Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KDVN 251547
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1047 AM CDT FRI JUL 25 2014

.UPDATE...
ISSUED AT 1041 AM CDT FRI JUL 25 2014

THE CURRENT THUNDERSTORM COMPLEX CONTINUES TO SLOWLY DECAY AS IT
MOVES EAST OF THE MISSISSIPPI. A MESO HIGH OVER NORTHEAST IOWA IS
STARTING TO COLLAPSE WHICH IS CAUSING A PERIOD OF STRONG WINDS ON
THE BACK SIDE OF THE PRECIPITATION.

NEW CONVECTION HAS DEVELOPED ACROSS NORTHERN IOWA WHICH APPEARS TO
BE ASSOCIATED WITH A WEAK THETA E GRADIENT. RECENT RADAR TRENDS
SHOW SOME WEAKENING OF THIS CONVECTION.

THE RAIN WILL END FROM WEST TO EAST THROUGH MID DAY AS WARMER
TEMPERATURES BUILDS IN ALOFT. THE POTENTIAL FOR CONVECTION WILL
HAVE TO BE RE-EVALUATED FOR THE AFTERNOON HOURS.

UPDATE ISSUED AT 700 AM CDT FRI JUL 25 2014

MCS OVER THE DVN CWA EARLY THIS MORNING WITH LOCALLY HEAVY RAINFALL
IN THE SOME OF THE STRONGER STORMS. IR SATELLITE SHOWED WARMING
TOPS IN OUR NORTHERN CWA WHICH ALSO IS INDICATED ON DOPPLER RADAR
WITH A WEAKENING TREND. THE ENTIRE MCS WILL GRADUALLY WEAKEN AS IT
PUSHES SOUTHEAST THIS MORNING AND THE HRRR MESO MODEL SHOWS THE BACK
EDGE OF THE MCS EXITING OUR SE CWA BY 1 PM. MANY AREAS SHOULD PICK
UP 1/4 TO 1/2 INCH OF RAIN WITH ISOLATED 1 INCH POSSIBLE.

&&

.SYNOPSIS...
ISSUED AT 345 AM CDT FRI JUL 25 2014

ELEVATED CONVECTION HAS FIRED IN THE PAST FEW HOURS ACROSS PORTIONS
OF NORTHERN/CENTRAL IA AND INTO WESTERN/SOUTHERN MN. THIS IS OCCURRING
ON THE NOSE OF A 50+ KNOT LOW LEVEL JET ON THE EASTERN EDGE OF A CAPPED
ELEVATED MIXED LAYER. SPC MESO ANALYSIS SHOWS THE BETTER MOISTURE
TRANSPORT IS STILL WEST OF THE DVN CWA WITH THE HIGHEST BULK SHEAR
VALUES IN SOUTHERN MN. PRECIPITABLE WATERS RANGE FROM 2.10 INCHES
IN WESTERN IA TO LESS THAN AN INCH IN NORTHERN IL. IR SATELLITE
LOOPS INDICATE TOPS CONTINUE TO RAPIDLY COOL AS THE THUNDERSTORM
ACTIVITY MOVES SOUTHEAST. A SHORT WAVE TROUGH WAS ALSO LIFTING
EASTWARD ACROSS THE NORTHERN/CENTRAL PLAINS AROUND A CLOSED UPPER
LOW IN SOUTHERN ALBERTA.

A COOL/STABLE SURFACE LAYER WAS NOTED ACROSS THE DVN CWA WITH 3 AM
TEMPERATURES IN THE MID 50S TO MID 60S...WHILE READINGS WERE WELL
INTO THE 70S TO LOWER 80S IN THE CENTRAL/SOUTHERN PLAINS.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 345 AM CDT FRI JUL 25 2014

FORECAST FOCUS ON THUNDERSTORMS MAINLY THIS MORNING AND TEMPERATURES.

