIKELY SEE SOME INCREASE IN SOME MID-CLOUD MAINLY
SOUTH OF I-94. OTHERWISE...PLAN ON HIGHS IN THE MID/UPPER 70S ACROSS
NORTH CENTRAL WI...AND LOWER TO MIDDLE 80S ELSEWHERE.
FOR WEDNESDAY NIGHT THROUGH FRIDAY...HIGH PRESSURE WILL REMAIN IN
CONTROL ACROSS THE REGION WITH WARMING TEMPERATURES. LOOK FOR HIGHS
IN THE MIDDLE 70S TO LOWER 80S ON THURSDAY...WARMING INTO THE LOWER
AND MIDDLE 80S ON FRIDAY.
GFS AND ECMWF SHOW A COLD FRONT SLIPPING SOUTHEAST INTO THE
REGION SATURDAY WITH BEST MOISTURE CONVERGENCE/SHOWER AND
THUNDERSTORM CHANCES STAYING MAINLY ACROSS EASTERN WI. A FAIRLY
STRONG CAP LOOKS TO REMAIN IN PLACE OVER US...KEEPING US VERY WARM
AND DRY. DID INCLUDE A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS
OVER THE FAR EASTERN PORTION OF THE FORECAST AREA...ON THE EASTERN
PERIPHERY OF THE STRONGER CAPPING. PLAN ON HIGHS SATURDAY IN THE
MIDDLE AND UPPER 80S.
SHOWER AND THUNDERSTORM CHANCES OVERSPREAD THE AREA SATURDAY NIGHT
THROUGH MONDAY AS THE FRONTAL BOUNDARY STALLS ACROSS THE REGION AND
LOW PRESSURE APPROACHES FROM THE PLAINS. HIGHS ON SUNDAY AND MONDAY
ARE EXPECTED TO BE IN THE MIDDLE 70S TO THE LOWER 80S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT
1140 PM CDT MON SEP 2 2013
NO REAL CHANGES HAVE BEEN PRESENTED BY THE 03.00Z NAM OR 03.03Z
RAP. THE SURFACE HIGH WILL CONTINUE TO DRIFT EAST AND BE OVER THE
AREA FOR THE REMAINDER OF THE NIGHT. SKIES HAVE CLEARED OUT AND
WINDS HAVE BECOME LIGHT UP THROUGH AT LEAST 5 THOUSAND FEET. THE
TEMP/DEW POINT SPREAD AT KLSE WAS DOWN TO 4 DEGREES AT 03Z AND 3
DEGREES AT 04Z...SO THINGS STILL APPEAR TO BE ON TRACK FOR A
VALLEY FOG EVENT WITH DENSE FOG FOR KLSE. THE RAP STILL DOES NOT
WANT TO SATURATE AT KLSE TONIGHT...WHICH STILL LENDS A LITTLE BIT
OF DOUBT TO WHETHER THE FOG WILL FORM OR NOT. THE NAM IS ALSO NOW
SUGGESTING THAT FOG TO FORM AT KRST AS WELL. BUT BASED ON
PERSISTENCE OF WHAT HAPPENED LAST NIGHT WHERE THE FOG ONLY FORMED
UNDER THE HIGH WHERE IT HAD RECENTLY RAINED...WILL NOT INCLUDE ANY
FOG FOR NOW. ONCE THE FOG BURNS OFF...VFR CONDITIONS FOR THE REST
OF THE PERIOD AS THE HIGH SLIDES OFF TO THE EAST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1140 PM CDT MON SEP 2 2013
.SHORT TERM...(TONIGHT THROUGH TUESDAY)
ISSUED AT 245 PM CDT MON SEP 2 2013
THICK BLANKET OF CLOUDS ACROSS WI AND PARTS OF EASTERN MN EARLY THIS
AFTERNOON...ON THE BACKSIDE OF A EASTWARD DEPARTING LOW PRESSURE
SYSTEM. THE LATEST HRRR AND SREF POINT TO SOMEWHAT RAPID
DISSIPATION/EXITING EAST OF THIS CLOUD DECK AS THE AFTERNOON WEARS
ON. MUCH OF THIS WOULD BE DUE TO THE MIXING IN OF DRY AIR AS A SFC
HIGH SLIDES IN FROM THE NORTHERN PLAINS. THAT SAID...SATELLITE STILL
DEPICTS THE ORIGINAL CLOUD SHIELD FAIRLY WELL...MORE A
NORTHWEST-SOUTHEAST RUNNING BAND. RAP13/NAM12 RH FIELDS HANG ONTO TO
SOME OF THIS SATURATION OVER NORTHEAST IA/SOUTHWEST WI THROUGH THE
OVERNIGHT. GOING TO SIDE WITH THE CLEARING TREND...HOLDING ONTO
CLOUDS THE LONGEST IN THE SOUTH. ADD A LIGHT NEAR SFC WIND FIELD
INTO THE MIX AND CLIMATOLOGICALLY FAVORED TIME OF YEAR AND RIVER
VALLEY FOG SHOULD DEVELOP...LIKELY BECOMING DENSE AT SOME LOCATIONS.
MOST OF WHAT DEVELOPS SHOULD BURN OFF BY 9-10 AM. THERE IS SOME
CONCERN THAT FOG COULD FORM OUTSIDE OF THE VALLEYS. THERE WAS SOME
FOG TO THE WEST UNDER THE HIGH EARLY THIS MORNING...BUT SOME OF
THIS WAS IN LOCATIONS THAT HAD RECENT RAINS. WE HAVE BEEN
EXCEEDINGLY DRY...AND DESPITE THE DEVELOPING CLEAR SKIES/LIGHT
WINDS...FOG DEVELOPMENT COULD BE INHIBITED BY THE DRY CONDITIONS.
MAY ADD IN SOME PATCHY FOG AREAWIDE. IF NOT...CONDITIONS WILL HAVE
TO BE MONITORED AND ADJUSTMENTS MADE TO FORECAST IF FOG LOOKS MORE
LIKELY. DON/T FEEL A DENSE FOG ADVISORY IS LIKELY. IF IT WOULD HAVE
RAINED RECENTLY...THAT WOULD BE A DIFFERENT STORY.
HIGH PRESSURE AND A COLD/DRY INFLUX OF AIR WILL GET THE SHORTENED
WORK WEEK OFF TO A CHILLY START. 850 MB TEMP ANOMALIES AROUND -1
TODAY INTO TUE MORNING. WITH PLENTY OF RADIATIONAL COOLING FROM
CLEARING SKIES...LIGHT WINDS...AND THE AFOREMENTIONED COLD AIR
ADVECTING IN...LOWS NEAR 40 ARE LIKELY IN SOME OF THE COLD DRAINAGE
AND LOW LYING AREAS OF CENTRAL/NORTH CENTRAL WI. ELSEWHERE 40S TO
NEAR 50 WILL BE THE RULE...ABOUT 10 TO 15 DEGREES BELOW NORMAL.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 245 PM CDT MON SEP 2 2013
A SURFACE HIGH WILL MEANDER SLOWLY SOUTHEAST ACROSS THE
REGION...WHILE AN UPPER LEVEL RIDGE HOLDS TO THE WEST FOR THE
SHORTENED WORK WEEK. MODELS FAVORING KEEPING ANY PERTURBATIONS ALONG
THE UPPER LEVEL FLOW NORTH/SOUTH OF THE FORECAST AREA...THUS DRY
CONDITIONS WILL CONTINUE.
SOME HOPE FOR RAIN TOWARD THE LATER PART OF THE WEEKEND AND EARLY
NEXT WEEK. THE RIDGE AXIS SHIFTS OVER THE UPPER MISSISSIPPI ON
SUNDAY...WITH AN UPPER LEVEL SHORTWAVE ROLLING ACROSS THE RIDGE TOP
MON/TUE...FLATTENING IT OUT. A SFC WARM FRONT WILL SWEEP AHEAD OF
THE UPPER LEVEL FORCING...WITH THE GFS/EC DEVELOPING PCPN WITH THIS
THERMODYNAMIC LIFT ON SUNDAY. PCPN CHANCES WOULD HANG THROUGH MONDAY
UNTIL THE UPPER LEVEL TROUGH AND ITS ASSOCIATED COLD FRONT MOVE
THROUGH LATER ON TUE. SOME DIFFERENCES IN TIMING ON WHEN THE VARIOUS
FEATURES WOULD MOVE IN...AND THUS ON THE PCPN CHANCES. ALL
SAID...IT LOOKS LIKE THE BEST SHOT FOR WIDESPREAD RAIN FOR THE LOCAL
AREA. WILL SIDE WITH THE CONSENSUS SOLUTION FOR PCPN CHANCES FOR
NOW.
TEMPERATURES WILL BE ON A SLOW RISE THROUGH THE WEEK...WITH A COUPLE
FAIRLY WARM DAYS FOR EARLY SEPT ON FRI/SAT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1140 PM CDT MON SEP 2 2013
NO REAL CHANGES HAVE BEEN PRESENTED BY THE 03.00Z NAM OR 03.03Z
RAP. THE SURFACE HIGH WILL CONTINUE TO DRIFT EAST AND BE OVER THE
AREA FOR THE REMAINDER OF THE NIGHT. SKIES HAVE CLEARED OUT AND
WINDS HAVE BECOME LIGHT UP THROUGH AT LEAST 5 THOUSAND FEET. THE
TEMP/DEW POINT SPREAD AT KLSE WAS DOWN TO 4 DEGREES AT 03Z AND 3
DEGREES AT 04Z...SO THINGS STILL APPEAR TO BE ON TRACK FOR A
VALLEY FOG EVENT WITH DENSE FOG FOR KLSE. THE RAP STILL DOES NOT
WANT TO SATURATE AT KLSE TONIGHT...WHICH STILL LENDS A LITTLE BIT
OF DOUBT TO WHETHER THE FOG WILL FORM OR NOT. THE NAM IS ALSO NOW
SUGGESTING THAT FOG TO FORM AT KRST AS WELL. BUT BASED ON
PERSISTENCE OF WHAT HAPPENED LAST NIGHT WHERE THE FOG ONLY FORMED
UNDER THE HIGH WHERE IT HAD RECENTLY RAINED...WILL NOT INCLUDE ANY
FOG FOR NOW. ONCE THE FOG BURNS OFF...VFR CONDITIONS FOR THE REST
OF THE PERIOD AS THE HIGH SLIDES OFF TO THE EAST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION...04
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1248 AM CDT THU SEP 5 2013
.DISCUSSION...
840 PM CDT
FOR EVENING UPDATE...
MAINLY ONLY MINOR ADJUSTMENTS BASED ON OBS/SATELLITE TRENDS THIS
EVENING.
SURFACE COLD FRONT WAS JUST ENTERING FAR NORTHEASTERN LAKE COUNTY
IL AT 01Z PER SFC OBS AND EXTRAPOLATION OF BOUNDARY THAT WAS
PROMINENT EARLIER IN KMKX REFLECTIVITY DATA. FRONT WILL CONTINUE
TO BACK-DOOR ITS WAY ACROSS NORTHEAST IL THROUGH THE REMAINDER OF
THE EVENING HOURS AND EVENTUALLY PUSHING INTO CENTRAL IL/IN
OVERNIGHT. WHILE COOLER TEMPS WILL SPREAD IN BEHIND THE FRONT...IT
APPEARS THE STRONGER COOLING/DRYING WILL LAG THE FRONT INTO THE
DAY THURSDAY GIVEN MODEST NORTHEAST WINDS OVERNIGHT.
TEMPS/HUMIDITY WILL ACTUALLY BE A LITTLE HIGHER BEHIND THE FRONT
TONIGHT THAN LAST NIGHT.
GOES 11-3.9 MICRON IR IMAGERY DOES INDICATE AREA OF LOW CLOUDS
(1100-1400 FT BASES) DEVELOPING BEHIND THE FRONT FROM EASTERN WI
INTO WESTERN LOWER MICHIGAN AT 01Z...THOUGH 18Z WRF-NAM SOUNDINGS
AND TSECTS APPEAR TO HAVE BACKED OFF A BIT ON THE DEPTH OF MOISTURE
THAT DEVELOPS OVER FAR NORTHERN/NORTHWESTERN IL BEHIND THE FRONT
OVERNIGHT AS WELL AS AREA OF LIGHT PRECIP OVER NORTHWEST IL. 00Z
RAOB ANALYSIS AT 925-850MB LEVELS DOES INDICATE LOW LEVEL THERMAL
RIDGE ALONG IA/MN BORDER REGION THAT MAY CONTINUE TO SUPPORT SOME
ASCENT ABOVE THE LOW LEVEL FRONTAL ZONE GIVEN STRONG NORTHWESTERLY
JET AND PRESENCE OF SHEARED MID-LEVEL SHORT WAVE...SO AM A LITTLE
HESITANT TO PULL CLOUDS/SPRINKLES OF GOING FORECAST. WILL SHIFT
TIMING A COUPLE HOURS PAST MIDNIGHT BUT OTHERWISE LEAVE ALONE AT
THIS POINT WITH LOCAL 8 KM WRF-ARW RUN ALSO STILL PRODUCING A LITTLE
QPF OVER SOUTHWEST WI/NORTHWEST IL TOWARD MORNING.
OTHERWISE...OTHER THAN ADJUSTMENTS TO HOURLY TEMP/WIND AND SKY COVER
GRIDS NO OTHER SIGNIFICANT CHANGES MADE TO NEAR TERM OF FORECAST FOR
THE OVERNIGHT HOURS.
RATZER
//PREV DISCUSSION...
300 PM CDT
THE FORECAST CHALLENGES ARE MAINLY TEMPERATURES AS SUMMER LOOKS TO
WIN OUT OVER AUTUMN IN THE EARLY GOING OF SEPTEMBER.
SYNOPSIS...IMPRESSIVELY DEEP UPPER TROUGH OVER EASTERN CANADA IS
BEING REINFORCED THIS AFTERNOON WITH A VIGOROUS JET DIVING INTO
THE UPPER GREAT LAKES. AS A GEE-WHIZ AND A SIGN OF THE CHANGE IN
SEASONS...NOT HERE YET BUT UP NORTH...850MB TEMPS AT CWZC ON THE
SOUTHERN END OF JAMES BAY DROPPED FROM +11C LAST NIGHT TO -5C THIS
MORNING UNDER THAT UPPER TROUGH. AN ASSOCIATED SURFACE COLD FRONT
IS DRAPED FROM LAKE ONTARIO THROUGH CENTRAL WI INTO SOUTHERN MN.
THIS FRONT HAS BEEN MOVING SLOWLY BUT CONSISTENTLY SOUTHWARD TODAY
WITH A RIBBON OF STRATUS/STRATOCU BEHIND IT. ALSO SEEN UPSTREAM IS A
SHEARING OUT SHORTWAVE ACROSS NW MN WHICH WILL CONTINUE TO MOVE
SOUTHEASTWARD.
TONIGHT...GIVEN THE COLD FRONT ORIENTATION AND THE LOSS OF MIXING
OF WESTERLY WINDS...EXPECT THE SURFACE COLD FRONT TO PROGRESS
QUICKER DOWN THE LAKE THIS EVENING...REACHING CHICAGO BY JUST
AFTER SUNDOWN OR SO. THIS WILL MEAN A TURN TO NORTHEAST WINDS AND
A DROP IN TEMPERATURE BY SEVERAL DEGREES LIKELY IN JUST A COUPLE
HOURS. READINGS SHOULD THEN STABILIZE NEAR THE LAKE GIVEN THE
STILL MILD WATER TEMPERATURES. THE NAM AND RAP SOUNDINGS ALONG
WITH COLD AIR ADVECTION AND RH FIELDS SUPPORT AT LEAST PATCHY
STRATUS MAKING IT DOWN INTO THE AREA NOT LONG BEHIND THE FRONT.
LOW-LEVEL THERMAL PROFILES ALSO HOVER AROUND LAPSE RATES
SUPPORTIVE OF LAKE-INDUCED CLOUDS. WITH THESE FORECASTS MESHING
WITH OBSERVATIONAL TRENDS UPSTREAM...HAVE BUMPED UP SKY COVER
LATER THIS EVE INTO OVERNIGHT. ALSO...AFOREMENTIONED SHEARING
SHORT WAVE OVER NW MN WILL RIDE A TIGHT 600-800MB THERMAL GRADIENT
INTO NW/NC IL BY EARLY OVERNIGHT. NAM FORECAST SOUNDINGS OVER RFD
WOULD CONTINUE TO SUPPORT A CHANCE FOR SOME SPRINKLES LATE AS THE
WAVE OVERRIDES SOME OF THE LOWER LEVEL MOISTURE. SO CONTINUE THAT
IN THE FORECAST BUT HAVE JUST BACKED UP IN TIME. WHILE A COLD
FRONT IS EASING THROUGH...TEMPERATURES WILL END UP SEVERAL DEGREES
WARMER THAN LAST NIGHT WITH MORE OF A WIND COMPONENT AND
INCREASING CLOUD COVER ACTING AS INSULATION.
THURSDAY THROUGH SATURDAY...FAIRLY QUIET WEATHER INTO FRIDAY
CONTINUES TO BE THE TREND IN THE WEATHER PATTERN. NORTHEAST WINDS
WILL CONTINUE INTO THU WITH TEMPERATURES IN THE 70S ACROSS AREAS
NORTH OF I-80. WARM AIR ADVECTION BEGINS FRIDAY AS THE HIGHS
SHIFTS EAST. THE 04.00 EC WAS FAIRLY SHARP WITH THIS ALOFT AND
HAVING A COINCIDENT SHORT WAVE WITH OUTPUT QPF. ITS MORE CURRENT
RUN IS MORE IN LINE WITH OTHER GUIDANCE...THAT IS DRIER AND
CONTINUE AS SUCH IN THE FORECAST. NEXT SHORT WAVE DROPS OVER THE
GREAT LAKES WITH ASSOCIATED WEAK SURFACE COLD FRONT OOZING
SOUTHWARD ON SAT. BEST LAPSE RATES AND MOISTURE ARE REALLY
CONFINED TO THE FRONT...SO DO NOT INTRODUCE SHOWER CHANCES UNTIL
SAT AFTERNOON AND AT THAT LOW AT THIS TIME. TEMPS RIGHT NOW LOOK
TO BE IN THE MID 80S FOR SAT GIVEN LOCAL CLIMATOLOGY...AND GIVEN
LOW-LEVEL THERMAL VALUES WHAT THEY WERE TODAY BUT WITH EVEN MORE
SW ADVECTION.
MTF
EXTENDED FORECAST SAT NIGHT-WED...WEAK COLD FRONT CONTINUES TO DROP
SOUTH THROUGH THE AREA SATURDAY EVENING INTO SUNDAY. WILL KEEP LOW
POPS FOR SATURDAY NIGHT...AND FOR THE SOUTHERN PART OF THE FORECAST
AREA SUNDAY. HIGH PRESSURE MOVES ACROSS THE LAKES SUNDAY WITH
NORTHEAST SURFACE WINDS. THIS SHOULD BRING DRY AND A LITTLE COOLER
WEATHER...ESPECIALLY NEAR THE LAKE. SUNDAY NIGHT INTO MONDAY THE
UPPER RIDGE AXIS SHIFTS EAST TOWARD THE GREAT LAKES AND THE SURFACE
HIGH SHIFTS EAST BRINGING A RETURN TO SOUTHERLY FLOW AND WARMER
WEATHER. GUIDANCE PRODUCING SLIGHT CHANCE POPS MOST PERIODS DAYS 4
THOUGH 7 BUT DON`T SEE ANY REAL FOCUS FOR THUNDERSTORMS SUNDAY NIGHT
THROUGH MONDAY NIGHT OR TUESDAY. AS UPPER RIDGE AXIS PUSHES EAST
THROUGH THE GREAT LAKES THE HEAT DOMES SPREADS EAST. TUESDAY LOOKS
ESPECIALLY WARM WITH GFS 925 MB TEMPS 26-28C AND ECMWF EVEN A BIT
WARMER WITH STRONG WSW FLOW. LOOKING AT CIPS ANALOGS...SIMILAR
PATTERNS IN LATE AUGUST AND SEPTEMBER YIELDED SURFACE TEMPS MOSTLY
IN THE LOWER 90S. HAVE BUMPED UP MAX TEMPS OVER GUIDANCE FOR
TUESDAY. NOT GOING TO GO WILD WITH TEMPS 6 DAYS OUT...BUT WILL
CONTINUE TO MONITOR. COULD SEE NEAR RECORD HIGHS TUESDAY IF MODELS
PAN OUT AND WE GET ENOUGH SUNSHINE. UPPER TROF MOVES ACROSS THE
UPPER LAKES AND TRAILING SURFACE COLD FRONT APPROACHES THE FORECAST
AREA TUESDAY NIGHT INTO WEDNESDAY FOR THE BEST CHANCE OF
THUNDERSTORMS IN THE EXTENDED PERIOD.
ALLSOPP
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* FROPA TURNING WINDS TO THE NORTHEAST IN THE NEAR TERM...WITH AN
INCREASE IN SPEED AND GUSTS THROUGH THE MORNING.
* LOW END MVFR AND IFR CEILINGS POSSIBLE EARLY THIS MORNING.
RODRIGUEZ
//DISCUSSION...UPDATED 06Z...
MAIN CONCERN THIS FORECAST PERIOD IS IN THE NEAR TERM...WITH WINDS
TURNING TO THE NORTHEAST WITH A SLOW MOVING COLD FRONT AS WELL AS
POTENTIAL FOR LOWER CEILINGS. LATEST OBSERVATIONS INDICATING A
SLOW PROGRESSION OF THIS FRONT INTO NORTHEAST ILLINOIS...WITH
WINDS SHIFTING TO THE NORTHEAST BUT STILL REMAINING ON THE LIGHTER
SIDE. THIS TRANSITION TO THE NORTHEAST WILL OCCUR WITH ALL THE
TERMINALS WITHIN THE NEXT 1-2 HOURS...WITH WINDS INITIALLY
REMAINING LIGHT. THEN AS THE GRADIENT PICKS UP...SHOULD SEE AN
INCREASE IN SPEEDS/GUSTS THROUGH THE REMAINDER OF THE MORNING.
LATEST SATELLITE IMAGERY DEPICTING AREA OF LOW END MVFR/IFR
CEILINGS INCREASING IN COVERAGE AS THEY SPILL SOUTH INTO NORTHEAST
ILLINOIS. WITH THIS INCREASE IN COVERAGE AND SHORT TERM GUIDANCE
SHOWING THIS LOW LEVEL MOISTURE MOVING ACROSS THE TERMINALS...HAVE
INCLUDED A PERIOD OF LOWER CEILINGS EARLY THIS MORNING.
ALTHOUGH...CONFIDENCE AS TO THE DURATION OF THE LOWER CEILINGS IS
SOMEWHAT LOWER AS THESE LOW CLOUDS SHOULD REMAIN PROGRESSIVE
WITHOUT ANY FURTHER EXPANSION ON THE BACKSIDE. WITH THE DEPARTURE
OF THESE CLOUDS...EXPECT VFR CONDITIONS THROUGH THE REMAINDER OF
THE FORECAST PERIOD.
RODRIGUEZ
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE WITH WIND SPEED AND DIRECTION.
* MEDIUM CONFIDENCE WITH CEILING TRENDS THIS MORNING.
RODRIGUEZ
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...VFR. WX NIL.
SATURDAY...CHANCE TSRA LATE AFTERNOON AND OVERNIGHT.
SUNDAY...SLIGHT CHANCE OF TSRA...OTHERWISE VFR.
MONDAY...SLIGHT CHANCE OF TSRA EARLY...OTHERWISE VFR.
TUESDAY...SLIGHT CHANCE OF TSRA...OTHERWISE VFR.
KREIN
&&
.MARINE...
229 PM CDT
A COLD FRONT IS STARTING TO MAKE ITS WAY DOWN LAKE MICHIGAN THIS
AFTERNOON WITH A PUSH OF NORTH-NORTHEASTERLY FLOW BEHIND THE FRONT
INCREASING THE WINDS INTO THE 15 TO 20 KT RANGE WITH OCCASIONAL
GUSTS TO 25 KT POSSIBLE. THE FRONT SHOULD CLEAR THE SOUTH END OF THE
LAKE AROUND MIDNIGHT TONIGHT. WITH A DECENT FETCH DOWN THE
LAKE...WAVES ARE EXPECTED TO BUILD INTO THE 3 TO 6 FT RANGE AT THE
SOUTH END OF THE LAKE PROMPTING A SMALL CRAFT ADVISORY FOR MAINLY
THE ILLINOIS NEARSHORE WATERS LATE THIS EVENING AND OVERNIGHT.
THESE CONDITIONS SHOULD SUBSIDE BACK BELOW CRITERIA THURSDAY
AFTERNOON AS HIGH PRESSURE PASSES OVER THE LAKE. AS THE HIGH
SHIFTS OVER THE EASTERN LAKES FRIDAY...SOUTHERLY FLOW INCREASES
AGAIN ACROSS THE LAKE. ANOTHER FRONT IS EXPECTED TO SAG SOUTH
ACROSS THE LAKE SATURDAY NIGHT INTO EARLY SUNDAY.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM THURSDAY TO 5 AM
FRIDAY.
IN...BEACH HAZARDS STATEMENT...INZ001...4 AM THURSDAY TO 5 AM FRIDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...4 AM
THURSDAY TO 3 PM THURSDAY.
&&
$$
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FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS DES MOINES IA
356 AM CDT THU SEP 5 2013
.SHORT TERM.../TODAY/...
ISSUED AT 355 AM CDT THU SEP 5 2013
WEAK ELEVATED SHOWER ACTIVITY LOOKS TO CONTINUE THROUGH THE MID
MORNING HOURS OVER THE WESTERN EDGES OF THE FORECAST AREA. THE
WEAK AREA OF VORTICITY ADVECTION BETWEEN 700-300MB WILL DISSIPATE
BY AROUND 18Z. SOUNDINGS BELOW 10KFT REMAIN VERY DRY AND NOT
EXPECTING MUCH QPF...IF ANY AT ALL...WITH THESE SHOWERS. KEPT
THUNDER OUT OF THE FORECAST ATTM AS LITTLE TO NO INSTABILITY
PRESENT THIS MORNING. THE 09.05 05Z HRRR HAS A DECENT HANDLE ON
THE OVERALL RADAR TRENDS THIS MORNING...BUT HAS SHOWERS LINGERING
PAST 18Z. FELT CONFIDENT ENOUGH TO KEEP FORECAST DRY AFTER 16Z
THIS MORNING WITH THE LACK OF FORCING AND MOISTURE AVAILABLE. USED
A BLEND OF THE 09.05 00Z NAM12/ECMWF FOR MAX TEMPS TODAY EVEN WITH
THE MID TO HIGH LEVEL CLOUD COVER THIS MORNING.
.LONG TERM.../TONIGHT THROUGH WEDNESDAY/...
ISSUED AT 355 AM CDT THU SEP 5 2013
MAIN CONCERNS THROUGH EARLY NEXT WEEK CONTINUE TO BE SUBTLE MINIMAL
PRECIP CHANCES AND WARMER TEMPS THROUGH EARLY NEXT WEEK. IA WILL
REMAIN IN NW FLOW INTO FRI WITH LOW CONFIDENCE IN PRECIP TRENDS.
MODELS CONTINUE TO GENERATE SPOTTY QPF BUT CANNOT REALLY FIND ANY
SUBSTANTIAL KINEMATIC OR THERMODYNAMIC FEATURES TO KEY ON...SO WITH
SURFACE BASED POTENTIAL NIL...WILL LEAVE FORECAST DRY. COULD BE
SOME WEAK VERY ELEVATED CONVECTION...BUT CONFIDENCE IN TIMING AND
LOCATION IS NOT GREAT ENOUGH TO MENTION. WARM ADVECTION DOES LIFT
THROUGH FRI DURING THE DAY...BUT MOISTURE SEEMS SOMEWHAT LIMITED AND
ITS DAYTIME TIMING WOULD NOT BE CLIMATOLOGICALLY FAVORED. HAVE
WAITED TO INTRODUCE SLIGHTS NE FRI NIGHT WHEN MOISTURE INCREASES A
BIT.
THE BIGGEST SENSIBLE WEATHER REFLECTION MAY BE TEMPERATURES WARMING
FURTHER HOWEVER WITH WIDESPREAD HIGHS ABOVE 90F. A WEAK BOUNDARY
WILL SAG INTO NRN IA SAT...BUT WILL NOT CHANGE THE AIRMASS MUCH
KEEPING TEMPS FAIRLY STATIC NORTH AND EVEN WARMING A FEW DEGREES TO
ITS SOUTH WITH PLENTY OF HIGHS IN THE MID 90S I80 INTO MO.
BAROCLINIC ZONE STRENGTHENS SLIGHTLY SAT NIGHT AS FRONT CONTINUES
TO DRIFT FARTHER SOUTH SO HAVE PUSHED FRI NIGHT SLIGHTS DOWN INTO
CENTRAL AND SRN IA BY THAT TIME. ANYTHING IN THIS TIME RANGE WOULD
LIKELY BE QUITE ELEVATED ABOVE THE ELEVATED MIXED LAYER.
THETA-E/WARM ADVECTION STRENGTHENS CONSIDERABLY BY LATE SUN FROM
IA/MN BORDER INTO THE NRN PLAINS. THIS WILL ALLOW TEMPS TO REBOUND
ONCE AGAIN AFTER BRIEFLY DROPPING A TAD SUN. THE STRONGER
THERMODYNAMIC FORCING ALSO STILL SUPPORTS MAINLY NOCTURNAL PRECIP
CHANCES NORTH...WITH BEST POTENTIAL NORTH OF IA.
WAVE CURRENTLY OFF THE OR COAST VERY SLOWLY BUT SURELY TOPS THE
ROCKIES RIDGE BY EARLY NEXT WEEK AND EVENTUALLY RESULTS IN MORE
ORGANIZED SYNOPTIC SCALE FORCING. THIS LIFT WILL SLOWLY PUSH SOUTH
AND EAST COINCIDENT WITH THE FRONTAL BOUNDARY AND LIKELY BRING OUR
BEST WINDOW OF PRECIP CHANCES LATE TUE INTO WED. THE FRONTAL
PASSAGE WILL ALSO DROP OUR TEMPS BACK CLOSER TO NORMAL FOR WED.
&&
.AVIATION...05/06Z
ISSUED AT 1202 AM CDT THU SEP 5 2013
VFR CONDITIONS EXPECTED THROUGHOUT THE TAF FORECAST PERIOD.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...PODRAZIK
LONG TERM...SMALL
AVIATION...BEERENDS
AREA FORECAST DISCUSSION
NWS GOODLAND KS
255 AM MDT THU SEP 5 2013
.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 250 AM MDT THU SEP 5 2013
STUBBORN UPPER HIGH WILL REMAIN PARKED OVER THE FORECAST AREA
THROUGH SATURDAY...AFTER WHICH TIME THE UPPER LOW OVER THE PAC NW
WILL BEGIN TO NUDGE IT EAST. AT THE SURFACE THE WEAK TROUGH OVER
EASTERN COLORADO WILL REMAIN IN PLACE RESULTING IN SOUTHERLY
SURFACE FLOW.
NO CHANGES WORTH NOTING FROM PREVIOUS FORECAST IN TERMS OF MAX-MIN
TEMPS AND WINDS. HIGHS WILL CONTINUE IN THE 95-102 RANGE WITH LOWS
IN THE 60S. NO PRECIP IS EXPECTED DURING PERIOD AFTER THIS
MORNING. DID INCLUDE SLIGHT CHANCE POPS FROM YUMA COUNTY EAST TO
RED WILLOW FOR EARLY THIS MORNING TO ACCOUNT FOR CURRENT RADAR
TRENDS. EVEN THOUGH SHOWERS CONTINUE TO WEAKEN JUST TO OUR NORTH
OVER PHILLIPS AND CHASE COUNTIES...WILL KEEP LOW POPS GOING FOR A
FEW HOURS AFTER SUNRISE. LAST SEVERAL RUNS OF HRRR SUGGEST SOME
PRECIP MAY LINGER A BIT INTO THE MORNING HOURS. OTHERWISE...TODAY
THROUGH SATURDAY WILL BASICALLY BE A REPEAT OF YESTERDAY.
