Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 230440
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1140 PM CDT TUE APR 22 2014

.UPDATE...
ISSUED AT 939 PM CDT TUE APR 22 2014

VERY GOOD RADIATIONAL COOLING SETUP HAS ALLOWED TEMPS TO PLUMMET WELL
DOWN INTO THE 40S IN SEVERAL LOCATIONS OVER EASTERN IA AND
NORTHWEST IL. MID CLOUDS ENCROACHING ON AREA FROM CENTRAL IA BUT
SLOWED AS 850 MB RIDGE AXIS ANALYZED OVER WESTERN CWA. EXPECT THE
CLOUDS TO SLOWLY SHIFT EWD OVERNIGHT HIGH PRESSURE SHIFTS GRADUALLY
EAST... BUT MOST OF NW IL WILL BE GENERALLY CLEAR MUCH OF THE
NIGHT. THIS SHOULD ALLOW TEMPS IN NW IL TO BOTTOM OUT IN THE L/M
30S WITH FROST...THUS HAVE ISSUED FROST ADVISORY MUCH OF NW IL WITH
GROWING SEASON FOR AREA PLANTS UNDERWAY. CANT RULE OUT ISOLD COLD
DRAINAGE SITES DROP INTO THE U20S NW IL. MIN TEMPS ELSEWHERE MORE
CHALLENGING AND HINGE ON TIMING OF CLOUDS. TRENDS SUGGEST CLOUDS
SLOWING WITH RISK OF FURTHER DELAY THUS HAVE LOWERED MINS 1-3 DEGS
MANY OTHER LOCATIONS... AND HAVE INTRODUCED PATCHY FROST OVER NE
AND ECNTRL IA ADJACENT TO THE ADVISORY. IF ANY DELTA...BELIEVE
COLDER BY 1-3 DEGS WITH POSSIBLY MORE FROST INTO FAR EASTERN IA BUT
TOO MUCH UNCERTAINTY WITH CLOUDS FOR ADVISORY IN THESE AREAS.

UPDATE ISSUED AT 748 PM CDT TUE APR 22 2014

UPDATED TO LOWER MINS 1-3 DEGS ESPECIALLY ALONG/E OF MISSISSIPPI
DUE TO DRY AIR AND SLOWER ARRIVAL OF CLOUDS. ALSO... ADDED
MENTION OF FROST NORTHWEST IL WHERE SOME MIN TEMPS APPEAR
DESTINED FOR THE LOWER 30S DEPENDING ON CLOUD TRENDS... AND MAY
NEED TO CONSIDER A FROST ADVISORY. HAVE UPDATED HAZARDOUS WEATHER
OUTLOOK TO ADD MENTION OF FROST.

&&

.SYNOPSIS...
ISSUED AT 315 PM CDT TUE APR 22 2014

DELIGHTFUL SPRING DAY IN PROGRESS WITH FULL SUNSHINE AND 3 PM
TEMPERATURES IN THE UPPER 50S TO LOWER 60S. NORTHWEST WINDS WERE
GUSTING OCCASIONALLY TO 20 TO 25 MPH AS A HIGH PRESSURE RIDGE
EXTENDED FROM MN TO TX.

WITH RIDGING SOUTHWARD TO THE SOUTHERN PLAINS GULF MOISTURE WAS
COMPLETELY CUT-OFF. THE HONORS GO TO THE KDVN SOUNDING AT 22/12Z
FOR HAVING THE LOWEST PRECIPITABLE WATER VALUE IN THE LOWER 48...
AT JUST 2 TENTHS OF AN INCH.

MEANWHILE...WATER VAPOR LOOPS SHOWED A SIGNIFICANT UPPER LEVEL TROUGH
PUSHING INLAND INTO THE WEST COAST. 500 MB HEIGHT FALLS OF 130 METERS
WAS NOTED.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 315 PM CDT TUE APR 22 2014

FORECAST FOCUS ON CHANCE OF RAIN WEDNESDAY.