TODAY...FORCING AND RAPIDLY INCREASING MOISTURE WILL ALLOW THUNDERSTORMS
TO CONTINUE TO DEVELOP/SPREAD ACROSS MUCH OF THE CWA THIS MORNING ON
THE NOSE OF THE STRONG LOW LEVEL JET...AS IT VEERS INTO THE AREA. DUE
TO THE ELEVATED NATURE OF THE STORMS AND THE COOL/STABLE SURFACE ENVIRONMENT
SEVERE WEATHER IS NOT EXPECTED. FREEZING LEVELS ARE QUITE HIGH AT NEARLY
15K FT. HOWEVER...SOME OF THE STRONGER STORMS MAY PRODUCE FREQUENT LIGHTNING...
SUB-SEVERE HAIL AND LOCALLY HEAVY RAINFALL. LATER THIS MORNING THE LOW
LEVEL JET WILL WEAKEN CONSIDERABLY ALONG WITH THE PASSAGE OF THE SHORT
WAVE TROUGH. A STRENGTHENING CAP WILL ALSO SPREAD EASTWARD INTO THE
CWA. THIS WILL DIMINISH OR END THE THUNDERSTORM ACTIVITY BY AFTERNOON
SO WILL HAVE LIKELY TO CATEGORICAL POPS THIS MORNING AND ONLY SMALL
POPS THIS AFTERNOON. EXPECTING EXTENSIVE CLOUD COVER TO LINGER INTO
THE AFTERNOON ESPECIALLY IN OUR EAST WHILE MORE SUNSHINE DEVELOPS IN
OUR WEST. MODELS REALLY SURGE THE WARM 850 MB TEMPERATURES INTO OUR
WESTERN CWA WITH +20C NOTED LATER IN THE AFTERNOON. I WILL FORECAST
MAXIMUM TEMPERATURES RANGING FROM THE MID 80S SW TO THE MID 70S NE.
HOWEVER...DEPENDING ON AMOUNT OF LINGERING CLOUDS (OR LACK OF) THIS
AFTERNOON THESE READINGS MAY NEED TO BE RE-VISITED.

TONIGHT...STRONG CAPPING ENVIRONMENT OVERSPREADS THE CWA EXCEPT
POSSIBLY OUR FAR EASTERN CWA. MODELS INSIST ON DEVELOPING CONVECTION
IN OUR EASTERN CWA AS THE LOW LEVEL JET STRENGTHENS AGAIN...BUT THERE
IS THE POTENTIAL THE STORMS MAY END UP FIRING EAST OF THE DVN CWA.
WILL HAVE CHANCE POPS TO COVER THIS SCENARIO BUT CONFIDENCE IS RATHER
LOW AT THIS POINT. THIS WILL BE A WARMER NIGHT WITH MINIMUM TEMPERATURES
IN THE MID 60S TO LOWER 70S.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 345 AM CDT FRI JUL 25 2014

CHANCES FOR SHOWERS AND STORMS THROUGH THE WEEKEND THEN MAINLY DRY AND
COOLER MUCH OF NEXT WEEK.