.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 250 AM MDT THU SEP 5 2013
THE 500MB HIGH IS STILL CENTERED OVER KANSAS AND BEGINS TO MOVE
EAST SUNDAY NIGHT INTO MONDAY WHILE THE UPPER LOW/TROUGH OVER THE
PACIFIC NORTHWEST MOVES INTO THE NORTHERN PLAINS. SUNDAY THROUGH
MONDAY SHOULD REMAIN WARM AND DRY...WITH HIGHS IN THE MID TO UPPER
90S. MODELS STILL DISAGREE OVER TIMING AND PLACEMENT OF THE COLD
FROPA NEXT WEEK...GFS HAS IT MOVING THROUGH MORE QUICKLY ON MONDAY
NIGHT INTO TUESDAY WHILE THE ECMWF HAS IT MOVING THROUGH TUESDAY
INTO TUESDAY NIGHT. AS OF RIGHT NOW...WEDNESDAY LOOKS TO BE THE
COOLEST DAY WITH NEAR NORMAL HIGH TEMPERATURES IN THE LOW TO MID
80S. TEMPERATURES MAY NEED ADJUSTING AS THE WEEK PROGRESSES AND
THE TIMING/PLACEMENT OF THE FRONT IS MORE SOLID. THE ALLBLEND
SOLUTION FOR TEMPERATURES AND PRECIPITATION SEEMED LIKE THE BEST
WITH THE CURRENT MODEL DIFFERENCES. THERE WERE MINOR ADJUSTMENTS
TO PRECIP...REMOVING THE 15 POP IN EASTERN COLORADO ON MONDAY
AFTERNOON CONSIDERING THE RIDGE WILL STILL BE IN PLACE...AND THERE
IS NO FEATURE THAT WOULD INDICATE PRECIP. OTHER THAN THAT...PRECIP
CHANCES ARE STILL THE GREATEST IN THE MONDAY NIGHT THROUGH
WEDNESDAY TIME FRAME. GFS HAS PWATS AROUND 1.50 ON TUESDAY
WHICH...GIVEN THE FRONT MOVING THROUGH AND NORTHEASTERLY/EASTERLY
FLOW BEHIND THE FRONT...COULD RESULT IN SOME GOOD RAINFALL AMOUNTS
WITH THE SHOWERS AND THUNDERSTORMS THAT MOVE THROUGH THE CWA.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1121 PM MDT WED SEP 4 2013
VFR CONDITIONS WILL CONTINUE AT KGLD AND KMCK FOR THE NEXT 24
HOURS AS A RIDGE OF HIGH PRESSURE IS CENTERED OVER THE AREA. SOME
GUSTY SOUTH WIND WILL BE POSSIBLE THURSDAY IN RESPONSE TO A
SURFACE TROUGH NEAR THE KANSAS/COLORADO BORDER.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DLF
LONG TERM...ALW
AVIATION...FS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
147 AM EDT THU SEP 5 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 407 PM EDT WED SEP 4 2013
WV IMAGERY AND RUC ANALYSIS INDICATED NW MID/UPPER LEVEL THROUGH THE
UPPER GREAT LAKES BETWEEN A LOW OVER NRN QUEBEC AND A RIDGE FROM
COLORADO THROUGH THE WRN PLAINS. WITH CONFLUENT FLOW AND 700-300 MB
QVECTOR DIV BUILDING INTO THE AREA...EXPECT MAINLY CLEAR SKIES TO
PREVAIL WITH ONLY SOME BANDS OF CIRRUS THROUGH THE ERN CWA...PER VIS
IMAGERY. AT THE SFC...HIGH PRES FROM SRN MANITOBA INTO NW ONTARIO
WAS BUILDING INTO THE NRN GREAT LAKES WITH INFLUX OF DRY AIR ON NRN
ACYC FLOW. LOWER DEWPOINTS UPSTREAM FROM LAKE SUPERIOR (READINGS IN
THE UPPER 30S) WERE FILTERING TOWARD UPPER MI.
TONIGHT...EVEN WITH PWAT VALUES AROUND 0.50 INCH CLIMBING TO NEAR
0.75 INCH...WITH HIGH PRES BUILDING INTO UPPER MI...MOSTLY CLEAR
SKIES AND LIGHT WINDS ALLOW TEMPS TO DROP OFF TOWARD THE LOWER END
OF GUIDANCE. READINGS INTO THE UPPER 30S INLAND WEST AND LOW TO MID
40S OVER THE EAST AND ALONG THE GREAT LAKES ARE EXPECTED. PATCHY
FROST MAY BE POSSIBLE IN THE TYPICAL COLD SPOTS FROM REPUBLIC AND
CHAMPION TO AMASA...IRON RIVER AND WATERSMEET.
THURSDAY...UNDER ABUNDANT SUNSHINE WITH 850 MB TEMPS IN THE 6C TO
10C RANGE...TEMPS WILL REBOUND CLOSER TO SEASONAL AVERAGES WITH HIGHS
RANGING FROM THE UPPER 60S EAST TO THE LOWER 70S WEST.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 407 PM EDT WED SEP 4 2013
HIGH PRESSURE WILL KEEP WEATHER QUIET THURSDAY NIGHT THROUGH EARLY
FRIDAY AFTERNOON. AS THE HIGH CENTERS OVER THE EASTERN
SEABOARD...UPPER MICHIGAN IS POSITIONED ON THE NORTHWESTERN
PERIPHERY OF THE RIDGE...MAKING US VULNERABLE FOR WEAK WAVES TO
SLIDE THROUGH. THE FIRST OF THESE SLIDES OUT AHEAD OF THE MAIN
TROUGH ON FRIDAY AFTERNOON. MODELS ARE MOSTLY IN AGREEMENT...WITH
THE EXCEPTION OF THE GFS WHICH BRINGS THE MAIN TROUGH IN MUCH
QUICKER...SO STRAYED FROM THAT SOLUTION. USED PRIMARILY THE
GEM/ECMWF FOR THIS LONG TERM FORECAST.
WEAK MOISTURE ADVECTION/CONVERGENCE SHOWS UP FOR THE MID LEVELS AND
FOCUSES ACROSS THE WEST AND NORTHERN PORTIONS OF THE CWA EARLIER IN
THE DAY...PRIMARILY OVER THE KEWEENAW AND LAKE SUPERIOR. THROUGHOUT
THE DAY THIS REGION MOVES EAST-SOUTHEASTWARD TOWARDS QUEBEC...SO
KEPT PCP CHANCES FAR EAST INTO FRIDAY EVENING. OVERALL...850-500MB
QVECTOR CONVERGENCE IS PALTRY BUT WARRANTS SOME SLIGHT CHANCE/CHANCE
POPS. LOW LEVELS ARE FAIRLY DRY THOUGH...AND INSTABILITY IS MINIMAL.
WILL KEEP THE POPS PRIMARILY OVER THE LAKE AND FAR EAST FOR NOW.
FRIDAY NIGHT THROUGH SATURDAY THE STRONGER TROUGH MOVES THROUGH THE
GREAT LAKES AS LOW PRESSURE OVER JAMES BAY ON FRIDAY MOVES INTO
QUEBEC. MOISTURE IS DEEPER AND INSTABILITY IS GREATER THIS GO
AROUND...WHICH WILL SUPPORT SHOWERS AND TSTORMS ACROSS THE CWA. THE
WESTERN CWA IS LIKELY TO SEE SHOWERS/A FEW TSTORMS STARTING LATER
FRIDAY NIGHT AND CONTINUING THROUGH MAINLY SATURDAY MORNING. WITH
GREATER INSTABILITY BUILDING TOWARDS SATURDAY AFTERNOON ALONG THE WI
BORDER AND CENTRAL U.P. LINGERED CHANCE POPS THERE THROUGH THE
AFTERNOON.
THE BEST MOISTURE IS CENTRAL AND EAST HOWEVER...AND SFC BASED CAPE
IS AROUND 1000-500 J/KG FOR THE AFTERNOON. WITH THE FRONT PASSING
THROUGH THE CENTRAL CWA AROUND 18Z AND NORTHWEST FLOW ALOFT...EXPECT
WE WILL SEE SOME ACTIVITY. 0-6KM BULK SHEAR IS AROUND 20-30
KNOTS...SO DO NOT EXPECT ANYTHING TOO GET TOO ORGANIZED. ANY SEVERE
THREAT AS OF RIGHT NOW LOOKS TO BE VERY ISOLATED.
ON SUNDAY HIGH PRESSURE BRINGS A BRIEF BREAK TO THE PRECIPITATION.
MONDAY AND TUESDAY A WARM FRONT LIFTS ACROSS THE MIDWEST WITH A
STRONGER LOW PRESSURE SYSTEM IN THE NORTHERN PLAINS. THIS LOW WILL
MOVE NORTHEASTWARD INTO ONTARIO...AND EVENTUALLY BRING A COLD FRONT
ACROSS UPPER MI ON WEDNESDAY. HAVE CHANCE POPS IN THE FORECAST FOR
NOW...GIVEN DIFFERENCES BETWEEN MODELS IN THE LOCATION OF THE LOW
PRESSURE SYSTEM DURING THESE TIMES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 144 AM EDT THU SEP 5 2013
WITH HIGH PRESSURE BUILDING INTO THE REGION...EXPECT VFR CONDITIONS
AND LIGHT WINDS THROUGH THE FCST PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 407 PM EDT WED SEP 4 2013
WITH HIGH PRES BUILDING INTO THE UPPER LAKES...WINDS WILL DIMINISH
TO LESS THAN 20 KTS LATER TONIGHT INTO THURSDAY. SW WINDS WILL
INCREASE ON FRIDAY IN THE TIGHTER PRESSURE GRADIENT BETWEEN THE
EXITING HIGH PRESSURE AND A COLD FRONT THAT ARRIVES THIS WEEKEND.
EXPECT WINDS ON FRIDAY TO STAY LESS THAN 25 KTS. WINDS FOR THE
REMAINDER OF THE FORECAST PERIOD WILL REMAIN LESS THAN 20 KNOTS DUE
TO WEAKER PRESSURE GRADIENT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...MCD
AVIATION...VOSS
MARINE...JLB
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
411 AM CDT Thu Sep 5 2013
.SHORT TERM...(Today through Saturday)
Issued at 410 AM CDT THU SEP 5 2013
At 8z water vapor imagery and RAP analysis continue to indicate a
strong 596 hpa H5 ridge over the interior mountain region of the
CONUS, with a deep trough over the Hudson Bay area. Between these
two features light northwest flow continues in the mid levels. At 8z
water vapor as well as IR imagery indicated an area of mid level
clouds rounding the northwest quadrant of the mid level ridge across
far eastern Nebraska and far western Iowa. Radar imagery indicates
that there are a few showers associated with this area of clouds.
These showers, with an isolated lightning strike or two are likely
associated with a very weak and subtle impulse rounding the mid
level ridge. Today`s forecast will depend on how many clouds this
subtle wave will form through the day. The current thought is that
these showers will likely not make it as far south as Interstate 70,
although a few light sprinkles or showers may affect the far
northern and western portions of Missouri and extreme NE Kansas. As
the trough moves through it looks as though it will bring with it
some mid level cloud cover, especially in the western half of the
forecast area. These mid level clouds could act to keep temperatures
a bit cooler than the going forecast suggested. Have gone with a dry
forecast for today, and dropped temperatures 1-3 degrees in the
western half of the CWA for day time highs. Even though perhaps
slightly cooler temps are expected day time highs will still make it
into the mid to upper 80s, but will continue to monitor the diurnal
trend and adjust based on how the cloud cover behaves.
For the rest of the mid range forecast expect dry conditions to
remain, as the mid level ridge continues to shunt any strong chance
for rain well north of the forecast area. With the steady flow of
southerly winds into the area as well as the mid level ridge keeping
the area clear of any significant cloud cover or rain expect a
steady warm up through the weekend, with daytime highs reaching the
lower 90s for Friday, and rising into the lower to mid 90s for
Saturday and Sunday. The only chance for rain in the forecast area
through the weekend will be a minimal chance for an isolated shower
or two across NC/NE Missouri Saturday night into Sunday morning.
.LONG TERM...(Sunday through Wednesday)
Issued at 410 AM CDT THU SEP 5 2013
Well above average temperatures will continue into the extended time
period however models are hinting at a potential pattern change
toward the end of the period. These well above above average
temperatures have been courtesy of an upper level ridge of high
pressure that has been dominating the regions weather. This will
also be the case at the onset of the extended period as the upper
level ridge axis will reside over the central Plains. Sunday an
upper level shortwave will be rounding this ridge and models
indicate that an overnight MCS will develop over Iowa and roll into
the eastern portion of the CWA Sunday morning. As such have added
slight chance POPs to the eastern CWA with slightly cooler
temperatures around 90 across the eastern CWA. Temperatures
elsewhere across the CWA will reach into the mid 90s.
Monday will be the warmest day in the extended time frame as the
upper level ridge axis moves directly overhead. Highs will reach
into the mid 90s CWA wide. However, Monday night an upper level
trough will move through the northern Plains into the Upper Midwest.
This will force a weak cold front towards the area however, it will
initially get hung up north of the CWA. It will also flatten the
upper level ridge across the area and force it into the southeastern
CONUS. This will make for a "cooler" Tuesday with highs in the low
to mid 90s.
Tuesday night a second upper level trough will dig into the northern
Plains. Models differ on the strength of the trough as the EC is
much stronger with it than the GFS or GEM. In either case, the
aforementioned cold front that was hung up north of the area will be
forced into the CWA Tuesday night. This will have a two-fold effect:
First, it will bring the next chance for showers and thunderstorms
to the area Tuesday night into Wednesday. Second, it will cool
temperatures into the mid to upper 80s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 1154 PM CDT WED SEP 4 2013
Nothing has changed from the previous discussion with VFR and light
southeast winds prevailing. KSTJ and river valleys across northern
and west central MO can expect patchy fog...with intermittent IFR
visibilities at KSTJ due to local effects...forming during the pre-
dawn hours and quickly dissipating after sunrise.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
SHORT TERM...Leighton
LONG TERM...73
AVIATION...MJ
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
403 AM CDT THU SEP 5 2013
.SYNOPSIS...
ISSUED AT 400 AM CDT THU SEP 5 2013
HUDSON BAY HAS DEEPENED CONSIDERABLY OVER THE PAST 24 HOURS WITH
A TROUGH EXTENDING DOWN THE ATLANTIC SEABOARD. HEAT RIDGE
CENTERED OVER NORTHEAST COLORADO HOLDS WITH A SHARP RIDGE INTO
THE CENTRAL PLAINS OF CANADA. CLOSED LOW OFF THE OREGON COAST
NEARLY STATIONARY OVER THE PAST 24 HOURS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CDT THU SEP 5 2013
MODELS FAIRLY CONSISTENT IN THE NEAR TERM. RING OF FIRE WITH THE
UPPER LOW CENTERED OVER NORTHEAST COLORADO AND WESTERN NEBRASKA
POSITIONED FOR WEAK WAVES MOVING THROUGH QUICKLY AND SETTING OFF
MAINLY ISOLATED THUNDERSTORMS. WILL CARRY A PRE FIRST PERIOD IN
THE ZONES TO ACCOUNT FOR ONGOING PRECIPITATION. ISO T MOVING OUT
OF THE FORECAST AREA EARLY THIS MORNING. DEBRIS CLOUDS MAY BE
HARD TO GET RID OF TODAY. WITH THIS IN MIND HAVE UNDERCUT
GUIDANCE BY A COUPLE OF DEGREES AND KEPT NORTH CENTRAL NEBRASKA
COOLER BUT THE SOUTHWEST AND THE EASTERN NEBRASKA PANHANDLE IN
THE VICINITY OF THE SURFACE TROUGH WILL SEE TEMPERATURES SOAR TO
AROUND 100 DEGREES. STRONG SOUTHEAST FLOW TODAY TO THE EAST OF
THE SURFACE TROUGH OVER THE NEBRASKA PANHANDLE. WILL SEE ISOLATED
THUNDERSTORMS AGAIN IN THE PANHANDLE THIS AFTERNOON AND EVENING
BUT SHOULD NOT MAKE IT TOO FAR OFF THE HIGHER TERRAIN AND HAVE
ENDED THROUGH THE EVENING. A WARM NIGHT AGAIN WITH LOWS IN THE
MID TO UPPER 60S.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 400 AM CDT THU SEP 5 2013
HEAT WAVE CONTINUES INTO THE WEEKEND. CENTER OF THE RIDGE WILL
DRIFT EAST INTO THE WEEKEND AS TROUGH/LOW COMES ONSHORE ACROSS
THE PAC NW. 850 MB TEMPS CONTINUE TO SURGE ABOVE 30 DEGREES
ACROSS MOST OF THE AREA DURING THE AFTERNOON BOTH FRIDAY AND
SATURDAY. GUIDANCE HAS HIGHS AROUND 100 DEGREES FOR MOST OF THE
CWA...AND WILL NOT STRAY FROM GUIDANCE. DISTURBANCES CONTINUES TO
ROTATE AROUND THE RIDGE...AND WILL NEED TO KEEP A CHANCE FOR
STORMS ACROSS THE NORTHWEST INTO NORTH CENTRAL. LOWER LEVELS ARE
FAIRLY DRY HOWEVER MOISTURE ALOFT SHOULD BE ENOUGH TO GET THINGS
TO DEVELOP OVER THE HIGHER TERRAIN TO THE WEST THEN DRIFT EAST.
QUESTION IS HOWEVER MUCH COVERAGE AND HOW MUCH WILL REACH THE
GROUND. WILL CONTINUE SOME ISOLD POPS IN THE FORECAST WITH LOW
CONFIDENCE.
TROUGH CROSS THE NORTHERN ROCKIES LATE IN THE WEEKEND INTO THE
FIRST OF NEXT WEEK. THIS WILL PUSH THE CENTER OF THE RIDGE TO THE
SE...WITH 850 MB TEMPS TO BEGIN TO COOL SUNDAY. STILL GOING TO BE
TOASTY FOR SEPT...WITH HIGHS IN THE 90S FOR SUNDAY. MONDAY A
SURFACE COLD FRONT WILL ENTER THE NW PART OF THE CWA. TIMING IS
STILL AN ISSUE WITH MODELS ALTHOUGH SOME IMPROVEMENT FROM THE 12Z
RUNS. WILL SEE A CHANCE FOR STORMS AS THE FRONT SLOWLY PUSHES
ACROSS THE AREA. TUESDAY WITH CLOUDS AND A CHANCE FOR
STORMS...TEMPS CLOSER TO SEASONAL...LOWER TO MID 80S. BY
WEDNESDAY COOLER HIGH PRESSURE WILL BUILD ACROSS THE AREA...WITH
SHOWERS TO PUSH TO THE SOUTHEAST. HIGHS SHOULD STILL BE ABLE TO
WARM INTO THE 80S...AS THE SUN RETURNS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1125 PM CDT WED SEP 4 2013
TWO AREAS OF THUNDERSTORMS MOVED NORTH AND SOUTH THROUGH WRN NEB
THIS EVENING AS ADVERTISED BY THE SHORT RANGE MODELS. THE HRRR
AND RAP MODELS NOW SUGGEST THE POTENTIAL FOR ISOLATED STORM
DEVELOPMENT OVERNIGHT ACROSS NCNTL NEB EAST OF HIGHWAY 83.
HOWEVER IT LOOKS LIKE THE MODELS ARE CARRYING THE ONGOING
CONVECTION TOO FAR EAST SO THE POTENTIAL FOR STORM DEVELOPMENT IS
QUESTIONABLE. IF ANY STORMS DEVELOP...THEY SHOULD DISSIPATE BY
17Z THURSDAY.
OTHERWISE VFR IS EXPECTED THROUGH 22Z THURSDAY. THEREAFTER MORE
CONVECTION COULD DEVELOP ACROSS WRN NEB SIMILAR TO TODAY. THIS IS
SHOWN BY THE NAM WHICH FIRES OFF TSTMS ON THE LARAMIE RANGE AROUND
18Z-21Z THURSDAY WHICH COULD BEGIN AFFECTING WRN NEB AROUND 23Z-
00Z.
&&
.FIRE WEATHER...
ISSUED AT 400 AM CDT THU SEP 5 2013
MINIMUM RELATIVE HUMIDITIES WILL FALL TO AROUND 20 PERCENT IN THE
VICINITY OF THE SURFACE TROUGH OVER THE NEBRASKA PANHANDLE THIS
AFTERNOON. THIS IS ALSO WHERE WINDS WILL BE THE LIGHTEST. THINGS
WILL CONTINUE TO DRY OVER THE NEXT SEVERAL DAYS WITH LITTLE IN THE
WAY OF PRECIPITATION. THAT TIME OF YEAR FOR CROPS DRYING. FIRE
DANGER WILL INCREASE.
&&
.CLIMATE...
ISSUED AT 400 AM CDT THU SEP 5 2013
A RECORD HERE OR THERE MAY FALL OVER THE NEXT FEW DAYS DURING THIS
HEAT WAVE...HOWEVER MOST ARE SAFE. OVER THE NEXT 3 DAYS HIGHS WILL
APPROACH AND POSSIBLY SURPASS 100 DEGREES ACROSS THE AREA. RECORD
HIGHS ARE ALL AT OR ABOVE 100. FOR THE 5TH, 6TH, AND 7TH...MANY OF
THE RECORD HIGHS ARE NEAR THE WARMEST OF ALL OF SEPTEMBER...WHICH
MAKES IT TOUGHER TO REACH. BELOW ARE THE RECORD HIGHS FOR THE NEXT
3 DAYS. FRIDAY AND SATURDAY ARE THE BEST CHANCE TO SET A RECORD
HIGH.
LOCATION...RECORD HIGH THURS...FRI...SAT.
NORTH PLATTE...105/1931...102/1931...102/1959.
VALENTINE......103/1998...101/1980...100/1940.
BROKEN BOW.....105/1931...101/1984+...102/1940.
IMPERIAL.......110/1931...105/1959+...103/1969.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...POWER
SHORT TERM...POWER
LONG TERM...MASEK
AVIATION...CDC
FIRE WEATHER...POWER
CLIMATE...MASEK
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
113 AM CDT THU SEP 5 2013
.SYNOPSIS...
ISSUED AT 342 PM CDT WED SEP 4 2013
UPPER RIDGE OF HIGH PRESSURE CENTERED OVER THE CENTRAL HIGH PLAINS
CONTINUES TO DOMINATE THE OVERALL SYNOPTIC PATTERN...WITH A TROUGH
OF LOW PRESSURE OVER THE NORTHEASTERN STATES...AND ONE OFF THE
PACIFIC NORTHWEST COAST. AT THE SURFACE...A TROUGH OF LOW PRESSURE
ARCHES FROM EAST CENTRAL COLORADO ACROSS THE PANHANDLE INTO SOUTHERN
SOUTH DAKOTA. SURFACE HIGH PRESSURE REMAINS OFF TO THE EAST ACROSS
THE MID MISSISSIPPI RIVER VALLEY. AS OF 20Z TEMPERATURES RANGED
FROM THE MID 80S OVER THE HEART OF THE SANDHILLS...TO THE MID 90S
ALONG THE NORTH PLATTE RIVER VALLEY NEAR KOGA.
&&
.UPDATE...
ISSUED AT 112 AM CDT THU SEP 5 2013
UPDATING FORECAST TO ACCOUNT FOR ON GOING PRECIPITATION OVER
SOUTHWEST NEBRASKA. INCREASED CLOUDS ADJUSTED WINDS AND EXPANDED
AREA OF PRECIPITATION.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 342 PM CDT WED SEP 4 2013
THUNDERSTORM CHANCES AND ABNORMALLY WARM TEMPERATURES HIGHLIGHT THE
SHORT TERM DISCUSSION. DESPITE LARGE SCALE SUBSIDENCE ASSOCIATED
WITH THE UPPER LEVEL RIDGE...SUFFICIENT DAYTIME HEATING WILL COMBINE
WITH A WEAK MIDLEVEL DISTURBANCE TO SPARK OFF ISOLATED CONVECTION
ACROSS WESTERN AND SOUTHWEST NEBRASKA THIS EVENING. OBJECTIVE
ANALYSIS INDICATES 1000-2000 J/KG OF MUCAPE WITH EFFECTIVE SHEAR ON
THE ORDER OF 30 KTS. ISOLATED STRONG WIND GUSTS WOULD BE POSSIBLE
WITHIN OR NEAR ANY CELL THAT DEVELOPS...ESPECIALLY GIVEN THE
PROJECTED INVERTED V SOUNDINGS WITH LARGE T/TD SPREADS. THE
ACTIVITY MAY CONTINUE ACROSS THE HEART OF THE CWA OVERNIGHT AS A LLJ
RE-DEVELOPS WITH INCREASING CONVERGENCE & WAA...FOR THIS WILL CARRY
A SLIGHT CHANCE MENTION THROUGH 15Z THURSDAY FROM WEST TO EAST.
ADDITIONAL STORMS WILL BE POSSIBLE THURSDAY AFTERNOON...WITH THE
AMPLIFIED RIDGE ATOP THE CWA...AND SUBSEQUENT WEAK DISTURBANCES
PASSING THROUGH THE FLOW.
AS FOR TEMPERATURES...HIGHS WILL REMAIN WELL ABOVE AVERAGE AS H85
T/S WARM WELL ABOVE 30C FOR MOST LOCATIONS. HIGHS ON THURSDAY WILL
TOP OUT ONCE AGAIN IN THE LOW TO MID 90S FOR MOST LOCATIONS.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 342 PM CDT WED SEP 4 2013
FOR THE MID-RANGE FORECAST...WEATHER WILL BE HOT AND DRY. MODEL
OUTPUT STATISTICS FROM THE THREE AVAILABLE BULLETINS INDICATE
ANOTHER HEAT WAVE IN THE MIDDLE RANGE OF THE FORECAST. IT SEEMS THAT
100 PLUS IS NOT OUT OF THE QUESTION FRIDAY OVER ALL OF CENTRAL AND
WESTERN NEBRASKA WITH THE HOTTEST WEATHER ALONG THE NEBRASKA-SOUTH
DAKOTA STATE LINE.
THE GFS SHOWS THE HOTTEST AIR SINKING SOUTH TO SOUTH CENTRAL AND
SOUTHWEST NEBRASKA FOR SATURDAY AS A WEAK FRONT DRIFTS ACROSS INTO
NEBRASKA...BUT THAT LASTS ONLY ONE DAY. AS THE FRONT COMES INTO
NORTHERN NEBRASKA...IT WILL GENERATE SOME LIFT. A CROSS-SECTION
THROUGH NORTHERN NEBRASKA SHOWS INSTABILITY ABOVE 700MB AND SOME
HUMIDITY 75 PERCENT OR HIGHER. HOWEVER...BELOW THAT LEVEL...THE AIR
IS FAIRLY DRY AT 40-50 PERCENT. THE RESULT IS THAT PRECIPITATION
WILL BE SPOTTY AND FAIRLY LIGHT.
IT IS NOT UNTIL MONDAY THAT SIGNIFICANT RELIEF FROM THE HOT AND DRY
WEATHER CAN BE EXPECTED. AT THAT TIME...A MODERATE FRONT WILL MOVE
THROUGH NEBRASKA. THE GFS IS ABOUT 12 HOURS FASTER WITH THE FRONT
THAN IS THE GEM AND THE 12Z ECMWF IS ABOUT SIX HOURS FASTER THAN THE
GEM. THE DIFFERENCES AMONG THE MODELS COULD HAVE AN EFFECT ON THE
TIMING OF THE PRECIPITATION AND ALSO ON THE TEMPERATURES ON TUESDAY.
STILL...THERE IS ENOUGH AGREEMENT THAT WE CAN NUDGE THE CURRENT
FORECAST TO A BLEND OF THE THREE EXTENDED MODELS. THIS SHOULD BRING
TEMPERATURES 5-15 DEGREES LOWER MONDAY OR TUESDAY AND A CHANCE FOR
PRECIPITATION...THOUGH THERE IS STILL UNCERTAINTY REGARDING THE
TIMING...AMOUNT AND EXTENT OF THE PRECIPITATION. STILL...IT DOES
APPEAR THAT THE BETTER CHANCES FOR PRECIPITATION WILL BE IN THAT
MONDAY THROUGH WEDNESDAY PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1125 PM CDT WED SEP 4 2013
TWO AREAS OF THUNDERSTORMS MOVED NORTH AND SOUTH THROUGH WRN NEB
THIS EVENING AS ADVERTISED BY THE SHORT RANGE MODELS. THE HRRR AND
RAP MODELS NOW SUGGEST THE POTENTIAL FOR ISOLATED STORM
DEVELOPMENT OVERNIGHT ACROSS NCNTL NEB EAST OF HIGHWAY 83. HOWEVER IT
LOOKS LIKE THE MODELS ARE CARRYING THE ONGOING CONVECTION TOO FAR
EAST SO THE POTENTIAL FOR STORM DEVELOPMENT IS QUESTIONABLE. IF
ANY STORMS DEVELOP...THEY SHOULD DISSIPATE BY 17Z THURSDAY.
OTHERWISE VFR IS EXPECTED THROUGH 22Z THURSDAY. THEREAFTER MORE
CONVECTION COULD DEVELOP ACROSS WRN NEB SIMILAR TO TODAY. THIS IS
SHOWN BY THE NAM WHICH FIRES OFF TSTMS ON THE LARAMIE RANGE AROUND
18Z-21Z THURSDAY WHICH COULD BEGIN AFFECTING WRN NEB AROUND 23Z-
00Z.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...POWER
SYNOPSIS...JACOBS
SHORT TERM...JACOBS
LONG TERM...SPRINGER
AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1132 PM CDT WED SEP 4 2013
.SYNOPSIS...
ISSUED AT 342 PM CDT WED SEP 4 2013
UPPER RIDGE OF HIGH PRESSURE CENTERED OVER THE CENTRAL HIGH PLAINS
CONTINUES TO DOMINATE THE OVERALL SYNOPTIC PATTERN...WITH A TROUGH
OF LOW PRESSURE OVER THE NORTHEASTERN STATES...AND ONE OFF THE
PACIFIC NORTHWEST COAST. AT THE SURFACE...A TROUGH OF LOW PRESSURE
ARCHES FROM EAST CENTRAL COLORADO ACROSS THE PANHANDLE INTO SOUTHERN
SOUTH DAKOTA. SURFACE HIGH PRESSURE REMAINS OFF TO THE EAST ACROSS
THE MID MISSISSIPPI RIVER VALLEY. AS OF 20Z TEMPERATURES RANGED
FROM THE MID 80S OVER THE HEART OF THE SANDHILLS...TO THE MID 90S
ALONG THE NORTH PLATTE RIVER VALLEY NEAR KOGA.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 342 PM CDT WED SEP 4 2013
THUNDERSTORM CHANCES AND ABNORMALLY WARM TEMPERATURES HIGHLIGHT THE
SHORT TERM DISCUSSION. DESPITE LARGE SCALE SUBSIDENCE ASSOCIATED
WITH THE UPPER LEVEL RIDGE...SUFFICIENT DAYTIME HEATING WILL COMBINE
WITH A WEAK MIDLEVEL DISTURBANCE TO SPARK OFF ISOLATED CONVECTION
ACROSS WESTERN AND SOUTHWEST NEBRASKA THIS EVENING. OBJECTIVE
ANALYSIS INDICATES 1000-2000 J/KG OF MUCAPE WITH EFFECTIVE SHEAR ON
THE ORDER OF 30 KTS. ISOLATED STRONG WIND GUSTS WOULD BE POSSIBLE
WITHIN OR NEAR ANY CELL THAT DEVELOPS...ESPECIALLY GIVEN THE
PROJECTED INVERTED V SOUNDINGS WITH LARGE T/TD SPREADS. THE
ACTIVITY MAY CONTINUE ACROSS THE HEART OF THE CWA OVERNIGHT AS A LLJ
RE-DEVELOPS WITH INCREASING CONVERGENCE & WAA...FOR THIS WILL CARRY
A SLIGHT CHANCE MENTION THROUGH 15Z THURSDAY FROM WEST TO EAST.
ADDITIONAL STORMS WILL BE POSSIBLE THURSDAY AFTERNOON...WITH THE
AMPLIFIED RIDGE ATOP THE CWA...AND SUBSEQUENT WEAK DISTURBANCES
PASSING THROUGH THE FLOW.
AS FOR TEMPERATURES...HIGHS WILL REMAIN WELL ABOVE AVERAGE AS H85
T/S WARM WELL ABOVE 30C FOR MOST LOCATIONS. HIGHS ON THURSDAY WILL
TOP OUT ONCE AGAIN IN THE LOW TO MID 90S FOR MOST LOCATIONS.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 342 PM CDT WED SEP 4 2013
FOR THE MID-RANGE FORECAST...WEATHER WILL BE HOT AND DRY. MODEL
OUTPUT STATISTICS FROM THE THREE AVAILABLE BULLETINS INDICATE
ANOTHER HEAT WAVE IN THE MIDDLE RANGE OF THE FORECAST. IT SEEMS THAT
100 PLUS IS NOT OUT OF THE QUESTION FRIDAY OVER ALL OF CENTRAL AND
WESTERN NEBRASKA WITH THE HOTTEST WEATHER ALONG THE NEBRASKA-SOUTH
DAKOTA STATE LINE.
THE GFS SHOWS THE HOTTEST AIR SINKING SOUTH TO SOUTH CENTRAL AND
SOUTHWEST NEBRASKA FOR SATURDAY AS A WEAK FRONT DRIFTS ACROSS INTO
NEBRASKA...BUT THAT LASTS ONLY ONE DAY. AS THE FRONT COMES INTO
NORTHERN NEBRASKA...IT WILL GENERATE SOME LIFT. A CROSS-SECTION
THROUGH NORTHERN NEBRASKA SHOWS INSTABILITY ABOVE 700MB AND SOME
HUMIDITY 75 PERCENT OR HIGHER. HOWEVER...BELOW THAT LEVEL...THE AIR
IS FAIRLY DRY AT 40-50 PERCENT. THE RESULT IS THAT PRECIPITATION
WILL BE SPOTTY AND FAIRLY LIGHT.
IT IS NOT UNTIL MONDAY THAT SIGNIFICANT RELIEF FROM THE HOT AND DRY
WEATHER CAN BE EXPECTED. AT THAT TIME...A MODERATE FRONT WILL MOVE
THROUGH NEBRASKA. THE GFS IS ABOUT 12 HOURS FASTER WITH THE FRONT
THAN IS THE GEM AND THE 12Z ECMWF IS ABOUT SIX HOURS FASTER THAN THE
GEM. THE DIFFERENCES AMONG THE MODELS COULD HAVE AN EFFECT ON THE
TIMING OF THE PRECIPITATION AND ALSO ON THE TEMPERATURES ON TUESDAY.
STILL...THERE IS ENOUGH AGREEMENT THAT WE CAN NUDGE THE CURRENT
FORECAST TO A BLEND OF THE THREE EXTENDED MODELS. THIS SHOULD BRING
TEMPERATURES 5-15 DEGREES LOWER MONDAY OR TUESDAY AND A CHANCE FOR
PRECIPITATION...THOUGH THERE IS STILL UNCERTAINTY REGARDING THE
TIMING...AMOUNT AND EXTENT OF THE PRECIPITATION. STILL...IT DOES
APPEAR THAT THE BETTER CHANCES FOR PRECIPITATION WILL BE IN THAT
MONDAY THROUGH WEDNESDAY PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1125 PM CDT WED SEP 4 2013
TWO AREAS OF THUNDERSTORMS MOVED NORTH AND SOUTH THROUGH WRN NEB
THIS EVENING AS ADVERTISED BY THE SHORT RANGE MODELS. THE HRRR AND
RAP MODELS NOW SUGGEST THE POTENTIAL FOR ISOLATED STORM
DEVELOPMENT OVERNIGHT ACROSS NCNTL NEB EAST OF HIGHWAY 83. HOWEVER IT
LOOKS LIKE THE MODELS ARE CARRYING THE ONGOING CONVECTION TOO FAR
EAST SO THE POTENTIAL FOR STORM DEVELOPMENT IS QUESTIONABLE. IF
ANY STORMS DEVELOP...THEY SHOULD DISSIPATE BY 17Z THURSDAY.