TONIGHT...HIGH PRESSURE RIDGE WILL BE PUSHING SLOWLY TO OUR EAST.
CLEAR SKIES CAN BE EXPECTED FOR MUCH OF THE EVENING...AND SHOULD
REMAIN SO INTO THE OVERNIGHT HOURS EAST OF THE MS RIVER. WINDS
WILL ALSO BECOME LIGHT AND FROM THE EAST FOR LOCATIONS EAST OF
THE RIVER. FOR AREAS WEST OF THE MS RIVER WINDS WILL REMAIN ABOUT
10 TO 15 MPH MUCH OF THE NIGHT AND MID/HIGH LEVEL CLOUDS WILL ALSO
INCREASE OVERNIGHT...AS LOW PRESSURE PUSHES INTO THE WESTERN HIGH
PLAINS BY MORNING. MINIMUM TEMPERATURES SHOULD RANGE FROM THE MID
TO UPPER 30S EAST TO THE LOWER 40S WEST. A FEW LOCALIZED SPOTS MAY
DIP TO THE LOWER 30S IN THE ROCK RIVER VALLEY.

WEDNESDAY...I LIKE THE DEPICTION OF THE SREF MODEL WITH THE NICE WARM
ADVECTION WING OF SHOWERS/ISOLATED THUNDERSTORMS THAT DEVELOPS ACROSS
OUR NORTHERN CWA...ESPECIALLY FROM LATE MORNING THROUGH THE AFTERNOON.
LOW PRESSURE AND A COLD FRONT WILL EMERGE INTO THE PLAINS WITH A
WARM FRONT LIFTING INTO THE CWA. WESTERN GULF MOISTURE IS JUST
BEGINNING TO GET PULLED INTO THE PLAINS BUT ACROSS THE DVN CWA THE
LOW LEVELS OF THE ATMOSPHERE WILL STILL BE QUITE DRY. THEREFORE...ANY
SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WILL BE HIGH
BASED AND ALONG AND NORTH OF THE WARM FRONT. FOR NOW WILL KEEP
POPS IN THE 30-40 PERCENT RANGE IN OUR NORTHERN COUNTIES. EXTENSIVE
MID/HIGH LEVEL CLOUDINESS IN CONJUNCTION WITH SOUTHEAST WINDS
SHOULD KEEP TEMPERATURES SEVERAL DEGREES COOLER THAN TODAY...MAINLY
IN OUR NORTHERN CWA. I WILL FORECAST HIGHS IN THE MID 50S NORTH TO
THE MID 60S SOUTH. TEMPERATURES ARE ACTUALLY SOMEWHAT OF A CHALLENGE
DUE TO THE EXACT LOCATION OF THE WARM FRONT AND IF THERE ARE ANY
BREAKS IN THE CLOUD COVER.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 315 PM CDT TUE APR 22 2014

INITIAL FORECAST FOCUS IS ON PCPN CHANCES WEDNESDAY NIGHT-THURSDAY
THEN ATTENTION TURNS TO COLDER TEMPERATURES OVER THE WEEKEND.
SIGNIFICANT LARGE SCALE MODEL DISCREPANCIES STILL REMAIN WITH THE
NEXT STORM SYSTEM DEVELOPING OUT WEST LATE IN THE WEEKEND.

WEDNESDAY NIGHT...LATEST MODEL RUNS SHOW THE POSSIBILITY OF
SOME LIGHT WAA TYPE PRECIP TRACKING ACROSS THE NORTH EARLY IN THE
PERIOD AS A WEAK SHORTWAVE MOVES OVER THE AREA. HOWEVER...GIVEN THAT
THE MODELS HAVE BEEN TOO MOIST IN THE LOW LEVELS THROUGH MANY EVENTS
THIS SPRING AND THAT WE WILL HAVE DRY AIR IN PLACE...OPTED TO ONLY
HAVE SLIGHT CHANCE TO CHANCE WORDING BEFORE 06Z THURSDAY. IF ANY
PCPN DOES FALL IT WILL BE VERY LIGHT.