SAT-SAT NGT...COVERAGE OF STORMS AND SEVERE POTENTIAL ARE THE MAIN
CHALLENGES. MODEL SOUNDINGS GENERALLY SHOW DECENT ELEVATED MIXED
LAYER OR CAP DEVELOPING OVER MUCH OF THE AREA SUPPRESSING CONVECTION
FOR MUCH OF THE DAY. THIS WILL ALSO SPELL VERY WARM AND HUMID
CONDITIONS WITH HIGHS MID 80S TO NEAR 90F AND DEWPTS UPPER 60S TO
LOWER 70S FOR PM HEAT INDICES FROM NEAR 90 NORTH TO AROUND 100 SOUTH.
SEVERAL FCST SOUNDINGS THOUGH SHOW THE CAP WEAKENING AFTER 20-21Z
WITH PASSAGE OF SFC-850 MB COOL FRONTS AND THEREFORE WOULD ANTICIPATE
INCREASING STORM COVERAGE BY LATE AFTN/EVE MAINLY SOUTH OF I-80
VICINITY OF FRONT AND ELEVATED CONVERGENCE AND MOISTURE ADVECTION ON
NOSE OF INCREASING SWLY LOW LEVEL JET. A FEW SEVERE STORMS POSSIBLE
GIVEN MODERATE TO STRONG INSTABILITY (SBCAPE 2500-3500 J/KG) AND
SHEAR (0-6KM 35-50 KTS). MAIN THREAT BEING DAMAGING WINDS WITH LARGE
HAIL RISK SECONDARY AND CONFINED TO SUPERCELLS OR DECENT MESOCYCLONES
GIVEN ABUNDANCE OF MOISTURE IN ATMOSPHERIC COLUMN CHARACTERIZED BY
PWATS OF 1.6-1.9 INCHES AND WARM CLOUD DEPTHS UP AROUND 13KFT AGL...
WHICH POSES RISK OF LOCALLY HEAVY RAIN OF 2+ INCHES WITH POTENTIAL
FOR BACKBUILDING AND ISOLATED HIGHER AMOUNTS WITH VEERED SWLY LOW LEVEL
JET.

SUN-SUN NGT...DIGGING PV ANOMALY FROM UPPER MIDWEST INTO GREAT LAKES
TO USHER IN SECONDARY AND STRONGER COOL FRONT SUNDAY PM. WILL SEE
CHANCES FOR ADDITIONAL SHOWERS AND STORMS MAINLY DURING THE PM INTO
EARLY EVE WITH THIS FRONT WITH BEST CHANCES OVER NORTHEAST 1/3-1/2 OF THE
CWA. NAM AND GFS SHOWING 40-50 KTS OF 0-6KM BULK SHEAR AND WITH
INVERTED V SOUNDINGS AND DRIER AIR ALOFT WILL NEED TO WATCH FOR POTENTIAL
OF MORE ORGANIZED AND STRONGER STORMS CONTAINING GUSTY WINDS AND HAIL.
SUNDAY LOOKS TO BE THE LAST WARM DAY FOR A WHILE... WHICH OF LATE MEANS
LAST DAY AROUND NORMAL.

MON-THU...MEDIUM RANGE MODELS AND ENSEMBLES IN GOOD AGREEMENT WITH THE
OVERALL PATTERN DEPICTING A DEEP UPPER TROUGH OVER THE EASTERN HALF OF THE
CONUS. THIS WILL RESULT IN ANOTHER PERIOD OF GENERALLY BELOW NORMAL
TEMPS...WHICH MAY FEATURE A MORNING OR TWO OF NEAR RECORD LOWS TUE-WED.
CHALLENGE ASIDE FROM TEMPS WILL BE WHETHER ANY PM SHOWER CHANCES EXIST
WITH THE COOLER AIR ALOFT AND ANY IMPULSES IN NORTHWEST FLOW... BUT TOO
FAR OUT AND PROBS APPEAR TOO LOW FOR MUCH MENTION OF PCPN UNTIL POSSIBLY
LATE WEEK AHEAD OF POTENTIALLY ANOTHER SHOT OF COOLER AIR BEYOND THE
SCOPE OF THE CURRENT EXTENDED.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 700 AM CDT FRI JUL 25 2014

SHOWERS AND THUNDERSTORMS WILL BE OVER THE TAF SITES THIS MORNING
WITH BRIEF MVFR CIGS/VIS OTHERWISE MAINLY VFR CONDS THROUGH TONIGHT.
SOUTH WINDS 10 TO 20 KNOTS TODAY THEN AROUND 10 KNOTS TONIGHT.


&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

UPDATE...08
SYNOPSIS...HAASE
SHORT TERM...HAASE
LONG TERM...05
AVIATION...HAASE





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.