OTHERWISE VFR IS EXPECTED THROUGH 22Z THURSDAY. THEREAFTER MORE
CONVECTION COULD DEVELOP ACROSS WRN NEB SIMILAR TO TODAY. THIS IS
SHOWN BY THE NAM WHICH FIRES OFF TSTMS ON THE LARAMIE RANGE AROUND
18Z-21Z THURSDAY WHICH COULD BEGIN AFFECTING WRN NEB AROUND 23Z-
00Z.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...JACOBS
SHORT TERM...JACOBS
LONG TERM...SPRINGER
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
349 AM CDT THU SEP 5 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 349 AM CDT THU SEP 5 2013
THE MAIN FORECAST HIGHLIGHT FOR THE SHORT TERM PERIOD IS
PRECIPITATION CHANCES.
RADAR IMAGERY AT 08Z SHOWS ONGOING SHOWER ACTIVITY ACROSS CENTRAL
NORTH DAKOTA...WITH MORE WIDESPREAD SHOWER/THUNDERSTORM ACTIVITY
OVER THE BLACK HILLS REGION OF SOUTH DAKOTA...ASSOCIATED WITH A
WEAK UPPER LEVEL IMPULSE MOVING OVER THE AREA THIS MORNING. THERE
IS A BIT OF UNCERTAINTY IN THE PRECIP FORECAST THROUGH EARLY
AFTERNOON...AS THE 00Z GFS/ECWMF ARE MORE ROBUST IN AREAL EXTENT
OF SHOWER/THUNDERSTORM COVERAGE VERSUS THE 00Z NAM/GEM AND LATEST
RUNS OF THE HRRR AND RAP...WHICH ARE MORE SPOTTY WITH COVERAGE.
CONSEQUENTLY...HAVE USED A BLEND OF GUIDANCE...LIMITING POPS TO
SLIGHT CHANCE. LIGHTNING STRIKES HAVE BEEN FAR AND FEW BETWEEN
WITH ONGOING SHOWERS...SO HAVE REMOVED THE MENTION OF THUNDER IN
WX GRIDS FOR ALL EXCEPT ACROSS THE SOUTHWEST AND FAR WEST WHERE
CAPE MAY BE MORE PLENTIFUL. IN ADDITION...HAVE INCLUDED THE
MENTION OF SPRINKLES THROUGH LATE MORNING TO REFLECT ONGOING
ACTIVITY. SHOWERS/THUNDERSTORMS SHOULD COME TO AN END BY 18Z ONCE
THE WEAK IMPULSE MOVES INTO WESTERN MINNESOTA.
WARMER TEMPERATURES ARE EXPECTED ACROSS THE AREA TODAY AS A RIDGE
AND WARMER H850 TEMPERATURES MOVE OVERHEAD. THIS WILL RESULT IN
AFTERNOON TEMPERATURES CLIMBING INTO THE UPPER 80S AND LOWER
90S...AND OVERNIGHT TEMPERATURES COOLING ONLY INTO THE 60S.
DEWPOINTS WILL ALSO BE ON THE RISE...THOUGH HEAT INDEX VALUES
SHOULD REMAIN IN THE 90S.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 349 AM CDT THU SEP 5 2013
THE MAIN FORECAST CHALLENGE FOR THE EXTENDED WILL BE THE AREAL
EXTENT AND COVERAGE OF PRECIPITATION CHANCES THIS WEEKEND. GIVEN THE
MODEL TO MODEL AND RUN TO RUN INCONSISTENCIES...CONTINUED TO FOLLOW
A BLENDED APPROACH FOR THE EXTENDED PERIOD FORECAST.
EARLY IN THE PERIOD...THE MEDIUM RANGE MODELS CONTINUE TO STRUGGLE
WITH THE EXACT TIMING AND LOCATION OF SHORTWAVES EJECTING FROM AN
UPPER LOW PROGGED TO REMAIN OVER THE PACIFIC NORTHWEST THROUGH
SATURDAY. FOR NOW CONTINUED TO FORECAST AN INCREASING POP TREND WEST
AND CENTRAL THROUGH SATURDAY AND KEPT THE EAST (TURTLE MOUNTAIN
SOUTH TO THE JAMES RIVER VALLEY) DRY THROUGH EARLY SUNDAY MORNING.
AS THE UPPER LOW FINALLY PUSHES INTO MONTANA...THUNDERSTORM CHANCES
SHOULD INCREASE ACROSS THE ENTIRE STATE SUNDAY AND SUNDAY NIGHT.
GIVEN THE EXPECTED POSITION OF THE LOW AND ATTENDANT DEEP LAYER
SHEAR/INSTABILITY PARAMETERS...SEVERE WEATHER COULD BE POSSIBLE
SUNDAY AFTERNOON/EVENING. WILL CONTINUE TO HIGHLIGHT THIS
POSSIBILITY IN THE HWO.
THE LATEST GFS/ECMWF/GEM ALL DIFFER WITH RESPECT TO THE TIMING OF
THE LOW PIVOTING ACROSS NORTH DAKOTA AND SUBSEQUENTLY DRY CONDITIONS
FILTERING INTO THE REGION. THE LATEST ECMWF IS NOW MORE PROGRESSIVE
WITH THIS FEATURE AND PIVOTS IT THROUGH THE REGION MONDAY. THE GFS
IS ABOUT 12 HOURS SLOWER WHEREAS THE GEM IS AN AVERAGE OF THE TWO.
FOR NOW KEPT POPS IN AREAWIDE MONDAY AND FORECAST A DRYING TREND
TUESDAY THROUGH WEDNESDAY AS HIGH PRESSURE BUILDS OVER THE ROCKIES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 106 AM CDT THU SEP 5 2013
VFR CONDITIONS WILL PREVAIL ACROSS ALL TAF SITES FOR THE 06Z TAF
PERIOD. SCATTERED SHOWERS CURRENTLY OVER THE NORTH CENTRAL PART OF
THE STATE WILL CONTINUE TO MOVE EAST. ADDITIONAL SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS WESTERN NORTH DAKOTA
OVER THE NEXT FEW HOURS. HOWEVER...UNCERTAINTY REMAINS TOO GREAT
TO INCLUDE ANY PREVAILING THUNDERSTORM OR SHOWER GROUP IN THE TAFS. SO
HAVE INCLUDED VCSH TO KDIK...KMOT...AND KBIS TO INDICATE POSSIBLE
TIMING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...LTH
LONG TERM...TM
AVIATION...LTH
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
400 AM EDT THU SEP 5 2013
.SYNOPSIS...
A MOISTURE-STARVED COLD FRONT WILL MOVE SOUTH THROUGH THE OHIO
VALLEY TODAY. BEHIND THE FRONT...HIGH PRESSURE WILL BUILD IN FOR
FRIDAY...WITH RELATIVELY COOL AND DRY CONDITIONS. AS THE HIGH
MOVES OFF TO THE EAST...A GRADUAL RETURN TO WARMER TEMPERATURES
WILL OCCUR OVER THE WEEKEND AND INTO NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A COLD FRONT IS CURRENTLY IDENTIFIABLE (BY WIND SHIFT) NEAR THE
BORDER WITH MICHIGAN...AND IT WILL BE MAKING ITS WAY SOUTH INTO
THE ILN CWA TODAY. A WIDE SUITE OF MODEL SOLUTIONS REFUSES TO
PRODUCE ANY QPF OUTPUT WITH THIS FEATURE...OWING MAINLY TO THE
DRY AIR MASS THAT THE FRONT IS MOVING INTO (PWAT VALUES AT OR
BELOW 1 INCH). THERE SHOULD BE SOME RESPONSE IN TERMS OF
STRATOCUMULUS DEVELOPMENT...SO SKY GRIDS NEAR THE FRONT INCREASE
TO AROUND 50 PERCENT. OTHERWISE...ASIDE FROM SOME HIGH
CLOUDS...SKIES SHOULD BE MOSTLY CLEAR.
THE TIMING OF THE TEMPERATURE TRACE TODAY LOOKS TO BE ROUGHLY
DIURNAL...EVEN AS THE FRONT MOVES THROUGH THE REGION. THE NORTH
HALF OF THE CWA MAY PEAK OUT SLIGHTLY EARLIER THAN NORMAL AND HOLD
SOMEWHAT STEADY GOING INTO THE AFTERNOON. THERE WILL BE A NNE-TO-
SSW GRADIENT...WITH THE WARMEST TEMPS IN SOME OF THE NORTHERN
KENTUCKY ILN COUNTIES. THE RAP MODEL HAS BEEN IGNORED FOR
TODAY...AS IT MIXES THROUGH 800MB AND PRODUCES TEMPERATURE VALUES
FAR TOO HIGH. OTHERWISE...THE REST OF THE MAIN SUITE OF MODELS IS
IN FAIRLY GOOD AGREEMENT ON TEMPS...WITH LOWER 80S IN THE SW AND
MID 70S IN THE NE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
ALTHOUGH THE SOUTHWARD-MOVING COLD FRONT WILL ALMOST CERTAINLY
COME THROUGH DRY (THOUGH A PATCH OR TWO OF TRACE PRECIP IS NOT
TOTALLY OUT OF THE REALM OF POSSIBILITY IN THE SOUTHERN CWA IN THE
LATE AFTERNOON)...THERE WILL BE A MARKED WIND SHIFT TO THE
NNE. THIS WILL BRING SOME STRONG COLD ADVECTION...SETTING THINGS
UP FOR A COOL FORECAST FOR TONIGHT. THE CENTER OF THE HIGH WILL BE
OVER PENNSYLVANIA...SO SOME LIGHT EASTERLY FLOW SHOULD STILL BE
PRESENT...MAKING THE RADIATIONAL COOLING CONDITIONS
NOT-QUITE-IDEAL. HOWEVER...THE DRYING AIR MASS AND CLEAR SKIES
WILL EASILY BE ENOUGH TO ALLOW TEMPS INTO THE LOWER 50S...WITH
UPPER 40S EXPECTED IN OUTLYING AREAS.
THE HIGH WILL STILL BE CLOSE ENOUGH TO INFLUENCE THE WEATHER
FRIDAY...WITH ONLY A SLIGHT CLOCKWISE TURN IN THE WIND
DIRECTION...AND NO REAL SIGN OF SURFACE WARM ADVECTION QUITE YET.
ON THE OTHER HAND...TEMPERATURES WILL BEGIN WARMING SLIGHTLY
ALOFT...LEADING TO AN INTERESTING FORECAST CHALLENGE. MODEL
SOUNDINGS ARE EXTREMELY SHALLOW IN MIXING FOR FRIDAY AFTERNOON
(GFS/NAM AT KCVG BOTH SHOWING ONLY AROUND 900MB-875MB).
HOWEVER...THE WARMING AIR JUST OFF THE SURFACE WILL MEAN THAT ONLY
A SMALL CHANGE IN MIXING HEIGHT WOULD CAUSE A MODERATE CHANGE IN
REALIZED SURFACE HIGH TEMPERATURES. FORECAST TEMPS ARE CLOSE TO A
BLEND OF THE RAW GFS/NAM...AND SLIGHTLY LOWER THAN THE ADJUSTED
MAV/MET GUIDANCE NUMBERS. HOWEVER...THOSE GUIDANCE NUMBERS WOULD
END UP LOOKING MORE CORRECT IF MIXING DOES GET HIGHER THAN
CURRENTLY ANTICIPATED.
A VEERING OF SURFACE WINDS WILL CONTINUE INTO THE WEEKEND...AS THE
SURFACE HIGH MOVES SOUTHEAST INTO THE DELMARVA REGION. AS THIS
OCCURS...RIDGING WILL BEGIN TO BUILD IN ALOFT. THIS WILL PUT THE
CWA IN A REGIME OF NORTHWEST FLOW ALOFT (EVENTUALLY SPILLING IN
SOME CLOUDS) AND SW FLOW AT THE SURFACE (WITH TEMPERATURES AND
DEWPOINTS BEGINNING TO RISE AGAIN). ANOTHER FRONT WILL MAKE ITS
WAY SOUTHWARD INTO THE OHIO VALLEY ON SATURDAY NIGHT INTO
SUNDAY...AND THOUGH IT ALSO LOOKS LIKE A FAIRLY DRY FRONT...THERE
IS ENOUGH MOISTURE TO SUPPORT SOME PRECIPITATION POTENTIAL. 00Z
GFS/ECMWF RUNS BOTH DEPICT THAT HIGH PRESSURE OVER THE GREAT LAKES
WILL VERY BRIEFLY ENTER THE PICTURE OVER THE OHIO VALLEY ON SUNDAY
NIGHT AND MONDAY...BEFORE RIDGING MOVES EAST AGAIN AND PUTS THE
CWA INTO A WARMER AND WETTER PATTERN FOR THE MIDDLE OF THE WEEK.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
AFTER SUNDAY...THE UPPER HIGH BUILDS AND NORTHWEST FLOW BECOMES
MORE WESTERLY IN OHIO VALLEY. SURFACE FLOW INCREASES FROM THE
SOUTHWEST ON TUESDAY. AN ISOLATED POPUP SHOWER COULD OCCUR DURING
THE HEATING OF THE DAY MONDAY AND AGAIN WITH THE INCREASED
MOISTURE WORKING IN TUESDAY...BUT THE LOW 20% COVERAGE WILL KEEP
MENTION OF SHOWERS OUT OF THE FORECAST.
UPPER RIDGE BREAKS DOWN AND A TROUGH APPROACHES FROM THE NORTHWEST
ON WEDNESDAY. IT ALSO COMES WITH A SURFACE COLD FRONT AND IS THE
FAVORED MECHANISM FOR THUNDERSTORM DEVELOPMENT IN THE EXTENDED
PERIOD.
HIGHS WILL REMAIN IN THE 80S AND COULD APPROACH 90 WITH ENOUGH
SUNSHINE. LOWS SHOULD STAY IN THE 60S BUT SOME UPPER 50S ARE
POSSIBLE IN CENTRAL OHIO SAT NIGHT AND FOR MOST AREAS SUN NIGHT WITH
DRIER AIR. THEY WILL PUSH BACK INTO THE MID TO UPPER 60S FOR THE
REMAINDER OF NEXT WEEK WITH THE RETURN OF SOUTHERLY FLOW.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
A MOISTURE STARVED COLD FRONT WILL DROP SOUTH FROM THE SOUTHERN
GREAT LAKES TO THE OHIO RIVER VALLEY BY MORNING. AHEAD OF THE
FRONT...ENOUGH LOW LEVEL MOISTURE AND MAINLY CLEAR SKIES/LIGHT
WINDS MAY ALLOW FOR SOME MVFR MIST TO FORM AT KILN AND KLUK WITH
PERHAPS A PERIOD OF IFR VSBYS AT KLUK BEFORE FRONTAL PASSAGE.
OTHERWISE...THE FRONT WILL BE MARKED BY A WIND SHIFT TO THE NORTH
ALONG WITH A FEW-SCT STRATOCUMULUS CLOUDS NEAR THE NORTHERN TAF
SITES.
FOR LATER TODAY...THE FRONT WILL CONTINUE SOUTH OF THE OHIO RIVER.
SOME POST FRONTAL MOISTURE AND CAA WILL RESULT IN DIURNALLY DRIVEN
SCT-BKN CUMULUS CLOUDS.
FOR TONIGHT...A SPRAWLING AREA OF HIGH PRESSURE WILL BUILD
SOUTH INTO THE NEW ENGLAND...MID ATLANTIC AND OHIO VALLEY REGION.
SKIES WILL BECOME MOSTLY CLEAR AS WINDS SHIFT TO THE EAST/NORTHEAST...
ALLOWING DRIER AIR TO FILTER BACK INTO THE AREA.
OUTLOOK...NO SIGNIFICANT WEATHER IS EXPECTED.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HATZOS
NEAR TERM...HATZOS
SHORT TERM...HATZOS
LONG TERM...FRANKS
AVIATION...HICKMAN
AREA FORECAST DISCUSSION...UPDATE
NWS PORTLAND OR
1110 PM PDT WED SEP 4 2013
.SYNOPSIS...AN UPPER LEVEL LOW WILL CONTINUE THE THREAT FOR SHOWERS
AND THUNDERSTORMS TONIGHT THROUGH THURSDAY. LOCALIZED HEAVY RAINFALL
IS EXPECTED THURSDAY AND FRIDAY AS THE LOW MOVES OVER THE AREA.
SHOWERS WILL DECREASE FRIDAY EVENING AS THE HIGH PRESSURE BEGINS TO
BUILD BEHIND THE LOW. DRIER WEATHER IS EXPECTED THIS WEEKEND WITH
WARMING AND CONTINUED DRY WEATHER EXPECTED NEXT WEEK.
&&
,MESOSCALE UPDATE...SHOWERS AND TSTORMS HAVE INCREASED IN RESPONSE
TO THE UPPER SHORTWAVE OFF THE COAST IN AN AREA OF UPPER LEVEL
DIVERGENCE/LIFT ON THE LEFT EXIT OF A STRONG HIGH LEVEL JET. EXPECT
THESE TO CONTINUE TO SPREAD NORTH. LATEST HRRR STILL SUGGESTING THIS
MAIN BAND WILL HEAD NORTHWEST TOWARD THE NORTH OREGON COAST
RANGE/COAST...THOUGH ADDITIONAL ACTIVITY IS POSSIBLE FURTHER EAST
TOWARD THE PORTLAND/VANCOUVER METRO AREAS...AS A FEW CELLS HAVE BEEN
POPPING UP OUTSIDE THE MAIN BAND. KMD
.EVENING UPDATE...DOPPLER RADAR THIS EVENING SHOWS LIGHT ECHOES OVER
THE CASCADES AND FOOTHILLS. THESE ECHOES HAVE BEEN PRIMARILY VIRGA
WITH THE ONLY REPORT OF RAIN REACHING THE GROUND COMING FROM VIDA
BRIEFLY THIS EVENING. THIS MID LEVEL CLOUD DECK SHOULD CONTINUE TO
PUSH EAST AND NORTH OF THE REGION AS IT WEAKENS OVERNIGHT.
FOG HAS ALSO DEVELOPED ALONG THE CENTRAL OREGON COAST THIS EVENING SO
FOG WAS ADDED TO THE FORECAST WHERE IT SHOULD LINGER INTO THURSDAY
MORNING.
OUR FOCUS IS QUICKLY TURNING TO THE UPPER LEVEL LOW PRESSURE SPINNING
INSIDE 130W. A VORT MAX LOCATED ON THE SOUTHEAST SIDE OF THE UPPER
LEVEL LOW PRESSURE EARLIER THIS EVENING MOVED NORTHWARD OFF THE
COAST WITH VERY LITTLE IMPACT. HOWEVER...ANOTHER MORE NOTABLE
VORT MAX IS CURRENTLY ROUNDING THE BASE OF THE TROUGH.
UNFORTUNATELY...THIS FEATURE IS EXPECTED TO MOVE INTO SOUTHWESTERN
OREGON OVERNIGHT. NONETHELESS...THIS FEATURE WILL WRAP AROUND THE
APPROACHING LOW PRESSURE CLIPPING OUR SOUTHEASTERN ZONES TOWARDS
THURSDAY MORNING...POSSIBLY AIDING IN CONVECTIVE DEVELOPMENT. IN THE
MEANTIME...THE CWA WILL BE UNDER AN INCREASINGLY DIFFLUENT FLOW
ALOFT WITH NEGATIVE 700-500MB THETAE LAPSE RATES EXPANDING
NORTHWESTWARD ACROSS MUCH OF THE AREA. THE RAP SUGGESTS THE BEST
INSTABILITY WILL BE ALONG AN AXIS EXTENDING BETWEEN EUGENE AND
ASTORIA OVERNIGHT...WITH PERHAPS ANOTHER AXIS EXTENDING INTO THE
SOUTHWEST WASHINGTON CASCADES FROM CENTRAL OREGON. IN FACT...CLOUDS
IN THE PAST HOUR OR SO ARE BEGINNING TO EXPAND IN AREAL
COVERAGE...AND ARE COOLING SLIGHTLY BETWEEN REEDSPORT...EUGENE AND
ROSEBURG...INCREASING CONFIDENCE THE HRRR/RAP IS ONTO SOMETHING. AS
A RESULT...POPS WERE INCREASED IN THESE REGIONS OVERNIGHT WITH
CHANCE WORDING OF THUNDERSTORMS. ELSEWHERE...POPS WERE KEPT LOWER
WITH ONLY SLIGHT CHANCE WORDING FOR THUNDERSTORMS DUE TO THE
INHERENT UNCERTAINTY IN THIS TYPE OF PATTERN.
GIVEN PWATS ARE TWO TO THREE STANDARD DEVIATIONS ABOVE
NORMAL...EXPECT RAIN TO BE LOCALLY HEAVY FOR THIS TIME OF YEAR
ESPECIALLY WHERE SHOWERS/THUNDERSTORMS TRAIN. HOWEVER...THE IMPACTS
WILL GENERALLY BE LOCAL IN NATURE AND LIMITED TO URBAN ENVIRONMENTS
AND SMALL STREAMS SO NO FLOOD RELATED PRODUCTS APPEAR NECESSARY AT
THIS POINT IN TIME. /NEUMAN
.LONG TERM...SATURDAY EVENING THROUGH WEDNESDAY...
AFTER THE FALL LIKE WEATHER EXPECTED OVER THE NEXT COUPLE OF
DAYS...IT APPEARS THAT SUMMER WILL MAKE ITS RETURN IN THE EXTENDED
PERIOD. THE CLOSED LOW THAT IS IMPACTING THE REGION THIS WEEK IS
MODELED TO BE EJECTED INTO THE ROCKIES DURING THE SAT NIGHT INTO
SUNDAY TIMEFRAME. THIS WILL OPEN THE DOOR FOR A STRONG LATE SEASON
RIDGE TO BUILD INTO THE PAC NW NEXT WEEK. THE LATEST MEDIUM RANGE
MODELS INDICATE THAT 500 MB HEIGHTS WILL NEAR 590 DM OVER THE
REGION...WITH 850 MB TEMPS NEAR 20C BY TUE OR WED. MEANWHILE A
THERMAL INDUCED SURFACE TROUGH IS PROGGED TO BUILD ALONG THE
COAST...BRINGING AN EASTERLY COMPONENT TO THE LOW LEVEL FLOW.
THUS...IT IS LOOKING MORE AND MORE LIKELY THAT WE WILL SEE A
SIGNIFICANT WARM UP NEXT WEEK. HIGH TEMPS WERE BUMPED UP INTO THE
UPPER 80S FOR THE INTERIOR LOWLANDS FOR BOTH TUE AND WED. THE
OFFSHORE FLOW PATTERN WOULD ALSO ALLOW THE COAST TO SEE SOME OF THEIR
WARMEST TEMPERATURES OF THE SEASON.
&&
.AVIATION...IFR CONDITIONS ALONG THE CENTRAL OREGON COAST WILL
LIKELY PERSIST FOR MUCH OF THE NIGHT. FURTHER NORTH MVFR DECKS
HAVE BEEN GOING IN AND OUT NEAR KAST. EXPECT THIS TREND TO
CONTINUE OVERNIGHT WITH CONFIDENCE IN ANY PARTICULAR CONDITION
DOMINATING NOT TERRIBLY HIGH. ACROSS THE INTERIOR...CIGS REMAIN
IN THE 3.5 TO 5KFT RANGE...BUT MAY GRADUALLY LOWER THROUGH THE
NIGHT. INSTABILITY ALOFT SHOULD LEAD TO INCREASING SHOWERS AND
POSSIBLY SOME THUNDERSTORMS TONIGHT INTO THURSDAY. THIS INFLUX OF
LOW LEVEL MOISTURE SHOULD AID IN CONDITIONS LOWERING TO MVFR FOR
MOST INTERIOR SITES LATE TONIGHT THROUGH THURSDAY MORNING.
KPDX AND APPROACHES...VFR CONDITIONS THIS EVENING SHOULD GIVE WAY
TO MVFR CIGS LATE TONIGHT INTO THURSDAY MORNING AS SHOWERS
INCREASE. THERE IS A SLIGHT CHANCE A THUNDERSTORM COULD IMPACT
THE TERMINAL AFTER 09Z TONIGHT. /NEUMAN
&&
.MARINE...RATHER BENIGN WIND AND SEA CONDITIONS WILL CONTINUE
THROUGH THE END OF THE WORK WEEK. HIGH PRESSURE OVER THE
NORTHEAST PACIFIC OCEAN AND THERMAL LOW PRESSURE OVER NORTHERN
CALIFORNIA WILL STRENGTHEN OVER THE WEEKEND...RESULTING IN SOME
LATE AFTERNOON AND EVENING GUSTY 25 KT WINDS WITH SEAS RUNNING 4
TO 6 FT. SEAS LOOK TO REMAIN UNDER 10 FT NEXT WEEK. /NEUMAN
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WA...NONE.
PZ...NONE.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION...UPDATE
NWS PORTLAND OR
905 PM PDT WED SEP 4 2013
.SYNOPSIS...AN UPPER LEVEL LOW WILL CONTINUE THE THREAT FOR SHOWERS
AND THUNDERSTORMS TONIGHT THROUGH THURSDAY. LOCALIZED HEAVY RAINFALL
IS EXPECTED THURSDAY AND FRIDAY AS THE LOW MOVES OVER THE AREA.
SHOWERS WILL DECREASE FRIDAY EVENING AS THE HIGH PRESSURE BEGINS TO
BUILD BEHIND THE LOW. DRIER WEATHER IS EXPECTED THIS WEEKEND WITH
WARMING AND CONTINUED DRY WEATHER EXPECTED NEXT WEEK.
&&
.EVENING UPDATE...DOPPLER RADAR THIS EVENING SHOWS LIGHT ECHOES OVER
THE CASCADES AND FOOTHILLS. THESE ECHOES HAVE BEEN PRIMARILY VIRGA
WITH THE ONLY REPORT OF RAIN REACHING THE GROUND COMING FROM VIDA
BRIEFLY THIS EVENING. THIS MID LEVEL CLOUD DECK SHOULD CONTINUE TO
PUSH EAST AND NORTH OF THE REGION AS IT WEAKENS OVERNIGHT.
FOG HAS ALSO DEVELOPED ALONG THE CENTRAL OREGON COAST THIS EVENING SO
FOG WAS ADDED TO THE FORECAST WHERE IT SHOULD LINGER INTO THURSDAY
MORNING.
OUR FOCUS IS QUICKLY TURNING TO THE UPPER LEVEL LOW PRESSURE SPINNING
INSIDE 130W. A VORT MAX LOCATED ON THE SOUTHEAST SIDE OF THE UPPER
LEVEL LOW PRESSURE EARLIER THIS EVENING MOVED NORTHWARD OFF THE
COAST WITH VERY LITTLE IMPACT. HOWEVER...ANOTHER MORE NOTABLE
VORT MAX IS CURRENTLY ROUNDING THE BASE OF THE TROUGH.
UNFORTUNATELY...THIS FEATURE IS EXPECTED TO MOVE INTO SOUTHWESTERN
OREGON OVERNIGHT. NONETHELESS...THIS FEATURE WILL WRAP AROUND THE
APPROACHING LOW PRESSURE CLIPPING OUR SOUTHEASTERN ZONES TOWARDS
THURSDAY MORNING...POSSIBLY AIDING IN CONVECTIVE DEVELOPMENT. IN THE
MEANTIME...THE CWA WILL BE UNDER AN INCREASINGLY DIFFLUENT FLOW
ALOFT WITH NEGATIVE 700-500MB THETAE LAPSE RATES EXPANDING
NORTHWESTWARD ACROSS MUCH OF THE AREA. THE RAP SUGGESTS THE BEST
INSTABILITY WILL BE ALONG AN AXIS EXTENDING BETWEEN EUGENE AND
ASTORIA OVERNIGHT...WITH PERHAPS ANOTHER AXIS EXTENDING INTO THE
SOUTHWEST WASHINGTON CASCADES FROM CENTRAL OREGON. IN FACT...CLOUDS
IN THE PAST HOUR OR SO ARE BEGINNING TO EXPAND IN AREAL
COVERAGE...AND ARE COOLING SLIGHTLY BETWEEN REEDSPORT...EUGENE AND
ROSEBURG...INCREASING CONFIDENCE THE HRRR/RAP IS ONTO SOMETHING. AS
A RESULT...POPS WERE INCREASED IN THESE REGIONS OVERNIGHT WITH
CHANCE WORDING OF THUNDERSTORMS. ELSEWHERE...POPS WERE KEPT LOWER
WITH ONLY SLIGHT CHANCE WORDING FOR THUNDERSTORMS DUE TO THE
INHERENT UNCERTAINTY IN THIS TYPE OF PATTERN.
GIVEN PWATS ARE TWO TO THREE STANDARD DEVIATIONS ABOVE
NORMAL...EXPECT RAIN TO BE LOCALLY HEAVY FOR THIS TIME OF YEAR
ESPECIALLY WHERE SHOWERS/THUNDERSTORMS TRAIN. HOWEVER...THE IMPACTS
WILL GENERALLY BE LOCAL IN NATURE AND LIMITED TO URBAN ENVIRONMENTS
AND SMALL STREAMS SO NO FLOOD RELATED PRODUCTS APPEAR NECESSARY AT
THIS POINT IN TIME. /NEUMAN
.LONG TERM...SATURDAY EVENING THROUGH WEDNESDAY...
AFTER THE FALL LIKE WEATHER EXPECTED OVER THE NEXT COUPLE OF
DAYS...IT APPEARS THAT SUMMER WILL MAKE ITS RETURN IN THE EXTENDED
PERIOD. THE CLOSED LOW THAT IS IMPACTING THE REGION THIS WEEK IS
MODELED TO BE EJECTED INTO THE ROCKIES DURING THE SAT NIGHT INTO
SUNDAY TIMEFRAME. THIS WILL OPEN THE DOOR FOR A STRONG LATE SEASON
RIDGE TO BUILD INTO THE PAC NW NEXT WEEK. THE LATEST MEDIUM RANGE
MODELS INDICATE THAT 500 MB HEIGHTS WILL NEAR 590 DM OVER THE
REGION...WITH 850 MB TEMPS NEAR 20C BY TUE OR WED. MEANWHILE A
THERMAL INDUCED SURFACE TROUGH IS PROGGED TO BUILD ALONG THE
COAST...BRINGING AN EASTERLY COMPONENT TO THE LOW LEVEL FLOW.
THUS...IT IS LOOKING MORE AND MORE LIKELY THAT WE WILL SEE A
SIGNIFICANT WARM UP NEXT WEEK. HIGH TEMPS WERE BUMPED UP INTO THE
UPPER 80S FOR THE INTERIOR LOWLANDS FOR BOTH TUE AND WED. THE
OFFSHORE FLOW PATTERN WOULD ALSO ALLOW THE COAST TO SEE SOME OF THEIR
WARMEST TEMPERATURES OF THE SEASON.
&&
.AVIATION...IFR CONDITIONS ALONG THE CENTRAL OREGON COAST WILL
LIKELY PERSIST FOR MUCH OF THE NIGHT. FURTHER NORTH MVFR DECKS
HAVE BEEN GOING IN AND OUT NEAR KAST. EXPECT THIS TREND TO
CONTINUE OVERNIGHT WITH CONFIDENCE IN ANY PARTICULAR CONDITION
DOMINATING NOT TERRIBLY HIGH. ACROSS THE INTERIOR...CIGS REMAIN
IN THE 3.5 TO 5KFT RANGE...BUT MAY GRADUALLY LOWER THROUGH THE
NIGHT. INSTABILITY ALOFT SHOULD LEAD TO INCREASING SHOWERS AND
POSSIBLY SOME THUNDERSTORMS TONIGHT INTO THURSDAY. THIS INFLUX OF
LOW LEVEL MOISTURE SHOULD AID IN CONDITIONS LOWERING TO MVFR FOR
MOST INTERIOR SITES LATE TONIGHT THROUGH THURSDAY MORNING.
KPDX AND APPROACHES...VFR CONDITIONS THIS EVENING SHOULD GIVE WAY
TO MVFR CIGS LATE TONIGHT INTO THURSDAY MORNING AS SHOWERS
INCREASE. THERE IS A SLIGHT CHANCE A THUNDERSTORM COULD IMPACT
THE TERMINAL AFTER 09Z TONIGHT. /NEUMAN
&&
.MARINE...RATHER BENIGN WIND AND SEA CONDITIONS WILL CONTINUE
THROUGH THE END OF THE WORK WEEK. HIGH PRESSURE OVER THE
NORTHEAST PACIFIC OCEAN AND THERMAL LOW PRESSURE OVER NORTHERN
CALIFORNIA WILL STRENGTHEN OVER THE WEEKEND...RESULTING IN SOME
LATE AFTERNOON AND EVENING GUSTY 25 KT WINDS WITH SEAS RUNNING 4
TO 6 FT. SEAS LOOK TO REMAIN UNDER 10 FT NEXT WEEK. /NEUMAN
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WA...NONE.
PZ...NONE.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1135 PM CDT WED SEP 4 2013
.DISCUSSION...
/See below for aviation discussion/
&&
.AVIATION...
VFR next 24 hours. Isolated afternoon and evening thunderstorms are
possible Thursday afternoon and evening at KSOA, KJCT, and KBBD.
Coverage however is expected to be too low for mention in TAFS.
Light winds tonight become southeast to south at 10 mph or less
Thursday.
04
&&
.PREV DISCUSSION... /ISSUED 936 PM CDT WED SEP 4 2013/
.UPDATE...