THURSDAY...STRONG LOW LEVEL JET IN EXCESS OF 55 KTS...A THETA-E
RIDGE...STEEP LOW LEVEL LAPSE RATES...AND STRONG UPPER LEVEL
DIVERGENCE ALL SUGGEST SHOWERS AND THUNDERSTORMS DEVELOPING TO OUR
WEST OVER THE PLAINS LATE WEDNESDAY/EARLY THURSDAY ALONG AND AHEAD
OF A COLD FRONT. THIS FRONT TO PUSH THROUGH THE CWA DURING THE DAY
AND SHOULD BE EAST OF THE MS RVR BY EARLY EVENING WITH PCPN CHANCES
ENDING AS THE FRONT MOVES THROUGH. STRONG SOUTHERLY FLOW ADVECTING
IN H85 DEW POINTS IN THE 5 TO 10C RANGE ALONG WITH MODEL PWATS
INCREASING TO OVER AN INCH WILL RESULT IN A WIDESPREAD RAIN EVENT
WITH A FEW RUMBLES OF THUNDER NOT OUT OF THE QUESTION. QPF AMOUNTS AT
THIS TIME ARE EXPECTED IN THE THREE TENTHS TO HALF INCH RANGE.
STRONG TO SEVERE STORMS TO STAY TO OUR WEST AND SOUTH WHERE BETTER
INSTABILITY WILL BE LOCATED. IF ANY BREAKS IN THE CLOUDS CAN DEVELOP
TO ALLOW FURTHER DESTABILIZATION AHEAD OF THE FRONT...THEN A STRONG
STORM MAY BE POSSIBLE. HOWEVER...AM NOT ANTICIPATING THIS AT THIS
TIME. HIGH TEMPS A CHALLENGE DUE TO RAIN AND FOR NOW WILL GO WITH
UPPER 50S NORTH TO MIDDLE 60S IN THE FAR SOUTH.

FRIDAY...DRY CONDITIONS WILL BE SEEN AS WEAK HIGH PRESSURE MOVES
OVER THE REGION. TEMPERATURES TO AVERAGE SLIGHTLY ABOVE NORMAL.

REST OF EXTENDED...A MORE AMPLIFIED PATTERN DEVELOPS OVER THE WEEKEND
WITH A LARGE RIDGE OVER THE CENTRAL CONUS AND A DEEP TROUGH OVER THE
DESERT SOUTHWEST. LONG RANGE MODELS STILL HAVING A HARD TIME
RESOLVING HOW THE ENERGY IN THE TROUGH EJECTS OUT OF THE SOUTHWEST.
BOTH THE ECMWF/GFS NOW HAVE A CUT OFF LOW DEVELOPING EAST OF THE
ROCKIES SUNDAY MORNING BUT THE STRENGTH AND TRACK OF THIS LOW IS
STILL IN QUESTION. THE ECMWF NOW KEEPS THE UPPER LOW CUTOFF THROUGH
TUESDAY AND IS SLIGHTLY STRONGER THAN THE LATEST GFS RUN. AT
THE SURFACE...DIFFERENCES EXIST IN THE PLACEMENT OF A WARM FRONT
WHERE THE ECMWF HAS THE FRONT AS FAR NORTH AS HIGHWAY 20 SATURDAY
NIGHT WHEREAS THE GFS/GEM KEEP IT OVER SOUTHERN MISSOURI. MODEL
CONSENSUS LEANS TOWARDS THE GFS SOLUTION AND LEADS TO A COOL REGIME
OVER THE WEEKEND AND INTO NEXT WEEK. IF THE ECMWF VERIFIES THAN
HIGHS THAT ARE FORECAST MAINLY IN THE 50S WOULD BE TOO LOW. LOW
CONFIDENCE RAIN CHANCES RUN FROM SATURDAY NIGHT THROUGH MONDAY AS
SEVERAL SHORTWAVES TRACK THROUGH THE PLAINS. DETAILS AS TO WHAT
PERIODS HAVE A BETTER CHANCE OF RAIN WILL BE FURTHER RESOLVED ONCE
THE MODELS COME INTO AGREEMENT OF THE UPPER LOW TRACK AND THE PIECES
OF ENERGY ASSOCIATED WITH IT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1133 PM CDT TUE APR 22 2014

HIGH PRESSURE WILL MOVE INTO THE OHIO VLY WED AM WITH WINDS BLO 10
KTS SHIFTING FROM N TO E. WINDS WILL INCREASE 10-15 KTS FROM E/SE
ON WED WITH SOME LOCAL HIGHER GUSTS POSSIBLE WEST OF THE
MISSISSIPPI IN STRENGTHENING PRESSURE GRADIENT BETWEEN DEPARTING
HIGH IN OHIO VLY AND LOW PRESSURE EMERGING INTO THE PLAINS.
ENSUING WARM ADVECTION ALOFT TO RESULT IN BKN-OVC MID/HIGH CLOUDS
WED/WED EVE...WITH A CHANCE OF SHOWERS DEVELOPING MAINLY IN THE
AFTN/EVE.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...FROST ADVISORY FROM 3 AM TO 7 AM CDT WEDNESDAY FOR BUREAU-
     CARROLL-HENRY IL-JO DAVIESS-PUTNAM-STEPHENSON-WHITESIDE.

MO...NONE.
&&

$$

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





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