Most of the convective activity that developed this afternoon across
West Central TX has dissipated. However, we are seeing storms over
the I-35 corridor from Waco to near San Antonio holding together,
continuing a general westerly trend. While most of this activity
will continue to weak, the HRRR is suggesting additional shower
development tonight across mainly the Heartland Counties overnight
(namely Brown, Coleman, San Saba, and McCulloch Counties). I trimmed
PoPs back across the southwest counties for the remainder of the
overnight period and extended the mention of isolated thunderstorms
through 08z to account for this possibility.
Dewpoints across the Big Country tanked into the mid 30s this
afternoon due to strong subsidence and associated dry air mixing to
the surface. This brought precipitable water values below 1 inch
across the northwest half of the forecast area with pwats near 1.4
inches across the southeast. The bulk of the deeper moisture will
remain to our south and east through tomorrow but we will see
similar pwat values again tomorrow, suggesting the potential for
additional diurnal convection, especially across the southern half
of the area. For tonight, dewpoints will be slow to recover and
should allow temperatures to fall into the upper 60s, especially in
areas where cloud cover will be sparse. Min temps were updated
accordingly.
Johnson
&&
.PREV DISCUSSION... /ISSUED 552 PM CDT WED SEP 3 2013/
DISCUSSION...
/See below for aviation discussion/
AVIATION...
VFR next 24 hours. Isolated thunderstorms possible Thursday afternoon
south of the I-20 corridor. However potential is too low to include
in TAFS.
04
PREV DISCUSSION... /ISSUED 352 PM CDT WED SEP 3 2013/
SHORT TERM...(Tonight and Thursday)
Isolated showers and a few storms possible this afternoon and early
this evening, and again on Thursday afternoon and evening.
West Central Texas remains on the edge of the large upper level high
pressure dominating much of the southern plains. Abundant moisture
with east winds prevailing at most levels will combine with
afternoon temperatures climbing into the mid 90s to produce a few
storms. These storms will mainly be along the edge of the ridge axis
itself, across the southern and eastern portions of the area. Have
inserted a mention of storms into the forecast itself through the
early evening hours tonight and again for a few hours Thursday
afternoon.
Otherwise, clouds having an impact on temperatures this afternoon
and expect of the same tomorrow. Readings in the mid and upper 90s
across the northern half of the area, while the southern half of the
area runs in the lower 90s.
LONG TERM...(Thursday Night through Wednesday)
The upper ridge will remain centered over the Southern Plains
through this weekend with above normal temperatures continuing.
Cannot rule out isolated convection developing again across far
southern counties Friday afternoon/early evening so will include
this potential this forecast cycle.
By early next week, a short wave trough will move east across
the Northern Plains and across the Great Lakes region by mid week.
This system will push the upper high east of the area for the latter
part of the extended period and allow afternoon highs to cool a few
degrees. The upper high will be situated over the Ohio and Tennessee
Valleys, which will result in deeper low to mid level southeasterly
flow across the area. This pattern would be more favorable for
diurnal convection, especially across southeast sections Monday
through Wednesday of next week. Kept the forecast dry for now given
uncertainties this far out and wait to see how models perform in
subsequent runs before considering adding POPS to the
forecast.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 68 96 71 96 71 / 0 5 5 5 5
San Angelo 69 95 69 96 70 / 5 10 10 10 10
Junction 68 95 69 95 70 / 10 10 10 10 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
25
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
346 AM CDT THU SEP 5 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 346 AM CDT THU SEP 5 2013
CURRENT WATER VAPOR COMBINED WITH RAP 500MB ANALYSIS SHOWS A HIGHLY
AMPLIFIED RIDGE IN PLACE JUST EAST OF THE COLORADO/NORTHERN/CANADIAN
ROCKIES WITH OUR AREA IN NORTHWEST FLOW ALOFT. AT THE SURFACE...A
BROAD AREA OF HIGH PRESSURE EXTENDED SOUTHWARD OUT OF ONTARIO CANADA
THROUGH THE UPPER MISSISSIPPI RIVER VALLEY REGION...INTO THE MID AND
SOUTHERN MISSISSIPPI RIVER REGION. EAST/NORTHEAST SURFACE FLOW OFF LAKE
MICHIGAN WAS COMBINING WITH A RATHER HUMID LOWER BOUNDARY LAYER TO
PRODUCE AN EXPANDING STRATUS FIELD ACROSS SOUTHEAST WI/SOUTH CENTRAL
WI. THIS STRATUS MAY PROVE TO BE PROBLEMATIC TODAY ACROSS THE
SOUTHEAST PORTION OF THE FORECAST AREA. OTHERWISE...TEMPERATURES
ACROSS THE AREA EARLY THIS MORNING RANGED FROM THE 40S ACROSS
NORTHERN WI...TO THE MIDDLE AND UPPER 60S ALONG AND SOUTH OF THE
I-94 CORRIDOR.
FOR TODAY...WILL BE WATCHING THIS AFOREMENTIONED STRATUS CLOSELY.
RAP SOUNDINGS SHOW THIS CLOUD THINNING AS THE MORNING PROGRESSES
FROM NORTHEAST TO SOUTHWEST AS HIGH PRESSURE BUILDS OVER THE GREAT
LAKES AND DRIER AIR GETS ENTRAINED INTO THE BOUNDARY LAYER. THE NAM
AND RAP ARE HINTING AT SOME -SHRA ALONG AND WEST OF TE MISSISSIPPI
RIVER THIS AFTERNOON IN DAYTIME HEATING. HOWEVER...THERE IS NO
FORCING MECHANISM TO TRIGGER THESE SHOWERS. WILL KEEP DRY FOR NOW
BUT WARRANTS WATCHING. WITH LIGHT EASTERLY WINDS...LOOK FOR HIGH
TEMPERATURES TODAY IN THE MIDDLE 70S TO THE LOWER 80S.
ATTENTION THEN TURNS TO NORTHWEST FLOW ALOFT TONIGHT WITH AN
EMBEDDED/WEAKENING SHORTWAVE TROUGH HEADING SOUTHEAST THROUGH THE
NORTHERN PLAINS INTO MN. NAM SHOWING AN INCREASING CORRIDOR OF
850-700MB ISENTROPIC LIFT AND MOISTURE TRANSPORT AHEAD OF THIS WAVE
ACROSS THE PLAINS INTO NORTHWEST MN. PLAN ON SOME INCREASE IN
MID-LEVEL CLOUDS/ACCAS ACROSS PORTIONS OF SOUTHEAST MN INTO
NORTHWEST WI ON THE EASTERN FRINGES OF THIS FORCING. ANY SHRA ACTIVITY IS
EXPECTED TO STAY NORTHWEST OF THE AREA TOWARD THE BETTER MOISTURE
TRANSPORT. ANOTHER MITIGATING FACTOR IN SHOWER CHANCES ACROSS
NORTHWEST IS THE VERY-HIGH BASED NATURE OF THE CLOUDS AND DRY LOWER
LEVELS FOR EVAPORATION OF SHOWERS FROM THESE CLOUDS...WITH JUST
VIRGA EXPECTED. BASED ON THIS SIGNAL...WENT WITH A DRY FORECAST
OVERNIGHT. OTHERWISE...SOUTHERLY AIRFLOW AND INCREASING DEW POINTS
SHOULD KEEP OVERNIGHT LOWS UP IN THE 50S TO LOWER 60S.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 346 AM CDT THU SEP 5 2013
ON FRIDAY...WILL BE WATCHING A SURFACE COLD FRONT PUSHING SOUTHEAST
OUT OF CANADA INTO NORTHERN WI THROUGH CENTRAL MN BY LATE IN THE
AFTERNOON. CORRIDOR OF BEST 850-700MB MOISTURE TRANSPORT AND
ISENTROPIC LIFT STAYS NORTH OF THE AREA WITH JUST SOME INCREASE IN
MID/HIGH CLOUDS EXPECTED ACROSS OUR AREA. OF NOTE WILL BE INCREASING
SOUTHWEST WINDS AND WARM AIR ADVECTION INTO OUR AREA WITH 925MB
TEMPERATURE INCREASING INTO THE 25-28C BY AFTERNOON. THIS SHOULD
YIELD HIGH TEMPERATURES IN THE MID-UPPER 80S...WITH A COUPLE
LOCATIONS FLIRTING WITH THE 90 DEGREE MARK.
FOR FRIDAY NIGHT THROUGH SATURDAY...LOOK FOR THE COLD FRONT TO SINK
SLOWLY SOUTHEAST ACROSS THE AREA. CONTINUED 850-700MB MOISTURE
TRANSPORT/ISENTROPIC LIFT AND WEAK CONVERGENCE ALONG THIS FRONTAL
BOUNDARY SHOULD BE SUFFICIENT FOR ISOLATED-SCATTERED
SHOWER/THUNDERSTORMS. OF NOTE THOUGH IS A FAIRLY STRONG CAP ON
SATURDAY INDICATED BY THE NAM SOUNDING WHICH MAY LIMIT CONVECTION OR
KEEP IT VERY ELEVATED AND SPARSE IN NATURE. EVEN WITH CLOUDS...
LOOKING FOR HIGHS IN THE 80S. LINGERING SHOWER/THUNDERSTORM CHANCES
WILL BE SEEN SATURDAY NIGHT MAINLY SOUTH OF I-90 AS THE FRONT EXITS
THE AREA.
SUNDAY LOOKS DRY AND SLIGHTLY COOLER AS HIGH PRESSURE BUILDS IN FROM
ONTARIO CANADA INTO THE GREAT LAKES REGION.
LOOK FOR THE HIGH TO SLIDE INTO THE NORTHEAST U.S. SUNDAY NIGHT AS
LOW PRESSURE PUSHES OUT OF THE INTERMOUNTAIN WEST INTO THE NORTHERN
PLAINS. THIS PUSHES A WARM FRONT INTO MN/IA AFTER MIDNIGHT WITH
INCREASING 850MB MOISTURE TRANSPORT NOSING INTO THE AREA FOR A
CHANCE OF SHOWERS AND THUNDERSTORMS. SHOWER AND THUNDERSTORM CHANCES
CONTINUE THROUGH MONDAY AS THE WARM FRONT PUSHES THROUGH THE AREA.
WILL HAVE TO WATCH FOR A SEVERE THREAT DURING THIS TIME FRAMES AS
WELL WITH THE GFS INDICATING 1000-1500J/KG 0-1KM MLCAPE WITH AROUND
35KT OF 0-3KM SHEAR SUNDAY NIGHT AND 2000-2500J/KG AND 25-30KT 0-3KM
SHEAR ON MONDAY. PLAN ON HIGHS IN THE MID 70S/LOWER 80S ON
SUNDAY...AND UPPER 70S/MIDDLE 80S MONDAY.
THE GFS AND ECMWF SHOW A COLD FRONT PUSHING INTO THE AREA MONDAY
NIGHT AND HANGING UP ACROSS THE AREA THROUGH WEDNESDAY FOR A
CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS. HIGHS TUESDAY ARE
EXPECTED TO TOP OFF AGAIN IN THE 80S...COOLING SLIGHTLY ON WEDNESDAY
INT THE UPPER 70S TO MIDDLE 80S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT
1143 PM CDT WED SEP 4 2013
THE MAIN FOCUS AT THE TAF SITES IS WITH THE POTENTIAL DEVELOPMENT
OF MVFR TO IFR STRATUS OVERNIGHT INTO TOMORROW MORNING. THIS
STRATUS HAS STARTED TO FORM ACROSS PORTIONS OF EASTERN WISCONSIN
OVER THE PAST FEW HOURS. SOME OF THESE MID LEVEL CLOUDS IN THE
3-6KFT RANGE HAVE SNUCK INTO WESTERN WISCONSIN ALREADY AND WILL
LIKELY PERSIST INTO TOMORROW. THE QUESTION IS IF/WHEN THE
MVFR/IFR STRATUS WILL MAKE IT INTO LSE/RST. WITH THE LOW STRATUS
STILL ALONG LAKE MICHIGAN AND THE LAST FEW RUNS OF THE RAP MODEL
SHOWING THIS HIGHER RH GETTING IN LATER...HAVE DECIDED TO KEEP THE
LOW CONDITIONS IN THE TAF SITES...BUT DELAY IT A FEW HOURS THIS
MORNING. THESE CONDITIONS SHOULD QUICKLY IMPROVE THROUGH THE LATE
MORNING HOURS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM...DAS
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1143 PM CDT WED SEP 4 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 337 PM CDT WED SEP 4 2013
MAIN FORECAST CONCERNS IN THE SHORT TERM ARE ON TEMPERATURES AND
CLOUD COVER TONIGHT INTO THURSDAY MORNING.
LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED RIDGING
ACROSS ANCHORED OVER THE ROCKIES. TWO UPPER LOWS NOTED...ONE
CENTERED OVER THE EASTERN SHORE OF HUDSON BAY...AND THE OTHER WAS
JUST EDGING INTO THE PACIFIC NORTHWEST. A WEAK COLD FRONT
STRETCHED FROM CENTRAL MINNESOTA ACROSS CENTRAL WISCONSIN EAST
THROUGH NORTHERN LOWER MICHIGAN AND WAS SLOWLY DRIFTING SOUTH.
THERE HAS NOT BEEN ANY PRECIPITATION ASSOCIATED WITH THE FRONT
JUST A SLIGHT INCREASE IN CLOUD COVER.
SURFACE HIGH PRESSURE WILL BUILD INTO THE FORECAST AREA TONIGHT AS
THE COLD FRONT SLIDES SOUTH INTO CENTRAL IOWA AND SOUTHERN ILLINOIS.
THE STRATUS CURRENTLY OVER NORTHERN WISCONSIN...SLIPS SOUTHWEST
TONIGHT. LINGERING MOISTURE CENTERED AROUND 850 MB...WITH AN
ADDITIONAL POCKET LOCATED IN THE 700-450 MB LAYER...MAY BE ENOUGH TO
GENERATE SOME CLOUD COVER TONIGHT OVER NORTHEAST IOWA....SOUTHEAST
MINNESOTA...AND SOUTHWEST WISCONSIN. FORECAST SOUNDINGS SUGGEST THE
LOWER LEVEL MOISTURE WILL DRY OUT AS THE HIGH BUILDS IN. IF THE
CLOUD COVER LINGERS IT WILL HAVE AN IMPACT ON FOG POTENTIAL AND
TEMPERATURES OVERNIGHT. PLAN ON PARTLY CLOUDY TO MOSTLY CLEAR SKIES
TONIGHT WITH LOW TEMPERATURES RANGING FROM THE UPPER 30S TO LOWER 40S
OVER NORTHERN WISCONSIN TO THE MID TO UPPER 50S ACROSS NORTHEAST
IOWA.
HIGH PRESSURE WILL BE IN CONTROL ACROSS THE REGION ON THURSDAY
PROVIDING DRY AND QUIET WEATHER. THE MAIN CONCERN WILL BE ON
AFTERNOON DEWPOINTS...ESPECIALLY CLOSER TO THE CENTER OF THE HIGH
OVER CENTRAL INTO NORTH CENTRAL WISCONSIN. FORECAST SOUNDINGS SHOW
DRY AIR ALOFT WITH DEEP MIXING TO NEARLY 875 MB. LOOKING UPSTREAM
ACROSS UPPER MICHIGAN AND SOUTHERN ONTARIO...DEWPOINTS ARE ONLY IN
THE UPPER 30S TO LOWER 40S AND THIS AIR IS ADVECTING SOUTHWARD. HAVE
LOWERED AFTERNOON DEWPOINTS INTO THE LOWER 40S OVER WEST CENTRAL
THROUGH CENTRAL WISCONSIN WHERE DEEP MIXING SHOULD EASILY YIELD THESE
AFTERNOON VALUES. THIS WOULD PRODUCE RELATIVE HUMIDITY VALUES IN
THE 27 TO 30 PERCENT RANGE. THERE WILL NOT BE MUCH WIND UNDER THE
HIGH WITH WIND MAINLY LIGHT AND VARIABLE AT 5 MPH OR LESS OVER THESE
AREA. OTHERWISE...PLAN ON SKIES RANGING FROM PARTLY TO MOSTLY CLOUDY
OVER SOUTHEAST MINNESOTA INTO NORTHEAST IOWA...TO MOSTLY SUNNY OVER
NORTH CENTRAL WISCONSIN. A WEAK SHORTWAVE LOOKS TO MOVE ACROSS AREAS
ALONG AND WEST OF THE MISSISSIPPI RIVER WITH THE MAIN IMPACT BEING
AN INCREASE IN CLOUD COVER.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 337 PM CDT WED SEP 4 2013
THE HIGH WILL SLIDE EAST INTO THE EASTERN GREAT LAKES THURSDAY NIGHT
INTO FRIDAY. A COLD FRONT IS EXPECTED TO PUSH INTO NORTHWEST
MINNESOTA AND EASTERN SOUTH DAKOTA BY FRIDAY AFTERNOON. SOUTHERLY
FLOW WILL INCREASE ACROSS THE AREA ON FRIDAY AS THE FRONT APPROACHES
HELPING TO USHER IN A WARMER AND SLIGHTLY MORE HUMID AIRMASS. 925 MB
TEMPERATURES WARM TO AROUND 25 ACROSS WESTERN AND CENTRAL WISCONSIN
AND TO THE UPPER 20S ACROSS PORTIONS OF NORTHEAST IOWA AND SOUTHEAST
MINNESOTA. HIGH TEMPERATURES ARE EXPECTED TO WARM INTO THE MID
80S...WITH A FEW UPPER 80S POSSIBLE ALONG THE MISSISSIPPI RIVER
VALLEY AND CLOSER TO THE INTERSTATE 35 CORRIDOR. FORECAST MODELS ARE
ADVERTISING A WEAK SHORTWAVE MOVING ACROSS THE EASTERN DAKOTAS AND
PUSHING INTO THE UPPER MISSISSIPPI RIVER VALLEY LATE THURSDAY NIGHT
INTO EARLY FRIDAY MORNING. 850 MB MOISTURE TRANSPORT IS WEAK AND
FOCUSED INTO SOUTHWEST MINNESOTA AND WESTERN IOWA THURSDAY EVENING
THEN ATTEMPTS TO SHIFT EAST INTO THE AREA EARLY FRIDAY MORNING.
THERE ISN/T MUCH UPPER LEVEL SUPPORT FOR PRECIPITATION SO DECIDED TO
MAINTAIN A DRY FORECAST DURING THIS TIMEFRAME. THE FRONT IS EXPECTED
TO PUSH SOUTHEAST FRIDAY NIGHT INTO SATURDAY POSSIBLY INTERACTING
WITH WEAK UPPER LEVEL IMPULSES IN NORTHWEST FLOW ALOFT. THIS WILL
BRING SLIGHT CHANCES FOR SHOWERS AND STORMS TO THE FORECAST AREA
FRIDAY NIGHT INTO SATURDAY. THE PACIFIC NORTHWEST TROUGH FINALLY
MOVES EAST ACROSS THE NORTHERN PLAINS SUNDAY NIGHT THROUGH MONDAY
NIGHT BREAKING DOWN THE PERSISTENT RIDGING OVER THE UPPER MIDWEST.
THIS WILL BRING CHANCES FOR SHOWERS AND STORMS TO THE FORECAST
AREA...ESPECIALLY SUNDAY NIGHT INTO MONDAY NIGHT. WARM SOUTHERLY
FLOW WILL CONTINUE INTO EARLY NEXT WEEK. HIGHS WILL REMAIN WELL
ABOVE NORMAL THROUGH THE WEEKEND WITH SATURDAY LOOKING TO BE THE
WARMEST DAY WITH HIGHS IN THE MID TO UPPER 80S. THE WARM
TEMPERATURES WILL CONTINUE THROUGH THE MIDDLE OF NEXT WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1143 PM CDT WED SEP 4 2013
THE MAIN FOCUS AT THE TAF SITES IS WITH THE POTENTIAL DEVELOPMENT
OF MVFR TO IFR STRATUS OVERNIGHT INTO TOMORROW MORNING. THIS
STRATUS HAS STARTED TO FORM ACROSS PORTIONS OF EASTERN WISCONSIN
OVER THE PAST FEW HOURS. SOME OF THESE MID LEVEL CLOUDS IN THE
3-6KFT RANGE HAVE SNUCK INTO WESTERN WISCONSIN ALREADY AND WILL
LIKELY PERSIST INTO TOMORROW. THE QUESTION IS IF/WHEN THE
MVFR/IFR STRATUS WILL MAKE IT INTO LSE/RST. WITH THE LOW STRATUS
STILL ALONG LAKE MICHIGAN AND THE LAST FEW RUNS OF THE RAP MODEL
SHOWING THIS HIGHER RH GETTING IN LATER...HAVE DECIDED TO KEEP THE
LOW CONDITIONS IN THE TAF SITES...BUT DELAY IT A FEW HOURS THIS
MORNING. THESE CONDITIONS SHOULD QUICKLY IMPROVE THROUGH THE LATE
MORNING HOURS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS TAUNTON MA
649 AM EDT THU SEP 5 2013
.SYNOPSIS...
A SHARP COLD FRONT WILL SWEEP ACROSS THE REGION THIS MORNING WITH
A FEW BRIEF SHOWERS. DRY WEATHER FOLLOWS WITH UNSEASONABLY COOL
CONDITIONS LATE TODAY INTO FRIDAY. TEMPERATURES MODERATE TO
SEASONAL LEVELS THIS WEEKEND...BEFORE ANOTHER COLD FRONT BRINGS
SOMEWHAT COOLER AIR EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
645 AM UPDATE...
LOWERED RAINFALL CHANCES THIS MORNING BASED ON LATEST RADAR
DATA...WHICH IS SHOWING RAINFALL DRYING SLIGHTLY AS IT MOVES EAST.
MOST OF THE RAPID REFRESH MODELS..SUCH AS THE HRRR AND RAP...ARE
CONSISTENTLY SHOWING A SLIGHT INCREASE IN COVERAGE FROM PRESENT
LATER THIS MORNING AS THE COLD FRONT MOVES INTO CENTRAL AND
EASTERN MA. THIS MAKES SENSE AS WE WILL BE AFTER SUNRISE...AND THE
LOW LEVEL LAPSE RATES SHOULD BE AT LEAST A LITTLE MORE FAVORABLE.
OTHERWISE...THE TIMING OF THE PREVIOUS FORECAST LOOKS GOOD WITH
A COLD FRONT MOVING OFFSHORE AROUND NOON. MADE MINOR TWEAKS TO
TEMPERATURES AS WELL TO BRING THEM IN LINE WITH OBSERVED TRENDS.
PREVIOUS DISCUSSION...
SFC OBS AND MSAS SUGGEST STRONG SFC COLD FRONT IS JUST ON THE NW
DOORSTEP OF BOX CWA THIS HOUR...HAVING ALREADY MOVED THROUGH
CENTRAL VT/NH. PRECIP HAS BEEN VERY CLOSELY ASSOCIATED WITH THIS
FRONT GIVEN LACK OF DEEP MOISTURE FLUX /MOISTURE IS LIMITED TO THE
H85-H5 LAYER/ AND REQUIRES ALL FRONTOGENETICAL FORCING. AM NOTING
A FAIR AMOUNT OF DRYING OF THESE -SHRA AS THEY APPROACH THE VERY
DRY AIRMASS ALREADY IN PLACE OVER SRN NEW ENGLAND.
THEREFORE...DESPITE THE MOISTURE AND LATEST MODEL TREND TO LEAN
TOWARD LIKELY- CATEGORICAL POPS WILL CONTINUE TO CAP POPS AT
CHANCE AS THE FRONT SLIDES THOUGH THIS MORNING. TIMING THIS FRONT
TO REACH SRN NH AND THE MASS BORDER BY 09-10Z...CENTRAL MA BY
13-14Z AND TO THE S COAST BY ABOUT 16-18Z. TIMING OF HIGHEST POPS
FOLLOW THE TIMING OF THE FRONT. IT IS POSSIBLE HOWEVER...GIVEN THE
LACK OF MOISTURE AND RECENT RADAR TRENDS...THAT MANY LOCATIONS MAY
REMAIN DRY WITH THIS FROPA. AREAS THAT DO SEE RAINFALL WILL LIKELY
ONLY SEE ENOUGH TO WET THE GROUND.
STRONG COLD ADVECTION AND SOME CLOUD COVER WITH THIS FRONT SUGGEST
A NON-DIURNAL TEMP TREND WITH THE HIGHS LIKELY ARRIVING ABOUT MID
DAY TO EARLY AFTERNOON WITH GRADUAL DECREASES INTO THE EVENING
HOURS. LATEST MAV/MET GUIDANCE SHOWS THIS WELL. CLOUDS ARE LIKELY
TO RAPIDLY DISSIPATE TO NEAR SKC CONDITIONS BY THIS EVENING AS DRY
AIR WORKS IN WITH HIGH PRES AND THE ACCOMPANYING CAA. WINDS WILL
ALSO BE BRIEFLY GUSTY...REACHING 20+ MPH AT TIMES JUST BEHIND THE
FRONT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
TONIGHT...
STRONG COLD ADVECTION CONTINUES INITIALLY ALLOWING H85 TEMPS TO
DIP AS LOW AS +2C BY THE EVENING HOURS. THE PRIMARY EFFECT FROM
THIS WILL BE THE POSSIBILITY OF SOME OCEAN EFFECT CLOUDS AND
POSSIBLY EVEN LIGHT SHOWERS WHICH MAY EFFECT THE CAPE/ISLANDS
OVERNIGHT WITH N FLOW. GIVEN THE DIFFERENCE WITH SST/S AROUND +18
TO +20C THERE SHOULD BE ENOUGH NEAR SFC INSTABILITY TO GENERATE
THESE OCEAN EFFECT CLOUDS. WILL KEEP POPS OUT FOR THE TIME BEING
AS WELL MIXED AND DRY BL MAY KEEP ANY -SHRA FROM REACHING THE SFC.
OTHERWISE...SKC CONDITIONS IN THE INTERIOR AND SLACKENING MASS
FIELDS SUGGEST GOOD RADIATIONAL COOLING WHICH COULD LEAD SOME
VALLEYS IN THE NW PORTIONS OF THE CWA TO DIP BELOW THE 36F
THRESHOLD DURING THE EARLY MORNING HOURS. THEREFORE...WILL BE
ISSUING A STATEMENT FOR THE THREAT OF SOME PATCHY FROST IN
TYPICALLY COLDER VALLEYS. WILL LIMIT THE STATEMENT TO CHESHIRE
COUNTY IN NH...AS WELL AS FRANKLIN AND NORTHERN WORCESTER COUNTIES
IN MA. DAY CREW MAY NEED TO CONSIDER A FULL FLEDGED FROST ADVISORY
IF MODEL COOLING TREND CONTINUES. ELSEWHERE...EVEN THOUGH PLACES
WILL BE TOO COOL FOR FROST WILL STILL BE MUCH COOLER THAN PREVIOUS
NIGHTS...WITH TEMPS RANGING FROM THE MID 30S TO MID 40S.
FRI...
COOL START TO THE DAY WILL WITH FULL SUNSHINE WILL REALIZING THE
INCREASING H85 TEMPS THROUGH THE DAY. THESE TEMPS SHOULD TOP OUT
AT ABOUT +6C BY LATE AFTERNOON. THEREFORE...MAX TEMPS GENERALLY
REMAIN AT OR BELOW THE 70F MARK FOR THE DAY. HIGH PRES REMAINS IN
CONTROL WITH DRY WX.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
HIGHLIGHTS...
* MAINLY DRY WEATHER THROUGH THE MIDDLE OF NEXT WEEK
* TEMPERATURES MODERATE TO NEAR NORMAL THIS WEEKEND
DETAILS...
FRIDAY NIGHT AND SATURDAY...
EXPECTING GOOD RADIATIONAL COOLING CONDITIONS FRIDAY NIGHT...BUT LOW
TEMPERATURES WILL NOT BE QUITE AS CHILLY AS THURSDAY NIGHT. AFTER A
COOL START EARLY SATURDAY...A HIGH PRESSURE MOVING OFF THE COAST
WILL ALLOW FOR A RETURN SOUTHWEST FLOW OF AIR INTO SOUTHERN NEW
ENGLAND. PLENTY OF SUNSHINE EARLY IN THE DAY...BUT WE SHOULD SEE AN
INCREASE IN MID AND HIGH CLOUDS DURING THE AFTERNOON IN THE WARM AIR
ADVECTION PATTERN.
SATURDAY NIGHT AND SUNDAY...
A COLD FRONT WILL MOVE ACROSS THE REGION SOMETIME SUNDAY. THERE IS
LITTLE MOISTURE OR INSTABILITY AHEAD OF THIS FRONT...BUT CANNOT RULE
OUT A BRIEF SPRINKLE/SPOT SHOWER OR TWO SOMETIME DURING THIS TIME
FRAME. EVEN IF THIS HAPPENS THOUGH...THE VAST MAJORITY OF THE TIME
WILL BE DRY SO HAVE MAINTAINED LOW POPS.
MONDAY THROUGH WEDNESDAY...
DRY BUT SOMEWHAT COOLER WEATHER EXPECTED MONDAY BEHIND A COLD FRONT.
HOWEVER...AIRMASS DOES NOT LOOK AS CHILLY AS WHAT WE WILL HAVE THIS
LATE THIS WEEK...WITH THE CORE OF COLDER AIR OVER NORTHERN NEW
ENGLAND. A HIGH PRESSURE SHOULD MOVE OFF THE COAST ALLOWING FOR A
RETURN OF WARMER AIR FOR TUESDAY AND ESPECIALLY WEDNESDAY. DRY
WEATHER SHOULD PREVAIL MOST OF THE TIME THROUGH WEDNESDAY. A WARM
FRONT PASSING NEARBY MAY BE ENOUGH TO TRIGGER ISOLATED SHOWERS IF
ENOUGH MOISTURE CAN BE POOLED TOGETHER TUESDAY INTO WEDNESDAY.
&&
.AVIATION /10Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW /THROUGH FRIDAY/...HIGH CONFIDENCE OVERALL...
MAINLY VFR THROUGH THE PERIOD. HOWEVER A PERIOD OF -SHRA WILL MOVE
ACROSS THE REGION FROM N TO S FROM ABOUT 08Z-18Z...EXITING
OFFSHORE AFTER 18Z...AND THERE MAY BE LOCALIZED MVFR CONDITIONS
WITHIN THESE -SHRA. OTHERWISE...SOME MVFR CIGS ARE POSSIBLE OVER
THE CAPE/ISLANDS LATE THIS EVENING AS SOME OCEAN EFFECT CLOUDS
DEVELOP. WIND GUSTS 15-20 KT POSSIBLE AT TIMES ONCE WINDS SHIFT TO
THE NNW THIS MORNING BEHIND THE COLD FRONT.
KBOS TERMINAL...GENERALLY HIGH CONFIDENCE IN TAF...ALTHOUGH A
BRIEF PERIOD OF MVFR IS POSSIBLE IN SOME -SHRA THIS MORNING.
ALSO...WINDS MAY SHIFT MORE NNE BEHIND THE COLD FRONT MID MORNING
INTO THE AFTERNOON.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
HIGH CONFIDENCE IN MAINLY VFR CONDITIONS THROUGH THE PERIOD. MAY
SEE SOME VERY LOCALIZED PATCHY GROUND FOG IN THE TYPICALLY PRONE
LOCATIONS DURING THE LATE NIGHT/EARLY MORNING HOURS. THERE ALSO IS
LOW PROBABILITY OF BRIEF MVFR CONDITIONS SAT NIGHT AND EARLY
SUNDAY IN SHOWERS AHEAD OF A COLD FRONT.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
SHORT TERM /THROUGH THURSDAY NIGHT/...HIGH CONFIDENCE.
MAIN ISSUE TODAY WILL BE THE THREAT FOR OCCASIONAL SMALL CRAFT
ADVISORY LEVEL WINDS ESPECIALLY AROUND THE MID DAY PERIOD. WIND
GUSTS MAY APPROACH 25 KT AT TIMES...BUT THE TIMING WILL BE SHORT
LIVED AND MANY GUSTS WILL STAY BELOW THIS THRESHOLD.
THEREFORE...WILL HOLD OFF ON ANY HEADLINES BUT MENTION THE THREAT
FOR A FEW GUSTS TO 25 KT IN THE COASTAL FORECAST.
OTHERWISE...HIGH PRES BUILDS OVER THE WATERS LATE TONIGHT INTO
TOMORROW WITH GENERAL DRY AND QUIET BOATING WEATHER EXPECTED.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
FRIDAY NIGHT...HIGH CONFIDENCE. HIGH PRESSURE OVERHEAD WILL KEEP
WINDS/SEAS WELL BELOW SMALL CRAFT ADVISORY THRESHOLDS.
SATURDAY...MODERATE CONFIDENCE. HIGH PRESSURE MOVING EAST OF THE
WATERS WILL ALLOW FOR SOUTHWEST WINDS TO DEVELOP. CONDITIONS SHOULD
GENERALLY REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS...BUT A
PERIOD OF SOUTHWEST WIND GUSTS OF 20 TO 25 KNOTS ARE POSSIBLE ACROSS
THE NEAR SHORE WATERS OF THE SOUTH COAST DURING THE AFTERNOON. THIS
MAY RESULT IN SOME CHOPPY SEAS ACROSS THE SOUNDS AND BAYS.
SUNDAY AND MONDAY...MODERATE CONFIDENCE. A PERIOD OF NORTHERLY SMALL
CRAFT ADVISORY WIND GUSTS AND SEAS ARE POSSIBLE LATE SUNDAY INTO
EARLY MONDAY BEHIND A COLD FRONT.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...BELK/DOODY
NEAR TERM...BELK/DOODY
SHORT TERM...DOODY
LONG TERM...BELK
AVIATION...BELK/DOODY
MARINE...BELK/DOODY
AREA FORECAST DISCUSSION
NWS DES MOINES IA
625 AM CDT THU SEP 5 2013
...UPDATED AVIATION DISCUSSION...
.SHORT TERM.../TODAY/...
ISSUED AT 355 AM CDT THU SEP 5 2013
WEAK ELEVATED SHOWER ACTIVITY LOOKS TO CONTINUE THROUGH THE MID
MORNING HOURS OVER THE WESTERN EDGES OF THE FORECAST AREA. THE
WEAK AREA OF VORTICITY ADVECTION BETWEEN 700-300MB WILL DISSIPATE
BY AROUND 18Z. SOUNDINGS BELOW 10KFT REMAIN VERY DRY AND NOT
EXPECTING MUCH QPF...IF ANY AT ALL...WITH THESE SHOWERS. KEPT
THUNDER OUT OF THE FORECAST ATTM AS LITTLE TO NO INSTABILITY
PRESENT THIS MORNING. THE 09.05 05Z HRRR HAS A DECENT HANDLE ON
THE OVERALL RADAR TRENDS THIS MORNING...BUT HAS SHOWERS LINGERING
PAST 18Z. FELT CONFIDENT ENOUGH TO KEEP FORECAST DRY AFTER 16Z
THIS MORNING WITH THE LACK OF FORCING AND MOISTURE AVAILABLE. USED
A BLEND OF THE 09.05 00Z NAM12/ECMWF FOR MAX TEMPS TODAY EVEN WITH
THE MID TO HIGH LEVEL CLOUD COVER THIS MORNING.
.LONG TERM.../TONIGHT THROUGH WEDNESDAY/...
ISSUED AT 355 AM CDT THU SEP 5 2013
MAIN CONCERNS THROUGH EARLY NEXT WEEK CONTINUE TO BE SUBTLE MINIMAL
PRECIP CHANCES AND WARMER TEMPS THROUGH EARLY NEXT WEEK. IA WILL
REMAIN IN NW FLOW INTO FRI WITH LOW CONFIDENCE IN PRECIP TRENDS.
MODELS CONTINUE TO GENERATE SPOTTY QPF BUT CANNOT REALLY FIND ANY
SUBSTANTIAL KINEMATIC OR THERMODYNAMIC FEATURES TO KEY ON...SO WITH
SURFACE BASED POTENTIAL NIL...WILL LEAVE FORECAST DRY. COULD BE
SOME WEAK VERY ELEVATED CONVECTION...BUT CONFIDENCE IN TIMING AND
LOCATION IS NOT GREAT ENOUGH TO MENTION. WARM ADVECTION DOES LIFT
THROUGH FRI DURING THE DAY...BUT MOISTURE SEEMS SOMEWHAT LIMITED AND
ITS DAYTIME TIMING WOULD NOT BE CLIMATOLOGICALLY FAVORED. HAVE
WAITED TO INTRODUCE SLIGHTS NE FRI NIGHT WHEN MOISTURE INCREASES A
BIT.
THE BIGGEST SENSIBLE WEATHER REFLECTION MAY BE TEMPERATURES WARMING
FURTHER HOWEVER WITH WIDESPREAD HIGHS ABOVE 90F. A WEAK BOUNDARY
WILL SAG INTO NRN IA SAT...BUT WILL NOT CHANGE THE AIRMASS MUCH
KEEPING TEMPS FAIRLY STATIC NORTH AND EVEN WARMING A FEW DEGREES TO
ITS SOUTH WITH PLENTY OF HIGHS IN THE MID 90S I80 INTO MO.
BAROCLINIC ZONE STRENGTHENS SLIGHTLY SAT NIGHT AS FRONT CONTINUES
TO DRIFT FARTHER SOUTH SO HAVE PUSHED FRI NIGHT SLIGHTS DOWN INTO
CENTRAL AND SRN IA BY THAT TIME. ANYTHING IN THIS TIME RANGE WOULD
LIKELY BE QUITE ELEVATED ABOVE THE ELEVATED MIXED LAYER.
THETA-E/WARM ADVECTION STRENGTHENS CONSIDERABLY BY LATE SUN FROM
IA/MN BORDER INTO THE NRN PLAINS. THIS WILL ALLOW TEMPS TO REBOUND
ONCE AGAIN AFTER BRIEFLY DROPPING A TAD SUN. THE STRONGER
THERMODYNAMIC FORCING ALSO STILL SUPPORTS MAINLY NOCTURNAL PRECIP
CHANCES NORTH...WITH BEST POTENTIAL NORTH OF IA.
WAVE CURRENTLY OFF THE OR COAST VERY SLOWLY BUT SURELY TOPS THE
ROCKIES RIDGE BY EARLY NEXT WEEK AND EVENTUALLY RESULTS IN MORE
ORGANIZED SYNOPTIC SCALE FORCING. THIS LIFT WILL SLOWLY PUSH SOUTH
AND EAST COINCIDENT WITH THE FRONTAL BOUNDARY AND LIKELY BRING OUR
BEST WINDOW OF PRECIP CHANCES LATE TUE INTO WED. THE FRONTAL
PASSAGE WILL ALSO DROP OUR TEMPS BACK CLOSER TO NORMAL FOR WED.
&&
.AVIATION...05/12Z
ISSUED AT 625 AM CDT THU SEP 5 2013
WEAK SHOWER ACTIVITY WILL CONTINUE TO DRIBBLE OVER WESTERN IOWA
AND HAD HIGH ENOUGH CONFIDENCE TO LEAVE OUT ANY MENTION OF RAIN IN
THE TAFS THIS MORNING. FOD IS LIKELY TO BE THE CLOSEST BUT IF
ANYTHING DOES MAKE IT THAT FAR EAST IT WILL QUICKLY DISSIPATE WITH
THE DEEP DRY LAYER BELOW 10KFT. OTHERWISE...VFR CONDITIONS ARE
FORECAST THROUGH FRIDAY MORNING.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...PODRAZIK
LONG TERM...SMALL
AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS GOODLAND KS
522 AM MDT THU SEP 5 2013
.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 250 AM MDT THU SEP 5 2013
STUBBORN UPPER HIGH WILL REMAIN PARKED OVER THE FORECAST AREA
THROUGH SATURDAY...AFTER WHICH TIME THE UPPER LOW OVER THE PAC NW
WILL BEGIN TO NUDGE IT EAST. AT THE SURFACE THE WEAK TROUGH OVER
EASTERN COLORADO WILL REMAIN IN PLACE RESULTING IN SOUTHERLY
SURFACE FLOW.
NO CHANGES WORTH NOTING FROM PREVIOUS FORECAST IN TERMS OF MAX-MIN
TEMPS AND WINDS. HIGHS WILL CONTINUE IN THE 95-102 RANGE WITH LOWS
IN THE 60S. NO PRECIP IS EXPECTED DURING PERIOD AFTER THIS
MORNING. DID INCLUDE SLIGHT CHANCE POPS FROM YUMA COUNTY EAST TO
RED WILLOW FOR EARLY THIS MORNING TO ACCOUNT FOR CURRENT RADAR
TRENDS. EVEN THOUGH SHOWERS CONTINUE TO WEAKEN JUST TO OUR NORTH
OVER PHILLIPS AND CHASE COUNTIES...WILL KEEP LOW POPS GOING FOR A
FEW HOURS AFTER SUNRISE. LAST SEVERAL RUNS OF HRRR SUGGEST SOME
PRECIP MAY LINGER A BIT INTO THE MORNING HOURS. OTHERWISE...TODAY
THROUGH SATURDAY WILL BASICALLY BE A REPEAT OF YESTERDAY.
.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 250 AM MDT THU SEP 5 2013
THE 500MB HIGH IS STILL CENTERED OVER KANSAS AND BEGINS TO MOVE
EAST SUNDAY NIGHT INTO MONDAY WHILE THE UPPER LOW/TROUGH OVER THE
PACIFIC NORTHWEST MOVES INTO THE NORTHERN PLAINS. SUNDAY THROUGH
MONDAY SHOULD REMAIN WARM AND DRY...WITH HIGHS IN THE MID TO UPPER
90S. MODELS STILL DISAGREE OVER TIMING AND PLACEMENT OF THE COLD
FROPA NEXT WEEK...GFS HAS IT MOVING THROUGH MORE QUICKLY ON MONDAY
NIGHT INTO TUESDAY WHILE THE ECMWF HAS IT MOVING THROUGH TUESDAY
INTO TUESDAY NIGHT. AS OF RIGHT NOW...WEDNESDAY LOOKS TO BE THE
COOLEST DAY WITH NEAR NORMAL HIGH TEMPERATURES IN THE LOW TO MID
80S. TEMPERATURES MAY NEED ADJUSTING AS THE WEEK PROGRESSES AND
THE TIMING/PLACEMENT OF THE FRONT IS MORE SOLID. THE ALLBLEND
SOLUTION FOR TEMPERATURES AND PRECIPITATION SEEMED LIKE THE BEST
WITH THE CURRENT MODEL DIFFERENCES. THERE WERE MINOR ADJUSTMENTS
TO PRECIP...REMOVING THE 15 POP IN EASTERN COLORADO ON MONDAY
AFTERNOON CONSIDERING THE RIDGE WILL STILL BE IN PLACE...AND THERE
IS NO FEATURE THAT WOULD INDICATE PRECIP. OTHER THAN THAT...PRECIP
CHANCES ARE STILL THE GREATEST IN THE MONDAY NIGHT THROUGH
WEDNESDAY TIME FRAME. GFS HAS PWATS AROUND 1.50 ON TUESDAY
WHICH...GIVEN THE FRONT MOVING THROUGH AND NORTHEASTERLY/EASTERLY
FLOW BEHIND THE FRONT...COULD RESULT IN SOME GOOD RAINFALL AMOUNTS
WITH THE SHOWERS AND THUNDERSTORMS THAT MOVE THROUGH THE CWA.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 511 AM MDT THU SEP 5 2013
VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. UPPER LEVEL
HIGH PRESSURE CENTERED OVER EASTERN COLORADO/WESTERN KANSAS WILL
BRING MOSTLY CLEAR CONDITIONS...WITH A FEW HIGH CLOUDS OVER BOTH
TAF SITES. LIGHT SOUTHERLY WINDS THIS MORNING WILL INCREASE TO
AROUND 10 TO 15 KTS MID-DAY FOR BOTH SITES AS MIXING TAKES
PLACE...WITH WIND GUSTS AROUND 20 TO 25 KTS. GUSTS SHOULD DECREASE
AROUND SUNSET WITH SUSTAINED WINDS AROUND 10KTS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DLF
LONG TERM...ALW
AVIATION...ALW
AREA FORECAST DISCUSSION
NWS GOODLAND KS
520 AM MDT THU SEP 5 2013
.UPDATE...
ISSUED AT 517 AM MDT THU SEP 5 2013
REMOVED POPS/THUNDERSTORMS FROM NORTHERN TIER OF COUNTIES FOR
EARLY THIS MORNING. CONVECTION THAT WAS PERSISTENT OVERNIGHT
ACROSS EXTREME NORTHEAST COLORADO AND PARTS OF SOUTHWEST NEBRASKA
HAS FINALLY DISSIPATED.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 250 AM MDT THU SEP 5 2013
STUBBORN UPPER HIGH WILL REMAIN PARKED OVER THE FORECAST AREA
THROUGH SATURDAY...AFTER WHICH TIME THE UPPER LOW OVER THE PAC NW
WILL BEGIN TO NUDGE IT EAST. AT THE SURFACE THE WEAK TROUGH OVER
EASTERN COLORADO WILL REMAIN IN PLACE RESULTING IN SOUTHERLY
SURFACE FLOW.
NO CHANGES WORTH NOTING FROM PREVIOUS FORECAST IN TERMS OF MAX-MIN
TEMPS AND WINDS. HIGHS WILL CONTINUE IN THE 95-102 RANGE WITH LOWS
IN THE 60S. NO PRECIP IS EXPECTED DURING PERIOD AFTER THIS
MORNING. DID INCLUDE SLIGHT CHANCE POPS FROM YUMA COUNTY EAST TO
RED WILLOW FOR EARLY THIS MORNING TO ACCOUNT FOR CURRENT RADAR
TRENDS. EVEN THOUGH SHOWERS CONTINUE TO WEAKEN JUST TO OUR NORTH
OVER PHILLIPS AND CHASE COUNTIES...WILL KEEP LOW POPS GOING FOR A
FEW HOURS AFTER SUNRISE. LAST SEVERAL RUNS OF HRRR SUGGEST SOME
PRECIP MAY LINGER A BIT INTO THE MORNING HOURS. OTHERWISE...TODAY
THROUGH SATURDAY WILL BASICALLY BE A REPEAT OF YESTERDAY.
.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 250 AM MDT THU SEP 5 2013
THE 500MB HIGH IS STILL CENTERED OVER KANSAS AND BEGINS TO MOVE
EAST SUNDAY NIGHT INTO MONDAY WHILE THE UPPER LOW/TROUGH OVER THE
PACIFIC NORTHWEST MOVES INTO THE NORTHERN PLAINS. SUNDAY THROUGH
MONDAY SHOULD REMAIN WARM AND DRY...WITH HIGHS IN THE MID TO UPPER
90S. MODELS STILL DISAGREE OVER TIMING AND PLACEMENT OF THE COLD
FROPA NEXT WEEK...GFS HAS IT MOVING THROUGH MORE QUICKLY ON MONDAY
NIGHT INTO TUESDAY WHILE THE ECMWF HAS IT MOVING THROUGH TUESDAY
INTO TUESDAY NIGHT. AS OF RIGHT NOW...WEDNESDAY LOOKS TO BE THE
COOLEST DAY WITH NEAR NORMAL HIGH TEMPERATURES IN THE LOW TO MID
80S. TEMPERATURES MAY NEED ADJUSTING AS THE WEEK PROGRESSES AND
THE TIMING/PLACEMENT OF THE FRONT IS MORE SOLID. THE ALLBLEND
SOLUTION FOR TEMPERATURES AND PRECIPITATION SEEMED LIKE THE BEST
WITH THE CURRENT MODEL DIFFERENCES. THERE WERE MINOR ADJUSTMENTS
TO PRECIP...REMOVING THE 15 POP IN EASTERN COLORADO ON MONDAY
AFTERNOON CONSIDERING THE RIDGE WILL STILL BE IN PLACE...AND THERE
IS NO FEATURE THAT WOULD INDICATE PRECIP. OTHER THAN THAT...PRECIP
CHANCES ARE STILL THE GREATEST IN THE MONDAY NIGHT THROUGH
WEDNESDAY TIME FRAME. GFS HAS PWATS AROUND 1.50 ON TUESDAY
WHICH...GIVEN THE FRONT MOVING THROUGH AND NORTHEASTERLY/EASTERLY
FLOW BEHIND THE FRONT...COULD RESULT IN SOME GOOD RAINFALL AMOUNTS
WITH THE SHOWERS AND THUNDERSTORMS THAT MOVE THROUGH THE CWA.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1121 PM MDT WED SEP 4 2013
VFR CONDITIONS WILL CONTINUE AT KGLD AND KMCK FOR THE NEXT 24
HOURS AS A RIDGE OF HIGH PRESSURE IS CENTERED OVER THE AREA. SOME
GUSTY SOUTH WIND WILL BE POSSIBLE THURSDAY IN RESPONSE TO A
SURFACE TROUGH NEAR THE KANSAS/COLORADO BORDER.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...DLF
SHORT TERM...DLF
LONG TERM...ALW
AVIATION...FS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1015 AM EDT THU SEP 5 2013
.SYNOPSIS...
A DRY COLD FRONT WILL PUSH SOUTHWARD THROUGH THE REGION TONIGHT.
CANADIAN HIGH PRESSURE WILL BUILD SOUTH INTO THE AREA ON FRIDAY WITH
GRADUAL WEAKENING THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1015 AM THURSDAY...
A WEAK COLD FRONT IS HUNG UP OVER THE COASTAL PLAIN THIS
MORNING...WITH DEWPOINTS ALONG AND TO THE EAST OF THE FRONT STILL IN
THE UPPER 60S AND LOWER 70S. WHILE THIS BOUNDARY CONTINUES TO PUSH
SLOWLY TO THE SOUTHEAST...MODIFIED NAM AND RAP SOUNDINGS SUGGEST
1000 J/KG OF MLCAPE WILL LINGER ALONG THE EASTERN PERIPHERY OF THE
CWA...AND THIS IS SOMEWHAT EVIDENT ALREADY IN THE SPC MESOANALYSIS.
HOWEVER..LOW LEVEL CONVERGENCE IS WEAK ALONG THE SURFACE FRONT AND A
WEAK 850MB TROUGH NOTED IN UPPER AIR ANALYSIS. THE SEABREEZE LOOKS
TO BE THE ONLY ENHANCEMENT FOR LIFT...AND RAP/HRRR PROGS SHOW THE
SEABREEZE ONLY BARELY REACHING SAMPSON COUNTY BY LATE AFTERNOON.
THUS...WILL LEAVE THE FORECAST FREE OF POPS FOR TODAY. OTHERWISE..
SKIES WILL BE MOSTLY SUNNY EXCEPT FOR OVER PORTIONS OF THE SOUTHERN
PIEDMONT WHERE THIN HIGH CLOUDS CONTINUE TO DRIFT SOUTHEAST IN THE
NORTHWESTERLY FLOW ALOFT. HIGHS IN THE UPPER 80S TO AROUND 90.
ANOTHER COLD FRONT TO OUR NORTH WILL SURGE SOUTH THIS EVENING AND
CROSS THE AREA OVERNIGHT...THOUGH WITH LITTLE MOISTURE TO WORK WITH.
LOWS TONIGHT WILL BE IN THE LOWER 60S NORTH TO MID/UPPER 60S
SOUTH.
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 215 AM THURSDAY...
CANADIAN SURFACE HIGH PRESSURE WILL BUILD SOUTH DOWN THE
MID-ATLANTIC SEABOARD...BECOMING CENTERED OVER THE AREA
BY SATURDAY MORNING. ASSOCIATED NORTHEASTERLY LOW-LEVEL MARITIME
FLOW WILL RESULT IN SCATTERED PATCHES OF POST-FRONTAL STRATUS FRIDAY
MORNING...AND PERHAPS A FAIRLY HEALTHY BROKEN STRATOCUMULUS DECK
BY THE AFTERNOON. COOLER AND LESS HUMID WITH HIGHS IN THE UPPER 70S
TO NEAR 80 NORTH TO MID 80S SOUTH.
THE STRATOCUMULUS MARINE LAYER LAYER WILL LIKELY GET TRAPPED
UNDERNEATH THE MID-LEVEL SUBSIDENCE INVERSION FRIDAY
EVENING/NIGHT...RESULTING IN PARTLY TO CLOUDY SKIES. LOWS IN THE MID
TO UPPER 50S NORTH TO LOWER/MID 60S SOUTH.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 245 AM THURSDAY...
OVERALL THE LONG TERM PERIOD WILL BE CHARACTERIZED BY MOSTLY DRY
CONDITIONS AS THE MAIN STORM TRACK REMAINS WELL NORTH OF THE REGION.
THE WEATHER ACROSS CENTRAL NC WILL BE DOMINATED BY SEVERAL
REINFORCING SURFACE HIGHS AND NORTHWEST FLOW ALOFT AS A BROAD TROUGH
REMAINS SITUATED JUST OFF THE EAST COAST...BEFORE AN UPPER LEVEL
RIDGE BUILDS EAST THROUGH THE MIDDLE OF NEXT WEEK.
HIGH PRESSURE OVER THE AREA ON SATURDAY WILL WEAKEN AND BEGIN TO
SHIFT OFFSHORE LATE SATURDAY INTO EARLY SUNDAY...BUT WITH ONLY
MINIMAL MOISTURE RETURN...THE DRY CONDITIONS ARE EXPECTED TO PERSIST
THROUGH AT LEAST SUNDAY. THEN...ANOTHER FRONT IS PROGGED TO MOVE
ACROSS THE AREA ON LATE SUNDAY INTO MONDAY...WITH YET ANOTHER
RENEWED SURFACE HIGH RIDGING DOWN INTO THE REGION FOR EARLY NEXT
WEEK. AS THE FRONT CROSSES THE AREA ON MONDAY...THERE COULD BE SOME
ISOLATED ACTIVITY...ESPECIALLY ACROSS THE SOUTHERN TIER OF THE
FORECAST AREA...WHERE THE BEST MOISTURE CONTENT WILL RESIDE AND THE
TIMING OF THE FRONTAL PASSAGE WILL BE MOST FAVORABLE.
FOR THE REMAINDER OF THE WEEK...THE SURFACE HIGH WILL BE CENTERED
SLIGHTLY FURTHER TO THE NORTH THAN PREVIOUS ONES AND AS A
RESULT...MORE IN THE WAY OF EASTERLY FLOW IS EXPECTED AND THEREFORE
MOISTURE IS PROGGED TO GRADUALLY INCREASE THROUGH THE MIDDLE NEXT
WEEK. HOWEVER...THE EAST COAST TROUGH ALOFT IS FINALLY EXPECTED TO
BE REPLACED BY AN EASTWARD PROGRESSING UPPER LEVEL RIDGE BY THE
EARLY TO MIDDLE PART OF NEXT WEEK...WHICH MAY WORK AGAINST ANY
CONVECTIVE DEVELOPMENT. WITH ALL OF THIS IN MIND...WITH MAINTAIN A
DRY FORECAST THROUGH THE REMAINDER OF THE LONG TERM PERIOD...BUT
THAT IS NOT TO SAY THERE COULD BE SOME ISOLATED DIURNAL TYPE
ACTIVITY. TEMPS WILL BE TIED TO THE MULTIPLE FRONTAL PASSAGES DURING
THE PERIOD...BUT WILL GENERALLY BE NEAR TO SLIGHTLY ABOVE NORMAL
THROUGHOUT THE ENTIRE PERIOD...EXCEPT FOR SATURDAY WHEN SLIGHTLY
BELOW NORMAL TEMPS ARE EXPECTED.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 720 AM THURSDAY...
24 HOUR TAF PERIOD:
CLEAR SKIES AND CALM WINDS WILL SUPPORT AREAS OF FOG
OVERNIGHT...ESPECIALLY ACROSS CENTRAL AND EASTERN PORTIONS OF THE
STATE WHERE LOW-LEVEL REMAINS HIGH IN CLOSER PROXIMITY TO A
DISSIPATING STALLED SURFACE FRONT. AFTER DAYBREAK...EXPECT
CONDITIONS TO IMPROVE BACK TO VFR (BY APPROX 12-13Z) FOR THE
REMAINDER OF THE TAF PERIOD WITH LIGHT NORTH-NORTHWESTERLY WINDS
THROUGHOUT THE DAY. A SECONDARY DRY COLD FRONT WILL PUSH SOUTH
THROUGH THE AREA BETWEEN 00 TO 09Z FRIDAY. COULD SEE A BRIEF 1-2HR
PERIOD OF NELY WIND GUSTS IMMEDIATELY BEHIND THE FRONT...OTHERWISE
NO SIGNIFICANT WEATHER IS EXPECTED.
LOOKING AHEAD:
ASIDE FROM SOME EARLY MORNING FOG..A DRY BELOW NORMAL PWAT AIRMASS
WITH HIGH PRES AT THE SURFACE WILL RESULT IN PREDOMINATELY VFR
CONDITIONS THROUGH THE WEEKEND. ANOTHER DRY BACK-DOOR COLD FRONTAL
WILL PUSH SOUTH THROUGH THE AREA SUNDAY NIGHT AND INTO EARLY MONDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CBL
NEAR TERM...CBL/SMITH
SHORT TERM...CBL
LONG TERM...KRR
AVIATION...CBL
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1031 AM CDT THU SEP 5 2013
.UPDATE...
ISSUED AT 1017 AM CDT THU SEP 5 2013
UPDATE TO REMOVE POPS ACROSS THE WEST FOR THE LATE MORNING AS THE
ISOLATED THUNDERSTORMS HAVE DISSIPATED. OTHERWISE...EXPECT A
MOSTLY SUNNY SKY TODAY WITH QUIET WEATHER.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 349 AM CDT THU SEP 5 2013
THE MAIN FORECAST HIGHLIGHT FOR THE SHORT TERM PERIOD IS
PRECIPITATION CHANCES.
RADAR IMAGERY AT 08Z SHOWS ONGOING SHOWER ACTIVITY ACROSS CENTRAL
NORTH DAKOTA...WITH MORE WIDESPREAD SHOWER/THUNDERSTORM ACTIVITY
OVER THE BLACK HILLS REGION OF SOUTH DAKOTA...ASSOCIATED WITH A
WEAK UPPER LEVEL IMPULSE MOVING OVER THE AREA THIS MORNING. THERE
IS A BIT OF UNCERTAINTY IN THE PRECIP FORECAST THROUGH EARLY
AFTERNOON...AS THE 00Z GFS/ECWMF ARE MORE ROBUST IN AREAL EXTENT
OF SHOWER/THUNDERSTORM COVERAGE VERSUS THE 00Z NAM/GEM AND LATEST
RUNS OF THE HRRR AND RAP...WHICH ARE MORE SPOTTY WITH COVERAGE.
CONSEQUENTLY...HAVE USED A BLEND OF GUIDANCE...LIMITING POPS TO
SLIGHT CHANCE. LIGHTNING STRIKES HAVE BEEN FAR AND FEW BETWEEN
WITH ONGOING SHOWERS...SO HAVE REMOVED THE MENTION OF THUNDER IN
WX GRIDS FOR ALL EXCEPT ACROSS THE SOUTHWEST AND FAR WEST WHERE
CAPE MAY BE MORE PLENTIFUL. IN ADDITION...HAVE INCLUDED THE
MENTION OF SPRINKLES THROUGH LATE MORNING TO REFLECT ONGOING
ACTIVITY. SHOWERS/THUNDERSTORMS SHOULD COME TO AN END BY 18Z ONCE
THE WEAK IMPULSE MOVES INTO WESTERN MINNESOTA.
WARMER TEMPERATURES ARE EXPECTED ACROSS THE AREA TODAY AS A RIDGE
AND WARMER H850 TEMPERATURES MOVE OVERHEAD. THIS WILL RESULT IN
AFTERNOON TEMPERATURES CLIMBING INTO THE UPPER 80S AND LOWER
90S...AND OVERNIGHT TEMPERATURES COOLING ONLY INTO THE 60S.
DEWPOINTS WILL ALSO BE ON THE RISE...THOUGH HEAT INDEX VALUES
SHOULD REMAIN IN THE 90S.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 349 AM CDT THU SEP 5 2013
THE MAIN FORECAST CHALLENGE FOR THE EXTENDED WILL BE THE AREAL
EXTENT AND COVERAGE OF PRECIPITATION CHANCES THIS WEEKEND. GIVEN THE
MODEL TO MODEL AND RUN TO RUN INCONSISTENCIES...CONTINUED TO FOLLOW
A BLENDED APPROACH FOR THE EXTENDED PERIOD FORECAST.
EARLY IN THE PERIOD...THE MEDIUM RANGE MODELS CONTINUE TO STRUGGLE
WITH THE EXACT TIMING AND LOCATION OF SHORTWAVES EJECTING FROM AN
UPPER LOW PROGGED TO REMAIN OVER THE PACIFIC NORTHWEST THROUGH
SATURDAY. FOR NOW CONTINUED TO FORECAST AN INCREASING POP TREND WEST
AND CENTRAL THROUGH SATURDAY AND KEPT THE EAST (TURTLE MOUNTAIN
SOUTH TO THE JAMES RIVER VALLEY) DRY THROUGH EARLY SUNDAY MORNING.
AS THE UPPER LOW FINALLY PUSHES INTO MONTANA...THUNDERSTORM CHANCES
SHOULD INCREASE ACROSS THE ENTIRE STATE SUNDAY AND SUNDAY NIGHT.
GIVEN THE EXPECTED POSITION OF THE LOW AND ATTENDANT DEEP LAYER
SHEAR/INSTABILITY PARAMETERS...SEVERE WEATHER COULD BE POSSIBLE
SUNDAY AFTERNOON/EVENING. WILL CONTINUE TO HIGHLIGHT THIS
POSSIBILITY IN THE HWO.
THE LATEST GFS/ECMWF/GEM ALL DIFFER WITH RESPECT TO THE TIMING OF
THE LOW PIVOTING ACROSS NORTH DAKOTA AND SUBSEQUENTLY DRY CONDITIONS
FILTERING INTO THE REGION. THE LATEST ECMWF IS NOW MORE PROGRESSIVE
WITH THIS FEATURE AND PIVOTS IT THROUGH THE REGION MONDAY. THE GFS
IS ABOUT 12 HOURS SLOWER WHEREAS THE GEM IS AN AVERAGE OF THE TWO.
FOR NOW KEPT POPS IN AREAWIDE MONDAY AND FORECAST A DRYING TREND
TUESDAY THROUGH WEDNESDAY AS HIGH PRESSURE BUILDS OVER THE ROCKIES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1017 AM CDT THU SEP 5 2013
EXPECT VFR CONDITIONS AT ALL TAF SITES THROUGH THE PERIOD WITH A
LIGHT SOUTHEAST WIND UNDER 10 KTS.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE/AVIATION...RP KINNEY
SHORT TERM...LTH
LONG TERM...TM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
636 AM CDT THU SEP 5 2013
.UPDATE...
ISSUED AT 636 AM CDT THU SEP 5 2013
ONGOING CONVECTION OVER EASTERN MONTANA IS DISORGANIZED AND VERY
SLOW MOVING. IT MAY NOT EVEN HOLD TOGETHER TO MAKE IT TO THE MT/ND
BORDER. NEVERTHELESS...MAINTAINED SLIGHT CHANCE POPS WEST THIS
MORNING. A DRYING TREND IS STILL EXPECTED THIS AFTERNOON AS AN
UPPER WAVE MOVES EAST OF THE CWA.
OTHERWISE...NO MAJOR CHANGES WERE REQUIRED TO THE ONGOING
FORECAST. ADJUSTED THE HOURLY TEMP/WIND/DEWPOINT GRIDS BASED ON
CURRENT OBS/TRENDS. THE UPDATED PRODUCTS HAVE BEEN SENT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 349 AM CDT THU SEP 5 2013
THE MAIN FORECAST HIGHLIGHT FOR THE SHORT TERM PERIOD IS
PRECIPITATION CHANCES.
RADAR IMAGERY AT 08Z SHOWS ONGOING SHOWER ACTIVITY ACROSS CENTRAL
NORTH DAKOTA...WITH MORE WIDESPREAD SHOWER/THUNDERSTORM ACTIVITY
OVER THE BLACK HILLS REGION OF SOUTH DAKOTA...ASSOCIATED WITH A
WEAK UPPER LEVEL IMPULSE MOVING OVER THE AREA THIS MORNING. THERE
IS A BIT OF UNCERTAINTY IN THE PRECIP FORECAST THROUGH EARLY
AFTERNOON...AS THE 00Z GFS/ECWMF ARE MORE ROBUST IN AREAL EXTENT
OF SHOWER/THUNDERSTORM COVERAGE VERSUS THE 00Z NAM/GEM AND LATEST
RUNS OF THE HRRR AND RAP...WHICH ARE MORE SPOTTY WITH COVERAGE.
CONSEQUENTLY...HAVE USED A BLEND OF GUIDANCE...LIMITING POPS TO
SLIGHT CHANCE. LIGHTNING STRIKES HAVE BEEN FAR AND FEW BETWEEN
WITH ONGOING SHOWERS...SO HAVE REMOVED THE MENTION OF THUNDER IN
WX GRIDS FOR ALL EXCEPT ACROSS THE SOUTHWEST AND FAR WEST WHERE
CAPE MAY BE MORE PLENTIFUL. IN ADDITION...HAVE INCLUDED THE
MENTION OF SPRINKLES THROUGH LATE MORNING TO REFLECT ONGOING
ACTIVITY. SHOWERS/THUNDERSTORMS SHOULD COME TO AN END BY 18Z ONCE
THE WEAK IMPULSE MOVES INTO WESTERN MINNESOTA.
WARMER TEMPERATURES ARE EXPECTED ACROSS THE AREA TODAY AS A RIDGE
AND WARMER H850 TEMPERATURES MOVE OVERHEAD. THIS WILL RESULT IN
AFTERNOON TEMPERATURES CLIMBING INTO THE UPPER 80S AND LOWER
90S...AND OVERNIGHT TEMPERATURES COOLING ONLY INTO THE 60S.
DEWPOINTS WILL ALSO BE ON THE RISE...THOUGH HEAT INDEX VALUES
SHOULD REMAIN IN THE 90S.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 349 AM CDT THU SEP 5 2013
THE MAIN FORECAST CHALLENGE FOR THE EXTENDED WILL BE THE AREAL
EXTENT AND COVERAGE OF PRECIPITATION CHANCES THIS WEEKEND. GIVEN THE
MODEL TO MODEL AND RUN TO RUN INCONSISTENCIES...CONTINUED TO FOLLOW
A BLENDED APPROACH FOR THE EXTENDED PERIOD FORECAST.
EARLY IN THE PERIOD...THE MEDIUM RANGE MODELS CONTINUE TO STRUGGLE
WITH THE EXACT TIMING AND LOCATION OF SHORTWAVES EJECTING FROM AN
UPPER LOW PROGGED TO REMAIN OVER THE PACIFIC NORTHWEST THROUGH
SATURDAY. FOR NOW CONTINUED TO FORECAST AN INCREASING POP TREND WEST
AND CENTRAL THROUGH SATURDAY AND KEPT THE EAST (TURTLE MOUNTAIN
SOUTH TO THE JAMES RIVER VALLEY) DRY THROUGH EARLY SUNDAY MORNING.
AS THE UPPER LOW FINALLY PUSHES INTO MONTANA...THUNDERSTORM CHANCES
SHOULD INCREASE ACROSS THE ENTIRE STATE SUNDAY AND SUNDAY NIGHT.
GIVEN THE EXPECTED POSITION OF THE LOW AND ATTENDANT DEEP LAYER
SHEAR/INSTABILITY PARAMETERS...SEVERE WEATHER COULD BE POSSIBLE
SUNDAY AFTERNOON/EVENING. WILL CONTINUE TO HIGHLIGHT THIS
POSSIBILITY IN THE HWO.
THE LATEST GFS/ECMWF/GEM ALL DIFFER WITH RESPECT TO THE TIMING OF
THE LOW PIVOTING ACROSS NORTH DAKOTA AND SUBSEQUENTLY DRY CONDITIONS
FILTERING INTO THE REGION. THE LATEST ECMWF IS NOW MORE PROGRESSIVE
WITH THIS FEATURE AND PIVOTS IT THROUGH THE REGION MONDAY. THE GFS
IS ABOUT 12 HOURS SLOWER WHEREAS THE GEM IS AN AVERAGE OF THE TWO.
FOR NOW KEPT POPS IN AREAWIDE MONDAY AND FORECAST A DRYING TREND
TUESDAY THROUGH WEDNESDAY AS HIGH PRESSURE BUILDS OVER THE ROCKIES.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 636 AM CDT THU SEP 5 2013
VFR CONDITIONS WILL PREVAIL ACROSS ALL TAF SITES FOR THE 12Z TAF
PERIOD. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS
WESTERN NORTH DAKOTA DURING THE EARLY MORNING HOURS.
HOWEVER...UNCERTAINTY REMAINS TOO GREAT TO INCLUDE ANY PREVAILING
THUNDERSTORM OR SHOWER GROUP IN THE TAFS. SO HAVE INCLUDED VCSH TO
KDIK AND KISN TO INDICATE POSSIBLE TIMING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TM
SHORT TERM...LTH
LONG TERM...TM
AVIATION...LTH
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
641 AM EDT THU SEP 5 2013
.SYNOPSIS...
A MOISTURE-STARVED COLD FRONT WILL MOVE SOUTH THROUGH THE OHIO
VALLEY TODAY. BEHIND THE FRONT...HIGH PRESSURE WILL BUILD IN FOR
FRIDAY...WITH RELATIVELY COOL AND DRY CONDITIONS. AS THE HIGH
MOVES OFF TO THE EAST...A GRADUAL RETURN TO WARMER TEMPERATURES
WILL OCCUR OVER THE WEEKEND AND INTO NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A COLD FRONT IS CURRENTLY IDENTIFIABLE (BY WIND SHIFT) NEAR THE
BORDER WITH MICHIGAN...AND IT WILL BE MAKING ITS WAY SOUTH INTO
THE ILN CWA TODAY. A WIDE SUITE OF MODEL SOLUTIONS REFUSES TO
PRODUCE ANY QPF OUTPUT WITH THIS FEATURE...OWING MAINLY TO THE
DRY AIR MASS THAT THE FRONT IS MOVING INTO (PWAT VALUES AT OR
BELOW 1 INCH). THERE SHOULD BE SOME RESPONSE IN TERMS OF
STRATOCUMULUS DEVELOPMENT...SO SKY GRIDS NEAR THE FRONT INCREASE
TO AROUND 50 PERCENT. OTHERWISE...ASIDE FROM SOME HIGH
CLOUDS...SKIES SHOULD BE MOSTLY CLEAR.
THE TIMING OF THE TEMPERATURE TRACE TODAY LOOKS TO BE ROUGHLY
DIURNAL...EVEN AS THE FRONT MOVES THROUGH THE REGION. THE NORTH
HALF OF THE CWA MAY PEAK OUT SLIGHTLY EARLIER THAN NORMAL AND HOLD
SOMEWHAT STEADY GOING INTO THE AFTERNOON. THERE WILL BE A NNE-TO-
SSW GRADIENT...WITH THE WARMEST TEMPS IN SOME OF THE NORTHERN
KENTUCKY ILN COUNTIES. THE RAP MODEL HAS BEEN IGNORED FOR
TODAY...AS IT MIXES THROUGH 800MB AND PRODUCES TEMPERATURE VALUES
FAR TOO HIGH. OTHERWISE...THE REST OF THE MAIN SUITE OF MODELS IS
IN FAIRLY GOOD AGREEMENT ON TEMPS...WITH LOWER 80S IN THE SW AND
MID 70S IN THE NE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
ALTHOUGH THE SOUTHWARD-MOVING COLD FRONT WILL ALMOST CERTAINLY
COME THROUGH DRY (THOUGH A PATCH OR TWO OF TRACE PRECIP IS NOT
TOTALLY OUT OF THE REALM OF POSSIBILITY IN THE SOUTHERN CWA IN THE
LATE AFTERNOON)...THERE WILL BE A MARKED WIND SHIFT TO THE
NNE. THIS WILL BRING SOME STRONG COLD ADVECTION...SETTING THINGS
UP FOR A COOL FORECAST FOR TONIGHT. THE CENTER OF THE HIGH WILL BE
OVER PENNSYLVANIA...SO SOME LIGHT EASTERLY FLOW SHOULD STILL BE
PRESENT...MAKING THE RADIATIONAL COOLING CONDITIONS
NOT-QUITE-IDEAL. HOWEVER...THE DRYING AIR MASS AND CLEAR SKIES
WILL EASILY BE ENOUGH TO ALLOW TEMPS INTO THE LOWER 50S...WITH
UPPER 40S EXPECTED IN OUTLYING AREAS.
THE HIGH WILL STILL BE CLOSE ENOUGH TO INFLUENCE THE WEATHER
FRIDAY...WITH ONLY A SLIGHT CLOCKWISE TURN IN THE WIND
DIRECTION...AND NO REAL SIGN OF SURFACE WARM ADVECTION QUITE YET.
ON THE OTHER HAND...TEMPERATURES WILL BEGIN WARMING SLIGHTLY
ALOFT...LEADING TO AN INTERESTING FORECAST CHALLENGE. MODEL
SOUNDINGS ARE EXTREMELY SHALLOW IN MIXING FOR FRIDAY AFTERNOON
(GFS/NAM AT KCVG BOTH SHOWING ONLY AROUND 900MB-875MB).
HOWEVER...THE WARMING AIR JUST OFF THE SURFACE WILL MEAN THAT ONLY
A SMALL CHANGE IN MIXING HEIGHT WOULD CAUSE A MODERATE CHANGE IN
REALIZED SURFACE HIGH TEMPERATURES. FORECAST TEMPS ARE CLOSE TO A
BLEND OF THE RAW GFS/NAM...AND SLIGHTLY LOWER THAN THE ADJUSTED
MAV/MET GUIDANCE NUMBERS. HOWEVER...THOSE GUIDANCE NUMBERS WOULD
END UP LOOKING MORE CORRECT IF MIXING DOES GET HIGHER THAN
CURRENTLY ANTICIPATED.
A VEERING OF SURFACE WINDS WILL CONTINUE INTO THE WEEKEND...AS THE
SURFACE HIGH MOVES SOUTHEAST INTO THE DELMARVA REGION. AS THIS
OCCURS...RIDGING WILL BEGIN TO BUILD IN ALOFT. THIS WILL PUT THE
CWA IN A REGIME OF NORTHWEST FLOW ALOFT (EVENTUALLY SPILLING IN
SOME CLOUDS) AND SW FLOW AT THE SURFACE (WITH TEMPERATURES AND
DEWPOINTS BEGINNING TO RISE AGAIN). ANOTHER FRONT WILL MAKE ITS
WAY SOUTHWARD INTO THE OHIO VALLEY ON SATURDAY NIGHT INTO
SUNDAY...AND THOUGH IT ALSO LOOKS LIKE A FAIRLY DRY FRONT...THERE
IS ENOUGH MOISTURE TO SUPPORT SOME PRECIPITATION POTENTIAL. 00Z
GFS/ECMWF RUNS BOTH DEPICT THAT HIGH PRESSURE OVER THE GREAT LAKES
WILL VERY BRIEFLY ENTER THE PICTURE OVER THE OHIO VALLEY ON SUNDAY
NIGHT AND MONDAY...BEFORE RIDGING MOVES EAST AGAIN AND PUTS THE
CWA INTO A WARMER AND WETTER PATTERN FOR THE MIDDLE OF THE WEEK.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
AFTER SUNDAY...THE UPPER HIGH BUILDS AND NORTHWEST FLOW BECOMES
MORE WESTERLY IN OHIO VALLEY. SURFACE FLOW INCREASES FROM THE
SOUTHWEST ON TUESDAY. AN ISOLATED POPUP SHOWER COULD OCCUR DURING
THE HEATING OF THE DAY MONDAY AND AGAIN WITH THE INCREASED
MOISTURE WORKING IN TUESDAY...BUT THE LOW 20% COVERAGE WILL KEEP
MENTION OF SHOWERS OUT OF THE FORECAST.
UPPER RIDGE BREAKS DOWN AND A TROUGH APPROACHES FROM THE NORTHWEST
ON WEDNESDAY. IT ALSO COMES WITH A SURFACE COLD FRONT AND IS THE
FAVORED MECHANISM FOR THUNDERSTORM DEVELOPMENT IN THE EXTENDED
PERIOD.
HIGHS WILL REMAIN IN THE 80S AND COULD APPROACH 90 WITH ENOUGH
SUNSHINE. LOWS SHOULD STAY IN THE 60S BUT SOME UPPER 50S ARE
POSSIBLE IN CENTRAL OHIO SAT NIGHT AND FOR MOST AREAS SUN NIGHT WITH
DRIER AIR. THEY WILL PUSH BACK INTO THE MID TO UPPER 60S FOR THE
REMAINDER OF NEXT WEEK WITH THE RETURN OF SOUTHERLY FLOW.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
A MOISTURE STARVED COLD FRONT WILL DROP SOUTH THROUGH THE TAF
SITES THIS MORNING. ANY MIST/FOG EARLY THIS MORNING SHOULD BE GONE
BETWEEN 13Z AND 14Z DUE TO MIXING AND/OR A WIND SHIFT TO THE
NORTH.
FOR LATER TODAY...THE FRONT WILL CONTINUE SOUTH OF THE OHIO RIVER.
SOME POST FRONTAL MOISTURE AND CAA WILL RESULT IN DIURNALLY DRIVEN
SCT-BKN CUMULUS CLOUDS.
FOR TONIGHT...A SPRAWLING AREA OF HIGH PRESSURE WILL BUILD
SOUTH INTO THE NEW ENGLAND...MID ATLANTIC AND OHIO VALLEY REGION.
SKIES WILL BECOME MOSTLY CLEAR AS WINDS SHIFT TO THE EAST/NORTHEAST...
ALLOWING DRIER AIR TO FILTER BACK INTO THE AREA. SOME SHALLOW
GROUND FOG MAY BE POSSIBLE AT KILN AND RIVER FOG AT KLUK LATE
TONIGHT.
OUTLOOK...NO SIGNIFICANT WEATHER IS EXPECTED.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HATZOS
NEAR TERM...HATZOS
SHORT TERM...HATZOS
LONG TERM...FRANKS
AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
610 AM CDT THU SEP 5 2013
.DISCUSSION...
SEE 12Z AVIATION DISCUSSION.
&&
.AVIATION...
MODELS DID NOT INITIALIZE WELL OVERNIGHT. NAM AND GFS SHOW THE
BEST OMEGA FIELDS OVER THE NORTHERN TAF SITES WHILE THE HRRR AND 4
KM WRF FAVOR SHRA/TSRA ALONG COAST. AT 09Z...A WEAK TROUGH
EXTENDED FROM THE LOUISIANA COASTAL WATERS...NORTHWEST TOWARD
KCLL. FCST SOUNDINGS SHOW PW VALUES PEAKING NEAR 2.00 INCHES
BETWEEN 21-00Z. THE UPPER RIDGE OVER THE SOUTHERN PLAINS SHOULD
IMPART SOME SUBSIDENCE TODAY BUT STILL FEEL HEATING COUPLED WITH
2.0 PW AIR WILL YIELD AFTN SHRA/TSRA. GENERALLY CLEAR SKIES AND
LIGHT WINDS OVERNIGHT. COLD BE SHRA NEAR KGLS EARLY FRIDAY MORNING
AND MORE OF AN EAST WIND ON FRIDAY. 43
&&
.PREV DISCUSSION... /ISSUED 435 AM CDT THU SEP 5 2013/
DISCUSSION...
ANOTHER WARM AND MUGGY NIGHT ACROSS SOUTHEAST TEXAS THIS MORNING
WITH TEMPERATURES IN THE MID 70S IN MOST LOCATIONS. THERE IS A
POSSIBILITY OF SOME PATCHY FOG IN RURAL AREAS THIS MORNING
(ESPECIALLY AREAS THAT HAVE SEEN RAIN) AS NEARLY CALM WINDS HAS
ALLOWED DEWPOINT DEPRESSIONS TO DROP TO AROUND A DEGREE OR TWO IN
SOME LOCATIONS. THERE ALSO HAS BEEN SOME RAIN IN THE GULF THIS
MORNING AS A WEDGE OF VORTICITY MOVES ACROSS THE AREA.
MODELS AGAIN APPEAR TO BE HAVING DIFFICULTY WITH HANDLING MOISTURE
VALUES ACROSS THE AREA. ACCORDING TO GPS MET KCLL PWAT VALUES HAVE
HELD STEAD AROUND 1.8 - 1.9" THE LAST TWO DAYS WHILE BOTH NAM AND
GFS FORECAST SOUNDINGS HAVE SHOWN PWAT VALUES DROPPING TO AROUND
1.6". AGAIN TODAY GFS AND NAM FORECAST SOUNDINGS SHOW PWAT VALUES
AROUND 1.6" AND 1.5" RESPECTIVELY. BOTH FORECAST SOUNDINGS ALSO
SHOW DRY AIR IN THE MID-LEVELS. THE KLCH 0Z SOUNDING SHOWS A PWAT
OF 2.12" WHILE KFWD 0Z SOUNDINGS SHOWS A PWAT OF ONLY 1.10". GIVEN
THE GPS MET DERIVED PWAT FEEL THAT OUR AREA IS MORE REPRESENTED BY
THE KLCH SOUNDING. GFS AND NAM OMEGA FIELDS ARE HINTING AT LIFT
NORTH OF I-10 TODAY AND GIVEN THE MOISTURE VALUES IN PLACE
SCATTERED SHOWERS AND THUNDERSTORMS AGAIN LOOK POSSIBLE. BEST
UPPER LEVEL DIFFLUENCE STILL APPEARS TO BE OFF TO THE EAST TODAY
THOUGH.
THE UPPER LEVEL RIDGE CURRENTLY OVER COLORADO WILL CONTINUE TO
MOVE EASTWARDS THIS WEEKEND. THE TROPICAL WAVE CURRENTLY LOCATED
OVER THE YUCATAN WILL DRIFT EASTWARD FRIDAY INTO SATURDAY. WITH
THE RIDGE TO THE NORTH THE BEST CHANCES OF RAIN APPEAR TO BE IN
THE SOUTHERN ZONES AND OFFSHORE WATERS. THE NEXT TROPICAL WAVE
WILL APPROACH THE AREA LATE TUESDAY INTO EARLY WEDNESDAY. THE GFS
WEAKENS THE UPPER LEVEL RIDGE ALLOWING THE WAVE TO DRIFT FARTHER
NORTHWARDS WILL THE ECMWF SHOWS A SLIGHTLY STRONGER RIDGE WHICH
KEEPS THE WAVE FURTHER SOUTH. A SLIGHT DEVIATION IN THE TRACK OF
THE UPPER LEVEL RIDGE COULD DRASTICALLY CHANGE TO AMOUNT OF RAIN
SEEN ACROSS THE REGION. MODELS HAVE ALSO SHOWN LITTLE CONSISTENCY
ON THIS FEATURE THE LAST COUPLE OF DAYS. MADE ONLY MINOR CHANGES
TO POPS GIVEN LACK OF CONSISTENCY IN MODELS. 23
MARINE...
A RELATIVELY WEAK PRESSURE GRADIENT WILL REMAIN IN PLACE WITH LIGHT
ONSHORE WINDS EXPECTED. A SERIES OF WEAK EASTERLY WAVES WILL MOVE
INTO MEXICO WITH THE FIRST WAVE MOVING TOWARD THE MEXICAN COAST ON
TONIGHT INTO FRIDAY AND A SECOND STRONGER WAVE MOVING INLAND ON
SUNDAY. THIS SHOULD SUPPORT EASTERLY WINDS AND SEAS AROUND 3 FEET.
SLIGHTLY HIGHER SEAS WILL BE POSSIBLE SUN-MON DUE TO PERSISTENT EAST
TO SOUTHEAST WINDS. THE PERSISTENT E-SE WINDS WILL ALSO PRODUCE A SUBTLE
INCREASE IN TIDE LEVELS. 43
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 98 75 98 75 97 / 30 10 20 10 20
HOUSTON (IAH) 97 76 97 75 96 / 30 20 20 20 20
GALVESTON (GLS) 90 80 89 80 89 / 30 20 30 20 30
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...23
AVIATION/MARINE...43
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
615 AM CDT THU SEP 5 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 346 AM CDT THU SEP 5 2013
CURRENT WATER VAPOR COMBINED WITH RAP 500MB ANALYSIS SHOWS A HIGHLY
AMPLIFIED RIDGE IN PLACE JUST EAST OF THE COLORADO/NORTHERN/CANADIAN
ROCKIES WITH OUR AREA IN NORTHWEST FLOW ALOFT. AT THE SURFACE...A
BROAD AREA OF HIGH PRESSURE EXTENDED SOUTHWARD OUT OF ONTARIO CANADA
THROUGH THE UPPER MISSISSIPPI RIVER VALLEY REGION...INTO THE MID AND
SOUTHERN MISSISSIPPI RIVER REGION. EAST/NORTHEAST SURFACE FLOW OFF
LAKE MICHIGAN WAS COMBINING WITH A RATHER HUMID LOWER BOUNDARY LAYER
TO PRODUCE AN EXPANDING STRATUS FIELD ACROSS SOUTHEAST WI/SOUTH
CENTRAL WI. THIS STRATUS MAY PROVE TO BE PROBLEMATIC TODAY ACROSS
THE SOUTHEAST PORTION OF THE FORECAST AREA. OTHERWISE...TEMPERATURES
ACROSS THE AREA EARLY THIS MORNING RANGED FROM THE 40S ACROSS
NORTHERN WI...TO THE MIDDLE AND UPPER 60S ALONG AND SOUTH OF THE
I-94 CORRIDOR.
FOR TODAY...WILL BE WATCHING THIS AFOREMENTIONED STRATUS CLOSELY.
RAP SOUNDINGS SHOW THIS CLOUD THINNING AS THE MORNING PROGRESSES
FROM NORTHEAST TO SOUTHWEST AS HIGH PRESSURE BUILDS OVER THE GREAT
LAKES AND DRIER AIR GETS ENTRAINED INTO THE BOUNDARY LAYER. THE NAM
AND RAP ARE HINTING AT SOME -SHRA ALONG AND WEST OF TE MISSISSIPPI
RIVER THIS AFTERNOON IN DAYTIME HEATING. HOWEVER...THERE IS NO
FORCING MECHANISM TO TRIGGER THESE SHOWERS. WILL KEEP DRY FOR NOW
BUT WARRANTS WATCHING. WITH LIGHT EASTERLY WINDS...LOOK FOR HIGH
TEMPERATURES TODAY IN THE MIDDLE 70S TO THE LOWER 80S.
ATTENTION THEN TURNS TO NORTHWEST FLOW ALOFT TONIGHT WITH AN
EMBEDDED/WEAKENING SHORTWAVE TROUGH HEADING SOUTHEAST THROUGH THE
NORTHERN PLAINS INTO MN. NAM SHOWING AN INCREASING CORRIDOR OF
850-700MB ISENTROPIC LIFT AND MOISTURE TRANSPORT AHEAD OF THIS WAVE
ACROSS THE PLAINS INTO NORTHWEST MN. PLAN ON SOME INCREASE IN
MID-LEVEL CLOUDS/ACCAS ACROSS PORTIONS OF SOUTHEAST MN INTO
NORTHWEST WI ON THE EASTERN FRINGES OF THIS FORCING. ANY SHRA
ACTIVITY IS EXPECTED TO STAY NORTHWEST OF THE AREA TOWARD THE BETTER
MOISTURE TRANSPORT. ANOTHER MITIGATING FACTOR IN SHOWER CHANCES
ACROSS NORTHWEST IS THE VERY-HIGH BASED NATURE OF THE CLOUDS AND DRY
LOWER LEVELS FOR EVAPORATION OF SHOWERS FROM THESE CLOUDS...WITH
JUST VIRGA EXPECTED. BASED ON THIS SIGNAL...WENT WITH A DRY FORECAST
OVERNIGHT. OTHERWISE...SOUTHERLY AIRFLOW AND INCREASING DEW POINTS
SHOULD KEEP OVERNIGHT LOWS UP IN THE 50S TO LOWER 60S.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 346 AM CDT THU SEP 5 2013
ON FRIDAY...WILL BE WATCHING A SURFACE COLD FRONT PUSHING SOUTHEAST
OUT OF CANADA INTO NORTHERN WI THROUGH CENTRAL MN BY LATE IN THE
AFTERNOON. CORRIDOR OF BEST 850-700MB MOISTURE TRANSPORT AND
ISENTROPIC LIFT STAYS NORTH OF THE AREA WITH JUST SOME INCREASE IN
MID/HIGH CLOUDS EXPECTED ACROSS OUR AREA. OF NOTE WILL BE INCREASING
SOUTHWEST WINDS AND WARM AIR ADVECTION INTO OUR AREA WITH 925MB
TEMPERATURE INCREASING INTO THE 25-28C BY AFTERNOON. THIS SHOULD
YIELD HIGH TEMPERATURES IN THE MID-UPPER 80S...WITH A COUPLE
LOCATIONS FLIRTING WITH THE 90 DEGREE MARK.
FOR FRIDAY NIGHT THROUGH SATURDAY...LOOK FOR THE COLD FRONT TO SINK
SLOWLY SOUTHEAST ACROSS THE AREA. CONTINUED 850-700MB MOISTURE
TRANSPORT/ISENTROPIC LIFT AND WEAK CONVERGENCE ALONG THIS FRONTAL
BOUNDARY SHOULD BE SUFFICIENT FOR ISOLATED-SCATTERED
SHOWER/THUNDERSTORMS. OF NOTE THOUGH IS A FAIRLY STRONG CAP ON
SATURDAY INDICATED BY THE NAM SOUNDING WHICH MAY LIMIT CONVECTION OR
KEEP IT VERY ELEVATED AND SPARSE IN NATURE. EVEN WITH CLOUDS...
LOOKING FOR HIGHS IN THE 80S. LINGERING SHOWER/THUNDERSTORM CHANCES
WILL BE SEEN SATURDAY NIGHT MAINLY SOUTH OF I-90 AS THE FRONT EXITS
THE AREA.
SUNDAY LOOKS DRY AND SLIGHTLY COOLER AS HIGH PRESSURE BUILDS IN FROM
ONTARIO CANADA INTO THE GREAT LAKES REGION.
LOOK FOR THE HIGH TO SLIDE INTO THE NORTHEAST U.S. SUNDAY NIGHT AS
LOW PRESSURE PUSHES OUT OF THE INTERMOUNTAIN WEST INTO THE NORTHERN
PLAINS. THIS PUSHES A WARM FRONT INTO MN/IA AFTER MIDNIGHT WITH
INCREASING 850MB MOISTURE TRANSPORT NOSING INTO THE AREA FOR A
CHANCE OF SHOWERS AND THUNDERSTORMS. SHOWER AND THUNDERSTORM CHANCES
CONTINUE THROUGH MONDAY AS THE WARM FRONT PUSHES THROUGH THE AREA.
WILL HAVE TO WATCH FOR A SEVERE THREAT DURING THIS TIME FRAMES AS
WELL WITH THE GFS INDICATING 1000-1500J/KG 0-1KM MLCAPE WITH AROUND
35KT OF 0-3KM SHEAR SUNDAY NIGHT AND 2000-2500J/KG AND 25-30KT 0-3KM
SHEAR ON MONDAY. PLAN ON HIGHS IN THE MID 70S/LOWER 80S ON
SUNDAY...AND UPPER 70S/MIDDLE 80S MONDAY.
THE GFS AND ECMWF SHOW A COLD FRONT PUSHING INTO THE AREA MONDAY
NIGHT AND HANGING UP ACROSS THE AREA THROUGH WEDNESDAY FOR A
CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS. HIGHS TUESDAY ARE
EXPECTED TO TOP OFF AGAIN IN THE 80S...COOLING SLIGHTLY ON WEDNESDAY
INT THE UPPER 70S TO MIDDLE 80S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 615 AM CDT THU SEP 5 2013
IN WHAT HAS BEEN A VFR REGIME HAS SOME CHALLENGES THIS MORNING AS
LOW LEVEL STRATUS DECK ADVECTING IN FROM THE EAST IS APPROACHING
MISSISSIPPI RIVER AT DAYBREAK WITH PATCH OF IFR CEILINGS. HOW FAR
WEST IT MIGRATES AND HOW LONG IT MIGHT LAST IS PROBLEMATIC.
MOST WISCONSIN LOCALES DEALING WITH IFR CONDITIONS...WHILE WEST OF
THE RIVER VFR CONDITIONS STILL PREVAIL. FEELING IS STRATUS DECK WILL
CONTINUE TO PUSH WEST THIS MORNING AND THEN PROBABLY HANG UP FOR
MUCH OF THE MORNING BEFORE EARLY SEPTEMBER SUN BEGINS TO BREAK IT
UP. SHORT TERM GUIDANCE SUGGEST DRY LAYERS ABOVE IT SHOULD HELP TO
BREAK IT UP SOMETIME THIS MORNING BUT THIS WILL HAVE TO WATCHED.
VFR CONDITIONS SHOULD RETURN LATER IN THE DAY AND AS SOUTHEAST FLOW
DEVELOPS TONIGHT...COULD SEE SOME MVFR VISIBILITIES RETURN AS
MOISTURE REMAINS HUNG UP ALONG BOUNDARY SITTING JUST TO THE SOUTH.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM...DAS
AVIATION...SHEA
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1231 PM CDT THU SEP 5 2013
.SHORT TERM.../TODAY/...
ISSUED AT 355 AM CDT THU SEP 5 2013
WEAK ELEVATED SHOWER ACTIVITY LOOKS TO CONTINUE THROUGH THE MID
MORNING HOURS OVER THE WESTERN EDGES OF THE FORECAST AREA. THE
WEAK AREA OF VORTICITY ADVECTION BETWEEN 700-300MB WILL DISSIPATE
BY AROUND 18Z. SOUNDINGS BELOW 10KFT REMAIN VERY DRY AND NOT
EXPECTING MUCH QPF...IF ANY AT ALL...WITH THESE SHOWERS. KEPT
THUNDER OUT OF THE FORECAST ATTM AS LITTLE TO NO INSTABILITY
PRESENT THIS MORNING. THE 09.05 05Z HRRR HAS A DECENT HANDLE ON
THE OVERALL RADAR TRENDS THIS MORNING...BUT HAS SHOWERS LINGERING
PAST 18Z. FELT CONFIDENT ENOUGH TO KEEP FORECAST DRY AFTER 16Z
THIS MORNING WITH THE LACK OF FORCING AND MOISTURE AVAILABLE. USED
A BLEND OF THE 09.05 00Z NAM12/ECMWF FOR MAX TEMPS TODAY EVEN WITH
THE MID TO HIGH LEVEL CLOUD COVER THIS MORNING.
.LONG TERM.../TONIGHT THROUGH WEDNESDAY/...
ISSUED AT 355 AM CDT THU SEP 5 2013
MAIN CONCERNS THROUGH EARLY NEXT WEEK CONTINUE TO BE SUBTLE MINIMAL
PRECIP CHANCES AND WARMER TEMPS THROUGH EARLY NEXT WEEK. IA WILL
REMAIN IN NW FLOW INTO FRI WITH LOW CONFIDENCE IN PRECIP TRENDS.
MODELS CONTINUE TO GENERATE SPOTTY QPF BUT CANNOT REALLY FIND ANY
SUBSTANTIAL KINEMATIC OR THERMODYNAMIC FEATURES TO KEY ON...SO WITH
SURFACE BASED POTENTIAL NIL...WILL LEAVE FORECAST DRY. COULD BE
SOME WEAK VERY ELEVATED CONVECTION...BUT CONFIDENCE IN TIMING AND
LOCATION IS NOT GREAT ENOUGH TO MENTION. WARM ADVECTION DOES LIFT
THROUGH FRI DURING THE DAY...BUT MOISTURE SEEMS SOMEWHAT LIMITED AND
ITS DAYTIME TIMING WOULD NOT BE CLIMATOLOGICALLY FAVORED. HAVE
WAITED TO INTRODUCE SLIGHTS NE FRI NIGHT WHEN MOISTURE INCREASES A
BIT.
THE BIGGEST SENSIBLE WEATHER REFLECTION MAY BE TEMPERATURES WARMING
FURTHER HOWEVER WITH WIDESPREAD HIGHS ABOVE 90F. A WEAK BOUNDARY
WILL SAG INTO NRN IA SAT...BUT WILL NOT CHANGE THE AIRMASS MUCH
KEEPING TEMPS FAIRLY STATIC NORTH AND EVEN WARMING A FEW DEGREES TO
ITS SOUTH WITH PLENTY OF HIGHS IN THE MID 90S I80 INTO MO.
BAROCLINIC ZONE STRENGTHENS SLIGHTLY SAT NIGHT AS FRONT CONTINUES
TO DRIFT FARTHER SOUTH SO HAVE PUSHED FRI NIGHT SLIGHTS DOWN INTO
CENTRAL AND SRN IA BY THAT TIME. ANYTHING IN THIS TIME RANGE WOULD
LIKELY BE QUITE ELEVATED ABOVE THE ELEVATED MIXED LAYER.
THETA-E/WARM ADVECTION STRENGTHENS CONSIDERABLY BY LATE SUN FROM
IA/MN BORDER INTO THE NRN PLAINS. THIS WILL ALLOW TEMPS TO REBOUND
ONCE AGAIN AFTER BRIEFLY DROPPING A TAD SUN. THE STRONGER
THERMODYNAMIC FORCING ALSO STILL SUPPORTS MAINLY NOCTURNAL PRECIP
CHANCES NORTH...WITH BEST POTENTIAL NORTH OF IA.
WAVE CURRENTLY OFF THE OR COAST VERY SLOWLY BUT SURELY TOPS THE
ROCKIES RIDGE BY EARLY NEXT WEEK AND EVENTUALLY RESULTS IN MORE
ORGANIZED SYNOPTIC SCALE FORCING. THIS LIFT WILL SLOWLY PUSH SOUTH
AND EAST COINCIDENT WITH THE FRONTAL BOUNDARY AND LIKELY BRING OUR
BEST WINDOW OF PRECIP CHANCES LATE TUE INTO WED. THE FRONTAL
PASSAGE WILL ALSO DROP OUR TEMPS BACK CLOSER TO NORMAL FOR WED.
&&
.AVIATION...05/18Z
ISSUED AT 1231 PM CDT THU SEP 5 2013
VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD WITH NO
PRECIPITATION FORECAST. THERE IS A CHANCE THAT LIGHT BR COULD FORM
EARLY FRIDAY MORNING AROUND KMCW/KALO...BUT CONFIDENCE IS TOO LOW
TO MENTION IN THE TAFS AT THIS TIME.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...PODRAZIK
LONG TERM...SMALL
AVIATION...LEE
AREA FORECAST DISCUSSION
NWS TOPEKA KS
317 PM CDT Thu Sep 5 2013
.SHORT TERM...(This Evening through Friday)
Issued at 243 PM CDT THU SEP 5 2013
Upper level high remains centered over Colorado through tomorrow
while a surface high continues to retreat eastward. An area of
isolated showers has continued to move closer to our northern
areas...although most of the precip is not reaching the ground. The
12z NAM supports moisture convergence in this area along with an
axis of slight elevated instability which extends into northeast
Kansas. The HRRR has also been consistent with bringing these
showers into our area. If showers are able to persist within the dry
air and weak advection only northern row of counties look to be
affected the next few hours with an overall diminishing trend
towards the evening.
High temperatures look to reach the low to mid 90s today which is
above normal for this time of year. The skies will remain partly
cloudy especially across northern areas closer to the ongoing shower
activity. Tonight WAA will again set up across eastern Nebraska well
north of the northeast Kansas to keep the entire area dry. Low
temperatures tonight appear to be on track for the mid to upper 60s.
Low level winds will gradually veer allowing warming 850 temps to
spread into eastern KS therefore high temperatures will make it into
the low to mid 90s again tomorrow. With more mixing likely tomorrow
during the day winds will likely increase to around 10 mph with
gusts up to 20 mph possible.
.LONG TERM...(Friday Night through Thursday)
Issued at 243 PM CDT THU SEP 5 2013
The forecast for Friday night through Tuesday is essentially one
of persistence. Other than subtle day to day differences, the
weather pattern will be fairly stagnant through the period with a
large area of upper level high pressure slowly drifting from west
to east across the plains and into the Ohio valley. High
temperatures will be consistently in the 90s. The hottest day
currently appears to be Saturday with southwest surface winds, the
upper ridge almost directly overhead, and the warmest 850 temps of
the week in place all pointing to highs in the middle to upper
90s. There will be a couple of very weak upper disturbances that
may provide enough lift for a shower or thunderstorm, mainly
northeast of the local forecast area along a weak convergence
zone, late on Saturday. Will watch these features in future
forecasts but expect dry conditions for the most part through the
weekend.
There are a couple of stronger northern stream short wave troughs
that come over the top of the ridge next week. The trough crossing
the Dakotas on Monday will push a cold front to the south, but
expect this front to lose its forward progression and stall over
northern Nebraska. The second of the stronger troughs will cross
the Dakotas late Tuesday and should successfully push the cold
front through the forecast area by late Wednesday. Much of the
upper forcing will remain well to the north, and surface
convergence is not expected to be particularly strong, but may be
sufficient for scattered storms along the incoming front. Cooler
and drier air with almost meridional flow aloft will follow the
frontal passage and expect the end of next week to be both cooler
and dry.
&&
.AVIATION...(For the 18Z TAFs through 18Z Friday Afternoon)
Issued at 1233 PM CDT THU SEP 5 2013
VFR conditions are expected through the taf period. Winds will
remain under 10 kts and gradually veer to the south through the
period.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Sanders
LONG TERM...Barjenbruch
AVIATION...Sanders
AREA FORECAST DISCUSSION
NWS TOPEKA KS
134 PM CDT Thu Sep 5 2013
.UPDATE...
Issued at 120 PM CDT THU SEP 5 2013
An area of showers with isolated thunder has continued to develop
across south central Nebraska. The 12z NAM shows that there has
been moisture convergence in this area along with an axis of
slight elevated instability which extends into northeast Kansas.
The HRRR has also been consistent with bringing these showers into
our area. These showers only look to affect the row of counties
along the NE/KS state line during the afternoon hours.
Therefore...have increased the pops and mentioned isolated
showers and thunder until 7pm this evening in the latest forecast
update.
&&
.SHORT TERM...(Today and Tonight)
Issued at 301 AM CDT THU SEP 5 2013
Upper level pattern remains nearly locked in place with upper
high centered over the Rockies and modest but widespread 500mb
height rises across the bulk of the CONUS. Mid levels again
showing a stronger though still not impressive temperature
gradient across Nebraska from west to east, with much drier
conditions to the south. Diurnal upswing in isolated to scattered
convection again taking place in eastern Nebraska in recent hours.
Moisture is a bit richer than that of Wednesday morning, but
again support for continued precipitation this far downstream
diminishes quickly. Anything more than very isolated coverage of
measurable precip seems unlikely. Higher level cloud to again
spread across eastern Kansas today with low levels continuing to
warm a bit and should support highs a bit above Wednesday`s
levels. Mid level WAA regime sets up again to the north tonight,
though not quite as robust as current conditions and will keep
any precip mention out.
.LONG TERM...(Friday through Wednesday)
Issued at 301 AM CDT THU SEP 5 2013
As the upper ridge advances eastward, so does the warmup that
comes along with it. 850mb temps in the 21-24C range rise to 22-26
Saturday into Sunday with the warmest west and north. Strong push
of cold air dropping into the Great Lakes comes toward the
forecast area from the east by Sunday morning, but think warm air
in place and strength of the ridging will keep precip chances east
of our area. A hot late week into weekend with highs in the middle
90s quite common across the entire area.
Start to see a pattern shift into next week as the upper trof over
the west coast rides across the northern periphery of the ridge on
Monday. This sets up a front across the northern plains, and speed
to which it can advance to the south will impact temperature and
precipitation forecasts for mid week. At this time, Monday looks
to remain warm as the thermal ridge is driven to flatten to more
of a SW to NE orientation and leaves warm temperatures over the
state, and would bring another day with highs well into the 90s.
Would expect similar conditions Tuesday as front knocks on the KS
NE border by late Tuesday afternoon. EC showing better signs of a
break in the hot pattern, along with the GFS, and now has a
stronger shortwave trof dropping southward across the Rockies and
reinforces a southern push for the front. Boundary would come
through sometime on Wednesday and finally have cooler highs
forecast and precip chances in the forecast.
&&
.AVIATION...(For the 18Z TAFs through 18Z Friday Afternoon)
Issued at 1233 PM CDT THU SEP 5 2013
VFR conditions are expected through the taf period. Winds will
remain under 10 kts and gradually veer to the south through the
period.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Sanders
SHORT TERM...65
LONG TERM...67
AVIATION...Sanders
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1135 AM MDT THU SEP 5 2013
.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 250 AM MDT THU SEP 5 2013
STUBBORN UPPER HIGH WILL REMAIN PARKED OVER THE FORECAST AREA
THROUGH SATURDAY...AFTER WHICH TIME THE UPPER LOW OVER THE PAC NW
WILL BEGIN TO NUDGE IT EAST. AT THE SURFACE THE WEAK TROUGH OVER
EASTERN COLORADO WILL REMAIN IN PLACE RESULTING IN SOUTHERLY
SURFACE FLOW.
NO CHANGES WORTH NOTING FROM PREVIOUS FORECAST IN TERMS OF MAX-MIN
TEMPS AND WINDS. HIGHS WILL CONTINUE IN THE 95-102 RANGE WITH LOWS
IN THE 60S. NO PRECIP IS EXPECTED DURING PERIOD AFTER THIS
MORNING. DID INCLUDE SLIGHT CHANCE POPS FROM YUMA COUNTY EAST TO
RED WILLOW FOR EARLY THIS MORNING TO ACCOUNT FOR CURRENT RADAR
TRENDS. EVEN THOUGH SHOWERS CONTINUE TO WEAKEN JUST TO OUR NORTH
OVER PHILLIPS AND CHASE COUNTIES...WILL KEEP LOW POPS GOING FOR A
FEW HOURS AFTER SUNRISE. LAST SEVERAL RUNS OF HRRR SUGGEST SOME
PRECIP MAY LINGER A BIT INTO THE MORNING HOURS. OTHERWISE...TODAY
THROUGH SATURDAY WILL BASICALLY BE A REPEAT OF YESTERDAY.
.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 250 AM MDT THU SEP 5 2013
THE 500MB HIGH IS STILL CENTERED OVER KANSAS AND BEGINS TO MOVE
EAST SUNDAY NIGHT INTO MONDAY WHILE THE UPPER LOW/TROUGH OVER THE
PACIFIC NORTHWEST MOVES INTO THE NORTHERN PLAINS. SUNDAY THROUGH
MONDAY SHOULD REMAIN WARM AND DRY...WITH HIGHS IN THE MID TO UPPER
90S. MODELS STILL DISAGREE OVER TIMING AND PLACEMENT OF THE COLD
FROPA NEXT WEEK...GFS HAS IT MOVING THROUGH MORE QUICKLY ON MONDAY
NIGHT INTO TUESDAY WHILE THE ECMWF HAS IT MOVING THROUGH TUESDAY
INTO TUESDAY NIGHT. AS OF RIGHT NOW...WEDNESDAY LOOKS TO BE THE
COOLEST DAY WITH NEAR NORMAL HIGH TEMPERATURES IN THE LOW TO MID
80S. TEMPERATURES MAY NEED ADJUSTING AS THE WEEK PROGRESSES AND
THE TIMING/PLACEMENT OF THE FRONT IS MORE SOLID. THE ALLBLEND
SOLUTION FOR TEMPERATURES AND PRECIPITATION SEEMED LIKE THE BEST
WITH THE CURRENT MODEL DIFFERENCES. THERE WERE MINOR ADJUSTMENTS
TO PRECIP...REMOVING THE 15 POP IN EASTERN COLORADO ON MONDAY
AFTERNOON CONSIDERING THE RIDGE WILL STILL BE IN PLACE...AND THERE
IS NO FEATURE THAT WOULD INDICATE PRECIP. OTHER THAN THAT...PRECIP
CHANCES ARE STILL THE GREATEST IN THE MONDAY NIGHT THROUGH
WEDNESDAY TIME FRAME. GFS HAS PWATS AROUND 1.50 ON TUESDAY
WHICH...GIVEN THE FRONT MOVING THROUGH AND NORTHEASTERLY/EASTERLY
FLOW BEHIND THE FRONT...COULD RESULT IN SOME GOOD RAINFALL AMOUNTS
WITH THE SHOWERS AND THUNDERSTORMS THAT MOVE THROUGH THE CWA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1133 AM MDT THU SEP 5 2013
VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. GUSTS TO NEAR 20
KNOTS THIS AFTERNOON WILL END NEAR SUNSET.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DLF
LONG TERM...ALW
AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
411 PM EDT THU SEP 5 2013
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 410 PM EDT THU SEP 5 2013
WV IMAGERY AND RUC ANALYSIS INDICATED NW MID/UPPER LEVEL FLOW
THROUGH THE GREAT LAKES BETWEEN A TROUGH OVER NE CANADA AND A RIDGE
FROM COLORADO INTO THE WRN PLAINS. THE MAIN UPSTREAM SHORTWAVE
TROUGH OF INTEREST WAS MOVING INTO WEST CENTRAL SASK. AT THE
SFC...HIGH PRES WAS CENTERED OVER MI AND THE WRN GREAT LAKES
BRINGING CLEAR SKIES AND LIGHT WINDS TO THE REGION.
TONIGHT...MAINLY CLEAR SKIES THIS EVENING ARE EXPECTED TO GIVE WAY
TO INCREASING MID/HIGH CLOUDS LATE. TEMPS MAY DROP OFF QUICKLY AFTER
SUNSET BUT WITH INCREASING SW FLOW OVERNIGHT...TEMPS ARE EXPECTED TO
ONLY DROP TO AROUND CENTRAL 50 AND BECOME STEADY OR SLOWLY RISING IN
THE MID TO UPPER 50S WEST.
FRIDAY...THE SASK SHRTWV IS EXPECTED TO SLIDE JUST NORTH OF LAKE
SUPERIOR. HOWEVER...925-700 MB THETA-E ADVECTION AHEAD OF THIS
FEATURE AND ASSOCIATED 310K ISENTROPIC LIFT WILL SUPPORT SCT ELEVATED
SHRA/TSRA INTO N AND W LAKE SUPERIOR BY LATE MORNING THAT MAY SPREAD
INTO THE CNTRL AND EAST DURING THE AFTERNOON. THERE IS STILL ENOUGH
UNCERTAINTY WITH MDLS DIFFERING ON TIMING/POSITION OF THE PCPN TO
KEEP JUST CHANCE POPS. ALTHOUGH MUCAPE VALUES TO AROUND 1K J/KG
RANGE MAY SUPPORT SOME STRONGER STORMS...THE GREATER INSTABILITY
WITH MLCAPES OF 1000-1500 J/KG IS EXPECTED TO REMAIN UPSTREAM OVER
MN. EVEN WITH INCREASING CLOUDS AND PCPN POSSIBLE DURING THE
AFTERNOON...HIGH TEMPS SHOULD CLIMB INTO THE LOWER 80S.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 410 PM EDT THU SEP 5 2013
MAIN FCST CONCERNS IN THE LONGER TERM REVOLVE ARND POPS ON FRI
NGT/SAT ASSOCIATED WITH PASSAGE OF SHRTWVS IN NW FLOW ALF BTWN THE
MEAN TROF OVER QUEBEC AND RIDGE IN THE PLAINS. FOCUS FOR LATER IN
THE WEEKEND TURNS TOWARD HI PRES BLDG INTO THE UPR LKS.
FRI NGT/SAT...A SHRTWV EMBEDDED IN THE NW FLOW ALF IS PROGGED TO
PASS NEAR THE UPR LKS IN THE EVNG...SO EXPECT THE BEST CHC OF
SHRA/TS TO BE IN THE EVNG WHEN ACCOMPANYING PVA INTERACTS WITH AXIS
OF HIER H85 THETA E. MID LVL DRYING/NEGATIVE H85 THETA E AVCTN IN
THE WAKE OF THIS INITIAL SHRTWV PASSAGE WL THEN RESULT IN
DIMINISHING POPS NW-SE THRU SAT MRNG...BUT APRCH OF ANOTHER SHRTWV
IN THE NW FLOW ALF WARRANTS AT LEAST A SCHC OF LINGERING SHRA. THE
12Z GFS AND ESPECIALLY THE 00Z CNDN MODELS ARE SLOWER/STRONGER THAN
THE BULK OF THE OTHER GUIDANCE WITH THIS TRAILING
DISTURBANCE...LINGERING DEEP LYR QVECTOR CNVGC AND QPF THRU MOST OF
THE DAY ON SAT...SO RETAINED SOME LO CHC POPS ESPECIALLY OVER THE
SCENTRAL THRU THE ENTIRE DAY.
SAT NGT THRU SUN...CNDN HI PRES UNDER CONFLUENT NW FLOW ALF BTWN THE
TROF IN QUEBEC/RDG IN THE PLAINS IS PROGGED TO SHIFT FM MANITOBA AT
00Z SUN TO OVER LK SUP SUN AFTN. UNDER LARGER SCALE SUBSIDENCE AND
PWAT FCST AOB 0.50 INCH...DRY WX WL PREVAIL. THE ONLY CONCERN IS
WHETHER THERE WL BE ANY LO CLDS AT LEAST FOR A TIME NEAR LK SUP WITH
UPSLOPE NNE FLOW UNDER SHARP SUBSIDENCE INVRN H85-9 IN ADVANCE OF
THE INCOMING SFC HI AS SUGGESTED BY THE 06Z AND 12Z GFS RUNS. GIVEN
LARGE SCALE ACYC LLVL FLOW...DRY NATURE OF INCOMING AIRMASS AND
MARGINAL CHILL OF THIS AIRMASS FOR LK CLDS /H925 TEMPS NO LOWER THAN
6-7C OVER THE E HALF COMPARED TO OPEN WATER TEMPS 14-15C/...
RESTRICTED FCST OF SCT-BKN LO CLDS TO THE HIER TERRAIN OF THE
NCENTRAL EARLY SUN MRNG PER THE MORE PESSIMISTIC GFS FCST SDNGS AND
BEFORE DAYTIME HEATING WOULD MIX THESE CLDS OUT ON SUN AFTN. TEMPS
ON SUN MRNG/AFTN WL BE COOLER THAN THE DAY BEFORE WITH H85 TEMPS
FCST BTWN 5-10C DURING THIS PERIOD. EXPECT THE LOWEST MIN TEMPS ON
SUN MRNG OVER THE INTERIOR W...WITH NNE FLOW OFF LK SUP KEEPING
AREAS NEAR THE SHORE WARMER.
SUN NGT...AS SFC HI PRES DRIFTS OVER NY STATE BY 12Z SUN...A RETURN
SLY FLOW OF WARMER/MOISTER AIR BTWN THIS FEATURE AND A SHRTWV/
ACCOMPANYING SFC LO MOVING INTO THE NRN PLAINS WL DVLP OVER THE UPR
LKS. SO EXPECT AT LEAST SOME INCRS IN CLDS AND A WARMER OVERNGT.
RESTRICTED POPS TO THE FAR WRN CWA GIVEN MODEL QPF/LINGERING LLVL
DRY AIR OVER MOST OF THE CWA.
MON INTO TUE...AS SHRTWV IN THE NRN PLAINS AND ATTENDANT SFC LO PRES/
WARM FNT MOVE TOWARD THE UPR LKS...EXPECT SHRA/TS CHCS TO INCRS OVER
THE CWA. NOT SURPRISINGLY...THE EXTENDED MODELS DISAGREE ON THE
EXACT TRACK OF THE SFC LO/WARM FNT AND AXIS OF HIER QPF. THE 12Z AND
ESPECIALLY THE 00Z CNDN MODELS ARE FARTHER N WITH THE SFC LO TRACK/
WARM FNT AND FCSTS THE BULK OF ANY ACCOMPANYING SHRA/TS TO REMAIN N
OF UPR MI WHILE THE 06Z GFS FCSTS HEAVY PCPN WITH THE SFC LO
TRACKING E THRU THE CWA OVER THE WARM FNT ON MON INTO EARLY TUE. THE
RESULT OF THIS SCENARIO WOULD BE A WARM SUMMER-LIKE DAY WITH A GOOD
DEAL OF SUNSHINE AND H85/SFC TEMPS NEAR 20C/WELL INTO THE 80S AWAY
FM LK MODERATION IN LLVL SW FLOW. SHRA/TS WITH HEAVY RA/PSBL SEVERE
TS WOULD BE THE RESULT IF THE GFS MODEL VERIFIES. THE 12Z GFS/00Z
ECWMF RUNS ARE A COMPROMISE BTWN THOSE TWO CAMPS AND ALSO INDICATE
THE POTENTIAL FOR SEVERE TS WITH FCST H85 TEMPS UP TO 20C AND SSI AS
LO AS -3 TO -4C UNDER STRONGER H5 FLOW. GIVEN THESE UNCERTAINTIES...
MAINTAINED CONSENSUS FCST FOR NOW.
EXTENDED...AS AN UPR TROF DEEPENS INTO THE GREAT LKS ON WED BEHIND
DEPARTING SHRTWV RESPONSIBLE FOR THE MON/TUE POPS...EXPECT SHRA/TS
CHCS TO PERSIST. EXPECT COOLER/DRIER WX TO SPREAD TO THE E NEXT
THU/FRI AS HI PRES BLDS TOWARD THE PLAINS/WRN GRT LKS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 131 PM EDT THU SEP 5 2013
WITH HIGH PRESSURE OVER THE REGION...EXPECT VFR CONDITIONS AND LIGHT
WINDS THROUGH MOST OF TONIGHT. MID CLOUDS WILL BEGIN TO THICKEN
AFTER MIDNIGHT AT CMX...BUT ANY SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO HOLD OFF UNTIL FRIDAY AFTERNOON. CONFIDENCE IN THE
SHA/TSRA ARRIVAL TIME AND PROBABILITY WAS LOW SO NONE MENTIONED
THROUGH 18Z/FRI.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 410 PM EDT THU SEP 5 2013
EXPECT SW WINDS UP TO 20-25 KTS ON FRI UNDER SHARPENING PRES
GRADIENT AHEAD OF INCOMING LO PRES TROUGH. FOLLOWING THE PASSAGE OF
A COLD FRONT ON SAT...WINDS WILL VEER TO THE N-NE AND REMAIN UP TO
20 KTS INTO SUN IN ADVANCE OF HI PRES BUILDING TOWARD THE GREAT
LAKES. A RELATIVELY WEAK PRES GRADIENT AND/OR HI OVERWATER STABILITY
WILL THEN DOMINATE ON SUN INTO TUE...RESULTING IN WINDS UNDER 20 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KC
AVIATION...JLB
MARINE...KC
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1236 PM CDT Thu Sep 5 2013
.SHORT TERM...(Today through Saturday)
Issued at 410 AM CDT THU SEP 5 2013
At 8z water vapor imagery and RAP analysis continue to indicate a
strong 596 hpa H5 ridge over the interior mountain region of the
CONUS, with a deep trough over the Hudson Bay area. Between these
two features light northwest flow continues in the mid levels. At 8z
water vapor as well as IR imagery indicated an area of mid level
clouds rounding the northwest quadrant of the mid level ridge across
far eastern Nebraska and far western Iowa. Radar imagery indicates
that there are a few showers associated with this area of clouds.
These showers, with an isolated lightning strike or two are likely
associated with a very weak and subtle impulse rounding the mid
level ridge. Today`s forecast will depend on how many clouds this
subtle wave will form through the day. The current thought is that
these showers will likely not make it as far south as Interstate 70,
although a few light sprinkles or showers may affect the far
northern and western portions of Missouri and extreme NE Kansas. As
the trough moves through it looks as though it will bring with it
some mid level cloud cover, especially in the western half of the
forecast area. These mid level clouds could act to keep temperatures
a bit cooler than the going forecast suggested. Have gone with a dry
forecast for today, and dropped temperatures 1-3 degrees in the
western half of the CWA for day time highs. Even though perhaps
slightly cooler temps are expected day time highs will still make it
into the mid to upper 80s, but will continue to monitor the diurnal
trend and adjust based on how the cloud cover behaves.
For the rest of the mid range forecast expect dry conditions to
remain, as the mid level ridge continues to shunt any strong chance
for rain well north of the forecast area. With the steady flow of
southerly winds into the area as well as the mid level ridge keeping
the area clear of any significant cloud cover or rain expect a
steady warm up through the weekend, with daytime highs reaching the
lower 90s for Friday, and rising into the lower to mid 90s for
Saturday and Sunday. The only chance for rain in the forecast area
through the weekend will be a minimal chance for an isolated shower
or two across NC/NE Missouri Saturday night into Sunday morning.
.LONG TERM...(Sunday through Wednesday)
Issued at 410 AM CDT THU SEP 5 2013
Well above average temperatures will continue into the extended time
period however models are hinting at a potential pattern change
toward the end of the period. These well above above average
temperatures have been courtesy of an upper level ridge of high
pressure that has been dominating the regions weather. This will
also be the case at the onset of the extended period as the upper
level ridge axis will reside over the central Plains. Sunday an
upper level shortwave will be rounding this ridge and models
indicate that an overnight MCS will develop over Iowa and roll into
the eastern portion of the CWA Sunday morning. As such have added
slight chance POPs to the eastern CWA with slightly cooler
temperatures around 90 across the eastern CWA. Temperatures
elsewhere across the CWA will reach into the mid 90s.
Monday will be the warmest day in the extended time frame as the
upper level ridge axis moves directly overhead. Highs will reach
into the mid 90s CWA wide. However, Monday night an upper level
trough will move through the northern Plains into the Upper Midwest.
This will force a weak cold front towards the area however, it will
initially get hung up north of the CWA. It will also flatten the
upper level ridge across the area and force it into the southeastern
CONUS. This will make for a "cooler" Tuesday with highs in the low
to mid 90s.
Tuesday night a second upper level trough will dig into the northern
Plains. Models differ on the strength of the trough as the EC is
much stronger with it than the GFS or GEM. In either case, the
aforementioned cold front that was hung up north of the area will be
forced into the CWA Tuesday night. This will have a two-fold effect:
First, it will bring the next chance for showers and thunderstorms
to the area Tuesday night into Wednesday. Second, it will cool
temperatures into the mid to upper 80s.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1235 PM CDT THU SEP 5 2013
VFR conditions look to prevail at the terminals again overnight with
the possible exception of KSTJ. Wind will likely go calm overnight,
but expect to only have surface restriction in the River Valley near
the KSTJ terminal during the early morning hours.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
SHORT TERM...Leighton
LONG TERM...73
AVIATION...Cutter
AREA FORECAST DISCUSSION
NWS RALEIGH NC
130 PM EDT THU SEP 5 2013
.SYNOPSIS...
A DRY COLD FRONT WILL PUSH SOUTHWARD THROUGH THE REGION TONIGHT.
CANADIAN HIGH PRESSURE WILL BUILD SOUTH INTO THE AREA ON FRIDAY WITH
GRADUAL WEAKENING THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1015 AM THURSDAY...
A WEAK COLD FRONT IS HUNG UP OVER THE COASTAL PLAIN THIS
MORNING...WITH DEWPOINTS ALONG AND TO THE EAST OF THE FRONT STILL IN
THE UPPER 60S AND LOWER 70S. WHILE THIS BOUNDARY CONTINUES TO PUSH
SLOWLY TO THE SOUTHEAST...MODIFIED NAM AND RAP SOUNDINGS SUGGEST
1000 J/KG OF MLCAPE WILL LINGER ALONG THE EASTERN PERIPHERY OF THE
CWA...AND THIS IS SOMEWHAT EVIDENT ALREADY IN THE SPC MESOANALYSIS.
HOWEVER..LOW LEVEL CONVERGENCE IS WEAK ALONG THE SURFACE FRONT AND A
WEAK 850MB TROUGH NOTED IN UPPER AIR ANALYSIS. THE SEABREEZE LOOKS
TO BE THE ONLY ENHANCEMENT FOR LIFT...AND RAP/HRRR PROGS SHOW THE
SEABREEZE ONLY BARELY REACHING SAMPSON COUNTY BY LATE AFTERNOON.
THUS...WILL LEAVE THE FORECAST FREE OF POPS FOR TODAY. OTHERWISE..
SKIES WILL BE MOSTLY SUNNY EXCEPT FOR OVER PORTIONS OF THE SOUTHERN
PIEDMONT WHERE THIN HIGH CLOUDS CONTINUE TO DRIFT SOUTHEAST IN THE
NORTHWESTERLY FLOW ALOFT. HIGHS IN THE UPPER 80S TO AROUND 90.
ANOTHER COLD FRONT TO OUR NORTH WILL SURGE SOUTH THIS EVENING AND
CROSS THE AREA OVERNIGHT...THOUGH WITH LITTLE MOISTURE TO WORK WITH.
LOWS TONIGHT WILL BE IN THE LOWER 60S NORTH TO MID/UPPER 60S
SOUTH.
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 215 AM THURSDAY...
CANADIAN SURFACE HIGH PRESSURE WILL BUILD SOUTH DOWN THE
MID-ATLANTIC SEABOARD...BECOMING CENTERED OVER THE AREA
BY SATURDAY MORNING. ASSOCIATED NORTHEASTERLY LOW-LEVEL MARITIME
FLOW WILL RESULT IN SCATTERED PATCHES OF POST-FRONTAL STRATUS FRIDAY
MORNING...AND PERHAPS A FAIRLY HEALTHY BROKEN STRATOCUMULUS DECK
BY THE AFTERNOON. COOLER AND LESS HUMID WITH HIGHS IN THE UPPER 70S
TO NEAR 80 NORTH TO MID 80S SOUTH.
THE STRATOCUMULUS MARINE LAYER LAYER WILL LIKELY GET TRAPPED
UNDERNEATH THE MID-LEVEL SUBSIDENCE INVERSION FRIDAY
EVENING/NIGHT...RESULTING IN PARTLY TO CLOUDY SKIES. LOWS IN THE MID
TO UPPER 50S NORTH TO LOWER/MID 60S SOUTH.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 245 AM THURSDAY...
OVERALL THE LONG TERM PERIOD WILL BE CHARACTERIZED BY MOSTLY DRY
CONDITIONS AS THE MAIN STORM TRACK REMAINS WELL NORTH OF THE REGION.
THE WEATHER ACROSS CENTRAL NC WILL BE DOMINATED BY SEVERAL
REINFORCING SURFACE HIGHS AND NORTHWEST FLOW ALOFT AS A BROAD TROUGH
REMAINS SITUATED JUST OFF THE EAST COAST...BEFORE AN UPPER LEVEL
RIDGE BUILDS EAST THROUGH THE MIDDLE OF NEXT WEEK.
HIGH PRESSURE OVER THE AREA ON SATURDAY WILL WEAKEN AND BEGIN TO
SHIFT OFFSHORE LATE SATURDAY INTO EARLY SUNDAY...BUT WITH ONLY
MINIMAL MOISTURE RETURN...THE DRY CONDITIONS ARE EXPECTED TO PERSIST
THROUGH AT LEAST SUNDAY. THEN...ANOTHER FRONT IS PROGGED TO MOVE
ACROSS THE AREA ON LATE SUNDAY INTO MONDAY...WITH YET ANOTHER
RENEWED SURFACE HIGH RIDGING DOWN INTO THE REGION FOR EARLY NEXT
WEEK. AS THE FRONT CROSSES THE AREA ON MONDAY...THERE COULD BE SOME
ISOLATED ACTIVITY...ESPECIALLY ACROSS THE SOUTHERN TIER OF THE
FORECAST AREA...WHERE THE BEST MOISTURE CONTENT WILL RESIDE AND THE
TIMING OF THE FRONTAL PASSAGE WILL BE MOST FAVORABLE.
FOR THE REMAINDER OF THE WEEK...THE SURFACE HIGH WILL BE CENTERED
SLIGHTLY FURTHER TO THE NORTH THAN PREVIOUS ONES AND AS A
RESULT...MORE IN THE WAY OF EASTERLY FLOW IS EXPECTED AND THEREFORE
MOISTURE IS PROGGED TO GRADUALLY INCREASE THROUGH THE MIDDLE NEXT
WEEK. HOWEVER...THE EAST COAST TROUGH ALOFT IS FINALLY EXPECTED TO
BE REPLACED BY AN EASTWARD PROGRESSING UPPER LEVEL RIDGE BY THE
EARLY TO MIDDLE PART OF NEXT WEEK...WHICH MAY WORK AGAINST ANY
CONVECTIVE DEVELOPMENT. WITH ALL OF THIS IN MIND...WITH MAINTAIN A
DRY FORECAST THROUGH THE REMAINDER OF THE LONG TERM PERIOD...BUT
THAT IS NOT TO SAY THERE COULD BE SOME ISOLATED DIURNAL TYPE
ACTIVITY. TEMPS WILL BE TIED TO THE MULTIPLE FRONTAL PASSAGES DURING
THE PERIOD...BUT WILL GENERALLY BE NEAR TO SLIGHTLY ABOVE NORMAL
THROUGHOUT THE ENTIRE PERIOD...EXCEPT FOR SATURDAY WHEN SLIGHTLY
BELOW NORMAL TEMPS ARE EXPECTED.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 130 PM THURSDAY...
VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. MOISTURE ALONG
AND EAST OF A STALLED FRONT OVER THE COASTAL PLAIN IS LEADING TO A
SCATTERED CU FIELD WITH BASES AT 5K FT OR HIGHER TO THE SOUTH AND
EAST KRDU. THIS EVENING...A DRY COLD FRONT WILL PUSH SOUTH THROUGH
THE AREA...BETWEEN ROUGHLY 03-07Z...WITH WINDS TURNING TO
NORTHEASTERLY AND POSSIBLY GUSTING TO 15-20KT IMMEDIATELY BEHIND THE
FRONT. WINDS WILL REMAIN OUT OF THE NORTHEAST ON FRIDAY.
OUTLOOK...
OUTSIDE OF POCKETS OF SUB-VFR VSBYS IN THE EARLY MORNING HOURS...VFR
CONDITIONS ARE EXPECTED THROUGH THE WEEKEND. A COLD FRONT WILL
PUSH SOUTH INTO THE AREA BY MONDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CBL
NEAR TERM...CBL/SMITH
SHORT TERM...CBL
LONG TERM...KRR
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
134 PM CDT THU SEP 5 2013
.UPDATE...
ISSUED AT 1247 PM CDT THU SEP 5 2013
EARLY AFTERNOON UPDATE FOR MIDDAY TEMPERATURE AND SKY COVER
TRENDS...OTHERWISE CURRENT FORECAST IS ON TRACK.
THE MAIN FORECAST ISSUE FOR TONIGHT THROUGH FRIDAY NIGHT IS THE
POTENTIAL FOR ANOTHER ROUND OF THUNDERSTORM ACTIVITY AND THE
ASSOCIATED THREAT FOR ISOLATED SEVERE WEATHER. IN THE NEAR
TERM...OPTED FOR A DRY FORECAST TONIGHT WITH LITTLE IN THE WAY OF
FORCING EXPECTED. ON FRIDAY...INSTABILITY AND MOISTURE WILL BE ON
THE INCREASE. A SURFACE TROUGH IS EXPECTED TO STRETCH ACROSS
WESTERN ND AND SYNOPTIC SCALE FORCING SHOULD BE ON THE INCREASE
DURING THE LATE AFTERNOON/EVENING HOURS AS SHORT WAVE ENERGY RIDES
UP THE UPPER RIDGE. THE ENTIRE FORECAST AREA IS IN THE 5 PERCENT
RISK AREA FOR ISOLATED SEVERE STORMS. HAVE SPEEDED UP THE TIMING
OF THE AFTERNOON POPS IN A NOD TO THE FASTER SOLUTIONS...AND MODEL
CONSENSUS SUPPORTS AN INCREASE IN POPS FOR FRIDAY
NIGHT...ESPECIALLY WEST. A LIMITING FACTOR FOR SEVERE WEATHER WILL
BE RELATIVELY MODEST DEEP LAYER SHEAR...BUT UNDOUBTEDLY THERE WILL
BE AT LEAST A FEW STORMS TO MONITOR.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 349 AM CDT THU SEP 5 2013
THE MAIN FORECAST HIGHLIGHT FOR THE SHORT TERM PERIOD IS
PRECIPITATION CHANCES.
RADAR IMAGERY AT 08Z SHOWS ONGOING SHOWER ACTIVITY ACROSS CENTRAL
NORTH DAKOTA...WITH MORE WIDESPREAD SHOWER/THUNDERSTORM ACTIVITY
OVER THE BLACK HILLS REGION OF SOUTH DAKOTA...ASSOCIATED WITH A
WEAK UPPER LEVEL IMPULSE MOVING OVER THE AREA THIS MORNING. THERE
IS A BIT OF UNCERTAINTY IN THE PRECIP FORECAST THROUGH EARLY
AFTERNOON...AS THE 00Z GFS/ECWMF ARE MORE ROBUST IN AREAL EXTENT
OF SHOWER/THUNDERSTORM COVERAGE VERSUS THE 00Z NAM/GEM AND LATEST
RUNS OF THE HRRR AND RAP...WHICH ARE MORE SPOTTY WITH COVERAGE.
CONSEQUENTLY...HAVE USED A BLEND OF GUIDANCE...LIMITING POPS TO
SLIGHT CHANCE. LIGHTNING STRIKES HAVE BEEN FAR AND FEW BETWEEN
WITH ONGOING SHOWERS...SO HAVE REMOVED THE MENTION OF THUNDER IN
WX GRIDS FOR ALL EXCEPT ACROSS THE SOUTHWEST AND FAR WEST WHERE
CAPE MAY BE MORE PLENTIFUL. IN ADDITION...HAVE INCLUDED THE
MENTION OF SPRINKLES THROUGH LATE MORNING TO REFLECT ONGOING
ACTIVITY. SHOWERS/THUNDERSTORMS SHOULD COME TO AN END BY 18Z ONCE
THE WEAK IMPULSE MOVES INTO WESTERN MINNESOTA.
WARMER TEMPERATURES ARE EXPECTED ACROSS THE AREA TODAY AS A RIDGE
AND WARMER H850 TEMPERATURES MOVE OVERHEAD. THIS WILL RESULT IN
AFTERNOON TEMPERATURES CLIMBING INTO THE UPPER 80S AND LOWER
90S...AND OVERNIGHT TEMPERATURES COOLING ONLY INTO THE 60S.
DEWPOINTS WILL ALSO BE ON THE RISE...THOUGH HEAT INDEX VALUES
SHOULD REMAIN IN THE 90S.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 349 AM CDT THU SEP 5 2013
THE MAIN FORECAST CHALLENGE FOR THE EXTENDED WILL BE THE AREAL
EXTENT AND COVERAGE OF PRECIPITATION CHANCES THIS WEEKEND. GIVEN THE
MODEL TO MODEL AND RUN TO RUN INCONSISTENCIES...CONTINUED TO FOLLOW
A BLENDED APPROACH FOR THE EXTENDED PERIOD FORECAST.
EARLY IN THE PERIOD...THE MEDIUM RANGE MODELS CONTINUE TO STRUGGLE
WITH THE EXACT TIMING AND LOCATION OF SHORTWAVES EJECTING FROM AN
UPPER LOW PROGGED TO REMAIN OVER THE PACIFIC NORTHWEST THROUGH
SATURDAY. FOR NOW CONTINUED TO FORECAST AN INCREASING POP TREND WEST
AND CENTRAL THROUGH SATURDAY AND KEPT THE EAST (TURTLE MOUNTAIN
SOUTH TO THE JAMES RIVER VALLEY) DRY THROUGH EARLY SUNDAY MORNING.
AS THE UPPER LOW FINALLY PUSHES INTO MONTANA...THUNDERSTORM CHANCES
SHOULD INCREASE ACROSS THE ENTIRE STATE SUNDAY AND SUNDAY NIGHT.
GIVEN THE EXPECTED POSITION OF THE LOW AND ATTENDANT DEEP LAYER
SHEAR/INSTABILITY PARAMETERS...SEVERE WEATHER COULD BE POSSIBLE
SUNDAY AFTERNOON/EVENING. WILL CONTINUE TO HIGHLIGHT THIS
POSSIBILITY IN THE HWO.
THE LATEST GFS/ECMWF/GEM ALL DIFFER WITH RESPECT TO THE TIMING OF
THE LOW PIVOTING ACROSS NORTH DAKOTA AND SUBSEQUENTLY DRY CONDITIONS
FILTERING INTO THE REGION. THE LATEST ECMWF IS NOW MORE PROGRESSIVE
WITH THIS FEATURE AND PIVOTS IT THROUGH THE REGION MONDAY. THE GFS
IS ABOUT 12 HOURS SLOWER WHEREAS THE GEM IS AN AVERAGE OF THE TWO.
FOR NOW KEPT POPS IN AREAWIDE MONDAY AND FORECAST A DRYING TREND
TUESDAY THROUGH WEDNESDAY AS HIGH PRESSURE BUILDS OVER THE ROCKIES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1017 AM CDT THU SEP 5 2013
EXPECT VFR CONDITIONS AT ALL TAF SITES THROUGH THE PERIOD WITH A
LIGHT SOUTHEAST WIND UNDER 10 KTS.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE/AVIATION...RP KINNEY
SHORT TERM...LTH
LONG TERM...TM
AREA FORECAST DISCUSSION...UPDATE
NWS PORTLAND OR
211 PM PDT THU SEP 5 2013
.SYNOPSIS...AN UPPER LEVEL LOW WILL CONTINUE THE THREAT FOR SHOWERS
AND THUNDERSTORMS TONIGHT. LOCALIZED HEAVY RAINFALL IS EXPECTED
THROUGH FRIDAY MORNING AS THE LOW MOVES OVER THE AREA.SHOWERS WILL
DECREASE FRIDAY EVENING TO THE SOUTH BUT LINGER ACROSS THE NORTH
THROUGH SATURDAY MORNING. HIGH PRESSURE WILL BUILD BEHIND
THE LOW WITH DRIER WEATHER EXPECTED BY SUNDAY. WARMER WEATHER IS
EXPECTED EARLY NEXT WEEK.
&&
.SHORT TERM....CONVECTIVE BANDS CIRCULATING AROUND AN UPPER LOW ARE
MOVING OVER LANE COUNTY EARLY THIS AFTERNOON...WITH THUNDERSTORMS
PRODUCING ABUNDANT LIGHTNING AND HEAVY RAIN. WE HAVE RECEIVED REPORTS
OF POWER OUTAGES...LOCALIZED PONDING OF WATER ON ROADWAYS WITH THESE
STORMS SO FAR...AS WELL AS ONE REPORT OF SMALL HAIL.
THE LOW CENTER IS CURRENTLY AROUND 60 MILES OFF OF THE SOUTHERN
OREGON COAST AND WILL BE PUSHING INLAND ACROSS NW OREGON THIS
AFTERNOON AND EVENING. AS IT MOVES INLAND SHOWERS AND THUNDERSTORMS
WILL SHIFT NORTHWARD. THE HRRR MODELED COMPOSITE REFLECTIVITIES HAS
BEEN DOING A GREAT JOB OF FORECASTING THE LOCATION OF RAIN THIS
MORNING AND SHOWS THE MAIN RAIN BAND WILL BE CENTERED OVER THE CENTRAL
WILLAMETTE VALLEY BY 4PM THIS EVENING AND CENTERED OVER THE PORTLAND
METRO AREA BY 7 PM. THIS BAND SEEMS TO THIN AND FALL APART AS IT
MOVES NORTH...AND EXPECT THUNDERSTORM COVERAGE TO LESSEN.
HOWEVER...SHOWERS WRAPPING AROUND THE LOW WILL EXPAND OVER THE AREA
LATER TONIGHT AS THE LOW MOVES FURTHER TO THE NE...AND LOCALIZED
HEAVY RAIN WILL CONTINUE THROUGH THE NIGHT.
WRAP AROUND SHOWERS WILL CONTINUE FRIDAY AS THE LOW SHIFTS NE OF THE
AREA...MAINLY NORTH OF SALEM. THE MODELS HAVE SLOWED THE TIMING OF
THE RIDGE BUILDING OVER THE AREA AND DELAYING DRYING OVER THE AREA.
SOUTHERN AREAS WILL DRY SATURDAY...BUT SHOWERS MAY LINGER ACROSS THE
SOUTHERN WASHINGTON THROUGH SATURDAY MORNING.
.LONG TERM...SUNDAY THROUGH WEDNESDAY NIGHT...A STRONG LATE SEASON
RIDGE WILL BUILD INTO THE PAC NW SUNDAY THROUGH TUESDAY HOLD THROUGH
LATE NEXT WEEK. THE LATEST MEDIUM RANGE MODELS INDICATE THAT 500 MB
HEIGHTS WILL NEAR 590 DM OVER THE REGION...WITH 850 MB TEMPS NEAR 20C
BY TUE OR WED. MEANWHILE A THERMAL INDUCED SURFACE TROUGH IS PROGGED
TO BUILD ALONG THE COAST...BRINGING AN EASTERLY COMPONENT TO THE LOW
LEVEL FLOW. THUS...IT IS LOOKING MORE AND MORE LIKELY THAT WE WILL
SEE A SIGNIFICANT WARM UP NEXT WEEK. THE OFFSHORE FLOW PATTERN WOULD
ALSO ALLOW THE COAST TO SEE SOME OF THEIR WARMEST TEMPERATURES OF THE
SEASON.
&&
.AVIATION...CONVECTIVE ACTIVITY HAS PICKED UP THIS AFTERNOON AND
WILL CONTINUE TO BRING HEAVY RAIN...LIGHTNING...AND OCCASIONAL
GUSTY WINDS TO TAF SITES AS LOW PRES PUSHES INLAND. MUCH OF THE
ACTIVITY HAS MAINLY BEEN SOUTH OF SALEM...BUT SHOWERS WILL
CONTINUE TO LIFT NORTH OVERNIGHT. EXPECT MOSTLY MVFR CIGS THROUGH
TONIGHT.
KPDX AND APPROACHES...EXPECT SHOWERS TO INCREASE THROUGH 00Z THIS
AFTERNOON AND CONTINUE INTO FRIDAY MORNING. MVFR CIGS WILL
CONTINUE...WITH VIS DROPPING TO MVFR IN HEAVIER SHOWERS ESPECIALLY
OVERNIGHT. /27
&&
.MARINE...AN UPPER LOW WILL MOVE SOUTH OF THE COASTAL WATERS THIS
AFTERNOON AND MOVE ONSHORE TONIGHT AND EARLY FRIDAY. OVERALL
BENIGN WIND AND SEA CONDITIONS WILL PERSIST THROUGH EARLY
SATURDAY AS THE SYSTEM PUSHES FURTHER INLAND. HIGH PRESSURE OVER
THE NORTHEAST PACIFIC OCEAN AND THERMAL LOW PRESSURE OVER NORTHERN
CALIFORNIA WILL STRENGTHEN OVER THE WEEKEND...RESULTING IN SOME
LATE AFTERNOON AND EVENING GUSTY 25 KT WINDS WITH SEAS RUNNING 4
TO 6 FT. SEAS LOOK TO REMAIN UNDER 10 FT NEXT WEEK. /27/NEUMAN
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WA...NONE.
PZ...NONE.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1226 PM CDT THU SEP 5 2013
.DISCUSSION...
See aviation discussion below...
&&
.AVIATION...
Isolated showers will develop across the southern half of West
Central Texas this afternoon. I have included a VCTS mention at
KJCT, KSOA, and KBBD, ending shortly after sunrise. For now I have
left a mention of thunder out of the KABI and KSJT TAF, but I will
continue to monitor. Otherwise, expect light winds and VFR
conditions through the next 24 hours.
&&
.PREV DISCUSSION... /ISSUED 1144 AM CDT THU SEP 5 2013/
UPDATE...
To expand POPS north...
DISCUSSION...
I sent out a quick update to expand isolated POPS north into the
Heartland and Concho Valley this afternoon. A cumulus field is
beginning to develop across the region, with low level moisture
higher than originally anticipated. High resolution models including
the Texas Tech WRF and HRRR are indicating isolated showers and
thunderstorms developing this afternoon across the southern half of
West Central Texas. For this reason, I have expanded POPS north as
previously mentioned. I have also tweaked temperatures down a degree
or two across much of the region, given the expected higher
dewpoints and increased cloud cover...with the hottest temperatures
across the Big Country. Otherwise, no other changes are needed at
this time.
PREV DISCUSSION... /ISSUED 630 AM CDT THU SEP 5 2013/
DISCUSSION...
Please see aviation section below for discussion.
AVIATION...
Look for beautiful flight weather to continue across West Central
Texas for the next 24 hours. High pressure will continue to
dominate; thus, I`m expecting light surface winds around 6 knots or
less for another 24 hours.
Huber
PREV DISCUSSION... /ISSUED 427 AM CDT THU SEP 5 2013/
SHORT TERM...
(today and tonight)
Thunderstorms may develop across our Northern Edwards Plateau and
Northwest Hill Country counties this afternoon and evening.
Otherwise, expect hot and dry conditions to continue for at least
another 24 hours. High pressure will remain dominate over the
southern Plains for the next 24 hours. Our southern counties will
remain just outside the major influence of this high and its
associated subsidence. Thus, I`ve decided to continue slight chance
POPs across our southern counties, as this area has been an area of
convective development during the last couple afternoons. As for
temperatures, I`m going with highs today just above the adjusted MEX
model data, simply because that`s been the trend the last couple
days, with highs just above model guidance. Lows tonight close to
persistence look reasonable.
Huber
LONG TERM...
(Friday through Wednesday)
The main forecast items of interest in the long term include
possible low rain chances in the southern part of our forecast
area, and a slow decrease in maximum temperatures over the course
of several days.
Friday through the weekend, the upper high will slowly weaken as it
shifts east across Kansas. Our area will continue to be on the
southern periphery of this upper high. The 00Z GFS and NAM are less
favorable with QPF across our southern counties on Friday. However,
given what has occurred during the past couple of days, plan to
continue with low POPs in our southern counties for isolated
afternoon and evening showers/thunderstorms across that area, where
sufficient moisture should remain.
On the fence whether to carry an isolated mention for afternoon/
early evening showers and thunderstorms this weekend across roughly
the southern third of West Central Texas. The 00Z models have
trended down a bit with mid-level moisture, and mid/upper forcing
will be weak. Planning to leave out the mention for now.
Early next week the upper level high is progged to shift into the
southeastern part of the country, with an upper trough moving east
across the northern Plains and into southwestern Ontario Province
in Canada. Over our area, the flow aloft will transition to
southeasterly through a deeper layer, but with the latest model
indications this may be short-lived. The 00Z GFS and ECMWF show
more ridging aloft over the northern half of Texas by the middle of
next week. With uncertainty in the specifics of how the upper level
pattern will evolve next week, holding off with any mentionable
rain chance in our counties at this time.
With a slight decrease in 850 mb temperatures across our area along
with some increase in cloud cover, maximum temperatures are expected
to decrease by a few degrees, over a period of several days.
19
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 73 96 71 96 71 / 5 5 10 5 5
San Angelo 72 96 69 94 71 / 10 10 10 10 5
Junction 72 95 70 94 71 / 20 10 10 10 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
Daniels
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1144 AM CDT THU SEP 5 2013
.UPDATE...
To expand POPS north...
&&
.DISCUSSION...
I sent out a quick update to expand isolated POPS north into the
Heartland and Concho Valley this afternoon. A cumulus field is
beginning to develop across the region, with low level moisture
higher than originally anticipated. High resolution models including
the Texas Tech WRF and HRRR are indicating isolated showers and
thunderstorms developing this afternoon across the southern half of
West Central Texas. For this reason, I have expanded POPS north as
previously mentioned. I have also tweaked temperatures down a degree
or two across much of the region, given the expected higher
dewpoints and increased cloud cover...with the hottest temperatures
across the Big Country. Otherwise, no other changes are needed at
this time.
&&
.PREV DISCUSSION... /ISSUED 630 AM CDT THU SEP 5 2013/
DISCUSSION...
Please see aviation section below for discussion.
AVIATION...
Look for beautiful flight weather to continue across West Central
Texas for the next 24 hours. High pressure will continue to
dominate; thus, I`m expecting light surface winds around 6 knots or
less for another 24 hours.
Huber
PREV DISCUSSION... /ISSUED 427 AM CDT THU SEP 5 2013/
SHORT TERM...
(today and tonight)
Thunderstorms may develop across our Northern Edwards Plateau and
Northwest Hill Country counties this afternoon and evening.
Otherwise, expect hot and dry conditions to continue for at least
another 24 hours. High pressure will remain dominate over the
southern Plains for the next 24 hours. Our southern counties will
remain just outside the major influence of this high and its
associated subsidence. Thus, I`ve decided to continue slight chance
POPs across our southern counties, as this area has been an area of
convective development during the last couple afternoons. As for
temperatures, I`m going with highs today just above the adjusted MEX
model data, simply because that`s been the trend the last couple
days, with highs just above model guidance. Lows tonight close to
persistence look reasonable.
Huber
LONG TERM...
(Friday through Wednesday)
The main forecast items of interest in the long term include
possible low rain chances in the southern part of our forecast
area, and a slow decrease in maximum temperatures over the course
of several days.
Friday through the weekend, the upper high will slowly weaken as it
shifts east across Kansas. Our area will continue to be on the
southern periphery of this upper high. The 00Z GFS and NAM are less
favorable with QPF across our southern counties on Friday. However,
given what has occurred during the past couple of days, plan to
continue with low POPs in our southern counties for isolated
afternoon and evening showers/thunderstorms across that area, where
sufficient moisture should remain.
On the fence whether to carry an isolated mention for afternoon/
early evening showers and thunderstorms this weekend across roughly
the southern third of West Central Texas. The 00Z models have
trended down a bit with mid-level moisture, and mid/upper forcing
will be weak. Planning to leave out the mention for now.
Early next week the upper level high is progged to shift into the
southeastern part of the country, with an upper trough moving east
across the northern Plains and into southwestern Ontario Province
in Canada. Over our area, the flow aloft will transition to
southeasterly through a deeper layer, but with the latest model
indications this may be short-lived. The 00Z GFS and ECMWF show
more ridging aloft over the northern half of Texas by the middle of
next week. With uncertainty in the specifics of how the upper level
pattern will evolve next week, holding off with any mentionable
rain chance in our counties at this time.
With a slight decrease in 850 mb temperatures across our area along
with some increase in cloud cover, maximum temperatures are expected
to decrease by a few degrees, over a period of several days.
19
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 98 73 96 71 96 / 10 5 5 10 5
San Angelo 98 72 96 69 94 / 10 10 10 10 10
Junction 95 72 95 70 94 / 20 20 10 10 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
Daniels
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
332 PM CDT THU SEP 5 2013
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 332 PM CDT THU SEP 5 2013
MAIN FORECAST CONCERNS ARE ON HIGH TEMPERATURES ON FRIDAY AND SHOWER
AND THUNDERSTORM CHANCES FRIDAY NIGHT INTO SATURDAY.
LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED HIGH
PRESSURE CENTERED OVER EASTERN COLORADO WITH A RIDGE EXTENDING NORTH
THROUGH THE DAKOTAS INTO SOUTHERN SASKATCHEWAN. AN UPPER LOW WAS
NOTED JUST OFF OF THE PACIFIC NORTHWEST...WHILE A BROAD TROUGH WAS
IN PLACE OVER EASTERN CANADA. NORTHWEST FLOW ALOFT WAS NOTED OVER
THE UPPER MISSISSIPPI RIVER VALLEY. SEVERAL WEAK EMBEDDED SHORTWAVES
WERE NOTED OVER THE DAKOTAS. THE PRIMARY WAVE WAS LOCATED OVER
WESTERN NORTH DAKOTA...HEADED SOUTHEAST. HIGH PRESSURE WAS
CENTERED OVER THE WESTERN GREAT LAKES WHILE A STATIONARY BOUNDARY
WAS LOCATED OVER THE EASTERN DAKOTAS AND WAS STRETCHING SOUTHEAST
THROUGH CENTRAL IOWA INTO SOUTHERN ILLINOIS.
THE HIGH WILL SLIDE EAST OF THE REGION TONIGHT AS THE SHORTWAVE
APPROACHES FORM THE DAKOTAS/WESTERN MINNESOTA. SOUTHERLY FLOW WILL
INCREASE ON THE BACK SIDE OF THE HIGH USHERING IN A WARMER AND
SLIGHTLY MORE HUMID AIRMASS. 850 MB MOISTURE TRANSPORT INCREASES
ACROSS WESTERN MINNESOTA AND WESTERN IOWA...WHICH SHOULD RESULT IN
THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS. THE MOISTURE
TRANSPORT ATTEMPTS TO EDGE INTO NORTHEAST IOWA AND SOUTHEAST
MINNESOTA LATE TONIGHT INTO EARLY FRIDAY MORNING WHICH MAY SUPPORT
AN ISOLATED SHOWER OR THUNDERSTORM. FORECAST SOUNDINGS ARE RATHER
DRY AND WITHOUT A STRONG FORCING MECHANISM HAVE DECIDED TO
MAINTAIN A DRY FORECAST FOR THE OVERNIGHT HOURS. CANNOT RULE OUT
SOME PATCHY VERY SHALLOW FOG IN COULEE AREAS TONIGHT BUT THAT
SHOULD BE THE EXTENT OF IT. THE GRADIENT TIGHTENS OVER THE REGION
TONIGHT AND WINDS FROM 500 TO 1KFT INCREASE TO 16 TO 25KTS...WHICH
SHOULD PROMOTE ENOUGH MIXING TO PREVENT DENSE FOG FORMATION.
FRIDAY WILL BE A WARM AND BREEZY DAY ACROSS THE REGION AHEAD OF A
WEAK COLD FRONT APPROACHING FROM THE NORTHERN PLAINS. PLAN ON
HIGHS RANGING FROM THE LOWER 80S OVER FAR NORTHERN WISCONSIN TO
THE UPPER 80S TO AROUND 90 OVER NORTHEAST IOWA.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 332 PM CDT THU SEP 5 2013
THE FRONT WILL MOVE THROUGH THE FORECAST AREA FRIDAY NIGHT INTO
SATURDAY MORNING BRINGING CHANCES FOR SHOWERS AND STORMS WITH IT.
THERE IS ELEVATED CAPE OVER THE REGION WITH VERY LITTLE TO NO CAP
IN PLACE. LIFTING FROM 800 MB YIELDS NEARLY 700 J/KG CAPE.
ALSO...850 MB MOISTURE TRANSPORT FOCUSES INTO THE AREA SO THERE
SHOULD BE ENOUGH SUPPORT FOR AT LEAST ISOLATED TO SCATTERED
THUNDERSTORMS. THE BEST CHANCES FOR THESE APPEARS TO BE ALONG AND
EAST OF THE MISSISSIPPI RIVER. HIGH PRESSURE GRADUALLY BUILDS INTO
THE AREA LATE SATURDAY AFTERNOON THROUGH SUNDAY. PRECIPITATION
CHANCES WILL SHIFT SOUTHEAST OF THE FORECAST AREA BY LATE SATURDAY
AFTERNOON AS THE HIGHS BUILDS IN. THE HIGH WILL BE CENTERED OVER
LAKE SUPERIOR ON SUNDAY PROVIDING DRY EAST/NORTHEAST FLOW. HAVE
LOWERED DEW POINTS SIGNIFICANTLY ALONG AND NORTHEAST OF THE
INTERSTATE 94 CORRIDOR WHERE DEEP MIXING WILL YIELD AFTERNOON
RELATIVE HUMIDITY VALUES IN THE MID 30S. THE HIGH WILL SLIDE EAST
OF THE REGION SUNDAY NIGHT INTO MONDAY AS A VIGOROUS TROUGH RACES
ACROSS NORTH DAKOTA AND NORTHERN MINNESOTA. VERY WARM IS ADVECTS
NORTHWARD AHEAD OF THIS FEATURE INTO THE FORECAST AREA WITH 925 MB
TEMPERATURES WARMING INTO THE UPPER 20S TO AROUND 30. DECIDED TO
WARM HIGH TEMPERATURES ON MONDAY INTO THE UPPER 80S TO LOWER
90S...CLOSER TO WHAT THE ECMWF IS ADVERTISING. THERE IS THE
POTENTIAL FOR SHOWERS AND STORMS ALONG AND NORTH OF INTERSTATE 90
ON MONDAY SO TEMPERATURES MAY NOT GET THAT WARM ACROSS THESE
AREAS. ZONAL FLOW LOOKS TO SET UP OVER THE REGION ON TUESDAY INTO
TUESDAY NIGHT WITH EMBEDDED SHORTWAVES POSSIBLY GENERATING SOME
SHOWERS AND STORMS OVER THE FORECAST AREA. THE ECMWF IF
ADVERTISING BETTER CHANCES FOR PRECIPITATION ON WEDNESDAY AS A
TROUGH DIVES SOUTH OUT OF CANADA. THE GFS IS NOT NEARLY AS
AGGRESSIVE WITH THIS FEATURE AND BRINGS THE BULK OF THE
PRECIPITATION THROUGH TUESDAY INTO TUESDAY NIGHT WITH THE PASSAGE
OF A COLD FRONT. CONSIDERABLE UNCERTAINTY IN THE FORECAST BEYOND
MONDAY SO CHOSE TO LEAN TOWARD A MODEL CONSENSUS BLEND.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1207 PM CDT THU SEP 5 2013
THE MAIN PROBLEM CONCERNS THE STRATUS DECK AN HOW FAR WEST IT WILL
PROGRESS AND WHEN OR IF IT WILL DISSIPATE. THE 05.14Z RAP SUGGESTS
THIS MOISTURE FIELD WILL MIX OUT THIS AFTERNOON ALLOWING THE
CLOUDS TO BREAK UP AND THAT THIS WILL HAPPEN BEFORE THE CLOUDS
MOVE INTO KRST. THE 05.12Z NAM HANGS ON TO THE MOISTURE FIELD
THROUGH THE ENTIRE PERIOD...SUGGESTING THE CLOUDS WILL PERSIST
INTO TONIGHT BEFORE GETTING LIFTED NORTH OF THE AREA ON THE
BACKSIDE OF THE RIDGE AXIS. LOOKING AT THE LAST FEW SATELLITE
IMAGES...THE AREA OF CLOUDS HAS ESSENTIALLY STOPPED ITS WESTWARD
ADVANCE AND NOW APPEARS TO BE SHRINKING ON THE EAST SIDE AS WELL.
THUS WILL FOLLOW THE RAP TRENDS AND NOT BRING THE CLOUDS INTO
KRST AND SHOW THEM SCATTERING OUT AT KLSE BY MID AFTERNOON. ONCE
THE CLOUDS ARE OUT OF THE WAY...THE HIGH WILL CONTINUE TO SLIDE
OFF TO THE EAST THROUGH THE REMAINDER OF THE PERIOD. THIS WILL
KEEP ENOUGH OF A GRADIENT THROUGH THE NIGHT TO HAVE SOUTHEAST
WINDS BETWEEN 5 AND 10 KNOTS. EXPECT THAT THIS WILL PRECLUDE THE
FORMATION OF ANY VALLEY FOG...BUT CANNOT TOTALLY RULE OUT A LITTLE
BIT OF MVFR FOG FOR A SHORT WHILE LATE TONIGHT INTO EARLY FRIDAY
MORNING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1207 PM CDT THU SEP 5 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 346 AM CDT THU SEP 5 2013
CURRENT WATER VAPOR COMBINED WITH RAP 500MB ANALYSIS SHOWS A HIGHLY
AMPLIFIED RIDGE IN PLACE JUST EAST OF THE COLORADO/NORTHERN/CANADIAN
ROCKIES WITH OUR AREA IN NORTHWEST FLOW ALOFT. AT THE SURFACE...A
BROAD AREA OF HIGH PRESSURE EXTENDED SOUTHWARD OUT OF ONTARIO CANADA
THROUGH THE UPPER MISSISSIPPI RIVER VALLEY REGION...INTO THE MID AND
SOUTHERN MISSISSIPPI RIVER REGION. EAST/NORTHEAST SURFACE FLOW OFF
LAKE MICHIGAN WAS COMBINING WITH A RATHER HUMID LOWER BOUNDARY LAYER
TO PRODUCE AN EXPANDING STRATUS FIELD ACROSS SOUTHEAST WI/SOUTH
CENTRAL WI. THIS STRATUS MAY PROVE TO BE PROBLEMATIC TODAY ACROSS
THE SOUTHEAST PORTION OF THE FORECAST AREA. OTHERWISE...TEMPERATURES
ACROSS THE AREA EARLY THIS MORNING RANGED FROM THE 40S ACROSS
NORTHERN WI...TO THE MIDDLE AND UPPER 60S ALONG AND SOUTH OF THE
I-94 CORRIDOR.
FOR TODAY...WILL BE WATCHING THIS AFOREMENTIONED STRATUS CLOSELY.
RAP SOUNDINGS SHOW THIS CLOUD THINNING AS THE MORNING PROGRESSES
FROM NORTHEAST TO SOUTHWEST AS HIGH PRESSURE BUILDS OVER THE GREAT
LAKES AND DRIER AIR GETS ENTRAINED INTO THE BOUNDARY LAYER. THE NAM
AND RAP ARE HINTING AT SOME -SHRA ALONG AND WEST OF TE MISSISSIPPI
RIVER THIS AFTERNOON IN DAYTIME HEATING. HOWEVER...THERE IS NO
FORCING MECHANISM TO TRIGGER THESE SHOWERS. WILL KEEP DRY FOR NOW
BUT WARRANTS WATCHING. WITH LIGHT EASTERLY WINDS...LOOK FOR HIGH
TEMPERATURES TODAY IN THE MIDDLE 70S TO THE LOWER 80S.
ATTENTION THEN TURNS TO NORTHWEST FLOW ALOFT TONIGHT WITH AN
EMBEDDED/WEAKENING SHORTWAVE TROUGH HEADING SOUTHEAST THROUGH THE
NORTHERN PLAINS INTO MN. NAM SHOWING AN INCREASING CORRIDOR OF
850-700MB ISENTROPIC LIFT AND MOISTURE TRANSPORT AHEAD OF THIS WAVE
ACROSS THE PLAINS INTO NORTHWEST MN. PLAN ON SOME INCREASE IN
MID-LEVEL CLOUDS/ACCAS ACROSS PORTIONS OF SOUTHEAST MN INTO
NORTHWEST WI ON THE EASTERN FRINGES OF THIS FORCING. ANY SHRA
ACTIVITY IS EXPECTED TO STAY NORTHWEST OF THE AREA TOWARD THE BETTER
MOISTURE TRANSPORT. ANOTHER MITIGATING FACTOR IN SHOWER CHANCES
ACROSS NORTHWEST IS THE VERY-HIGH BASED NATURE OF THE CLOUDS AND DRY
LOWER LEVELS FOR EVAPORATION OF SHOWERS FROM THESE CLOUDS...WITH
JUST VIRGA EXPECTED. BASED ON THIS SIGNAL...WENT WITH A DRY FORECAST
OVERNIGHT. OTHERWISE...SOUTHERLY AIRFLOW AND INCREASING DEW POINTS
SHOULD KEEP OVERNIGHT LOWS UP IN THE 50S TO LOWER 60S.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 346 AM CDT THU SEP 5 2013
ON FRIDAY...WILL BE WATCHING A SURFACE COLD FRONT PUSHING SOUTHEAST
OUT OF CANADA INTO NORTHERN WI THROUGH CENTRAL MN BY LATE IN THE
AFTERNOON. CORRIDOR OF BEST 850-700MB MOISTURE TRANSPORT AND
ISENTROPIC LIFT STAYS NORTH OF THE AREA WITH JUST SOME INCREASE IN
MID/HIGH CLOUDS EXPECTED ACROSS OUR AREA. OF NOTE WILL BE INCREASING
SOUTHWEST WINDS AND WARM AIR ADVECTION INTO OUR AREA WITH 925MB
TEMPERATURE INCREASING INTO THE 25-28C BY AFTERNOON. THIS SHOULD
YIELD HIGH TEMPERATURES IN THE MID-UPPER 80S...WITH A COUPLE
LOCATIONS FLIRTING WITH THE 90 DEGREE MARK.
FOR FRIDAY NIGHT THROUGH SATURDAY...LOOK FOR THE COLD FRONT TO SINK
SLOWLY SOUTHEAST ACROSS THE AREA. CONTINUED 850-700MB MOISTURE
TRANSPORT/ISENTROPIC LIFT AND WEAK CONVERGENCE ALONG THIS FRONTAL
BOUNDARY SHOULD BE SUFFICIENT FOR ISOLATED-SCATTERED
SHOWER/THUNDERSTORMS. OF NOTE THOUGH IS A FAIRLY STRONG CAP ON
SATURDAY INDICATED BY THE NAM SOUNDING WHICH MAY LIMIT CONVECTION OR
KEEP IT VERY ELEVATED AND SPARSE IN NATURE. EVEN WITH CLOUDS...
LOOKING FOR HIGHS IN THE 80S. LINGERING SHOWER/THUNDERSTORM CHANCES
WILL BE SEEN SATURDAY NIGHT MAINLY SOUTH OF I-90 AS THE FRONT EXITS
THE AREA.
SUNDAY LOOKS DRY AND SLIGHTLY COOLER AS HIGH PRESSURE BUILDS IN FROM
ONTARIO CANADA INTO THE GREAT LAKES REGION.
LOOK FOR THE HIGH TO SLIDE INTO THE NORTHEAST U.S. SUNDAY NIGHT AS
LOW PRESSURE PUSHES OUT OF THE INTERMOUNTAIN WEST INTO THE NORTHERN
PLAINS. THIS PUSHES A WARM FRONT INTO MN/IA AFTER MIDNIGHT WITH
INCREASING 850MB MOISTURE TRANSPORT NOSING INTO THE AREA FOR A
CHANCE OF SHOWERS AND THUNDERSTORMS. SHOWER AND THUNDERSTORM CHANCES
CONTINUE THROUGH MONDAY AS THE WARM FRONT PUSHES THROUGH THE AREA.
WILL HAVE TO WATCH FOR A SEVERE THREAT DURING THIS TIME FRAMES AS
WELL WITH THE GFS INDICATING 1000-1500J/KG 0-1KM MLCAPE WITH AROUND
35KT OF 0-3KM SHEAR SUNDAY NIGHT AND 2000-2500J/KG AND 25-30KT 0-3KM
SHEAR ON MONDAY. PLAN ON HIGHS IN THE MID 70S/LOWER 80S ON
SUNDAY...AND UPPER 70S/MIDDLE 80S MONDAY.
THE GFS AND ECMWF SHOW A COLD FRONT PUSHING INTO THE AREA MONDAY
NIGHT AND HANGING UP ACROSS THE AREA THROUGH WEDNESDAY FOR A
CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS. HIGHS TUESDAY ARE
EXPECTED TO TOP OFF AGAIN IN THE 80S...COOLING SLIGHTLY ON WEDNESDAY
INT THE UPPER 70S TO MIDDLE 80S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1207 PM CDT THU SEP 5 2013
THE MAIN PROBLEM CONCERNS THE STRATUS DECK AN HOW FAR WEST IT WILL
PROGRESS AND WHEN OR IF IT WILL DISSIPATE. THE 05.14Z RAP SUGGESTS
THIS MOISTURE FIELD WILL MIX OUT THIS AFTERNOON ALLOWING THE
CLOUDS TO BREAK UP AND THAT THIS WILL HAPPEN BEFORE THE CLOUDS
MOVE INTO KRST. THE 05.12Z NAM HANGS ON TO THE MOISTURE FIELD
THROUGH THE ENTIRE PERIOD...SUGGESTING THE CLOUDS WILL PERSIST
INTO TONIGHT BEFORE GETTING LIFTED NORTH OF THE AREA ON THE
BACKSIDE OF THE RIDGE AXIS. LOOKING AT THE LAST FEW SATELLITE
IMAGES...THE AREA OF CLOUDS HAS ESSENTIALLY STOPPED ITS WESTWARD
ADVANCE AND NOW APPEARS TO BE SHRINKING ON THE EAST SIDE AS WELL.
THUS WILL FOLLOW THE RAP TRENDS AND NOT BRING THE CLOUDS INTO
KRST AND SHOW THEM SCATTERING OUT AT KLSE BY MID AFTERNOON. ONCE
THE CLOUDS ARE OUT OF THE WAY...THE HIGH WILL CONTINUE TO SLIDE
OFF TO THE EAST THROUGH THE REMAINDER OF THE PERIOD. THIS WILL
KEEP ENOUGH OF A GRADIENT THROUGH THE NIGHT TO HAVE SOUTHEAST
WINDS BETWEEN 5 AND 10 KNOTS. EXPECT THAT THIS WILL PRECLUDE THE
FORMATION OF ANY VALLEY FOG...BUT CANNOT TOTALLY RULE OUT A LITTLE
BIT OF MVFR FOG FOR A SHORT WHILE LATE TONIGHT INTO EARLY FRIDAY
MORNING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM...DAS
AVIATION...04